From c9822fad8038870bb690543539c8e9ad5213b12f Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:14 +0100 Subject: [PATCH 01/75] libfs: allow to specify s_d_flags Make it possible for pseudo filesystems to specify default dentry flags. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-1-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- fs/libfs.c | 1 + include/linux/pseudo_fs.h | 1 + 2 files changed, 2 insertions(+) diff --git a/fs/libfs.c b/fs/libfs.c index ce8c496a6940..4bb4d8a313e7 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -680,6 +680,7 @@ static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc) s->s_export_op = ctx->eops; s->s_xattr = ctx->xattr; s->s_time_gran = 1; + s->s_d_flags |= ctx->s_d_flags; root = new_inode(s); if (!root) return -ENOMEM; diff --git a/include/linux/pseudo_fs.h b/include/linux/pseudo_fs.h index 2503f7625d65..a651e60d9410 100644 --- a/include/linux/pseudo_fs.h +++ b/include/linux/pseudo_fs.h @@ -9,6 +9,7 @@ struct pseudo_fs_context { const struct xattr_handler * const *xattr; const struct dentry_operations *dops; unsigned long magic; + unsigned int s_d_flags; }; struct pseudo_fs_context *init_pseudo(struct fs_context *fc, From 1e9a9be249ad4cd43ba155ea7e2ed06f15d38eab Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:15 +0100 Subject: [PATCH 02/75] nsfs: use inode_just_drop() Currently nsfs uses the default inode_generic_drop() fallback which drops the inode when it's unlinked or when it's unhashed. Since nsfs never hashes inodes that always amounts to dropping the inode. But that's just annoying to have to reason through every time we look at this code. Switch to inode_just_drop() which always drops the inode explicitly. This also aligns the behavior with pidfs which does the same. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-2-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- fs/nsfs.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/nsfs.c b/fs/nsfs.c index 79b026a36fb6..ded833f66d4d 100644 --- a/fs/nsfs.c +++ b/fs/nsfs.c @@ -408,6 +408,7 @@ static const struct super_operations nsfs_ops = { .statfs = simple_statfs, .evict_inode = nsfs_evict, .show_path = nsfs_show_path, + .drop_inode = inode_just_drop, }; static int nsfs_init_inode(struct inode *inode, void *data) From 6dbe134e4bf775572c87aba5a39654c0dbd875a4 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:16 +0100 Subject: [PATCH 03/75] nsfs: raise DCACHE_DONTCACHE explicitly While nsfs dentries are never hashed and thus retain_dentry() will never consider them for placing them on the LRU it isn't great to always have to go and remember that. Raise DCACHE_DONTCACHE explicitly as a visual marker that dentries aren't kept but freed immediately instead. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-3-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- fs/nsfs.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/nsfs.c b/fs/nsfs.c index ded833f66d4d..c1661feaccf0 100644 --- a/fs/nsfs.c +++ b/fs/nsfs.c @@ -591,6 +591,7 @@ static int nsfs_init_fs_context(struct fs_context *fc) struct pseudo_fs_context *ctx = init_pseudo(fc, NSFS_MAGIC); if (!ctx) return -ENOMEM; + ctx->s_d_flags |= DCACHE_DONTCACHE; ctx->ops = &nsfs_ops; ctx->eops = &nsfs_export_operations; ctx->dops = &ns_dentry_operations; From b21cba8d8719881d7a9c8b746bc932be881af4c8 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:17 +0100 Subject: [PATCH 04/75] pidfs: raise DCACHE_DONTCACHE explicitly While pidfs dentries are never hashed and thus retain_dentry() will never consider them for placing them on the LRU it isn't great to always have to go and remember that. Raise DCACHE_DONTCACHE explicitly as a visual marker that dentries aren't kept but freed immediately instead. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-4-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- fs/pidfs.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/pidfs.c b/fs/pidfs.c index 0ef5b47d796a..db236427fc2c 100644 --- a/fs/pidfs.c +++ b/fs/pidfs.c @@ -1022,6 +1022,7 @@ static int pidfs_init_fs_context(struct fs_context *fc) fc->s_iflags |= SB_I_NOEXEC; fc->s_iflags |= SB_I_NODEV; + ctx->s_d_flags |= DCACHE_DONTCACHE; ctx->ops = &pidfs_sops; ctx->eops = &pidfs_export_operations; ctx->dops = &pidfs_dentry_operations; From 4af033dad67e30c9a48a7ab461012a42200ee51a Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:18 +0100 Subject: [PATCH 05/75] nsfs: raise SB_I_NODEV and SB_I_NOEXEC There's zero need for nsfs to allow device nodes or execution. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-5-2e6f823ebdc0@kernel.org Signed-off-by: Christian Brauner --- fs/nsfs.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/nsfs.c b/fs/nsfs.c index c1661feaccf0..8b53fd361177 100644 --- a/fs/nsfs.c +++ b/fs/nsfs.c @@ -591,6 +591,7 @@ static int nsfs_init_fs_context(struct fs_context *fc) struct pseudo_fs_context *ctx = init_pseudo(fc, NSFS_MAGIC); if (!ctx) return -ENOMEM; + fc->s_iflags |= SB_I_NOEXEC | SB_I_NODEV; ctx->s_d_flags |= DCACHE_DONTCACHE; ctx->ops = &nsfs_ops; ctx->eops = &nsfs_export_operations; From 768b1565d9d1e1eebf7567f477f7f46c05a98a4d Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:19 +0100 Subject: [PATCH 06/75] cgroup: add cgroup namespace to tree after owner is set Otherwise we trip VFS_WARN_ON_ONC() in __ns_tree_add_raw(). Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-6-2e6f823ebdc0@kernel.org Fixes: 7c6059398533 ("cgroup: support ns lookup") Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- kernel/cgroup/namespace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/cgroup/namespace.c b/kernel/cgroup/namespace.c index fdbe57578e68..db9617556dd7 100644 --- a/kernel/cgroup/namespace.c +++ b/kernel/cgroup/namespace.c @@ -30,7 +30,6 @@ static struct cgroup_namespace *alloc_cgroup_ns(void) ret = ns_common_init(new_ns); if (ret) return ERR_PTR(ret); - ns_tree_add(new_ns); return no_free_ptr(new_ns); } @@ -86,6 +85,7 @@ struct cgroup_namespace *copy_cgroup_ns(u64 flags, new_ns->ucounts = ucounts; new_ns->root_cset = cset; + ns_tree_add(new_ns); return new_ns; } From 36a304de2640fa15637fa95d2e79d23ad266ef68 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:20 +0100 Subject: [PATCH 07/75] nstree: simplify return node_to_ns() checks for NULL and the assert isn't really helpful and will have to be dropped later anyway. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-7-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- kernel/nstree.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/kernel/nstree.c b/kernel/nstree.c index b24a320a11a6..369fd1675c6a 100644 --- a/kernel/nstree.c +++ b/kernel/nstree.c @@ -194,11 +194,6 @@ struct ns_common *ns_tree_lookup_rcu(u64 ns_id, int ns_type) break; } while (read_seqretry(&ns_tree->ns_tree_lock, seq)); - if (!node) - return NULL; - - VFS_WARN_ON_ONCE(node_to_ns(node)->ns_type != ns_type); - return node_to_ns(node); } From 8627bc8c7d815d929ad59407e13458b564870acf Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Mon, 3 Nov 2025 17:34:18 +0100 Subject: [PATCH 08/75] ns: add missing authorship I authored the files a short while ago. Signed-off-by: Christian Brauner --- include/linux/nstree.h | 1 + kernel/nscommon.c | 1 + kernel/nstree.c | 1 + 3 files changed, 3 insertions(+) diff --git a/include/linux/nstree.h b/include/linux/nstree.h index 8b8636690473..43aa262c0ea1 100644 --- a/include/linux/nstree.h +++ b/include/linux/nstree.h @@ -1,4 +1,5 @@ /* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (c) 2025 Christian Brauner */ #ifndef _LINUX_NSTREE_H #define _LINUX_NSTREE_H diff --git a/kernel/nscommon.c b/kernel/nscommon.c index c1fb2bad6d72..238402b189f7 100644 --- a/kernel/nscommon.c +++ b/kernel/nscommon.c @@ -1,4 +1,5 @@ // SPDX-License-Identifier: GPL-2.0-only +/* Copyright (c) 2025 Christian Brauner */ #include #include diff --git a/kernel/nstree.c b/kernel/nstree.c index 369fd1675c6a..4eabab5fceaf 100644 --- a/kernel/nstree.c +++ b/kernel/nstree.c @@ -1,4 +1,5 @@ // SPDX-License-Identifier: GPL-2.0-only +/* Copyright (c) 2025 Christian Brauner */ #include #include From d915fe20e5cba4bd50e41e792a32dcddc7490e25 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Mon, 3 Nov 2025 16:10:10 +0100 Subject: [PATCH 09/75] ns: add NS_COMMON_INIT() Add an initializer that can be used for the ns common initialization for static namespace such as most init namespaces. Suggested-by: Thomas Gleixner Link: https://patch.msgid.link/87ecqhy2y5.ffs@tglx Signed-off-by: Christian Brauner --- include/linux/ns_common.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h index f5b68b8abb54..3a72c3f81eca 100644 --- a/include/linux/ns_common.h +++ b/include/linux/ns_common.h @@ -119,6 +119,16 @@ void __ns_common_free(struct ns_common *ns); struct user_namespace *: CLONE_NEWUSER, \ struct uts_namespace *: CLONE_NEWUTS) +#define NS_COMMON_INIT(nsname, refs) \ +{ \ + .ns_type = ns_common_type(&nsname), \ + .ns_id = 0, \ + .inum = ns_init_inum(&nsname), \ + .ops = to_ns_operations(&nsname), \ + .stashed = NULL, \ + .__ns_ref = REFCOUNT_INIT(refs), \ +} + #define ns_common_init(__ns) \ __ns_common_init(to_ns_common(__ns), \ ns_common_type(__ns), \ From 0b1765830cf9c652f010e9f5df7d9fa435a2f930 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Mon, 3 Nov 2025 16:16:01 +0100 Subject: [PATCH 10/75] ns: use NS_COMMON_INIT() for all namespaces Now that we have a common initializer use it for all static namespaces. Signed-off-by: Christian Brauner --- fs/namespace.c | 5 +---- init/version-timestamp.c | 7 +------ ipc/msgutil.c | 7 +------ kernel/cgroup/cgroup.c | 5 +---- kernel/pid.c | 7 +------ kernel/time/namespace.c | 5 +---- kernel/user.c | 7 +------ 7 files changed, 7 insertions(+), 36 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index d82910f33dc4..7b78dd48b6c3 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -5985,11 +5985,8 @@ SYSCALL_DEFINE4(listmount, const struct mnt_id_req __user *, req, } struct mnt_namespace init_mnt_ns = { - .ns.inum = ns_init_inum(&init_mnt_ns), - .ns.ops = &mntns_operations, + .ns = NS_COMMON_INIT(init_mnt_ns, 1), .user_ns = &init_user_ns, - .ns.__ns_ref = REFCOUNT_INIT(1), - .ns.ns_type = ns_common_type(&init_mnt_ns), .passive = REFCOUNT_INIT(1), .mounts = RB_ROOT, .poll = __WAIT_QUEUE_HEAD_INITIALIZER(init_mnt_ns.poll), diff --git a/init/version-timestamp.c b/init/version-timestamp.c index d071835121c2..56ded64fdfe4 100644 --- a/init/version-timestamp.c +++ b/init/version-timestamp.c @@ -8,8 +8,7 @@ #include struct uts_namespace init_uts_ns = { - .ns.ns_type = ns_common_type(&init_uts_ns), - .ns.__ns_ref = REFCOUNT_INIT(2), + .ns = NS_COMMON_INIT(init_uts_ns, 2), .name = { .sysname = UTS_SYSNAME, .nodename = UTS_NODENAME, @@ -19,10 +18,6 @@ struct uts_namespace init_uts_ns = { .domainname = UTS_DOMAINNAME, }, .user_ns = &init_user_ns, - .ns.inum = ns_init_inum(&init_uts_ns), -#ifdef CONFIG_UTS_NS - .ns.ops = &utsns_operations, -#endif }; /* FIXED STRINGS! Don't touch! */ diff --git a/ipc/msgutil.c b/ipc/msgutil.c index 7a03f6d03de3..55a908ec0674 100644 --- a/ipc/msgutil.c +++ b/ipc/msgutil.c @@ -27,13 +27,8 @@ DEFINE_SPINLOCK(mq_lock); * and not CONFIG_IPC_NS. */ struct ipc_namespace init_ipc_ns = { - .ns.__ns_ref = REFCOUNT_INIT(1), + .ns = NS_COMMON_INIT(init_ipc_ns, 1), .user_ns = &init_user_ns, - .ns.inum = ns_init_inum(&init_ipc_ns), -#ifdef CONFIG_IPC_NS - .ns.ops = &ipcns_operations, -#endif - .ns.ns_type = ns_common_type(&init_ipc_ns), }; struct msg_msgseg { diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 6ae5f48cf64e..df8bfd26d502 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -250,12 +250,9 @@ bool cgroup_enable_per_threadgroup_rwsem __read_mostly; /* cgroup namespace for init task */ struct cgroup_namespace init_cgroup_ns = { - .ns.__ns_ref = REFCOUNT_INIT(2), + .ns = NS_COMMON_INIT(init_cgroup_ns, 2), .user_ns = &init_user_ns, - .ns.ops = &cgroupns_operations, - .ns.inum = ns_init_inum(&init_cgroup_ns), .root_cset = &init_css_set, - .ns.ns_type = ns_common_type(&init_cgroup_ns), }; static struct file_system_type cgroup2_fs_type; diff --git a/kernel/pid.c b/kernel/pid.c index 4fffec767a63..19d4599c136c 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -71,21 +71,16 @@ static int pid_max_max = PID_MAX_LIMIT; * the scheme scales to up to 4 million PIDs, runtime. */ struct pid_namespace init_pid_ns = { - .ns.__ns_ref = REFCOUNT_INIT(2), + .ns = NS_COMMON_INIT(init_pid_ns, 2), .idr = IDR_INIT(init_pid_ns.idr), .pid_allocated = PIDNS_ADDING, .level = 0, .child_reaper = &init_task, .user_ns = &init_user_ns, - .ns.inum = ns_init_inum(&init_pid_ns), -#ifdef CONFIG_PID_NS - .ns.ops = &pidns_operations, -#endif .pid_max = PID_MAX_DEFAULT, #if defined(CONFIG_SYSCTL) && defined(CONFIG_MEMFD_CREATE) .memfd_noexec_scope = MEMFD_NOEXEC_SCOPE_EXEC, #endif - .ns.ns_type = ns_common_type(&init_pid_ns), }; EXPORT_SYMBOL_GPL(init_pid_ns); diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c index 5b6997f4dc3d..19911f88e2b8 100644 --- a/kernel/time/namespace.c +++ b/kernel/time/namespace.c @@ -478,11 +478,8 @@ const struct proc_ns_operations timens_for_children_operations = { }; struct time_namespace init_time_ns = { - .ns.ns_type = ns_common_type(&init_time_ns), - .ns.__ns_ref = REFCOUNT_INIT(3), + .ns = NS_COMMON_INIT(init_time_ns, 3), .user_ns = &init_user_ns, - .ns.inum = ns_init_inum(&init_time_ns), - .ns.ops = &timens_operations, .frozen_offsets = true, }; diff --git a/kernel/user.c b/kernel/user.c index 0163665914c9..4b3132e786d9 100644 --- a/kernel/user.c +++ b/kernel/user.c @@ -35,6 +35,7 @@ EXPORT_SYMBOL_GPL(init_binfmt_misc); * and 1 for... ? */ struct user_namespace init_user_ns = { + .ns = NS_COMMON_INIT(init_user_ns, 3), .uid_map = { { .extent[0] = { @@ -65,14 +66,8 @@ struct user_namespace init_user_ns = { .nr_extents = 1, }, }, - .ns.ns_type = ns_common_type(&init_user_ns), - .ns.__ns_ref = REFCOUNT_INIT(3), .owner = GLOBAL_ROOT_UID, .group = GLOBAL_ROOT_GID, - .ns.inum = ns_init_inum(&init_user_ns), -#ifdef CONFIG_USER_NS - .ns.ops = &userns_operations, -#endif .flags = USERNS_INIT_FLAGS, #ifdef CONFIG_KEYS .keyring_name_list = LIST_HEAD_INIT(init_user_ns.keyring_name_list), From 3dd50c58664e2684bd610a57bf3ab713cbb0ea91 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:21 +0100 Subject: [PATCH 11/75] ns: initialize ns_list_node for initial namespaces Make sure that the list is always initialized for initial namespaces. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-8-2e6f823ebdc0@kernel.org Fixes: 885fc8ac0a4d ("nstree: make iterator generic") Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- include/linux/ns_common.h | 1 + 1 file changed, 1 insertion(+) diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h index 3a72c3f81eca..71a5e28344d1 100644 --- a/include/linux/ns_common.h +++ b/include/linux/ns_common.h @@ -127,6 +127,7 @@ void __ns_common_free(struct ns_common *ns); .ops = to_ns_operations(&nsname), \ .stashed = NULL, \ .__ns_ref = REFCOUNT_INIT(refs), \ + .ns_list_node = LIST_HEAD_INIT(nsname.ns.ns_list_node), \ } #define ns_common_init(__ns) \ From 6b053576edb12c7739ea9c7c9900031361922631 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:22 +0100 Subject: [PATCH 12/75] ns: add __ns_ref_read() Implement ns_ref_read() the same way as ns_ref_{get,put}(). No point in making that any more special or different from the other helpers. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-9-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- include/linux/ns_common.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h index 71a5e28344d1..5e09facafd93 100644 --- a/include/linux/ns_common.h +++ b/include/linux/ns_common.h @@ -154,7 +154,12 @@ static __always_inline __must_check bool __ns_ref_get(struct ns_common *ns) return refcount_inc_not_zero(&ns->__ns_ref); } -#define ns_ref_read(__ns) refcount_read(&to_ns_common((__ns))->__ns_ref) +static __always_inline __must_check int __ns_ref_read(const struct ns_common *ns) +{ + return refcount_read(&ns->__ns_ref); +} + +#define ns_ref_read(__ns) __ns_ref_read(to_ns_common((__ns))) #define ns_ref_inc(__ns) refcount_inc(&to_ns_common((__ns))->__ns_ref) #define ns_ref_get(__ns) __ns_ref_get(to_ns_common((__ns))) #define ns_ref_put(__ns) __ns_ref_put(to_ns_common((__ns))) From 4b06b70c8244b442d58ae0fb59870cf31fdb422e Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:23 +0100 Subject: [PATCH 13/75] ns: rename to exit_nsproxy_namespaces() The current naming is very misleading as this really isn't exiting all of the task's namespaces. It is only exiting the namespaces that hang of off nsproxy. Reflect that in the name. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-10-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- include/linux/nsproxy.h | 2 +- kernel/cgroup/cgroup.c | 6 +++--- kernel/exit.c | 2 +- kernel/fork.c | 2 +- kernel/nsproxy.c | 2 +- 5 files changed, 7 insertions(+), 7 deletions(-) diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h index bd118a187dec..538ba8dba184 100644 --- a/include/linux/nsproxy.h +++ b/include/linux/nsproxy.h @@ -93,7 +93,7 @@ static inline struct cred *nsset_cred(struct nsset *set) */ int copy_namespaces(u64 flags, struct task_struct *tsk); -void exit_task_namespaces(struct task_struct *tsk); +void exit_nsproxy_namespaces(struct task_struct *tsk); void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new); int exec_task_namespaces(void); void free_nsproxy(struct nsproxy *ns); diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index df8bfd26d502..b758a9dd7526 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -1519,9 +1519,9 @@ static struct cgroup *current_cgns_cgroup_dfl(void) } else { /* * NOTE: This function may be called from bpf_cgroup_from_id() - * on a task which has already passed exit_task_namespaces() and - * nsproxy == NULL. Fall back to cgrp_dfl_root which will make all - * cgroups visible for lookups. + * on a task which has already passed exit_nsproxy_namespaces() + * and nsproxy == NULL. Fall back to cgrp_dfl_root which will + * make all cgroups visible for lookups. */ return &cgrp_dfl_root.cgrp; } diff --git a/kernel/exit.c b/kernel/exit.c index 9f74e8f1c431..825998103520 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -962,7 +962,7 @@ void __noreturn do_exit(long code) exit_fs(tsk); if (group_dead) disassociate_ctty(1); - exit_task_namespaces(tsk); + exit_nsproxy_namespaces(tsk); exit_task_work(tsk); exit_thread(tsk); diff --git a/kernel/fork.c b/kernel/fork.c index 3da0f08615a9..0926bfe4b8df 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2453,7 +2453,7 @@ __latent_entropy struct task_struct *copy_process( if (p->io_context) exit_io_context(p); bad_fork_cleanup_namespaces: - exit_task_namespaces(p); + exit_nsproxy_namespaces(p); bad_fork_cleanup_mm: if (p->mm) { mm_clear_owner(p->mm, p); diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c index 19aa64ab08c8..6ce76a0278ab 100644 --- a/kernel/nsproxy.c +++ b/kernel/nsproxy.c @@ -241,7 +241,7 @@ void switch_task_namespaces(struct task_struct *p, struct nsproxy *new) put_nsproxy(ns); } -void exit_task_namespaces(struct task_struct *p) +void exit_nsproxy_namespaces(struct task_struct *p) { switch_task_namespaces(p, NULL); } From 3a18f809184bc5a1cfad7cde5b8b026e2ff61587 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:24 +0100 Subject: [PATCH 14/75] ns: add active reference count The namespace tree is, among other things, currently used to support file handles for namespaces. When a namespace is created it is placed on the namespace trees and when it is destroyed it is removed from the namespace trees. While a namespace is on the namespace trees with a valid reference count it is possible to reopen it through a namespace file handle. This is all fine but has some issues that should be addressed. On current kernels a namespace is visible to userspace in the following cases: (1) The namespace is in use by a task. (2) The namespace is persisted through a VFS object (namespace file descriptor or bind-mount). Note that (2) only cares about direct persistence of the namespace itself not indirectly via e.g., file->f_cred file references or similar. (3) The namespace is a hierarchical namespace type and is the parent of a single or multiple child namespaces. Case (3) is interesting because it is possible that a parent namespace might not fulfill any of (1) or (2), i.e., is invisible to userspace but it may still be resurrected through the NS_GET_PARENT ioctl(). Currently namespace file handles allow much broader access to namespaces than what is currently possible via (1)-(3). The reason is that namespaces may remain pinned for completely internal reasons yet are inaccessible to userspace. For example, a user namespace my remain pinned by get_cred() calls to stash the opener's credentials into file->f_cred. As it stands file handles allow to resurrect such a users namespace even though this should not be possible via (1)-(3). This is a fundamental uapi change that we shouldn't do if we don't have to. Consider the following insane case: Various architectures support the CONFIG_MMU_LAZY_TLB_REFCOUNT option which uses lazy TLB destruction. When this option is set a userspace task's struct mm_struct may be used for kernel threads such as the idle task and will only be destroyed once the cpu's runqueue switches back to another task. But because of ptrace() permission checks struct mm_struct stashes the user namespace of the task that struct mm_struct originally belonged to. The kernel thread will take a reference on the struct mm_struct and thus pin it. So on an idle system user namespaces can be persisted for arbitrary amounts of time which also means that they can be resurrected using namespace file handles. That makes no sense whatsoever. The problem is of course excarabted on large systems with a huge number of cpus. To handle this nicely we introduce an active reference count which tracks (1)-(3). This is easy to do as all of these things are already managed centrally. Only (1)-(3) will count towards the active reference count and only namespaces which are active may be opened via namespace file handles. The problem is that namespaces may be resurrected. Which means that they can become temporarily inactive and will be reactived some time later. Currently the only example of this is the SIOGCSKNS socket ioctl. The SIOCGSKNS ioctl allows to open a network namespace file descriptor based on a socket file descriptor. If a socket is tied to a network namespace that subsequently becomes inactive but that socket is persisted by another process in another network namespace (e.g., via SCM_RIGHTS of pidfd_getfd()) then the SIOCGSKNS ioctl will resurrect this network namespace. So calls to open_related_ns() and open_namespace() will end up resurrecting the corresponding namespace tree. Note that the active reference count does not regulate the lifetime of the namespace itself. This is still done by the normal reference count. The active reference count can only be elevated if the regular reference count is elevated. The active reference count also doesn't regulate the presence of a namespace on the namespace trees. It only regulates its visiblity to namespace file handles (and in later patches to listns()). A namespace remains on the namespace trees from creation until its actual destruction. This will allow the kernel to always reach any namespace trivially and it will also enable subsystems like bpf to walk the namespace lists on the system for tracing or general introspection purposes. Note that different namespaces have different visibility lifetimes on current kernels. While most namespace are immediately released when the last task using them exits, the user- and pid namespace are persisted and thus both remain accessible via /proc//ns/. The user namespace lifetime is aliged with struct cred and is only released through exit_creds(). However, it becomes inaccessible to userspace once the last task using it is reaped, i.e., when release_task() is called and all proc entries are flushed. Similarly, the pid namespace is also visible until the last task using it has been reaped and the associated pid numbers are freed. The active reference counts of the user- and pid namespace are decremented once the task is reaped. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-11-2e6f823ebdc0@kernel.org Signed-off-by: Christian Brauner --- fs/nsfs.c | 48 ++++++++- include/linux/ns_common.h | 141 ++++++++++++++++++++++++- include/linux/nsfs.h | 3 + include/linux/nsproxy.h | 3 + kernel/cred.c | 6 ++ kernel/exit.c | 1 + kernel/fork.c | 1 + kernel/nscommon.c | 214 +++++++++++++++++++++++++++++++++++++- kernel/nsproxy.c | 23 ++++ kernel/nstree.c | 8 ++ kernel/pid.c | 5 + 11 files changed, 449 insertions(+), 4 deletions(-) diff --git a/fs/nsfs.c b/fs/nsfs.c index 8b53fd361177..0c35e4e54711 100644 --- a/fs/nsfs.c +++ b/fs/nsfs.c @@ -58,6 +58,8 @@ const struct dentry_operations ns_dentry_operations = { static void nsfs_evict(struct inode *inode) { struct ns_common *ns = inode->i_private; + + __ns_ref_active_put(ns); clear_inode(inode); ns->ops->put(ns); } @@ -419,6 +421,16 @@ static int nsfs_init_inode(struct inode *inode, void *data) inode->i_mode |= S_IRUGO; inode->i_fop = &ns_file_operations; inode->i_ino = ns->inum; + + /* + * Bring the namespace subtree back to life if we have to. This + * can happen when e.g., all processes using a network namespace + * and all namespace files or namespace file bind-mounts have + * died but there are still sockets pinning it. The SIOCGSKNS + * ioctl on such a socket will resurrect the relevant namespace + * subtree. + */ + __ns_ref_active_resurrect(ns); return 0; } @@ -495,7 +507,17 @@ static struct dentry *nsfs_fh_to_dentry(struct super_block *sb, struct fid *fh, if (ns->inum != fid->ns_inum) return NULL; - if (!__ns_ref_get(ns)) + /* + * This is racy because we're not actually taking an + * active reference. IOW, it could happen that the + * namespace becomes inactive after this check. + * We don't care because nsfs_init_inode() will just + * resurrect the relevant namespace tree for us. If it + * has been active here we just allow it's resurrection. + * We could try to take an active reference here and + * then drop it again. But really, why bother. + */ + if (!ns_get_unless_inactive(ns)) return NULL; } @@ -615,3 +637,27 @@ void __init nsfs_init(void) nsfs_root_path.mnt = nsfs_mnt; nsfs_root_path.dentry = nsfs_mnt->mnt_root; } + +void nsproxy_ns_active_get(struct nsproxy *ns) +{ + ns_ref_active_get(ns->mnt_ns); + ns_ref_active_get(ns->uts_ns); + ns_ref_active_get(ns->ipc_ns); + ns_ref_active_get(ns->pid_ns_for_children); + ns_ref_active_get(ns->cgroup_ns); + ns_ref_active_get(ns->net_ns); + ns_ref_active_get(ns->time_ns); + ns_ref_active_get(ns->time_ns_for_children); +} + +void nsproxy_ns_active_put(struct nsproxy *ns) +{ + ns_ref_active_put(ns->mnt_ns); + ns_ref_active_put(ns->uts_ns); + ns_ref_active_put(ns->ipc_ns); + ns_ref_active_put(ns->pid_ns_for_children); + ns_ref_active_put(ns->cgroup_ns); + ns_ref_active_put(ns->net_ns); + ns_ref_active_put(ns->time_ns); + ns_ref_active_put(ns->time_ns_for_children); +} diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h index 5e09facafd93..bdd0df15ad9c 100644 --- a/include/linux/ns_common.h +++ b/include/linux/ns_common.h @@ -4,7 +4,9 @@ #include #include +#include #include +#include struct proc_ns_operations; @@ -37,6 +39,67 @@ extern const struct proc_ns_operations cgroupns_operations; extern const struct proc_ns_operations timens_operations; extern const struct proc_ns_operations timens_for_children_operations; +/* + * Namespace lifetimes are managed via a two-tier reference counting model: + * + * (1) __ns_ref (refcount_t): Main reference count tracking memory + * lifetime. Controls when the namespace structure itself is freed. + * It also pins the namespace on the namespace trees whereas (2) + * only regulates their visibility to userspace. + * + * (2) __ns_ref_active (atomic_t): Reference count tracking active users. + * Controls visibility of the namespace in the namespace trees. + * Any live task that uses the namespace (via nsproxy or cred) holds + * an active reference. Any open file descriptor or bind-mount of + * the namespace holds an active reference. Once all tasks have + * called exited their namespaces and all file descriptors and + * bind-mounts have been released the active reference count drops + * to zero and the namespace becomes inactive. IOW, the namespace + * cannot be listed or opened via file handles anymore. + * + * Note that it is valid to transition from active to inactive and + * back from inactive to active e.g., when resurrecting an inactive + * namespace tree via the SIOCGSKNS ioctl(). + * + * Relationship and lifecycle states: + * + * - Active (__ns_ref_active > 0): + * Namespace is actively used and visible to userspace. The namespace + * can be reopened via /proc//ns/, via namespace file + * handles, or discovered via listns(). + * + * - Inactive (__ns_ref_active == 0, __ns_ref > 0): + * No tasks are actively using the namespace and it isn't pinned by + * any bind-mounts or open file descriptors anymore. But the namespace + * is still kept alive by internal references. For example, the user + * namespace could be pinned by an open file through file->f_cred + * references when one of the now defunct tasks had opened a file and + * handed the file descriptor off to another process via a UNIX + * sockets. Such references keep the namespace structure alive through + * __ns_ref but will not hold an active reference. + * + * - Destroyed (__ns_ref == 0): + * No references remain. The namespace is removed from the tree and freed. + * + * State transitions: + * + * Active -> Inactive: + * When the last task using the namespace exits it drops its active + * references to all namespaces. However, user and pid namespaces + * remain accessible until the task has been reaped. + * + * Inactive -> Active: + * An inactive namespace tree might be resurrected due to e.g., the + * SIOCGSKNS ioctl() on a socket. + * + * Inactive -> Destroyed: + * When __ns_ref drops to zero the namespace is removed from the + * namespaces trees and the memory is freed (after RCU grace period). + * + * Initial namespaces: + * Boot-time namespaces (init_net, init_pid_ns, etc.) start with + * __ns_ref_active = 1 and remain active forever. + */ struct ns_common { u32 ns_type; struct dentry *stashed; @@ -48,6 +111,7 @@ struct ns_common { u64 ns_id; struct rb_node ns_tree_node; struct list_head ns_list_node; + atomic_t __ns_ref_active; /* do not use directly */ }; struct rcu_head ns_rcu; }; @@ -56,6 +120,13 @@ struct ns_common { int __ns_common_init(struct ns_common *ns, u32 ns_type, const struct proc_ns_operations *ops, int inum); void __ns_common_free(struct ns_common *ns); +static __always_inline bool is_initial_namespace(struct ns_common *ns) +{ + VFS_WARN_ON_ONCE(ns->inum == 0); + return unlikely(in_range(ns->inum, MNT_NS_INIT_INO, + IPC_NS_INIT_INO - MNT_NS_INIT_INO + 1)); +} + #define to_ns_common(__ns) \ _Generic((__ns), \ struct cgroup_namespace *: &(__ns)->ns, \ @@ -127,6 +198,7 @@ void __ns_common_free(struct ns_common *ns); .ops = to_ns_operations(&nsname), \ .stashed = NULL, \ .__ns_ref = REFCOUNT_INIT(refs), \ + .__ns_ref_active = ATOMIC_INIT(1), \ .ns_list_node = LIST_HEAD_INIT(nsname.ns.ns_list_node), \ } @@ -144,14 +216,26 @@ void __ns_common_free(struct ns_common *ns); #define ns_common_free(__ns) __ns_common_free(to_ns_common((__ns))) +static __always_inline __must_check int __ns_ref_active_read(const struct ns_common *ns) +{ + return atomic_read(&ns->__ns_ref_active); +} + static __always_inline __must_check bool __ns_ref_put(struct ns_common *ns) { - return refcount_dec_and_test(&ns->__ns_ref); + if (refcount_dec_and_test(&ns->__ns_ref)) { + VFS_WARN_ON_ONCE(__ns_ref_active_read(ns)); + return true; + } + return false; } static __always_inline __must_check bool __ns_ref_get(struct ns_common *ns) { - return refcount_inc_not_zero(&ns->__ns_ref); + if (refcount_inc_not_zero(&ns->__ns_ref)) + return true; + VFS_WARN_ON_ONCE(__ns_ref_active_read(ns)); + return false; } static __always_inline __must_check int __ns_ref_read(const struct ns_common *ns) @@ -166,4 +250,57 @@ static __always_inline __must_check int __ns_ref_read(const struct ns_common *ns #define ns_ref_put_and_lock(__ns, __lock) \ refcount_dec_and_lock(&to_ns_common((__ns))->__ns_ref, (__lock)) +#define ns_ref_active_read(__ns) \ + ((__ns) ? __ns_ref_active_read(to_ns_common(__ns)) : 0) + +void __ns_ref_active_get_owner(struct ns_common *ns); + +static __always_inline void __ns_ref_active_get(struct ns_common *ns) +{ + WARN_ON_ONCE(atomic_add_negative(1, &ns->__ns_ref_active)); + VFS_WARN_ON_ONCE(is_initial_namespace(ns) && __ns_ref_active_read(ns) <= 0); +} +#define ns_ref_active_get(__ns) \ + do { if (__ns) __ns_ref_active_get(to_ns_common(__ns)); } while (0) + +static __always_inline bool __ns_ref_active_get_not_zero(struct ns_common *ns) +{ + if (atomic_inc_not_zero(&ns->__ns_ref_active)) { + VFS_WARN_ON_ONCE(!__ns_ref_read(ns)); + return true; + } + return false; +} + +#define ns_ref_active_get_owner(__ns) \ + do { if (__ns) __ns_ref_active_get_owner(to_ns_common(__ns)); } while (0) + +void __ns_ref_active_put_owner(struct ns_common *ns); + +static __always_inline void __ns_ref_active_put(struct ns_common *ns) +{ + if (atomic_dec_and_test(&ns->__ns_ref_active)) { + VFS_WARN_ON_ONCE(is_initial_namespace(ns)); + VFS_WARN_ON_ONCE(!__ns_ref_read(ns)); + __ns_ref_active_put_owner(ns); + } +} +#define ns_ref_active_put(__ns) \ + do { if (__ns) __ns_ref_active_put(to_ns_common(__ns)); } while (0) + +static __always_inline struct ns_common *__must_check ns_get_unless_inactive(struct ns_common *ns) +{ + VFS_WARN_ON_ONCE(__ns_ref_active_read(ns) && !__ns_ref_read(ns)); + if (!__ns_ref_active_read(ns)) + return NULL; + if (!__ns_ref_get(ns)) + return NULL; + return ns; +} + +void __ns_ref_active_resurrect(struct ns_common *ns); + +#define ns_ref_active_resurrect(__ns) \ + do { if (__ns) __ns_ref_active_resurrect(to_ns_common(__ns)); } while (0) + #endif diff --git a/include/linux/nsfs.h b/include/linux/nsfs.h index e5a5fa83d36b..731b67fc2fec 100644 --- a/include/linux/nsfs.h +++ b/include/linux/nsfs.h @@ -37,4 +37,7 @@ void nsfs_init(void); #define current_in_namespace(__ns) (__current_namespace_from_type(__ns) == __ns) +void nsproxy_ns_active_get(struct nsproxy *ns); +void nsproxy_ns_active_put(struct nsproxy *ns); + #endif /* _LINUX_NSFS_H */ diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h index 538ba8dba184..ac825eddec59 100644 --- a/include/linux/nsproxy.h +++ b/include/linux/nsproxy.h @@ -93,7 +93,10 @@ static inline struct cred *nsset_cred(struct nsset *set) */ int copy_namespaces(u64 flags, struct task_struct *tsk); +void switch_cred_namespaces(const struct cred *old, const struct cred *new); void exit_nsproxy_namespaces(struct task_struct *tsk); +void get_cred_namespaces(struct task_struct *tsk); +void exit_cred_namespaces(struct task_struct *tsk); void switch_task_namespaces(struct task_struct *tsk, struct nsproxy *new); int exec_task_namespaces(void); void free_nsproxy(struct nsproxy *ns); diff --git a/kernel/cred.c b/kernel/cred.c index dbf6b687dc5c..a6e7f580df14 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -306,6 +306,7 @@ int copy_creds(struct task_struct *p, u64 clone_flags) kdebug("share_creds(%p{%ld})", p->cred, atomic_long_read(&p->cred->usage)); inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); + get_cred_namespaces(p); return 0; } @@ -343,6 +344,8 @@ int copy_creds(struct task_struct *p, u64 clone_flags) p->cred = p->real_cred = get_cred(new); inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); + get_cred_namespaces(p); + return 0; error_put: @@ -435,10 +438,13 @@ int commit_creds(struct cred *new) */ if (new->user != old->user || new->user_ns != old->user_ns) inc_rlimit_ucounts(new->ucounts, UCOUNT_RLIMIT_NPROC, 1); + rcu_assign_pointer(task->real_cred, new); rcu_assign_pointer(task->cred, new); if (new->user != old->user || new->user_ns != old->user_ns) dec_rlimit_ucounts(old->ucounts, UCOUNT_RLIMIT_NPROC, 1); + if (new->user_ns != old->user_ns) + switch_cred_namespaces(old, new); /* send notifications */ if (!uid_eq(new->uid, old->uid) || diff --git a/kernel/exit.c b/kernel/exit.c index 825998103520..988e16efd66b 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -291,6 +291,7 @@ void release_task(struct task_struct *p) write_unlock_irq(&tasklist_lock); /* @thread_pid can't go away until free_pids() below */ proc_flush_pid(thread_pid); + exit_cred_namespaces(p); add_device_randomness(&p->se.sum_exec_runtime, sizeof(p->se.sum_exec_runtime)); free_pids(post.pids); diff --git a/kernel/fork.c b/kernel/fork.c index 0926bfe4b8df..f1857672426e 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2487,6 +2487,7 @@ __latent_entropy struct task_struct *copy_process( delayacct_tsk_free(p); bad_fork_cleanup_count: dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1); + exit_cred_namespaces(p); exit_creds(p); bad_fork_free: WRITE_ONCE(p->__state, TASK_DEAD); diff --git a/kernel/nscommon.c b/kernel/nscommon.c index 238402b189f7..abd1ac1a2d02 100644 --- a/kernel/nscommon.c +++ b/kernel/nscommon.c @@ -3,6 +3,7 @@ #include #include +#include #include #ifdef CONFIG_DEBUG_VFS @@ -53,6 +54,8 @@ static void ns_debug(struct ns_common *ns, const struct proc_ns_operations *ops) int __ns_common_init(struct ns_common *ns, u32 ns_type, const struct proc_ns_operations *ops, int inum) { + int ret; + refcount_set(&ns->__ns_ref, 1); ns->stashed = NULL; ns->ops = ops; @@ -69,10 +72,219 @@ int __ns_common_init(struct ns_common *ns, u32 ns_type, const struct proc_ns_ope ns->inum = inum; return 0; } - return proc_alloc_inum(&ns->inum); + ret = proc_alloc_inum(&ns->inum); + if (ret) + return ret; + /* + * Tree ref starts at 0. It's incremented when namespace enters + * active use (installed in nsproxy) and decremented when all + * active uses are gone. Initial namespaces are always active. + */ + if (is_initial_namespace(ns)) + atomic_set(&ns->__ns_ref_active, 1); + else + atomic_set(&ns->__ns_ref_active, 0); + return 0; } void __ns_common_free(struct ns_common *ns) { proc_free_inum(ns->inum); } + +static struct ns_common *ns_owner(struct ns_common *ns) +{ + struct user_namespace *owner; + + if (unlikely(!ns->ops)) + return NULL; + VFS_WARN_ON_ONCE(!ns->ops->owner); + owner = ns->ops->owner(ns); + VFS_WARN_ON_ONCE(!owner && ns != to_ns_common(&init_user_ns)); + if (!owner) + return NULL; + /* Skip init_user_ns as it's always active */ + if (owner == &init_user_ns) + return NULL; + return to_ns_common(owner); +} + +void __ns_ref_active_get_owner(struct ns_common *ns) +{ + ns = ns_owner(ns); + if (ns) + WARN_ON_ONCE(atomic_add_negative(1, &ns->__ns_ref_active)); +} + +/* + * The active reference count works by having each namespace that gets + * created take a single active reference on its owning user namespace. + * That single reference is only released once the child namespace's + * active count itself goes down. + * + * A regular namespace tree might look as follow: + * Legend: + * + : adding active reference + * - : dropping active reference + * x : always active (initial namespace) + * + * + * net_ns pid_ns + * \ / + * + + + * user_ns1 (2) + * | + * ipc_ns | uts_ns + * \ | / + * + + + + * user_ns2 (3) + * | + * cgroup_ns | mnt_ns + * \ | / + * x x x + * init_user_ns (1) + * + * If both net_ns and pid_ns put their last active reference on + * themselves it will cascade to user_ns1 dropping its own active + * reference and dropping one active reference on user_ns2: + * + * net_ns pid_ns + * \ / + * - - + * user_ns1 (0) + * | + * ipc_ns | uts_ns + * \ | / + * + - + + * user_ns2 (2) + * | + * cgroup_ns | mnt_ns + * \ | / + * x x x + * init_user_ns (1) + * + * The iteration stops once we reach a namespace that still has active + * references. + */ +void __ns_ref_active_put_owner(struct ns_common *ns) +{ + for (;;) { + ns = ns_owner(ns); + if (!ns) + return; + if (!atomic_dec_and_test(&ns->__ns_ref_active)) + return; + } +} + +/* + * The active reference count works by having each namespace that gets + * created take a single active reference on its owning user namespace. + * That single reference is only released once the child namespace's + * active count itself goes down. This makes it possible to efficiently + * resurrect a namespace tree: + * + * A regular namespace tree might look as follow: + * Legend: + * + : adding active reference + * - : dropping active reference + * x : always active (initial namespace) + * + * + * net_ns pid_ns + * \ / + * + + + * user_ns1 (2) + * | + * ipc_ns | uts_ns + * \ | / + * + + + + * user_ns2 (3) + * | + * cgroup_ns | mnt_ns + * \ | / + * x x x + * init_user_ns (1) + * + * If both net_ns and pid_ns put their last active reference on + * themselves it will cascade to user_ns1 dropping its own active + * reference and dropping one active reference on user_ns2: + * + * net_ns pid_ns + * \ / + * - - + * user_ns1 (0) + * | + * ipc_ns | uts_ns + * \ | / + * + - + + * user_ns2 (2) + * | + * cgroup_ns | mnt_ns + * \ | / + * x x x + * init_user_ns (1) + * + * Assume the whole tree is dead but all namespaces are still active: + * + * net_ns pid_ns + * \ / + * - - + * user_ns1 (0) + * | + * ipc_ns | uts_ns + * \ | / + * - - - + * user_ns2 (0) + * | + * cgroup_ns | mnt_ns + * \ | / + * x x x + * init_user_ns (1) + * + * Now assume the net_ns gets resurrected (.e.g., via the SIOCGSKNS ioctl()): + * + * net_ns pid_ns + * \ / + * + - + * user_ns1 (0) + * | + * ipc_ns | uts_ns + * \ | / + * - + - + * user_ns2 (0) + * | + * cgroup_ns | mnt_ns + * \ | / + * x x x + * init_user_ns (1) + * + * If net_ns had a zero reference count and we bumped it we also need to + * take another reference on its owning user namespace. Similarly, if + * pid_ns had a zero reference count it also needs to take another + * reference on its owning user namespace. So both net_ns and pid_ns + * will each have their own reference on the owning user namespace. + * + * If the owning user namespace user_ns1 had a zero reference count then + * it also needs to take another reference on its owning user namespace + * and so on. + */ +void __ns_ref_active_resurrect(struct ns_common *ns) +{ + /* If we didn't resurrect the namespace we're done. */ + if (atomic_fetch_add(1, &ns->__ns_ref_active)) + return; + + /* + * We did resurrect it. Walk the ownership hierarchy upwards + * until we found an owning user namespace that is active. + */ + for (;;) { + ns = ns_owner(ns); + if (!ns) + return; + + if (atomic_fetch_add(1, &ns->__ns_ref_active)) + return; + } +} diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c index 6ce76a0278ab..94c2cfe0afa1 100644 --- a/kernel/nsproxy.c +++ b/kernel/nsproxy.c @@ -26,6 +26,7 @@ #include #include #include +#include static struct kmem_cache *nsproxy_cachep; @@ -179,12 +180,15 @@ int copy_namespaces(u64 flags, struct task_struct *tsk) if ((flags & CLONE_VM) == 0) timens_on_fork(new_ns, tsk); + nsproxy_ns_active_get(new_ns); tsk->nsproxy = new_ns; return 0; } void free_nsproxy(struct nsproxy *ns) { + nsproxy_ns_active_put(ns); + put_mnt_ns(ns->mnt_ns); put_uts_ns(ns->uts_ns); put_ipc_ns(ns->ipc_ns); @@ -232,6 +236,9 @@ void switch_task_namespaces(struct task_struct *p, struct nsproxy *new) might_sleep(); + if (new) + nsproxy_ns_active_get(new); + task_lock(p); ns = p->nsproxy; p->nsproxy = new; @@ -246,6 +253,22 @@ void exit_nsproxy_namespaces(struct task_struct *p) switch_task_namespaces(p, NULL); } +void switch_cred_namespaces(const struct cred *old, const struct cred *new) +{ + ns_ref_active_get(new->user_ns); + ns_ref_active_put(old->user_ns); +} + +void get_cred_namespaces(struct task_struct *tsk) +{ + ns_ref_active_get(tsk->real_cred->user_ns); +} + +void exit_cred_namespaces(struct task_struct *tsk) +{ + ns_ref_active_put(tsk->real_cred->user_ns); +} + int exec_task_namespaces(void) { struct task_struct *tsk = current; diff --git a/kernel/nstree.c b/kernel/nstree.c index 4eabab5fceaf..e2a537785128 100644 --- a/kernel/nstree.c +++ b/kernel/nstree.c @@ -123,6 +123,14 @@ void __ns_tree_add_raw(struct ns_common *ns, struct ns_tree *ns_tree) write_sequnlock(&ns_tree->ns_tree_lock); VFS_WARN_ON_ONCE(node); + + /* + * Take an active reference on the owner namespace. This ensures + * that the owner remains visible while any of its child namespaces + * are active. For init namespaces this is a no-op as ns_owner() + * returns NULL for namespaces owned by init_user_ns. + */ + __ns_ref_active_get_owner(ns); } void __ns_tree_remove(struct ns_common *ns, struct ns_tree *ns_tree) diff --git a/kernel/pid.c b/kernel/pid.c index 19d4599c136c..a5a63dc0a491 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -112,9 +112,13 @@ static void delayed_put_pid(struct rcu_head *rhp) void free_pid(struct pid *pid) { int i; + struct pid_namespace *active_ns; lockdep_assert_not_held(&tasklist_lock); + active_ns = pid->numbers[pid->level].ns; + ns_ref_active_put(active_ns); + spin_lock(&pidmap_lock); for (i = 0; i <= pid->level; i++) { struct upid *upid = pid->numbers + i; @@ -278,6 +282,7 @@ struct pid *alloc_pid(struct pid_namespace *ns, pid_t *set_tid, } spin_unlock(&pidmap_lock); idr_preload_end(); + ns_ref_active_get(ns); return pid; From 8895d2a3dbf49f23622ab8da9fb3909826edd6dc Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:25 +0100 Subject: [PATCH 15/75] ns: use anonymous struct to group list member Make it easier to spot that they belong together conceptually. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-12-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- include/linux/ns_common.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h index bdd0df15ad9c..32463203c824 100644 --- a/include/linux/ns_common.h +++ b/include/linux/ns_common.h @@ -109,8 +109,10 @@ struct ns_common { union { struct { u64 ns_id; - struct rb_node ns_tree_node; - struct list_head ns_list_node; + struct /* per type rbtree and list */ { + struct rb_node ns_tree_node; + struct list_head ns_list_node; + }; atomic_t __ns_ref_active; /* do not use directly */ }; struct rcu_head ns_rcu; From 2ccaebc686e9ef7e94b3a8d89706daed6e696667 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:26 +0100 Subject: [PATCH 16/75] nstree: introduce a unified tree This will allow userspace to lookup and stat a namespace simply by its identifier without having to know what type of namespace it is. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-13-2e6f823ebdc0@kernel.org Signed-off-by: Christian Brauner --- include/linux/ns_common.h | 3 ++ kernel/nscommon.c | 1 + kernel/nstree.c | 96 +++++++++++++++++++++++++++++---------- 3 files changed, 76 insertions(+), 24 deletions(-) diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h index 32463203c824..7a3c71b3a76f 100644 --- a/include/linux/ns_common.h +++ b/include/linux/ns_common.h @@ -109,6 +109,9 @@ struct ns_common { union { struct { u64 ns_id; + struct /* global namespace rbtree and list */ { + struct rb_node ns_unified_tree_node; + }; struct /* per type rbtree and list */ { struct rb_node ns_tree_node; struct list_head ns_list_node; diff --git a/kernel/nscommon.c b/kernel/nscommon.c index abd1ac1a2d02..17a6ea44f054 100644 --- a/kernel/nscommon.c +++ b/kernel/nscommon.c @@ -62,6 +62,7 @@ int __ns_common_init(struct ns_common *ns, u32 ns_type, const struct proc_ns_ope ns->ns_id = 0; ns->ns_type = ns_type; RB_CLEAR_NODE(&ns->ns_tree_node); + RB_CLEAR_NODE(&ns->ns_unified_tree_node); INIT_LIST_HEAD(&ns->ns_list_node); #ifdef CONFIG_DEBUG_VFS diff --git a/kernel/nstree.c b/kernel/nstree.c index e2a537785128..bbb34b46b01b 100644 --- a/kernel/nstree.c +++ b/kernel/nstree.c @@ -5,31 +5,30 @@ #include #include +static __cacheline_aligned_in_smp DEFINE_SEQLOCK(ns_tree_lock); +static struct rb_root ns_unified_tree = RB_ROOT; /* protected by ns_tree_lock */ + /** * struct ns_tree - Namespace tree * @ns_tree: Rbtree of namespaces of a particular type * @ns_list: Sequentially walkable list of all namespaces of this type - * @ns_tree_lock: Seqlock to protect the tree and list * @type: type of namespaces in this tree */ struct ns_tree { - struct rb_root ns_tree; - struct list_head ns_list; - seqlock_t ns_tree_lock; - int type; + struct rb_root ns_tree; + struct list_head ns_list; + int type; }; struct ns_tree mnt_ns_tree = { .ns_tree = RB_ROOT, .ns_list = LIST_HEAD_INIT(mnt_ns_tree.ns_list), - .ns_tree_lock = __SEQLOCK_UNLOCKED(mnt_ns_tree.ns_tree_lock), .type = CLONE_NEWNS, }; struct ns_tree net_ns_tree = { .ns_tree = RB_ROOT, .ns_list = LIST_HEAD_INIT(net_ns_tree.ns_list), - .ns_tree_lock = __SEQLOCK_UNLOCKED(net_ns_tree.ns_tree_lock), .type = CLONE_NEWNET, }; EXPORT_SYMBOL_GPL(net_ns_tree); @@ -37,42 +36,36 @@ EXPORT_SYMBOL_GPL(net_ns_tree); struct ns_tree uts_ns_tree = { .ns_tree = RB_ROOT, .ns_list = LIST_HEAD_INIT(uts_ns_tree.ns_list), - .ns_tree_lock = __SEQLOCK_UNLOCKED(uts_ns_tree.ns_tree_lock), .type = CLONE_NEWUTS, }; struct ns_tree user_ns_tree = { .ns_tree = RB_ROOT, .ns_list = LIST_HEAD_INIT(user_ns_tree.ns_list), - .ns_tree_lock = __SEQLOCK_UNLOCKED(user_ns_tree.ns_tree_lock), .type = CLONE_NEWUSER, }; struct ns_tree ipc_ns_tree = { .ns_tree = RB_ROOT, .ns_list = LIST_HEAD_INIT(ipc_ns_tree.ns_list), - .ns_tree_lock = __SEQLOCK_UNLOCKED(ipc_ns_tree.ns_tree_lock), .type = CLONE_NEWIPC, }; struct ns_tree pid_ns_tree = { .ns_tree = RB_ROOT, .ns_list = LIST_HEAD_INIT(pid_ns_tree.ns_list), - .ns_tree_lock = __SEQLOCK_UNLOCKED(pid_ns_tree.ns_tree_lock), .type = CLONE_NEWPID, }; struct ns_tree cgroup_ns_tree = { .ns_tree = RB_ROOT, .ns_list = LIST_HEAD_INIT(cgroup_ns_tree.ns_list), - .ns_tree_lock = __SEQLOCK_UNLOCKED(cgroup_ns_tree.ns_tree_lock), .type = CLONE_NEWCGROUP, }; struct ns_tree time_ns_tree = { .ns_tree = RB_ROOT, .ns_list = LIST_HEAD_INIT(time_ns_tree.ns_list), - .ns_tree_lock = __SEQLOCK_UNLOCKED(time_ns_tree.ns_tree_lock), .type = CLONE_NEWTIME, }; @@ -85,6 +78,13 @@ static inline struct ns_common *node_to_ns(const struct rb_node *node) return rb_entry(node, struct ns_common, ns_tree_node); } +static inline struct ns_common *node_to_ns_unified(const struct rb_node *node) +{ + if (!node) + return NULL; + return rb_entry(node, struct ns_common, ns_unified_tree_node); +} + static inline int ns_cmp(struct rb_node *a, const struct rb_node *b) { struct ns_common *ns_a = node_to_ns(a); @@ -99,15 +99,27 @@ static inline int ns_cmp(struct rb_node *a, const struct rb_node *b) return 0; } +static inline int ns_cmp_unified(struct rb_node *a, const struct rb_node *b) +{ + struct ns_common *ns_a = node_to_ns_unified(a); + struct ns_common *ns_b = node_to_ns_unified(b); + u64 ns_id_a = ns_a->ns_id; + u64 ns_id_b = ns_b->ns_id; + + if (ns_id_a < ns_id_b) + return -1; + if (ns_id_a > ns_id_b) + return 1; + return 0; +} + void __ns_tree_add_raw(struct ns_common *ns, struct ns_tree *ns_tree) { struct rb_node *node, *prev; VFS_WARN_ON_ONCE(!ns->ns_id); - write_seqlock(&ns_tree->ns_tree_lock); - - VFS_WARN_ON_ONCE(ns->ns_type != ns_tree->type); + write_seqlock(&ns_tree_lock); node = rb_find_add_rcu(&ns->ns_tree_node, &ns_tree->ns_tree, ns_cmp); /* @@ -120,7 +132,8 @@ void __ns_tree_add_raw(struct ns_common *ns, struct ns_tree *ns_tree) else list_add_rcu(&ns->ns_list_node, &node_to_ns(prev)->ns_list_node); - write_sequnlock(&ns_tree->ns_tree_lock); + rb_find_add_rcu(&ns->ns_unified_tree_node, &ns_unified_tree, ns_cmp_unified); + write_sequnlock(&ns_tree_lock); VFS_WARN_ON_ONCE(node); @@ -139,11 +152,12 @@ void __ns_tree_remove(struct ns_common *ns, struct ns_tree *ns_tree) VFS_WARN_ON_ONCE(list_empty(&ns->ns_list_node)); VFS_WARN_ON_ONCE(ns->ns_type != ns_tree->type); - write_seqlock(&ns_tree->ns_tree_lock); + write_seqlock(&ns_tree_lock); rb_erase(&ns->ns_tree_node, &ns_tree->ns_tree); + rb_erase(&ns->ns_unified_tree_node, &ns_unified_tree); list_bidir_del_rcu(&ns->ns_list_node); RB_CLEAR_NODE(&ns->ns_tree_node); - write_sequnlock(&ns_tree->ns_tree_lock); + write_sequnlock(&ns_tree_lock); } EXPORT_SYMBOL_GPL(__ns_tree_remove); @@ -159,6 +173,17 @@ static int ns_find(const void *key, const struct rb_node *node) return 0; } +static int ns_find_unified(const void *key, const struct rb_node *node) +{ + const u64 ns_id = *(u64 *)key; + const struct ns_common *ns = node_to_ns_unified(node); + + if (ns_id < ns->ns_id) + return -1; + if (ns_id > ns->ns_id) + return 1; + return 0; +} static struct ns_tree *ns_tree_from_type(int ns_type) { @@ -184,28 +209,51 @@ static struct ns_tree *ns_tree_from_type(int ns_type) return NULL; } -struct ns_common *ns_tree_lookup_rcu(u64 ns_id, int ns_type) +static struct ns_common *__ns_unified_tree_lookup_rcu(u64 ns_id) +{ + struct rb_node *node; + unsigned int seq; + + do { + seq = read_seqbegin(&ns_tree_lock); + node = rb_find_rcu(&ns_id, &ns_unified_tree, ns_find_unified); + if (node) + break; + } while (read_seqretry(&ns_tree_lock, seq)); + + return node_to_ns_unified(node); +} + +static struct ns_common *__ns_tree_lookup_rcu(u64 ns_id, int ns_type) { struct ns_tree *ns_tree; struct rb_node *node; unsigned int seq; - RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "suspicious ns_tree_lookup_rcu() usage"); - ns_tree = ns_tree_from_type(ns_type); if (!ns_tree) return NULL; do { - seq = read_seqbegin(&ns_tree->ns_tree_lock); + seq = read_seqbegin(&ns_tree_lock); node = rb_find_rcu(&ns_id, &ns_tree->ns_tree, ns_find); if (node) break; - } while (read_seqretry(&ns_tree->ns_tree_lock, seq)); + } while (read_seqretry(&ns_tree_lock, seq)); return node_to_ns(node); } +struct ns_common *ns_tree_lookup_rcu(u64 ns_id, int ns_type) +{ + RCU_LOCKDEP_WARN(!rcu_read_lock_held(), "suspicious ns_tree_lookup_rcu() usage"); + + if (ns_type) + return __ns_tree_lookup_rcu(ns_id, ns_type); + + return __ns_unified_tree_lookup_rcu(ns_id); +} + /** * ns_tree_adjoined_rcu - find the next/previous namespace in the same * tree From 04173501a69ed0387cceb190181ef8f7f1c54f0a Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:27 +0100 Subject: [PATCH 17/75] nstree: allow lookup solely based on inode The namespace file handle struct nsfs_file_handle is uapi and userspace is expressly allowed to generate file handles without going through name_to_handle_at(). Allow userspace to generate a file handle where both the inode number and the namespace type are zero and just pass in the unique namespace id. The kernel uses the unified namespace tree to find the namespace and open the file handle. When the kernel creates a file handle via name_to_handle_at() it will always fill in the type and the inode number allowing userspace to retrieve core information. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-14-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- fs/nsfs.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/fs/nsfs.c b/fs/nsfs.c index 0c35e4e54711..4a95a0a38f86 100644 --- a/fs/nsfs.c +++ b/fs/nsfs.c @@ -496,15 +496,22 @@ static struct dentry *nsfs_fh_to_dentry(struct super_block *sb, struct fid *fh, return NULL; } + if (!fid->ns_id) + return NULL; + /* Either both are set or both are unset. */ + if (!fid->ns_inum != !fid->ns_type) + return NULL; + scoped_guard(rcu) { ns = ns_tree_lookup_rcu(fid->ns_id, fid->ns_type); if (!ns) return NULL; VFS_WARN_ON_ONCE(ns->ns_id != fid->ns_id); - VFS_WARN_ON_ONCE(ns->ns_type != fid->ns_type); - if (ns->inum != fid->ns_inum) + if (fid->ns_inum && (fid->ns_inum != ns->inum)) + return NULL; + if (fid->ns_type && (fid->ns_type != ns->ns_type)) return NULL; /* From 3760342fd6312416491d536144e39297fa5b1950 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:28 +0100 Subject: [PATCH 18/75] nstree: assign fixed ids to the initial namespaces The initial set of namespace comes with fixed inode numbers making it easy for userspace to identify them solely based on that information. This has long preceeded anything here. Similarly, let's assign fixed namespace ids for the initial namespaces. Kill the cookie and use a sequentially increasing number. This has the nice side-effect that the owning user namespace will always have a namespace id that is smaller than any of it's descendant namespaces. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-15-2e6f823ebdc0@kernel.org Signed-off-by: Christian Brauner --- fs/namespace.c | 2 +- include/linux/ns_common.h | 13 ++++++++++++- include/linux/nstree.h | 15 +++++++++++---- include/uapi/linux/nsfs.h | 14 ++++++++++++++ kernel/nstree.c | 13 ++++++++----- net/core/net_namespace.c | 2 +- 6 files changed, 47 insertions(+), 12 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index 7b78dd48b6c3..eded33eeb647 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -4094,7 +4094,7 @@ static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns, bool a return ERR_PTR(ret); } if (!anon) - ns_tree_gen_id(&new_ns->ns); + ns_tree_gen_id(new_ns); refcount_set(&new_ns->passive, 1); new_ns->mounts = RB_ROOT; init_waitqueue_head(&new_ns->poll); diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h index 7a3c71b3a76f..009a6dea724f 100644 --- a/include/linux/ns_common.h +++ b/include/linux/ns_common.h @@ -173,6 +173,17 @@ static __always_inline bool is_initial_namespace(struct ns_common *ns) struct user_namespace *: &init_user_ns, \ struct uts_namespace *: &init_uts_ns) +#define ns_init_id(__ns) \ + _Generic((__ns), \ + struct cgroup_namespace *: CGROUP_NS_INIT_ID, \ + struct ipc_namespace *: IPC_NS_INIT_ID, \ + struct mnt_namespace *: MNT_NS_INIT_ID, \ + struct net *: NET_NS_INIT_ID, \ + struct pid_namespace *: PID_NS_INIT_ID, \ + struct time_namespace *: TIME_NS_INIT_ID, \ + struct user_namespace *: USER_NS_INIT_ID, \ + struct uts_namespace *: UTS_NS_INIT_ID) + #define to_ns_operations(__ns) \ _Generic((__ns), \ struct cgroup_namespace *: (IS_ENABLED(CONFIG_CGROUPS) ? &cgroupns_operations : NULL), \ @@ -198,7 +209,7 @@ static __always_inline bool is_initial_namespace(struct ns_common *ns) #define NS_COMMON_INIT(nsname, refs) \ { \ .ns_type = ns_common_type(&nsname), \ - .ns_id = 0, \ + .ns_id = ns_init_id(&nsname), \ .inum = ns_init_inum(&nsname), \ .ops = to_ns_operations(&nsname), \ .stashed = NULL, \ diff --git a/include/linux/nstree.h b/include/linux/nstree.h index 43aa262c0ea1..38674c6fa4f7 100644 --- a/include/linux/nstree.h +++ b/include/linux/nstree.h @@ -9,6 +9,7 @@ #include #include #include +#include extern struct ns_tree cgroup_ns_tree; extern struct ns_tree ipc_ns_tree; @@ -30,7 +31,11 @@ extern struct ns_tree uts_ns_tree; struct user_namespace *: &(user_ns_tree), \ struct uts_namespace *: &(uts_ns_tree)) -u64 ns_tree_gen_id(struct ns_common *ns); +#define ns_tree_gen_id(__ns) \ + __ns_tree_gen_id(to_ns_common(__ns), \ + (((__ns) == ns_init_ns(__ns)) ? ns_init_id(__ns) : 0)) + +u64 __ns_tree_gen_id(struct ns_common *ns, u64 id); void __ns_tree_add_raw(struct ns_common *ns, struct ns_tree *ns_tree); void __ns_tree_remove(struct ns_common *ns, struct ns_tree *ns_tree); struct ns_common *ns_tree_lookup_rcu(u64 ns_id, int ns_type); @@ -38,9 +43,9 @@ struct ns_common *__ns_tree_adjoined_rcu(struct ns_common *ns, struct ns_tree *ns_tree, bool previous); -static inline void __ns_tree_add(struct ns_common *ns, struct ns_tree *ns_tree) +static inline void __ns_tree_add(struct ns_common *ns, struct ns_tree *ns_tree, u64 id) { - ns_tree_gen_id(ns); + __ns_tree_gen_id(ns, id); __ns_tree_add_raw(ns, ns_tree); } @@ -60,7 +65,9 @@ static inline void __ns_tree_add(struct ns_common *ns, struct ns_tree *ns_tree) * This function assigns a new id to the namespace and adds it to the * appropriate namespace tree and list. */ -#define ns_tree_add(__ns) __ns_tree_add(to_ns_common(__ns), to_ns_tree(__ns)) +#define ns_tree_add(__ns) \ + __ns_tree_add(to_ns_common(__ns), to_ns_tree(__ns), \ + (((__ns) == ns_init_ns(__ns)) ? ns_init_id(__ns) : 0)) /** * ns_tree_remove - Remove a namespace from a namespace tree diff --git a/include/uapi/linux/nsfs.h b/include/uapi/linux/nsfs.h index e098759ec917..f8bc2aad74d6 100644 --- a/include/uapi/linux/nsfs.h +++ b/include/uapi/linux/nsfs.h @@ -67,4 +67,18 @@ struct nsfs_file_handle { #define NSFS_FILE_HANDLE_SIZE_VER0 16 /* sizeof first published struct */ #define NSFS_FILE_HANDLE_SIZE_LATEST sizeof(struct nsfs_file_handle) /* sizeof latest published struct */ +enum init_ns_id { + IPC_NS_INIT_ID = 1ULL, + UTS_NS_INIT_ID = 2ULL, + USER_NS_INIT_ID = 3ULL, + PID_NS_INIT_ID = 4ULL, + CGROUP_NS_INIT_ID = 5ULL, + TIME_NS_INIT_ID = 6ULL, + NET_NS_INIT_ID = 7ULL, + MNT_NS_INIT_ID = 8ULL, +#ifdef __KERNEL__ + NS_LAST_INIT_ID = MNT_NS_INIT_ID, +#endif +}; + #endif /* __LINUX_NSFS_H */ diff --git a/kernel/nstree.c b/kernel/nstree.c index bbb34b46b01b..cf102c5bb849 100644 --- a/kernel/nstree.c +++ b/kernel/nstree.c @@ -69,8 +69,6 @@ struct ns_tree time_ns_tree = { .type = CLONE_NEWTIME, }; -DEFINE_COOKIE(namespace_cookie); - static inline struct ns_common *node_to_ns(const struct rb_node *node) { if (!node) @@ -285,15 +283,20 @@ struct ns_common *__ns_tree_adjoined_rcu(struct ns_common *ns, /** * ns_tree_gen_id - generate a new namespace id * @ns: namespace to generate id for + * @id: if non-zero, this is the initial namespace and this is a fixed id * * Generates a new namespace id and assigns it to the namespace. All * namespaces types share the same id space and thus can be compared * directly. IOW, when two ids of two namespace are equal, they are * identical. */ -u64 ns_tree_gen_id(struct ns_common *ns) +u64 __ns_tree_gen_id(struct ns_common *ns, u64 id) { - guard(preempt)(); - ns->ns_id = gen_cookie_next(&namespace_cookie); + static atomic64_t namespace_cookie = ATOMIC64_INIT(NS_LAST_INIT_ID + 1); + + if (id) + ns->ns_id = id; + else + ns->ns_id = atomic64_inc_return(&namespace_cookie); return ns->ns_id; } diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index b0e0f22d7b21..83cbec4afcb3 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -439,7 +439,7 @@ static __net_init int setup_net(struct net *net) LIST_HEAD(net_exit_list); int error = 0; - net->net_cookie = ns_tree_gen_id(&net->ns); + net->net_cookie = ns_tree_gen_id(net); list_for_each_entry(ops, &pernet_list, list) { error = ops_init(ops, net); From 3c1a52f2a6c865464babe7a85c2796aa31cc9744 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:29 +0100 Subject: [PATCH 19/75] nstree: maintain list of owned namespaces The namespace tree doesn't express the ownership concept of namespace appropriately. Maintain a list of directly owned namespaces per user namespace. This will allow userspace and the kernel to use the listns() system call to walk the namespace tree by owning user namespace. The rbtree is used to find the relevant namespace entry point which allows to continue iteration and the owner list can be used to walk the tree completely lock free. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-16-2e6f823ebdc0@kernel.org Signed-off-by: Christian Brauner --- include/linux/ns_common.h | 8 +++++ kernel/nscommon.c | 4 +++ kernel/nstree.c | 68 ++++++++++++++++++++++++++++++++++++++- 3 files changed, 79 insertions(+), 1 deletion(-) diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h index 009a6dea724f..698aa2f7f486 100644 --- a/include/linux/ns_common.h +++ b/include/linux/ns_common.h @@ -116,6 +116,12 @@ struct ns_common { struct rb_node ns_tree_node; struct list_head ns_list_node; }; + struct /* namespace ownership rbtree and list */ { + struct rb_root ns_owner_tree; /* rbtree of namespaces owned by this namespace */ + struct list_head ns_owner; /* list of namespaces owned by this namespace */ + struct rb_node ns_owner_tree_node; /* node in the owner namespace's rbtree */ + struct list_head ns_owner_entry; /* node in the owner namespace's ns_owned list */ + }; atomic_t __ns_ref_active; /* do not use directly */ }; struct rcu_head ns_rcu; @@ -216,6 +222,8 @@ static __always_inline bool is_initial_namespace(struct ns_common *ns) .__ns_ref = REFCOUNT_INIT(refs), \ .__ns_ref_active = ATOMIC_INIT(1), \ .ns_list_node = LIST_HEAD_INIT(nsname.ns.ns_list_node), \ + .ns_owner_entry = LIST_HEAD_INIT(nsname.ns.ns_owner_entry), \ + .ns_owner = LIST_HEAD_INIT(nsname.ns.ns_owner), \ } #define ns_common_init(__ns) \ diff --git a/kernel/nscommon.c b/kernel/nscommon.c index 17a6ea44f054..f0b7971392d2 100644 --- a/kernel/nscommon.c +++ b/kernel/nscommon.c @@ -63,7 +63,11 @@ int __ns_common_init(struct ns_common *ns, u32 ns_type, const struct proc_ns_ope ns->ns_type = ns_type; RB_CLEAR_NODE(&ns->ns_tree_node); RB_CLEAR_NODE(&ns->ns_unified_tree_node); + RB_CLEAR_NODE(&ns->ns_owner_tree_node); INIT_LIST_HEAD(&ns->ns_list_node); + ns->ns_owner_tree = RB_ROOT; + INIT_LIST_HEAD(&ns->ns_owner); + INIT_LIST_HEAD(&ns->ns_owner_entry); #ifdef CONFIG_DEBUG_VFS ns_debug(ns, ops); diff --git a/kernel/nstree.c b/kernel/nstree.c index cf102c5bb849..1f54f914e30c 100644 --- a/kernel/nstree.c +++ b/kernel/nstree.c @@ -3,7 +3,9 @@ #include #include +#include #include +#include static __cacheline_aligned_in_smp DEFINE_SEQLOCK(ns_tree_lock); static struct rb_root ns_unified_tree = RB_ROOT; /* protected by ns_tree_lock */ @@ -83,6 +85,13 @@ static inline struct ns_common *node_to_ns_unified(const struct rb_node *node) return rb_entry(node, struct ns_common, ns_unified_tree_node); } +static inline struct ns_common *node_to_ns_owner(const struct rb_node *node) +{ + if (!node) + return NULL; + return rb_entry(node, struct ns_common, ns_owner_tree_node); +} + static inline int ns_cmp(struct rb_node *a, const struct rb_node *b) { struct ns_common *ns_a = node_to_ns(a); @@ -111,11 +120,27 @@ static inline int ns_cmp_unified(struct rb_node *a, const struct rb_node *b) return 0; } +static inline int ns_cmp_owner(struct rb_node *a, const struct rb_node *b) +{ + struct ns_common *ns_a = node_to_ns_owner(a); + struct ns_common *ns_b = node_to_ns_owner(b); + u64 ns_id_a = ns_a->ns_id; + u64 ns_id_b = ns_b->ns_id; + + if (ns_id_a < ns_id_b) + return -1; + if (ns_id_a > ns_id_b) + return 1; + return 0; +} + void __ns_tree_add_raw(struct ns_common *ns, struct ns_tree *ns_tree) { struct rb_node *node, *prev; + const struct proc_ns_operations *ops = ns->ops; VFS_WARN_ON_ONCE(!ns->ns_id); + VFS_WARN_ON_ONCE(ns->ns_type != ns_tree->type); write_seqlock(&ns_tree_lock); @@ -131,6 +156,30 @@ void __ns_tree_add_raw(struct ns_common *ns, struct ns_tree *ns_tree) list_add_rcu(&ns->ns_list_node, &node_to_ns(prev)->ns_list_node); rb_find_add_rcu(&ns->ns_unified_tree_node, &ns_unified_tree, ns_cmp_unified); + + if (ops) { + struct user_namespace *user_ns; + + VFS_WARN_ON_ONCE(!ops->owner); + user_ns = ops->owner(ns); + if (user_ns) { + struct ns_common *owner = &user_ns->ns; + VFS_WARN_ON_ONCE(owner->ns_type != CLONE_NEWUSER); + + /* Insert into owner's rbtree */ + rb_find_add_rcu(&ns->ns_owner_tree_node, &owner->ns_owner_tree, ns_cmp_owner); + + /* Insert into owner's list in sorted order */ + prev = rb_prev(&ns->ns_owner_tree_node); + if (!prev) + list_add_rcu(&ns->ns_owner_entry, &owner->ns_owner); + else + list_add_rcu(&ns->ns_owner_entry, &node_to_ns_owner(prev)->ns_owner_entry); + } else { + /* Only the initial user namespace doesn't have an owner. */ + VFS_WARN_ON_ONCE(ns != to_ns_common(&init_user_ns)); + } + } write_sequnlock(&ns_tree_lock); VFS_WARN_ON_ONCE(node); @@ -146,6 +195,9 @@ void __ns_tree_add_raw(struct ns_common *ns, struct ns_tree *ns_tree) void __ns_tree_remove(struct ns_common *ns, struct ns_tree *ns_tree) { + const struct proc_ns_operations *ops = ns->ops; + struct user_namespace *user_ns; + VFS_WARN_ON_ONCE(RB_EMPTY_NODE(&ns->ns_tree_node)); VFS_WARN_ON_ONCE(list_empty(&ns->ns_list_node)); VFS_WARN_ON_ONCE(ns->ns_type != ns_tree->type); @@ -153,8 +205,22 @@ void __ns_tree_remove(struct ns_common *ns, struct ns_tree *ns_tree) write_seqlock(&ns_tree_lock); rb_erase(&ns->ns_tree_node, &ns_tree->ns_tree); rb_erase(&ns->ns_unified_tree_node, &ns_unified_tree); - list_bidir_del_rcu(&ns->ns_list_node); RB_CLEAR_NODE(&ns->ns_tree_node); + + list_bidir_del_rcu(&ns->ns_list_node); + + /* Remove from owner's rbtree if this namespace has an owner */ + if (ops) { + user_ns = ops->owner(ns); + if (user_ns) { + struct ns_common *owner = &user_ns->ns; + rb_erase(&ns->ns_owner_tree_node, &owner->ns_owner_tree); + RB_CLEAR_NODE(&ns->ns_owner_tree_node); + } + + list_bidir_del_rcu(&ns->ns_owner_entry); + } + write_sequnlock(&ns_tree_lock); } EXPORT_SYMBOL_GPL(__ns_tree_remove); From a202a50092cc47ff63048f0a53530fb95bbf3e44 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:30 +0100 Subject: [PATCH 20/75] nstree: simplify rbtree comparison helpers They all do the same basic thing. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-17-2e6f823ebdc0@kernel.org Signed-off-by: Christian Brauner --- kernel/nstree.c | 40 +++++++++++----------------------------- 1 file changed, 11 insertions(+), 29 deletions(-) diff --git a/kernel/nstree.c b/kernel/nstree.c index 1f54f914e30c..419d500d09df 100644 --- a/kernel/nstree.c +++ b/kernel/nstree.c @@ -92,46 +92,28 @@ static inline struct ns_common *node_to_ns_owner(const struct rb_node *node) return rb_entry(node, struct ns_common, ns_owner_tree_node); } -static inline int ns_cmp(struct rb_node *a, const struct rb_node *b) +static int ns_id_cmp(u64 id_a, u64 id_b) { - struct ns_common *ns_a = node_to_ns(a); - struct ns_common *ns_b = node_to_ns(b); - u64 ns_id_a = ns_a->ns_id; - u64 ns_id_b = ns_b->ns_id; - - if (ns_id_a < ns_id_b) + if (id_a < id_b) return -1; - if (ns_id_a > ns_id_b) + if (id_a > id_b) return 1; return 0; } -static inline int ns_cmp_unified(struct rb_node *a, const struct rb_node *b) +static int ns_cmp(struct rb_node *a, const struct rb_node *b) { - struct ns_common *ns_a = node_to_ns_unified(a); - struct ns_common *ns_b = node_to_ns_unified(b); - u64 ns_id_a = ns_a->ns_id; - u64 ns_id_b = ns_b->ns_id; - - if (ns_id_a < ns_id_b) - return -1; - if (ns_id_a > ns_id_b) - return 1; - return 0; + return ns_id_cmp(node_to_ns(a)->ns_id, node_to_ns(b)->ns_id); } -static inline int ns_cmp_owner(struct rb_node *a, const struct rb_node *b) +static int ns_cmp_unified(struct rb_node *a, const struct rb_node *b) { - struct ns_common *ns_a = node_to_ns_owner(a); - struct ns_common *ns_b = node_to_ns_owner(b); - u64 ns_id_a = ns_a->ns_id; - u64 ns_id_b = ns_b->ns_id; + return ns_id_cmp(node_to_ns_unified(a)->ns_id, node_to_ns_unified(b)->ns_id); +} - if (ns_id_a < ns_id_b) - return -1; - if (ns_id_a > ns_id_b) - return 1; - return 0; +static int ns_cmp_owner(struct rb_node *a, const struct rb_node *b) +{ + return ns_id_cmp(node_to_ns_owner(a)->ns_id, node_to_ns_owner(b)->ns_id); } void __ns_tree_add_raw(struct ns_common *ns, struct ns_tree *ns_tree) From 560e25e70fa40ec69f97f14207bde9bc18bec9b8 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:31 +0100 Subject: [PATCH 21/75] nstree: add unified namespace list Allow to walk the unified namespace list completely locklessly. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-18-2e6f823ebdc0@kernel.org Signed-off-by: Christian Brauner --- include/linux/ns_common.h | 2 ++ kernel/nscommon.c | 1 + kernel/nstree.c | 13 ++++++++++++- 3 files changed, 15 insertions(+), 1 deletion(-) diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h index 698aa2f7f486..3f05dd7d40c7 100644 --- a/include/linux/ns_common.h +++ b/include/linux/ns_common.h @@ -111,6 +111,7 @@ struct ns_common { u64 ns_id; struct /* global namespace rbtree and list */ { struct rb_node ns_unified_tree_node; + struct list_head ns_unified_list_node; }; struct /* per type rbtree and list */ { struct rb_node ns_tree_node; @@ -224,6 +225,7 @@ static __always_inline bool is_initial_namespace(struct ns_common *ns) .ns_list_node = LIST_HEAD_INIT(nsname.ns.ns_list_node), \ .ns_owner_entry = LIST_HEAD_INIT(nsname.ns.ns_owner_entry), \ .ns_owner = LIST_HEAD_INIT(nsname.ns.ns_owner), \ + .ns_unified_list_node = LIST_HEAD_INIT(nsname.ns.ns_unified_list_node), \ } #define ns_common_init(__ns) \ diff --git a/kernel/nscommon.c b/kernel/nscommon.c index f0b7971392d2..4cbe1ecc8df0 100644 --- a/kernel/nscommon.c +++ b/kernel/nscommon.c @@ -65,6 +65,7 @@ int __ns_common_init(struct ns_common *ns, u32 ns_type, const struct proc_ns_ope RB_CLEAR_NODE(&ns->ns_unified_tree_node); RB_CLEAR_NODE(&ns->ns_owner_tree_node); INIT_LIST_HEAD(&ns->ns_list_node); + INIT_LIST_HEAD(&ns->ns_unified_list_node); ns->ns_owner_tree = RB_ROOT; INIT_LIST_HEAD(&ns->ns_owner); INIT_LIST_HEAD(&ns->ns_owner_entry); diff --git a/kernel/nstree.c b/kernel/nstree.c index 419d500d09df..dcad6a308547 100644 --- a/kernel/nstree.c +++ b/kernel/nstree.c @@ -9,6 +9,7 @@ static __cacheline_aligned_in_smp DEFINE_SEQLOCK(ns_tree_lock); static struct rb_root ns_unified_tree = RB_ROOT; /* protected by ns_tree_lock */ +static LIST_HEAD(ns_unified_list); /* protected by ns_tree_lock */ /** * struct ns_tree - Namespace tree @@ -137,7 +138,13 @@ void __ns_tree_add_raw(struct ns_common *ns, struct ns_tree *ns_tree) else list_add_rcu(&ns->ns_list_node, &node_to_ns(prev)->ns_list_node); + /* Add to unified tree and list */ rb_find_add_rcu(&ns->ns_unified_tree_node, &ns_unified_tree, ns_cmp_unified); + prev = rb_prev(&ns->ns_unified_tree_node); + if (!prev) + list_add_rcu(&ns->ns_unified_list_node, &ns_unified_list); + else + list_add_rcu(&ns->ns_unified_list_node, &node_to_ns_unified(prev)->ns_unified_list_node); if (ops) { struct user_namespace *user_ns; @@ -186,11 +193,15 @@ void __ns_tree_remove(struct ns_common *ns, struct ns_tree *ns_tree) write_seqlock(&ns_tree_lock); rb_erase(&ns->ns_tree_node, &ns_tree->ns_tree); - rb_erase(&ns->ns_unified_tree_node, &ns_unified_tree); RB_CLEAR_NODE(&ns->ns_tree_node); list_bidir_del_rcu(&ns->ns_list_node); + rb_erase(&ns->ns_unified_tree_node, &ns_unified_tree); + RB_CLEAR_NODE(&ns->ns_unified_tree_node); + + list_bidir_del_rcu(&ns->ns_unified_list_node); + /* Remove from owner's rbtree if this namespace has an owner */ if (ops) { user_ns = ops->owner(ns); From 76b6f5dfb3fda76fce1f9990d6fa58adc711122b Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:32 +0100 Subject: [PATCH 22/75] nstree: add listns() Add a new listns() system call that allows userspace to iterate through namespaces in the system. This provides a programmatic interface to discover and inspect namespaces, enhancing existing namespace apis. Currently, there is no direct way for userspace to enumerate namespaces in the system. Applications must resort to scanning /proc//ns/ across all processes, which is: 1. Inefficient - requires iterating over all processes 2. Incomplete - misses inactive namespaces that aren't attached to any running process but are kept alive by file descriptors, bind mounts, or parent namespace references 3. Permission-heavy - requires access to /proc for many processes 4. No ordering or ownership. 5. No filtering per namespace type: Must always iterate and check all namespaces. The list goes on. The listns() system call solves these problems by providing direct kernel-level enumeration of namespaces. It is similar to listmount() but obviously tailored to namespaces. /* * @req: Pointer to struct ns_id_req specifying search parameters * @ns_ids: User buffer to receive namespace IDs * @nr_ns_ids: Size of ns_ids buffer (maximum number of IDs to return) * @flags: Reserved for future use (must be 0) */ ssize_t listns(const struct ns_id_req *req, u64 *ns_ids, size_t nr_ns_ids, unsigned int flags); Returns: - On success: Number of namespace IDs written to ns_ids - On error: Negative error code /* * @size: Structure size * @ns_id: Starting point for iteration; use 0 for first call, then * use the last returned ID for subsequent calls to paginate * @ns_type: Bitmask of namespace types to include (from enum ns_type): * 0: Return all namespace types * MNT_NS: Mount namespaces * NET_NS: Network namespaces * USER_NS: User namespaces * etc. Can be OR'd together * @user_ns_id: Filter results to namespaces owned by this user namespace: * 0: Return all namespaces (subject to permission checks) * LISTNS_CURRENT_USER: Namespaces owned by caller's user namespace * Other value: Namespaces owned by the specified user namespace ID */ struct ns_id_req { __u32 size; /* sizeof(struct ns_id_req) */ __u32 spare; /* Reserved, must be 0 */ __u64 ns_id; /* Last seen namespace ID (for pagination) */ __u32 ns_type; /* Filter by namespace type(s) */ __u32 spare2; /* Reserved, must be 0 */ __u64 user_ns_id; /* Filter by owning user namespace */ }; Example 1: List all namespaces void list_all_namespaces(void) { struct ns_id_req req = { .size = sizeof(req), .ns_id = 0, /* Start from beginning */ .ns_type = 0, /* All types */ .user_ns_id = 0, /* All user namespaces */ }; uint64_t ids[100]; ssize_t ret; printf("All namespaces in the system:\n"); do { ret = listns(&req, ids, 100, 0); if (ret < 0) { perror("listns"); break; } for (ssize_t i = 0; i < ret; i++) printf(" Namespace ID: %llu\n", (unsigned long long)ids[i]); /* Continue from last seen ID */ if (ret > 0) req.ns_id = ids[ret - 1]; } while (ret == 100); /* Buffer was full, more may exist */ } Example 2: List network namespaces only void list_network_namespaces(void) { struct ns_id_req req = { .size = sizeof(req), .ns_id = 0, .ns_type = NET_NS, /* Only network namespaces */ .user_ns_id = 0, }; uint64_t ids[100]; ssize_t ret; ret = listns(&req, ids, 100, 0); if (ret < 0) { perror("listns"); return; } printf("Network namespaces: %zd found\n", ret); for (ssize_t i = 0; i < ret; i++) printf(" netns ID: %llu\n", (unsigned long long)ids[i]); } Example 3: List namespaces owned by current user namespace void list_owned_namespaces(void) { struct ns_id_req req = { .size = sizeof(req), .ns_id = 0, .ns_type = 0, /* All types */ .user_ns_id = LISTNS_CURRENT_USER, /* Current userns */ }; uint64_t ids[100]; ssize_t ret; ret = listns(&req, ids, 100, 0); if (ret < 0) { perror("listns"); return; } printf("Namespaces owned by my user namespace: %zd\n", ret); for (ssize_t i = 0; i < ret; i++) printf(" ns ID: %llu\n", (unsigned long long)ids[i]); } Example 4: List multiple namespace types void list_network_and_mount_namespaces(void) { struct ns_id_req req = { .size = sizeof(req), .ns_id = 0, .ns_type = NET_NS | MNT_NS, /* Network and mount */ .user_ns_id = 0, }; uint64_t ids[100]; ssize_t ret; ret = listns(&req, ids, 100, 0); printf("Network and mount namespaces: %zd found\n", ret); } Example 5: Pagination through large namespace sets void list_all_with_pagination(void) { struct ns_id_req req = { .size = sizeof(req), .ns_id = 0, .ns_type = 0, .user_ns_id = 0, }; uint64_t ids[50]; size_t total = 0; ssize_t ret; printf("Enumerating all namespaces with pagination:\n"); while (1) { ret = listns(&req, ids, 50, 0); if (ret < 0) { perror("listns"); break; } if (ret == 0) break; /* No more namespaces */ total += ret; printf(" Batch: %zd namespaces\n", ret); /* Last ID in this batch becomes start of next batch */ req.ns_id = ids[ret - 1]; if (ret < 50) break; /* Partial batch = end of results */ } printf("Total: %zu namespaces\n", total); } Permission Model listns() respects namespace isolation and capabilities: (1) Global listing (user_ns_id = 0): - Requires CAP_SYS_ADMIN in the namespace's owning user namespace - OR the namespace must be in the caller's namespace context (e.g., a namespace the caller is currently using) - User namespaces additionally allow listing if the caller has CAP_SYS_ADMIN in that user namespace itself (2) Owner-filtered listing (user_ns_id != 0): - Requires CAP_SYS_ADMIN in the specified owner user namespace - OR the namespace must be in the caller's namespace context - This allows unprivileged processes to enumerate namespaces they own (3) Visibility: - Only "active" namespaces are listed - A namespace is active if it has a non-zero __ns_ref_active count - This includes namespaces used by running processes, held by open file descriptors, or kept active by bind mounts - Inactive namespaces (kept alive only by internal kernel references) are not visible via listns() Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-19-2e6f823ebdc0@kernel.org Signed-off-by: Christian Brauner --- fs/nsfs.c | 39 ++++ include/linux/ns_common.h | 2 + include/linux/syscalls.h | 4 + include/linux/user_namespace.h | 4 +- include/uapi/linux/nsfs.h | 44 ++++ kernel/nscommon.c | 2 +- kernel/nstree.c | 397 +++++++++++++++++++++++++++++++++ 7 files changed, 489 insertions(+), 3 deletions(-) diff --git a/fs/nsfs.c b/fs/nsfs.c index 4a95a0a38f86..ba6c8975c82e 100644 --- a/fs/nsfs.c +++ b/fs/nsfs.c @@ -471,6 +471,45 @@ static int nsfs_encode_fh(struct inode *inode, u32 *fh, int *max_len, return FILEID_NSFS; } +bool is_current_namespace(struct ns_common *ns) +{ + switch (ns->ns_type) { +#ifdef CONFIG_CGROUPS + case CLONE_NEWCGROUP: + return current_in_namespace(to_cg_ns(ns)); +#endif +#ifdef CONFIG_IPC_NS + case CLONE_NEWIPC: + return current_in_namespace(to_ipc_ns(ns)); +#endif + case CLONE_NEWNS: + return current_in_namespace(to_mnt_ns(ns)); +#ifdef CONFIG_NET_NS + case CLONE_NEWNET: + return current_in_namespace(to_net_ns(ns)); +#endif +#ifdef CONFIG_PID_NS + case CLONE_NEWPID: + return current_in_namespace(to_pid_ns(ns)); +#endif +#ifdef CONFIG_TIME_NS + case CLONE_NEWTIME: + return current_in_namespace(to_time_ns(ns)); +#endif +#ifdef CONFIG_USER_NS + case CLONE_NEWUSER: + return current_in_namespace(to_user_ns(ns)); +#endif +#ifdef CONFIG_UTS_NS + case CLONE_NEWUTS: + return current_in_namespace(to_uts_ns(ns)); +#endif + default: + VFS_WARN_ON_ONCE(true); + return false; + } +} + static struct dentry *nsfs_fh_to_dentry(struct super_block *sb, struct fid *fh, int fh_len, int fh_type) { diff --git a/include/linux/ns_common.h b/include/linux/ns_common.h index 3f05dd7d40c7..bd4492ef6ffc 100644 --- a/include/linux/ns_common.h +++ b/include/linux/ns_common.h @@ -129,8 +129,10 @@ struct ns_common { }; }; +bool is_current_namespace(struct ns_common *ns); int __ns_common_init(struct ns_common *ns, u32 ns_type, const struct proc_ns_operations *ops, int inum); void __ns_common_free(struct ns_common *ns); +struct ns_common *__must_check ns_owner(struct ns_common *ns); static __always_inline bool is_initial_namespace(struct ns_common *ns) { diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 66c06fcdfe19..cf84d98964b2 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -77,6 +77,7 @@ struct cachestat_range; struct cachestat; struct statmount; struct mnt_id_req; +struct ns_id_req; struct xattr_args; struct file_attr; @@ -437,6 +438,9 @@ asmlinkage long sys_statmount(const struct mnt_id_req __user *req, asmlinkage long sys_listmount(const struct mnt_id_req __user *req, u64 __user *mnt_ids, size_t nr_mnt_ids, unsigned int flags); +asmlinkage long sys_listns(const struct ns_id_req __user *req, + u64 __user *ns_ids, size_t nr_ns_ids, + unsigned int flags); asmlinkage long sys_truncate(const char __user *path, long length); asmlinkage long sys_ftruncate(unsigned int fd, off_t length); #if BITS_PER_LONG == 32 diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h index 9a9aebbf96b9..9c3be157397e 100644 --- a/include/linux/user_namespace.h +++ b/include/linux/user_namespace.h @@ -166,13 +166,13 @@ static inline void set_userns_rlimit_max(struct user_namespace *ns, ns->rlimit_max[type] = max <= LONG_MAX ? max : LONG_MAX; } -#ifdef CONFIG_USER_NS - static inline struct user_namespace *to_user_ns(struct ns_common *ns) { return container_of(ns, struct user_namespace, ns); } +#ifdef CONFIG_USER_NS + static inline struct user_namespace *get_user_ns(struct user_namespace *ns) { if (ns) diff --git a/include/uapi/linux/nsfs.h b/include/uapi/linux/nsfs.h index f8bc2aad74d6..a25e38d1c874 100644 --- a/include/uapi/linux/nsfs.h +++ b/include/uapi/linux/nsfs.h @@ -81,4 +81,48 @@ enum init_ns_id { #endif }; +enum ns_type { + TIME_NS = (1ULL << 7), /* CLONE_NEWTIME */ + MNT_NS = (1ULL << 17), /* CLONE_NEWNS */ + CGROUP_NS = (1ULL << 25), /* CLONE_NEWCGROUP */ + UTS_NS = (1ULL << 26), /* CLONE_NEWUTS */ + IPC_NS = (1ULL << 27), /* CLONE_NEWIPC */ + USER_NS = (1ULL << 28), /* CLONE_NEWUSER */ + PID_NS = (1ULL << 29), /* CLONE_NEWPID */ + NET_NS = (1ULL << 30), /* CLONE_NEWNET */ +}; + +/** + * struct ns_id_req - namespace ID request structure + * @size: size of this structure + * @spare: reserved for future use + * @filter: filter mask + * @ns_id: last namespace id + * @user_ns_id: owning user namespace ID + * + * Structure for passing namespace ID and miscellaneous parameters to + * statns(2) and listns(2). + * + * For statns(2) @param represents the request mask. + * For listns(2) @param represents the last listed mount id (or zero). + */ +struct ns_id_req { + __u32 size; + __u32 spare; + __u64 ns_id; + struct /* listns */ { + __u32 ns_type; + __u32 spare2; + __u64 user_ns_id; + }; +}; + +/* + * Special @user_ns_id value that can be passed to listns() + */ +#define LISTNS_CURRENT_USER 0xffffffffffffffff /* Caller's userns */ + +/* List of all ns_id_req versions. */ +#define NS_ID_REQ_SIZE_VER0 32 /* sizeof first published struct */ + #endif /* __LINUX_NSFS_H */ diff --git a/kernel/nscommon.c b/kernel/nscommon.c index 4cbe1ecc8df0..6fe1c747fa46 100644 --- a/kernel/nscommon.c +++ b/kernel/nscommon.c @@ -98,7 +98,7 @@ void __ns_common_free(struct ns_common *ns) proc_free_inum(ns->inum); } -static struct ns_common *ns_owner(struct ns_common *ns) +struct ns_common *__must_check ns_owner(struct ns_common *ns) { struct user_namespace *owner; diff --git a/kernel/nstree.c b/kernel/nstree.c index dcad6a308547..4a8838683b6b 100644 --- a/kernel/nstree.c +++ b/kernel/nstree.c @@ -5,6 +5,7 @@ #include #include #include +#include #include static __cacheline_aligned_in_smp DEFINE_SEQLOCK(ns_tree_lock); @@ -359,3 +360,399 @@ u64 __ns_tree_gen_id(struct ns_common *ns, u64 id) ns->ns_id = atomic64_inc_return(&namespace_cookie); return ns->ns_id; } + +struct klistns { + u64 __user *uns_ids; + u32 nr_ns_ids; + u64 last_ns_id; + u64 user_ns_id; + u32 ns_type; + struct user_namespace *user_ns; + bool userns_capable; + struct ns_common *first_ns; +}; + +static void __free_klistns_free(const struct klistns *kls) +{ + if (kls->user_ns_id != LISTNS_CURRENT_USER) + put_user_ns(kls->user_ns); + if (kls->first_ns && kls->first_ns->ops) + kls->first_ns->ops->put(kls->first_ns); +} + +#define NS_ALL (PID_NS | USER_NS | MNT_NS | UTS_NS | IPC_NS | NET_NS | CGROUP_NS | TIME_NS) + +static int copy_ns_id_req(const struct ns_id_req __user *req, + struct ns_id_req *kreq) +{ + int ret; + size_t usize; + + BUILD_BUG_ON(sizeof(struct ns_id_req) != NS_ID_REQ_SIZE_VER0); + + ret = get_user(usize, &req->size); + if (ret) + return -EFAULT; + if (unlikely(usize > PAGE_SIZE)) + return -E2BIG; + if (unlikely(usize < NS_ID_REQ_SIZE_VER0)) + return -EINVAL; + memset(kreq, 0, sizeof(*kreq)); + ret = copy_struct_from_user(kreq, sizeof(*kreq), req, usize); + if (ret) + return ret; + if (kreq->spare != 0) + return -EINVAL; + if (kreq->ns_type & ~NS_ALL) + return -EOPNOTSUPP; + return 0; +} + +static inline int prepare_klistns(struct klistns *kls, struct ns_id_req *kreq, + u64 __user *ns_ids, size_t nr_ns_ids) +{ + kls->last_ns_id = kreq->ns_id; + kls->user_ns_id = kreq->user_ns_id; + kls->nr_ns_ids = nr_ns_ids; + kls->ns_type = kreq->ns_type; + kls->uns_ids = ns_ids; + return 0; +} + +/* + * Lookup a namespace owned by owner with id >= ns_id. + * Returns the namespace with the smallest id that is >= ns_id. + */ +static struct ns_common *lookup_ns_owner_at(u64 ns_id, struct ns_common *owner) +{ + struct ns_common *ret = NULL; + struct rb_node *node; + + VFS_WARN_ON_ONCE(owner->ns_type != CLONE_NEWUSER); + + read_seqlock_excl(&ns_tree_lock); + node = owner->ns_owner_tree.rb_node; + + while (node) { + struct ns_common *ns; + + ns = node_to_ns_owner(node); + if (ns_id <= ns->ns_id) { + ret = ns; + if (ns_id == ns->ns_id) + break; + node = node->rb_left; + } else { + node = node->rb_right; + } + } + + if (ret) + ret = ns_get_unless_inactive(ret); + read_sequnlock_excl(&ns_tree_lock); + return ret; +} + +static struct ns_common *lookup_ns_id(u64 mnt_ns_id, int ns_type) +{ + struct ns_common *ns; + + guard(rcu)(); + ns = ns_tree_lookup_rcu(mnt_ns_id, ns_type); + if (!ns) + return NULL; + + if (!ns_get_unless_inactive(ns)) + return NULL; + + return ns; +} + +static inline bool __must_check ns_requested(const struct klistns *kls, + const struct ns_common *ns) +{ + return !kls->ns_type || (kls->ns_type & ns->ns_type); +} + +static inline bool __must_check may_list_ns(const struct klistns *kls, + struct ns_common *ns) +{ + if (kls->user_ns) { + if (kls->userns_capable) + return true; + } else { + struct ns_common *owner; + struct user_namespace *user_ns; + + owner = ns_owner(ns); + if (owner) + user_ns = to_user_ns(owner); + else + user_ns = &init_user_ns; + if (ns_capable_noaudit(user_ns, CAP_SYS_ADMIN)) + return true; + } + + if (is_current_namespace(ns)) + return true; + + if (ns->ns_type != CLONE_NEWUSER) + return false; + + if (ns_capable_noaudit(to_user_ns(ns), CAP_SYS_ADMIN)) + return true; + + return false; +} + +static void __ns_put(struct ns_common *ns) +{ + if (ns->ops) + ns->ops->put(ns); +} + +DEFINE_FREE(ns_put, struct ns_common *, if (!IS_ERR_OR_NULL(_T)) __ns_put(_T)) + +static inline struct ns_common *__must_check legitimize_ns(const struct klistns *kls, + struct ns_common *candidate) +{ + struct ns_common *ns __free(ns_put) = NULL; + + if (!ns_requested(kls, candidate)) + return NULL; + + ns = ns_get_unless_inactive(candidate); + if (!ns) + return NULL; + + if (!may_list_ns(kls, ns)) + return NULL; + + return no_free_ptr(ns); +} + +static ssize_t do_listns_userns(struct klistns *kls) +{ + u64 __user *ns_ids = kls->uns_ids; + size_t nr_ns_ids = kls->nr_ns_ids; + struct ns_common *ns = NULL, *first_ns = NULL; + const struct list_head *head; + ssize_t ret; + + VFS_WARN_ON_ONCE(!kls->user_ns_id); + + if (kls->user_ns_id == LISTNS_CURRENT_USER) + ns = to_ns_common(current_user_ns()); + else if (kls->user_ns_id) + ns = lookup_ns_id(kls->user_ns_id, CLONE_NEWUSER); + if (!ns) + return -EINVAL; + kls->user_ns = to_user_ns(ns); + + /* + * Use the rbtree to find the first namespace we care about and + * then use it's list entry to iterate from there. + */ + if (kls->last_ns_id) { + kls->first_ns = lookup_ns_owner_at(kls->last_ns_id + 1, ns); + if (!kls->first_ns) + return -ENOENT; + first_ns = kls->first_ns; + } + + ret = 0; + head = &to_ns_common(kls->user_ns)->ns_owner; + kls->userns_capable = ns_capable_noaudit(kls->user_ns, CAP_SYS_ADMIN); + + rcu_read_lock(); + + if (!first_ns) + first_ns = list_entry_rcu(head->next, typeof(*ns), ns_owner_entry); + for (ns = first_ns; &ns->ns_owner_entry != head && nr_ns_ids; + ns = list_entry_rcu(ns->ns_owner_entry.next, typeof(*ns), ns_owner_entry)) { + struct ns_common *valid __free(ns_put); + + valid = legitimize_ns(kls, ns); + if (!valid) + continue; + + rcu_read_unlock(); + + if (put_user(valid->ns_id, ns_ids + ret)) + return -EINVAL; + nr_ns_ids--; + ret++; + + rcu_read_lock(); + } + + rcu_read_unlock(); + return ret; +} + +/* + * Lookup a namespace with id >= ns_id in either the unified tree or a type-specific tree. + * Returns the namespace with the smallest id that is >= ns_id. + */ +static struct ns_common *lookup_ns_id_at(u64 ns_id, int ns_type) +{ + struct ns_common *ret = NULL; + struct ns_tree *ns_tree = NULL; + struct rb_node *node; + + if (ns_type) { + ns_tree = ns_tree_from_type(ns_type); + if (!ns_tree) + return NULL; + } + + read_seqlock_excl(&ns_tree_lock); + if (ns_tree) + node = ns_tree->ns_tree.rb_node; + else + node = ns_unified_tree.rb_node; + + while (node) { + struct ns_common *ns; + + if (ns_type) + ns = node_to_ns(node); + else + ns = node_to_ns_unified(node); + + if (ns_id <= ns->ns_id) { + if (ns_type) + ret = node_to_ns(node); + else + ret = node_to_ns_unified(node); + if (ns_id == ns->ns_id) + break; + node = node->rb_left; + } else { + node = node->rb_right; + } + } + + if (ret) + ret = ns_get_unless_inactive(ret); + read_sequnlock_excl(&ns_tree_lock); + return ret; +} + +static inline struct ns_common *first_ns_common(const struct list_head *head, + struct ns_tree *ns_tree) +{ + if (ns_tree) + return list_entry_rcu(head->next, struct ns_common, ns_list_node); + return list_entry_rcu(head->next, struct ns_common, ns_unified_list_node); +} + +static inline struct ns_common *next_ns_common(struct ns_common *ns, + struct ns_tree *ns_tree) +{ + if (ns_tree) + return list_entry_rcu(ns->ns_list_node.next, struct ns_common, ns_list_node); + return list_entry_rcu(ns->ns_unified_list_node.next, struct ns_common, ns_unified_list_node); +} + +static inline bool ns_common_is_head(struct ns_common *ns, + const struct list_head *head, + struct ns_tree *ns_tree) +{ + if (ns_tree) + return &ns->ns_list_node == head; + return &ns->ns_unified_list_node == head; +} + +static ssize_t do_listns(struct klistns *kls) +{ + u64 __user *ns_ids = kls->uns_ids; + size_t nr_ns_ids = kls->nr_ns_ids; + struct ns_common *ns, *first_ns = NULL; + struct ns_tree *ns_tree = NULL; + const struct list_head *head; + u32 ns_type; + ssize_t ret; + + if (hweight32(kls->ns_type) == 1) + ns_type = kls->ns_type; + else + ns_type = 0; + + if (ns_type) { + ns_tree = ns_tree_from_type(ns_type); + if (!ns_tree) + return -EINVAL; + } + + if (kls->last_ns_id) { + kls->first_ns = lookup_ns_id_at(kls->last_ns_id + 1, ns_type); + if (!kls->first_ns) + return -ENOENT; + first_ns = kls->first_ns; + } + + ret = 0; + if (ns_tree) + head = &ns_tree->ns_list; + else + head = &ns_unified_list; + + rcu_read_lock(); + + if (!first_ns) + first_ns = first_ns_common(head, ns_tree); + + for (ns = first_ns; !ns_common_is_head(ns, head, ns_tree) && nr_ns_ids; + ns = next_ns_common(ns, ns_tree)) { + struct ns_common *valid __free(ns_put); + + valid = legitimize_ns(kls, ns); + if (!valid) + continue; + + rcu_read_unlock(); + + if (put_user(valid->ns_id, ns_ids + ret)) + return -EINVAL; + + nr_ns_ids--; + ret++; + + rcu_read_lock(); + } + + rcu_read_unlock(); + return ret; +} + +SYSCALL_DEFINE4(listns, const struct ns_id_req __user *, req, + u64 __user *, ns_ids, size_t, nr_ns_ids, unsigned int, flags) +{ + struct klistns klns __free(klistns_free) = {}; + const size_t maxcount = 1000000; + struct ns_id_req kreq; + ssize_t ret; + + if (flags) + return -EINVAL; + + if (unlikely(nr_ns_ids > maxcount)) + return -EOVERFLOW; + + if (!access_ok(ns_ids, nr_ns_ids * sizeof(*ns_ids))) + return -EFAULT; + + ret = copy_ns_id_req(req, &kreq); + if (ret) + return ret; + + ret = prepare_klistns(&klns, &kreq, ns_ids, nr_ns_ids); + if (ret) + return ret; + + if (kreq.user_ns_id) + return do_listns_userns(&klns); + + return do_listns(&klns); +} From b36d4b6aa88ef039647228b98c59a875e92f8c8e Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:33 +0100 Subject: [PATCH 23/75] arch: hookup listns() system call Add the listns() system call to all architectures. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-20-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Arnd Bergmann Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- arch/alpha/kernel/syscalls/syscall.tbl | 1 + arch/arm/tools/syscall.tbl | 1 + arch/arm64/tools/syscall_32.tbl | 1 + arch/m68k/kernel/syscalls/syscall.tbl | 1 + arch/microblaze/kernel/syscalls/syscall.tbl | 1 + arch/mips/kernel/syscalls/syscall_n32.tbl | 1 + arch/mips/kernel/syscalls/syscall_n64.tbl | 1 + arch/mips/kernel/syscalls/syscall_o32.tbl | 1 + arch/parisc/kernel/syscalls/syscall.tbl | 1 + arch/powerpc/kernel/syscalls/syscall.tbl | 1 + arch/s390/kernel/syscalls/syscall.tbl | 1 + arch/sh/kernel/syscalls/syscall.tbl | 1 + arch/sparc/kernel/syscalls/syscall.tbl | 1 + arch/x86/entry/syscalls/syscall_32.tbl | 1 + arch/x86/entry/syscalls/syscall_64.tbl | 1 + arch/xtensa/kernel/syscalls/syscall.tbl | 1 + include/uapi/asm-generic/unistd.h | 4 +++- scripts/syscall.tbl | 1 + 18 files changed, 20 insertions(+), 1 deletion(-) diff --git a/arch/alpha/kernel/syscalls/syscall.tbl b/arch/alpha/kernel/syscalls/syscall.tbl index 16dca28ebf17..3fed97478058 100644 --- a/arch/alpha/kernel/syscalls/syscall.tbl +++ b/arch/alpha/kernel/syscalls/syscall.tbl @@ -509,3 +509,4 @@ 577 common open_tree_attr sys_open_tree_attr 578 common file_getattr sys_file_getattr 579 common file_setattr sys_file_setattr +580 common listns sys_listns diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl index b07e699aaa3c..fd09afae72a2 100644 --- a/arch/arm/tools/syscall.tbl +++ b/arch/arm/tools/syscall.tbl @@ -484,3 +484,4 @@ 467 common open_tree_attr sys_open_tree_attr 468 common file_getattr sys_file_getattr 469 common file_setattr sys_file_setattr +470 common listns sys_listns diff --git a/arch/arm64/tools/syscall_32.tbl b/arch/arm64/tools/syscall_32.tbl index 8d9088bc577d..8cdfe5d4dac9 100644 --- a/arch/arm64/tools/syscall_32.tbl +++ b/arch/arm64/tools/syscall_32.tbl @@ -481,3 +481,4 @@ 467 common open_tree_attr sys_open_tree_attr 468 common file_getattr sys_file_getattr 469 common file_setattr sys_file_setattr +470 common listns sys_listns diff --git a/arch/m68k/kernel/syscalls/syscall.tbl b/arch/m68k/kernel/syscalls/syscall.tbl index f41d38dfbf13..871a5d67bf41 100644 --- a/arch/m68k/kernel/syscalls/syscall.tbl +++ b/arch/m68k/kernel/syscalls/syscall.tbl @@ -469,3 +469,4 @@ 467 common open_tree_attr sys_open_tree_attr 468 common file_getattr sys_file_getattr 469 common file_setattr sys_file_setattr +470 common listns sys_listns diff --git a/arch/microblaze/kernel/syscalls/syscall.tbl b/arch/microblaze/kernel/syscalls/syscall.tbl index 580af574fe73..022fc85d94b3 100644 --- a/arch/microblaze/kernel/syscalls/syscall.tbl +++ b/arch/microblaze/kernel/syscalls/syscall.tbl @@ -475,3 +475,4 @@ 467 common open_tree_attr sys_open_tree_attr 468 common file_getattr sys_file_getattr 469 common file_setattr sys_file_setattr +470 common listns sys_listns diff --git a/arch/mips/kernel/syscalls/syscall_n32.tbl b/arch/mips/kernel/syscalls/syscall_n32.tbl index d824ffe9a014..8cedc83c3266 100644 --- a/arch/mips/kernel/syscalls/syscall_n32.tbl +++ b/arch/mips/kernel/syscalls/syscall_n32.tbl @@ -408,3 +408,4 @@ 467 n32 open_tree_attr sys_open_tree_attr 468 n32 file_getattr sys_file_getattr 469 n32 file_setattr sys_file_setattr +470 n32 listns sys_listns diff --git a/arch/mips/kernel/syscalls/syscall_n64.tbl b/arch/mips/kernel/syscalls/syscall_n64.tbl index 7a7049c2c307..9b92bddf06b5 100644 --- a/arch/mips/kernel/syscalls/syscall_n64.tbl +++ b/arch/mips/kernel/syscalls/syscall_n64.tbl @@ -384,3 +384,4 @@ 467 n64 open_tree_attr sys_open_tree_attr 468 n64 file_getattr sys_file_getattr 469 n64 file_setattr sys_file_setattr +470 n64 listns sys_listns diff --git a/arch/mips/kernel/syscalls/syscall_o32.tbl b/arch/mips/kernel/syscalls/syscall_o32.tbl index d330274f0601..f810b8a55716 100644 --- a/arch/mips/kernel/syscalls/syscall_o32.tbl +++ b/arch/mips/kernel/syscalls/syscall_o32.tbl @@ -457,3 +457,4 @@ 467 o32 open_tree_attr sys_open_tree_attr 468 o32 file_getattr sys_file_getattr 469 o32 file_setattr sys_file_setattr +470 o32 listns sys_listns diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl index 88a788a7b18d..39bdacaa530b 100644 --- a/arch/parisc/kernel/syscalls/syscall.tbl +++ b/arch/parisc/kernel/syscalls/syscall.tbl @@ -468,3 +468,4 @@ 467 common open_tree_attr sys_open_tree_attr 468 common file_getattr sys_file_getattr 469 common file_setattr sys_file_setattr +470 common listns sys_listns diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl index b453e80dfc00..ec4458cdb97b 100644 --- a/arch/powerpc/kernel/syscalls/syscall.tbl +++ b/arch/powerpc/kernel/syscalls/syscall.tbl @@ -560,3 +560,4 @@ 467 common open_tree_attr sys_open_tree_attr 468 common file_getattr sys_file_getattr 469 common file_setattr sys_file_setattr +470 common listns sys_listns diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl index 8a6744d658db..5863787ab036 100644 --- a/arch/s390/kernel/syscalls/syscall.tbl +++ b/arch/s390/kernel/syscalls/syscall.tbl @@ -472,3 +472,4 @@ 467 common open_tree_attr sys_open_tree_attr sys_open_tree_attr 468 common file_getattr sys_file_getattr sys_file_getattr 469 common file_setattr sys_file_setattr sys_file_setattr +470 common listns sys_listns sys_listns diff --git a/arch/sh/kernel/syscalls/syscall.tbl b/arch/sh/kernel/syscalls/syscall.tbl index 5e9c9eff5539..969c11325ade 100644 --- a/arch/sh/kernel/syscalls/syscall.tbl +++ b/arch/sh/kernel/syscalls/syscall.tbl @@ -473,3 +473,4 @@ 467 common open_tree_attr sys_open_tree_attr 468 common file_getattr sys_file_getattr 469 common file_setattr sys_file_setattr +470 common listns sys_listns diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl index ebb7d06d1044..39aa26b6a50b 100644 --- a/arch/sparc/kernel/syscalls/syscall.tbl +++ b/arch/sparc/kernel/syscalls/syscall.tbl @@ -515,3 +515,4 @@ 467 common open_tree_attr sys_open_tree_attr 468 common file_getattr sys_file_getattr 469 common file_setattr sys_file_setattr +470 common listns sys_listns diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl index 4877e16da69a..e979a3eac7a3 100644 --- a/arch/x86/entry/syscalls/syscall_32.tbl +++ b/arch/x86/entry/syscalls/syscall_32.tbl @@ -475,3 +475,4 @@ 467 i386 open_tree_attr sys_open_tree_attr 468 i386 file_getattr sys_file_getattr 469 i386 file_setattr sys_file_setattr +470 i386 listns sys_listns diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl index ced2a1deecd7..8a4ac4841be6 100644 --- a/arch/x86/entry/syscalls/syscall_64.tbl +++ b/arch/x86/entry/syscalls/syscall_64.tbl @@ -394,6 +394,7 @@ 467 common open_tree_attr sys_open_tree_attr 468 common file_getattr sys_file_getattr 469 common file_setattr sys_file_setattr +470 common listns sys_listns # # Due to a historical design error, certain syscalls are numbered differently diff --git a/arch/xtensa/kernel/syscalls/syscall.tbl b/arch/xtensa/kernel/syscalls/syscall.tbl index 374e4cb788d8..438a3b170402 100644 --- a/arch/xtensa/kernel/syscalls/syscall.tbl +++ b/arch/xtensa/kernel/syscalls/syscall.tbl @@ -440,3 +440,4 @@ 467 common open_tree_attr sys_open_tree_attr 468 common file_getattr sys_file_getattr 469 common file_setattr sys_file_setattr +470 common listns sys_listns diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h index 04e0077fb4c9..942370b3f5d2 100644 --- a/include/uapi/asm-generic/unistd.h +++ b/include/uapi/asm-generic/unistd.h @@ -857,9 +857,11 @@ __SYSCALL(__NR_open_tree_attr, sys_open_tree_attr) __SYSCALL(__NR_file_getattr, sys_file_getattr) #define __NR_file_setattr 469 __SYSCALL(__NR_file_setattr, sys_file_setattr) +#define __NR_listns 470 +__SYSCALL(__NR_listns, sys_listns) #undef __NR_syscalls -#define __NR_syscalls 470 +#define __NR_syscalls 471 /* * 32 bit systems traditionally used different diff --git a/scripts/syscall.tbl b/scripts/syscall.tbl index d1ae5e92c615..e74868be513c 100644 --- a/scripts/syscall.tbl +++ b/scripts/syscall.tbl @@ -410,3 +410,4 @@ 467 common open_tree_attr sys_open_tree_attr 468 common file_getattr sys_file_getattr 469 common file_setattr sys_file_setattr +470 common listns sys_listns From 6fc9baa49d0ce36e4c2c27dd9e5fbd387240d8e7 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:34 +0100 Subject: [PATCH 24/75] nsfs: update tools header Ensure all the new uapi bits are visible for the selftests. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-21-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- tools/include/uapi/linux/nsfs.h | 70 +++++++++++++++++++++++++++++++++ 1 file changed, 70 insertions(+) diff --git a/tools/include/uapi/linux/nsfs.h b/tools/include/uapi/linux/nsfs.h index 33c9b578b3b2..a25e38d1c874 100644 --- a/tools/include/uapi/linux/nsfs.h +++ b/tools/include/uapi/linux/nsfs.h @@ -53,6 +53,76 @@ enum init_ns_ino { TIME_NS_INIT_INO = 0xEFFFFFFAU, NET_NS_INIT_INO = 0xEFFFFFF9U, MNT_NS_INIT_INO = 0xEFFFFFF8U, +#ifdef __KERNEL__ + MNT_NS_ANON_INO = 0xEFFFFFF7U, +#endif }; +struct nsfs_file_handle { + __u64 ns_id; + __u32 ns_type; + __u32 ns_inum; +}; + +#define NSFS_FILE_HANDLE_SIZE_VER0 16 /* sizeof first published struct */ +#define NSFS_FILE_HANDLE_SIZE_LATEST sizeof(struct nsfs_file_handle) /* sizeof latest published struct */ + +enum init_ns_id { + IPC_NS_INIT_ID = 1ULL, + UTS_NS_INIT_ID = 2ULL, + USER_NS_INIT_ID = 3ULL, + PID_NS_INIT_ID = 4ULL, + CGROUP_NS_INIT_ID = 5ULL, + TIME_NS_INIT_ID = 6ULL, + NET_NS_INIT_ID = 7ULL, + MNT_NS_INIT_ID = 8ULL, +#ifdef __KERNEL__ + NS_LAST_INIT_ID = MNT_NS_INIT_ID, +#endif +}; + +enum ns_type { + TIME_NS = (1ULL << 7), /* CLONE_NEWTIME */ + MNT_NS = (1ULL << 17), /* CLONE_NEWNS */ + CGROUP_NS = (1ULL << 25), /* CLONE_NEWCGROUP */ + UTS_NS = (1ULL << 26), /* CLONE_NEWUTS */ + IPC_NS = (1ULL << 27), /* CLONE_NEWIPC */ + USER_NS = (1ULL << 28), /* CLONE_NEWUSER */ + PID_NS = (1ULL << 29), /* CLONE_NEWPID */ + NET_NS = (1ULL << 30), /* CLONE_NEWNET */ +}; + +/** + * struct ns_id_req - namespace ID request structure + * @size: size of this structure + * @spare: reserved for future use + * @filter: filter mask + * @ns_id: last namespace id + * @user_ns_id: owning user namespace ID + * + * Structure for passing namespace ID and miscellaneous parameters to + * statns(2) and listns(2). + * + * For statns(2) @param represents the request mask. + * For listns(2) @param represents the last listed mount id (or zero). + */ +struct ns_id_req { + __u32 size; + __u32 spare; + __u64 ns_id; + struct /* listns */ { + __u32 ns_type; + __u32 spare2; + __u64 user_ns_id; + }; +}; + +/* + * Special @user_ns_id value that can be passed to listns() + */ +#define LISTNS_CURRENT_USER 0xffffffffffffffff /* Caller's userns */ + +/* List of all ns_id_req versions. */ +#define NS_ID_REQ_SIZE_VER0 32 /* sizeof first published struct */ + #endif /* __LINUX_NSFS_H */ From e2b6e5eadc13ee5268c20ad7fd4bb638326ea6d4 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:35 +0100 Subject: [PATCH 25/75] selftests/filesystems: remove CLONE_NEWPIDNS from setup_userns() helper This is effectively unused and doesn't really server any purpose after having reviewed all of the tests that rely on it. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-22-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- tools/testing/selftests/filesystems/utils.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/filesystems/utils.c b/tools/testing/selftests/filesystems/utils.c index c43a69dffd83..a0c64f415a7f 100644 --- a/tools/testing/selftests/filesystems/utils.c +++ b/tools/testing/selftests/filesystems/utils.c @@ -487,7 +487,7 @@ int setup_userns(void) uid_t uid = getuid(); gid_t gid = getgid(); - ret = unshare(CLONE_NEWNS|CLONE_NEWUSER|CLONE_NEWPID); + ret = unshare(CLONE_NEWNS|CLONE_NEWUSER); if (ret) { ksft_exit_fail_msg("unsharing mountns and userns: %s\n", strerror(errno)); From 6bdce845fd5add4a69bc7a8101bf1741822d5de0 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:36 +0100 Subject: [PATCH 26/75] selftests/namespaces: first active reference count tests Test that initial namespaces can be reopened via file handle. Initial namespaces should always have a ref count of one from boot. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-23-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- tools/testing/selftests/namespaces/.gitignore | 1 + tools/testing/selftests/namespaces/Makefile | 5 +- .../selftests/namespaces/ns_active_ref_test.c | 74 +++++++++++++++++++ 3 files changed, 79 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/namespaces/ns_active_ref_test.c diff --git a/tools/testing/selftests/namespaces/.gitignore b/tools/testing/selftests/namespaces/.gitignore index ccfb40837a73..100cc5bfef04 100644 --- a/tools/testing/selftests/namespaces/.gitignore +++ b/tools/testing/selftests/namespaces/.gitignore @@ -1,3 +1,4 @@ nsid_test file_handle_test init_ino_test +ns_active_ref_test diff --git a/tools/testing/selftests/namespaces/Makefile b/tools/testing/selftests/namespaces/Makefile index 5fe4b3dc07d3..5cea938cdde8 100644 --- a/tools/testing/selftests/namespaces/Makefile +++ b/tools/testing/selftests/namespaces/Makefile @@ -1,7 +1,10 @@ # SPDX-License-Identifier: GPL-2.0-only CFLAGS += -Wall -O0 -g $(KHDR_INCLUDES) $(TOOLS_INCLUDES) +LDLIBS += -lcap -TEST_GEN_PROGS := nsid_test file_handle_test init_ino_test +TEST_GEN_PROGS := nsid_test file_handle_test init_ino_test ns_active_ref_test include ../lib.mk +$(OUTPUT)/ns_active_ref_test: ../filesystems/utils.c + diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c new file mode 100644 index 000000000000..21514a537b26 --- /dev/null +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -0,0 +1,74 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "../kselftest_harness.h" +#include "../filesystems/utils.h" + +#ifndef FD_NSFS_ROOT +#define FD_NSFS_ROOT -10003 /* Root of the nsfs filesystem */ +#endif + +/* + * Test that initial namespaces can be reopened via file handle. + * Initial namespaces should have active ref count of 1 from boot. + */ +TEST(init_ns_always_active) +{ + struct file_handle *handle; + int mount_id; + int ret; + int fd1, fd2; + struct stat st1, st2; + + handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ); + ASSERT_NE(handle, NULL); + + /* Open initial network namespace */ + fd1 = open("/proc/1/ns/net", O_RDONLY); + ASSERT_GE(fd1, 0); + + /* Get file handle for initial namespace */ + handle->handle_bytes = MAX_HANDLE_SZ; + ret = name_to_handle_at(fd1, "", handle, &mount_id, AT_EMPTY_PATH); + if (ret < 0 && errno == EOPNOTSUPP) { + SKIP(free(handle); close(fd1); + return, "nsfs doesn't support file handles"); + } + ASSERT_EQ(ret, 0); + + /* Close the namespace fd */ + close(fd1); + + /* Try to reopen via file handle - should succeed since init ns is always active */ + fd2 = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + if (fd2 < 0 && (errno == EINVAL || errno == EOPNOTSUPP)) { + SKIP(free(handle); + return, "open_by_handle_at with FD_NSFS_ROOT not supported"); + } + ASSERT_GE(fd2, 0); + + /* Verify we opened the same namespace */ + fd1 = open("/proc/1/ns/net", O_RDONLY); + ASSERT_GE(fd1, 0); + ASSERT_EQ(fstat(fd1, &st1), 0); + ASSERT_EQ(fstat(fd2, &st2), 0); + ASSERT_EQ(st1.st_ino, st2.st_ino); + + close(fd1); + close(fd2); + free(handle); +} + +TEST_HARNESS_MAIN From 721c7e41b184714cb173b04365a168d58522f9fc Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:37 +0100 Subject: [PATCH 27/75] selftests/namespaces: second active reference count tests Test namespace lifecycle: create a namespace in a child process, get a file handle while it's active, then try to reopen after the process exits (namespace becomes inactive). Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-24-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 81 +++++++++++++++++++ 1 file changed, 81 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index 21514a537b26..7cade298c754 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -71,4 +71,85 @@ TEST(init_ns_always_active) free(handle); } +/* + * Test namespace lifecycle: create a namespace in a child process, + * get a file handle while it's active, then try to reopen after + * the process exits (namespace becomes inactive). + */ +TEST(ns_inactive_after_exit) +{ + struct file_handle *handle; + int mount_id; + int ret; + int fd; + int pipefd[2]; + pid_t pid; + int status; + char buf[sizeof(*handle) + MAX_HANDLE_SZ]; + + /* Create pipe for passing file handle from child */ + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child process */ + close(pipefd[0]); + + /* Create new network namespace */ + ret = unshare(CLONE_NEWNET); + if (ret < 0) { + close(pipefd[1]); + exit(1); + } + + /* Open our new namespace */ + fd = open("/proc/self/ns/net", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + /* Get file handle for the namespace */ + handle = (struct file_handle *)buf; + handle->handle_bytes = MAX_HANDLE_SZ; + ret = name_to_handle_at(fd, "", handle, &mount_id, AT_EMPTY_PATH); + close(fd); + + if (ret < 0) { + close(pipefd[1]); + exit(1); + } + + /* Send handle to parent */ + write(pipefd[1], buf, sizeof(*handle) + handle->handle_bytes); + close(pipefd[1]); + + /* Exit - namespace should become inactive */ + exit(0); + } + + /* Parent process */ + close(pipefd[1]); + + /* Read file handle from child */ + ret = read(pipefd[0], buf, sizeof(buf)); + close(pipefd[0]); + + /* Wait for child to exit */ + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + ASSERT_GT(ret, 0); + handle = (struct file_handle *)buf; + + /* Try to reopen namespace - should fail with ENOENT since it's inactive */ + fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + ASSERT_LT(fd, 0); + /* Should fail with ENOENT (namespace inactive) or ESTALE */ + ASSERT_TRUE(errno == ENOENT || errno == ESTALE); +} + TEST_HARNESS_MAIN From c6e25d930b4b6e15e6b16b528e3f14c03c90f14c Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:38 +0100 Subject: [PATCH 28/75] selftests/namespaces: third active reference count tests Test that a namespace remains active while a process is using it, even after the creating process exits. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-25-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 124 ++++++++++++++++++ 1 file changed, 124 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index 7cade298c754..c2e34de7a3a9 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -152,4 +152,128 @@ TEST(ns_inactive_after_exit) ASSERT_TRUE(errno == ENOENT || errno == ESTALE); } +/* + * Test that a namespace remains active while a process is using it, + * even after the creating process exits. + */ +TEST(ns_active_with_multiple_processes) +{ + struct file_handle *handle; + int mount_id; + int ret; + int fd; + int pipefd[2]; + int syncpipe[2]; + pid_t pid1, pid2; + int status; + char buf[sizeof(*handle) + MAX_HANDLE_SZ]; + char sync_byte; + + /* Create pipes for communication */ + ASSERT_EQ(pipe(pipefd), 0); + ASSERT_EQ(pipe(syncpipe), 0); + + pid1 = fork(); + ASSERT_GE(pid1, 0); + + if (pid1 == 0) { + /* First child - creates namespace */ + close(pipefd[0]); + close(syncpipe[1]); + + /* Create new network namespace */ + ret = unshare(CLONE_NEWNET); + if (ret < 0) { + close(pipefd[1]); + close(syncpipe[0]); + exit(1); + } + + /* Open and get handle */ + fd = open("/proc/self/ns/net", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + close(syncpipe[0]); + exit(1); + } + + handle = (struct file_handle *)buf; + handle->handle_bytes = MAX_HANDLE_SZ; + ret = name_to_handle_at(fd, "", handle, &mount_id, AT_EMPTY_PATH); + close(fd); + + if (ret < 0) { + close(pipefd[1]); + close(syncpipe[0]); + exit(1); + } + + /* Send handle to parent */ + write(pipefd[1], buf, sizeof(*handle) + handle->handle_bytes); + close(pipefd[1]); + + /* Wait for signal before exiting */ + read(syncpipe[0], &sync_byte, 1); + close(syncpipe[0]); + exit(0); + } + + /* Parent reads handle */ + close(pipefd[1]); + ret = read(pipefd[0], buf, sizeof(buf)); + close(pipefd[0]); + ASSERT_GT(ret, 0); + + handle = (struct file_handle *)buf; + + /* Create second child that will keep namespace active */ + pid2 = fork(); + ASSERT_GE(pid2, 0); + + if (pid2 == 0) { + /* Second child - reopens the namespace */ + close(syncpipe[0]); + close(syncpipe[1]); + + /* Open the namespace via handle */ + fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + if (fd < 0) { + exit(1); + } + + /* Join the namespace */ + ret = setns(fd, CLONE_NEWNET); + close(fd); + if (ret < 0) { + exit(1); + } + + /* Sleep to keep namespace active */ + sleep(1); + exit(0); + } + + /* Let second child enter the namespace */ + usleep(100000); /* 100ms */ + + /* Signal first child to exit */ + close(syncpipe[0]); + sync_byte = 'X'; + write(syncpipe[1], &sync_byte, 1); + close(syncpipe[1]); + + /* Wait for first child */ + waitpid(pid1, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + + /* Namespace should still be active because second child is using it */ + fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + ASSERT_GE(fd, 0); + close(fd); + + /* Wait for second child */ + waitpid(pid2, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); +} + TEST_HARNESS_MAIN From 28655ff2537e3906a3f86e8ec5d0de76277859c5 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:39 +0100 Subject: [PATCH 29/75] selftests/namespaces: fourth active reference count tests Test user namespace active ref tracking via credential lifecycle. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-26-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 90 +++++++++++++++++++ 1 file changed, 90 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index c2e34de7a3a9..396066e641da 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -276,4 +276,94 @@ TEST(ns_active_with_multiple_processes) ASSERT_TRUE(WIFEXITED(status)); } +/* + * Test user namespace active ref tracking via credential lifecycle + */ +TEST(userns_active_ref_lifecycle) +{ + struct file_handle *handle; + int mount_id; + int ret; + int fd; + int pipefd[2]; + pid_t pid; + int status; + char buf[sizeof(*handle) + MAX_HANDLE_SZ]; + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child process */ + close(pipefd[0]); + + /* Create new user namespace */ + ret = unshare(CLONE_NEWUSER); + if (ret < 0) { + close(pipefd[1]); + exit(1); + } + + /* Set up uid/gid mappings */ + int uid_map_fd = open("/proc/self/uid_map", O_WRONLY); + int gid_map_fd = open("/proc/self/gid_map", O_WRONLY); + int setgroups_fd = open("/proc/self/setgroups", O_WRONLY); + + if (uid_map_fd >= 0 && gid_map_fd >= 0 && setgroups_fd >= 0) { + write(setgroups_fd, "deny", 4); + close(setgroups_fd); + + char mapping[64]; + snprintf(mapping, sizeof(mapping), "0 %d 1", getuid()); + write(uid_map_fd, mapping, strlen(mapping)); + close(uid_map_fd); + + snprintf(mapping, sizeof(mapping), "0 %d 1", getgid()); + write(gid_map_fd, mapping, strlen(mapping)); + close(gid_map_fd); + } + + /* Get file handle */ + fd = open("/proc/self/ns/user", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + handle = (struct file_handle *)buf; + handle->handle_bytes = MAX_HANDLE_SZ; + ret = name_to_handle_at(fd, "", handle, &mount_id, AT_EMPTY_PATH); + close(fd); + + if (ret < 0) { + close(pipefd[1]); + exit(1); + } + + /* Send handle to parent */ + write(pipefd[1], buf, sizeof(*handle) + handle->handle_bytes); + close(pipefd[1]); + exit(0); + } + + /* Parent */ + close(pipefd[1]); + ret = read(pipefd[0], buf, sizeof(buf)); + close(pipefd[0]); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + ASSERT_GT(ret, 0); + handle = (struct file_handle *)buf; + + /* Namespace should be inactive after all tasks exit */ + fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + ASSERT_LT(fd, 0); + ASSERT_TRUE(errno == ENOENT || errno == ESTALE); +} + TEST_HARNESS_MAIN From c4803b255ff9f8e0b72ac3bc4a6fb2f83df325c9 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:40 +0100 Subject: [PATCH 30/75] selftests/namespaces: fifth active reference count tests Test PID namespace active ref tracking Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-27-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 82 +++++++++++++++++++ 1 file changed, 82 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index 396066e641da..f4e92b772f70 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -366,4 +366,86 @@ TEST(userns_active_ref_lifecycle) ASSERT_TRUE(errno == ENOENT || errno == ESTALE); } +/* + * Test PID namespace active ref tracking + */ +TEST(pidns_active_ref_lifecycle) +{ + struct file_handle *handle; + int mount_id; + int ret; + int fd; + int pipefd[2]; + pid_t pid; + int status; + char buf[sizeof(*handle) + MAX_HANDLE_SZ]; + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child process */ + close(pipefd[0]); + + /* Create new PID namespace */ + ret = unshare(CLONE_NEWPID); + if (ret < 0) { + close(pipefd[1]); + exit(1); + } + + /* Fork to actually enter the PID namespace */ + pid_t child = fork(); + if (child < 0) { + close(pipefd[1]); + exit(1); + } + + if (child == 0) { + /* Grandchild - in new PID namespace */ + fd = open("/proc/self/ns/pid", O_RDONLY); + if (fd < 0) { + exit(1); + } + + handle = (struct file_handle *)buf; + handle->handle_bytes = MAX_HANDLE_SZ; + ret = name_to_handle_at(fd, "", handle, &mount_id, AT_EMPTY_PATH); + close(fd); + + if (ret < 0) { + exit(1); + } + + /* Send handle to grandparent */ + write(pipefd[1], buf, sizeof(*handle) + handle->handle_bytes); + close(pipefd[1]); + exit(0); + } + + /* Wait for grandchild */ + waitpid(child, NULL, 0); + exit(0); + } + + /* Parent */ + close(pipefd[1]); + ret = read(pipefd[0], buf, sizeof(buf)); + close(pipefd[0]); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + ASSERT_GT(ret, 0); + handle = (struct file_handle *)buf; + + /* Namespace should be inactive after all processes exit */ + fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + ASSERT_LT(fd, 0); + ASSERT_TRUE(errno == ENOENT || errno == ESTALE); +} + TEST_HARNESS_MAIN From 47a5fd8ce18bee0b08aac119ab81dc4de3b40f3f Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:41 +0100 Subject: [PATCH 31/75] selftests/namespaces: sixth active reference count tests Test that an open file descriptor keeps a namespace active. Even after the creating process exits, the namespace should remain active as long as an fd is held open. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-28-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 155 ++++++++++++++++++ 1 file changed, 155 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index f4e92b772f70..50653096fcb6 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -448,4 +448,159 @@ TEST(pidns_active_ref_lifecycle) ASSERT_TRUE(errno == ENOENT || errno == ESTALE); } +/* + * Test that an open file descriptor keeps a namespace active. + * Even after the creating process exits, the namespace should remain + * active as long as an fd is held open. + */ +TEST(ns_fd_keeps_active) +{ + struct file_handle *handle; + int mount_id; + int ret; + int nsfd; + int pipe_child_ready[2]; + int pipe_parent_ready[2]; + pid_t pid; + int status; + char buf[sizeof(*handle) + MAX_HANDLE_SZ]; + char sync_byte; + char proc_path[64]; + + ASSERT_EQ(pipe(pipe_child_ready), 0); + ASSERT_EQ(pipe(pipe_parent_ready), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child process */ + close(pipe_child_ready[0]); + close(pipe_parent_ready[1]); + + TH_LOG("Child: creating new network namespace"); + + /* Create new network namespace */ + ret = unshare(CLONE_NEWNET); + if (ret < 0) { + TH_LOG("Child: unshare(CLONE_NEWNET) failed: %s", strerror(errno)); + close(pipe_child_ready[1]); + close(pipe_parent_ready[0]); + exit(1); + } + + TH_LOG("Child: network namespace created successfully"); + + /* Get file handle for the namespace */ + nsfd = open("/proc/self/ns/net", O_RDONLY); + if (nsfd < 0) { + TH_LOG("Child: failed to open /proc/self/ns/net: %s", strerror(errno)); + close(pipe_child_ready[1]); + close(pipe_parent_ready[0]); + exit(1); + } + + TH_LOG("Child: opened namespace fd %d", nsfd); + + handle = (struct file_handle *)buf; + handle->handle_bytes = MAX_HANDLE_SZ; + ret = name_to_handle_at(nsfd, "", handle, &mount_id, AT_EMPTY_PATH); + close(nsfd); + + if (ret < 0) { + TH_LOG("Child: name_to_handle_at failed: %s", strerror(errno)); + close(pipe_child_ready[1]); + close(pipe_parent_ready[0]); + exit(1); + } + + TH_LOG("Child: got file handle (bytes=%u)", handle->handle_bytes); + + /* Send file handle to parent */ + ret = write(pipe_child_ready[1], buf, sizeof(*handle) + handle->handle_bytes); + TH_LOG("Child: sent %d bytes of file handle to parent", ret); + close(pipe_child_ready[1]); + + /* Wait for parent to open the fd */ + TH_LOG("Child: waiting for parent to open fd"); + ret = read(pipe_parent_ready[0], &sync_byte, 1); + close(pipe_parent_ready[0]); + + TH_LOG("Child: parent signaled (read %d bytes), exiting now", ret); + /* Exit - namespace should stay active because parent holds fd */ + exit(0); + } + + /* Parent process */ + close(pipe_child_ready[1]); + close(pipe_parent_ready[0]); + + TH_LOG("Parent: reading file handle from child"); + + /* Read file handle from child */ + ret = read(pipe_child_ready[0], buf, sizeof(buf)); + close(pipe_child_ready[0]); + ASSERT_GT(ret, 0); + handle = (struct file_handle *)buf; + + TH_LOG("Parent: received %d bytes, handle size=%u", ret, handle->handle_bytes); + + /* Open the child's namespace while it's still alive */ + snprintf(proc_path, sizeof(proc_path), "/proc/%d/ns/net", pid); + TH_LOG("Parent: opening child's namespace at %s", proc_path); + nsfd = open(proc_path, O_RDONLY); + if (nsfd < 0) { + TH_LOG("Parent: failed to open %s: %s", proc_path, strerror(errno)); + close(pipe_parent_ready[1]); + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to open child's namespace"); + } + + TH_LOG("Parent: opened child's namespace, got fd %d", nsfd); + + /* Signal child that we have the fd */ + sync_byte = 'G'; + write(pipe_parent_ready[1], &sync_byte, 1); + close(pipe_parent_ready[1]); + TH_LOG("Parent: signaled child that we have the fd"); + + /* Wait for child to exit */ + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + TH_LOG("Child exited, parent holds fd %d to namespace", nsfd); + + /* + * Namespace should still be ACTIVE because we hold an fd. + * We should be able to reopen it via file handle. + */ + TH_LOG("Attempting to reopen namespace via file handle (should succeed - fd held)"); + int fd2 = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + ASSERT_GE(fd2, 0); + + TH_LOG("Successfully reopened namespace via file handle, got fd %d", fd2); + + /* Verify it's the same namespace */ + struct stat st1, st2; + ASSERT_EQ(fstat(nsfd, &st1), 0); + ASSERT_EQ(fstat(fd2, &st2), 0); + TH_LOG("Namespace inodes: nsfd=%lu, fd2=%lu", st1.st_ino, st2.st_ino); + ASSERT_EQ(st1.st_ino, st2.st_ino); + close(fd2); + + /* Now close the fd - namespace should become inactive */ + TH_LOG("Closing fd %d - namespace should become inactive", nsfd); + close(nsfd); + + /* Now reopening should fail - namespace is inactive */ + TH_LOG("Attempting to reopen namespace via file handle (should fail - inactive)"); + fd2 = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + ASSERT_LT(fd2, 0); + /* Should fail with ENOENT (inactive) or ESTALE (gone) */ + TH_LOG("Reopen failed as expected: %s (errno=%d)", strerror(errno), errno); + ASSERT_TRUE(errno == ENOENT || errno == ESTALE); +} + TEST_HARNESS_MAIN From 4b971b07e4b4ed7f2e65f7075c7d07c0337360a1 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:42 +0100 Subject: [PATCH 32/75] selftests/namespaces: seventh active reference count tests Test hierarchical active reference propagation. When a child namespace is active, its owning user namespace should also be active automatically due to hierarchical active reference propagation. This ensures parents are always reachable when children are active. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-29-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 222 ++++++++++++++++++ 1 file changed, 222 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index 50653096fcb6..60876965dd71 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -20,6 +20,10 @@ #define FD_NSFS_ROOT -10003 /* Root of the nsfs filesystem */ #endif +#ifndef FILEID_NSFS +#define FILEID_NSFS 0xf1 +#endif + /* * Test that initial namespaces can be reopened via file handle. * Initial namespaces should have active ref count of 1 from boot. @@ -603,4 +607,222 @@ TEST(ns_fd_keeps_active) ASSERT_TRUE(errno == ENOENT || errno == ESTALE); } +/* + * Test hierarchical active reference propagation. + * When a child namespace is active, its owning user namespace should also + * be active automatically due to hierarchical active reference propagation. + * This ensures parents are always reachable when children are active. + */ +TEST(ns_parent_always_reachable) +{ + struct file_handle *parent_handle, *child_handle; + int ret; + int child_nsfd; + int pipefd[2]; + pid_t pid; + int status; + __u64 parent_id, child_id; + char parent_buf[sizeof(*parent_handle) + MAX_HANDLE_SZ]; + char child_buf[sizeof(*child_handle) + MAX_HANDLE_SZ]; + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child process */ + close(pipefd[0]); + + TH_LOG("Child: creating parent user namespace and setting up mappings"); + + /* Create parent user namespace with mappings */ + ret = setup_userns(); + if (ret < 0) { + TH_LOG("Child: setup_userns() for parent failed: %s", strerror(errno)); + close(pipefd[1]); + exit(1); + } + + TH_LOG("Child: parent user namespace created, now uid=%d gid=%d", getuid(), getgid()); + + /* Get namespace ID for parent user namespace */ + int parent_fd = open("/proc/self/ns/user", O_RDONLY); + if (parent_fd < 0) { + TH_LOG("Child: failed to open parent /proc/self/ns/user: %s", strerror(errno)); + close(pipefd[1]); + exit(1); + } + + TH_LOG("Child: opened parent userns fd %d", parent_fd); + + if (ioctl(parent_fd, NS_GET_ID, &parent_id) < 0) { + TH_LOG("Child: NS_GET_ID for parent failed: %s", strerror(errno)); + close(parent_fd); + close(pipefd[1]); + exit(1); + } + close(parent_fd); + + TH_LOG("Child: got parent namespace ID %llu", (unsigned long long)parent_id); + + /* Create child user namespace within parent */ + TH_LOG("Child: creating nested child user namespace"); + ret = setup_userns(); + if (ret < 0) { + TH_LOG("Child: setup_userns() for child failed: %s", strerror(errno)); + close(pipefd[1]); + exit(1); + } + + TH_LOG("Child: nested child user namespace created, uid=%d gid=%d", getuid(), getgid()); + + /* Get namespace ID for child user namespace */ + int child_fd = open("/proc/self/ns/user", O_RDONLY); + if (child_fd < 0) { + TH_LOG("Child: failed to open child /proc/self/ns/user: %s", strerror(errno)); + close(pipefd[1]); + exit(1); + } + + TH_LOG("Child: opened child userns fd %d", child_fd); + + if (ioctl(child_fd, NS_GET_ID, &child_id) < 0) { + TH_LOG("Child: NS_GET_ID for child failed: %s", strerror(errno)); + close(child_fd); + close(pipefd[1]); + exit(1); + } + close(child_fd); + + TH_LOG("Child: got child namespace ID %llu", (unsigned long long)child_id); + + /* Send both namespace IDs to parent */ + TH_LOG("Child: sending both namespace IDs to parent"); + write(pipefd[1], &parent_id, sizeof(parent_id)); + write(pipefd[1], &child_id, sizeof(child_id)); + close(pipefd[1]); + + TH_LOG("Child: exiting - parent userns should become inactive"); + /* Exit - parent user namespace should become inactive */ + exit(0); + } + + /* Parent process */ + close(pipefd[1]); + + TH_LOG("Parent: reading both namespace IDs from child"); + + /* Read both namespace IDs - fixed size, no parsing needed */ + ret = read(pipefd[0], &parent_id, sizeof(parent_id)); + if (ret != sizeof(parent_id)) { + close(pipefd[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read parent namespace ID from child"); + } + + ret = read(pipefd[0], &child_id, sizeof(child_id)); + close(pipefd[0]); + if (ret != sizeof(child_id)) { + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read child namespace ID from child"); + } + + TH_LOG("Parent: received parent_id=%llu, child_id=%llu", + (unsigned long long)parent_id, (unsigned long long)child_id); + + /* Construct file handles from namespace IDs */ + parent_handle = (struct file_handle *)parent_buf; + parent_handle->handle_bytes = sizeof(struct nsfs_file_handle); + parent_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *parent_fh = (struct nsfs_file_handle *)parent_handle->f_handle; + parent_fh->ns_id = parent_id; + parent_fh->ns_type = 0; + parent_fh->ns_inum = 0; + + child_handle = (struct file_handle *)child_buf; + child_handle->handle_bytes = sizeof(struct nsfs_file_handle); + child_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *child_fh = (struct nsfs_file_handle *)child_handle->f_handle; + child_fh->ns_id = child_id; + child_fh->ns_type = 0; + child_fh->ns_inum = 0; + + TH_LOG("Parent: opening child namespace BEFORE child exits"); + + /* Open child namespace while child is still alive to keep it active */ + child_nsfd = open_by_handle_at(FD_NSFS_ROOT, child_handle, O_RDONLY); + if (child_nsfd < 0) { + TH_LOG("Failed to open child namespace: %s (errno=%d)", strerror(errno), errno); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to open child namespace"); + } + + TH_LOG("Opened child namespace fd %d", child_nsfd); + + /* Now wait for child to exit */ + TH_LOG("Parent: waiting for child to exit"); + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + TH_LOG("Child process exited, parent holds fd to child namespace"); + + /* + * With hierarchical active reference propagation: + * Since the child namespace is active (parent process holds fd), + * the parent user namespace should ALSO be active automatically. + * This is because when we took an active reference on the child, + * it propagated up to the owning user namespace. + */ + TH_LOG("Attempting to reopen parent namespace (should SUCCEED - hierarchical propagation)"); + int parent_fd = open_by_handle_at(FD_NSFS_ROOT, parent_handle, O_RDONLY); + ASSERT_GE(parent_fd, 0); + + TH_LOG("SUCCESS: Parent namespace is active (fd=%d) due to active child", parent_fd); + + /* Verify we can also get parent via NS_GET_USERNS */ + TH_LOG("Verifying NS_GET_USERNS also works"); + int parent_fd2 = ioctl(child_nsfd, NS_GET_USERNS); + if (parent_fd2 < 0) { + close(parent_fd); + close(child_nsfd); + TH_LOG("NS_GET_USERNS failed: %s (errno=%d)", strerror(errno), errno); + SKIP(return, "NS_GET_USERNS not supported or failed"); + } + + TH_LOG("NS_GET_USERNS succeeded, got parent fd %d", parent_fd2); + + /* Verify both methods give us the same namespace */ + struct stat st1, st2; + ASSERT_EQ(fstat(parent_fd, &st1), 0); + ASSERT_EQ(fstat(parent_fd2, &st2), 0); + TH_LOG("Parent namespace inodes: parent_fd=%lu, parent_fd2=%lu", st1.st_ino, st2.st_ino); + ASSERT_EQ(st1.st_ino, st2.st_ino); + + /* + * Close child fd - parent should remain active because we still + * hold direct references to it (parent_fd and parent_fd2). + */ + TH_LOG("Closing child fd - parent should remain active (direct refs held)"); + close(child_nsfd); + + /* Parent should still be openable */ + TH_LOG("Verifying parent still active via file handle"); + int parent_fd3 = open_by_handle_at(FD_NSFS_ROOT, parent_handle, O_RDONLY); + ASSERT_GE(parent_fd3, 0); + close(parent_fd3); + + TH_LOG("Closing all fds to parent namespace"); + close(parent_fd); + close(parent_fd2); + + /* Both should now be inactive */ + TH_LOG("Attempting to reopen parent (should fail - inactive, no refs)"); + parent_fd = open_by_handle_at(FD_NSFS_ROOT, parent_handle, O_RDONLY); + ASSERT_LT(parent_fd, 0); + TH_LOG("Parent inactive as expected: %s (errno=%d)", strerror(errno), errno); + ASSERT_TRUE(errno == ENOENT || errno == ESTALE); +} + TEST_HARNESS_MAIN From 94f87110807ae36a1007886b70dfb46e100112b0 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:43 +0100 Subject: [PATCH 33/75] selftests/namespaces: eigth active reference count tests Test that bind mounts keep namespaces in the tree even when inactive Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-30-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 117 ++++++++++++++++++ 1 file changed, 117 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index 60876965dd71..55a741d32b08 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -825,4 +825,121 @@ TEST(ns_parent_always_reachable) ASSERT_TRUE(errno == ENOENT || errno == ESTALE); } +/* + * Test that bind mounts keep namespaces in the tree even when inactive + */ +TEST(ns_bind_mount_keeps_in_tree) +{ + struct file_handle *handle; + int mount_id; + int ret; + int fd; + int pipefd[2]; + pid_t pid; + int status; + char buf[sizeof(*handle) + MAX_HANDLE_SZ]; + char tmpfile[] = "/tmp/ns-test-XXXXXX"; + int tmpfd; + + /* Create temporary file for bind mount */ + tmpfd = mkstemp(tmpfile); + if (tmpfd < 0) { + SKIP(return, "Cannot create temporary file"); + } + close(tmpfd); + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child process */ + close(pipefd[0]); + + /* Unshare mount namespace and make mounts private to avoid propagation */ + ret = unshare(CLONE_NEWNS); + if (ret < 0) { + close(pipefd[1]); + unlink(tmpfile); + exit(1); + } + ret = mount(NULL, "/", NULL, MS_PRIVATE | MS_REC, NULL); + if (ret < 0) { + close(pipefd[1]); + unlink(tmpfile); + exit(1); + } + + /* Create new network namespace */ + ret = unshare(CLONE_NEWNET); + if (ret < 0) { + close(pipefd[1]); + unlink(tmpfile); + exit(1); + } + + /* Bind mount the namespace */ + ret = mount("/proc/self/ns/net", tmpfile, NULL, MS_BIND, NULL); + if (ret < 0) { + close(pipefd[1]); + unlink(tmpfile); + exit(1); + } + + /* Get file handle */ + fd = open("/proc/self/ns/net", O_RDONLY); + if (fd < 0) { + umount(tmpfile); + close(pipefd[1]); + unlink(tmpfile); + exit(1); + } + + handle = (struct file_handle *)buf; + handle->handle_bytes = MAX_HANDLE_SZ; + ret = name_to_handle_at(fd, "", handle, &mount_id, AT_EMPTY_PATH); + close(fd); + + if (ret < 0) { + umount(tmpfile); + close(pipefd[1]); + unlink(tmpfile); + exit(1); + } + + /* Send handle to parent */ + write(pipefd[1], buf, sizeof(*handle) + handle->handle_bytes); + close(pipefd[1]); + exit(0); + } + + /* Parent */ + close(pipefd[1]); + ret = read(pipefd[0], buf, sizeof(buf)); + close(pipefd[0]); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + ASSERT_GT(ret, 0); + handle = (struct file_handle *)buf; + + /* + * Namespace should be inactive but still in tree due to bind mount. + * Reopening should fail with ENOENT (inactive) not ESTALE (not in tree). + */ + fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + ASSERT_LT(fd, 0); + /* Should be ENOENT (inactive) since bind mount keeps it in tree */ + if (errno != ENOENT && errno != ESTALE) { + TH_LOG("Unexpected error: %d", errno); + } + + /* Cleanup */ + umount(tmpfile); + unlink(tmpfile); +} + TEST_HARNESS_MAIN From a8ce47a1ac4b1fad5038663c62223490c0666135 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:44 +0100 Subject: [PATCH 34/75] selftests/namespaces: ninth active reference count tests MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Test multi-level hierarchy (3+ levels deep). Grandparent → Parent → Child When child is active, both parent AND grandparent should be active. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-31-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 164 ++++++++++++++++++ 1 file changed, 164 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index 55a741d32b08..88189398aa35 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -942,4 +942,168 @@ TEST(ns_bind_mount_keeps_in_tree) unlink(tmpfile); } +/* + * Test multi-level hierarchy (3+ levels deep). + * Grandparent → Parent → Child + * When child is active, both parent AND grandparent should be active. + */ +TEST(ns_multilevel_hierarchy) +{ + struct file_handle *gp_handle, *p_handle, *c_handle; + int ret, pipefd[2]; + pid_t pid; + int status; + __u64 gp_id, p_id, c_id; + char gp_buf[sizeof(*gp_handle) + MAX_HANDLE_SZ]; + char p_buf[sizeof(*p_handle) + MAX_HANDLE_SZ]; + char c_buf[sizeof(*c_handle) + MAX_HANDLE_SZ]; + + ASSERT_EQ(pipe(pipefd), 0); + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + close(pipefd[0]); + + /* Create grandparent user namespace */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + int gp_fd = open("/proc/self/ns/user", O_RDONLY); + if (gp_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(gp_fd, NS_GET_ID, &gp_id) < 0) { + close(gp_fd); + close(pipefd[1]); + exit(1); + } + close(gp_fd); + + /* Create parent user namespace */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + int p_fd = open("/proc/self/ns/user", O_RDONLY); + if (p_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(p_fd, NS_GET_ID, &p_id) < 0) { + close(p_fd); + close(pipefd[1]); + exit(1); + } + close(p_fd); + + /* Create child user namespace */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + int c_fd = open("/proc/self/ns/user", O_RDONLY); + if (c_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(c_fd, NS_GET_ID, &c_id) < 0) { + close(c_fd); + close(pipefd[1]); + exit(1); + } + close(c_fd); + + /* Send all three namespace IDs */ + write(pipefd[1], &gp_id, sizeof(gp_id)); + write(pipefd[1], &p_id, sizeof(p_id)); + write(pipefd[1], &c_id, sizeof(c_id)); + close(pipefd[1]); + exit(0); + } + + close(pipefd[1]); + + /* Read all three namespace IDs - fixed size, no parsing needed */ + ret = read(pipefd[0], &gp_id, sizeof(gp_id)); + if (ret != sizeof(gp_id)) { + close(pipefd[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read grandparent namespace ID from child"); + } + + ret = read(pipefd[0], &p_id, sizeof(p_id)); + if (ret != sizeof(p_id)) { + close(pipefd[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read parent namespace ID from child"); + } + + ret = read(pipefd[0], &c_id, sizeof(c_id)); + close(pipefd[0]); + if (ret != sizeof(c_id)) { + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read child namespace ID from child"); + } + + /* Construct file handles from namespace IDs */ + gp_handle = (struct file_handle *)gp_buf; + gp_handle->handle_bytes = sizeof(struct nsfs_file_handle); + gp_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *gp_fh = (struct nsfs_file_handle *)gp_handle->f_handle; + gp_fh->ns_id = gp_id; + gp_fh->ns_type = 0; + gp_fh->ns_inum = 0; + + p_handle = (struct file_handle *)p_buf; + p_handle->handle_bytes = sizeof(struct nsfs_file_handle); + p_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *p_fh = (struct nsfs_file_handle *)p_handle->f_handle; + p_fh->ns_id = p_id; + p_fh->ns_type = 0; + p_fh->ns_inum = 0; + + c_handle = (struct file_handle *)c_buf; + c_handle->handle_bytes = sizeof(struct nsfs_file_handle); + c_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *c_fh = (struct nsfs_file_handle *)c_handle->f_handle; + c_fh->ns_id = c_id; + c_fh->ns_type = 0; + c_fh->ns_inum = 0; + + /* Open child before process exits */ + int c_fd = open_by_handle_at(FD_NSFS_ROOT, c_handle, O_RDONLY); + if (c_fd < 0) { + waitpid(pid, NULL, 0); + SKIP(return, "Failed to open child namespace"); + } + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* + * With 3-level hierarchy and child active: + * - Child is active (we hold fd) + * - Parent should be active (propagated from child) + * - Grandparent should be active (propagated from parent) + */ + TH_LOG("Testing parent active when child is active"); + int p_fd = open_by_handle_at(FD_NSFS_ROOT, p_handle, O_RDONLY); + ASSERT_GE(p_fd, 0); + + TH_LOG("Testing grandparent active when child is active"); + int gp_fd = open_by_handle_at(FD_NSFS_ROOT, gp_handle, O_RDONLY); + ASSERT_GE(gp_fd, 0); + + close(c_fd); + close(p_fd); + close(gp_fd); +} + TEST_HARNESS_MAIN From e7585a9ef5bedf059e9cde57c31c86befb8ba21e Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:45 +0100 Subject: [PATCH 35/75] selftests/namespaces: tenth active reference count tests Test multiple children sharing same parent. Parent should stay active as long as ANY child is active. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-32-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 170 ++++++++++++++++++ 1 file changed, 170 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index 88189398aa35..a334792da982 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -1106,4 +1106,174 @@ TEST(ns_multilevel_hierarchy) close(gp_fd); } +/* + * Test multiple children sharing same parent. + * Parent should stay active as long as ANY child is active. + */ +TEST(ns_multiple_children_same_parent) +{ + struct file_handle *p_handle, *c1_handle, *c2_handle; + int ret, pipefd[2]; + pid_t pid; + int status; + __u64 p_id, c1_id, c2_id; + char p_buf[sizeof(*p_handle) + MAX_HANDLE_SZ]; + char c1_buf[sizeof(*c1_handle) + MAX_HANDLE_SZ]; + char c2_buf[sizeof(*c2_handle) + MAX_HANDLE_SZ]; + + ASSERT_EQ(pipe(pipefd), 0); + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + close(pipefd[0]); + + /* Create parent user namespace */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + int p_fd = open("/proc/self/ns/user", O_RDONLY); + if (p_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(p_fd, NS_GET_ID, &p_id) < 0) { + close(p_fd); + close(pipefd[1]); + exit(1); + } + close(p_fd); + + /* Create first child user namespace */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + int c1_fd = open("/proc/self/ns/user", O_RDONLY); + if (c1_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(c1_fd, NS_GET_ID, &c1_id) < 0) { + close(c1_fd); + close(pipefd[1]); + exit(1); + } + close(c1_fd); + + /* Return to parent user namespace and create second child */ + /* We can't actually do this easily, so let's create a sibling namespace + * by creating a network namespace instead */ + if (unshare(CLONE_NEWNET) < 0) { + close(pipefd[1]); + exit(1); + } + + int c2_fd = open("/proc/self/ns/net", O_RDONLY); + if (c2_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(c2_fd, NS_GET_ID, &c2_id) < 0) { + close(c2_fd); + close(pipefd[1]); + exit(1); + } + close(c2_fd); + + /* Send all namespace IDs */ + write(pipefd[1], &p_id, sizeof(p_id)); + write(pipefd[1], &c1_id, sizeof(c1_id)); + write(pipefd[1], &c2_id, sizeof(c2_id)); + close(pipefd[1]); + exit(0); + } + + close(pipefd[1]); + + /* Read all three namespace IDs - fixed size, no parsing needed */ + ret = read(pipefd[0], &p_id, sizeof(p_id)); + if (ret != sizeof(p_id)) { + close(pipefd[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read parent namespace ID"); + } + + ret = read(pipefd[0], &c1_id, sizeof(c1_id)); + if (ret != sizeof(c1_id)) { + close(pipefd[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read first child namespace ID"); + } + + ret = read(pipefd[0], &c2_id, sizeof(c2_id)); + close(pipefd[0]); + if (ret != sizeof(c2_id)) { + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read second child namespace ID"); + } + + /* Construct file handles from namespace IDs */ + p_handle = (struct file_handle *)p_buf; + p_handle->handle_bytes = sizeof(struct nsfs_file_handle); + p_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *p_fh = (struct nsfs_file_handle *)p_handle->f_handle; + p_fh->ns_id = p_id; + p_fh->ns_type = 0; + p_fh->ns_inum = 0; + + c1_handle = (struct file_handle *)c1_buf; + c1_handle->handle_bytes = sizeof(struct nsfs_file_handle); + c1_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *c1_fh = (struct nsfs_file_handle *)c1_handle->f_handle; + c1_fh->ns_id = c1_id; + c1_fh->ns_type = 0; + c1_fh->ns_inum = 0; + + c2_handle = (struct file_handle *)c2_buf; + c2_handle->handle_bytes = sizeof(struct nsfs_file_handle); + c2_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *c2_fh = (struct nsfs_file_handle *)c2_handle->f_handle; + c2_fh->ns_id = c2_id; + c2_fh->ns_type = 0; + c2_fh->ns_inum = 0; + + /* Open both children before process exits */ + int c1_fd = open_by_handle_at(FD_NSFS_ROOT, c1_handle, O_RDONLY); + int c2_fd = open_by_handle_at(FD_NSFS_ROOT, c2_handle, O_RDONLY); + + if (c1_fd < 0 || c2_fd < 0) { + if (c1_fd >= 0) close(c1_fd); + if (c2_fd >= 0) close(c2_fd); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to open child namespaces"); + } + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* Parent should be active (both children active) */ + TH_LOG("Both children active - parent should be active"); + int p_fd = open_by_handle_at(FD_NSFS_ROOT, p_handle, O_RDONLY); + ASSERT_GE(p_fd, 0); + close(p_fd); + + /* Close first child - parent should STILL be active */ + TH_LOG("Closing first child - parent should still be active"); + close(c1_fd); + p_fd = open_by_handle_at(FD_NSFS_ROOT, p_handle, O_RDONLY); + ASSERT_GE(p_fd, 0); + close(p_fd); + + /* Close second child - NOW parent should become inactive */ + TH_LOG("Closing second child - parent should become inactive"); + close(c2_fd); + p_fd = open_by_handle_at(FD_NSFS_ROOT, p_handle, O_RDONLY); + ASSERT_LT(p_fd, 0); +} + TEST_HARNESS_MAIN From 26d238ea6a3424413a5f1cc89180e16ec4c4e22b Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:46 +0100 Subject: [PATCH 36/75] selftests/namespaces: eleventh active reference count tests Test that different namespace types with same owner all contribute active references to the owning user namespace. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-33-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 171 ++++++++++++++++++ 1 file changed, 171 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index a334792da982..885f58c81247 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -1276,4 +1276,175 @@ TEST(ns_multiple_children_same_parent) ASSERT_LT(p_fd, 0); } +/* + * Test that different namespace types with same owner all contribute + * active references to the owning user namespace. + */ +TEST(ns_different_types_same_owner) +{ + struct file_handle *u_handle, *n_handle, *ut_handle; + int ret, pipefd[2]; + pid_t pid; + int status; + __u64 u_id, n_id, ut_id; + char u_buf[sizeof(*u_handle) + MAX_HANDLE_SZ]; + char n_buf[sizeof(*n_handle) + MAX_HANDLE_SZ]; + char ut_buf[sizeof(*ut_handle) + MAX_HANDLE_SZ]; + + ASSERT_EQ(pipe(pipefd), 0); + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + close(pipefd[0]); + + /* Create user namespace */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + int u_fd = open("/proc/self/ns/user", O_RDONLY); + if (u_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(u_fd, NS_GET_ID, &u_id) < 0) { + close(u_fd); + close(pipefd[1]); + exit(1); + } + close(u_fd); + + /* Create network namespace (owned by user namespace) */ + if (unshare(CLONE_NEWNET) < 0) { + close(pipefd[1]); + exit(1); + } + + int n_fd = open("/proc/self/ns/net", O_RDONLY); + if (n_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(n_fd, NS_GET_ID, &n_id) < 0) { + close(n_fd); + close(pipefd[1]); + exit(1); + } + close(n_fd); + + /* Create UTS namespace (also owned by user namespace) */ + if (unshare(CLONE_NEWUTS) < 0) { + close(pipefd[1]); + exit(1); + } + + int ut_fd = open("/proc/self/ns/uts", O_RDONLY); + if (ut_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(ut_fd, NS_GET_ID, &ut_id) < 0) { + close(ut_fd); + close(pipefd[1]); + exit(1); + } + close(ut_fd); + + /* Send all namespace IDs */ + write(pipefd[1], &u_id, sizeof(u_id)); + write(pipefd[1], &n_id, sizeof(n_id)); + write(pipefd[1], &ut_id, sizeof(ut_id)); + close(pipefd[1]); + exit(0); + } + + close(pipefd[1]); + + /* Read all three namespace IDs - fixed size, no parsing needed */ + ret = read(pipefd[0], &u_id, sizeof(u_id)); + if (ret != sizeof(u_id)) { + close(pipefd[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read user namespace ID"); + } + + ret = read(pipefd[0], &n_id, sizeof(n_id)); + if (ret != sizeof(n_id)) { + close(pipefd[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read network namespace ID"); + } + + ret = read(pipefd[0], &ut_id, sizeof(ut_id)); + close(pipefd[0]); + if (ret != sizeof(ut_id)) { + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read UTS namespace ID"); + } + + /* Construct file handles from namespace IDs */ + u_handle = (struct file_handle *)u_buf; + u_handle->handle_bytes = sizeof(struct nsfs_file_handle); + u_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *u_fh = (struct nsfs_file_handle *)u_handle->f_handle; + u_fh->ns_id = u_id; + u_fh->ns_type = 0; + u_fh->ns_inum = 0; + + n_handle = (struct file_handle *)n_buf; + n_handle->handle_bytes = sizeof(struct nsfs_file_handle); + n_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *n_fh = (struct nsfs_file_handle *)n_handle->f_handle; + n_fh->ns_id = n_id; + n_fh->ns_type = 0; + n_fh->ns_inum = 0; + + ut_handle = (struct file_handle *)ut_buf; + ut_handle->handle_bytes = sizeof(struct nsfs_file_handle); + ut_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *ut_fh = (struct nsfs_file_handle *)ut_handle->f_handle; + ut_fh->ns_id = ut_id; + ut_fh->ns_type = 0; + ut_fh->ns_inum = 0; + + /* Open both non-user namespaces before process exits */ + int n_fd = open_by_handle_at(FD_NSFS_ROOT, n_handle, O_RDONLY); + int ut_fd = open_by_handle_at(FD_NSFS_ROOT, ut_handle, O_RDONLY); + + if (n_fd < 0 || ut_fd < 0) { + if (n_fd >= 0) close(n_fd); + if (ut_fd >= 0) close(ut_fd); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to open namespaces"); + } + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* + * Both network and UTS namespaces are active. + * User namespace should be active (gets 2 active refs). + */ + TH_LOG("Both net and uts active - user namespace should be active"); + int u_fd = open_by_handle_at(FD_NSFS_ROOT, u_handle, O_RDONLY); + ASSERT_GE(u_fd, 0); + close(u_fd); + + /* Close network namespace - user namespace should STILL be active */ + TH_LOG("Closing network ns - user ns should still be active (uts still active)"); + close(n_fd); + u_fd = open_by_handle_at(FD_NSFS_ROOT, u_handle, O_RDONLY); + ASSERT_GE(u_fd, 0); + close(u_fd); + + /* Close UTS namespace - user namespace should become inactive */ + TH_LOG("Closing uts ns - user ns should become inactive"); + close(ut_fd); + u_fd = open_by_handle_at(FD_NSFS_ROOT, u_handle, O_RDONLY); + ASSERT_LT(u_fd, 0); +} + TEST_HARNESS_MAIN From 04aee1a3462dbebd13d0fab343490406f69d530b Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:47 +0100 Subject: [PATCH 37/75] selftests/namespaces: twelth active reference count tests Test hierarchical propagation with deep namespace hierarchy. Create: init_user_ns -> user_A -> user_B -> net_ns When net_ns is active, both user_A and user_B should be active. This verifies the conditional recursion in __ns_ref_active_put() works. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-34-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 176 ++++++++++++++++++ 1 file changed, 176 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index 885f58c81247..b1a454dac9d0 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -1447,4 +1447,180 @@ TEST(ns_different_types_same_owner) ASSERT_LT(u_fd, 0); } +/* + * Test hierarchical propagation with deep namespace hierarchy. + * Create: init_user_ns -> user_A -> user_B -> net_ns + * When net_ns is active, both user_A and user_B should be active. + * This verifies the conditional recursion in __ns_ref_active_put() works. + */ +TEST(ns_deep_hierarchy_propagation) +{ + struct file_handle *ua_handle, *ub_handle, *net_handle; + int ret, pipefd[2]; + pid_t pid; + int status; + __u64 ua_id, ub_id, net_id; + char ua_buf[sizeof(*ua_handle) + MAX_HANDLE_SZ]; + char ub_buf[sizeof(*ub_handle) + MAX_HANDLE_SZ]; + char net_buf[sizeof(*net_handle) + MAX_HANDLE_SZ]; + + ASSERT_EQ(pipe(pipefd), 0); + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + close(pipefd[0]); + + /* Create user_A -> user_B -> net hierarchy */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + int ua_fd = open("/proc/self/ns/user", O_RDONLY); + if (ua_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(ua_fd, NS_GET_ID, &ua_id) < 0) { + close(ua_fd); + close(pipefd[1]); + exit(1); + } + close(ua_fd); + + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + int ub_fd = open("/proc/self/ns/user", O_RDONLY); + if (ub_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(ub_fd, NS_GET_ID, &ub_id) < 0) { + close(ub_fd); + close(pipefd[1]); + exit(1); + } + close(ub_fd); + + if (unshare(CLONE_NEWNET) < 0) { + close(pipefd[1]); + exit(1); + } + + int net_fd = open("/proc/self/ns/net", O_RDONLY); + if (net_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(net_fd, NS_GET_ID, &net_id) < 0) { + close(net_fd); + close(pipefd[1]); + exit(1); + } + close(net_fd); + + /* Send all three namespace IDs */ + write(pipefd[1], &ua_id, sizeof(ua_id)); + write(pipefd[1], &ub_id, sizeof(ub_id)); + write(pipefd[1], &net_id, sizeof(net_id)); + close(pipefd[1]); + exit(0); + } + + close(pipefd[1]); + + /* Read all three namespace IDs - fixed size, no parsing needed */ + ret = read(pipefd[0], &ua_id, sizeof(ua_id)); + if (ret != sizeof(ua_id)) { + close(pipefd[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read user_A namespace ID"); + } + + ret = read(pipefd[0], &ub_id, sizeof(ub_id)); + if (ret != sizeof(ub_id)) { + close(pipefd[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read user_B namespace ID"); + } + + ret = read(pipefd[0], &net_id, sizeof(net_id)); + close(pipefd[0]); + if (ret != sizeof(net_id)) { + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read network namespace ID"); + } + + /* Construct file handles from namespace IDs */ + ua_handle = (struct file_handle *)ua_buf; + ua_handle->handle_bytes = sizeof(struct nsfs_file_handle); + ua_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *ua_fh = (struct nsfs_file_handle *)ua_handle->f_handle; + ua_fh->ns_id = ua_id; + ua_fh->ns_type = 0; + ua_fh->ns_inum = 0; + + ub_handle = (struct file_handle *)ub_buf; + ub_handle->handle_bytes = sizeof(struct nsfs_file_handle); + ub_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *ub_fh = (struct nsfs_file_handle *)ub_handle->f_handle; + ub_fh->ns_id = ub_id; + ub_fh->ns_type = 0; + ub_fh->ns_inum = 0; + + net_handle = (struct file_handle *)net_buf; + net_handle->handle_bytes = sizeof(struct nsfs_file_handle); + net_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *net_fh = (struct nsfs_file_handle *)net_handle->f_handle; + net_fh->ns_id = net_id; + net_fh->ns_type = 0; + net_fh->ns_inum = 0; + + /* Open net_ns before child exits to keep it active */ + int net_fd = open_by_handle_at(FD_NSFS_ROOT, net_handle, O_RDONLY); + if (net_fd < 0) { + waitpid(pid, NULL, 0); + SKIP(return, "Failed to open network namespace"); + } + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* With net_ns active, both user_A and user_B should be active */ + TH_LOG("Testing user_B active (net_ns active causes propagation)"); + int ub_fd = open_by_handle_at(FD_NSFS_ROOT, ub_handle, O_RDONLY); + ASSERT_GE(ub_fd, 0); + + TH_LOG("Testing user_A active (propagated through user_B)"); + int ua_fd = open_by_handle_at(FD_NSFS_ROOT, ua_handle, O_RDONLY); + ASSERT_GE(ua_fd, 0); + + /* Close net_ns - user_B should stay active (we hold direct ref) */ + TH_LOG("Closing net_ns, user_B should remain active (direct ref held)"); + close(net_fd); + int ub_fd2 = open_by_handle_at(FD_NSFS_ROOT, ub_handle, O_RDONLY); + ASSERT_GE(ub_fd2, 0); + close(ub_fd2); + + /* Close user_B - user_A should stay active (we hold direct ref) */ + TH_LOG("Closing user_B, user_A should remain active (direct ref held)"); + close(ub_fd); + int ua_fd2 = open_by_handle_at(FD_NSFS_ROOT, ua_handle, O_RDONLY); + ASSERT_GE(ua_fd2, 0); + close(ua_fd2); + + /* Close user_A - everything should become inactive */ + TH_LOG("Closing user_A, all should become inactive"); + close(ua_fd); + + /* All should now be inactive */ + ua_fd = open_by_handle_at(FD_NSFS_ROOT, ua_handle, O_RDONLY); + ASSERT_LT(ua_fd, 0); +} + TEST_HARNESS_MAIN From 2a94bf7bb8795bd6def3a45c9dcde906d83f4f26 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:48 +0100 Subject: [PATCH 38/75] selftests/namespaces: thirteenth active reference count tests Test that parent stays active as long as ANY child is active. Create parent user namespace with two child net namespaces. Parent should remain active until BOTH children are inactive. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-35-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 194 ++++++++++++++++++ 1 file changed, 194 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index b1a454dac9d0..25f06e623064 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -1623,4 +1623,198 @@ TEST(ns_deep_hierarchy_propagation) ASSERT_LT(ua_fd, 0); } +/* + * Test that parent stays active as long as ANY child is active. + * Create parent user namespace with two child net namespaces. + * Parent should remain active until BOTH children are inactive. + */ +TEST(ns_parent_multiple_children_refcount) +{ + struct file_handle *parent_handle, *net1_handle, *net2_handle; + int ret, pipefd[2], syncpipe[2]; + pid_t pid; + int status; + __u64 p_id, n1_id, n2_id; + char p_buf[sizeof(*parent_handle) + MAX_HANDLE_SZ]; + char n1_buf[sizeof(*net1_handle) + MAX_HANDLE_SZ]; + char n2_buf[sizeof(*net2_handle) + MAX_HANDLE_SZ]; + char sync_byte; + + ASSERT_EQ(pipe(pipefd), 0); + ASSERT_EQ(pipe(syncpipe), 0); + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + close(pipefd[0]); + close(syncpipe[1]); + + /* Create parent user namespace */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + int p_fd = open("/proc/self/ns/user", O_RDONLY); + if (p_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(p_fd, NS_GET_ID, &p_id) < 0) { + close(p_fd); + close(pipefd[1]); + exit(1); + } + close(p_fd); + + /* Create first network namespace */ + if (unshare(CLONE_NEWNET) < 0) { + close(pipefd[1]); + close(syncpipe[0]); + exit(1); + } + + int n1_fd = open("/proc/self/ns/net", O_RDONLY); + if (n1_fd < 0) { + close(pipefd[1]); + close(syncpipe[0]); + exit(1); + } + if (ioctl(n1_fd, NS_GET_ID, &n1_id) < 0) { + close(n1_fd); + close(pipefd[1]); + close(syncpipe[0]); + exit(1); + } + /* Keep n1_fd open so first namespace stays active */ + + /* Create second network namespace */ + if (unshare(CLONE_NEWNET) < 0) { + close(n1_fd); + close(pipefd[1]); + close(syncpipe[0]); + exit(1); + } + + int n2_fd = open("/proc/self/ns/net", O_RDONLY); + if (n2_fd < 0) { + close(n1_fd); + close(pipefd[1]); + close(syncpipe[0]); + exit(1); + } + if (ioctl(n2_fd, NS_GET_ID, &n2_id) < 0) { + close(n1_fd); + close(n2_fd); + close(pipefd[1]); + close(syncpipe[0]); + exit(1); + } + /* Keep both n1_fd and n2_fd open */ + + /* Send all namespace IDs */ + write(pipefd[1], &p_id, sizeof(p_id)); + write(pipefd[1], &n1_id, sizeof(n1_id)); + write(pipefd[1], &n2_id, sizeof(n2_id)); + close(pipefd[1]); + + /* Wait for parent to signal before exiting */ + read(syncpipe[0], &sync_byte, 1); + close(syncpipe[0]); + exit(0); + } + + close(pipefd[1]); + close(syncpipe[0]); + + /* Read all three namespace IDs - fixed size, no parsing needed */ + ret = read(pipefd[0], &p_id, sizeof(p_id)); + if (ret != sizeof(p_id)) { + close(pipefd[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read parent namespace ID"); + } + + ret = read(pipefd[0], &n1_id, sizeof(n1_id)); + if (ret != sizeof(n1_id)) { + close(pipefd[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read first network namespace ID"); + } + + ret = read(pipefd[0], &n2_id, sizeof(n2_id)); + close(pipefd[0]); + if (ret != sizeof(n2_id)) { + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read second network namespace ID"); + } + + /* Construct file handles from namespace IDs */ + parent_handle = (struct file_handle *)p_buf; + parent_handle->handle_bytes = sizeof(struct nsfs_file_handle); + parent_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *p_fh = (struct nsfs_file_handle *)parent_handle->f_handle; + p_fh->ns_id = p_id; + p_fh->ns_type = 0; + p_fh->ns_inum = 0; + + net1_handle = (struct file_handle *)n1_buf; + net1_handle->handle_bytes = sizeof(struct nsfs_file_handle); + net1_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *n1_fh = (struct nsfs_file_handle *)net1_handle->f_handle; + n1_fh->ns_id = n1_id; + n1_fh->ns_type = 0; + n1_fh->ns_inum = 0; + + net2_handle = (struct file_handle *)n2_buf; + net2_handle->handle_bytes = sizeof(struct nsfs_file_handle); + net2_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *n2_fh = (struct nsfs_file_handle *)net2_handle->f_handle; + n2_fh->ns_id = n2_id; + n2_fh->ns_type = 0; + n2_fh->ns_inum = 0; + + /* Open both net namespaces while child is still alive */ + int n1_fd = open_by_handle_at(FD_NSFS_ROOT, net1_handle, O_RDONLY); + int n2_fd = open_by_handle_at(FD_NSFS_ROOT, net2_handle, O_RDONLY); + if (n1_fd < 0 || n2_fd < 0) { + if (n1_fd >= 0) close(n1_fd); + if (n2_fd >= 0) close(n2_fd); + sync_byte = 'G'; + write(syncpipe[1], &sync_byte, 1); + close(syncpipe[1]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to open net namespaces"); + } + + /* Signal child that we have opened the namespaces */ + sync_byte = 'G'; + write(syncpipe[1], &sync_byte, 1); + close(syncpipe[1]); + + /* Wait for child to exit */ + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* Parent should be active (has 2 active children) */ + TH_LOG("Both net namespaces active - parent should be active"); + int p_fd = open_by_handle_at(FD_NSFS_ROOT, parent_handle, O_RDONLY); + ASSERT_GE(p_fd, 0); + close(p_fd); + + /* Close first net namespace - parent should STILL be active */ + TH_LOG("Closing first net ns - parent should still be active"); + close(n1_fd); + p_fd = open_by_handle_at(FD_NSFS_ROOT, parent_handle, O_RDONLY); + ASSERT_GE(p_fd, 0); + close(p_fd); + + /* Close second net namespace - parent should become inactive */ + TH_LOG("Closing second net ns - parent should become inactive"); + close(n2_fd); + p_fd = open_by_handle_at(FD_NSFS_ROOT, parent_handle, O_RDONLY); + ASSERT_LT(p_fd, 0); +} + TEST_HARNESS_MAIN From a9d84bf7bf32b05a2c3979c149a7587dd2426ad4 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:49 +0100 Subject: [PATCH 39/75] selftests/namespaces: fourteenth active reference count tests Test that user namespace as a child also propagates correctly. Create user_A -> user_B, verify when user_B is active that user_A is also active. This is different from non-user namespace children. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-36-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 132 ++++++++++++++++++ 1 file changed, 132 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index 25f06e623064..430702c041a9 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -1817,4 +1817,136 @@ TEST(ns_parent_multiple_children_refcount) ASSERT_LT(p_fd, 0); } +/* + * Test that user namespace as a child also propagates correctly. + * Create user_A -> user_B, verify when user_B is active that user_A + * is also active. This is different from non-user namespace children. + */ +TEST(ns_userns_child_propagation) +{ + struct file_handle *ua_handle, *ub_handle; + int ret, pipefd[2]; + pid_t pid; + int status; + __u64 ua_id, ub_id; + char ua_buf[sizeof(*ua_handle) + MAX_HANDLE_SZ]; + char ub_buf[sizeof(*ub_handle) + MAX_HANDLE_SZ]; + + ASSERT_EQ(pipe(pipefd), 0); + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + close(pipefd[0]); + + /* Create user_A */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + int ua_fd = open("/proc/self/ns/user", O_RDONLY); + if (ua_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(ua_fd, NS_GET_ID, &ua_id) < 0) { + close(ua_fd); + close(pipefd[1]); + exit(1); + } + close(ua_fd); + + /* Create user_B (child of user_A) */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + int ub_fd = open("/proc/self/ns/user", O_RDONLY); + if (ub_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(ub_fd, NS_GET_ID, &ub_id) < 0) { + close(ub_fd); + close(pipefd[1]); + exit(1); + } + close(ub_fd); + + /* Send both namespace IDs */ + write(pipefd[1], &ua_id, sizeof(ua_id)); + write(pipefd[1], &ub_id, sizeof(ub_id)); + close(pipefd[1]); + exit(0); + } + + close(pipefd[1]); + + /* Read both namespace IDs - fixed size, no parsing needed */ + ret = read(pipefd[0], &ua_id, sizeof(ua_id)); + if (ret != sizeof(ua_id)) { + close(pipefd[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read user_A namespace ID"); + } + + ret = read(pipefd[0], &ub_id, sizeof(ub_id)); + close(pipefd[0]); + if (ret != sizeof(ub_id)) { + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read user_B namespace ID"); + } + + /* Construct file handles from namespace IDs */ + ua_handle = (struct file_handle *)ua_buf; + ua_handle->handle_bytes = sizeof(struct nsfs_file_handle); + ua_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *ua_fh = (struct nsfs_file_handle *)ua_handle->f_handle; + ua_fh->ns_id = ua_id; + ua_fh->ns_type = 0; + ua_fh->ns_inum = 0; + + ub_handle = (struct file_handle *)ub_buf; + ub_handle->handle_bytes = sizeof(struct nsfs_file_handle); + ub_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *ub_fh = (struct nsfs_file_handle *)ub_handle->f_handle; + ub_fh->ns_id = ub_id; + ub_fh->ns_type = 0; + ub_fh->ns_inum = 0; + + /* Open user_B before child exits */ + int ub_fd = open_by_handle_at(FD_NSFS_ROOT, ub_handle, O_RDONLY); + if (ub_fd < 0) { + waitpid(pid, NULL, 0); + SKIP(return, "Failed to open user_B"); + } + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* With user_B active, user_A should also be active */ + TH_LOG("Testing user_A active when child user_B is active"); + int ua_fd = open_by_handle_at(FD_NSFS_ROOT, ua_handle, O_RDONLY); + ASSERT_GE(ua_fd, 0); + + /* Close user_B */ + TH_LOG("Closing user_B"); + close(ub_fd); + + /* user_A should remain active (we hold direct ref) */ + int ua_fd2 = open_by_handle_at(FD_NSFS_ROOT, ua_handle, O_RDONLY); + ASSERT_GE(ua_fd2, 0); + close(ua_fd2); + + /* Close user_A - should become inactive */ + TH_LOG("Closing user_A - should become inactive"); + close(ua_fd); + + ua_fd = open_by_handle_at(FD_NSFS_ROOT, ua_handle, O_RDONLY); + ASSERT_LT(ua_fd, 0); +} + TEST_HARNESS_MAIN From da3c02b70cd980d8c0c8fded5d890b9f118309e1 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:50 +0100 Subject: [PATCH 40/75] selftests/namespaces: fifteenth active reference count tests Test different namespace types (net, uts, ipc) all contributing active references to the same owning user namespace. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-37-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 164 ++++++++++++++++++ 1 file changed, 164 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index 430702c041a9..b7fa973a2572 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -1949,4 +1949,168 @@ TEST(ns_userns_child_propagation) ASSERT_LT(ua_fd, 0); } +/* + * Test different namespace types (net, uts, ipc) all contributing + * active references to the same owning user namespace. + */ +TEST(ns_mixed_types_same_owner) +{ + struct file_handle *user_handle, *net_handle, *uts_handle; + int ret, pipefd[2]; + pid_t pid; + int status; + __u64 u_id, n_id, ut_id; + char u_buf[sizeof(*user_handle) + MAX_HANDLE_SZ]; + char n_buf[sizeof(*net_handle) + MAX_HANDLE_SZ]; + char ut_buf[sizeof(*uts_handle) + MAX_HANDLE_SZ]; + + ASSERT_EQ(pipe(pipefd), 0); + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + close(pipefd[0]); + + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + int u_fd = open("/proc/self/ns/user", O_RDONLY); + if (u_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(u_fd, NS_GET_ID, &u_id) < 0) { + close(u_fd); + close(pipefd[1]); + exit(1); + } + close(u_fd); + + if (unshare(CLONE_NEWNET) < 0) { + close(pipefd[1]); + exit(1); + } + + int n_fd = open("/proc/self/ns/net", O_RDONLY); + if (n_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(n_fd, NS_GET_ID, &n_id) < 0) { + close(n_fd); + close(pipefd[1]); + exit(1); + } + close(n_fd); + + if (unshare(CLONE_NEWUTS) < 0) { + close(pipefd[1]); + exit(1); + } + + int ut_fd = open("/proc/self/ns/uts", O_RDONLY); + if (ut_fd < 0) { + close(pipefd[1]); + exit(1); + } + if (ioctl(ut_fd, NS_GET_ID, &ut_id) < 0) { + close(ut_fd); + close(pipefd[1]); + exit(1); + } + close(ut_fd); + + /* Send all namespace IDs */ + write(pipefd[1], &u_id, sizeof(u_id)); + write(pipefd[1], &n_id, sizeof(n_id)); + write(pipefd[1], &ut_id, sizeof(ut_id)); + close(pipefd[1]); + exit(0); + } + + close(pipefd[1]); + + /* Read all three namespace IDs - fixed size, no parsing needed */ + ret = read(pipefd[0], &u_id, sizeof(u_id)); + if (ret != sizeof(u_id)) { + close(pipefd[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read user namespace ID"); + } + + ret = read(pipefd[0], &n_id, sizeof(n_id)); + if (ret != sizeof(n_id)) { + close(pipefd[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read network namespace ID"); + } + + ret = read(pipefd[0], &ut_id, sizeof(ut_id)); + close(pipefd[0]); + if (ret != sizeof(ut_id)) { + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read UTS namespace ID"); + } + + /* Construct file handles from namespace IDs */ + user_handle = (struct file_handle *)u_buf; + user_handle->handle_bytes = sizeof(struct nsfs_file_handle); + user_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *u_fh = (struct nsfs_file_handle *)user_handle->f_handle; + u_fh->ns_id = u_id; + u_fh->ns_type = 0; + u_fh->ns_inum = 0; + + net_handle = (struct file_handle *)n_buf; + net_handle->handle_bytes = sizeof(struct nsfs_file_handle); + net_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *n_fh = (struct nsfs_file_handle *)net_handle->f_handle; + n_fh->ns_id = n_id; + n_fh->ns_type = 0; + n_fh->ns_inum = 0; + + uts_handle = (struct file_handle *)ut_buf; + uts_handle->handle_bytes = sizeof(struct nsfs_file_handle); + uts_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *ut_fh = (struct nsfs_file_handle *)uts_handle->f_handle; + ut_fh->ns_id = ut_id; + ut_fh->ns_type = 0; + ut_fh->ns_inum = 0; + + /* Open both non-user namespaces */ + int n_fd = open_by_handle_at(FD_NSFS_ROOT, net_handle, O_RDONLY); + int ut_fd = open_by_handle_at(FD_NSFS_ROOT, uts_handle, O_RDONLY); + if (n_fd < 0 || ut_fd < 0) { + if (n_fd >= 0) close(n_fd); + if (ut_fd >= 0) close(ut_fd); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to open namespaces"); + } + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* User namespace should be active (2 active children) */ + TH_LOG("Both net and uts active - user ns should be active"); + int u_fd = open_by_handle_at(FD_NSFS_ROOT, user_handle, O_RDONLY); + ASSERT_GE(u_fd, 0); + close(u_fd); + + /* Close net - user ns should STILL be active (uts still active) */ + TH_LOG("Closing net - user ns should still be active"); + close(n_fd); + u_fd = open_by_handle_at(FD_NSFS_ROOT, user_handle, O_RDONLY); + ASSERT_GE(u_fd, 0); + close(u_fd); + + /* Close uts - user ns should become inactive */ + TH_LOG("Closing uts - user ns should become inactive"); + close(ut_fd); + u_fd = open_by_handle_at(FD_NSFS_ROOT, user_handle, O_RDONLY); + ASSERT_LT(u_fd, 0); +} + TEST_HARNESS_MAIN From 158c5c786e91675a508a3afdda2f38973b487ff0 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:51 +0100 Subject: [PATCH 41/75] selftests/namespaces: add listns() wrapper Add a wrapper for the listns() system call. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-38-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- tools/testing/selftests/namespaces/wrappers.h | 35 +++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 tools/testing/selftests/namespaces/wrappers.h diff --git a/tools/testing/selftests/namespaces/wrappers.h b/tools/testing/selftests/namespaces/wrappers.h new file mode 100644 index 000000000000..9741a64a5b1d --- /dev/null +++ b/tools/testing/selftests/namespaces/wrappers.h @@ -0,0 +1,35 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include +#include + +#ifndef __SELFTESTS_NAMESPACES_WRAPPERS_H__ +#define __SELFTESTS_NAMESPACES_WRAPPERS_H__ + +#ifndef __NR_listns + #if defined __alpha__ + #define __NR_listns 580 + #elif defined _MIPS_SIM + #if _MIPS_SIM == _MIPS_SIM_ABI32 /* o32 */ + #define __NR_listns 4470 + #endif + #if _MIPS_SIM == _MIPS_SIM_NABI32 /* n32 */ + #define __NR_listns 6470 + #endif + #if _MIPS_SIM == _MIPS_SIM_ABI64 /* n64 */ + #define __NR_listns 5470 + #endif + #else + #define __NR_listns 470 + #endif +#endif + +static inline int sys_listns(const struct ns_id_req *req, __u64 *ns_ids, + size_t nr_ns_ids, unsigned int flags) +{ + return syscall(__NR_listns, req, ns_ids, nr_ns_ids, flags); +} + +#endif /* __SELFTESTS_NAMESPACES_WRAPPERS_H__ */ From e2ff8d88649c2e4303f2dbb80659ae0312c30846 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:52 +0100 Subject: [PATCH 42/75] selftests/namespaces: first listns() test Test basic listns() functionality with the unified namespace tree. List all active namespaces globally. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-39-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- tools/testing/selftests/namespaces/.gitignore | 1 + tools/testing/selftests/namespaces/Makefile | 3 +- .../selftests/namespaces/listns_test.c | 57 +++++++++++++++++++ 3 files changed, 60 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/namespaces/listns_test.c diff --git a/tools/testing/selftests/namespaces/.gitignore b/tools/testing/selftests/namespaces/.gitignore index 100cc5bfef04..5065f07e92c9 100644 --- a/tools/testing/selftests/namespaces/.gitignore +++ b/tools/testing/selftests/namespaces/.gitignore @@ -2,3 +2,4 @@ nsid_test file_handle_test init_ino_test ns_active_ref_test +listns_test diff --git a/tools/testing/selftests/namespaces/Makefile b/tools/testing/selftests/namespaces/Makefile index 5cea938cdde8..de708f4df159 100644 --- a/tools/testing/selftests/namespaces/Makefile +++ b/tools/testing/selftests/namespaces/Makefile @@ -2,9 +2,10 @@ CFLAGS += -Wall -O0 -g $(KHDR_INCLUDES) $(TOOLS_INCLUDES) LDLIBS += -lcap -TEST_GEN_PROGS := nsid_test file_handle_test init_ino_test ns_active_ref_test +TEST_GEN_PROGS := nsid_test file_handle_test init_ino_test ns_active_ref_test listns_test include ../lib.mk $(OUTPUT)/ns_active_ref_test: ../filesystems/utils.c +$(OUTPUT)/listns_test: ../filesystems/utils.c diff --git a/tools/testing/selftests/namespaces/listns_test.c b/tools/testing/selftests/namespaces/listns_test.c new file mode 100644 index 000000000000..cb42827d3dfe --- /dev/null +++ b/tools/testing/selftests/namespaces/listns_test.c @@ -0,0 +1,57 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "../kselftest_harness.h" +#include "../filesystems/utils.h" +#include "wrappers.h" + +/* + * Test basic listns() functionality with the unified namespace tree. + * List all active namespaces globally. + */ +TEST(listns_basic_unified) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = 0, /* All types */ + .spare2 = 0, + .user_ns_id = 0, /* Global listing */ + }; + __u64 ns_ids[100]; + ssize_t ret; + + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + TH_LOG("listns failed: %s (errno=%d)", strerror(errno), errno); + ASSERT_TRUE(false); + } + + /* Should find at least the initial namespaces */ + ASSERT_GT(ret, 0); + TH_LOG("Found %zd active namespaces", ret); + + /* Verify all returned IDs are non-zero */ + for (ssize_t i = 0; i < ret; i++) { + ASSERT_NE(ns_ids[i], 0); + TH_LOG(" [%zd] ns_id: %llu", i, (unsigned long long)ns_ids[i]); + } +} + +TEST_HARNESS_MAIN From 6a68c7f919d9068b9b857be8085af3d59ff0084c Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:53 +0100 Subject: [PATCH 43/75] selftests/namespaces: second listns() test test listns() with type filtering. List only network namespaces. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-40-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/listns_test.c | 61 +++++++++++++++++++ 1 file changed, 61 insertions(+) diff --git a/tools/testing/selftests/namespaces/listns_test.c b/tools/testing/selftests/namespaces/listns_test.c index cb42827d3dfe..64249502ac49 100644 --- a/tools/testing/selftests/namespaces/listns_test.c +++ b/tools/testing/selftests/namespaces/listns_test.c @@ -54,4 +54,65 @@ TEST(listns_basic_unified) } } +/* + * Test listns() with type filtering. + * List only network namespaces. + */ +TEST(listns_filter_by_type) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWNET, /* Only network namespaces */ + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids[100]; + ssize_t ret; + + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + TH_LOG("listns failed: %s (errno=%d)", strerror(errno), errno); + ASSERT_TRUE(false); + } + ASSERT_GE(ret, 0); + + /* Should find at least init_net */ + ASSERT_GT(ret, 0); + TH_LOG("Found %zd active network namespaces", ret); + + /* Verify we can open each namespace and it's actually a network namespace */ + for (ssize_t i = 0; i < ret && i < 5; i++) { + struct nsfs_file_handle nsfh = { + .ns_id = ns_ids[i], + .ns_type = CLONE_NEWNET, + .ns_inum = 0, + }; + struct file_handle *fh; + int fd; + + fh = (struct file_handle *)malloc(sizeof(*fh) + sizeof(nsfh)); + ASSERT_NE(fh, NULL); + fh->handle_bytes = sizeof(nsfh); + fh->handle_type = 0; + memcpy(fh->f_handle, &nsfh, sizeof(nsfh)); + + fd = open_by_handle_at(-10003, fh, O_RDONLY); + free(fh); + + if (fd >= 0) { + int ns_type; + /* Verify it's a network namespace via ioctl */ + ns_type = ioctl(fd, NS_GET_NSTYPE); + if (ns_type >= 0) { + ASSERT_EQ(ns_type, CLONE_NEWNET); + } + close(fd); + } + } +} + TEST_HARNESS_MAIN From 46909d13434bf73d09a224c1e5fca409adc94f10 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:54 +0100 Subject: [PATCH 44/75] selftests/namespaces: third listns() test Test listns() pagination. List namespaces in batches. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-41-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/listns_test.c | 53 +++++++++++++++++++ 1 file changed, 53 insertions(+) diff --git a/tools/testing/selftests/namespaces/listns_test.c b/tools/testing/selftests/namespaces/listns_test.c index 64249502ac49..7dff63a00263 100644 --- a/tools/testing/selftests/namespaces/listns_test.c +++ b/tools/testing/selftests/namespaces/listns_test.c @@ -115,4 +115,57 @@ TEST(listns_filter_by_type) } } +/* + * Test listns() pagination. + * List namespaces in batches. + */ +TEST(listns_pagination) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = 0, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 batch1[2], batch2[2]; + ssize_t ret1, ret2; + + /* Get first batch */ + ret1 = sys_listns(&req, batch1, ARRAY_SIZE(batch1), 0); + if (ret1 < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + TH_LOG("listns failed: %s (errno=%d)", strerror(errno), errno); + ASSERT_TRUE(false); + } + ASSERT_GE(ret1, 0); + + if (ret1 == 0) + SKIP(return, "No namespaces found"); + + TH_LOG("First batch: %zd namespaces", ret1); + + /* Get second batch using last ID from first batch */ + if (ret1 == ARRAY_SIZE(batch1)) { + req.ns_id = batch1[ret1 - 1]; + ret2 = sys_listns(&req, batch2, ARRAY_SIZE(batch2), 0); + ASSERT_GE(ret2, 0); + + TH_LOG("Second batch: %zd namespaces (after ns_id=%llu)", + ret2, (unsigned long long)req.ns_id); + + /* If we got more results, verify IDs are monotonically increasing */ + if (ret2 > 0) { + ASSERT_GT(batch2[0], batch1[ret1 - 1]); + TH_LOG("Pagination working: %llu > %llu", + (unsigned long long)batch2[0], + (unsigned long long)batch1[ret1 - 1]); + } + } else { + TH_LOG("All namespaces fit in first batch"); + } +} + TEST_HARNESS_MAIN From abac8de3e5000b2b448bab4a9d19e35ce32e80ce Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:55 +0100 Subject: [PATCH 45/75] selftests/namespaces: fourth listns() test Test listns() with LISTNS_CURRENT_USER. List namespaces owned by current user namespace. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-42-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/listns_test.c | 33 +++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/tools/testing/selftests/namespaces/listns_test.c b/tools/testing/selftests/namespaces/listns_test.c index 7dff63a00263..457298cb4c64 100644 --- a/tools/testing/selftests/namespaces/listns_test.c +++ b/tools/testing/selftests/namespaces/listns_test.c @@ -168,4 +168,37 @@ TEST(listns_pagination) } } +/* + * Test listns() with LISTNS_CURRENT_USER. + * List namespaces owned by current user namespace. + */ +TEST(listns_current_user) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = 0, + .spare2 = 0, + .user_ns_id = LISTNS_CURRENT_USER, + }; + __u64 ns_ids[100]; + ssize_t ret; + + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + TH_LOG("listns failed: %s (errno=%d)", strerror(errno), errno); + ASSERT_TRUE(false); + } + ASSERT_GE(ret, 0); + + /* Should find at least the initial namespaces if we're in init_user_ns */ + TH_LOG("Found %zd namespaces owned by current user namespace", ret); + + for (ssize_t i = 0; i < ret; i++) + TH_LOG(" [%zd] ns_id: %llu", i, (unsigned long long)ns_ids[i]); +} + TEST_HARNESS_MAIN From 4080b9d946f4eddd055d7470e55505f8da434c33 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:56 +0100 Subject: [PATCH 46/75] selftests/namespaces: fifth listns() test Test that listns() only returns active namespaces. Create a namespace, let it become inactive, verify it's not listed. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-43-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/listns_test.c | 123 ++++++++++++++++++ 1 file changed, 123 insertions(+) diff --git a/tools/testing/selftests/namespaces/listns_test.c b/tools/testing/selftests/namespaces/listns_test.c index 457298cb4c64..a04ebe11ce2c 100644 --- a/tools/testing/selftests/namespaces/listns_test.c +++ b/tools/testing/selftests/namespaces/listns_test.c @@ -201,4 +201,127 @@ TEST(listns_current_user) TH_LOG(" [%zd] ns_id: %llu", i, (unsigned long long)ns_ids[i]); } +/* + * Test that listns() only returns active namespaces. + * Create a namespace, let it become inactive, verify it's not listed. + */ +TEST(listns_only_active) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWNET, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids_before[100], ns_ids_after[100]; + ssize_t ret_before, ret_after; + int pipefd[2]; + pid_t pid; + __u64 new_ns_id = 0; + int status; + + /* Get initial list */ + ret_before = sys_listns(&req, ns_ids_before, ARRAY_SIZE(ns_ids_before), 0); + if (ret_before < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + TH_LOG("listns failed: %s (errno=%d)", strerror(errno), errno); + ASSERT_TRUE(false); + } + ASSERT_GE(ret_before, 0); + + TH_LOG("Before: %zd active network namespaces", ret_before); + + /* Create a new namespace in a child process and get its ID */ + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + int fd; + __u64 ns_id; + + close(pipefd[0]); + + /* Create new network namespace */ + if (unshare(CLONE_NEWNET) < 0) { + close(pipefd[1]); + exit(1); + } + + /* Get its ID */ + fd = open("/proc/self/ns/net", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &ns_id) < 0) { + close(fd); + close(pipefd[1]); + exit(1); + } + close(fd); + + /* Send ID to parent */ + write(pipefd[1], &ns_id, sizeof(ns_id)); + close(pipefd[1]); + + /* Keep namespace active briefly */ + usleep(100000); + exit(0); + } + + /* Parent reads the new namespace ID */ + { + int bytes; + + close(pipefd[1]); + bytes = read(pipefd[0], &new_ns_id, sizeof(new_ns_id)); + close(pipefd[0]); + + if (bytes == sizeof(new_ns_id)) { + __u64 ns_ids_during[100]; + int ret_during; + + TH_LOG("Child created namespace with ID %llu", (unsigned long long)new_ns_id); + + /* List namespaces while child is still alive - should see new one */ + ret_during = sys_listns(&req, ns_ids_during, ARRAY_SIZE(ns_ids_during), 0); + ASSERT_GE(ret_during, 0); + TH_LOG("During: %d active network namespaces", ret_during); + + /* Should have more namespaces than before */ + ASSERT_GE(ret_during, ret_before); + } + } + + /* Wait for child to exit */ + waitpid(pid, &status, 0); + + /* Give time for namespace to become inactive */ + usleep(100000); + + /* List namespaces after child exits - should not see new one */ + ret_after = sys_listns(&req, ns_ids_after, ARRAY_SIZE(ns_ids_after), 0); + ASSERT_GE(ret_after, 0); + TH_LOG("After: %zd active network namespaces", ret_after); + + /* Verify the new namespace ID is not in the after list */ + if (new_ns_id != 0) { + bool found = false; + + for (ssize_t i = 0; i < ret_after; i++) { + if (ns_ids_after[i] == new_ns_id) { + found = true; + break; + } + } + ASSERT_FALSE(found); + } +} + TEST_HARNESS_MAIN From bc8da67e0e1e7eca9289736584c876259eace9fa Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:57 +0100 Subject: [PATCH 47/75] selftests/namespaces: sixth listns() test Test listns() with specific user namespace ID. Create a user namespace and list namespaces it owns. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-44-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/listns_test.c | 122 ++++++++++++++++++ 1 file changed, 122 insertions(+) diff --git a/tools/testing/selftests/namespaces/listns_test.c b/tools/testing/selftests/namespaces/listns_test.c index a04ebe11ce2c..f5b8bc5d111f 100644 --- a/tools/testing/selftests/namespaces/listns_test.c +++ b/tools/testing/selftests/namespaces/listns_test.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include #include @@ -324,4 +325,125 @@ TEST(listns_only_active) } } +/* + * Test listns() with specific user namespace ID. + * Create a user namespace and list namespaces it owns. + */ +TEST(listns_specific_userns) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = 0, + .spare2 = 0, + .user_ns_id = 0, /* Will be filled with created userns ID */ + }; + __u64 ns_ids[100]; + int sv[2]; + pid_t pid; + int status; + __u64 user_ns_id = 0; + int bytes; + ssize_t ret; + + ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sv), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + int fd; + __u64 ns_id; + char buf; + + close(sv[0]); + + /* Create new user namespace */ + if (setup_userns() < 0) { + close(sv[1]); + exit(1); + } + + /* Get user namespace ID */ + fd = open("/proc/self/ns/user", O_RDONLY); + if (fd < 0) { + close(sv[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &ns_id) < 0) { + close(fd); + close(sv[1]); + exit(1); + } + close(fd); + + /* Send ID to parent */ + if (write(sv[1], &ns_id, sizeof(ns_id)) != sizeof(ns_id)) { + close(sv[1]); + exit(1); + } + + /* Create some namespaces owned by this user namespace */ + unshare(CLONE_NEWNET); + unshare(CLONE_NEWUTS); + + /* Wait for parent signal */ + if (read(sv[1], &buf, 1) != 1) { + close(sv[1]); + exit(1); + } + close(sv[1]); + exit(0); + } + + /* Parent */ + close(sv[1]); + bytes = read(sv[0], &user_ns_id, sizeof(user_ns_id)); + + if (bytes != sizeof(user_ns_id)) { + close(sv[0]); + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to get user namespace ID from child"); + } + + TH_LOG("Child created user namespace with ID %llu", (unsigned long long)user_ns_id); + + /* List namespaces owned by this user namespace */ + req.user_ns_id = user_ns_id; + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + + if (ret < 0) { + TH_LOG("listns failed: %s (errno=%d)", strerror(errno), errno); + close(sv[0]); + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + if (errno == ENOSYS) { + SKIP(return, "listns() not supported"); + } + ASSERT_GE(ret, 0); + } + + TH_LOG("Found %zd namespaces owned by user namespace %llu", ret, + (unsigned long long)user_ns_id); + + /* Should find at least the network and UTS namespaces we created */ + if (ret > 0) { + for (ssize_t i = 0; i < ret && i < 10; i++) + TH_LOG(" [%zd] ns_id: %llu", i, (unsigned long long)ns_ids[i]); + } + + /* Signal child to exit */ + if (write(sv[0], "X", 1) != 1) { + close(sv[0]); + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + ASSERT_TRUE(false); + } + close(sv[0]); + waitpid(pid, &status, 0); +} + TEST_HARNESS_MAIN From 6aeca1dd493ba5afb4ae2e1091f93f4bf9675b12 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:58 +0100 Subject: [PATCH 48/75] selftests/namespaces: seventh listns() test Test listns() with multiple namespace types filter. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-45-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/listns_test.c | 31 +++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/tools/testing/selftests/namespaces/listns_test.c b/tools/testing/selftests/namespaces/listns_test.c index f5b8bc5d111f..d73c2a2898cf 100644 --- a/tools/testing/selftests/namespaces/listns_test.c +++ b/tools/testing/selftests/namespaces/listns_test.c @@ -446,4 +446,35 @@ TEST(listns_specific_userns) waitpid(pid, &status, 0); } +/* + * Test listns() with multiple namespace types filter. + */ +TEST(listns_multiple_types) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWNET | CLONE_NEWUTS, /* Network and UTS */ + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids[100]; + ssize_t ret; + + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + TH_LOG("listns failed: %s (errno=%d)", strerror(errno), errno); + ASSERT_TRUE(false); + } + ASSERT_GE(ret, 0); + + TH_LOG("Found %zd active network/UTS namespaces", ret); + + for (ssize_t i = 0; i < ret; i++) + TH_LOG(" [%zd] ns_id: %llu", i, (unsigned long long)ns_ids[i]); +} + TEST_HARNESS_MAIN From b0de4c80fb836f74dbd9e02612e240f5f8026aca Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:59 +0100 Subject: [PATCH 49/75] selftests/namespaces: eigth listns() test Test that hierarchical active reference propagation keeps parent user namespaces visible in listns(). Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-46-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/listns_test.c | 150 ++++++++++++++++++ 1 file changed, 150 insertions(+) diff --git a/tools/testing/selftests/namespaces/listns_test.c b/tools/testing/selftests/namespaces/listns_test.c index d73c2a2898cf..d3be6f97d34e 100644 --- a/tools/testing/selftests/namespaces/listns_test.c +++ b/tools/testing/selftests/namespaces/listns_test.c @@ -477,4 +477,154 @@ TEST(listns_multiple_types) TH_LOG(" [%zd] ns_id: %llu", i, (unsigned long long)ns_ids[i]); } +/* + * Test that hierarchical active reference propagation keeps parent + * user namespaces visible in listns(). + */ +TEST(listns_hierarchical_visibility) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 parent_ns_id = 0, child_ns_id = 0; + int sv[2]; + pid_t pid; + int status; + int bytes; + __u64 ns_ids[100]; + ssize_t ret; + bool found_parent, found_child; + + ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sv), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + int fd; + char buf; + + close(sv[0]); + + /* Create parent user namespace */ + if (setup_userns() < 0) { + close(sv[1]); + exit(1); + } + + fd = open("/proc/self/ns/user", O_RDONLY); + if (fd < 0) { + close(sv[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &parent_ns_id) < 0) { + close(fd); + close(sv[1]); + exit(1); + } + close(fd); + + /* Create child user namespace */ + if (setup_userns() < 0) { + close(sv[1]); + exit(1); + } + + fd = open("/proc/self/ns/user", O_RDONLY); + if (fd < 0) { + close(sv[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &child_ns_id) < 0) { + close(fd); + close(sv[1]); + exit(1); + } + close(fd); + + /* Send both IDs to parent */ + if (write(sv[1], &parent_ns_id, sizeof(parent_ns_id)) != sizeof(parent_ns_id)) { + close(sv[1]); + exit(1); + } + if (write(sv[1], &child_ns_id, sizeof(child_ns_id)) != sizeof(child_ns_id)) { + close(sv[1]); + exit(1); + } + + /* Wait for parent signal */ + if (read(sv[1], &buf, 1) != 1) { + close(sv[1]); + exit(1); + } + close(sv[1]); + exit(0); + } + + /* Parent */ + close(sv[1]); + + /* Read both namespace IDs */ + bytes = read(sv[0], &parent_ns_id, sizeof(parent_ns_id)); + bytes += read(sv[0], &child_ns_id, sizeof(child_ns_id)); + + if (bytes != (int)(2 * sizeof(__u64))) { + close(sv[0]); + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to get namespace IDs from child"); + } + + TH_LOG("Parent user namespace ID: %llu", (unsigned long long)parent_ns_id); + TH_LOG("Child user namespace ID: %llu", (unsigned long long)child_ns_id); + + /* List all user namespaces */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + + if (ret < 0 && errno == ENOSYS) { + close(sv[0]); + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + SKIP(return, "listns() not supported"); + } + + ASSERT_GE(ret, 0); + TH_LOG("Found %zd active user namespaces", ret); + + /* Both parent and child should be visible (active due to child process) */ + found_parent = false; + found_child = false; + for (ssize_t i = 0; i < ret; i++) { + if (ns_ids[i] == parent_ns_id) + found_parent = true; + if (ns_ids[i] == child_ns_id) + found_child = true; + } + + TH_LOG("Parent namespace %s, child namespace %s", + found_parent ? "found" : "NOT FOUND", + found_child ? "found" : "NOT FOUND"); + + ASSERT_TRUE(found_child); + /* With hierarchical propagation, parent should also be active */ + ASSERT_TRUE(found_parent); + + /* Signal child to exit */ + if (write(sv[0], "X", 1) != 1) { + close(sv[0]); + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + ASSERT_TRUE(false); + } + close(sv[0]); + waitpid(pid, &status, 0); +} + TEST_HARNESS_MAIN From 674294a479fc0e587b758c2ecb7dcfe8373e6be8 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:00 +0100 Subject: [PATCH 50/75] selftests/namespaces: ninth listns() test Test error cases for listns(). Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-47-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/listns_test.c | 49 +++++++++++++++++++ 1 file changed, 49 insertions(+) diff --git a/tools/testing/selftests/namespaces/listns_test.c b/tools/testing/selftests/namespaces/listns_test.c index d3be6f97d34e..8a95789d6a87 100644 --- a/tools/testing/selftests/namespaces/listns_test.c +++ b/tools/testing/selftests/namespaces/listns_test.c @@ -627,4 +627,53 @@ TEST(listns_hierarchical_visibility) waitpid(pid, &status, 0); } +/* + * Test error cases for listns(). + */ +TEST(listns_error_cases) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = 0, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids[10]; + int ret; + + /* Test with invalid flags */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0xFFFF); + if (errno == ENOSYS) { + /* listns() not supported, skip this check */ + } else { + ASSERT_LT(ret, 0); + ASSERT_EQ(errno, EINVAL); + } + + /* Test with NULL ns_ids array */ + ret = sys_listns(&req, NULL, 10, 0); + ASSERT_LT(ret, 0); + + /* Test with invalid spare field */ + req.spare = 1; + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (errno == ENOSYS) { + /* listns() not supported, skip this check */ + } else { + ASSERT_LT(ret, 0); + ASSERT_EQ(errno, EINVAL); + } + req.spare = 0; + + /* Test with huge nr_ns_ids */ + ret = sys_listns(&req, ns_ids, 2000000, 0); + if (errno == ENOSYS) { + /* listns() not supported, skip this check */ + } else { + ASSERT_LT(ret, 0); + } +} + TEST_HARNESS_MAIN From 1f8ee4a1f94afcf7680a9537a397c27a4919ccec Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:01 +0100 Subject: [PATCH 51/75] selftests/namespaces: first listns() permission test Test that unprivileged users can only see namespaces they're currently in. Create a namespace, drop privileges, verify we can only see our own namespaces. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-48-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- tools/testing/selftests/namespaces/.gitignore | 1 + tools/testing/selftests/namespaces/Makefile | 3 +- .../namespaces/listns_permissions_test.c | 131 ++++++++++++++++++ 3 files changed, 134 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/namespaces/listns_permissions_test.c diff --git a/tools/testing/selftests/namespaces/.gitignore b/tools/testing/selftests/namespaces/.gitignore index 5065f07e92c9..17f9c675a60b 100644 --- a/tools/testing/selftests/namespaces/.gitignore +++ b/tools/testing/selftests/namespaces/.gitignore @@ -3,3 +3,4 @@ file_handle_test init_ino_test ns_active_ref_test listns_test +listns_permissions_test diff --git a/tools/testing/selftests/namespaces/Makefile b/tools/testing/selftests/namespaces/Makefile index de708f4df159..2dd22bc68b89 100644 --- a/tools/testing/selftests/namespaces/Makefile +++ b/tools/testing/selftests/namespaces/Makefile @@ -2,10 +2,11 @@ CFLAGS += -Wall -O0 -g $(KHDR_INCLUDES) $(TOOLS_INCLUDES) LDLIBS += -lcap -TEST_GEN_PROGS := nsid_test file_handle_test init_ino_test ns_active_ref_test listns_test +TEST_GEN_PROGS := nsid_test file_handle_test init_ino_test ns_active_ref_test listns_test listns_permissions_test include ../lib.mk $(OUTPUT)/ns_active_ref_test: ../filesystems/utils.c $(OUTPUT)/listns_test: ../filesystems/utils.c +$(OUTPUT)/listns_permissions_test: ../filesystems/utils.c diff --git a/tools/testing/selftests/namespaces/listns_permissions_test.c b/tools/testing/selftests/namespaces/listns_permissions_test.c new file mode 100644 index 000000000000..907fe419ec22 --- /dev/null +++ b/tools/testing/selftests/namespaces/listns_permissions_test.c @@ -0,0 +1,131 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "../kselftest_harness.h" +#include "../filesystems/utils.h" +#include "wrappers.h" + +/* + * Test that unprivileged users can only see namespaces they're currently in. + * Create a namespace, drop privileges, verify we can only see our own namespaces. + */ +TEST(listns_unprivileged_current_only) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWNET, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids[100]; + ssize_t ret; + int pipefd[2]; + pid_t pid; + int status; + bool found_ours; + int unexpected_count; + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + int fd; + __u64 our_netns_id; + bool found_ours; + int unexpected_count; + + close(pipefd[0]); + + /* Create user namespace to be unprivileged */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + /* Create a network namespace */ + if (unshare(CLONE_NEWNET) < 0) { + close(pipefd[1]); + exit(1); + } + + /* Get our network namespace ID */ + fd = open("/proc/self/ns/net", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &our_netns_id) < 0) { + close(fd); + close(pipefd[1]); + exit(1); + } + close(fd); + + /* Now we're unprivileged - list all network namespaces */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + close(pipefd[1]); + exit(1); + } + + /* We should only see our own network namespace */ + found_ours = false; + unexpected_count = 0; + + for (ssize_t i = 0; i < ret; i++) { + if (ns_ids[i] == our_netns_id) { + found_ours = true; + } else { + /* This is either init_net (which we can see) or unexpected */ + unexpected_count++; + } + } + + /* Send results to parent */ + write(pipefd[1], &found_ours, sizeof(found_ours)); + write(pipefd[1], &unexpected_count, sizeof(unexpected_count)); + close(pipefd[1]); + exit(0); + } + + /* Parent */ + close(pipefd[1]); + + found_ours = false; + unexpected_count = 0; + read(pipefd[0], &found_ours, sizeof(found_ours)); + read(pipefd[0], &unexpected_count, sizeof(unexpected_count)); + close(pipefd[0]); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* Child should have seen its own namespace */ + ASSERT_TRUE(found_ours); + + TH_LOG("Unprivileged child saw its own namespace, plus %d others (likely init_net)", + unexpected_count); +} + +TEST_HARNESS_MAIN From ec382377311b5032bfd9f4844d8a5884d1facbf6 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:02 +0100 Subject: [PATCH 52/75] selftests/namespaces: second listns() permission test Test that users with CAP_SYS_ADMIN in a user namespace can see all namespaces owned by that user namespace. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-49-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../namespaces/listns_permissions_test.c | 100 ++++++++++++++++++ 1 file changed, 100 insertions(+) diff --git a/tools/testing/selftests/namespaces/listns_permissions_test.c b/tools/testing/selftests/namespaces/listns_permissions_test.c index 907fe419ec22..c99c87cca046 100644 --- a/tools/testing/selftests/namespaces/listns_permissions_test.c +++ b/tools/testing/selftests/namespaces/listns_permissions_test.c @@ -128,4 +128,104 @@ TEST(listns_unprivileged_current_only) unexpected_count); } +/* + * Test that users with CAP_SYS_ADMIN in a user namespace can see + * all namespaces owned by that user namespace. + */ +TEST(listns_cap_sys_admin_in_userns) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = 0, /* All types */ + .spare2 = 0, + .user_ns_id = 0, /* Will be set to our created user namespace */ + }; + __u64 ns_ids[100]; + int pipefd[2]; + pid_t pid; + int status; + bool success; + ssize_t count; + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + int fd; + __u64 userns_id; + ssize_t ret; + int min_expected; + bool success; + + close(pipefd[0]); + + /* Create user namespace - we'll have CAP_SYS_ADMIN in it */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + /* Get the user namespace ID */ + fd = open("/proc/self/ns/user", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &userns_id) < 0) { + close(fd); + close(pipefd[1]); + exit(1); + } + close(fd); + + /* Create several namespaces owned by this user namespace */ + unshare(CLONE_NEWNET); + unshare(CLONE_NEWUTS); + unshare(CLONE_NEWIPC); + + /* List namespaces owned by our user namespace */ + req.user_ns_id = userns_id; + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + close(pipefd[1]); + exit(1); + } + + /* + * We have CAP_SYS_ADMIN in this user namespace, + * so we should see all namespaces owned by it. + * That includes: net, uts, ipc, and the user namespace itself. + */ + min_expected = 4; + success = (ret >= min_expected); + + write(pipefd[1], &success, sizeof(success)); + write(pipefd[1], &ret, sizeof(ret)); + close(pipefd[1]); + exit(0); + } + + /* Parent */ + close(pipefd[1]); + + success = false; + count = 0; + read(pipefd[0], &success, sizeof(success)); + read(pipefd[0], &count, sizeof(count)); + close(pipefd[0]); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + ASSERT_TRUE(success); + TH_LOG("User with CAP_SYS_ADMIN saw %zd namespaces owned by their user namespace", + count); +} + TEST_HARNESS_MAIN From 2635f93989bf15456ccfd06df6a1f5a4a3928aa7 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:03 +0100 Subject: [PATCH 53/75] selftests/namespaces: third listns() permission test Test that users cannot see namespaces from unrelated user namespaces. Create two sibling user namespaces, verify they can't see each other's owned namespaces. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-50-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../namespaces/listns_permissions_test.c | 138 ++++++++++++++++++ 1 file changed, 138 insertions(+) diff --git a/tools/testing/selftests/namespaces/listns_permissions_test.c b/tools/testing/selftests/namespaces/listns_permissions_test.c index c99c87cca046..aed7288c7eca 100644 --- a/tools/testing/selftests/namespaces/listns_permissions_test.c +++ b/tools/testing/selftests/namespaces/listns_permissions_test.c @@ -228,4 +228,142 @@ TEST(listns_cap_sys_admin_in_userns) count); } +/* + * Test that users cannot see namespaces from unrelated user namespaces. + * Create two sibling user namespaces, verify they can't see each other's + * owned namespaces. + */ +TEST(listns_cannot_see_sibling_userns_namespaces) +{ + int pipefd[2]; + pid_t pid1, pid2; + int status; + __u64 netns_a_id; + int pipefd2[2]; + bool found_sibling_netns; + + ASSERT_EQ(pipe(pipefd), 0); + + /* Fork first child - creates user namespace A */ + pid1 = fork(); + ASSERT_GE(pid1, 0); + + if (pid1 == 0) { + int fd; + __u64 netns_a_id; + char buf; + + close(pipefd[0]); + + /* Create user namespace A */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + /* Create network namespace owned by user namespace A */ + if (unshare(CLONE_NEWNET) < 0) { + close(pipefd[1]); + exit(1); + } + + /* Get network namespace ID */ + fd = open("/proc/self/ns/net", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &netns_a_id) < 0) { + close(fd); + close(pipefd[1]); + exit(1); + } + close(fd); + + /* Send namespace ID to parent */ + write(pipefd[1], &netns_a_id, sizeof(netns_a_id)); + + /* Keep alive for sibling to check */ + read(pipefd[1], &buf, 1); + close(pipefd[1]); + exit(0); + } + + /* Parent reads namespace A ID */ + close(pipefd[1]); + netns_a_id = 0; + read(pipefd[0], &netns_a_id, sizeof(netns_a_id)); + + TH_LOG("User namespace A created network namespace with ID %llu", + (unsigned long long)netns_a_id); + + /* Fork second child - creates user namespace B */ + ASSERT_EQ(pipe(pipefd2), 0); + + pid2 = fork(); + ASSERT_GE(pid2, 0); + + if (pid2 == 0) { + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWNET, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids[100]; + ssize_t ret; + bool found_sibling_netns; + + close(pipefd[0]); + close(pipefd2[0]); + + /* Create user namespace B (sibling to A) */ + if (setup_userns() < 0) { + close(pipefd2[1]); + exit(1); + } + + /* Try to list all network namespaces */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + + found_sibling_netns = false; + if (ret > 0) { + for (ssize_t i = 0; i < ret; i++) { + if (ns_ids[i] == netns_a_id) { + found_sibling_netns = true; + break; + } + } + } + + /* We should NOT see the sibling's network namespace */ + write(pipefd2[1], &found_sibling_netns, sizeof(found_sibling_netns)); + close(pipefd2[1]); + exit(0); + } + + /* Parent reads result from second child */ + close(pipefd2[1]); + found_sibling_netns = false; + read(pipefd2[0], &found_sibling_netns, sizeof(found_sibling_netns)); + close(pipefd2[0]); + + /* Signal first child to exit */ + close(pipefd[0]); + + /* Wait for both children */ + waitpid(pid2, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + + waitpid(pid1, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + + /* Second child should NOT have seen first child's namespace */ + ASSERT_FALSE(found_sibling_netns); + TH_LOG("User namespace B correctly could not see sibling namespace A's network namespace"); +} + TEST_HARNESS_MAIN From 6f360f2b2f2285ad3cc8072afde0e3eeb2b926e5 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:04 +0100 Subject: [PATCH 54/75] selftests/namespaces: fourth listns() permission test Test permission checking with LISTNS_CURRENT_USER. Verify that listing with LISTNS_CURRENT_USER respects permissions. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-51-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../namespaces/listns_permissions_test.c | 76 +++++++++++++++++++ 1 file changed, 76 insertions(+) diff --git a/tools/testing/selftests/namespaces/listns_permissions_test.c b/tools/testing/selftests/namespaces/listns_permissions_test.c index aed7288c7eca..7727c5964104 100644 --- a/tools/testing/selftests/namespaces/listns_permissions_test.c +++ b/tools/testing/selftests/namespaces/listns_permissions_test.c @@ -366,4 +366,80 @@ TEST(listns_cannot_see_sibling_userns_namespaces) TH_LOG("User namespace B correctly could not see sibling namespace A's network namespace"); } +/* + * Test permission checking with LISTNS_CURRENT_USER. + * Verify that listing with LISTNS_CURRENT_USER respects permissions. + */ +TEST(listns_current_user_permissions) +{ + int pipefd[2]; + pid_t pid; + int status; + bool success; + ssize_t count; + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = 0, + .spare2 = 0, + .user_ns_id = LISTNS_CURRENT_USER, + }; + __u64 ns_ids[100]; + ssize_t ret; + bool success; + + close(pipefd[0]); + + /* Create user namespace */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + /* Create some namespaces owned by this user namespace */ + if (unshare(CLONE_NEWNET) < 0) { + close(pipefd[1]); + exit(1); + } + + if (unshare(CLONE_NEWUTS) < 0) { + close(pipefd[1]); + exit(1); + } + + /* List with LISTNS_CURRENT_USER - should see our owned namespaces */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + + success = (ret >= 3); /* At least user, net, uts */ + write(pipefd[1], &success, sizeof(success)); + write(pipefd[1], &ret, sizeof(ret)); + close(pipefd[1]); + exit(0); + } + + /* Parent */ + close(pipefd[1]); + + success = false; + count = 0; + read(pipefd[0], &success, sizeof(success)); + read(pipefd[0], &count, sizeof(count)); + close(pipefd[0]); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + ASSERT_TRUE(success); + TH_LOG("LISTNS_CURRENT_USER returned %zd namespaces", count); +} + TEST_HARNESS_MAIN From 1c28817eb37eea6593f8734a01b419f33df0ab5b Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:05 +0100 Subject: [PATCH 55/75] selftests/namespaces: fifth listns() permission test Test that CAP_SYS_ADMIN in parent user namespace allows seeing child user namespace's owned namespaces. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-52-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../namespaces/listns_permissions_test.c | 119 ++++++++++++++++++ 1 file changed, 119 insertions(+) diff --git a/tools/testing/selftests/namespaces/listns_permissions_test.c b/tools/testing/selftests/namespaces/listns_permissions_test.c index 7727c5964104..b990b785dd7f 100644 --- a/tools/testing/selftests/namespaces/listns_permissions_test.c +++ b/tools/testing/selftests/namespaces/listns_permissions_test.c @@ -442,4 +442,123 @@ TEST(listns_current_user_permissions) TH_LOG("LISTNS_CURRENT_USER returned %zd namespaces", count); } +/* + * Test that CAP_SYS_ADMIN in parent user namespace allows seeing + * child user namespace's owned namespaces. + */ +TEST(listns_parent_userns_cap_sys_admin) +{ + int pipefd[2]; + pid_t pid; + int status; + bool found_child_userns; + ssize_t count; + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + int fd; + __u64 parent_userns_id; + __u64 child_userns_id; + struct ns_id_req req; + __u64 ns_ids[100]; + ssize_t ret; + bool found_child_userns; + + close(pipefd[0]); + + /* Create parent user namespace - we have CAP_SYS_ADMIN in it */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + /* Get parent user namespace ID */ + fd = open("/proc/self/ns/user", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &parent_userns_id) < 0) { + close(fd); + close(pipefd[1]); + exit(1); + } + close(fd); + + /* Create child user namespace */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + /* Get child user namespace ID */ + fd = open("/proc/self/ns/user", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &child_userns_id) < 0) { + close(fd); + close(pipefd[1]); + exit(1); + } + close(fd); + + /* Create namespaces owned by child user namespace */ + if (unshare(CLONE_NEWNET) < 0) { + close(pipefd[1]); + exit(1); + } + + /* List namespaces owned by parent user namespace */ + req.size = sizeof(req); + req.spare = 0; + req.ns_id = 0; + req.ns_type = 0; + req.spare2 = 0; + req.user_ns_id = parent_userns_id; + + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + + /* Should see child user namespace in the list */ + found_child_userns = false; + if (ret > 0) { + for (ssize_t i = 0; i < ret; i++) { + if (ns_ids[i] == child_userns_id) { + found_child_userns = true; + break; + } + } + } + + write(pipefd[1], &found_child_userns, sizeof(found_child_userns)); + write(pipefd[1], &ret, sizeof(ret)); + close(pipefd[1]); + exit(0); + } + + /* Parent */ + close(pipefd[1]); + + found_child_userns = false; + count = 0; + read(pipefd[0], &found_child_userns, sizeof(found_child_userns)); + read(pipefd[0], &count, sizeof(count)); + close(pipefd[0]); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + ASSERT_TRUE(found_child_userns); + TH_LOG("Process with CAP_SYS_ADMIN in parent user namespace saw child user namespace (total: %zd)", + count); +} + TEST_HARNESS_MAIN From cff66421ee59618c6623008ca7281e7113701631 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:06 +0100 Subject: [PATCH 56/75] selftests/namespaces: sixth listns() permission test Test that we can see user namespaces we have CAP_SYS_ADMIN inside of. This is different from seeing namespaces owned by a user namespace. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-53-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../namespaces/listns_permissions_test.c | 87 +++++++++++++++++++ 1 file changed, 87 insertions(+) diff --git a/tools/testing/selftests/namespaces/listns_permissions_test.c b/tools/testing/selftests/namespaces/listns_permissions_test.c index b990b785dd7f..9aa06ff76333 100644 --- a/tools/testing/selftests/namespaces/listns_permissions_test.c +++ b/tools/testing/selftests/namespaces/listns_permissions_test.c @@ -561,4 +561,91 @@ TEST(listns_parent_userns_cap_sys_admin) count); } +/* + * Test that we can see user namespaces we have CAP_SYS_ADMIN inside of. + * This is different from seeing namespaces owned by a user namespace. + */ +TEST(listns_cap_sys_admin_inside_userns) +{ + int pipefd[2]; + pid_t pid; + int status; + bool found_ours; + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + int fd; + __u64 our_userns_id; + struct ns_id_req req; + __u64 ns_ids[100]; + ssize_t ret; + bool found_ours; + + close(pipefd[0]); + + /* Create user namespace - we have CAP_SYS_ADMIN inside it */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + /* Get our user namespace ID */ + fd = open("/proc/self/ns/user", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &our_userns_id) < 0) { + close(fd); + close(pipefd[1]); + exit(1); + } + close(fd); + + /* List all user namespaces globally */ + req.size = sizeof(req); + req.spare = 0; + req.ns_id = 0; + req.ns_type = CLONE_NEWUSER; + req.spare2 = 0; + req.user_ns_id = 0; + + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + + /* We should be able to see our own user namespace */ + found_ours = false; + if (ret > 0) { + for (ssize_t i = 0; i < ret; i++) { + if (ns_ids[i] == our_userns_id) { + found_ours = true; + break; + } + } + } + + write(pipefd[1], &found_ours, sizeof(found_ours)); + close(pipefd[1]); + exit(0); + } + + /* Parent */ + close(pipefd[1]); + + found_ours = false; + read(pipefd[0], &found_ours, sizeof(found_ours)); + close(pipefd[0]); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + ASSERT_TRUE(found_ours); + TH_LOG("Process can see user namespace it has CAP_SYS_ADMIN inside of"); +} + TEST_HARNESS_MAIN From 39bcc7ae57867110265bbbf60999e85b522ae624 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:07 +0100 Subject: [PATCH 57/75] selftests/namespaces: seventh listns() permission test Test that dropping CAP_SYS_ADMIN restricts what we can see. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-54-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../namespaces/listns_permissions_test.c | 108 ++++++++++++++++++ 1 file changed, 108 insertions(+) diff --git a/tools/testing/selftests/namespaces/listns_permissions_test.c b/tools/testing/selftests/namespaces/listns_permissions_test.c index 9aa06ff76333..82d818751a5f 100644 --- a/tools/testing/selftests/namespaces/listns_permissions_test.c +++ b/tools/testing/selftests/namespaces/listns_permissions_test.c @@ -648,4 +648,112 @@ TEST(listns_cap_sys_admin_inside_userns) TH_LOG("Process can see user namespace it has CAP_SYS_ADMIN inside of"); } +/* + * Test that dropping CAP_SYS_ADMIN restricts what we can see. + */ +TEST(listns_drop_cap_sys_admin) +{ + cap_t caps; + cap_value_t cap_list[1] = { CAP_SYS_ADMIN }; + + /* This test needs to start with CAP_SYS_ADMIN */ + caps = cap_get_proc(); + if (!caps) { + SKIP(return, "Cannot get capabilities"); + } + + cap_flag_value_t cap_val; + if (cap_get_flag(caps, CAP_SYS_ADMIN, CAP_EFFECTIVE, &cap_val) < 0) { + cap_free(caps); + SKIP(return, "Cannot check CAP_SYS_ADMIN"); + } + + if (cap_val != CAP_SET) { + cap_free(caps); + SKIP(return, "Test needs CAP_SYS_ADMIN to start"); + } + cap_free(caps); + + int pipefd[2]; + pid_t pid; + int status; + bool correct; + ssize_t count_before, count_after; + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWNET, + .spare2 = 0, + .user_ns_id = LISTNS_CURRENT_USER, + }; + __u64 ns_ids_before[100]; + ssize_t count_before; + __u64 ns_ids_after[100]; + ssize_t count_after; + bool correct; + + close(pipefd[0]); + + /* Create user namespace */ + if (setup_userns() < 0) { + close(pipefd[1]); + exit(1); + } + + /* Count namespaces with CAP_SYS_ADMIN */ + count_before = sys_listns(&req, ns_ids_before, ARRAY_SIZE(ns_ids_before), 0); + + /* Drop CAP_SYS_ADMIN */ + caps = cap_get_proc(); + if (caps) { + cap_set_flag(caps, CAP_EFFECTIVE, 1, cap_list, CAP_CLEAR); + cap_set_flag(caps, CAP_PERMITTED, 1, cap_list, CAP_CLEAR); + cap_set_proc(caps); + cap_free(caps); + } + + /* Ensure we can't regain the capability */ + prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0); + + /* Count namespaces without CAP_SYS_ADMIN */ + count_after = sys_listns(&req, ns_ids_after, ARRAY_SIZE(ns_ids_after), 0); + + /* Without CAP_SYS_ADMIN, we should see same or fewer namespaces */ + correct = (count_after <= count_before); + + write(pipefd[1], &correct, sizeof(correct)); + write(pipefd[1], &count_before, sizeof(count_before)); + write(pipefd[1], &count_after, sizeof(count_after)); + close(pipefd[1]); + exit(0); + } + + /* Parent */ + close(pipefd[1]); + + correct = false; + count_before = 0; + count_after = 0; + read(pipefd[0], &correct, sizeof(correct)); + read(pipefd[0], &count_before, sizeof(count_before)); + read(pipefd[0], &count_after, sizeof(count_after)); + close(pipefd[0]); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + ASSERT_TRUE(correct); + TH_LOG("With CAP_SYS_ADMIN: %zd namespaces, without: %zd namespaces", + count_before, count_after); +} + TEST_HARNESS_MAIN From a1e49d8d18ba0fc53f1a2d5453af32b6339b67cf Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:08 +0100 Subject: [PATCH 58/75] selftests/namespaces: first inactive namespace resurrection test Test basic SIOCGSKNS functionality. Create a socket and verify SIOCGSKNS returns the correct network namespace. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-55-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- tools/testing/selftests/namespaces/.gitignore | 1 + tools/testing/selftests/namespaces/Makefile | 9 ++- .../selftests/namespaces/siocgskns_test.c | 72 +++++++++++++++++++ 3 files changed, 81 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/namespaces/siocgskns_test.c diff --git a/tools/testing/selftests/namespaces/.gitignore b/tools/testing/selftests/namespaces/.gitignore index 17f9c675a60b..aeb5f2711ff6 100644 --- a/tools/testing/selftests/namespaces/.gitignore +++ b/tools/testing/selftests/namespaces/.gitignore @@ -4,3 +4,4 @@ init_ino_test ns_active_ref_test listns_test listns_permissions_test +siocgskns_test diff --git a/tools/testing/selftests/namespaces/Makefile b/tools/testing/selftests/namespaces/Makefile index 2dd22bc68b89..d456505189cd 100644 --- a/tools/testing/selftests/namespaces/Makefile +++ b/tools/testing/selftests/namespaces/Makefile @@ -2,11 +2,18 @@ CFLAGS += -Wall -O0 -g $(KHDR_INCLUDES) $(TOOLS_INCLUDES) LDLIBS += -lcap -TEST_GEN_PROGS := nsid_test file_handle_test init_ino_test ns_active_ref_test listns_test listns_permissions_test +TEST_GEN_PROGS := nsid_test \ + file_handle_test \ + init_ino_test \ + ns_active_ref_test \ + listns_test \ + listns_permissions_test \ + siocgskns_test include ../lib.mk $(OUTPUT)/ns_active_ref_test: ../filesystems/utils.c $(OUTPUT)/listns_test: ../filesystems/utils.c $(OUTPUT)/listns_permissions_test: ../filesystems/utils.c +$(OUTPUT)/siocgskns_test: ../filesystems/utils.c diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c new file mode 100644 index 000000000000..0c9098624cd4 --- /dev/null +++ b/tools/testing/selftests/namespaces/siocgskns_test.c @@ -0,0 +1,72 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "../kselftest_harness.h" +#include "../filesystems/utils.h" +#include "wrappers.h" + +#ifndef SIOCGSKNS +#define SIOCGSKNS 0x894C +#endif + +#ifndef FD_NSFS_ROOT +#define FD_NSFS_ROOT -10003 +#endif + +#ifndef FILEID_NSFS +#define FILEID_NSFS 0xf1 +#endif + +/* + * Test basic SIOCGSKNS functionality. + * Create a socket and verify SIOCGSKNS returns the correct network namespace. + */ +TEST(siocgskns_basic) +{ + int sock_fd, netns_fd, current_netns_fd; + struct stat st1, st2; + + /* Create a TCP socket */ + sock_fd = socket(AF_INET, SOCK_STREAM, 0); + ASSERT_GE(sock_fd, 0); + + /* Use SIOCGSKNS to get network namespace */ + netns_fd = ioctl(sock_fd, SIOCGSKNS); + if (netns_fd < 0) { + close(sock_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "SIOCGSKNS not supported"); + ASSERT_GE(netns_fd, 0); + } + + /* Get current network namespace */ + current_netns_fd = open("/proc/self/ns/net", O_RDONLY); + ASSERT_GE(current_netns_fd, 0); + + /* Verify they match */ + ASSERT_EQ(fstat(netns_fd, &st1), 0); + ASSERT_EQ(fstat(current_netns_fd, &st2), 0); + ASSERT_EQ(st1.st_ino, st2.st_ino); + + close(sock_fd); + close(netns_fd); + close(current_netns_fd); +} + +TEST_HARNESS_MAIN From c0f06da56860f185268b77cb23c4b3c85518e87a Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:09 +0100 Subject: [PATCH 59/75] selftests/namespaces: second inactive namespace resurrection test Test that socket file descriptors keep network namespaces active. Create a network namespace, create a socket in it, then exit the namespace. The namespace should remain active while the socket FD is held. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-56-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/siocgskns_test.c | 126 ++++++++++++++++++ 1 file changed, 126 insertions(+) diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c index 0c9098624cd4..0ad5e39b7e16 100644 --- a/tools/testing/selftests/namespaces/siocgskns_test.c +++ b/tools/testing/selftests/namespaces/siocgskns_test.c @@ -69,4 +69,130 @@ TEST(siocgskns_basic) close(current_netns_fd); } +/* + * Test that socket file descriptors keep network namespaces active. + * Create a network namespace, create a socket in it, then exit the namespace. + * The namespace should remain active while the socket FD is held. + */ +TEST(siocgskns_keeps_netns_active) +{ + int sock_fd, netns_fd, test_fd; + int ipc_sockets[2]; + pid_t pid; + int status; + struct stat st; + + EXPECT_EQ(socketpair(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child: create new netns and socket */ + close(ipc_sockets[0]); + + if (unshare(CLONE_NEWNET) < 0) { + TH_LOG("unshare(CLONE_NEWNET) failed: %s", strerror(errno)); + close(ipc_sockets[1]); + exit(1); + } + + /* Create a socket in the new network namespace */ + sock_fd = socket(AF_INET, SOCK_DGRAM, 0); + if (sock_fd < 0) { + TH_LOG("socket() failed: %s", strerror(errno)); + close(ipc_sockets[1]); + exit(1); + } + + /* Send socket FD to parent via SCM_RIGHTS */ + struct msghdr msg = {0}; + struct iovec iov = {0}; + char buf[1] = {'X'}; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); + memcpy(CMSG_DATA(cmsg), &sock_fd, sizeof(int)); + + if (sendmsg(ipc_sockets[1], &msg, 0) < 0) { + close(sock_fd); + close(ipc_sockets[1]); + exit(1); + } + + close(sock_fd); + close(ipc_sockets[1]); + exit(0); + } + + /* Parent: receive socket FD */ + close(ipc_sockets[1]); + + struct msghdr msg = {0}; + struct iovec iov = {0}; + char buf[1]; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + ssize_t n = recvmsg(ipc_sockets[0], &msg, 0); + close(ipc_sockets[0]); + ASSERT_EQ(n, 1); + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + ASSERT_NE(cmsg, NULL); + ASSERT_EQ(cmsg->cmsg_type, SCM_RIGHTS); + + memcpy(&sock_fd, CMSG_DATA(cmsg), sizeof(int)); + + /* Wait for child to exit */ + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + if (WEXITSTATUS(status) != 0) + SKIP(close(sock_fd); return, "Child failed to create namespace"); + + /* Get network namespace from socket */ + netns_fd = ioctl(sock_fd, SIOCGSKNS); + if (netns_fd < 0) { + close(sock_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "SIOCGSKNS not supported"); + ASSERT_GE(netns_fd, 0); + } + + ASSERT_EQ(fstat(netns_fd, &st), 0); + + /* + * Namespace should still be active because socket FD keeps it alive. + * Try to access it via /proc/self/fd/. + */ + char path[64]; + snprintf(path, sizeof(path), "/proc/self/fd/%d", netns_fd); + test_fd = open(path, O_RDONLY); + ASSERT_GE(test_fd, 0); + close(test_fd); + close(netns_fd); + + /* Close socket - namespace should become inactive */ + close(sock_fd); + + /* Try SIOCGSKNS again - should fail since socket is closed */ + ASSERT_LT(ioctl(sock_fd, SIOCGSKNS), 0); +} + TEST_HARNESS_MAIN From 5aec9f455ced4004f758d8619cda69e979734670 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:10 +0100 Subject: [PATCH 60/75] selftests/namespaces: third inactive namespace resurrection test Test SIOCGSKNS with different socket types (TCP, UDP, RAW). Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-57-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/siocgskns_test.c | 65 ++++++++++++++++++- 1 file changed, 63 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c index 0ad5e39b7e16..02798e59fc11 100644 --- a/tools/testing/selftests/namespaces/siocgskns_test.c +++ b/tools/testing/selftests/namespaces/siocgskns_test.c @@ -163,8 +163,7 @@ TEST(siocgskns_keeps_netns_active) /* Wait for child to exit */ waitpid(pid, &status, 0); ASSERT_TRUE(WIFEXITED(status)); - if (WEXITSTATUS(status) != 0) - SKIP(close(sock_fd); return, "Child failed to create namespace"); + ASSERT_EQ(WEXITSTATUS(status), 0); /* Get network namespace from socket */ netns_fd = ioctl(sock_fd, SIOCGSKNS); @@ -195,4 +194,66 @@ TEST(siocgskns_keeps_netns_active) ASSERT_LT(ioctl(sock_fd, SIOCGSKNS), 0); } +/* + * Test SIOCGSKNS with different socket types (TCP, UDP, RAW). + */ +TEST(siocgskns_socket_types) +{ + int sock_tcp, sock_udp, sock_raw; + int netns_tcp, netns_udp, netns_raw; + struct stat st_tcp, st_udp, st_raw; + + /* TCP socket */ + sock_tcp = socket(AF_INET, SOCK_STREAM, 0); + ASSERT_GE(sock_tcp, 0); + + /* UDP socket */ + sock_udp = socket(AF_INET, SOCK_DGRAM, 0); + ASSERT_GE(sock_udp, 0); + + /* RAW socket (may require privileges) */ + sock_raw = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP); + if (sock_raw < 0 && (errno == EPERM || errno == EACCES)) { + sock_raw = -1; /* Skip raw socket test */ + } + + /* Test SIOCGSKNS on TCP */ + netns_tcp = ioctl(sock_tcp, SIOCGSKNS); + if (netns_tcp < 0) { + close(sock_tcp); + close(sock_udp); + if (sock_raw >= 0) close(sock_raw); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "SIOCGSKNS not supported"); + ASSERT_GE(netns_tcp, 0); + } + + /* Test SIOCGSKNS on UDP */ + netns_udp = ioctl(sock_udp, SIOCGSKNS); + ASSERT_GE(netns_udp, 0); + + /* Test SIOCGSKNS on RAW (if available) */ + if (sock_raw >= 0) { + netns_raw = ioctl(sock_raw, SIOCGSKNS); + ASSERT_GE(netns_raw, 0); + } + + /* Verify all return the same network namespace */ + ASSERT_EQ(fstat(netns_tcp, &st_tcp), 0); + ASSERT_EQ(fstat(netns_udp, &st_udp), 0); + ASSERT_EQ(st_tcp.st_ino, st_udp.st_ino); + + if (sock_raw >= 0) { + ASSERT_EQ(fstat(netns_raw, &st_raw), 0); + ASSERT_EQ(st_tcp.st_ino, st_raw.st_ino); + close(netns_raw); + close(sock_raw); + } + + close(netns_tcp); + close(netns_udp); + close(sock_tcp); + close(sock_udp); +} + TEST_HARNESS_MAIN From 40226da47124bdf454503f00a948585b7403c73a Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:11 +0100 Subject: [PATCH 61/75] selftests/namespaces: fourth inactive namespace resurrection test Test SIOCGSKNS across setns. Create a socket in netns A, switch to netns B, verify SIOCGSKNS still returns netns A. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-58-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/siocgskns_test.c | 51 +++++++++++++++++++ 1 file changed, 51 insertions(+) diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c index 02798e59fc11..28e45954c4fa 100644 --- a/tools/testing/selftests/namespaces/siocgskns_test.c +++ b/tools/testing/selftests/namespaces/siocgskns_test.c @@ -256,4 +256,55 @@ TEST(siocgskns_socket_types) close(sock_udp); } +/* + * Test SIOCGSKNS across setns. + * Create a socket in netns A, switch to netns B, verify SIOCGSKNS still + * returns netns A. + */ +TEST(siocgskns_across_setns) +{ + int sock_fd, netns_a_fd, netns_b_fd, result_fd; + struct stat st_a; + + /* Get current netns (A) */ + netns_a_fd = open("/proc/self/ns/net", O_RDONLY); + ASSERT_GE(netns_a_fd, 0); + ASSERT_EQ(fstat(netns_a_fd, &st_a), 0); + + /* Create socket in netns A */ + sock_fd = socket(AF_INET, SOCK_STREAM, 0); + ASSERT_GE(sock_fd, 0); + + /* Create new netns (B) */ + ASSERT_EQ(unshare(CLONE_NEWNET), 0); + + netns_b_fd = open("/proc/self/ns/net", O_RDONLY); + ASSERT_GE(netns_b_fd, 0); + + /* Get netns from socket created in A */ + result_fd = ioctl(sock_fd, SIOCGSKNS); + if (result_fd < 0) { + close(sock_fd); + setns(netns_a_fd, CLONE_NEWNET); + close(netns_a_fd); + close(netns_b_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "SIOCGSKNS not supported"); + ASSERT_GE(result_fd, 0); + } + + /* Verify it still points to netns A */ + struct stat st_result_stat; + ASSERT_EQ(fstat(result_fd, &st_result_stat), 0); + ASSERT_EQ(st_a.st_ino, st_result_stat.st_ino); + + close(result_fd); + close(sock_fd); + close(netns_b_fd); + + /* Restore original netns */ + ASSERT_EQ(setns(netns_a_fd, CLONE_NEWNET), 0); + close(netns_a_fd); +} + TEST_HARNESS_MAIN From 2b9fa5bf0c417c444d3c572dfe2138da7fdf11cd Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:12 +0100 Subject: [PATCH 62/75] selftests/namespaces: fifth inactive namespace resurrection test Test SIOCGSKNS fails on non-socket file descriptors. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-59-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/siocgskns_test.c | 26 +++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c index 28e45954c4fa..bbfef3c51ac1 100644 --- a/tools/testing/selftests/namespaces/siocgskns_test.c +++ b/tools/testing/selftests/namespaces/siocgskns_test.c @@ -307,4 +307,30 @@ TEST(siocgskns_across_setns) close(netns_a_fd); } +/* + * Test SIOCGSKNS fails on non-socket file descriptors. + */ +TEST(siocgskns_non_socket) +{ + int fd; + int pipefd[2]; + + /* Test on regular file */ + fd = open("/dev/null", O_RDONLY); + ASSERT_GE(fd, 0); + + ASSERT_LT(ioctl(fd, SIOCGSKNS), 0); + ASSERT_TRUE(errno == ENOTTY || errno == EINVAL); + close(fd); + + /* Test on pipe */ + ASSERT_EQ(pipe(pipefd), 0); + + ASSERT_LT(ioctl(pipefd[0], SIOCGSKNS), 0); + ASSERT_TRUE(errno == ENOTTY || errno == EINVAL); + + close(pipefd[0]); + close(pipefd[1]); +} + TEST_HARNESS_MAIN From aec2237695289cf0654e936e86acc8e898882850 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:13 +0100 Subject: [PATCH 63/75] selftests/namespaces: sixth inactive namespace resurrection test Test multiple sockets keep the same network namespace active. Create multiple sockets, verify closing some doesn't affect others. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-60-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/siocgskns_test.c | 68 +++++++++++++++++++ 1 file changed, 68 insertions(+) diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c index bbfef3c51ac1..231830daf5dc 100644 --- a/tools/testing/selftests/namespaces/siocgskns_test.c +++ b/tools/testing/selftests/namespaces/siocgskns_test.c @@ -333,4 +333,72 @@ TEST(siocgskns_non_socket) close(pipefd[1]); } +/* + * Test multiple sockets keep the same network namespace active. + * Create multiple sockets, verify closing some doesn't affect others. + */ +TEST(siocgskns_multiple_sockets) +{ + int socks[5]; + int netns_fds[5]; + int i; + struct stat st; + ino_t netns_ino; + + /* Create new network namespace */ + ASSERT_EQ(unshare(CLONE_NEWNET), 0); + + /* Create multiple sockets */ + for (i = 0; i < 5; i++) { + socks[i] = socket(AF_INET, SOCK_STREAM, 0); + ASSERT_GE(socks[i], 0); + } + + /* Get netns from all sockets */ + for (i = 0; i < 5; i++) { + netns_fds[i] = ioctl(socks[i], SIOCGSKNS); + if (netns_fds[i] < 0) { + int j; + for (j = 0; j <= i; j++) { + close(socks[j]); + if (j < i && netns_fds[j] >= 0) + close(netns_fds[j]); + } + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "SIOCGSKNS not supported"); + ASSERT_GE(netns_fds[i], 0); + } + } + + /* Verify all point to same netns */ + ASSERT_EQ(fstat(netns_fds[0], &st), 0); + netns_ino = st.st_ino; + + for (i = 1; i < 5; i++) { + ASSERT_EQ(fstat(netns_fds[i], &st), 0); + ASSERT_EQ(st.st_ino, netns_ino); + } + + /* Close some sockets */ + for (i = 0; i < 3; i++) { + close(socks[i]); + } + + /* Remaining netns FDs should still be valid */ + for (i = 3; i < 5; i++) { + char path[64]; + snprintf(path, sizeof(path), "/proc/self/fd/%d", netns_fds[i]); + int test_fd = open(path, O_RDONLY); + ASSERT_GE(test_fd, 0); + close(test_fd); + } + + /* Cleanup */ + for (i = 0; i < 5; i++) { + if (i >= 3) + close(socks[i]); + close(netns_fds[i]); + } +} + TEST_HARNESS_MAIN From 54a29d1233815287034b0b87f20e46dfe20da0e4 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:14 +0100 Subject: [PATCH 64/75] selftests/namespaces: seventh inactive namespace resurrection test Test socket keeps netns active after creating process exits. Verify that as long as the socket FD exists, the namespace remains active. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-61-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/siocgskns_test.c | 141 ++++++++++++++++++ 1 file changed, 141 insertions(+) diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c index 231830daf5dc..60028eeecde0 100644 --- a/tools/testing/selftests/namespaces/siocgskns_test.c +++ b/tools/testing/selftests/namespaces/siocgskns_test.c @@ -401,4 +401,145 @@ TEST(siocgskns_multiple_sockets) } } +/* + * Test socket keeps netns active after creating process exits. + * Verify that as long as the socket FD exists, the namespace remains active. + */ +TEST(siocgskns_netns_lifecycle) +{ + int sock_fd, netns_fd; + int ipc_sockets[2]; + int syncpipe[2]; + pid_t pid; + int status; + char sync_byte; + struct stat st; + ino_t netns_ino; + + EXPECT_EQ(socketpair(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets), 0); + + ASSERT_EQ(pipe(syncpipe), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child */ + close(ipc_sockets[0]); + close(syncpipe[1]); + + if (unshare(CLONE_NEWNET) < 0) { + close(ipc_sockets[1]); + close(syncpipe[0]); + exit(1); + } + + sock_fd = socket(AF_INET, SOCK_STREAM, 0); + if (sock_fd < 0) { + close(ipc_sockets[1]); + close(syncpipe[0]); + exit(1); + } + + /* Send socket to parent */ + struct msghdr msg = {0}; + struct iovec iov = {0}; + char buf[1] = {'X'}; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); + memcpy(CMSG_DATA(cmsg), &sock_fd, sizeof(int)); + + if (sendmsg(ipc_sockets[1], &msg, 0) < 0) { + close(sock_fd); + close(ipc_sockets[1]); + close(syncpipe[0]); + exit(1); + } + + close(sock_fd); + close(ipc_sockets[1]); + + /* Wait for parent signal */ + read(syncpipe[0], &sync_byte, 1); + close(syncpipe[0]); + exit(0); + } + + /* Parent */ + close(ipc_sockets[1]); + close(syncpipe[0]); + + /* Receive socket FD */ + struct msghdr msg = {0}; + struct iovec iov = {0}; + char buf[1]; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + ssize_t n = recvmsg(ipc_sockets[0], &msg, 0); + close(ipc_sockets[0]); + ASSERT_EQ(n, 1); + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + ASSERT_NE(cmsg, NULL); + memcpy(&sock_fd, CMSG_DATA(cmsg), sizeof(int)); + + /* Get netns from socket while child is alive */ + netns_fd = ioctl(sock_fd, SIOCGSKNS); + if (netns_fd < 0) { + sync_byte = 'G'; + write(syncpipe[1], &sync_byte, 1); + close(syncpipe[1]); + close(sock_fd); + waitpid(pid, NULL, 0); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "SIOCGSKNS not supported"); + ASSERT_GE(netns_fd, 0); + } + ASSERT_EQ(fstat(netns_fd, &st), 0); + netns_ino = st.st_ino; + + /* Signal child to exit */ + sync_byte = 'G'; + write(syncpipe[1], &sync_byte, 1); + close(syncpipe[1]); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + + /* + * Socket FD should still keep namespace active even after + * the creating process exited. + */ + int test_fd = ioctl(sock_fd, SIOCGSKNS); + ASSERT_GE(test_fd, 0); + + struct stat st_test; + ASSERT_EQ(fstat(test_fd, &st_test), 0); + ASSERT_EQ(st_test.st_ino, netns_ino); + + close(test_fd); + close(netns_fd); + + /* Close socket - namespace should become inactive */ + close(sock_fd); +} + TEST_HARNESS_MAIN From 6de17ec3ccc1eab51601f1b37332cdb384a3a3c9 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:15 +0100 Subject: [PATCH 65/75] selftests/namespaces: eigth inactive namespace resurrection test Test IPv6 sockets also work with SIOCGSKNS. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-62-2e6f823ebdc0@kernel.org Tested-by: syzbot@syzkaller.appspotmail.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/siocgskns_test.c | 34 +++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c index 60028eeecde0..47c1524a8648 100644 --- a/tools/testing/selftests/namespaces/siocgskns_test.c +++ b/tools/testing/selftests/namespaces/siocgskns_test.c @@ -542,4 +542,38 @@ TEST(siocgskns_netns_lifecycle) close(sock_fd); } +/* + * Test IPv6 sockets also work with SIOCGSKNS. + */ +TEST(siocgskns_ipv6) +{ + int sock_fd, netns_fd, current_netns_fd; + struct stat st1, st2; + + /* Create an IPv6 TCP socket */ + sock_fd = socket(AF_INET6, SOCK_STREAM, 0); + ASSERT_GE(sock_fd, 0); + + /* Use SIOCGSKNS */ + netns_fd = ioctl(sock_fd, SIOCGSKNS); + if (netns_fd < 0) { + close(sock_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "SIOCGSKNS not supported"); + ASSERT_GE(netns_fd, 0); + } + + /* Verify it matches current namespace */ + current_netns_fd = open("/proc/self/ns/net", O_RDONLY); + ASSERT_GE(current_netns_fd, 0); + + ASSERT_EQ(fstat(netns_fd, &st1), 0); + ASSERT_EQ(fstat(current_netns_fd, &st2), 0); + ASSERT_EQ(st1.st_ino, st2.st_ino); + + close(sock_fd); + close(netns_fd); + close(current_netns_fd); +} + TEST_HARNESS_MAIN From b9d09f568b350cac63344c7e526996c2e6f2363f Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:16 +0100 Subject: [PATCH 66/75] selftests/namespaces: ninth inactive namespace resurrection test Test that socket-kept netns appears in listns() output. Verify that a network namespace kept alive by a socket FD appears in listns() output even after the creating process exits, and that it disappears when the socket is closed. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-63-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/siocgskns_test.c | 203 ++++++++++++++++++ 1 file changed, 203 insertions(+) diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c index 47c1524a8648..98f6a0e1b9dd 100644 --- a/tools/testing/selftests/namespaces/siocgskns_test.c +++ b/tools/testing/selftests/namespaces/siocgskns_test.c @@ -576,4 +576,207 @@ TEST(siocgskns_ipv6) close(current_netns_fd); } +/* + * Test that socket-kept netns appears in listns() output. + * Verify that a network namespace kept alive by a socket FD appears in + * listns() output even after the creating process exits, and that it + * disappears when the socket is closed. + */ +TEST(siocgskns_listns_visibility) +{ + int sock_fd, netns_fd, owner_fd; + int ipc_sockets[2]; + pid_t pid; + int status; + __u64 netns_id, owner_id; + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWNET, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids[256]; + int ret, i; + bool found_netns = false; + + EXPECT_EQ(socketpair(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child: create new netns and socket */ + close(ipc_sockets[0]); + + if (unshare(CLONE_NEWNET) < 0) { + close(ipc_sockets[1]); + exit(1); + } + + sock_fd = socket(AF_INET, SOCK_DGRAM, 0); + if (sock_fd < 0) { + close(ipc_sockets[1]); + exit(1); + } + + /* Send socket FD to parent via SCM_RIGHTS */ + struct msghdr msg = {0}; + struct iovec iov = {0}; + char buf[1] = {'X'}; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); + memcpy(CMSG_DATA(cmsg), &sock_fd, sizeof(int)); + + if (sendmsg(ipc_sockets[1], &msg, 0) < 0) { + close(sock_fd); + close(ipc_sockets[1]); + exit(1); + } + + close(sock_fd); + close(ipc_sockets[1]); + exit(0); + } + + /* Parent: receive socket FD */ + close(ipc_sockets[1]); + + struct msghdr msg = {0}; + struct iovec iov = {0}; + char buf[1]; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + ssize_t n = recvmsg(ipc_sockets[0], &msg, 0); + close(ipc_sockets[0]); + ASSERT_EQ(n, 1); + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + ASSERT_NE(cmsg, NULL); + memcpy(&sock_fd, CMSG_DATA(cmsg), sizeof(int)); + + /* Wait for child to exit */ + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* Get network namespace from socket */ + netns_fd = ioctl(sock_fd, SIOCGSKNS); + if (netns_fd < 0) { + close(sock_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "SIOCGSKNS not supported"); + ASSERT_GE(netns_fd, 0); + } + + /* Get namespace ID */ + ret = ioctl(netns_fd, NS_GET_ID, &netns_id); + if (ret < 0) { + close(sock_fd); + close(netns_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "NS_GET_ID not supported"); + ASSERT_EQ(ret, 0); + } + + /* Get owner user namespace */ + owner_fd = ioctl(netns_fd, NS_GET_USERNS); + if (owner_fd < 0) { + close(sock_fd); + close(netns_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "NS_GET_USERNS not supported"); + ASSERT_GE(owner_fd, 0); + } + + /* Get owner namespace ID */ + ret = ioctl(owner_fd, NS_GET_ID, &owner_id); + if (ret < 0) { + close(owner_fd); + close(sock_fd); + close(netns_fd); + ASSERT_EQ(ret, 0); + } + close(owner_fd); + + /* Namespace should appear in listns() output */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + close(sock_fd); + close(netns_fd); + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + TH_LOG("listns failed: %s", strerror(errno)); + ASSERT_GE(ret, 0); + } + + /* Search for our network namespace in the list */ + for (i = 0; i < ret; i++) { + if (ns_ids[i] == netns_id) { + found_netns = true; + break; + } + } + + ASSERT_TRUE(found_netns); + TH_LOG("Found netns %llu in listns() output (kept alive by socket)", netns_id); + + /* Now verify with owner filtering */ + req.user_ns_id = owner_id; + found_netns = false; + + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + ASSERT_GE(ret, 0); + + for (i = 0; i < ret; i++) { + if (ns_ids[i] == netns_id) { + found_netns = true; + break; + } + } + + ASSERT_TRUE(found_netns); + TH_LOG("Found netns %llu owned by userns %llu", netns_id, owner_id); + + /* Close socket - namespace should become inactive and disappear from listns() */ + close(sock_fd); + close(netns_fd); + + /* Verify it's no longer in listns() output */ + req.user_ns_id = 0; + found_netns = false; + + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + ASSERT_GE(ret, 0); + + for (i = 0; i < ret; i++) { + if (ns_ids[i] == netns_id) { + found_netns = true; + break; + } + } + + ASSERT_FALSE(found_netns); + TH_LOG("Netns %llu correctly disappeared from listns() after socket closed", netns_id); +} + TEST_HARNESS_MAIN From 3798991a9f56779c1020ca5035edbbe15670a34a Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:17 +0100 Subject: [PATCH 67/75] selftests/namespaces: tenth inactive namespace resurrection test Test that socket-kept netns can be reopened via file handle. Verify that a network namespace kept alive by a socket FD can be reopened using file handles even after the creating process exits. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-64-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/siocgskns_test.c | 195 ++++++++++++++++++ 1 file changed, 195 insertions(+) diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c index 98f6a0e1b9dd..a909232dba36 100644 --- a/tools/testing/selftests/namespaces/siocgskns_test.c +++ b/tools/testing/selftests/namespaces/siocgskns_test.c @@ -779,4 +779,199 @@ TEST(siocgskns_listns_visibility) TH_LOG("Netns %llu correctly disappeared from listns() after socket closed", netns_id); } +/* + * Test that socket-kept netns can be reopened via file handle. + * Verify that a network namespace kept alive by a socket FD can be + * reopened using file handles even after the creating process exits. + */ +TEST(siocgskns_file_handle) +{ + int sock_fd, netns_fd, reopened_fd; + int ipc_sockets[2]; + pid_t pid; + int status; + struct stat st1, st2; + ino_t netns_ino; + __u64 netns_id; + struct file_handle *handle; + struct nsfs_file_handle *nsfs_fh; + int ret; + + /* Allocate file_handle structure for nsfs */ + handle = malloc(sizeof(struct file_handle) + sizeof(struct nsfs_file_handle)); + ASSERT_NE(handle, NULL); + handle->handle_bytes = sizeof(struct nsfs_file_handle); + handle->handle_type = FILEID_NSFS; + + EXPECT_EQ(socketpair(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child: create new netns and socket */ + close(ipc_sockets[0]); + + if (unshare(CLONE_NEWNET) < 0) { + close(ipc_sockets[1]); + exit(1); + } + + sock_fd = socket(AF_INET, SOCK_DGRAM, 0); + if (sock_fd < 0) { + close(ipc_sockets[1]); + exit(1); + } + + /* Send socket FD to parent via SCM_RIGHTS */ + struct msghdr msg = {0}; + struct iovec iov = {0}; + char buf[1] = {'X'}; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); + memcpy(CMSG_DATA(cmsg), &sock_fd, sizeof(int)); + + if (sendmsg(ipc_sockets[1], &msg, 0) < 0) { + close(sock_fd); + close(ipc_sockets[1]); + exit(1); + } + + close(sock_fd); + close(ipc_sockets[1]); + exit(0); + } + + /* Parent: receive socket FD */ + close(ipc_sockets[1]); + + struct msghdr msg = {0}; + struct iovec iov = {0}; + char buf[1]; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + ssize_t n = recvmsg(ipc_sockets[0], &msg, 0); + close(ipc_sockets[0]); + ASSERT_EQ(n, 1); + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + ASSERT_NE(cmsg, NULL); + memcpy(&sock_fd, CMSG_DATA(cmsg), sizeof(int)); + + /* Wait for child to exit */ + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* Get network namespace from socket */ + netns_fd = ioctl(sock_fd, SIOCGSKNS); + if (netns_fd < 0) { + free(handle); + close(sock_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "SIOCGSKNS not supported"); + ASSERT_GE(netns_fd, 0); + } + + ASSERT_EQ(fstat(netns_fd, &st1), 0); + netns_ino = st1.st_ino; + + /* Get namespace ID */ + ret = ioctl(netns_fd, NS_GET_ID, &netns_id); + if (ret < 0) { + free(handle); + close(sock_fd); + close(netns_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "NS_GET_ID not supported"); + ASSERT_EQ(ret, 0); + } + + /* Construct file handle from namespace ID */ + nsfs_fh = (struct nsfs_file_handle *)handle->f_handle; + nsfs_fh->ns_id = netns_id; + nsfs_fh->ns_type = 0; /* Type field not needed for reopening */ + nsfs_fh->ns_inum = 0; /* Inum field not needed for reopening */ + + TH_LOG("Constructed file handle for netns %lu (id=%llu)", netns_ino, netns_id); + + /* Reopen namespace using file handle (while socket still keeps it alive) */ + reopened_fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + if (reopened_fd < 0) { + free(handle); + close(sock_fd); + if (errno == EOPNOTSUPP || errno == ENOSYS || errno == EBADF) + SKIP(return, "open_by_handle_at with FD_NSFS_ROOT not supported"); + TH_LOG("open_by_handle_at failed: %s", strerror(errno)); + ASSERT_GE(reopened_fd, 0); + } + + /* Verify it's the same namespace */ + ASSERT_EQ(fstat(reopened_fd, &st2), 0); + ASSERT_EQ(st1.st_ino, st2.st_ino); + ASSERT_EQ(st1.st_dev, st2.st_dev); + + TH_LOG("Successfully reopened netns %lu via file handle", netns_ino); + + close(reopened_fd); + + /* Close the netns FD */ + close(netns_fd); + + /* Try to reopen via file handle - should fail since namespace is now inactive */ + reopened_fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + ASSERT_LT(reopened_fd, 0); + TH_LOG("Correctly failed to reopen inactive netns: %s", strerror(errno)); + + /* Get network namespace from socket */ + netns_fd = ioctl(sock_fd, SIOCGSKNS); + if (netns_fd < 0) { + free(handle); + close(sock_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "SIOCGSKNS not supported"); + ASSERT_GE(netns_fd, 0); + } + + /* Reopen namespace using file handle (while socket still keeps it alive) */ + reopened_fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + if (reopened_fd < 0) { + free(handle); + close(sock_fd); + if (errno == EOPNOTSUPP || errno == ENOSYS || errno == EBADF) + SKIP(return, "open_by_handle_at with FD_NSFS_ROOT not supported"); + TH_LOG("open_by_handle_at failed: %s", strerror(errno)); + ASSERT_GE(reopened_fd, 0); + } + + /* Verify it's the same namespace */ + ASSERT_EQ(fstat(reopened_fd, &st2), 0); + ASSERT_EQ(st1.st_ino, st2.st_ino); + ASSERT_EQ(st1.st_dev, st2.st_dev); + + TH_LOG("Successfully reopened netns %lu via file handle", netns_ino); + + /* Close socket - namespace should become inactive */ + close(sock_fd); + free(handle); +} + TEST_HARNESS_MAIN From c80168b677fbdbefecb5fb270a325f2928005687 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:18 +0100 Subject: [PATCH 68/75] selftests/namespaces: eleventh inactive namespace resurrection test Test combined listns() and file handle operations with socket-kept netns. Create a netns, keep it alive with a socket, verify it appears in listns(), then reopen it via file handle obtained from listns() entry. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-65-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/siocgskns_test.c | 283 ++++++++++++++++++ 1 file changed, 283 insertions(+) diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c index a909232dba36..706049768d52 100644 --- a/tools/testing/selftests/namespaces/siocgskns_test.c +++ b/tools/testing/selftests/namespaces/siocgskns_test.c @@ -974,4 +974,287 @@ TEST(siocgskns_file_handle) free(handle); } +/* + * Test combined listns() and file handle operations with socket-kept netns. + * Create a netns, keep it alive with a socket, verify it appears in listns(), + * then reopen it via file handle obtained from listns() entry. + */ +TEST(siocgskns_listns_and_file_handle) +{ + int sock_fd, netns_fd, userns_fd, reopened_fd; + int ipc_sockets[2]; + pid_t pid; + int status; + struct stat st; + ino_t netns_ino; + __u64 netns_id, userns_id; + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWNET | CLONE_NEWUSER, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids[256]; + int ret, i; + bool found_netns = false, found_userns = false; + struct file_handle *handle; + struct nsfs_file_handle *nsfs_fh; + + /* Allocate file_handle structure for nsfs */ + handle = malloc(sizeof(struct file_handle) + sizeof(struct nsfs_file_handle)); + ASSERT_NE(handle, NULL); + handle->handle_bytes = sizeof(struct nsfs_file_handle); + handle->handle_type = FILEID_NSFS; + + EXPECT_EQ(socketpair(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child: create new userns and netns with socket */ + close(ipc_sockets[0]); + + if (setup_userns() < 0) { + close(ipc_sockets[1]); + exit(1); + } + + if (unshare(CLONE_NEWNET) < 0) { + close(ipc_sockets[1]); + exit(1); + } + + sock_fd = socket(AF_INET, SOCK_DGRAM, 0); + if (sock_fd < 0) { + close(ipc_sockets[1]); + exit(1); + } + + /* Send socket FD to parent via SCM_RIGHTS */ + struct msghdr msg = {0}; + struct iovec iov = {0}; + char buf[1] = {'X'}; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); + memcpy(CMSG_DATA(cmsg), &sock_fd, sizeof(int)); + + if (sendmsg(ipc_sockets[1], &msg, 0) < 0) { + close(sock_fd); + close(ipc_sockets[1]); + exit(1); + } + + close(sock_fd); + close(ipc_sockets[1]); + exit(0); + } + + /* Parent: receive socket FD */ + close(ipc_sockets[1]); + + struct msghdr msg = {0}; + struct iovec iov = {0}; + char buf[1]; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + ssize_t n = recvmsg(ipc_sockets[0], &msg, 0); + close(ipc_sockets[0]); + ASSERT_EQ(n, 1); + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + ASSERT_NE(cmsg, NULL); + memcpy(&sock_fd, CMSG_DATA(cmsg), sizeof(int)); + + /* Wait for child to exit */ + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* Get network namespace from socket */ + netns_fd = ioctl(sock_fd, SIOCGSKNS); + if (netns_fd < 0) { + free(handle); + close(sock_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "SIOCGSKNS not supported"); + ASSERT_GE(netns_fd, 0); + } + + ASSERT_EQ(fstat(netns_fd, &st), 0); + netns_ino = st.st_ino; + + /* Get namespace ID */ + ret = ioctl(netns_fd, NS_GET_ID, &netns_id); + if (ret < 0) { + free(handle); + close(sock_fd); + close(netns_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "NS_GET_ID not supported"); + ASSERT_EQ(ret, 0); + } + + /* Get owner user namespace */ + userns_fd = ioctl(netns_fd, NS_GET_USERNS); + if (userns_fd < 0) { + free(handle); + close(sock_fd); + close(netns_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "NS_GET_USERNS not supported"); + ASSERT_GE(userns_fd, 0); + } + + /* Get owner namespace ID */ + ret = ioctl(userns_fd, NS_GET_ID, &userns_id); + if (ret < 0) { + close(userns_fd); + free(handle); + close(sock_fd); + close(netns_fd); + ASSERT_EQ(ret, 0); + } + close(userns_fd); + + TH_LOG("Testing netns %lu (id=%llu) owned by userns id=%llu", netns_ino, netns_id, userns_id); + + /* Verify namespace appears in listns() */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + free(handle); + close(sock_fd); + close(netns_fd); + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + TH_LOG("listns failed: %s", strerror(errno)); + ASSERT_GE(ret, 0); + } + + found_netns = false; + found_userns = false; + for (i = 0; i < ret; i++) { + if (ns_ids[i] == netns_id) + found_netns = true; + if (ns_ids[i] == userns_id) + found_userns = true; + } + ASSERT_TRUE(found_netns); + ASSERT_TRUE(found_userns); + TH_LOG("Found netns %llu in listns() output", netns_id); + + /* Construct file handle from namespace ID */ + nsfs_fh = (struct nsfs_file_handle *)handle->f_handle; + nsfs_fh->ns_id = netns_id; + nsfs_fh->ns_type = 0; + nsfs_fh->ns_inum = 0; + + reopened_fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + if (reopened_fd < 0) { + free(handle); + close(sock_fd); + if (errno == EOPNOTSUPP || errno == ENOSYS || errno == EBADF) + SKIP(return, "open_by_handle_at with FD_NSFS_ROOT not supported"); + TH_LOG("open_by_handle_at failed: %s", strerror(errno)); + ASSERT_GE(reopened_fd, 0); + } + + struct stat reopened_st; + ASSERT_EQ(fstat(reopened_fd, &reopened_st), 0); + ASSERT_EQ(reopened_st.st_ino, netns_ino); + + TH_LOG("Successfully reopened netns %lu via file handle (socket-kept)", netns_ino); + + close(reopened_fd); + close(netns_fd); + + /* Try to reopen via file handle - should fail since namespace is now inactive */ + reopened_fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + ASSERT_LT(reopened_fd, 0); + TH_LOG("Correctly failed to reopen inactive netns: %s", strerror(errno)); + + /* Get network namespace from socket */ + netns_fd = ioctl(sock_fd, SIOCGSKNS); + if (netns_fd < 0) { + free(handle); + close(sock_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "SIOCGSKNS not supported"); + ASSERT_GE(netns_fd, 0); + } + + /* Verify namespace appears in listns() */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + free(handle); + close(sock_fd); + close(netns_fd); + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + TH_LOG("listns failed: %s", strerror(errno)); + ASSERT_GE(ret, 0); + } + + found_netns = false; + found_userns = false; + for (i = 0; i < ret; i++) { + if (ns_ids[i] == netns_id) + found_netns = true; + if (ns_ids[i] == userns_id) + found_userns = true; + } + ASSERT_TRUE(found_netns); + ASSERT_TRUE(found_userns); + TH_LOG("Found netns %llu in listns() output", netns_id); + + close(netns_fd); + + /* Verify namespace appears in listns() */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + free(handle); + close(sock_fd); + close(netns_fd); + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + TH_LOG("listns failed: %s", strerror(errno)); + ASSERT_GE(ret, 0); + } + + found_netns = false; + found_userns = false; + for (i = 0; i < ret; i++) { + if (ns_ids[i] == netns_id) + found_netns = true; + if (ns_ids[i] == userns_id) + found_userns = true; + } + ASSERT_FALSE(found_netns); + ASSERT_FALSE(found_userns); + TH_LOG("Netns %llu correctly disappeared from listns() after socket closed", netns_id); + + close(sock_fd); + free(handle); +} + TEST_HARNESS_MAIN From c89d100f6a10efc1ee90d44125a5500bd5e6ab77 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:19 +0100 Subject: [PATCH 69/75] selftests/namespaces: twelth inactive namespace resurrection test Test multi-level namespace resurrection across three user namespace levels. This test creates a complex namespace hierarchy with three levels of user namespaces and a network namespace at the deepest level. It verifies that the resurrection semantics work correctly when SIOCGSKNS is called on a socket from an inactive namespace tree, and that listns() and open_by_handle_at() correctly respect visibility rules. Hierarchy after child processes exit (all with 0 active refcount): net_L3A (0) <- Level 3 network namespace | + userns_L3 (0) <- Level 3 user namespace | + userns_L2 (0) <- Level 2 user namespace | + userns_L1 (0) <- Level 1 user namespace | x init_user_ns The test verifies: 1. SIOCGSKNS on a socket from inactive net_L3A resurrects the entire chain 2. After resurrection, all namespaces are visible in listns() 3. Resurrected namespaces can be reopened via file handles 4. Closing the netns FD cascades down: the entire ownership chain (userns_L3 -> userns_L2 -> userns_L1) becomes inactive again 5. Inactive namespaces disappear from listns() and cannot be reopened 6. Calling SIOCGSKNS again on the same socket resurrects the tree again 7. After second resurrection, namespaces are visible and can be reopened Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-66-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/siocgskns_test.c | 564 ++++++++++++++++++ 1 file changed, 564 insertions(+) diff --git a/tools/testing/selftests/namespaces/siocgskns_test.c b/tools/testing/selftests/namespaces/siocgskns_test.c index 706049768d52..ba689a22d82f 100644 --- a/tools/testing/selftests/namespaces/siocgskns_test.c +++ b/tools/testing/selftests/namespaces/siocgskns_test.c @@ -1257,4 +1257,568 @@ TEST(siocgskns_listns_and_file_handle) free(handle); } +/* + * Test multi-level namespace resurrection across three user namespace levels. + * + * This test creates a complex namespace hierarchy with three levels of user + * namespaces and a network namespace at the deepest level. It verifies that + * the resurrection semantics work correctly when SIOCGSKNS is called on a + * socket from an inactive namespace tree, and that listns() and + * open_by_handle_at() correctly respect visibility rules. + * + * Hierarchy after child processes exit (all with 0 active refcount): + * + * net_L3A (0) <- Level 3 network namespace + * | + * + + * userns_L3 (0) <- Level 3 user namespace + * | + * + + * userns_L2 (0) <- Level 2 user namespace + * | + * + + * userns_L1 (0) <- Level 1 user namespace + * | + * x + * init_user_ns + * + * The test verifies: + * 1. SIOCGSKNS on a socket from inactive net_L3A resurrects the entire chain + * 2. After resurrection, all namespaces are visible in listns() + * 3. Resurrected namespaces can be reopened via file handles + * 4. Closing the netns FD cascades down: the entire ownership chain + * (userns_L3 -> userns_L2 -> userns_L1) becomes inactive again + * 5. Inactive namespaces disappear from listns() and cannot be reopened + * 6. Calling SIOCGSKNS again on the same socket resurrects the tree again + * 7. After second resurrection, namespaces are visible and can be reopened + */ +TEST(siocgskns_multilevel_resurrection) +{ + int ipc_sockets[2]; + pid_t pid_l1, pid_l2, pid_l3; + int status; + + /* Namespace file descriptors to be received from child */ + int sock_L3A_fd = -1; + int netns_L3A_fd = -1; + __u64 netns_L3A_id; + __u64 userns_L1_id, userns_L2_id, userns_L3_id; + + /* For listns() and file handle testing */ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWNET | CLONE_NEWUSER, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids[256]; + int ret, i; + struct file_handle *handle; + struct nsfs_file_handle *nsfs_fh; + int reopened_fd; + + /* Allocate file handle for testing */ + handle = malloc(sizeof(struct file_handle) + sizeof(struct nsfs_file_handle)); + ASSERT_NE(handle, NULL); + handle->handle_bytes = sizeof(struct nsfs_file_handle); + handle->handle_type = FILEID_NSFS; + + EXPECT_EQ(socketpair(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_sockets), 0); + + /* + * Fork level 1 child that creates userns_L1 + */ + pid_l1 = fork(); + ASSERT_GE(pid_l1, 0); + + if (pid_l1 == 0) { + /* Level 1 child */ + int ipc_L2[2]; + close(ipc_sockets[0]); + + /* Create userns_L1 */ + if (setup_userns() < 0) { + close(ipc_sockets[1]); + exit(1); + } + + /* Create socketpair for communicating with L2 child */ + if (socketpair(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_L2) < 0) { + close(ipc_sockets[1]); + exit(1); + } + + /* + * Fork level 2 child that creates userns_L2 + */ + pid_l2 = fork(); + if (pid_l2 < 0) { + close(ipc_sockets[1]); + close(ipc_L2[0]); + close(ipc_L2[1]); + exit(1); + } + + if (pid_l2 == 0) { + /* Level 2 child */ + int ipc_L3[2]; + close(ipc_L2[0]); + + /* Create userns_L2 (nested inside userns_L1) */ + if (setup_userns() < 0) { + close(ipc_L2[1]); + exit(1); + } + + /* Create socketpair for communicating with L3 child */ + if (socketpair(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, ipc_L3) < 0) { + close(ipc_L2[1]); + exit(1); + } + + /* + * Fork level 3 child that creates userns_L3 and network namespaces + */ + pid_l3 = fork(); + if (pid_l3 < 0) { + close(ipc_L2[1]); + close(ipc_L3[0]); + close(ipc_L3[1]); + exit(1); + } + + if (pid_l3 == 0) { + /* Level 3 child - the deepest level */ + int sock_fd; + close(ipc_L3[0]); + + /* Create userns_L3 (nested inside userns_L2) */ + if (setup_userns() < 0) { + close(ipc_L3[1]); + exit(1); + } + + /* Create network namespace at level 3 */ + if (unshare(CLONE_NEWNET) < 0) { + close(ipc_L3[1]); + exit(1); + } + + /* Create socket in net_L3A */ + sock_fd = socket(AF_INET, SOCK_DGRAM, 0); + if (sock_fd < 0) { + close(ipc_L3[1]); + exit(1); + } + + /* Send socket FD to L2 parent */ + struct msghdr msg = {0}; + struct iovec iov = {0}; + char buf[1] = {'X'}; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); + memcpy(CMSG_DATA(cmsg), &sock_fd, sizeof(int)); + + if (sendmsg(ipc_L3[1], &msg, 0) < 0) { + close(sock_fd); + close(ipc_L3[1]); + exit(1); + } + + close(sock_fd); + close(ipc_L3[1]); + exit(0); + } + + /* Level 2 child - receive from L3 and forward to L1 */ + close(ipc_L3[1]); + + struct msghdr msg = {0}; + struct iovec iov = {0}; + char buf[1]; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + int received_fd; + + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + ssize_t n = recvmsg(ipc_L3[0], &msg, 0); + close(ipc_L3[0]); + + if (n != 1) { + close(ipc_L2[1]); + waitpid(pid_l3, NULL, 0); + exit(1); + } + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + if (!cmsg) { + close(ipc_L2[1]); + waitpid(pid_l3, NULL, 0); + exit(1); + } + memcpy(&received_fd, CMSG_DATA(cmsg), sizeof(int)); + + /* Wait for L3 child */ + waitpid(pid_l3, NULL, 0); + + /* Forward the socket FD to L1 parent */ + memset(&msg, 0, sizeof(msg)); + buf[0] = 'Y'; + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); + memcpy(CMSG_DATA(cmsg), &received_fd, sizeof(int)); + + if (sendmsg(ipc_L2[1], &msg, 0) < 0) { + close(received_fd); + close(ipc_L2[1]); + exit(1); + } + + close(received_fd); + close(ipc_L2[1]); + exit(0); + } + + /* Level 1 child - receive from L2 and forward to parent */ + close(ipc_L2[1]); + + struct msghdr msg = {0}; + struct iovec iov = {0}; + char buf[1]; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + int received_fd; + + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + ssize_t n = recvmsg(ipc_L2[0], &msg, 0); + close(ipc_L2[0]); + + if (n != 1) { + close(ipc_sockets[1]); + waitpid(pid_l2, NULL, 0); + exit(1); + } + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + if (!cmsg) { + close(ipc_sockets[1]); + waitpid(pid_l2, NULL, 0); + exit(1); + } + memcpy(&received_fd, CMSG_DATA(cmsg), sizeof(int)); + + /* Wait for L2 child */ + waitpid(pid_l2, NULL, 0); + + /* Forward the socket FD to parent */ + memset(&msg, 0, sizeof(msg)); + buf[0] = 'Z'; + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); + memcpy(CMSG_DATA(cmsg), &received_fd, sizeof(int)); + + if (sendmsg(ipc_sockets[1], &msg, 0) < 0) { + close(received_fd); + close(ipc_sockets[1]); + exit(1); + } + + close(received_fd); + close(ipc_sockets[1]); + exit(0); + } + + /* Parent - receive the socket from the deepest level */ + close(ipc_sockets[1]); + + struct msghdr msg = {0}; + struct iovec iov = {0}; + char buf[1]; + char cmsg_buf[CMSG_SPACE(sizeof(int))]; + + iov.iov_base = buf; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof(cmsg_buf); + + ssize_t n = recvmsg(ipc_sockets[0], &msg, 0); + close(ipc_sockets[0]); + + if (n != 1) { + free(handle); + waitpid(pid_l1, NULL, 0); + SKIP(return, "Failed to receive socket from child"); + } + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + if (!cmsg) { + free(handle); + waitpid(pid_l1, NULL, 0); + SKIP(return, "Failed to receive socket from child"); + } + memcpy(&sock_L3A_fd, CMSG_DATA(cmsg), sizeof(int)); + + /* Wait for L1 child */ + waitpid(pid_l1, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* + * At this point, all child processes have exited. The socket itself + * doesn't keep the namespace active - we need to call SIOCGSKNS which + * will resurrect the entire namespace tree by taking active references. + */ + + /* Get network namespace from socket - this resurrects the tree */ + netns_L3A_fd = ioctl(sock_L3A_fd, SIOCGSKNS); + if (netns_L3A_fd < 0) { + free(handle); + close(sock_L3A_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "SIOCGSKNS not supported"); + ASSERT_GE(netns_L3A_fd, 0); + } + + /* Get namespace ID for net_L3A */ + ret = ioctl(netns_L3A_fd, NS_GET_ID, &netns_L3A_id); + if (ret < 0) { + free(handle); + close(sock_L3A_fd); + close(netns_L3A_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "NS_GET_ID not supported"); + ASSERT_EQ(ret, 0); + } + + /* Get owner user namespace chain: userns_L3 -> userns_L2 -> userns_L1 */ + int userns_L3_fd = ioctl(netns_L3A_fd, NS_GET_USERNS); + if (userns_L3_fd < 0) { + free(handle); + close(sock_L3A_fd); + close(netns_L3A_fd); + if (errno == ENOTTY || errno == EINVAL) + SKIP(return, "NS_GET_USERNS not supported"); + ASSERT_GE(userns_L3_fd, 0); + } + + ret = ioctl(userns_L3_fd, NS_GET_ID, &userns_L3_id); + ASSERT_EQ(ret, 0); + + int userns_L2_fd = ioctl(userns_L3_fd, NS_GET_USERNS); + ASSERT_GE(userns_L2_fd, 0); + ret = ioctl(userns_L2_fd, NS_GET_ID, &userns_L2_id); + ASSERT_EQ(ret, 0); + + int userns_L1_fd = ioctl(userns_L2_fd, NS_GET_USERNS); + ASSERT_GE(userns_L1_fd, 0); + ret = ioctl(userns_L1_fd, NS_GET_ID, &userns_L1_id); + ASSERT_EQ(ret, 0); + + close(userns_L1_fd); + close(userns_L2_fd); + close(userns_L3_fd); + + TH_LOG("Multi-level hierarchy: net_L3A (id=%llu) -> userns_L3 (id=%llu) -> userns_L2 (id=%llu) -> userns_L1 (id=%llu)", + netns_L3A_id, userns_L3_id, userns_L2_id, userns_L1_id); + + /* + * Test 1: Verify net_L3A is visible in listns() after resurrection. + * The entire ownership chain should be resurrected and visible. + */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + free(handle); + close(sock_L3A_fd); + close(netns_L3A_fd); + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + ASSERT_GE(ret, 0); + } + + bool found_netns_L3A = false; + bool found_userns_L1 = false; + bool found_userns_L2 = false; + bool found_userns_L3 = false; + + for (i = 0; i < ret; i++) { + if (ns_ids[i] == netns_L3A_id) + found_netns_L3A = true; + if (ns_ids[i] == userns_L1_id) + found_userns_L1 = true; + if (ns_ids[i] == userns_L2_id) + found_userns_L2 = true; + if (ns_ids[i] == userns_L3_id) + found_userns_L3 = true; + } + + ASSERT_TRUE(found_netns_L3A); + ASSERT_TRUE(found_userns_L1); + ASSERT_TRUE(found_userns_L2); + ASSERT_TRUE(found_userns_L3); + TH_LOG("Resurrection verified: all namespaces in hierarchy visible in listns()"); + + /* + * Test 2: Verify net_L3A can be reopened via file handle. + */ + nsfs_fh = (struct nsfs_file_handle *)handle->f_handle; + nsfs_fh->ns_id = netns_L3A_id; + nsfs_fh->ns_type = 0; + nsfs_fh->ns_inum = 0; + + reopened_fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + if (reopened_fd < 0) { + free(handle); + close(sock_L3A_fd); + close(netns_L3A_fd); + if (errno == EOPNOTSUPP || errno == ENOSYS || errno == EBADF) + SKIP(return, "open_by_handle_at with FD_NSFS_ROOT not supported"); + TH_LOG("open_by_handle_at failed: %s", strerror(errno)); + ASSERT_GE(reopened_fd, 0); + } + + close(reopened_fd); + TH_LOG("File handle test passed: net_L3A can be reopened"); + + /* + * Test 3: Verify that when we close the netns FD (dropping the last + * active reference), the entire tree becomes inactive and disappears + * from listns(). The cascade goes: net_L3A drops -> userns_L3 drops -> + * userns_L2 drops -> userns_L1 drops. + */ + close(netns_L3A_fd); + + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + ASSERT_GE(ret, 0); + + found_netns_L3A = false; + found_userns_L1 = false; + found_userns_L2 = false; + found_userns_L3 = false; + + for (i = 0; i < ret; i++) { + if (ns_ids[i] == netns_L3A_id) + found_netns_L3A = true; + if (ns_ids[i] == userns_L1_id) + found_userns_L1 = true; + if (ns_ids[i] == userns_L2_id) + found_userns_L2 = true; + if (ns_ids[i] == userns_L3_id) + found_userns_L3 = true; + } + + ASSERT_FALSE(found_netns_L3A); + ASSERT_FALSE(found_userns_L1); + ASSERT_FALSE(found_userns_L2); + ASSERT_FALSE(found_userns_L3); + TH_LOG("Cascade test passed: all namespaces disappeared after netns FD closed"); + + /* + * Test 4: Verify file handle no longer works for inactive namespace. + */ + reopened_fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + if (reopened_fd >= 0) { + close(reopened_fd); + free(handle); + ASSERT_TRUE(false); /* Should have failed */ + } + TH_LOG("Inactive namespace correctly cannot be reopened via file handle"); + + /* + * Test 5: Verify that calling SIOCGSKNS again resurrects the tree again. + * The socket is still valid, so we can call SIOCGSKNS on it to resurrect + * the namespace tree once more. + */ + netns_L3A_fd = ioctl(sock_L3A_fd, SIOCGSKNS); + ASSERT_GE(netns_L3A_fd, 0); + + TH_LOG("Called SIOCGSKNS again to resurrect the namespace tree"); + + /* Verify the namespace tree is resurrected and visible in listns() */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + ASSERT_GE(ret, 0); + + found_netns_L3A = false; + found_userns_L1 = false; + found_userns_L2 = false; + found_userns_L3 = false; + + for (i = 0; i < ret; i++) { + if (ns_ids[i] == netns_L3A_id) + found_netns_L3A = true; + if (ns_ids[i] == userns_L1_id) + found_userns_L1 = true; + if (ns_ids[i] == userns_L2_id) + found_userns_L2 = true; + if (ns_ids[i] == userns_L3_id) + found_userns_L3 = true; + } + + ASSERT_TRUE(found_netns_L3A); + ASSERT_TRUE(found_userns_L1); + ASSERT_TRUE(found_userns_L2); + ASSERT_TRUE(found_userns_L3); + TH_LOG("Second resurrection verified: all namespaces in hierarchy visible in listns() again"); + + /* Verify we can reopen via file handle again */ + reopened_fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + if (reopened_fd < 0) { + free(handle); + close(sock_L3A_fd); + close(netns_L3A_fd); + TH_LOG("open_by_handle_at failed after second resurrection: %s", strerror(errno)); + ASSERT_GE(reopened_fd, 0); + } + + close(reopened_fd); + TH_LOG("File handle test passed: net_L3A can be reopened after second resurrection"); + + /* Final cleanup */ + close(sock_L3A_fd); + close(netns_L3A_fd); + free(handle); +} + TEST_HARNESS_MAIN From 29f083c499821663c2a0863fd2b9c06883c2b19d Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:20 +0100 Subject: [PATCH 70/75] selftests/namespace: first threaded active reference count test Test that namespace becomes inactive after thread exits. This verifies active reference counting works with threads, not just processes. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-67-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 138 ++++++++++++++++++ 1 file changed, 138 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index b7fa973a2572..0c6c4869bb16 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -12,9 +12,12 @@ #include #include #include +#include #include +#include #include "../kselftest_harness.h" #include "../filesystems/utils.h" +#include "wrappers.h" #ifndef FD_NSFS_ROOT #define FD_NSFS_ROOT -10003 /* Root of the nsfs filesystem */ @@ -2113,4 +2116,139 @@ TEST(ns_mixed_types_same_owner) ASSERT_LT(u_fd, 0); } +/* Thread test helpers and structures */ +struct thread_ns_info { + __u64 ns_id; + int pipefd; + int syncfd_read; + int syncfd_write; + int exit_code; +}; + +static void *thread_create_namespace(void *arg) +{ + struct thread_ns_info *info = (struct thread_ns_info *)arg; + int ret; + + /* Create new network namespace */ + ret = unshare(CLONE_NEWNET); + if (ret < 0) { + info->exit_code = 1; + return NULL; + } + + /* Get namespace ID */ + int fd = open("/proc/thread-self/ns/net", O_RDONLY); + if (fd < 0) { + info->exit_code = 2; + return NULL; + } + + ret = ioctl(fd, NS_GET_ID, &info->ns_id); + close(fd); + if (ret < 0) { + info->exit_code = 3; + return NULL; + } + + /* Send namespace ID to main thread */ + if (write(info->pipefd, &info->ns_id, sizeof(info->ns_id)) != sizeof(info->ns_id)) { + info->exit_code = 4; + return NULL; + } + + /* Wait for signal to exit */ + char sync_byte; + if (read(info->syncfd_read, &sync_byte, 1) != 1) { + info->exit_code = 5; + return NULL; + } + + info->exit_code = 0; + return NULL; +} + +/* + * Test that namespace becomes inactive after thread exits. + * This verifies active reference counting works with threads, not just processes. + */ +TEST(thread_ns_inactive_after_exit) +{ + pthread_t thread; + struct thread_ns_info info; + struct file_handle *handle; + int pipefd[2]; + int syncpipe[2]; + int ret; + char sync_byte; + char buf[sizeof(*handle) + MAX_HANDLE_SZ]; + + ASSERT_EQ(pipe(pipefd), 0); + ASSERT_EQ(pipe(syncpipe), 0); + + info.pipefd = pipefd[1]; + info.syncfd_read = syncpipe[0]; + info.syncfd_write = -1; + info.exit_code = -1; + + /* Create thread that will create a namespace */ + ret = pthread_create(&thread, NULL, thread_create_namespace, &info); + ASSERT_EQ(ret, 0); + + /* Read namespace ID from thread */ + __u64 ns_id; + ret = read(pipefd[0], &ns_id, sizeof(ns_id)); + if (ret != sizeof(ns_id)) { + sync_byte = 'X'; + write(syncpipe[1], &sync_byte, 1); + pthread_join(thread, NULL); + close(pipefd[0]); + close(pipefd[1]); + close(syncpipe[0]); + close(syncpipe[1]); + SKIP(return, "Failed to read namespace ID from thread"); + } + + TH_LOG("Thread created namespace with ID %llu", (unsigned long long)ns_id); + + /* Construct file handle */ + handle = (struct file_handle *)buf; + handle->handle_bytes = sizeof(struct nsfs_file_handle); + handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *fh = (struct nsfs_file_handle *)handle->f_handle; + fh->ns_id = ns_id; + fh->ns_type = 0; + fh->ns_inum = 0; + + /* Namespace should be active while thread is alive */ + TH_LOG("Attempting to open namespace while thread is alive (should succeed)"); + int nsfd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + ASSERT_GE(nsfd, 0); + close(nsfd); + + /* Signal thread to exit */ + TH_LOG("Signaling thread to exit"); + sync_byte = 'X'; + ASSERT_EQ(write(syncpipe[1], &sync_byte, 1), 1); + close(syncpipe[1]); + + /* Wait for thread to exit */ + ASSERT_EQ(pthread_join(thread, NULL), 0); + close(pipefd[0]); + close(pipefd[1]); + close(syncpipe[0]); + + if (info.exit_code != 0) + SKIP(return, "Thread failed to create namespace"); + + TH_LOG("Thread exited, namespace should be inactive"); + + /* Namespace should now be inactive */ + nsfd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + ASSERT_LT(nsfd, 0); + /* Should fail with ENOENT (inactive) or ESTALE (gone) */ + TH_LOG("Namespace inactive as expected: %s (errno=%d)", strerror(errno), errno); + ASSERT_TRUE(errno == ENOENT || errno == ESTALE); +} + TEST_HARNESS_MAIN From ee861032381b6bf9188a84891ae7c31396e5dd2a Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:21 +0100 Subject: [PATCH 71/75] selftests/namespace: second threaded active reference count test Test that a namespace remains active while a thread holds an fd to it. Even after the thread exits, the namespace should remain active as long as another thread holds a file descriptor to it. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-68-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 99 +++++++++++++++++++ 1 file changed, 99 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index 0c6c4869bb16..24dc8ef106b9 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -2251,4 +2251,103 @@ TEST(thread_ns_inactive_after_exit) ASSERT_TRUE(errno == ENOENT || errno == ESTALE); } +/* + * Test that a namespace remains active while a thread holds an fd to it. + * Even after the thread exits, the namespace should remain active as long as + * another thread holds a file descriptor to it. + */ +TEST(thread_ns_fd_keeps_active) +{ + pthread_t thread; + struct thread_ns_info info; + struct file_handle *handle; + int pipefd[2]; + int syncpipe[2]; + int ret; + char sync_byte; + char buf[sizeof(*handle) + MAX_HANDLE_SZ]; + + ASSERT_EQ(pipe(pipefd), 0); + ASSERT_EQ(pipe(syncpipe), 0); + + info.pipefd = pipefd[1]; + info.syncfd_read = syncpipe[0]; + info.syncfd_write = -1; + info.exit_code = -1; + + /* Create thread that will create a namespace */ + ret = pthread_create(&thread, NULL, thread_create_namespace, &info); + ASSERT_EQ(ret, 0); + + /* Read namespace ID from thread */ + __u64 ns_id; + ret = read(pipefd[0], &ns_id, sizeof(ns_id)); + if (ret != sizeof(ns_id)) { + sync_byte = 'X'; + write(syncpipe[1], &sync_byte, 1); + pthread_join(thread, NULL); + close(pipefd[0]); + close(pipefd[1]); + close(syncpipe[0]); + close(syncpipe[1]); + SKIP(return, "Failed to read namespace ID from thread"); + } + + TH_LOG("Thread created namespace with ID %llu", (unsigned long long)ns_id); + + /* Construct file handle */ + handle = (struct file_handle *)buf; + handle->handle_bytes = sizeof(struct nsfs_file_handle); + handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *fh = (struct nsfs_file_handle *)handle->f_handle; + fh->ns_id = ns_id; + fh->ns_type = 0; + fh->ns_inum = 0; + + /* Open namespace while thread is alive */ + TH_LOG("Opening namespace while thread is alive"); + int nsfd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + ASSERT_GE(nsfd, 0); + + /* Signal thread to exit */ + TH_LOG("Signaling thread to exit"); + sync_byte = 'X'; + write(syncpipe[1], &sync_byte, 1); + close(syncpipe[1]); + + /* Wait for thread to exit */ + pthread_join(thread, NULL); + close(pipefd[0]); + close(pipefd[1]); + close(syncpipe[0]); + + if (info.exit_code != 0) { + close(nsfd); + SKIP(return, "Thread failed to create namespace"); + } + + TH_LOG("Thread exited, but main thread holds fd - namespace should remain active"); + + /* Namespace should still be active because we hold an fd */ + int nsfd2 = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + ASSERT_GE(nsfd2, 0); + + /* Verify it's the same namespace */ + struct stat st1, st2; + ASSERT_EQ(fstat(nsfd, &st1), 0); + ASSERT_EQ(fstat(nsfd2, &st2), 0); + ASSERT_EQ(st1.st_ino, st2.st_ino); + close(nsfd2); + + TH_LOG("Closing fd - namespace should become inactive"); + close(nsfd); + + /* Now namespace should be inactive */ + nsfd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + ASSERT_LT(nsfd, 0); + /* Should fail with ENOENT (inactive) or ESTALE (gone) */ + TH_LOG("Namespace inactive as expected: %s (errno=%d)", strerror(errno), errno); + ASSERT_TRUE(errno == ENOENT || errno == ESTALE); +} + TEST_HARNESS_MAIN From 80fedf8168ee82c30b343977901b6176cf1e0e76 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:22 +0100 Subject: [PATCH 72/75] selftests/namespace: third threaded active reference count test Test that namespaces become inactive after subprocess with multiple threads exits. Create a subprocess that unshares user and network namespaces, then creates two threads that share those namespaces. Verify that after all threads and subprocess exit, the namespaces are no longer listed by listns() and cannot be opened by open_by_handle_at(). Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-69-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 319 ++++++++++++++++++ 1 file changed, 319 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tools/testing/selftests/namespaces/ns_active_ref_test.c index 24dc8ef106b9..093268f0efaa 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include #include @@ -2350,4 +2351,322 @@ TEST(thread_ns_fd_keeps_active) ASSERT_TRUE(errno == ENOENT || errno == ESTALE); } +/* Structure for thread data in subprocess */ +struct thread_sleep_data { + int syncfd_read; +}; + +static void *thread_sleep_and_wait(void *arg) +{ + struct thread_sleep_data *data = (struct thread_sleep_data *)arg; + char sync_byte; + + /* Wait for signal to exit - read will unblock when pipe is closed */ + (void)read(data->syncfd_read, &sync_byte, 1); + return NULL; +} + +/* + * Test that namespaces become inactive after subprocess with multiple threads exits. + * Create a subprocess that unshares user and network namespaces, then creates two + * threads that share those namespaces. Verify that after all threads and subprocess + * exit, the namespaces are no longer listed by listns() and cannot be opened by + * open_by_handle_at(). + */ +TEST(thread_subprocess_ns_inactive_after_all_exit) +{ + int pipefd[2]; + int sv[2]; + pid_t pid; + int status; + __u64 user_id, net_id; + struct file_handle *user_handle, *net_handle; + char user_buf[sizeof(*user_handle) + MAX_HANDLE_SZ]; + char net_buf[sizeof(*net_handle) + MAX_HANDLE_SZ]; + char sync_byte; + int ret; + + ASSERT_EQ(pipe(pipefd), 0); + ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sv), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child process */ + close(pipefd[0]); + close(sv[0]); + + /* Create user namespace with mappings */ + if (setup_userns() < 0) { + fprintf(stderr, "Child: setup_userns() failed: %s\n", strerror(errno)); + close(pipefd[1]); + close(sv[1]); + exit(1); + } + fprintf(stderr, "Child: setup_userns() succeeded\n"); + + /* Get user namespace ID */ + int user_fd = open("/proc/self/ns/user", O_RDONLY); + if (user_fd < 0) { + fprintf(stderr, "Child: open(/proc/self/ns/user) failed: %s\n", strerror(errno)); + close(pipefd[1]); + close(sv[1]); + exit(1); + } + + if (ioctl(user_fd, NS_GET_ID, &user_id) < 0) { + fprintf(stderr, "Child: ioctl(NS_GET_ID) for user ns failed: %s\n", strerror(errno)); + close(user_fd); + close(pipefd[1]); + close(sv[1]); + exit(1); + } + close(user_fd); + fprintf(stderr, "Child: user ns ID = %llu\n", (unsigned long long)user_id); + + /* Unshare network namespace */ + if (unshare(CLONE_NEWNET) < 0) { + fprintf(stderr, "Child: unshare(CLONE_NEWNET) failed: %s\n", strerror(errno)); + close(pipefd[1]); + close(sv[1]); + exit(1); + } + fprintf(stderr, "Child: unshare(CLONE_NEWNET) succeeded\n"); + + /* Get network namespace ID */ + int net_fd = open("/proc/self/ns/net", O_RDONLY); + if (net_fd < 0) { + fprintf(stderr, "Child: open(/proc/self/ns/net) failed: %s\n", strerror(errno)); + close(pipefd[1]); + close(sv[1]); + exit(1); + } + + if (ioctl(net_fd, NS_GET_ID, &net_id) < 0) { + fprintf(stderr, "Child: ioctl(NS_GET_ID) for net ns failed: %s\n", strerror(errno)); + close(net_fd); + close(pipefd[1]); + close(sv[1]); + exit(1); + } + close(net_fd); + fprintf(stderr, "Child: net ns ID = %llu\n", (unsigned long long)net_id); + + /* Send namespace IDs to parent */ + if (write(pipefd[1], &user_id, sizeof(user_id)) != sizeof(user_id)) { + fprintf(stderr, "Child: write(user_id) failed: %s\n", strerror(errno)); + exit(1); + } + if (write(pipefd[1], &net_id, sizeof(net_id)) != sizeof(net_id)) { + fprintf(stderr, "Child: write(net_id) failed: %s\n", strerror(errno)); + exit(1); + } + close(pipefd[1]); + fprintf(stderr, "Child: sent namespace IDs to parent\n"); + + /* Create two threads that share the namespaces */ + pthread_t thread1, thread2; + struct thread_sleep_data data; + data.syncfd_read = sv[1]; + + int ret_thread = pthread_create(&thread1, NULL, thread_sleep_and_wait, &data); + if (ret_thread != 0) { + fprintf(stderr, "Child: pthread_create(thread1) failed: %s\n", strerror(ret_thread)); + close(sv[1]); + exit(1); + } + fprintf(stderr, "Child: created thread1\n"); + + ret_thread = pthread_create(&thread2, NULL, thread_sleep_and_wait, &data); + if (ret_thread != 0) { + fprintf(stderr, "Child: pthread_create(thread2) failed: %s\n", strerror(ret_thread)); + close(sv[1]); + pthread_cancel(thread1); + exit(1); + } + fprintf(stderr, "Child: created thread2\n"); + + /* Wait for threads to complete - they will unblock when parent writes */ + fprintf(stderr, "Child: waiting for threads to exit\n"); + pthread_join(thread1, NULL); + fprintf(stderr, "Child: thread1 exited\n"); + pthread_join(thread2, NULL); + fprintf(stderr, "Child: thread2 exited\n"); + + close(sv[1]); + + /* Exit - namespaces should become inactive */ + fprintf(stderr, "Child: all threads joined, exiting with success\n"); + exit(0); + } + + /* Parent process */ + close(pipefd[1]); + close(sv[1]); + + TH_LOG("Parent: waiting to read namespace IDs from child"); + + /* Read namespace IDs from child */ + ret = read(pipefd[0], &user_id, sizeof(user_id)); + if (ret != sizeof(user_id)) { + TH_LOG("Parent: failed to read user_id, ret=%d, errno=%s", ret, strerror(errno)); + close(pipefd[0]); + sync_byte = 'X'; + (void)write(sv[0], &sync_byte, 1); + close(sv[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read user namespace ID from child"); + } + + ret = read(pipefd[0], &net_id, sizeof(net_id)); + close(pipefd[0]); + if (ret != sizeof(net_id)) { + TH_LOG("Parent: failed to read net_id, ret=%d, errno=%s", ret, strerror(errno)); + sync_byte = 'X'; + (void)write(sv[0], &sync_byte, 1); + close(sv[0]); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to read network namespace ID from child"); + } + + TH_LOG("Child created user ns %llu and net ns %llu with 2 threads", + (unsigned long long)user_id, (unsigned long long)net_id); + + /* Construct file handles */ + user_handle = (struct file_handle *)user_buf; + user_handle->handle_bytes = sizeof(struct nsfs_file_handle); + user_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *user_fh = (struct nsfs_file_handle *)user_handle->f_handle; + user_fh->ns_id = user_id; + user_fh->ns_type = 0; + user_fh->ns_inum = 0; + + net_handle = (struct file_handle *)net_buf; + net_handle->handle_bytes = sizeof(struct nsfs_file_handle); + net_handle->handle_type = FILEID_NSFS; + struct nsfs_file_handle *net_fh = (struct nsfs_file_handle *)net_handle->f_handle; + net_fh->ns_id = net_id; + net_fh->ns_type = 0; + net_fh->ns_inum = 0; + + /* Verify namespaces are active while subprocess and threads are alive */ + TH_LOG("Verifying namespaces are active while subprocess with threads is running"); + int user_fd = open_by_handle_at(FD_NSFS_ROOT, user_handle, O_RDONLY); + ASSERT_GE(user_fd, 0); + + int net_fd = open_by_handle_at(FD_NSFS_ROOT, net_handle, O_RDONLY); + ASSERT_GE(net_fd, 0); + + close(user_fd); + close(net_fd); + + /* Also verify they appear in listns() */ + TH_LOG("Verifying namespaces appear in listns() while active"); + struct ns_id_req req = { + .size = sizeof(struct ns_id_req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids[256]; + int nr_ids = sys_listns(&req, ns_ids, 256, 0); + if (nr_ids < 0) { + TH_LOG("listns() not available, skipping listns verification"); + } else { + /* Check if user_id is in the list */ + int found_user = 0; + for (int i = 0; i < nr_ids; i++) { + if (ns_ids[i] == user_id) { + found_user = 1; + break; + } + } + ASSERT_TRUE(found_user); + TH_LOG("User namespace found in listns() as expected"); + + /* Check network namespace */ + req.ns_type = CLONE_NEWNET; + nr_ids = sys_listns(&req, ns_ids, 256, 0); + if (nr_ids >= 0) { + int found_net = 0; + for (int i = 0; i < nr_ids; i++) { + if (ns_ids[i] == net_id) { + found_net = 1; + break; + } + } + ASSERT_TRUE(found_net); + TH_LOG("Network namespace found in listns() as expected"); + } + } + + /* Signal threads to exit */ + TH_LOG("Signaling threads to exit"); + sync_byte = 'X'; + /* Write two bytes - one for each thread */ + ASSERT_EQ(write(sv[0], &sync_byte, 1), 1); + ASSERT_EQ(write(sv[0], &sync_byte, 1), 1); + close(sv[0]); + + /* Wait for child process to exit */ + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + if (WEXITSTATUS(status) != 0) { + TH_LOG("Child process failed with exit code %d", WEXITSTATUS(status)); + SKIP(return, "Child process failed"); + } + + TH_LOG("Subprocess and all threads have exited successfully"); + + /* Verify namespaces are now inactive - open_by_handle_at should fail */ + TH_LOG("Verifying namespaces are inactive after subprocess and threads exit"); + user_fd = open_by_handle_at(FD_NSFS_ROOT, user_handle, O_RDONLY); + ASSERT_LT(user_fd, 0); + TH_LOG("User namespace inactive as expected: %s (errno=%d)", + strerror(errno), errno); + ASSERT_TRUE(errno == ENOENT || errno == ESTALE); + + net_fd = open_by_handle_at(FD_NSFS_ROOT, net_handle, O_RDONLY); + ASSERT_LT(net_fd, 0); + TH_LOG("Network namespace inactive as expected: %s (errno=%d)", + strerror(errno), errno); + ASSERT_TRUE(errno == ENOENT || errno == ESTALE); + + /* Verify namespaces do NOT appear in listns() */ + TH_LOG("Verifying namespaces do NOT appear in listns() when inactive"); + memset(&req, 0, sizeof(req)); + req.size = sizeof(struct ns_id_req); + req.ns_type = CLONE_NEWUSER; + nr_ids = sys_listns(&req, ns_ids, 256, 0); + if (nr_ids >= 0) { + int found_user = 0; + for (int i = 0; i < nr_ids; i++) { + if (ns_ids[i] == user_id) { + found_user = 1; + break; + } + } + ASSERT_FALSE(found_user); + TH_LOG("User namespace correctly not listed in listns()"); + + /* Check network namespace */ + req.ns_type = CLONE_NEWNET; + nr_ids = sys_listns(&req, ns_ids, 256, 0); + if (nr_ids >= 0) { + int found_net = 0; + for (int i = 0; i < nr_ids; i++) { + if (ns_ids[i] == net_id) { + found_net = 1; + break; + } + } + ASSERT_FALSE(found_net); + TH_LOG("Network namespace correctly not listed in listns()"); + } + } +} + TEST_HARNESS_MAIN From d18cf3f9a4ab67869d468672399de6eac0f8f571 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:23 +0100 Subject: [PATCH 73/75] selftests/namespace: commit_creds() active reference tests Test credential changes and their impact on namespace active references. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-70-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- tools/testing/selftests/namespaces/.gitignore | 1 + tools/testing/selftests/namespaces/Makefile | 4 +- .../selftests/namespaces/cred_change_test.c | 814 ++++++++++++++++++ 3 files changed, 818 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/namespaces/cred_change_test.c diff --git a/tools/testing/selftests/namespaces/.gitignore b/tools/testing/selftests/namespaces/.gitignore index aeb5f2711ff6..0091a7dfff20 100644 --- a/tools/testing/selftests/namespaces/.gitignore +++ b/tools/testing/selftests/namespaces/.gitignore @@ -5,3 +5,4 @@ ns_active_ref_test listns_test listns_permissions_test siocgskns_test +cred_change_test diff --git a/tools/testing/selftests/namespaces/Makefile b/tools/testing/selftests/namespaces/Makefile index d456505189cd..5d73f8dde6a0 100644 --- a/tools/testing/selftests/namespaces/Makefile +++ b/tools/testing/selftests/namespaces/Makefile @@ -8,7 +8,8 @@ TEST_GEN_PROGS := nsid_test \ ns_active_ref_test \ listns_test \ listns_permissions_test \ - siocgskns_test + siocgskns_test \ + cred_change_test include ../lib.mk @@ -16,4 +17,5 @@ $(OUTPUT)/ns_active_ref_test: ../filesystems/utils.c $(OUTPUT)/listns_test: ../filesystems/utils.c $(OUTPUT)/listns_permissions_test: ../filesystems/utils.c $(OUTPUT)/siocgskns_test: ../filesystems/utils.c +$(OUTPUT)/cred_change_test: ../filesystems/utils.c diff --git a/tools/testing/selftests/namespaces/cred_change_test.c b/tools/testing/selftests/namespaces/cred_change_test.c new file mode 100644 index 000000000000..7b4f5ad3f725 --- /dev/null +++ b/tools/testing/selftests/namespaces/cred_change_test.c @@ -0,0 +1,814 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "../kselftest_harness.h" +#include "../filesystems/utils.h" +#include "wrappers.h" + +/* + * Test credential changes and their impact on namespace active references. + */ + +/* + * Test setuid() in a user namespace properly swaps active references. + * Create a user namespace with multiple UIDs mapped, then setuid() between them. + * Verify that the user namespace remains active throughout. + */ +TEST(setuid_preserves_active_refs) +{ + pid_t pid; + int status; + __u64 userns_id; + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids[256]; + ssize_t ret; + int i; + bool found = false; + int pipefd[2]; + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child process */ + int fd, userns_fd; + __u64 child_userns_id; + uid_t orig_uid = getuid(); + int setuid_count; + + close(pipefd[0]); + + /* Create new user namespace with multiple UIDs mapped (0-9) */ + userns_fd = get_userns_fd(0, orig_uid, 10); + if (userns_fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (setns(userns_fd, CLONE_NEWUSER) < 0) { + close(userns_fd); + close(pipefd[1]); + exit(1); + } + close(userns_fd); + + /* Get user namespace ID */ + fd = open("/proc/self/ns/user", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &child_userns_id) < 0) { + close(fd); + close(pipefd[1]); + exit(1); + } + close(fd); + + /* Send namespace ID to parent */ + write(pipefd[1], &child_userns_id, sizeof(child_userns_id)); + + /* + * Perform multiple setuid() calls. + * Each setuid() triggers commit_creds() which should properly + * swap active references via switch_cred_namespaces(). + */ + for (setuid_count = 0; setuid_count < 50; setuid_count++) { + uid_t target_uid = (setuid_count % 10); + if (setuid(target_uid) < 0) { + if (errno != EPERM) { + close(pipefd[1]); + exit(1); + } + } + } + + close(pipefd[1]); + exit(0); + } + + /* Parent process */ + close(pipefd[1]); + + if (read(pipefd[0], &userns_id, sizeof(userns_id)) != sizeof(userns_id)) { + close(pipefd[0]); + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to get namespace ID from child"); + } + close(pipefd[0]); + + TH_LOG("Child user namespace ID: %llu", (unsigned long long)userns_id); + + /* Verify namespace is active while child is running */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + ASSERT_GE(ret, 0); + } + + for (i = 0; i < ret; i++) { + if (ns_ids[i] == userns_id) { + found = true; + break; + } + } + ASSERT_TRUE(found); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* Verify namespace becomes inactive after child exits */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + ASSERT_GE(ret, 0); + + found = false; + for (i = 0; i < ret; i++) { + if (ns_ids[i] == userns_id) { + found = true; + break; + } + } + + ASSERT_FALSE(found); + TH_LOG("setuid() correctly preserved active references (no leak)"); +} + +/* + * Test setgid() in a user namespace properly handles active references. + */ +TEST(setgid_preserves_active_refs) +{ + pid_t pid; + int status; + __u64 userns_id; + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids[256]; + ssize_t ret; + int i; + bool found = false; + int pipefd[2]; + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child process */ + int fd, userns_fd; + __u64 child_userns_id; + uid_t orig_uid = getuid(); + int setgid_count; + + close(pipefd[0]); + + /* Create new user namespace with multiple GIDs mapped */ + userns_fd = get_userns_fd(0, orig_uid, 10); + if (userns_fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (setns(userns_fd, CLONE_NEWUSER) < 0) { + close(userns_fd); + close(pipefd[1]); + exit(1); + } + close(userns_fd); + + /* Get user namespace ID */ + fd = open("/proc/self/ns/user", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &child_userns_id) < 0) { + close(fd); + close(pipefd[1]); + exit(1); + } + close(fd); + + write(pipefd[1], &child_userns_id, sizeof(child_userns_id)); + + /* Perform multiple setgid() calls */ + for (setgid_count = 0; setgid_count < 50; setgid_count++) { + gid_t target_gid = (setgid_count % 10); + if (setgid(target_gid) < 0) { + if (errno != EPERM) { + close(pipefd[1]); + exit(1); + } + } + } + + close(pipefd[1]); + exit(0); + } + + /* Parent process */ + close(pipefd[1]); + + if (read(pipefd[0], &userns_id, sizeof(userns_id)) != sizeof(userns_id)) { + close(pipefd[0]); + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to get namespace ID from child"); + } + close(pipefd[0]); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* Verify namespace becomes inactive */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + ASSERT_GE(ret, 0); + } + + for (i = 0; i < ret; i++) { + if (ns_ids[i] == userns_id) { + found = true; + break; + } + } + + ASSERT_FALSE(found); + TH_LOG("setgid() correctly preserved active references (no leak)"); +} + +/* + * Test setresuid() which changes real, effective, and saved UIDs. + * This should properly swap active references via commit_creds(). + */ +TEST(setresuid_preserves_active_refs) +{ + pid_t pid; + int status; + __u64 userns_id; + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids[256]; + ssize_t ret; + int i; + bool found = false; + int pipefd[2]; + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child process */ + int fd, userns_fd; + __u64 child_userns_id; + uid_t orig_uid = getuid(); + int setres_count; + + close(pipefd[0]); + + /* Create new user namespace */ + userns_fd = get_userns_fd(0, orig_uid, 10); + if (userns_fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (setns(userns_fd, CLONE_NEWUSER) < 0) { + close(userns_fd); + close(pipefd[1]); + exit(1); + } + close(userns_fd); + + /* Get user namespace ID */ + fd = open("/proc/self/ns/user", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &child_userns_id) < 0) { + close(fd); + close(pipefd[1]); + exit(1); + } + close(fd); + + write(pipefd[1], &child_userns_id, sizeof(child_userns_id)); + + /* Perform multiple setresuid() calls */ + for (setres_count = 0; setres_count < 30; setres_count++) { + uid_t uid1 = (setres_count % 5); + uid_t uid2 = ((setres_count + 1) % 5); + uid_t uid3 = ((setres_count + 2) % 5); + + if (setresuid(uid1, uid2, uid3) < 0) { + if (errno != EPERM) { + close(pipefd[1]); + exit(1); + } + } + } + + close(pipefd[1]); + exit(0); + } + + /* Parent process */ + close(pipefd[1]); + + if (read(pipefd[0], &userns_id, sizeof(userns_id)) != sizeof(userns_id)) { + close(pipefd[0]); + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to get namespace ID from child"); + } + close(pipefd[0]); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* Verify namespace becomes inactive */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + ASSERT_GE(ret, 0); + } + + for (i = 0; i < ret; i++) { + if (ns_ids[i] == userns_id) { + found = true; + break; + } + } + + ASSERT_FALSE(found); + TH_LOG("setresuid() correctly preserved active references (no leak)"); +} + +/* + * Test credential changes across multiple user namespaces. + * Create nested user namespaces and verify active reference tracking. + */ +TEST(cred_change_nested_userns) +{ + pid_t pid; + int status; + __u64 parent_userns_id, child_userns_id; + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids[256]; + ssize_t ret; + int i; + bool found_parent = false, found_child = false; + int pipefd[2]; + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child process */ + int fd, userns_fd; + __u64 parent_id, child_id; + uid_t orig_uid = getuid(); + + close(pipefd[0]); + + /* Create first user namespace */ + userns_fd = get_userns_fd(0, orig_uid, 1); + if (userns_fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (setns(userns_fd, CLONE_NEWUSER) < 0) { + close(userns_fd); + close(pipefd[1]); + exit(1); + } + close(userns_fd); + + /* Get first namespace ID */ + fd = open("/proc/self/ns/user", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &parent_id) < 0) { + close(fd); + close(pipefd[1]); + exit(1); + } + close(fd); + + /* Create nested user namespace */ + userns_fd = get_userns_fd(0, 0, 1); + if (userns_fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (setns(userns_fd, CLONE_NEWUSER) < 0) { + close(userns_fd); + close(pipefd[1]); + exit(1); + } + close(userns_fd); + + /* Get nested namespace ID */ + fd = open("/proc/self/ns/user", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &child_id) < 0) { + close(fd); + close(pipefd[1]); + exit(1); + } + close(fd); + + /* Send both IDs to parent */ + write(pipefd[1], &parent_id, sizeof(parent_id)); + write(pipefd[1], &child_id, sizeof(child_id)); + + /* Perform some credential changes in nested namespace */ + setuid(0); + setgid(0); + + close(pipefd[1]); + exit(0); + } + + /* Parent process */ + close(pipefd[1]); + + /* Read both namespace IDs */ + if (read(pipefd[0], &parent_userns_id, sizeof(parent_userns_id)) != sizeof(parent_userns_id)) { + close(pipefd[0]); + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to get parent namespace ID"); + } + + if (read(pipefd[0], &child_userns_id, sizeof(child_userns_id)) != sizeof(child_userns_id)) { + close(pipefd[0]); + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to get child namespace ID"); + } + close(pipefd[0]); + + TH_LOG("Parent userns: %llu, Child userns: %llu", + (unsigned long long)parent_userns_id, + (unsigned long long)child_userns_id); + + /* Verify both namespaces are active */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + ASSERT_GE(ret, 0); + } + + for (i = 0; i < ret; i++) { + if (ns_ids[i] == parent_userns_id) + found_parent = true; + if (ns_ids[i] == child_userns_id) + found_child = true; + } + + ASSERT_TRUE(found_parent); + ASSERT_TRUE(found_child); + + /* Wait for child */ + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* Verify both namespaces become inactive */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + ASSERT_GE(ret, 0); + + found_parent = false; + found_child = false; + for (i = 0; i < ret; i++) { + if (ns_ids[i] == parent_userns_id) + found_parent = true; + if (ns_ids[i] == child_userns_id) + found_child = true; + } + + ASSERT_FALSE(found_parent); + ASSERT_FALSE(found_child); + TH_LOG("Nested user namespace credential changes preserved active refs (no leak)"); +} + +/* + * Test rapid credential changes don't cause refcount imbalances. + * This stress-tests the switch_cred_namespaces() logic. + */ +TEST(rapid_cred_changes_no_leak) +{ + pid_t pid; + int status; + __u64 userns_id; + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids[256]; + ssize_t ret; + int i; + bool found = false; + int pipefd[2]; + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child process */ + int fd, userns_fd; + __u64 child_userns_id; + uid_t orig_uid = getuid(); + int change_count; + + close(pipefd[0]); + + /* Create new user namespace with wider range of UIDs/GIDs */ + userns_fd = get_userns_fd(0, orig_uid, 100); + if (userns_fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (setns(userns_fd, CLONE_NEWUSER) < 0) { + close(userns_fd); + close(pipefd[1]); + exit(1); + } + close(userns_fd); + + /* Get user namespace ID */ + fd = open("/proc/self/ns/user", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &child_userns_id) < 0) { + close(fd); + close(pipefd[1]); + exit(1); + } + close(fd); + + write(pipefd[1], &child_userns_id, sizeof(child_userns_id)); + + /* + * Perform many rapid credential changes. + * Mix setuid, setgid, setreuid, setregid, setresuid, setresgid. + */ + for (change_count = 0; change_count < 200; change_count++) { + switch (change_count % 6) { + case 0: + setuid(change_count % 50); + break; + case 1: + setgid(change_count % 50); + break; + case 2: + setreuid(change_count % 50, (change_count + 1) % 50); + break; + case 3: + setregid(change_count % 50, (change_count + 1) % 50); + break; + case 4: + setresuid(change_count % 50, (change_count + 1) % 50, (change_count + 2) % 50); + break; + case 5: + setresgid(change_count % 50, (change_count + 1) % 50, (change_count + 2) % 50); + break; + } + } + + close(pipefd[1]); + exit(0); + } + + /* Parent process */ + close(pipefd[1]); + + if (read(pipefd[0], &userns_id, sizeof(userns_id)) != sizeof(userns_id)) { + close(pipefd[0]); + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to get namespace ID from child"); + } + close(pipefd[0]); + + TH_LOG("Testing with user namespace ID: %llu", (unsigned long long)userns_id); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* Verify namespace becomes inactive (no leaked active refs) */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + ASSERT_GE(ret, 0); + } + + for (i = 0; i < ret; i++) { + if (ns_ids[i] == userns_id) { + found = true; + break; + } + } + + ASSERT_FALSE(found); + TH_LOG("200 rapid credential changes completed with no active ref leak"); +} + +/* + * Test setfsuid/setfsgid which change filesystem UID/GID. + * These also trigger credential changes but may have different code paths. + */ +TEST(setfsuid_preserves_active_refs) +{ + pid_t pid; + int status; + __u64 userns_id; + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids[256]; + ssize_t ret; + int i; + bool found = false; + int pipefd[2]; + + ASSERT_EQ(pipe(pipefd), 0); + + pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child process */ + int fd, userns_fd; + __u64 child_userns_id; + uid_t orig_uid = getuid(); + int change_count; + + close(pipefd[0]); + + /* Create new user namespace */ + userns_fd = get_userns_fd(0, orig_uid, 10); + if (userns_fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (setns(userns_fd, CLONE_NEWUSER) < 0) { + close(userns_fd); + close(pipefd[1]); + exit(1); + } + close(userns_fd); + + /* Get user namespace ID */ + fd = open("/proc/self/ns/user", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + exit(1); + } + + if (ioctl(fd, NS_GET_ID, &child_userns_id) < 0) { + close(fd); + close(pipefd[1]); + exit(1); + } + close(fd); + + write(pipefd[1], &child_userns_id, sizeof(child_userns_id)); + + /* Perform multiple setfsuid/setfsgid calls */ + for (change_count = 0; change_count < 50; change_count++) { + setfsuid(change_count % 10); + setfsgid(change_count % 10); + } + + close(pipefd[1]); + exit(0); + } + + /* Parent process */ + close(pipefd[1]); + + if (read(pipefd[0], &userns_id, sizeof(userns_id)) != sizeof(userns_id)) { + close(pipefd[0]); + kill(pid, SIGKILL); + waitpid(pid, NULL, 0); + SKIP(return, "Failed to get namespace ID from child"); + } + close(pipefd[0]); + + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + + /* Verify namespace becomes inactive */ + ret = sys_listns(&req, ns_ids, ARRAY_SIZE(ns_ids), 0); + if (ret < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + ASSERT_GE(ret, 0); + } + + for (i = 0; i < ret; i++) { + if (ns_ids[i] == userns_id) { + found = true; + break; + } + } + + ASSERT_FALSE(found); + TH_LOG("setfsuid/setfsgid correctly preserved active references (no leak)"); +} + +TEST_HARNESS_MAIN From fc85885692a84a6c561351973fea26e4426ae72b Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:24 +0100 Subject: [PATCH 74/75] selftests/namespace: add stress test Stress tests for namespace active reference counting. These tests validate that the active reference counting system can handle high load scenarios including rapid namespace creation/destruction, large numbers of concurrent namespaces, and various edge cases under stress. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-71-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- tools/testing/selftests/namespaces/.gitignore | 1 + tools/testing/selftests/namespaces/Makefile | 4 +- .../selftests/namespaces/stress_test.c | 626 ++++++++++++++++++ 3 files changed, 630 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/namespaces/stress_test.c diff --git a/tools/testing/selftests/namespaces/.gitignore b/tools/testing/selftests/namespaces/.gitignore index 0091a7dfff20..f6dcf769f150 100644 --- a/tools/testing/selftests/namespaces/.gitignore +++ b/tools/testing/selftests/namespaces/.gitignore @@ -6,3 +6,4 @@ listns_test listns_permissions_test siocgskns_test cred_change_test +stress_test diff --git a/tools/testing/selftests/namespaces/Makefile b/tools/testing/selftests/namespaces/Makefile index 5d73f8dde6a0..3c776740f3ac 100644 --- a/tools/testing/selftests/namespaces/Makefile +++ b/tools/testing/selftests/namespaces/Makefile @@ -9,7 +9,8 @@ TEST_GEN_PROGS := nsid_test \ listns_test \ listns_permissions_test \ siocgskns_test \ - cred_change_test + cred_change_test \ + stress_test include ../lib.mk @@ -18,4 +19,5 @@ $(OUTPUT)/listns_test: ../filesystems/utils.c $(OUTPUT)/listns_permissions_test: ../filesystems/utils.c $(OUTPUT)/siocgskns_test: ../filesystems/utils.c $(OUTPUT)/cred_change_test: ../filesystems/utils.c +$(OUTPUT)/stress_test: ../filesystems/utils.c diff --git a/tools/testing/selftests/namespaces/stress_test.c b/tools/testing/selftests/namespaces/stress_test.c new file mode 100644 index 000000000000..dd7df7d6cb27 --- /dev/null +++ b/tools/testing/selftests/namespaces/stress_test.c @@ -0,0 +1,626 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "../kselftest_harness.h" +#include "../filesystems/utils.h" +#include "wrappers.h" + +/* + * Stress tests for namespace active reference counting. + * + * These tests validate that the active reference counting system can handle + * high load scenarios including rapid namespace creation/destruction, large + * numbers of concurrent namespaces, and various edge cases under stress. + */ + +/* + * Test rapid creation and destruction of user namespaces. + * Create and destroy namespaces in quick succession to stress the + * active reference tracking and ensure no leaks occur. + */ +TEST(rapid_namespace_creation_destruction) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids_before[256], ns_ids_after[256]; + ssize_t ret_before, ret_after; + int i; + + /* Get baseline count of active user namespaces */ + ret_before = sys_listns(&req, ns_ids_before, ARRAY_SIZE(ns_ids_before), 0); + if (ret_before < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + ASSERT_GE(ret_before, 0); + } + + TH_LOG("Baseline: %zd active user namespaces", ret_before); + + /* Rapidly create and destroy 100 user namespaces */ + for (i = 0; i < 100; i++) { + pid_t pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child: create user namespace and immediately exit */ + if (setup_userns() < 0) + exit(1); + exit(0); + } + + /* Parent: wait for child */ + int status; + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + } + + /* Verify we're back to baseline (no leaked namespaces) */ + ret_after = sys_listns(&req, ns_ids_after, ARRAY_SIZE(ns_ids_after), 0); + ASSERT_GE(ret_after, 0); + + TH_LOG("After 100 rapid create/destroy cycles: %zd active user namespaces", ret_after); + ASSERT_EQ(ret_before, ret_after); +} + +/* + * Test creating many concurrent namespaces. + * Verify that listns() correctly tracks all of them and that they all + * become inactive after processes exit. + */ +TEST(many_concurrent_namespaces) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids_before[512], ns_ids_during[512], ns_ids_after[512]; + ssize_t ret_before, ret_during, ret_after; + pid_t pids[50]; + int num_children = 50; + int i; + int sv[2]; + + /* Get baseline */ + ret_before = sys_listns(&req, ns_ids_before, ARRAY_SIZE(ns_ids_before), 0); + if (ret_before < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + ASSERT_GE(ret_before, 0); + } + + TH_LOG("Baseline: %zd active user namespaces", ret_before); + + ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sv), 0); + + /* Create many children, each with their own user namespace */ + for (i = 0; i < num_children; i++) { + pids[i] = fork(); + ASSERT_GE(pids[i], 0); + + if (pids[i] == 0) { + /* Child: create user namespace and wait for parent signal */ + char c; + + close(sv[0]); + + if (setup_userns() < 0) { + close(sv[1]); + exit(1); + } + + /* Signal parent we're ready */ + if (write(sv[1], &c, 1) != 1) { + close(sv[1]); + exit(1); + } + + /* Wait for parent signal to exit */ + if (read(sv[1], &c, 1) != 1) { + close(sv[1]); + exit(1); + } + + close(sv[1]); + exit(0); + } + } + + close(sv[1]); + + /* Wait for all children to signal ready */ + for (i = 0; i < num_children; i++) { + char c; + if (read(sv[0], &c, 1) != 1) { + /* If we fail to read, kill all children and exit */ + close(sv[0]); + for (int j = 0; j < num_children; j++) + kill(pids[j], SIGKILL); + for (int j = 0; j < num_children; j++) + waitpid(pids[j], NULL, 0); + ASSERT_TRUE(false); + } + } + + /* List namespaces while all children are running */ + ret_during = sys_listns(&req, ns_ids_during, ARRAY_SIZE(ns_ids_during), 0); + ASSERT_GE(ret_during, 0); + + TH_LOG("With %d children running: %zd active user namespaces", num_children, ret_during); + + /* Should have at least num_children more namespaces than baseline */ + ASSERT_GE(ret_during, ret_before + num_children); + + /* Signal all children to exit */ + for (i = 0; i < num_children; i++) { + char c = 'X'; + if (write(sv[0], &c, 1) != 1) { + /* If we fail to write, kill remaining children */ + close(sv[0]); + for (int j = i; j < num_children; j++) + kill(pids[j], SIGKILL); + for (int j = 0; j < num_children; j++) + waitpid(pids[j], NULL, 0); + ASSERT_TRUE(false); + } + } + + close(sv[0]); + + /* Wait for all children */ + for (i = 0; i < num_children; i++) { + int status; + waitpid(pids[i], &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + } + + /* Verify we're back to baseline */ + ret_after = sys_listns(&req, ns_ids_after, ARRAY_SIZE(ns_ids_after), 0); + ASSERT_GE(ret_after, 0); + + TH_LOG("After all children exit: %zd active user namespaces", ret_after); + ASSERT_EQ(ret_before, ret_after); +} + +/* + * Test rapid namespace creation with different namespace types. + * Create multiple types of namespaces rapidly to stress the tracking system. + */ +TEST(rapid_mixed_namespace_creation) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = 0, /* All types */ + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids_before[512], ns_ids_after[512]; + ssize_t ret_before, ret_after; + int i; + + /* Get baseline count */ + ret_before = sys_listns(&req, ns_ids_before, ARRAY_SIZE(ns_ids_before), 0); + if (ret_before < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + ASSERT_GE(ret_before, 0); + } + + TH_LOG("Baseline: %zd active namespaces (all types)", ret_before); + + /* Rapidly create and destroy namespaces with multiple types */ + for (i = 0; i < 50; i++) { + pid_t pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + /* Child: create multiple namespace types */ + if (setup_userns() < 0) + exit(1); + + /* Create additional namespace types */ + if (unshare(CLONE_NEWNET) < 0) + exit(1); + if (unshare(CLONE_NEWUTS) < 0) + exit(1); + if (unshare(CLONE_NEWIPC) < 0) + exit(1); + + exit(0); + } + + /* Parent: wait for child */ + int status; + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + } + + /* Verify we're back to baseline */ + ret_after = sys_listns(&req, ns_ids_after, ARRAY_SIZE(ns_ids_after), 0); + ASSERT_GE(ret_after, 0); + + TH_LOG("After 50 rapid mixed namespace cycles: %zd active namespaces", ret_after); + ASSERT_EQ(ret_before, ret_after); +} + +/* + * Test nested namespace creation under stress. + * Create deeply nested namespace hierarchies and verify proper cleanup. + */ +TEST(nested_namespace_stress) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids_before[512], ns_ids_after[512]; + ssize_t ret_before, ret_after; + int i; + + /* Get baseline */ + ret_before = sys_listns(&req, ns_ids_before, ARRAY_SIZE(ns_ids_before), 0); + if (ret_before < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + ASSERT_GE(ret_before, 0); + } + + TH_LOG("Baseline: %zd active user namespaces", ret_before); + + /* Create 20 processes, each with nested user namespaces */ + for (i = 0; i < 20; i++) { + pid_t pid = fork(); + ASSERT_GE(pid, 0); + + if (pid == 0) { + int userns_fd; + uid_t orig_uid = getuid(); + int depth; + + /* Create nested user namespaces (up to 5 levels) */ + for (depth = 0; depth < 5; depth++) { + userns_fd = get_userns_fd(0, (depth == 0) ? orig_uid : 0, 1); + if (userns_fd < 0) + exit(1); + + if (setns(userns_fd, CLONE_NEWUSER) < 0) { + close(userns_fd); + exit(1); + } + close(userns_fd); + } + + exit(0); + } + + /* Parent: wait for child */ + int status; + waitpid(pid, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + } + + /* Verify we're back to baseline */ + ret_after = sys_listns(&req, ns_ids_after, ARRAY_SIZE(ns_ids_after), 0); + ASSERT_GE(ret_after, 0); + + TH_LOG("After 20 nested namespace hierarchies: %zd active user namespaces", ret_after); + ASSERT_EQ(ret_before, ret_after); +} + +/* + * Test listns() pagination under stress. + * Create many namespaces and verify pagination works correctly. + */ +TEST(listns_pagination_stress) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, + .spare2 = 0, + .user_ns_id = 0, + }; + pid_t pids[30]; + int num_children = 30; + int i; + int sv[2]; + __u64 all_ns_ids[512]; + int total_found = 0; + + ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sv), 0); + + /* Create many children with user namespaces */ + for (i = 0; i < num_children; i++) { + pids[i] = fork(); + ASSERT_GE(pids[i], 0); + + if (pids[i] == 0) { + char c; + close(sv[0]); + + if (setup_userns() < 0) { + close(sv[1]); + exit(1); + } + + /* Signal parent we're ready */ + if (write(sv[1], &c, 1) != 1) { + close(sv[1]); + exit(1); + } + + /* Wait for parent signal to exit */ + if (read(sv[1], &c, 1) != 1) { + close(sv[1]); + exit(1); + } + + close(sv[1]); + exit(0); + } + } + + close(sv[1]); + + /* Wait for all children to signal ready */ + for (i = 0; i < num_children; i++) { + char c; + if (read(sv[0], &c, 1) != 1) { + /* If we fail to read, kill all children and exit */ + close(sv[0]); + for (int j = 0; j < num_children; j++) + kill(pids[j], SIGKILL); + for (int j = 0; j < num_children; j++) + waitpid(pids[j], NULL, 0); + ASSERT_TRUE(false); + } + } + + /* Paginate through all namespaces using small batch sizes */ + req.ns_id = 0; + while (1) { + __u64 batch[5]; /* Small batch size to force pagination */ + ssize_t ret; + + ret = sys_listns(&req, batch, ARRAY_SIZE(batch), 0); + if (ret < 0) { + if (errno == ENOSYS) { + close(sv[0]); + for (i = 0; i < num_children; i++) + kill(pids[i], SIGKILL); + for (i = 0; i < num_children; i++) + waitpid(pids[i], NULL, 0); + SKIP(return, "listns() not supported"); + } + ASSERT_GE(ret, 0); + } + + if (ret == 0) + break; + + /* Store results */ + for (i = 0; i < ret && total_found < 512; i++) { + all_ns_ids[total_found++] = batch[i]; + } + + /* Update cursor for next batch */ + if (ret == ARRAY_SIZE(batch)) + req.ns_id = batch[ret - 1]; + else + break; + } + + TH_LOG("Paginated through %d user namespaces", total_found); + + /* Verify no duplicates in pagination */ + for (i = 0; i < total_found; i++) { + for (int j = i + 1; j < total_found; j++) { + if (all_ns_ids[i] == all_ns_ids[j]) { + TH_LOG("Found duplicate ns_id: %llu at positions %d and %d", + (unsigned long long)all_ns_ids[i], i, j); + ASSERT_TRUE(false); + } + } + } + + /* Signal all children to exit */ + for (i = 0; i < num_children; i++) { + char c = 'X'; + if (write(sv[0], &c, 1) != 1) { + close(sv[0]); + for (int j = i; j < num_children; j++) + kill(pids[j], SIGKILL); + for (int j = 0; j < num_children; j++) + waitpid(pids[j], NULL, 0); + ASSERT_TRUE(false); + } + } + + close(sv[0]); + + /* Wait for all children */ + for (i = 0; i < num_children; i++) { + int status; + waitpid(pids[i], &status, 0); + } +} + +/* + * Test concurrent namespace operations. + * Multiple processes creating, querying, and destroying namespaces concurrently. + */ +TEST(concurrent_namespace_operations) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = 0, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids_before[512], ns_ids_after[512]; + ssize_t ret_before, ret_after; + pid_t pids[20]; + int num_workers = 20; + int i; + + /* Get baseline */ + ret_before = sys_listns(&req, ns_ids_before, ARRAY_SIZE(ns_ids_before), 0); + if (ret_before < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + ASSERT_GE(ret_before, 0); + } + + TH_LOG("Baseline: %zd active namespaces", ret_before); + + /* Create worker processes that do concurrent operations */ + for (i = 0; i < num_workers; i++) { + pids[i] = fork(); + ASSERT_GE(pids[i], 0); + + if (pids[i] == 0) { + /* Each worker: create namespaces, list them, repeat */ + int iterations; + + for (iterations = 0; iterations < 10; iterations++) { + int userns_fd; + __u64 temp_ns_ids[100]; + ssize_t ret; + + /* Create a user namespace */ + userns_fd = get_userns_fd(0, getuid(), 1); + if (userns_fd < 0) + continue; + + /* List namespaces */ + ret = sys_listns(&req, temp_ns_ids, ARRAY_SIZE(temp_ns_ids), 0); + (void)ret; + + close(userns_fd); + + /* Small delay */ + usleep(1000); + } + + exit(0); + } + } + + /* Wait for all workers */ + for (i = 0; i < num_workers; i++) { + int status; + waitpid(pids[i], &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + ASSERT_EQ(WEXITSTATUS(status), 0); + } + + /* Verify we're back to baseline */ + ret_after = sys_listns(&req, ns_ids_after, ARRAY_SIZE(ns_ids_after), 0); + ASSERT_GE(ret_after, 0); + + TH_LOG("After concurrent operations: %zd active namespaces", ret_after); + ASSERT_EQ(ret_before, ret_after); +} + +/* + * Test namespace churn - continuous creation and destruction. + * Simulates high-churn scenarios like container orchestration. + */ +TEST(namespace_churn) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER | CLONE_NEWNET | CLONE_NEWUTS, + .spare2 = 0, + .user_ns_id = 0, + }; + __u64 ns_ids_before[512], ns_ids_after[512]; + ssize_t ret_before, ret_after; + int cycle; + + /* Get baseline */ + ret_before = sys_listns(&req, ns_ids_before, ARRAY_SIZE(ns_ids_before), 0); + if (ret_before < 0) { + if (errno == ENOSYS) + SKIP(return, "listns() not supported"); + ASSERT_GE(ret_before, 0); + } + + TH_LOG("Baseline: %zd active namespaces", ret_before); + + /* Simulate churn: batches of namespaces created and destroyed */ + for (cycle = 0; cycle < 10; cycle++) { + pid_t batch_pids[10]; + int i; + + /* Create batch */ + for (i = 0; i < 10; i++) { + batch_pids[i] = fork(); + ASSERT_GE(batch_pids[i], 0); + + if (batch_pids[i] == 0) { + /* Create multiple namespace types */ + if (setup_userns() < 0) + exit(1); + if (unshare(CLONE_NEWNET) < 0) + exit(1); + if (unshare(CLONE_NEWUTS) < 0) + exit(1); + + /* Keep namespaces alive briefly */ + usleep(10000); + exit(0); + } + } + + /* Wait for batch to complete */ + for (i = 0; i < 10; i++) { + int status; + waitpid(batch_pids[i], &status, 0); + } + } + + /* Verify we're back to baseline */ + ret_after = sys_listns(&req, ns_ids_after, ARRAY_SIZE(ns_ids_after), 0); + ASSERT_GE(ret_after, 0); + + TH_LOG("After 10 churn cycles (100 namespace sets): %zd active namespaces", ret_after); + ASSERT_EQ(ret_before, ret_after); +} + +TEST_HARNESS_MAIN From 2cc1c01fe97703d9d694fa49b16fb3aab47b70a9 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 29 Oct 2025 13:21:25 +0100 Subject: [PATCH 75/75] selftests/namespace: test listns() pagination Minimal test case to reproduce KASAN out-of-bounds in listns pagination. Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-72-2e6f823ebdc0@kernel.org Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- tools/testing/selftests/namespaces/.gitignore | 1 + tools/testing/selftests/namespaces/Makefile | 4 +- .../namespaces/listns_pagination_bug.c | 138 ++++++++++++++++++ 3 files changed, 142 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/namespaces/listns_pagination_bug.c diff --git a/tools/testing/selftests/namespaces/.gitignore b/tools/testing/selftests/namespaces/.gitignore index f6dcf769f150..f4d2209ca4e4 100644 --- a/tools/testing/selftests/namespaces/.gitignore +++ b/tools/testing/selftests/namespaces/.gitignore @@ -7,3 +7,4 @@ listns_permissions_test siocgskns_test cred_change_test stress_test +listns_pagination_bug diff --git a/tools/testing/selftests/namespaces/Makefile b/tools/testing/selftests/namespaces/Makefile index 3c776740f3ac..01569e0abbdb 100644 --- a/tools/testing/selftests/namespaces/Makefile +++ b/tools/testing/selftests/namespaces/Makefile @@ -10,7 +10,8 @@ TEST_GEN_PROGS := nsid_test \ listns_permissions_test \ siocgskns_test \ cred_change_test \ - stress_test + stress_test \ + listns_pagination_bug include ../lib.mk @@ -20,4 +21,5 @@ $(OUTPUT)/listns_permissions_test: ../filesystems/utils.c $(OUTPUT)/siocgskns_test: ../filesystems/utils.c $(OUTPUT)/cred_change_test: ../filesystems/utils.c $(OUTPUT)/stress_test: ../filesystems/utils.c +$(OUTPUT)/listns_pagination_bug: ../filesystems/utils.c diff --git a/tools/testing/selftests/namespaces/listns_pagination_bug.c b/tools/testing/selftests/namespaces/listns_pagination_bug.c new file mode 100644 index 000000000000..da7d33f96397 --- /dev/null +++ b/tools/testing/selftests/namespaces/listns_pagination_bug.c @@ -0,0 +1,138 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include "../kselftest_harness.h" +#include "../filesystems/utils.h" +#include "wrappers.h" + +/* + * Minimal test case to reproduce KASAN out-of-bounds in listns pagination. + * + * The bug occurs when: + * 1. Filtering by a specific namespace type (e.g., CLONE_NEWUSER) + * 2. Using pagination (req.ns_id != 0) + * 3. The lookup_ns_id_at() call in do_listns() passes ns_type=0 instead of + * the filtered type, causing it to search the unified tree and potentially + * return a namespace of the wrong type. + */ +TEST(pagination_with_type_filter) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, /* Filter by user namespace */ + .spare2 = 0, + .user_ns_id = 0, + }; + pid_t pids[10]; + int num_children = 10; + int i; + int sv[2]; + __u64 first_batch[3]; + ssize_t ret; + + ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sv), 0); + + /* Create children with user namespaces */ + for (i = 0; i < num_children; i++) { + pids[i] = fork(); + ASSERT_GE(pids[i], 0); + + if (pids[i] == 0) { + char c; + close(sv[0]); + + if (setup_userns() < 0) { + close(sv[1]); + exit(1); + } + + /* Signal parent we're ready */ + if (write(sv[1], &c, 1) != 1) { + close(sv[1]); + exit(1); + } + + /* Wait for parent signal to exit */ + if (read(sv[1], &c, 1) != 1) { + close(sv[1]); + exit(1); + } + + close(sv[1]); + exit(0); + } + } + + close(sv[1]); + + /* Wait for all children to signal ready */ + for (i = 0; i < num_children; i++) { + char c; + if (read(sv[0], &c, 1) != 1) { + close(sv[0]); + for (int j = 0; j < num_children; j++) + kill(pids[j], SIGKILL); + for (int j = 0; j < num_children; j++) + waitpid(pids[j], NULL, 0); + ASSERT_TRUE(false); + } + } + + /* First batch - this should work */ + ret = sys_listns(&req, first_batch, 3, 0); + if (ret < 0) { + if (errno == ENOSYS) { + close(sv[0]); + for (i = 0; i < num_children; i++) + kill(pids[i], SIGKILL); + for (i = 0; i < num_children; i++) + waitpid(pids[i], NULL, 0); + SKIP(return, "listns() not supported"); + } + ASSERT_GE(ret, 0); + } + + TH_LOG("First batch returned %zd entries", ret); + + if (ret == 3) { + __u64 second_batch[3]; + + /* Second batch - pagination triggers the bug */ + req.ns_id = first_batch[2]; /* Continue from last ID */ + ret = sys_listns(&req, second_batch, 3, 0); + + TH_LOG("Second batch returned %zd entries", ret); + ASSERT_GE(ret, 0); + } + + /* Signal all children to exit */ + for (i = 0; i < num_children; i++) { + char c = 'X'; + if (write(sv[0], &c, 1) != 1) { + close(sv[0]); + for (int j = i; j < num_children; j++) + kill(pids[j], SIGKILL); + for (int j = 0; j < num_children; j++) + waitpid(pids[j], NULL, 0); + ASSERT_TRUE(false); + } + } + + close(sv[0]); + + /* Cleanup */ + for (i = 0; i < num_children; i++) { + int status; + waitpid(pids[i], &status, 0); + } +} + +TEST_HARNESS_MAIN