mirror of https://github.com/torvalds/linux.git
169 Commits
| Author | SHA1 | Message | Date |
|---|---|---|---|
Sargun Dhillon
|
c2aa2dfef2 |
seccomp: Add wait_killable semantic to seccomp user notifier
This introduces a per-filter flag (SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV) that makes it so that when notifications are received by the supervisor the notifying process will transition to wait killable semantics. Although wait killable isn't a set of semantics formally exposed to userspace, the concept is searchable. If the notifying process is signaled prior to the notification being received by the userspace agent, it will be handled as normal. One quirk about how this is handled is that the notifying process only switches to TASK_KILLABLE if it receives a wakeup from either an addfd or a signal. This is to avoid an unnecessary wakeup of the notifying task. The reasons behind switching into wait_killable only after userspace receives the notification are: * Avoiding unncessary work - Often, workloads will perform work that they may abort (request racing comes to mind). This allows for syscalls to be aborted safely prior to the notification being received by the supervisor. In this, the supervisor doesn't end up doing work that the workload does not want to complete anyways. * Avoiding side effects - We don't want the syscall to be interruptible once the supervisor starts doing work because it may not be trivial to reverse the operation. For example, unmounting a file system may take a long time, and it's hard to rollback, or treat that as reentrant. * Avoid breaking runtimes - Various runtimes do not GC when they are during a syscall (or while running native code that subsequently calls a syscall). If many notifications are blocked, and not picked up by the supervisor, this can get the application into a bad state. Signed-off-by: Sargun Dhillon <sargun@sargun.me> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20220503080958.20220-2-sargun@sargun.me |
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Sargun Dhillon
|
4cbf6f6211 |
seccomp: Use FIFO semantics to order notifications
Previously, the seccomp notifier used LIFO semantics, where each notification would be added on top of the stack, and notifications were popped off the top of the stack. This could result one process that generates a large number of notifications preventing other notifications from being handled. This patch moves from LIFO (stack) semantics to FIFO (queue semantics). Signed-off-by: Sargun Dhillon <sargun@sargun.me> Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20220428015447.13661-1-sargun@sargun.me |
|
Linus Torvalds
|
1930a6e739 |
ptrace: Cleanups for v5.18
This set of changes removes tracehook.h, moves modification of all of
the ptrace fields inside of siglock to remove races, adds a missing
permission check to ptrace.c
The removal of tracehook.h is quite significant as it has been a major
source of confusion in recent years. Much of that confusion was
around task_work and TIF_NOTIFY_SIGNAL (which I have now decoupled
making the semantics clearer).
For people who don't know tracehook.h is a vestiage of an attempt to
implement uprobes like functionality that was never fully merged, and
was later superseeded by uprobes when uprobes was merged. For many
years now we have been removing what tracehook functionaly a little
bit at a time. To the point where now anything left in tracehook.h is
some weird strange thing that is difficult to understand.
Eric W. Biederman (15):
ptrace: Move ptrace_report_syscall into ptrace.h
ptrace/arm: Rename tracehook_report_syscall report_syscall
ptrace: Create ptrace_report_syscall_{entry,exit} in ptrace.h
ptrace: Remove arch_syscall_{enter,exit}_tracehook
ptrace: Remove tracehook_signal_handler
task_work: Remove unnecessary include from posix_timers.h
task_work: Introduce task_work_pending
task_work: Call tracehook_notify_signal from get_signal on all architectures
task_work: Decouple TIF_NOTIFY_SIGNAL and task_work
signal: Move set_notify_signal and clear_notify_signal into sched/signal.h
resume_user_mode: Remove #ifdef TIF_NOTIFY_RESUME in set_notify_resume
resume_user_mode: Move to resume_user_mode.h
tracehook: Remove tracehook.h
ptrace: Move setting/clearing ptrace_message into ptrace_stop
ptrace: Return the signal to continue with from ptrace_stop
Jann Horn (1):
ptrace: Check PTRACE_O_SUSPEND_SECCOMP permission on PTRACE_SEIZE
Yang Li (1):
ptrace: Remove duplicated include in ptrace.c
MAINTAINERS | 1 -
arch/Kconfig | 5 +-
arch/alpha/kernel/ptrace.c | 5 +-
arch/alpha/kernel/signal.c | 4 +-
arch/arc/kernel/ptrace.c | 5 +-
arch/arc/kernel/signal.c | 4 +-
arch/arm/kernel/ptrace.c | 12 +-
arch/arm/kernel/signal.c | 4 +-
arch/arm64/kernel/ptrace.c | 14 +--
arch/arm64/kernel/signal.c | 4 +-
arch/csky/kernel/ptrace.c | 5 +-
arch/csky/kernel/signal.c | 4 +-
arch/h8300/kernel/ptrace.c | 5 +-
arch/h8300/kernel/signal.c | 4 +-
arch/hexagon/kernel/process.c | 4 +-
arch/hexagon/kernel/signal.c | 1 -
arch/hexagon/kernel/traps.c | 6 +-
arch/ia64/kernel/process.c | 4 +-
arch/ia64/kernel/ptrace.c | 6 +-
arch/ia64/kernel/signal.c | 1 -
arch/m68k/kernel/ptrace.c | 5 +-
arch/m68k/kernel/signal.c | 4 +-
arch/microblaze/kernel/ptrace.c | 5 +-
arch/microblaze/kernel/signal.c | 4 +-
arch/mips/kernel/ptrace.c | 5 +-
arch/mips/kernel/signal.c | 4 +-
arch/nds32/include/asm/syscall.h | 2 +-
arch/nds32/kernel/ptrace.c | 5 +-
arch/nds32/kernel/signal.c | 4 +-
arch/nios2/kernel/ptrace.c | 5 +-
arch/nios2/kernel/signal.c | 4 +-
arch/openrisc/kernel/ptrace.c | 5 +-
arch/openrisc/kernel/signal.c | 4 +-
arch/parisc/kernel/ptrace.c | 7 +-
arch/parisc/kernel/signal.c | 4 +-
arch/powerpc/kernel/ptrace/ptrace.c | 8 +-
arch/powerpc/kernel/signal.c | 4 +-
arch/riscv/kernel/ptrace.c | 5 +-
arch/riscv/kernel/signal.c | 4 +-
arch/s390/include/asm/entry-common.h | 1 -
arch/s390/kernel/ptrace.c | 1 -
arch/s390/kernel/signal.c | 5 +-
arch/sh/kernel/ptrace_32.c | 5 +-
arch/sh/kernel/signal_32.c | 4 +-
arch/sparc/kernel/ptrace_32.c | 5 +-
arch/sparc/kernel/ptrace_64.c | 5 +-
arch/sparc/kernel/signal32.c | 1 -
arch/sparc/kernel/signal_32.c | 4 +-
arch/sparc/kernel/signal_64.c | 4 +-
arch/um/kernel/process.c | 4 +-
arch/um/kernel/ptrace.c | 5 +-
arch/x86/kernel/ptrace.c | 1 -
arch/x86/kernel/signal.c | 5 +-
arch/x86/mm/tlb.c | 1 +
arch/xtensa/kernel/ptrace.c | 5 +-
arch/xtensa/kernel/signal.c | 4 +-
block/blk-cgroup.c | 2 +-
fs/coredump.c | 1 -
fs/exec.c | 1 -
fs/io-wq.c | 6 +-
fs/io_uring.c | 11 +-
fs/proc/array.c | 1 -
fs/proc/base.c | 1 -
include/asm-generic/syscall.h | 2 +-
include/linux/entry-common.h | 47 +-------
include/linux/entry-kvm.h | 2 +-
include/linux/posix-timers.h | 1 -
include/linux/ptrace.h | 81 ++++++++++++-
include/linux/resume_user_mode.h | 64 ++++++++++
include/linux/sched/signal.h | 17 +++
include/linux/task_work.h | 5 +
include/linux/tracehook.h | 226 -----------------------------------
include/uapi/linux/ptrace.h | 2 +-
kernel/entry/common.c | 19 +--
kernel/entry/kvm.c | 9 +-
kernel/exit.c | 3 +-
kernel/livepatch/transition.c | 1 -
kernel/ptrace.c | 47 +++++---
kernel/seccomp.c | 1 -
kernel/signal.c | 62 +++++-----
kernel/task_work.c | 4 +-
kernel/time/posix-cpu-timers.c | 1 +
mm/memcontrol.c | 2 +-
security/apparmor/domain.c | 1 -
security/selinux/hooks.c | 1 -
85 files changed, 372 insertions(+), 495 deletions(-)
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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Merge tag 'ptrace-cleanups-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull ptrace cleanups from Eric Biederman:
"This set of changes removes tracehook.h, moves modification of all of
the ptrace fields inside of siglock to remove races, adds a missing
permission check to ptrace.c
The removal of tracehook.h is quite significant as it has been a major
source of confusion in recent years. Much of that confusion was around
task_work and TIF_NOTIFY_SIGNAL (which I have now decoupled making the
semantics clearer).
For people who don't know tracehook.h is a vestiage of an attempt to
implement uprobes like functionality that was never fully merged, and
was later superseeded by uprobes when uprobes was merged. For many
years now we have been removing what tracehook functionaly a little
bit at a time. To the point where anything left in tracehook.h was
some weird strange thing that was difficult to understand"
* tag 'ptrace-cleanups-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
ptrace: Remove duplicated include in ptrace.c
ptrace: Check PTRACE_O_SUSPEND_SECCOMP permission on PTRACE_SEIZE
ptrace: Return the signal to continue with from ptrace_stop
ptrace: Move setting/clearing ptrace_message into ptrace_stop
tracehook: Remove tracehook.h
resume_user_mode: Move to resume_user_mode.h
resume_user_mode: Remove #ifdef TIF_NOTIFY_RESUME in set_notify_resume
signal: Move set_notify_signal and clear_notify_signal into sched/signal.h
task_work: Decouple TIF_NOTIFY_SIGNAL and task_work
task_work: Call tracehook_notify_signal from get_signal on all architectures
task_work: Introduce task_work_pending
task_work: Remove unnecessary include from posix_timers.h
ptrace: Remove tracehook_signal_handler
ptrace: Remove arch_syscall_{enter,exit}_tracehook
ptrace: Create ptrace_report_syscall_{entry,exit} in ptrace.h
ptrace/arm: Rename tracehook_report_syscall report_syscall
ptrace: Move ptrace_report_syscall into ptrace.h
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Eric W. Biederman
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355f841a3f |
tracehook: Remove tracehook.h
Now that all of the definitions have moved out of tracehook.h into ptrace.h, sched/signal.h, resume_user_mode.h there is nothing left in tracehook.h so remove it. Update the few files that were depending upon tracehook.h to bring in definitions to use the headers they need directly. Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/20220309162454.123006-13-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> |
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Kees Cook
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495ac3069a |
seccomp: Invalidate seccomp mode to catch death failures
If seccomp tries to kill a process, it should never see that process
again. To enforce this proactively, switch the mode to something
impossible. If encountered: WARN, reject all syscalls, and attempt to
kill the process again even harder.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will Drewry <wad@chromium.org>
Fixes:
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Linus Torvalds
|
bcfeebbff3 |
Merge branch 'exit-cleanups-for-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull exit cleanups from Eric Biederman: "In preparation of doing something about PTRACE_EVENT_EXIT I have started cleaning up various pieces of code related to do_exit. Most of that code I did not manage to get tested and reviewed before the merge window opened but a handful of very useful cleanups are ready to be merged. The first change is simply the removal of the bdflush system call. The code has now been disabled long enough that even the oldest userspace working userspace setups anyone can find to test are fine with the bdflush system call being removed. Changing m68k fsp040_die to use force_sigsegv(SIGSEGV) instead of calling do_exit directly is interesting only in that it is nearly the most difficult of the incorrect uses of do_exit to remove. The change to the seccomp code to simply send a signal instead of calling do_coredump directly is a very nice little cleanup made possible by realizing the existing signal sending helpers were missing a little bit of functionality that is easy to provide" * 'exit-cleanups-for-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: signal/seccomp: Dump core when there is only one live thread signal/seccomp: Refactor seccomp signal and coredump generation signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die exit/bdflush: Remove the deprecated bdflush system call |
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Eric W. Biederman
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d21918e5a9 |
signal/seccomp: Dump core when there is only one live thread
Replace get_nr_threads with atomic_read(¤t->signal->live) as that is a more accurate number that is decremented sooner. Acked-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/87lf6z6qbd.fsf_-_@disp2133 Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> |
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Eric W. Biederman
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307d522f5e |
signal/seccomp: Refactor seccomp signal and coredump generation
Factor out force_sig_seccomp from the seccomp signal generation and place it in kernel/signal.c. The function force_sig_seccomp takes a parameter force_coredump to indicate that the sigaction field should be reset to SIGDFL so that a coredump will be generated when the signal is delivered. force_sig_seccomp is then used to replace both seccomp_send_sigsys and seccomp_init_siginfo. force_sig_info_to_task gains an extra parameter to force using the default signal action. With this change seccomp is no longer a special case and there becomes exactly one place do_coredump is called from. Further it no longer becomes necessary for __seccomp_filter to call do_group_exit. Acked-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/87r1gr6qc4.fsf_-_@disp2133 Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> |
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Hsuan-Chi Kuo
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b4d8a58f8d |
seccomp: Fix setting loaded filter count during TSYNC
The desired behavior is to set the caller's filter count to thread's.
This value is reported via /proc, so this fixes the inaccurate count
exposed to userspace; it is not used for reference counting, etc.
Signed-off-by: Hsuan-Chi Kuo <hsuanchikuo@gmail.com>
Link: https://lore.kernel.org/r/20210304233708.420597-1-hsuanchikuo@gmail.com
Co-developed-by: Wiktor Garbacz <wiktorg@google.com>
Signed-off-by: Wiktor Garbacz <wiktorg@google.com>
Link: https://lore.kernel.org/lkml/20210810125158.329849-1-wiktorg@google.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Fixes:
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Rodrigo Campos
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0ae71c7720 |
seccomp: Support atomic "addfd + send reply"
Alban Crequy reported a race condition userspace faces when we want to add some fds and make the syscall return them[1] using seccomp notify. The problem is that currently two different ioctl() calls are needed by the process handling the syscalls (agent) for another userspace process (target): SECCOMP_IOCTL_NOTIF_ADDFD to allocate the fd and SECCOMP_IOCTL_NOTIF_SEND to return that value. Therefore, it is possible for the agent to do the first ioctl to add a file descriptor but the target is interrupted (EINTR) before the agent does the second ioctl() call. This patch adds a flag to the ADDFD ioctl() so it adds the fd and returns that value atomically to the target program, as suggested by Kees Cook[2]. This is done by simply allowing seccomp_do_user_notification() to add the fd and return it in this case. Therefore, in this case the target wakes up from the wait in seccomp_do_user_notification() either to interrupt the syscall or to add the fd and return it. This "allocate an fd and return" functionality is useful for syscalls that return a file descriptor only, like connect(2). Other syscalls that return a file descriptor but not as return value (or return more than one fd), like socketpair(), pipe(), recvmsg with SCM_RIGHTs, will not work with this flag. This effectively combines SECCOMP_IOCTL_NOTIF_ADDFD and SECCOMP_IOCTL_NOTIF_SEND into an atomic opteration. The notification's return value, nor error can be set by the user. Upon successful invocation of the SECCOMP_IOCTL_NOTIF_ADDFD ioctl with the SECCOMP_ADDFD_FLAG_SEND flag, the notifying process's errno will be 0, and the return value will be the file descriptor number that was installed. [1]: https://lore.kernel.org/lkml/CADZs7q4sw71iNHmV8EOOXhUKJMORPzF7thraxZYddTZsxta-KQ@mail.gmail.com/ [2]: https://lore.kernel.org/lkml/202012011322.26DCBC64F2@keescook/ Signed-off-by: Rodrigo Campos <rodrigo@kinvolk.io> Signed-off-by: Sargun Dhillon <sargun@sargun.me> Acked-by: Tycho Andersen <tycho@tycho.pizza> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20210517193908.3113-4-sargun@sargun.me |
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Sargun Dhillon
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ddc4739169 |
seccomp: Refactor notification handler to prepare for new semantics
This refactors the user notification code to have a do / while loop around
the completion condition. This has a small change in semantic, in that
previously we ignored addfd calls upon wakeup if the notification had been
responded to, but instead with the new change we check for an outstanding
addfd calls prior to returning to userspace.
Rodrigo Campos also identified a bug that can result in addfd causing
an early return, when the supervisor didn't actually handle the
syscall [1].
[1]: https://lore.kernel.org/lkml/20210413160151.3301-1-rodrigo@kinvolk.io/
Fixes:
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Linus Torvalds
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23806a3e96 |
Merge branch 'work.file' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull receive_fd update from Al Viro: "Cleanup of receive_fd mess" * 'work.file' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: fs: split receive_fd_replace from __receive_fd |
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Christoph Hellwig
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42eb0d54c0 |
fs: split receive_fd_replace from __receive_fd
receive_fd_replace shares almost no code with the general case, so split it out. Also remove the "Bump the sock usage counts" comment from both copies, as that is now what __receive_sock actually does. [AV: ... and make the only user of receive_fd_replace() choose between it and receive_fd() according to what userland had passed to it in flags] Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
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Cui GaoSheng
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a3fc712c5b |
seccomp: Fix "cacheable" typo in comments
Do a trivial typo fix: s/cachable/cacheable/ Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Cui GaoSheng <cuigaosheng1@huawei.com> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20210331030724.84419-1-cuigaosheng1@huawei.com |
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wanghongzhe
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a381b70a1c |
seccomp: Improve performace by optimizing rmb()
According to Kees's suggest, we started with the patch that just replaces
rmb() with smp_rmb() and did a performance test with UnixBench. The
results showed the overhead about 2.53% in rmb() test compared to the
smp_rmb() one, in a x86-64 kernel with CONFIG_SMP enabled running inside a
qemu-kvm vm. The test is a "syscall" testcase in UnixBench, which executes
5 syscalls in a loop during a certain timeout (100 second in our test) and
counts the total number of executions of this 5-syscall sequence. We set
a seccomp filter with all allow rule for all used syscalls in this test
(which will go bitmap path) to make sure the rmb() will be executed. The
details for the test:
with rmb():
/txm # ./syscall_allow_min 100
COUNT|35861159|1|lps
/txm # ./syscall_allow_min 100
COUNT|35545501|1|lps
/txm # ./syscall_allow_min 100
COUNT|35664495|1|lps
with smp_rmb():
/txm # ./syscall_allow_min 100
COUNT|36552771|1|lps
/txm # ./syscall_allow_min 100
COUNT|36491247|1|lps
/txm # ./syscall_allow_min 100
COUNT|36504746|1|lps
For a x86-64 kernel with CONFIG_SMP enabled, the smp_rmb() is just a
compiler barrier() which have no impact in runtime, while rmb() is a
lfence which will prevent all memory access operations (not just load
according the recently claim by Intel) behind itself. We can also figure
it out in disassembly:
with rmb():
0000000000001430 <__seccomp_filter>:
1430: 41 57 push %r15
1432: 41 56 push %r14
1434: 41 55 push %r13
1436: 41 54 push %r12
1438: 55 push %rbp
1439: 53 push %rbx
143a: 48 81 ec 90 00 00 00 sub $0x90,%rsp
1441: 89 7c 24 10 mov %edi,0x10(%rsp)
1445: 89 54 24 14 mov %edx,0x14(%rsp)
1449: 65 48 8b 04 25 28 00 mov %gs:0x28,%rax
1450: 00 00
1452: 48 89 84 24 88 00 00 mov %rax,0x88(%rsp)
1459: 00
145a: 31 c0 xor %eax,%eax
* 145c: 0f ae e8 lfence
145f: 48 85 f6 test %rsi,%rsi
1462: 49 89 f4 mov %rsi,%r12
1465: 0f 84 42 03 00 00 je 17ad <__seccomp_filter+0x37d>
146b: 65 48 8b 04 25 00 00 mov %gs:0x0,%rax
1472: 00 00
1474: 48 8b 98 80 07 00 00 mov 0x780(%rax),%rbx
147b: 48 85 db test %rbx,%rbx
with smp_rmb();
0000000000001430 <__seccomp_filter>:
1430: 41 57 push %r15
1432: 41 56 push %r14
1434: 41 55 push %r13
1436: 41 54 push %r12
1438: 55 push %rbp
1439: 53 push %rbx
143a: 48 81 ec 90 00 00 00 sub $0x90,%rsp
1441: 89 7c 24 10 mov %edi,0x10(%rsp)
1445: 89 54 24 14 mov %edx,0x14(%rsp)
1449: 65 48 8b 04 25 28 00 mov %gs:0x28,%rax
1450: 00 00
1452: 48 89 84 24 88 00 00 mov %rax,0x88(%rsp)
1459: 00
145a: 31 c0 xor %eax,%eax
145c: 48 85 f6 test %rsi,%rsi
145f: 49 89 f4 mov %rsi,%r12
1462: 0f 84 42 03 00 00 je 17aa <__seccomp_filter+0x37a>
1468: 65 48 8b 04 25 00 00 mov %gs:0x0,%rax
146f: 00 00
1471: 48 8b 98 80 07 00 00 mov 0x780(%rax),%rbx
1478: 48 85 db test %rbx,%rbx
Signed-off-by: wanghongzhe <wanghongzhe@huawei.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/1612496049-32507-1-git-send-email-wanghongzhe@huawei.com
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Paul Cercueil
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04b38d0125 |
seccomp: Add missing return in non-void function
We don't actually care about the value, since the kernel will panic
before that; but a value should nonetheless be returned, otherwise the
compiler will complain.
Fixes:
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Linus Torvalds
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e994cc240a |
seccomp updates for v5.11-rc1
- Improve seccomp performance via constant-action bitmaps (YiFei Zhu & Kees Cook)
- Fix bogus __user annotations (Jann Horn)
- Add missed CONFIG for improved selftest coverage (Mickaël Salaün)
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Merge tag 'seccomp-v5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull seccomp updates from Kees Cook:
"The major change here is finally gaining seccomp constant-action
bitmaps, which internally reduces the seccomp overhead for many
real-world syscall filters to O(1), as discussed at Plumbers this
year.
- Improve seccomp performance via constant-action bitmaps (YiFei Zhu
& Kees Cook)
- Fix bogus __user annotations (Jann Horn)
- Add missed CONFIG for improved selftest coverage (Mickaël Salaün)"
* tag 'seccomp-v5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
selftests/seccomp: Update kernel config
seccomp: Remove bogus __user annotations
seccomp/cache: Report cache data through /proc/pid/seccomp_cache
xtensa: Enable seccomp architecture tracking
sh: Enable seccomp architecture tracking
s390: Enable seccomp architecture tracking
riscv: Enable seccomp architecture tracking
powerpc: Enable seccomp architecture tracking
parisc: Enable seccomp architecture tracking
csky: Enable seccomp architecture tracking
arm: Enable seccomp architecture tracking
arm64: Enable seccomp architecture tracking
selftests/seccomp: Compare bitmap vs filter overhead
x86: Enable seccomp architecture tracking
seccomp/cache: Add "emulator" to check if filter is constant allow
seccomp/cache: Lookup syscall allowlist bitmap for fast path
|
|
|
Linus Torvalds
|
1ac0884d54 |
A set of updates for entry/exit handling:
- More generalization of entry/exit functionality
- The consolidation work to reclaim TIF flags on x86 and also for non-x86
specific TIF flags which are solely relevant for syscall related work
and have been moved into their own storage space. The x86 specific part
had to be merged in to avoid a major conflict.
- The TIF_NOTIFY_SIGNAL work which replaces the inefficient signal
delivery mode of task work and results in an impressive performance
improvement for io_uring. The non-x86 consolidation of this is going to
come seperate via Jens.
- The selective syscall redirection facility which provides a clean and
efficient way to support the non-Linux syscalls of WINE by catching them
at syscall entry and redirecting them to the user space emulation. This
can be utilized for other purposes as well and has been designed
carefully to avoid overhead for the regular fastpath. This includes the
core changes and the x86 support code.
- Simplification of the context tracking entry/exit handling for the users
of the generic entry code which guarantee the proper ordering and
protection.
- Preparatory changes to make the generic entry code accomodate S390
specific requirements which are mostly related to their syscall restart
mechanism.
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Merge tag 'core-entry-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core entry/exit updates from Thomas Gleixner:
"A set of updates for entry/exit handling:
- More generalization of entry/exit functionality
- The consolidation work to reclaim TIF flags on x86 and also for
non-x86 specific TIF flags which are solely relevant for syscall
related work and have been moved into their own storage space. The
x86 specific part had to be merged in to avoid a major conflict.
- The TIF_NOTIFY_SIGNAL work which replaces the inefficient signal
delivery mode of task work and results in an impressive performance
improvement for io_uring. The non-x86 consolidation of this is
going to come seperate via Jens.
- The selective syscall redirection facility which provides a clean
and efficient way to support the non-Linux syscalls of WINE by
catching them at syscall entry and redirecting them to the user
space emulation. This can be utilized for other purposes as well
and has been designed carefully to avoid overhead for the regular
fastpath. This includes the core changes and the x86 support code.
- Simplification of the context tracking entry/exit handling for the
users of the generic entry code which guarantee the proper ordering
and protection.
- Preparatory changes to make the generic entry code accomodate S390
specific requirements which are mostly related to their syscall
restart mechanism"
* tag 'core-entry-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
entry: Add syscall_exit_to_user_mode_work()
entry: Add exit_to_user_mode() wrapper
entry_Add_enter_from_user_mode_wrapper
entry: Rename exit_to_user_mode()
entry: Rename enter_from_user_mode()
docs: Document Syscall User Dispatch
selftests: Add benchmark for syscall user dispatch
selftests: Add kselftest for syscall user dispatch
entry: Support Syscall User Dispatch on common syscall entry
kernel: Implement selective syscall userspace redirection
signal: Expose SYS_USER_DISPATCH si_code type
x86: vdso: Expose sigreturn address on vdso to the kernel
MAINTAINERS: Add entry for common entry code
entry: Fix boot for !CONFIG_GENERIC_ENTRY
x86: Support HAVE_CONTEXT_TRACKING_OFFSTACK
context_tracking: Only define schedule_user() on !HAVE_CONTEXT_TRACKING_OFFSTACK archs
sched: Detect call to schedule from critical entry code
context_tracking: Don't implement exception_enter/exit() on CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK
context_tracking: Introduce HAVE_CONTEXT_TRACKING_OFFSTACK
x86: Reclaim unused x86 TI flags
...
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Kees Cook
|
7ef95e3dbc | Merge branch 'for-linus/seccomp' into for-next/seccomp | |
Jann Horn
|
fab686eb03 |
seccomp: Remove bogus __user annotations
Buffers that are passed to read_actions_logged() and write_actions_logged()
are in kernel memory; the sysctl core takes care of copying from/to
userspace.
Fixes:
|
|
YiFei Zhu
|
0d8315dddd |
seccomp/cache: Report cache data through /proc/pid/seccomp_cache
Currently the kernel does not provide an infrastructure to translate architecture numbers to a human-readable name. Translating syscall numbers to syscall names is possible through FTRACE_SYSCALL infrastructure but it does not provide support for compat syscalls. This will create a file for each PID as /proc/pid/seccomp_cache. The file will be empty when no seccomp filters are loaded, or be in the format of: <arch name> <decimal syscall number> <ALLOW | FILTER> where ALLOW means the cache is guaranteed to allow the syscall, and filter means the cache will pass the syscall to the BPF filter. For the docker default profile on x86_64 it looks like: x86_64 0 ALLOW x86_64 1 ALLOW x86_64 2 ALLOW x86_64 3 ALLOW [...] x86_64 132 ALLOW x86_64 133 ALLOW x86_64 134 FILTER x86_64 135 FILTER x86_64 136 FILTER x86_64 137 ALLOW x86_64 138 ALLOW x86_64 139 FILTER x86_64 140 ALLOW x86_64 141 ALLOW [...] This file is guarded by CONFIG_SECCOMP_CACHE_DEBUG with a default of N because I think certain users of seccomp might not want the application to know which syscalls are definitely usable. For the same reason, it is also guarded by CAP_SYS_ADMIN. Suggested-by: Jann Horn <jannh@google.com> Link: https://lore.kernel.org/lkml/CAG48ez3Ofqp4crXGksLmZY6=fGrF_tWyUCg7PBkAetvbbOPeOA@mail.gmail.com/ Signed-off-by: YiFei Zhu <yifeifz2@illinois.edu> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/94e663fa53136f5a11f432c661794d1ee7060779.1605101222.git.yifeifz2@illinois.edu |
|
|
YiFei Zhu
|
8e01b51a31 |
seccomp/cache: Add "emulator" to check if filter is constant allow
SECCOMP_CACHE will only operate on syscalls that do not access any syscall arguments or instruction pointer. To facilitate this we need a static analyser to know whether a filter will return allow regardless of syscall arguments for a given architecture number / syscall number pair. This is implemented here with a pseudo-emulator, and stored in a per-filter bitmap. In order to build this bitmap at filter attach time, each filter is emulated for every syscall (under each possible architecture), and checked for any accesses of struct seccomp_data that are not the "arch" nor "nr" (syscall) members. If only "arch" and "nr" are examined, and the program returns allow, then we can be sure that the filter must return allow independent from syscall arguments. Nearly all seccomp filters are built from these cBPF instructions: BPF_LD | BPF_W | BPF_ABS BPF_JMP | BPF_JEQ | BPF_K BPF_JMP | BPF_JGE | BPF_K BPF_JMP | BPF_JGT | BPF_K BPF_JMP | BPF_JSET | BPF_K BPF_JMP | BPF_JA BPF_RET | BPF_K BPF_ALU | BPF_AND | BPF_K Each of these instructions are emulated. Any weirdness or loading from a syscall argument will cause the emulator to bail. The emulation is also halted if it reaches a return. In that case, if it returns an SECCOMP_RET_ALLOW, the syscall is marked as good. Emulator structure and comments are from Kees [1] and Jann [2]. Emulation is done at attach time. If a filter depends on more filters, and if the dependee does not guarantee to allow the syscall, then we skip the emulation of this syscall. [1] https://lore.kernel.org/lkml/20200923232923.3142503-5-keescook@chromium.org/ [2] https://lore.kernel.org/lkml/CAG48ez1p=dR_2ikKq=xVxkoGg0fYpTBpkhJSv1w-6BG=76PAvw@mail.gmail.com/ Suggested-by: Jann Horn <jannh@google.com> Signed-off-by: YiFei Zhu <yifeifz2@illinois.edu> Reviewed-by: Jann Horn <jannh@google.com> Co-developed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/71c7be2db5ee08905f41c3be5c1ad6e2601ce88f.1602431034.git.yifeifz2@illinois.edu |
|
|
YiFei Zhu
|
f9d480b6ff |
seccomp/cache: Lookup syscall allowlist bitmap for fast path
The overhead of running Seccomp filters has been part of some past discussions [1][2][3]. Oftentimes, the filters have a large number of instructions that check syscall numbers one by one and jump based on that. Some users chain BPF filters which further enlarge the overhead. A recent work [6] comprehensively measures the Seccomp overhead and shows that the overhead is non-negligible and has a non-trivial impact on application performance. We observed some common filters, such as docker's [4] or systemd's [5], will make most decisions based only on the syscall numbers, and as past discussions considered, a bitmap where each bit represents a syscall makes most sense for these filters. The fast (common) path for seccomp should be that the filter permits the syscall to pass through, and failing seccomp is expected to be an exceptional case; it is not expected for userspace to call a denylisted syscall over and over. When it can be concluded that an allow must occur for the given architecture and syscall pair (this determination is introduced in the next commit), seccomp will immediately allow the syscall, bypassing further BPF execution. Each architecture number has its own bitmap. The architecture number in seccomp_data is checked against the defined architecture number constant before proceeding to test the bit against the bitmap with the syscall number as the index of the bit in the bitmap, and if the bit is set, seccomp returns allow. The bitmaps are all clear in this patch and will be initialized in the next commit. When only one architecture exists, the check against architecture number is skipped, suggested by Kees Cook [7]. [1] https://lore.kernel.org/linux-security-module/c22a6c3cefc2412cad00ae14c1371711@huawei.com/T/ [2] https://lore.kernel.org/lkml/202005181120.971232B7B@keescook/T/ [3] https://github.com/seccomp/libseccomp/issues/116 [4] |
|
Mickaël Salaün
|
fb14528e44 |
seccomp: Set PF_SUPERPRIV when checking capability
Replace the use of security_capable(current_cred(), ...) with ns_capable_noaudit() which set PF_SUPERPRIV. Since commit |
|
Gabriel Krisman Bertazi
|
23d67a5485 |
seccomp: Migrate to use SYSCALL_WORK flag
On architectures using the generic syscall entry code the architecture independent syscall work is moved to flags in thread_info::syscall_work. This removes architecture dependencies and frees up TIF bits. Define SYSCALL_WORK_SECCOMP, use it in the generic entry code and convert the code which uses the TIF specific helper functions to use the new *_syscall_work() helpers which either resolve to the new mode for users of the generic entry code or to the TIF based functions for the other architectures. Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20201116174206.2639648-5-krisman@collabora.com |
|
|
Jann Horn
|
dfe719fef0 |
seccomp: Make duplicate listener detection non-racy
Currently, init_listener() tries to prevent adding a filter with SECCOMP_FILTER_FLAG_NEW_LISTENER if one of the existing filters already has a listener. However, this check happens without holding any lock that would prevent another thread from concurrently installing a new filter (potentially with a listener) on top of the ones we already have. Theoretically, this is also a data race: The plain load from current->seccomp.filter can race with concurrent writes to the same location. Fix it by moving the check into the region that holds the siglock to guard against concurrent TSYNC. (The "Fixes" tag points to the commit that introduced the theoretical data race; concurrent installation of another filter with TSYNC only became possible later, in commit |
|
Denis Efremov
|
2d9ca267a9 |
seccomp: Use current_pt_regs() instead of task_pt_regs(current)
As described in commit
|
|
Rich Felker
|
4d671d922d |
seccomp: kill process instead of thread for unknown actions
Asynchronous termination of a thread outside of the userspace thread library's knowledge is an unsafe operation that leaves the process in an inconsistent, corrupt, and possibly unrecoverable state. In order to make new actions that may be added in the future safe on kernels not aware of them, change the default action from SECCOMP_RET_KILL_THREAD to SECCOMP_RET_KILL_PROCESS. Signed-off-by: Rich Felker <dalias@libc.org> Link: https://lore.kernel.org/r/20200829015609.GA32566@brightrain.aerifal.cx [kees: Fixed up coredump selection logic to match] Signed-off-by: Kees Cook <keescook@chromium.org> |
|
Tycho Andersen
|
e839317900 |
seccomp: don't leave dangling ->notif if file allocation fails
Christian and Kees both pointed out that this is a bit sloppy to open-code both places, and Christian points out that we leave a dangling pointer to ->notif if file allocation fails. Since we check ->notif for null in order to determine if it's ok to install a filter, this means people won't be able to install a filter if the file allocation fails for some reason, even if they subsequently should be able to. To fix this, let's hoist this free+null into its own little helper and use it. Reported-by: Kees Cook <keescook@chromium.org> Reported-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Tycho Andersen <tycho@tycho.pizza> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/r/20200902140953.1201956-1-tycho@tycho.pizza Signed-off-by: Kees Cook <keescook@chromium.org> |
|
|
Tycho Andersen
|
a566a9012a |
seccomp: don't leak memory when filter install races
In seccomp_set_mode_filter() with TSYNC | NEW_LISTENER, we first initialize
the listener fd, then check to see if we can actually use it later in
seccomp_may_assign_mode(), which can fail if anyone else in our thread
group has installed a filter and caused some divergence. If we can't, we
partially clean up the newly allocated file: we put the fd, put the file,
but don't actually clean up the *memory* that was allocated at
filter->notif. Let's clean that up too.
To accomplish this, let's hoist the actual "detach a notifier from a
filter" code to its own helper out of seccomp_notify_release(), so that in
case anyone adds stuff to init_listener(), they only have to add the
cleanup code in one spot. This does a bit of extra locking and such on the
failure path when the filter is not attached, but it's a slow failure path
anyway.
Fixes:
|
|
|
Sargun Dhillon
|
7cf97b1254 |
seccomp: Introduce addfd ioctl to seccomp user notifier
The current SECCOMP_RET_USER_NOTIF API allows for syscall supervision over an fd. It is often used in settings where a supervising task emulates syscalls on behalf of a supervised task in userspace, either to further restrict the supervisee's syscall abilities or to circumvent kernel enforced restrictions the supervisor deems safe to lift (e.g. actually performing a mount(2) for an unprivileged container). While SECCOMP_RET_USER_NOTIF allows for the interception of any syscall, only a certain subset of syscalls could be correctly emulated. Over the last few development cycles, the set of syscalls which can't be emulated has been reduced due to the addition of pidfd_getfd(2). With this we are now able to, for example, intercept syscalls that require the supervisor to operate on file descriptors of the supervisee such as connect(2). However, syscalls that cause new file descriptors to be installed can not currently be correctly emulated since there is no way for the supervisor to inject file descriptors into the supervisee. This patch adds a new addfd ioctl to remove this restriction by allowing the supervisor to install file descriptors into the intercepted task. By implementing this feature via seccomp the supervisor effectively instructs the supervisee to install a set of file descriptors into its own file descriptor table during the intercepted syscall. This way it is possible to intercept syscalls such as open() or accept(), and install (or replace, like dup2(2)) the supervisor's resulting fd into the supervisee. One replacement use-case would be to redirect the stdout and stderr of a supervisee into log file descriptors opened by the supervisor. The ioctl handling is based on the discussions[1] of how Extensible Arguments should interact with ioctls. Instead of building size into the addfd structure, make it a function of the ioctl command (which is how sizes are normally passed to ioctls). To support forward and backward compatibility, just mask out the direction and size, and match everything. The size (and any future direction) checks are done along with copy_struct_from_user() logic. As a note, the seccomp_notif_addfd structure is laid out based on 8-byte alignment without requiring packing as there have been packing issues with uapi highlighted before[2][3]. Although we could overload the newfd field and use -1 to indicate that it is not to be used, doing so requires changing the size of the fd field, and introduces struct packing complexity. [1]: https://lore.kernel.org/lkml/87o8w9bcaf.fsf@mid.deneb.enyo.de/ [2]: https://lore.kernel.org/lkml/a328b91d-fd8f-4f27-b3c2-91a9c45f18c0@rasmusvillemoes.dk/ [3]: https://lore.kernel.org/lkml/20200612104629.GA15814@ircssh-2.c.rugged-nimbus-611.internal Cc: Christoph Hellwig <hch@lst.de> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Tycho Andersen <tycho@tycho.ws> Cc: Jann Horn <jannh@google.com> Cc: Robert Sesek <rsesek@google.com> Cc: Chris Palmer <palmer@google.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-api@vger.kernel.org Suggested-by: Matt Denton <mpdenton@google.com> Link: https://lore.kernel.org/r/20200603011044.7972-4-sargun@sargun.me Signed-off-by: Sargun Dhillon <sargun@sargun.me> Reviewed-by: Will Drewry <wad@chromium.org> Co-developed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Kees Cook <keescook@chromium.org> |
|
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Kees Cook
|
fe4bfff86e |
seccomp: Use -1 marker for end of mode 1 syscall list
The terminator for the mode 1 syscalls list was a 0, but that could be a valid syscall number (e.g. x86_64 __NR_read). By luck, __NR_read was listed first and the loop construct would not test it, so there was no bug. However, this is fragile. Replace the terminator with -1 instead, and make the variable name for mode 1 syscall lists more descriptive. Cc: Andy Lutomirski <luto@amacapital.net> Cc: Will Drewry <wad@chromium.org> Signed-off-by: Kees Cook <keescook@chromium.org> |
|
|
Kees Cook
|
47e33c05f9 |
seccomp: Fix ioctl number for SECCOMP_IOCTL_NOTIF_ID_VALID
When SECCOMP_IOCTL_NOTIF_ID_VALID was first introduced it had the wrong
direction flag set. While this isn't a big deal as nothing currently
enforces these bits in the kernel, it should be defined correctly. Fix
the define and provide support for the old command until it is no longer
needed for backward compatibility.
Fixes:
|
|
|
Kees Cook
|
e68f9d49dd |
seccomp: Use pr_fmt
Avoid open-coding "seccomp: " prefixes for pr_*() calls. Signed-off-by: Kees Cook <keescook@chromium.org> |
|
Christian Brauner
|
99cdb8b9a5 |
seccomp: notify about unused filter
We've been making heavy use of the seccomp notifier to intercept and handle certain syscalls for containers. This patch allows a syscall supervisor listening on a given notifier to be notified when a seccomp filter has become unused. A container is often managed by a singleton supervisor process the so-called "monitor". This monitor process has an event loop which has various event handlers registered. If the user specified a seccomp profile that included a notifier for various syscalls then we also register a seccomp notify even handler. For any container using a separate pid namespace the lifecycle of the seccomp notifier is bound to the init process of the pid namespace, i.e. when the init process exits the filter must be unused. If a new process attaches to a container we force it to assume a seccomp profile. This can either be the same seccomp profile as the container was started with or a modified one. If the attaching process makes use of the seccomp notifier we will register a new seccomp notifier handler in the monitor's event loop. However, when the attaching process exits we can't simply delete the handler since other child processes could've been created (daemons spawned etc.) that have inherited the seccomp filter and so we need to keep the seccomp notifier fd alive in the event loop. But this is problematic since we don't get a notification when the seccomp filter has become unused and so we currently never remove the seccomp notifier fd from the event loop and just keep accumulating fds in the event loop. We've had this issue for a while but it has recently become more pressing as more and larger users make use of this. To fix this, we introduce a new "users" reference counter that tracks any tasks and dependent filters making use of a filter. When a notifier is registered waiting tasks will be notified that the filter is now empty by receiving a (E)POLLHUP event. The concept in this patch introduces is the same as for signal_struct, i.e. reference counting for life-cycle management is decoupled from reference counting taks using the object. There's probably some trickery possible but the second counter is just the correct way of doing this IMHO and has precedence. Cc: Tycho Andersen <tycho@tycho.ws> Cc: Kees Cook <keescook@chromium.org> Cc: Matt Denton <mpdenton@google.com> Cc: Sargun Dhillon <sargun@sargun.me> Cc: Jann Horn <jannh@google.com> Cc: Chris Palmer <palmer@google.com> Cc: Aleksa Sarai <cyphar@cyphar.com> Cc: Robert Sesek <rsesek@google.com> Cc: Jeffrey Vander Stoep <jeffv@google.com> Cc: Linux Containers <containers@lists.linux-foundation.org> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/r/20200531115031.391515-3-christian.brauner@ubuntu.com Signed-off-by: Kees Cook <keescook@chromium.org> |
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|
Christian Brauner
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76194c4e83 |
seccomp: Lift wait_queue into struct seccomp_filter
Lift the wait_queue from struct notification into struct seccomp_filter. This is cleaner overall and lets us avoid having to take the notifier mutex in the future for EPOLLHUP notifications since we need to neither read nor modify the notifier specific aspects of the seccomp filter. In the exit path I'd very much like to avoid having to take the notifier mutex for each filter in the task's filter hierarchy. Cc: Tycho Andersen <tycho@tycho.ws> Cc: Kees Cook <keescook@chromium.org> Cc: Matt Denton <mpdenton@google.com> Cc: Sargun Dhillon <sargun@sargun.me> Cc: Jann Horn <jannh@google.com> Cc: Chris Palmer <palmer@google.com> Cc: Aleksa Sarai <cyphar@cyphar.com> Cc: Robert Sesek <rsesek@google.com> Cc: Jeffrey Vander Stoep <jeffv@google.com> Cc: Linux Containers <containers@lists.linux-foundation.org> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Kees Cook <keescook@chromium.org> |
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Christian Brauner
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3a15fb6ed9 |
seccomp: release filter after task is fully dead
The seccomp filter used to be released in free_task() which is called asynchronously via call_rcu() and assorted mechanisms. Since we need to inform tasks waiting on the seccomp notifier when a filter goes empty we will notify them as soon as a task has been marked fully dead in release_task(). To not split seccomp cleanup into two parts, move filter release out of free_task() and into release_task() after we've unhashed struct task from struct pid, exited signals, and unlinked it from the threadgroups' thread list. We'll put the empty filter notification infrastructure into it in a follow up patch. This also renames put_seccomp_filter() to seccomp_filter_release() which is a more descriptive name of what we're doing here especially once we've added the empty filter notification mechanism in there. We're also NULL-ing the task's filter tree entrypoint which seems cleaner than leaving a dangling pointer in there. Note that this shouldn't need any memory barriers since we're calling this when the task is in release_task() which means it's EXIT_DEAD. So it can't modify its seccomp filters anymore. You can also see this from the point where we're calling seccomp_filter_release(). It's after __exit_signal() and at this point, tsk->sighand will already have been NULLed which is required for thread-sync and filter installation alike. Cc: Tycho Andersen <tycho@tycho.ws> Cc: Kees Cook <keescook@chromium.org> Cc: Matt Denton <mpdenton@google.com> Cc: Sargun Dhillon <sargun@sargun.me> Cc: Jann Horn <jannh@google.com> Cc: Chris Palmer <palmer@google.com> Cc: Aleksa Sarai <cyphar@cyphar.com> Cc: Robert Sesek <rsesek@google.com> Cc: Jeffrey Vander Stoep <jeffv@google.com> Cc: Linux Containers <containers@lists.linux-foundation.org> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/r/20200531115031.391515-2-christian.brauner@ubuntu.com Signed-off-by: Kees Cook <keescook@chromium.org> |
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Christian Brauner
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b707ddee11 |
seccomp: rename "usage" to "refs" and document
Naming the lifetime counter of a seccomp filter "usage" suggests a little too strongly that its about tasks that are using this filter while it also tracks other references such as the user notifier or ptrace. This also updates the documentation to note this fact. We'll be introducing an actual usage counter in a follow-up patch. Cc: Tycho Andersen <tycho@tycho.ws> Cc: Kees Cook <keescook@chromium.org> Cc: Matt Denton <mpdenton@google.com> Cc: Sargun Dhillon <sargun@sargun.me> Cc: Jann Horn <jannh@google.com> Cc: Chris Palmer <palmer@google.com> Cc: Aleksa Sarai <cyphar@cyphar.com> Cc: Robert Sesek <rsesek@google.com> Cc: Jeffrey Vander Stoep <jeffv@google.com> Cc: Linux Containers <containers@lists.linux-foundation.org> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/r/20200531115031.391515-1-christian.brauner@ubuntu.com Signed-off-by: Kees Cook <keescook@chromium.org> |
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Sargun Dhillon
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9f87dcf14b |
seccomp: Add find_notification helper
This adds a helper which can iterate through a seccomp_filter to find a notification matching an ID. It removes several replicated chunks of code. Signed-off-by: Sargun Dhillon <sargun@sargun.me> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Reviewed-by: Tycho Andersen <tycho@tycho.ws> Cc: Matt Denton <mpdenton@google.com> Cc: Kees Cook <keescook@google.com>, Cc: Jann Horn <jannh@google.com>, Cc: Robert Sesek <rsesek@google.com>, Cc: Chris Palmer <palmer@google.com> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Tycho Andersen <tycho@tycho.ws> Link: https://lore.kernel.org/r/20200601112532.150158-1-sargun@sargun.me Signed-off-by: Kees Cook <keescook@chromium.org> |
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Kees Cook
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c818c03b66 |
seccomp: Report number of loaded filters in /proc/$pid/status
A common question asked when debugging seccomp filters is "how many filters are attached to your process?" Provide a way to easily answer this question through /proc/$pid/status with a "Seccomp_filters" line. Signed-off-by: Kees Cook <keescook@chromium.org> |
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Christoph Hellwig
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32927393dc |
sysctl: pass kernel pointers to ->proc_handler
Instead of having all the sysctl handlers deal with user pointers, which is rather hairy in terms of the BPF interaction, copy the input to and from userspace in common code. This also means that the strings are always NUL-terminated by the common code, making the API a little bit safer. As most handler just pass through the data to one of the common handlers a lot of the changes are mechnical. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> |
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Linus Torvalds
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29d9f30d4c |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from David Miller:
"Highlights:
1) Fix the iwlwifi regression, from Johannes Berg.
2) Support BSS coloring and 802.11 encapsulation offloading in
hardware, from John Crispin.
3) Fix some potential Spectre issues in qtnfmac, from Sergey
Matyukevich.
4) Add TTL decrement action to openvswitch, from Matteo Croce.
5) Allow paralleization through flow_action setup by not taking the
RTNL mutex, from Vlad Buslov.
6) A lot of zero-length array to flexible-array conversions, from
Gustavo A. R. Silva.
7) Align XDP statistics names across several drivers for consistency,
from Lorenzo Bianconi.
8) Add various pieces of infrastructure for offloading conntrack, and
make use of it in mlx5 driver, from Paul Blakey.
9) Allow using listening sockets in BPF sockmap, from Jakub Sitnicki.
10) Lots of parallelization improvements during configuration changes
in mlxsw driver, from Ido Schimmel.
11) Add support to devlink for generic packet traps, which report
packets dropped during ACL processing. And use them in mlxsw
driver. From Jiri Pirko.
12) Support bcmgenet on ACPI, from Jeremy Linton.
13) Make BPF compatible with RT, from Thomas Gleixnet, Alexei
Starovoitov, and your's truly.
14) Support XDP meta-data in virtio_net, from Yuya Kusakabe.
15) Fix sysfs permissions when network devices change namespaces, from
Christian Brauner.
16) Add a flags element to ethtool_ops so that drivers can more simply
indicate which coalescing parameters they actually support, and
therefore the generic layer can validate the user's ethtool
request. Use this in all drivers, from Jakub Kicinski.
17) Offload FIFO qdisc in mlxsw, from Petr Machata.
18) Support UDP sockets in sockmap, from Lorenz Bauer.
19) Fix stretch ACK bugs in several TCP congestion control modules,
from Pengcheng Yang.
20) Support virtual functiosn in octeontx2 driver, from Tomasz
Duszynski.
21) Add region operations for devlink and use it in ice driver to dump
NVM contents, from Jacob Keller.
22) Add support for hw offload of MACSEC, from Antoine Tenart.
23) Add support for BPF programs that can be attached to LSM hooks,
from KP Singh.
24) Support for multiple paths, path managers, and counters in MPTCP.
From Peter Krystad, Paolo Abeni, Florian Westphal, Davide Caratti,
and others.
25) More progress on adding the netlink interface to ethtool, from
Michal Kubecek"
* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2121 commits)
net: ipv6: rpl_iptunnel: Fix potential memory leak in rpl_do_srh_inline
cxgb4/chcr: nic-tls stats in ethtool
net: dsa: fix oops while probing Marvell DSA switches
net/bpfilter: remove superfluous testing message
net: macb: Fix handling of fixed-link node
net: dsa: ksz: Select KSZ protocol tag
netdevsim: dev: Fix memory leak in nsim_dev_take_snapshot_write
net: stmmac: add EHL 2.5Gbps PCI info and PCI ID
net: stmmac: add EHL PSE0 & PSE1 1Gbps PCI info and PCI ID
net: stmmac: create dwmac-intel.c to contain all Intel platform
net: dsa: bcm_sf2: Support specifying VLAN tag egress rule
net: dsa: bcm_sf2: Add support for matching VLAN TCI
net: dsa: bcm_sf2: Move writing of CFP_DATA(5) into slicing functions
net: dsa: bcm_sf2: Check earlier for FLOW_EXT and FLOW_MAC_EXT
net: dsa: bcm_sf2: Disable learning for ASP port
net: dsa: b53: Deny enslaving port 7 for 7278 into a bridge
net: dsa: b53: Prevent tagged VLAN on port 7 for 7278
net: dsa: b53: Restore VLAN entries upon (re)configuration
net: dsa: bcm_sf2: Fix overflow checks
hv_netvsc: Remove unnecessary round_up for recv_completion_cnt
...
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Sven Schnelle
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3db81afd99 |
seccomp: Add missing compat_ioctl for notify
Executing the seccomp_bpf testsuite under a 64-bit kernel with 32-bit
userland (both s390 and x86) doesn't work because there's no compat_ioctl
handler defined. Add the handler.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Fixes:
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Tycho Andersen
|
51891498f2 |
seccomp: allow TSYNC and USER_NOTIF together
The restriction introduced in
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David Miller
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3d9f773cf2 |
bpf: Use bpf_prog_run_pin_on_cpu() at simple call sites.
All of these cases are strictly of the form: preempt_disable(); BPF_PROG_RUN(...); preempt_enable(); Replace this with bpf_prog_run_pin_on_cpu() which wraps BPF_PROG_RUN() with: migrate_disable(); BPF_PROG_RUN(...); migrate_enable(); On non RT enabled kernels this maps to preempt_disable/enable() and on RT enabled kernels this solely prevents migration, which is sufficient as there is no requirement to prevent reentrancy to any BPF program from a preempting task. The only requirement is that the program stays on the same CPU. Therefore, this is a trivially correct transformation. The seccomp loop does not need protection over the loop. It only needs protection per BPF filter program [ tglx: Converted to bpf_prog_run_pin_on_cpu() ] Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145643.691493094@linutronix.de |
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Sargun Dhillon
|
2882d53c9c |
seccomp: Check that seccomp_notif is zeroed out by the user
This patch is a small change in enforcement of the uapi for
SECCOMP_IOCTL_NOTIF_RECV ioctl. Specifically, the datastructure which
is passed (seccomp_notif) must be zeroed out. Previously any of its
members could be set to nonsense values, and we would ignore it.
This ensures all fields are set to their zero value.
Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: Aleksa Sarai <cyphar@cyphar.com>
Acked-by: Tycho Andersen <tycho@tycho.ws>
Link: https://lore.kernel.org/r/20191229062451.9467-2-sargun@sargun.me
Fixes:
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Christian Brauner
|
fb3c5386b3 |
seccomp: add SECCOMP_USER_NOTIF_FLAG_CONTINUE
This allows the seccomp notifier to continue a syscall. A positive
discussion about this feature was triggered by a post to the
ksummit-discuss mailing list (cf. [3]) and took place during KSummit
(cf. [1]) and again at the containers/checkpoint-restore
micro-conference at Linux Plumbers.
Recently we landed seccomp support for SECCOMP_RET_USER_NOTIF (cf. [4])
which enables a process (watchee) to retrieve an fd for its seccomp
filter. This fd can then be handed to another (usually more privileged)
process (watcher). The watcher will then be able to receive seccomp
messages about the syscalls having been performed by the watchee.
This feature is heavily used in some userspace workloads. For example,
it is currently used to intercept mknod() syscalls in user namespaces
aka in containers.
The mknod() syscall can be easily filtered based on dev_t. This allows
us to only intercept a very specific subset of mknod() syscalls.
Furthermore, mknod() is not possible in user namespaces toto coelo and
so intercepting and denying syscalls that are not in the whitelist on
accident is not a big deal. The watchee won't notice a difference.
In contrast to mknod(), a lot of other syscall we intercept (e.g.
setxattr()) cannot be easily filtered like mknod() because they have
pointer arguments. Additionally, some of them might actually succeed in
user namespaces (e.g. setxattr() for all "user.*" xattrs). Since we
currently cannot tell seccomp to continue from a user notifier we are
stuck with performing all of the syscalls in lieu of the container. This
is a huge security liability since it is extremely difficult to
correctly assume all of the necessary privileges of the calling task
such that the syscall can be successfully emulated without escaping
other additional security restrictions (think missing CAP_MKNOD for
mknod(), or MS_NODEV on a filesystem etc.). This can be solved by
telling seccomp to resume the syscall.
One thing that came up in the discussion was the problem that another
thread could change the memory after userspace has decided to let the
syscall continue which is a well known TOCTOU with seccomp which is
present in other ways already.
The discussion showed that this feature is already very useful for any
syscall without pointer arguments. For any accidentally intercepted
non-pointer syscall it is safe to continue.
For syscalls with pointer arguments there is a race but for any cautious
userspace and the main usec cases the race doesn't matter. The notifier
is intended to be used in a scenario where a more privileged watcher
supervises the syscalls of lesser privileged watchee to allow it to get
around kernel-enforced limitations by performing the syscall for it
whenever deemed save by the watcher. Hence, if a user tricks the watcher
into allowing a syscall they will either get a deny based on
kernel-enforced restrictions later or they will have changed the
arguments in such a way that they manage to perform a syscall with
arguments that they would've been allowed to do anyway.
In general, it is good to point out again, that the notifier fd was not
intended to allow userspace to implement a security policy but rather to
work around kernel security mechanisms in cases where the watcher knows
that a given action is safe to perform.
/* References */
[1]: https://linuxplumbersconf.org/event/4/contributions/560
[2]: https://linuxplumbersconf.org/event/4/contributions/477
[3]: https://lore.kernel.org/r/20190719093538.dhyopljyr5ns33qx@brauner.io
[4]: commit
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Eric W. Biederman
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a89e9b8abf |
signal: Remove the signal number and task parameters from force_sig_info
force_sig_info always delivers to the current task and the signal parameter always matches info.si_signo. So remove those parameters to make it a simpler less error prone interface, and to make it clear that none of the callers are doing anything clever. This guarantees that force_sig_info will not grow any new buggy callers that attempt to call force_sig on a non-current task, or that pass an signal number that does not match info.si_signo. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> |
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Linus Torvalds
|
02aff8db64 |
audit/stable-5.2 PR 20190507
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Merge tag 'audit-pr-20190507' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit
Pull audit updates from Paul Moore:
"We've got a reasonably broad set of audit patches for the v5.2 merge
window, the highlights are below:
- The biggest change, and the source of all the arch/* changes, is
the patchset from Dmitry to help enable some of the work he is
doing around PTRACE_GET_SYSCALL_INFO.
To be honest, including this in the audit tree is a bit of a
stretch, but it does help move audit a little further along towards
proper syscall auditing for all arches, and everyone else seemed to
agree that audit was a "good" spot for this to land (or maybe they
just didn't want to merge it? dunno.).
- We can now audit time/NTP adjustments.
- We continue the work to connect associated audit records into a
single event"
* tag 'audit-pr-20190507' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit: (21 commits)
audit: fix a memory leak bug
ntp: Audit NTP parameters adjustment
timekeeping: Audit clock adjustments
audit: purge unnecessary list_empty calls
audit: link integrity evm_write_xattrs record to syscall event
syscall_get_arch: add "struct task_struct *" argument
unicore32: define syscall_get_arch()
Move EM_UNICORE to uapi/linux/elf-em.h
nios2: define syscall_get_arch()
nds32: define syscall_get_arch()
Move EM_NDS32 to uapi/linux/elf-em.h
m68k: define syscall_get_arch()
hexagon: define syscall_get_arch()
Move EM_HEXAGON to uapi/linux/elf-em.h
h8300: define syscall_get_arch()
c6x: define syscall_get_arch()
arc: define syscall_get_arch()
Move EM_ARCOMPACT and EM_ARCV2 to uapi/linux/elf-em.h
audit: Make audit_log_cap and audit_copy_inode static
audit: connect LOGIN record to its syscall record
...
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Linus Torvalds
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78ee8b1b9b |
Merge branch 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull security subsystem updates from James Morris:
"Just a few bugfixes and documentation updates"
* 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
seccomp: fix up grammar in comment
Revert "security: inode: fix a missing check for securityfs_create_file"
Yama: mark function as static
security: inode: fix a missing check for securityfs_create_file
keys: safe concurrent user->{session,uid}_keyring access
security: don't use RCU accessors for cred->session_keyring
Yama: mark local symbols as static
LSM: lsm_hooks.h: fix documentation format
LSM: fix documentation for the shm_* hooks
LSM: fix documentation for the sem_* hooks
LSM: fix documentation for the msg_queue_* hooks
LSM: fix documentation for the audit_* hooks
LSM: fix documentation for the path_chmod hook
LSM: fix documentation for the socket_getpeersec_dgram hook
LSM: fix documentation for the task_setscheduler hook
LSM: fix documentation for the socket_post_create hook
LSM: fix documentation for the syslog hook
LSM: fix documentation for sb_copy_data hook
|