bpf-fixes

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Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Pull bpf fixes from Alexei Starovoitov:

 - Finish constification of 1st parameter of bpf_d_path() (Rong Tao)

 - Harden userspace-supplied xdp_desc validation (Alexander Lobakin)

 - Fix metadata_dst leak in __bpf_redirect_neigh_v{4,6}() (Daniel
   Borkmann)

 - Fix undefined behavior in {get,put}_unaligned_be32() (Eric Biggers)

 - Use correct context to unpin bpf hash map with special types (KaFai
   Wan)

* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  selftests/bpf: Add test for unpinning htab with internal timer struct
  bpf: Avoid RCU context warning when unpinning htab with internal structs
  xsk: Harden userspace-supplied xdp_desc validation
  bpf: Fix metadata_dst leak __bpf_redirect_neigh_v{4,6}
  libbpf: Fix undefined behavior in {get,put}_unaligned_be32()
  bpf: Finish constification of 1st parameter of bpf_d_path()

include/uapi/linux/bpf.h

@@ -4891,7 +4891,7 @@ union bpf_attr {
  *
  *		**-ENOENT** if the bpf_local_storage cannot be found.
  *
- * long bpf_d_path(struct path *path, char *buf, u32 sz)
+ * long bpf_d_path(const struct path *path, char *buf, u32 sz)
  *	Description
  *		Return full path for given **struct path** object, which
  *		needs to be the kernel BTF *path* object. The path is

kernel/bpf/inode.c

@@ -775,7 +775,7 @@ static int bpf_show_options(struct seq_file *m, struct dentry *root)
 	return 0;
 }
 
-static void bpf_free_inode(struct inode *inode)
+static void bpf_destroy_inode(struct inode *inode)
 {
 	enum bpf_type type;
 
@@ -790,7 +790,7 @@ const struct super_operations bpf_super_ops = {
 	.statfs		= simple_statfs,
 	.drop_inode	= inode_just_drop,
 	.show_options	= bpf_show_options,
-	.free_inode	= bpf_free_inode,
+	.destroy_inode	= bpf_destroy_inode,
 };
 
 enum {

net/core/filter.c

@@ -2281,6 +2281,7 @@ static int __bpf_redirect_neigh_v6(struct sk_buff *skb, struct net_device *dev,
 		if (IS_ERR(dst))
 			goto out_drop;
 
+		skb_dst_drop(skb);
 		skb_dst_set(skb, dst);
 	} else if (nh->nh_family != AF_INET6) {
 		goto out_drop;
@@ -2389,6 +2390,7 @@ static int __bpf_redirect_neigh_v4(struct sk_buff *skb, struct net_device *dev,
 			goto out_drop;
 		}
 
+		skb_dst_drop(skb);
 		skb_dst_set(skb, &rt->dst);
 	}
 

net/xdp/xsk_queue.h

@@ -143,14 +143,24 @@ static inline bool xp_unused_options_set(u32 options)
 static inline bool xp_aligned_validate_desc(struct xsk_buff_pool *pool,
 					    struct xdp_desc *desc)
 {
-	u64 addr = desc->addr - pool->tx_metadata_len;
+	u64 len = desc->len;
-	u64 len = desc->len + pool->tx_metadata_len;
+	u64 addr, offset;
-	u64 offset = addr & (pool->chunk_size - 1);
 
-	if (!desc->len)
+	if (!len)
 		return false;
 
-	if (offset + len > pool->chunk_size)
+	/* Can overflow if desc->addr < pool->tx_metadata_len */
+	if (check_sub_overflow(desc->addr, pool->tx_metadata_len, &addr))
+		return false;
+
+	offset = addr & (pool->chunk_size - 1);
+
+	/*
+	 * Can't overflow: @offset is guaranteed to be < ``U32_MAX``
+	 * (pool->chunk_size is ``u32``), @len is guaranteed
+	 * to be <= ``U32_MAX``.
+	 */
+	if (offset + len + pool->tx_metadata_len > pool->chunk_size)
 		return false;
 
 	if (addr >= pool->addrs_cnt)
@@ -158,27 +168,42 @@ static inline bool xp_aligned_validate_desc(struct xsk_buff_pool *pool,
 
 	if (xp_unused_options_set(desc->options))
 		return false;
+
 	return true;
 }
 
 static inline bool xp_unaligned_validate_desc(struct xsk_buff_pool *pool,
 					      struct xdp_desc *desc)
 {
-	u64 addr = xp_unaligned_add_offset_to_addr(desc->addr) - pool->tx_metadata_len;
+	u64 len = desc->len;
-	u64 len = desc->len + pool->tx_metadata_len;
+	u64 addr, end;
 
-	if (!desc->len)
+	if (!len)
 		return false;
 
+	/* Can't overflow: @len is guaranteed to be <= ``U32_MAX`` */
+	len += pool->tx_metadata_len;
 	if (len > pool->chunk_size)
 		return false;
 
-	if (addr >= pool->addrs_cnt || addr + len > pool->addrs_cnt ||
+	/* Can overflow if desc->addr is close to 0 */
-	    xp_desc_crosses_non_contig_pg(pool, addr, len))
+	if (check_sub_overflow(xp_unaligned_add_offset_to_addr(desc->addr),
+			       pool->tx_metadata_len, &addr))
+		return false;
+
+	if (addr >= pool->addrs_cnt)
+		return false;
+
+	/* Can overflow if pool->addrs_cnt is high enough */
+	if (check_add_overflow(addr, len, &end) || end > pool->addrs_cnt)
+		return false;
+
+	if (xp_desc_crosses_non_contig_pg(pool, addr, len))
 		return false;
 
 	if (xp_unused_options_set(desc->options))
 		return false;
+
 	return true;
 }
 

scripts/bpf_doc.py

@@ -788,6 +788,7 @@ class PrinterHelpersHeader(Printer):
             'struct task_struct',
             'struct cgroup',
             'struct path',
+            'const struct path',
             'struct btf_ptr',
             'struct inode',
             'struct socket',

tools/include/uapi/linux/bpf.h

@@ -4891,7 +4891,7 @@ union bpf_attr {
  *
  *		**-ENOENT** if the bpf_local_storage cannot be found.
  *
- * long bpf_d_path(struct path *path, char *buf, u32 sz)
+ * long bpf_d_path(const struct path *path, char *buf, u32 sz)
  *	Description
  *		Return full path for given **struct path** object, which
  *		needs to be the kernel BTF *path* object. The path is

tools/lib/bpf/libbpf_utils.c

@@ -148,16 +148,20 @@ const char *libbpf_errstr(int err)
 	}
 }
 
-#pragma GCC diagnostic push
+static inline __u32 get_unaligned_be32(const void *p)
-#pragma GCC diagnostic ignored "-Wpacked"
+{
-#pragma GCC diagnostic ignored "-Wattributes"
+	__be32 val;
-struct __packed_u32 { __u32 __val; } __attribute__((packed));
-#pragma GCC diagnostic pop
 
-#define get_unaligned_be32(p) be32_to_cpu((((struct __packed_u32 *)(p))->__val))
+	memcpy(&val, p, sizeof(val));
-#define put_unaligned_be32(v, p) do {							\
+	return be32_to_cpu(val);
-	((struct __packed_u32 *)(p))->__val = cpu_to_be32(v);				\
+}
-} while (0)
+
+static inline void put_unaligned_be32(__u32 val, void *p)
+{
+	__be32 be_val = cpu_to_be32(val);
+
+	memcpy(p, &be_val, sizeof(be_val));
+}
 
 #define SHA256_BLOCK_LENGTH 64
 #define Ch(x, y, z) (((x) & (y)) ^ (~(x) & (z)))

tools/testing/selftests/bpf/prog_tests/pinning_htab.c

@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include "test_pinning_htab.skel.h"
+
+static void unpin_map(const char *map_name, const char *pin_path)
+{
+	struct test_pinning_htab *skel;
+	struct bpf_map *map;
+	int err;
+
+	skel = test_pinning_htab__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel open_and_load"))
+		return;
+
+	map = bpf_object__find_map_by_name(skel->obj, map_name);
+	if (!ASSERT_OK_PTR(map, "bpf_object__find_map_by_name"))
+		goto out;
+
+	err = bpf_map__pin(map, pin_path);
+	if (!ASSERT_OK(err, "bpf_map__pin"))
+		goto out;
+
+	err = bpf_map__unpin(map, pin_path);
+	ASSERT_OK(err, "bpf_map__unpin");
+out:
+	test_pinning_htab__destroy(skel);
+}
+
+void test_pinning_htab(void)
+{
+	if (test__start_subtest("timer_prealloc"))
+		unpin_map("timer_prealloc", "/sys/fs/bpf/timer_prealloc");
+	if (test__start_subtest("timer_no_prealloc"))
+		unpin_map("timer_no_prealloc", "/sys/fs/bpf/timer_no_prealloc");
+}

tools/testing/selftests/bpf/progs/test_pinning_htab.c

@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+
+char _license[] SEC("license") = "GPL";
+
+struct timer_val {
+	struct bpf_timer timer;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__type(key, __u32);
+	__type(value, struct timer_val);
+	__uint(max_entries, 1);
+} timer_prealloc SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__type(key, __u32);
+	__type(value, struct timer_val);
+	__uint(max_entries, 1);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+} timer_no_prealloc SEC(".maps");

tools/testing/selftests/bpf/progs/verifier_vfs_accept.c

@@ -70,7 +70,7 @@ __success
 int BPF_PROG(path_d_path_from_file_argument, struct file *file)
 {
 	int ret;
-	struct path *path;
+	const struct path *path;
 
 	/* The f_path member is a path which is embedded directly within a
 	 * file. Therefore, a pointer to such embedded members are still