linux-stable.git/kernel/audit_fsnotify.c, branch v6.6.154

audit: fix recursive locking deadlock in audit_dupe_exe()

2026-08-03T09:15:34+00:00

[ Upstream commit 81905b5acbe77284734438df3fbec1158e6429a3 ]

A deadlock occurs in the audit subsystem when duplicating
executable-related rules.

When a file is moved (e.g., via do_renameat2()), the VFS layer locks
the parent directory (I_MUTEX_PARENT), which synchronously triggers an
fsnotify_move event. If an existing executable audit rule matches the
file being moved, the audit subsystem catches this event and calls
audit_dupe_exe() to duplicate the watch and update the rule. Then,
audit_alloc_mark() would call kern_path_parent() to resolve the path,
leading to a blind attempt to acquire the exact same I_MUTEX_PARENT lock
already held by the task, resulting in the following recursive locking
deadlock:

 ============================================
 WARNING: possible recursive locking detected
 6.12.0-55.27.1.el10_0.x86_64+debug #1 Not tainted
 --------------------------------------------
 mv/5099 is trying to acquire lock:
 ffff888132845358 (&inode->i_sb->s_type->i_mutex_dir_key/1){+.+.}-{3:3},
 at: __kern_path_locked+0x10a/0x2f0

 but task is already holding lock:
 ffff888132846b58 (&inode->i_sb->s_type->i_mutex_dir_key/1){+.+.}-{3:3},
 at: lock_two_directories+0x13f/0x2b0

 other info that might help us debug this:
  Possible unsafe locking scenario:

        CPU0
        ----
   lock(&inode->i_sb->s_type->i_mutex_dir_key/1);
   lock(&inode->i_sb->s_type->i_mutex_dir_key/1);

  *** DEADLOCK ***

  May be due to missing lock nesting notation

  6 locks held by mv/5099:
  #0: ffff888112a9c440 (sb_writers#13)
  at: do_renameat2+0x34c/0xbc0
  #1: ffff888112a9c790 (&type->s_vfs_rename_key#3)
  at: do_renameat2+0x415/0xbc0
  #2: ffff888132846b58 (&inode->i_sb->s_type->i_mutex_dir_key/1)
  at: lock_two_directories+0x13f/0x2b0
  #3: ffff888132845358 (&inode->i_sb->s_type->i_mutex_dir_key/5)
  at: lock_two_directories+0x175/0x2b0
  #4: ffffffffb3a1fb10 (&fsnotify_mark_srcu)
  at: fsnotify+0x454/0x28a0
  #5: ffffffffaf886230 (audit_filter_mutex)
  at: audit_update_watch+0x36/0x11e0

 stack backtrace:
 Call Trace:
  
  dump_stack_lvl+0x6f/0xb0
  print_deadlock_bug.cold+0xbd/0xca
  validate_chain+0x83a/0xf00
  __lock_acquire+0xcac/0x1d20
  lock_acquire.part.0+0x11b/0x360
  down_write_nested+0x9f/0x230
  __kern_path_locked+0x10a/0x2f0
  kern_path_locked+0x26/0x40
  audit_alloc_mark+0xfb/0x4f0
  audit_dupe_exe+0x6c/0xe0
  audit_dupe_rule+0x6c2/0xc00
  audit_update_watch+0x4cc/0x11e0
  audit_watch_handle_event+0x12c/0x1b0
  send_to_group+0x5d0/0x8b0
  fsnotify+0x615/0x28a0
  fsnotify_move+0x1d8/0x630
  vfs_rename+0xdcd/0x1df0
  do_renameat2+0x9d4/0xbc0
  __x64_sys_renameat+0x192/0x260
  do_syscall_64+0x92/0x180
  entry_SYSCALL_64_after_hwframe+0x76/0x7e
 RIP: 0033:0x7f0491fe8c4e
 Code: 0f 1f 40 00 48 8b 15 c1 e1 16 00 f7 d8 64 89 02 b8 ff ff ff ff
 c3 66 0f 1f 44 00 00 f3 0f 1e fa 49 89 ca b8 08 01 00 00 0f 05 <48>
 3d 00 f0 ff ff 77 0a c3 66 0f 1f 84 00 00 00 00 00 48 8b 15 89
 RSP: 002b:00007ffc7210bf38 EFLAGS: 00000246 ORIG_RAX: 0000000000000108
 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f0491fe8c4e
 RDX: 0000000000000003 RSI: 00007ffc7210e6c8 RDI: 00000000ffffff9c
 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001
 R10: 00005575eb2dae2a R11: 0000000000000246 R12: 00005575eb2dae2a
 R13: 00007ffc7210e6c8 R14: 0000000000000003 R15: 00000000ffffff9c
  

The aforementioned deadlock can be consistently reproduced by running
the script below:

 audit-dupe-exe-deadlock.sh
 --------------------------
 #!/bin/bash
 auditctl -D
 mkdir -p /tmp/foo
 touch /tmp/file
 auditctl -a always,exit -F exe=/tmp/file -F path=/tmp/file -S all -k dr
 mv /tmp/file /tmp/foo/file
 rm -Rf /tmp/foo

This patch fixes the issue by introducing struct audit_watch_ctx to pass
the fsnotify event context down to audit_alloc_mark(). By utilizing the
already-resolved directory inode provided by the event, we bypass the
kern_path_parent() path resolution entirely, safely avoiding the
recursive lock. Furthermore, it explicitly allows duplicate fsnotify
marks (allow_dups = 1) during the rename update, allowing the new rule's
mark to safely coexist with the old rule's mark until the old rule is
freed.

P.S.: This issue was identified and reproduced during a comprehensive
code coverage analysis of the audit subsystem. The full report is
available at the link below:

https://people.redhat.com/rrobaina/audit-code-coverage-analysis.pdf

P.P.S: With the permission of both Ricardo and Nathan, I've squashed a
fixup patch from Nathan that addresses a compile time error when
CONFIG_AUDITSYSCALL=n.

Cc: stable@kernel.org
Fixes: 34d99af52ad4 ("audit: implement audit by executable")
Acked-by: Waiman Long 
Acked-by: Richard Guy Briggs 
Signed-off-by: Nathan Chancellor 
Signed-off-by: Ricardo Robaina 
[PM: move link metadata into the msg, apply fix from NC]
Signed-off-by: Paul Moore 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

audit: widen ino fields to u64

2026-08-03T09:15:33+00:00

[ Upstream commit 125dfa218134df7cc112667e92984de9d8cd0bf6 ]

inode->i_ino is being widened from unsigned long to u64. The audit
subsystem uses unsigned long ino in struct fields, function parameters,
and local variables that store inode numbers from arbitrary filesystems.
On 32-bit platforms this truncates inode numbers that exceed 32 bits,
which will cause incorrect audit log entries and broken watch/mark
comparisons.

Widen all audit ino fields, parameters, and locals to u64, and update
the inode format string from %lu to %llu to match.

Signed-off-by: Jeff Layton 
Link: https://patch.msgid.link/20260304-iino-u64-v3-2-2257ad83d372@kernel.org
Acked-by: Paul Moore 
Signed-off-by: Christian Brauner 
Stable-dep-of: 81905b5acbe7 ("audit: fix recursive locking deadlock in audit_dupe_exe()")
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

VFS/audit: introduce kern_path_parent() for audit

2026-08-03T09:15:33+00:00

[ Upstream commit 76a53de6f7ff0641570364234fb4489f4d4fc8e9 ]

audit_alloc_mark() and audit_get_nd() both need to perform a path
lookup getting the parent dentry (which must exist) and the final
target (following a LAST_NORM name) which sometimes doesn't need to
exist.

They don't need the parent to be locked, but use kern_path_locked() or
kern_path_locked_negative() anyway.  This is somewhat misleading to the
casual reader.

This patch introduces a more targeted function, kern_path_parent(),
which returns not holding locks.  On success the "path" will
be set to the parent, which must be found, and the return value is the
dentry of the target, which might be negative.

This will clear the way to rename kern_path_locked() which is
otherwise only used to prepare for removing something.

It also allows us to remove kern_path_locked_negative(), which is
transformed into the new kern_path_parent().

Signed-off-by: NeilBrown 
Signed-off-by: Christian Brauner 
Stable-dep-of: 81905b5acbe7 ("audit: fix recursive locking deadlock in audit_dupe_exe()")
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

audit: fix potential double free on error path from fsnotify_add_inode_mark

2022-08-22T22:50:06+00:00

Audit_alloc_mark() assign pathname to audit_mark->path, on error path
from fsnotify_add_inode_mark(), fsnotify_put_mark will free memory
of audit_mark->path, but the caller of audit_alloc_mark will free
the pathname again, so there will be double free problem.

Fix this by resetting audit_mark->path to NULL pointer on error path
from fsnotify_add_inode_mark().

Cc: stable@vger.kernel.org
Fixes: 7b1293234084d ("fsnotify: Add group pointer in fsnotify_init_mark()")
Signed-off-by: Gaosheng Cui 
Reviewed-by: Jan Kara 
Signed-off-by: Paul Moore

fsnotify: make allow_dups a property of the group

2022-04-25T12:37:18+00:00

Instead of passing the allow_dups argument to fsnotify_add_mark()
as an argument, define the group flag FSNOTIFY_GROUP_DUPS to express
the allow_dups behavior and set this behavior at group creation time
for all calls of fsnotify_add_mark().

Rename the allow_dups argument to generic add_flags argument for future
use.

Link: https://lore.kernel.org/r/20220422120327.3459282-6-amir73il@gmail.com
Suggested-by: Jan Kara 
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: pass flags argument to fsnotify_alloc_group()

2022-04-25T12:37:12+00:00

Add flags argument to fsnotify_alloc_group(), define and use the flag
FSNOTIFY_GROUP_USER in inotify and fanotify instead of the helper
fsnotify_alloc_user_group() to indicate user allocation.

Although the flag FSNOTIFY_GROUP_USER is currently not used after group
allocation, we store the flags argument in the group struct for future
use of other group flags.

Link: https://lore.kernel.org/r/20220422120327.3459282-5-amir73il@gmail.com
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: clarify contract for create event hooks

2021-10-27T10:32:34+00:00

Clarify argument names and contract for fsnotify_create() and
fsnotify_mkdir() to reflect the anomaly of kernfs, which leaves dentries
negavite after mkdir/create.

Remove the WARN_ON(!inode) in audit code that were added by the Fixes
commit under the wrong assumption that dentries cannot be negative after
mkdir/create.

Fixes: aa93bdc5500c ("fsnotify: use helpers to access data by data_type")
Link: https://lore.kernel.org/linux-fsdevel/87mtp5yz0q.fsf@collabora.com/
Link: https://lore.kernel.org/r/20211025192746.66445-4-krisman@collabora.com
Reviewed-by: Jan Kara 
Reported-by: Gabriel Krisman Bertazi 
Signed-off-by: Amir Goldstein 
Signed-off-by: Gabriel Krisman Bertazi 
Signed-off-by: Jan Kara

audit_alloc_mark(): don't open-code ERR_CAST()

2021-02-23T15:25:27+00:00

Signed-off-by: Al Viro

fsnotify: generalize handle_inode_event()

2020-12-03T13:58:35+00:00

The handle_inode_event() interface was added as (quoting comment):
"a simple variant of handle_event() for groups that only have inode
marks and don't have ignore mask".

In other words, all backends except fanotify.  The inotify backend
also falls under this category, but because it required extra arguments
it was left out of the initial pass of backends conversion to the
simple interface.

This results in code duplication between the generic helper
fsnotify_handle_event() and the inotify_handle_event() callback
which also happen to be buggy code.

Generalize the handle_inode_event() arguments and add the check for
FS_EXCL_UNLINK flag to the generic helper, so inotify backend could
be converted to use the simple interface.

Link: https://lore.kernel.org/r/20201202120713.702387-2-amir73il@gmail.com
CC: stable@vger.kernel.org
Fixes: b9a1b9772509 ("fsnotify: create method handle_inode_event() in fsnotify_operations")
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara

fsnotify: create method handle_inode_event() in fsnotify_operations

2020-07-27T21:25:50+00:00

The method handle_event() grew a lot of complexity due to the design of
fanotify and merging of ignore masks.

Most backends do not care about this complex functionality, so we can hide
this complexity from them.

Introduce a method handle_inode_event() that serves those backends and
passes a single inode mark and less arguments.

This change converts all backends except fanotify and inotify to use the
simplified handle_inode_event() method.  In pricipal, inotify could have
also used the new method, but that would require passing more arguments
on the simple helper (data, data_type, cookie), so we leave it with the
handle_event() method.

Link: https://lore.kernel.org/r/20200722125849.17418-9-amir73il@gmail.com
Suggested-by: Jan Kara 
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara