linux.git/kernel/audit_watch.c, branch v6.18.21

VFS/audit: introduce kern_path_parent() for audit

2025-09-23T10:37:35+00:00

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

fs: add kern_path_locked_negative()

2025-04-15T09:32:34+00:00

The audit code relies on the fact that kern_path_locked() returned a
path even for a negative dentry. If it doesn't find a valid dentry it
immediately calls:

    audit_find_parent(d_backing_inode(parent_path.dentry));

which assumes that parent_path.dentry is still valid. But it isn't since
kern_path_locked() has been changed to path_put() also for a negative
dentry.

Fix this by adding a helper that implements the required audit semantics
and allows us to fix the immediate bleeding. We can find a unified
solution for this afterwards.

Link: https://lore.kernel.org/20250414-rennt-wimmeln-f186c3a780f1@brauner
Fixes: 1c3cb50b58c3 ("VFS: change kern_path_locked() and user_path_locked_at() to never return negative dentry")
Reported-and-tested-by: Vlastimil Babka 
Signed-off-by: Christian Brauner

VFS: change kern_path_locked() and user_path_locked_at() to never return negative dentry

2025-02-19T13:08:41+00:00

No callers of kern_path_locked() or user_path_locked_at() want a
negative dentry.  So change them to return -ENOENT instead.  This
simplifies callers.

This results in a subtle change to bcachefs in that an ioctl will now
return -ENOENT in preference to -EXDEV.  I believe this restores the
behaviour to what it was prior to
 Commit bbe6a7c899e7 ("bch2_ioctl_subvolume_destroy(): fix locking")

Signed-off-by: NeilBrown 
Link: https://lore.kernel.org/r/20250217003020.3170652-2-neilb@suse.de
Acked-by: Paul Moore 
Reviewed-by: Jeff Layton 
Signed-off-by: Christian Brauner

fsnotify: create a wrapper fsnotify_find_inode_mark()

2024-04-04T14:24:16+00:00

In preparation to passing an object pointer to fsnotify_find_mark(), add
a wrapper fsnotify_find_inode_mark() and use it where possible.

Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara 
Message-Id: <20240317184154.1200192-4-amir73il@gmail.com>

audit: don't WARN_ON_ONCE(!current->mm) in audit_exe_compare()

2023-11-14T22:34:27+00:00

eBPF can end up calling into the audit code from some odd places, and
some of these places don't have @current set properly so we end up
tripping the `WARN_ON_ONCE(!current->mm)` near the top of
`audit_exe_compare()`.  While the basic `!current->mm` check is good,
the `WARN_ON_ONCE()` results in some scary console messages so let's
drop that and just do the regular `!current->mm` check to avoid
problems.

Cc: 
Fixes: 47846d51348d ("audit: don't take task_lock() in audit_exe_compare() code path")
Reported-by: Artem Savkov 
Signed-off-by: Paul Moore

audit: don't take task_lock() in audit_exe_compare() code path

2023-10-26T02:29:47+00:00

The get_task_exe_file() function locks the given task with task_lock()
which when used inside audit_exe_compare() can cause deadlocks on
systems that generate audit records when the task_lock() is held. We
resolve this problem with two changes: ignoring those cases where the
task being audited is not the current task, and changing our approach
to obtaining the executable file struct to not require task_lock().

With the intent of the audit exe filter being to filter on audit events
generated by processes started by the specified executable, it makes
sense that we would only want to use the exe filter on audit records
associated with the currently executing process, e.g. @current.  If
we are asked to filter records using a non-@current task_struct we can
safely ignore the exe filter without negatively impacting the admin's
expectations for the exe filter.

Knowing that we only have to worry about filtering the currently
executing task in audit_exe_compare() we can do away with the
task_lock() and call get_mm_exe_file() with @current->mm directly.

Cc: 
Fixes: 5efc244346f9 ("audit: fix exe_file access in audit_exe_compare")
Reported-by: Andreas Steinmetz 
Reviewed-by: John Johansen 
Reviewed-by: Mateusz Guzik 
Signed-off-by: Paul Moore

audit_init_parent(): constify path

2022-09-01T21:39:30+00:00

Reviewed-by: Christian Brauner (Microsoft) 
Signed-off-by: Al Viro

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

Merge tag 'fsnotify_for_v5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

2021-11-06T23:43:20+00:00

Pull fsnotify updates from Jan Kara:
 "Support for reporting filesystem errors through fanotify so that
  system health monitoring daemons can watch for these and act instead
  of scraping system logs"

* tag 'fsnotify_for_v5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs: (34 commits)
  samples: remove duplicate include in fs-monitor.c
  samples: Fix warning in fsnotify sample
  docs: Fix formatting of literal sections in fanotify docs
  samples: Make fs-monitor depend on libc and headers
  docs: Document the FAN_FS_ERROR event
  samples: Add fs error monitoring example
  ext4: Send notifications on error
  fanotify: Allow users to request FAN_FS_ERROR events
  fanotify: Emit generic error info for error event
  fanotify: Report fid info for file related file system errors
  fanotify: WARN_ON against too large file handles
  fanotify: Add helpers to decide whether to report FID/DFID
  fanotify: Wrap object_fh inline space in a creator macro
  fanotify: Support merging of error events
  fanotify: Support enqueueing of error events
  fanotify: Pre-allocate pool of error events
  fanotify: Reserve UAPI bits for FAN_FS_ERROR
  fsnotify: Support FS_ERROR event type
  fanotify: Require fid_mode for any non-fd event
  fanotify: Encode empty file handle when no inode is provided
  ...

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