diff options
| author | Christian Brauner <brauner@kernel.org> | 2025-04-14 22:13:33 +0200 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2025-04-15 11:32:34 +0200 |
| commit | c86b300b1ea35959a6e2a63a6497226a6ea90b67 (patch) | |
| tree | a58eff52db91c26b171ad1485d0988ec1f8091cc /kernel | |
| parent | ddee68c499f76ae47c011549df5be53db0057402 (diff) | |
fs: add kern_path_locked_negative()
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 <vbabka@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/audit_watch.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c index 367eaf2c78b7..0ebbbe37a60f 100644 --- a/kernel/audit_watch.c +++ b/kernel/audit_watch.c @@ -347,12 +347,17 @@ static void audit_remove_parent_watches(struct audit_parent *parent) /* Get path information necessary for adding watches. */ static int audit_get_nd(struct audit_watch *watch, struct path *parent) { - struct dentry *d = kern_path_locked(watch->path, parent); + struct dentry *d; + + d = kern_path_locked_negative(watch->path, parent); if (IS_ERR(d)) return PTR_ERR(d); - /* update watch filter fields */ - watch->dev = d->d_sb->s_dev; - watch->ino = d_backing_inode(d)->i_ino; + + if (d_is_positive(d)) { + /* update watch filter fields */ + watch->dev = d->d_sb->s_dev; + watch->ino = d_backing_inode(d)->i_ino; + } inode_unlock(d_backing_inode(parent->dentry)); dput(d); @@ -418,11 +423,10 @@ int audit_add_watch(struct audit_krule *krule, struct list_head **list) /* caller expects mutex locked */ mutex_lock(&audit_filter_mutex); - if (ret && ret != -ENOENT) { + if (ret) { audit_put_watch(watch); return ret; } - ret = 0; /* either find an old parent or attach a new one */ parent = audit_find_parent(d_backing_inode(parent_path.dentry)); |