[PATCH 2/3] vfs: call audit_inode_child() in lookup_open() on failure
From: Jori Koolstra
Date: Fri Jul 10 2026 - 12:46:58 EST
audit_inode_child() is called in may_create_dentry() so that failed
filesystem operations still register an audit entry. On success, the
entry is overwritten when, for instance, fsnotify_create() is called.
This is the calling convention in vfs_create() and vfs_mkdir().
In lookup_open(), however, when atomic_open() should have created a
file but didn't, no call to audit_inode_child() is made. The same is
true for the regular ->create() path.
Fix the calling of audit_inode_child() in lookup_open() to match the
vfs_create() path. For the ->atomic_open() filesystems this logic has
been pushed into atomic_open(). This function is also reordered a bit
to make the case distinction of the possible returns from
->atomic_open() more explicit (i.e. finish_open() or finish_no_open()).
When retrying delegation breaking, audit_inode_child() could be called
more than once, but this is OK because those entries are reused.
Signed-off-by: Jori Koolstra <jkoolstra@xxxxxxxxx>
---
fs/namei.c | 92 ++++++++++++++++++++++++++++++++----------------------
1 file changed, 55 insertions(+), 37 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 447eda7cbe34..fe5d59c6f925 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4351,35 +4351,55 @@ static int may_o_create(struct mnt_idmap *idmap,
*/
static struct dentry *atomic_open(const struct path *path, struct dentry *dentry,
struct file *file,
- int open_flag, umode_t mode)
+ int open_flag, umode_t mode, int create_error)
{
struct dentry *const DENTRY_NOT_SET = (void *) -1UL;
- struct inode *dir = path->dentry->d_inode;
+ struct inode *dir_inode = path->dentry->d_inode;
int error;
file->__f_path.dentry = DENTRY_NOT_SET;
file->__f_path.mnt = path->mnt;
- error = dir->i_op->atomic_open(dir, dentry, file,
+ error = dir_inode->i_op->atomic_open(dir_inode, dentry, file,
open_to_namei_flags(open_flag), mode);
d_lookup_done(dentry);
+
if (!error) {
if (file->f_mode & FMODE_OPENED) {
- if (unlikely(dentry != file->f_path.dentry)) {
+ /* finish_open() called */
+ struct dentry *opened = file->f_path.dentry;
+ if (unlikely(opened != dentry)) {
dput(dentry);
- dentry = dget(file->f_path.dentry);
+ dentry = dget(opened);
}
- } else if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) {
- error = -EIO;
- } else {
- if (file->f_path.dentry) {
+ } else if (likely(file->f_path.dentry != DENTRY_NOT_SET)) {
+ /* finish_no_open() called */
+ struct dentry *replaced = file->f_path.dentry;
+ if (replaced) {
dput(dentry);
- dentry = file->f_path.dentry;
+ dentry = replaced;
}
if (unlikely(d_is_negative(dentry)))
error = -ENOENT;
+ } else {
+ const char *fsname = dentry->d_sb->s_type->name;
+ WARN(1, "%s: ->atomic_open() left file->f_path.dentry unset!\n",
+ fsname);
+ error = -EIO;
}
}
+
if (error) {
+ if (unlikely(create_error) && error == -ENOENT) {
+ /*
+ * Should have done a create, but errored before.
+ * Some filesystems return -ENOENT directly instead of
+ * calling finish_no_open() with a negative dentry;
+ * either way it should only mean the child doesn't exist,
+ * so a refused create is safe to record here.
+ */
+ audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE);
+ error = create_error;
+ }
dput(dentry);
dentry = ERR_PTR(error);
}
@@ -4437,7 +4457,7 @@ static struct dentry *lookup_open(struct nameidata *nd, struct file *file,
dentry = NULL;
}
if (dentry->d_inode) {
- /* Cached positive dentry: will open in f_op->open */
+ /* Cached positive dentry: will open in do_open(). */
return dentry;
}
@@ -4471,10 +4491,7 @@ static struct dentry *lookup_open(struct nameidata *nd, struct file *file,
if (dir_inode->i_op->atomic_open) {
if (nd->flags & LOOKUP_DIRECTORY)
open_flag |= O_DIRECTORY;
- dentry = atomic_open(&nd->path, dentry, file, open_flag, mode);
- if (unlikely(create_error) && dentry == ERR_PTR(-ENOENT))
- dentry = ERR_PTR(create_error);
- return dentry;
+ return atomic_open(&nd->path, dentry, file, open_flag, mode, create_error);
}
if (d_in_lookup(dentry)) {
@@ -4490,32 +4507,36 @@ static struct dentry *lookup_open(struct nameidata *nd, struct file *file,
dentry = res;
}
}
+ if (dentry->d_inode || !(op->open_flag & O_CREAT)) {
+ /* No need to create a file. If lookup returned a positive
+ * dentry, the file will be opened in do_open(). */
+ return dentry;
+ }
+
+ /* Negative dentry with O_CREAT flag set */
+ audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE);
- if (unlikely(create_error) && !dentry->d_inode) {
+ if (unlikely(create_error)) {
+ /* should have done a create, but we already errored */
error = create_error;
goto out_dput;
}
- /* Negative dentry, just create the file */
- if (!dentry->d_inode && (open_flag & O_CREAT)) {
- /* but break the directory lease first! */
- error = try_break_deleg(dir_inode, LEASE_BREAK_DIR_CREATE, delegated_inode);
- if (error)
- goto out_dput;
-
- file->f_mode |= FMODE_CREATED;
- audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE);
- if (!dir_inode->i_op->create) {
- error = -EACCES;
- goto out_dput;
- }
+ error = try_break_deleg(dir_inode, LEASE_BREAK_DIR_CREATE, delegated_inode);
+ if (error)
+ goto out_dput;
- error = dir_inode->i_op->create(idmap, dir_inode, dentry,
- mode, open_flag & O_EXCL);
- if (error)
- goto out_dput;
+ file->f_mode |= FMODE_CREATED;
+ if (!dir_inode->i_op->create) {
+ error = -EACCES;
+ goto out_dput;
}
+ error = dir_inode->i_op->create(idmap, dir_inode, dentry,
+ mode, open_flag & O_EXCL);
+ if (error)
+ goto out_dput;
+
return dentry;
out_dput:
@@ -5053,7 +5074,7 @@ struct file *dentry_create(struct path *path, int flags, umode_t mode,
/* atomic_open will dput(dentry) on error */
dget(orig_dentry);
- dentry = atomic_open(path, dentry, file, flags, mode);
+ dentry = atomic_open(path, dentry, file, flags, mode, create_error);
error = PTR_ERR_OR_ZERO(dentry);
if (IS_ERR(dentry))
@@ -5063,9 +5084,6 @@ struct file *dentry_create(struct path *path, int flags, umode_t mode,
/* Drop the extra reference */
dput(orig_dentry);
- if (unlikely(create_error) && error == -ENOENT)
- error = create_error;
-
if (!error) {
if (file->f_mode & FMODE_CREATED)
fsnotify_create(dir->d_inode, dentry);
--
2.55.0