Commit dabe729d authored by Amir Goldstein's avatar Amir Goldstein Committed by Jan Kara
Browse files

fsnotify: clarify contract for create event hooks 

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: aa93bdc5 ("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: default avatarJan Kara <jack@suse.cz>
Reported-by: default avatarGabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarGabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent fd5a3ff4

include/linux/fsnotify.h

+16 −6
Original line number Diff line number Diff line
@@ -192,16 +192,22 @@ static inline void fsnotify_inoderemove(struct inode *inode) 


/*

 * fsnotify_create - 'name' was linked in

 *

 * Caller must make sure that dentry->d_name is stable.

 * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate

 * ->d_inode later

 */

static inline void fsnotify_create(struct inode *inode, struct dentry *dentry)

static inline void fsnotify_create(struct inode *dir, struct dentry *dentry)

{

	audit_inode_child(inode, dentry, AUDIT_TYPE_CHILD_CREATE);

	audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);



	fsnotify_dirent(inode, dentry, FS_CREATE);

	fsnotify_dirent(dir, dentry, FS_CREATE);

}



/*

 * fsnotify_link - new hardlink in 'inode' directory

 *

 * Caller must make sure that new_dentry->d_name is stable.

 * Note: We have to pass also the linked inode ptr as some filesystems leave

 *   new_dentry->d_inode NULL and instantiate inode pointer later

 */
@@ -230,12 +236,16 @@ static inline void fsnotify_unlink(struct inode *dir, struct dentry *dentry) 


/*

 * fsnotify_mkdir - directory 'name' was created

 *

 * Caller must make sure that dentry->d_name is stable.

 * Note: some filesystems (e.g. kernfs) leave @dentry negative and instantiate

 * ->d_inode later

 */

static inline void fsnotify_mkdir(struct inode *inode, struct dentry *dentry)

static inline void fsnotify_mkdir(struct inode *dir, struct dentry *dentry)

{

	audit_inode_child(inode, dentry, AUDIT_TYPE_CHILD_CREATE);

	audit_inode_child(dir, dentry, AUDIT_TYPE_CHILD_CREATE);



	fsnotify_dirent(inode, dentry, FS_CREATE | FS_ISDIR);

	fsnotify_dirent(dir, dentry, FS_CREATE | FS_ISDIR);

}



/*

kernel/audit_fsnotify.c

+1 −2
Original line number Diff line number Diff line
@@ -160,8 +160,7 @@ static int audit_mark_handle_event(struct fsnotify_mark *inode_mark, u32 mask, 


	audit_mark = container_of(inode_mark, struct audit_fsnotify_mark, mark);



	if (WARN_ON_ONCE(inode_mark->group != audit_fsnotify_group) ||

	    WARN_ON_ONCE(!inode))

	if (WARN_ON_ONCE(inode_mark->group != audit_fsnotify_group))

		return 0;



	if (mask & (FS_CREATE|FS_MOVED_TO|FS_DELETE|FS_MOVED_FROM)) {

kernel/audit_watch.c

+1 −2
Original line number Diff line number Diff line
@@ -472,8 +472,7 @@ static int audit_watch_handle_event(struct fsnotify_mark *inode_mark, u32 mask, 


	parent = container_of(inode_mark, struct audit_parent, mark);



	if (WARN_ON_ONCE(inode_mark->group != audit_watch_group) ||

	    WARN_ON_ONCE(!inode))

	if (WARN_ON_ONCE(inode_mark->group != audit_watch_group))

		return 0;



	if (mask & (FS_CREATE|FS_MOVED_TO) && inode)