From: Naohiro Aota <naota@xxxxxxxxx> Subject: fsnotify: handle subfiles' perm events Recently I'm working on fanotify and found the following strange behaviors. I wrote a program to set fanotify_mark on "/tmp/block" and FAN_DENY all events notified. fanotify_mask = FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD: $ cd /tmp/block; cat foo cat: foo: Operation not permitted Operation on the file is blocked as expected. But, fanotify_mask = FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD: $ cd /tmp/block; cat foo aaa It's not blocked anymore. This is confusing behavior. Also reading commit "fsnotify: call fsnotify_parent in perm events", it seems like fsnotify should handle subfiles' perm events as well as the other notify events. With this patch, regardless of FAN_ALL_EVENTS set or not: $ cd /tmp/block; cat foo cat: foo: Operation not permitted Operation on the file is now blocked properly. FS_OPEN_PERM and FS_ACCESS_PERM are not listed on FS_EVENTS_POSS_ON_CHILD. Due to fsnotify_inode_watches_children() check, if you only specify only these events as fsnotify_mask, you don't get subfiles' perm events notified. This patch add the events to FS_EVENTS_POSS_ON_CHILD to get them notified even if only these events are specified to fsnotify_mask. Signed-off-by: Naohiro Aota <naota@xxxxxxxxx> Cc: Eric Paris <eparis@xxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/fsnotify_backend.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN include/linux/fsnotify_backend.h~fsnotify-handle-subfiles-perm-events include/linux/fsnotify_backend.h --- a/include/linux/fsnotify_backend.h~fsnotify-handle-subfiles-perm-events +++ a/include/linux/fsnotify_backend.h @@ -60,7 +60,7 @@ #define FS_EVENTS_POSS_ON_CHILD (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\ FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\ FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\ - FS_DELETE) + FS_DELETE | FS_OPEN_PERM | FS_ACCESS_PERM) #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO) _ -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
