From a4f9a9a635e4d54ac93df4b861ed8792e17bd4a2 Mon Sep 17 00:00:00 2001 From: Naohiro Aota Date: Tue, 29 May 2012 11:02:24 -0700 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 Cc: Eric Paris Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Al Viro diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h index 91d0e0a3..63d966d 100644 --- a/include/linux/fsnotify_backend.h +++ b/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) -- cgit v0.10.2