fanotify: mask out special event flags from ignored mask

The special event flags (FAN_ONDIR, FAN_EVENT_ON_CHILD) never had
any meaning in ignored mask. Mask them out explicitly.

Link: https://lore.kernel.org/r/20200716084230.30611-6-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/notify/fanotify/fanotify_user.c

@@ -1040,6 +1040,7 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 	__kernel_fsid_t __fsid, *fsid = NULL;
 	u32 valid_mask = FANOTIFY_EVENTS | FANOTIFY_EVENT_FLAGS;
 	unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
+	bool ignored = flags & FAN_MARK_IGNORED_MASK;
 	unsigned int obj_type, fid_mode;
 	int ret;
 
@@ -1087,6 +1088,10 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 	if (mask & ~valid_mask)
 		return -EINVAL;
 
+	/* Event flags (ONDIR, ON_CHILD) are meaningless in ignored mask */
+	if (ignored)
+		mask &= ~FANOTIFY_EVENT_FLAGS;
+
 	f = fdget(fanotify_fd);
 	if (unlikely(!f.file))
 		return -EBADF;