fanotify: fix handling of events on child sub-directory (b469e7e4) · Commits · 戴 / test

When an event is reported on a sub-directory and the parent inode has a mark mask with FS_EVENT_ON_CHILD|FS_ISDIR, the event will be sent to fsnotify() even if the event type is not in the parent mark mask (e.g. FS_OPEN). Further more, if that event happened on a mount or a filesystem with a mount/sb mark that does have that event type in their mask, the "on child" event will be reported on the mount/sb mark. That is not desired, because user will get a duplicate event for the same action. Note that the event reported on the victim inode is never merged with the event reported on the parent inode, because of the check in should_merge(): old_fsn->inode == new_fsn->inode. Fix this by looking for a match of an actual event type (i.e. not just FS_ISDIR) in parent's inode mark mask and by not reporting an "on child" event to group if event type is only found on mount/sb marks. [backport hint: The bug seems to have always been in fanotify, but this patch will only apply cleanly to v4.19.y] Cc: <stable@vger.kernel.org> # v4.19 Signed-off-by:

Amir Goldstein <amir73il@gmail.com> Signed-off-by:

Jan Kara <jack@suse.cz>

fs/notify/fanotify/fanotify.c

+5 −5

Original line number	Diff line number	Diff line
		@@ -115,12 +115,12 @@ static bool fanotify_should_send_event(struct fsnotify_iter_info *iter_info,
		continue;
		mark = iter_info->marks[type];
		/*
		* if the event is for a child and this inode doesn't care about
		* events on the child, don't send it!
		* If the event is for a child and this mark doesn't care about
		* events on a child, don't send it!
		*/
		if (type == FSNOTIFY_OBJ_TYPE_INODE &&
		(event_mask & FS_EVENT_ON_CHILD) &&
		!(mark->mask & FS_EVENT_ON_CHILD))
		if (event_mask & FS_EVENT_ON_CHILD &&
		(type != FSNOTIFY_OBJ_TYPE_INODE \|\|
		!(mark->mask & FS_EVENT_ON_CHILD)))
		continue;

		marks_mask \|= mark->mask;

fs/notify/fsnotify.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -167,9 +167,9 @@ int __fsnotify_parent(const struct path path, struct dentry dentry, __u32 mask
		parent = dget_parent(dentry);
		p_inode = parent->d_inode;

		if (unlikely(!fsnotify_inode_watches_children(p_inode)))
		if (unlikely(!fsnotify_inode_watches_children(p_inode))) {
		__fsnotify_update_child_dentry_flags(p_inode);
		else if (p_inode->i_fsnotify_mask & mask) {
		} else if (p_inode->i_fsnotify_mask & mask & ALL_FSNOTIFY_EVENTS) {
		struct name_snapshot name;

		/* we are notifying a parent so come up with the new mask which
		@@ -339,6 +339,9 @@ int fsnotify(struct inode to_tell, __u32 mask, const void data, int data_is,
		sb = mnt->mnt.mnt_sb;
		mnt_or_sb_mask = mnt->mnt_fsnotify_mask \| sb->s_fsnotify_mask;
		}
		/* An event "on child" is not intended for a mount/sb mark */
		if (mask & FS_EVENT_ON_CHILD)
		mnt_or_sb_mask = 0;

		/*
		* Optimization: srcu_read_lock() has a memory barrier which can

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