From 55bf882c7f13dda8bbe624040c6d5b4fbb812d16 Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Thu, 19 Mar 2020 17:10:17 +0200
Subject: [PATCH] fanotify: fix merging marks masks with FAN_ONDIR
Git-commit: 55bf882c7f13dda8bbe624040c6d5b4fbb812d16
Patch-mainline: v5.7-rc1
References: bsc#1171679

Change the logic of FAN_ONDIR in two ways that are similar to the logic
of FAN_EVENT_ON_CHILD, that was fixed in commit 54a307ba8d3c ("fanotify:
fix logic of events on child"):

1. The flag is meaningless in ignore mask
2. The flag refers only to events in the mask of the mark where it is set

This is what the fanotify_mark.2 man page says about FAN_ONDIR:
"Without this flag, only events for files are created."  It doesn't
say anything about setting this flag in ignore mask to stop getting
events on directories nor can I think of any setup where this capability
would be useful.

Currently, when marks masks are merged, the FAN_ONDIR flag set in one
mark affects the events that are set in another mark's mask and this
behavior causes unexpected results.  For example, a user adds a mark on a
directory with mask FAN_ATTRIB | FAN_ONDIR and a mount mark with mask
FAN_OPEN (without FAN_ONDIR).  An opendir() of that directory (which is
inside that mount) generates a FAN_OPEN event even though neither of the
marks requested to get open events on directories.

Link: https://lore.kernel.org/r/20200319151022.31456-10-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Jan Kara <jack@suse.cz>

---
 fs/notify/fanotify/fanotify.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -108,10 +108,13 @@ static bool fanotify_should_send_event(s
 	/*
 	 * If the event is for a child and this mark doesn't care about
 	 * events on a child, don't send it!
+	 * If the event is on dir and this mark doesn't care about
+	 * events on dir, don't send it!
 	 */
 	if (inode_mark &&
 	    (!(event_mask & FS_EVENT_ON_CHILD) ||
-	     (inode_mark->mask & FS_EVENT_ON_CHILD))) {
+	     (inode_mark->mask & FS_EVENT_ON_CHILD)) &&
+	    (!(event_mask & FS_ISDIR) || inode_mark->mask & FS_ISDIR)) {
 		marks_mask |= inode_mark->mask;
 		marks_ignored_mask |= inode_mark->ignored_mask;
 	}
@@ -119,8 +122,11 @@ static bool fanotify_should_send_event(s
 	/*
 	 * Mount marks don't care about event on children. Ignore them as
 	 * otherwise we could report some events twice. 
+	 * If the event is on dir and this mark doesn't care about
+	 * events on dir, don't send it!
 	 */
-	if (vfsmnt_mark && !(event_mask & FS_EVENT_ON_CHILD)) {
+	if (vfsmnt_mark && !(event_mask & FS_EVENT_ON_CHILD) &&
+	    (!(event_mask & FS_ISDIR) || vfsmnt_mark->mask & FS_ISDIR)) {
 		marks_mask |= vfsmnt_mark->mask;
 		marks_ignored_mask |= vfsmnt_mark->ignored_mask;
 	}