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fanotify: fix merging marks masks with FAN_ONDIR 

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 54a307ba8d ("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>
This commit is contained in:
Amir Goldstein 2020-03-19 17:10:17 +02:00 committed by Jan Kara
parent f367a62a7c
commit 55bf882c7f
1 changed files with 7 additions and 4 deletions
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11
fs/notify/fanotify/fanotify.c
View File

@ -171,6 +171,13 @@ static u32 fanotify_group_event_mask(struct fsnotify_group *group,
if (!fsnotify_iter_should_report_type(iter_info, type))
continue;
mark = iter_info->marks[type];
/*
* If the event is on dir and this mark doesn't care about
* events on dir, don't send it!
*/
if (event_mask & FS_ISDIR && !(mark->mask & FS_ISDIR))
continue;
/*
* If the event is for a child and this mark doesn't care about
* events on a child, don't send it!
@ -203,10 +210,6 @@ static u32 fanotify_group_event_mask(struct fsnotify_group *group,
user_mask &= ~FAN_ONDIR;
}
if (event_mask & FS_ISDIR &&
!(marks_mask & FS_ISDIR & ~marks_ignored_mask))
return 0;
return test_mask & user_mask;
}