Re: [PATCH v7 0/4] fanotify: introduce new event mask FAN_OPEN_EXEC and FAN_OPEN_EXEC_PERM

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On Wed 14-11-18 05:43:25, Amir Goldstein wrote:
> On Tue, Nov 13, 2018 at 8:01 PM Amir Goldstein <amir73il@xxxxxxxxx> wrote:
> >
> > > > LTP tests for this feature are on my 'fanotify-exec' branch here:
> > > > https://github.com/matthewbobrowski/ltp/commits/fanotify_exec. The files
> > > > that contains the test cases are provided below:
> > > >
> > > > syscalls/fanotify03: test cases have been updated to cover
> > > >                      FAN_OPEN_EXEC_PERM events
> > > > syscalls/fanotify12: newly introduced LTP test file to cover
> > > >                      FAN_OPEN_EXEC events
> > >
> > > I have been wondering for a while why the testcases passed when ignore mask
> > > hasn't been properly treated in fanotify_group_event_mask() but then I
> > > realized that the generic code will not even call to fanotify if ignore
> > > masks result in clearing the event.
> >
> > So does that means we have missing test coverage?
> >
> 
> This is covered by test case #3 of Matthew's proposed LTP test.
> https://github.com/matthewbobrowski/ltp/commit/9e350fe15a5423d896ed0e8e147edc15bee13b42#diff-2bb8ddff24b3a031be0f64354262e587R76

This testcase does not catch the bug we had in fanotify_group_event_mask()
because the masking by mark->mask already hides the fact that we failed to
apply the ignore mask.

What does catch this kind of bug (tested) is a testcase (admittedly
somewhat silly) like this:

{
        "inode mark, FAN_OPEN | FAN_OPEN_EXEC events, ignore FAN_OPEN_EXEC",
        INIT_FANOTIFY_MARK_TYPE(INODE),
        FAN_OPEN | FAN_OPEN_EXEC,
        FAN_OPEN_EXEC,
        2,
        {FAN_OPEN, FAN_OPEN}
},

A real variant of this would be FAN_OPEN | FAN_OPEN_EXEC on mount, ignore
FAN_OPEN on inode. Then we should just get one FAN_OPEN_EXEC but with the bug
we'd get FAN_OPEN | FAN_OPEN_EXEC.

But creating such test would be slightly more involved. But probably it is
worth it. Matthew?

Also I have noticed that fanotify12 test has a bug that it reports:

fanotify12.c:220: FAIL: Received event: mask=1020, pid=5142 (expected 5142), fd=5

i.e., it reports expected pid instead of expected mask when mask does not
match. Can you please fix it Matthew?

								Honza
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR



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