Re: [PATCH V2 0/1] selinux-testsuite: Add filesystem tests

[Richard Haines <richard_c_haines@btinternet.com>]

On Thu, 2020-01-09 at 13:04 -0500, Stephen Smalley wrote:
> On 1/9/20 10:07 AM, Richard Haines wrote:
> > These tests should cover all the areas in selinux/hooks.c that
> > touch
> > the 'filesystem' class. Each hooks.c function is listed in the
> > 'test'
> > script as there are some permissions that are checked in multiple
> > places.
> > 
> > Tested on Fedora 31 and Rawhide (5.5 for the new watch perm).
> > 
> > V2 Changes:
> > 1) If udisks(8) daemon is running, stop then restart after tests.
> > The tests
> >     run faster and stops the annoying habit of adding mounts to the
> > 'files'
> >     app on the desktop. Supports /usr/bin/systemctl or
> > /usr/sbin/service
> >     More importantly it stops interferance with the '*context='
> > tests as it
> >     can cause intermittent failures. Tested by running 'test' in a
> > continuous
> >     loop with udisks enabled, and then again disabled.
> >     Loop 200 times, with udisks failed between 1 to 70 iterations,
> > without
> >     udisks, no failures.
> 
> Wondering why udisks is causing failures - that seems like another
> bug.

With udisk2 enabled, 99% of the time the 'rootcontext=' test fails (the
1% is 'defcontext='). However if I run this test on its own, it does
not fail. If I add the 'context=' test before and run, the
'rootcontext=' will fail at some point.

If I add a short delay as shown in the 'context=' sequence, the fault
does not occur:
-- Start --
system("losetup -d $dev 2>/dev/null");
system("sleep 0.01");
get_loop_dev();
attach_dev();

# Mount again with no xttr support
$context2_opts =
"context=system_u:object_r:test_filesystem_context_t:s0";
-- End --

It could be udisk2 has a timing problem as the losetup(8) man page '-d' 
entry reads:
Note that since Linux v3.7 kernel uses "lazy  device destruction". The
detach operation does not return EBUSY error anymore if device is
actively used by system, but it  is  marked by autoclear flag and
destroyed later.

But then again it could be something else !!!!