Re: [RFC PATCH 3/3] ima: additional ToMToU violation tests

[Petr Vorel <pvorel@suse.cz>]

> On Thu, 2025-02-20 at 15:22 -0500, Mimi Zohar wrote:
> > On Thu, 2025-02-20 at 20:13 +0100, Petr Vorel wrote:
> > > > On Thu, 2025-02-20 at 19:16 +0100, Petr Vorel wrote:
> > > > > Hi Mimi,

> > > > > > Kernel patch "ima: limit the number of ToMToU integrity violations"
> > > > > > prevents superfluous ToMToU violations.  Add corresponding LTP tests.

> > > > > > Link:
> > > > > > https://lore.kernel.org/linux-integrity/20250219162131.416719-3-zohar@linux.ibm.com/
> > > > > > Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

> > > > > Unfortunately tests fail on both mainline kernel and kernel with your patches.

> > > > The new LTP IMA violations patches should fail without the associated kernel
> > > > patches.

> > > > > Any hint what could be wrong?

> > > > Of course it's dependent on the IMA policy.  The tests assume being booted with the
> > > > IMA
> > > > TCB measurement policy or similar policy being loaded.  Can you share the IMA
> > > > policy?
> > > > e.g. cat /sys/kernel/security/ima/policy

> > > > thanks,

> > > > Mimi

> > > Now testing on kernel *with* your patches. First run always fails, regardless
> > > whether using ima_policy=tcb or
> > > /opt/ltp/testcases/data/ima_violations/violations.policy).

> > > Kind regards,
> > > Petr

> > I'm not seeing that on my test machine.  Could there be other things running on your
> > system causing violations.  In anycase, your original test was less exacting.  
> > Similarly,
> > instead of "-eq", try using "-qe" in the following test and removing the subsequent new
> > "gt" test.

> -> "-ge"

Sure, changing to -ge fixes the problem:
if [ $(($num_violations_new - $num_violations)) -ge $expected_violations ]; then

I guess we need "-ge" for older kernels (unless "fix" for stable).  Should we
accept "$expected_violations || $expected_violations + 1" for new kernels to
avoid problems like the one on my system.

I wonder if the problem was somehow caused by the fact that I built kernel. OTOH
it's build by OBS (official openSUSE build service).

I don't expect you'd have time to look into it, in case you're interested and
have time sending a links to rpm binary and src package.

https://download.opensuse.org/repositories/home:/pevik:/ima-limit-open-writers-ToMToU/standard/x86_64/kernel-default-6.14~rc3-1.1.gb6b4102.x86_64.rpm
https://download.opensuse.org/repositories/home:/pevik:/ima-limit-open-writers-ToMToU/standard/src/kernel-source-6.14~rc3-1.1.gb6b4102.src.rpm

Kind regards,
Petr

> > if [ $(($num_violations_new - $num_violations)) -eq $expected_violations ]; then