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

[Mimi Zohar <zohar@linux.ibm.com>]

On Thu, 2025-02-20 at 22:43 +0100, Petr Vorel wrote:
> > 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.

The problem is that we don't control what else is running on the system.  So there could
be other violations independent of these tests.  I'll have to think about it some more and
get back to you.  (There's no rush to do anything with these LTP IMA violation tests.)

> 
> 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).

As long as you weren't building the kernel and running the tests at the same, I doubt it
would be the problem.

> 
> 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.

Ok.
> 
> 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
> 

thanks,

Mimi

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