Re: seccomp ptrace selftest failures with 4.4-stable [Was: Re: LTS testing with latest kselftests - some failures]

From: Shuah Khan
Date: Thu Jun 22 2017 - 13:09:47 EST

On 06/22/2017 10:53 AM, Kees Cook wrote:
> On Thu, Jun 22, 2017 at 9:18 AM, Sumit Semwal <sumit.semwal@xxxxxxxxxx> wrote:
>> Hi Kees, Andy,
>> On 15 June 2017 at 23:26, Sumit Semwal <sumit.semwal@xxxxxxxxxx> wrote:
>>> 3. 'seccomp ptrace hole closure' patches got added in 4.7 [3] -
>>> feature and test together.
>>> - This one also seems like a security hole being closed, and the
>>> 'feature' could be a candidate for stable backports, but Arnd tried
>>> that, and it was quite non-trivial. So perhaps we'll need some help
>>> from the subsystem developers here.
>> Could you please help us sort this out? Our goal is to help Greg with
>> testing stable kernels, and currently the seccomp tests fail due to
>> missing feature (seccomp ptrace hole closure) getting tested via
>> latest kselftest.
>> If you feel the feature isn't a stable candidate, then could you
>> please help make the test degrade gracefully in its absence?
> I don't really want to have that change be a backport -- it's quite
> invasive across multiple architectures.
> I would say just add a kernel version check to the test. This is
> probably not the only selftest that will need such things. :)

Adding release checks to selftests is going to problematic for maintenance.
Tests should fail gracefully if feature isn't supported in older kernels.

Several tests do that now and please find a way to check for dependencies
and feature availability and fail the test gracefully. If there is a test
that can't do that for some reason, we can discuss it, but as a general
rule, I don't want to see kselftest patches that check release.

-- Shuah