Re: Should audit_seccomp check audit_enabled?

From: Paul Moore
Date: Fri Oct 23 2015 - 22:24:24 EST


On October 23, 2015 5:30:45 PM Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:

On Fri, Oct 23, 2015 at 2:22 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
On Fri, Oct 23, 2015 at 2:07 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
On Oct 23, 2015 10:01 AM, "Kees Cook" <keescook@xxxxxxxxxxxx> wrote:

On Fri, Oct 23, 2015 at 9:19 AM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
> I would argue that, if auditing is off, audit_seccomp shouldn't do
> anything. After all, unlike e.g. selinux, seccomp is not a systemwide
> policy, and seccomp signals might be ordinary behavior that's internal
> to the seccomp-using application. IOW, for people with audit compiled
> in and subscribed by journald but switched off, I think that the
> records shouldn't be emitted.
>
> If you agree, I can send the two-line patch.

I think signr==0 states (which I would identify as "intended
behavior") don't need to be reported under any situation, but audit
folks wanted to keep it around.

Even if there is a nonzero signr, it could just be a program opting to
trap and emulate one of its own syscalls.

At present, that is a rare situation. Programs tend to be ptrace
managed externally. Is there anything catching SIGSYS itself?


I wrote one once. I also wrote a whole set of patches for libseccomp
to make it easier that never went anywhere -- I should dust those off
and package them into their own library.

It has been a while since we discussed those patches, but if I remember correctly it was going to be very difficult to do it in an arch agnostic way and that was a concern.

--
paul moore
www.paul-moore.com


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