linux-kernel - Re: Should audit_seccomp check audit

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Date:	Fri, 23 Oct 2015 16:58:15 -0400
From:	Paul Moore <paul@...l-moore.com>
To:	Steve Grubb <sgrubb@...hat.com>, Kees Cook <keescook@...omium.org>
Cc:	Andy Lutomirski <luto@...capital.net>,
	Richard Guy Briggs <rgb@...hat.com>, linux-audit@...hat.com,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Should audit_seccomp check audit_enabled?

On Fri, Oct 23, 2015 at 4:51 PM, Steve Grubb <sgrubb@...hat.com> wrote:
> On Friday, October 23, 2015 03:38:05 PM Paul Moore wrote:
>> On Fri, Oct 23, 2015 at 1:01 PM, Kees Cook <keescook@...omium.org> wrote:
>> > On Fri, Oct 23, 2015 at 9:19 AM, Andy Lutomirski <luto@...capital.net>
> 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.
>>
>> Wearing my libseccomp hat, I would like some logging when the seccomp
>> filter triggers a result other than allow.  I don't care if this is
>> via audit or printk(), I just want some notification.  If we go the
>> printk route and people really don't want to see anything in their
>> logs, I suppose we could always add a sysctl knob to turn off the
>> message completely (we would still need to do whatever audit records
>> are required, see below).
>>
>> Wearing my audit hat, I want to make sure we tick off all the right
>> boxes for the various certifications that people care about.  Steve
>> Grubb has commented on what he needs in the past, although I'm not
>> sure it was on-list, so I'll ask him to repeat it here.
>
> I went back and reviewed my notes since this came up in the current Common
> Criteria evaluation. What we decided to do is treat syscall failures which
> failed due to seccomp the same as syscall failures caused by dropping
> capabilities. Both are opt-in DAC policies. That means we don't care. Do
> whatever you like. :-)

Thanks Steve.

Andy, is your objection that you don't want to see any seccomp
messages, or just seccomp audit records when audit is disabled?

-- 
paul moore
www.paul-moore.com
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