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From:   Paul Moore <paul@paul-moore.com>
Date:   Wed, 18 Mar 2020 17:01:26 -0400
Message-ID: <CAHC9VhQKOpVWxDg-tWuCWV22QRu8P_NpFKme==0Ot1RQKa_DWA@mail.gmail.com>
Subject: Re: [PATCH ghak90 V8 07/16] audit: add contid support for signalling
 the audit daemon
To:     Richard Guy Briggs <rgb@redhat.com>
Cc:     Steve Grubb <sgrubb@redhat.com>, linux-audit@redhat.com,
        nhorman@tuxdriver.com, linux-api@vger.kernel.org,
        containers@lists.linux-foundation.org,
        LKML <linux-kernel@vger.kernel.org>, dhowells@redhat.com,
        netfilter-devel@vger.kernel.org, ebiederm@xmission.com,
        simo@redhat.com, netdev@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, Eric Paris <eparis@parisplace.org>,
        mpatel@redhat.com, Serge Hallyn <serge@hallyn.com>
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On Fri, Mar 13, 2020 at 3:23 PM Richard Guy Briggs <rgb@redhat.com> wrote:
> On 2020-03-13 12:42, Paul Moore wrote:

...

> > The thread has had a lot of starts/stops, so I may be repeating a
> > previous suggestion, but one idea would be to still emit a "death
> > record" when the final task in the audit container ID does die, but
> > block the particular audit container ID from reuse until it the
> > SIGNAL2 info has been reported.  This gives us the timely ACID death
> > notification while still preventing confusion and ambiguity caused by
> > potentially reusing the ACID before the SIGNAL2 record has been sent;
> > there is a small nit about the ACID being present in the SIGNAL2
> > *after* its death, but I think that can be easily explained and
> > understood by admins.
>
> Thinking quickly about possible technical solutions to this, maybe it
> makes sense to have two counters on a contobj so that we know when the
> last process in that container exits and can issue the death
> certificate, but we still block reuse of it until all further references
> to it have been resolved.  This will likely also make it possible to
> report the full contid chain in SIGNAL2 records.  This will eliminate
> some of the issues we are discussing with regards to passing a contobj
> vs a contid to the audit_log_contid function, but won't eliminate them
> all because there are still some contids that won't have an object
> associated with them to make it impossible to look them up in the
> contobj lists.

I'm not sure you need a full second counter, I imagine a simple flag
would be okay.  I think you just something to indicate that this ACID
object is marked as "dead" but it still being held for sanity reasons
and should not be reused.

-- 
paul moore
www.paul-moore.com