linux-kernel - Re: [PATCH ghak90 V7 05/21] audit: log drop of contid on exit of last task

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Date:   Fri, 25 Oct 2019 15:43:56 -0400
From:   Richard Guy Briggs <rgb@...hat.com>
To:     Paul Moore <paul@...l-moore.com>
Cc:     containers@...ts.linux-foundation.org, linux-api@...r.kernel.org,
        Linux-Audit Mailing List <linux-audit@...hat.com>,
        linux-fsdevel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        netdev@...r.kernel.org, netfilter-devel@...r.kernel.org,
        sgrubb@...hat.com, omosnace@...hat.com, dhowells@...hat.com,
        simo@...hat.com, Eric Paris <eparis@...isplace.org>,
        Serge Hallyn <serge@...lyn.com>, ebiederm@...ssion.com,
        nhorman@...driver.com, Dan Walsh <dwalsh@...hat.com>,
        mpatel@...hat.com
Subject: Re: [PATCH ghak90 V7 05/21] audit: log drop of contid on exit of
 last task

On 2019-10-10 20:38, Paul Moore wrote:
> On Wed, Sep 18, 2019 at 9:24 PM Richard Guy Briggs <rgb@...hat.com> wrote:
> > Since we are tracking the life of each audit container indentifier, we
> > can match the creation event with the destruction event.  Log the
> > destruction of the audit container identifier when the last process in
> > that container exits.
> >
> > Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
> > ---
> >  kernel/audit.c   | 32 ++++++++++++++++++++++++++++++++
> >  kernel/audit.h   |  2 ++
> >  kernel/auditsc.c |  2 ++
> >  3 files changed, 36 insertions(+)
> >
> > diff --git a/kernel/audit.c b/kernel/audit.c
> > index ea0899130cc1..53d13d638c63 100644
> > --- a/kernel/audit.c
> > +++ b/kernel/audit.c
> > @@ -2503,6 +2503,38 @@ int audit_set_contid(struct task_struct *task, u64 contid)
> >         return rc;
> >  }
> >
> > +void audit_log_container_drop(void)
> > +{
> > +       struct audit_buffer *ab;
> > +       uid_t uid;
> > +       struct tty_struct *tty;
> > +       char comm[sizeof(current->comm)];
> > +
> > +       if (!current->audit || !current->audit->cont ||
> > +           refcount_read(&current->audit->cont->refcount) > 1)
> > +               return;
> > +       ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_CONTAINER_OP);
> > +       if (!ab)
> > +               return;
> > +
> > +       uid = from_kuid(&init_user_ns, task_uid(current));
> > +       tty = audit_get_tty();
> > +       audit_log_format(ab,
> > +                        "op=drop opid=%d contid=%llu old-contid=%llu pid=%d uid=%u auid=%u tty=%s ses=%u",
> > +                        task_tgid_nr(current), audit_get_contid(current),
> > +                        audit_get_contid(current), task_tgid_nr(current), uid,
> > +                        from_kuid(&init_user_ns, audit_get_loginuid(current)),
> > +                        tty ? tty_name(tty) : "(none)",
> > +                                audit_get_sessionid(current));
> > +       audit_put_tty(tty);
> > +       audit_log_task_context(ab);
> > +       audit_log_format(ab, " comm=");
> > +       audit_log_untrustedstring(ab, get_task_comm(comm, current));
> > +       audit_log_d_path_exe(ab, current->mm);
> > +       audit_log_format(ab, " res=1");
> > +       audit_log_end(ab);
> > +}
> 
> Why can't we just do this in audit_cont_put()?  Is it because we call
> audit_cont_put() in the new audit_free() function?  What if we were to
> do it in __audit_free()/audit_free_syscall()?

The intent was to put this before the EOE record of a syscall so we
could fill out all the fields similarly to op=set, but this could stand
alone dropping or nulling a bunch of fields.

It would also never get printed if we left it before the EOE and had the
audit signal info record keep a reference to it.

Hmmm...

> paul moore

- RGB

--
Richard Guy Briggs <rgb@...hat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635