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

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Date:   Thu, 10 Oct 2019 20:38:47 -0400
From:   Paul Moore <paul@...l-moore.com>
To:     Richard Guy Briggs <rgb@...hat.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 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()?

--
paul moore
www.paul-moore.com