Re: [PATCH ghak90 V9 04/13] audit: log drop of contid on exit of last task

[Paul Moore]

On Sat, Jun 27, 2020 at 9:22 AM Richard Guy Briggs <rgb@xxxxxxxxxx> 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@xxxxxxxxxx>
> ---
>  kernel/audit.c   | 20 ++++++++++++++++++++
>  kernel/audit.h   |  2 ++
>  kernel/auditsc.c |  2 ++
>  3 files changed, 24 insertions(+)

If you end up respinning this patchset it seems like this should be
merged in with patch 2/13.  This way patch 2/13 would include both the
"set" and "drop" records, making that patch a bit more useful on it's
own.

> diff --git a/kernel/audit.c b/kernel/audit.c
> index 6d387793f702..9e0b38ce1ead 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -2558,6 +2558,26 @@ int audit_set_contid(struct task_struct *task, u64 contid)
>         return rc;
>  }
>
> +void audit_log_container_drop(void)
> +{
> +       struct audit_buffer *ab;
> +       struct audit_contobj *cont;
> +
> +       rcu_read_lock();
> +       cont = _audit_contobj_get(current);
> +       _audit_contobj_put(cont);
> +       if (!cont || refcount_read(&cont->refcount) > 1)
> +               goto out;
> +       ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_CONTAINER_OP);

You may want to check on sleeping with RCU locks held, or just use
GFP_ATOMIC to be safe.


> +       if (!ab)
> +               goto out;
> +       audit_log_format(ab, "op=drop opid=%d contid=%llu old-contid=%llu",
> +                        task_tgid_nr(current), cont->id, cont->id);
> +       audit_log_end(ab);
> +out:
> +       rcu_read_unlock();
> +}
> +
>  /**
>   * audit_log_end - end one audit record
>   * @ab: the audit_buffer
> diff --git a/kernel/audit.h b/kernel/audit.h
> index 182fc76ea276..d07093903008 100644
> --- a/kernel/audit.h
> +++ b/kernel/audit.h
> @@ -254,6 +254,8 @@ extern void audit_log_d_path_exe(struct audit_buffer *ab,
>  extern struct tty_struct *audit_get_tty(void);
>  extern void audit_put_tty(struct tty_struct *tty);
>
> +extern void audit_log_container_drop(void);
> +
>  /* audit watch/mark/tree functions */
>  #ifdef CONFIG_AUDITSYSCALL
>  extern unsigned int audit_serial(void);
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index f00c1da587ea..f03d3eb0752c 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -1575,6 +1575,8 @@ static void audit_log_exit(void)
>
>         audit_log_proctitle();
>
> +       audit_log_container_drop();
> +
>         /* Send end of event record to help user space know we are finished */
>         ab = audit_log_start(context, GFP_KERNEL, AUDIT_EOE);
>         if (ab)

--
paul moore
www.paul-moore.com