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

From: Paul Moore
Date: Sun Jul 05 2020 - 11:10:28 EST


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