Re: [PATCH 4/5] audit: anchor all pid references in the initial pid namespace

[Oleg Nesterov <oleg@redhat.com>]

On 12/23, Richard Guy Briggs wrote:
>
> Store and log all PIDs with reference to the initial PID namespace and
> use the access functions task_pid_nr() and task_tgid_nr() for task->pid
> and task->tgid rather than access them directly.

At first glance this patch looks like a good cleanup, but...

> @@ -429,6 +429,19 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
>  			f->val = 0;
>  		}
>
> +		if ((f->type == AUDIT_PID) || (f->type == AUDIT_PPID)) {
> +			struct pid *pid;
> +			rcu_read_lock();
> +			pid = find_vpid(f->val);
> +			if (!pid) {
> +				rcu_read_unlock();
> +				err = -ESRCH;
> +				goto exit_free;
> +			}
> +			f->val = pid_nr(pid);
> +			rcu_read_unlock();
> +		}

I do not really understand this change, but this doesn't matter, I do
not understand audit.

However, I think this deserves a separate patch with the changelog.

> @@ -278,9 +278,12 @@ static void dump_common_audit_data(struct audit_buffer *ab,
>  	}
>  	case LSM_AUDIT_DATA_TASK:
>  		tsk = a->u.tsk;
> -		if (tsk && tsk->pid) {
> -			audit_log_format(ab, " pid=%d comm=", tsk->pid);
> -			audit_log_untrustedstring(ab, tsk->comm);
> +		if (tsk) {
> +			pid_t pid = task_pid_nr(tsk);
> +			if (pid) {
> +				audit_log_format(ab, " pid=%d comm=", pid);
> +				audit_log_untrustedstring(ab, tsk->comm);

Just curious, is it really possible that a->u.tsk is an idle thread?

Oleg.