[PATCH v8 3/9] seccomp: introduce writer locking

[Oleg Nesterov]

On 06/24, Kees Cook wrote:
>
> +static void copy_seccomp(struct task_struct *p)
> +{
> +#ifdef CONFIG_SECCOMP
> +	/*
> +	 * Must be called with sighand->lock held, which is common to
> +	 * all threads in the group. Regardless, nothing special is
> +	 * needed for the child since it is not yet in the tasklist.
> +	 */
> +	BUG_ON(!spin_is_locked(&current->sighand->siglock));
> +
> +	get_seccomp_filter(current);
> +	p->seccomp = current->seccomp;
> +
> +	if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
> +		set_tsk_thread_flag(p, TIF_SECCOMP);
> +#endif
> +}

Wait. But what about no_new_privs? We should copy it as well...

Perhaps this helper should be updated a bit and moved into seccomp.c so
that seccomp_sync_threads() could use it too.

Oleg.