Re: [PATCH v5 5/5] sidechannel: Linux Security Module for sidechannel

[James Morris]

On Wed, 26 Sep 2018, Casey Schaufler wrote:

> +	/*
> +	 * Namespace checks. Considered safe if:
> +	 *	cgroup namespace is the same
> +	 *	User namespace is the same
> +	 *	PID namespace is the same
> +	 */
> +	if (current->nsproxy)
> +		ccgn = current->nsproxy->cgroup_ns;
> +	if (p->nsproxy)
> +		pcgn = p->nsproxy->cgroup_ns;
> +	if (ccgn != pcgn)
> +		return -EACCES;
> +	if (current->cred->user_ns != p->cred->user_ns)
> +		return -EACCES;
> +	if (task_active_pid_ns(current) != task_active_pid_ns(p))
> +		return -EACCES;
> +	return 0;

I really don't like the idea of hard-coding namespace security semantics 
in an LSM.  Also, I'm not sure if these semantics make any sense.

It least make it user configurable.


-- 
James Morris
<jmorris@xxxxxxxxx>