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

[James Morris]

On Thu, 27 Sep 2018, Casey Schaufler wrote:

> On 9/27/2018 2:45 PM, James Morris wrote:
> > 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.
> 
> Checks on namespaces where explicitly requested.

By whom and what is the rationale?


-- 
James Morris
<jmorris@xxxxxxxxx>