Re: [RFC][PATCH] ns: Syscalls for better namespace sharing control. v2

[Jonathan Corbet <corbet-T1hC0tSOHrs@public.gmane.org>]

Quick question:

> +void set_namespace(unsigned long nstype, void *ns)
> +{
> +	struct task_struct *tsk = current;
> +	struct nsproxy *new_nsproxy;
> +
> +	new_nsproxy = create_new_namespaces(0, tsk, tsk->fs);
> +	switch(nstype) {
> +	case NSTYPE_NET:
> +		put_net(new_nsproxy->net_ns);
> +		new_nsproxy->net_ns = get_net(ns);
> +		break;
> +	}
> +
> +	switch_task_namespaces(tsk, new_nsproxy);
> +}

I assume that, at some future point when more than one namespace type
is supported, there will be a check to ensure that the type of the given
namespace matches nstype?  I can imagine all kinds of mayhem that could
result in the case of an accidental (or intentional) mismatch.

Actually, why does setns() require the nstype parameter at all?  A
namespace fd is certainly going to have to know what sort of namespace
it represents...

Thanks,

jon