On 23/09/10  1:47 -0700, Eric W. Biederman wrote:
> 
> Implementing file descriptors for the network namespace is simple and
> straight forward.
> 
> Signed-off-by: Eric W. Biederman <ebied...@xmission.com>

[...]

> diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
> index c988e68..581a088 100644
> --- a/net/core/net_namespace.c
> +++ b/net/core/net_namespace.c
> @@ -571,3 +571,33 @@ void unregister_pernet_device(struct pernet_operations 
> *ops)
>       mutex_unlock(&net_mutex);
>  }
>  EXPORT_SYMBOL_GPL(unregister_pernet_device);
> +
> +#ifdef CONFIG_NET_NS
> +static void *netns_get(struct task_struct *task)
> +{
> +     struct net *net;
> +     rcu_read_lock();
> +     net = get_net(task->nsproxy->net_ns);

task could be exiting, so task->nsproxy could be NULL, right?
Maybe make proc_ns_instantiate() rcu_dereference task->nsproxy, check for it
being not NULL, and pass task->nsproxy to ns_ops->get()?

That could be an issue for the user namespace since it is not in nsproxy, but
maybe no reasonable usage of ns_ops with user namespaces is envisioned.
Otherwise, checking that task is alive with RCU locked in proc_ns_instantiate() 
should be enough to be
rely on task->cred when calling ns_ops->get().

Thanks,

Louis

> +     rcu_read_unlock();
> +     return net;
> +}
> +
> +static void netns_put(void *ns)
> +{
> +     put_net(ns);
> +}
> +
> +static int netns_install(struct nsproxy *nsproxy, void *ns)
> +{
> +     put_net(nsproxy->net_ns);
> +     nsproxy->net_ns = get_net(ns);
> +     return 0;
> +}
> +
> +const struct proc_ns_operations netns_operations = {
> +     .name           = PROC_NSNAME("net"),
> +     .get            = netns_get,
> +     .put            = netns_put,
> +     .install        = netns_install,
> +};
> +#endif
> -- 
> 1.6.5.2.143.g8cc62
> 
> --
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-- 
Dr Louis Rilling                        Kerlabs
Skype: louis.rilling                    Batiment Germanium
Phone: (+33|0) 6 80 89 08 23            80 avenue des Buttes de Coesmes
http://www.kerlabs.com/                 35700 Rennes

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