From 13b6f57623bc485e116344fe91fbcb29f149242b Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Sun, 7 Mar 2010 18:14:23 -0800
Subject: [PATCH] ns proc: Add support for the network namespace.

Implementing file descriptors for the network namespace
is simple and straight forward.

Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 fs/proc/namespaces.c     |  3 +++
 include/linux/proc_fs.h  |  1 +
 net/core/net_namespace.c | 31 +++++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+)

diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index 6ae9f07d59ee..dcbd483e9915 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -16,6 +16,9 @@
 
 
 static const struct proc_ns_operations *ns_entries[] = {
+#ifdef CONFIG_NET_NS
+	&netns_operations,
+#endif
 };
 
 static const struct file_operations ns_file_operations = {
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index a6d2c6da5e5a..62126ec6ede9 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -265,6 +265,7 @@ struct proc_ns_operations {
 	void (*put)(void *ns);
 	int (*install)(struct nsproxy *nsproxy, void *ns);
 };
+extern const struct proc_ns_operations netns_operations;
 
 union proc_op {
 	int (*proc_get_link)(struct inode *, struct path *);
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 3f860261c5ee..bf7707e09a80 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -573,3 +573,34 @@ 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);
+	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		= "net",
+	.type		= CLONE_NEWNET,
+	.get		= netns_get,
+	.put		= netns_put,
+	.install	= netns_install,
+};
+#endif