Subject: [PATCH 3/8] ns proc: Add support for the network namespace.

From: [email-masked] (Eric W. Biederman)
Date: Thu, 23 Sep 2010 01:47:42 -0700

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

Signed-off-by: Eric W. Biederman <[email-masked]>
---
 fs/proc/namespaces.c     |    3 +++
 include/linux/proc_fs.h  |    1 +
 net/core/net_namespace.c |   30 ++++++++++++++++++++++++++++++
 3 files changed, 34 insertions(+), 0 deletions(-)

diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index f33537f..31e32f3 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 a6c26f0..9cd3fae 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -262,6 +262,7 @@ struct proc_ns_operations {
 	int (*install)(struct nsproxy *nsproxy, void *ns);
 };
 #define PROC_NSNAME(NAME) { .name = (NAME), .len = (sizeof(NAME) - 1), }
+extern const struct proc_ns_operations netns_operations;
 extern struct file *proc_ns_fget(int fd);
 
 union proc_op {
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);
+	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