[PATCH 7/8] net: Allow setting the network namespace by fd

[ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman)]

Take advantage of the new abstraction and allow network devices
to be placed in any network namespace that we have a fd to talk
about.

Signed-off-by: Eric W. Biederman <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
---
 include/linux/if_link.h     |    1 +
 include/net/net_namespace.h |    1 +
 net/core/net_namespace.c    |   26 ++++++++++++++++++++++++++
 net/core/rtnetlink.c        |    4 +++-
 4 files changed, 31 insertions(+), 1 deletions(-)

diff --git a/include/linux/if_link.h b/include/linux/if_link.h
index 2fc66dd..ae73d5e 100644
--- a/include/linux/if_link.h
+++ b/include/linux/if_link.h
@@ -116,6 +116,7 @@ enum {
 	IFLA_STATS64,
 	IFLA_VF_PORTS,
 	IFLA_PORT_SELF,
+	IFLA_NET_NS_FD,
 	__IFLA_MAX
 };
 
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index bd10a79..68672ce 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -114,6 +114,7 @@ static inline struct net *copy_net_ns(unsigned long flags, struct net *net_ns)
 extern struct list_head net_namespace_list;
 
 extern struct net *get_net_ns_by_pid(pid_t pid);
+extern struct net *get_net_ns_by_fd(int pid);
 
 #ifdef CONFIG_NET_NS
 extern void __put_net(struct net *net);
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 581a088..a9b54a7 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -8,6 +8,8 @@
 #include <linux/idr.h>
 #include <linux/rculist.h>
 #include <linux/nsproxy.h>
+#include <linux/proc_fs.h>
+#include <linux/file.h>
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
 
@@ -341,6 +343,30 @@ struct net *get_net_ns_by_pid(pid_t pid)
 }
 EXPORT_SYMBOL_GPL(get_net_ns_by_pid);
 
+struct net *get_net_ns_by_fd(int fd)
+{
+	struct proc_inode *ei;
+	struct file *file;
+	struct net *net;
+
+	file = NULL;
+	net = ERR_PTR(-EINVAL);
+	file = proc_ns_fget(fd);
+	if (!fd)
+		goto out;
+		return ERR_PTR(-EINVAL);
+
+	ei = PROC_I(file->f_dentry->d_inode);
+	if (ei->ns_ops != &netns_operations)
+		goto out;
+
+	net = get_net(ei->ns);
+out:
+	if (file)
+		fput(file);
+	return net;
+}
+
 static int __init net_ns_init(void)
 {
 	struct net_generic *ng;
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index f78d821..771d8be 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1003,6 +1003,8 @@ struct net *rtnl_link_get_net(struct net *src_net, struct nlattr *tb[])
 	 */
 	if (tb[IFLA_NET_NS_PID])
 		net = get_net_ns_by_pid(nla_get_u32(tb[IFLA_NET_NS_PID]));
+	else if (tb[IFLA_NET_NS_FD])
+		net = get_net_ns_by_fd(nla_get_u32(tb[IFLA_NET_NS_FD]));
 	else
 		net = get_net(src_net);
 	return net;
@@ -1077,7 +1079,7 @@ static int do_setlink(struct net_device *dev, struct ifinfomsg *ifm,
 	int send_addr_notify = 0;
 	int err;
 
-	if (tb[IFLA_NET_NS_PID]) {
+	if (tb[IFLA_NET_NS_PID] || tb[IFLA_NET_NS_FD]) {
 		struct net *net = rtnl_link_get_net(dev_net(dev), tb);
 		if (IS_ERR(net)) {
 			err = PTR_ERR(net);
-- 
1.6.5.2.143.g8cc62