net: Allow setting the network namespace by fd

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.

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>

4 files changed, 37 insertions, 3 deletions

diff --git a/include/linux/if_link.h b/include/linux/if_link.h
index f4a2e6b1b864..0ee969a5593d 100644
--- a/include/linux/if_link.h
+++ b/include/linux/if_link.h
@@ -136,6 +136,7 @@ enum {
         IFLA_PORT_SELF,
         IFLA_AF_SPEC,
         IFLA_GROUP,             /* Group the device belongs to */
+        IFLA_NET_NS_FD,
         __IFLA_MAX
 };
 
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 3ae491932bc8..dcc8f5749d3f 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -119,6 +119,7 @@ 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 bf7707e09a80..b7403ff4d6c6 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>
 
@@ -343,6 +345,28 @@ 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;
+
+        net = ERR_PTR(-EINVAL);
+        file = proc_ns_fget(fd);
+        if (!file)
+                goto out;
+
+        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;
@@ -577,10 +601,15 @@ EXPORT_SYMBOL_GPL(unregister_pernet_device);
 #ifdef CONFIG_NET_NS
 static void *netns_get(struct task_struct *task)
 {
-        struct net *net;
+        struct net *net = NULL;
+        struct nsproxy *nsproxy;
+
         rcu_read_lock();
-        net = get_net(task->nsproxy->net_ns);
+        nsproxy = task_nsproxy(task);
+        if (nsproxy)
+                net = get_net(nsproxy->net_ns);
         rcu_read_unlock();
+
         return net;
 }
 
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index d7c4bb4b1820..dca9602c62e4 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1043,6 +1043,7 @@ const struct nla_policy ifla_policy[IFLA_MAX+1] = {
         [IFLA_LINKMODE]         = { .type = NLA_U8 },
         [IFLA_LINKINFO]         = { .type = NLA_NESTED },
         [IFLA_NET_NS_PID]       = { .type = NLA_U32 },
+        [IFLA_NET_NS_FD]        = { .type = NLA_U32 },
         [IFLA_IFALIAS]          = { .type = NLA_STRING, .len = IFALIASZ-1 },
         [IFLA_VFINFO_LIST]      = {. type = NLA_NESTED },
         [IFLA_VF_PORTS]         = { .type = NLA_NESTED },
@@ -1091,6 +1092,8 @@ 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;
@@ -1221,7 +1224,7 @@ 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);