net: dev: fix incorrect getting net device's name

When moving a nic from net namespace A to net namespace B,
in dev_change_net_namesapce,we call __dev_get_by_name to
decide if the netns B has the device has the same name.

if the netns B already has the same named device,we call
dev_get_valid_name to try to get a valid name for this nic in
the netns B,but net_device->nd_net still point to netns A now.

this patch fix it.

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 20 insertions, 8 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 52cd1d7f004a..bb42eb161969 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -959,18 +959,30 @@ int dev_alloc_name(struct net_device *dev, const char *name)
 }
 EXPORT_SYMBOL(dev_alloc_name);
 
-static int dev_get_valid_name(struct net_device *dev, const char *name)
+static int dev_alloc_name_ns(struct net *net,
+                             struct net_device *dev,
+                             const char *name)
 {
-        struct net *net;
+        char buf[IFNAMSIZ];
+        int ret;
 
-        BUG_ON(!dev_net(dev));
-        net = dev_net(dev);
+        ret = __dev_alloc_name(net, name, buf);
+        if (ret >= 0)
+                strlcpy(dev->name, buf, IFNAMSIZ);
+        return ret;
+}
+
+static int dev_get_valid_name(struct net *net,
+                              struct net_device *dev,
+                              const char *name)
+{
+        BUG_ON(!net);
 
         if (!dev_valid_name(name))
                 return -EINVAL;
 
         if (strchr(name, '%'))
-                return dev_alloc_name(dev, name);
+                return dev_alloc_name_ns(net, dev, name);
         else if (__dev_get_by_name(net, name))
                 return -EEXIST;
         else if (dev->name != name)
@@ -1006,7 +1018,7 @@ int dev_change_name(struct net_device *dev, const char *newname)
 
         memcpy(oldname, dev->name, IFNAMSIZ);
 
-        err = dev_get_valid_name(dev, newname);
+        err = dev_get_valid_name(net, dev, newname);
         if (err < 0)
                 return err;
 
@@ -5589,7 +5601,7 @@ int register_netdevice(struct net_device *dev)
 
         dev->iflink = -1;
 
-        ret = dev_get_valid_name(dev, dev->name);
+        ret = dev_get_valid_name(net, dev, dev->name);
         if (ret < 0)
                 goto out;
 
@@ -6233,7 +6245,7 @@ int dev_change_net_namespace(struct net_device *dev, struct net *net, const char
                 /* We get here if we can't use the current device name */
                 if (!pat)
                         goto out;
-                if (dev_get_valid_name(dev, pat) < 0)
+                if (dev_get_valid_name(net, dev, pat) < 0)
                         goto out;
         }