[PATCH 3.16.y-ckt 122/126] net: fix creation adjacent device symlinks

[Luis Henriques]

3.16.7-ckt5 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Alexander Y. Fomichev" <git.user at gmail.com>

commit 7ce64c79c4decdeb1afe0bf2f6ef834b382871d1 upstream.

__netdev_adjacent_dev_insert may add adjust device of different net
namespace, without proper check it leads to emergence of broken
sysfs links from/to devices in another namespace.
Fix: rewrite netdev_adjacent_is_neigh_list macro as a function,
     move net_eq check into netdev_adjacent_is_neigh_list.
     (thanks David)
     related to: 4c75431ac3520631f1d9e74aa88407e6374dbbc4

Signed-off-by: Alexander Fomichev <git.user at gmail.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Cc: Miquel van Smoorenburg <mikevs at xs4all.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/core/dev.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 1a9b82061128..2d93b9de1d7b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4799,9 +4799,14 @@ static void netdev_adjacent_sysfs_del(struct net_device *dev,
 	sysfs_remove_link(&(dev->dev.kobj), linkname);
 }
 
-#define netdev_adjacent_is_neigh_list(dev, dev_list) \
-		(dev_list == &dev->adj_list.upper || \
-		 dev_list == &dev->adj_list.lower)
+static inline bool netdev_adjacent_is_neigh_list(struct net_device *dev,
+						 struct net_device *adj_dev,
+						 struct list_head *dev_list)
+{
+	return (dev_list == &dev->adj_list.upper ||
+		dev_list == &dev->adj_list.lower) &&
+		net_eq(dev_net(dev), dev_net(adj_dev));
+}
 
 static int __netdev_adjacent_dev_insert(struct net_device *dev,
 					struct net_device *adj_dev,
@@ -4831,7 +4836,7 @@ static int __netdev_adjacent_dev_insert(struct net_device *dev,
 	pr_debug("dev_hold for %s, because of link added from %s to %s\n",
 		 adj_dev->name, dev->name, adj_dev->name);
 
-	if (netdev_adjacent_is_neigh_list(dev, dev_list)) {
+	if (netdev_adjacent_is_neigh_list(dev, adj_dev, dev_list)) {
 		ret = netdev_adjacent_sysfs_add(dev, adj_dev, dev_list);
 		if (ret)
 			goto free_adj;
@@ -4852,7 +4857,7 @@ static int __netdev_adjacent_dev_insert(struct net_device *dev,
 	return 0;
 
 remove_symlinks:
-	if (netdev_adjacent_is_neigh_list(dev, dev_list))
+	if (netdev_adjacent_is_neigh_list(dev, adj_dev, dev_list))
 		netdev_adjacent_sysfs_del(dev, adj_dev->name, dev_list);
 free_adj:
 	kfree(adj);
@@ -4885,8 +4890,7 @@ static void __netdev_adjacent_dev_remove(struct net_device *dev,
 	if (adj->master)
 		sysfs_remove_link(&(dev->dev.kobj), "master");
 
-	if (netdev_adjacent_is_neigh_list(dev, dev_list) &&
-	    net_eq(dev_net(dev),dev_net(adj_dev)))
+	if (netdev_adjacent_is_neigh_list(dev, adj_dev, dev_list))
 		netdev_adjacent_sysfs_del(dev, adj_dev->name, dev_list);
 
 	list_del_rcu(&adj->list);
-- 
2.1.4