rtnetlink: rtnl_link_register() sanity test

Before adding a struct rtnl_link_ops into link_ops list, check it doesnt
clash with a prior one.

Based on a previous patch from Alexander Smirnov

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Alexander Smirnov <alex.bluesman.smirnov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 11 deletions

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 9083e82bdae5..dbf2ddafd52d 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -273,6 +273,17 @@ EXPORT_SYMBOL_GPL(rtnl_unregister_all);
 
 static LIST_HEAD(link_ops);
 
+static const struct rtnl_link_ops *rtnl_link_ops_get(const char *kind)
+{
+        const struct rtnl_link_ops *ops;
+
+        list_for_each_entry(ops, &link_ops, list) {
+                if (!strcmp(ops->kind, kind))
+                        return ops;
+        }
+        return NULL;
+}
+
 /**
  * __rtnl_link_register - Register rtnl_link_ops with rtnetlink.
  * @ops: struct rtnl_link_ops * to register
@@ -285,6 +296,9 @@ static LIST_HEAD(link_ops);
  */
 int __rtnl_link_register(struct rtnl_link_ops *ops)
 {
+        if (rtnl_link_ops_get(ops->kind))
+                return -EEXIST;
+
         if (!ops->dellink)
                 ops->dellink = unregister_netdevice_queue;
 
@@ -351,17 +365,6 @@ void rtnl_link_unregister(struct rtnl_link_ops *ops)
 }
 EXPORT_SYMBOL_GPL(rtnl_link_unregister);
 
-static const struct rtnl_link_ops *rtnl_link_ops_get(const char *kind)
-{
-        const struct rtnl_link_ops *ops;
-
-        list_for_each_entry(ops, &link_ops, list) {
-                if (!strcmp(ops->kind, kind))
-                        return ops;
-        }
-        return NULL;
-}
-
 static size_t rtnl_link_get_size(const struct net_device *dev)
 {
         const struct rtnl_link_ops *ops = dev->rtnl_link_ops;