netfilter: nf_tables: allow netdevice to be used only once per flowtable

Allow netdevice only once per flowtable, otherwise hit EEXIST.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index d6224c7b0e283843a605ac9b85ab8ca31272bff0..2664bc388db4731bfb572000ab76a6bf9a577498 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1538,6 +1538,19 @@ err_hook_alloc:
        return ERR_PTR(err);
 }
 
+static bool nft_hook_list_find(struct list_head *hook_list,
+                              const struct nft_hook *this)
+{
+       struct nft_hook *hook;
+
+       list_for_each_entry(hook, hook_list, list) {
+               if (this->ops.dev == hook->ops.dev)
+                       return true;
+       }
+
+       return false;
+}
+
 static int nf_tables_parse_netdev_hooks(struct net *net,
                                        const struct nlattr *attr,
                                        struct list_head *hook_list)
@@ -1557,6 +1570,10 @@ static int nf_tables_parse_netdev_hooks(struct net *net,
                        err = PTR_ERR(hook);
                        goto err_hook;
                }
+               if (nft_hook_list_find(hook_list, hook)) {
+                       err = -EEXIST;
+                       goto err_hook;
+               }
                list_add_tail(&hook->list, hook_list);
                n++;