netfilter: nf_tables: add nft_unregister_flowtable_hook()

Unbind flowtable callback if hook is unregistered.

This patch is implicitly fixing the error path of
nf_tables_newflowtable() and nft_flowtable_event().

Fixes: 8bb69f3b ("netfilter: nf_tables: add flowtable offload control plane")
Reported-by: wenxu <wenxu@ucloud.cn>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -5975,16 +5975,22 @@ nft_flowtable_type_get(struct net *net, u8 family)
 	return ERR_PTR(-ENOENT);
 }
 
+static void nft_unregister_flowtable_hook(struct net *net,
+					  struct nft_flowtable *flowtable,
+					  struct nft_hook *hook)
+{
+	nf_unregister_net_hook(net, &hook->ops);
+	flowtable->data.type->setup(&flowtable->data, hook->ops.dev,
+				    FLOW_BLOCK_UNBIND);
+}
+
 static void nft_unregister_flowtable_net_hooks(struct net *net,
 					       struct nft_flowtable *flowtable)
 {
 	struct nft_hook *hook;
 
-	list_for_each_entry(hook, &flowtable->hook_list, list) {
-		nf_unregister_net_hook(net, &hook->ops);
-		flowtable->data.type->setup(&flowtable->data, hook->ops.dev,
-					    FLOW_BLOCK_UNBIND);
-	}
+	list_for_each_entry(hook, &flowtable->hook_list, list)
+		nft_unregister_flowtable_hook(net, flowtable, hook);
 }
 
 static int nft_register_flowtable_net_hooks(struct net *net,
@@ -6030,9 +6036,7 @@ static int nft_register_flowtable_net_hooks(struct net *net,
 		if (i-- <= 0)
 			break;
 
-		nf_unregister_net_hook(net, &hook->ops);
-		flowtable->data.type->setup(&flowtable->data, hook->ops.dev,
-					    FLOW_BLOCK_UNBIND);
+		nft_unregister_flowtable_hook(net, flowtable, hook);
 		list_del_rcu(&hook->list);
 		kfree_rcu(hook, rcu);
 	}
@@ -6139,7 +6143,7 @@ static int nf_tables_newflowtable(struct net *net, struct sock *nlsk,
 	return 0;
 err5:
 	list_for_each_entry_safe(hook, next, &flowtable->hook_list, list) {
-		nf_unregister_net_hook(net, &hook->ops);
+		nft_unregister_flowtable_hook(net, flowtable, hook);
 		list_del_rcu(&hook->list);
 		kfree_rcu(hook, rcu);
 	}
@@ -6484,7 +6488,7 @@ static void nft_flowtable_event(unsigned long event, struct net_device *dev,
 		if (hook->ops.dev != dev)
 			continue;
 
-		nf_unregister_net_hook(dev_net(dev), &hook->ops);
+		nft_unregister_flowtable_hook(dev_net(dev), flowtable, hook);
 		list_del_rcu(&hook->list);
 		kfree_rcu(hook, rcu);
 		break;