netfilter: nf_tables_offload: remove rules when the device unregisters

If the net_device unregisters, clean up the offload rules before the
chain is destroy.
Signed-off-by: wenxu <wenxu@ucloud.cn>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_tables_offload.h

@@ -77,7 +77,7 @@ int nft_flow_rule_offload_commit(struct net *net);
 
 int nft_chain_offload_priority(struct nft_base_chain *basechain);
 
-void nft_offload_init(void);
+int nft_offload_init(void);
 void nft_offload_exit(void);
 
 #endif

net/netfilter/nf_tables_api.c

@@ -7694,15 +7694,20 @@ static int __init nf_tables_module_init(void)
 	if (err < 0)
 		goto err4;
 
+	err = nft_offload_init();
+	if (err < 0)
+		goto err5;
+
 	/* must be last */
 	err = nfnetlink_subsys_register(&nf_tables_subsys);
 	if (err < 0)
-		goto err5;
+		goto err6;
 
 	nft_chain_route_init();
-	nft_offload_init();
 
 	return err;
+err6:
+	nft_offload_exit();
 err5:
 	rhltable_destroy(&nft_objname_ht);
 err4:
@@ -7718,8 +7723,8 @@ static int __init nf_tables_module_init(void)
 
 static void __exit nf_tables_module_exit(void)
 {
-	nft_offload_exit();
 	nfnetlink_subsys_unregister(&nf_tables_subsys);
+	nft_offload_exit();
 	unregister_netdevice_notifier(&nf_tables_flowtable_notifier);
 	nft_chain_filter_fini();
 	nft_chain_route_fini();

net/netfilter/nf_tables_offload.c

@@ -426,17 +426,58 @@ static void nft_indr_block_cb(struct net_device *dev,
 	mutex_unlock(&net->nft.commit_mutex);
 }
 
+static void nft_offload_chain_clean(struct nft_chain *chain)
+{
+	struct nft_rule *rule;
+
+	list_for_each_entry(rule, &chain->rules, list) {
+		nft_flow_offload_rule(chain, rule,
+				      NULL, FLOW_CLS_DESTROY);
+	}
+
+	nft_flow_offload_chain(chain, NULL, FLOW_BLOCK_UNBIND);
+}
+
+static int nft_offload_netdev_event(struct notifier_block *this,
+				    unsigned long event, void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	struct net *net = dev_net(dev);
+	struct nft_chain *chain;
+
+	mutex_lock(&net->nft.commit_mutex);
+	chain = __nft_offload_get_chain(dev);
+	if (chain)
+		nft_offload_chain_clean(chain);
+	mutex_unlock(&net->nft.commit_mutex);
+
+	return NOTIFY_DONE;
+}
+
 static struct flow_indr_block_ing_entry block_ing_entry = {
 	.cb	= nft_indr_block_cb,
 	.list	= LIST_HEAD_INIT(block_ing_entry.list),
 };
 
-void nft_offload_init(void)
+static struct notifier_block nft_offload_netdev_notifier = {
+	.notifier_call	= nft_offload_netdev_event,
+};
+
+int nft_offload_init(void)
 {
+	int err;
+
+	err = register_netdevice_notifier(&nft_offload_netdev_notifier);
+	if (err < 0)
+		return err;
+
 	flow_indr_add_block_ing_cb(&block_ing_entry);
+
+	return 0;
 }
 
 void nft_offload_exit(void)
 {
 	flow_indr_del_block_ing_cb(&block_ing_entry);
+	unregister_netdevice_notifier(&nft_offload_netdev_notifier);
 }