netfilter: arptables: unregister the tables by name

and again, this time for arptables.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/linux/netfilter_arp/arp_tables.h

@@ -52,8 +52,8 @@ extern void *arpt_alloc_initial_table(const struct xt_table *);
 int arpt_register_table(struct net *net, const struct xt_table *table,
 			const struct arpt_replace *repl,
 			const struct nf_hook_ops *ops, struct xt_table **res);
-void arpt_unregister_table(struct net *net, struct xt_table *table);
-void arpt_unregister_table_pre_exit(struct net *net, struct xt_table *table,
+void arpt_unregister_table(struct net *net, const char *name);
+void arpt_unregister_table_pre_exit(struct net *net, const char *name,
 				    const struct nf_hook_ops *ops);
 extern unsigned int arpt_do_table(struct sk_buff *skb,
 				  const struct nf_hook_state *state,

net/ipv4/netfilter/arp_tables.c

@@ -1541,16 +1541,22 @@ int arpt_register_table(struct net *net,
 	return ret;
 }
 
-void arpt_unregister_table_pre_exit(struct net *net, struct xt_table *table,
+void arpt_unregister_table_pre_exit(struct net *net, const char *name,
 				    const struct nf_hook_ops *ops)
 {
-	nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks));
+	struct xt_table *table = xt_find_table(net, NFPROTO_ARP, name);
+
+	if (table)
+		nf_unregister_net_hooks(net, ops, hweight32(table->valid_hooks));
 }
 EXPORT_SYMBOL(arpt_unregister_table_pre_exit);
 
-void arpt_unregister_table(struct net *net, struct xt_table *table)
+void arpt_unregister_table(struct net *net, const char *name)
 {
-	__arpt_unregister_table(net, table);
+	struct xt_table *table = xt_find_table(net, NFPROTO_ARP, name);
+
+	if (table)
+		__arpt_unregister_table(net, table);
 }
 
 /* The built-in targets: standard (NULL) and error. */

net/ipv4/netfilter/arptable_filter.c

@@ -58,16 +58,12 @@ static int __net_init arptable_filter_table_init(struct net *net)
 
 static void __net_exit arptable_filter_net_pre_exit(struct net *net)
 {
-	if (net->ipv4.arptable_filter)
-		arpt_unregister_table_pre_exit(net, net->ipv4.arptable_filter,
-					       arpfilter_ops);
+	arpt_unregister_table_pre_exit(net, "filter", arpfilter_ops);
 }
 
 static void __net_exit arptable_filter_net_exit(struct net *net)
 {
-	if (!net->ipv4.arptable_filter)
-		return;
-	arpt_unregister_table(net, net->ipv4.arptable_filter);
+	arpt_unregister_table(net, "filter");
 	net->ipv4.arptable_filter = NULL;
 }