netfilter: nf_tables: fix register ordering

We must register nfnetlink ops last, as that exposes nf_tables to
userspace.  Without this, we could theoretically get nfnetlink request
before net->nft state has been initialized.

Fixes: 99633ab29b ("netfilter: nf_tables: complete net namespace support")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_tables.h

@@ -1374,6 +1374,6 @@ struct nft_trans_flowtable {
 	(((struct nft_trans_flowtable *)trans->data)->flowtable)
 
 int __init nft_chain_filter_init(void);
-void __exit nft_chain_filter_fini(void);
+void nft_chain_filter_fini(void);
 
 #endif /* _NET_NF_TABLES_H */

net/netfilter/nf_tables_api.c

@@ -7273,21 +7273,36 @@ static int __init nf_tables_module_init(void)
 {
 	int err;
 
-	nft_chain_filter_init();
-
-	err = nf_tables_core_module_init();
+	err = register_pernet_subsys(&nf_tables_net_ops);
 	if (err < 0)
 		return err;
 
+	err = nft_chain_filter_init();
+	if (err < 0)
+		goto err1;
+
+	err = nf_tables_core_module_init();
+	if (err < 0)
+		goto err2;
+
+	err = register_netdevice_notifier(&nf_tables_flowtable_notifier);
+	if (err < 0)
+		goto err3;
+
+	/* must be last */
 	err = nfnetlink_subsys_register(&nf_tables_subsys);
 	if (err < 0)
-		goto err;
+		goto err4;
 
-	register_netdevice_notifier(&nf_tables_flowtable_notifier);
-
-	return register_pernet_subsys(&nf_tables_net_ops);
-err:
+	return err;
+err4:
+	unregister_netdevice_notifier(&nf_tables_flowtable_notifier);
+err3:
 	nf_tables_core_module_exit();
+err2:
+	nft_chain_filter_fini();
+err1:
+	unregister_pernet_subsys(&nf_tables_net_ops);
 	return err;
 }
 

net/netfilter/nft_chain_filter.c

@@ -392,7 +392,7 @@ int __init nft_chain_filter_init(void)
 	return 0;
 }
 
-void __exit nft_chain_filter_fini(void)
+void nft_chain_filter_fini(void)
 {
 	nft_chain_filter_bridge_fini();
 	nft_chain_filter_inet_fini();