[02/25] netfilter: nf_ct_helper: allow to disable automatic helper assignment

diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h
index 5767dc2..1d18894 100644
--- a/include/net/netfilter/nf_conntrack_helper.h
+++ b/include/net/netfilter/nf_conntrack_helper.h
@@ -60,8 +60,8 @@  static inline struct nf_conn_help *nfct_help(const struct nf_conn *ct)
 	return nf_ct_ext_find(ct, NF_CT_EXT_HELPER);
 }
 
-extern int nf_conntrack_helper_init(void);
-extern void nf_conntrack_helper_fini(void);
+extern int nf_conntrack_helper_init(struct net *net);
+extern void nf_conntrack_helper_fini(struct net *net);
 
 extern int nf_conntrack_broadcast_help(struct sk_buff *skb,
 				       unsigned int protoff,
diff --git a/include/net/netns/conntrack.h b/include/net/netns/conntrack.h
index 7a911ec..a053a19 100644
--- a/include/net/netns/conntrack.h
+++ b/include/net/netns/conntrack.h
@@ -26,11 +26,14 @@  struct netns_ct {
 	int			sysctl_tstamp;
 	int			sysctl_checksum;
 	unsigned int		sysctl_log_invalid; /* Log invalid packets */
+	int			sysctl_auto_assign_helper;
+	bool			auto_assign_helper_warned;
 #ifdef CONFIG_SYSCTL
 	struct ctl_table_header	*sysctl_header;
 	struct ctl_table_header	*acct_sysctl_header;
 	struct ctl_table_header	*tstamp_sysctl_header;
 	struct ctl_table_header	*event_sysctl_header;
+	struct ctl_table_header	*helper_sysctl_header;
 #endif
 	char			*slabname;
 };
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index cf0747c..32c5909 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1336,7 +1336,6 @@  static void nf_conntrack_cleanup_init_net(void)
 	while (untrack_refs() > 0)
 		schedule();
 
-	nf_conntrack_helper_fini();
 	nf_conntrack_proto_fini();
 #ifdef CONFIG_NF_CONNTRACK_ZONES
 	nf_ct_extend_unregister(&nf_ct_zone_extend);
@@ -1354,6 +1353,7 @@  static void nf_conntrack_cleanup_net(struct net *net)
 	}
 
 	nf_ct_free_hashtable(net->ct.hash, net->ct.htable_size);
+	nf_conntrack_helper_fini(net);
 	nf_conntrack_timeout_fini(net);
 	nf_conntrack_ecache_fini(net);
 	nf_conntrack_tstamp_fini(net);
@@ -1504,10 +1504,6 @@  static int nf_conntrack_init_init_net(void)
 	if (ret < 0)
 		goto err_proto;
 
-	ret = nf_conntrack_helper_init();
-	if (ret < 0)
-		goto err_helper;
-
 #ifdef CONFIG_NF_CONNTRACK_ZONES
 	ret = nf_ct_extend_register(&nf_ct_zone_extend);
 	if (ret < 0)
@@ -1525,10 +1521,8 @@  static int nf_conntrack_init_init_net(void)
 
 #ifdef CONFIG_NF_CONNTRACK_ZONES
 err_extend:
-	nf_conntrack_helper_fini();
-#endif
-err_helper:
 	nf_conntrack_proto_fini();
+#endif
 err_proto:
 	return ret;
 }
@@ -1589,9 +1583,14 @@  static int nf_conntrack_init_net(struct net *net)
 	ret = nf_conntrack_timeout_init(net);
 	if (ret < 0)
 		goto err_timeout;
+	ret = nf_conntrack_helper_init(net);
+	if (ret < 0)
+		goto err_helper;
 
 	return 0;
 
+err_helper:
+	nf_conntrack_timeout_fini(net);
 err_timeout:
 	nf_conntrack_ecache_fini(net);
 err_ecache:
diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index 436b7cb..55234dd 100644
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -34,6 +34,66 @@  static struct hlist_head *nf_ct_helper_hash __read_mostly;
 static unsigned int nf_ct_helper_hsize __read_mostly;
 static unsigned int nf_ct_helper_count __read_mostly;
 
+static bool nf_ct_auto_assign_helper __read_mostly = true;
+module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644);
+MODULE_PARM_DESC(nf_conntrack_helper,
+		 "Enable automatic conntrack helper assignment (default 1)");
+
+#ifdef CONFIG_SYSCTL
+static struct ctl_table helper_sysctl_table[] = {
+	{
+		.procname	= "nf_conntrack_helper",
+		.data		= &init_net.ct.sysctl_auto_assign_helper,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{}
+};
+
+static int nf_conntrack_helper_init_sysctl(struct net *net)
+{
+	struct ctl_table *table;
+
+	table = kmemdup(helper_sysctl_table, sizeof(helper_sysctl_table),
+			GFP_KERNEL);
+	if (!table)
+		goto out;
+
+	table[0].data = &net->ct.sysctl_auto_assign_helper;
+
+	net->ct.helper_sysctl_header = register_net_sysctl_table(net,
+			nf_net_netfilter_sysctl_path, table);
+	if (!net->ct.helper_sysctl_header) {
+		pr_err("nf_conntrack_helper: can't register to sysctl.\n");
+		goto out_register;
+	}
+	return 0;
+
+out_register:
+	kfree(table);
+out:
+	return -ENOMEM;
+}
+
+static void nf_conntrack_helper_fini_sysctl(struct net *net)
+{
+	struct ctl_table *table;
+
+	table = net->ct.helper_sysctl_header->ctl_table_arg;
+	unregister_net_sysctl_table(net->ct.helper_sysctl_header);
+	kfree(table);
+}
+#else
+static int nf_conntrack_helper_init_sysctl(struct net *net)
+{
+	return 0;
+}
+
+static void nf_conntrack_helper_fini_sysctl(struct net *net)
+{
+}
+#endif /* CONFIG_SYSCTL */
 
 /* Stupid hash, but collision free for the default registrations of the
  * helpers currently in the kernel. */
@@ -118,6 +178,7 @@  int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
 {
 	struct nf_conntrack_helper *helper = NULL;
 	struct nf_conn_help *help;
+	struct net *net = nf_ct_net(ct);
 	int ret = 0;
 
 	if (tmpl != NULL) {
@@ -127,8 +188,17 @@  int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
 	}
 
 	help = nfct_help(ct);
-	if (helper == NULL)
+	if (net->ct.sysctl_auto_assign_helper && helper == NULL) {
 		helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
+		if (unlikely(!net->ct.auto_assign_helper_warned && helper)) {
+			pr_info("nf_conntrack: automatic helper "
+				"assignment is deprecated and it will "
+				"be removed soon. Use the iptables CT target "
+				"to attach helpers instead.\n");
+			net->ct.auto_assign_helper_warned = true;
+		}
+	}
+
 	if (helper == NULL) {
 		if (help)
 			RCU_INIT_POINTER(help->helper, NULL);
@@ -315,28 +385,44 @@  static struct nf_ct_ext_type helper_extend __read_mostly = {
 	.id	= NF_CT_EXT_HELPER,
 };
 
-int nf_conntrack_helper_init(void)
+int nf_conntrack_helper_init(struct net *net)
 {
 	int err;
 
-	nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
-	nf_ct_helper_hash = nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
-	if (!nf_ct_helper_hash)
-		return -ENOMEM;
+	net->ct.auto_assign_helper_warned = false;
+	net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper;
 
-	err = nf_ct_extend_register(&helper_extend);
+	if (net_eq(net, &init_net)) {
+		nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
+		nf_ct_helper_hash =
+			nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
+		if (!nf_ct_helper_hash)
+			return -ENOMEM;
+
+		err = nf_ct_extend_register(&helper_extend);
+		if (err < 0)
+			goto err1;
+	}
+
+	err = nf_conntrack_helper_init_sysctl(net);
 	if (err < 0)
-		goto err1;
+		goto out_sysctl;
 
 	return 0;
 
+out_sysctl:
+	if (net_eq(net, &init_net))
+		nf_ct_extend_unregister(&helper_extend);
 err1:
 	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
 	return err;
 }
 
-void nf_conntrack_helper_fini(void)
+void nf_conntrack_helper_fini(struct net *net)
 {
-	nf_ct_extend_unregister(&helper_extend);
-	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
+	nf_conntrack_helper_fini_sysctl(net);
+	if (net_eq(net, &init_net)) {
+		nf_ct_extend_unregister(&helper_extend);
+		nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
+	}
 }