ipvs: register hooks only with services

Keep the IPVS hooks registered in Netfilter only
while there are configured virtual services. This
saves CPU cycles while IPVS is loaded but not used.
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Reviewed-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/ip_vs.h

@@ -874,6 +874,7 @@ struct netns_ipvs {
 	struct ip_vs_stats		tot_stats;  /* Statistics & est. */
 
 	int			num_services;    /* no of virtual services */
+	int			num_services6;   /* IPv6 virtual services */
 
 	/* Trash for destinations */
 	struct list_head	dest_trash;
@@ -960,6 +961,7 @@ struct netns_ipvs {
 	 * are not supported when synchronization is enabled.
 	 */
 	unsigned int		mixed_address_family_dests;
+	unsigned int		hooks_afmask;	/* &1=AF_INET, &2=AF_INET6 */
 };
 
 #define DEFAULT_SYNC_THRESHOLD	3
@@ -1670,6 +1672,9 @@ static inline void ip_vs_unregister_conntrack(struct ip_vs_service *svc)
 #endif
 }
 
+int ip_vs_register_hooks(struct netns_ipvs *ipvs, unsigned int af);
+void ip_vs_unregister_hooks(struct netns_ipvs *ipvs, unsigned int af);
+
 static inline int
 ip_vs_dest_conn_overhead(struct ip_vs_dest *dest)
 {

net/netfilter/ipvs/ip_vs_core.c

@@ -2256,7 +2256,7 @@ ip_vs_forward_icmp_v6(void *priv, struct sk_buff *skb,
 #endif
 
 
-static const struct nf_hook_ops ip_vs_ops[] = {
+static const struct nf_hook_ops ip_vs_ops4[] = {
 	/* After packet filtering, change source only for VS/NAT */
 	{
 		.hook		= ip_vs_reply4,
@@ -2302,7 +2302,10 @@ static const struct nf_hook_ops ip_vs_ops[] = {
 		.hooknum	= NF_INET_FORWARD,
 		.priority	= 100,
 	},
+};
+
 #ifdef CONFIG_IP_VS_IPV6
+static const struct nf_hook_ops ip_vs_ops6[] = {
 	/* After packet filtering, change source only for VS/NAT */
 	{
 		.hook		= ip_vs_reply6,
@@ -2348,8 +2351,64 @@ static const struct nf_hook_ops ip_vs_ops[] = {
 		.hooknum	= NF_INET_FORWARD,
 		.priority	= 100,
 	},
-#endif
 };
+#endif
+
+int ip_vs_register_hooks(struct netns_ipvs *ipvs, unsigned int af)
+{
+	const struct nf_hook_ops *ops;
+	unsigned int count;
+	unsigned int afmask;
+	int ret = 0;
+
+	if (af == AF_INET6) {
+#ifdef CONFIG_IP_VS_IPV6
+		ops = ip_vs_ops6;
+		count = ARRAY_SIZE(ip_vs_ops6);
+		afmask = 2;
+#else
+		return -EINVAL;
+#endif
+	} else {
+		ops = ip_vs_ops4;
+		count = ARRAY_SIZE(ip_vs_ops4);
+		afmask = 1;
+	}
+
+	if (!(ipvs->hooks_afmask & afmask)) {
+		ret = nf_register_net_hooks(ipvs->net, ops, count);
+		if (ret >= 0)
+			ipvs->hooks_afmask |= afmask;
+	}
+	return ret;
+}
+
+void ip_vs_unregister_hooks(struct netns_ipvs *ipvs, unsigned int af)
+{
+	const struct nf_hook_ops *ops;
+	unsigned int count;
+	unsigned int afmask;
+
+	if (af == AF_INET6) {
+#ifdef CONFIG_IP_VS_IPV6
+		ops = ip_vs_ops6;
+		count = ARRAY_SIZE(ip_vs_ops6);
+		afmask = 2;
+#else
+		return;
+#endif
+	} else {
+		ops = ip_vs_ops4;
+		count = ARRAY_SIZE(ip_vs_ops4);
+		afmask = 1;
+	}
+
+	if (ipvs->hooks_afmask & afmask) {
+		nf_unregister_net_hooks(ipvs->net, ops, count);
+		ipvs->hooks_afmask &= ~afmask;
+	}
+}
+
 /*
  *	Initialize IP Virtual Server netns mem.
  */
@@ -2425,19 +2484,6 @@ static void __net_exit __ip_vs_cleanup_batch(struct list_head *net_list)
 	}
 }
 
-static int __net_init __ip_vs_dev_init(struct net *net)
-{
-	int ret;
-
-	ret = nf_register_net_hooks(net, ip_vs_ops, ARRAY_SIZE(ip_vs_ops));
-	if (ret < 0)
-		goto hook_fail;
-	return 0;
-
-hook_fail:
-	return ret;
-}
-
 static void __net_exit __ip_vs_dev_cleanup_batch(struct list_head *net_list)
 {
 	struct netns_ipvs *ipvs;
@@ -2446,7 +2492,8 @@ static void __net_exit __ip_vs_dev_cleanup_batch(struct list_head *net_list)
 	EnterFunction(2);
 	list_for_each_entry(net, net_list, exit_list) {
 		ipvs = net_ipvs(net);
-		nf_unregister_net_hooks(net, ip_vs_ops, ARRAY_SIZE(ip_vs_ops));
+		ip_vs_unregister_hooks(ipvs, AF_INET);
+		ip_vs_unregister_hooks(ipvs, AF_INET6);
 		ipvs->enable = 0;	/* Disable packet reception */
 		smp_wmb();
 		ip_vs_sync_net_cleanup(ipvs);
@@ -2462,7 +2509,6 @@ static struct pernet_operations ipvs_core_ops = {
 };
 
 static struct pernet_operations ipvs_core_dev_ops = {
-	.init = __ip_vs_dev_init,
 	.exit_batch = __ip_vs_dev_cleanup_batch,
 };
 

net/netfilter/ipvs/ip_vs_ctl.c

@@ -1272,6 +1272,7 @@ ip_vs_add_service(struct netns_ipvs *ipvs, struct ip_vs_service_user_kern *u,
 	struct ip_vs_scheduler *sched = NULL;
 	struct ip_vs_pe *pe = NULL;
 	struct ip_vs_service *svc = NULL;
+	int ret_hooks = -1;
 
 	/* increase the module use count */
 	if (!ip_vs_use_count_inc())
@@ -1313,6 +1314,14 @@ ip_vs_add_service(struct netns_ipvs *ipvs, struct ip_vs_service_user_kern *u,
 	}
 #endif
 
+	if ((u->af == AF_INET && !ipvs->num_services) ||
+	    (u->af == AF_INET6 && !ipvs->num_services6)) {
+		ret = ip_vs_register_hooks(ipvs, u->af);
+		if (ret < 0)
+			goto out_err;
+		ret_hooks = ret;
+	}
+
 	svc = kzalloc(sizeof(struct ip_vs_service), GFP_KERNEL);
 	if (svc == NULL) {
 		IP_VS_DBG(1, "%s(): no memory\n", __func__);
@@ -1374,6 +1383,8 @@ ip_vs_add_service(struct netns_ipvs *ipvs, struct ip_vs_service_user_kern *u,
 	/* Count only IPv4 services for old get/setsockopt interface */
 	if (svc->af == AF_INET)
 		ipvs->num_services++;
+	else if (svc->af == AF_INET6)
+		ipvs->num_services6++;
 
 	/* Hash the service into the service table */
 	ip_vs_svc_hash(svc);
@@ -1385,6 +1396,8 @@ ip_vs_add_service(struct netns_ipvs *ipvs, struct ip_vs_service_user_kern *u,
 
 
  out_err:
+	if (ret_hooks >= 0)
+		ip_vs_unregister_hooks(ipvs, u->af);
 	if (svc != NULL) {
 		ip_vs_unbind_scheduler(svc, sched);
 		ip_vs_service_free(svc);
@@ -1500,9 +1513,15 @@ static void __ip_vs_del_service(struct ip_vs_service *svc, bool cleanup)
 	struct ip_vs_pe *old_pe;
 	struct netns_ipvs *ipvs = svc->ipvs;
 
-	/* Count only IPv4 services for old get/setsockopt interface */
-	if (svc->af == AF_INET)
+	if (svc->af == AF_INET) {
 		ipvs->num_services--;
+		if (!ipvs->num_services)
+			ip_vs_unregister_hooks(ipvs, svc->af);
+	} else if (svc->af == AF_INET6) {
+		ipvs->num_services6--;
+		if (!ipvs->num_services6)
+			ip_vs_unregister_hooks(ipvs, svc->af);
+	}
 
 	ip_vs_stop_estimator(svc->ipvs, &svc->stats);