kernel: add a patch to make netfilter conntrack cache routing information

Significantly improves routing / NAT performance

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

SVN-Revision: 43587

5 files changed, 512 insertions, 8 deletions

diff --git a/target/linux/generic/patches-3.14/090-backport_netfilter_rtcache.patch b/target/linux/generic/patches-3.14/090-backport_netfilter_rtcache.patch
new file mode 100644
index 0000000..ebe573f
--- /dev/null
+++ b/target/linux/generic/patches-3.14/090-backport_netfilter_rtcache.patch
@@ -0,0 +1,504 @@
+Subject: netfilter: conntrack: cache route for forwarded connections
+
+... to avoid per-packet FIB lookup if possible.
+
+The cached dst is re-used provided the input interface
+is the same as that of the previous packet in the same direction.
+
+If not, the cached dst is invalidated.
+
+For ipv6 we also need to store sernum, else dst_check doesn't work,
+pointed out by Eric Dumazet.
+
+This should speed up forwarding when conntrack is already in use
+anyway, especially when using reverse path filtering -- active RPF
+enforces two FIB lookups for each packet.
+
+Before the routing cache removal this didn't matter since RPF was performed
+only when route cache didn't yield a result; but without route cache it
+comes at higher price.
+
+Julian Anastasov suggested to add NETDEV_UNREGISTER handler to
+avoid holding on to dsts of 'frozen' conntracks.
+
+Signed-off-by: Florian Westphal <fw@strlen.de>
+
+--- a/include/net/netfilter/nf_conntrack_extend.h
++++ b/include/net/netfilter/nf_conntrack_extend.h
+@@ -30,6 +30,9 @@ enum nf_ct_ext_id {
+ #if IS_ENABLED(CONFIG_NETFILTER_SYNPROXY)
+ 	NF_CT_EXT_SYNPROXY,
+ #endif
++#if IS_ENABLED(CONFIG_NF_CONNTRACK_RTCACHE)
++	NF_CT_EXT_RTCACHE,
++#endif
+ 	NF_CT_EXT_NUM,
+ };
+ 
+@@ -43,6 +46,7 @@ enum nf_ct_ext_id {
+ #define NF_CT_EXT_TIMEOUT_TYPE struct nf_conn_timeout
+ #define NF_CT_EXT_LABELS_TYPE struct nf_conn_labels
+ #define NF_CT_EXT_SYNPROXY_TYPE struct nf_conn_synproxy
++#define NF_CT_EXT_RTCACHE_TYPE struct nf_conn_rtcache
+ 
+ /* Extensions: optional stuff which isn't permanently in struct. */
+ struct nf_ct_ext {
+--- /dev/null
++++ b/include/net/netfilter/nf_conntrack_rtcache.h
+@@ -0,0 +1,34 @@
++#include <linux/gfp.h>
++#include <net/netfilter/nf_conntrack.h>
++#include <net/netfilter/nf_conntrack_extend.h>
++
++struct dst_entry;
++
++struct nf_conn_dst_cache {
++	struct dst_entry *dst;
++	int iif;
++#if IS_ENABLED(CONFIG_NF_CONNTRACK_IPV6)
++	u32 cookie;
++#endif
++
++};
++
++struct nf_conn_rtcache {
++	struct nf_conn_dst_cache cached_dst[IP_CT_DIR_MAX];
++};
++
++static inline
++struct nf_conn_rtcache *nf_ct_rtcache_find(const struct nf_conn *ct)
++{
++#if IS_ENABLED(CONFIG_NF_CONNTRACK_RTCACHE)
++	return nf_ct_ext_find(ct, NF_CT_EXT_RTCACHE);
++#else
++	return NULL;
++#endif
++}
++
++static inline int nf_conn_rtcache_iif_get(const struct nf_conn_rtcache *rtc,
++					  enum ip_conntrack_dir dir)
++{
++	return rtc->cached_dst[dir].iif;
++}
+--- a/net/netfilter/Kconfig
++++ b/net/netfilter/Kconfig
+@@ -103,6 +103,18 @@ config NF_CONNTRACK_EVENTS
+ 
+ 	  If unsure, say `N'.
+ 
++config NF_CONNTRACK_RTCACHE
++	tristate "Cache route entries in conntrack objects"
++	depends on NETFILTER_ADVANCED
++	depends on NF_CONNTRACK
++	help
++	  If this option is enabled, the connection tracking code will
++	  cache routing information for each connection that is being
++	  forwarded, at a cost of 32 bytes per conntrack object.
++
++	  To compile it as a module, choose M here.  If unsure, say N.
++	  The module will be called nf_conntrack_rtcache.
++
+ config NF_CONNTRACK_TIMEOUT
+ 	bool  'Connection tracking timeout'
+ 	depends on NETFILTER_ADVANCED
+--- a/net/netfilter/Makefile
++++ b/net/netfilter/Makefile
+@@ -18,6 +18,9 @@ obj-$(CONFIG_NETFILTER_NETLINK_LOG) += n
+ # connection tracking
+ obj-$(CONFIG_NF_CONNTRACK) += nf_conntrack.o
+ 
++# optional conntrack route cache extension
++obj-$(CONFIG_NF_CONNTRACK_RTCACHE) += nf_conntrack_rtcache.o
++
+ # SCTP protocol connection tracking
+ obj-$(CONFIG_NF_CT_PROTO_DCCP) += nf_conntrack_proto_dccp.o
+ obj-$(CONFIG_NF_CT_PROTO_GRE) += nf_conntrack_proto_gre.o
+--- /dev/null
++++ b/net/netfilter/nf_conntrack_rtcache.c
+@@ -0,0 +1,386 @@
++/* route cache for netfilter.
++ *
++ * (C) 2014 Red Hat GmbH
++ *
++ * This program is free software; you can redistribute it and/or modify
++ * it under the terms of the GNU General Public License version 2 as
++ * published by the Free Software Foundation.
++ */
++
++#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
++
++#include <linux/types.h>
++#include <linux/netfilter.h>
++#include <linux/skbuff.h>
++#include <linux/stddef.h>
++#include <linux/kernel.h>
++#include <linux/netdevice.h>
++#include <linux/export.h>
++#include <linux/module.h>
++
++#include <net/dst.h>
++
++#include <net/netfilter/nf_conntrack.h>
++#include <net/netfilter/nf_conntrack_core.h>
++#include <net/netfilter/nf_conntrack_extend.h>
++#include <net/netfilter/nf_conntrack_rtcache.h>
++
++#if IS_ENABLED(CONFIG_NF_CONNTRACK_IPV6)
++#include <net/ip6_fib.h>
++#endif
++
++static void __nf_conn_rtcache_destroy(struct nf_conn_rtcache *rtc,
++				      enum ip_conntrack_dir dir)
++{
++	struct dst_entry *dst = rtc->cached_dst[dir].dst;
++
++	dst_release(dst);
++}
++
++static void nf_conn_rtcache_destroy(struct nf_conn *ct)
++{
++	struct nf_conn_rtcache *rtc = nf_ct_rtcache_find(ct);
++
++	if (!rtc)
++		return;
++
++	__nf_conn_rtcache_destroy(rtc, IP_CT_DIR_ORIGINAL);
++	__nf_conn_rtcache_destroy(rtc, IP_CT_DIR_REPLY);
++}
++
++static void nf_ct_rtcache_ext_add(struct nf_conn *ct)
++{
++	struct nf_conn_rtcache *rtc;
++
++	rtc = nf_ct_ext_add(ct, NF_CT_EXT_RTCACHE, GFP_ATOMIC);
++	if (rtc) {
++		rtc->cached_dst[IP_CT_DIR_ORIGINAL].iif = -1;
++		rtc->cached_dst[IP_CT_DIR_ORIGINAL].dst = NULL;
++		rtc->cached_dst[IP_CT_DIR_REPLY].iif = -1;
++		rtc->cached_dst[IP_CT_DIR_REPLY].dst = NULL;
++	}
++}
++
++static struct nf_conn_rtcache *nf_ct_rtcache_find_usable(struct nf_conn *ct)
++{
++	if (nf_ct_is_untracked(ct))
++		return NULL;
++	return nf_ct_rtcache_find(ct);
++}
++
++static struct dst_entry *
++nf_conn_rtcache_dst_get(const struct nf_conn_rtcache *rtc,
++			enum ip_conntrack_dir dir)
++{
++	return rtc->cached_dst[dir].dst;
++}
++
++static u32 nf_rtcache_get_cookie(int pf, const struct dst_entry *dst)
++{
++#if IS_ENABLED(CONFIG_NF_CONNTRACK_IPV6)
++	if (pf == NFPROTO_IPV6) {
++		const struct rt6_info *rt = (const struct rt6_info *)dst;
++
++		if (rt->rt6i_node)
++			return (u32)rt->rt6i_node->fn_sernum;
++	}
++#endif
++	return 0;
++}
++
++static void nf_conn_rtcache_dst_set(int pf,
++				    struct nf_conn_rtcache *rtc,
++				    struct dst_entry *dst,
++				    enum ip_conntrack_dir dir, int iif)
++{
++	if (rtc->cached_dst[dir].iif != iif)
++		rtc->cached_dst[dir].iif = iif;
++
++	if (rtc->cached_dst[dir].dst != dst) {
++		struct dst_entry *old;
++
++		dst_hold(dst);
++
++		old = xchg(&rtc->cached_dst[dir].dst, dst);
++		dst_release(old);
++
++#if IS_ENABLED(CONFIG_NF_CONNTRACK_IPV6)
++		if (pf == NFPROTO_IPV6)
++			rtc->cached_dst[dir].cookie =
++				nf_rtcache_get_cookie(pf, dst);
++#endif
++	}
++}
++
++static void nf_conn_rtcache_dst_obsolete(struct nf_conn_rtcache *rtc,
++					 enum ip_conntrack_dir dir)
++{
++	struct dst_entry *old;
++
++	pr_debug("Invalidate iif %d for dir %d on cache %p\n",
++		 rtc->cached_dst[dir].iif, dir, rtc);
++
++	old = xchg(&rtc->cached_dst[dir].dst, NULL);
++	dst_release(old);
++	rtc->cached_dst[dir].iif = -1;
++}
++
++static unsigned int nf_rtcache_in(const struct nf_hook_ops *ops,
++				  struct sk_buff *skb,
++				  const struct net_device *in,
++				  const struct net_device *out,
++				  int (*okfn)(struct sk_buff *))
++{
++	struct nf_conn_rtcache *rtc;
++	enum ip_conntrack_info ctinfo;
++	enum ip_conntrack_dir dir;
++	struct dst_entry *dst;
++	struct nf_conn *ct;
++	int iif;
++	u32 cookie;
++
++	if (skb_dst(skb) || skb->sk)
++		return NF_ACCEPT;
++
++	ct = nf_ct_get(skb, &ctinfo);
++	if (!ct)
++		return NF_ACCEPT;
++
++	rtc = nf_ct_rtcache_find_usable(ct);
++	if (!rtc)
++		return NF_ACCEPT;
++
++	/* if iif changes, don't use cache and let ip stack
++	 * do route lookup.
++	 *
++	 * If rp_filter is enabled it might toss skb, so
++	 * we don't want to avoid these checks.
++	 */
++	dir = CTINFO2DIR(ctinfo);
++	iif = nf_conn_rtcache_iif_get(rtc, dir);
++	if (in->ifindex != iif) {
++		pr_debug("ct %p, iif %d, cached iif %d, skip cached entry\n",
++			 ct, iif, in->ifindex);
++		return NF_ACCEPT;
++	}
++	dst = nf_conn_rtcache_dst_get(rtc, dir);
++	if (dst == NULL)
++		return NF_ACCEPT;
++
++	cookie = nf_rtcache_get_cookie(ops->pf, dst);
++
++	dst = dst_check(dst, cookie);
++	pr_debug("obtained dst %p for skb %p, cookie %d\n", dst, skb, cookie);
++	if (likely(dst))
++		skb_dst_set_noref_force(skb, dst);
++	else
++		nf_conn_rtcache_dst_obsolete(rtc, dir);
++
++	return NF_ACCEPT;
++}
++
++static unsigned int nf_rtcache_forward(const struct nf_hook_ops *ops,
++				       struct sk_buff *skb,
++				       const struct net_device *in,
++				       const struct net_device *out,
++				       int (*okfn)(struct sk_buff *))
++{
++	struct nf_conn_rtcache *rtc;
++	enum ip_conntrack_info ctinfo;
++	enum ip_conntrack_dir dir;
++	struct nf_conn *ct;
++	int iif;
++
++	ct = nf_ct_get(skb, &ctinfo);
++	if (!ct)
++		return NF_ACCEPT;
++
++	if (!nf_ct_is_confirmed(ct)) {
++		if (WARN_ON(nf_ct_rtcache_find(ct)))
++			return NF_ACCEPT;
++		nf_ct_rtcache_ext_add(ct);
++		return NF_ACCEPT;
++	}
++
++	rtc = nf_ct_rtcache_find_usable(ct);
++	if (!rtc)
++		return NF_ACCEPT;
++
++	dir = CTINFO2DIR(ctinfo);
++	iif = nf_conn_rtcache_iif_get(rtc, dir);
++	pr_debug("ct %p, skb %p, dir %d, iif %d, cached iif %d\n",
++		 ct, skb, dir, iif, in->ifindex);
++	if (likely(in->ifindex == iif))
++		return NF_ACCEPT;
++
++	nf_conn_rtcache_dst_set(ops->pf, rtc, skb_dst(skb), dir, in->ifindex);
++	return NF_ACCEPT;
++}
++
++static int nf_rtcache_dst_remove(struct nf_conn *ct, void *data)
++{
++	struct nf_conn_rtcache *rtc = nf_ct_rtcache_find(ct);
++	struct net_device *dev = data;
++
++	if (!rtc)
++		return 0;
++
++	if (dev->ifindex == rtc->cached_dst[IP_CT_DIR_ORIGINAL].iif ||
++	    dev->ifindex == rtc->cached_dst[IP_CT_DIR_REPLY].iif) {
++		nf_conn_rtcache_dst_obsolete(rtc, IP_CT_DIR_ORIGINAL);
++		nf_conn_rtcache_dst_obsolete(rtc, IP_CT_DIR_REPLY);
++	}
++
++	return 0;
++}
++
++static int nf_rtcache_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);
++
++	if (event == NETDEV_DOWN)
++		nf_ct_iterate_cleanup(net, nf_rtcache_dst_remove, dev, 0, 0);
++
++	return NOTIFY_DONE;
++}
++
++static struct notifier_block nf_rtcache_notifier = {
++	.notifier_call = nf_rtcache_netdev_event,
++};
++
++static struct nf_hook_ops rtcache_ops[] = {
++	{
++		.hook		= nf_rtcache_in,
++		.owner		= THIS_MODULE,
++		.pf		= NFPROTO_IPV4,
++		.hooknum	= NF_INET_PRE_ROUTING,
++		.priority       = NF_IP_PRI_LAST,
++	},
++	{
++		.hook           = nf_rtcache_forward,
++		.owner          = THIS_MODULE,
++		.pf             = NFPROTO_IPV4,
++		.hooknum        = NF_INET_FORWARD,
++		.priority       = NF_IP_PRI_LAST,
++	},
++#if IS_ENABLED(CONFIG_NF_CONNTRACK_IPV6)
++	{
++		.hook		= nf_rtcache_in,
++		.owner		= THIS_MODULE,
++		.pf		= NFPROTO_IPV6,
++		.hooknum	= NF_INET_PRE_ROUTING,
++		.priority       = NF_IP_PRI_LAST,
++	},
++	{
++		.hook           = nf_rtcache_forward,
++		.owner          = THIS_MODULE,
++		.pf             = NFPROTO_IPV6,
++		.hooknum        = NF_INET_FORWARD,
++		.priority       = NF_IP_PRI_LAST,
++	},
++#endif
++};
++
++static struct nf_ct_ext_type rtcache_extend __read_mostly = {
++	.len	= sizeof(struct nf_conn_rtcache),
++	.align	= __alignof__(struct nf_conn_rtcache),
++	.id	= NF_CT_EXT_RTCACHE,
++	.destroy = nf_conn_rtcache_destroy,
++};
++
++static int __init nf_conntrack_rtcache_init(void)
++{
++	int ret = nf_ct_extend_register(&rtcache_extend);
++
++	if (ret < 0) {
++		pr_err("nf_conntrack_rtcache: Unable to register extension\n");
++		return ret;
++	}
++
++	ret = nf_register_hooks(rtcache_ops, ARRAY_SIZE(rtcache_ops));
++	if (ret < 0) {
++		nf_ct_extend_unregister(&rtcache_extend);
++		return ret;
++	}
++
++	ret = register_netdevice_notifier(&nf_rtcache_notifier);
++	if (ret) {
++		nf_unregister_hooks(rtcache_ops, ARRAY_SIZE(rtcache_ops));
++		nf_ct_extend_unregister(&rtcache_extend);
++	}
++
++	return ret;
++}
++
++static int nf_rtcache_ext_remove(struct nf_conn *ct, void *data)
++{
++	struct nf_conn_rtcache *rtc = nf_ct_rtcache_find(ct);
++
++	return rtc != NULL;
++}
++
++static bool __exit nf_conntrack_rtcache_wait_for_dying(struct net *net)
++{
++	bool wait = false;
++	int cpu;
++
++	for_each_possible_cpu(cpu) {
++		struct nf_conntrack_tuple_hash *h;
++		struct hlist_nulls_node *n;
++		struct nf_conn *ct;
++
++		rcu_read_lock();
++		spin_lock_bh(&nf_conntrack_lock);
++
++		hlist_nulls_for_each_entry(h, n, &net->ct.dying, hnnode) {
++			ct = nf_ct_tuplehash_to_ctrack(h);
++			if (nf_ct_rtcache_find(ct) != NULL) {
++				wait = true;
++				break;
++			}
++		}
++		spin_unlock_bh(&nf_conntrack_lock);
++		rcu_read_unlock();
++	}
++
++	return wait;
++}
++
++static void __exit nf_conntrack_rtcache_fini(void)
++{
++	struct net *net;
++	int count = 0;
++
++	/* remove hooks so no new connections get rtcache extension */
++	nf_unregister_hooks(rtcache_ops, ARRAY_SIZE(rtcache_ops));
++
++	synchronize_net();
++
++	unregister_netdevice_notifier(&nf_rtcache_notifier);
++
++	rtnl_lock();
++
++	/* zap all conntracks with rtcache extension */
++	for_each_net(net)
++		nf_ct_iterate_cleanup(net, nf_rtcache_ext_remove, NULL, 0, 0);
++
++	for_each_net(net) {
++		/* .. and make sure they're gone from dying list, too */
++		while (nf_conntrack_rtcache_wait_for_dying(net)) {
++			msleep(200);
++			WARN_ONCE(++count > 25, "Waiting for all rtcache conntracks to go away\n");
++		}
++	}
++
++	rtnl_unlock();
++	synchronize_net();
++	nf_ct_extend_unregister(&rtcache_extend);
++}
++module_init(nf_conntrack_rtcache_init);
++module_exit(nf_conntrack_rtcache_fini);
++
++MODULE_LICENSE("GPL");
++MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
++MODULE_DESCRIPTION("Conntrack route cache extension");
diff --git a/target/linux/generic/patches-3.14/250-netfilter_depends.patch b/target/linux/generic/patches-3.14/250-netfilter_depends.patch
index 6edd9c6..e9239a7 100644
--- a/target/linux/generic/patches-3.14/250-netfilter_depends.patch
+++ b/target/linux/generic/patches-3.14/250-netfilter_depends.patch
@@ -1,6 +1,6 @@
 --- a/net/netfilter/Kconfig
 +++ b/net/netfilter/Kconfig
-@@ -195,7 +195,6 @@ config NF_CONNTRACK_FTP
+@@ -207,7 +207,6 @@ config NF_CONNTRACK_FTP
  
  config NF_CONNTRACK_H323
  	tristate "H.323 protocol support"
@@ -8,7 +8,7 @@
  	depends on NETFILTER_ADVANCED
  	help
  	  H.323 is a VoIP signalling protocol from ITU-T. As one of the most
-@@ -871,7 +870,6 @@ config NETFILTER_XT_TARGET_SECMARK
+@@ -883,7 +882,6 @@ config NETFILTER_XT_TARGET_SECMARK
  
  config NETFILTER_XT_TARGET_TCPMSS
  	tristate '"TCPMSS" target support'
diff --git a/target/linux/generic/patches-3.14/600-netfilter_layer7_2.22.patch b/target/linux/generic/patches-3.14/600-netfilter_layer7_2.22.patch
index d57ee1f..6d3db38 100644
--- a/target/linux/generic/patches-3.14/600-netfilter_layer7_2.22.patch
+++ b/target/linux/generic/patches-3.14/600-netfilter_layer7_2.22.patch
@@ -1,6 +1,6 @@
 --- a/net/netfilter/Kconfig
 +++ b/net/netfilter/Kconfig
-@@ -1345,6 +1345,27 @@ config NETFILTER_XT_MATCH_STATE
+@@ -1357,6 +1357,27 @@ config NETFILTER_XT_MATCH_STATE
  
  	  To compile it as a module, choose M here.  If unsure, say N.
  
@@ -30,7 +30,7 @@
  	depends on NETFILTER_ADVANCED
 --- a/net/netfilter/Makefile
 +++ b/net/netfilter/Makefile
-@@ -158,6 +158,7 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_RECENT) 
+@@ -161,6 +161,7 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_RECENT) 
  obj-$(CONFIG_NETFILTER_XT_MATCH_SCTP) += xt_sctp.o
  obj-$(CONFIG_NETFILTER_XT_MATCH_SOCKET) += xt_socket.o
  obj-$(CONFIG_NETFILTER_XT_MATCH_STATE) += xt_state.o
diff --git a/target/linux/generic/patches-3.14/603-netfilter_layer7_2.6.36_fix.patch b/target/linux/generic/patches-3.14/603-netfilter_layer7_2.6.36_fix.patch
index d7e2ac2..85c6f0d 100644
--- a/target/linux/generic/patches-3.14/603-netfilter_layer7_2.6.36_fix.patch
+++ b/target/linux/generic/patches-3.14/603-netfilter_layer7_2.6.36_fix.patch
@@ -1,6 +1,6 @@
 --- a/net/netfilter/Kconfig
 +++ b/net/netfilter/Kconfig
-@@ -1151,6 +1151,27 @@ config NETFILTER_XT_MATCH_L2TP
+@@ -1163,6 +1163,27 @@ config NETFILTER_XT_MATCH_L2TP
  
  	To compile it as a module, choose M here. If unsure, say N.
  
@@ -28,7 +28,7 @@
  config NETFILTER_XT_MATCH_LENGTH
  	tristate '"length" match support'
  	depends on NETFILTER_ADVANCED
-@@ -1345,26 +1366,11 @@ config NETFILTER_XT_MATCH_STATE
+@@ -1357,26 +1378,11 @@ config NETFILTER_XT_MATCH_STATE
  
  	  To compile it as a module, choose M here.  If unsure, say N.
  
diff --git a/target/linux/generic/patches-3.14/615-netfilter_add_xt_id_match.patch b/target/linux/generic/patches-3.14/615-netfilter_add_xt_id_match.patch
index c91f035..07b4bfa 100644
--- a/target/linux/generic/patches-3.14/615-netfilter_add_xt_id_match.patch
+++ b/target/linux/generic/patches-3.14/615-netfilter_add_xt_id_match.patch
@@ -21,7 +21,7 @@
 +#endif /* XT_ID_H */
 --- a/net/netfilter/Kconfig
 +++ b/net/netfilter/Kconfig
-@@ -1121,6 +1121,13 @@ config NETFILTER_XT_MATCH_IPCOMP
+@@ -1133,6 +1133,13 @@ config NETFILTER_XT_MATCH_IPCOMP
  
  	  To compile it as a module, choose M here.  If unsure, say N.
  
@@ -37,7 +37,7 @@
  	depends on NETFILTER_ADVANCED
 --- a/net/netfilter/Makefile
 +++ b/net/netfilter/Makefile
-@@ -136,6 +136,7 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_ESP) += 
+@@ -139,6 +139,7 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_ESP) += 
  obj-$(CONFIG_NETFILTER_XT_MATCH_HASHLIMIT) += xt_hashlimit.o
  obj-$(CONFIG_NETFILTER_XT_MATCH_HELPER) += xt_helper.o
  obj-$(CONFIG_NETFILTER_XT_MATCH_HL) += xt_hl.o