From 42824d4b753f84ccf885eca602c5037338b546c8 Mon Sep 17 00:00:00 2001
From: Zhi Chen <zhichen@codeaurora.org>
Date: Tue, 13 Jan 2015 14:28:18 -0800
Subject: [PATCH 3/3] net: conntrack events, support multiple registrant

Merging this patch from kernel 3.4:
This was supported by old (.28) kernel versions but removed
because of it's overhead.
But we need this feature for NA connection manager. Both ipv4
and ipv6 modules needs to register themselves to ct events.

Change-Id: Iebfb254590fb594f5baf232f849d1b7ae45ef757
Signed-off-by: Zhi Chen <zhichen@codeaurora.org>
---
 include/net/netfilter/nf_conntrack_ecache.h | 42 ++++++++++++++++++-
 include/net/netns/conntrack.h               |  4 ++
 net/netfilter/Kconfig                       |  8 ++++
 net/netfilter/nf_conntrack_core.c           |  4 ++
 net/netfilter/nf_conntrack_ecache.c         | 63 +++++++++++++++++++++++++++++
 net/netfilter/nf_conntrack_netlink.c        | 17 ++++++++
 6 files changed, 137 insertions(+), 1 deletion(-)

--- a/include/net/netfilter/nf_conntrack_ecache.h
+++ b/include/net/netfilter/nf_conntrack_ecache.h
@@ -72,6 +72,10 @@ struct nf_ct_event {
 	int report;
 };
 
+#ifdef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
+extern int nf_conntrack_register_notifier(struct net *net, struct notifier_block *nb);
+extern int nf_conntrack_unregister_notifier(struct net *net, struct notifier_block *nb);
+#else
 struct nf_ct_event_notifier {
 	int (*fcn)(unsigned int events, struct nf_ct_event *item);
 };
@@ -80,6 +84,7 @@ int nf_conntrack_register_notifier(struc
 				   struct nf_ct_event_notifier *nb);
 void nf_conntrack_unregister_notifier(struct net *net,
 				      struct nf_ct_event_notifier *nb);
+#endif
 
 void nf_ct_deliver_cached_events(struct nf_conn *ct);
 int nf_conntrack_eventmask_report(unsigned int eventmask, struct nf_conn *ct,
@@ -105,11 +110,13 @@ static inline void
 nf_conntrack_event_cache(enum ip_conntrack_events event, struct nf_conn *ct)
 {
 #ifdef CONFIG_NF_CONNTRACK_EVENTS
-	struct net *net = nf_ct_net(ct);
 	struct nf_conntrack_ecache *e;
+#ifndef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
+	struct net *net = nf_ct_net(ct);
 
 	if (!rcu_access_pointer(net->ct.nf_conntrack_event_cb))
 		return;
+#endif
 
 	e = nf_ct_ecache_find(ct);
 	if (e == NULL)
@@ -124,10 +131,12 @@ nf_conntrack_event_report(enum ip_conntr
 			  u32 portid, int report)
 {
 #ifdef CONFIG_NF_CONNTRACK_EVENTS
+#ifndef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
 	const struct net *net = nf_ct_net(ct);
 
 	if (!rcu_access_pointer(net->ct.nf_conntrack_event_cb))
 		return 0;
+#endif
 
 	return nf_conntrack_eventmask_report(1 << event, ct, portid, report);
 #else
@@ -139,10 +148,12 @@ static inline int
 nf_conntrack_event(enum ip_conntrack_events event, struct nf_conn *ct)
 {
 #ifdef CONFIG_NF_CONNTRACK_EVENTS
+#ifndef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
 	const struct net *net = nf_ct_net(ct);
 
 	if (!rcu_access_pointer(net->ct.nf_conntrack_event_cb))
 		return 0;
+#endif
 
 	return nf_conntrack_eventmask_report(1 << event, ct, 0, 0);
 #else
--- a/include/net/netns/conntrack.h
+++ b/include/net/netns/conntrack.h
@@ -112,7 +112,11 @@ struct netns_ct {
 
 	struct ct_pcpu __percpu *pcpu_lists;
 	struct ip_conntrack_stat __percpu *stat;
+#ifdef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
+	struct atomic_notifier_head nf_conntrack_chain;
+#else
 	struct nf_ct_event_notifier __rcu *nf_conntrack_event_cb;
+#endif
 	struct nf_exp_event_notifier __rcu *nf_expect_event_cb;
 	struct nf_ip_net	nf_ct_proto;
 #if defined(CONFIG_NF_CONNTRACK_LABELS)
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -135,6 +135,14 @@ config NF_CONNTRACK_EVENTS
 
 	  If unsure, say `N'.
 
+config NF_CONNTRACK_CHAIN_EVENTS
+	bool "Register multiple callbacks to ct events"
+	depends on NF_CONNTRACK_EVENTS
+	help
+	  Support multiple registrations.
+
+	  If unsure, say `N'.
+
 config NF_CONNTRACK_TIMEOUT
 	bool  'Connection tracking timeout'
 	depends on NETFILTER_ADVANCED
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -2573,6 +2573,9 @@ int nf_conntrack_init_net(struct net *ne
 	nf_conntrack_helper_pernet_init(net);
 	nf_conntrack_proto_pernet_init(net);
 
+#ifdef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
+	ATOMIC_INIT_NOTIFIER_HEAD(&net->ct.nf_conntrack_chain);
+#endif
 	return 0;
 
 err_expect:
--- a/net/netfilter/nf_conntrack_ecache.c
+++ b/net/netfilter/nf_conntrack_ecache.c
@@ -17,6 +17,9 @@
 #include <linux/stddef.h>
 #include <linux/err.h>
 #include <linux/percpu.h>
+#ifdef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
+#include <linux/notifier.h>
+#endif
 #include <linux/kernel.h>
 #include <linux/netdevice.h>
 #include <linux/slab.h>
@@ -116,7 +119,35 @@ static void ecache_work(struct work_stru
 	if (delay >= 0)
 		schedule_delayed_work(&ctnet->ecache_dwork, delay);
 }
+#ifdef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
+int nf_conntrack_eventmask_report(unsigned int eventmask, struct nf_conn *ct,
+				  u32 portid, int report)
+{
+	struct nf_conntrack_ecache *e;
+	struct net *net = nf_ct_net(ct);
+
+	e = nf_ct_ecache_find(ct);
+	if (e == NULL)
+		return 0;
+
+	if (nf_ct_is_confirmed(ct)) {
+		struct nf_ct_event item = {
+			.ct = ct,
+			.portid	= e->portid ? e->portid : portid,
+			.report = report
+		};
+		/* This is a resent of a destroy event? If so, skip missed */
+		unsigned long missed = e->portid ? 0 : e->missed;
+
+		if (!((eventmask | missed) & e->ctmask))
+			return 0;
 
+		atomic_notifier_call_chain(&net->ct.nf_conntrack_chain, eventmask | missed, &item);
+	}
+
+	return 0;
+}
+#else
 int nf_conntrack_eventmask_report(unsigned int eventmask, struct nf_conn *ct,
 				  u32 portid, int report)
 {
@@ -171,10 +202,52 @@ out_unlock:
 	rcu_read_unlock();
 	return ret;
 }
+#endif
 EXPORT_SYMBOL_GPL(nf_conntrack_eventmask_report);
 
 /* deliver cached events and clear cache entry - must be called with locally
  * disabled softirqs */
+#ifdef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
+void nf_ct_deliver_cached_events(struct nf_conn *ct)
+{
+	unsigned long events, missed;
+	struct nf_conntrack_ecache *e;
+	struct nf_ct_event item;
+	struct net *net = nf_ct_net(ct);
+
+	e = nf_ct_ecache_find(ct);
+	if (e == NULL)
+		return;
+
+	events = xchg(&e->cache, 0);
+
+	if (!nf_ct_is_confirmed(ct) || nf_ct_is_dying(ct) || !events)
+		return;
+
+	/* We make a copy of the missed event cache without taking
+	 * the lock, thus we may send missed events twice. However,
+	 * this does not harm and it happens very rarely. */
+	missed = e->missed;
+
+	if (!((events | missed) & e->ctmask))
+		return;
+
+	item.ct = ct;
+	item.portid = 0;
+	item.report = 0;
+
+	atomic_notifier_call_chain(&net->ct.nf_conntrack_chain,
+			events | missed,
+			&item);
+
+	if (likely(!missed))
+		return;
+
+	spin_lock_bh(&ct->lock);
+		e->missed &= ~missed;
+	spin_unlock_bh(&ct->lock);
+}
+#else
 void nf_ct_deliver_cached_events(struct nf_conn *ct)
 {
 	struct net *net = nf_ct_net(ct);
@@ -225,6 +298,7 @@ void nf_ct_deliver_cached_events(struct
 out_unlock:
 	rcu_read_unlock();
 }
+#endif
 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
 
 void nf_ct_expect_event_report(enum ip_conntrack_expect_events event,
@@ -257,6 +331,13 @@ out_unlock:
 	rcu_read_unlock();
 }
 
+#ifdef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
+int nf_conntrack_register_notifier(struct net *net,
+				   struct notifier_block *nb)
+{
+        return atomic_notifier_chain_register(&net->ct.nf_conntrack_chain, nb);
+}
+#else
 int nf_conntrack_register_notifier(struct net *net,
 				   struct nf_ct_event_notifier *new)
 {
@@ -277,8 +358,15 @@ out_unlock:
 	mutex_unlock(&nf_ct_ecache_mutex);
 	return ret;
 }
+#endif
 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 
+#ifdef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
+int nf_conntrack_unregister_notifier(struct net *net, struct notifier_block *nb)
+{
+	return atomic_notifier_chain_unregister(&net->ct.nf_conntrack_chain, nb);
+}
+#else
 void nf_conntrack_unregister_notifier(struct net *net,
 				      struct nf_ct_event_notifier *new)
 {
@@ -292,6 +380,7 @@ void nf_conntrack_unregister_notifier(st
 	mutex_unlock(&nf_ct_ecache_mutex);
 	/* synchronize_rcu() is called from ctnetlink_exit. */
 }
+#endif
 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 
 int nf_ct_expect_register_notifier(struct net *net,
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -675,12 +675,19 @@ static size_t ctnetlink_nlmsg_size(const
 }
 
 static int
+#ifdef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
+ctnetlink_conntrack_event(struct notifier_block *this, unsigned long events, void *ptr)
+#else
 ctnetlink_conntrack_event(unsigned int events, struct nf_ct_event *item)
+#endif
 {
 	const struct nf_conntrack_zone *zone;
 	struct net *net;
 	struct nlmsghdr *nlh;
 	struct nlattr *nest_parms;
+#ifdef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
+	struct nf_ct_event *item = (struct nf_ct_event *)ptr;
+#endif
 	struct nf_conn *ct = item->ct;
 	struct sk_buff *skb;
 	unsigned int type;
@@ -3472,9 +3479,15 @@ static int ctnetlink_stat_exp_cpu(struct
 }
 
 #ifdef CONFIG_NF_CONNTRACK_EVENTS
+#ifdef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
+static struct notifier_block ctnl_notifier = {
+	.notifier_call = ctnetlink_conntrack_event,
+};
+#else
 static struct nf_ct_event_notifier ctnl_notifier = {
 	.fcn = ctnetlink_conntrack_event,
 };
+#endif
 
 static struct nf_exp_event_notifier ctnl_notifier_exp = {
 	.fcn = ctnetlink_expect_event,
