From 56294a39f14712f868a495f28be6b2e92f0a48c6 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 | 13 +++-
 include/net/netns/conntrack.h               |  4 ++
 net/netfilter/Kconfig                       |  8 +++
 net/netfilter/nf_conntrack_core.c           |  4 ++
 net/netfilter/nf_conntrack_ecache.c         | 92 +++++++++++++++++++++++++++++
 net/netfilter/nf_conntrack_netlink.c        | 19 ++++++
 6 files changed, 139 insertions(+), 1 deletion(-)

diff --git a/include/net/netfilter/nf_conntrack_ecache.h b/include/net/netfilter/nf_conntrack_ecache.h
index 12d967b..c2b98b6 100644
--- a/include/net/netfilter/nf_conntrack_ecache.h
+++ b/include/net/netfilter/nf_conntrack_ecache.h
@@ -70,6 +70,10 @@ 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);
 };
@@ -78,6 +82,7 @@ int nf_conntrack_register_notifier(struct net *net,
 				   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,
@@ -86,11 +91,13 @@ int nf_conntrack_eventmask_report(unsigned int eventmask, struct nf_conn *ct,
 static inline void
 nf_conntrack_event_cache(enum ip_conntrack_events event, struct nf_conn *ct)
 {
-	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)
@@ -103,10 +110,12 @@ static inline int
 nf_conntrack_event_report(enum ip_conntrack_events event, struct nf_conn *ct,
 			  u32 portid, int report)
 {
+#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);
 }
@@ -114,10 +123,12 @@ nf_conntrack_event_report(enum ip_conntrack_events event, struct nf_conn *ct,
 static inline int
 nf_conntrack_event(enum ip_conntrack_events event, struct nf_conn *ct)
 {
+#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);
 }
diff --git a/include/net/netns/conntrack.h b/include/net/netns/conntrack.h
index e469e85..1d31db8 100644
--- a/include/net/netns/conntrack.h
+++ b/include/net/netns/conntrack.h
@@ -86,7 +86,11 @@ 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)
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 63073be..08d7aab 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -136,6 +136,14 @@ config NF_CONNTRACK_TIMEOUT
 
 	  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_TIMESTAMP
 	bool  'Connection tracking timestamping'
 	depends on NETFILTER_ADVANCED
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 6bd1508..9b81c7c 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1998,6 +1998,10 @@ int nf_conntrack_init_net(struct net *net)
 	ret = nf_conntrack_proto_pernet_init(net);
 	if (ret < 0)
 		goto err_proto;
+
+#ifdef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
+	ATOMIC_INIT_NOTIFIER_HEAD(&net->ct.nf_conntrack_chain);
+#endif
 	return 0;
 
 err_proto:
diff --git a/net/netfilter/nf_conntrack_ecache.c b/net/netfilter/nf_conntrack_ecache.c
index da9df2d..e0e2a8f 100644
--- a/net/netfilter/nf_conntrack_ecache.c
+++ b/net/netfilter/nf_conntrack_ecache.c
@@ -18,6 +18,9 @@
 #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>
@@ -117,6 +120,38 @@ static void ecache_work(struct work_struct *work)
 		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 +206,52 @@ int nf_conntrack_eventmask_report(unsigned int eventmask, struct nf_conn *ct,
 	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 +302,7 @@ void nf_ct_deliver_cached_events(struct nf_conn *ct)
 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 +335,12 @@ void nf_ct_expect_event_report(enum ip_conntrack_expect_events event,
 	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 +361,15 @@ int nf_conntrack_register_notifier(struct net *net,
 	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)
 {
@@ -291,6 +382,7 @@ void nf_conntrack_unregister_notifier(struct net *net,
 	RCU_INIT_POINTER(net->ct.nf_conntrack_event_cb, NULL);
 	mutex_unlock(&nf_ct_ecache_mutex);
 }
+#endif
 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 
 int nf_ct_expect_register_notifier(struct net *net,
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 04111c1..8c741f7 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -28,6 +28,11 @@
 #include <linux/netlink.h>
 #include <linux/spinlock.h>
 #include <linux/interrupt.h>
+
+#ifdef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
+#include <linux/notifier.h>
+#endif
+
 #include <linux/slab.h>
 
 #include <linux/netfilter.h>
@@ -615,14 +620,22 @@ static size_t ctnetlink_nlmsg_size(const struct nf_conn *ct)
 	       ;
 }
 
+#ifdef CONFIG_NF_CONNTRACK_CHAIN_EVENTS
+static int ctnetlink_conntrack_event(struct notifier_block *this,
+                           unsigned long events, void *ptr)
+#else
 static int
 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 nfgenmsg *nfmsg;
 	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;
@@ -3260,9 +3273,15 @@ static int ctnetlink_stat_exp_cpu(struct net *net, struct sock *ctnl,
 }
 
 #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,
-- 
2.7.4

