Date:	Fri, 28 Dec 2012 10:36:27 +0800
From:	Gao feng <gaofeng@...fujitsu.com>
To:	netfilter-devel@...r.kernel.org
Cc:	netdev@...r.kernel.org, canqunzhang@...il.com, kaber@...sh.net,
	pablo@...filter.org, ebiederm@...ssion.com,
	Gao feng <gaofeng@...fujitsu.com>
Subject: [PATCH 01/19] netfilter: move nf_conntrack initialize out of pernet operations

canqun zhang reported a panic BUG,kernel may panic when
unloading nf_conntrack module.

It's because we reset nf_ct_destroy to NULL when we deal
with init_net,it's too early.Some packets belongs to other
netns still refers to the conntrack.when these packets need
to be freed, kfree_skb will call nf_ct_destroy which is
NULL.

fix this bug by moving the nf_conntrack initialize and cleanup
codes out of the pernet operations,this job should be done
in module_init/exit.We can't use init_net to identify if
it's the right time.

Reported-by: canqun zhang <canqunzhang@...il.com>
Signed-off-by: Gao feng <gaofeng@...fujitsu.com>
---
 include/net/netfilter/nf_conntrack_core.h | 10 +++-
 net/netfilter/nf_conntrack_core.c         | 99 ++++++++++++-------------------
 net/netfilter/nf_conntrack_standalone.c   | 29 ++++++---
 3 files changed, 67 insertions(+), 71 deletions(-)

diff --git a/include/net/netfilter/nf_conntrack_core.h b/include/net/netfilter/nf_conntrack_core.h
index d8f5b9f..ec51a3c 100644
--- a/include/net/netfilter/nf_conntrack_core.h
+++ b/include/net/netfilter/nf_conntrack_core.h
@@ -25,8 +25,14 @@ extern unsigned int nf_conntrack_in(struct net *net,
 				    unsigned int hooknum,
 				    struct sk_buff *skb);
 
-extern int nf_conntrack_init(struct net *net);
-extern void nf_conntrack_cleanup(struct net *net);
+extern int nf_conntrack_init_net(struct net *net);
+extern void nf_conntrack_cleanup_net(struct net *net);
+
+extern int nf_conntrack_init_start(void);
+extern void nf_conntrack_cleanup_start(void);
+
+extern void nf_conntrack_init_end(void);
+extern void nf_conntrack_cleanup_end(void);
 
 extern int nf_conntrack_proto_init(struct net *net);
 extern void nf_conntrack_proto_fini(struct net *net);
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 08cdc71..ffb2463 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1331,18 +1331,23 @@ static int untrack_refs(void)
 	return cnt;
 }
 
-static void nf_conntrack_cleanup_init_net(void)
+void nf_conntrack_cleanup_start(void)
 {
-	while (untrack_refs() > 0)
-		schedule();
-
-#ifdef CONFIG_NF_CONNTRACK_ZONES
-	nf_ct_extend_unregister(&nf_ct_zone_extend);
-#endif
+	RCU_INIT_POINTER(ip_ct_attach, NULL);
 }
 
-static void nf_conntrack_cleanup_net(struct net *net)
+/*
+ * Mishearing the voices in his head, our hero wonders how he's
+ * supposed to kill the mall.
+ */
+void nf_conntrack_cleanup_net(struct net *net)
 {
+	/*
+	 * This makes sure all current packets have passed through
+	 * netfilter framework.  Roll on, two-stage module
+	 * delete...
+	 */
+	synchronize_net();
  i_see_dead_people:
 	nf_ct_iterate_cleanup(net, kill_all, NULL);
 	nf_ct_release_dying_list(net);
@@ -1352,6 +1357,7 @@ static void nf_conntrack_cleanup_net(struct net *net)
 	}
 
 	nf_ct_free_hashtable(net->ct.hash, net->ct.htable_size);
+	nf_conntrack_proto_fini(net);
 	nf_conntrack_helper_fini(net);
 	nf_conntrack_timeout_fini(net);
 	nf_conntrack_ecache_fini(net);
@@ -1363,24 +1369,15 @@ static void nf_conntrack_cleanup_net(struct net *net)
 	free_percpu(net->ct.stat);
 }
 
-/* Mishearing the voices in his head, our hero wonders how he's
-   supposed to kill the mall. */
-void nf_conntrack_cleanup(struct net *net)
+void nf_conntrack_cleanup_end(void)
 {
-	if (net_eq(net, &init_net))
-		RCU_INIT_POINTER(ip_ct_attach, NULL);
-
-	/* This makes sure all current packets have passed through
-	   netfilter framework.  Roll on, two-stage module
-	   delete... */
-	synchronize_net();
-	nf_conntrack_proto_fini(net);
-	nf_conntrack_cleanup_net(net);
+	RCU_INIT_POINTER(nf_ct_destroy, NULL);
+	while (untrack_refs() > 0)
+		schedule();
 
-	if (net_eq(net, &init_net)) {
-		RCU_INIT_POINTER(nf_ct_destroy, NULL);
-		nf_conntrack_cleanup_init_net();
-	}
+#ifdef CONFIG_NF_CONNTRACK_ZONES
+	nf_ct_extend_unregister(&nf_ct_zone_extend);
+#endif
 }
 
 void *nf_ct_alloc_hashtable(unsigned int *sizep, int nulls)
@@ -1473,7 +1470,7 @@ void nf_ct_untracked_status_or(unsigned long bits)
 }
 EXPORT_SYMBOL_GPL(nf_ct_untracked_status_or);
 
-static int nf_conntrack_init_init_net(void)
+int nf_conntrack_init_start(void)
 {
 	int max_factor = 8;
 	int ret, cpu;
@@ -1527,7 +1524,7 @@ err_extend:
 #define UNCONFIRMED_NULLS_VAL	((1<<30)+0)
 #define DYING_NULLS_VAL		((1<<30)+1)
 
-static int nf_conntrack_init_net(struct net *net)
+int nf_conntrack_init_net(struct net *net)
 {
 	int ret;
 
@@ -1580,7 +1577,12 @@ static int nf_conntrack_init_net(struct net *net)
 	ret = nf_conntrack_helper_init(net);
 	if (ret < 0)
 		goto err_helper;
+	ret = nf_conntrack_proto_init(net);
+	if (ret < 0)
+		goto out_proto;
 	return 0;
+out_proto:
+	nf_conntrack_helper_fini(net);
 err_helper:
 	nf_conntrack_timeout_fini(net);
 err_timeout:
@@ -1603,42 +1605,17 @@ err_stat:
 	return ret;
 }
 
+void nf_conntrack_init_end(void)
+{
+	/* For use by REJECT target */
+	RCU_INIT_POINTER(ip_ct_attach, nf_conntrack_attach);
+	RCU_INIT_POINTER(nf_ct_destroy, destroy_conntrack);
+
+	/* Howto get NAT offsets */
+	RCU_INIT_POINTER(nf_ct_nat_offset, NULL);
+}
+
 s16 (*nf_ct_nat_offset)(const struct nf_conn *ct,
 			enum ip_conntrack_dir dir,
 			u32 seq);
 EXPORT_SYMBOL_GPL(nf_ct_nat_offset);
-
-int nf_conntrack_init(struct net *net)
-{
-	int ret;
-
-	if (net_eq(net, &init_net)) {
-		ret = nf_conntrack_init_init_net();
-		if (ret < 0)
-			goto out_init_net;
-	}
-	ret = nf_conntrack_proto_init(net);
-	if (ret < 0)
-		goto out_proto;
-	ret = nf_conntrack_init_net(net);
-	if (ret < 0)
-		goto out_net;
-
-	if (net_eq(net, &init_net)) {
-		/* For use by REJECT target */
-		RCU_INIT_POINTER(ip_ct_attach, nf_conntrack_attach);
-		RCU_INIT_POINTER(nf_ct_destroy, destroy_conntrack);
-
-		/* Howto get NAT offsets */
-		RCU_INIT_POINTER(nf_ct_nat_offset, NULL);
-	}
-	return 0;
-
-out_net:
-	nf_conntrack_proto_fini(net);
-out_proto:
-	if (net_eq(net, &init_net))
-		nf_conntrack_cleanup_init_net();
-out_init_net:
-	return ret;
-}
diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
index 363285d..00bf93c 100644
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -530,11 +530,11 @@ static void nf_conntrack_standalone_fini_sysctl(struct net *net)
 }
 #endif /* CONFIG_SYSCTL */
 
-static int nf_conntrack_net_init(struct net *net)
+static int nf_conntrack_pernet_init(struct net *net)
 {
 	int ret;
 
-	ret = nf_conntrack_init(net);
+	ret = nf_conntrack_init_net(net);
 	if (ret < 0)
 		goto out_init;
 	ret = nf_conntrack_standalone_init_proc(net);
@@ -550,31 +550,44 @@ static int nf_conntrack_net_init(struct net *net)
 out_sysctl:
 	nf_conntrack_standalone_fini_proc(net);
 out_proc:
-	nf_conntrack_cleanup(net);
+	nf_conntrack_cleanup_net(net);
 out_init:
 	return ret;
 }
 
-static void nf_conntrack_net_exit(struct net *net)
+static void nf_conntrack_pernet_exit(struct net *net)
 {
 	nf_conntrack_standalone_fini_sysctl(net);
 	nf_conntrack_standalone_fini_proc(net);
-	nf_conntrack_cleanup(net);
+	nf_conntrack_cleanup_net(net);
 }
 
 static struct pernet_operations nf_conntrack_net_ops = {
-	.init = nf_conntrack_net_init,
-	.exit = nf_conntrack_net_exit,
+	.init = nf_conntrack_pernet_init,
+	.exit = nf_conntrack_pernet_exit,
 };
 
 static int __init nf_conntrack_standalone_init(void)
 {
-	return register_pernet_subsys(&nf_conntrack_net_ops);
+	int ret = nf_conntrack_init_start();
+	if (ret < 0)
+		goto out_start;
+	ret = register_pernet_subsys(&nf_conntrack_net_ops);
+	if (ret < 0)
+		goto out_pernet;
+	nf_conntrack_init_end();
+	return 0;
+out_pernet:
+	nf_conntrack_cleanup_end();
+out_start:
+	return ret;
 }
 
 static void __exit nf_conntrack_standalone_fini(void)
 {
+	nf_conntrack_cleanup_start();
 	unregister_pernet_subsys(&nf_conntrack_net_ops);
+	nf_conntrack_cleanup_end();
 }
 
 module_init(nf_conntrack_standalone_init);
-- 
1.7.11.7

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