[NETFILTER]: nf_conntrack: add nf_copy() to safely copy members in skb

This unifies the codes to copy netfilter related datas. Before copying,
nf_copy() puts original members in destination skb.

Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 11029b9..11ab100 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -384,21 +384,10 @@
 #ifdef CONFIG_NET_SCHED
 	to->tc_index = from->tc_index;
 #endif
-#ifdef CONFIG_NETFILTER
-	/* Connection association is same as pre-frag packet */
-	nf_conntrack_put(to->nfct);
-	to->nfct = from->nfct;
-	nf_conntrack_get(to->nfct);
-	to->nfctinfo = from->nfctinfo;
+	nf_copy(to, from);
 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
 	to->ipvs_property = from->ipvs_property;
 #endif
-#ifdef CONFIG_BRIDGE_NETFILTER
-	nf_bridge_put(to->nf_bridge);
-	to->nf_bridge = from->nf_bridge;
-	nf_bridge_get(to->nf_bridge);
-#endif
-#endif
 	skb_copy_secmark(to, from);
 }
 
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 0f4434e..49523c2 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -504,23 +504,7 @@
 #ifdef CONFIG_NET_SCHED
 	to->tc_index = from->tc_index;
 #endif
-#ifdef CONFIG_NETFILTER
-	/* Connection association is same as pre-frag packet */
-	nf_conntrack_put(to->nfct);
-	to->nfct = from->nfct;
-	nf_conntrack_get(to->nfct);
-	to->nfctinfo = from->nfctinfo;
-#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
-	nf_conntrack_put_reasm(to->nfct_reasm);
-	to->nfct_reasm = from->nfct_reasm;
-	nf_conntrack_get_reasm(to->nfct_reasm);
-#endif
-#ifdef CONFIG_BRIDGE_NETFILTER
-	nf_bridge_put(to->nf_bridge);
-	to->nf_bridge = from->nf_bridge;
-	nf_bridge_get(to->nf_bridge);
-#endif
-#endif
+	nf_copy(to, from);
 	skb_copy_secmark(to, from);
 }