netfilter: nf_nat: move common nat code to nat core

Copy-pasted, both l3 helpers almost use same code here.
Split out the common part into an 'inet' helper.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_nat_core.h

@@ -11,6 +11,13 @@
 unsigned int nf_nat_packet(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
 			   unsigned int hooknum, struct sk_buff *skb);
 
+unsigned int
+nf_nat_inet_fn(void *priv, struct sk_buff *skb,
+	       const struct nf_hook_state *state,
+	       unsigned int (*do_chain)(void *priv,
+					struct sk_buff *skb,
+					const struct nf_hook_state *state));
+
 int nf_xfrm_me_harder(struct net *net, struct sk_buff *skb, unsigned int family);
 
 static inline int nf_nat_initialized(struct nf_conn *ct,

net/ipv4/netfilter/nf_nat_l3proto_ipv4.c

@@ -250,24 +250,12 @@ nf_nat_ipv4_fn(void *priv, struct sk_buff *skb,
 {
 	struct nf_conn *ct;
 	enum ip_conntrack_info ctinfo;
-	struct nf_conn_nat *nat;
-	/* maniptype == SRC for postrouting. */
-	enum nf_nat_manip_type maniptype = HOOK2MANIP(state->hook);
 
 	ct = nf_ct_get(skb, &ctinfo);
-	/* Can't track?  It's not due to stress, or conntrack would
-	 * have dropped it.  Hence it's the user's responsibilty to
-	 * packet filter it out, or implement conntrack/NAT for that
-	 * protocol. 8) --RR
-	 */
 	if (!ct)
 		return NF_ACCEPT;
 
-	nat = nfct_nat(ct);
-
-	switch (ctinfo) {
-	case IP_CT_RELATED:
-	case IP_CT_RELATED_REPLY:
+	if (ctinfo == IP_CT_RELATED || ctinfo == IP_CT_RELATED_REPLY) {
 		if (ip_hdr(skb)->protocol == IPPROTO_ICMP) {
 			if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo,
 							   state->hook))
@@ -275,48 +263,9 @@ nf_nat_ipv4_fn(void *priv, struct sk_buff *skb,
 			else
 				return NF_ACCEPT;
 		}
-		/* Only ICMPs can be IP_CT_IS_REPLY: */
-		/* fall through */
-	case IP_CT_NEW:
-		/* Seen it before?  This can happen for loopback, retrans,
-		 * or local packets.
-		 */
-		if (!nf_nat_initialized(ct, maniptype)) {
-			unsigned int ret;
-
-			ret = do_chain(priv, skb, state);
-			if (ret != NF_ACCEPT)
-				return ret;
-
-			if (nf_nat_initialized(ct, HOOK2MANIP(state->hook)))
-				break;
-
-			ret = nf_nat_alloc_null_binding(ct, state->hook);
-			if (ret != NF_ACCEPT)
-				return ret;
-		} else {
-			pr_debug("Already setup manip %s for ct %p\n",
-				 maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
-				 ct);
-			if (nf_nat_oif_changed(state->hook, ctinfo, nat,
-					       state->out))
-				goto oif_changed;
-		}
-		break;
-
-	default:
-		/* ESTABLISHED */
-		WARN_ON(ctinfo != IP_CT_ESTABLISHED &&
-			ctinfo != IP_CT_ESTABLISHED_REPLY);
-		if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
-			goto oif_changed;
 	}
 
-	return nf_nat_packet(ct, ctinfo, state->hook, skb);
-
-oif_changed:
-	nf_ct_kill_acct(ct, ctinfo, skb);
-	return NF_DROP;
+	return nf_nat_inet_fn(priv, skb, state, do_chain);
 }
 EXPORT_SYMBOL_GPL(nf_nat_ipv4_fn);
 

net/ipv6/netfilter/nf_nat_l3proto_ipv6.c

@@ -261,8 +261,6 @@ nf_nat_ipv6_fn(void *priv, struct sk_buff *skb,
 {
 	struct nf_conn *ct;
 	enum ip_conntrack_info ctinfo;
-	struct nf_conn_nat *nat;
-	enum nf_nat_manip_type maniptype = HOOK2MANIP(state->hook);
 	__be16 frag_off;
 	int hdrlen;
 	u8 nexthdr;
@@ -276,11 +274,7 @@ nf_nat_ipv6_fn(void *priv, struct sk_buff *skb,
 	if (!ct)
 		return NF_ACCEPT;
 
-	nat = nfct_nat(ct);
-
-	switch (ctinfo) {
-	case IP_CT_RELATED:
-	case IP_CT_RELATED_REPLY:
+	if (ctinfo == IP_CT_RELATED || ctinfo == IP_CT_RELATED_REPLY) {
 		nexthdr = ipv6_hdr(skb)->nexthdr;
 		hdrlen = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr),
 					  &nexthdr, &frag_off);
@@ -293,47 +287,9 @@ nf_nat_ipv6_fn(void *priv, struct sk_buff *skb,
 			else
 				return NF_ACCEPT;
 		}
-		/* Only ICMPs can be IP_CT_IS_REPLY: */
-		/* fall through */
-	case IP_CT_NEW:
-		/* Seen it before?  This can happen for loopback, retrans,
-		 * or local packets.
-		 */
-		if (!nf_nat_initialized(ct, maniptype)) {
-			unsigned int ret;
-
-			ret = do_chain(priv, skb, state);
-			if (ret != NF_ACCEPT)
-				return ret;
-
-			if (nf_nat_initialized(ct, HOOK2MANIP(state->hook)))
-				break;
-
-			ret = nf_nat_alloc_null_binding(ct, state->hook);
-			if (ret != NF_ACCEPT)
-				return ret;
-		} else {
-			pr_debug("Already setup manip %s for ct %p\n",
-				 maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
-				 ct);
-			if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
-				goto oif_changed;
-		}
-		break;
-
-	default:
-		/* ESTABLISHED */
-		WARN_ON(ctinfo != IP_CT_ESTABLISHED &&
-			ctinfo != IP_CT_ESTABLISHED_REPLY);
-		if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
-			goto oif_changed;
 	}
 
-	return nf_nat_packet(ct, ctinfo, state->hook, skb);
-
-oif_changed:
-	nf_ct_kill_acct(ct, ctinfo, skb);
-	return NF_DROP;
+	return nf_nat_inet_fn(priv, skb, state, do_chain);
 }
 EXPORT_SYMBOL_GPL(nf_nat_ipv6_fn);
 

net/netfilter/nf_nat_core.c

@@ -513,6 +513,76 @@ unsigned int nf_nat_packet(struct nf_conn *ct,
 }
 EXPORT_SYMBOL_GPL(nf_nat_packet);
 
+unsigned int
+nf_nat_inet_fn(void *priv, struct sk_buff *skb,
+	       const struct nf_hook_state *state,
+	       unsigned int (*do_chain)(void *priv,
+					struct sk_buff *skb,
+					const struct nf_hook_state *state))
+{
+	struct nf_conn *ct;
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn_nat *nat;
+	/* maniptype == SRC for postrouting. */
+	enum nf_nat_manip_type maniptype = HOOK2MANIP(state->hook);
+
+	ct = nf_ct_get(skb, &ctinfo);
+	/* Can't track?  It's not due to stress, or conntrack would
+	 * have dropped it.  Hence it's the user's responsibilty to
+	 * packet filter it out, or implement conntrack/NAT for that
+	 * protocol. 8) --RR
+	 */
+	if (!ct)
+		return NF_ACCEPT;
+
+	nat = nfct_nat(ct);
+
+	switch (ctinfo) {
+	case IP_CT_RELATED:
+	case IP_CT_RELATED_REPLY:
+		/* Only ICMPs can be IP_CT_IS_REPLY.  Fallthrough */
+	case IP_CT_NEW:
+		/* Seen it before?  This can happen for loopback, retrans,
+		 * or local packets.
+		 */
+		if (!nf_nat_initialized(ct, maniptype)) {
+			unsigned int ret;
+
+			ret = do_chain(priv, skb, state);
+			if (ret != NF_ACCEPT)
+				return ret;
+
+			if (nf_nat_initialized(ct, HOOK2MANIP(state->hook)))
+				break;
+
+			ret = nf_nat_alloc_null_binding(ct, state->hook);
+			if (ret != NF_ACCEPT)
+				return ret;
+		} else {
+			pr_debug("Already setup manip %s for ct %p (status bits 0x%lx)\n",
+				 maniptype == NF_NAT_MANIP_SRC ? "SRC" : "DST",
+				 ct, ct->status);
+			if (nf_nat_oif_changed(state->hook, ctinfo, nat,
+					       state->out))
+				goto oif_changed;
+		}
+		break;
+	default:
+		/* ESTABLISHED */
+		WARN_ON(ctinfo != IP_CT_ESTABLISHED &&
+			ctinfo != IP_CT_ESTABLISHED_REPLY);
+		if (nf_nat_oif_changed(state->hook, ctinfo, nat, state->out))
+			goto oif_changed;
+	}
+
+	return nf_nat_packet(ct, ctinfo, state->hook, skb);
+
+oif_changed:
+	nf_ct_kill_acct(ct, ctinfo, skb);
+	return NF_DROP;
+}
+EXPORT_SYMBOL_GPL(nf_nat_inet_fn);
+
 struct nf_nat_proto_clean {
 	u8	l3proto;
 	u8	l4proto;