netfilter: nft_chain_nat_ipv6: use generic IPv6 NAT code from core

Use the exported IPv6 NAT functions that are provided by the core. This
removes duplicated code so iptables and nft use the same NAT codebase.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/ipv6/netfilter/nft_chain_nat_ipv6.c

@@ -24,144 +24,53 @@
 #include <net/netfilter/nf_nat_l3proto.h>
 #include <net/ipv6.h>
 
-/*
- * IPv6 NAT chains
- */
-
-static unsigned int nft_nat_ipv6_fn(const struct nf_hook_ops *ops,
-			      struct sk_buff *skb,
-			      const struct net_device *in,
-			      const struct net_device *out,
-			      int (*okfn)(struct sk_buff *))
+static unsigned int nft_nat_do_chain(const struct nf_hook_ops *ops,
+				     struct sk_buff *skb,
+				     const struct net_device *in,
+				     const struct net_device *out,
+				     struct nf_conn *ct)
 {
-	enum ip_conntrack_info ctinfo;
-	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
-	struct nf_conn_nat *nat;
-	enum nf_nat_manip_type maniptype = HOOK2MANIP(ops->hooknum);
-	__be16 frag_off;
-	int hdrlen;
-	u8 nexthdr;
 	struct nft_pktinfo pkt;
-	unsigned int ret;
-
-	if (ct == NULL || nf_ct_is_untracked(ct))
-		return NF_ACCEPT;
-
-	nat = nf_ct_nat_ext_add(ct);
-	if (nat == NULL)
-		return NF_ACCEPT;
-
-	switch (ctinfo) {
-	case IP_CT_RELATED:
-	case IP_CT_RELATED + IP_CT_IS_REPLY:
-		nexthdr = ipv6_hdr(skb)->nexthdr;
-		hdrlen = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr),
-					  &nexthdr, &frag_off);
-
-		if (hdrlen >= 0 && nexthdr == IPPROTO_ICMPV6) {
-			if (!nf_nat_icmpv6_reply_translation(skb, ct, ctinfo,
-							   ops->hooknum,
-							   hdrlen))
-				return NF_DROP;
-			else
-				return NF_ACCEPT;
-		}
-		/* Fall through */
-	case IP_CT_NEW:
-		if (nf_nat_initialized(ct, maniptype))
-			break;
-
-		nft_set_pktinfo_ipv6(&pkt, ops, skb, in, out);
 
-		ret = nft_do_chain(&pkt, ops);
-		if (ret != NF_ACCEPT)
-			return ret;
-		if (!nf_nat_initialized(ct, maniptype)) {
-			ret = nf_nat_alloc_null_binding(ct, ops->hooknum);
-			if (ret != NF_ACCEPT)
-				return ret;
-		}
-	default:
-		break;
-	}
+	nft_set_pktinfo_ipv6(&pkt, ops, skb, in, out);
 
-	return nf_nat_packet(ct, ctinfo, ops->hooknum, skb);
+	return nft_do_chain(&pkt, ops);
 }
 
-static unsigned int nf_nat_ipv6_prerouting(const struct nf_hook_ops *ops,
-				      struct sk_buff *skb,
-				      const struct net_device *in,
-				      const struct net_device *out,
-				      int (*okfn)(struct sk_buff *))
+static unsigned int nft_nat_ipv6_fn(const struct nf_hook_ops *ops,
+				    struct sk_buff *skb,
+				    const struct net_device *in,
+				    const struct net_device *out,
+				    int (*okfn)(struct sk_buff *))
 {
-	struct in6_addr daddr = ipv6_hdr(skb)->daddr;
-	unsigned int ret;
-
-	ret = nft_nat_ipv6_fn(ops, skb, in, out, okfn);
-	if (ret != NF_DROP && ret != NF_STOLEN &&
-	    ipv6_addr_cmp(&daddr, &ipv6_hdr(skb)->daddr))
-		skb_dst_drop(skb);
-
-	return ret;
+	return nf_nat_ipv6_fn(ops, skb, in, out, nft_nat_do_chain);
 }
 
-static unsigned int nf_nat_ipv6_postrouting(const struct nf_hook_ops *ops,
-				       struct sk_buff *skb,
-				       const struct net_device *in,
-				       const struct net_device *out,
-				       int (*okfn)(struct sk_buff *))
+static unsigned int nft_nat_ipv6_in(const struct nf_hook_ops *ops,
+				    struct sk_buff *skb,
+				    const struct net_device *in,
+				    const struct net_device *out,
+				    int (*okfn)(struct sk_buff *))
 {
-	enum ip_conntrack_info ctinfo __maybe_unused;
-	const struct nf_conn *ct __maybe_unused;
-	unsigned int ret;
-
-	ret = nft_nat_ipv6_fn(ops, skb, in, out, okfn);
-#ifdef CONFIG_XFRM
-	if (ret != NF_DROP && ret != NF_STOLEN &&
-	    !(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
-	    (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
-		enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
-
-		if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
-				      &ct->tuplehash[!dir].tuple.dst.u3) ||
-		    (ct->tuplehash[dir].tuple.src.u.all !=
-		     ct->tuplehash[!dir].tuple.dst.u.all))
-			if (nf_xfrm_me_harder(skb, AF_INET6) < 0)
-				ret = NF_DROP;
-	}
-#endif
-	return ret;
+	return nf_nat_ipv6_in(ops, skb, in, out, nft_nat_do_chain);
 }
 
-static unsigned int nf_nat_ipv6_output(const struct nf_hook_ops *ops,
-				  struct sk_buff *skb,
-				  const struct net_device *in,
-				  const struct net_device *out,
-				  int (*okfn)(struct sk_buff *))
+static unsigned int nft_nat_ipv6_out(const struct nf_hook_ops *ops,
+				     struct sk_buff *skb,
+				     const struct net_device *in,
+				     const struct net_device *out,
+				     int (*okfn)(struct sk_buff *))
 {
-	enum ip_conntrack_info ctinfo;
-	const struct nf_conn *ct;
-	unsigned int ret;
-
-	ret = nft_nat_ipv6_fn(ops, skb, in, out, okfn);
-	if (ret != NF_DROP && ret != NF_STOLEN &&
-	    (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
-		enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+	return nf_nat_ipv6_out(ops, skb, in, out, nft_nat_do_chain);
+}
 
-		if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3,
-				      &ct->tuplehash[!dir].tuple.src.u3)) {
-			if (ip6_route_me_harder(skb))
-				ret = NF_DROP;
-		}
-#ifdef CONFIG_XFRM
-		else if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
-			 ct->tuplehash[dir].tuple.dst.u.all !=
-			 ct->tuplehash[!dir].tuple.src.u.all)
-			if (nf_xfrm_me_harder(skb, AF_INET6))
-				ret = NF_DROP;
-#endif
-	}
-	return ret;
+static unsigned int nft_nat_ipv6_local_fn(const struct nf_hook_ops *ops,
+					  struct sk_buff *skb,
+					  const struct net_device *in,
+					  const struct net_device *out,
+					  int (*okfn)(struct sk_buff *))
+{
+	return nf_nat_ipv6_local_fn(ops, skb, in, out, nft_nat_do_chain);
 }
 
 static const struct nf_chain_type nft_chain_nat_ipv6 = {
@@ -174,9 +83,9 @@ static const struct nf_chain_type nft_chain_nat_ipv6 = {
 			  (1 << NF_INET_LOCAL_OUT) |
 			  (1 << NF_INET_LOCAL_IN),
 	.hooks		= {
-		[NF_INET_PRE_ROUTING]	= nf_nat_ipv6_prerouting,
-		[NF_INET_POST_ROUTING]	= nf_nat_ipv6_postrouting,
-		[NF_INET_LOCAL_OUT]	= nf_nat_ipv6_output,
+		[NF_INET_PRE_ROUTING]	= nft_nat_ipv6_in,
+		[NF_INET_POST_ROUTING]	= nft_nat_ipv6_out,
+		[NF_INET_LOCAL_OUT]	= nft_nat_ipv6_local_fn,
 		[NF_INET_LOCAL_IN]	= nft_nat_ipv6_fn,
 	},
 };