text: /*
   * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
   * Copyright (c) 2012 Intel Corporation
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms and conditions of the GNU General Public License,
   * version 2, as published by the Free Software Foundation.
   *
   */
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/list.h>
  #include <linux/skbuff.h>
  #include <linux/ip.h>
  #include <linux/netfilter.h>
  #include <linux/netfilter_ipv6.h>
  #include <linux/netfilter/nf_tables.h>
  #include <net/netfilter/nf_conntrack.h>
  #include <net/netfilter/nf_nat.h>
  #include <net/netfilter/nf_nat_core.h>
  #include <net/netfilter/nf_tables.h>
  #include <net/netfilter/nf_tables_ipv6.h>
  #include <net/netfilter/nf_nat_l3proto.h>
  #include <net/ipv6.h>
  
  /*
   * IPv6 NAT chains
   */
  
  static unsigned int nf_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 *))
  {
  	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;
  	}
  
  	return nf_nat_packet(ct, ctinfo, ops->hooknum, skb);
  }
  
  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 *))
  {
  	struct in6_addr daddr = ipv6_hdr(skb)->daddr;
  	unsigned int ret;
  
  	ret = nf_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;
  }
  
  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 *))
  {
  	enum ip_conntrack_info ctinfo __maybe_unused;
  	const struct nf_conn *ct __maybe_unused;
  	unsigned int ret;
  
  	ret = nf_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;
  }
  
  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 *))
  {
  	enum ip_conntrack_info ctinfo;
  	const struct nf_conn *ct;
  	unsigned int ret;
  
  	ret = nf_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);
  
  		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 const struct nf_chain_type nft_chain_nat_ipv6 = {
  	.name		= "nat",
  	.type		= NFT_CHAIN_T_NAT,
  	.family		= NFPROTO_IPV6,
  	.owner		= THIS_MODULE,
  	.hook_mask	= (1 << NF_INET_PRE_ROUTING) |
  			  (1 << NF_INET_POST_ROUTING) |
  			  (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_LOCAL_IN]	= nf_nat_ipv6_fn,
  	},
  };
  
  static int __init nft_chain_nat_ipv6_init(void)
  {
  	int err;
  
  	err = nft_register_chain_type(&nft_chain_nat_ipv6);
  	if (err < 0)
  		return err;
  
  	return 0;
  }
  
  static void __exit nft_chain_nat_ipv6_exit(void)
  {
  	nft_unregister_chain_type(&nft_chain_nat_ipv6);
  }
  
  module_init(nft_chain_nat_ipv6_init);
  module_exit(nft_chain_nat_ipv6_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>");
  MODULE_ALIAS_NFT_CHAIN(AF_INET6, "nat");
  