net/ipv6/netfilter/nft_chain_nat_ipv6.c

   1 /*
   2  * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
   3  * Copyright (c) 2012 Intel Corporation
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms and conditions of the GNU General Public License,
   7  * version 2, as published by the Free Software Foundation.
   8  *
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/init.h>
  13 #include <linux/list.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/ip.h>
  16 #include <linux/netfilter.h>
  17 #include <linux/netfilter_ipv6.h>
  18 #include <linux/netfilter/nf_tables.h>
  19 #include <net/netfilter/nf_conntrack.h>
  20 #include <net/netfilter/nf_nat.h>
  21 #include <net/netfilter/nf_nat_core.h>
  22 #include <net/netfilter/nf_tables.h>
  23 #include <net/netfilter/nf_tables_ipv6.h>
  24 #include <net/netfilter/nf_nat_l3proto.h>
  25 #include <net/ipv6.h>
  26
  27 /*
  28  * IPv6 NAT chains
  29  */
  30
  31 static unsigned int nf_nat_ipv6_fn(const struct nf_hook_ops *ops,
  32                               struct sk_buff *skb,
  33                               const struct net_device *in,
  34                               const struct net_device *out,
  35                               int (*okfn)(struct sk_buff *))
  36 {
  37         enum ip_conntrack_info ctinfo;
  38         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
  39         struct nf_conn_nat *nat;
  40         enum nf_nat_manip_type maniptype = HOOK2MANIP(ops->hooknum);
  41         __be16 frag_off;
  42         int hdrlen;
  43         u8 nexthdr;
  44         struct nft_pktinfo pkt;
  45         unsigned int ret;
  46
  47         if (ct == NULL || nf_ct_is_untracked(ct))
  48                 return NF_ACCEPT;
  49
  50         nat = nfct_nat(ct);
  51         if (nat == NULL) {
  52                 /* Conntrack module was loaded late, can't add extension. */
  53                 if (nf_ct_is_confirmed(ct))
  54                         return NF_ACCEPT;
  55                 nat = nf_ct_ext_add(ct, NF_CT_EXT_NAT, GFP_ATOMIC);
  56                 if (nat == NULL)
  57                         return NF_ACCEPT;
  58         }
  59
  60         switch (ctinfo) {
  61         case IP_CT_RELATED:
  62         case IP_CT_RELATED + IP_CT_IS_REPLY:
  63                 nexthdr = ipv6_hdr(skb)->nexthdr;
  64                 hdrlen = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr),
  65                                           &nexthdr, &frag_off);
  66
  67                 if (hdrlen >= 0 && nexthdr == IPPROTO_ICMPV6) {
  68                         if (!nf_nat_icmpv6_reply_translation(skb, ct, ctinfo,
  69                                                            ops->hooknum,
  70                                                            hdrlen))
  71                                 return NF_DROP;
  72                         else
  73                                 return NF_ACCEPT;
  74                 }
  75                 /* Fall through */
  76         case IP_CT_NEW:
  77                 if (nf_nat_initialized(ct, maniptype))
  78                         break;
  79
  80                 nft_set_pktinfo_ipv6(&pkt, ops, skb, in, out);
  81
  82                 ret = nft_do_chain_pktinfo(&pkt, ops);
  83                 if (ret != NF_ACCEPT)
  84                         return ret;
  85                 if (!nf_nat_initialized(ct, maniptype)) {
  86                         ret = nf_nat_alloc_null_binding(ct, ops->hooknum);
  87                         if (ret != NF_ACCEPT)
  88                                 return ret;
  89                 }
  90         default:
  91                 break;
  92         }
  93
  94         return nf_nat_packet(ct, ctinfo, ops->hooknum, skb);
  95 }
  96
  97 static unsigned int nf_nat_ipv6_prerouting(const struct nf_hook_ops *ops,
  98                                       struct sk_buff *skb,
  99                                       const struct net_device *in,
 100                                       const struct net_device *out,
 101                                       int (*okfn)(struct sk_buff *))
 102 {
 103         struct in6_addr daddr = ipv6_hdr(skb)->daddr;
 104         unsigned int ret;
 105
 106         ret = nf_nat_ipv6_fn(ops, skb, in, out, okfn);
 107         if (ret != NF_DROP && ret != NF_STOLEN &&
 108             ipv6_addr_cmp(&daddr, &ipv6_hdr(skb)->daddr))
 109                 skb_dst_drop(skb);
 110
 111         return ret;
 112 }
 113
 114 static unsigned int nf_nat_ipv6_postrouting(const struct nf_hook_ops *ops,
 115                                        struct sk_buff *skb,
 116                                        const struct net_device *in,
 117                                        const struct net_device *out,
 118                                        int (*okfn)(struct sk_buff *))
 119 {
 120         enum ip_conntrack_info ctinfo __maybe_unused;
 121         const struct nf_conn *ct __maybe_unused;
 122         unsigned int ret;
 123
 124         ret = nf_nat_ipv6_fn(ops, skb, in, out, okfn);
 125 #ifdef CONFIG_XFRM
 126         if (ret != NF_DROP && ret != NF_STOLEN &&
 127             !(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
 128             (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
 129                 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 130
 131                 if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
 132                                       &ct->tuplehash[!dir].tuple.dst.u3) ||
 133                     (ct->tuplehash[dir].tuple.src.u.all !=
 134                      ct->tuplehash[!dir].tuple.dst.u.all))
 135                         if (nf_xfrm_me_harder(skb, AF_INET6) < 0)
 136                                 ret = NF_DROP;
 137         }
 138 #endif
 139         return ret;
 140 }
 141
 142 static unsigned int nf_nat_ipv6_output(const struct nf_hook_ops *ops,
 143                                   struct sk_buff *skb,
 144                                   const struct net_device *in,
 145                                   const struct net_device *out,
 146                                   int (*okfn)(struct sk_buff *))
 147 {
 148         enum ip_conntrack_info ctinfo;
 149         const struct nf_conn *ct;
 150         unsigned int ret;
 151
 152         ret = nf_nat_ipv6_fn(ops, skb, in, out, okfn);
 153         if (ret != NF_DROP && ret != NF_STOLEN &&
 154             (ct = nf_ct_get(skb, &ctinfo)) != NULL) {
 155                 enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 156
 157                 if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3,
 158                                       &ct->tuplehash[!dir].tuple.src.u3)) {
 159                         if (ip6_route_me_harder(skb))
 160                                 ret = NF_DROP;
 161                 }
 162 #ifdef CONFIG_XFRM
 163                 else if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
 164                          ct->tuplehash[dir].tuple.dst.u.all !=
 165                          ct->tuplehash[!dir].tuple.src.u.all)
 166                         if (nf_xfrm_me_harder(skb, AF_INET6))
 167                                 ret = NF_DROP;
 168 #endif
 169         }
 170         return ret;
 171 }
 172
 173 static struct nf_chain_type nft_chain_nat_ipv6 = {
 174         .family         = NFPROTO_IPV6,
 175         .name           = "nat",
 176         .type           = NFT_CHAIN_T_NAT,
 177         .hook_mask      = (1 << NF_INET_PRE_ROUTING) |
 178                           (1 << NF_INET_POST_ROUTING) |
 179                           (1 << NF_INET_LOCAL_OUT) |
 180                           (1 << NF_INET_LOCAL_IN),
 181         .fn             = {
 182                 [NF_INET_PRE_ROUTING]   = nf_nat_ipv6_prerouting,
 183                 [NF_INET_POST_ROUTING]  = nf_nat_ipv6_postrouting,
 184                 [NF_INET_LOCAL_OUT]     = nf_nat_ipv6_output,
 185                 [NF_INET_LOCAL_IN]      = nf_nat_ipv6_fn,
 186         },
 187         .me             = THIS_MODULE,
 188 };
 189
 190 static int __init nft_chain_nat_ipv6_init(void)
 191 {
 192         int err;
 193
 194         err = nft_register_chain_type(&nft_chain_nat_ipv6);
 195         if (err < 0)
 196                 return err;
 197
 198         return 0;
 199 }
 200
 201 static void __exit nft_chain_nat_ipv6_exit(void)
 202 {
 203         nft_unregister_chain_type(&nft_chain_nat_ipv6);
 204 }
 205
 206 module_init(nft_chain_nat_ipv6_init);
 207 module_exit(nft_chain_nat_ipv6_exit);
 208
 209 MODULE_LICENSE("GPL");
 210 MODULE_AUTHOR("Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>");
 211 MODULE_ALIAS_NFT_CHAIN(AF_INET6, "nat");