net/netfilter/xt_NETMAP.c

   1 /*
   2  * (C) 2000-2001 Svenning Soerensen <svenning@post5.tele.dk>
   3  * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/ip.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/netdevice.h>
  14 #include <linux/ipv6.h>
  15 #include <linux/netfilter.h>
  16 #include <linux/netfilter_ipv4.h>
  17 #include <linux/netfilter_ipv6.h>
  18 #include <linux/netfilter/x_tables.h>
  19 #include <net/netfilter/nf_nat.h>
  20
  21 static unsigned int
  22 netmap_tg6(struct sk_buff *skb, const struct xt_action_param *par)
  23 {
  24         const struct nf_nat_range *range = par->targinfo;
  25         struct nf_nat_range newrange;
  26         struct nf_conn *ct;
  27         enum ip_conntrack_info ctinfo;
  28         union nf_inet_addr new_addr, netmask;
  29         unsigned int i;
  30
  31         ct = nf_ct_get(skb, &ctinfo);
  32         for (i = 0; i < ARRAY_SIZE(range->min_addr.ip6); i++)
  33                 netmask.ip6[i] = ~(range->min_addr.ip6[i] ^
  34                                    range->max_addr.ip6[i]);
  35
  36         if (par->hooknum == NF_INET_PRE_ROUTING ||
  37             par->hooknum == NF_INET_LOCAL_OUT)
  38                 new_addr.in6 = ipv6_hdr(skb)->daddr;
  39         else
  40                 new_addr.in6 = ipv6_hdr(skb)->saddr;
  41
  42         for (i = 0; i < ARRAY_SIZE(new_addr.ip6); i++) {
  43                 new_addr.ip6[i] &= ~netmask.ip6[i];
  44                 new_addr.ip6[i] |= range->min_addr.ip6[i] &
  45                                    netmask.ip6[i];
  46         }
  47
  48         newrange.flags  = range->flags | NF_NAT_RANGE_MAP_IPS;
  49         newrange.min_addr       = new_addr;
  50         newrange.max_addr       = new_addr;
  51         newrange.min_proto      = range->min_proto;
  52         newrange.max_proto      = range->max_proto;
  53
  54         return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(par->hooknum));
  55 }
  56
  57 static int netmap_tg6_checkentry(const struct xt_tgchk_param *par)
  58 {
  59         const struct nf_nat_range *range = par->targinfo;
  60
  61         if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
  62                 return -EINVAL;
  63         return 0;
  64 }
  65
  66 static unsigned int
  67 netmap_tg4(struct sk_buff *skb, const struct xt_action_param *par)
  68 {
  69         struct nf_conn *ct;
  70         enum ip_conntrack_info ctinfo;
  71         __be32 new_ip, netmask;
  72         const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
  73         struct nf_nat_range newrange;
  74
  75         NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING ||
  76                      par->hooknum == NF_INET_POST_ROUTING ||
  77                      par->hooknum == NF_INET_LOCAL_OUT ||
  78                      par->hooknum == NF_INET_LOCAL_IN);
  79         ct = nf_ct_get(skb, &ctinfo);
  80
  81         netmask = ~(mr->range[0].min_ip ^ mr->range[0].max_ip);
  82
  83         if (par->hooknum == NF_INET_PRE_ROUTING ||
  84             par->hooknum == NF_INET_LOCAL_OUT)
  85                 new_ip = ip_hdr(skb)->daddr & ~netmask;
  86         else
  87                 new_ip = ip_hdr(skb)->saddr & ~netmask;
  88         new_ip |= mr->range[0].min_ip & netmask;
  89
  90         memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
  91         memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
  92         newrange.flags       = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
  93         newrange.min_addr.ip = new_ip;
  94         newrange.max_addr.ip = new_ip;
  95         newrange.min_proto   = mr->range[0].min;
  96         newrange.max_proto   = mr->range[0].max;
  97
  98         /* Hand modified range to generic setup. */
  99         return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(par->hooknum));
 100 }
 101
 102 static int netmap_tg4_check(const struct xt_tgchk_param *par)
 103 {
 104         const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
 105
 106         if (!(mr->range[0].flags & NF_NAT_RANGE_MAP_IPS)) {
 107                 pr_debug("bad MAP_IPS.\n");
 108                 return -EINVAL;
 109         }
 110         if (mr->rangesize != 1) {
 111                 pr_debug("bad rangesize %u.\n", mr->rangesize);
 112                 return -EINVAL;
 113         }
 114         return 0;
 115 }
 116
 117 static struct xt_target netmap_tg_reg[] __read_mostly = {
 118         {
 119                 .name       = "NETMAP",
 120                 .family     = NFPROTO_IPV6,
 121                 .revision   = 0,
 122                 .target     = netmap_tg6,
 123                 .targetsize = sizeof(struct nf_nat_range),
 124                 .table      = "nat",
 125                 .hooks      = (1 << NF_INET_PRE_ROUTING) |
 126                               (1 << NF_INET_POST_ROUTING) |
 127                               (1 << NF_INET_LOCAL_OUT) |
 128                               (1 << NF_INET_LOCAL_IN),
 129                 .checkentry = netmap_tg6_checkentry,
 130                 .me         = THIS_MODULE,
 131         },
 132         {
 133                 .name       = "NETMAP",
 134                 .family     = NFPROTO_IPV4,
 135                 .revision   = 0,
 136                 .target     = netmap_tg4,
 137                 .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
 138                 .table      = "nat",
 139                 .hooks      = (1 << NF_INET_PRE_ROUTING) |
 140                               (1 << NF_INET_POST_ROUTING) |
 141                               (1 << NF_INET_LOCAL_OUT) |
 142                               (1 << NF_INET_LOCAL_IN),
 143                 .checkentry = netmap_tg4_check,
 144                 .me         = THIS_MODULE,
 145         },
 146 };
 147
 148 static int __init netmap_tg_init(void)
 149 {
 150         return xt_register_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
 151 }
 152
 153 static void netmap_tg_exit(void)
 154 {
 155         xt_unregister_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
 156 }
 157
 158 module_init(netmap_tg_init);
 159 module_exit(netmap_tg_exit);
 160
 161 MODULE_LICENSE("GPL");
 162 MODULE_DESCRIPTION("Xtables: 1:1 NAT mapping of subnets");
 163 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 164 MODULE_ALIAS("ip6t_NETMAP");
 165 MODULE_ALIAS("ipt_NETMAP");