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 (xt_hooknum(par) == NF_INET_PRE_ROUTING ||
  37             xt_hooknum(par) == 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(xt_hooknum(par)));
  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 nf_ct_netns_get(par->net, par->family);
  64 }
  65
  66 static void netmap_tg_destroy(const struct xt_tgdtor_param *par)
  67 {
  68         nf_ct_netns_put(par->net, par->family);
  69 }
  70
  71 static unsigned int
  72 netmap_tg4(struct sk_buff *skb, const struct xt_action_param *par)
  73 {
  74         struct nf_conn *ct;
  75         enum ip_conntrack_info ctinfo;
  76         __be32 new_ip, netmask;
  77         const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
  78         struct nf_nat_range newrange;
  79
  80         WARN_ON(xt_hooknum(par) != NF_INET_PRE_ROUTING &&
  81                 xt_hooknum(par) != NF_INET_POST_ROUTING &&
  82                 xt_hooknum(par) != NF_INET_LOCAL_OUT &&
  83                 xt_hooknum(par) != NF_INET_LOCAL_IN);
  84         ct = nf_ct_get(skb, &ctinfo);
  85
  86         netmask = ~(mr->range[0].min_ip ^ mr->range[0].max_ip);
  87
  88         if (xt_hooknum(par) == NF_INET_PRE_ROUTING ||
  89             xt_hooknum(par) == NF_INET_LOCAL_OUT)
  90                 new_ip = ip_hdr(skb)->daddr & ~netmask;
  91         else
  92                 new_ip = ip_hdr(skb)->saddr & ~netmask;
  93         new_ip |= mr->range[0].min_ip & netmask;
  94
  95         memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
  96         memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
  97         newrange.flags       = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
  98         newrange.min_addr.ip = new_ip;
  99         newrange.max_addr.ip = new_ip;
 100         newrange.min_proto   = mr->range[0].min;
 101         newrange.max_proto   = mr->range[0].max;
 102
 103         /* Hand modified range to generic setup. */
 104         return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(xt_hooknum(par)));
 105 }
 106
 107 static int netmap_tg4_check(const struct xt_tgchk_param *par)
 108 {
 109         const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
 110
 111         if (!(mr->range[0].flags & NF_NAT_RANGE_MAP_IPS)) {
 112                 pr_debug("bad MAP_IPS.\n");
 113                 return -EINVAL;
 114         }
 115         if (mr->rangesize != 1) {
 116                 pr_debug("bad rangesize %u.\n", mr->rangesize);
 117                 return -EINVAL;
 118         }
 119         return nf_ct_netns_get(par->net, par->family);
 120 }
 121
 122 static struct xt_target netmap_tg_reg[] __read_mostly = {
 123         {
 124                 .name       = "NETMAP",
 125                 .family     = NFPROTO_IPV6,
 126                 .revision   = 0,
 127                 .target     = netmap_tg6,
 128                 .targetsize = sizeof(struct nf_nat_range),
 129                 .table      = "nat",
 130                 .hooks      = (1 << NF_INET_PRE_ROUTING) |
 131                               (1 << NF_INET_POST_ROUTING) |
 132                               (1 << NF_INET_LOCAL_OUT) |
 133                               (1 << NF_INET_LOCAL_IN),
 134                 .checkentry = netmap_tg6_checkentry,
 135                 .destroy    = netmap_tg_destroy,
 136                 .me         = THIS_MODULE,
 137         },
 138         {
 139                 .name       = "NETMAP",
 140                 .family     = NFPROTO_IPV4,
 141                 .revision   = 0,
 142                 .target     = netmap_tg4,
 143                 .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
 144                 .table      = "nat",
 145                 .hooks      = (1 << NF_INET_PRE_ROUTING) |
 146                               (1 << NF_INET_POST_ROUTING) |
 147                               (1 << NF_INET_LOCAL_OUT) |
 148                               (1 << NF_INET_LOCAL_IN),
 149                 .checkentry = netmap_tg4_check,
 150                 .destroy    = netmap_tg_destroy,
 151                 .me         = THIS_MODULE,
 152         },
 153 };
 154
 155 static int __init netmap_tg_init(void)
 156 {
 157         return xt_register_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
 158 }
 159
 160 static void netmap_tg_exit(void)
 161 {
 162         xt_unregister_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
 163 }
 164
 165 module_init(netmap_tg_init);
 166 module_exit(netmap_tg_exit);
 167
 168 MODULE_LICENSE("GPL");
 169 MODULE_DESCRIPTION("Xtables: 1:1 NAT mapping of subnets");
 170 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 171 MODULE_ALIAS("ip6t_NETMAP");
 172 MODULE_ALIAS("ipt_NETMAP");