linux/net/netfilter/xt_NETMAP.c
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   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
  21static unsigned int
  22netmap_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
  57static 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
  66static unsigned int
  67netmap_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
 102static 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
 117static 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
 148static int __init netmap_tg_init(void)
 149{
 150        return xt_register_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
 151}
 152
 153static void netmap_tg_exit(void)
 154{
 155        xt_unregister_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
 156}
 157
 158module_init(netmap_tg_init);
 159module_exit(netmap_tg_exit);
 160
 161MODULE_LICENSE("GPL");
 162MODULE_DESCRIPTION("Xtables: 1:1 NAT mapping of subnets");
 163MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 164MODULE_ALIAS("ip6t_NETMAP");
 165MODULE_ALIAS("ipt_NETMAP");
 166
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