net/netfilter/xt_REDIRECT.c

   1 /*
   2  * (C) 1999-2001 Paul `Rusty' Russell
   3  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
   4  * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * Based on Rusty Russell's IPv4 REDIRECT target. Development of IPv6
  11  * NAT funded by Astaro.
  12  */
  13
  14 #include <linux/if.h>
  15 #include <linux/inetdevice.h>
  16 #include <linux/ip.h>
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/netdevice.h>
  20 #include <linux/netfilter.h>
  21 #include <linux/types.h>
  22 #include <linux/netfilter_ipv4.h>
  23 #include <linux/netfilter_ipv6.h>
  24 #include <linux/netfilter/x_tables.h>
  25 #include <net/addrconf.h>
  26 #include <net/checksum.h>
  27 #include <net/protocol.h>
  28 #include <net/netfilter/nf_nat.h>
  29 #include <net/netfilter/nf_nat_redirect.h>
  30
  31 static unsigned int
  32 redirect_tg6(struct sk_buff *skb, const struct xt_action_param *par)
  33 {
  34         return nf_nat_redirect_ipv6(skb, par->targinfo, xt_hooknum(par));
  35 }
  36
  37 static int redirect_tg6_checkentry(const struct xt_tgchk_param *par)
  38 {
  39         const struct nf_nat_range *range = par->targinfo;
  40
  41         if (range->flags & NF_NAT_RANGE_MAP_IPS)
  42                 return -EINVAL;
  43
  44         return nf_ct_netns_get(par->net, par->family);
  45 }
  46
  47 static void redirect_tg_destroy(const struct xt_tgdtor_param *par)
  48 {
  49         nf_ct_netns_put(par->net, par->family);
  50 }
  51
  52 /* FIXME: Take multiple ranges --RR */
  53 static int redirect_tg4_check(const struct xt_tgchk_param *par)
  54 {
  55         const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
  56
  57         if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {
  58                 pr_debug("bad MAP_IPS.\n");
  59                 return -EINVAL;
  60         }
  61         if (mr->rangesize != 1) {
  62                 pr_debug("bad rangesize %u.\n", mr->rangesize);
  63                 return -EINVAL;
  64         }
  65         return nf_ct_netns_get(par->net, par->family);
  66 }
  67
  68 static unsigned int
  69 redirect_tg4(struct sk_buff *skb, const struct xt_action_param *par)
  70 {
  71         return nf_nat_redirect_ipv4(skb, par->targinfo, xt_hooknum(par));
  72 }
  73
  74 static struct xt_target redirect_tg_reg[] __read_mostly = {
  75         {
  76                 .name       = "REDIRECT",
  77                 .family     = NFPROTO_IPV6,
  78                 .revision   = 0,
  79                 .table      = "nat",
  80                 .checkentry = redirect_tg6_checkentry,
  81                 .destroy    = redirect_tg_destroy,
  82                 .target     = redirect_tg6,
  83                 .targetsize = sizeof(struct nf_nat_range),
  84                 .hooks      = (1 << NF_INET_PRE_ROUTING) |
  85                               (1 << NF_INET_LOCAL_OUT),
  86                 .me         = THIS_MODULE,
  87         },
  88         {
  89                 .name       = "REDIRECT",
  90                 .family     = NFPROTO_IPV4,
  91                 .revision   = 0,
  92                 .table      = "nat",
  93                 .target     = redirect_tg4,
  94                 .checkentry = redirect_tg4_check,
  95                 .destroy    = redirect_tg_destroy,
  96                 .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
  97                 .hooks      = (1 << NF_INET_PRE_ROUTING) |
  98                               (1 << NF_INET_LOCAL_OUT),
  99                 .me         = THIS_MODULE,
 100         },
 101 };
 102
 103 static int __init redirect_tg_init(void)
 104 {
 105         return xt_register_targets(redirect_tg_reg,
 106                                    ARRAY_SIZE(redirect_tg_reg));
 107 }
 108
 109 static void __exit redirect_tg_exit(void)
 110 {
 111         xt_unregister_targets(redirect_tg_reg, ARRAY_SIZE(redirect_tg_reg));
 112 }
 113
 114 module_init(redirect_tg_init);
 115 module_exit(redirect_tg_exit);
 116
 117 MODULE_LICENSE("GPL");
 118 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 119 MODULE_DESCRIPTION("Xtables: Connection redirection to localhost");
 120 MODULE_ALIAS("ip6t_REDIRECT");
 121 MODULE_ALIAS("ipt_REDIRECT");