net/netfilter/xt_REDIRECT.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * (C) 1999-2001 Paul `Rusty' Russell
   4  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
   5  * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
   6  *
   7  * Based on Rusty Russell's IPv4 REDIRECT target. Development of IPv6
   8  * NAT funded by Astaro.
   9  */
  10
  11 #include <linux/if.h>
  12 #include <linux/inetdevice.h>
  13 #include <linux/ip.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/netdevice.h>
  17 #include <linux/netfilter.h>
  18 #include <linux/types.h>
  19 #include <linux/netfilter_ipv4.h>
  20 #include <linux/netfilter_ipv6.h>
  21 #include <linux/netfilter/x_tables.h>
  22 #include <net/addrconf.h>
  23 #include <net/checksum.h>
  24 #include <net/protocol.h>
  25 #include <net/netfilter/nf_nat.h>
  26 #include <net/netfilter/nf_nat_redirect.h>
  27
  28 static unsigned int
  29 redirect_tg6(struct sk_buff *skb, const struct xt_action_param *par)
  30 {
  31         return nf_nat_redirect_ipv6(skb, par->targinfo, xt_hooknum(par));
  32 }
  33
  34 static int redirect_tg6_checkentry(const struct xt_tgchk_param *par)
  35 {
  36         const struct nf_nat_range2 *range = par->targinfo;
  37
  38         if (range->flags & NF_NAT_RANGE_MAP_IPS)
  39                 return -EINVAL;
  40
  41         return nf_ct_netns_get(par->net, par->family);
  42 }
  43
  44 static void redirect_tg_destroy(const struct xt_tgdtor_param *par)
  45 {
  46         nf_ct_netns_put(par->net, par->family);
  47 }
  48
  49 /* FIXME: Take multiple ranges --RR */
  50 static int redirect_tg4_check(const struct xt_tgchk_param *par)
  51 {
  52         const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
  53
  54         if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {
  55                 pr_debug("bad MAP_IPS.\n");
  56                 return -EINVAL;
  57         }
  58         if (mr->rangesize != 1) {
  59                 pr_debug("bad rangesize %u.\n", mr->rangesize);
  60                 return -EINVAL;
  61         }
  62         return nf_ct_netns_get(par->net, par->family);
  63 }
  64
  65 static unsigned int
  66 redirect_tg4(struct sk_buff *skb, const struct xt_action_param *par)
  67 {
  68         return nf_nat_redirect_ipv4(skb, par->targinfo, xt_hooknum(par));
  69 }
  70
  71 static struct xt_target redirect_tg_reg[] __read_mostly = {
  72         {
  73                 .name       = "REDIRECT",
  74                 .family     = NFPROTO_IPV6,
  75                 .revision   = 0,
  76                 .table      = "nat",
  77                 .checkentry = redirect_tg6_checkentry,
  78                 .destroy    = redirect_tg_destroy,
  79                 .target     = redirect_tg6,
  80                 .targetsize = sizeof(struct nf_nat_range),
  81                 .hooks      = (1 << NF_INET_PRE_ROUTING) |
  82                               (1 << NF_INET_LOCAL_OUT),
  83                 .me         = THIS_MODULE,
  84         },
  85         {
  86                 .name       = "REDIRECT",
  87                 .family     = NFPROTO_IPV4,
  88                 .revision   = 0,
  89                 .table      = "nat",
  90                 .target     = redirect_tg4,
  91                 .checkentry = redirect_tg4_check,
  92                 .destroy    = redirect_tg_destroy,
  93                 .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
  94                 .hooks      = (1 << NF_INET_PRE_ROUTING) |
  95                               (1 << NF_INET_LOCAL_OUT),
  96                 .me         = THIS_MODULE,
  97         },
  98 };
  99
 100 static int __init redirect_tg_init(void)
 101 {
 102         return xt_register_targets(redirect_tg_reg,
 103                                    ARRAY_SIZE(redirect_tg_reg));
 104 }
 105
 106 static void __exit redirect_tg_exit(void)
 107 {
 108         xt_unregister_targets(redirect_tg_reg, ARRAY_SIZE(redirect_tg_reg));
 109 }
 110
 111 module_init(redirect_tg_init);
 112 module_exit(redirect_tg_exit);
 113
 114 MODULE_LICENSE("GPL");
 115 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 116 MODULE_DESCRIPTION("Xtables: Connection redirection to localhost");
 117 MODULE_ALIAS("ip6t_REDIRECT");
 118 MODULE_ALIAS("ipt_REDIRECT");