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 static int redirect_tg4_check(const struct xt_tgchk_param *par)
  50 {
  51         const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
  52
  53         if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {
  54                 pr_debug("bad MAP_IPS.\n");
  55                 return -EINVAL;
  56         }
  57         if (mr->rangesize != 1) {
  58                 pr_debug("bad rangesize %u.\n", mr->rangesize);
  59                 return -EINVAL;
  60         }
  61         return nf_ct_netns_get(par->net, par->family);
  62 }
  63
  64 static unsigned int
  65 redirect_tg4(struct sk_buff *skb, const struct xt_action_param *par)
  66 {
  67         const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
  68         struct nf_nat_range2 range = {
  69                 .flags       = mr->range[0].flags,
  70                 .min_proto   = mr->range[0].min,
  71                 .max_proto   = mr->range[0].max,
  72         };
  73
  74         return nf_nat_redirect_ipv4(skb, &range, xt_hooknum(par));
  75 }
  76
  77 static struct xt_target redirect_tg_reg[] __read_mostly = {
  78         {
  79                 .name       = "REDIRECT",
  80                 .family     = NFPROTO_IPV6,
  81                 .revision   = 0,
  82                 .table      = "nat",
  83                 .checkentry = redirect_tg6_checkentry,
  84                 .destroy    = redirect_tg_destroy,
  85                 .target     = redirect_tg6,
  86                 .targetsize = sizeof(struct nf_nat_range),
  87                 .hooks      = (1 << NF_INET_PRE_ROUTING) |
  88                               (1 << NF_INET_LOCAL_OUT),
  89                 .me         = THIS_MODULE,
  90         },
  91         {
  92                 .name       = "REDIRECT",
  93                 .family     = NFPROTO_IPV4,
  94                 .revision   = 0,
  95                 .table      = "nat",
  96                 .target     = redirect_tg4,
  97                 .checkentry = redirect_tg4_check,
  98                 .destroy    = redirect_tg_destroy,
  99                 .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
 100                 .hooks      = (1 << NF_INET_PRE_ROUTING) |
 101                               (1 << NF_INET_LOCAL_OUT),
 102                 .me         = THIS_MODULE,
 103         },
 104 };
 105
 106 static int __init redirect_tg_init(void)
 107 {
 108         return xt_register_targets(redirect_tg_reg,
 109                                    ARRAY_SIZE(redirect_tg_reg));
 110 }
 111
 112 static void __exit redirect_tg_exit(void)
 113 {
 114         xt_unregister_targets(redirect_tg_reg, ARRAY_SIZE(redirect_tg_reg));
 115 }
 116
 117 module_init(redirect_tg_init);
 118 module_exit(redirect_tg_exit);
 119
 120 MODULE_LICENSE("GPL");
 121 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 122 MODULE_DESCRIPTION("Xtables: Connection redirection to localhost");
 123 MODULE_ALIAS("ip6t_REDIRECT");
 124 MODULE_ALIAS("ipt_REDIRECT");