net/netfilter/xt_MASQUERADE.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Masquerade.  Simple mapping which alters range to a local IP address
   3    (depending on route). */
   4
   5 /* (C) 1999-2001 Paul `Rusty' Russell
   6  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
   7  */
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9 #include <linux/module.h>
  10 #include <linux/netfilter/x_tables.h>
  11 #include <net/netfilter/nf_nat.h>
  12 #include <net/netfilter/nf_nat_masquerade.h>
  13
  14 MODULE_LICENSE("GPL");
  15 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  16 MODULE_DESCRIPTION("Xtables: automatic-address SNAT");
  17
  18 /* FIXME: Multiple targets. --RR */
  19 static int masquerade_tg_check(const struct xt_tgchk_param *par)
  20 {
  21         const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
  22
  23         if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {
  24                 pr_debug("bad MAP_IPS.\n");
  25                 return -EINVAL;
  26         }
  27         if (mr->rangesize != 1) {
  28                 pr_debug("bad rangesize %u\n", mr->rangesize);
  29                 return -EINVAL;
  30         }
  31         return nf_ct_netns_get(par->net, par->family);
  32 }
  33
  34 static unsigned int
  35 masquerade_tg(struct sk_buff *skb, const struct xt_action_param *par)
  36 {
  37         struct nf_nat_range2 range;
  38         const struct nf_nat_ipv4_multi_range_compat *mr;
  39
  40         mr = par->targinfo;
  41         range.flags = mr->range[0].flags;
  42         range.min_proto = mr->range[0].min;
  43         range.max_proto = mr->range[0].max;
  44
  45         return nf_nat_masquerade_ipv4(skb, xt_hooknum(par), &range,
  46                                       xt_out(par));
  47 }
  48
  49 static void masquerade_tg_destroy(const struct xt_tgdtor_param *par)
  50 {
  51         nf_ct_netns_put(par->net, par->family);
  52 }
  53
  54 #if IS_ENABLED(CONFIG_IPV6)
  55 static unsigned int
  56 masquerade_tg6(struct sk_buff *skb, const struct xt_action_param *par)
  57 {
  58         return nf_nat_masquerade_ipv6(skb, par->targinfo, xt_out(par));
  59 }
  60
  61 static int masquerade_tg6_checkentry(const struct xt_tgchk_param *par)
  62 {
  63         const struct nf_nat_range2 *range = par->targinfo;
  64
  65         if (range->flags & NF_NAT_RANGE_MAP_IPS)
  66                 return -EINVAL;
  67
  68         return nf_ct_netns_get(par->net, par->family);
  69 }
  70 #endif
  71
  72 static struct xt_target masquerade_tg_reg[] __read_mostly = {
  73         {
  74 #if IS_ENABLED(CONFIG_IPV6)
  75                 .name           = "MASQUERADE",
  76                 .family         = NFPROTO_IPV6,
  77                 .target         = masquerade_tg6,
  78                 .targetsize     = sizeof(struct nf_nat_range),
  79                 .table          = "nat",
  80                 .hooks          = 1 << NF_INET_POST_ROUTING,
  81                 .checkentry     = masquerade_tg6_checkentry,
  82                 .destroy        = masquerade_tg_destroy,
  83                 .me             = THIS_MODULE,
  84         }, {
  85 #endif
  86                 .name           = "MASQUERADE",
  87                 .family         = NFPROTO_IPV4,
  88                 .target         = masquerade_tg,
  89                 .targetsize     = sizeof(struct nf_nat_ipv4_multi_range_compat),
  90                 .table          = "nat",
  91                 .hooks          = 1 << NF_INET_POST_ROUTING,
  92                 .checkentry     = masquerade_tg_check,
  93                 .destroy        = masquerade_tg_destroy,
  94                 .me             = THIS_MODULE,
  95         }
  96 };
  97
  98 static int __init masquerade_tg_init(void)
  99 {
 100         int ret;
 101
 102         ret = xt_register_targets(masquerade_tg_reg,
 103                                   ARRAY_SIZE(masquerade_tg_reg));
 104         if (ret)
 105                 return ret;
 106
 107         ret = nf_nat_masquerade_inet_register_notifiers();
 108         if (ret) {
 109                 xt_unregister_targets(masquerade_tg_reg,
 110                                       ARRAY_SIZE(masquerade_tg_reg));
 111                 return ret;
 112         }
 113
 114         return ret;
 115 }
 116
 117 static void __exit masquerade_tg_exit(void)
 118 {
 119         xt_unregister_targets(masquerade_tg_reg, ARRAY_SIZE(masquerade_tg_reg));
 120         nf_nat_masquerade_inet_unregister_notifiers();
 121 }
 122
 123 module_init(masquerade_tg_init);
 124 module_exit(masquerade_tg_exit);
 125 #if IS_ENABLED(CONFIG_IPV6)
 126 MODULE_ALIAS("ip6t_MASQUERADE");
 127 #endif
 128 MODULE_ALIAS("ipt_MASQUERADE");