1 /* Masquerade. Simple mapping which alters range to a local IP address 2 (depending on route). */ 3 4 /* (C) 1999-2001 Paul `Rusty' Russell 5 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 */ 11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 12 #include <linux/module.h> 13 #include <linux/netfilter/x_tables.h> 14 #include <net/netfilter/nf_nat.h> 15 #include <net/netfilter/nf_nat_masquerade.h> 16 17 MODULE_LICENSE("GPL"); 18 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); 19 MODULE_DESCRIPTION("Xtables: automatic-address SNAT"); 20 21 /* FIXME: Multiple targets. --RR */ 22 static int masquerade_tg_check(const struct xt_tgchk_param *par) 23 { 24 const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo; 25 26 if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) { 27 pr_debug("bad MAP_IPS.\n"); 28 return -EINVAL; 29 } 30 if (mr->rangesize != 1) { 31 pr_debug("bad rangesize %u\n", mr->rangesize); 32 return -EINVAL; 33 } 34 return nf_ct_netns_get(par->net, par->family); 35 } 36 37 static unsigned int 38 masquerade_tg(struct sk_buff *skb, const struct xt_action_param *par) 39 { 40 struct nf_nat_range2 range; 41 const struct nf_nat_ipv4_multi_range_compat *mr; 42 43 mr = par->targinfo; 44 range.flags = mr->range[0].flags; 45 range.min_proto = mr->range[0].min; 46 range.max_proto = mr->range[0].max; 47 48 return nf_nat_masquerade_ipv4(skb, xt_hooknum(par), &range, 49 xt_out(par)); 50 } 51 52 static void masquerade_tg_destroy(const struct xt_tgdtor_param *par) 53 { 54 nf_ct_netns_put(par->net, par->family); 55 } 56 57 #if IS_ENABLED(CONFIG_IPV6) 58 static unsigned int 59 masquerade_tg6(struct sk_buff *skb, const struct xt_action_param *par) 60 { 61 return nf_nat_masquerade_ipv6(skb, par->targinfo, xt_out(par)); 62 } 63 64 static int masquerade_tg6_checkentry(const struct xt_tgchk_param *par) 65 { 66 const struct nf_nat_range2 *range = par->targinfo; 67 68 if (range->flags & NF_NAT_RANGE_MAP_IPS) 69 return -EINVAL; 70 71 return nf_ct_netns_get(par->net, par->family); 72 } 73 #endif 74 75 static struct xt_target masquerade_tg_reg[] __read_mostly = { 76 { 77 #if IS_ENABLED(CONFIG_IPV6) 78 .name = "MASQUERADE", 79 .family = NFPROTO_IPV6, 80 .target = masquerade_tg6, 81 .targetsize = sizeof(struct nf_nat_range), 82 .table = "nat", 83 .hooks = 1 << NF_INET_POST_ROUTING, 84 .checkentry = masquerade_tg6_checkentry, 85 .destroy = masquerade_tg_destroy, 86 .me = THIS_MODULE, 87 }, { 88 #endif 89 .name = "MASQUERADE", 90 .family = NFPROTO_IPV4, 91 .target = masquerade_tg, 92 .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat), 93 .table = "nat", 94 .hooks = 1 << NF_INET_POST_ROUTING, 95 .checkentry = masquerade_tg_check, 96 .destroy = masquerade_tg_destroy, 97 .me = THIS_MODULE, 98 } 99 }; 100 101 static int __init masquerade_tg_init(void) 102 { 103 int ret; 104 105 ret = xt_register_targets(masquerade_tg_reg, 106 ARRAY_SIZE(masquerade_tg_reg)); 107 if (ret) 108 return ret; 109 110 ret = nf_nat_masquerade_ipv4_register_notifier(); 111 if (ret) { 112 xt_unregister_targets(masquerade_tg_reg, 113 ARRAY_SIZE(masquerade_tg_reg)); 114 return ret; 115 } 116 117 #if IS_ENABLED(CONFIG_IPV6) 118 ret = nf_nat_masquerade_ipv6_register_notifier(); 119 if (ret) { 120 xt_unregister_targets(masquerade_tg_reg, 121 ARRAY_SIZE(masquerade_tg_reg)); 122 nf_nat_masquerade_ipv4_unregister_notifier(); 123 return ret; 124 } 125 #endif 126 return ret; 127 } 128 129 static void __exit masquerade_tg_exit(void) 130 { 131 xt_unregister_targets(masquerade_tg_reg, ARRAY_SIZE(masquerade_tg_reg)); 132 nf_nat_masquerade_ipv4_unregister_notifier(); 133 #if IS_ENABLED(CONFIG_IPV6) 134 nf_nat_masquerade_ipv6_unregister_notifier(); 135 #endif 136 } 137 138 module_init(masquerade_tg_init); 139 module_exit(masquerade_tg_exit); 140 #if IS_ENABLED(CONFIG_IPV6) 141 MODULE_ALIAS("ip6t_MASQUERADE"); 142 #endif 143 MODULE_ALIAS("ipt_MASQUERADE"); 144