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"); 129