net/netfilter/xt_MASQUERADE.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /* Masquerade.  Simple mapping which alters range to a local IP address
0003    (depending on route). */
0004
0005 /* (C) 1999-2001 Paul `Rusty' Russell
0006  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
0007  */
0008 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0009 #include <linux/module.h>
0010 #include <linux/netfilter/x_tables.h>
0011 #include <net/netfilter/nf_nat.h>
0012 #include <net/netfilter/nf_nat_masquerade.h>
0013
0014 MODULE_LICENSE("GPL");
0015 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
0016 MODULE_DESCRIPTION("Xtables: automatic-address SNAT");
0017
0018 /* FIXME: Multiple targets. --RR */
0019 static int masquerade_tg_check(const struct xt_tgchk_param *par)
0020 {
0021     const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
0022
0023     if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {
0024         pr_debug("bad MAP_IPS.\n");
0025         return -EINVAL;
0026     }
0027     if (mr->rangesize != 1) {
0028         pr_debug("bad rangesize %u\n", mr->rangesize);
0029         return -EINVAL;
0030     }
0031     return nf_ct_netns_get(par->net, par->family);
0032 }
0033
0034 static unsigned int
0035 masquerade_tg(struct sk_buff *skb, const struct xt_action_param *par)
0036 {
0037     struct nf_nat_range2 range;
0038     const struct nf_nat_ipv4_multi_range_compat *mr;
0039
0040     mr = par->targinfo;
0041     range.flags = mr->range[0].flags;
0042     range.min_proto = mr->range[0].min;
0043     range.max_proto = mr->range[0].max;
0044
0045     return nf_nat_masquerade_ipv4(skb, xt_hooknum(par), &range,
0046                       xt_out(par));
0047 }
0048
0049 static void masquerade_tg_destroy(const struct xt_tgdtor_param *par)
0050 {
0051     nf_ct_netns_put(par->net, par->family);
0052 }
0053
0054 #if IS_ENABLED(CONFIG_IPV6)
0055 static unsigned int
0056 masquerade_tg6(struct sk_buff *skb, const struct xt_action_param *par)
0057 {
0058     return nf_nat_masquerade_ipv6(skb, par->targinfo, xt_out(par));
0059 }
0060
0061 static int masquerade_tg6_checkentry(const struct xt_tgchk_param *par)
0062 {
0063     const struct nf_nat_range2 *range = par->targinfo;
0064
0065     if (range->flags & NF_NAT_RANGE_MAP_IPS)
0066         return -EINVAL;
0067
0068     return nf_ct_netns_get(par->net, par->family);
0069 }
0070 #endif
0071
0072 static struct xt_target masquerade_tg_reg[] __read_mostly = {
0073     {
0074 #if IS_ENABLED(CONFIG_IPV6)
0075         .name       = "MASQUERADE",
0076         .family     = NFPROTO_IPV6,
0077         .target     = masquerade_tg6,
0078         .targetsize = sizeof(struct nf_nat_range),
0079         .table      = "nat",
0080         .hooks      = 1 << NF_INET_POST_ROUTING,
0081         .checkentry = masquerade_tg6_checkentry,
0082         .destroy    = masquerade_tg_destroy,
0083         .me     = THIS_MODULE,
0084     }, {
0085 #endif
0086         .name       = "MASQUERADE",
0087         .family     = NFPROTO_IPV4,
0088         .target     = masquerade_tg,
0089         .targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
0090         .table      = "nat",
0091         .hooks      = 1 << NF_INET_POST_ROUTING,
0092         .checkentry = masquerade_tg_check,
0093         .destroy    = masquerade_tg_destroy,
0094         .me     = THIS_MODULE,
0095     }
0096 };
0097
0098 static int __init masquerade_tg_init(void)
0099 {
0100     int ret;
0101
0102     ret = xt_register_targets(masquerade_tg_reg,
0103                   ARRAY_SIZE(masquerade_tg_reg));
0104     if (ret)
0105         return ret;
0106
0107     ret = nf_nat_masquerade_inet_register_notifiers();
0108     if (ret) {
0109         xt_unregister_targets(masquerade_tg_reg,
0110                       ARRAY_SIZE(masquerade_tg_reg));
0111         return ret;
0112     }
0113
0114     return ret;
0115 }
0116
0117 static void __exit masquerade_tg_exit(void)
0118 {
0119     xt_unregister_targets(masquerade_tg_reg, ARRAY_SIZE(masquerade_tg_reg));
0120     nf_nat_masquerade_inet_unregister_notifiers();
0121 }
0122
0123 module_init(masquerade_tg_init);
0124 module_exit(masquerade_tg_exit);
0125 #if IS_ENABLED(CONFIG_IPV6)
0126 MODULE_ALIAS("ip6t_MASQUERADE");
0127 #endif
0128 MODULE_ALIAS("ipt_MASQUERADE");