1/*
  2 * (C) 2000-2001 Svenning Soerensen <svenning@post5.tele.dk>
  3 * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
  4 *
  5 * This program is free software; you can redistribute it and/or modify
  6 * it under the terms of the GNU General Public License version 2 as
  7 * published by the Free Software Foundation.
  8 */
  9
 10#include <linux/ip.h>
 11#include <linux/kernel.h>
 12#include <linux/module.h>
 13#include <linux/netdevice.h>
 14#include <linux/ipv6.h>
 15#include <linux/netfilter.h>
 16#include <linux/netfilter_ipv4.h>
 17#include <linux/netfilter_ipv6.h>
 18#include <linux/netfilter/x_tables.h>
 19#include <net/netfilter/nf_nat.h>
 20
 21static unsigned int
 22netmap_tg6(struct sk_buff *skb, const struct xt_action_param *par)
 23{
 24	const struct nf_nat_range *range = par->targinfo;
 25	struct nf_nat_range newrange;
 26	struct nf_conn *ct;
 27	enum ip_conntrack_info ctinfo;
 28	union nf_inet_addr new_addr, netmask;
 29	unsigned int i;
 30
 31	ct = nf_ct_get(skb, &ctinfo);
 32	for (i = 0; i < ARRAY_SIZE(range->min_addr.ip6); i++)
 33		netmask.ip6[i] = ~(range->min_addr.ip6[i] ^
 34				   range->max_addr.ip6[i]);
 35
 36	if (xt_hooknum(par) == NF_INET_PRE_ROUTING ||
 37	    xt_hooknum(par) == NF_INET_LOCAL_OUT)
 38		new_addr.in6 = ipv6_hdr(skb)->daddr;
 39	else
 40		new_addr.in6 = ipv6_hdr(skb)->saddr;
 41
 42	for (i = 0; i < ARRAY_SIZE(new_addr.ip6); i++) {
 43		new_addr.ip6[i] &= ~netmask.ip6[i];
 44		new_addr.ip6[i] |= range->min_addr.ip6[i] &
 45				   netmask.ip6[i];
 46	}
 47
 48	newrange.flags	= range->flags | NF_NAT_RANGE_MAP_IPS;
 49	newrange.min_addr	= new_addr;
 50	newrange.max_addr	= new_addr;
 51	newrange.min_proto	= range->min_proto;
 52	newrange.max_proto	= range->max_proto;
 53
 54	return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(xt_hooknum(par)));
 55}
 56
 57static int netmap_tg6_checkentry(const struct xt_tgchk_param *par)
 58{
 59	const struct nf_nat_range *range = par->targinfo;
 60
 61	if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
 62		return -EINVAL;
 63	return nf_ct_netns_get(par->net, par->family);
 64}
 65
 66static void netmap_tg_destroy(const struct xt_tgdtor_param *par)
 67{
 68	nf_ct_netns_put(par->net, par->family);
 69}
 70
 71static unsigned int
 72netmap_tg4(struct sk_buff *skb, const struct xt_action_param *par)
 73{
 74	struct nf_conn *ct;
 75	enum ip_conntrack_info ctinfo;
 76	__be32 new_ip, netmask;
 77	const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
 78	struct nf_nat_range newrange;
 79
 80	NF_CT_ASSERT(xt_hooknum(par) == NF_INET_PRE_ROUTING ||
 81		     xt_hooknum(par) == NF_INET_POST_ROUTING ||
 82		     xt_hooknum(par) == NF_INET_LOCAL_OUT ||
 83		     xt_hooknum(par) == NF_INET_LOCAL_IN);
 84	ct = nf_ct_get(skb, &ctinfo);
 85
 86	netmask = ~(mr->range[0].min_ip ^ mr->range[0].max_ip);
 87
 88	if (xt_hooknum(par) == NF_INET_PRE_ROUTING ||
 89	    xt_hooknum(par) == NF_INET_LOCAL_OUT)
 90		new_ip = ip_hdr(skb)->daddr & ~netmask;
 91	else
 92		new_ip = ip_hdr(skb)->saddr & ~netmask;
 93	new_ip |= mr->range[0].min_ip & netmask;
 94
 95	memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
 96	memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
 97	newrange.flags	     = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
 98	newrange.min_addr.ip = new_ip;
 99	newrange.max_addr.ip = new_ip;
100	newrange.min_proto   = mr->range[0].min;
101	newrange.max_proto   = mr->range[0].max;
102
103	/* Hand modified range to generic setup. */
104	return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(xt_hooknum(par)));
105}
106
107static int netmap_tg4_check(const struct xt_tgchk_param *par)
108{
109	const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
110
111	if (!(mr->range[0].flags & NF_NAT_RANGE_MAP_IPS)) {
112		pr_debug("bad MAP_IPS.\n");
113		return -EINVAL;
114	}
115	if (mr->rangesize != 1) {
116		pr_debug("bad rangesize %u.\n", mr->rangesize);
117		return -EINVAL;
118	}
119	return nf_ct_netns_get(par->net, par->family);
120}
121
122static struct xt_target netmap_tg_reg[] __read_mostly = {
123	{
124		.name       = "NETMAP",
125		.family     = NFPROTO_IPV6,
126		.revision   = 0,
127		.target     = netmap_tg6,
128		.targetsize = sizeof(struct nf_nat_range),
129		.table      = "nat",
130		.hooks      = (1 << NF_INET_PRE_ROUTING) |
131		              (1 << NF_INET_POST_ROUTING) |
132		              (1 << NF_INET_LOCAL_OUT) |
133		              (1 << NF_INET_LOCAL_IN),
134		.checkentry = netmap_tg6_checkentry,
135		.destroy    = netmap_tg_destroy,
136		.me         = THIS_MODULE,
137	},
138	{
139		.name       = "NETMAP",
140		.family     = NFPROTO_IPV4,
141		.revision   = 0,
142		.target     = netmap_tg4,
143		.targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
144		.table      = "nat",
145		.hooks      = (1 << NF_INET_PRE_ROUTING) |
146		              (1 << NF_INET_POST_ROUTING) |
147		              (1 << NF_INET_LOCAL_OUT) |
148		              (1 << NF_INET_LOCAL_IN),
149		.checkentry = netmap_tg4_check,
150		.destroy    = netmap_tg_destroy,
151		.me         = THIS_MODULE,
152	},
153};
154
155static int __init netmap_tg_init(void)
156{
157	return xt_register_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
158}
159
160static void netmap_tg_exit(void)
161{
162	xt_unregister_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
163}
164
165module_init(netmap_tg_init);
166module_exit(netmap_tg_exit);
167
168MODULE_LICENSE("GPL");
169MODULE_DESCRIPTION("Xtables: 1:1 NAT mapping of subnets");
170MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
171MODULE_ALIAS("ip6t_NETMAP");
172MODULE_ALIAS("ipt_NETMAP");