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/*
* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
* Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Based on Rusty Russell's IPv4 REDIRECT target. Development of IPv6
* NAT funded by Astaro.
*/
#include <linux/if.h>
#include <linux/inetdevice.h>
#include <linux/ip.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/netfilter.h>
#include <linux/types.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netfilter/x_tables.h>
#include <net/addrconf.h>
#include <net/checksum.h>
#include <net/protocol.h>
#include <net/netfilter/nf_nat.h>
static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT;
static unsigned int
redirect_tg6(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct nf_nat_range *range = par->targinfo;
struct nf_nat_range newrange;
struct in6_addr newdst;
enum ip_conntrack_info ctinfo;
struct nf_conn *ct;
ct = nf_ct_get(skb, &ctinfo);
if (par->hooknum == NF_INET_LOCAL_OUT)
newdst = loopback_addr;
else {
struct inet6_dev *idev;
struct inet6_ifaddr *ifa;
bool addr = false;
rcu_read_lock();
idev = __in6_dev_get(skb->dev);
if (idev != NULL) {
list_for_each_entry(ifa, &idev->addr_list, if_list) {
newdst = ifa->addr;
addr = true;
break;
}
}
rcu_read_unlock();
if (!addr)
return NF_DROP;
}
newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
newrange.min_addr.in6 = newdst;
newrange.max_addr.in6 = newdst;
newrange.min_proto = range->min_proto;
newrange.max_proto = range->max_proto;
return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
}
static int redirect_tg6_checkentry(const struct xt_tgchk_param *par)
{
const struct nf_nat_range *range = par->targinfo;
if (range->flags & NF_NAT_RANGE_MAP_IPS)
return -EINVAL;
return 0;
}
/* FIXME: Take multiple ranges --RR */
static int redirect_tg4_check(const struct xt_tgchk_param *par)
{
const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {
pr_debug("bad MAP_IPS.\n");
return -EINVAL;
}
if (mr->rangesize != 1) {
pr_debug("bad rangesize %u.\n", mr->rangesize);
return -EINVAL;
}
return 0;
}
static unsigned int
redirect_tg4(struct sk_buff *skb, const struct xt_action_param *par)
{
struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
__be32 newdst;
const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
struct nf_nat_range newrange;
NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING ||
par->hooknum == NF_INET_LOCAL_OUT);
ct = nf_ct_get(skb, &ctinfo);
NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
/* Local packets: make them go to loopback */
if (par->hooknum == NF_INET_LOCAL_OUT)
newdst = htonl(0x7F000001);
else {
struct in_device *indev;
struct in_ifaddr *ifa;
newdst = 0;
rcu_read_lock();
indev = __in_dev_get_rcu(skb->dev);
if (indev && (ifa = indev->ifa_list))
newdst = ifa->ifa_local;
rcu_read_unlock();
if (!newdst)
return NF_DROP;
}
/* Transfer from original range. */
memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
newrange.flags = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
newrange.min_addr.ip = newdst;
newrange.max_addr.ip = newdst;
newrange.min_proto = mr->range[0].min;
newrange.max_proto = mr->range[0].max;
/* Hand modified range to generic setup. */
return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
}
static struct xt_target redirect_tg_reg[] __read_mostly = {
{
.name = "REDIRECT",
.family = NFPROTO_IPV6,
.revision = 0,
.table = "nat",
.checkentry = redirect_tg6_checkentry,
.target = redirect_tg6,
.targetsize = sizeof(struct nf_nat_range),
.hooks = (1 << NF_INET_PRE_ROUTING) |
(1 << NF_INET_LOCAL_OUT),
.me = THIS_MODULE,
},
{
.name = "REDIRECT",
.family = NFPROTO_IPV4,
.revision = 0,
.table = "nat",
.target = redirect_tg4,
.checkentry = redirect_tg4_check,
.targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
.hooks = (1 << NF_INET_PRE_ROUTING) |
(1 << NF_INET_LOCAL_OUT),
.me = THIS_MODULE,
},
};
static int __init redirect_tg_init(void)
{
return xt_register_targets(redirect_tg_reg,
ARRAY_SIZE(redirect_tg_reg));
}
static void __exit redirect_tg_exit(void)
{
xt_unregister_targets(redirect_tg_reg, ARRAY_SIZE(redirect_tg_reg));
}
module_init(redirect_tg_init);
module_exit(redirect_tg_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_DESCRIPTION("Xtables: Connection redirection to localhost");
MODULE_ALIAS("ip6t_REDIRECT");
MODULE_ALIAS("ipt_REDIRECT");
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