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/* Redirect. Simple mapping which alters dst to a local IP address. */
/* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
*
* 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.
*/
#include <linux/types.h>
#include <linux/ip.h>
#include <linux/timer.h>
#include <linux/module.h>
#include <linux/netfilter.h>
#include <linux/netdevice.h>
#include <linux/if.h>
#include <linux/inetdevice.h>
#include <net/protocol.h>
#include <net/checksum.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter/x_tables.h>
#include <net/netfilter/nf_nat_rule.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
MODULE_DESCRIPTION("iptables REDIRECT target module");
/* FIXME: Take multiple ranges --RR */
static bool
redirect_check(const char *tablename,
const void *e,
const struct xt_target *target,
void *targinfo,
unsigned int hook_mask)
{
const struct nf_nat_multi_range_compat *mr = targinfo;
if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) {
pr_debug("redirect_check: bad MAP_IPS.\n");
return false;
}
if (mr->rangesize != 1) {
pr_debug("redirect_check: bad rangesize %u.\n", mr->rangesize);
return false;
}
return true;
}
static unsigned int
redirect_target(struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
unsigned int hooknum,
const struct xt_target *target,
const void *targinfo)
{
struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
__be32 newdst;
const struct nf_nat_multi_range_compat *mr = targinfo;
struct nf_nat_range newrange;
NF_CT_ASSERT(hooknum == NF_IP_PRE_ROUTING
|| hooknum == NF_IP_LOCAL_OUT);
ct = nf_ct_get(*pskb, &ctinfo);
NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
/* Local packets: make them go to loopback */
if (hooknum == NF_IP_LOCAL_OUT)
newdst = htonl(0x7F000001);
else {
struct in_device *indev;
struct in_ifaddr *ifa;
newdst = 0;
rcu_read_lock();
indev = __in_dev_get_rcu((*pskb)->dev);
if (indev && (ifa = indev->ifa_list))
newdst = ifa->ifa_local;
rcu_read_unlock();
if (!newdst)
return NF_DROP;
}
/* Transfer from original range. */
newrange = ((struct nf_nat_range)
{ mr->range[0].flags | IP_NAT_RANGE_MAP_IPS,
newdst, newdst,
mr->range[0].min, mr->range[0].max });
/* Hand modified range to generic setup. */
return nf_nat_setup_info(ct, &newrange, hooknum);
}
static struct xt_target redirect_reg __read_mostly = {
.name = "REDIRECT",
.family = AF_INET,
.target = redirect_target,
.targetsize = sizeof(struct nf_nat_multi_range_compat),
.table = "nat",
.hooks = (1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_OUT),
.checkentry = redirect_check,
.me = THIS_MODULE,
};
static int __init ipt_redirect_init(void)
{
return xt_register_target(&redirect_reg);
}
static void __exit ipt_redirect_fini(void)
{
xt_unregister_target(&redirect_reg);
}
module_init(ipt_redirect_init);
module_exit(ipt_redirect_fini);
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