134 lines
3.3 KiB
C
134 lines
3.3 KiB
C
/* Redirect. Simple mapping which alters dst to a local IP address. */
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/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/types.h>
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#include <linux/ip.h>
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#include <linux/timer.h>
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#include <linux/module.h>
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#include <linux/netfilter.h>
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#include <linux/netdevice.h>
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#include <linux/if.h>
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#include <linux/inetdevice.h>
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#include <net/protocol.h>
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#include <net/checksum.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/netfilter_ipv4/ip_nat_rule.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
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MODULE_DESCRIPTION("iptables REDIRECT target module");
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#if 0
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#define DEBUGP printk
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#else
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#define DEBUGP(format, args...)
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#endif
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/* FIXME: Take multiple ranges --RR */
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static int
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redirect_check(const char *tablename,
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const struct ipt_entry *e,
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void *targinfo,
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unsigned int targinfosize,
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unsigned int hook_mask)
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{
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const struct ip_nat_multi_range_compat *mr = targinfo;
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if (strcmp(tablename, "nat") != 0) {
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DEBUGP("redirect_check: bad table `%s'.\n", table);
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return 0;
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}
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if (targinfosize != IPT_ALIGN(sizeof(*mr))) {
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DEBUGP("redirect_check: size %u.\n", targinfosize);
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return 0;
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}
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if (hook_mask & ~((1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_OUT))) {
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DEBUGP("redirect_check: bad hooks %x.\n", hook_mask);
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return 0;
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}
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if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) {
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DEBUGP("redirect_check: bad MAP_IPS.\n");
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return 0;
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}
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if (mr->rangesize != 1) {
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DEBUGP("redirect_check: bad rangesize %u.\n", mr->rangesize);
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return 0;
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}
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return 1;
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}
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static unsigned int
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redirect_target(struct sk_buff **pskb,
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const struct net_device *in,
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const struct net_device *out,
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unsigned int hooknum,
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const void *targinfo,
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void *userinfo)
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{
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struct ip_conntrack *ct;
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enum ip_conntrack_info ctinfo;
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u_int32_t newdst;
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const struct ip_nat_multi_range_compat *mr = targinfo;
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struct ip_nat_range newrange;
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IP_NF_ASSERT(hooknum == NF_IP_PRE_ROUTING
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|| hooknum == NF_IP_LOCAL_OUT);
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ct = ip_conntrack_get(*pskb, &ctinfo);
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IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED));
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/* Local packets: make them go to loopback */
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if (hooknum == NF_IP_LOCAL_OUT)
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newdst = htonl(0x7F000001);
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else {
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struct in_device *indev;
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struct in_ifaddr *ifa;
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newdst = 0;
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rcu_read_lock();
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indev = __in_dev_get_rcu((*pskb)->dev);
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if (indev && (ifa = indev->ifa_list))
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newdst = ifa->ifa_local;
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rcu_read_unlock();
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if (!newdst)
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return NF_DROP;
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}
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/* Transfer from original range. */
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newrange = ((struct ip_nat_range)
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{ mr->range[0].flags | IP_NAT_RANGE_MAP_IPS,
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newdst, newdst,
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mr->range[0].min, mr->range[0].max });
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/* Hand modified range to generic setup. */
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return ip_nat_setup_info(ct, &newrange, hooknum);
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}
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static struct ipt_target redirect_reg = {
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.name = "REDIRECT",
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.target = redirect_target,
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.checkentry = redirect_check,
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.me = THIS_MODULE,
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};
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static int __init init(void)
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{
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return ipt_register_target(&redirect_reg);
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}
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static void __exit fini(void)
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{
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ipt_unregister_target(&redirect_reg);
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}
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module_init(init);
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module_exit(fini);
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