![Jörn Engel](/assets/img/avatar_default.png)
Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
112 lines
2.9 KiB
C
112 lines
2.9 KiB
C
/* NETMAP - static NAT mapping of IP network addresses (1:1).
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* The mapping can be applied to source (POSTROUTING),
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* destination (PREROUTING), or both (with separate rules).
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*/
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/* (C) 2000-2001 Svenning Soerensen <svenning@post5.tele.dk>
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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/ip.h>
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#include <linux/module.h>
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#include <linux/netdevice.h>
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#include <linux/netfilter.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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#define MODULENAME "NETMAP"
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Svenning Soerensen <svenning@post5.tele.dk>");
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MODULE_DESCRIPTION("iptables 1:1 NAT mapping of IP networks target");
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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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static int
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check(const char *tablename,
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const void *e,
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const struct xt_target *target,
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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 (!(mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)) {
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DEBUGP(MODULENAME":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(MODULENAME":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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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 struct xt_target *target,
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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 new_ip, netmask;
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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_POST_ROUTING
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|| hooknum == NF_IP_LOCAL_OUT);
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ct = ip_conntrack_get(*pskb, &ctinfo);
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netmask = ~(mr->range[0].min_ip ^ mr->range[0].max_ip);
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if (hooknum == NF_IP_PRE_ROUTING || hooknum == NF_IP_LOCAL_OUT)
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new_ip = (*pskb)->nh.iph->daddr & ~netmask;
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else
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new_ip = (*pskb)->nh.iph->saddr & ~netmask;
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new_ip |= mr->range[0].min_ip & netmask;
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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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new_ip, new_ip,
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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 target_module = {
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.name = MODULENAME,
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.target = target,
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.targetsize = sizeof(struct ip_nat_multi_range_compat),
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.table = "nat",
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.hooks = (1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_POST_ROUTING) |
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(1 << NF_IP_LOCAL_OUT),
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.checkentry = check,
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.me = THIS_MODULE
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};
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static int __init ipt_netmap_init(void)
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{
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return ipt_register_target(&target_module);
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}
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static void __exit ipt_netmap_fini(void)
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{
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ipt_unregister_target(&target_module);
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}
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module_init(ipt_netmap_init);
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module_exit(ipt_netmap_fini);
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