105 lines
2.8 KiB
C
105 lines
2.8 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/x_tables.h>
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#include <net/netfilter/nf_nat_rule.h>
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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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static bool
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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 hook_mask)
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{
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const struct nf_nat_multi_range_compat *mr = targinfo;
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if (!(mr->range[0].flags & IP_NAT_RANGE_MAP_IPS)) {
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pr_debug("NETMAP:check: bad MAP_IPS.\n");
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return false;
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}
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if (mr->rangesize != 1) {
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pr_debug("NETMAP:check: bad rangesize %u.\n", mr->rangesize);
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return false;
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}
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return true;
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}
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static unsigned int
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target(struct sk_buff *skb,
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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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{
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struct nf_conn *ct;
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enum ip_conntrack_info ctinfo;
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__be32 new_ip, netmask;
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const struct nf_nat_multi_range_compat *mr = targinfo;
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struct nf_nat_range newrange;
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NF_CT_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 = nf_ct_get(skb, &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 = ip_hdr(skb)->daddr & ~netmask;
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else
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new_ip = ip_hdr(skb)->saddr & ~netmask;
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new_ip |= mr->range[0].min_ip & netmask;
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newrange = ((struct nf_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 nf_nat_setup_info(ct, &newrange, hooknum);
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}
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static struct xt_target target_module __read_mostly = {
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.name = "NETMAP",
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.family = AF_INET,
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.target = target,
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.targetsize = sizeof(struct nf_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 xt_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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xt_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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