![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>
202 lines
5 KiB
C
202 lines
5 KiB
C
/* Masquerade. Simple mapping which alters range to a local IP address
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(depending on route). */
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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/inetdevice.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 <net/protocol.h>
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#include <net/ip.h>
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#include <net/checksum.h>
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#include <net/route.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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#include <linux/netfilter_ipv4/ip_tables.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 MASQUERADE 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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/* Lock protects masq region inside conntrack */
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static DEFINE_RWLOCK(masq_lock);
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/* FIXME: Multiple targets. --RR */
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static int
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masquerade_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("masquerade_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("masquerade_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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masquerade_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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const struct ip_nat_multi_range_compat *mr;
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struct ip_nat_range newrange;
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struct rtable *rt;
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u_int32_t newsrc;
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IP_NF_ASSERT(hooknum == NF_IP_POST_ROUTING);
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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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|| ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
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/* Source address is 0.0.0.0 - locally generated packet that is
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* probably not supposed to be masqueraded.
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*/
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if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip == 0)
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return NF_ACCEPT;
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mr = targinfo;
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rt = (struct rtable *)(*pskb)->dst;
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newsrc = inet_select_addr(out, rt->rt_gateway, RT_SCOPE_UNIVERSE);
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if (!newsrc) {
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printk("MASQUERADE: %s ate my IP address\n", out->name);
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return NF_DROP;
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}
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write_lock_bh(&masq_lock);
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ct->nat.masq_index = out->ifindex;
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write_unlock_bh(&masq_lock);
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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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newsrc, newsrc,
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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 inline int
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device_cmp(struct ip_conntrack *i, void *ifindex)
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{
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int ret;
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read_lock_bh(&masq_lock);
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ret = (i->nat.masq_index == (int)(long)ifindex);
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read_unlock_bh(&masq_lock);
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return ret;
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}
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static int masq_device_event(struct notifier_block *this,
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unsigned long event,
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void *ptr)
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{
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struct net_device *dev = ptr;
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if (event == NETDEV_DOWN) {
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/* Device was downed. Search entire table for
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conntracks which were associated with that device,
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and forget them. */
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IP_NF_ASSERT(dev->ifindex != 0);
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ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
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}
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return NOTIFY_DONE;
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}
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static int masq_inet_event(struct notifier_block *this,
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unsigned long event,
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void *ptr)
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{
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struct net_device *dev = ((struct in_ifaddr *)ptr)->ifa_dev->dev;
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if (event == NETDEV_DOWN) {
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/* IP address was deleted. Search entire table for
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conntracks which were associated with that device,
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and forget them. */
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IP_NF_ASSERT(dev->ifindex != 0);
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ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
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}
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return NOTIFY_DONE;
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}
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static struct notifier_block masq_dev_notifier = {
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.notifier_call = masq_device_event,
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};
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static struct notifier_block masq_inet_notifier = {
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.notifier_call = masq_inet_event,
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};
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static struct ipt_target masquerade = {
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.name = "MASQUERADE",
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.target = masquerade_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_POST_ROUTING,
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.checkentry = masquerade_check,
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.me = THIS_MODULE,
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};
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static int __init ipt_masquerade_init(void)
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{
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int ret;
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ret = ipt_register_target(&masquerade);
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if (ret == 0) {
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/* Register for device down reports */
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register_netdevice_notifier(&masq_dev_notifier);
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/* Register IP address change reports */
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register_inetaddr_notifier(&masq_inet_notifier);
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}
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return ret;
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}
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static void __exit ipt_masquerade_fini(void)
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{
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ipt_unregister_target(&masquerade);
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unregister_netdevice_notifier(&masq_dev_notifier);
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unregister_inetaddr_notifier(&masq_inet_notifier);
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}
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module_init(ipt_masquerade_init);
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module_exit(ipt_masquerade_fini);
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