182 lines
4.8 KiB
C
182 lines
4.8 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) 2002-2006 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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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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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/x_tables.h>
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#include <net/netfilter/nf_nat.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("Xtables: automatic-address SNAT");
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/* FIXME: Multiple targets. --RR */
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static int masquerade_tg_check(const struct xt_tgchk_param *par)
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{
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const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
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if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) {
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pr_debug("bad MAP_IPS.\n");
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return -EINVAL;
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}
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if (mr->rangesize != 1) {
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pr_debug("bad rangesize %u\n", mr->rangesize);
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return -EINVAL;
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}
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return 0;
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}
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static unsigned int
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masquerade_tg(struct sk_buff *skb, const struct xt_action_param *par)
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{
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struct nf_conn *ct;
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struct nf_conn_nat *nat;
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enum ip_conntrack_info ctinfo;
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struct nf_nat_range newrange;
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const struct nf_nat_ipv4_multi_range_compat *mr;
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const struct rtable *rt;
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__be32 newsrc, nh;
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NF_CT_ASSERT(par->hooknum == NF_INET_POST_ROUTING);
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ct = nf_ct_get(skb, &ctinfo);
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nat = nfct_nat(ct);
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NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
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ctinfo == IP_CT_RELATED_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.u3.ip == 0)
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return NF_ACCEPT;
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mr = par->targinfo;
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rt = skb_rtable(skb);
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nh = rt_nexthop(rt, ip_hdr(skb)->daddr);
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newsrc = inet_select_addr(par->out, nh, RT_SCOPE_UNIVERSE);
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if (!newsrc) {
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pr_info("%s ate my IP address\n", par->out->name);
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return NF_DROP;
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}
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nat->masq_index = par->out->ifindex;
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/* Transfer from original range. */
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memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
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memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
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newrange.flags = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
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newrange.min_addr.ip = newsrc;
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newrange.max_addr.ip = newsrc;
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newrange.min_proto = mr->range[0].min;
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newrange.max_proto = 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, NF_NAT_MANIP_SRC);
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}
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static int
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device_cmp(struct nf_conn *i, void *ifindex)
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{
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const struct nf_conn_nat *nat = nfct_nat(i);
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if (!nat)
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return 0;
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if (nf_ct_l3num(i) != NFPROTO_IPV4)
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return 0;
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return nat->masq_index == (int)(long)ifindex;
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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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const struct net_device *dev = netdev_notifier_info_to_dev(ptr);
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struct net *net = dev_net(dev);
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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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NF_CT_ASSERT(dev->ifindex != 0);
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nf_ct_iterate_cleanup(net, device_cmp,
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(void *)(long)dev->ifindex, 0, 0);
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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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struct netdev_notifier_info info;
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netdev_notifier_info_init(&info, dev);
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return masq_device_event(this, event, &info);
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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 xt_target masquerade_tg_reg __read_mostly = {
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.name = "MASQUERADE",
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.family = NFPROTO_IPV4,
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.target = masquerade_tg,
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.targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
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.table = "nat",
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.hooks = 1 << NF_INET_POST_ROUTING,
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.checkentry = masquerade_tg_check,
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.me = THIS_MODULE,
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};
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static int __init masquerade_tg_init(void)
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{
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int ret;
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ret = xt_register_target(&masquerade_tg_reg);
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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 masquerade_tg_exit(void)
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{
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xt_unregister_target(&masquerade_tg_reg);
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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(masquerade_tg_init);
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module_exit(masquerade_tg_exit);
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