| /* Masquerade. Simple mapping which alters range to a local IP address |
| (depending on route). */ |
| |
| /* (C) 1999-2001 Paul `Rusty' Russell |
| * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| */ |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| #include <linux/types.h> |
| #include <linux/inetdevice.h> |
| #include <linux/ip.h> |
| #include <linux/timer.h> |
| #include <linux/module.h> |
| #include <linux/netfilter.h> |
| #include <net/protocol.h> |
| #include <net/ip.h> |
| #include <net/checksum.h> |
| #include <net/route.h> |
| #include <net/netfilter/nf_nat_rule.h> |
| #include <linux/netfilter_ipv4.h> |
| #include <linux/netfilter/x_tables.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); |
| MODULE_DESCRIPTION("Xtables: automatic-address SNAT"); |
| |
| /* FIXME: Multiple targets. --RR */ |
| static int masquerade_tg_check(const struct xt_tgchk_param *par) |
| { |
| const struct nf_nat_multi_range_compat *mr = par->targinfo; |
| |
| if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) { |
| pr_debug("bad MAP_IPS.\n"); |
| return false; |
| } |
| if (mr->rangesize != 1) { |
| pr_debug("bad rangesize %u\n", mr->rangesize); |
| return false; |
| } |
| return true; |
| } |
| |
| static unsigned int |
| masquerade_tg(struct sk_buff *skb, const struct xt_target_param *par) |
| { |
| struct nf_conn *ct; |
| struct nf_conn_nat *nat; |
| enum ip_conntrack_info ctinfo; |
| struct nf_nat_range newrange; |
| const struct nf_nat_multi_range_compat *mr; |
| const struct rtable *rt; |
| __be32 newsrc; |
| |
| NF_CT_ASSERT(par->hooknum == NF_INET_POST_ROUTING); |
| |
| ct = nf_ct_get(skb, &ctinfo); |
| nat = nfct_nat(ct); |
| |
| NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED || |
| ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY)); |
| |
| /* Source address is 0.0.0.0 - locally generated packet that is |
| * probably not supposed to be masqueraded. |
| */ |
| if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip == 0) |
| return NF_ACCEPT; |
| |
| mr = par->targinfo; |
| rt = skb_rtable(skb); |
| newsrc = inet_select_addr(par->out, rt->rt_gateway, RT_SCOPE_UNIVERSE); |
| if (!newsrc) { |
| pr_info("%s ate my IP address\n", par->out->name); |
| return NF_DROP; |
| } |
| |
| nat->masq_index = par->out->ifindex; |
| |
| /* Transfer from original range. */ |
| newrange = ((struct nf_nat_range) |
| { mr->range[0].flags | IP_NAT_RANGE_MAP_IPS, |
| newsrc, newsrc, |
| mr->range[0].min, mr->range[0].max }); |
| |
| /* Hand modified range to generic setup. */ |
| return nf_nat_setup_info(ct, &newrange, IP_NAT_MANIP_SRC); |
| } |
| |
| static int |
| device_cmp(struct nf_conn *i, void *ifindex) |
| { |
| const struct nf_conn_nat *nat = nfct_nat(i); |
| |
| if (!nat) |
| return 0; |
| |
| return nat->masq_index == (int)(long)ifindex; |
| } |
| |
| static int masq_device_event(struct notifier_block *this, |
| unsigned long event, |
| void *ptr) |
| { |
| const struct net_device *dev = ptr; |
| struct net *net = dev_net(dev); |
| |
| if (event == NETDEV_DOWN) { |
| /* Device was downed. Search entire table for |
| conntracks which were associated with that device, |
| and forget them. */ |
| NF_CT_ASSERT(dev->ifindex != 0); |
| |
| nf_ct_iterate_cleanup(net, device_cmp, |
| (void *)(long)dev->ifindex); |
| } |
| |
| return NOTIFY_DONE; |
| } |
| |
| static int masq_inet_event(struct notifier_block *this, |
| unsigned long event, |
| void *ptr) |
| { |
| struct net_device *dev = ((struct in_ifaddr *)ptr)->ifa_dev->dev; |
| return masq_device_event(this, event, dev); |
| } |
| |
| static struct notifier_block masq_dev_notifier = { |
| .notifier_call = masq_device_event, |
| }; |
| |
| static struct notifier_block masq_inet_notifier = { |
| .notifier_call = masq_inet_event, |
| }; |
| |
| static struct xt_target masquerade_tg_reg __read_mostly = { |
| .name = "MASQUERADE", |
| .family = NFPROTO_IPV4, |
| .target = masquerade_tg, |
| .targetsize = sizeof(struct nf_nat_multi_range_compat), |
| .table = "nat", |
| .hooks = 1 << NF_INET_POST_ROUTING, |
| .checkentry = masquerade_tg_check, |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init masquerade_tg_init(void) |
| { |
| int ret; |
| |
| ret = xt_register_target(&masquerade_tg_reg); |
| |
| if (ret == 0) { |
| /* Register for device down reports */ |
| register_netdevice_notifier(&masq_dev_notifier); |
| /* Register IP address change reports */ |
| register_inetaddr_notifier(&masq_inet_notifier); |
| } |
| |
| return ret; |
| } |
| |
| static void __exit masquerade_tg_exit(void) |
| { |
| xt_unregister_target(&masquerade_tg_reg); |
| unregister_netdevice_notifier(&masq_dev_notifier); |
| unregister_inetaddr_notifier(&masq_inet_notifier); |
| } |
| |
| module_init(masquerade_tg_init); |
| module_exit(masquerade_tg_exit); |