/* 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 * * 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 #include #include #include #include #include #include #include #include #include #include #include #include MODULE_LICENSE("GPL"); MODULE_AUTHOR("Netfilter Core Team "); 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_ipv4_multi_range_compat *mr = par->targinfo; if (mr->range[0].flags & NF_NAT_RANGE_MAP_IPS) { pr_debug("bad MAP_IPS.\n"); return -EINVAL; } if (mr->rangesize != 1) { pr_debug("bad rangesize %u\n", mr->rangesize); return -EINVAL; } return 0; } static unsigned int masquerade_tg(struct sk_buff *skb, const struct xt_action_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_ipv4_multi_range_compat *mr; const struct rtable *rt; __be32 newsrc, nh; 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_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); nh = rt_nexthop(rt, ip_hdr(skb)->daddr); newsrc = inet_select_addr(par->out, nh, 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. */ memset(&newrange.min_addr, 0, sizeof(newrange.min_addr)); memset(&newrange.max_addr, 0, sizeof(newrange.max_addr)); newrange.flags = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS; newrange.min_addr.ip = newsrc; newrange.max_addr.ip = newsrc; newrange.min_proto = mr->range[0].min; newrange.max_proto = mr->range[0].max; /* Hand modified range to generic setup. */ return nf_nat_setup_info(ct, &newrange, NF_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; if (nf_ct_l3num(i) != NFPROTO_IPV4) 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_ipv4_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);