| /* NETMAP - static NAT mapping of IP network addresses (1:1). |
| * The mapping can be applied to source (POSTROUTING), |
| * destination (PREROUTING), or both (with separate rules). |
| */ |
| |
| /* (C) 2000-2001 Svenning Soerensen <svenning@post5.tele.dk> |
| * |
| * 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/ip.h> |
| #include <linux/module.h> |
| #include <linux/netdevice.h> |
| #include <linux/netfilter.h> |
| #include <linux/netfilter_ipv4.h> |
| #include <linux/netfilter/x_tables.h> |
| #include <net/netfilter/nf_nat_rule.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Svenning Soerensen <svenning@post5.tele.dk>"); |
| MODULE_DESCRIPTION("Xtables: 1:1 NAT mapping of IPv4 subnets"); |
| |
| static int netmap_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 -EINVAL; |
| } |
| if (mr->rangesize != 1) { |
| pr_debug("bad rangesize %u.\n", mr->rangesize); |
| return -EINVAL; |
| } |
| return 0; |
| } |
| |
| static unsigned int |
| netmap_tg(struct sk_buff *skb, const struct xt_action_param *par) |
| { |
| struct nf_conn *ct; |
| enum ip_conntrack_info ctinfo; |
| __be32 new_ip, netmask; |
| const struct nf_nat_multi_range_compat *mr = par->targinfo; |
| struct nf_nat_range newrange; |
| |
| NF_CT_ASSERT(par->hooknum == NF_INET_PRE_ROUTING || |
| par->hooknum == NF_INET_POST_ROUTING || |
| par->hooknum == NF_INET_LOCAL_OUT || |
| par->hooknum == NF_INET_LOCAL_IN); |
| ct = nf_ct_get(skb, &ctinfo); |
| |
| netmask = ~(mr->range[0].min_ip ^ mr->range[0].max_ip); |
| |
| if (par->hooknum == NF_INET_PRE_ROUTING || |
| par->hooknum == NF_INET_LOCAL_OUT) |
| new_ip = ip_hdr(skb)->daddr & ~netmask; |
| else |
| new_ip = ip_hdr(skb)->saddr & ~netmask; |
| new_ip |= mr->range[0].min_ip & netmask; |
| |
| newrange = ((struct nf_nat_range) |
| { mr->range[0].flags | IP_NAT_RANGE_MAP_IPS, |
| new_ip, new_ip, |
| mr->range[0].min, mr->range[0].max }); |
| |
| /* Hand modified range to generic setup. */ |
| return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(par->hooknum)); |
| } |
| |
| static struct xt_target netmap_tg_reg __read_mostly = { |
| .name = "NETMAP", |
| .family = NFPROTO_IPV4, |
| .target = netmap_tg, |
| .targetsize = sizeof(struct nf_nat_multi_range_compat), |
| .table = "nat", |
| .hooks = (1 << NF_INET_PRE_ROUTING) | |
| (1 << NF_INET_POST_ROUTING) | |
| (1 << NF_INET_LOCAL_OUT) | |
| (1 << NF_INET_LOCAL_IN), |
| .checkentry = netmap_tg_check, |
| .me = THIS_MODULE |
| }; |
| |
| static int __init netmap_tg_init(void) |
| { |
| return xt_register_target(&netmap_tg_reg); |
| } |
| |
| static void __exit netmap_tg_exit(void) |
| { |
| xt_unregister_target(&netmap_tg_reg); |
| } |
| |
| module_init(netmap_tg_init); |
| module_exit(netmap_tg_exit); |