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/*
* MAP66: Network Address Translation IPv6-to-IPv6 as
* proposed in the IETF's second NAT66 draft document.
* (c) 2010 sven-ola()gmx.de
*/
#include <linux/module.h>
#include <linux/version.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <net/ipv6.h>
#include "ip6t_MAP66.h"
MODULE_AUTHOR("Sven-Ola <sven-ola()gmx.de>");
MODULE_DESCRIPTION("Xtables: MAP66 - IPv6 to IPv6 SNAT");
MODULE_LICENSE("GPL");
#ifdef MAP66_DEBUG
/* Use lock to serialize, so printks don't overlap */
static DEFINE_SPINLOCK(MAP66_lock);
#endif
/* One's complement add */
static inline u_int16_t add16(
u_int16_t a,
u_int16_t b)
{
a += b;
return a + (a < b);
}
/* Calc one's complement csum */
static inline u_int16_t csum16(const u_int16_t *buf, int len)
{
u_int16_t csum = 0;
while(len--) csum = add16(csum, *buf++);
return csum;
}
/* Perform checksum neutral mapping */
static void map16(
struct in6_addr* addr,
unsigned char mask,
const struct in6_addr* to,
u_int16_t csum)
{
csum = add16(
*((u_int16_t*)addr + mask),
add16(csum16((const u_int16_t *)addr, mask), csum)
);
if (csum == 0xffff) csum = 0x0000;
*((u_int16_t *)addr + mask) = csum;
memcpy(addr, to, sizeof(u_int16_t) * mask);
}
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,5,0)
# define rcu_dereference(p) p
# define ipv6_addr_equal(a, b) 0 == ipv6_addr_cmp(a, b)
# define ipv6_hdr(sbk) skb->nh.ipv6h
# ifndef bool
# define bool int
# define false 0
# define true 0
# endif
# define xt_target ip6t_target
# define __read_mostly
# define xt_register_target ip6t_register_target
# define xt_unregister_target ip6t_unregister_target
#endif
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,24)
# define NF_INET_PRE_ROUTING NF_IP6_PRE_ROUTING
# define NF_INET_POST_ROUTING NF_IP6_POST_ROUTING
#endif
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,26)
struct xt_target_param {
const struct net_device *in, *out;
const void *targinfo;
unsigned int hooknum;
};
struct xt_tgchk_param {
void *targinfo;
};
#endif
static bool is_my_ipv6_addr(
const struct net_device *dev,
const struct in6_addr *addr)
{
#ifdef MAP66_DEBUG
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,28)
printk("MAP66: is_my_ipv6_addr(%s, " NIP6_FMT ")\n", NULL != dev ? dev->name : "", NIP6(*addr));
#else
printk("MAP66: is_my_ipv6_addr(%s, %pI6)\n", NULL != dev ? dev->name : "", addr);
#endif
#endif
if (NULL != dev) {
const struct inet6_ifaddr *ifa;
const struct inet6_dev *idev = rcu_dereference(dev->ip6_ptr);
for (ifa = idev->addr_list; NULL != ifa; ifa = ifa->if_next) {
#ifdef MAP66_DEBUG
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,28)
printk("MAP66: cmp " NIP6_FMT "\n", NIP6(ifa->addr));
#else
printk("MAP66: cmp %pI6\n", &ifa->addr);
#endif
#endif
if (ipv6_addr_equal(&ifa->addr, addr)) return true;
}
}
return false;
}
static unsigned int MAP66_tg6(
struct sk_buff *skb,
const struct xt_target_param *par)
{
struct ipv6hdr *hdr = ipv6_hdr(skb);
const struct ip6t_MAP66_info *info = (const struct ip6t_MAP66_info *)par->targinfo;
#ifdef MAP66_DEBUG
spin_lock_bh(&MAP66_lock);
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,28)
printk("MAP66: enter in=%s, out=%s, saddr=" NIP6_FMT ", daddr=" NIP6_FMT "\n",
NULL != par->in ? par->in->name : "",
NULL != par->out ? par->out->name : "",
NIP6(hdr->saddr), NIP6(hdr->daddr));
#else
printk("MAP66: enter in=%s, out=%s, saddr=%pI6, daddr=%pI6\n",
NULL != par->in ? par->in->name : "",
NULL != par->out ? par->out->name : "",
&hdr->saddr, &hdr->daddr);
#endif
#endif
switch(par->hooknum) {
case NF_INET_PRE_ROUTING:
#ifdef MAP66_DEBUG
printk("MAP66 PRE, check=%d\n", 0 != (IP6T_MAP66_OPT_NOCHECK & info->mapflags));
#endif
if (0 != (IP6T_MAP66_OPT_NOCHECK & info->mapflags) ||
!is_my_ipv6_addr(par->in, &hdr->daddr))
{
map16(&hdr->daddr, info->prefixlength, &info->prefix, info->prefixcsum);
}
break;
case NF_INET_POST_ROUTING:
#ifdef MAP66_DEBUG
printk("MAP66 POST, check=%d\n", 0 != (IP6T_MAP66_OPT_NOCHECK & info->mapflags));
#endif
map16(&hdr->saddr, info->prefixlength, &info->prefix, info->prefixcsum);
if (0 == (IP6T_MAP66_OPT_NOCHECK & info->mapflags) &&
is_my_ipv6_addr(par->out, &hdr->saddr))
{
#ifdef MAP66_DEBUG
spin_unlock_bh(&MAP66_lock);
#endif
return NF_DROP;
}
break;
default:
#ifdef MAP66_DEBUG
printk("MAP66: unsupported hook: %d\n", par->hooknum);
#endif
break;
}
#ifdef MAP66_DEBUG
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,28)
printk("MAP66: exit in=%s, out=%s, saddr=" NIP6_FMT ", daddr=" NIP6_FMT "\n",
NULL != par->in ? par->in->name : "",
NULL != par->out ? par->out->name : "",
NIP6(hdr->saddr), NIP6(hdr->daddr));
#else
printk("MAP66: exit in=%s, out=%s, saddr=%pI6, daddr=%pI6\n",
NULL != par->in ? par->in->name : "",
NULL != par->out ? par->out->name : "",
&hdr->saddr, &hdr->daddr);
#endif
spin_unlock_bh(&MAP66_lock);
#endif
return IP6T_CONTINUE;
}
static bool MAP66_tg6_check(
const struct xt_tgchk_param *par)
{
const struct ip6t_MAP66_info *info = (const struct ip6t_MAP66_info *)par->targinfo;
if (0 >= info->prefixlength || 8 <= info->prefixlength) {
printk("MAP66: Unsupported prefix length /%d\n", 16 * info->prefixlength);
return false;
}
return true;
}
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,5,0)
static unsigned int MAP66_tg6_24(
struct sk_buff **pskb,
unsigned int hooknum,
const struct net_device *in,
const struct net_device *out,
const void *targinfo,
void *userinfo)
{
const struct xt_target_param par = {
.in = in,
.out = out,
.hooknum = hooknum,
.targinfo = targinfo,
};
return MAP66_tg6(*pskb, &par);
}
static int MAP66_tg6_check_24(
const char *table,
const struct ip6t_entry *entry,
void *targinfo,
unsigned int targinfosize,
unsigned int hook_mask)
{
const struct xt_tgchk_param par = {
.targinfo = targinfo,
};
if (0 != (hook_mask & ~((1 << NF_IP6_PRE_ROUTING) | (1 << NF_IP6_POST_ROUTING)))) {
printk("MAP66: Only valid for PRE_ROUTING or POST_ROUTING.\n");
return 0;
}
return MAP66_tg6_check(&par);
}
#elif LINUX_VERSION_CODE < KERNEL_VERSION(2,6,28)
static unsigned int MAP66_tg6_26(
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
unsigned int hooknum,
const struct xt_target *target,
const void *targinfo)
{
const struct xt_target_param par = {
.in = in,
.out = out,
.hooknum = hooknum,
.targinfo = targinfo,
};
return MAP66_tg6(skb, &par);
}
static bool MAP66_tg6_check_26(
const char *table,
const void *entryinfo,
const struct xt_target *target,
void *targinfo,
unsigned int hook_mask)
{
const struct xt_tgchk_param par = {
.targinfo = targinfo,
};
return MAP66_tg6_check(&par);
}
#endif
static struct xt_target MAP66_tg6_reg __read_mostly = {
.name = "MAP66",
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,5,0)
.target = MAP66_tg6_24,
.checkentry = MAP66_tg6_check_24,
#else
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,28)
.family = AF_INET6,
.target = MAP66_tg6_26,
.checkentry = MAP66_tg6_check_26,
.destroy = NULL,
#else
.family = NFPROTO_IPV6,
.target = MAP66_tg6,
.checkentry = MAP66_tg6_check,
#endif
.targetsize = sizeof(struct ip6t_MAP66_info),
.table = "mangle",
.hooks = (1 << NF_INET_POST_ROUTING) | (1 << NF_INET_PRE_ROUTING),
#endif
.me = THIS_MODULE,
};
static int __init MAP66_tg6_init(void)
{
return xt_register_target(&MAP66_tg6_reg);
}
static void __exit MAP66_tg6_exit(void)
{
xt_unregister_target(&MAP66_tg6_reg);
}
module_init(MAP66_tg6_init);
module_exit(MAP66_tg6_exit);
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