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/*
* This implements the ROUTE v6 target, which enables you to setup unusual
* routes not supported by the standard kernel routing table.
*
* Copyright (C) 2003 Cedric de Launois <delaunois@info.ucl.ac.be>
*
* v 1.1 2004/11/23
*
* This software is distributed under GNU GPL v2, 1991
*/
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ipv6.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter_ipv6/ip6t_ROUTE.h>
#include <linux/netdevice.h>
#include <net/ipv6.h>
#include <net/ndisc.h>
#include <net/ip6_route.h>
#include <linux/icmpv6.h>
#if 1
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif
#define NIP6(addr) \
ntohs((addr).s6_addr16[0]), \
ntohs((addr).s6_addr16[1]), \
ntohs((addr).s6_addr16[2]), \
ntohs((addr).s6_addr16[3]), \
ntohs((addr).s6_addr16[4]), \
ntohs((addr).s6_addr16[5]), \
ntohs((addr).s6_addr16[6]), \
ntohs((addr).s6_addr16[7])
/* Route the packet according to the routing keys specified in
* route_info. Keys are :
* - ifindex :
* 0 if no oif preferred,
* otherwise set to the index of the desired oif
* - route_info->gw :
* 0 if no gateway specified,
* otherwise set to the next host to which the pkt must be routed
* If success, skb->dev is the output device to which the packet must
* be sent and skb->dst is not NULL
*
* RETURN: 1 if the packet was succesfully routed to the
* destination desired
* 0 if the kernel routing table could not route the packet
* according to the keys specified
*/
static int
route6(struct sk_buff *skb,
unsigned int ifindex,
const struct ip6t_route_target_info *route_info)
{
struct rt6_info *rt = NULL;
struct ipv6hdr *ipv6h = skb->nh.ipv6h;
struct in6_addr *gw = (struct in6_addr*)&route_info->gw;
DEBUGP("ip6t_ROUTE: called with: ");
DEBUGP("DST=%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x ", NIP6(ipv6h->daddr));
DEBUGP("GATEWAY=%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x ", NIP6(*gw));
DEBUGP("OUT=%s\n", route_info->oif);
if (ipv6_addr_any(gw))
rt = rt6_lookup(&ipv6h->daddr, &ipv6h->saddr, ifindex, 1);
else
rt = rt6_lookup(gw, &ipv6h->saddr, ifindex, 1);
if (!rt)
goto no_route;
DEBUGP("ip6t_ROUTE: routing gives: ");
DEBUGP("DST=%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x ", NIP6(rt->rt6i_dst.addr));
DEBUGP("GATEWAY=%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x ", NIP6(rt->rt6i_gateway));
DEBUGP("OUT=%s\n", rt->rt6i_dev->name);
if (ifindex && rt->rt6i_dev->ifindex!=ifindex)
goto wrong_route;
if (!rt->rt6i_nexthop) {
DEBUGP("ip6t_ROUTE: discovering neighbour\n");
rt->rt6i_nexthop = ndisc_get_neigh(rt->rt6i_dev, &rt->rt6i_dst.addr);
}
/* Drop old route. */
dst_release(skb->dst);
skb->dst = &rt->u.dst;
skb->dev = rt->rt6i_dev;
return 1;
wrong_route:
dst_release(&rt->u.dst);
no_route:
if (!net_ratelimit())
return 0;
printk("ip6t_ROUTE: no explicit route found ");
if (ifindex)
printk("via interface %s ", route_info->oif);
if (!ipv6_addr_any(gw))
printk("via gateway %04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x", NIP6(*gw));
printk("\n");
return 0;
}
/* Stolen from ip6_output_finish
* PRE : skb->dev is set to the device we are leaving by
* skb->dst is not NULL
* POST: the packet is sent with the link layer header pushed
* the packet is destroyed
*/
static void ip_direct_send(struct sk_buff *skb)
{
struct dst_entry *dst = skb->dst;
struct hh_cache *hh = dst->hh;
if (hh) {
read_lock_bh(&hh->hh_lock);
memcpy(skb->data - 16, hh->hh_data, 16);
read_unlock_bh(&hh->hh_lock);
skb_push(skb, hh->hh_len);
hh->hh_output(skb);
} else if (dst->neighbour)
dst->neighbour->output(skb);
else {
if (net_ratelimit())
DEBUGP(KERN_DEBUG "ip6t_ROUTE: no hdr & no neighbour cache!\n");
kfree_skb(skb);
}
}
static unsigned int
route6_oif(const struct ip6t_route_target_info *route_info,
struct sk_buff *skb)
{
unsigned int ifindex = 0;
struct net_device *dev_out = NULL;
/* The user set the interface name to use.
* Getting the current interface index.
*/
if ((dev_out = dev_get_by_name(route_info->oif))) {
ifindex = dev_out->ifindex;
} else {
/* Unknown interface name : packet dropped */
if (net_ratelimit())
DEBUGP("ip6t_ROUTE: oif interface %s not found\n", route_info->oif);
if (route_info->flags & IP6T_ROUTE_CONTINUE)
return IP6T_CONTINUE;
else
return NF_DROP;
}
/* Trying the standard way of routing packets */
if (route6(skb, ifindex, route_info)) {
dev_put(dev_out);
if (route_info->flags & IP6T_ROUTE_CONTINUE)
return IP6T_CONTINUE;
ip_direct_send(skb);
return NF_STOLEN;
} else
return NF_DROP;
}
static unsigned int
route6_gw(const struct ip6t_route_target_info *route_info,
struct sk_buff *skb)
{
if (route6(skb, 0, route_info)) {
if (route_info->flags & IP6T_ROUTE_CONTINUE)
return IP6T_CONTINUE;
ip_direct_send(skb);
return NF_STOLEN;
} else
return NF_DROP;
}
static unsigned int
ip6t_route_target(struct sk_buff **pskb,
unsigned int hooknum,
const struct net_device *in,
const struct net_device *out,
const void *targinfo,
void *userinfo)
{
const struct ip6t_route_target_info *route_info = targinfo;
struct sk_buff *skb = *pskb;
struct in6_addr *gw = (struct in6_addr*)&route_info->gw;
unsigned int res;
if (route_info->flags & IP6T_ROUTE_CONTINUE)
goto do_it;
/* If we are at PREROUTING or INPUT hook
* the TTL isn't decreased by the IP stack
*/
if (hooknum == NF_IP6_PRE_ROUTING ||
hooknum == NF_IP6_LOCAL_IN) {
struct ipv6hdr *ipv6h = skb->nh.ipv6h;
if (ipv6h->hop_limit <= 1) {
/* Force OUTPUT device used as source address */
skb->dev = skb->dst->dev;
icmpv6_send(skb, ICMPV6_TIME_EXCEED,
ICMPV6_EXC_HOPLIMIT, 0, skb->dev);
return NF_DROP;
}
ipv6h->hop_limit--;
}
if ((route_info->flags & IP6T_ROUTE_TEE)) {
/*
* Copy the *pskb, and route the copy. Will later return
* IP6T_CONTINUE for the original skb, which should continue
* on its way as if nothing happened. The copy should be
* independantly delivered to the ROUTE --gw.
*/
skb = skb_copy(*pskb, GFP_ATOMIC);
if (!skb) {
if (net_ratelimit())
DEBUGP(KERN_DEBUG "ip6t_ROUTE: copy failed!\n");
return IP6T_CONTINUE;
}
}
do_it:
if (route_info->oif[0]) {
res = route6_oif(route_info, skb);
} else if (!ipv6_addr_any(gw)) {
res = route6_gw(route_info, skb);
} else {
if (net_ratelimit())
DEBUGP(KERN_DEBUG "ip6t_ROUTE: no parameter !\n");
res = IP6T_CONTINUE;
}
if ((route_info->flags & IP6T_ROUTE_TEE))
res = IP6T_CONTINUE;
return res;
}
static int
ip6t_route_checkentry(const char *tablename,
const struct ip6t_entry *e,
void *targinfo,
unsigned int targinfosize,
unsigned int hook_mask)
{
if (strcmp(tablename, "mangle") != 0) {
printk("ip6t_ROUTE: can only be called from \"mangle\" table.\n");
return 0;
}
if (targinfosize != IP6T_ALIGN(sizeof(struct ip6t_route_target_info))) {
printk(KERN_WARNING "ip6t_ROUTE: targinfosize %u != %Zu\n",
targinfosize,
IP6T_ALIGN(sizeof(struct ip6t_route_target_info)));
return 0;
}
return 1;
}
static struct ip6t_target ip6t_route_reg = {
.name = "ROUTE",
.target = ip6t_route_target,
.checkentry = ip6t_route_checkentry,
.me = THIS_MODULE
};
static int __init init(void)
{
printk(KERN_DEBUG "registering ipv6 ROUTE target\n");
if (ip6t_register_target(&ip6t_route_reg))
return -EINVAL;
return 0;
}
static void __exit fini(void)
{
ip6t_unregister_target(&ip6t_route_reg);
}
module_init(init);
module_exit(fini);
MODULE_LICENSE("GPL");
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