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/*
* ip_nat_proto_esp.c - Version 0.1
*
* NAT protocol helper module for ESP.
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/ip.h>
#include <linux/netfilter_ipv4/ip_nat.h>
#include <linux/netfilter_ipv4/ip_nat_rule.h>
#include <linux/netfilter_ipv4/ip_nat_protocol.h>
#include <linux/netfilter_ipv4/ip_conntrack_proto_esp.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
MODULE_DESCRIPTION("Netfilter NAT protocol helper module for ESP");
#if 0
//#define DEBUGP(format, args...) printk(KERN_DEBUG __FILE__ ":" __FUNCTION__": " format, ## args)
#define DEBUGP printk
#define DUMP_TUPLE_ESP(x) printk("%u.%u.%u.%u:0x%x -> %u.%u.%u.%u:0x%x\n", \
NIPQUAD((x)->src.ip), ntohl((x)->src.u.esp.spi), \
NIPQUAD((x)->dst.ip), ntohl((x)->dst.u.esp.spi))
#else
#define DUMP_TUPLE_ESP(x)
#define DEBUGP(x, args...)
#endif
/* is key in given range between min and max */
static int
esp_in_range(const struct ip_conntrack_tuple *tuple,
enum ip_nat_manip_type maniptype,
const union ip_conntrack_manip_proto *min,
const union ip_conntrack_manip_proto *max)
{
unsigned int spi;
DEBUGP("esp_in_range entry.\n");
return 0;
if (maniptype == IP_NAT_MANIP_SRC)
spi = tuple->src.u.esp.spi;
else
spi = tuple->dst.u.esp.spi;
DUMP_TUPLE_ESP(tuple);
return (ntohl(spi) >= ntohl(min->esp.spi) &&
ntohl(spi) <= ntohl(max->esp.spi));
}
/* generate unique tuple ... */
static int
esp_unique_tuple(struct ip_conntrack_tuple *tuple,
const struct ip_nat_range *range,
enum ip_nat_manip_type maniptype,
const struct ip_conntrack *conntrack)
{
u_int32_t min, i, range_size;
u_int32_t key = 0, *spi = NULL;
DEBUGP("esp_unique_tuple entry.\n");
return 1;
DUMP_TUPLE_ESP(tuple);
if (maniptype == IP_NAT_MANIP_SRC)
spi = &tuple->src.u.esp.spi;
else
spi = &tuple->dst.u.esp.spi;
/*range is to do fast search*/
if (! (range->flags & IP_NAT_RANGE_PROTO_SPECIFIED))
{
DEBUGP("NATing ESP (ct = %p)\n",conntrack);
min = 1;
range_size = 0xffffffff;
}
else
{
min = ntohl(range->min.esp.spi);
range_size = ntohl(range->max.esp.spi) - min + 1;
}
DEBUGP("min = %u, range_size = %u\n", min, range_size);
for (i = 0; i < range_size; i++, key++) {
*spi = htonl(min + key % range_size);
if (!ip_nat_used_tuple(tuple, conntrack))
return 1;
}
DEBUGP("%p: no NAT mapping\n", conntrack);
return 0;
}
/* manipulate a ESP packet according to maniptype */
static void
esp_manip_pkt(struct iphdr *iph, size_t len,
const struct ip_conntrack_manip *manip,
enum ip_nat_manip_type maniptype)
{
struct esp_hdr *esph = (struct esp_hdr *)((u_int32_t *)iph+iph->ihl);
u_int32_t *old_ip;
u_int32_t *old_spi =NULL;
u_int32_t sip = 0, dip =0,ret = 0;
DEBUGP("\n@@@@ %s @@@@\n", __FUNCTION__);
DEBUGP("dir =[%d] manip [%u.%u.%u.%u] spi[%x].\n "
"ip_header sip[%u.%u.%u.%u]dip[%u.%u.%u.%u].\n"
"spi[0x%x] seq[%u].\n",
maniptype,NIPQUAD(manip->ip),ntohl(manip->u.esp.spi),
NIPQUAD(iph->saddr),NIPQUAD(iph->daddr),ntohl(esph->spi),ntohl(esph->seq));
/*keep data to tuple struct*/
if (maniptype == IP_NAT_MANIP_SRC)
{
/* Get rid of dst ip / spi */
old_ip = &iph->daddr; //here orignal ip header
old_spi =&esph->spi;
}
else
{
ret = esp_packet_in(iph,&sip,&dip);
if (ret == NF_ACCEPT)
{
DEBUGP("found !! sip[%u.%u.%u.%u]dip[%u.%u.%u.%u]\n",
NIPQUAD(sip),NIPQUAD(dip));
old_ip = &dip; //here orignal ip header
old_spi = &esph->spi;
}
else
{
DEBUGP("Not found !! sip[%u.%u.%u.%u]dip[%u.%u.%u.%u]\n",
NIPQUAD(sip),NIPQUAD(dip));
/* Get rid of dst ip / spi */
old_ip = &iph->daddr; //here orignal ip header
old_spi = &esph->spi;
}
}
}
/* print out a nat tuple */
static unsigned int
esp_print(char *buffer,
const struct ip_conntrack_tuple *match,
const struct ip_conntrack_tuple *mask)
{
unsigned int len = 0;
DEBUGP("esp_print entry.\n");
DEBUGP("match.....\n");
DUMP_TUPLE_ESP(match);
DEBUGP("mask.....\n");
DUMP_TUPLE_ESP(mask);
DEBUGP("end.....\n\n");
return 0;
if (mask->dst.u.esp.spi)
len += sprintf(buffer + len, "dst spi=[0x%x]",
ntohl(match->dst.u.esp.spi));
if (mask->src.u.esp.spi)
len += sprintf(buffer + len, "src spi=0x%x ",
ntohl(match->src.u.esp.spi));
return len;
}
/* print a range of keys */
static unsigned int
esp_print_range(char *buffer, const struct ip_nat_range *range)
{
DEBUGP("esp_print_range entry.\n");
return 0;
if (range->min.esp.spi != 0
|| range->max.esp.spi != 0xFFFFFFFF)
{
if (range->min.esp.spi == range->max.esp.spi)
return sprintf(buffer, "ESP SPI 0x%x ",
ntohl(range->min.esp.spi));
else
return sprintf(buffer, "ESP SPI 0x%u-0x%u ",
ntohl(range->min.esp.spi),
ntohl(range->max.esp.spi));
} else
return 0;
}
/* nat helper struct */
static struct ip_nat_protocol esp =
{
{ NULL, NULL },
"ESP",
IPPROTO_ESP,
esp_manip_pkt,
esp_in_range,
esp_unique_tuple,
esp_print,
esp_print_range
};
static int __init init(void)
{
if (ip_nat_protocol_register(&esp))
return -EIO;
DEBUGP("init IP_nat_proto_esp register.\n");
return 0;
}
static void __exit fini(void)
{
DEBUGP("uninit IP_nat_proto_esp register.\n");
ip_nat_protocol_unregister(&esp);
}
module_init(init);
module_exit(fini);
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