225 lines
5.3 KiB
C
225 lines
5.3 KiB
C
/* Kernel module to match Hop-by-Hop and Destination parameters. */
|
|
|
|
/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/skbuff.h>
|
|
#include <linux/ipv6.h>
|
|
#include <linux/types.h>
|
|
#include <net/checksum.h>
|
|
#include <net/ipv6.h>
|
|
|
|
#include <asm/byteorder.h>
|
|
|
|
#include <linux/netfilter_ipv6/ip6_tables.h>
|
|
#include <linux/netfilter_ipv6/ip6t_opts.h>
|
|
|
|
#define HOPBYHOP 1
|
|
|
|
MODULE_LICENSE("GPL");
|
|
#if HOPBYHOP
|
|
MODULE_DESCRIPTION("IPv6 HbH match");
|
|
#else
|
|
MODULE_DESCRIPTION("IPv6 DST match");
|
|
#endif
|
|
MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
|
|
|
|
#if 0
|
|
#define DEBUGP printk
|
|
#else
|
|
#define DEBUGP(format, args...)
|
|
#endif
|
|
|
|
/*
|
|
* (Type & 0xC0) >> 6
|
|
* 0 -> ignorable
|
|
* 1 -> must drop the packet
|
|
* 2 -> send ICMP PARM PROB regardless and drop packet
|
|
* 3 -> Send ICMP if not a multicast address and drop packet
|
|
* (Type & 0x20) >> 5
|
|
* 0 -> invariant
|
|
* 1 -> can change the routing
|
|
* (Type & 0x1F) Type
|
|
* 0 -> Pad1 (only 1 byte!)
|
|
* 1 -> PadN LENGTH info (total length = length + 2)
|
|
* C0 | 2 -> JUMBO 4 x x x x ( xxxx > 64k )
|
|
* 5 -> RTALERT 2 x x
|
|
*/
|
|
|
|
static int
|
|
match(const struct sk_buff *skb,
|
|
const struct net_device *in,
|
|
const struct net_device *out,
|
|
const void *matchinfo,
|
|
int offset,
|
|
unsigned int protoff,
|
|
int *hotdrop)
|
|
{
|
|
struct ipv6_opt_hdr _optsh, *oh;
|
|
const struct ip6t_opts *optinfo = matchinfo;
|
|
unsigned int temp;
|
|
unsigned int ptr;
|
|
unsigned int hdrlen = 0;
|
|
unsigned int ret = 0;
|
|
u8 _opttype, *tp = NULL;
|
|
u8 _optlen, *lp = NULL;
|
|
unsigned int optlen;
|
|
|
|
#if HOPBYHOP
|
|
if (ipv6_find_hdr(skb, &ptr, NEXTHDR_HOP) < 0)
|
|
#else
|
|
if (ipv6_find_hdr(skb, &ptr, NEXTHDR_DEST) < 0)
|
|
#endif
|
|
return 0;
|
|
|
|
oh = skb_header_pointer(skb, ptr, sizeof(_optsh), &_optsh);
|
|
if (oh == NULL){
|
|
*hotdrop = 1;
|
|
return 0;
|
|
}
|
|
|
|
hdrlen = ipv6_optlen(oh);
|
|
if (skb->len - ptr < hdrlen){
|
|
/* Packet smaller than it's length field */
|
|
return 0;
|
|
}
|
|
|
|
DEBUGP("IPv6 OPTS LEN %u %u ", hdrlen, oh->hdrlen);
|
|
|
|
DEBUGP("len %02X %04X %02X ",
|
|
optinfo->hdrlen, hdrlen,
|
|
(!(optinfo->flags & IP6T_OPTS_LEN) ||
|
|
((optinfo->hdrlen == hdrlen) ^
|
|
!!(optinfo->invflags & IP6T_OPTS_INV_LEN))));
|
|
|
|
ret = (oh != NULL)
|
|
&&
|
|
(!(optinfo->flags & IP6T_OPTS_LEN) ||
|
|
((optinfo->hdrlen == hdrlen) ^
|
|
!!(optinfo->invflags & IP6T_OPTS_INV_LEN)));
|
|
|
|
ptr += 2;
|
|
hdrlen -= 2;
|
|
if ( !(optinfo->flags & IP6T_OPTS_OPTS) ){
|
|
return ret;
|
|
} else if (optinfo->flags & IP6T_OPTS_NSTRICT) {
|
|
DEBUGP("Not strict - not implemented");
|
|
} else {
|
|
DEBUGP("Strict ");
|
|
DEBUGP("#%d ",optinfo->optsnr);
|
|
for(temp=0; temp<optinfo->optsnr; temp++){
|
|
/* type field exists ? */
|
|
if (hdrlen < 1)
|
|
break;
|
|
tp = skb_header_pointer(skb, ptr, sizeof(_opttype),
|
|
&_opttype);
|
|
if (tp == NULL)
|
|
break;
|
|
|
|
/* Type check */
|
|
if (*tp != (optinfo->opts[temp] & 0xFF00)>>8){
|
|
DEBUGP("Tbad %02X %02X\n",
|
|
*tp,
|
|
(optinfo->opts[temp] & 0xFF00)>>8);
|
|
return 0;
|
|
} else {
|
|
DEBUGP("Tok ");
|
|
}
|
|
/* Length check */
|
|
if (*tp) {
|
|
u16 spec_len;
|
|
|
|
/* length field exists ? */
|
|
if (hdrlen < 2)
|
|
break;
|
|
lp = skb_header_pointer(skb, ptr + 1,
|
|
sizeof(_optlen),
|
|
&_optlen);
|
|
if (lp == NULL)
|
|
break;
|
|
spec_len = optinfo->opts[temp] & 0x00FF;
|
|
|
|
if (spec_len != 0x00FF && spec_len != *lp) {
|
|
DEBUGP("Lbad %02X %04X\n", *lp,
|
|
spec_len);
|
|
return 0;
|
|
}
|
|
DEBUGP("Lok ");
|
|
optlen = *lp + 2;
|
|
} else {
|
|
DEBUGP("Pad1\n");
|
|
optlen = 1;
|
|
}
|
|
|
|
/* Step to the next */
|
|
DEBUGP("len%04X \n", optlen);
|
|
|
|
if ((ptr > skb->len - optlen || hdrlen < optlen) &&
|
|
(temp < optinfo->optsnr - 1)) {
|
|
DEBUGP("new pointer is too large! \n");
|
|
break;
|
|
}
|
|
ptr += optlen;
|
|
hdrlen -= optlen;
|
|
}
|
|
if (temp == optinfo->optsnr)
|
|
return ret;
|
|
else return 0;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* Called when user tries to insert an entry of this type. */
|
|
static int
|
|
checkentry(const char *tablename,
|
|
const struct ip6t_ip6 *ip,
|
|
void *matchinfo,
|
|
unsigned int matchinfosize,
|
|
unsigned int hook_mask)
|
|
{
|
|
const struct ip6t_opts *optsinfo = matchinfo;
|
|
|
|
if (matchinfosize != IP6T_ALIGN(sizeof(struct ip6t_opts))) {
|
|
DEBUGP("ip6t_opts: matchsize %u != %u\n",
|
|
matchinfosize, IP6T_ALIGN(sizeof(struct ip6t_opts)));
|
|
return 0;
|
|
}
|
|
if (optsinfo->invflags & ~IP6T_OPTS_INV_MASK) {
|
|
DEBUGP("ip6t_opts: unknown flags %X\n",
|
|
optsinfo->invflags);
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
static struct ip6t_match opts_match = {
|
|
#if HOPBYHOP
|
|
.name = "hbh",
|
|
#else
|
|
.name = "dst",
|
|
#endif
|
|
.match = &match,
|
|
.checkentry = &checkentry,
|
|
.me = THIS_MODULE,
|
|
};
|
|
|
|
static int __init init(void)
|
|
{
|
|
return ip6t_register_match(&opts_match);
|
|
}
|
|
|
|
static void __exit cleanup(void)
|
|
{
|
|
ip6t_unregister_match(&opts_match);
|
|
}
|
|
|
|
module_init(init);
|
|
module_exit(cleanup);
|