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DEFINITIONS
This source file includes following definitions.
- hbh_mt6
- hbh_mt6_check
- hbh_mt6_init
- hbh_mt6_exit
/* 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/x_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter_ipv6/ip6t_opts.h>
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Xtables: IPv6 Hop-By-Hop and Destination Header match");
MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
MODULE_ALIAS("ip6t_dst");
/*
* (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 bool
hbh_mt6(const struct sk_buff *skb, const struct xt_match_param *par)
{
struct ipv6_opt_hdr _optsh;
const struct ipv6_opt_hdr *oh;
const struct ip6t_opts *optinfo = par->matchinfo;
unsigned int temp;
unsigned int ptr;
unsigned int hdrlen = 0;
bool ret = false;
u8 _opttype;
u8 _optlen;
const u_int8_t *tp = NULL;
const u_int8_t *lp = NULL;
unsigned int optlen;
int err;
err = ipv6_find_hdr(skb, &ptr, par->match->data, NULL);
if (err < 0) {
if (err != -ENOENT)
*par->hotdrop = true;
return false;
}
oh = skb_header_pointer(skb, ptr, sizeof(_optsh), &_optsh);
if (oh == NULL) {
*par->hotdrop = true;
return false;
}
hdrlen = ipv6_optlen(oh);
if (skb->len - ptr < hdrlen) {
/* Packet smaller than it's length field */
return false;
}
pr_debug("IPv6 OPTS LEN %u %u ", hdrlen, oh->hdrlen);
pr_debug("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 {
pr_debug("Strict ");
pr_debug("#%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) {
pr_debug("Tbad %02X %02X\n", *tp,
(optinfo->opts[temp] & 0xFF00) >> 8);
return false;
} else {
pr_debug("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) {
pr_debug("Lbad %02X %04X\n", *lp,
spec_len);
return false;
}
pr_debug("Lok ");
optlen = *lp + 2;
} else {
pr_debug("Pad1\n");
optlen = 1;
}
/* Step to the next */
pr_debug("len%04X \n", optlen);
if ((ptr > skb->len - optlen || hdrlen < optlen) &&
temp < optinfo->optsnr - 1) {
pr_debug("new pointer is too large! \n");
break;
}
ptr += optlen;
hdrlen -= optlen;
}
if (temp == optinfo->optsnr)
return ret;
else
return false;
}
return false;
}
static bool hbh_mt6_check(const struct xt_mtchk_param *par)
{
const struct ip6t_opts *optsinfo = par->matchinfo;
if (optsinfo->invflags & ~IP6T_OPTS_INV_MASK) {
pr_debug("ip6t_opts: unknown flags %X\n", optsinfo->invflags);
return false;
}
if (optsinfo->flags & IP6T_OPTS_NSTRICT) {
pr_debug("ip6t_opts: Not strict - not implemented");
return false;
}
return true;
}
static struct xt_match hbh_mt6_reg[] __read_mostly = {
{
.name = "hbh",
.family = NFPROTO_IPV6,
.match = hbh_mt6,
.matchsize = sizeof(struct ip6t_opts),
.checkentry = hbh_mt6_check,
.me = THIS_MODULE,
.data = NEXTHDR_HOP,
},
{
.name = "dst",
.family = NFPROTO_IPV6,
.match = hbh_mt6,
.matchsize = sizeof(struct ip6t_opts),
.checkentry = hbh_mt6_check,
.me = THIS_MODULE,
.data = NEXTHDR_DEST,
},
};
static int __init hbh_mt6_init(void)
{
return xt_register_matches(hbh_mt6_reg, ARRAY_SIZE(hbh_mt6_reg));
}
static void __exit hbh_mt6_exit(void)
{
xt_unregister_matches(hbh_mt6_reg, ARRAY_SIZE(hbh_mt6_reg));
}
module_init(hbh_mt6_init);
module_exit(hbh_mt6_exit);