blob: 968aeba020737856abb6e1de3f4803849c9c2e2e [file] [log] [blame]
/* Kernel module to match FRAG 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 <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter_ipv6/ip6t_frag.h>
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("IPv6 FRAG match");
MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
/* Returns 1 if the id is matched by the range, 0 otherwise */
static inline bool
id_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert)
{
bool r;
pr_debug("frag id_match:%c 0x%x <= 0x%x <= 0x%x", invert ? '!' : ' ',
min, id, max);
r = (id >= min && id <= max) ^ invert;
pr_debug(" result %s\n", r ? "PASS" : "FAILED");
return r;
}
static bool
match(const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const struct xt_match *match,
const void *matchinfo,
int offset,
unsigned int protoff,
bool *hotdrop)
{
struct frag_hdr _frag;
const struct frag_hdr *fh;
const struct ip6t_frag *fraginfo = matchinfo;
unsigned int ptr;
int err;
err = ipv6_find_hdr(skb, &ptr, NEXTHDR_FRAGMENT, NULL);
if (err < 0) {
if (err != -ENOENT)
*hotdrop = true;
return false;
}
fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag);
if (fh == NULL) {
*hotdrop = true;
return false;
}
pr_debug("INFO %04X ", fh->frag_off);
pr_debug("OFFSET %04X ", ntohs(fh->frag_off) & ~0x7);
pr_debug("RES %02X %04X", fh->reserved, ntohs(fh->frag_off) & 0x6);
pr_debug("MF %04X ", fh->frag_off & htons(IP6_MF));
pr_debug("ID %u %08X\n", ntohl(fh->identification),
ntohl(fh->identification));
pr_debug("IPv6 FRAG id %02X ",
id_match(fraginfo->ids[0], fraginfo->ids[1],
ntohl(fh->identification),
!!(fraginfo->invflags & IP6T_FRAG_INV_IDS)));
pr_debug("res %02X %02X%04X %02X ",
fraginfo->flags & IP6T_FRAG_RES, fh->reserved,
ntohs(fh->frag_off) & 0x6,
!((fraginfo->flags & IP6T_FRAG_RES)
&& (fh->reserved || (ntohs(fh->frag_off) & 0x06))));
pr_debug("first %02X %02X %02X ",
fraginfo->flags & IP6T_FRAG_FST,
ntohs(fh->frag_off) & ~0x7,
!((fraginfo->flags & IP6T_FRAG_FST)
&& (ntohs(fh->frag_off) & ~0x7)));
pr_debug("mf %02X %02X %02X ",
fraginfo->flags & IP6T_FRAG_MF,
ntohs(fh->frag_off) & IP6_MF,
!((fraginfo->flags & IP6T_FRAG_MF)
&& !((ntohs(fh->frag_off) & IP6_MF))));
pr_debug("last %02X %02X %02X\n",
fraginfo->flags & IP6T_FRAG_NMF,
ntohs(fh->frag_off) & IP6_MF,
!((fraginfo->flags & IP6T_FRAG_NMF)
&& (ntohs(fh->frag_off) & IP6_MF)));
return (fh != NULL)
&&
id_match(fraginfo->ids[0], fraginfo->ids[1],
ntohl(fh->identification),
!!(fraginfo->invflags & IP6T_FRAG_INV_IDS))
&&
!((fraginfo->flags & IP6T_FRAG_RES)
&& (fh->reserved || (ntohs(fh->frag_off) & 0x6)))
&&
!((fraginfo->flags & IP6T_FRAG_FST)
&& (ntohs(fh->frag_off) & ~0x7))
&&
!((fraginfo->flags & IP6T_FRAG_MF)
&& !(ntohs(fh->frag_off) & IP6_MF))
&&
!((fraginfo->flags & IP6T_FRAG_NMF)
&& (ntohs(fh->frag_off) & IP6_MF));
}
/* Called when user tries to insert an entry of this type. */
static bool
checkentry(const char *tablename,
const void *ip,
const struct xt_match *match,
void *matchinfo,
unsigned int hook_mask)
{
const struct ip6t_frag *fraginfo = matchinfo;
if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) {
pr_debug("ip6t_frag: unknown flags %X\n", fraginfo->invflags);
return false;
}
return true;
}
static struct xt_match frag_match __read_mostly = {
.name = "frag",
.family = AF_INET6,
.match = match,
.matchsize = sizeof(struct ip6t_frag),
.checkentry = checkentry,
.me = THIS_MODULE,
};
static int __init ip6t_frag_init(void)
{
return xt_register_match(&frag_match);
}
static void __exit ip6t_frag_fini(void)
{
xt_unregister_match(&frag_match);
}
module_init(ip6t_frag_init);
module_exit(ip6t_frag_fini);