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/* 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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#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("Xtables: IPv6 fragment 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("id_match:%c 0x%x <= 0x%x <= 0x%x\n", invert ? '!' : ' ',
min, id, max);
r = (id >= min && id <= max) ^ invert;
pr_debug(" result %s\n", r ? "PASS" : "FAILED");
return r;
}
static bool
frag_mt6(const struct sk_buff *skb, const struct xt_match_param *par)
{
struct frag_hdr _frag;
const struct frag_hdr *fh;
const struct ip6t_frag *fraginfo = par->matchinfo;
unsigned int ptr;
int err;
err = ipv6_find_hdr(skb, &ptr, NEXTHDR_FRAGMENT, NULL);
if (err < 0) {
if (err != -ENOENT)
*par->hotdrop = true;
return false;
}
fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag);
if (fh == NULL) {
*par->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));
}
static int frag_mt6_check(const struct xt_mtchk_param *par)
{
const struct ip6t_frag *fraginfo = par->matchinfo;
if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) {
pr_debug("unknown flags %X\n", fraginfo->invflags);
return -EINVAL;
}
return 0;
}
static struct xt_match frag_mt6_reg __read_mostly = {
.name = "frag",
.family = NFPROTO_IPV6,
.match = frag_mt6,
.matchsize = sizeof(struct ip6t_frag),
.checkentry = frag_mt6_check,
.me = THIS_MODULE,
};
static int __init frag_mt6_init(void)
{
return xt_register_match(&frag_mt6_reg);
}
static void __exit frag_mt6_exit(void)
{
xt_unregister_match(&frag_mt6_reg);
}
module_init(frag_mt6_init);
module_exit(frag_mt6_exit);
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