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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 | /* Kernel module to match AH parameters. */
/* (C) 1999-2000 Yon Uriarte <yon@astaro.de>
*
* 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/ip.h>
#include <linux/netfilter_ipv4/ipt_ah.h>
#include <linux/netfilter_ipv4/ip_tables.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>");
MODULE_DESCRIPTION("iptables AH SPI match module");
#ifdef DEBUG_CONNTRACK
#define duprintf(format, args...) printk(format , ## args)
#else
#define duprintf(format, args...)
#endif
/* Returns 1 if the spi is matched by the range, 0 otherwise */
static inline int
spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert)
{
int r=0;
duprintf("ah spi_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ',
min,spi,max);
r=(spi >= min && spi <= max) ^ invert;
duprintf(" result %s\n",r? "PASS" : "FAILED");
return r;
}
static int
match(const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const void *matchinfo,
int offset,
int *hotdrop)
{
struct ip_auth_hdr ah;
const struct ipt_ah *ahinfo = matchinfo;
/* Must not be a fragment. */
if (offset)
return 0;
if (skb_copy_bits(skb, skb->nh.iph->ihl*4, &ah, sizeof(ah)) < 0) {
/* We've been asked to examine this packet, and we
can't. Hence, no choice but to drop. */
duprintf("Dropping evil AH tinygram.\n");
*hotdrop = 1;
return 0;
}
return spi_match(ahinfo->spis[0], ahinfo->spis[1],
ntohl(ah.spi),
!!(ahinfo->invflags & IPT_AH_INV_SPI));
}
/* Called when user tries to insert an entry of this type. */
static int
checkentry(const char *tablename,
const struct ipt_ip *ip,
void *matchinfo,
unsigned int matchinfosize,
unsigned int hook_mask)
{
const struct ipt_ah *ahinfo = matchinfo;
/* Must specify proto == AH, and no unknown invflags */
if (ip->proto != IPPROTO_AH || (ip->invflags & IPT_INV_PROTO)) {
duprintf("ipt_ah: Protocol %u != %u\n", ip->proto,
IPPROTO_AH);
return 0;
}
if (matchinfosize != IPT_ALIGN(sizeof(struct ipt_ah))) {
duprintf("ipt_ah: matchsize %u != %u\n",
matchinfosize, IPT_ALIGN(sizeof(struct ipt_ah)));
return 0;
}
if (ahinfo->invflags & ~IPT_AH_INV_MASK) {
duprintf("ipt_ah: unknown flags %X\n",
ahinfo->invflags);
return 0;
}
return 1;
}
static struct ipt_match ah_match = {
.name = "ah",
.match = &match,
.checkentry = &checkentry,
.me = THIS_MODULE,
};
static int __init init(void)
{
return ipt_register_match(&ah_match);
}
static void __exit cleanup(void)
{
ipt_unregister_match(&ah_match);
}
module_init(init);
module_exit(cleanup);
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