[net-next-2.6.git] / net / ipv4 / netfilter / ipt_ah.c

/* 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.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/in.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>

#include <linux/netfilter_ipv4/ipt_ah.h>
#include <linux/netfilter/x_tables.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>");
MODULE_DESCRIPTION("Xtables: IPv4 IPsec-AH SPI match");

/* Returns 1 if the spi is matched by the range, 0 otherwise */
static inline bool
spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)
{
	bool r;
	pr_debug("spi_match:%c 0x%x <= 0x%x <= 0x%x\n",
		 invert ? '!' : ' ', min, spi, max);
	r=(spi >= min && spi <= max) ^ invert;
	pr_debug(" result %s\n", r ? "PASS" : "FAILED");
	return r;
}

static bool ah_mt(const struct sk_buff *skb, const struct xt_action_param *par)
{
	struct ip_auth_hdr _ahdr;
	const struct ip_auth_hdr *ah;
	const struct ipt_ah *ahinfo = par->matchinfo;

	/* Must not be a fragment. */
	if (par->fragoff != 0)
		return false;

	ah = skb_header_pointer(skb, par->thoff, sizeof(_ahdr), &_ahdr);
	if (ah == NULL) {
		/* We've been asked to examine this packet, and we
		 * can't.  Hence, no choice but to drop.
		 */
		pr_debug("Dropping evil AH tinygram.\n");
		*par->hotdrop = true;
		return 0;
	}

	return spi_match(ahinfo->spis[0], ahinfo->spis[1],
			 ntohl(ah->spi),
			 !!(ahinfo->invflags & IPT_AH_INV_SPI));
}

static int ah_mt_check(const struct xt_mtchk_param *par)
{
	const struct ipt_ah *ahinfo = par->matchinfo;

	/* Must specify no unknown invflags */
	if (ahinfo->invflags & ~IPT_AH_INV_MASK) {
		pr_debug("unknown flags %X\n", ahinfo->invflags);
		return -EINVAL;
	}
	return 0;
}

static struct xt_match ah_mt_reg __read_mostly = {
	.name		= "ah",
	.family		= NFPROTO_IPV4,
	.match		= ah_mt,
	.matchsize	= sizeof(struct ipt_ah),
	.proto		= IPPROTO_AH,
	.checkentry	= ah_mt_check,
	.me		= THIS_MODULE,
};

static int __init ah_mt_init(void)
{
	return xt_register_match(&ah_mt_reg);
}

static void __exit ah_mt_exit(void)
{
	xt_unregister_match(&ah_mt_reg);
}

module_init(ah_mt_init);
module_exit(ah_mt_exit);
Commit	Line	Data
1da177e4 LT	1	/* Kernel module to match AH parameters. */
	2	/* (C) 1999-2000 Yon Uriarte <yon@astaro.de>
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License version 2 as
	6	* published by the Free Software Foundation.
	7	*/
be91fd5e	8	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
6709dbbb	9	#include <linux/in.h>
1da177e4 LT	10	#include <linux/module.h>
	11	#include <linux/skbuff.h>
	12	#include <linux/ip.h>
	13
	14	#include <linux/netfilter_ipv4/ipt_ah.h>
6709dbbb	15	#include <linux/netfilter/x_tables.h>
1da177e4 LT	16
	17	MODULE_LICENSE("GPL");
	18	MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>");
2ae15b64	19	MODULE_DESCRIPTION("Xtables: IPv4 IPsec-AH SPI match");
1da177e4	20
1da177e4	21	/* Returns 1 if the spi is matched by the range, 0 otherwise */
1d93a9cb JE	22	static inline bool
1d93a9cb JE	23	spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)
1da177e4	24	{
1d93a9cb	25	bool r;
be91fd5e JE	26	pr_debug("spi_match:%c 0x%x <= 0x%x <= 0x%x\n",
be91fd5e JE	27	invert ? '!' : ' ', min, spi, max);
1da177e4	28	r=(spi >= min && spi <= max) ^ invert;
be91fd5e	29	pr_debug(" result %s\n", r ? "PASS" : "FAILED");
1da177e4 LT	30	return r;
	31	}
	32
4b560b44	33	static bool ah_mt(const struct sk_buff skb, const struct xt_action_param par)
1da177e4	34	{
a47362a2 JE	35	struct ip_auth_hdr _ahdr;
a47362a2 JE	36	const struct ip_auth_hdr *ah;
f7108a20	37	const struct ipt_ah *ahinfo = par->matchinfo;
1da177e4 LT	38
1da177e4 LT	39	/* Must not be a fragment. */
f7108a20	40	if (par->fragoff != 0)
1d93a9cb	41	return false;
1da177e4	42
f7108a20	43	ah = skb_header_pointer(skb, par->thoff, sizeof(_ahdr), &_ahdr);
1da177e4 LT	44	if (ah == NULL) {
	45	/* We've been asked to examine this packet, and we
	46	* can't. Hence, no choice but to drop.
	47	*/
be91fd5e	48	pr_debug("Dropping evil AH tinygram.\n");
f7108a20	49	*par->hotdrop = true;
1da177e4 LT	50	return 0;
	51	}
	52
	53	return spi_match(ahinfo->spis[0], ahinfo->spis[1],
	54	ntohl(ah->spi),
	55	!!(ahinfo->invflags & IPT_AH_INV_SPI));
	56	}
	57
b0f38452	58	static int ah_mt_check(const struct xt_mtchk_param *par)
1da177e4	59	{
9b4fce7a	60	const struct ipt_ah *ahinfo = par->matchinfo;
1da177e4	61
1d5cd909	62	/* Must specify no unknown invflags */
1da177e4	63	if (ahinfo->invflags & ~IPT_AH_INV_MASK) {
be91fd5e	64	pr_debug("unknown flags %X\n", ahinfo->invflags);
bd414ee6	65	return -EINVAL;
1da177e4	66	}
bd414ee6	67	return 0;
1da177e4 LT	68	}
1da177e4 LT	69
d3c5ee6d	70	static struct xt_match ah_mt_reg __read_mostly = {
1da177e4	71	.name = "ah",
ee999d8b	72	.family = NFPROTO_IPV4,
d3c5ee6d	73	.match = ah_mt,
1d5cd909 PM	74	.matchsize = sizeof(struct ipt_ah),
1d5cd909 PM	75	.proto = IPPROTO_AH,
d3c5ee6d	76	.checkentry = ah_mt_check,
1da177e4 LT	77	.me = THIS_MODULE,
	78	};
	79
d3c5ee6d	80	static int __init ah_mt_init(void)
1da177e4	81	{
d3c5ee6d	82	return xt_register_match(&ah_mt_reg);
1da177e4 LT	83	}
1da177e4 LT	84
d3c5ee6d	85	static void __exit ah_mt_exit(void)
1da177e4	86	{
d3c5ee6d	87	xt_unregister_match(&ah_mt_reg);
1da177e4 LT	88	}
1da177e4 LT	89
d3c5ee6d JE	90	module_init(ah_mt_init);
d3c5ee6d JE	91	module_exit(ah_mt_exit);