[deliverable/linux.git] / net / ipv4 / netfilter / ipt_esp.c

/* Kernel module to match ESP 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_esp.h>
#include <linux/netfilter_ipv4/ip_tables.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>");
MODULE_DESCRIPTION("iptables ESP 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("esp 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 struct xt_match *match,
      const void *matchinfo,
      int offset,
      unsigned int protoff,
      int *hotdrop)
{
	struct ip_esp_hdr _esp, *eh;
	const struct ipt_esp *espinfo = matchinfo;

	/* Must not be a fragment. */
	if (offset)
		return 0;

	eh = skb_header_pointer(skb, protoff,
				sizeof(_esp), &_esp);
	if (eh == NULL) {
		/* We've been asked to examine this packet, and we
		 * can't.  Hence, no choice but to drop.
		 */
		duprintf("Dropping evil ESP tinygram.\n");
		*hotdrop = 1;
		return 0;
	}

	return spi_match(espinfo->spis[0], espinfo->spis[1],
			 ntohl(eh->spi),
			 !!(espinfo->invflags & IPT_ESP_INV_SPI));
}

/* Called when user tries to insert an entry of this type. */
static int
checkentry(const char *tablename,
	   const void *ip_void,
	   const struct xt_match *match,
	   void *matchinfo,
	   unsigned int matchinfosize,
	   unsigned int hook_mask)
{
	const struct ipt_esp *espinfo = matchinfo;

	/* Must specify no unknown invflags */
	if (espinfo->invflags & ~IPT_ESP_INV_MASK) {
		duprintf("ipt_esp: unknown flags %X\n", espinfo->invflags);
		return 0;
	}
	return 1;
}

static struct ipt_match esp_match = {
	.name		= "esp",
	.match		= match,
	.matchsize	= sizeof(struct ipt_esp),
	.proto		= IPPROTO_ESP,
	.checkentry	= checkentry,
	.me		= THIS_MODULE,
};

static int __init ipt_esp_init(void)
{
	return ipt_register_match(&esp_match);
}

static void __exit ipt_esp_fini(void)
{
	ipt_unregister_match(&esp_match);
}

module_init(ipt_esp_init);
module_exit(ipt_esp_fini);
Commit	Line	Data
1da177e4 LT	1	/* Kernel module to match ESP parameters. */
	2
	3	/* (C) 1999-2000 Yon Uriarte <yon@astaro.de>
	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License version 2 as
	7	* published by the Free Software Foundation.
	8	*/
	9
	10	#include <linux/module.h>
	11	#include <linux/skbuff.h>
	12	#include <linux/ip.h>
	13
	14	#include <linux/netfilter_ipv4/ipt_esp.h>
	15	#include <linux/netfilter_ipv4/ip_tables.h>
	16
	17	MODULE_LICENSE("GPL");
	18	MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>");
	19	MODULE_DESCRIPTION("iptables ESP SPI match module");
	20
	21	#ifdef DEBUG_CONNTRACK
	22	#define duprintf(format, args...) printk(format , ## args)
	23	#else
	24	#define duprintf(format, args...)
	25	#endif
	26
	27	/* Returns 1 if the spi is matched by the range, 0 otherwise */
	28	static inline int
	29	spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert)
	30	{
	31	int r=0;
	32	duprintf("esp spi_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ',
	33	min,spi,max);
	34	r=(spi >= min && spi <= max) ^ invert;
	35	duprintf(" result %s\n",r? "PASS" : "FAILED");
	36	return r;
	37	}
	38
	39	static int
	40	match(const struct sk_buff *skb,
	41	const struct net_device *in,
	42	const struct net_device *out,
c4986734	43	const struct xt_match *match,
1da177e4 LT	44	const void *matchinfo,
1da177e4 LT	45	int offset,
2e4e6a17	46	unsigned int protoff,
1da177e4 LT	47	int *hotdrop)
	48	{
	49	struct ip_esp_hdr _esp, *eh;
	50	const struct ipt_esp *espinfo = matchinfo;
	51
	52	/* Must not be a fragment. */
	53	if (offset)
	54	return 0;
	55
2e4e6a17	56	eh = skb_header_pointer(skb, protoff,
1da177e4 LT	57	sizeof(_esp), &_esp);
	58	if (eh == NULL) {
	59	/* We've been asked to examine this packet, and we
	60	* can't. Hence, no choice but to drop.
	61	*/
	62	duprintf("Dropping evil ESP tinygram.\n");
	63	*hotdrop = 1;
	64	return 0;
	65	}
	66
	67	return spi_match(espinfo->spis[0], espinfo->spis[1],
	68	ntohl(eh->spi),
	69	!!(espinfo->invflags & IPT_ESP_INV_SPI));
	70	}
	71
	72	/* Called when user tries to insert an entry of this type. */
	73	static int
	74	checkentry(const char *tablename,
2e4e6a17	75	const void *ip_void,
c4986734	76	const struct xt_match *match,
1da177e4 LT	77	void *matchinfo,
	78	unsigned int matchinfosize,
	79	unsigned int hook_mask)
	80	{
	81	const struct ipt_esp *espinfo = matchinfo;
	82
1d5cd909	83	/* Must specify no unknown invflags */
1da177e4	84	if (espinfo->invflags & ~IPT_ESP_INV_MASK) {
1d5cd909	85	duprintf("ipt_esp: unknown flags %X\n", espinfo->invflags);
1da177e4 LT	86	return 0;
1da177e4 LT	87	}
1da177e4 LT	88	return 1;
	89	}
	90
	91	static struct ipt_match esp_match = {
	92	.name = "esp",
1d5cd909 PM	93	.match = match,
	94	.matchsize = sizeof(struct ipt_esp),
	95	.proto = IPPROTO_ESP,
	96	.checkentry = checkentry,
1da177e4 LT	97	.me = THIS_MODULE,
	98	};
	99
65b4b4e8	100	static int __init ipt_esp_init(void)
1da177e4 LT	101	{
	102	return ipt_register_match(&esp_match);
	103	}
	104
65b4b4e8	105	static void __exit ipt_esp_fini(void)
1da177e4 LT	106	{
	107	ipt_unregister_match(&esp_match);
	108	}
	109
65b4b4e8 AM	110	module_init(ipt_esp_init);
65b4b4e8 AM	111	module_exit(ipt_esp_fini);