[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 void *matchinfo,
      int offset,
      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, skb->nh.iph->ihl * 4,
				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 struct ipt_ip *ip,
	   void *matchinfo,
	   unsigned int matchinfosize,
	   unsigned int hook_mask)
{
	const struct ipt_esp *espinfo = matchinfo;

	/* Must specify proto == ESP, and no unknown invflags */
	if (ip->proto != IPPROTO_ESP || (ip->invflags & IPT_INV_PROTO)) {
		duprintf("ipt_esp: Protocol %u != %u\n", ip->proto,
			 IPPROTO_ESP);
		return 0;
	}
	if (matchinfosize != IPT_ALIGN(sizeof(struct ipt_esp))) {
		duprintf("ipt_esp: matchsize %u != %u\n",
			 matchinfosize, IPT_ALIGN(sizeof(struct ipt_esp)));
		return 0;
	}
	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,
	.checkentry	= &checkentry,
	.me		= THIS_MODULE,
};

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

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

module_init(init);
module_exit(cleanup);
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,
	43	const void *matchinfo,
	44	int offset,
	45	int *hotdrop)
	46	{
	47	struct ip_esp_hdr _esp, *eh;
	48	const struct ipt_esp *espinfo = matchinfo;
	49
	50	/* Must not be a fragment. */
	51	if (offset)
	52	return 0;
	53
	54	eh = skb_header_pointer(skb, skb->nh.iph->ihl * 4,
	55	sizeof(_esp), &_esp);
	56	if (eh == NULL) {
	57	/* We've been asked to examine this packet, and we
	58	* can't. Hence, no choice but to drop.
	59	*/
	60	duprintf("Dropping evil ESP tinygram.\n");
	61	*hotdrop = 1;
	62	return 0;
	63	}
	64
65	return spi_match(espinfo->spis[0], espinfo->spis[1],
66	ntohl(eh->spi),
67	!!(espinfo->invflags & IPT_ESP_INV_SPI));
68	}
69
70	/* Called when user tries to insert an entry of this type. */
71	static int
72	checkentry(const char *tablename,
73	const struct ipt_ip *ip,
74	void *matchinfo,
75	unsigned int matchinfosize,
76	unsigned int hook_mask)
77	{
78	const struct ipt_esp *espinfo = matchinfo;
79
80	/* Must specify proto == ESP, and no unknown invflags */
81	if (ip->proto != IPPROTO_ESP \|\| (ip->invflags & IPT_INV_PROTO)) {
82	duprintf("ipt_esp: Protocol %u != %u\n", ip->proto,
83	IPPROTO_ESP);
84	return 0;
85	}
86	if (matchinfosize != IPT_ALIGN(sizeof(struct ipt_esp))) {
87	duprintf("ipt_esp: matchsize %u != %u\n",
88	matchinfosize, IPT_ALIGN(sizeof(struct ipt_esp)));
89	return 0;
90	}
91	if (espinfo->invflags & ~IPT_ESP_INV_MASK) {
92	duprintf("ipt_esp: unknown flags %X\n",
93	espinfo->invflags);
94	return 0;
95	}
96
97	return 1;
98	}
99
100	static struct ipt_match esp_match = {
101	.name = "esp",
102	.match = &match,
103	.checkentry = &checkentry,
104	.me = THIS_MODULE,
105	};
106
107	static int __init init(void)
108	{
109	return ipt_register_match(&esp_match);
110	}
111
112	static void __exit cleanup(void)
113	{
114	ipt_unregister_match(&esp_match);
115	}
116
117	module_init(init);
118	module_exit(cleanup);