[linux-2.6-block.git] / net / bridge / netfilter / ebt_among.c

/*
 *  ebt_among
 *
 *	Authors:
 *	Grzegorz Borowiak <grzes@gnu.univ.gda.pl>
 *
 *  August, 2003
 *
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/ip.h>
#include <linux/if_arp.h>
#include <linux/module.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_among.h>

static bool ebt_mac_wormhash_contains(const struct ebt_mac_wormhash *wh,
				      const char *mac, __be32 ip)
{
	/* You may be puzzled as to how this code works.
	 * Some tricks were used, refer to
	 * 	include/linux/netfilter_bridge/ebt_among.h
	 * as there you can find a solution of this mystery.
	 */
	const struct ebt_mac_wormhash_tuple *p;
	int start, limit, i;
	uint32_t cmp[2] = { 0, 0 };
	int key = ((const unsigned char *)mac)[5];

	ether_addr_copy(((char *) cmp) + 2, mac);
	start = wh->table[key];
	limit = wh->table[key + 1];
	if (ip) {
		for (i = start; i < limit; i++) {
			p = &wh->pool[i];
			if (cmp[1] == p->cmp[1] && cmp[0] == p->cmp[0])
				if (p->ip == 0 || p->ip == ip)
					return true;
		}
	} else {
		for (i = start; i < limit; i++) {
			p = &wh->pool[i];
			if (cmp[1] == p->cmp[1] && cmp[0] == p->cmp[0])
				if (p->ip == 0)
					return true;
		}
	}
	return false;
}

static int ebt_mac_wormhash_check_integrity(const struct ebt_mac_wormhash
					    *wh)
{
	int i;

	for (i = 0; i < 256; i++) {
		if (wh->table[i] > wh->table[i + 1])
			return -0x100 - i;
		if (wh->table[i] < 0)
			return -0x200 - i;
		if (wh->table[i] > wh->poolsize)
			return -0x300 - i;
	}
	if (wh->table[256] > wh->poolsize)
		return -0xc00;
	return 0;
}

static int get_ip_dst(const struct sk_buff *skb, __be32 *addr)
{
	if (eth_hdr(skb)->h_proto == htons(ETH_P_IP)) {
		const struct iphdr *ih;
		struct iphdr _iph;

		ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
		if (ih == NULL)
			return -1;
		*addr = ih->daddr;
	} else if (eth_hdr(skb)->h_proto == htons(ETH_P_ARP)) {
		const struct arphdr *ah;
		struct arphdr _arph;
		const __be32 *bp;
		__be32 buf;

		ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph);
		if (ah == NULL ||
		    ah->ar_pln != sizeof(__be32) ||
		    ah->ar_hln != ETH_ALEN)
			return -1;
		bp = skb_header_pointer(skb, sizeof(struct arphdr) +
					2 * ETH_ALEN + sizeof(__be32),
					sizeof(__be32), &buf);
		if (bp == NULL)
			return -1;
		*addr = *bp;
	}
	return 0;
}

static int get_ip_src(const struct sk_buff *skb, __be32 *addr)
{
	if (eth_hdr(skb)->h_proto == htons(ETH_P_IP)) {
		const struct iphdr *ih;
		struct iphdr _iph;

		ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
		if (ih == NULL)
			return -1;
		*addr = ih->saddr;
	} else if (eth_hdr(skb)->h_proto == htons(ETH_P_ARP)) {
		const struct arphdr *ah;
		struct arphdr _arph;
		const __be32 *bp;
		__be32 buf;

		ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph);
		if (ah == NULL ||
		    ah->ar_pln != sizeof(__be32) ||
		    ah->ar_hln != ETH_ALEN)
			return -1;
		bp = skb_header_pointer(skb, sizeof(struct arphdr) +
					ETH_ALEN, sizeof(__be32), &buf);
		if (bp == NULL)
			return -1;
		*addr = *bp;
	}
	return 0;
}

static bool
ebt_among_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
	const struct ebt_among_info *info = par->matchinfo;
	const char *dmac, *smac;
	const struct ebt_mac_wormhash *wh_dst, *wh_src;
	__be32 dip = 0, sip = 0;

	wh_dst = ebt_among_wh_dst(info);
	wh_src = ebt_among_wh_src(info);

	if (wh_src) {
		smac = eth_hdr(skb)->h_source;
		if (get_ip_src(skb, &sip))
			return false;
		if (!(info->bitmask & EBT_AMONG_SRC_NEG)) {
			/* we match only if it contains */
			if (!ebt_mac_wormhash_contains(wh_src, smac, sip))
				return false;
		} else {
			/* we match only if it DOES NOT contain */
			if (ebt_mac_wormhash_contains(wh_src, smac, sip))
				return false;
		}
	}

	if (wh_dst) {
		dmac = eth_hdr(skb)->h_dest;
		if (get_ip_dst(skb, &dip))
			return false;
		if (!(info->bitmask & EBT_AMONG_DST_NEG)) {
			/* we match only if it contains */
			if (!ebt_mac_wormhash_contains(wh_dst, dmac, dip))
				return false;
		} else {
			/* we match only if it DOES NOT contain */
			if (ebt_mac_wormhash_contains(wh_dst, dmac, dip))
				return false;
		}
	}

	return true;
}

static int ebt_among_mt_check(const struct xt_mtchk_param *par)
{
	const struct ebt_among_info *info = par->matchinfo;
	const struct ebt_entry_match *em =
		container_of(par->matchinfo, const struct ebt_entry_match, data);
	int expected_length = sizeof(struct ebt_among_info);
	const struct ebt_mac_wormhash *wh_dst, *wh_src;
	int err;

	wh_dst = ebt_among_wh_dst(info);
	wh_src = ebt_among_wh_src(info);
	expected_length += ebt_mac_wormhash_size(wh_dst);
	expected_length += ebt_mac_wormhash_size(wh_src);

	if (em->match_size != EBT_ALIGN(expected_length)) {
		pr_info("wrong size: %d against expected %d, rounded to %Zd\n",
			em->match_size, expected_length,
			EBT_ALIGN(expected_length));
		return -EINVAL;
	}
	if (wh_dst && (err = ebt_mac_wormhash_check_integrity(wh_dst))) {
		pr_info("dst integrity fail: %x\n", -err);
		return -EINVAL;
	}
	if (wh_src && (err = ebt_mac_wormhash_check_integrity(wh_src))) {
		pr_info("src integrity fail: %x\n", -err);
		return -EINVAL;
	}
	return 0;
}

static struct xt_match ebt_among_mt_reg __read_mostly = {
	.name		= "among",
	.revision	= 0,
	.family		= NFPROTO_BRIDGE,
	.match		= ebt_among_mt,
	.checkentry	= ebt_among_mt_check,
	.matchsize	= -1, /* special case */
	.me		= THIS_MODULE,
};

static int __init ebt_among_init(void)
{
	return xt_register_match(&ebt_among_mt_reg);
}

static void __exit ebt_among_fini(void)
{
	xt_unregister_match(&ebt_among_mt_reg);
}

module_init(ebt_among_init);
module_exit(ebt_among_fini);
MODULE_DESCRIPTION("Ebtables: Combined MAC/IP address list matching");
MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* ebt_among
	3	*
	4	* Authors:
	5	* Grzegorz Borowiak <grzes@gnu.univ.gda.pl>
	6	*
	7	* August, 2003
	8	*
	9	*/
ff67e4e4	10	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
1da177e4 LT	11	#include <linux/ip.h>
	12	#include <linux/if_arp.h>
	13	#include <linux/module.h>
043ef46c JE	14	#include <linux/netfilter/x_tables.h>
	15	#include <linux/netfilter_bridge/ebtables.h>
	16	#include <linux/netfilter_bridge/ebt_among.h>
1da177e4	17
8cc784ee JE	18	static bool ebt_mac_wormhash_contains(const struct ebt_mac_wormhash *wh,
8cc784ee JE	19	const char *mac, __be32 ip)
1da177e4 LT	20	{
1da177e4 LT	21	/* You may be puzzled as to how this code works.
9d6f229f	22	* Some tricks were used, refer to
1da177e4 LT	23	* include/linux/netfilter_bridge/ebt_among.h
	24	* as there you can find a solution of this mystery.
	25	*/
	26	const struct ebt_mac_wormhash_tuple *p;
	27	int start, limit, i;
	28	uint32_t cmp[2] = { 0, 0 };
abfdf1c4	29	int key = ((const unsigned char *)mac)[5];
1da177e4	30
04091142	31	ether_addr_copy(((char *) cmp) + 2, mac);
1da177e4 LT	32	start = wh->table[key];
	33	limit = wh->table[key + 1];
	34	if (ip) {
	35	for (i = start; i < limit; i++) {
	36	p = &wh->pool[i];
8cc784ee JE	37	if (cmp[1] == p->cmp[1] && cmp[0] == p->cmp[0])
	38	if (p->ip == 0 \|\| p->ip == ip)
	39	return true;
1da177e4 LT	40	}
	41	} else {
	42	for (i = start; i < limit; i++) {
	43	p = &wh->pool[i];
8cc784ee JE	44	if (cmp[1] == p->cmp[1] && cmp[0] == p->cmp[0])
	45	if (p->ip == 0)
	46	return true;
1da177e4 LT	47	}
1da177e4 LT	48	}
8cc784ee	49	return false;
1da177e4 LT	50	}
	51
	52	static int ebt_mac_wormhash_check_integrity(const struct ebt_mac_wormhash
	53	*wh)
	54	{
	55	int i;
	56
	57	for (i = 0; i < 256; i++) {
	58	if (wh->table[i] > wh->table[i + 1])
	59	return -0x100 - i;
	60	if (wh->table[i] < 0)
	61	return -0x200 - i;
	62	if (wh->table[i] > wh->poolsize)
	63	return -0x300 - i;
	64	}
	65	if (wh->table[256] > wh->poolsize)
	66	return -0xc00;
	67	return 0;
	68	}
	69
47c183fa	70	static int get_ip_dst(const struct sk_buff skb, __be32 addr)
1da177e4 LT	71	{
1da177e4 LT	72	if (eth_hdr(skb)->h_proto == htons(ETH_P_IP)) {
abfdf1c4 JE	73	const struct iphdr *ih;
abfdf1c4 JE	74	struct iphdr _iph;
1da177e4 LT	75
	76	ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
	77	if (ih == NULL)
	78	return -1;
	79	*addr = ih->daddr;
	80	} else if (eth_hdr(skb)->h_proto == htons(ETH_P_ARP)) {
abfdf1c4 JE	81	const struct arphdr *ah;
	82	struct arphdr _arph;
	83	const __be32 *bp;
	84	__be32 buf;
1da177e4 LT	85
	86	ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph);
	87	if (ah == NULL \|\|
47c183fa	88	ah->ar_pln != sizeof(__be32) \|\|
1da177e4 LT	89	ah->ar_hln != ETH_ALEN)
	90	return -1;
	91	bp = skb_header_pointer(skb, sizeof(struct arphdr) +
47c183fa AV	92	2 * ETH_ALEN + sizeof(__be32),
47c183fa AV	93	sizeof(__be32), &buf);
1da177e4 LT	94	if (bp == NULL)
	95	return -1;
	96	addr = bp;
	97	}
	98	return 0;
	99	}
	100
47c183fa	101	static int get_ip_src(const struct sk_buff skb, __be32 addr)
1da177e4 LT	102	{
1da177e4 LT	103	if (eth_hdr(skb)->h_proto == htons(ETH_P_IP)) {
abfdf1c4 JE	104	const struct iphdr *ih;
abfdf1c4 JE	105	struct iphdr _iph;
1da177e4 LT	106
	107	ih = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
	108	if (ih == NULL)
	109	return -1;
	110	*addr = ih->saddr;
	111	} else if (eth_hdr(skb)->h_proto == htons(ETH_P_ARP)) {
abfdf1c4 JE	112	const struct arphdr *ah;
	113	struct arphdr _arph;
	114	const __be32 *bp;
	115	__be32 buf;
1da177e4 LT	116
	117	ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph);
	118	if (ah == NULL \|\|
47c183fa	119	ah->ar_pln != sizeof(__be32) \|\|
1da177e4 LT	120	ah->ar_hln != ETH_ALEN)
	121	return -1;
	122	bp = skb_header_pointer(skb, sizeof(struct arphdr) +
47c183fa	123	ETH_ALEN, sizeof(__be32), &buf);
1da177e4 LT	124	if (bp == NULL)
	125	return -1;
	126	addr = bp;
	127	}
	128	return 0;
	129	}
	130
2d06d4a5	131	static bool
62fc8051	132	ebt_among_mt(const struct sk_buff skb, struct xt_action_param par)
1da177e4	133	{
f7108a20	134	const struct ebt_among_info *info = par->matchinfo;
1da177e4 LT	135	const char dmac, smac;
1da177e4 LT	136	const struct ebt_mac_wormhash wh_dst, wh_src;
47c183fa	137	__be32 dip = 0, sip = 0;
1da177e4 LT	138
	139	wh_dst = ebt_among_wh_dst(info);
	140	wh_src = ebt_among_wh_src(info);
	141
	142	if (wh_src) {
	143	smac = eth_hdr(skb)->h_source;
	144	if (get_ip_src(skb, &sip))
8cc784ee	145	return false;
1da177e4 LT	146	if (!(info->bitmask & EBT_AMONG_SRC_NEG)) {
	147	/* we match only if it contains */
	148	if (!ebt_mac_wormhash_contains(wh_src, smac, sip))
8cc784ee	149	return false;
1da177e4 LT	150	} else {
	151	/* we match only if it DOES NOT contain */
	152	if (ebt_mac_wormhash_contains(wh_src, smac, sip))
8cc784ee	153	return false;
1da177e4 LT	154	}
	155	}
	156
	157	if (wh_dst) {
	158	dmac = eth_hdr(skb)->h_dest;
	159	if (get_ip_dst(skb, &dip))
8cc784ee	160	return false;
1da177e4 LT	161	if (!(info->bitmask & EBT_AMONG_DST_NEG)) {
	162	/* we match only if it contains */
	163	if (!ebt_mac_wormhash_contains(wh_dst, dmac, dip))
8cc784ee	164	return false;
1da177e4 LT	165	} else {
	166	/* we match only if it DOES NOT contain */
	167	if (ebt_mac_wormhash_contains(wh_dst, dmac, dip))
8cc784ee	168	return false;
1da177e4 LT	169	}
	170	}
	171
8cc784ee	172	return true;
1da177e4 LT	173	}
1da177e4 LT	174
b0f38452	175	static int ebt_among_mt_check(const struct xt_mtchk_param *par)
1da177e4	176	{
9b4fce7a	177	const struct ebt_among_info *info = par->matchinfo;
815377fe	178	const struct ebt_entry_match *em =
9b4fce7a	179	container_of(par->matchinfo, const struct ebt_entry_match, data);
1da177e4 LT	180	int expected_length = sizeof(struct ebt_among_info);
	181	const struct ebt_mac_wormhash wh_dst, wh_src;
	182	int err;
	183
	184	wh_dst = ebt_among_wh_dst(info);
	185	wh_src = ebt_among_wh_src(info);
	186	expected_length += ebt_mac_wormhash_size(wh_dst);
	187	expected_length += ebt_mac_wormhash_size(wh_src);
	188
815377fe	189	if (em->match_size != EBT_ALIGN(expected_length)) {
ff67e4e4 JE	190	pr_info("wrong size: %d against expected %d, rounded to %Zd\n",
	191	em->match_size, expected_length,
	192	EBT_ALIGN(expected_length));
bd414ee6	193	return -EINVAL;
1da177e4 LT	194	}
1da177e4 LT	195	if (wh_dst && (err = ebt_mac_wormhash_check_integrity(wh_dst))) {
ff67e4e4	196	pr_info("dst integrity fail: %x\n", -err);
bd414ee6	197	return -EINVAL;
1da177e4 LT	198	}
1da177e4 LT	199	if (wh_src && (err = ebt_mac_wormhash_check_integrity(wh_src))) {
ff67e4e4	200	pr_info("src integrity fail: %x\n", -err);
bd414ee6	201	return -EINVAL;
1da177e4	202	}
bd414ee6	203	return 0;
1da177e4 LT	204	}
1da177e4 LT	205
043ef46c JE	206	static struct xt_match ebt_among_mt_reg __read_mostly = {
043ef46c JE	207	.name = "among",
001a18d3 JE	208	.revision = 0,
001a18d3 JE	209	.family = NFPROTO_BRIDGE,
2d06d4a5 JE	210	.match = ebt_among_mt,
2d06d4a5 JE	211	.checkentry = ebt_among_mt_check,
18219d3f	212	.matchsize = -1, /* special case */
1da177e4 LT	213	.me = THIS_MODULE,
	214	};
	215
65b4b4e8	216	static int __init ebt_among_init(void)
1da177e4	217	{
043ef46c	218	return xt_register_match(&ebt_among_mt_reg);
1da177e4 LT	219	}
1da177e4 LT	220
65b4b4e8	221	static void __exit ebt_among_fini(void)
1da177e4	222	{
043ef46c	223	xt_unregister_match(&ebt_among_mt_reg);
1da177e4 LT	224	}
1da177e4 LT	225
65b4b4e8 AM	226	module_init(ebt_among_init);
65b4b4e8 AM	227	module_exit(ebt_among_fini);
f776c4cd	228	MODULE_DESCRIPTION("Ebtables: Combined MAC/IP address list matching");
1da177e4	229	MODULE_LICENSE("GPL");