net/bridge/netfilter/ebt_among.c - linux-mtk - Git at Google

 /*
  *  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 bool poolsize_invalid(const struct ebt_mac_wormhash *w)
 {
 	return w && w->poolsize >= (INT_MAX / sizeof(struct ebt_mac_wormhash_tuple));
 }

 static bool wormhash_offset_invalid(int off, unsigned int len)
 {
 	if (off == 0) /* not present */
 		return false;

 	if (off < (int)sizeof(struct ebt_among_info) ||
 	    off % __alignof__(struct ebt_mac_wormhash))
 		return true;

 	off += sizeof(struct ebt_mac_wormhash);

 	return off > len;
 }

 static bool wormhash_sizes_valid(const struct ebt_mac_wormhash *wh, int a, int b)
 {
 	if (a == 0)
 		a = sizeof(struct ebt_among_info);

 	return ebt_mac_wormhash_size(wh) + a == b;
 }

 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);
 	unsigned int expected_length = sizeof(struct ebt_among_info);
 	const struct ebt_mac_wormhash *wh_dst, *wh_src;
 	int err;

 	if (expected_length > em->match_size)
 		return -EINVAL;

 	if (wormhash_offset_invalid(info->wh_dst_ofs, em->match_size) ||
 	    wormhash_offset_invalid(info->wh_src_ofs, em->match_size))
 		return -EINVAL;

 	wh_dst = ebt_among_wh_dst(info);
 	if (poolsize_invalid(wh_dst))
 		return -EINVAL;

 	expected_length += ebt_mac_wormhash_size(wh_dst);
 	if (expected_length > em->match_size)
 		return -EINVAL;

 	wh_src = ebt_among_wh_src(info);
 	if (poolsize_invalid(wh_src))
 		return -EINVAL;

 	if (info->wh_src_ofs < info->wh_dst_ofs) {
 		if (!wormhash_sizes_valid(wh_src, info->wh_src_ofs, info->wh_dst_ofs))
 			return -EINVAL;
 	} else {
 		if (!wormhash_sizes_valid(wh_dst, info->wh_dst_ofs, info->wh_src_ofs))
 			return -EINVAL;
 	}

 	expected_length += ebt_mac_wormhash_size(wh_src);

 	if (em->match_size != EBT_ALIGN(expected_length)) {
 		pr_err_ratelimited("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_err_ratelimited("dst integrity fail: %x\n", -err);
 		return -EINVAL;
 	}
 	if (wh_src && (err = ebt_mac_wormhash_check_integrity(wh_src))) {
 		pr_err_ratelimited("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");
	/*
	* 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 bool poolsize_invalid(const struct ebt_mac_wormhash *w)
	{
	return w && w->poolsize >= (INT_MAX / sizeof(struct ebt_mac_wormhash_tuple));
	}

	static bool wormhash_offset_invalid(int off, unsigned int len)
	{
	if (off == 0) /* not present */
	return false;

	if (off < (int)sizeof(struct ebt_among_info) \|\|
	off % __alignof__(struct ebt_mac_wormhash))
	return true;

	off += sizeof(struct ebt_mac_wormhash);

	return off > len;
	}

	static bool wormhash_sizes_valid(const struct ebt_mac_wormhash *wh, int a, int b)
	{
	if (a == 0)
	a = sizeof(struct ebt_among_info);

	return ebt_mac_wormhash_size(wh) + a == b;
	}

	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);
	unsigned int expected_length = sizeof(struct ebt_among_info);
	const struct ebt_mac_wormhash wh_dst, wh_src;
	int err;

	if (expected_length > em->match_size)
	return -EINVAL;

	if (wormhash_offset_invalid(info->wh_dst_ofs, em->match_size) \|\|
	wormhash_offset_invalid(info->wh_src_ofs, em->match_size))
	return -EINVAL;

	wh_dst = ebt_among_wh_dst(info);
	if (poolsize_invalid(wh_dst))
	return -EINVAL;

	expected_length += ebt_mac_wormhash_size(wh_dst);
	if (expected_length > em->match_size)
	return -EINVAL;

	wh_src = ebt_among_wh_src(info);
	if (poolsize_invalid(wh_src))
	return -EINVAL;

	if (info->wh_src_ofs < info->wh_dst_ofs) {
	if (!wormhash_sizes_valid(wh_src, info->wh_src_ofs, info->wh_dst_ofs))
	return -EINVAL;
	} else {
	if (!wormhash_sizes_valid(wh_dst, info->wh_dst_ofs, info->wh_src_ofs))
	return -EINVAL;
	}

	expected_length += ebt_mac_wormhash_size(wh_src);

	if (em->match_size != EBT_ALIGN(expected_length)) {
	pr_err_ratelimited("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_err_ratelimited("dst integrity fail: %x\n", -err);
	return -EINVAL;
	}
	if (wh_src && (err = ebt_mac_wormhash_check_integrity(wh_src))) {
	pr_err_ratelimited("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");