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

/*
 *  ebt_arpreply
 *
 *	Authors:
 *	Grzegorz Borowiak <grzes@gnu.univ.gda.pl>
 *	Bart De Schuymer <bdschuym@pandora.be>
 *
 *  August, 2003
 *
 */
#include <linux/if_arp.h>
#include <net/arp.h>
#include <linux/module.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_arpreply.h>

static unsigned int
ebt_arpreply_tg(struct sk_buff *skb, const struct xt_target_param *par)
{
	const struct ebt_arpreply_info *info = par->targinfo;
	const __be32 *siptr, *diptr;
	__be32 _sip, _dip;
	const struct arphdr *ap;
	struct arphdr _ah;
	const unsigned char *shp;
	unsigned char _sha[ETH_ALEN];

	ap = skb_header_pointer(skb, 0, sizeof(_ah), &_ah);
	if (ap == NULL)
		return EBT_DROP;

	if (ap->ar_op != htons(ARPOP_REQUEST) ||
	    ap->ar_hln != ETH_ALEN ||
	    ap->ar_pro != htons(ETH_P_IP) ||
	    ap->ar_pln != 4)
		return EBT_CONTINUE;

	shp = skb_header_pointer(skb, sizeof(_ah), ETH_ALEN, &_sha);
	if (shp == NULL)
		return EBT_DROP;

	siptr = skb_header_pointer(skb, sizeof(_ah) + ETH_ALEN,
				   sizeof(_sip), &_sip);
	if (siptr == NULL)
		return EBT_DROP;

	diptr = skb_header_pointer(skb,
				   sizeof(_ah) + 2 * ETH_ALEN + sizeof(_sip),
				   sizeof(_dip), &_dip);
	if (diptr == NULL)
		return EBT_DROP;

	arp_send(ARPOP_REPLY, ETH_P_ARP, *siptr, (struct net_device *)par->in,
		 *diptr, shp, info->mac, shp);

	return info->target;
}

static bool
ebt_arpreply_tg_check(const char *tablename, const void *entry,
		      const struct xt_target *target, void *data,
		      unsigned int hookmask)
{
	const struct ebt_arpreply_info *info = data;
	const struct ebt_entry *e = entry;

	if (BASE_CHAIN && info->target == EBT_RETURN)
		return false;
	if (e->ethproto != htons(ETH_P_ARP) ||
	    e->invflags & EBT_IPROTO)
		return false;
	CLEAR_BASE_CHAIN_BIT;
	return true;
}

static struct xt_target ebt_arpreply_tg_reg __read_mostly = {
	.name		= "arpreply",
	.revision	= 0,
	.family		= NFPROTO_BRIDGE,
	.table		= "nat",
	.hooks		= (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_PRE_ROUTING),
	.target		= ebt_arpreply_tg,
	.checkentry	= ebt_arpreply_tg_check,
	.targetsize	= XT_ALIGN(sizeof(struct ebt_arpreply_info)),
	.me		= THIS_MODULE,
};

static int __init ebt_arpreply_init(void)
{
	return xt_register_target(&ebt_arpreply_tg_reg);
}

static void __exit ebt_arpreply_fini(void)
{
	xt_unregister_target(&ebt_arpreply_tg_reg);
}

module_init(ebt_arpreply_init);
module_exit(ebt_arpreply_fini);
MODULE_DESCRIPTION("Ebtables: ARP reply target");
MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* ebt_arpreply
	3	*
	4	* Authors:
	5	* Grzegorz Borowiak <grzes@gnu.univ.gda.pl>
	6	* Bart De Schuymer <bdschuym@pandora.be>
	7	*
	8	* August, 2003
	9	*
	10	*/
1da177e4 LT	11	#include <linux/if_arp.h>
	12	#include <net/arp.h>
	13	#include <linux/module.h>
18219d3f JE	14	#include <linux/netfilter/x_tables.h>
	15	#include <linux/netfilter_bridge/ebtables.h>
	16	#include <linux/netfilter_bridge/ebt_arpreply.h>
1da177e4	17
2d06d4a5	18	static unsigned int
7eb35586	19	ebt_arpreply_tg(struct sk_buff skb, const struct xt_target_param par)
1da177e4	20	{
7eb35586	21	const struct ebt_arpreply_info *info = par->targinfo;
abfdf1c4 JE	22	const __be32 siptr, diptr;
	23	__be32 _sip, _dip;
	24	const struct arphdr *ap;
	25	struct arphdr _ah;
	26	const unsigned char *shp;
	27	unsigned char _sha[ETH_ALEN];
1da177e4 LT	28
	29	ap = skb_header_pointer(skb, 0, sizeof(_ah), &_ah);
	30	if (ap == NULL)
	31	return EBT_DROP;
	32
	33	if (ap->ar_op != htons(ARPOP_REQUEST) \|\|
	34	ap->ar_hln != ETH_ALEN \|\|
	35	ap->ar_pro != htons(ETH_P_IP) \|\|
	36	ap->ar_pln != 4)
	37	return EBT_CONTINUE;
	38
	39	shp = skb_header_pointer(skb, sizeof(_ah), ETH_ALEN, &_sha);
	40	if (shp == NULL)
	41	return EBT_DROP;
	42
	43	siptr = skb_header_pointer(skb, sizeof(_ah) + ETH_ALEN,
	44	sizeof(_sip), &_sip);
	45	if (siptr == NULL)
	46	return EBT_DROP;
	47
	48	diptr = skb_header_pointer(skb,
	49	sizeof(_ah) + 2 * ETH_ALEN + sizeof(_sip),
	50	sizeof(_dip), &_dip);
	51	if (diptr == NULL)
	52	return EBT_DROP;
	53
7eb35586	54	arp_send(ARPOP_REPLY, ETH_P_ARP, siptr, (struct net_device )par->in,
9d6f229f	55	*diptr, shp, info->mac, shp);
1da177e4 LT	56
	57	return info->target;
	58	}
	59
2d06d4a5 JE	60	static bool
	61	ebt_arpreply_tg_check(const char tablename, const void entry,
	62	const struct xt_target target, void data,
	63	unsigned int hookmask)
1da177e4	64	{
abfdf1c4	65	const struct ebt_arpreply_info *info = data;
2d06d4a5	66	const struct ebt_entry *e = entry;
1da177e4	67
1da177e4	68	if (BASE_CHAIN && info->target == EBT_RETURN)
19eda879	69	return false;
1da177e4 LT	70	if (e->ethproto != htons(ETH_P_ARP) \|\|
1da177e4 LT	71	e->invflags & EBT_IPROTO)
19eda879	72	return false;
1da177e4	73	CLEAR_BASE_CHAIN_BIT;
19eda879	74	return true;
1da177e4 LT	75	}
1da177e4 LT	76
043ef46c JE	77	static struct xt_target ebt_arpreply_tg_reg __read_mostly = {
043ef46c JE	78	.name = "arpreply",
001a18d3 JE	79	.revision = 0,
001a18d3 JE	80	.family = NFPROTO_BRIDGE,
f2ff525c JE	81	.table = "nat",
f2ff525c JE	82	.hooks = (1 << NF_BR_NUMHOOKS) \| (1 << NF_BR_PRE_ROUTING),
2d06d4a5 JE	83	.target = ebt_arpreply_tg,
2d06d4a5 JE	84	.checkentry = ebt_arpreply_tg_check,
18219d3f	85	.targetsize = XT_ALIGN(sizeof(struct ebt_arpreply_info)),
1da177e4 LT	86	.me = THIS_MODULE,
	87	};
	88
65b4b4e8	89	static int __init ebt_arpreply_init(void)
1da177e4	90	{
043ef46c	91	return xt_register_target(&ebt_arpreply_tg_reg);
1da177e4 LT	92	}
1da177e4 LT	93
65b4b4e8	94	static void __exit ebt_arpreply_fini(void)
1da177e4	95	{
043ef46c	96	xt_unregister_target(&ebt_arpreply_tg_reg);
1da177e4 LT	97	}
1da177e4 LT	98
65b4b4e8 AM	99	module_init(ebt_arpreply_init);
65b4b4e8 AM	100	module_exit(ebt_arpreply_fini);
f776c4cd	101	MODULE_DESCRIPTION("Ebtables: ARP reply target");
1da177e4	102	MODULE_LICENSE("GPL");