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

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  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_action_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 *)xt_in(par),
		 *diptr, shp, info->mac, shp);

	return info->target;
}

static int ebt_arpreply_tg_check(const struct xt_tgchk_param *par)
{
	const struct ebt_arpreply_info *info = par->targinfo;
	const struct ebt_entry *e = par->entryinfo;

	if (BASE_CHAIN && info->target == EBT_RETURN)
		return -EINVAL;
	if (e->ethproto != htons(ETH_P_ARP) ||
	    e->invflags & EBT_IPROTO)
		return -EINVAL;
	if (ebt_invalid_target(info->target))
		return -EINVAL;

	return 0;
}

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	= 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
09c434b8	1	// SPDX-License-Identifier: GPL-2.0-only
1da177e4 LT	2	/*
	3	* ebt_arpreply
	4	*
	5	* Authors:
	6	* Grzegorz Borowiak <grzes@gnu.univ.gda.pl>
	7	* Bart De Schuymer <bdschuym@pandora.be>
	8	*
	9	* August, 2003
	10	*
	11	*/
1da177e4 LT	12	#include <linux/if_arp.h>
	13	#include <net/arp.h>
	14	#include <linux/module.h>
18219d3f JE	15	#include <linux/netfilter/x_tables.h>
	16	#include <linux/netfilter_bridge/ebtables.h>
	17	#include <linux/netfilter_bridge/ebt_arpreply.h>
1da177e4	18
2d06d4a5	19	static unsigned int
4b560b44	20	ebt_arpreply_tg(struct sk_buff skb, const struct xt_action_param par)
1da177e4	21	{
7eb35586	22	const struct ebt_arpreply_info *info = par->targinfo;
abfdf1c4 JE	23	const __be32 siptr, diptr;
	24	__be32 _sip, _dip;
	25	const struct arphdr *ap;
	26	struct arphdr _ah;
	27	const unsigned char *shp;
	28	unsigned char _sha[ETH_ALEN];
1da177e4 LT	29
	30	ap = skb_header_pointer(skb, 0, sizeof(_ah), &_ah);
	31	if (ap == NULL)
	32	return EBT_DROP;
	33
	34	if (ap->ar_op != htons(ARPOP_REQUEST) \|\|
	35	ap->ar_hln != ETH_ALEN \|\|
	36	ap->ar_pro != htons(ETH_P_IP) \|\|
	37	ap->ar_pln != 4)
	38	return EBT_CONTINUE;
	39
	40	shp = skb_header_pointer(skb, sizeof(_ah), ETH_ALEN, &_sha);
	41	if (shp == NULL)
	42	return EBT_DROP;
	43
	44	siptr = skb_header_pointer(skb, sizeof(_ah) + ETH_ALEN,
	45	sizeof(_sip), &_sip);
	46	if (siptr == NULL)
	47	return EBT_DROP;
	48
	49	diptr = skb_header_pointer(skb,
	50	sizeof(_ah) + 2 * ETH_ALEN + sizeof(_sip),
	51	sizeof(_dip), &_dip);
	52	if (diptr == NULL)
	53	return EBT_DROP;
	54
613dbd95 PNA	55	arp_send(ARPOP_REPLY, ETH_P_ARP, *siptr,
613dbd95 PNA	56	(struct net_device *)xt_in(par),
9d6f229f	57	*diptr, shp, info->mac, shp);
1da177e4 LT	58
	59	return info->target;
	60	}
	61
135367b8	62	static int ebt_arpreply_tg_check(const struct xt_tgchk_param *par)
1da177e4	63	{
af5d6dc2 JE	64	const struct ebt_arpreply_info *info = par->targinfo;
af5d6dc2 JE	65	const struct ebt_entry *e = par->entryinfo;
1da177e4	66
1da177e4	67	if (BASE_CHAIN && info->target == EBT_RETURN)
d6b00a53	68	return -EINVAL;
1da177e4 LT	69	if (e->ethproto != htons(ETH_P_ARP) \|\|
1da177e4 LT	70	e->invflags & EBT_IPROTO)
d6b00a53	71	return -EINVAL;
c953d635 GF	72	if (ebt_invalid_target(info->target))
	73	return -EINVAL;
	74
d6b00a53	75	return 0;
1da177e4 LT	76	}
1da177e4 LT	77
043ef46c JE	78	static struct xt_target ebt_arpreply_tg_reg __read_mostly = {
043ef46c JE	79	.name = "arpreply",
001a18d3 JE	80	.revision = 0,
001a18d3 JE	81	.family = NFPROTO_BRIDGE,
f2ff525c JE	82	.table = "nat",
f2ff525c JE	83	.hooks = (1 << NF_BR_NUMHOOKS) \| (1 << NF_BR_PRE_ROUTING),
2d06d4a5 JE	84	.target = ebt_arpreply_tg,
2d06d4a5 JE	85	.checkentry = ebt_arpreply_tg_check,
fc0e3df4	86	.targetsize = sizeof(struct ebt_arpreply_info),
1da177e4 LT	87	.me = THIS_MODULE,
	88	};
	89
65b4b4e8	90	static int __init ebt_arpreply_init(void)
1da177e4	91	{
043ef46c	92	return xt_register_target(&ebt_arpreply_tg_reg);
1da177e4 LT	93	}
1da177e4 LT	94
65b4b4e8	95	static void __exit ebt_arpreply_fini(void)
1da177e4	96	{
043ef46c	97	xt_unregister_target(&ebt_arpreply_tg_reg);
1da177e4 LT	98	}
1da177e4 LT	99
65b4b4e8 AM	100	module_init(ebt_arpreply_init);
65b4b4e8 AM	101	module_exit(ebt_arpreply_fini);
f776c4cd	102	MODULE_DESCRIPTION("Ebtables: ARP reply target");
1da177e4	103	MODULE_LICENSE("GPL");