/* *  ebt_arp * *	Authors: *	Bart De Schuymer <bdschuym@pandora.be> *	Tim Gardner <timg@tpi.com> * *  April, 2002 * */#include <linux/netfilter_bridge/ebtables.h>#include <linux/netfilter_bridge/ebt_arp.h>#include <linux/if_arp.h>#include <linux/if_ether.h>#include <linux/module.h>static int ebt_filter_arp(const struct sk_buff *skb, const struct net_device *in,   const struct net_device *out, const void *data, unsigned int datalen){	struct ebt_arp_info *info = (struct ebt_arp_info *)data;	struct arphdr arph;	if (skb_copy_bits(skb, 0, &arph, sizeof(arph)))		return EBT_NOMATCH;	if (info->bitmask & EBT_ARP_OPCODE && FWINV(info->opcode !=	   arph.ar_op, EBT_ARP_OPCODE))		return EBT_NOMATCH;	if (info->bitmask & EBT_ARP_HTYPE && FWINV(info->htype !=	   arph.ar_hrd, EBT_ARP_HTYPE))		return EBT_NOMATCH;	if (info->bitmask & EBT_ARP_PTYPE && FWINV(info->ptype !=	   arph.ar_pro, EBT_ARP_PTYPE))		return EBT_NOMATCH;	if (info->bitmask & (EBT_ARP_SRC_IP | EBT_ARP_DST_IP)) {		uint32_t addr;		/* IPv4 addresses are always 4 bytes */		if (arph.ar_pln != sizeof(uint32_t))			return EBT_NOMATCH;		if (info->bitmask & EBT_ARP_SRC_IP) {			if (skb_copy_bits(skb, sizeof(struct arphdr) +			    arph.ar_hln, &addr, sizeof(addr)))				return EBT_NOMATCH;			if (FWINV(info->saddr != (addr & info->smsk),			   EBT_ARP_SRC_IP))				return EBT_NOMATCH;		}		if (info->bitmask & EBT_ARP_DST_IP) {			if (skb_copy_bits(skb, sizeof(struct arphdr) +			    2*arph.ar_hln + sizeof(uint32_t), &addr,			    sizeof(addr)))				return EBT_NOMATCH;			if (FWINV(info->daddr != (addr & info->dmsk),			   EBT_ARP_DST_IP))				return EBT_NOMATCH;		}	}	if (info->bitmask & (EBT_ARP_SRC_MAC | EBT_ARP_DST_MAC)) {		unsigned char mac[ETH_ALEN];		uint8_t verdict, i;		/* MAC addresses are 6 bytes */		if (arph.ar_hln != ETH_ALEN)			return EBT_NOMATCH;		if (info->bitmask & EBT_ARP_SRC_MAC) {			if (skb_copy_bits(skb, sizeof(struct arphdr), &mac,			    ETH_ALEN))				return EBT_NOMATCH;			verdict = 0;			for (i = 0; i < 6; i++)				verdict |= (mac[i] ^ info->smaddr[i]) &				       info->smmsk[i];			if (FWINV(verdict != 0, EBT_ARP_SRC_MAC))				return EBT_NOMATCH;		}		if (info->bitmask & EBT_ARP_DST_MAC) {			if (skb_copy_bits(skb, sizeof(struct arphdr) +			    arph.ar_hln + arph.ar_pln, &mac, ETH_ALEN))				return EBT_NOMATCH;			verdict = 0;			for (i = 0; i < 6; i++)				verdict |= (mac[i] ^ info->dmaddr[i]) &					info->dmmsk[i];			if (FWINV(verdict != 0, EBT_ARP_DST_MAC))				return EBT_NOMATCH;		}	}	return EBT_MATCH;}static int ebt_arp_check(const char *tablename, unsigned int hookmask,   const struct ebt_entry *e, void *data, unsigned int datalen){	struct ebt_arp_info *info = (struct ebt_arp_info *)data;	if (datalen != EBT_ALIGN(sizeof(struct ebt_arp_info)))		return -EINVAL;	if ((e->ethproto != __constant_htons(ETH_P_ARP) &&	   e->ethproto != __constant_htons(ETH_P_RARP)) ||	   e->invflags & EBT_IPROTO)		return -EINVAL;	if (info->bitmask & ~EBT_ARP_MASK || info->invflags & ~EBT_ARP_MASK)		return -EINVAL;	return 0;}static struct ebt_match filter_arp ={	.name		= EBT_ARP_MATCH,	.match		= ebt_filter_arp,	.check		= ebt_arp_check,	.me		= THIS_MODULE,};static int __init init(void){	return ebt_register_match(&filter_arp);}static void __exit fini(void){	ebt_unregister_match(&filter_arp);}module_init(init);module_exit(fini);MODULE_LICENSE("GPL");