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/*
* 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 != 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");
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