diff options
Diffstat (limited to 'net/bridge/netfilter/ebt_arp.c')
-rw-r--r-- | net/bridge/netfilter/ebt_arp.c | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/net/bridge/netfilter/ebt_arp.c b/net/bridge/netfilter/ebt_arp.c new file mode 100644 index 0000000..b94c48c --- /dev/null +++ b/net/bridge/netfilter/ebt_arp.c @@ -0,0 +1,140 @@ +/* + * 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, *ah; + + ah = skb_header_pointer(skb, 0, sizeof(_arph), &_arph); + if (ah == NULL) + return EBT_NOMATCH; + if (info->bitmask & EBT_ARP_OPCODE && FWINV(info->opcode != + ah->ar_op, EBT_ARP_OPCODE)) + return EBT_NOMATCH; + if (info->bitmask & EBT_ARP_HTYPE && FWINV(info->htype != + ah->ar_hrd, EBT_ARP_HTYPE)) + return EBT_NOMATCH; + if (info->bitmask & EBT_ARP_PTYPE && FWINV(info->ptype != + ah->ar_pro, EBT_ARP_PTYPE)) + return EBT_NOMATCH; + + if (info->bitmask & (EBT_ARP_SRC_IP | EBT_ARP_DST_IP)) { + uint32_t _addr, *ap; + + /* IPv4 addresses are always 4 bytes */ + if (ah->ar_pln != sizeof(uint32_t)) + return EBT_NOMATCH; + if (info->bitmask & EBT_ARP_SRC_IP) { + ap = skb_header_pointer(skb, sizeof(struct arphdr) + + ah->ar_hln, sizeof(_addr), + &_addr); + if (ap == NULL) + return EBT_NOMATCH; + if (FWINV(info->saddr != (*ap & info->smsk), + EBT_ARP_SRC_IP)) + return EBT_NOMATCH; + } + + if (info->bitmask & EBT_ARP_DST_IP) { + ap = skb_header_pointer(skb, sizeof(struct arphdr) + + 2*ah->ar_hln+sizeof(uint32_t), + sizeof(_addr), &_addr); + if (ap == NULL) + return EBT_NOMATCH; + if (FWINV(info->daddr != (*ap & 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], *mp; + uint8_t verdict, i; + + /* MAC addresses are 6 bytes */ + if (ah->ar_hln != ETH_ALEN) + return EBT_NOMATCH; + if (info->bitmask & EBT_ARP_SRC_MAC) { + mp = skb_header_pointer(skb, sizeof(struct arphdr), + sizeof(_mac), &_mac); + if (mp == NULL) + return EBT_NOMATCH; + verdict = 0; + for (i = 0; i < 6; i++) + verdict |= (mp[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) { + mp = skb_header_pointer(skb, sizeof(struct arphdr) + + ah->ar_hln + ah->ar_pln, + sizeof(_mac), &_mac); + if (mp == NULL) + return EBT_NOMATCH; + verdict = 0; + for (i = 0; i < 6; i++) + verdict |= (mp[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 != htons(ETH_P_ARP) && + e->ethproto != 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"); |