| /* |
| * 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_target_reply(struct sk_buff *skb, unsigned int hooknr, |
| const struct net_device *in, const struct net_device *out, |
| const void *data, unsigned int datalen) |
| { |
| struct ebt_arpreply_info *info = (void *)data; |
| 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 *)in, |
| *diptr, shp, info->mac, shp); |
| |
| return info->target; |
| } |
| |
| static bool ebt_target_reply_check(const char *tablename, unsigned int hookmask, |
| const struct ebt_entry *e, void *data, unsigned int datalen) |
| { |
| const struct ebt_arpreply_info *info = data; |
| |
| 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; |
| if (strcmp(tablename, "nat") || hookmask & ~(1 << NF_BR_PRE_ROUTING)) |
| return false; |
| return true; |
| } |
| |
| static struct ebt_target reply_target __read_mostly = { |
| .name = EBT_ARPREPLY_TARGET, |
| .target = ebt_target_reply, |
| .check = ebt_target_reply_check, |
| .targetsize = XT_ALIGN(sizeof(struct ebt_arpreply_info)), |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init ebt_arpreply_init(void) |
| { |
| return ebt_register_target(&reply_target); |
| } |
| |
| static void __exit ebt_arpreply_fini(void) |
| { |
| ebt_unregister_target(&reply_target); |
| } |
| |
| module_init(ebt_arpreply_init); |
| module_exit(ebt_arpreply_fini); |
| MODULE_DESCRIPTION("Ebtables: ARP reply target"); |
| MODULE_LICENSE("GPL"); |