diff options
Diffstat (limited to 'net/bridge/netfilter/ebt_arpreply.c')
-rw-r--r-- | net/bridge/netfilter/ebt_arpreply.c | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/net/bridge/netfilter/ebt_arpreply.c b/net/bridge/netfilter/ebt_arpreply.c new file mode 100644 index 000000000000..b934de90f7c5 --- /dev/null +++ b/net/bridge/netfilter/ebt_arpreply.c @@ -0,0 +1,97 @@ +/* + * ebt_arpreply + * + * Authors: + * Grzegorz Borowiak <grzes@gnu.univ.gda.pl> + * Bart De Schuymer <bdschuym@pandora.be> + * + * August, 2003 + * + */ + +#include <linux/netfilter_bridge/ebtables.h> +#include <linux/netfilter_bridge/ebt_arpreply.h> +#include <linux/if_arp.h> +#include <net/arp.h> +#include <linux/module.h> + +static int ebt_target_reply(struct sk_buff **pskb, unsigned int hooknr, + const struct net_device *in, const struct net_device *out, + const void *data, unsigned int datalen) +{ + struct ebt_arpreply_info *info = (struct ebt_arpreply_info *)data; + u32 _sip, *siptr, _dip, *diptr; + struct arphdr _ah, *ap; + unsigned char _sha[ETH_ALEN], *shp; + struct sk_buff *skb = *pskb; + + 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 int ebt_target_reply_check(const char *tablename, unsigned int hookmask, + const struct ebt_entry *e, void *data, unsigned int datalen) +{ + struct ebt_arpreply_info *info = (struct ebt_arpreply_info *)data; + + if (datalen != EBT_ALIGN(sizeof(struct ebt_arpreply_info))) + return -EINVAL; + if (BASE_CHAIN && info->target == EBT_RETURN) + return -EINVAL; + if (e->ethproto != htons(ETH_P_ARP) || + e->invflags & EBT_IPROTO) + return -EINVAL; + CLEAR_BASE_CHAIN_BIT; + if (strcmp(tablename, "nat") || hookmask & ~(1 << NF_BR_PRE_ROUTING)) + return -EINVAL; + return 0; +} + +static struct ebt_target reply_target = +{ + .name = EBT_ARPREPLY_TARGET, + .target = ebt_target_reply, + .check = ebt_target_reply_check, + .me = THIS_MODULE, +}; + +static int __init init(void) +{ + return ebt_register_target(&reply_target); +} + +static void __exit fini(void) +{ + ebt_unregister_target(&reply_target); +} + +module_init(init); +module_exit(fini); +MODULE_LICENSE("GPL"); |