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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * 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_arpreply_tg(struct sk_buff *skb, const struct xt_action_param *par)
- {
- const struct ebt_arpreply_info *info = par->targinfo;
- 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 *)xt_in(par),
- *diptr, shp, info->mac, shp);
- return info->target;
- }
- static int ebt_arpreply_tg_check(const struct xt_tgchk_param *par)
- {
- const struct ebt_arpreply_info *info = par->targinfo;
- const struct ebt_entry *e = par->entryinfo;
- if (BASE_CHAIN && info->target == EBT_RETURN)
- return -EINVAL;
- if (e->ethproto != htons(ETH_P_ARP) ||
- e->invflags & EBT_IPROTO)
- return -EINVAL;
- if (ebt_invalid_target(info->target))
- return -EINVAL;
- return 0;
- }
- static struct xt_target ebt_arpreply_tg_reg __read_mostly = {
- .name = "arpreply",
- .revision = 0,
- .family = NFPROTO_BRIDGE,
- .table = "nat",
- .hooks = (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_PRE_ROUTING),
- .target = ebt_arpreply_tg,
- .checkentry = ebt_arpreply_tg_check,
- .targetsize = sizeof(struct ebt_arpreply_info),
- .me = THIS_MODULE,
- };
- static int __init ebt_arpreply_init(void)
- {
- return xt_register_target(&ebt_arpreply_tg_reg);
- }
- static void __exit ebt_arpreply_fini(void)
- {
- xt_unregister_target(&ebt_arpreply_tg_reg);
- }
- module_init(ebt_arpreply_init);
- module_exit(ebt_arpreply_fini);
- MODULE_DESCRIPTION("Ebtables: ARP reply target");
- MODULE_LICENSE("GPL");
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