1 files changed, 103 insertions, 0 deletions
diff --git a/net/bridge/netfilter/ebt_arpreply.c b/net/bridge/netfilter/ebt_arpreply.c
new file mode 100644
index 000000000..d9e77e250
--- /dev/null
+++ b/net/bridge/netfilter/ebt_arpreply.c
@@ -0,0 +1,103 @@
+// 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");