// SPDX-License-Identifier: GPL-2.0-only
/*
 *  ebt_dnat
 *
 *      Authors:
 *      Bart De Schuymer <bdschuym@pandora.be>
 *
 *  June, 2002
 *
 */
#include <linux/module.h>
#include <net/sock.h>
#include "../br_private.h"
#include <linux/netfilter.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_bridge/ebtables.h>
#include <linux/netfilter_bridge/ebt_nat.h>

static unsigned int
ebt_dnat_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
        const struct ebt_nat_info *info = par->targinfo;

        if (skb_ensure_writable(skb, 0))
                return EBT_DROP;

        ether_addr_copy(eth_hdr(skb)->h_dest, info->mac);

        if (is_multicast_ether_addr(info->mac)) {
                if (is_broadcast_ether_addr(info->mac))
                        skb->pkt_type = PACKET_BROADCAST;
                else
                        skb->pkt_type = PACKET_MULTICAST;
        } else {
                const struct net_device *dev;

                switch (xt_hooknum(par)) {
                case NF_BR_BROUTING:
                        dev = xt_in(par);
                        break;
                case NF_BR_PRE_ROUTING:
                        dev = br_port_get_rcu(xt_in(par))->br->dev;
                        break;
                default:
                        dev = NULL;
                        break;
                }

                if (!dev) /* NF_BR_LOCAL_OUT */
                        return info->target;

                if (ether_addr_equal(info->mac, dev->dev_addr))
                        skb->pkt_type = PACKET_HOST;
                else
                        skb->pkt_type = PACKET_OTHERHOST;
        }

        return info->target;
}

static int ebt_dnat_tg_check(const struct xt_tgchk_param *par)
{
        const struct ebt_nat_info *info = par->targinfo;
        unsigned int hook_mask;

        if (BASE_CHAIN && info->target == EBT_RETURN)
                return -EINVAL;

        hook_mask = par->hook_mask & ~(1 << NF_BR_NUMHOOKS);
        if ((strcmp(par->table, "nat") != 0 ||
            (hook_mask & ~((1 << NF_BR_PRE_ROUTING) |
            (1 << NF_BR_LOCAL_OUT)))) &&
            (strcmp(par->table, "broute") != 0 ||
            hook_mask & ~(1 << NF_BR_BROUTING)))
                return -EINVAL;
        if (ebt_invalid_target(info->target))
                return -EINVAL;
        return 0;
}

static struct xt_target ebt_dnat_tg_reg __read_mostly = {
        .name           = "dnat",
        .revision       = 0,
        .family         = NFPROTO_BRIDGE,
        .hooks          = (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_PRE_ROUTING) |
                          (1 << NF_BR_LOCAL_OUT) | (1 << NF_BR_BROUTING),
        .target         = ebt_dnat_tg,
        .checkentry     = ebt_dnat_tg_check,
        .targetsize     = sizeof(struct ebt_nat_info),
        .me             = THIS_MODULE,
};

static int __init ebt_dnat_init(void)
{
        return xt_register_target(&ebt_dnat_tg_reg);
}

static void __exit ebt_dnat_fini(void)
{
        xt_unregister_target(&ebt_dnat_tg_reg);
}

module_init(ebt_dnat_init);
module_exit(ebt_dnat_fini);
MODULE_DESCRIPTION("Ebtables: Destination MAC address translation");
MODULE_LICENSE("GPL");