// SPDX-License-Identifier: GPL-2.0-only
/*
 *  ebt_redirect
 *
 *      Authors:
 *      Bart De Schuymer <bdschuym@pandora.be>
 *
 *  April, 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_redirect.h>

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

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

        if (xt_hooknum(par) != NF_BR_BROUTING)
                /* rcu_read_lock()ed by nf_hook_thresh */
                ether_addr_copy(eth_hdr(skb)->h_dest,
                                br_port_get_rcu(xt_in(par))->br->dev->dev_addr);
        else
                ether_addr_copy(eth_hdr(skb)->h_dest, xt_in(par)->dev_addr);
        skb->pkt_type = PACKET_HOST;
        return info->target;
}

static int ebt_redirect_tg_check(const struct xt_tgchk_param *par)
{
        const struct ebt_redirect_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)) &&
            (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_redirect_tg_reg __read_mostly = {
        .name           = "redirect",
        .revision       = 0,
        .family         = NFPROTO_BRIDGE,
        .hooks          = (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_PRE_ROUTING) |
                          (1 << NF_BR_BROUTING),
        .target         = ebt_redirect_tg,
        .checkentry     = ebt_redirect_tg_check,
        .targetsize     = sizeof(struct ebt_redirect_info),
        .me             = THIS_MODULE,
};

static int __init ebt_redirect_init(void)
{
        return xt_register_target(&ebt_redirect_tg_reg);
}

static void __exit ebt_redirect_fini(void)
{
        xt_unregister_target(&ebt_redirect_tg_reg);
}

module_init(ebt_redirect_init);
module_exit(ebt_redirect_fini);
MODULE_DESCRIPTION("Ebtables: Packet redirection to localhost");
MODULE_LICENSE("GPL");