// SPDX-License-Identifier: GPL-2.0-only
/*
 *  ebtable_broute
 *
 *      Authors:
 *      Bart De Schuymer <bdschuym@pandora.be>
 *
 *  April, 2002
 *
 *  This table lets you choose between routing and bridging for frames
 *  entering on a bridge enslaved nic. This table is traversed before any
 *  other ebtables table. See net/bridge/br_input.c.
 */

#include <linux/netfilter_bridge/ebtables.h>
#include <linux/module.h>
#include <linux/if_bridge.h>

#include "../br_private.h"

/* EBT_ACCEPT means the frame will be bridged
 * EBT_DROP means the frame will be routed
 */
static struct ebt_entries initial_chain = {
        .name           = "BROUTING",
        .policy         = EBT_ACCEPT,
};

static struct ebt_replace_kernel initial_table = {
        .name           = "broute",
        .valid_hooks    = 1 << NF_BR_BROUTING,
        .entries_size   = sizeof(struct ebt_entries),
        .hook_entry     = {
                [NF_BR_BROUTING]        = &initial_chain,
        },
        .entries        = (char *)&initial_chain,
};

static const struct ebt_table broute_table = {
        .name           = "broute",
        .table          = &initial_table,
        .valid_hooks    = 1 << NF_BR_BROUTING,
        .me             = THIS_MODULE,
};

static unsigned int ebt_broute(void *priv, struct sk_buff *skb,
                               const struct nf_hook_state *s)
{
        struct net_bridge_port *p = br_port_get_rcu(skb->dev);
        struct nf_hook_state state;
        unsigned char *dest;
        int ret;

        if (!p || p->state != BR_STATE_FORWARDING)
                return NF_ACCEPT;

        nf_hook_state_init(&state, NF_BR_BROUTING,
                           NFPROTO_BRIDGE, s->in, NULL, NULL,
                           s->net, NULL);

        ret = ebt_do_table(priv, skb, &state);
        if (ret != NF_DROP)
                return ret;

        /* DROP in ebtables -t broute means that the
         * skb should be routed, not bridged.
         * This is awkward, but can't be changed for compatibility
         * reasons.
         *
         * We map DROP to ACCEPT and set the ->br_netfilter_broute flag.
         */
        BR_INPUT_SKB_CB(skb)->br_netfilter_broute = 1;

        /* undo PACKET_HOST mangling done in br_input in case the dst
         * address matches the logical bridge but not the port.
         */
        dest = eth_hdr(skb)->h_dest;
        if (skb->pkt_type == PACKET_HOST &&
            !ether_addr_equal(skb->dev->dev_addr, dest) &&
             ether_addr_equal(p->br->dev->dev_addr, dest))
                skb->pkt_type = PACKET_OTHERHOST;

        return NF_ACCEPT;
}

static const struct nf_hook_ops ebt_ops_broute = {
        .hook           = ebt_broute,
        .pf             = NFPROTO_BRIDGE,
        .hooknum        = NF_BR_PRE_ROUTING,
        .priority       = NF_BR_PRI_FIRST,
};

static int broute_table_init(struct net *net)
{
        return ebt_register_table(net, &broute_table, &ebt_ops_broute);
}

static void __net_exit broute_net_pre_exit(struct net *net)
{
        ebt_unregister_table_pre_exit(net, "broute");
}

static void __net_exit broute_net_exit(struct net *net)
{
        ebt_unregister_table(net, "broute");
}

static struct pernet_operations broute_net_ops = {
        .exit = broute_net_exit,
        .pre_exit = broute_net_pre_exit,
};

static int __init ebtable_broute_init(void)
{
        int ret = ebt_register_template(&broute_table, broute_table_init);

        if (ret)
                return ret;

        ret = register_pernet_subsys(&broute_net_ops);
        if (ret) {
                ebt_unregister_template(&broute_table);
                return ret;
        }

        return 0;
}

static void __exit ebtable_broute_fini(void)
{
        unregister_pernet_subsys(&broute_net_ops);
        ebt_unregister_template(&broute_table);
}

module_init(ebtable_broute_init);
module_exit(ebtable_broute_fini);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Force packets to be routed instead of bridged");