ebtable_broute.c

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/*
 *  ebtable_broute
 *
 *  Authors:
 *  Bart De Schuymer <[email protected]>
 *
 *  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>

/* 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 int check(const struct ebt_table_info *info, unsigned int valid_hooks)
{
    if (valid_hooks & ~(1 << NF_BR_BROUTING))
        return -EINVAL;
    return 0;
}

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

static int ebt_broute(struct sk_buff *skb)
{
    int ret;

    ret = ebt_do_table(NF_BR_BROUTING, skb, skb->dev, NULL,
               dev_net(skb->dev)->xt.broute_table);
    if (ret == NF_DROP)
        return 1; /* route it */
    return 0; /* bridge it */
}

static int __net_init broute_net_init(struct net *net)
{
    net->xt.broute_table = ebt_register_table(net, &broute_table);
    if (IS_ERR(net->xt.broute_table))
        return PTR_ERR(net->xt.broute_table);
    return 0;
}

static void __net_exit broute_net_exit(struct net *net)
{
    ebt_unregister_table(net, net->xt.broute_table);
}

static struct pernet_operations broute_net_ops = {
    .init = broute_net_init,
    .exit = broute_net_exit,
};

static int __init ebtable_broute_init(void)
{
    int ret;

    ret = register_pernet_subsys(&broute_net_ops);
    if (ret < 0)
        return ret;
    /* see br_input.c */
    RCU_INIT_POINTER(br_should_route_hook,
               (br_should_route_hook_t *)ebt_broute);
    return 0;
}

static void __exit ebtable_broute_fini(void)
{
    RCU_INIT_POINTER(br_should_route_hook, NULL);
    synchronize_net();
    unregister_pernet_subsys(&broute_net_ops);
}

module_init(ebtable_broute_init);
module_exit(ebtable_broute_fini);
MODULE_LICENSE("GPL");