ebt_redirect.c

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/*
 *  ebt_redirect
 *
 *  Authors:
 *  Bart De Schuymer <[email protected]>
 *
 *  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_make_writable(skb, 0))
        return EBT_DROP;

    if (par->hooknum != NF_BR_BROUTING)
        /* rcu_read_lock()ed by nf_hook_slow */
        memcpy(eth_hdr(skb)->h_dest,
               br_port_get_rcu(par->in)->br->dev->dev_addr, ETH_ALEN);
    else
        memcpy(eth_hdr(skb)->h_dest, par->in->dev_addr, ETH_ALEN);
    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 (INVALID_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");