LXR linux/net/bridge/netfilter/ebt

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  ebt_redirect
   4 *
   5 *      Authors:
   6 *      Bart De Schuymer <bdschuym@pandora.be>
   7 *
   8 *  April, 2002
   9 *
  10 */
  11#include <linux/module.h>
  12#include <net/sock.h>
  13#include "../br_private.h"
  14#include <linux/netfilter.h>
  15#include <linux/netfilter/x_tables.h>
  16#include <linux/netfilter_bridge/ebtables.h>
  17#include <linux/netfilter_bridge/ebt_redirect.h>
  18
  19static unsigned int
  20ebt_redirect_tg(struct sk_buff *skb, const struct xt_action_param *par)
  21{
  22        const struct ebt_redirect_info *info = par->targinfo;
  23
  24        if (skb_ensure_writable(skb, ETH_ALEN))
  25                return EBT_DROP;
  26
  27        if (xt_hooknum(par) != NF_BR_BROUTING)
  28                /* rcu_read_lock()ed by nf_hook_thresh */
  29                ether_addr_copy(eth_hdr(skb)->h_dest,
  30                                br_port_get_rcu(xt_in(par))->br->dev->dev_addr);
  31        else
  32                ether_addr_copy(eth_hdr(skb)->h_dest, xt_in(par)->dev_addr);
  33        skb->pkt_type = PACKET_HOST;
  34        return info->target;
  35}
  36
  37static int ebt_redirect_tg_check(const struct xt_tgchk_param *par)
  38{
  39        const struct ebt_redirect_info *info = par->targinfo;
  40        unsigned int hook_mask;
  41
  42        if (BASE_CHAIN && info->target == EBT_RETURN)
  43                return -EINVAL;
  44
  45        hook_mask = par->hook_mask & ~(1 << NF_BR_NUMHOOKS);
  46        if ((strcmp(par->table, "nat") != 0 ||
  47            hook_mask & ~(1 << NF_BR_PRE_ROUTING)) &&
  48            (strcmp(par->table, "broute") != 0 ||
  49            hook_mask & ~(1 << NF_BR_BROUTING)))
  50                return -EINVAL;
  51        if (ebt_invalid_target(info->target))
  52                return -EINVAL;
  53        return 0;
  54}
  55
  56static struct xt_target ebt_redirect_tg_reg __read_mostly = {
  57        .name           = "redirect",
  58        .revision       = 0,
  59        .family         = NFPROTO_BRIDGE,
  60        .hooks          = (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_PRE_ROUTING) |
  61                          (1 << NF_BR_BROUTING),
  62        .target         = ebt_redirect_tg,
  63        .checkentry     = ebt_redirect_tg_check,
  64        .targetsize     = sizeof(struct ebt_redirect_info),
  65        .me             = THIS_MODULE,
  66};
  67
  68static int __init ebt_redirect_init(void)
  69{
  70        return xt_register_target(&ebt_redirect_tg_reg);
  71}
  72
  73static void __exit ebt_redirect_fini(void)
  74{
  75        xt_unregister_target(&ebt_redirect_tg_reg);
  76}
  77
  78module_init(ebt_redirect_init);
  79module_exit(ebt_redirect_fini);
  80MODULE_DESCRIPTION("Ebtables: Packet redirection to localhost");
  81MODULE_LICENSE("GPL");
  82