LXR linux/net/bridge/netfilter/ebt

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  ebt_dnat
   4 *
   5 *      Authors:
   6 *      Bart De Schuymer <bdschuym@pandora.be>
   7 *
   8 *  June, 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_nat.h>
  18
  19static unsigned int
  20ebt_dnat_tg(struct sk_buff *skb, const struct xt_action_param *par)
  21{
  22        const struct ebt_nat_info *info = par->targinfo;
  23        struct net_device *dev;
  24
  25        if (skb_ensure_writable(skb, ETH_ALEN))
  26                return EBT_DROP;
  27
  28        ether_addr_copy(eth_hdr(skb)->h_dest, info->mac);
  29
  30        if (is_multicast_ether_addr(info->mac)) {
  31                if (is_broadcast_ether_addr(info->mac))
  32                        skb->pkt_type = PACKET_BROADCAST;
  33                else
  34                        skb->pkt_type = PACKET_MULTICAST;
  35        } else {
  36                if (xt_hooknum(par) != NF_BR_BROUTING)
  37                        dev = br_port_get_rcu(xt_in(par))->br->dev;
  38                else
  39                        dev = xt_in(par);
  40
  41                if (ether_addr_equal(info->mac, dev->dev_addr))
  42                        skb->pkt_type = PACKET_HOST;
  43                else
  44                        skb->pkt_type = PACKET_OTHERHOST;
  45        }
  46
  47        return info->target;
  48}
  49
  50static int ebt_dnat_tg_check(const struct xt_tgchk_param *par)
  51{
  52        const struct ebt_nat_info *info = par->targinfo;
  53        unsigned int hook_mask;
  54
  55        if (BASE_CHAIN && info->target == EBT_RETURN)
  56                return -EINVAL;
  57
  58        hook_mask = par->hook_mask & ~(1 << NF_BR_NUMHOOKS);
  59        if ((strcmp(par->table, "nat") != 0 ||
  60            (hook_mask & ~((1 << NF_BR_PRE_ROUTING) |
  61            (1 << NF_BR_LOCAL_OUT)))) &&
  62            (strcmp(par->table, "broute") != 0 ||
  63            hook_mask & ~(1 << NF_BR_BROUTING)))
  64                return -EINVAL;
  65        if (ebt_invalid_target(info->target))
  66                return -EINVAL;
  67        return 0;
  68}
  69
  70static struct xt_target ebt_dnat_tg_reg __read_mostly = {
  71        .name           = "dnat",
  72        .revision       = 0,
  73        .family         = NFPROTO_BRIDGE,
  74        .hooks          = (1 << NF_BR_NUMHOOKS) | (1 << NF_BR_PRE_ROUTING) |
  75                          (1 << NF_BR_LOCAL_OUT) | (1 << NF_BR_BROUTING),
  76        .target         = ebt_dnat_tg,
  77        .checkentry     = ebt_dnat_tg_check,
  78        .targetsize     = sizeof(struct ebt_nat_info),
  79        .me             = THIS_MODULE,
  80};
  81
  82static int __init ebt_dnat_init(void)
  83{
  84        return xt_register_target(&ebt_dnat_tg_reg);
  85}
  86
  87static void __exit ebt_dnat_fini(void)
  88{
  89        xt_unregister_target(&ebt_dnat_tg_reg);
  90}
  91
  92module_init(ebt_dnat_init);
  93module_exit(ebt_dnat_fini);
  94MODULE_DESCRIPTION("Ebtables: Destination MAC address translation");
  95MODULE_LICENSE("GPL");
  96