LXR linux/net/bridge/netfilter/ebtable

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  ebtable_nat
   4 *
   5 *      Authors:
   6 *      Bart De Schuymer <bdschuym@pandora.be>
   7 *
   8 *  April, 2002
   9 *
  10 */
  11
  12#include <linux/netfilter_bridge/ebtables.h>
  13#include <uapi/linux/netfilter_bridge.h>
  14#include <linux/module.h>
  15
  16#define NAT_VALID_HOOKS ((1 << NF_BR_PRE_ROUTING) | (1 << NF_BR_LOCAL_OUT) | \
  17                         (1 << NF_BR_POST_ROUTING))
  18
  19static struct ebt_entries initial_chains[] = {
  20        {
  21                .name   = "PREROUTING",
  22                .policy = EBT_ACCEPT,
  23        },
  24        {
  25                .name   = "OUTPUT",
  26                .policy = EBT_ACCEPT,
  27        },
  28        {
  29                .name   = "POSTROUTING",
  30                .policy = EBT_ACCEPT,
  31        }
  32};
  33
  34static struct ebt_replace_kernel initial_table = {
  35        .name           = "nat",
  36        .valid_hooks    = NAT_VALID_HOOKS,
  37        .entries_size   = 3 * sizeof(struct ebt_entries),
  38        .hook_entry     = {
  39                [NF_BR_PRE_ROUTING]     = &initial_chains[0],
  40                [NF_BR_LOCAL_OUT]       = &initial_chains[1],
  41                [NF_BR_POST_ROUTING]    = &initial_chains[2],
  42        },
  43        .entries        = (char *)initial_chains,
  44};
  45
  46static int check(const struct ebt_table_info *info, unsigned int valid_hooks)
  47{
  48        if (valid_hooks & ~NAT_VALID_HOOKS)
  49                return -EINVAL;
  50        return 0;
  51}
  52
  53static const struct ebt_table frame_nat = {
  54        .name           = "nat",
  55        .table          = &initial_table,
  56        .valid_hooks    = NAT_VALID_HOOKS,
  57        .check          = check,
  58        .me             = THIS_MODULE,
  59};
  60
  61static unsigned int ebt_nat_hook(void *priv, struct sk_buff *skb,
  62                                 const struct nf_hook_state *state)
  63{
  64        return ebt_do_table(skb, state, priv);
  65}
  66
  67static const struct nf_hook_ops ebt_ops_nat[] = {
  68        {
  69                .hook           = ebt_nat_hook,
  70                .pf             = NFPROTO_BRIDGE,
  71                .hooknum        = NF_BR_LOCAL_OUT,
  72                .priority       = NF_BR_PRI_NAT_DST_OTHER,
  73        },
  74        {
  75                .hook           = ebt_nat_hook,
  76                .pf             = NFPROTO_BRIDGE,
  77                .hooknum        = NF_BR_POST_ROUTING,
  78                .priority       = NF_BR_PRI_NAT_SRC,
  79        },
  80        {
  81                .hook           = ebt_nat_hook,
  82                .pf             = NFPROTO_BRIDGE,
  83                .hooknum        = NF_BR_PRE_ROUTING,
  84                .priority       = NF_BR_PRI_NAT_DST_BRIDGED,
  85        },
  86};
  87
  88static int frame_nat_table_init(struct net *net)
  89{
  90        return ebt_register_table(net, &frame_nat, ebt_ops_nat);
  91}
  92
  93static void __net_exit frame_nat_net_pre_exit(struct net *net)
  94{
  95        ebt_unregister_table_pre_exit(net, "nat");
  96}
  97
  98static void __net_exit frame_nat_net_exit(struct net *net)
  99{
 100        ebt_unregister_table(net, "nat");
 101}
 102
 103static struct pernet_operations frame_nat_net_ops = {
 104        .exit = frame_nat_net_exit,
 105        .pre_exit = frame_nat_net_pre_exit,
 106};
 107
 108static int __init ebtable_nat_init(void)
 109{
 110        int ret = ebt_register_template(&frame_nat, frame_nat_table_init);
 111
 112        if (ret)
 113                return ret;
 114
 115        ret = register_pernet_subsys(&frame_nat_net_ops);
 116        if (ret) {
 117                ebt_unregister_template(&frame_nat);
 118                return ret;
 119        }
 120
 121        return ret;
 122}
 123
 124static void __exit ebtable_nat_fini(void)
 125{
 126        unregister_pernet_subsys(&frame_nat_net_ops);
 127        ebt_unregister_template(&frame_nat);
 128}
 129
 130module_init(ebtable_nat_init);
 131module_exit(ebtable_nat_fini);
 132MODULE_LICENSE("GPL");
 133