net/bridge/netfilter/ebtable_nat.c

   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
  19 static 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
  34 static 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
  46 static const struct ebt_table frame_nat = {
  47         .name           = "nat",
  48         .table          = &initial_table,
  49         .valid_hooks    = NAT_VALID_HOOKS,
  50         .me             = THIS_MODULE,
  51 };
  52
  53 static unsigned int ebt_nat_hook(void *priv, struct sk_buff *skb,
  54                                  const struct nf_hook_state *state)
  55 {
  56         return ebt_do_table(skb, state, priv);
  57 }
  58
  59 static const struct nf_hook_ops ebt_ops_nat[] = {
  60         {
  61                 .hook           = ebt_nat_hook,
  62                 .pf             = NFPROTO_BRIDGE,
  63                 .hooknum        = NF_BR_LOCAL_OUT,
  64                 .priority       = NF_BR_PRI_NAT_DST_OTHER,
  65         },
  66         {
  67                 .hook           = ebt_nat_hook,
  68                 .pf             = NFPROTO_BRIDGE,
  69                 .hooknum        = NF_BR_POST_ROUTING,
  70                 .priority       = NF_BR_PRI_NAT_SRC,
  71         },
  72         {
  73                 .hook           = ebt_nat_hook,
  74                 .pf             = NFPROTO_BRIDGE,
  75                 .hooknum        = NF_BR_PRE_ROUTING,
  76                 .priority       = NF_BR_PRI_NAT_DST_BRIDGED,
  77         },
  78 };
  79
  80 static int frame_nat_table_init(struct net *net)
  81 {
  82         return ebt_register_table(net, &frame_nat, ebt_ops_nat);
  83 }
  84
  85 static void __net_exit frame_nat_net_pre_exit(struct net *net)
  86 {
  87         ebt_unregister_table_pre_exit(net, "nat");
  88 }
  89
  90 static void __net_exit frame_nat_net_exit(struct net *net)
  91 {
  92         ebt_unregister_table(net, "nat");
  93 }
  94
  95 static struct pernet_operations frame_nat_net_ops = {
  96         .exit = frame_nat_net_exit,
  97         .pre_exit = frame_nat_net_pre_exit,
  98 };
  99
 100 static int __init ebtable_nat_init(void)
 101 {
 102         int ret = ebt_register_template(&frame_nat, frame_nat_table_init);
 103
 104         if (ret)
 105                 return ret;
 106
 107         ret = register_pernet_subsys(&frame_nat_net_ops);
 108         if (ret) {
 109                 ebt_unregister_template(&frame_nat);
 110                 return ret;
 111         }
 112
 113         return ret;
 114 }
 115
 116 static void __exit ebtable_nat_fini(void)
 117 {
 118         unregister_pernet_subsys(&frame_nat_net_ops);
 119         ebt_unregister_template(&frame_nat);
 120 }
 121
 122 module_init(ebtable_nat_init);
 123 module_exit(ebtable_nat_fini);
 124 MODULE_LICENSE("GPL");