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 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
  53 static 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
  61 static unsigned int
  62 ebt_nat_in(void *priv, struct sk_buff *skb,
  63            const struct nf_hook_state *state)
  64 {
  65         return ebt_do_table(skb, state, state->net->xt.frame_nat);
  66 }
  67
  68 static unsigned int
  69 ebt_nat_out(void *priv, struct sk_buff *skb,
  70             const struct nf_hook_state *state)
  71 {
  72         return ebt_do_table(skb, state, state->net->xt.frame_nat);
  73 }
  74
  75 static const struct nf_hook_ops ebt_ops_nat[] = {
  76         {
  77                 .hook           = ebt_nat_out,
  78                 .pf             = NFPROTO_BRIDGE,
  79                 .hooknum        = NF_BR_LOCAL_OUT,
  80                 .priority       = NF_BR_PRI_NAT_DST_OTHER,
  81         },
  82         {
  83                 .hook           = ebt_nat_out,
  84                 .pf             = NFPROTO_BRIDGE,
  85                 .hooknum        = NF_BR_POST_ROUTING,
  86                 .priority       = NF_BR_PRI_NAT_SRC,
  87         },
  88         {
  89                 .hook           = ebt_nat_in,
  90                 .pf             = NFPROTO_BRIDGE,
  91                 .hooknum        = NF_BR_PRE_ROUTING,
  92                 .priority       = NF_BR_PRI_NAT_DST_BRIDGED,
  93         },
  94 };
  95
  96 static int __net_init frame_nat_net_init(struct net *net)
  97 {
  98         return ebt_register_table(net, &frame_nat, ebt_ops_nat,
  99                                   &net->xt.frame_nat);
 100 }
 101
 102 static void __net_exit frame_nat_net_exit(struct net *net)
 103 {
 104         ebt_unregister_table(net, net->xt.frame_nat, ebt_ops_nat);
 105 }
 106
 107 static struct pernet_operations frame_nat_net_ops = {
 108         .init = frame_nat_net_init,
 109         .exit = frame_nat_net_exit,
 110 };
 111
 112 static int __init ebtable_nat_init(void)
 113 {
 114         return register_pernet_subsys(&frame_nat_net_ops);
 115 }
 116
 117 static void __exit ebtable_nat_fini(void)
 118 {
 119         unregister_pernet_subsys(&frame_nat_net_ops);
 120 }
 121
 122 module_init(ebtable_nat_init);
 123 module_exit(ebtable_nat_fini);
 124 MODULE_LICENSE("GPL");