net/bridge/netfilter/ebtable_nat.c

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