kernel/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 <linux/module.h>
  13
  14 #define NAT_VALID_HOOKS ((1 << NF_BR_PRE_ROUTING) | (1 << NF_BR_LOCAL_OUT) | \
  15    (1 << NF_BR_POST_ROUTING))
  16
  17 static struct ebt_entries initial_chains[] = {
  18         {
  19                 .name   = "PREROUTING",
  20                 .policy = EBT_ACCEPT,
  21         },
  22         {
  23                 .name   = "OUTPUT",
  24                 .policy = EBT_ACCEPT,
  25         },
  26         {
  27                 .name   = "POSTROUTING",
  28                 .policy = EBT_ACCEPT,
  29         }
  30 };
  31
  32 static struct ebt_replace_kernel initial_table = {
  33         .name           = "nat",
  34         .valid_hooks    = NAT_VALID_HOOKS,
  35         .entries_size   = 3 * sizeof(struct ebt_entries),
  36         .hook_entry     = {
  37                 [NF_BR_PRE_ROUTING]     = &initial_chains[0],
  38                 [NF_BR_LOCAL_OUT]       = &initial_chains[1],
  39                 [NF_BR_POST_ROUTING]    = &initial_chains[2],
  40         },
  41         .entries        = (char *)initial_chains,
  42 };
  43
  44 static int check(const struct ebt_table_info *info, unsigned int valid_hooks)
  45 {
  46         if (valid_hooks & ~NAT_VALID_HOOKS)
  47                 return -EINVAL;
  48         return 0;
  49 }
  50
  51 static struct ebt_table frame_nat = {
  52         .name           = "nat",
  53         .table          = &initial_table,
  54         .valid_hooks    = NAT_VALID_HOOKS,
  55         .check          = check,
  56         .me             = THIS_MODULE,
  57 };
  58
  59 static unsigned int
  60 ebt_nat_in(const struct nf_hook_ops *ops, struct sk_buff *skb,
  61            const struct nf_hook_state *state)
  62 {
  63         return ebt_do_table(ops->hooknum, skb, state->in, state->out,
  64                             dev_net(state->in)->xt.frame_nat);
  65 }
  66
  67 static unsigned int
  68 ebt_nat_out(const struct nf_hook_ops *ops, struct sk_buff *skb,
  69             const struct nf_hook_state *state)
  70 {
  71         return ebt_do_table(ops->hooknum, skb, state->in, state->out,
  72                             dev_net(state->out)->xt.frame_nat);
  73 }
  74
  75 static struct nf_hook_ops ebt_ops_nat[] __read_mostly = {
  76         {
  77                 .hook           = ebt_nat_out,
  78                 .owner          = THIS_MODULE,
  79                 .pf             = NFPROTO_BRIDGE,
  80                 .hooknum        = NF_BR_LOCAL_OUT,
  81                 .priority       = NF_BR_PRI_NAT_DST_OTHER,
  82         },
  83         {
  84                 .hook           = ebt_nat_out,
  85                 .owner          = THIS_MODULE,
  86                 .pf             = NFPROTO_BRIDGE,
  87                 .hooknum        = NF_BR_POST_ROUTING,
  88                 .priority       = NF_BR_PRI_NAT_SRC,
  89         },
  90         {
  91                 .hook           = ebt_nat_in,
  92                 .owner          = THIS_MODULE,
  93                 .pf             = NFPROTO_BRIDGE,
  94                 .hooknum        = NF_BR_PRE_ROUTING,
  95                 .priority       = NF_BR_PRI_NAT_DST_BRIDGED,
  96         },
  97 };
  98
  99 static int __net_init frame_nat_net_init(struct net *net)
 100 {
 101         net->xt.frame_nat = ebt_register_table(net, &frame_nat);
 102         return PTR_ERR_OR_ZERO(net->xt.frame_nat);
 103 }
 104
 105 static void __net_exit frame_nat_net_exit(struct net *net)
 106 {
 107         ebt_unregister_table(net, net->xt.frame_nat);
 108 }
 109
 110 static struct pernet_operations frame_nat_net_ops = {
 111         .init = frame_nat_net_init,
 112         .exit = frame_nat_net_exit,
 113 };
 114
 115 static int __init ebtable_nat_init(void)
 116 {
 117         int ret;
 118
 119         ret = register_pernet_subsys(&frame_nat_net_ops);
 120         if (ret < 0)
 121                 return ret;
 122         ret = nf_register_hooks(ebt_ops_nat, ARRAY_SIZE(ebt_ops_nat));
 123         if (ret < 0)
 124                 unregister_pernet_subsys(&frame_nat_net_ops);
 125         return ret;
 126 }
 127
 128 static void __exit ebtable_nat_fini(void)
 129 {
 130         nf_unregister_hooks(ebt_ops_nat, ARRAY_SIZE(ebt_ops_nat));
 131         unregister_pernet_subsys(&frame_nat_net_ops);
 132 }
 133
 134 module_init(ebtable_nat_init);
 135 module_exit(ebtable_nat_fini);
 136 MODULE_LICENSE("GPL");