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         {
  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 {
  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 struct ebt_table frame_nat =
  54 {
  55         .name           = "nat",
  56         .table          = &initial_table,
  57         .valid_hooks    = NAT_VALID_HOOKS,
  58         .lock           = RW_LOCK_UNLOCKED,
  59         .check          = check,
  60         .me             = THIS_MODULE,
  61 };
  62
  63 static unsigned int
  64 ebt_nat_dst(unsigned int hook, struct sk_buff *skb, const struct net_device *in
  65    , const struct net_device *out, int (*okfn)(struct sk_buff *))
  66 {
  67         return ebt_do_table(hook, skb, in, out, &frame_nat);
  68 }
  69
  70 static unsigned int
  71 ebt_nat_src(unsigned int hook, struct sk_buff *skb, const struct net_device *in
  72    , const struct net_device *out, int (*okfn)(struct sk_buff *))
  73 {
  74         return ebt_do_table(hook, skb, in, out, &frame_nat);
  75 }
  76
  77 static struct nf_hook_ops ebt_ops_nat[] __read_mostly = {
  78         {
  79                 .hook           = ebt_nat_dst,
  80                 .owner          = THIS_MODULE,
  81                 .pf             = PF_BRIDGE,
  82                 .hooknum        = NF_BR_LOCAL_OUT,
  83                 .priority       = NF_BR_PRI_NAT_DST_OTHER,
  84         },
  85         {
  86                 .hook           = ebt_nat_src,
  87                 .owner          = THIS_MODULE,
  88                 .pf             = PF_BRIDGE,
  89                 .hooknum        = NF_BR_POST_ROUTING,
  90                 .priority       = NF_BR_PRI_NAT_SRC,
  91         },
  92         {
  93                 .hook           = ebt_nat_dst,
  94                 .owner          = THIS_MODULE,
  95                 .pf             = PF_BRIDGE,
  96                 .hooknum        = NF_BR_PRE_ROUTING,
  97                 .priority       = NF_BR_PRI_NAT_DST_BRIDGED,
  98         },
  99 };
 100
 101 static int __init ebtable_nat_init(void)
 102 {
 103         int i, ret, j;
 104
 105         ret = ebt_register_table(&frame_nat);
 106         if (ret < 0)
 107                 return ret;
 108         for (i = 0; i < ARRAY_SIZE(ebt_ops_nat); i++)
 109                 if ((ret = nf_register_hook(&ebt_ops_nat[i])) < 0)
 110                         goto cleanup;
 111         return ret;
 112 cleanup:
 113         for (j = 0; j < i; j++)
 114                 nf_unregister_hook(&ebt_ops_nat[j]);
 115         ebt_unregister_table(&frame_nat);
 116         return ret;
 117 }
 118
 119 static void __exit ebtable_nat_fini(void)
 120 {
 121         int i;
 122
 123         for (i = 0; i < ARRAY_SIZE(ebt_ops_nat); i++)
 124                 nf_unregister_hook(&ebt_ops_nat[i]);
 125         ebt_unregister_table(&frame_nat);
 126 }
 127
 128 module_init(ebtable_nat_init);
 129 module_exit(ebtable_nat_fini);
 130 MODULE_LICENSE("GPL");