linux/net/bridge/netfilter/ebtable_nat.c
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   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
  17static 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
  33static 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
  46static 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
  53static struct ebt_table frame_nat =
  54{
  55        .name           = "nat",
  56        .table          = &initial_table,
  57        .valid_hooks    = NAT_VALID_HOOKS,
  58        .check          = check,
  59        .me             = THIS_MODULE,
  60};
  61
  62static unsigned int
  63ebt_nat_in(unsigned int hook, struct sk_buff *skb, const struct net_device *in
  64   , const struct net_device *out, int (*okfn)(struct sk_buff *))
  65{
  66        return ebt_do_table(hook, skb, in, out, dev_net(in)->xt.frame_nat);
  67}
  68
  69static unsigned int
  70ebt_nat_out(unsigned int hook, struct sk_buff *skb, const struct net_device *in
  71   , const struct net_device *out, int (*okfn)(struct sk_buff *))
  72{
  73        return ebt_do_table(hook, skb, in, out, dev_net(out)->xt.frame_nat);
  74}
  75
  76static struct nf_hook_ops ebt_ops_nat[] __read_mostly = {
  77        {
  78                .hook           = ebt_nat_out,
  79                .owner          = THIS_MODULE,
  80                .pf             = NFPROTO_BRIDGE,
  81                .hooknum        = NF_BR_LOCAL_OUT,
  82                .priority       = NF_BR_PRI_NAT_DST_OTHER,
  83        },
  84        {
  85                .hook           = ebt_nat_out,
  86                .owner          = THIS_MODULE,
  87                .pf             = NFPROTO_BRIDGE,
  88                .hooknum        = NF_BR_POST_ROUTING,
  89                .priority       = NF_BR_PRI_NAT_SRC,
  90        },
  91        {
  92                .hook           = ebt_nat_in,
  93                .owner          = THIS_MODULE,
  94                .pf             = NFPROTO_BRIDGE,
  95                .hooknum        = NF_BR_PRE_ROUTING,
  96                .priority       = NF_BR_PRI_NAT_DST_BRIDGED,
  97        },
  98};
  99
 100static int __net_init frame_nat_net_init(struct net *net)
 101{
 102        net->xt.frame_nat = ebt_register_table(net, &frame_nat);
 103        if (IS_ERR(net->xt.frame_nat))
 104                return PTR_ERR(net->xt.frame_nat);
 105        return 0;
 106}
 107
 108static void __net_exit frame_nat_net_exit(struct net *net)
 109{
 110        ebt_unregister_table(net, net->xt.frame_nat);
 111}
 112
 113static struct pernet_operations frame_nat_net_ops = {
 114        .init = frame_nat_net_init,
 115        .exit = frame_nat_net_exit,
 116};
 117
 118static int __init ebtable_nat_init(void)
 119{
 120        int ret;
 121
 122        ret = register_pernet_subsys(&frame_nat_net_ops);
 123        if (ret < 0)
 124                return ret;
 125        ret = nf_register_hooks(ebt_ops_nat, ARRAY_SIZE(ebt_ops_nat));
 126        if (ret < 0)
 127                unregister_pernet_subsys(&frame_nat_net_ops);
 128        return ret;
 129}
 130
 131static void __exit ebtable_nat_fini(void)
 132{
 133        nf_unregister_hooks(ebt_ops_nat, ARRAY_SIZE(ebt_ops_nat));
 134        unregister_pernet_subsys(&frame_nat_net_ops);
 135}
 136
 137module_init(ebtable_nat_init);
 138module_exit(ebtable_nat_fini);
 139MODULE_LICENSE("GPL");
 140