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                .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
  32static 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
  44static 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
  51static 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
  59static unsigned int
  60ebt_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
  67static unsigned int
  68ebt_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
  75static 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
  99static 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
 105static void __net_exit frame_nat_net_exit(struct net *net)
 106{
 107        ebt_unregister_table(net, net->xt.frame_nat);
 108}
 109
 110static struct pernet_operations frame_nat_net_ops = {
 111        .init = frame_nat_net_init,
 112        .exit = frame_nat_net_exit,
 113};
 114
 115static 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
 128static 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
 134module_init(ebtable_nat_init);
 135module_exit(ebtable_nat_fini);
 136MODULE_LICENSE("GPL");
 137