linux/net/bridge/netfilter/ebtable_filter.c
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   1/*
   2 *  ebtable_filter
   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 FILTER_VALID_HOOKS ((1 << NF_BR_LOCAL_IN) | (1 << NF_BR_FORWARD) | \
  15   (1 << NF_BR_LOCAL_OUT))
  16
  17static struct ebt_entries initial_chains[] =
  18{
  19        {
  20                .name   = "INPUT",
  21                .policy = EBT_ACCEPT,
  22        },
  23        {
  24                .name   = "FORWARD",
  25                .policy = EBT_ACCEPT,
  26        },
  27        {
  28                .name   = "OUTPUT",
  29                .policy = EBT_ACCEPT,
  30        },
  31};
  32
  33static struct ebt_replace_kernel initial_table =
  34{
  35        .name           = "filter",
  36        .valid_hooks    = FILTER_VALID_HOOKS,
  37        .entries_size   = 3 * sizeof(struct ebt_entries),
  38        .hook_entry     = {
  39                [NF_BR_LOCAL_IN]        = &initial_chains[0],
  40                [NF_BR_FORWARD]         = &initial_chains[1],
  41                [NF_BR_LOCAL_OUT]       = &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 & ~FILTER_VALID_HOOKS)
  49                return -EINVAL;
  50        return 0;
  51}
  52
  53static const struct ebt_table frame_filter =
  54{
  55        .name           = "filter",
  56        .table          = &initial_table,
  57        .valid_hooks    = FILTER_VALID_HOOKS,
  58        .check          = check,
  59        .me             = THIS_MODULE,
  60};
  61
  62static unsigned int
  63ebt_in_hook(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_filter);
  67}
  68
  69static unsigned int
  70ebt_out_hook(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_filter);
  74}
  75
  76static struct nf_hook_ops ebt_ops_filter[] __read_mostly = {
  77        {
  78                .hook           = ebt_in_hook,
  79                .owner          = THIS_MODULE,
  80                .pf             = NFPROTO_BRIDGE,
  81                .hooknum        = NF_BR_LOCAL_IN,
  82                .priority       = NF_BR_PRI_FILTER_BRIDGED,
  83        },
  84        {
  85                .hook           = ebt_in_hook,
  86                .owner          = THIS_MODULE,
  87                .pf             = NFPROTO_BRIDGE,
  88                .hooknum        = NF_BR_FORWARD,
  89                .priority       = NF_BR_PRI_FILTER_BRIDGED,
  90        },
  91        {
  92                .hook           = ebt_out_hook,
  93                .owner          = THIS_MODULE,
  94                .pf             = NFPROTO_BRIDGE,
  95                .hooknum        = NF_BR_LOCAL_OUT,
  96                .priority       = NF_BR_PRI_FILTER_OTHER,
  97        },
  98};
  99
 100static int __net_init frame_filter_net_init(struct net *net)
 101{
 102        net->xt.frame_filter = ebt_register_table(net, &frame_filter);
 103        return PTR_RET(net->xt.frame_filter);
 104}
 105
 106static void __net_exit frame_filter_net_exit(struct net *net)
 107{
 108        ebt_unregister_table(net, net->xt.frame_filter);
 109}
 110
 111static struct pernet_operations frame_filter_net_ops = {
 112        .init = frame_filter_net_init,
 113        .exit = frame_filter_net_exit,
 114};
 115
 116static int __init ebtable_filter_init(void)
 117{
 118        int ret;
 119
 120        ret = register_pernet_subsys(&frame_filter_net_ops);
 121        if (ret < 0)
 122                return ret;
 123        ret = nf_register_hooks(ebt_ops_filter, ARRAY_SIZE(ebt_ops_filter));
 124        if (ret < 0)
 125                unregister_pernet_subsys(&frame_filter_net_ops);
 126        return ret;
 127}
 128
 129static void __exit ebtable_filter_fini(void)
 130{
 131        nf_unregister_hooks(ebt_ops_filter, ARRAY_SIZE(ebt_ops_filter));
 132        unregister_pernet_subsys(&frame_filter_net_ops);
 133}
 134
 135module_init(ebtable_filter_init);
 136module_exit(ebtable_filter_fini);
 137MODULE_LICENSE("GPL");
 138