net/bridge/netfilter/ebtable_filter.c

   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
  17 static struct ebt_entries initial_chains[] = {
  18         {
  19                 .name   = "INPUT",
  20                 .policy = EBT_ACCEPT,
  21         },
  22         {
  23                 .name   = "FORWARD",
  24                 .policy = EBT_ACCEPT,
  25         },
  26         {
  27                 .name   = "OUTPUT",
  28                 .policy = EBT_ACCEPT,
  29         },
  30 };
  31
  32 static struct ebt_replace_kernel initial_table = {
  33         .name           = "filter",
  34         .valid_hooks    = FILTER_VALID_HOOKS,
  35         .entries_size   = 3 * sizeof(struct ebt_entries),
  36         .hook_entry     = {
  37                 [NF_BR_LOCAL_IN]        = &initial_chains[0],
  38                 [NF_BR_FORWARD]         = &initial_chains[1],
  39                 [NF_BR_LOCAL_OUT]       = &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 & ~FILTER_VALID_HOOKS)
  47                 return -EINVAL;
  48         return 0;
  49 }
  50
  51 static const struct ebt_table frame_filter = {
  52         .name           = "filter",
  53         .table          = &initial_table,
  54         .valid_hooks    = FILTER_VALID_HOOKS,
  55         .check          = check,
  56         .me             = THIS_MODULE,
  57 };
  58
  59 static unsigned int
  60 ebt_in_hook(const struct nf_hook_ops *ops, struct sk_buff *skb,
  61             const struct net_device *in, const struct net_device *out,
  62             int (*okfn)(struct sk_buff *))
  63 {
  64         return ebt_do_table(ops->hooknum, skb, in, out,
  65                             dev_net(in)->xt.frame_filter);
  66 }
  67
  68 static unsigned int
  69 ebt_out_hook(const struct nf_hook_ops *ops, struct sk_buff *skb,
  70              const struct net_device *in, const struct net_device *out,
  71              int (*okfn)(struct sk_buff *))
  72 {
  73         return ebt_do_table(ops->hooknum, skb, in, out,
  74                             dev_net(out)->xt.frame_filter);
  75 }
  76
  77 static struct nf_hook_ops ebt_ops_filter[] __read_mostly = {
  78         {
  79                 .hook           = ebt_in_hook,
  80                 .owner          = THIS_MODULE,
  81                 .pf             = NFPROTO_BRIDGE,
  82                 .hooknum        = NF_BR_LOCAL_IN,
  83                 .priority       = NF_BR_PRI_FILTER_BRIDGED,
  84         },
  85         {
  86                 .hook           = ebt_in_hook,
  87                 .owner          = THIS_MODULE,
  88                 .pf             = NFPROTO_BRIDGE,
  89                 .hooknum        = NF_BR_FORWARD,
  90                 .priority       = NF_BR_PRI_FILTER_BRIDGED,
  91         },
  92         {
  93                 .hook           = ebt_out_hook,
  94                 .owner          = THIS_MODULE,
  95                 .pf             = NFPROTO_BRIDGE,
  96                 .hooknum        = NF_BR_LOCAL_OUT,
  97                 .priority       = NF_BR_PRI_FILTER_OTHER,
  98         },
  99 };
 100
 101 static int __net_init frame_filter_net_init(struct net *net)
 102 {
 103         net->xt.frame_filter = ebt_register_table(net, &frame_filter);
 104         return PTR_ERR_OR_ZERO(net->xt.frame_filter);
 105 }
 106
 107 static void __net_exit frame_filter_net_exit(struct net *net)
 108 {
 109         ebt_unregister_table(net, net->xt.frame_filter);
 110 }
 111
 112 static struct pernet_operations frame_filter_net_ops = {
 113         .init = frame_filter_net_init,
 114         .exit = frame_filter_net_exit,
 115 };
 116
 117 static int __init ebtable_filter_init(void)
 118 {
 119         int ret;
 120
 121         ret = register_pernet_subsys(&frame_filter_net_ops);
 122         if (ret < 0)
 123                 return ret;
 124         ret = nf_register_hooks(ebt_ops_filter, ARRAY_SIZE(ebt_ops_filter));
 125         if (ret < 0)
 126                 unregister_pernet_subsys(&frame_filter_net_ops);
 127         return ret;
 128 }
 129
 130 static void __exit ebtable_filter_fini(void)
 131 {
 132         nf_unregister_hooks(ebt_ops_filter, ARRAY_SIZE(ebt_ops_filter));
 133         unregister_pernet_subsys(&frame_filter_net_ops);
 134 }
 135
 136 module_init(ebtable_filter_init);
 137 module_exit(ebtable_filter_fini);
 138 MODULE_LICENSE("GPL");