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         {
  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
  33 static 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
  46 static 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
  53 static 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
  62 static unsigned int
  63 ebt_in_hook(const struct nf_hook_ops *ops, struct sk_buff *skb,
  64             const struct net_device *in, const struct net_device *out,
  65             int (*okfn)(struct sk_buff *))
  66 {
  67         return ebt_do_table(ops->hooknum, skb, in, out,
  68                             dev_net(in)->xt.frame_filter);
  69 }
  70
  71 static unsigned int
  72 ebt_out_hook(const struct nf_hook_ops *ops, struct sk_buff *skb,
  73              const struct net_device *in, const struct net_device *out,
  74              int (*okfn)(struct sk_buff *))
  75 {
  76         return ebt_do_table(ops->hooknum, skb, in, out,
  77                             dev_net(out)->xt.frame_filter);
  78 }
  79
  80 static struct nf_hook_ops ebt_ops_filter[] __read_mostly = {
  81         {
  82                 .hook           = ebt_in_hook,
  83                 .owner          = THIS_MODULE,
  84                 .pf             = NFPROTO_BRIDGE,
  85                 .hooknum        = NF_BR_LOCAL_IN,
  86                 .priority       = NF_BR_PRI_FILTER_BRIDGED,
  87         },
  88         {
  89                 .hook           = ebt_in_hook,
  90                 .owner          = THIS_MODULE,
  91                 .pf             = NFPROTO_BRIDGE,
  92                 .hooknum        = NF_BR_FORWARD,
  93                 .priority       = NF_BR_PRI_FILTER_BRIDGED,
  94         },
  95         {
  96                 .hook           = ebt_out_hook,
  97                 .owner          = THIS_MODULE,
  98                 .pf             = NFPROTO_BRIDGE,
  99                 .hooknum        = NF_BR_LOCAL_OUT,
 100                 .priority       = NF_BR_PRI_FILTER_OTHER,
 101         },
 102 };
 103
 104 static int __net_init frame_filter_net_init(struct net *net)
 105 {
 106         net->xt.frame_filter = ebt_register_table(net, &frame_filter);
 107         return PTR_ERR_OR_ZERO(net->xt.frame_filter);
 108 }
 109
 110 static void __net_exit frame_filter_net_exit(struct net *net)
 111 {
 112         ebt_unregister_table(net, net->xt.frame_filter);
 113 }
 114
 115 static struct pernet_operations frame_filter_net_ops = {
 116         .init = frame_filter_net_init,
 117         .exit = frame_filter_net_exit,
 118 };
 119
 120 static int __init ebtable_filter_init(void)
 121 {
 122         int ret;
 123
 124         ret = register_pernet_subsys(&frame_filter_net_ops);
 125         if (ret < 0)
 126                 return ret;
 127         ret = nf_register_hooks(ebt_ops_filter, ARRAY_SIZE(ebt_ops_filter));
 128         if (ret < 0)
 129                 unregister_pernet_subsys(&frame_filter_net_ops);
 130         return ret;
 131 }
 132
 133 static void __exit ebtable_filter_fini(void)
 134 {
 135         nf_unregister_hooks(ebt_ops_filter, ARRAY_SIZE(ebt_ops_filter));
 136         unregister_pernet_subsys(&frame_filter_net_ops);
 137 }
 138
 139 module_init(ebtable_filter_init);
 140 module_exit(ebtable_filter_fini);
 141 MODULE_LICENSE("GPL");