net/bridge/netfilter/ebtable_filter.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  ebtable_filter
   4  *
   5  *      Authors:
   6  *      Bart De Schuymer <bdschuym@pandora.be>
   7  *
   8  *  April, 2002
   9  *
  10  */
  11
  12 #include <linux/netfilter_bridge/ebtables.h>
  13 #include <uapi/linux/netfilter_bridge.h>
  14 #include <linux/module.h>
  15
  16 #define FILTER_VALID_HOOKS ((1 << NF_BR_LOCAL_IN) | (1 << NF_BR_FORWARD) | \
  17                             (1 << NF_BR_LOCAL_OUT))
  18
  19 static struct ebt_entries initial_chains[] = {
  20         {
  21                 .name   = "INPUT",
  22                 .policy = EBT_ACCEPT,
  23         },
  24         {
  25                 .name   = "FORWARD",
  26                 .policy = EBT_ACCEPT,
  27         },
  28         {
  29                 .name   = "OUTPUT",
  30                 .policy = EBT_ACCEPT,
  31         },
  32 };
  33
  34 static struct ebt_replace_kernel initial_table = {
  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 const struct ebt_table frame_filter = {
  47         .name           = "filter",
  48         .table          = &initial_table,
  49         .valid_hooks    = FILTER_VALID_HOOKS,
  50         .me             = THIS_MODULE,
  51 };
  52
  53 static unsigned int
  54 ebt_filter_hook(void *priv, struct sk_buff *skb,
  55                 const struct nf_hook_state *state)
  56 {
  57         return ebt_do_table(skb, state, priv);
  58 }
  59
  60 static const struct nf_hook_ops ebt_ops_filter[] = {
  61         {
  62                 .hook           = ebt_filter_hook,
  63                 .pf             = NFPROTO_BRIDGE,
  64                 .hooknum        = NF_BR_LOCAL_IN,
  65                 .priority       = NF_BR_PRI_FILTER_BRIDGED,
  66         },
  67         {
  68                 .hook           = ebt_filter_hook,
  69                 .pf             = NFPROTO_BRIDGE,
  70                 .hooknum        = NF_BR_FORWARD,
  71                 .priority       = NF_BR_PRI_FILTER_BRIDGED,
  72         },
  73         {
  74                 .hook           = ebt_filter_hook,
  75                 .pf             = NFPROTO_BRIDGE,
  76                 .hooknum        = NF_BR_LOCAL_OUT,
  77                 .priority       = NF_BR_PRI_FILTER_OTHER,
  78         },
  79 };
  80
  81 static int frame_filter_table_init(struct net *net)
  82 {
  83         return ebt_register_table(net, &frame_filter, ebt_ops_filter);
  84 }
  85
  86 static void __net_exit frame_filter_net_pre_exit(struct net *net)
  87 {
  88         ebt_unregister_table_pre_exit(net, "filter");
  89 }
  90
  91 static void __net_exit frame_filter_net_exit(struct net *net)
  92 {
  93         ebt_unregister_table(net, "filter");
  94 }
  95
  96 static struct pernet_operations frame_filter_net_ops = {
  97         .exit = frame_filter_net_exit,
  98         .pre_exit = frame_filter_net_pre_exit,
  99 };
 100
 101 static int __init ebtable_filter_init(void)
 102 {
 103         int ret = ebt_register_template(&frame_filter, frame_filter_table_init);
 104
 105         if (ret)
 106                 return ret;
 107
 108         ret = register_pernet_subsys(&frame_filter_net_ops);
 109         if (ret) {
 110                 ebt_unregister_template(&frame_filter);
 111                 return ret;
 112         }
 113
 114         return 0;
 115 }
 116
 117 static void __exit ebtable_filter_fini(void)
 118 {
 119         unregister_pernet_subsys(&frame_filter_net_ops);
 120         ebt_unregister_template(&frame_filter);
 121 }
 122
 123 module_init(ebtable_filter_init);
 124 module_exit(ebtable_filter_fini);
 125 MODULE_LICENSE("GPL");