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 <[email protected]>
   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 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         .name           = "filter",
  55         .table          = &initial_table,
  56         .valid_hooks    = FILTER_VALID_HOOKS,
  57         .check          = check,
  58         .me             = THIS_MODULE,
  59 };
  60
  61 static unsigned int
  62 ebt_filter_hook(void *priv, struct sk_buff *skb,
  63                 const struct nf_hook_state *state)
  64 {
  65         return ebt_do_table(skb, state, priv);
  66 }
  67
  68 static const struct nf_hook_ops ebt_ops_filter[] = {
  69         {
  70                 .hook           = ebt_filter_hook,
  71                 .pf             = NFPROTO_BRIDGE,
  72                 .hooknum        = NF_BR_LOCAL_IN,
  73                 .priority       = NF_BR_PRI_FILTER_BRIDGED,
  74         },
  75         {
  76                 .hook           = ebt_filter_hook,
  77                 .pf             = NFPROTO_BRIDGE,
  78                 .hooknum        = NF_BR_FORWARD,
  79                 .priority       = NF_BR_PRI_FILTER_BRIDGED,
  80         },
  81         {
  82                 .hook           = ebt_filter_hook,
  83                 .pf             = NFPROTO_BRIDGE,
  84                 .hooknum        = NF_BR_LOCAL_OUT,
  85                 .priority       = NF_BR_PRI_FILTER_OTHER,
  86         },
  87 };
  88
  89 static int __net_init frame_filter_net_init(struct net *net)
  90 {
  91         return ebt_register_table(net, &frame_filter, ebt_ops_filter);
  92 }
  93
  94 static void __net_exit frame_filter_net_pre_exit(struct net *net)
  95 {
  96         ebt_unregister_table_pre_exit(net, "filter");
  97 }
  98
  99 static void __net_exit frame_filter_net_exit(struct net *net)
 100 {
 101         ebt_unregister_table(net, "filter");
 102 }
 103
 104 static struct pernet_operations frame_filter_net_ops = {
 105         .init = frame_filter_net_init,
 106         .exit = frame_filter_net_exit,
 107         .pre_exit = frame_filter_net_pre_exit,
 108 };
 109
 110 static int __init ebtable_filter_init(void)
 111 {
 112         return register_pernet_subsys(&frame_filter_net_ops);
 113 }
 114
 115 static void __exit ebtable_filter_fini(void)
 116 {
 117         unregister_pernet_subsys(&frame_filter_net_ops);
 118 }
 119
 120 module_init(ebtable_filter_init);
 121 module_exit(ebtable_filter_fini);
 122 MODULE_LICENSE("GPL");