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   1 /*
   2  * Filtering ARP tables module.
   3  *
   4  * Copyright (C) 2002 David S. Miller (davem@redhat.com)
   5  *
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/netfilter_arp/arp_tables.h>
  10
  11 MODULE_LICENSE("GPL");
  12 MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
  13 MODULE_DESCRIPTION("arptables filter table");
  14
  15 #define FILTER_VALID_HOOKS ((1 << NF_ARP_IN) | (1 << NF_ARP_OUT) | \
  16                            (1 << NF_ARP_FORWARD))
  17
  18 static struct
  19 {
  20         struct arpt_replace repl;
  21         struct arpt_standard entries[3];
  22         struct arpt_error term;
  23 } initial_table __net_initdata = {
  24         .repl = {
  25                 .name = "filter",
  26                 .valid_hooks = FILTER_VALID_HOOKS,
  27                 .num_entries = 4,
  28                 .size = sizeof(struct arpt_standard) * 3 + sizeof(struct arpt_error),
  29                 .hook_entry = {
  30                         [NF_ARP_IN] = 0,
  31                         [NF_ARP_OUT] = sizeof(struct arpt_standard),
  32                         [NF_ARP_FORWARD] = 2 * sizeof(struct arpt_standard),
  33                 },
  34                 .underflow = {
  35                         [NF_ARP_IN] = 0,
  36                         [NF_ARP_OUT] = sizeof(struct arpt_standard),
  37                         [NF_ARP_FORWARD] = 2 * sizeof(struct arpt_standard),
  38                 },
  39         },
  40         .entries = {
  41                 ARPT_STANDARD_INIT(NF_ACCEPT),  /* ARP_IN */
  42                 ARPT_STANDARD_INIT(NF_ACCEPT),  /* ARP_OUT */
  43                 ARPT_STANDARD_INIT(NF_ACCEPT),  /* ARP_FORWARD */
  44         },
  45         .term = ARPT_ERROR_INIT,
  46 };
  47
  48 static struct arpt_table packet_filter = {
  49         .name           = "filter",
  50         .valid_hooks    = FILTER_VALID_HOOKS,
  51         .lock           = RW_LOCK_UNLOCKED,
  52         .private        = NULL,
  53         .me             = THIS_MODULE,
  54         .af             = NF_ARP,
  55 };
  56
  57 /* The work comes in here from netfilter.c */
  58 static unsigned int arpt_hook(unsigned int hook,
  59                               struct sk_buff *skb,
  60                               const struct net_device *in,
  61                               const struct net_device *out,
  62                               int (*okfn)(struct sk_buff *))
  63 {
  64         return arpt_do_table(skb, hook, in, out, init_net.ipv4.arptable_filter);
  65 }
  66
  67 static struct nf_hook_ops arpt_ops[] __read_mostly = {
  68         {
  69                 .hook           = arpt_hook,
  70                 .owner          = THIS_MODULE,
  71                 .pf             = NF_ARP,
  72                 .hooknum        = NF_ARP_IN,
  73         },
  74         {
  75                 .hook           = arpt_hook,
  76                 .owner          = THIS_MODULE,
  77                 .pf             = NF_ARP,
  78                 .hooknum        = NF_ARP_OUT,
  79         },
  80         {
  81                 .hook           = arpt_hook,
  82                 .owner          = THIS_MODULE,
  83                 .pf             = NF_ARP,
  84                 .hooknum        = NF_ARP_FORWARD,
  85         },
  86 };
  87
  88 static int __net_init arptable_filter_net_init(struct net *net)
  89 {
  90         /* Register table */
  91         net->ipv4.arptable_filter =
  92                 arpt_register_table(net, &packet_filter, &initial_table.repl);
  93         if (IS_ERR(net->ipv4.arptable_filter))
  94                 return PTR_ERR(net->ipv4.arptable_filter);
  95         return 0;
  96 }
  97
  98 static void __net_exit arptable_filter_net_exit(struct net *net)
  99 {
 100         arpt_unregister_table(net->ipv4.arptable_filter);
 101 }
 102
 103 static struct pernet_operations arptable_filter_net_ops = {
 104         .init = arptable_filter_net_init,
 105         .exit = arptable_filter_net_exit,
 106 };
 107
 108 static int __init arptable_filter_init(void)
 109 {
 110         int ret;
 111
 112         ret = register_pernet_subsys(&arptable_filter_net_ops);
 113         if (ret < 0)
 114                 return ret;
 115
 116         ret = nf_register_hooks(arpt_ops, ARRAY_SIZE(arpt_ops));
 117         if (ret < 0)
 118                 goto cleanup_table;
 119         return ret;
 120
 121 cleanup_table:
 122         unregister_pernet_subsys(&arptable_filter_net_ops);
 123         return ret;
 124 }
 125
 126 static void __exit arptable_filter_fini(void)
 127 {
 128         nf_unregister_hooks(arpt_ops, ARRAY_SIZE(arpt_ops));
 129         unregister_pernet_subsys(&arptable_filter_net_ops);
 130 }
 131
 132 module_init(arptable_filter_init);
 133 module_exit(arptable_filter_fini);