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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 const 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 const struct xt_table packet_filter = {
  49         .name           = "filter",
  50         .valid_hooks    = FILTER_VALID_HOOKS,
  51         .me             = THIS_MODULE,
  52         .af             = NFPROTO_ARP,
  53 };
  54
  55 /* The work comes in here from netfilter.c */
  56 static unsigned int arpt_in_hook(unsigned int hook,
  57                                  struct sk_buff *skb,
  58                                  const struct net_device *in,
  59                                  const struct net_device *out,
  60                                  int (*okfn)(struct sk_buff *))
  61 {
  62         return arpt_do_table(skb, hook, in, out,
  63                              dev_net(in)->ipv4.arptable_filter);
  64 }
  65
  66 static unsigned int arpt_out_hook(unsigned int hook,
  67                                   struct sk_buff *skb,
  68                                   const struct net_device *in,
  69                                   const struct net_device *out,
  70                                   int (*okfn)(struct sk_buff *))
  71 {
  72         return arpt_do_table(skb, hook, in, out,
  73                              dev_net(out)->ipv4.arptable_filter);
  74 }
  75
  76 static struct nf_hook_ops arpt_ops[] __read_mostly = {
  77         {
  78                 .hook           = arpt_in_hook,
  79                 .owner          = THIS_MODULE,
  80                 .pf             = NFPROTO_ARP,
  81                 .hooknum        = NF_ARP_IN,
  82                 .priority       = NF_IP_PRI_FILTER,
  83         },
  84         {
  85                 .hook           = arpt_out_hook,
  86                 .owner          = THIS_MODULE,
  87                 .pf             = NFPROTO_ARP,
  88                 .hooknum        = NF_ARP_OUT,
  89                 .priority       = NF_IP_PRI_FILTER,
  90         },
  91         {
  92                 .hook           = arpt_in_hook,
  93                 .owner          = THIS_MODULE,
  94                 .pf             = NFPROTO_ARP,
  95                 .hooknum        = NF_ARP_FORWARD,
  96                 .priority       = NF_IP_PRI_FILTER,
  97         },
  98 };
  99
 100 static int __net_init arptable_filter_net_init(struct net *net)
 101 {
 102         /* Register table */
 103         net->ipv4.arptable_filter =
 104                 arpt_register_table(net, &packet_filter, &initial_table.repl);
 105         if (IS_ERR(net->ipv4.arptable_filter))
 106                 return PTR_ERR(net->ipv4.arptable_filter);
 107         return 0;
 108 }
 109
 110 static void __net_exit arptable_filter_net_exit(struct net *net)
 111 {
 112         arpt_unregister_table(net->ipv4.arptable_filter);
 113 }
 114
 115 static struct pernet_operations arptable_filter_net_ops = {
 116         .init = arptable_filter_net_init,
 117         .exit = arptable_filter_net_exit,
 118 };
 119
 120 static int __init arptable_filter_init(void)
 121 {
 122         int ret;
 123
 124         ret = register_pernet_subsys(&arptable_filter_net_ops);
 125         if (ret < 0)
 126                 return ret;
 127
 128         ret = nf_register_hooks(arpt_ops, ARRAY_SIZE(arpt_ops));
 129         if (ret < 0)
 130                 goto cleanup_table;
 131         return ret;
 132
 133 cleanup_table:
 134         unregister_pernet_subsys(&arptable_filter_net_ops);
 135         return ret;
 136 }
 137
 138 static void __exit arptable_filter_fini(void)
 139 {
 140         nf_unregister_hooks(arpt_ops, ARRAY_SIZE(arpt_ops));
 141         unregister_pernet_subsys(&arptable_filter_net_ops);
 142 }
 143
 144 module_init(arptable_filter_init);
 145 module_exit(arptable_filter_fini);