LXR linux/net/ipv4/netfilter/arptable

   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
  11MODULE_LICENSE("GPL");
  12MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
  13MODULE_DESCRIPTION("arptables filter table");
  14
  15#define FILTER_VALID_HOOKS ((1 << NF_ARP_IN) | (1 << NF_ARP_OUT) | \
  16                           (1 << NF_ARP_FORWARD))
  17
  18static 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
  48static 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 */
  56static 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
  66static 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
  76static 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
 100static 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
 110static void __net_exit arptable_filter_net_exit(struct net *net)
 111{
 112        arpt_unregister_table(net->ipv4.arptable_filter);
 113}
 114
 115static struct pernet_operations arptable_filter_net_ops = {
 116        .init = arptable_filter_net_init,
 117        .exit = arptable_filter_net_exit,
 118};
 119
 120static 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
 133cleanup_table:
 134        unregister_pernet_subsys(&arptable_filter_net_ops);
 135        return ret;
 136}
 137
 138static 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
 144module_init(arptable_filter_init);
 145module_exit(arptable_filter_fini);
 146