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/x_tables.h>
  10#include <linux/netfilter_arp/arp_tables.h>
  11#include <linux/slab.h>
  12
  13MODULE_LICENSE("GPL");
  14MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
  15MODULE_DESCRIPTION("arptables filter table");
  16
  17#define FILTER_VALID_HOOKS ((1 << NF_ARP_IN) | (1 << NF_ARP_OUT) | \
  18                           (1 << NF_ARP_FORWARD))
  19
  20static int __net_init arptable_filter_table_init(struct net *net);
  21
  22static const struct xt_table packet_filter = {
  23        .name           = "filter",
  24        .valid_hooks    = FILTER_VALID_HOOKS,
  25        .me             = THIS_MODULE,
  26        .af             = NFPROTO_ARP,
  27        .priority       = NF_IP_PRI_FILTER,
  28        .table_init     = arptable_filter_table_init,
  29};
  30
  31/* The work comes in here from netfilter.c */
  32static unsigned int
  33arptable_filter_hook(void *priv, struct sk_buff *skb,
  34                     const struct nf_hook_state *state)
  35{
  36        return arpt_do_table(skb, state, state->net->ipv4.arptable_filter);
  37}
  38
  39static struct nf_hook_ops *arpfilter_ops __read_mostly;
  40
  41static int __net_init arptable_filter_table_init(struct net *net)
  42{
  43        struct arpt_replace *repl;
  44        int err;
  45
  46        if (net->ipv4.arptable_filter)
  47                return 0;
  48
  49        repl = arpt_alloc_initial_table(&packet_filter);
  50        if (repl == NULL)
  51                return -ENOMEM;
  52        err = arpt_register_table(net, &packet_filter, repl, arpfilter_ops,
  53                                  &net->ipv4.arptable_filter);
  54        kfree(repl);
  55        return err;
  56}
  57
  58static void __net_exit arptable_filter_net_exit(struct net *net)
  59{
  60        if (!net->ipv4.arptable_filter)
  61                return;
  62        arpt_unregister_table(net, net->ipv4.arptable_filter, arpfilter_ops);
  63        net->ipv4.arptable_filter = NULL;
  64}
  65
  66static struct pernet_operations arptable_filter_net_ops = {
  67        .exit = arptable_filter_net_exit,
  68};
  69
  70static int __init arptable_filter_init(void)
  71{
  72        int ret;
  73
  74        arpfilter_ops = xt_hook_ops_alloc(&packet_filter, arptable_filter_hook);
  75        if (IS_ERR(arpfilter_ops))
  76                return PTR_ERR(arpfilter_ops);
  77
  78        ret = register_pernet_subsys(&arptable_filter_net_ops);
  79        if (ret < 0) {
  80                kfree(arpfilter_ops);
  81                return ret;
  82        }
  83
  84        ret = arptable_filter_table_init(&init_net);
  85        if (ret) {
  86                unregister_pernet_subsys(&arptable_filter_net_ops);
  87                kfree(arpfilter_ops);
  88        }
  89
  90        return ret;
  91}
  92
  93static void __exit arptable_filter_fini(void)
  94{
  95        unregister_pernet_subsys(&arptable_filter_net_ops);
  96        kfree(arpfilter_ops);
  97}
  98
  99module_init(arptable_filter_init);
 100module_exit(arptable_filter_fini);
 101