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 const struct xt_table packet_filter = {
  21        .name           = "filter",
  22        .valid_hooks    = FILTER_VALID_HOOKS,
  23        .me             = THIS_MODULE,
  24        .af             = NFPROTO_ARP,
  25        .priority       = NF_IP_PRI_FILTER,
  26};
  27
  28/* The work comes in here from netfilter.c */
  29static unsigned int
  30arptable_filter_hook(unsigned int hook, struct sk_buff *skb,
  31                     const struct net_device *in, const struct net_device *out,
  32                     int (*okfn)(struct sk_buff *))
  33{
  34        const struct net *net = dev_net((in != NULL) ? in : out);
  35
  36        return arpt_do_table(skb, hook, in, out, net->ipv4.arptable_filter);
  37}
  38
  39static struct nf_hook_ops *arpfilter_ops __read_mostly;
  40
  41static int __net_init arptable_filter_net_init(struct net *net)
  42{
  43        struct arpt_replace *repl;
  44        
  45        repl = arpt_alloc_initial_table(&packet_filter);
  46        if (repl == NULL)
  47                return -ENOMEM;
  48        net->ipv4.arptable_filter =
  49                arpt_register_table(net, &packet_filter, repl);
  50        kfree(repl);
  51        return PTR_RET(net->ipv4.arptable_filter);
  52}
  53
  54static void __net_exit arptable_filter_net_exit(struct net *net)
  55{
  56        arpt_unregister_table(net->ipv4.arptable_filter);
  57}
  58
  59static struct pernet_operations arptable_filter_net_ops = {
  60        .init = arptable_filter_net_init,
  61        .exit = arptable_filter_net_exit,
  62};
  63
  64static int __init arptable_filter_init(void)
  65{
  66        int ret;
  67
  68        ret = register_pernet_subsys(&arptable_filter_net_ops);
  69        if (ret < 0)
  70                return ret;
  71
  72        arpfilter_ops = xt_hook_link(&packet_filter, arptable_filter_hook);
  73        if (IS_ERR(arpfilter_ops)) {
  74                ret = PTR_ERR(arpfilter_ops);
  75                goto cleanup_table;
  76        }
  77        return ret;
  78
  79cleanup_table:
  80        unregister_pernet_subsys(&arptable_filter_net_ops);
  81        return ret;
  82}
  83
  84static void __exit arptable_filter_fini(void)
  85{
  86        xt_hook_unlink(&packet_filter, arpfilter_ops);
  87        unregister_pernet_subsys(&arptable_filter_net_ops);
  88}
  89
  90module_init(arptable_filter_init);
  91module_exit(arptable_filter_fini);
  92