LXR linux/net/ipv4/netfilter/arptable

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Filtering ARP tables module.
   4 *
   5 * Copyright (C) 2002 David S. Miller (davem@redhat.com)
   6 *
   7 */
   8
   9#include <linux/module.h>
  10#include <linux/netfilter/x_tables.h>
  11#include <linux/netfilter_arp/arp_tables.h>
  12#include <linux/slab.h>
  13
  14MODULE_LICENSE("GPL");
  15MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
  16MODULE_DESCRIPTION("arptables filter table");
  17
  18#define FILTER_VALID_HOOKS ((1 << NF_ARP_IN) | (1 << NF_ARP_OUT) | \
  19                           (1 << NF_ARP_FORWARD))
  20
  21static int __net_init arptable_filter_table_init(struct net *net);
  22
  23static const struct xt_table packet_filter = {
  24        .name           = "filter",
  25        .valid_hooks    = FILTER_VALID_HOOKS,
  26        .me             = THIS_MODULE,
  27        .af             = NFPROTO_ARP,
  28        .priority       = NF_IP_PRI_FILTER,
  29        .table_init     = arptable_filter_table_init,
  30};
  31
  32/* The work comes in here from netfilter.c */
  33static unsigned int
  34arptable_filter_hook(void *priv, struct sk_buff *skb,
  35                     const struct nf_hook_state *state)
  36{
  37        return arpt_do_table(skb, state, state->net->ipv4.arptable_filter);
  38}
  39
  40static struct nf_hook_ops *arpfilter_ops __read_mostly;
  41
  42static int __net_init arptable_filter_table_init(struct net *net)
  43{
  44        struct arpt_replace *repl;
  45        int err;
  46
  47        if (net->ipv4.arptable_filter)
  48                return 0;
  49
  50        repl = arpt_alloc_initial_table(&packet_filter);
  51        if (repl == NULL)
  52                return -ENOMEM;
  53        err = arpt_register_table(net, &packet_filter, repl, arpfilter_ops,
  54                                  &net->ipv4.arptable_filter);
  55        kfree(repl);
  56        return err;
  57}
  58
  59static void __net_exit arptable_filter_net_exit(struct net *net)
  60{
  61        if (!net->ipv4.arptable_filter)
  62                return;
  63        arpt_unregister_table(net, net->ipv4.arptable_filter, arpfilter_ops);
  64        net->ipv4.arptable_filter = NULL;
  65}
  66
  67static struct pernet_operations arptable_filter_net_ops = {
  68        .exit = arptable_filter_net_exit,
  69};
  70
  71static int __init arptable_filter_init(void)
  72{
  73        int ret;
  74
  75        arpfilter_ops = xt_hook_ops_alloc(&packet_filter, arptable_filter_hook);
  76        if (IS_ERR(arpfilter_ops))
  77                return PTR_ERR(arpfilter_ops);
  78
  79        ret = register_pernet_subsys(&arptable_filter_net_ops);
  80        if (ret < 0) {
  81                kfree(arpfilter_ops);
  82                return ret;
  83        }
  84
  85        ret = arptable_filter_table_init(&init_net);
  86        if (ret) {
  87                unregister_pernet_subsys(&arptable_filter_net_ops);
  88                kfree(arpfilter_ops);
  89        }
  90
  91        return ret;
  92}
  93
  94static void __exit arptable_filter_fini(void)
  95{
  96        unregister_pernet_subsys(&arptable_filter_net_ops);
  97        kfree(arpfilter_ops);
  98}
  99
 100module_init(arptable_filter_init);
 101module_exit(arptable_filter_fini);
 102