net/ipv4/netfilter/arptable_filter.c

   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
  14 MODULE_LICENSE("GPL");
  15 MODULE_AUTHOR("David S. Miller <davem@redhat.com>");
  16 MODULE_DESCRIPTION("arptables filter table");
  17
  18 #define FILTER_VALID_HOOKS ((1 << NF_ARP_IN) | (1 << NF_ARP_OUT) | \
  19                            (1 << NF_ARP_FORWARD))
  20
  21 static const struct xt_table packet_filter = {
  22         .name           = "filter",
  23         .valid_hooks    = FILTER_VALID_HOOKS,
  24         .me             = THIS_MODULE,
  25         .af             = NFPROTO_ARP,
  26         .priority       = NF_IP_PRI_FILTER,
  27 };
  28
  29 static struct nf_hook_ops *arpfilter_ops __read_mostly;
  30
  31 static int arptable_filter_table_init(struct net *net)
  32 {
  33         struct arpt_replace *repl;
  34         int err;
  35
  36         repl = arpt_alloc_initial_table(&packet_filter);
  37         if (repl == NULL)
  38                 return -ENOMEM;
  39         err = arpt_register_table(net, &packet_filter, repl, arpfilter_ops);
  40         kfree(repl);
  41         return err;
  42 }
  43
  44 static void __net_exit arptable_filter_net_pre_exit(struct net *net)
  45 {
  46         arpt_unregister_table_pre_exit(net, "filter");
  47 }
  48
  49 static void __net_exit arptable_filter_net_exit(struct net *net)
  50 {
  51         arpt_unregister_table(net, "filter");
  52 }
  53
  54 static struct pernet_operations arptable_filter_net_ops = {
  55         .exit = arptable_filter_net_exit,
  56         .pre_exit = arptable_filter_net_pre_exit,
  57 };
  58
  59 static int __init arptable_filter_init(void)
  60 {
  61         int ret = xt_register_template(&packet_filter,
  62                                        arptable_filter_table_init);
  63
  64         if (ret < 0)
  65                 return ret;
  66
  67         arpfilter_ops = xt_hook_ops_alloc(&packet_filter, arpt_do_table);
  68         if (IS_ERR(arpfilter_ops)) {
  69                 xt_unregister_template(&packet_filter);
  70                 return PTR_ERR(arpfilter_ops);
  71         }
  72
  73         ret = register_pernet_subsys(&arptable_filter_net_ops);
  74         if (ret < 0) {
  75                 xt_unregister_template(&packet_filter);
  76                 kfree(arpfilter_ops);
  77                 return ret;
  78         }
  79
  80         return ret;
  81 }
  82
  83 static void __exit arptable_filter_fini(void)
  84 {
  85         unregister_pernet_subsys(&arptable_filter_net_ops);
  86         xt_unregister_template(&packet_filter);
  87         kfree(arpfilter_ops);
  88 }
  89
  90 module_init(arptable_filter_init);
  91 module_exit(arptable_filter_fini);