net/ipv6/netfilter/ip6table_filter.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
   4  *
   5  * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
   6  * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/moduleparam.h>
  11 #include <linux/netfilter_ipv6/ip6_tables.h>
  12 #include <linux/slab.h>
  13
  14 MODULE_LICENSE("GPL");
  15 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  16 MODULE_DESCRIPTION("ip6tables filter table");
  17
  18 #define FILTER_VALID_HOOKS ((1 << NF_INET_LOCAL_IN) | \
  19                             (1 << NF_INET_FORWARD) | \
  20                             (1 << NF_INET_LOCAL_OUT))
  21
  22 static const struct xt_table packet_filter = {
  23         .name           = "filter",
  24         .valid_hooks    = FILTER_VALID_HOOKS,
  25         .me             = THIS_MODULE,
  26         .af             = NFPROTO_IPV6,
  27         .priority       = NF_IP6_PRI_FILTER,
  28 };
  29
  30 /* The work comes in here from netfilter.c. */
  31 static unsigned int
  32 ip6table_filter_hook(void *priv, struct sk_buff *skb,
  33                      const struct nf_hook_state *state)
  34 {
  35         return ip6t_do_table(skb, state, priv);
  36 }
  37
  38 static struct nf_hook_ops *filter_ops __read_mostly;
  39
  40 /* Default to forward because I got too much mail already. */
  41 static bool forward = true;
  42 module_param(forward, bool, 0000);
  43
  44 static int ip6table_filter_table_init(struct net *net)
  45 {
  46         struct ip6t_replace *repl;
  47         int err;
  48
  49         repl = ip6t_alloc_initial_table(&packet_filter);
  50         if (repl == NULL)
  51                 return -ENOMEM;
  52         /* Entry 1 is the FORWARD hook */
  53         ((struct ip6t_standard *)repl->entries)[1].target.verdict =
  54                 forward ? -NF_ACCEPT - 1 : -NF_DROP - 1;
  55
  56         err = ip6t_register_table(net, &packet_filter, repl, filter_ops);
  57         kfree(repl);
  58         return err;
  59 }
  60
  61 static int __net_init ip6table_filter_net_init(struct net *net)
  62 {
  63         if (!forward)
  64                 return ip6table_filter_table_init(net);
  65
  66         return 0;
  67 }
  68
  69 static void __net_exit ip6table_filter_net_pre_exit(struct net *net)
  70 {
  71         ip6t_unregister_table_pre_exit(net, "filter");
  72 }
  73
  74 static void __net_exit ip6table_filter_net_exit(struct net *net)
  75 {
  76         ip6t_unregister_table_exit(net, "filter");
  77 }
  78
  79 static struct pernet_operations ip6table_filter_net_ops = {
  80         .init = ip6table_filter_net_init,
  81         .pre_exit = ip6table_filter_net_pre_exit,
  82         .exit = ip6table_filter_net_exit,
  83 };
  84
  85 static int __init ip6table_filter_init(void)
  86 {
  87         int ret = xt_register_template(&packet_filter,
  88                                         ip6table_filter_table_init);
  89
  90         if (ret < 0)
  91                 return ret;
  92
  93         filter_ops = xt_hook_ops_alloc(&packet_filter, ip6table_filter_hook);
  94         if (IS_ERR(filter_ops)) {
  95                 xt_unregister_template(&packet_filter);
  96                 return PTR_ERR(filter_ops);
  97         }
  98
  99         ret = register_pernet_subsys(&ip6table_filter_net_ops);
 100         if (ret < 0) {
 101                 xt_unregister_template(&packet_filter);
 102                 kfree(filter_ops);
 103                 return ret;
 104         }
 105
 106         return ret;
 107 }
 108
 109 static void __exit ip6table_filter_fini(void)
 110 {
 111         unregister_pernet_subsys(&ip6table_filter_net_ops);
 112         xt_unregister_template(&packet_filter);
 113         kfree(filter_ops);
 114 }
 115
 116 module_init(ip6table_filter_init);
 117 module_exit(ip6table_filter_fini);