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 int __net_init ip6table_filter_table_init(struct net *net);
  23
  24 static const struct xt_table packet_filter = {
  25         .name           = "filter",
  26         .valid_hooks    = FILTER_VALID_HOOKS,
  27         .me             = THIS_MODULE,
  28         .af             = NFPROTO_IPV6,
  29         .priority       = NF_IP6_PRI_FILTER,
  30         .table_init     = ip6table_filter_table_init,
  31 };
  32
  33 /* The work comes in here from netfilter.c. */
  34 static unsigned int
  35 ip6table_filter_hook(void *priv, struct sk_buff *skb,
  36                      const struct nf_hook_state *state)
  37 {
  38         return ip6t_do_table(skb, state, state->net->ipv6.ip6table_filter);
  39 }
  40
  41 static struct nf_hook_ops *filter_ops __read_mostly;
  42
  43 /* Default to forward because I got too much mail already. */
  44 static bool forward = true;
  45 module_param(forward, bool, 0000);
  46
  47 static int __net_init ip6table_filter_table_init(struct net *net)
  48 {
  49         struct ip6t_replace *repl;
  50         int err;
  51
  52         if (net->ipv6.ip6table_filter)
  53                 return 0;
  54
  55         repl = ip6t_alloc_initial_table(&packet_filter);
  56         if (repl == NULL)
  57                 return -ENOMEM;
  58         /* Entry 1 is the FORWARD hook */
  59         ((struct ip6t_standard *)repl->entries)[1].target.verdict =
  60                 forward ? -NF_ACCEPT - 1 : -NF_DROP - 1;
  61
  62         err = ip6t_register_table(net, &packet_filter, repl, filter_ops,
  63                                   &net->ipv6.ip6table_filter);
  64         kfree(repl);
  65         return err;
  66 }
  67
  68 static int __net_init ip6table_filter_net_init(struct net *net)
  69 {
  70         if (net == &init_net || !forward)
  71                 return ip6table_filter_table_init(net);
  72
  73         return 0;
  74 }
  75
  76 static void __net_exit ip6table_filter_net_pre_exit(struct net *net)
  77 {
  78         if (net->ipv6.ip6table_filter)
  79                 ip6t_unregister_table_pre_exit(net, net->ipv6.ip6table_filter,
  80                                                filter_ops);
  81 }
  82
  83 static void __net_exit ip6table_filter_net_exit(struct net *net)
  84 {
  85         if (!net->ipv6.ip6table_filter)
  86                 return;
  87         ip6t_unregister_table_exit(net, net->ipv6.ip6table_filter);
  88         net->ipv6.ip6table_filter = NULL;
  89 }
  90
  91 static struct pernet_operations ip6table_filter_net_ops = {
  92         .init = ip6table_filter_net_init,
  93         .pre_exit = ip6table_filter_net_pre_exit,
  94         .exit = ip6table_filter_net_exit,
  95 };
  96
  97 static int __init ip6table_filter_init(void)
  98 {
  99         int ret;
 100
 101         filter_ops = xt_hook_ops_alloc(&packet_filter, ip6table_filter_hook);
 102         if (IS_ERR(filter_ops))
 103                 return PTR_ERR(filter_ops);
 104
 105         ret = register_pernet_subsys(&ip6table_filter_net_ops);
 106         if (ret < 0)
 107                 kfree(filter_ops);
 108
 109         return ret;
 110 }
 111
 112 static void __exit ip6table_filter_fini(void)
 113 {
 114         unregister_pernet_subsys(&ip6table_filter_net_ops);
 115         kfree(filter_ops);
 116 }
 117
 118 module_init(ip6table_filter_init);
 119 module_exit(ip6table_filter_fini);