net/ipv6/netfilter/ip6table_filter.c

   1 /*
   2  * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
   3  *
   4  * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
   5  * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/moduleparam.h>
  14 #include <linux/netfilter_ipv6/ip6_tables.h>
  15
  16 MODULE_LICENSE("GPL");
  17 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  18 MODULE_DESCRIPTION("ip6tables filter table");
  19
  20 #define FILTER_VALID_HOOKS ((1 << NF_INET_LOCAL_IN) | \
  21                             (1 << NF_INET_FORWARD) | \
  22                             (1 << NF_INET_LOCAL_OUT))
  23
  24 static struct
  25 {
  26         struct ip6t_replace repl;
  27         struct ip6t_standard entries[3];
  28         struct ip6t_error term;
  29 } initial_table __net_initdata = {
  30         .repl = {
  31                 .name = "filter",
  32                 .valid_hooks = FILTER_VALID_HOOKS,
  33                 .num_entries = 4,
  34                 .size = sizeof(struct ip6t_standard) * 3 + sizeof(struct ip6t_error),
  35                 .hook_entry = {
  36                         [NF_INET_LOCAL_IN] = 0,
  37                         [NF_INET_FORWARD] = sizeof(struct ip6t_standard),
  38                         [NF_INET_LOCAL_OUT] = sizeof(struct ip6t_standard) * 2
  39                 },
  40                 .underflow = {
  41                         [NF_INET_LOCAL_IN] = 0,
  42                         [NF_INET_FORWARD] = sizeof(struct ip6t_standard),
  43                         [NF_INET_LOCAL_OUT] = sizeof(struct ip6t_standard) * 2
  44                 },
  45         },
  46         .entries = {
  47                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* LOCAL_IN */
  48                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* FORWARD */
  49                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* LOCAL_OUT */
  50         },
  51         .term = IP6T_ERROR_INIT,                /* ERROR */
  52 };
  53
  54 static struct xt_table packet_filter = {
  55         .name           = "filter",
  56         .valid_hooks    = FILTER_VALID_HOOKS,
  57         .lock           = RW_LOCK_UNLOCKED,
  58         .me             = THIS_MODULE,
  59         .af             = AF_INET6,
  60 };
  61
  62 /* The work comes in here from netfilter.c. */
  63 static unsigned int
  64 ip6t_hook(unsigned int hook,
  65          struct sk_buff *skb,
  66          const struct net_device *in,
  67          const struct net_device *out,
  68          int (*okfn)(struct sk_buff *))
  69 {
  70         return ip6t_do_table(skb, hook, in, out, init_net.ipv6.ip6table_filter);
  71 }
  72
  73 static unsigned int
  74 ip6t_local_out_hook(unsigned int hook,
  75                    struct sk_buff *skb,
  76                    const struct net_device *in,
  77                    const struct net_device *out,
  78                    int (*okfn)(struct sk_buff *))
  79 {
  80 #if 0
  81         /* root is playing with raw sockets. */
  82         if (skb->len < sizeof(struct iphdr)
  83             || ip_hdrlen(skb) < sizeof(struct iphdr)) {
  84                 if (net_ratelimit())
  85                         printk("ip6t_hook: happy cracking.\n");
  86                 return NF_ACCEPT;
  87         }
  88 #endif
  89
  90         return ip6t_do_table(skb, hook, in, out, init_net.ipv6.ip6table_filter);
  91 }
  92
  93 static struct nf_hook_ops ip6t_ops[] __read_mostly = {
  94         {
  95                 .hook           = ip6t_hook,
  96                 .owner          = THIS_MODULE,
  97                 .pf             = PF_INET6,
  98                 .hooknum        = NF_INET_LOCAL_IN,
  99                 .priority       = NF_IP6_PRI_FILTER,
 100         },
 101         {
 102                 .hook           = ip6t_hook,
 103                 .owner          = THIS_MODULE,
 104                 .pf             = PF_INET6,
 105                 .hooknum        = NF_INET_FORWARD,
 106                 .priority       = NF_IP6_PRI_FILTER,
 107         },
 108         {
 109                 .hook           = ip6t_local_out_hook,
 110                 .owner          = THIS_MODULE,
 111                 .pf             = PF_INET6,
 112                 .hooknum        = NF_INET_LOCAL_OUT,
 113                 .priority       = NF_IP6_PRI_FILTER,
 114         },
 115 };
 116
 117 /* Default to forward because I got too much mail already. */
 118 static int forward = NF_ACCEPT;
 119 module_param(forward, bool, 0000);
 120
 121 static int __net_init ip6table_filter_net_init(struct net *net)
 122 {
 123         /* Register table */
 124         net->ipv6.ip6table_filter =
 125                 ip6t_register_table(net, &packet_filter, &initial_table.repl);
 126         if (IS_ERR(net->ipv6.ip6table_filter))
 127                 return PTR_ERR(net->ipv6.ip6table_filter);
 128         return 0;
 129 }
 130
 131 static void __net_exit ip6table_filter_net_exit(struct net *net)
 132 {
 133         ip6t_unregister_table(net->ipv6.ip6table_filter);
 134 }
 135
 136 static struct pernet_operations ip6table_filter_net_ops = {
 137         .init = ip6table_filter_net_init,
 138         .exit = ip6table_filter_net_exit,
 139 };
 140
 141 static int __init ip6table_filter_init(void)
 142 {
 143         int ret;
 144
 145         if (forward < 0 || forward > NF_MAX_VERDICT) {
 146                 printk("iptables forward must be 0 or 1\n");
 147                 return -EINVAL;
 148         }
 149
 150         /* Entry 1 is the FORWARD hook */
 151         initial_table.entries[1].target.verdict = -forward - 1;
 152
 153         ret = register_pernet_subsys(&ip6table_filter_net_ops);
 154         if (ret < 0)
 155                 return ret;
 156
 157         /* Register hooks */
 158         ret = nf_register_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 159         if (ret < 0)
 160                 goto cleanup_table;
 161
 162         return ret;
 163
 164  cleanup_table:
 165         unregister_pernet_subsys(&ip6table_filter_net_ops);
 166         return ret;
 167 }
 168
 169 static void __exit ip6table_filter_fini(void)
 170 {
 171         nf_unregister_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 172         unregister_pernet_subsys(&ip6table_filter_net_ops);
 173 }
 174
 175 module_init(ip6table_filter_init);
 176 module_exit(ip6table_filter_fini);