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(packet_filter.lock),
  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_in_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,
  71                              dev_net(in)->ipv6.ip6table_filter);
  72 }
  73
  74 static unsigned int
  75 ip6t_local_out_hook(unsigned int hook,
  76                    struct sk_buff *skb,
  77                    const struct net_device *in,
  78                    const struct net_device *out,
  79                    int (*okfn)(struct sk_buff *))
  80 {
  81 #if 0
  82         /* root is playing with raw sockets. */
  83         if (skb->len < sizeof(struct iphdr)
  84             || ip_hdrlen(skb) < sizeof(struct iphdr)) {
  85                 if (net_ratelimit())
  86                         printk("ip6t_hook: happy cracking.\n");
  87                 return NF_ACCEPT;
  88         }
  89 #endif
  90
  91         return ip6t_do_table(skb, hook, in, out,
  92                              dev_net(out)->ipv6.ip6table_filter);
  93 }
  94
  95 static struct nf_hook_ops ip6t_ops[] __read_mostly = {
  96         {
  97                 .hook           = ip6t_in_hook,
  98                 .owner          = THIS_MODULE,
  99                 .pf             = PF_INET6,
 100                 .hooknum        = NF_INET_LOCAL_IN,
 101                 .priority       = NF_IP6_PRI_FILTER,
 102         },
 103         {
 104                 .hook           = ip6t_in_hook,
 105                 .owner          = THIS_MODULE,
 106                 .pf             = PF_INET6,
 107                 .hooknum        = NF_INET_FORWARD,
 108                 .priority       = NF_IP6_PRI_FILTER,
 109         },
 110         {
 111                 .hook           = ip6t_local_out_hook,
 112                 .owner          = THIS_MODULE,
 113                 .pf             = PF_INET6,
 114                 .hooknum        = NF_INET_LOCAL_OUT,
 115                 .priority       = NF_IP6_PRI_FILTER,
 116         },
 117 };
 118
 119 /* Default to forward because I got too much mail already. */
 120 static int forward = NF_ACCEPT;
 121 module_param(forward, bool, 0000);
 122
 123 static int __net_init ip6table_filter_net_init(struct net *net)
 124 {
 125         /* Register table */
 126         net->ipv6.ip6table_filter =
 127                 ip6t_register_table(net, &packet_filter, &initial_table.repl);
 128         if (IS_ERR(net->ipv6.ip6table_filter))
 129                 return PTR_ERR(net->ipv6.ip6table_filter);
 130         return 0;
 131 }
 132
 133 static void __net_exit ip6table_filter_net_exit(struct net *net)
 134 {
 135         ip6t_unregister_table(net->ipv6.ip6table_filter);
 136 }
 137
 138 static struct pernet_operations ip6table_filter_net_ops = {
 139         .init = ip6table_filter_net_init,
 140         .exit = ip6table_filter_net_exit,
 141 };
 142
 143 static int __init ip6table_filter_init(void)
 144 {
 145         int ret;
 146
 147         if (forward < 0 || forward > NF_MAX_VERDICT) {
 148                 printk("iptables forward must be 0 or 1\n");
 149                 return -EINVAL;
 150         }
 151
 152         /* Entry 1 is the FORWARD hook */
 153         initial_table.entries[1].target.verdict = -forward - 1;
 154
 155         ret = register_pernet_subsys(&ip6table_filter_net_ops);
 156         if (ret < 0)
 157                 return ret;
 158
 159         /* Register hooks */
 160         ret = nf_register_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 161         if (ret < 0)
 162                 goto cleanup_table;
 163
 164         return ret;
 165
 166  cleanup_table:
 167         unregister_pernet_subsys(&ip6table_filter_net_ops);
 168         return ret;
 169 }
 170
 171 static void __exit ip6table_filter_fini(void)
 172 {
 173         nf_unregister_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 174         unregister_pernet_subsys(&ip6table_filter_net_ops);
 175 }
 176
 177 module_init(ip6table_filter_init);
 178 module_exit(ip6table_filter_fini);