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 const struct xt_table packet_filter = {
  55         .name           = "filter",
  56         .valid_hooks    = FILTER_VALID_HOOKS,
  57         .me             = THIS_MODULE,
  58         .af             = NFPROTO_IPV6,
  59 };
  60
  61 /* The work comes in here from netfilter.c. */
  62 static unsigned int
  63 ip6t_in_hook(unsigned int hook,
  64                    struct sk_buff *skb,
  65                    const struct net_device *in,
  66                    const struct net_device *out,
  67                    int (*okfn)(struct sk_buff *))
  68 {
  69         return ip6t_do_table(skb, hook, in, out,
  70                              dev_net(in)->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,
  91                              dev_net(out)->ipv6.ip6table_filter);
  92 }
  93
  94 static struct nf_hook_ops ip6t_ops[] __read_mostly = {
  95         {
  96                 .hook           = ip6t_in_hook,
  97                 .owner          = THIS_MODULE,
  98                 .pf             = NFPROTO_IPV6,
  99                 .hooknum        = NF_INET_LOCAL_IN,
 100                 .priority       = NF_IP6_PRI_FILTER,
 101         },
 102         {
 103                 .hook           = ip6t_in_hook,
 104                 .owner          = THIS_MODULE,
 105                 .pf             = NFPROTO_IPV6,
 106                 .hooknum        = NF_INET_FORWARD,
 107                 .priority       = NF_IP6_PRI_FILTER,
 108         },
 109         {
 110                 .hook           = ip6t_local_out_hook,
 111                 .owner          = THIS_MODULE,
 112                 .pf             = NFPROTO_IPV6,
 113                 .hooknum        = NF_INET_LOCAL_OUT,
 114                 .priority       = NF_IP6_PRI_FILTER,
 115         },
 116 };
 117
 118 /* Default to forward because I got too much mail already. */
 119 static int forward = NF_ACCEPT;
 120 module_param(forward, bool, 0000);
 121
 122 static int __net_init ip6table_filter_net_init(struct net *net)
 123 {
 124         /* Register table */
 125         net->ipv6.ip6table_filter =
 126                 ip6t_register_table(net, &packet_filter, &initial_table.repl);
 127         if (IS_ERR(net->ipv6.ip6table_filter))
 128                 return PTR_ERR(net->ipv6.ip6table_filter);
 129         return 0;
 130 }
 131
 132 static void __net_exit ip6table_filter_net_exit(struct net *net)
 133 {
 134         ip6t_unregister_table(net->ipv6.ip6table_filter);
 135 }
 136
 137 static struct pernet_operations ip6table_filter_net_ops = {
 138         .init = ip6table_filter_net_init,
 139         .exit = ip6table_filter_net_exit,
 140 };
 141
 142 static int __init ip6table_filter_init(void)
 143 {
 144         int ret;
 145
 146         if (forward < 0 || forward > NF_MAX_VERDICT) {
 147                 printk("iptables forward must be 0 or 1\n");
 148                 return -EINVAL;
 149         }
 150
 151         /* Entry 1 is the FORWARD hook */
 152         initial_table.entries[1].target.verdict = -forward - 1;
 153
 154         ret = register_pernet_subsys(&ip6table_filter_net_ops);
 155         if (ret < 0)
 156                 return ret;
 157
 158         /* Register hooks */
 159         ret = nf_register_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 160         if (ret < 0)
 161                 goto cleanup_table;
 162
 163         return ret;
 164
 165  cleanup_table:
 166         unregister_pernet_subsys(&ip6table_filter_net_ops);
 167         return ret;
 168 }
 169
 170 static void __exit ip6table_filter_fini(void)
 171 {
 172         nf_unregister_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 173         unregister_pernet_subsys(&ip6table_filter_net_ops);
 174 }
 175
 176 module_init(ip6table_filter_init);
 177 module_exit(ip6table_filter_fini);