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_IP6_LOCAL_IN) | (1 << NF_IP6_FORWARD) | (1 << NF_IP6_LOCAL_OUT))
  21
  22 static struct
  23 {
  24         struct ip6t_replace repl;
  25         struct ip6t_standard entries[3];
  26         struct ip6t_error term;
  27 } initial_table __initdata = {
  28         .repl = {
  29                 .name = "filter",
  30                 .valid_hooks = FILTER_VALID_HOOKS,
  31                 .num_entries = 4,
  32                 .size = sizeof(struct ip6t_standard) * 3 + sizeof(struct ip6t_error),
  33                 .hook_entry = {
  34                         [NF_IP6_LOCAL_IN] = 0,
  35                         [NF_IP6_FORWARD] = sizeof(struct ip6t_standard),
  36                         [NF_IP6_LOCAL_OUT] = sizeof(struct ip6t_standard) * 2
  37                 },
  38                 .underflow = {
  39                         [NF_IP6_LOCAL_IN] = 0,
  40                         [NF_IP6_FORWARD] = sizeof(struct ip6t_standard),
  41                         [NF_IP6_LOCAL_OUT] = sizeof(struct ip6t_standard) * 2
  42                 },
  43         },
  44         .entries = {
  45                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* LOCAL_IN */
  46                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* FORWARD */
  47                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* LOCAL_OUT */
  48         },
  49         .term = IP6T_ERROR_INIT,                /* ERROR */
  50 };
  51
  52 static struct xt_table packet_filter = {
  53         .name           = "filter",
  54         .valid_hooks    = FILTER_VALID_HOOKS,
  55         .lock           = RW_LOCK_UNLOCKED,
  56         .me             = THIS_MODULE,
  57         .af             = AF_INET6,
  58 };
  59
  60 /* The work comes in here from netfilter.c. */
  61 static unsigned int
  62 ip6t_hook(unsigned int hook,
  63          struct sk_buff *skb,
  64          const struct net_device *in,
  65          const struct net_device *out,
  66          int (*okfn)(struct sk_buff *))
  67 {
  68         return ip6t_do_table(skb, hook, in, out, &packet_filter);
  69 }
  70
  71 static unsigned int
  72 ip6t_local_out_hook(unsigned int hook,
  73                    struct sk_buff *skb,
  74                    const struct net_device *in,
  75                    const struct net_device *out,
  76                    int (*okfn)(struct sk_buff *))
  77 {
  78 #if 0
  79         /* root is playing with raw sockets. */
  80         if (skb->len < sizeof(struct iphdr)
  81             || ip_hdrlen(skb) < sizeof(struct iphdr)) {
  82                 if (net_ratelimit())
  83                         printk("ip6t_hook: happy cracking.\n");
  84                 return NF_ACCEPT;
  85         }
  86 #endif
  87
  88         return ip6t_do_table(skb, hook, in, out, &packet_filter);
  89 }
  90
  91 static struct nf_hook_ops ip6t_ops[] = {
  92         {
  93                 .hook           = ip6t_hook,
  94                 .owner          = THIS_MODULE,
  95                 .pf             = PF_INET6,
  96                 .hooknum        = NF_IP6_LOCAL_IN,
  97                 .priority       = NF_IP6_PRI_FILTER,
  98         },
  99         {
 100                 .hook           = ip6t_hook,
 101                 .owner          = THIS_MODULE,
 102                 .pf             = PF_INET6,
 103                 .hooknum        = NF_IP6_FORWARD,
 104                 .priority       = NF_IP6_PRI_FILTER,
 105         },
 106         {
 107                 .hook           = ip6t_local_out_hook,
 108                 .owner          = THIS_MODULE,
 109                 .pf             = PF_INET6,
 110                 .hooknum        = NF_IP6_LOCAL_OUT,
 111                 .priority       = NF_IP6_PRI_FILTER,
 112         },
 113 };
 114
 115 /* Default to forward because I got too much mail already. */
 116 static int forward = NF_ACCEPT;
 117 module_param(forward, bool, 0000);
 118
 119 static int __init ip6table_filter_init(void)
 120 {
 121         int ret;
 122
 123         if (forward < 0 || forward > NF_MAX_VERDICT) {
 124                 printk("iptables forward must be 0 or 1\n");
 125                 return -EINVAL;
 126         }
 127
 128         /* Entry 1 is the FORWARD hook */
 129         initial_table.entries[1].target.verdict = -forward - 1;
 130
 131         /* Register table */
 132         ret = ip6t_register_table(&packet_filter, &initial_table.repl);
 133         if (ret < 0)
 134                 return ret;
 135
 136         /* Register hooks */
 137         ret = nf_register_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 138         if (ret < 0)
 139                 goto cleanup_table;
 140
 141         return ret;
 142
 143  cleanup_table:
 144         ip6t_unregister_table(&packet_filter);
 145         return ret;
 146 }
 147
 148 static void __exit ip6table_filter_fini(void)
 149 {
 150         nf_unregister_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 151         ip6t_unregister_table(&packet_filter);
 152 }
 153
 154 module_init(ip6table_filter_init);
 155 module_exit(ip6table_filter_fini);