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_local_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                              nf_local_in_net(in, out)->ipv6.ip6table_filter);
  72 }
  73
  74 static unsigned int
  75 ip6t_forward_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         return ip6t_do_table(skb, hook, in, out,
  82                              nf_forward_net(in, out)->ipv6.ip6table_filter);
  83 }
  84
  85 static unsigned int
  86 ip6t_local_out_hook(unsigned int hook,
  87                    struct sk_buff *skb,
  88                    const struct net_device *in,
  89                    const struct net_device *out,
  90                    int (*okfn)(struct sk_buff *))
  91 {
  92 #if 0
  93         /* root is playing with raw sockets. */
  94         if (skb->len < sizeof(struct iphdr)
  95             || ip_hdrlen(skb) < sizeof(struct iphdr)) {
  96                 if (net_ratelimit())
  97                         printk("ip6t_hook: happy cracking.\n");
  98                 return NF_ACCEPT;
  99         }
 100 #endif
 101
 102         return ip6t_do_table(skb, hook, in, out,
 103                              nf_local_out_net(in, out)->ipv6.ip6table_filter);
 104 }
 105
 106 static struct nf_hook_ops ip6t_ops[] __read_mostly = {
 107         {
 108                 .hook           = ip6t_local_in_hook,
 109                 .owner          = THIS_MODULE,
 110                 .pf             = PF_INET6,
 111                 .hooknum        = NF_INET_LOCAL_IN,
 112                 .priority       = NF_IP6_PRI_FILTER,
 113         },
 114         {
 115                 .hook           = ip6t_forward_hook,
 116                 .owner          = THIS_MODULE,
 117                 .pf             = PF_INET6,
 118                 .hooknum        = NF_INET_FORWARD,
 119                 .priority       = NF_IP6_PRI_FILTER,
 120         },
 121         {
 122                 .hook           = ip6t_local_out_hook,
 123                 .owner          = THIS_MODULE,
 124                 .pf             = PF_INET6,
 125                 .hooknum        = NF_INET_LOCAL_OUT,
 126                 .priority       = NF_IP6_PRI_FILTER,
 127         },
 128 };
 129
 130 /* Default to forward because I got too much mail already. */
 131 static int forward = NF_ACCEPT;
 132 module_param(forward, bool, 0000);
 133
 134 static int __net_init ip6table_filter_net_init(struct net *net)
 135 {
 136         /* Register table */
 137         net->ipv6.ip6table_filter =
 138                 ip6t_register_table(net, &packet_filter, &initial_table.repl);
 139         if (IS_ERR(net->ipv6.ip6table_filter))
 140                 return PTR_ERR(net->ipv6.ip6table_filter);
 141         return 0;
 142 }
 143
 144 static void __net_exit ip6table_filter_net_exit(struct net *net)
 145 {
 146         ip6t_unregister_table(net->ipv6.ip6table_filter);
 147 }
 148
 149 static struct pernet_operations ip6table_filter_net_ops = {
 150         .init = ip6table_filter_net_init,
 151         .exit = ip6table_filter_net_exit,
 152 };
 153
 154 static int __init ip6table_filter_init(void)
 155 {
 156         int ret;
 157
 158         if (forward < 0 || forward > NF_MAX_VERDICT) {
 159                 printk("iptables forward must be 0 or 1\n");
 160                 return -EINVAL;
 161         }
 162
 163         /* Entry 1 is the FORWARD hook */
 164         initial_table.entries[1].target.verdict = -forward - 1;
 165
 166         ret = register_pernet_subsys(&ip6table_filter_net_ops);
 167         if (ret < 0)
 168                 return ret;
 169
 170         /* Register hooks */
 171         ret = nf_register_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 172         if (ret < 0)
 173                 goto cleanup_table;
 174
 175         return ret;
 176
 177  cleanup_table:
 178         unregister_pernet_subsys(&ip6table_filter_net_ops);
 179         return ret;
 180 }
 181
 182 static void __exit ip6table_filter_fini(void)
 183 {
 184         nf_unregister_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 185         unregister_pernet_subsys(&ip6table_filter_net_ops);
 186 }
 187
 188 module_init(ip6table_filter_init);
 189 module_exit(ip6table_filter_fini);