net/ipv6/netfilter/ip6table_mangle.c

   1 /*
   2  * IPv6 packet mangling table, a port of the IPv4 mangle table to IPv6
   3  *
   4  * Copyright (C) 2000-2001 by Harald Welte <laforge@gnumonks.org>
   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 #include <linux/module.h>
  12 #include <linux/netfilter_ipv6/ip6_tables.h>
  13
  14 MODULE_LICENSE("GPL");
  15 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  16 MODULE_DESCRIPTION("ip6tables mangle table");
  17
  18 #define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \
  19                             (1 << NF_INET_LOCAL_IN) | \
  20                             (1 << NF_INET_FORWARD) | \
  21                             (1 << NF_INET_LOCAL_OUT) | \
  22                             (1 << NF_INET_POST_ROUTING))
  23
  24 static struct
  25 {
  26         struct ip6t_replace repl;
  27         struct ip6t_standard entries[5];
  28         struct ip6t_error term;
  29 } initial_table __net_initdata = {
  30         .repl = {
  31                 .name = "mangle",
  32                 .valid_hooks = MANGLE_VALID_HOOKS,
  33                 .num_entries = 6,
  34                 .size = sizeof(struct ip6t_standard) * 5 + sizeof(struct ip6t_error),
  35                 .hook_entry = {
  36                         [NF_INET_PRE_ROUTING]   = 0,
  37                         [NF_INET_LOCAL_IN]      = sizeof(struct ip6t_standard),
  38                         [NF_INET_FORWARD]       = sizeof(struct ip6t_standard) * 2,
  39                         [NF_INET_LOCAL_OUT]     = sizeof(struct ip6t_standard) * 3,
  40                         [NF_INET_POST_ROUTING]  = sizeof(struct ip6t_standard) * 4,
  41                 },
  42                 .underflow = {
  43                         [NF_INET_PRE_ROUTING]   = 0,
  44                         [NF_INET_LOCAL_IN]      = sizeof(struct ip6t_standard),
  45                         [NF_INET_FORWARD]       = sizeof(struct ip6t_standard) * 2,
  46                         [NF_INET_LOCAL_OUT]     = sizeof(struct ip6t_standard) * 3,
  47                         [NF_INET_POST_ROUTING]  = sizeof(struct ip6t_standard) * 4,
  48                 },
  49         },
  50         .entries = {
  51                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* PRE_ROUTING */
  52                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* LOCAL_IN */
  53                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* FORWARD */
  54                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* LOCAL_OUT */
  55                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* POST_ROUTING */
  56         },
  57         .term = IP6T_ERROR_INIT,                /* ERROR */
  58 };
  59
  60 static struct xt_table packet_mangler = {
  61         .name           = "mangle",
  62         .valid_hooks    = MANGLE_VALID_HOOKS,
  63         .lock           = __RW_LOCK_UNLOCKED(packet_mangler.lock),
  64         .me             = THIS_MODULE,
  65         .af             = AF_INET6,
  66 };
  67
  68 /* The work comes in here from netfilter.c. */
  69 static unsigned int
  70 ip6t_in_hook(unsigned int hook,
  71          struct sk_buff *skb,
  72          const struct net_device *in,
  73          const struct net_device *out,
  74          int (*okfn)(struct sk_buff *))
  75 {
  76         return ip6t_do_table(skb, hook, in, out,
  77                              dev_net(in)->ipv6.ip6table_mangle);
  78 }
  79
  80 static unsigned int
  81 ip6t_post_routing_hook(unsigned int hook,
  82                 struct sk_buff *skb,
  83                 const struct net_device *in,
  84                 const struct net_device *out,
  85                 int (*okfn)(struct sk_buff *))
  86 {
  87         return ip6t_do_table(skb, hook, in, out,
  88                              dev_net(out)->ipv6.ip6table_mangle);
  89 }
  90
  91 static unsigned int
  92 ip6t_local_out_hook(unsigned int hook,
  93                    struct sk_buff *skb,
  94                    const struct net_device *in,
  95                    const struct net_device *out,
  96                    int (*okfn)(struct sk_buff *))
  97 {
  98
  99         unsigned int ret;
 100         struct in6_addr saddr, daddr;
 101         u_int8_t hop_limit;
 102         u_int32_t flowlabel, mark;
 103
 104 #if 0
 105         /* root is playing with raw sockets. */
 106         if (skb->len < sizeof(struct iphdr)
 107             || ip_hdrlen(skb) < sizeof(struct iphdr)) {
 108                 if (net_ratelimit())
 109                         printk("ip6t_hook: happy cracking.\n");
 110                 return NF_ACCEPT;
 111         }
 112 #endif
 113
 114         /* save source/dest address, mark, hoplimit, flowlabel, priority,  */
 115         memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
 116         memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
 117         mark = skb->mark;
 118         hop_limit = ipv6_hdr(skb)->hop_limit;
 119
 120         /* flowlabel and prio (includes version, which shouldn't change either */
 121         flowlabel = *((u_int32_t *)ipv6_hdr(skb));
 122
 123         ret = ip6t_do_table(skb, hook, in, out,
 124                             dev_net(out)->ipv6.ip6table_mangle);
 125
 126         if (ret != NF_DROP && ret != NF_STOLEN
 127                 && (memcmp(&ipv6_hdr(skb)->saddr, &saddr, sizeof(saddr))
 128                     || memcmp(&ipv6_hdr(skb)->daddr, &daddr, sizeof(daddr))
 129                     || skb->mark != mark
 130                     || ipv6_hdr(skb)->hop_limit != hop_limit))
 131                 return ip6_route_me_harder(skb) == 0 ? ret : NF_DROP;
 132
 133         return ret;
 134 }
 135
 136 static struct nf_hook_ops ip6t_ops[] __read_mostly = {
 137         {
 138                 .hook           = ip6t_in_hook,
 139                 .owner          = THIS_MODULE,
 140                 .pf             = PF_INET6,
 141                 .hooknum        = NF_INET_PRE_ROUTING,
 142                 .priority       = NF_IP6_PRI_MANGLE,
 143         },
 144         {
 145                 .hook           = ip6t_in_hook,
 146                 .owner          = THIS_MODULE,
 147                 .pf             = PF_INET6,
 148                 .hooknum        = NF_INET_LOCAL_IN,
 149                 .priority       = NF_IP6_PRI_MANGLE,
 150         },
 151         {
 152                 .hook           = ip6t_in_hook,
 153                 .owner          = THIS_MODULE,
 154                 .pf             = PF_INET6,
 155                 .hooknum        = NF_INET_FORWARD,
 156                 .priority       = NF_IP6_PRI_MANGLE,
 157         },
 158         {
 159                 .hook           = ip6t_local_out_hook,
 160                 .owner          = THIS_MODULE,
 161                 .pf             = PF_INET6,
 162                 .hooknum        = NF_INET_LOCAL_OUT,
 163                 .priority       = NF_IP6_PRI_MANGLE,
 164         },
 165         {
 166                 .hook           = ip6t_post_routing_hook,
 167                 .owner          = THIS_MODULE,
 168                 .pf             = PF_INET6,
 169                 .hooknum        = NF_INET_POST_ROUTING,
 170                 .priority       = NF_IP6_PRI_MANGLE,
 171         },
 172 };
 173
 174 static int __net_init ip6table_mangle_net_init(struct net *net)
 175 {
 176         /* Register table */
 177         net->ipv6.ip6table_mangle =
 178                 ip6t_register_table(net, &packet_mangler, &initial_table.repl);
 179         if (IS_ERR(net->ipv6.ip6table_mangle))
 180                 return PTR_ERR(net->ipv6.ip6table_mangle);
 181         return 0;
 182 }
 183
 184 static void __net_exit ip6table_mangle_net_exit(struct net *net)
 185 {
 186         ip6t_unregister_table(net->ipv6.ip6table_mangle);
 187 }
 188
 189 static struct pernet_operations ip6table_mangle_net_ops = {
 190         .init = ip6table_mangle_net_init,
 191         .exit = ip6table_mangle_net_exit,
 192 };
 193
 194 static int __init ip6table_mangle_init(void)
 195 {
 196         int ret;
 197
 198         ret = register_pernet_subsys(&ip6table_mangle_net_ops);
 199         if (ret < 0)
 200                 return ret;
 201
 202         /* Register hooks */
 203         ret = nf_register_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 204         if (ret < 0)
 205                 goto cleanup_table;
 206
 207         return ret;
 208
 209  cleanup_table:
 210         unregister_pernet_subsys(&ip6table_mangle_net_ops);
 211         return ret;
 212 }
 213
 214 static void __exit ip6table_mangle_fini(void)
 215 {
 216         nf_unregister_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 217         unregister_pernet_subsys(&ip6table_mangle_net_ops);
 218 }
 219
 220 module_init(ip6table_mangle_init);
 221 module_exit(ip6table_mangle_fini);