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 __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,
  64         .me             = THIS_MODULE,
  65         .af             = AF_INET6,
  66 };
  67 static struct xt_table *packet_mangler;
  68
  69 /* The work comes in here from netfilter.c. */
  70 static unsigned int
  71 ip6t_route_hook(unsigned int hook,
  72          struct sk_buff *skb,
  73          const struct net_device *in,
  74          const struct net_device *out,
  75          int (*okfn)(struct sk_buff *))
  76 {
  77         return ip6t_do_table(skb, hook, in, out, packet_mangler);
  78 }
  79
  80 static unsigned int
  81 ip6t_local_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
  88         unsigned int ret;
  89         struct in6_addr saddr, daddr;
  90         u_int8_t hop_limit;
  91         u_int32_t flowlabel, mark;
  92
  93 #if 0
  94         /* root is playing with raw sockets. */
  95         if (skb->len < sizeof(struct iphdr)
  96             || ip_hdrlen(skb) < sizeof(struct iphdr)) {
  97                 if (net_ratelimit())
  98                         printk("ip6t_hook: happy cracking.\n");
  99                 return NF_ACCEPT;
 100         }
 101 #endif
 102
 103         /* save source/dest address, mark, hoplimit, flowlabel, priority,  */
 104         memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
 105         memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
 106         mark = skb->mark;
 107         hop_limit = ipv6_hdr(skb)->hop_limit;
 108
 109         /* flowlabel and prio (includes version, which shouldn't change either */
 110         flowlabel = *((u_int32_t *)ipv6_hdr(skb));
 111
 112         ret = ip6t_do_table(skb, hook, in, out, packet_mangler);
 113
 114         if (ret != NF_DROP && ret != NF_STOLEN
 115                 && (memcmp(&ipv6_hdr(skb)->saddr, &saddr, sizeof(saddr))
 116                     || memcmp(&ipv6_hdr(skb)->daddr, &daddr, sizeof(daddr))
 117                     || skb->mark != mark
 118                     || ipv6_hdr(skb)->hop_limit != hop_limit))
 119                 return ip6_route_me_harder(skb) == 0 ? ret : NF_DROP;
 120
 121         return ret;
 122 }
 123
 124 static struct nf_hook_ops ip6t_ops[] __read_mostly = {
 125         {
 126                 .hook           = ip6t_route_hook,
 127                 .owner          = THIS_MODULE,
 128                 .pf             = PF_INET6,
 129                 .hooknum        = NF_INET_PRE_ROUTING,
 130                 .priority       = NF_IP6_PRI_MANGLE,
 131         },
 132         {
 133                 .hook           = ip6t_local_hook,
 134                 .owner          = THIS_MODULE,
 135                 .pf             = PF_INET6,
 136                 .hooknum        = NF_INET_LOCAL_IN,
 137                 .priority       = NF_IP6_PRI_MANGLE,
 138         },
 139         {
 140                 .hook           = ip6t_route_hook,
 141                 .owner          = THIS_MODULE,
 142                 .pf             = PF_INET6,
 143                 .hooknum        = NF_INET_FORWARD,
 144                 .priority       = NF_IP6_PRI_MANGLE,
 145         },
 146         {
 147                 .hook           = ip6t_local_hook,
 148                 .owner          = THIS_MODULE,
 149                 .pf             = PF_INET6,
 150                 .hooknum        = NF_INET_LOCAL_OUT,
 151                 .priority       = NF_IP6_PRI_MANGLE,
 152         },
 153         {
 154                 .hook           = ip6t_route_hook,
 155                 .owner          = THIS_MODULE,
 156                 .pf             = PF_INET6,
 157                 .hooknum        = NF_INET_POST_ROUTING,
 158                 .priority       = NF_IP6_PRI_MANGLE,
 159         },
 160 };
 161
 162 static int __init ip6table_mangle_init(void)
 163 {
 164         int ret;
 165
 166         /* Register table */
 167         packet_mangler = ip6t_register_table(&init_net, &__packet_mangler, &initial_table.repl);
 168         if (IS_ERR(packet_mangler))
 169                 return PTR_ERR(packet_mangler);
 170
 171         /* Register hooks */
 172         ret = nf_register_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 173         if (ret < 0)
 174                 goto cleanup_table;
 175
 176         return ret;
 177
 178  cleanup_table:
 179         ip6t_unregister_table(packet_mangler);
 180         return ret;
 181 }
 182
 183 static void __exit ip6table_mangle_fini(void)
 184 {
 185         nf_unregister_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 186         ip6t_unregister_table(packet_mangler);
 187 }
 188
 189 module_init(ip6table_mangle_init);
 190 module_exit(ip6table_mangle_fini);