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_IP6_PRE_ROUTING) | \
  19                             (1 << NF_IP6_LOCAL_IN) | \
  20                             (1 << NF_IP6_FORWARD) | \
  21                             (1 << NF_IP6_LOCAL_OUT) | \
  22                             (1 << NF_IP6_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_IP6_PRE_ROUTING]    = 0,
  37                         [NF_IP6_LOCAL_IN]       = sizeof(struct ip6t_standard),
  38                         [NF_IP6_FORWARD]        = sizeof(struct ip6t_standard) * 2,
  39                         [NF_IP6_LOCAL_OUT]      = sizeof(struct ip6t_standard) * 3,
  40                         [NF_IP6_POST_ROUTING]   = sizeof(struct ip6t_standard) * 4,
  41                 },
  42                 .underflow = {
  43                         [NF_IP6_PRE_ROUTING]    = 0,
  44                         [NF_IP6_LOCAL_IN]       = sizeof(struct ip6t_standard),
  45                         [NF_IP6_FORWARD]        = sizeof(struct ip6t_standard) * 2,
  46                         [NF_IP6_LOCAL_OUT]      = sizeof(struct ip6t_standard) * 3,
  47                         [NF_IP6_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
  68 /* The work comes in here from netfilter.c. */
  69 static unsigned int
  70 ip6t_route_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, &packet_mangler);
  77 }
  78
  79 static unsigned int
  80 ip6t_local_hook(unsigned int hook,
  81                    struct sk_buff *skb,
  82                    const struct net_device *in,
  83                    const struct net_device *out,
  84                    int (*okfn)(struct sk_buff *))
  85 {
  86
  87         unsigned int ret;
  88         struct in6_addr saddr, daddr;
  89         u_int8_t hop_limit;
  90         u_int32_t flowlabel, mark;
  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         /* save source/dest address, mark, hoplimit, flowlabel, priority,  */
 103         memcpy(&saddr, &ipv6_hdr(skb)->saddr, sizeof(saddr));
 104         memcpy(&daddr, &ipv6_hdr(skb)->daddr, sizeof(daddr));
 105         mark = skb->mark;
 106         hop_limit = ipv6_hdr(skb)->hop_limit;
 107
 108         /* flowlabel and prio (includes version, which shouldn't change either */
 109         flowlabel = *((u_int32_t *)ipv6_hdr(skb));
 110
 111         ret = ip6t_do_table(skb, hook, in, out, &packet_mangler);
 112
 113         if (ret != NF_DROP && ret != NF_STOLEN
 114                 && (memcmp(&ipv6_hdr(skb)->saddr, &saddr, sizeof(saddr))
 115                     || memcmp(&ipv6_hdr(skb)->daddr, &daddr, sizeof(daddr))
 116                     || skb->mark != mark
 117                     || ipv6_hdr(skb)->hop_limit != hop_limit))
 118                 return ip6_route_me_harder(skb) == 0 ? ret : NF_DROP;
 119
 120         return ret;
 121 }
 122
 123 static struct nf_hook_ops ip6t_ops[] = {
 124         {
 125                 .hook           = ip6t_route_hook,
 126                 .owner          = THIS_MODULE,
 127                 .pf             = PF_INET6,
 128                 .hooknum        = NF_IP6_PRE_ROUTING,
 129                 .priority       = NF_IP6_PRI_MANGLE,
 130         },
 131         {
 132                 .hook           = ip6t_local_hook,
 133                 .owner          = THIS_MODULE,
 134                 .pf             = PF_INET6,
 135                 .hooknum        = NF_IP6_LOCAL_IN,
 136                 .priority       = NF_IP6_PRI_MANGLE,
 137         },
 138         {
 139                 .hook           = ip6t_route_hook,
 140                 .owner          = THIS_MODULE,
 141                 .pf             = PF_INET6,
 142                 .hooknum        = NF_IP6_FORWARD,
 143                 .priority       = NF_IP6_PRI_MANGLE,
 144         },
 145         {
 146                 .hook           = ip6t_local_hook,
 147                 .owner          = THIS_MODULE,
 148                 .pf             = PF_INET6,
 149                 .hooknum        = NF_IP6_LOCAL_OUT,
 150                 .priority       = NF_IP6_PRI_MANGLE,
 151         },
 152         {
 153                 .hook           = ip6t_route_hook,
 154                 .owner          = THIS_MODULE,
 155                 .pf             = PF_INET6,
 156                 .hooknum        = NF_IP6_POST_ROUTING,
 157                 .priority       = NF_IP6_PRI_MANGLE,
 158         },
 159 };
 160
 161 static int __init ip6table_mangle_init(void)
 162 {
 163         int ret;
 164
 165         /* Register table */
 166         ret = ip6t_register_table(&packet_mangler, &initial_table.repl);
 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         ip6t_unregister_table(&packet_mangler);
 179         return ret;
 180 }
 181
 182 static void __exit ip6table_mangle_fini(void)
 183 {
 184         nf_unregister_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 185         ip6t_unregister_table(&packet_mangler);
 186 }
 187
 188 module_init(ip6table_mangle_init);
 189 module_exit(ip6table_mangle_fini);