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 #if 0
  25 #define DEBUGP(x, args...)      printk(KERN_DEBUG x, ## args)
  26 #else
  27 #define DEBUGP(x, args...)
  28 #endif
  29
  30 static struct
  31 {
  32         struct ip6t_replace repl;
  33         struct ip6t_standard entries[5];
  34         struct ip6t_error term;
  35 } initial_table __initdata = {
  36         .repl = {
  37                 .name = "mangle",
  38                 .valid_hooks = MANGLE_VALID_HOOKS,
  39                 .num_entries = 6,
  40                 .size = sizeof(struct ip6t_standard) * 5 + sizeof(struct ip6t_error),
  41                 .hook_entry = {
  42                         [NF_IP6_PRE_ROUTING]    = 0,
  43                         [NF_IP6_LOCAL_IN]       = sizeof(struct ip6t_standard),
  44                         [NF_IP6_FORWARD]        = sizeof(struct ip6t_standard) * 2,
  45                         [NF_IP6_LOCAL_OUT]      = sizeof(struct ip6t_standard) * 3,
  46                         [NF_IP6_POST_ROUTING]   = sizeof(struct ip6t_standard) * 4,
  47                 },
  48                 .underflow = {
  49                         [NF_IP6_PRE_ROUTING]    = 0,
  50                         [NF_IP6_LOCAL_IN]       = sizeof(struct ip6t_standard),
  51                         [NF_IP6_FORWARD]        = sizeof(struct ip6t_standard) * 2,
  52                         [NF_IP6_LOCAL_OUT]      = sizeof(struct ip6t_standard) * 3,
  53                         [NF_IP6_POST_ROUTING]   = sizeof(struct ip6t_standard) * 4,
  54                 },
  55         },
  56         .entries = {
  57                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* PRE_ROUTING */
  58                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* LOCAL_IN */
  59                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* FORWARD */
  60                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* LOCAL_OUT */
  61                 IP6T_STANDARD_INIT(NF_ACCEPT),  /* POST_ROUTING */
  62         },
  63         .term = IP6T_ERROR_INIT,                /* ERROR */
  64 };
  65
  66 static struct xt_table packet_mangler = {
  67         .name           = "mangle",
  68         .valid_hooks    = MANGLE_VALID_HOOKS,
  69         .lock           = RW_LOCK_UNLOCKED,
  70         .me             = THIS_MODULE,
  71         .af             = AF_INET6,
  72 };
  73
  74 /* The work comes in here from netfilter.c. */
  75 static unsigned int
  76 ip6t_route_hook(unsigned int hook,
  77          struct sk_buff **pskb,
  78          const struct net_device *in,
  79          const struct net_device *out,
  80          int (*okfn)(struct sk_buff *))
  81 {
  82         return ip6t_do_table(pskb, hook, in, out, &packet_mangler);
  83 }
  84
  85 static unsigned int
  86 ip6t_local_hook(unsigned int hook,
  87                    struct sk_buff **pskb,
  88                    const struct net_device *in,
  89                    const struct net_device *out,
  90                    int (*okfn)(struct sk_buff *))
  91 {
  92
  93         unsigned int ret;
  94         struct in6_addr saddr, daddr;
  95         u_int8_t hop_limit;
  96         u_int32_t flowlabel, mark;
  97
  98 #if 0
  99         /* root is playing with raw sockets. */
 100         if ((*pskb)->len < sizeof(struct iphdr)
 101             || ip_hdrlen(*pskb) < sizeof(struct iphdr)) {
 102                 if (net_ratelimit())
 103                         printk("ip6t_hook: happy cracking.\n");
 104                 return NF_ACCEPT;
 105         }
 106 #endif
 107
 108         /* save source/dest address, mark, hoplimit, flowlabel, priority,  */
 109         memcpy(&saddr, &ipv6_hdr(*pskb)->saddr, sizeof(saddr));
 110         memcpy(&daddr, &ipv6_hdr(*pskb)->daddr, sizeof(daddr));
 111         mark = (*pskb)->mark;
 112         hop_limit = ipv6_hdr(*pskb)->hop_limit;
 113
 114         /* flowlabel and prio (includes version, which shouldn't change either */
 115         flowlabel = *((u_int32_t *)ipv6_hdr(*pskb));
 116
 117         ret = ip6t_do_table(pskb, hook, in, out, &packet_mangler);
 118
 119         if (ret != NF_DROP && ret != NF_STOLEN
 120                 && (memcmp(&ipv6_hdr(*pskb)->saddr, &saddr, sizeof(saddr))
 121                     || memcmp(&ipv6_hdr(*pskb)->daddr, &daddr, sizeof(daddr))
 122                     || (*pskb)->mark != mark
 123                     || ipv6_hdr(*pskb)->hop_limit != hop_limit))
 124                 return ip6_route_me_harder(*pskb) == 0 ? ret : NF_DROP;
 125
 126         return ret;
 127 }
 128
 129 static struct nf_hook_ops ip6t_ops[] = {
 130         {
 131                 .hook           = ip6t_route_hook,
 132                 .owner          = THIS_MODULE,
 133                 .pf             = PF_INET6,
 134                 .hooknum        = NF_IP6_PRE_ROUTING,
 135                 .priority       = NF_IP6_PRI_MANGLE,
 136         },
 137         {
 138                 .hook           = ip6t_local_hook,
 139                 .owner          = THIS_MODULE,
 140                 .pf             = PF_INET6,
 141                 .hooknum        = NF_IP6_LOCAL_IN,
 142                 .priority       = NF_IP6_PRI_MANGLE,
 143         },
 144         {
 145                 .hook           = ip6t_route_hook,
 146                 .owner          = THIS_MODULE,
 147                 .pf             = PF_INET6,
 148                 .hooknum        = NF_IP6_FORWARD,
 149                 .priority       = NF_IP6_PRI_MANGLE,
 150         },
 151         {
 152                 .hook           = ip6t_local_hook,
 153                 .owner          = THIS_MODULE,
 154                 .pf             = PF_INET6,
 155                 .hooknum        = NF_IP6_LOCAL_OUT,
 156                 .priority       = NF_IP6_PRI_MANGLE,
 157         },
 158         {
 159                 .hook           = ip6t_route_hook,
 160                 .owner          = THIS_MODULE,
 161                 .pf             = PF_INET6,
 162                 .hooknum        = NF_IP6_POST_ROUTING,
 163                 .priority       = NF_IP6_PRI_MANGLE,
 164         },
 165 };
 166
 167 static int __init ip6table_mangle_init(void)
 168 {
 169         int ret;
 170
 171         /* Register table */
 172         ret = ip6t_register_table(&packet_mangler, &initial_table.repl);
 173         if (ret < 0)
 174                 return ret;
 175
 176         /* Register hooks */
 177         ret = nf_register_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 178         if (ret < 0)
 179                 goto cleanup_table;
 180
 181         return ret;
 182
 183  cleanup_table:
 184         ip6t_unregister_table(&packet_mangler);
 185         return ret;
 186 }
 187
 188 static void __exit ip6table_mangle_fini(void)
 189 {
 190         nf_unregister_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 191         ip6t_unregister_table(&packet_mangler);
 192 }
 193
 194 module_init(ip6table_mangle_init);
 195 module_exit(ip6table_mangle_fini);