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  * Extended to all five netfilter hooks by Brad Chapman & Harald Welte
  12  */
  13 #include <linux/module.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 mangle table");
  19
  20 #define MANGLE_VALID_HOOKS ((1 << NF_IP6_PRE_ROUTING) | \
  21                             (1 << NF_IP6_LOCAL_IN) | \
  22                             (1 << NF_IP6_FORWARD) | \
  23                             (1 << NF_IP6_LOCAL_OUT) | \
  24                             (1 << NF_IP6_POST_ROUTING))
  25
  26 #if 0
  27 #define DEBUGP(x, args...)      printk(KERN_DEBUG x, ## args)
  28 #else
  29 #define DEBUGP(x, args...)
  30 #endif
  31
  32 static struct
  33 {
  34         struct ip6t_replace repl;
  35         struct ip6t_standard entries[5];
  36         struct ip6t_error term;
  37 } initial_table __initdata
  38 = { { "mangle", MANGLE_VALID_HOOKS, 6,
  39       sizeof(struct ip6t_standard) * 5 + sizeof(struct ip6t_error),
  40       { [NF_IP6_PRE_ROUTING]    = 0,
  41         [NF_IP6_LOCAL_IN]       = sizeof(struct ip6t_standard),
  42         [NF_IP6_FORWARD]        = sizeof(struct ip6t_standard) * 2,
  43         [NF_IP6_LOCAL_OUT]      = sizeof(struct ip6t_standard) * 3,
  44         [NF_IP6_POST_ROUTING]   = sizeof(struct ip6t_standard) * 4},
  45       { [NF_IP6_PRE_ROUTING]    = 0,
  46         [NF_IP6_LOCAL_IN]       = sizeof(struct ip6t_standard),
  47         [NF_IP6_FORWARD]        = sizeof(struct ip6t_standard) * 2,
  48         [NF_IP6_LOCAL_OUT]      = sizeof(struct ip6t_standard) * 3,
  49         [NF_IP6_POST_ROUTING]   = sizeof(struct ip6t_standard) * 4},
  50       0, NULL, { } },
  51     {
  52             /* PRE_ROUTING */
  53             { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  54                 0,
  55                 sizeof(struct ip6t_entry),
  56                 sizeof(struct ip6t_standard),
  57                 0, { 0, 0 }, { } },
  58               { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  59                 -NF_ACCEPT - 1 } },
  60             /* LOCAL_IN */
  61             { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  62                 0,
  63                 sizeof(struct ip6t_entry),
  64                 sizeof(struct ip6t_standard),
  65                 0, { 0, 0 }, { } },
  66               { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  67                 -NF_ACCEPT - 1 } },
  68             /* FORWARD */
  69             { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  70                 0,
  71                 sizeof(struct ip6t_entry),
  72                 sizeof(struct ip6t_standard),
  73                 0, { 0, 0 }, { } },
  74               { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  75                 -NF_ACCEPT - 1 } },
  76             /* LOCAL_OUT */
  77             { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  78                 0,
  79                 sizeof(struct ip6t_entry),
  80                 sizeof(struct ip6t_standard),
  81                 0, { 0, 0 }, { } },
  82               { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  83                 -NF_ACCEPT - 1 } },
  84             /* POST_ROUTING */
  85             { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  86                 0,
  87                 sizeof(struct ip6t_entry),
  88                 sizeof(struct ip6t_standard),
  89                 0, { 0, 0 }, { } },
  90               { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  91                 -NF_ACCEPT - 1 } }
  92     },
  93     /* ERROR */
  94     { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  95         0,
  96         sizeof(struct ip6t_entry),
  97         sizeof(struct ip6t_error),
  98         0, { 0, 0 }, { } },
  99       { { { { IP6T_ALIGN(sizeof(struct ip6t_error_target)), IP6T_ERROR_TARGET } },
 100           { } },
 101         "ERROR"
 102       }
 103     }
 104 };
 105
 106 static struct xt_table packet_mangler = {
 107         .name           = "mangle",
 108         .valid_hooks    = MANGLE_VALID_HOOKS,
 109         .lock           = RW_LOCK_UNLOCKED,
 110         .me             = THIS_MODULE,
 111         .af             = AF_INET6,
 112 };
 113
 114 /* The work comes in here from netfilter.c. */
 115 static unsigned int
 116 ip6t_route_hook(unsigned int hook,
 117          struct sk_buff **pskb,
 118          const struct net_device *in,
 119          const struct net_device *out,
 120          int (*okfn)(struct sk_buff *))
 121 {
 122         return ip6t_do_table(pskb, hook, in, out, &packet_mangler);
 123 }
 124
 125 static unsigned int
 126 ip6t_local_hook(unsigned int hook,
 127                    struct sk_buff **pskb,
 128                    const struct net_device *in,
 129                    const struct net_device *out,
 130                    int (*okfn)(struct sk_buff *))
 131 {
 132
 133         unsigned int ret;
 134         struct in6_addr saddr, daddr;
 135         u_int8_t hop_limit;
 136         u_int32_t flowlabel, mark;
 137
 138 #if 0
 139         /* root is playing with raw sockets. */
 140         if ((*pskb)->len < sizeof(struct iphdr)
 141             || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr)) {
 142                 if (net_ratelimit())
 143                         printk("ip6t_hook: happy cracking.\n");
 144                 return NF_ACCEPT;
 145         }
 146 #endif
 147
 148         /* save source/dest address, mark, hoplimit, flowlabel, priority,  */
 149         memcpy(&saddr, &(*pskb)->nh.ipv6h->saddr, sizeof(saddr));
 150         memcpy(&daddr, &(*pskb)->nh.ipv6h->daddr, sizeof(daddr));
 151         mark = (*pskb)->mark;
 152         hop_limit = (*pskb)->nh.ipv6h->hop_limit;
 153
 154         /* flowlabel and prio (includes version, which shouldn't change either */
 155         flowlabel = *((u_int32_t *) (*pskb)->nh.ipv6h);
 156
 157         ret = ip6t_do_table(pskb, hook, in, out, &packet_mangler);
 158
 159         if (ret != NF_DROP && ret != NF_STOLEN
 160                 && (memcmp(&(*pskb)->nh.ipv6h->saddr, &saddr, sizeof(saddr))
 161                     || memcmp(&(*pskb)->nh.ipv6h->daddr, &daddr, sizeof(daddr))
 162                     || (*pskb)->mark != mark
 163                     || (*pskb)->nh.ipv6h->hop_limit != hop_limit))
 164                 return ip6_route_me_harder(*pskb) == 0 ? ret : NF_DROP;
 165
 166         return ret;
 167 }
 168
 169 static struct nf_hook_ops ip6t_ops[] = {
 170         {
 171                 .hook           = ip6t_route_hook,
 172                 .owner          = THIS_MODULE,
 173                 .pf             = PF_INET6,
 174                 .hooknum        = NF_IP6_PRE_ROUTING,
 175                 .priority       = NF_IP6_PRI_MANGLE,
 176         },
 177         {
 178                 .hook           = ip6t_local_hook,
 179                 .owner          = THIS_MODULE,
 180                 .pf             = PF_INET6,
 181                 .hooknum        = NF_IP6_LOCAL_IN,
 182                 .priority       = NF_IP6_PRI_MANGLE,
 183         },
 184         {
 185                 .hook           = ip6t_route_hook,
 186                 .owner          = THIS_MODULE,
 187                 .pf             = PF_INET6,
 188                 .hooknum        = NF_IP6_FORWARD,
 189                 .priority       = NF_IP6_PRI_MANGLE,
 190         },
 191         {
 192                 .hook           = ip6t_local_hook,
 193                 .owner          = THIS_MODULE,
 194                 .pf             = PF_INET6,
 195                 .hooknum        = NF_IP6_LOCAL_OUT,
 196                 .priority       = NF_IP6_PRI_MANGLE,
 197         },
 198         {
 199                 .hook           = ip6t_route_hook,
 200                 .owner          = THIS_MODULE,
 201                 .pf             = PF_INET6,
 202                 .hooknum        = NF_IP6_POST_ROUTING,
 203                 .priority       = NF_IP6_PRI_MANGLE,
 204         },
 205 };
 206
 207 static int __init ip6table_mangle_init(void)
 208 {
 209         int ret;
 210
 211         /* Register table */
 212         ret = ip6t_register_table(&packet_mangler, &initial_table.repl);
 213         if (ret < 0)
 214                 return ret;
 215
 216         /* Register hooks */
 217         ret = nf_register_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 218         if (ret < 0)
 219                 goto cleanup_table;
 220
 221         return ret;
 222
 223  cleanup_table:
 224         ip6t_unregister_table(&packet_mangler);
 225         return ret;
 226 }
 227
 228 static void __exit ip6table_mangle_fini(void)
 229 {
 230         nf_unregister_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 231         ip6t_unregister_table(&packet_mangler);
 232 }
 233
 234 module_init(ip6table_mangle_init);
 235 module_exit(ip6table_mangle_fini);