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 /* Standard entry. */
  33 struct ip6t_standard
  34 {
  35         struct ip6t_entry entry;
  36         struct ip6t_standard_target target;
  37 };
  38
  39 struct ip6t_error_target
  40 {
  41         struct ip6t_entry_target target;
  42         char errorname[IP6T_FUNCTION_MAXNAMELEN];
  43 };
  44
  45 struct ip6t_error
  46 {
  47         struct ip6t_entry entry;
  48         struct ip6t_error_target target;
  49 };
  50
  51 static struct
  52 {
  53         struct ip6t_replace repl;
  54         struct ip6t_standard entries[5];
  55         struct ip6t_error term;
  56 } initial_table __initdata
  57 = { { "mangle", MANGLE_VALID_HOOKS, 6,
  58       sizeof(struct ip6t_standard) * 5 + sizeof(struct ip6t_error),
  59       { [NF_IP6_PRE_ROUTING]    = 0,
  60         [NF_IP6_LOCAL_IN]       = sizeof(struct ip6t_standard),
  61         [NF_IP6_FORWARD]        = sizeof(struct ip6t_standard) * 2,
  62         [NF_IP6_LOCAL_OUT]      = sizeof(struct ip6t_standard) * 3,
  63         [NF_IP6_POST_ROUTING]   = sizeof(struct ip6t_standard) * 4},
  64       { [NF_IP6_PRE_ROUTING]    = 0,
  65         [NF_IP6_LOCAL_IN]       = sizeof(struct ip6t_standard),
  66         [NF_IP6_FORWARD]        = sizeof(struct ip6t_standard) * 2,
  67         [NF_IP6_LOCAL_OUT]      = sizeof(struct ip6t_standard) * 3,
  68         [NF_IP6_POST_ROUTING]   = sizeof(struct ip6t_standard) * 4},
  69       0, NULL, { } },
  70     {
  71             /* PRE_ROUTING */
  72             { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  73                 0,
  74                 sizeof(struct ip6t_entry),
  75                 sizeof(struct ip6t_standard),
  76                 0, { 0, 0 }, { } },
  77               { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  78                 -NF_ACCEPT - 1 } },
  79             /* LOCAL_IN */
  80             { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  81                 0,
  82                 sizeof(struct ip6t_entry),
  83                 sizeof(struct ip6t_standard),
  84                 0, { 0, 0 }, { } },
  85               { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  86                 -NF_ACCEPT - 1 } },
  87             /* FORWARD */
  88             { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  89                 0,
  90                 sizeof(struct ip6t_entry),
  91                 sizeof(struct ip6t_standard),
  92                 0, { 0, 0 }, { } },
  93               { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
  94                 -NF_ACCEPT - 1 } },
  95             /* LOCAL_OUT */
  96             { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
  97                 0,
  98                 sizeof(struct ip6t_entry),
  99                 sizeof(struct ip6t_standard),
 100                 0, { 0, 0 }, { } },
 101               { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
 102                 -NF_ACCEPT - 1 } },
 103             /* POST_ROUTING */
 104             { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
 105                 0,
 106                 sizeof(struct ip6t_entry),
 107                 sizeof(struct ip6t_standard),
 108                 0, { 0, 0 }, { } },
 109               { { { { IP6T_ALIGN(sizeof(struct ip6t_standard_target)), "" } }, { } },
 110                 -NF_ACCEPT - 1 } }
 111     },
 112     /* ERROR */
 113     { { { { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, { { { 0 } } }, "", "", { 0 }, { 0 }, 0, 0, 0 },
 114         0,
 115         sizeof(struct ip6t_entry),
 116         sizeof(struct ip6t_error),
 117         0, { 0, 0 }, { } },
 118       { { { { IP6T_ALIGN(sizeof(struct ip6t_error_target)), IP6T_ERROR_TARGET } },
 119           { } },
 120         "ERROR"
 121       }
 122     }
 123 };
 124
 125 static struct ip6t_table packet_mangler = {
 126         .name           = "mangle",
 127         .valid_hooks    = MANGLE_VALID_HOOKS,
 128         .lock           = RW_LOCK_UNLOCKED,
 129         .me             = THIS_MODULE,
 130         .af             = AF_INET6,
 131 };
 132
 133 /* The work comes in here from netfilter.c. */
 134 static unsigned int
 135 ip6t_route_hook(unsigned int hook,
 136          struct sk_buff **pskb,
 137          const struct net_device *in,
 138          const struct net_device *out,
 139          int (*okfn)(struct sk_buff *))
 140 {
 141         return ip6t_do_table(pskb, hook, in, out, &packet_mangler, NULL);
 142 }
 143
 144 static unsigned int
 145 ip6t_local_hook(unsigned int hook,
 146                    struct sk_buff **pskb,
 147                    const struct net_device *in,
 148                    const struct net_device *out,
 149                    int (*okfn)(struct sk_buff *))
 150 {
 151
 152         unsigned long nfmark;
 153         unsigned int ret;
 154         struct in6_addr saddr, daddr;
 155         u_int8_t hop_limit;
 156         u_int32_t flowlabel;
 157
 158 #if 0
 159         /* root is playing with raw sockets. */
 160         if ((*pskb)->len < sizeof(struct iphdr)
 161             || (*pskb)->nh.iph->ihl * 4 < sizeof(struct iphdr)) {
 162                 if (net_ratelimit())
 163                         printk("ip6t_hook: happy cracking.\n");
 164                 return NF_ACCEPT;
 165         }
 166 #endif
 167
 168         /* save source/dest address, nfmark, hoplimit, flowlabel, priority,  */
 169         memcpy(&saddr, &(*pskb)->nh.ipv6h->saddr, sizeof(saddr));
 170         memcpy(&daddr, &(*pskb)->nh.ipv6h->daddr, sizeof(daddr));
 171         nfmark = (*pskb)->nfmark;
 172         hop_limit = (*pskb)->nh.ipv6h->hop_limit;
 173
 174         /* flowlabel and prio (includes version, which shouldn't change either */
 175         flowlabel = *((u_int32_t *) (*pskb)->nh.ipv6h);
 176
 177         ret = ip6t_do_table(pskb, hook, in, out, &packet_mangler, NULL);
 178
 179         if (ret != NF_DROP && ret != NF_STOLEN
 180                 && (memcmp(&(*pskb)->nh.ipv6h->saddr, &saddr, sizeof(saddr))
 181                     || memcmp(&(*pskb)->nh.ipv6h->daddr, &daddr, sizeof(daddr))
 182                     || (*pskb)->nfmark != nfmark
 183                     || (*pskb)->nh.ipv6h->hop_limit != hop_limit)) {
 184
 185                 /* something which could affect routing has changed */
 186
 187                 DEBUGP("ip6table_mangle: we'd need to re-route a packet\n");
 188         }
 189
 190         return ret;
 191 }
 192
 193 static struct nf_hook_ops ip6t_ops[] = {
 194         {
 195                 .hook           = ip6t_route_hook,
 196                 .owner          = THIS_MODULE,
 197                 .pf             = PF_INET6,
 198                 .hooknum        = NF_IP6_PRE_ROUTING,
 199                 .priority       = NF_IP6_PRI_MANGLE,
 200         },
 201         {
 202                 .hook           = ip6t_local_hook,
 203                 .owner          = THIS_MODULE,
 204                 .pf             = PF_INET6,
 205                 .hooknum        = NF_IP6_LOCAL_IN,
 206                 .priority       = NF_IP6_PRI_MANGLE,
 207         },
 208         {
 209                 .hook           = ip6t_route_hook,
 210                 .owner          = THIS_MODULE,
 211                 .pf             = PF_INET6,
 212                 .hooknum        = NF_IP6_FORWARD,
 213                 .priority       = NF_IP6_PRI_MANGLE,
 214         },
 215         {
 216                 .hook           = ip6t_local_hook,
 217                 .owner          = THIS_MODULE,
 218                 .pf             = PF_INET6,
 219                 .hooknum        = NF_IP6_LOCAL_OUT,
 220                 .priority       = NF_IP6_PRI_MANGLE,
 221         },
 222         {
 223                 .hook           = ip6t_route_hook,
 224                 .owner          = THIS_MODULE,
 225                 .pf             = PF_INET6,
 226                 .hooknum        = NF_IP6_POST_ROUTING,
 227                 .priority       = NF_IP6_PRI_MANGLE,
 228         },
 229 };
 230
 231 static int __init ip6table_mangle_init(void)
 232 {
 233         int ret;
 234
 235         /* Register table */
 236         ret = ip6t_register_table(&packet_mangler, &initial_table.repl);
 237         if (ret < 0)
 238                 return ret;
 239
 240         /* Register hooks */
 241         ret = nf_register_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 242         if (ret < 0)
 243                 goto cleanup_table;
 244
 245         return ret;
 246
 247  cleanup_table:
 248         ip6t_unregister_table(&packet_mangler);
 249         return ret;
 250 }
 251
 252 static void __exit ip6table_mangle_fini(void)
 253 {
 254         nf_unregister_hooks(ip6t_ops, ARRAY_SIZE(ip6t_ops));
 255         ip6t_unregister_table(&packet_mangler);
 256 }
 257
 258 module_init(ip6table_mangle_init);
 259 module_exit(ip6table_mangle_fini);