kdc/524.c

   1 /*
   2  * Copyright (c) 1997-2005 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include "kdc_locl.h"
  35
  36 #include <krb5-v4compat.h>
  37
  38 /*
  39  * fetch the server from `t', returning the name in malloced memory in
  40  * `spn' and the entry itself in `server'
  41  */
  42
  43 static krb5_error_code
  44 fetch_server (krb5_context context,
  45               krb5_kdc_configuration *config,
  46               const Ticket *t,
  47               char **spn,
  48               hdb_entry_ex **server,
  49               const char *from)
  50 {
  51     krb5_error_code ret;
  52     krb5_principal sprinc;
  53
  54     ret = _krb5_principalname2krb5_principal(context, &sprinc,
  55                                              t->sname, t->realm);
  56     if (ret) {
  57         kdc_log(context, config, 0, "_krb5_principalname2krb5_principal: %s",
  58                 krb5_get_err_text(context, ret));
  59         return ret;
  60     }
  61     ret = krb5_unparse_name(context, sprinc, spn);
  62     if (ret) {
  63         krb5_free_principal(context, sprinc);
  64         kdc_log(context, config, 0, "krb5_unparse_name: %s",
  65                 krb5_get_err_text(context, ret));
  66         return ret;
  67     }
  68     ret = _kdc_db_fetch(context, config, sprinc, HDB_F_GET_SERVER,
  69                         NULL, server);
  70     krb5_free_principal(context, sprinc);
  71     if (ret) {
  72         kdc_log(context, config, 0,
  73         "Request to convert ticket from %s for unknown principal %s: %s",
  74                 from, *spn, krb5_get_err_text(context, ret));
  75         if (ret == HDB_ERR_NOENTRY)
  76             ret = KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN;
  77         return ret;
  78     }
  79     return 0;
  80 }
  81
  82 static krb5_error_code
  83 log_524 (krb5_context context,
  84          krb5_kdc_configuration *config,
  85          const EncTicketPart *et,
  86          const char *from,
  87          const char *spn)
  88 {
  89     krb5_principal client;
  90     char *cpn;
  91     krb5_error_code ret;
  92
  93     ret = _krb5_principalname2krb5_principal(context, &client,
  94                                              et->cname, et->crealm);
  95     if (ret) {
  96         kdc_log(context, config, 0, "_krb5_principalname2krb5_principal: %s",
  97                 krb5_get_err_text (context, ret));
  98         return ret;
  99     }
 100     ret = krb5_unparse_name(context, client, &cpn);
 101     if (ret) {
 102         krb5_free_principal(context, client);
 103         kdc_log(context, config, 0, "krb5_unparse_name: %s",
 104                 krb5_get_err_text (context, ret));
 105         return ret;
 106     }
 107     kdc_log(context, config, 1, "524-REQ %s from %s for %s", cpn, from, spn);
 108     free(cpn);
 109     krb5_free_principal(context, client);
 110     return 0;
 111 }
 112
 113 static krb5_error_code
 114 verify_flags (krb5_context context,
 115               krb5_kdc_configuration *config,
 116               const EncTicketPart *et,
 117               const char *spn)
 118 {
 119     if(et->endtime < kdc_time){
 120         kdc_log(context, config, 0, "Ticket expired (%s)", spn);
 121         return KRB5KRB_AP_ERR_TKT_EXPIRED;
 122     }
 123     if(et->flags.invalid){
 124         kdc_log(context, config, 0, "Ticket not valid (%s)", spn);
 125         return KRB5KRB_AP_ERR_TKT_NYV;
 126     }
 127     return 0;
 128 }
 129
 130 /*
 131  * set the `et->caddr' to the most appropriate address to use, where
 132  * `addr' is the address the request was received from.
 133  */
 134
 135 static krb5_error_code
 136 set_address (krb5_context context,
 137              krb5_kdc_configuration *config,
 138              EncTicketPart *et,
 139              struct sockaddr *addr,
 140              const char *from)
 141 {
 142     krb5_error_code ret;
 143     krb5_address *v4_addr;
 144
 145     v4_addr = malloc (sizeof(*v4_addr));
 146     if (v4_addr == NULL)
 147         return ENOMEM;
 148
 149     ret = krb5_sockaddr2address(context, addr, v4_addr);
 150     if(ret) {
 151         free (v4_addr);
 152         kdc_log(context, config, 0, "Failed to convert address (%s)", from);
 153         return ret;
 154     }
 155
 156     if (et->caddr && !krb5_address_search (context, v4_addr, et->caddr)) {
 157         kdc_log(context, config, 0, "Incorrect network address (%s)", from);
 158         krb5_free_address(context, v4_addr);
 159         free (v4_addr);
 160         return KRB5KRB_AP_ERR_BADADDR;
 161     }
 162     if(v4_addr->addr_type == KRB5_ADDRESS_INET) {
 163         /* we need to collapse the addresses in the ticket to a
 164            single address; best guess is to use the address the
 165            connection came from */
 166
 167         if (et->caddr != NULL) {
 168             free_HostAddresses(et->caddr);
 169         } else {
 170             et->caddr = malloc (sizeof (*et->caddr));
 171             if (et->caddr == NULL) {
 172                 krb5_free_address(context, v4_addr);
 173                 free(v4_addr);
 174                 return ENOMEM;
 175             }
 176         }
 177         et->caddr->val = v4_addr;
 178         et->caddr->len = 1;
 179     } else {
 180         krb5_free_address(context, v4_addr);
 181         free(v4_addr);
 182     }
 183     return 0;
 184 }
 185
 186
 187 static krb5_error_code
 188 encrypt_v4_ticket(krb5_context context,
 189                   krb5_kdc_configuration *config,
 190                   void *buf,
 191                   size_t len,
 192                   krb5_keyblock *skey,
 193                   EncryptedData *reply)
 194 {
 195     krb5_crypto crypto;
 196     krb5_error_code ret;
 197     ret = krb5_crypto_init(context, skey, ETYPE_DES_PCBC_NONE, &crypto);
 198     if (ret) {
 199         free(buf);
 200         kdc_log(context, config, 0, "krb5_crypto_init failed: %s",
 201                 krb5_get_err_text(context, ret));
 202         return ret;
 203     }
 204
 205     ret = krb5_encrypt_EncryptedData(context,
 206                                      crypto,
 207                                      KRB5_KU_TICKET,
 208                                      buf,
 209                                      len,
 210                                      0,
 211                                      reply);
 212     krb5_crypto_destroy(context, crypto);
 213     if(ret) {
 214         kdc_log(context, config, 0, "Failed to encrypt data: %s",
 215                 krb5_get_err_text(context, ret));
 216         return ret;
 217     }
 218     return 0;
 219 }
 220
 221 static krb5_error_code
 222 encode_524_response(krb5_context context,
 223                     krb5_kdc_configuration *config,
 224                     const char *spn, const EncTicketPart et,
 225                     const Ticket *t, hdb_entry_ex *server,
 226                     EncryptedData *ticket, int *kvno)
 227 {
 228     krb5_error_code ret;
 229     int use_2b;
 230     size_t len;
 231
 232     use_2b = krb5_config_get_bool(context, NULL, "kdc", "use_2b", spn, NULL);
 233     if(use_2b) {
 234         ASN1_MALLOC_ENCODE(EncryptedData,
 235                            ticket->cipher.data, ticket->cipher.length,
 236                            &t->enc_part, &len, ret);
 237
 238         if (ret) {
 239             kdc_log(context, config, 0,
 240                     "Failed to encode v4 (2b) ticket (%s)", spn);
 241             return ret;
 242         }
 243
 244         ticket->etype = 0;
 245         ticket->kvno = NULL;
 246         *kvno = 213; /* 2b's use this magic kvno */
 247     } else {
 248         unsigned char buf[MAX_KTXT_LEN + 4 * 4];
 249         Key *skey;
 250
 251         if (!config->enable_v4_cross_realm && strcmp (et.crealm, t->realm) != 0) {
 252             kdc_log(context, config, 0, "524 cross-realm %s -> %s disabled", et.crealm,
 253                     t->realm);
 254             return KRB5KDC_ERR_POLICY;
 255         }
 256
 257         ret = _kdc_encode_v4_ticket(context, config,
 258                                     buf + sizeof(buf) - 1, sizeof(buf),
 259                                     &et, &t->sname, &len);
 260         if(ret){
 261             kdc_log(context, config, 0,
 262                     "Failed to encode v4 ticket (%s)", spn);
 263             return ret;
 264         }
 265         ret = _kdc_get_des_key(context, server, TRUE, FALSE, &skey);
 266         if(ret){
 267             kdc_log(context, config, 0,
 268                     "no suitable DES key for server (%s)", spn);
 269             return ret;
 270         }
 271         ret = encrypt_v4_ticket(context, config, buf + sizeof(buf) - len, len,
 272                                 &skey->key, ticket);
 273         if(ret){
 274             kdc_log(context, config, 0,
 275                     "Failed to encrypt v4 ticket (%s)", spn);
 276             return ret;
 277         }
 278         *kvno = server->entry.kvno;
 279     }
 280
 281     return 0;
 282 }
 283
 284 /*
 285  * process a 5->4 request, based on `t', and received `from, addr',
 286  * returning the reply in `reply'
 287  */
 288
 289 krb5_error_code
 290 _kdc_do_524(krb5_context context,
 291             krb5_kdc_configuration *config,
 292             const Ticket *t, krb5_data *reply,
 293             const char *from, struct sockaddr *addr)
 294 {
 295     krb5_error_code ret = 0;
 296     krb5_crypto crypto;
 297     hdb_entry_ex *server = NULL;
 298     Key *skey;
 299     krb5_data et_data;
 300     EncTicketPart et;
 301     EncryptedData ticket;
 302     krb5_storage *sp;
 303     char *spn = NULL;
 304     unsigned char buf[MAX_KTXT_LEN + 4 * 4];
 305     int kvno = 0;
 306
 307     if(!config->enable_524) {
 308         ret = KRB5KDC_ERR_POLICY;
 309         kdc_log(context, config, 0,
 310                 "Rejected ticket conversion request from %s", from);
 311         goto out;
 312     }
 313
 314     ret = fetch_server (context, config, t, &spn, &server, from);
 315     if (ret) {
 316         goto out;
 317     }
 318
 319     ret = hdb_enctype2key(context, &server->entry, t->enc_part.etype, &skey);
 320     if(ret){
 321         kdc_log(context, config, 0,
 322                 "No suitable key found for server (%s) from %s", spn, from);
 323         goto out;
 324     }
 325     ret = krb5_crypto_init(context, &skey->key, 0, &crypto);
 326     if (ret) {
 327         kdc_log(context, config, 0, "krb5_crypto_init failed: %s",
 328                 krb5_get_err_text(context, ret));
 329         goto out;
 330     }
 331     ret = krb5_decrypt_EncryptedData (context,
 332                                       crypto,
 333                                       KRB5_KU_TICKET,
 334                                       &t->enc_part,
 335                                       &et_data);
 336     krb5_crypto_destroy(context, crypto);
 337     if(ret){
 338         kdc_log(context, config, 0,
 339                 "Failed to decrypt ticket from %s for %s", from, spn);
 340         goto out;
 341     }
 342     ret = decode_EncTicketPart(et_data.data, et_data.length, &et, NULL);
 343     krb5_data_free(&et_data);
 344     if(ret){
 345         kdc_log(context, config, 0,
 346                 "Failed to decode ticket from %s for %s", from, spn);
 347         goto out;
 348     }
 349
 350     ret = log_524 (context, config, &et, from, spn);
 351     if (ret) {
 352         free_EncTicketPart(&et);
 353         goto out;
 354     }
 355
 356     ret = verify_flags (context, config, &et, spn);
 357     if (ret) {
 358         free_EncTicketPart(&et);
 359         goto out;
 360     }
 361
 362     ret = set_address (context, config, &et, addr, from);
 363     if (ret) {
 364         free_EncTicketPart(&et);
 365         goto out;
 366     }
 367
 368     ret = encode_524_response(context, config, spn, et, t,
 369                               server, &ticket, &kvno);
 370     free_EncTicketPart(&et);
 371
 372  out:
 373     /* make reply */
 374     memset(buf, 0, sizeof(buf));
 375     sp = krb5_storage_from_mem(buf, sizeof(buf));
 376     if (sp) {
 377         krb5_store_int32(sp, ret);
 378         if(ret == 0){
 379             krb5_store_int32(sp, kvno);
 380             krb5_store_data(sp, ticket.cipher);
 381             /* Aargh! This is coded as a KTEXT_ST. */
 382             krb5_storage_seek(sp, MAX_KTXT_LEN - ticket.cipher.length, SEEK_CUR);
 383             krb5_store_int32(sp, 0); /* mbz */
 384             free_EncryptedData(&ticket);
 385         }
 386         ret = krb5_storage_to_data(sp, reply);
 387         reply->length = krb5_storage_seek(sp, 0, SEEK_CUR);
 388         krb5_storage_free(sp);
 389     } else
 390         krb5_data_zero(reply);
 391     if(spn)
 392         free(spn);
 393     if(server)
 394         _kdc_free_ent (context, server);
 395     return ret;
 396 }