lib/gssapi/krb5/wrap.c

   1 /*
   2  * Copyright (c) 1997 - 2003 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 "gsskrb5_locl.h"
  35
  36 /*
  37  * Return initiator subkey, or if that doesn't exists, the subkey.
  38  */
  39
  40 krb5_error_code
  41 _gsskrb5i_get_initiator_subkey(const gsskrb5_ctx ctx,
  42                                krb5_context context,
  43                                krb5_keyblock **key)
  44 {
  45     krb5_error_code ret;
  46     *key = NULL;
  47
  48     if (ctx->more_flags & LOCAL) {
  49         ret = krb5_auth_con_getlocalsubkey(context,
  50                                      ctx->auth_context,
  51                                      key);
  52     } else {
  53         ret = krb5_auth_con_getremotesubkey(context,
  54                                       ctx->auth_context,
  55                                       key);
  56     }
  57     if (ret == 0 && *key == NULL)
  58         ret = krb5_auth_con_getkey(context,
  59                                    ctx->auth_context,
  60                                    key);
  61     if (ret == 0 && *key == NULL) {
  62         krb5_set_error_message(context, 0, "No initiator subkey available");
  63         return GSS_KRB5_S_KG_NO_SUBKEY;
  64     }
  65     return ret;
  66 }
  67
  68 krb5_error_code
  69 _gsskrb5i_get_acceptor_subkey(const gsskrb5_ctx ctx,
  70                               krb5_context context,
  71                               krb5_keyblock **key)
  72 {
  73     krb5_error_code ret;
  74     *key = NULL;
  75
  76     if (ctx->more_flags & LOCAL) {
  77         ret = krb5_auth_con_getremotesubkey(context,
  78                                       ctx->auth_context,
  79                                       key);
  80     } else {
  81         ret = krb5_auth_con_getlocalsubkey(context,
  82                                      ctx->auth_context,
  83                                      key);
  84     }
  85     if (ret == 0 && *key == NULL) {
  86         krb5_set_error_message(context, 0, "No acceptor subkey available");
  87         return GSS_KRB5_S_KG_NO_SUBKEY;
  88     }
  89     return ret;
  90 }
  91
  92 OM_uint32
  93 _gsskrb5i_get_token_key(const gsskrb5_ctx ctx,
  94                         krb5_context context,
  95                         krb5_keyblock **key)
  96 {
  97     _gsskrb5i_get_acceptor_subkey(ctx, context, key);
  98     if(*key == NULL) {
  99         /*
 100          * Only use the initiator subkey or ticket session key if an
 101          * acceptor subkey was not required.
 102          */
 103         if ((ctx->more_flags & ACCEPTOR_SUBKEY) == 0)
 104             _gsskrb5i_get_initiator_subkey(ctx, context, key);
 105     }
 106     if (*key == NULL) {
 107         krb5_set_error_message(context, 0, "No token key available");
 108         return GSS_KRB5_S_KG_NO_SUBKEY;
 109     }
 110     return 0;
 111 }
 112
 113 static OM_uint32
 114 sub_wrap_size (
 115             OM_uint32 req_output_size,
 116             OM_uint32 * max_input_size,
 117             int blocksize,
 118             int extrasize
 119            )
 120 {
 121     size_t len, total_len;
 122
 123     len = 8 + req_output_size + blocksize + extrasize;
 124
 125     _gsskrb5_encap_length(len, &len, &total_len, GSS_KRB5_MECHANISM);
 126
 127     total_len -= req_output_size; /* token length */
 128     if (total_len < req_output_size) {
 129         *max_input_size = (req_output_size - total_len);
 130         (*max_input_size) &= (~(OM_uint32)(blocksize - 1));
 131     } else {
 132         *max_input_size = 0;
 133     }
 134     return GSS_S_COMPLETE;
 135 }
 136
 137 OM_uint32
 138 _gsskrb5_wrap_size_limit (
 139             OM_uint32 * minor_status,
 140             const gss_ctx_id_t context_handle,
 141             int conf_req_flag,
 142             gss_qop_t qop_req,
 143             OM_uint32 req_output_size,
 144             OM_uint32 * max_input_size
 145            )
 146 {
 147   krb5_context context;
 148   krb5_keyblock *key;
 149   OM_uint32 ret;
 150   krb5_keytype keytype;
 151   const gsskrb5_ctx ctx = (const gsskrb5_ctx) context_handle;
 152
 153   GSSAPI_KRB5_INIT (&context);
 154
 155   if (ctx->more_flags & IS_CFX)
 156       return _gssapi_wrap_size_cfx(minor_status, ctx, context,
 157                                    conf_req_flag, qop_req,
 158                                    req_output_size, max_input_size);
 159
 160   HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
 161   ret = _gsskrb5i_get_token_key(ctx, context, &key);
 162   HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 163   if (ret) {
 164       *minor_status = ret;
 165       return GSS_S_FAILURE;
 166   }
 167   krb5_enctype_to_keytype (context, key->keytype, &keytype);
 168
 169   switch (keytype) {
 170   case KEYTYPE_DES :
 171       ret = sub_wrap_size(req_output_size, max_input_size, 8, 22);
 172       break;
 173   case KEYTYPE_ARCFOUR:
 174   case KEYTYPE_ARCFOUR_56:
 175       ret = _gssapi_wrap_size_arcfour(minor_status, ctx, context,
 176                                       conf_req_flag, qop_req,
 177                                       req_output_size, max_input_size, key);
 178       break;
 179   case KEYTYPE_DES3 :
 180       ret = sub_wrap_size(req_output_size, max_input_size, 8, 34);
 181       break;
 182   default :
 183       abort();
 184       break;
 185   }
 186   krb5_free_keyblock (context, key);
 187   *minor_status = 0;
 188   return ret;
 189 }
 190
 191 static OM_uint32
 192 wrap_des
 193            (OM_uint32 * minor_status,
 194             const gsskrb5_ctx ctx,
 195             krb5_context context,
 196             int conf_req_flag,
 197             gss_qop_t qop_req,
 198             const gss_buffer_t input_message_buffer,
 199             int * conf_state,
 200             gss_buffer_t output_message_buffer,
 201             krb5_keyblock *key
 202            )
 203 {
 204   u_char *p;
 205   MD5_CTX md5;
 206   u_char hash[16];
 207   DES_key_schedule schedule;
 208   DES_cblock deskey;
 209   DES_cblock zero;
 210   int i;
 211   int32_t seq_number;
 212   size_t len, total_len, padlength, datalen;
 213
 214   padlength = 8 - (input_message_buffer->length % 8);
 215   datalen = input_message_buffer->length + padlength + 8;
 216   len = datalen + 22;
 217   _gsskrb5_encap_length (len, &len, &total_len, GSS_KRB5_MECHANISM);
 218
 219   output_message_buffer->length = total_len;
 220   output_message_buffer->value  = malloc (total_len);
 221   if (output_message_buffer->value == NULL) {
 222     output_message_buffer->length = 0;
 223     *minor_status = ENOMEM;
 224     return GSS_S_FAILURE;
 225   }
 226
 227   p = _gsskrb5_make_header(output_message_buffer->value,
 228                               len,
 229                               "\x02\x01", /* TOK_ID */
 230                               GSS_KRB5_MECHANISM);
 231
 232   /* SGN_ALG */
 233   memcpy (p, "\x00\x00", 2);
 234   p += 2;
 235   /* SEAL_ALG */
 236   if(conf_req_flag)
 237       memcpy (p, "\x00\x00", 2);
 238   else
 239       memcpy (p, "\xff\xff", 2);
 240   p += 2;
 241   /* Filler */
 242   memcpy (p, "\xff\xff", 2);
 243   p += 2;
 244
 245   /* fill in later */
 246   memset (p, 0, 16);
 247   p += 16;
 248
 249   /* confounder + data + pad */
 250   krb5_generate_random_block(p, 8);
 251   memcpy (p + 8, input_message_buffer->value,
 252           input_message_buffer->length);
 253   memset (p + 8 + input_message_buffer->length, padlength, padlength);
 254
 255   /* checksum */
 256   MD5_Init (&md5);
 257   MD5_Update (&md5, p - 24, 8);
 258   MD5_Update (&md5, p, datalen);
 259   MD5_Final (hash, &md5);
 260
 261   memset (&zero, 0, sizeof(zero));
 262   memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
 263   DES_set_key_unchecked (&deskey, &schedule);
 264   DES_cbc_cksum ((void *)hash, (void *)hash, sizeof(hash),
 265                  &schedule, &zero);
 266   memcpy (p - 8, hash, 8);
 267
 268   /* sequence number */
 269   HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
 270   krb5_auth_con_getlocalseqnumber (context,
 271                                    ctx->auth_context,
 272                                    &seq_number);
 273
 274   p -= 16;
 275   p[0] = (seq_number >> 0)  & 0xFF;
 276   p[1] = (seq_number >> 8)  & 0xFF;
 277   p[2] = (seq_number >> 16) & 0xFF;
 278   p[3] = (seq_number >> 24) & 0xFF;
 279   memset (p + 4,
 280           (ctx->more_flags & LOCAL) ? 0 : 0xFF,
 281           4);
 282
 283   DES_set_key_unchecked (&deskey, &schedule);
 284   DES_cbc_encrypt ((void *)p, (void *)p, 8,
 285                    &schedule, (DES_cblock *)(p + 8), DES_ENCRYPT);
 286
 287   krb5_auth_con_setlocalseqnumber (context,
 288                                ctx->auth_context,
 289                                ++seq_number);
 290   HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 291
 292   /* encrypt the data */
 293   p += 16;
 294
 295   if(conf_req_flag) {
 296       memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
 297
 298       for (i = 0; i < sizeof(deskey); ++i)
 299           deskey[i] ^= 0xf0;
 300       DES_set_key_unchecked (&deskey, &schedule);
 301       memset (&zero, 0, sizeof(zero));
 302       DES_cbc_encrypt ((void *)p,
 303                        (void *)p,
 304                        datalen,
 305                        &schedule,
 306                        &zero,
 307                        DES_ENCRYPT);
 308   }
 309   memset (deskey, 0, sizeof(deskey));
 310   memset (&schedule, 0, sizeof(schedule));
 311
 312   if(conf_state != NULL)
 313       *conf_state = conf_req_flag;
 314   *minor_status = 0;
 315   return GSS_S_COMPLETE;
 316 }
 317
 318 static OM_uint32
 319 wrap_des3
 320            (OM_uint32 * minor_status,
 321             const gsskrb5_ctx ctx,
 322             krb5_context context,
 323             int conf_req_flag,
 324             gss_qop_t qop_req,
 325             const gss_buffer_t input_message_buffer,
 326             int * conf_state,
 327             gss_buffer_t output_message_buffer,
 328             krb5_keyblock *key
 329            )
 330 {
 331   u_char *p;
 332   u_char seq[8];
 333   int32_t seq_number;
 334   size_t len, total_len, padlength, datalen;
 335   uint32_t ret;
 336   krb5_crypto crypto;
 337   Checksum cksum;
 338   krb5_data encdata;
 339
 340   padlength = 8 - (input_message_buffer->length % 8);
 341   datalen = input_message_buffer->length + padlength + 8;
 342   len = datalen + 34;
 343   _gsskrb5_encap_length (len, &len, &total_len, GSS_KRB5_MECHANISM);
 344
 345   output_message_buffer->length = total_len;
 346   output_message_buffer->value  = malloc (total_len);
 347   if (output_message_buffer->value == NULL) {
 348     output_message_buffer->length = 0;
 349     *minor_status = ENOMEM;
 350     return GSS_S_FAILURE;
 351   }
 352
 353   p = _gsskrb5_make_header(output_message_buffer->value,
 354                               len,
 355                               "\x02\x01", /* TOK_ID */
 356                               GSS_KRB5_MECHANISM);
 357
 358   /* SGN_ALG */
 359   memcpy (p, "\x04\x00", 2);    /* HMAC SHA1 DES3-KD */
 360   p += 2;
 361   /* SEAL_ALG */
 362   if(conf_req_flag)
 363       memcpy (p, "\x02\x00", 2); /* DES3-KD */
 364   else
 365       memcpy (p, "\xff\xff", 2);
 366   p += 2;
 367   /* Filler */
 368   memcpy (p, "\xff\xff", 2);
 369   p += 2;
 370
 371   /* calculate checksum (the above + confounder + data + pad) */
 372
 373   memcpy (p + 20, p - 8, 8);
 374   krb5_generate_random_block(p + 28, 8);
 375   memcpy (p + 28 + 8, input_message_buffer->value,
 376           input_message_buffer->length);
 377   memset (p + 28 + 8 + input_message_buffer->length, padlength, padlength);
 378
 379   ret = krb5_crypto_init(context, key, 0, &crypto);
 380   if (ret) {
 381       free (output_message_buffer->value);
 382       output_message_buffer->length = 0;
 383       output_message_buffer->value = NULL;
 384       *minor_status = ret;
 385       return GSS_S_FAILURE;
 386   }
 387
 388   ret = krb5_create_checksum (context,
 389                               crypto,
 390                               KRB5_KU_USAGE_SIGN,
 391                               0,
 392                               p + 20,
 393                               datalen + 8,
 394                               &cksum);
 395   krb5_crypto_destroy (context, crypto);
 396   if (ret) {
 397       free (output_message_buffer->value);
 398       output_message_buffer->length = 0;
 399       output_message_buffer->value = NULL;
 400       *minor_status = ret;
 401       return GSS_S_FAILURE;
 402   }
 403
 404   /* zero out SND_SEQ + SGN_CKSUM in case */
 405   memset (p, 0, 28);
 406
 407   memcpy (p + 8, cksum.checksum.data, cksum.checksum.length);
 408   free_Checksum (&cksum);
 409
 410   HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
 411   /* sequence number */
 412   krb5_auth_con_getlocalseqnumber (context,
 413                                ctx->auth_context,
 414                                &seq_number);
 415
 416   seq[0] = (seq_number >> 0)  & 0xFF;
 417   seq[1] = (seq_number >> 8)  & 0xFF;
 418   seq[2] = (seq_number >> 16) & 0xFF;
 419   seq[3] = (seq_number >> 24) & 0xFF;
 420   memset (seq + 4,
 421           (ctx->more_flags & LOCAL) ? 0 : 0xFF,
 422           4);
 423
 424
 425   ret = krb5_crypto_init(context, key, ETYPE_DES3_CBC_NONE,
 426                          &crypto);
 427   if (ret) {
 428       free (output_message_buffer->value);
 429       output_message_buffer->length = 0;
 430       output_message_buffer->value = NULL;
 431       *minor_status = ret;
 432       return GSS_S_FAILURE;
 433   }
 434
 435   {
 436       DES_cblock ivec;
 437
 438       memcpy (&ivec, p + 8, 8);
 439       ret = krb5_encrypt_ivec (context,
 440                                crypto,
 441                                KRB5_KU_USAGE_SEQ,
 442                                seq, 8, &encdata,
 443                                &ivec);
 444   }
 445   krb5_crypto_destroy (context, crypto);
 446   if (ret) {
 447       free (output_message_buffer->value);
 448       output_message_buffer->length = 0;
 449       output_message_buffer->value = NULL;
 450       *minor_status = ret;
 451       return GSS_S_FAILURE;
 452   }
 453
 454   assert (encdata.length == 8);
 455
 456   memcpy (p, encdata.data, encdata.length);
 457   krb5_data_free (&encdata);
 458
 459   krb5_auth_con_setlocalseqnumber (context,
 460                                ctx->auth_context,
 461                                ++seq_number);
 462   HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 463
 464   /* encrypt the data */
 465   p += 28;
 466
 467   if(conf_req_flag) {
 468       krb5_data tmp;
 469
 470       ret = krb5_crypto_init(context, key,
 471                              ETYPE_DES3_CBC_NONE, &crypto);
 472       if (ret) {
 473           free (output_message_buffer->value);
 474           output_message_buffer->length = 0;
 475           output_message_buffer->value = NULL;
 476           *minor_status = ret;
 477           return GSS_S_FAILURE;
 478       }
 479       ret = krb5_encrypt(context, crypto, KRB5_KU_USAGE_SEAL,
 480                          p, datalen, &tmp);
 481       krb5_crypto_destroy(context, crypto);
 482       if (ret) {
 483           free (output_message_buffer->value);
 484           output_message_buffer->length = 0;
 485           output_message_buffer->value = NULL;
 486           *minor_status = ret;
 487           return GSS_S_FAILURE;
 488       }
 489       assert (tmp.length == datalen);
 490
 491       memcpy (p, tmp.data, datalen);
 492       krb5_data_free(&tmp);
 493   }
 494   if(conf_state != NULL)
 495       *conf_state = conf_req_flag;
 496   *minor_status = 0;
 497   return GSS_S_COMPLETE;
 498 }
 499
 500 OM_uint32 _gsskrb5_wrap
 501            (OM_uint32 * minor_status,
 502             const gss_ctx_id_t context_handle,
 503             int conf_req_flag,
 504             gss_qop_t qop_req,
 505             const gss_buffer_t input_message_buffer,
 506             int * conf_state,
 507             gss_buffer_t output_message_buffer
 508            )
 509 {
 510   krb5_context context;
 511   krb5_keyblock *key;
 512   OM_uint32 ret;
 513   krb5_keytype keytype;
 514   const gsskrb5_ctx ctx = (const gsskrb5_ctx) context_handle;
 515
 516   output_message_buffer->value = NULL;
 517   output_message_buffer->length = 0;
 518
 519   GSSAPI_KRB5_INIT (&context);
 520
 521   if (ctx->more_flags & IS_CFX)
 522       return _gssapi_wrap_cfx (minor_status, ctx, context, conf_req_flag,
 523                                input_message_buffer, conf_state,
 524                                output_message_buffer);
 525
 526   HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
 527   ret = _gsskrb5i_get_token_key(ctx, context, &key);
 528   HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 529   if (ret) {
 530       *minor_status = ret;
 531       return GSS_S_FAILURE;
 532   }
 533   krb5_enctype_to_keytype (context, key->keytype, &keytype);
 534
 535   switch (keytype) {
 536   case KEYTYPE_DES :
 537       ret = wrap_des (minor_status, ctx, context, conf_req_flag,
 538                       qop_req, input_message_buffer, conf_state,
 539                       output_message_buffer, key);
 540       break;
 541   case KEYTYPE_DES3 :
 542       ret = wrap_des3 (minor_status, ctx, context, conf_req_flag,
 543                        qop_req, input_message_buffer, conf_state,
 544                        output_message_buffer, key);
 545       break;
 546   case KEYTYPE_ARCFOUR:
 547   case KEYTYPE_ARCFOUR_56:
 548       ret = _gssapi_wrap_arcfour (minor_status, ctx, context, conf_req_flag,
 549                                   qop_req, input_message_buffer, conf_state,
 550                                   output_message_buffer, key);
 551       break;
 552   default :
 553       abort();
 554       break;
 555   }
 556   krb5_free_keyblock (context, key);
 557   return ret;
 558 }