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   EVP_MD_CTX md5;
 206   u_char hash[16];
 207   DES_key_schedule schedule;
 208   EVP_CIPHER_CTX des_ctx;
 209   DES_cblock deskey;
 210   DES_cblock zero;
 211   int i;
 212   int32_t seq_number;
 213   size_t len, total_len, padlength, datalen;
 214
 215   if (IS_DCE_STYLE(ctx)) {
 216     padlength = 0;
 217     datalen = input_message_buffer->length;
 218     len = 22 + 8;
 219     _gsskrb5_encap_length (len, &len, &total_len, GSS_KRB5_MECHANISM);
 220     total_len += datalen;
 221     datalen += 8;
 222   } else {
 223     padlength = 8 - (input_message_buffer->length % 8);
 224     datalen = input_message_buffer->length + padlength + 8;
 225     len = datalen + 22;
 226     _gsskrb5_encap_length (len, &len, &total_len, GSS_KRB5_MECHANISM);
 227   }
 228
 229   output_message_buffer->length = total_len;
 230   output_message_buffer->value  = malloc (total_len);
 231   if (output_message_buffer->value == NULL) {
 232     output_message_buffer->length = 0;
 233     *minor_status = ENOMEM;
 234     return GSS_S_FAILURE;
 235   }
 236
 237   p = _gsskrb5_make_header(output_message_buffer->value,
 238                               len,
 239                               "\x02\x01", /* TOK_ID */
 240                               GSS_KRB5_MECHANISM);
 241
 242   /* SGN_ALG */
 243   memcpy (p, "\x00\x00", 2);
 244   p += 2;
 245   /* SEAL_ALG */
 246   if(conf_req_flag)
 247       memcpy (p, "\x00\x00", 2);
 248   else
 249       memcpy (p, "\xff\xff", 2);
 250   p += 2;
 251   /* Filler */
 252   memcpy (p, "\xff\xff", 2);
 253   p += 2;
 254
 255   /* fill in later */
 256   memset (p, 0, 16);
 257   p += 16;
 258
 259   /* confounder + data + pad */
 260   krb5_generate_random_block(p, 8);
 261   memcpy (p + 8, input_message_buffer->value,
 262           input_message_buffer->length);
 263   memset (p + 8 + input_message_buffer->length, padlength, padlength);
 264
 265   /* checksum */
 266   EVP_MD_CTX_init(&md5);
 267   EVP_DigestInit_ex(&md5, EVP_md5(), NULL);
 268   EVP_DigestUpdate(&md5, p - 24, 8);
 269   EVP_DigestUpdate(&md5, p, datalen);
 270   EVP_DigestFinal_ex(&md5, hash, NULL);
 271   EVP_MD_CTX_cleanup(&md5);
 272
 273   memset (&zero, 0, sizeof(zero));
 274   memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
 275   DES_set_key_unchecked (&deskey, &schedule);
 276   DES_cbc_cksum ((void *)hash, (void *)hash, sizeof(hash),
 277                  &schedule, &zero);
 278   memcpy (p - 8, hash, 8);
 279
 280   /* sequence number */
 281   HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
 282   krb5_auth_con_getlocalseqnumber (context,
 283                                    ctx->auth_context,
 284                                    &seq_number);
 285
 286   p -= 16;
 287   p[0] = (seq_number >> 0)  & 0xFF;
 288   p[1] = (seq_number >> 8)  & 0xFF;
 289   p[2] = (seq_number >> 16) & 0xFF;
 290   p[3] = (seq_number >> 24) & 0xFF;
 291   memset (p + 4,
 292           (ctx->more_flags & LOCAL) ? 0 : 0xFF,
 293           4);
 294
 295   EVP_CIPHER_CTX_init(&des_ctx);
 296   EVP_CipherInit_ex(&des_ctx, EVP_des_cbc(), NULL, key->keyvalue.data, p + 8, 1);
 297   EVP_Cipher(&des_ctx, p, p, 8);
 298   EVP_CIPHER_CTX_cleanup(&des_ctx);
 299
 300   krb5_auth_con_setlocalseqnumber (context,
 301                                ctx->auth_context,
 302                                ++seq_number);
 303   HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 304
 305   /* encrypt the data */
 306   p += 16;
 307
 308   if(conf_req_flag) {
 309       memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
 310
 311       for (i = 0; i < sizeof(deskey); ++i)
 312           deskey[i] ^= 0xf0;
 313
 314       EVP_CIPHER_CTX_init(&des_ctx);
 315       EVP_CipherInit_ex(&des_ctx, EVP_des_cbc(), NULL, deskey, zero, 1);
 316       EVP_Cipher(&des_ctx, p, p, datalen);
 317       EVP_CIPHER_CTX_cleanup(&des_ctx);
 318   }
 319   memset (deskey, 0, sizeof(deskey));
 320   memset (&schedule, 0, sizeof(schedule));
 321
 322   if(conf_state != NULL)
 323       *conf_state = conf_req_flag;
 324   *minor_status = 0;
 325   return GSS_S_COMPLETE;
 326 }
 327
 328 static OM_uint32
 329 wrap_des3
 330            (OM_uint32 * minor_status,
 331             const gsskrb5_ctx ctx,
 332             krb5_context context,
 333             int conf_req_flag,
 334             gss_qop_t qop_req,
 335             const gss_buffer_t input_message_buffer,
 336             int * conf_state,
 337             gss_buffer_t output_message_buffer,
 338             krb5_keyblock *key
 339            )
 340 {
 341   u_char *p;
 342   u_char seq[8];
 343   int32_t seq_number;
 344   size_t len, total_len, padlength, datalen;
 345   uint32_t ret;
 346   krb5_crypto crypto;
 347   Checksum cksum;
 348   krb5_data encdata;
 349
 350   if (IS_DCE_STYLE(ctx)) {
 351     padlength = 0;
 352     datalen = input_message_buffer->length;
 353     len = 34 + 8;
 354     _gsskrb5_encap_length (len, &len, &total_len, GSS_KRB5_MECHANISM);
 355     total_len += datalen;
 356     datalen += 8;
 357   } else {
 358     padlength = 8 - (input_message_buffer->length % 8);
 359     datalen = input_message_buffer->length + padlength + 8;
 360     len = datalen + 34;
 361     _gsskrb5_encap_length (len, &len, &total_len, GSS_KRB5_MECHANISM);
 362   }
 363
 364   output_message_buffer->length = total_len;
 365   output_message_buffer->value  = malloc (total_len);
 366   if (output_message_buffer->value == NULL) {
 367     output_message_buffer->length = 0;
 368     *minor_status = ENOMEM;
 369     return GSS_S_FAILURE;
 370   }
 371
 372   p = _gsskrb5_make_header(output_message_buffer->value,
 373                               len,
 374                               "\x02\x01", /* TOK_ID */
 375                               GSS_KRB5_MECHANISM);
 376
 377   /* SGN_ALG */
 378   memcpy (p, "\x04\x00", 2);    /* HMAC SHA1 DES3-KD */
 379   p += 2;
 380   /* SEAL_ALG */
 381   if(conf_req_flag)
 382       memcpy (p, "\x02\x00", 2); /* DES3-KD */
 383   else
 384       memcpy (p, "\xff\xff", 2);
 385   p += 2;
 386   /* Filler */
 387   memcpy (p, "\xff\xff", 2);
 388   p += 2;
 389
 390   /* calculate checksum (the above + confounder + data + pad) */
 391
 392   memcpy (p + 20, p - 8, 8);
 393   krb5_generate_random_block(p + 28, 8);
 394   memcpy (p + 28 + 8, input_message_buffer->value,
 395           input_message_buffer->length);
 396   memset (p + 28 + 8 + input_message_buffer->length, padlength, padlength);
 397
 398   ret = krb5_crypto_init(context, key, 0, &crypto);
 399   if (ret) {
 400       free (output_message_buffer->value);
 401       output_message_buffer->length = 0;
 402       output_message_buffer->value = NULL;
 403       *minor_status = ret;
 404       return GSS_S_FAILURE;
 405   }
 406
 407   ret = krb5_create_checksum (context,
 408                               crypto,
 409                               KRB5_KU_USAGE_SIGN,
 410                               0,
 411                               p + 20,
 412                               datalen + 8,
 413                               &cksum);
 414   krb5_crypto_destroy (context, crypto);
 415   if (ret) {
 416       free (output_message_buffer->value);
 417       output_message_buffer->length = 0;
 418       output_message_buffer->value = NULL;
 419       *minor_status = ret;
 420       return GSS_S_FAILURE;
 421   }
 422
 423   /* zero out SND_SEQ + SGN_CKSUM in case */
 424   memset (p, 0, 28);
 425
 426   memcpy (p + 8, cksum.checksum.data, cksum.checksum.length);
 427   free_Checksum (&cksum);
 428
 429   HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
 430   /* sequence number */
 431   krb5_auth_con_getlocalseqnumber (context,
 432                                ctx->auth_context,
 433                                &seq_number);
 434
 435   seq[0] = (seq_number >> 0)  & 0xFF;
 436   seq[1] = (seq_number >> 8)  & 0xFF;
 437   seq[2] = (seq_number >> 16) & 0xFF;
 438   seq[3] = (seq_number >> 24) & 0xFF;
 439   memset (seq + 4,
 440           (ctx->more_flags & LOCAL) ? 0 : 0xFF,
 441           4);
 442
 443
 444   ret = krb5_crypto_init(context, key, ETYPE_DES3_CBC_NONE,
 445                          &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   {
 455       DES_cblock ivec;
 456
 457       memcpy (&ivec, p + 8, 8);
 458       ret = krb5_encrypt_ivec (context,
 459                                crypto,
 460                                KRB5_KU_USAGE_SEQ,
 461                                seq, 8, &encdata,
 462                                &ivec);
 463   }
 464   krb5_crypto_destroy (context, crypto);
 465   if (ret) {
 466       free (output_message_buffer->value);
 467       output_message_buffer->length = 0;
 468       output_message_buffer->value = NULL;
 469       *minor_status = ret;
 470       return GSS_S_FAILURE;
 471   }
 472
 473   assert (encdata.length == 8);
 474
 475   memcpy (p, encdata.data, encdata.length);
 476   krb5_data_free (&encdata);
 477
 478   krb5_auth_con_setlocalseqnumber (context,
 479                                ctx->auth_context,
 480                                ++seq_number);
 481   HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 482
 483   /* encrypt the data */
 484   p += 28;
 485
 486   if(conf_req_flag) {
 487       krb5_data tmp;
 488
 489       ret = krb5_crypto_init(context, key,
 490                              ETYPE_DES3_CBC_NONE, &crypto);
 491       if (ret) {
 492           free (output_message_buffer->value);
 493           output_message_buffer->length = 0;
 494           output_message_buffer->value = NULL;
 495           *minor_status = ret;
 496           return GSS_S_FAILURE;
 497       }
 498       ret = krb5_encrypt(context, crypto, KRB5_KU_USAGE_SEAL,
 499                          p, datalen, &tmp);
 500       krb5_crypto_destroy(context, crypto);
 501       if (ret) {
 502           free (output_message_buffer->value);
 503           output_message_buffer->length = 0;
 504           output_message_buffer->value = NULL;
 505           *minor_status = ret;
 506           return GSS_S_FAILURE;
 507       }
 508       assert (tmp.length == datalen);
 509
 510       memcpy (p, tmp.data, datalen);
 511       krb5_data_free(&tmp);
 512   }
 513   if(conf_state != NULL)
 514       *conf_state = conf_req_flag;
 515   *minor_status = 0;
 516   return GSS_S_COMPLETE;
 517 }
 518
 519 OM_uint32 _gsskrb5_wrap
 520            (OM_uint32 * minor_status,
 521             const gss_ctx_id_t context_handle,
 522             int conf_req_flag,
 523             gss_qop_t qop_req,
 524             const gss_buffer_t input_message_buffer,
 525             int * conf_state,
 526             gss_buffer_t output_message_buffer
 527            )
 528 {
 529   krb5_context context;
 530   krb5_keyblock *key;
 531   OM_uint32 ret;
 532   krb5_keytype keytype;
 533   const gsskrb5_ctx ctx = (const gsskrb5_ctx) context_handle;
 534
 535   output_message_buffer->value = NULL;
 536   output_message_buffer->length = 0;
 537
 538   GSSAPI_KRB5_INIT (&context);
 539
 540   if (ctx->more_flags & IS_CFX)
 541       return _gssapi_wrap_cfx (minor_status, ctx, context, conf_req_flag,
 542                                input_message_buffer, conf_state,
 543                                output_message_buffer);
 544
 545   HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
 546   ret = _gsskrb5i_get_token_key(ctx, context, &key);
 547   HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 548   if (ret) {
 549       *minor_status = ret;
 550       return GSS_S_FAILURE;
 551   }
 552   krb5_enctype_to_keytype (context, key->keytype, &keytype);
 553
 554   switch (keytype) {
 555   case KEYTYPE_DES :
 556       ret = wrap_des (minor_status, ctx, context, conf_req_flag,
 557                       qop_req, input_message_buffer, conf_state,
 558                       output_message_buffer, key);
 559       break;
 560   case KEYTYPE_DES3 :
 561       ret = wrap_des3 (minor_status, ctx, context, conf_req_flag,
 562                        qop_req, input_message_buffer, conf_state,
 563                        output_message_buffer, key);
 564       break;
 565   case KEYTYPE_ARCFOUR:
 566   case KEYTYPE_ARCFOUR_56:
 567       ret = _gssapi_wrap_arcfour (minor_status, ctx, context, conf_req_flag,
 568                                   qop_req, input_message_buffer, conf_state,
 569                                   output_message_buffer, key);
 570       break;
 571   default :
 572       abort();
 573       break;
 574   }
 575   krb5_free_keyblock (context, key);
 576   return ret;
 577 }