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 GSSAPI_CALLCONV
 138 _gsskrb5_wrap_size_limit (
 139             OM_uint32 * minor_status,
 140             gss_const_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   const gsskrb5_ctx ctx = (const gsskrb5_ctx) context_handle;
 151
 152   GSSAPI_KRB5_INIT (&context);
 153
 154   if (ctx->more_flags & IS_CFX)
 155       return _gssapi_wrap_size_cfx(minor_status, ctx, context,
 156                                    conf_req_flag, qop_req,
 157                                    req_output_size, max_input_size);
 158
 159   HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
 160   ret = _gsskrb5i_get_token_key(ctx, context, &key);
 161   HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 162   if (ret) {
 163       *minor_status = ret;
 164       return GSS_S_FAILURE;
 165   }
 166
 167   switch (key->keytype) {
 168   case KRB5_ENCTYPE_DES_CBC_CRC :
 169   case KRB5_ENCTYPE_DES_CBC_MD4 :
 170   case KRB5_ENCTYPE_DES_CBC_MD5 :
 171 #ifdef HEIM_WEAK_CRYPTO
 172       ret = sub_wrap_size(req_output_size, max_input_size, 8, 22);
 173 #else
 174       ret = GSS_S_FAILURE;
 175 #endif
 176       break;
 177   case KRB5_ENCTYPE_ARCFOUR_HMAC_MD5:
 178   case KRB5_ENCTYPE_ARCFOUR_HMAC_MD5_56:
 179       ret = _gssapi_wrap_size_arcfour(minor_status, ctx, context,
 180                                       conf_req_flag, qop_req,
 181                                       req_output_size, max_input_size, key);
 182       break;
 183   case KRB5_ENCTYPE_DES3_CBC_MD5 :
 184   case KRB5_ENCTYPE_DES3_CBC_SHA1 :
 185       ret = sub_wrap_size(req_output_size, max_input_size, 8, 34);
 186       break;
 187   default :
 188       abort();
 189       break;
 190   }
 191   krb5_free_keyblock (context, key);
 192   *minor_status = 0;
 193   return ret;
 194 }
 195
 196 #ifdef HEIM_WEAK_CRYPTO
 197
 198 static OM_uint32
 199 wrap_des
 200            (OM_uint32 * minor_status,
 201             const gsskrb5_ctx ctx,
 202             krb5_context context,
 203             int conf_req_flag,
 204             gss_qop_t qop_req,
 205             const gss_buffer_t input_message_buffer,
 206             int * conf_state,
 207             gss_buffer_t output_message_buffer,
 208             krb5_keyblock *key
 209            )
 210 {
 211   u_char *p;
 212   EVP_MD_CTX *md5;
 213   u_char hash[16];
 214   DES_key_schedule schedule;
 215   EVP_CIPHER_CTX des_ctx;
 216   DES_cblock deskey;
 217   DES_cblock zero;
 218   size_t i;
 219   int32_t seq_number;
 220   size_t len, total_len, padlength, datalen;
 221
 222   if (IS_DCE_STYLE(ctx)) {
 223     padlength = 0;
 224     datalen = input_message_buffer->length;
 225     len = 22 + 8;
 226     _gsskrb5_encap_length (len, &len, &total_len, GSS_KRB5_MECHANISM);
 227     total_len += datalen;
 228     datalen += 8;
 229   } else {
 230     padlength = 8 - (input_message_buffer->length % 8);
 231     datalen = input_message_buffer->length + padlength + 8;
 232     len = datalen + 22;
 233     _gsskrb5_encap_length (len, &len, &total_len, GSS_KRB5_MECHANISM);
 234   }
 235
 236   output_message_buffer->length = total_len;
 237   output_message_buffer->value  = malloc (total_len);
 238   if (output_message_buffer->value == NULL) {
 239     output_message_buffer->length = 0;
 240     *minor_status = ENOMEM;
 241     return GSS_S_FAILURE;
 242   }
 243
 244   p = _gsskrb5_make_header(output_message_buffer->value,
 245                               len,
 246                               "\x02\x01", /* TOK_ID */
 247                               GSS_KRB5_MECHANISM);
 248
 249   /* SGN_ALG */
 250   memcpy (p, "\x00\x00", 2);
 251   p += 2;
 252   /* SEAL_ALG */
 253   if(conf_req_flag)
 254       memcpy (p, "\x00\x00", 2);
 255   else
 256       memcpy (p, "\xff\xff", 2);
 257   p += 2;
 258   /* Filler */
 259   memcpy (p, "\xff\xff", 2);
 260   p += 2;
 261
 262   /* fill in later */
 263   memset (p, 0, 16);
 264   p += 16;
 265
 266   /* confounder + data + pad */
 267   krb5_generate_random_block(p, 8);
 268   memcpy (p + 8, input_message_buffer->value,
 269           input_message_buffer->length);
 270   memset (p + 8 + input_message_buffer->length, padlength, padlength);
 271
 272   /* checksum */
 273   md5 = EVP_MD_CTX_create();
 274   EVP_DigestInit_ex(md5, EVP_md5(), NULL);
 275   EVP_DigestUpdate(md5, p - 24, 8);
 276   EVP_DigestUpdate(md5, p, datalen);
 277   EVP_DigestFinal_ex(md5, hash, NULL);
 278   EVP_MD_CTX_destroy(md5);
 279
 280   memset (&zero, 0, sizeof(zero));
 281   memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
 282   DES_set_key_unchecked (&deskey, &schedule);
 283   DES_cbc_cksum ((void *)hash, (void *)hash, sizeof(hash),
 284                  &schedule, &zero);
 285   memcpy (p - 8, hash, 8);
 286
 287   /* sequence number */
 288   HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
 289   krb5_auth_con_getlocalseqnumber (context,
 290                                    ctx->auth_context,
 291                                    &seq_number);
 292
 293   p -= 16;
 294   p[0] = (seq_number >> 0)  & 0xFF;
 295   p[1] = (seq_number >> 8)  & 0xFF;
 296   p[2] = (seq_number >> 16) & 0xFF;
 297   p[3] = (seq_number >> 24) & 0xFF;
 298   memset (p + 4,
 299           (ctx->more_flags & LOCAL) ? 0 : 0xFF,
 300           4);
 301
 302   EVP_CIPHER_CTX_init(&des_ctx);
 303   EVP_CipherInit_ex(&des_ctx, EVP_des_cbc(), NULL, key->keyvalue.data, p + 8, 1);
 304   EVP_Cipher(&des_ctx, p, p, 8);
 305   EVP_CIPHER_CTX_cleanup(&des_ctx);
 306
 307   krb5_auth_con_setlocalseqnumber (context,
 308                                ctx->auth_context,
 309                                ++seq_number);
 310   HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 311
 312   /* encrypt the data */
 313   p += 16;
 314
 315   if(conf_req_flag) {
 316       memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
 317
 318       for (i = 0; i < sizeof(deskey); ++i)
 319           deskey[i] ^= 0xf0;
 320
 321       EVP_CIPHER_CTX_init(&des_ctx);
 322       EVP_CipherInit_ex(&des_ctx, EVP_des_cbc(), NULL, deskey, zero, 1);
 323       EVP_Cipher(&des_ctx, p, p, datalen);
 324       EVP_CIPHER_CTX_cleanup(&des_ctx);
 325   }
 326   memset (deskey, 0, sizeof(deskey));
 327   memset (&schedule, 0, sizeof(schedule));
 328
 329   if(conf_state != NULL)
 330       *conf_state = conf_req_flag;
 331   *minor_status = 0;
 332   return GSS_S_COMPLETE;
 333 }
 334
 335 #endif
 336
 337 static OM_uint32
 338 wrap_des3
 339            (OM_uint32 * minor_status,
 340             const gsskrb5_ctx ctx,
 341             krb5_context context,
 342             int conf_req_flag,
 343             gss_qop_t qop_req,
 344             const gss_buffer_t input_message_buffer,
 345             int * conf_state,
 346             gss_buffer_t output_message_buffer,
 347             krb5_keyblock *key
 348            )
 349 {
 350   u_char *p;
 351   u_char seq[8];
 352   int32_t seq_number;
 353   size_t len, total_len, padlength, datalen;
 354   uint32_t ret;
 355   krb5_crypto crypto;
 356   Checksum cksum;
 357   krb5_data encdata;
 358
 359   if (IS_DCE_STYLE(ctx)) {
 360     padlength = 0;
 361     datalen = input_message_buffer->length;
 362     len = 34 + 8;
 363     _gsskrb5_encap_length (len, &len, &total_len, GSS_KRB5_MECHANISM);
 364     total_len += datalen;
 365     datalen += 8;
 366   } else {
 367     padlength = 8 - (input_message_buffer->length % 8);
 368     datalen = input_message_buffer->length + padlength + 8;
 369     len = datalen + 34;
 370     _gsskrb5_encap_length (len, &len, &total_len, GSS_KRB5_MECHANISM);
 371   }
 372
 373   output_message_buffer->length = total_len;
 374   output_message_buffer->value  = malloc (total_len);
 375   if (output_message_buffer->value == NULL) {
 376     output_message_buffer->length = 0;
 377     *minor_status = ENOMEM;
 378     return GSS_S_FAILURE;
 379   }
 380
 381   p = _gsskrb5_make_header(output_message_buffer->value,
 382                               len,
 383                               "\x02\x01", /* TOK_ID */
 384                               GSS_KRB5_MECHANISM);
 385
 386   /* SGN_ALG */
 387   memcpy (p, "\x04\x00", 2);    /* HMAC SHA1 DES3-KD */
 388   p += 2;
 389   /* SEAL_ALG */
 390   if(conf_req_flag)
 391       memcpy (p, "\x02\x00", 2); /* DES3-KD */
 392   else
 393       memcpy (p, "\xff\xff", 2);
 394   p += 2;
 395   /* Filler */
 396   memcpy (p, "\xff\xff", 2);
 397   p += 2;
 398
 399   /* calculate checksum (the above + confounder + data + pad) */
 400
 401   memcpy (p + 20, p - 8, 8);
 402   krb5_generate_random_block(p + 28, 8);
 403   memcpy (p + 28 + 8, input_message_buffer->value,
 404           input_message_buffer->length);
 405   memset (p + 28 + 8 + input_message_buffer->length, padlength, padlength);
 406
 407   ret = krb5_crypto_init(context, key, 0, &crypto);
 408   if (ret) {
 409       free (output_message_buffer->value);
 410       output_message_buffer->length = 0;
 411       output_message_buffer->value = NULL;
 412       *minor_status = ret;
 413       return GSS_S_FAILURE;
 414   }
 415
 416   ret = krb5_create_checksum (context,
 417                               crypto,
 418                               KRB5_KU_USAGE_SIGN,
 419                               0,
 420                               p + 20,
 421                               datalen + 8,
 422                               &cksum);
 423   krb5_crypto_destroy (context, crypto);
 424   if (ret) {
 425       free (output_message_buffer->value);
 426       output_message_buffer->length = 0;
 427       output_message_buffer->value = NULL;
 428       *minor_status = ret;
 429       return GSS_S_FAILURE;
 430   }
 431
 432   /* zero out SND_SEQ + SGN_CKSUM in case */
 433   memset (p, 0, 28);
 434
 435   memcpy (p + 8, cksum.checksum.data, cksum.checksum.length);
 436   free_Checksum (&cksum);
 437
 438   HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
 439   /* sequence number */
 440   krb5_auth_con_getlocalseqnumber (context,
 441                                ctx->auth_context,
 442                                &seq_number);
 443
 444   seq[0] = (seq_number >> 0)  & 0xFF;
 445   seq[1] = (seq_number >> 8)  & 0xFF;
 446   seq[2] = (seq_number >> 16) & 0xFF;
 447   seq[3] = (seq_number >> 24) & 0xFF;
 448   memset (seq + 4,
 449           (ctx->more_flags & LOCAL) ? 0 : 0xFF,
 450           4);
 451
 452
 453   ret = krb5_crypto_init(context, key, ETYPE_DES3_CBC_NONE,
 454                          &crypto);
 455   if (ret) {
 456       free (output_message_buffer->value);
 457       output_message_buffer->length = 0;
 458       output_message_buffer->value = NULL;
 459       *minor_status = ret;
 460       return GSS_S_FAILURE;
 461   }
 462
 463   {
 464       DES_cblock ivec;
 465
 466       memcpy (&ivec, p + 8, 8);
 467       ret = krb5_encrypt_ivec (context,
 468                                crypto,
 469                                KRB5_KU_USAGE_SEQ,
 470                                seq, 8, &encdata,
 471                                &ivec);
 472   }
 473   krb5_crypto_destroy (context, crypto);
 474   if (ret) {
 475       free (output_message_buffer->value);
 476       output_message_buffer->length = 0;
 477       output_message_buffer->value = NULL;
 478       *minor_status = ret;
 479       return GSS_S_FAILURE;
 480   }
 481
 482   assert (encdata.length == 8);
 483
 484   memcpy (p, encdata.data, encdata.length);
 485   krb5_data_free (&encdata);
 486
 487   krb5_auth_con_setlocalseqnumber (context,
 488                                ctx->auth_context,
 489                                ++seq_number);
 490   HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 491
 492   /* encrypt the data */
 493   p += 28;
 494
 495   if(conf_req_flag) {
 496       krb5_data tmp;
 497
 498       ret = krb5_crypto_init(context, key,
 499                              ETYPE_DES3_CBC_NONE, &crypto);
 500       if (ret) {
 501           free (output_message_buffer->value);
 502           output_message_buffer->length = 0;
 503           output_message_buffer->value = NULL;
 504           *minor_status = ret;
 505           return GSS_S_FAILURE;
 506       }
 507       ret = krb5_encrypt(context, crypto, KRB5_KU_USAGE_SEAL,
 508                          p, datalen, &tmp);
 509       krb5_crypto_destroy(context, crypto);
 510       if (ret) {
 511           free (output_message_buffer->value);
 512           output_message_buffer->length = 0;
 513           output_message_buffer->value = NULL;
 514           *minor_status = ret;
 515           return GSS_S_FAILURE;
 516       }
 517       assert (tmp.length == datalen);
 518
 519       memcpy (p, tmp.data, datalen);
 520       krb5_data_free(&tmp);
 521   }
 522   if(conf_state != NULL)
 523       *conf_state = conf_req_flag;
 524   *minor_status = 0;
 525   return GSS_S_COMPLETE;
 526 }
 527
 528 OM_uint32 GSSAPI_CALLCONV
 529 _gsskrb5_wrap
 530            (OM_uint32 * minor_status,
 531             gss_const_ctx_id_t context_handle,
 532             int conf_req_flag,
 533             gss_qop_t qop_req,
 534             const gss_buffer_t input_message_buffer,
 535             int * conf_state,
 536             gss_buffer_t output_message_buffer
 537            )
 538 {
 539   krb5_context context;
 540   krb5_keyblock *key;
 541   OM_uint32 ret;
 542   const gsskrb5_ctx ctx = (const gsskrb5_ctx) context_handle;
 543
 544   output_message_buffer->value = NULL;
 545   output_message_buffer->length = 0;
 546
 547   GSSAPI_KRB5_INIT (&context);
 548
 549   if (ctx->more_flags & IS_CFX)
 550       return _gssapi_wrap_cfx (minor_status, ctx, context, conf_req_flag,
 551                                input_message_buffer, conf_state,
 552                                output_message_buffer);
 553
 554   HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
 555   ret = _gsskrb5i_get_token_key(ctx, context, &key);
 556   HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 557   if (ret) {
 558       *minor_status = ret;
 559       return GSS_S_FAILURE;
 560   }
 561
 562   switch (key->keytype) {
 563   case KRB5_ENCTYPE_DES_CBC_CRC :
 564   case KRB5_ENCTYPE_DES_CBC_MD4 :
 565   case KRB5_ENCTYPE_DES_CBC_MD5 :
 566 #ifdef HEIM_WEAK_CRYPTO
 567       ret = wrap_des (minor_status, ctx, context, conf_req_flag,
 568                       qop_req, input_message_buffer, conf_state,
 569                       output_message_buffer, key);
 570 #else
 571       ret = GSS_S_FAILURE;
 572 #endif
 573       break;
 574   case KRB5_ENCTYPE_DES3_CBC_MD5 :
 575   case KRB5_ENCTYPE_DES3_CBC_SHA1 :
 576       ret = wrap_des3 (minor_status, ctx, context, conf_req_flag,
 577                        qop_req, input_message_buffer, conf_state,
 578                        output_message_buffer, key);
 579       break;
 580   case KRB5_ENCTYPE_ARCFOUR_HMAC_MD5:
 581   case KRB5_ENCTYPE_ARCFOUR_HMAC_MD5_56:
 582       ret = _gssapi_wrap_arcfour (minor_status, ctx, context, conf_req_flag,
 583                                   qop_req, input_message_buffer, conf_state,
 584                                   output_message_buffer, key);
 585       break;
 586   default :
 587       abort();
 588       break;
 589   }
 590   krb5_free_keyblock (context, key);
 591   return ret;
 592 }