lib/gssapi/krb5/unwrap.c

   1 /*
   2  * Copyright (c) 1997 - 2004 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 #ifdef HEIM_WEAK_CRYPTO
  37
  38 static OM_uint32
  39 unwrap_des
  40            (OM_uint32 * minor_status,
  41             const gsskrb5_ctx context_handle,
  42             const gss_buffer_t input_message_buffer,
  43             gss_buffer_t output_message_buffer,
  44             int * conf_state,
  45             gss_qop_t * qop_state,
  46             krb5_keyblock *key
  47            )
  48 {
  49   u_char *p, *seq;
  50   size_t len;
  51   EVP_MD_CTX md5;
  52   u_char hash[16];
  53   EVP_CIPHER_CTX des_ctx;
  54   DES_key_schedule schedule;
  55   DES_cblock deskey;
  56   DES_cblock zero;
  57   int i;
  58   uint32_t seq_number;
  59   size_t padlength;
  60   OM_uint32 ret;
  61   int cstate;
  62   int cmp;
  63   int token_len;
  64
  65   if (IS_DCE_STYLE(context_handle)) {
  66      token_len = 22 + 8 + 15; /* 45 */
  67   } else {
  68      token_len = input_message_buffer->length;
  69   }
  70
  71   p = input_message_buffer->value;
  72   ret = _gsskrb5_verify_header (&p,
  73                                    token_len,
  74                                    "\x02\x01",
  75                                    GSS_KRB5_MECHANISM);
  76   if (ret)
  77       return ret;
  78
  79   if (memcmp (p, "\x00\x00", 2) != 0)
  80     return GSS_S_BAD_SIG;
  81   p += 2;
  82   if (memcmp (p, "\x00\x00", 2) == 0) {
  83       cstate = 1;
  84   } else if (memcmp (p, "\xFF\xFF", 2) == 0) {
  85       cstate = 0;
  86   } else
  87       return GSS_S_BAD_MIC;
  88   p += 2;
  89   if(conf_state != NULL)
  90       *conf_state = cstate;
  91   if (memcmp (p, "\xff\xff", 2) != 0)
  92     return GSS_S_DEFECTIVE_TOKEN;
  93   p += 2;
  94   p += 16;
  95
  96   len = p - (u_char *)input_message_buffer->value;
  97
  98   if(cstate) {
  99       /* decrypt data */
 100       memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
 101
 102       for (i = 0; i < sizeof(deskey); ++i)
 103           deskey[i] ^= 0xf0;
 104
 105
 106       EVP_CIPHER_CTX_init(&des_ctx);
 107       EVP_CipherInit_ex(&des_ctx, EVP_des_cbc(), NULL, deskey, zero, 0);
 108       EVP_Cipher(&des_ctx, p, p, input_message_buffer->length - len);
 109       EVP_CIPHER_CTX_cleanup(&des_ctx);
 110
 111       memset (&schedule, 0, sizeof(schedule));
 112   }
 113
 114   if (IS_DCE_STYLE(context_handle)) {
 115     padlength = 0;
 116   } else {
 117     /* check pad */
 118     ret = _gssapi_verify_pad(input_message_buffer,
 119                              input_message_buffer->length - len,
 120                              &padlength);
 121     if (ret)
 122         return ret;
 123   }
 124
 125   EVP_MD_CTX_init(&md5);
 126   EVP_DigestInit_ex(&md5, EVP_md5(), NULL);
 127   EVP_DigestUpdate(&md5, p - 24, 8);
 128   EVP_DigestUpdate(&md5, p, input_message_buffer->length - len);
 129   EVP_DigestFinal_ex(&md5, hash, NULL);
 130   EVP_MD_CTX_cleanup(&md5);
 131
 132   memset (&zero, 0, sizeof(zero));
 133   memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
 134   DES_set_key_unchecked (&deskey, &schedule);
 135   DES_cbc_cksum ((void *)hash, (void *)hash, sizeof(hash),
 136                  &schedule, &zero);
 137   if (ct_memcmp (p - 8, hash, 8) != 0)
 138     return GSS_S_BAD_MIC;
 139
 140   /* verify sequence number */
 141
 142   HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
 143
 144   p -= 16;
 145
 146   EVP_CIPHER_CTX_init(&des_ctx);
 147   EVP_CipherInit_ex(&des_ctx, EVP_des_cbc(), NULL, key->keyvalue.data, hash, 0);
 148   EVP_Cipher(&des_ctx, p, p, 8);
 149   EVP_CIPHER_CTX_cleanup(&des_ctx);
 150
 151   memset (deskey, 0, sizeof(deskey));
 152   memset (&schedule, 0, sizeof(schedule));
 153
 154   seq = p;
 155   _gsskrb5_decode_om_uint32(seq, &seq_number);
 156
 157   if (context_handle->more_flags & LOCAL)
 158       cmp = ct_memcmp(&seq[4], "\xff\xff\xff\xff", 4);
 159   else
 160       cmp = ct_memcmp(&seq[4], "\x00\x00\x00\x00", 4);
 161
 162   if (cmp != 0) {
 163     HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 164     return GSS_S_BAD_MIC;
 165   }
 166
 167   ret = _gssapi_msg_order_check(context_handle->order, seq_number);
 168   if (ret) {
 169     HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 170     return ret;
 171   }
 172
 173   HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 174
 175   /* copy out data */
 176
 177   output_message_buffer->length = input_message_buffer->length
 178     - len - padlength - 8;
 179   output_message_buffer->value  = malloc(output_message_buffer->length);
 180   if(output_message_buffer->length != 0 && output_message_buffer->value == NULL)
 181       return GSS_S_FAILURE;
 182   memcpy (output_message_buffer->value,
 183           p + 24,
 184           output_message_buffer->length);
 185   return GSS_S_COMPLETE;
 186 }
 187 #endif
 188
 189 static OM_uint32
 190 unwrap_des3
 191            (OM_uint32 * minor_status,
 192             const gsskrb5_ctx context_handle,
 193             krb5_context context,
 194             const gss_buffer_t input_message_buffer,
 195             gss_buffer_t output_message_buffer,
 196             int * conf_state,
 197             gss_qop_t * qop_state,
 198             krb5_keyblock *key
 199            )
 200 {
 201   u_char *p;
 202   size_t len;
 203   u_char *seq;
 204   krb5_data seq_data;
 205   u_char cksum[20];
 206   uint32_t seq_number;
 207   size_t padlength;
 208   OM_uint32 ret;
 209   int cstate;
 210   krb5_crypto crypto;
 211   Checksum csum;
 212   int cmp;
 213   int token_len;
 214
 215   if (IS_DCE_STYLE(context_handle)) {
 216      token_len = 34 + 8 + 15; /* 57 */
 217   } else {
 218      token_len = input_message_buffer->length;
 219   }
 220
 221   p = input_message_buffer->value;
 222   ret = _gsskrb5_verify_header (&p,
 223                                    token_len,
 224                                    "\x02\x01",
 225                                    GSS_KRB5_MECHANISM);
 226   if (ret)
 227       return ret;
 228
 229   if (memcmp (p, "\x04\x00", 2) != 0) /* HMAC SHA1 DES3_KD */
 230     return GSS_S_BAD_SIG;
 231   p += 2;
 232   if (ct_memcmp (p, "\x02\x00", 2) == 0) {
 233     cstate = 1;
 234   } else if (ct_memcmp (p, "\xff\xff", 2) == 0) {
 235     cstate = 0;
 236   } else
 237     return GSS_S_BAD_MIC;
 238   p += 2;
 239   if(conf_state != NULL)
 240     *conf_state = cstate;
 241   if (ct_memcmp (p, "\xff\xff", 2) != 0)
 242     return GSS_S_DEFECTIVE_TOKEN;
 243   p += 2;
 244   p += 28;
 245
 246   len = p - (u_char *)input_message_buffer->value;
 247
 248   if(cstate) {
 249       /* decrypt data */
 250       krb5_data tmp;
 251
 252       ret = krb5_crypto_init(context, key,
 253                              ETYPE_DES3_CBC_NONE, &crypto);
 254       if (ret) {
 255           *minor_status = ret;
 256           return GSS_S_FAILURE;
 257       }
 258       ret = krb5_decrypt(context, crypto, KRB5_KU_USAGE_SEAL,
 259                          p, input_message_buffer->length - len, &tmp);
 260       krb5_crypto_destroy(context, crypto);
 261       if (ret) {
 262           *minor_status = ret;
 263           return GSS_S_FAILURE;
 264       }
 265       assert (tmp.length == input_message_buffer->length - len);
 266
 267       memcpy (p, tmp.data, tmp.length);
 268       krb5_data_free(&tmp);
 269   }
 270
 271   if (IS_DCE_STYLE(context_handle)) {
 272     padlength = 0;
 273   } else {
 274     /* check pad */
 275     ret = _gssapi_verify_pad(input_message_buffer,
 276                              input_message_buffer->length - len,
 277                              &padlength);
 278     if (ret)
 279         return ret;
 280   }
 281
 282   /* verify sequence number */
 283
 284   HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
 285
 286   p -= 28;
 287
 288   ret = krb5_crypto_init(context, key,
 289                          ETYPE_DES3_CBC_NONE, &crypto);
 290   if (ret) {
 291       *minor_status = ret;
 292       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 293       return GSS_S_FAILURE;
 294   }
 295   {
 296       DES_cblock ivec;
 297
 298       memcpy(&ivec, p + 8, 8);
 299       ret = krb5_decrypt_ivec (context,
 300                                crypto,
 301                                KRB5_KU_USAGE_SEQ,
 302                                p, 8, &seq_data,
 303                                &ivec);
 304   }
 305   krb5_crypto_destroy (context, crypto);
 306   if (ret) {
 307       *minor_status = ret;
 308       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 309       return GSS_S_FAILURE;
 310   }
 311   if (seq_data.length != 8) {
 312       krb5_data_free (&seq_data);
 313       *minor_status = 0;
 314       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 315       return GSS_S_BAD_MIC;
 316   }
 317
 318   seq = seq_data.data;
 319   _gsskrb5_decode_om_uint32(seq, &seq_number);
 320
 321   if (context_handle->more_flags & LOCAL)
 322       cmp = ct_memcmp(&seq[4], "\xff\xff\xff\xff", 4);
 323   else
 324       cmp = ct_memcmp(&seq[4], "\x00\x00\x00\x00", 4);
 325
 326   krb5_data_free (&seq_data);
 327   if (cmp != 0) {
 328       *minor_status = 0;
 329       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 330       return GSS_S_BAD_MIC;
 331   }
 332
 333   ret = _gssapi_msg_order_check(context_handle->order, seq_number);
 334   if (ret) {
 335       *minor_status = 0;
 336       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 337       return ret;
 338   }
 339
 340   HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 341
 342   /* verify checksum */
 343
 344   memcpy (cksum, p + 8, 20);
 345
 346   memcpy (p + 20, p - 8, 8);
 347
 348   csum.cksumtype = CKSUMTYPE_HMAC_SHA1_DES3;
 349   csum.checksum.length = 20;
 350   csum.checksum.data   = cksum;
 351
 352   ret = krb5_crypto_init(context, key, 0, &crypto);
 353   if (ret) {
 354       *minor_status = ret;
 355       return GSS_S_FAILURE;
 356   }
 357
 358   ret = krb5_verify_checksum (context, crypto,
 359                               KRB5_KU_USAGE_SIGN,
 360                               p + 20,
 361                               input_message_buffer->length - len + 8,
 362                               &csum);
 363   krb5_crypto_destroy (context, crypto);
 364   if (ret) {
 365       *minor_status = ret;
 366       return GSS_S_FAILURE;
 367   }
 368
 369   /* copy out data */
 370
 371   output_message_buffer->length = input_message_buffer->length
 372     - len - padlength - 8;
 373   output_message_buffer->value  = malloc(output_message_buffer->length);
 374   if(output_message_buffer->length != 0 && output_message_buffer->value == NULL)
 375       return GSS_S_FAILURE;
 376   memcpy (output_message_buffer->value,
 377           p + 36,
 378           output_message_buffer->length);
 379   return GSS_S_COMPLETE;
 380 }
 381
 382 OM_uint32 _gsskrb5_unwrap
 383            (OM_uint32 * minor_status,
 384             const gss_ctx_id_t context_handle,
 385             const gss_buffer_t input_message_buffer,
 386             gss_buffer_t output_message_buffer,
 387             int * conf_state,
 388             gss_qop_t * qop_state
 389            )
 390 {
 391   krb5_keyblock *key;
 392   krb5_context context;
 393   OM_uint32 ret;
 394   krb5_keytype keytype;
 395   gsskrb5_ctx ctx = (gsskrb5_ctx) context_handle;
 396
 397   output_message_buffer->value = NULL;
 398   output_message_buffer->length = 0;
 399   if (qop_state != NULL)
 400       *qop_state = GSS_C_QOP_DEFAULT;
 401
 402   GSSAPI_KRB5_INIT (&context);
 403
 404   if (ctx->more_flags & IS_CFX)
 405       return _gssapi_unwrap_cfx (minor_status, ctx, context,
 406                                  input_message_buffer, output_message_buffer,
 407                                  conf_state, qop_state);
 408
 409   HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
 410   ret = _gsskrb5i_get_token_key(ctx, context, &key);
 411   HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 412   if (ret) {
 413       *minor_status = ret;
 414       return GSS_S_FAILURE;
 415   }
 416   krb5_enctype_to_keytype (context, key->keytype, &keytype);
 417
 418   *minor_status = 0;
 419
 420   switch (keytype) {
 421   case KEYTYPE_DES :
 422 #ifdef HEIM_WEAK_CRYPTO
 423       ret = unwrap_des (minor_status, ctx,
 424                         input_message_buffer, output_message_buffer,
 425                         conf_state, qop_state, key);
 426 #else
 427       ret = GSS_S_FAILURE;
 428 #endif
 429       break;
 430   case KEYTYPE_DES3 :
 431       ret = unwrap_des3 (minor_status, ctx, context,
 432                          input_message_buffer, output_message_buffer,
 433                          conf_state, qop_state, key);
 434       break;
 435   case KEYTYPE_ARCFOUR:
 436   case KEYTYPE_ARCFOUR_56:
 437       ret = _gssapi_unwrap_arcfour (minor_status, ctx, context,
 438                                     input_message_buffer, output_message_buffer,
 439                                     conf_state, qop_state, key);
 440       break;
 441   default :
 442       abort();
 443       break;
 444   }
 445   krb5_free_keyblock (context, key);
 446   return ret;
 447 }