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   size_t 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       memset (&zero, 0, sizeof(zero));
 102
 103       for (i = 0; i < sizeof(deskey); ++i)
 104           deskey[i] ^= 0xf0;
 105
 106
 107       EVP_CIPHER_CTX_init(&des_ctx);
 108       EVP_CipherInit_ex(&des_ctx, EVP_des_cbc(), NULL, deskey, zero, 0);
 109       EVP_Cipher(&des_ctx, p, p, input_message_buffer->length - len);
 110       EVP_CIPHER_CTX_cleanup(&des_ctx);
 111
 112       memset (&schedule, 0, sizeof(schedule));
 113   }
 114
 115   if (IS_DCE_STYLE(context_handle)) {
 116     padlength = 0;
 117   } else {
 118     /* check pad */
 119     ret = _gssapi_verify_pad(input_message_buffer,
 120                              input_message_buffer->length - len,
 121                              &padlength);
 122     if (ret)
 123         return ret;
 124   }
 125
 126   md5 = EVP_MD_CTX_create();
 127   EVP_DigestInit_ex(md5, EVP_md5(), NULL);
 128   EVP_DigestUpdate(md5, p - 24, 8);
 129   EVP_DigestUpdate(md5, p, input_message_buffer->length - len);
 130   EVP_DigestFinal_ex(md5, hash, NULL);
 131   EVP_MD_CTX_destroy(md5);
 132
 133   memset (&zero, 0, sizeof(zero));
 134   memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
 135   DES_set_key_unchecked (&deskey, &schedule);
 136   DES_cbc_cksum ((void *)hash, (void *)hash, sizeof(hash),
 137                  &schedule, &zero);
 138   if (ct_memcmp (p - 8, hash, 8) != 0)
 139     return GSS_S_BAD_MIC;
 140
 141   /* verify sequence number */
 142
 143   HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
 144
 145   p -= 16;
 146
 147   EVP_CIPHER_CTX_init(&des_ctx);
 148   EVP_CipherInit_ex(&des_ctx, EVP_des_cbc(), NULL, key->keyvalue.data, hash, 0);
 149   EVP_Cipher(&des_ctx, p, p, 8);
 150   EVP_CIPHER_CTX_cleanup(&des_ctx);
 151
 152   memset (deskey, 0, sizeof(deskey));
 153   memset (&schedule, 0, sizeof(schedule));
 154
 155   seq = p;
 156   _gsskrb5_decode_om_uint32(seq, &seq_number);
 157
 158   if (context_handle->more_flags & LOCAL)
 159       cmp = ct_memcmp(&seq[4], "\xff\xff\xff\xff", 4);
 160   else
 161       cmp = ct_memcmp(&seq[4], "\x00\x00\x00\x00", 4);
 162
 163   if (cmp != 0) {
 164     HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 165     return GSS_S_BAD_MIC;
 166   }
 167
 168   ret = _gssapi_msg_order_check(context_handle->order, seq_number);
 169   if (ret) {
 170     HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 171     return ret;
 172   }
 173
 174   HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 175
 176   /* copy out data */
 177
 178   output_message_buffer->length = input_message_buffer->length
 179     - len - padlength - 8;
 180   output_message_buffer->value  = malloc(output_message_buffer->length);
 181   if(output_message_buffer->length != 0 && output_message_buffer->value == NULL)
 182       return GSS_S_FAILURE;
 183   memcpy (output_message_buffer->value,
 184           p + 24,
 185           output_message_buffer->length);
 186   return GSS_S_COMPLETE;
 187 }
 188 #endif
 189
 190 static OM_uint32
 191 unwrap_des3
 192            (OM_uint32 * minor_status,
 193             const gsskrb5_ctx context_handle,
 194             krb5_context context,
 195             const gss_buffer_t input_message_buffer,
 196             gss_buffer_t output_message_buffer,
 197             int * conf_state,
 198             gss_qop_t * qop_state,
 199             krb5_keyblock *key
 200            )
 201 {
 202   u_char *p;
 203   size_t len;
 204   u_char *seq;
 205   krb5_data seq_data;
 206   u_char cksum[20];
 207   uint32_t seq_number;
 208   size_t padlength;
 209   OM_uint32 ret;
 210   int cstate;
 211   krb5_crypto crypto;
 212   Checksum csum;
 213   int cmp;
 214   int token_len;
 215
 216   if (IS_DCE_STYLE(context_handle)) {
 217      token_len = 34 + 8 + 15; /* 57 */
 218   } else {
 219      token_len = input_message_buffer->length;
 220   }
 221
 222   p = input_message_buffer->value;
 223   ret = _gsskrb5_verify_header (&p,
 224                                    token_len,
 225                                    "\x02\x01",
 226                                    GSS_KRB5_MECHANISM);
 227   if (ret)
 228       return ret;
 229
 230   if (memcmp (p, "\x04\x00", 2) != 0) /* HMAC SHA1 DES3_KD */
 231     return GSS_S_BAD_SIG;
 232   p += 2;
 233   if (ct_memcmp (p, "\x02\x00", 2) == 0) {
 234     cstate = 1;
 235   } else if (ct_memcmp (p, "\xff\xff", 2) == 0) {
 236     cstate = 0;
 237   } else
 238     return GSS_S_BAD_MIC;
 239   p += 2;
 240   if(conf_state != NULL)
 241     *conf_state = cstate;
 242   if (ct_memcmp (p, "\xff\xff", 2) != 0)
 243     return GSS_S_DEFECTIVE_TOKEN;
 244   p += 2;
 245   p += 28;
 246
 247   len = p - (u_char *)input_message_buffer->value;
 248
 249   if(cstate) {
 250       /* decrypt data */
 251       krb5_data tmp;
 252
 253       ret = krb5_crypto_init(context, key,
 254                              ETYPE_DES3_CBC_NONE, &crypto);
 255       if (ret) {
 256           *minor_status = ret;
 257           return GSS_S_FAILURE;
 258       }
 259       ret = krb5_decrypt(context, crypto, KRB5_KU_USAGE_SEAL,
 260                          p, input_message_buffer->length - len, &tmp);
 261       krb5_crypto_destroy(context, crypto);
 262       if (ret) {
 263           *minor_status = ret;
 264           return GSS_S_FAILURE;
 265       }
 266       assert (tmp.length == input_message_buffer->length - len);
 267
 268       memcpy (p, tmp.data, tmp.length);
 269       krb5_data_free(&tmp);
 270   }
 271
 272   if (IS_DCE_STYLE(context_handle)) {
 273     padlength = 0;
 274   } else {
 275     /* check pad */
 276     ret = _gssapi_verify_pad(input_message_buffer,
 277                              input_message_buffer->length - len,
 278                              &padlength);
 279     if (ret)
 280         return ret;
 281   }
 282
 283   /* verify sequence number */
 284
 285   HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
 286
 287   p -= 28;
 288
 289   ret = krb5_crypto_init(context, key,
 290                          ETYPE_DES3_CBC_NONE, &crypto);
 291   if (ret) {
 292       *minor_status = ret;
 293       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 294       return GSS_S_FAILURE;
 295   }
 296   {
 297       DES_cblock ivec;
 298
 299       memcpy(&ivec, p + 8, 8);
 300       ret = krb5_decrypt_ivec (context,
 301                                crypto,
 302                                KRB5_KU_USAGE_SEQ,
 303                                p, 8, &seq_data,
 304                                &ivec);
 305   }
 306   krb5_crypto_destroy (context, crypto);
 307   if (ret) {
 308       *minor_status = ret;
 309       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 310       return GSS_S_FAILURE;
 311   }
 312   if (seq_data.length != 8) {
 313       krb5_data_free (&seq_data);
 314       *minor_status = 0;
 315       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 316       return GSS_S_BAD_MIC;
 317   }
 318
 319   seq = seq_data.data;
 320   _gsskrb5_decode_om_uint32(seq, &seq_number);
 321
 322   if (context_handle->more_flags & LOCAL)
 323       cmp = ct_memcmp(&seq[4], "\xff\xff\xff\xff", 4);
 324   else
 325       cmp = ct_memcmp(&seq[4], "\x00\x00\x00\x00", 4);
 326
 327   krb5_data_free (&seq_data);
 328   if (cmp != 0) {
 329       *minor_status = 0;
 330       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 331       return GSS_S_BAD_MIC;
 332   }
 333
 334   ret = _gssapi_msg_order_check(context_handle->order, seq_number);
 335   if (ret) {
 336       *minor_status = 0;
 337       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 338       return ret;
 339   }
 340
 341   HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 342
 343   /* verify checksum */
 344
 345   memcpy (cksum, p + 8, 20);
 346
 347   memcpy (p + 20, p - 8, 8);
 348
 349   csum.cksumtype = CKSUMTYPE_HMAC_SHA1_DES3;
 350   csum.checksum.length = 20;
 351   csum.checksum.data   = cksum;
 352
 353   ret = krb5_crypto_init(context, key, 0, &crypto);
 354   if (ret) {
 355       *minor_status = ret;
 356       return GSS_S_FAILURE;
 357   }
 358
 359   ret = krb5_verify_checksum (context, crypto,
 360                               KRB5_KU_USAGE_SIGN,
 361                               p + 20,
 362                               input_message_buffer->length - len + 8,
 363                               &csum);
 364   krb5_crypto_destroy (context, crypto);
 365   if (ret) {
 366       *minor_status = ret;
 367       return GSS_S_FAILURE;
 368   }
 369
 370   /* copy out data */
 371
 372   output_message_buffer->length = input_message_buffer->length
 373     - len - padlength - 8;
 374   output_message_buffer->value  = malloc(output_message_buffer->length);
 375   if(output_message_buffer->length != 0 && output_message_buffer->value == NULL)
 376       return GSS_S_FAILURE;
 377   memcpy (output_message_buffer->value,
 378           p + 36,
 379           output_message_buffer->length);
 380   return GSS_S_COMPLETE;
 381 }
 382
 383 OM_uint32 GSSAPI_CALLCONV _gsskrb5_unwrap
 384            (OM_uint32 * minor_status,
 385             gss_const_ctx_id_t context_handle,
 386             const gss_buffer_t input_message_buffer,
 387             gss_buffer_t output_message_buffer,
 388             int * conf_state,
 389             gss_qop_t * qop_state
 390            )
 391 {
 392   krb5_keyblock *key;
 393   krb5_context context;
 394   OM_uint32 ret;
 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
 417   *minor_status = 0;
 418
 419   switch (key->keytype) {
 420   case KRB5_ENCTYPE_DES_CBC_CRC :
 421   case KRB5_ENCTYPE_DES_CBC_MD4 :
 422   case KRB5_ENCTYPE_DES_CBC_MD5 :
 423 #ifdef HEIM_WEAK_CRYPTO
 424       ret = unwrap_des (minor_status, ctx,
 425                         input_message_buffer, output_message_buffer,
 426                         conf_state, qop_state, key);
 427 #else
 428       ret = GSS_S_FAILURE;
 429 #endif
 430       break;
 431   case KRB5_ENCTYPE_DES3_CBC_MD5 :
 432   case KRB5_ENCTYPE_DES3_CBC_SHA1 :
 433       ret = unwrap_des3 (minor_status, ctx, context,
 434                          input_message_buffer, output_message_buffer,
 435                          conf_state, qop_state, key);
 436       break;
 437   case KRB5_ENCTYPE_ARCFOUR_HMAC_MD5:
 438   case KRB5_ENCTYPE_ARCFOUR_HMAC_MD5_56:
 439       ret = _gssapi_unwrap_arcfour (minor_status, ctx, context,
 440                                     input_message_buffer, output_message_buffer,
 441                                     conf_state, qop_state, key);
 442       break;
 443   default :
 444       abort();
 445       break;
 446   }
 447   krb5_free_keyblock (context, key);
 448   return ret;
 449 }