lib/gssapi/krb5/verify_mic.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 #ifdef HEIM_WEAK_CRYPTO
  37
  38 static OM_uint32
  39 verify_mic_des
  40            (OM_uint32 * minor_status,
  41             const gsskrb5_ctx context_handle,
  42             krb5_context context,
  43             const gss_buffer_t message_buffer,
  44             const gss_buffer_t token_buffer,
  45             gss_qop_t * qop_state,
  46             krb5_keyblock *key,
  47             const char *type
  48             )
  49 {
  50   u_char *p;
  51   EVP_MD_CTX *md5;
  52   u_char hash[16], *seq;
  53   DES_key_schedule schedule;
  54   EVP_CIPHER_CTX des_ctx;
  55   DES_cblock zero;
  56   DES_cblock deskey;
  57   uint32_t seq_number;
  58   OM_uint32 ret;
  59   int cmp;
  60
  61   p = token_buffer->value;
  62   ret = _gsskrb5_verify_header (&p,
  63                                    token_buffer->length,
  64                                    type,
  65                                    GSS_KRB5_MECHANISM);
  66   if (ret)
  67       return ret;
  68
  69   if (memcmp(p, "\x00\x00", 2) != 0)
  70       return GSS_S_BAD_SIG;
  71   p += 2;
  72   if (memcmp (p, "\xff\xff\xff\xff", 4) != 0)
  73     return GSS_S_BAD_MIC;
  74   p += 4;
  75   p += 16;
  76
  77   /* verify checksum */
  78   md5 = EVP_MD_CTX_create();
  79   EVP_DigestInit_ex(md5, EVP_md5(), NULL);
  80   EVP_DigestUpdate(md5, p - 24, 8);
  81   EVP_DigestUpdate(md5, message_buffer->value, message_buffer->length);
  82   EVP_DigestFinal_ex(md5, hash, NULL);
  83   EVP_MD_CTX_destroy(md5);
  84
  85   memset (&zero, 0, sizeof(zero));
  86   memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
  87
  88   DES_set_key_unchecked (&deskey, &schedule);
  89   DES_cbc_cksum ((void *)hash, (void *)hash, sizeof(hash),
  90                  &schedule, &zero);
  91   if (ct_memcmp (p - 8, hash, 8) != 0) {
  92     memset (deskey, 0, sizeof(deskey));
  93     memset (&schedule, 0, sizeof(schedule));
  94     return GSS_S_BAD_MIC;
  95   }
  96
  97   /* verify sequence number */
  98
  99   HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
 100
 101   p -= 16;
 102
 103   EVP_CIPHER_CTX_init(&des_ctx);
 104   EVP_CipherInit_ex(&des_ctx, EVP_des_cbc(), NULL, key->keyvalue.data, hash, 0);
 105   EVP_Cipher(&des_ctx, p, p, 8);
 106   EVP_CIPHER_CTX_cleanup(&des_ctx);
 107
 108   memset (deskey, 0, sizeof(deskey));
 109   memset (&schedule, 0, sizeof(schedule));
 110
 111   seq = p;
 112   _gsskrb5_decode_om_uint32(seq, &seq_number);
 113
 114   if (context_handle->more_flags & LOCAL)
 115       cmp = ct_memcmp(&seq[4], "\xff\xff\xff\xff", 4);
 116   else
 117       cmp = ct_memcmp(&seq[4], "\x00\x00\x00\x00", 4);
 118
 119   if (cmp != 0) {
 120     HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 121     return GSS_S_BAD_MIC;
 122   }
 123
 124   ret = _gssapi_msg_order_check(context_handle->order, seq_number);
 125   if (ret) {
 126       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 127       return ret;
 128   }
 129
 130   HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 131
 132   return GSS_S_COMPLETE;
 133 }
 134 #endif
 135
 136 static OM_uint32
 137 verify_mic_des3
 138            (OM_uint32 * minor_status,
 139             const gsskrb5_ctx context_handle,
 140             krb5_context context,
 141             const gss_buffer_t message_buffer,
 142             const gss_buffer_t token_buffer,
 143             gss_qop_t * qop_state,
 144             krb5_keyblock *key,
 145             const char *type
 146             )
 147 {
 148   u_char *p;
 149   u_char *seq;
 150   uint32_t seq_number;
 151   OM_uint32 ret;
 152   krb5_crypto crypto;
 153   krb5_data seq_data;
 154   int cmp, docompat;
 155   Checksum csum;
 156   char *tmp;
 157   char ivec[8];
 158
 159   p = token_buffer->value;
 160   ret = _gsskrb5_verify_header (&p,
 161                                    token_buffer->length,
 162                                    type,
 163                                    GSS_KRB5_MECHANISM);
 164   if (ret)
 165       return ret;
 166
 167   if (memcmp(p, "\x04\x00", 2) != 0) /* SGN_ALG = HMAC SHA1 DES3-KD */
 168       return GSS_S_BAD_SIG;
 169   p += 2;
 170   if (memcmp (p, "\xff\xff\xff\xff", 4) != 0)
 171     return GSS_S_BAD_MIC;
 172   p += 4;
 173
 174   ret = krb5_crypto_init(context, key,
 175                          ETYPE_DES3_CBC_NONE, &crypto);
 176   if (ret){
 177       *minor_status = ret;
 178       return GSS_S_FAILURE;
 179   }
 180
 181   /* verify sequence number */
 182   docompat = 0;
 183 retry:
 184   if (docompat)
 185       memset(ivec, 0, 8);
 186   else
 187       memcpy(ivec, p + 8, 8);
 188
 189   ret = krb5_decrypt_ivec (context,
 190                            crypto,
 191                            KRB5_KU_USAGE_SEQ,
 192                            p, 8, &seq_data, ivec);
 193   if (ret) {
 194       if (docompat++) {
 195           krb5_crypto_destroy (context, crypto);
 196           *minor_status = ret;
 197           return GSS_S_FAILURE;
 198       } else
 199           goto retry;
 200   }
 201
 202   if (seq_data.length != 8) {
 203       krb5_data_free (&seq_data);
 204       if (docompat++) {
 205           krb5_crypto_destroy (context, crypto);
 206           return GSS_S_BAD_MIC;
 207       } else
 208           goto retry;
 209   }
 210
 211   HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
 212
 213   seq = seq_data.data;
 214   _gsskrb5_decode_om_uint32(seq, &seq_number);
 215
 216   if (context_handle->more_flags & LOCAL)
 217       cmp = ct_memcmp(&seq[4], "\xff\xff\xff\xff", 4);
 218   else
 219       cmp = ct_memcmp(&seq[4], "\x00\x00\x00\x00", 4);
 220
 221   krb5_data_free (&seq_data);
 222   if (cmp != 0) {
 223       krb5_crypto_destroy (context, crypto);
 224       *minor_status = 0;
 225       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 226       return GSS_S_BAD_MIC;
 227   }
 228
 229   ret = _gssapi_msg_order_check(context_handle->order, seq_number);
 230   if (ret) {
 231       krb5_crypto_destroy (context, crypto);
 232       *minor_status = 0;
 233       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 234       return ret;
 235   }
 236
 237   /* verify checksum */
 238
 239   tmp = malloc (message_buffer->length + 8);
 240   if (tmp == NULL) {
 241       krb5_crypto_destroy (context, crypto);
 242       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 243       *minor_status = ENOMEM;
 244       return GSS_S_FAILURE;
 245   }
 246
 247   memcpy (tmp, p - 8, 8);
 248   memcpy (tmp + 8, message_buffer->value, message_buffer->length);
 249
 250   csum.cksumtype = CKSUMTYPE_HMAC_SHA1_DES3;
 251   csum.checksum.length = 20;
 252   csum.checksum.data   = p + 8;
 253
 254   krb5_crypto_destroy (context, crypto);
 255   ret = krb5_crypto_init(context, key,
 256                          ETYPE_DES3_CBC_SHA1, &crypto);
 257   if (ret){
 258       *minor_status = ret;
 259       return GSS_S_FAILURE;
 260   }
 261
 262   ret = krb5_verify_checksum (context, crypto,
 263                               KRB5_KU_USAGE_SIGN,
 264                               tmp, message_buffer->length + 8,
 265                               &csum);
 266   free (tmp);
 267   if (ret) {
 268       krb5_crypto_destroy (context, crypto);
 269       *minor_status = ret;
 270       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 271       return GSS_S_BAD_MIC;
 272   }
 273   HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 274
 275   krb5_crypto_destroy (context, crypto);
 276   return GSS_S_COMPLETE;
 277 }
 278
 279 OM_uint32
 280 _gsskrb5_verify_mic_internal
 281            (OM_uint32 * minor_status,
 282             const gsskrb5_ctx ctx,
 283             krb5_context context,
 284             const gss_buffer_t message_buffer,
 285             const gss_buffer_t token_buffer,
 286             gss_qop_t * qop_state,
 287             const char * type
 288             )
 289 {
 290     krb5_keyblock *key;
 291     OM_uint32 ret;
 292
 293     if (ctx->more_flags & IS_CFX)
 294         return _gssapi_verify_mic_cfx (minor_status, ctx,
 295                                        context, message_buffer, token_buffer,
 296                                        qop_state);
 297
 298     HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
 299     ret = _gsskrb5i_get_token_key(ctx, context, &key);
 300     HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 301     if (ret) {
 302         *minor_status = ret;
 303         return GSS_S_FAILURE;
 304     }
 305     *minor_status = 0;
 306
 307     switch (key->keytype) {
 308     case KRB5_ENCTYPE_DES_CBC_CRC :
 309     case KRB5_ENCTYPE_DES_CBC_MD4 :
 310     case KRB5_ENCTYPE_DES_CBC_MD5 :
 311 #ifdef HEIM_WEAK_CRYPTO
 312         ret = verify_mic_des (minor_status, ctx, context,
 313                               message_buffer, token_buffer, qop_state, key,
 314                               type);
 315 #else
 316       ret = GSS_S_FAILURE;
 317 #endif
 318         break;
 319     case KRB5_ENCTYPE_DES3_CBC_MD5 :
 320     case KRB5_ENCTYPE_DES3_CBC_SHA1 :
 321         ret = verify_mic_des3 (minor_status, ctx, context,
 322                                message_buffer, token_buffer, qop_state, key,
 323                                type);
 324         break;
 325     case KRB5_ENCTYPE_ARCFOUR_HMAC_MD5:
 326     case KRB5_ENCTYPE_ARCFOUR_HMAC_MD5_56:
 327         ret = _gssapi_verify_mic_arcfour (minor_status, ctx,
 328                                           context,
 329                                           message_buffer, token_buffer,
 330                                           qop_state, key, type);
 331         break;
 332     default :
 333         abort();
 334     }
 335     krb5_free_keyblock (context, key);
 336
 337     return ret;
 338 }
 339
 340 OM_uint32 GSSAPI_CALLCONV
 341 _gsskrb5_verify_mic
 342            (OM_uint32 * minor_status,
 343             gss_const_ctx_id_t context_handle,
 344             const gss_buffer_t message_buffer,
 345             const gss_buffer_t token_buffer,
 346             gss_qop_t * qop_state
 347             )
 348 {
 349     krb5_context context;
 350     OM_uint32 ret;
 351
 352     GSSAPI_KRB5_INIT (&context);
 353
 354     if (qop_state != NULL)
 355         *qop_state = GSS_C_QOP_DEFAULT;
 356
 357     ret = _gsskrb5_verify_mic_internal(minor_status,
 358                                        (gsskrb5_ctx)context_handle,
 359                                        context,
 360                                        message_buffer, token_buffer,
 361                                        qop_state, (void *)(intptr_t)"\x01\x01");
 362
 363     return ret;
 364 }