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 static OM_uint32
  37 verify_mic_des
  38            (OM_uint32 * minor_status,
  39             const gsskrb5_ctx context_handle,
  40             krb5_context context,
  41             const gss_buffer_t message_buffer,
  42             const gss_buffer_t token_buffer,
  43             gss_qop_t * qop_state,
  44             krb5_keyblock *key,
  45             char *type
  46             )
  47 {
  48   u_char *p;
  49   EVP_MD_CTX md5;
  50   u_char hash[16], *seq;
  51   DES_key_schedule schedule;
  52   EVP_CIPHER_CTX des_ctx;
  53   DES_cblock zero;
  54   DES_cblock deskey;
  55   uint32_t seq_number;
  56   OM_uint32 ret;
  57   int cmp;
  58
  59   p = token_buffer->value;
  60   ret = _gsskrb5_verify_header (&p,
  61                                    token_buffer->length,
  62                                    type,
  63                                    GSS_KRB5_MECHANISM);
  64   if (ret)
  65       return ret;
  66
  67   if (memcmp(p, "\x00\x00", 2) != 0)
  68       return GSS_S_BAD_SIG;
  69   p += 2;
  70   if (memcmp (p, "\xff\xff\xff\xff", 4) != 0)
  71     return GSS_S_BAD_MIC;
  72   p += 4;
  73   p += 16;
  74
  75   /* verify checksum */
  76   EVP_MD_CTX_init(&md5);
  77   EVP_DigestInit_ex(&md5, EVP_md5(), NULL);
  78   EVP_DigestUpdate(&md5, p - 24, 8);
  79   EVP_DigestUpdate(&md5, message_buffer->value, message_buffer->length);
  80   EVP_DigestFinal_ex(&md5, hash, NULL);
  81   EVP_MD_CTX_cleanup(&md5);
  82
  83   memset (&zero, 0, sizeof(zero));
  84   memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
  85
  86   DES_set_key_unchecked (&deskey, &schedule);
  87   DES_cbc_cksum ((void *)hash, (void *)hash, sizeof(hash),
  88                  &schedule, &zero);
  89   if (ct_memcmp (p - 8, hash, 8) != 0) {
  90     memset (deskey, 0, sizeof(deskey));
  91     memset (&schedule, 0, sizeof(schedule));
  92     return GSS_S_BAD_MIC;
  93   }
  94
  95   /* verify sequence number */
  96
  97   HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
  98
  99   p -= 16;
 100
 101   EVP_CIPHER_CTX_init(&des_ctx);
 102   EVP_CipherInit_ex(&des_ctx, EVP_des_cbc(), NULL, key->keyvalue.data, hash, 0);
 103   EVP_Cipher(&des_ctx, p, p, 8);
 104   EVP_CIPHER_CTX_cleanup(&des_ctx);
 105
 106   memset (deskey, 0, sizeof(deskey));
 107   memset (&schedule, 0, sizeof(schedule));
 108
 109   seq = p;
 110   _gsskrb5_decode_om_uint32(seq, &seq_number);
 111
 112   if (context_handle->more_flags & LOCAL)
 113       cmp = ct_memcmp(&seq[4], "\xff\xff\xff\xff", 4);
 114   else
 115       cmp = ct_memcmp(&seq[4], "\x00\x00\x00\x00", 4);
 116
 117   if (cmp != 0) {
 118     HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 119     return GSS_S_BAD_MIC;
 120   }
 121
 122   ret = _gssapi_msg_order_check(context_handle->order, seq_number);
 123   if (ret) {
 124       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 125       return ret;
 126   }
 127
 128   HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 129
 130   return GSS_S_COMPLETE;
 131 }
 132
 133 static OM_uint32
 134 verify_mic_des3
 135            (OM_uint32 * minor_status,
 136             const gsskrb5_ctx context_handle,
 137             krb5_context context,
 138             const gss_buffer_t message_buffer,
 139             const gss_buffer_t token_buffer,
 140             gss_qop_t * qop_state,
 141             krb5_keyblock *key,
 142             char *type
 143             )
 144 {
 145   u_char *p;
 146   u_char *seq;
 147   uint32_t seq_number;
 148   OM_uint32 ret;
 149   krb5_crypto crypto;
 150   krb5_data seq_data;
 151   int cmp, docompat;
 152   Checksum csum;
 153   char *tmp;
 154   char ivec[8];
 155
 156   p = token_buffer->value;
 157   ret = _gsskrb5_verify_header (&p,
 158                                    token_buffer->length,
 159                                    type,
 160                                    GSS_KRB5_MECHANISM);
 161   if (ret)
 162       return ret;
 163
 164   if (memcmp(p, "\x04\x00", 2) != 0) /* SGN_ALG = HMAC SHA1 DES3-KD */
 165       return GSS_S_BAD_SIG;
 166   p += 2;
 167   if (memcmp (p, "\xff\xff\xff\xff", 4) != 0)
 168     return GSS_S_BAD_MIC;
 169   p += 4;
 170
 171   ret = krb5_crypto_init(context, key,
 172                          ETYPE_DES3_CBC_NONE, &crypto);
 173   if (ret){
 174       *minor_status = ret;
 175       return GSS_S_FAILURE;
 176   }
 177
 178   /* verify sequence number */
 179   docompat = 0;
 180 retry:
 181   if (docompat)
 182       memset(ivec, 0, 8);
 183   else
 184       memcpy(ivec, p + 8, 8);
 185
 186   ret = krb5_decrypt_ivec (context,
 187                            crypto,
 188                            KRB5_KU_USAGE_SEQ,
 189                            p, 8, &seq_data, ivec);
 190   if (ret) {
 191       if (docompat++) {
 192           krb5_crypto_destroy (context, crypto);
 193           *minor_status = ret;
 194           return GSS_S_FAILURE;
 195       } else
 196           goto retry;
 197   }
 198
 199   if (seq_data.length != 8) {
 200       krb5_data_free (&seq_data);
 201       if (docompat++) {
 202           krb5_crypto_destroy (context, crypto);
 203           return GSS_S_BAD_MIC;
 204       } else
 205           goto retry;
 206   }
 207
 208   HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
 209
 210   seq = seq_data.data;
 211   _gsskrb5_decode_om_uint32(seq, &seq_number);
 212
 213   if (context_handle->more_flags & LOCAL)
 214       cmp = ct_memcmp(&seq[4], "\xff\xff\xff\xff", 4);
 215   else
 216       cmp = ct_memcmp(&seq[4], "\x00\x00\x00\x00", 4);
 217
 218   krb5_data_free (&seq_data);
 219   if (cmp != 0) {
 220       krb5_crypto_destroy (context, crypto);
 221       *minor_status = 0;
 222       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 223       return GSS_S_BAD_MIC;
 224   }
 225
 226   ret = _gssapi_msg_order_check(context_handle->order, seq_number);
 227   if (ret) {
 228       krb5_crypto_destroy (context, crypto);
 229       *minor_status = 0;
 230       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 231       return ret;
 232   }
 233
 234   /* verify checksum */
 235
 236   tmp = malloc (message_buffer->length + 8);
 237   if (tmp == NULL) {
 238       krb5_crypto_destroy (context, crypto);
 239       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 240       *minor_status = ENOMEM;
 241       return GSS_S_FAILURE;
 242   }
 243
 244   memcpy (tmp, p - 8, 8);
 245   memcpy (tmp + 8, message_buffer->value, message_buffer->length);
 246
 247   csum.cksumtype = CKSUMTYPE_HMAC_SHA1_DES3;
 248   csum.checksum.length = 20;
 249   csum.checksum.data   = p + 8;
 250
 251   ret = krb5_verify_checksum (context, crypto,
 252                               KRB5_KU_USAGE_SIGN,
 253                               tmp, message_buffer->length + 8,
 254                               &csum);
 255   free (tmp);
 256   if (ret) {
 257       krb5_crypto_destroy (context, crypto);
 258       *minor_status = ret;
 259       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 260       return GSS_S_BAD_MIC;
 261   }
 262   HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 263
 264   krb5_crypto_destroy (context, crypto);
 265   return GSS_S_COMPLETE;
 266 }
 267
 268 OM_uint32
 269 _gsskrb5_verify_mic_internal
 270            (OM_uint32 * minor_status,
 271             const gsskrb5_ctx ctx,
 272             krb5_context context,
 273             const gss_buffer_t message_buffer,
 274             const gss_buffer_t token_buffer,
 275             gss_qop_t * qop_state,
 276             char * type
 277             )
 278 {
 279     krb5_keyblock *key;
 280     OM_uint32 ret;
 281     krb5_keytype keytype;
 282
 283     if (ctx->more_flags & IS_CFX)
 284         return _gssapi_verify_mic_cfx (minor_status, ctx,
 285                                        context, message_buffer, token_buffer,
 286                                        qop_state);
 287
 288     HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
 289     ret = _gsskrb5i_get_token_key(ctx, context, &key);
 290     HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 291     if (ret) {
 292         *minor_status = ret;
 293         return GSS_S_FAILURE;
 294     }
 295     *minor_status = 0;
 296     krb5_enctype_to_keytype (context, key->keytype, &keytype);
 297     switch (keytype) {
 298     case KEYTYPE_DES :
 299         ret = verify_mic_des (minor_status, ctx, context,
 300                               message_buffer, token_buffer, qop_state, key,
 301                               type);
 302         break;
 303     case KEYTYPE_DES3 :
 304         ret = verify_mic_des3 (minor_status, ctx, context,
 305                                message_buffer, token_buffer, qop_state, key,
 306                                type);
 307         break;
 308     case KEYTYPE_ARCFOUR :
 309     case KEYTYPE_ARCFOUR_56 :
 310         ret = _gssapi_verify_mic_arcfour (minor_status, ctx,
 311                                           context,
 312                                           message_buffer, token_buffer,
 313                                           qop_state, key, type);
 314         break;
 315     default :
 316         abort();
 317     }
 318     krb5_free_keyblock (context, key);
 319
 320     return ret;
 321 }
 322
 323 OM_uint32
 324 _gsskrb5_verify_mic
 325            (OM_uint32 * minor_status,
 326             const gss_ctx_id_t context_handle,
 327             const gss_buffer_t message_buffer,
 328             const gss_buffer_t token_buffer,
 329             gss_qop_t * qop_state
 330             )
 331 {
 332     krb5_context context;
 333     OM_uint32 ret;
 334
 335     GSSAPI_KRB5_INIT (&context);
 336
 337     if (qop_state != NULL)
 338         *qop_state = GSS_C_QOP_DEFAULT;
 339
 340     ret = _gsskrb5_verify_mic_internal(minor_status,
 341                                        (gsskrb5_ctx)context_handle,
 342                                        context,
 343                                        message_buffer, token_buffer,
 344                                        qop_state, "\x01\x01");
 345
 346     return ret;
 347 }