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 static OM_uint32
  37 unwrap_des
  38            (OM_uint32 * minor_status,
  39             const gsskrb5_ctx context_handle,
  40             const gss_buffer_t input_message_buffer,
  41             gss_buffer_t output_message_buffer,
  42             int * conf_state,
  43             gss_qop_t * qop_state,
  44             krb5_keyblock *key
  45            )
  46 {
  47   u_char *p, *seq;
  48   size_t len;
  49   MD5_CTX md5;
  50   u_char hash[16];
  51   DES_key_schedule schedule;
  52   DES_cblock deskey;
  53   DES_cblock zero;
  54   int i;
  55   uint32_t seq_number;
  56   size_t padlength;
  57   OM_uint32 ret;
  58   int cstate;
  59   int cmp;
  60
  61   p = input_message_buffer->value;
  62   ret = _gsskrb5_verify_header (&p,
  63                                    input_message_buffer->length,
  64                                    "\x02\x01",
  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, "\x00\x00", 2) == 0) {
  73       cstate = 1;
  74   } else if (memcmp (p, "\xFF\xFF", 2) == 0) {
  75       cstate = 0;
  76   } else
  77       return GSS_S_BAD_MIC;
  78   p += 2;
  79   if(conf_state != NULL)
  80       *conf_state = cstate;
  81   if (memcmp (p, "\xff\xff", 2) != 0)
  82     return GSS_S_DEFECTIVE_TOKEN;
  83   p += 2;
  84   p += 16;
  85
  86   len = p - (u_char *)input_message_buffer->value;
  87
  88   if(cstate) {
  89       /* decrypt data */
  90       memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
  91
  92       for (i = 0; i < sizeof(deskey); ++i)
  93           deskey[i] ^= 0xf0;
  94       DES_set_key_unchecked (&deskey, &schedule);
  95       memset (&zero, 0, sizeof(zero));
  96       DES_cbc_encrypt ((void *)p,
  97                        (void *)p,
  98                        input_message_buffer->length - len,
  99                        &schedule,
 100                        &zero,
 101                        DES_DECRYPT);
 102
 103       memset (deskey, 0, sizeof(deskey));
 104       memset (&schedule, 0, sizeof(schedule));
 105   }
 106   /* check pad */
 107   ret = _gssapi_verify_pad(input_message_buffer,
 108                            input_message_buffer->length - len,
 109                            &padlength);
 110   if (ret)
 111       return ret;
 112
 113   MD5_Init (&md5);
 114   MD5_Update (&md5, p - 24, 8);
 115   MD5_Update (&md5, p, input_message_buffer->length - len);
 116   MD5_Final (hash, &md5);
 117
 118   memset (&zero, 0, sizeof(zero));
 119   memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
 120   DES_set_key_unchecked (&deskey, &schedule);
 121   DES_cbc_cksum ((void *)hash, (void *)hash, sizeof(hash),
 122                  &schedule, &zero);
 123   if (memcmp (p - 8, hash, 8) != 0)
 124     return GSS_S_BAD_MIC;
 125
 126   /* verify sequence number */
 127
 128   HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
 129
 130   p -= 16;
 131   DES_set_key_unchecked (&deskey, &schedule);
 132   DES_cbc_encrypt ((void *)p, (void *)p, 8,
 133                    &schedule, (DES_cblock *)hash, DES_DECRYPT);
 134
 135   memset (deskey, 0, sizeof(deskey));
 136   memset (&schedule, 0, sizeof(schedule));
 137
 138   seq = p;
 139   _gsskrb5_decode_om_uint32(seq, &seq_number);
 140
 141   if (context_handle->more_flags & LOCAL)
 142       cmp = memcmp(&seq[4], "\xff\xff\xff\xff", 4);
 143   else
 144       cmp = memcmp(&seq[4], "\x00\x00\x00\x00", 4);
 145
 146   if (cmp != 0) {
 147     HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 148     return GSS_S_BAD_MIC;
 149   }
 150
 151   ret = _gssapi_msg_order_check(context_handle->order, seq_number);
 152   if (ret) {
 153     HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 154     return ret;
 155   }
 156
 157   HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 158
 159   /* copy out data */
 160
 161   output_message_buffer->length = input_message_buffer->length
 162     - len - padlength - 8;
 163   output_message_buffer->value  = malloc(output_message_buffer->length);
 164   if(output_message_buffer->length != 0 && output_message_buffer->value == NULL)
 165       return GSS_S_FAILURE;
 166   memcpy (output_message_buffer->value,
 167           p + 24,
 168           output_message_buffer->length);
 169   return GSS_S_COMPLETE;
 170 }
 171
 172 static OM_uint32
 173 unwrap_des3
 174            (OM_uint32 * minor_status,
 175             const gsskrb5_ctx context_handle,
 176             krb5_context context,
 177             const gss_buffer_t input_message_buffer,
 178             gss_buffer_t output_message_buffer,
 179             int * conf_state,
 180             gss_qop_t * qop_state,
 181             krb5_keyblock *key
 182            )
 183 {
 184   u_char *p;
 185   size_t len;
 186   u_char *seq;
 187   krb5_data seq_data;
 188   u_char cksum[20];
 189   uint32_t seq_number;
 190   size_t padlength;
 191   OM_uint32 ret;
 192   int cstate;
 193   krb5_crypto crypto;
 194   Checksum csum;
 195   int cmp;
 196
 197   p = input_message_buffer->value;
 198   ret = _gsskrb5_verify_header (&p,
 199                                    input_message_buffer->length,
 200                                    "\x02\x01",
 201                                    GSS_KRB5_MECHANISM);
 202   if (ret)
 203       return ret;
 204
 205   if (memcmp (p, "\x04\x00", 2) != 0) /* HMAC SHA1 DES3_KD */
 206     return GSS_S_BAD_SIG;
 207   p += 2;
 208   if (memcmp (p, "\x02\x00", 2) == 0) {
 209     cstate = 1;
 210   } else if (memcmp (p, "\xff\xff", 2) == 0) {
 211     cstate = 0;
 212   } else
 213     return GSS_S_BAD_MIC;
 214   p += 2;
 215   if(conf_state != NULL)
 216     *conf_state = cstate;
 217   if (memcmp (p, "\xff\xff", 2) != 0)
 218     return GSS_S_DEFECTIVE_TOKEN;
 219   p += 2;
 220   p += 28;
 221
 222   len = p - (u_char *)input_message_buffer->value;
 223
 224   if(cstate) {
 225       /* decrypt data */
 226       krb5_data tmp;
 227
 228       ret = krb5_crypto_init(context, key,
 229                              ETYPE_DES3_CBC_NONE, &crypto);
 230       if (ret) {
 231           *minor_status = ret;
 232           return GSS_S_FAILURE;
 233       }
 234       ret = krb5_decrypt(context, crypto, KRB5_KU_USAGE_SEAL,
 235                          p, input_message_buffer->length - len, &tmp);
 236       krb5_crypto_destroy(context, crypto);
 237       if (ret) {
 238           *minor_status = ret;
 239           return GSS_S_FAILURE;
 240       }
 241       assert (tmp.length == input_message_buffer->length - len);
 242
 243       memcpy (p, tmp.data, tmp.length);
 244       krb5_data_free(&tmp);
 245   }
 246   /* check pad */
 247   ret = _gssapi_verify_pad(input_message_buffer,
 248                            input_message_buffer->length - len,
 249                            &padlength);
 250   if (ret)
 251       return ret;
 252
 253   /* verify sequence number */
 254
 255   HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
 256
 257   p -= 28;
 258
 259   ret = krb5_crypto_init(context, key,
 260                          ETYPE_DES3_CBC_NONE, &crypto);
 261   if (ret) {
 262       *minor_status = ret;
 263       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 264       return GSS_S_FAILURE;
 265   }
 266   {
 267       DES_cblock ivec;
 268
 269       memcpy(&ivec, p + 8, 8);
 270       ret = krb5_decrypt_ivec (context,
 271                                crypto,
 272                                KRB5_KU_USAGE_SEQ,
 273                                p, 8, &seq_data,
 274                                &ivec);
 275   }
 276   krb5_crypto_destroy (context, crypto);
 277   if (ret) {
 278       *minor_status = ret;
 279       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 280       return GSS_S_FAILURE;
 281   }
 282   if (seq_data.length != 8) {
 283       krb5_data_free (&seq_data);
 284       *minor_status = 0;
 285       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 286       return GSS_S_BAD_MIC;
 287   }
 288
 289   seq = seq_data.data;
 290   _gsskrb5_decode_om_uint32(seq, &seq_number);
 291
 292   if (context_handle->more_flags & LOCAL)
 293       cmp = memcmp(&seq[4], "\xff\xff\xff\xff", 4);
 294   else
 295       cmp = memcmp(&seq[4], "\x00\x00\x00\x00", 4);
 296
 297   krb5_data_free (&seq_data);
 298   if (cmp != 0) {
 299       *minor_status = 0;
 300       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 301       return GSS_S_BAD_MIC;
 302   }
 303
 304   ret = _gssapi_msg_order_check(context_handle->order, seq_number);
 305   if (ret) {
 306       *minor_status = 0;
 307       HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 308       return ret;
 309   }
 310
 311   HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
 312
 313   /* verify checksum */
 314
 315   memcpy (cksum, p + 8, 20);
 316
 317   memcpy (p + 20, p - 8, 8);
 318
 319   csum.cksumtype = CKSUMTYPE_HMAC_SHA1_DES3;
 320   csum.checksum.length = 20;
 321   csum.checksum.data   = cksum;
 322
 323   ret = krb5_crypto_init(context, key, 0, &crypto);
 324   if (ret) {
 325       *minor_status = ret;
 326       return GSS_S_FAILURE;
 327   }
 328
 329   ret = krb5_verify_checksum (context, crypto,
 330                               KRB5_KU_USAGE_SIGN,
 331                               p + 20,
 332                               input_message_buffer->length - len + 8,
 333                               &csum);
 334   krb5_crypto_destroy (context, crypto);
 335   if (ret) {
 336       *minor_status = ret;
 337       return GSS_S_FAILURE;
 338   }
 339
 340   /* copy out data */
 341
 342   output_message_buffer->length = input_message_buffer->length
 343     - len - padlength - 8;
 344   output_message_buffer->value  = malloc(output_message_buffer->length);
 345   if(output_message_buffer->length != 0 && output_message_buffer->value == NULL)
 346       return GSS_S_FAILURE;
 347   memcpy (output_message_buffer->value,
 348           p + 36,
 349           output_message_buffer->length);
 350   return GSS_S_COMPLETE;
 351 }
 352
 353 OM_uint32 _gsskrb5_unwrap
 354            (OM_uint32 * minor_status,
 355             const gss_ctx_id_t context_handle,
 356             const gss_buffer_t input_message_buffer,
 357             gss_buffer_t output_message_buffer,
 358             int * conf_state,
 359             gss_qop_t * qop_state
 360            )
 361 {
 362   krb5_keyblock *key;
 363   krb5_context context;
 364   OM_uint32 ret;
 365   krb5_keytype keytype;
 366   gsskrb5_ctx ctx = (gsskrb5_ctx) context_handle;
 367
 368   output_message_buffer->value = NULL;
 369   output_message_buffer->length = 0;
 370   if (qop_state != NULL)
 371       *qop_state = GSS_C_QOP_DEFAULT;
 372
 373   GSSAPI_KRB5_INIT (&context);
 374
 375   if (ctx->more_flags & IS_CFX)
 376       return _gssapi_unwrap_cfx (minor_status, ctx, context,
 377                                  input_message_buffer, output_message_buffer,
 378                                  conf_state, qop_state);
 379
 380   HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
 381   ret = _gsskrb5i_get_token_key(ctx, context, &key);
 382   HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
 383   if (ret) {
 384       *minor_status = ret;
 385       return GSS_S_FAILURE;
 386   }
 387   krb5_enctype_to_keytype (context, key->keytype, &keytype);
 388
 389   *minor_status = 0;
 390
 391   switch (keytype) {
 392   case KEYTYPE_DES :
 393       ret = unwrap_des (minor_status, ctx,
 394                         input_message_buffer, output_message_buffer,
 395                         conf_state, qop_state, key);
 396       break;
 397   case KEYTYPE_DES3 :
 398       ret = unwrap_des3 (minor_status, ctx, context,
 399                          input_message_buffer, output_message_buffer,
 400                          conf_state, qop_state, key);
 401       break;
 402   case KEYTYPE_ARCFOUR:
 403   case KEYTYPE_ARCFOUR_56:
 404       ret = _gssapi_unwrap_arcfour (minor_status, ctx, context,
 405                                     input_message_buffer, output_message_buffer,
 406                                     conf_state, qop_state, key);
 407       break;
 408   default :
 409       abort();
 410       break;
 411   }
 412   krb5_free_keyblock (context, key);
 413   return ret;
 414 }