lib/gssapi/unwrap.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 "gssapi_locl.h"
  35
  36 RCSID("$Id$");
  37
  38 OM_uint32
  39 gss_krb5_get_remotekey(const gss_ctx_id_t context_handle,
  40                        krb5_keyblock **key)
  41 {
  42     krb5_keyblock *skey;
  43
  44     krb5_auth_con_getremotesubkey(gssapi_krb5_context,
  45                                   context_handle->auth_context,
  46                                   &skey);
  47     if(skey == NULL)
  48         krb5_auth_con_getlocalsubkey(gssapi_krb5_context,
  49                                      context_handle->auth_context,
  50                                      &skey);
  51     if(skey == NULL)
  52         krb5_auth_con_getkey(gssapi_krb5_context,
  53                              context_handle->auth_context,
  54                              &skey);
  55     if(skey == NULL)
  56         return GSS_KRB5_S_KG_NO_SUBKEY; /* XXX */
  57     *key = skey;
  58     return 0;
  59 }
  60
  61 static OM_uint32
  62 unwrap_des
  63            (OM_uint32 * minor_status,
  64             const gss_ctx_id_t context_handle,
  65             const gss_buffer_t input_message_buffer,
  66             gss_buffer_t output_message_buffer,
  67             int * conf_state,
  68             gss_qop_t * qop_state,
  69             krb5_keyblock *key
  70            )
  71 {
  72   u_char *p, *pad;
  73   size_t len;
  74   MD5_CTX md5;
  75   u_char hash[16], seq_data[8];
  76   des_key_schedule schedule;
  77   des_cblock deskey;
  78   des_cblock zero;
  79   int i;
  80   int32_t seq_number;
  81   size_t padlength;
  82   OM_uint32 ret;
  83   int cstate;
  84
  85   p = input_message_buffer->value;
  86   ret = gssapi_krb5_verify_header (&p,
  87                                    input_message_buffer->length,
  88                                    "\x02\x01");
  89   if (ret)
  90       return ret;
  91
  92   if (memcmp (p, "\x00\x00", 2) != 0)
  93     return GSS_S_BAD_SIG;
  94   p += 2;
  95   if (memcmp (p, "\x00\x00", 2) == 0) {
  96       cstate = 1;
  97   } else if (memcmp (p, "\xFF\xFF", 2) == 0) {
  98       cstate = 0;
  99   } else
 100       return GSS_S_BAD_MIC;
 101   p += 2;
 102   if(conf_state != NULL)
 103       *conf_state = cstate;
 104   if (memcmp (p, "\xff\xff", 2) != 0)
 105     return GSS_S_DEFECTIVE_TOKEN;
 106   p += 2;
 107   p += 16;
 108
 109   len = p - (u_char *)input_message_buffer->value;
 110
 111   if(cstate) {
 112       /* decrypt data */
 113       memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
 114
 115       for (i = 0; i < sizeof(deskey); ++i)
 116           deskey[i] ^= 0xf0;
 117       des_set_key (&deskey, schedule);
 118       memset (&zero, 0, sizeof(zero));
 119       des_cbc_encrypt ((void *)p,
 120                        (void *)p,
 121                        input_message_buffer->length - len,
 122                        schedule,
 123                        &zero,
 124                        DES_DECRYPT);
 125
 126       memset (deskey, 0, sizeof(deskey));
 127       memset (schedule, 0, sizeof(schedule));
 128   }
 129   /* check pad */
 130
 131   pad = (u_char *)input_message_buffer->value + input_message_buffer->length - 1;
 132   padlength = *pad;
 133
 134   for (i = padlength; i > 0 && *pad == padlength; i--, pad--)
 135     ;
 136   if (i != 0)
 137     return GSS_S_BAD_MIC;
 138
 139   MD5_Init (&md5);
 140   MD5_Update (&md5, p - 24, 8);
 141   MD5_Update (&md5, p, input_message_buffer->length - len);
 142   MD5_Final (hash, &md5);
 143
 144   memset (&zero, 0, sizeof(zero));
 145   memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
 146   des_set_key (&deskey, schedule);
 147   des_cbc_cksum ((void *)hash, (void *)hash, sizeof(hash),
 148                  schedule, &zero);
 149   if (memcmp (p - 8, hash, 8) != 0)
 150     return GSS_S_BAD_MIC;
 151
 152   /* verify sequence number */
 153
 154   krb5_auth_getremoteseqnumber (gssapi_krb5_context,
 155                                 context_handle->auth_context,
 156                                 &seq_number);
 157   seq_data[0] = (seq_number >> 0)  & 0xFF;
 158   seq_data[1] = (seq_number >> 8)  & 0xFF;
 159   seq_data[2] = (seq_number >> 16) & 0xFF;
 160   seq_data[3] = (seq_number >> 24) & 0xFF;
 161   memset (seq_data + 4,
 162           (context_handle->more_flags & LOCAL) ? 0xFF : 0,
 163           4);
 164
 165   p -= 16;
 166   des_set_key (&deskey, schedule);
 167   des_cbc_encrypt ((void *)p, (void *)p, 8,
 168                    schedule, (des_cblock *)hash, DES_DECRYPT);
 169
 170   memset (deskey, 0, sizeof(deskey));
 171   memset (schedule, 0, sizeof(schedule));
 172
 173   if (memcmp (p, seq_data, 8) != 0) {
 174     return GSS_S_BAD_MIC;
 175   }
 176
 177   krb5_auth_con_setremoteseqnumber (gssapi_krb5_context,
 178                                 context_handle->auth_context,
 179                                 ++seq_number);
 180
 181   /* copy out data */
 182
 183   output_message_buffer->length = input_message_buffer->length
 184     - len - padlength - 8;
 185   output_message_buffer->value  = malloc(output_message_buffer->length);
 186   if(output_message_buffer->length != 0 && output_message_buffer->value == NULL)
 187       return GSS_S_FAILURE;
 188   memcpy (output_message_buffer->value,
 189           p + 24,
 190           output_message_buffer->length);
 191   return GSS_S_COMPLETE;
 192 }
 193
 194 static OM_uint32
 195 unwrap_des3
 196            (OM_uint32 * minor_status,
 197             const gss_ctx_id_t context_handle,
 198             const gss_buffer_t input_message_buffer,
 199             gss_buffer_t output_message_buffer,
 200             int * conf_state,
 201             gss_qop_t * qop_state,
 202             krb5_keyblock *key
 203            )
 204 {
 205   u_char *p, *pad;
 206   size_t len;
 207   u_char seq[8];
 208   krb5_data seq_data;
 209   u_char cksum[20];
 210   int i;
 211   int32_t seq_number;
 212   size_t padlength;
 213   OM_uint32 ret;
 214   int cstate;
 215   krb5_crypto crypto;
 216   Checksum csum;
 217   int cmp;
 218
 219   p = input_message_buffer->value;
 220   ret = gssapi_krb5_verify_header (&p,
 221                                    input_message_buffer->length,
 222                                    "\x02\x01");
 223   if (ret)
 224       return ret;
 225
 226   if (memcmp (p, "\x04\x00", 2) != 0) /* HMAC SHA1 DES3_KD */
 227     return GSS_S_BAD_SIG;
 228   p += 2;
 229   if (memcmp (p, "\x02\x00", 2) == 0) {
 230     cstate = 1;
 231   } else if (memcmp (p, "\xff\xff", 2) == 0) {
 232     cstate = 0;
 233   } else
 234     return GSS_S_BAD_MIC;
 235   p += 2;
 236   if(conf_state != NULL)
 237     *conf_state = cstate;
 238   if (memcmp (p, "\xff\xff", 2) != 0)
 239     return GSS_S_DEFECTIVE_TOKEN;
 240   p += 2;
 241   p += 28;
 242
 243   len = p - (u_char *)input_message_buffer->value;
 244
 245   if(cstate) {
 246       /* decrypt data */
 247       krb5_data tmp;
 248
 249       ret = krb5_crypto_init(gssapi_krb5_context, key,
 250                              ETYPE_DES3_CBC_NONE, &crypto);
 251       if (ret) {
 252           gssapi_krb5_set_error_string ();
 253           *minor_status = ret;
 254           return GSS_S_FAILURE;
 255       }
 256       ret = krb5_decrypt(gssapi_krb5_context, crypto, KRB5_KU_USAGE_SEAL,
 257                          p, input_message_buffer->length - len, &tmp);
 258       krb5_crypto_destroy(gssapi_krb5_context, crypto);
 259       if (ret) {
 260           gssapi_krb5_set_error_string ();
 261           *minor_status = ret;
 262           return GSS_S_FAILURE;
 263       }
 264       assert (tmp.length == input_message_buffer->length - len);
 265
 266       memcpy (p, tmp.data, tmp.length);
 267       krb5_data_free(&tmp);
 268   }
 269   /* check pad */
 270
 271   pad = (u_char *)input_message_buffer->value + input_message_buffer->length - 1;
 272   padlength = *pad;
 273
 274   for (i = padlength; i > 0 && *pad == padlength; i--, pad--)
 275     ;
 276   if (i != 0)
 277     return GSS_S_BAD_MIC;
 278
 279   /* verify sequence number */
 280
 281   krb5_auth_getremoteseqnumber (gssapi_krb5_context,
 282                                 context_handle->auth_context,
 283                                 &seq_number);
 284   seq[0] = (seq_number >> 0)  & 0xFF;
 285   seq[1] = (seq_number >> 8)  & 0xFF;
 286   seq[2] = (seq_number >> 16) & 0xFF;
 287   seq[3] = (seq_number >> 24) & 0xFF;
 288   memset (seq + 4,
 289           (context_handle->more_flags & LOCAL) ? 0xFF : 0,
 290           4);
 291
 292   p -= 28;
 293
 294   ret = krb5_crypto_init(gssapi_krb5_context, key,
 295                          ETYPE_DES3_CBC_NONE, &crypto);
 296   if (ret) {
 297       gssapi_krb5_set_error_string ();
 298       *minor_status = ret;
 299       return GSS_S_FAILURE;
 300   }
 301   {
 302       des_cblock ivec;
 303
 304       memcpy(&ivec, p + 8, 8);
 305       ret = krb5_decrypt_ivec (gssapi_krb5_context,
 306                                crypto,
 307                                KRB5_KU_USAGE_SEQ,
 308                                p, 8, &seq_data,
 309                                &ivec);
 310   }
 311   krb5_crypto_destroy (gssapi_krb5_context, crypto);
 312   if (ret) {
 313       gssapi_krb5_set_error_string ();
 314       *minor_status = ret;
 315       return GSS_S_FAILURE;
 316   }
 317   if (seq_data.length != 8) {
 318       krb5_data_free (&seq_data);
 319       return GSS_S_BAD_MIC;
 320   }
 321
 322   cmp = memcmp (seq, seq_data.data, seq_data.length);
 323   krb5_data_free (&seq_data);
 324   if (cmp != 0) {
 325       return GSS_S_BAD_MIC;
 326   }
 327
 328   krb5_auth_con_setremoteseqnumber (gssapi_krb5_context,
 329                                 context_handle->auth_context,
 330                                 ++seq_number);
 331
 332   /* verify checksum */
 333
 334   memcpy (cksum, p + 8, 20);
 335
 336   memcpy (p + 20, p - 8, 8);
 337
 338   csum.cksumtype = CKSUMTYPE_HMAC_SHA1_DES3;
 339   csum.checksum.length = 20;
 340   csum.checksum.data   = cksum;
 341
 342   ret = krb5_crypto_init(gssapi_krb5_context, key, 0, &crypto);
 343   if (ret) {
 344       gssapi_krb5_set_error_string ();
 345       *minor_status = ret;
 346       return GSS_S_FAILURE;
 347   }
 348
 349   ret = krb5_verify_checksum (gssapi_krb5_context, crypto,
 350                               KRB5_KU_USAGE_SIGN,
 351                               p + 20,
 352                               input_message_buffer->length - len + 8,
 353                               &csum);
 354   krb5_crypto_destroy (gssapi_krb5_context, crypto);
 355   if (ret) {
 356       gssapi_krb5_set_error_string ();
 357       *minor_status = ret;
 358       return GSS_S_FAILURE;
 359   }
 360
 361   /* copy out data */
 362
 363   output_message_buffer->length = input_message_buffer->length
 364     - len - padlength - 8;
 365   output_message_buffer->value  = malloc(output_message_buffer->length);
 366   if(output_message_buffer->length != 0 && output_message_buffer->value == NULL)
 367       return GSS_S_FAILURE;
 368   memcpy (output_message_buffer->value,
 369           p + 36,
 370           output_message_buffer->length);
 371   return GSS_S_COMPLETE;
 372 }
 373
 374 OM_uint32 gss_unwrap
 375            (OM_uint32 * minor_status,
 376             const gss_ctx_id_t context_handle,
 377             const gss_buffer_t input_message_buffer,
 378             gss_buffer_t output_message_buffer,
 379             int * conf_state,
 380             gss_qop_t * qop_state
 381            )
 382 {
 383   krb5_keyblock *key;
 384   OM_uint32 ret;
 385   krb5_keytype keytype;
 386
 387   if (qop_state != NULL)
 388       *qop_state = GSS_C_QOP_DEFAULT;
 389   ret = gss_krb5_get_remotekey(context_handle, &key);
 390   if (ret) {
 391       gssapi_krb5_set_error_string ();
 392       *minor_status = ret;
 393       return GSS_S_FAILURE;
 394   }
 395   krb5_enctype_to_keytype (gssapi_krb5_context, key->keytype, &keytype);
 396
 397   *minor_status = 0;
 398
 399   switch (keytype) {
 400   case KEYTYPE_DES :
 401       ret = unwrap_des (minor_status, context_handle,
 402                         input_message_buffer, output_message_buffer,
 403                         conf_state, qop_state, key);
 404       break;
 405   case KEYTYPE_DES3 :
 406       ret = unwrap_des3 (minor_status, context_handle,
 407                          input_message_buffer, output_message_buffer,
 408                          conf_state, qop_state, key);
 409       break;
 410   case KEYTYPE_ARCFOUR:
 411       ret = _gssapi_unwrap_arcfour (minor_status, context_handle,
 412                                     input_message_buffer, output_message_buffer,
 413                                     conf_state, qop_state, key);
 414       break;
 415   default :
 416       *minor_status = KRB5_PROG_ETYPE_NOSUPP;
 417       ret = GSS_S_FAILURE;
 418       break;
 419   }
 420   krb5_free_keyblock (gssapi_krb5_context, key);
 421   return ret;
 422 }