lib/gssapi/krb5/verify_mic.c

   1 /*
   2  * Copyright (c) 1997 - 2001 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 static OM_uint32
  39 verify_mic_des
  40            (OM_uint32 * minor_status,
  41             const gss_ctx_id_t context_handle,
  42             const gss_buffer_t message_buffer,
  43             const gss_buffer_t token_buffer,
  44             gss_qop_t * qop_state,
  45             krb5_keyblock *key
  46             )
  47 {
  48   u_char *p;
  49   MD5_CTX md5;
  50   u_char hash[16], seq_data[8];
  51   des_key_schedule schedule;
  52   des_cblock zero;
  53   des_cblock deskey;
  54   int32_t seq_number;
  55   OM_uint32 ret;
  56
  57   p = token_buffer->value;
  58   ret = gssapi_krb5_verify_header (&p,
  59                                    token_buffer->length,
  60                                    "\x01\x01");
  61   if (ret) {
  62       *minor_status = 0;
  63       return ret;
  64   }
  65
  66   if (memcmp(p, "\x00\x00", 2) != 0)
  67       return GSS_S_BAD_SIG;
  68   p += 2;
  69   if (memcmp (p, "\xff\xff\xff\xff", 4) != 0)
  70     return GSS_S_BAD_MIC;
  71   p += 4;
  72   p += 16;
  73
  74   /* verify checksum */
  75   MD5_Init (&md5);
  76   MD5_Update (&md5, p - 24, 8);
  77   MD5_Update (&md5, message_buffer->value,
  78              message_buffer->length);
  79   MD5_Final (hash, &md5);
  80
  81   memset (&zero, 0, sizeof(zero));
  82   memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
  83
  84   des_set_key (&deskey, schedule);
  85   des_cbc_cksum ((void *)hash, (void *)hash, sizeof(hash),
  86                  schedule, &zero);
  87   if (memcmp (p - 8, hash, 8) != 0) {
  88     memset (deskey, 0, sizeof(deskey));
  89     memset (schedule, 0, sizeof(schedule));
  90     return GSS_S_BAD_MIC;
  91   }
  92
  93   /* verify sequence number */
  94
  95   krb5_auth_getremoteseqnumber (gssapi_krb5_context,
  96                                 context_handle->auth_context,
  97                                 &seq_number);
  98   seq_data[0] = (seq_number >> 0)  & 0xFF;
  99   seq_data[1] = (seq_number >> 8)  & 0xFF;
 100   seq_data[2] = (seq_number >> 16) & 0xFF;
 101   seq_data[3] = (seq_number >> 24) & 0xFF;
 102   memset (seq_data + 4,
 103           (context_handle->more_flags & LOCAL) ? 0xFF : 0,
 104           4);
 105
 106   p -= 16;
 107   des_set_key (&deskey, schedule);
 108   des_cbc_encrypt ((void *)p, (void *)p, 8,
 109                    schedule, (des_cblock *)hash, DES_DECRYPT);
 110
 111   memset (deskey, 0, sizeof(deskey));
 112   memset (schedule, 0, sizeof(schedule));
 113
 114   if (memcmp (p, seq_data, 8) != 0) {
 115     return GSS_S_BAD_MIC;
 116   }
 117
 118   krb5_auth_con_setremoteseqnumber (gssapi_krb5_context,
 119                                 context_handle->auth_context,
 120                                 ++seq_number);
 121
 122   return GSS_S_COMPLETE;
 123 }
 124
 125 static OM_uint32
 126 verify_mic_des3
 127            (OM_uint32 * minor_status,
 128             const gss_ctx_id_t context_handle,
 129             const gss_buffer_t message_buffer,
 130             const gss_buffer_t token_buffer,
 131             gss_qop_t * qop_state,
 132             krb5_keyblock *key
 133             )
 134 {
 135   u_char *p;
 136   u_char seq[8];
 137   int32_t seq_number;
 138   OM_uint32 ret;
 139   krb5_crypto crypto;
 140   krb5_data seq_data;
 141   int cmp;
 142   Checksum csum;
 143   char *tmp;
 144
 145   p = token_buffer->value;
 146   ret = gssapi_krb5_verify_header (&p,
 147                                    token_buffer->length,
 148                                    "\x01\x01");
 149   if (ret) {
 150       *minor_status = 0;
 151       return ret;
 152   }
 153
 154   if (memcmp(p, "\x04\x00", 2) != 0) /* SGN_ALG = HMAC SHA1 DES3-KD */
 155       return GSS_S_BAD_SIG;
 156   p += 2;
 157   if (memcmp (p, "\xff\xff\xff\xff", 4) != 0)
 158     return GSS_S_BAD_MIC;
 159   p += 4;
 160
 161   ret = krb5_crypto_init(gssapi_krb5_context, key,
 162                          ETYPE_DES3_CBC_NONE, &crypto);
 163   if (ret){
 164       gssapi_krb5_set_error_string ();
 165       *minor_status = ret;
 166       return GSS_S_FAILURE;
 167   }
 168
 169   /* verify sequence number */
 170
 171   ret = krb5_decrypt (gssapi_krb5_context,
 172                       crypto,
 173                       KRB5_KU_USAGE_SEQ,
 174                       p, 8, &seq_data);
 175   if (ret) {
 176       gssapi_krb5_set_error_string ();
 177       krb5_crypto_destroy (gssapi_krb5_context, crypto);
 178       *minor_status = ret;
 179       return GSS_S_FAILURE;
 180   }
 181
 182   if (seq_data.length != 8) {
 183       krb5_crypto_destroy (gssapi_krb5_context, crypto);
 184       krb5_data_free (&seq_data);
 185       return GSS_S_BAD_MIC;
 186   }
 187
 188   krb5_auth_getremoteseqnumber (gssapi_krb5_context,
 189                                 context_handle->auth_context,
 190                                 &seq_number);
 191   seq[0] = (seq_number >> 0)  & 0xFF;
 192   seq[1] = (seq_number >> 8)  & 0xFF;
 193   seq[2] = (seq_number >> 16) & 0xFF;
 194   seq[3] = (seq_number >> 24) & 0xFF;
 195   memset (seq + 4,
 196           (context_handle->more_flags & LOCAL) ? 0xFF : 0,
 197           4);
 198   cmp = memcmp (seq, seq_data.data, seq_data.length);
 199   krb5_data_free (&seq_data);
 200   if (cmp != 0) {
 201       krb5_crypto_destroy (gssapi_krb5_context, crypto);
 202       return GSS_S_BAD_MIC;
 203   }
 204
 205   /* verify checksum */
 206
 207   tmp = malloc (message_buffer->length + 8);
 208   if (tmp == NULL) {
 209       krb5_crypto_destroy (gssapi_krb5_context, crypto);
 210       *minor_status = ENOMEM;
 211       return GSS_S_FAILURE;
 212   }
 213
 214   memcpy (tmp, p - 8, 8);
 215   memcpy (tmp + 8, message_buffer->value, message_buffer->length);
 216
 217   csum.cksumtype = CKSUMTYPE_HMAC_SHA1_DES3;
 218   csum.checksum.length = 20;
 219   csum.checksum.data   = p + 8;
 220
 221   ret = krb5_verify_checksum (gssapi_krb5_context, crypto,
 222                               KRB5_KU_USAGE_SIGN,
 223                               tmp, message_buffer->length + 8,
 224                               &csum);
 225   free (tmp);
 226   if (ret) {
 227       gssapi_krb5_set_error_string ();
 228       krb5_crypto_destroy (gssapi_krb5_context, crypto);
 229       *minor_status = ret;
 230       return GSS_S_BAD_MIC;
 231   }
 232
 233   krb5_auth_con_setremoteseqnumber (gssapi_krb5_context,
 234                                 context_handle->auth_context,
 235                                 ++seq_number);
 236
 237   krb5_crypto_destroy (gssapi_krb5_context, crypto);
 238   return GSS_S_COMPLETE;
 239 }
 240
 241 OM_uint32
 242 gss_verify_mic
 243            (OM_uint32 * minor_status,
 244             const gss_ctx_id_t context_handle,
 245             const gss_buffer_t message_buffer,
 246             const gss_buffer_t token_buffer,
 247             gss_qop_t * qop_state
 248             )
 249 {
 250     krb5_keyblock *key;
 251     OM_uint32 ret;
 252     krb5_keytype keytype;
 253
 254     if (qop_state != NULL)
 255         *qop_state = GSS_C_QOP_DEFAULT;
 256     ret = gss_krb5_get_remotekey(context_handle, &key);
 257     if (ret) {
 258         gssapi_krb5_set_error_string ();
 259         *minor_status = ret;
 260         return GSS_S_FAILURE;
 261     }
 262     krb5_enctype_to_keytype (gssapi_krb5_context, key->keytype, &keytype);
 263     switch (keytype) {
 264     case KEYTYPE_DES :
 265         ret = verify_mic_des (minor_status, context_handle,
 266                               message_buffer, token_buffer, qop_state, key);
 267         break;
 268     case KEYTYPE_DES3 :
 269         ret = verify_mic_des3 (minor_status, context_handle,
 270                                message_buffer, token_buffer, qop_state, key);
 271         break;
 272     default :
 273         *minor_status = KRB5_PROG_ETYPE_NOSUPP;
 274         ret = GSS_S_FAILURE;
 275         break;
 276     }
 277     krb5_free_keyblock (gssapi_krb5_context, key);
 278     return ret;
 279 }