verify_mic.c revision 233294 
1/*
2 * Copyright (c) 1997 - 2003 Kungliga Tekniska H��gskolan
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
38static OM_uint32
39verify_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
136static OM_uint32
137verify_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;
183retry:
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  ret = krb5_verify_checksum (context, crypto,
255			      KRB5_KU_USAGE_SIGN,
256			      tmp, message_buffer->length + 8,
257			      &csum);
258  free (tmp);
259  if (ret) {
260      krb5_crypto_destroy (context, crypto);
261      *minor_status = ret;
262      HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
263      return GSS_S_BAD_MIC;
264  }
265  HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
266
267  krb5_crypto_destroy (context, crypto);
268  return GSS_S_COMPLETE;
269}
270
271OM_uint32
272_gsskrb5_verify_mic_internal
273           (OM_uint32 * minor_status,
274            const gsskrb5_ctx ctx,
275	    krb5_context context,
276            const gss_buffer_t message_buffer,
277            const gss_buffer_t token_buffer,
278            gss_qop_t * qop_state,
279	    const char * type
280	    )
281{
282    krb5_keyblock *key;
283    OM_uint32 ret;
284    krb5_keytype keytype;
285
286    if (ctx->more_flags & IS_CFX)
287        return _gssapi_verify_mic_cfx (minor_status, ctx,
288				       context, message_buffer, token_buffer,
289				       qop_state);
290
291    HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
292    ret = _gsskrb5i_get_token_key(ctx, context, &key);
293    HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
294    if (ret) {
295	*minor_status = ret;
296	return GSS_S_FAILURE;
297    }
298    *minor_status = 0;
299    krb5_enctype_to_keytype (context, key->keytype, &keytype);
300    switch (keytype) {
301    case KEYTYPE_DES :
302#ifdef HEIM_WEAK_CRYPTO
303	ret = verify_mic_des (minor_status, ctx, context,
304			      message_buffer, token_buffer, qop_state, key,
305			      type);
306#else
307      ret = GSS_S_FAILURE;
308#endif
309	break;
310    case KEYTYPE_DES3 :
311	ret = verify_mic_des3 (minor_status, ctx, context,
312			       message_buffer, token_buffer, qop_state, key,
313			       type);
314	break;
315    case KEYTYPE_ARCFOUR :
316    case KEYTYPE_ARCFOUR_56 :
317	ret = _gssapi_verify_mic_arcfour (minor_status, ctx,
318					  context,
319					  message_buffer, token_buffer,
320					  qop_state, key, type);
321	break;
322    default :
323        abort();
324    }
325    krb5_free_keyblock (context, key);
326
327    return ret;
328}
329
330OM_uint32 GSSAPI_CALLCONV
331_gsskrb5_verify_mic
332           (OM_uint32 * minor_status,
333            const gss_ctx_id_t context_handle,
334            const gss_buffer_t message_buffer,
335            const gss_buffer_t token_buffer,
336            gss_qop_t * qop_state
337	    )
338{
339    krb5_context context;
340    OM_uint32 ret;
341
342    GSSAPI_KRB5_INIT (&context);
343
344    if (qop_state != NULL)
345	*qop_state = GSS_C_QOP_DEFAULT;
346
347    ret = _gsskrb5_verify_mic_internal(minor_status,
348				       (gsskrb5_ctx)context_handle,
349				       context,
350				       message_buffer, token_buffer,
351				       qop_state, (void *)(intptr_t)"\x01\x01");
352
353    return ret;
354}
355