1/*	$NetBSD: verify_mic.c,v 1.7 2023/06/19 21:41:43 christos Exp $	*/
2
3/*
4 * Copyright (c) 1997 - 2003 Kungliga Tekniska H��gskolan
5 * (Royal Institute of Technology, Stockholm, Sweden).
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * 3. Neither the name of the Institute nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36#include "gsskrb5_locl.h"
37
38#ifdef HEIM_WEAK_CRYPTO
39
40static OM_uint32
41verify_mic_des
42           (OM_uint32 * minor_status,
43            const gsskrb5_ctx context_handle,
44	    krb5_context context,
45            const gss_buffer_t message_buffer,
46            const gss_buffer_t token_buffer,
47            gss_qop_t * qop_state,
48	    krb5_keyblock *key,
49	    const char *type
50	    )
51{
52  u_char *p;
53  EVP_MD_CTX *md5;
54  u_char hash[16], *seq;
55  DES_key_schedule schedule;
56  EVP_CIPHER_CTX *des_ctx;
57  DES_cblock zero;
58  DES_cblock deskey;
59  uint32_t seq_number;
60  OM_uint32 ret;
61  int cmp;
62
63  p = token_buffer->value;
64  ret = _gsskrb5_verify_header (&p,
65				   token_buffer->length,
66				   type,
67				   GSS_KRB5_MECHANISM);
68  if (ret)
69      return ret;
70
71  if (memcmp(p, "\x00\x00", 2) != 0)
72      return GSS_S_BAD_SIG;
73  p += 2;
74  if (memcmp (p, "\xff\xff\xff\xff", 4) != 0)
75    return GSS_S_BAD_MIC;
76  p += 4;
77  p += 16;
78
79  /* verify checksum */
80  md5 = EVP_MD_CTX_create();
81  EVP_DigestInit_ex(md5, EVP_md5(), NULL);
82  EVP_DigestUpdate(md5, p - 24, 8);
83  EVP_DigestUpdate(md5, message_buffer->value, message_buffer->length);
84  EVP_DigestFinal_ex(md5, hash, NULL);
85  EVP_MD_CTX_destroy(md5);
86
87  memset (&zero, 0, sizeof(zero));
88  memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
89
90  DES_set_key_unchecked (&deskey, &schedule);
91  DES_cbc_cksum ((void *)hash, (void *)hash, sizeof(hash),
92		 &schedule, &zero);
93  if (ct_memcmp (p - 8, hash, 8) != 0) {
94    memset_s(deskey, sizeof(deskey), 0, sizeof(deskey));
95    memset_s(&schedule, sizeof(schedule), 0, sizeof(schedule));
96    return GSS_S_BAD_MIC;
97  }
98
99  /* verify sequence number */
100
101  HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
102
103  p -= 16;
104
105#if OPENSSL_VERSION_NUMBER < 0x10100000UL
106  EVP_CIPHER_CTX des_ctxs;
107  des_ctx = &des_ctxs;
108  EVP_CIPHER_CTX_init(des_ctx);
109#else
110  des_ctx = EVP_CIPHER_CTX_new();
111#endif
112  if (!EVP_CipherInit_ex(des_ctx, EVP_des_cbc(), NULL, key->keyvalue.data,
113      hash, 0)) {
114    *minor_status = EINVAL;
115    return GSS_S_FAILURE;
116  }
117  EVP_Cipher(des_ctx, p, p, 8);
118#if OPENSSL_VERSION_NUMBER < 0x10100000UL
119  EVP_CIPHER_CTX_cleanup(des_ctx);
120#else
121  EVP_CIPHER_CTX_free(des_ctx);
122#endif
123
124  memset_s(deskey, sizeof(deskey), 0, sizeof(deskey));
125  memset_s(&schedule, sizeof(schedule), 0, sizeof(schedule));
126
127  seq = p;
128  _gsskrb5_decode_om_uint32(seq, &seq_number);
129
130  if (context_handle->more_flags & LOCAL)
131      cmp = ct_memcmp(&seq[4], "\xff\xff\xff\xff", 4);
132  else
133      cmp = ct_memcmp(&seq[4], "\x00\x00\x00\x00", 4);
134
135  if (cmp != 0) {
136    HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
137    return GSS_S_BAD_MIC;
138  }
139
140  ret = _gssapi_msg_order_check(context_handle->order, seq_number);
141  if (ret) {
142      HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
143      return ret;
144  }
145
146  HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
147
148  return GSS_S_COMPLETE;
149}
150#endif
151
152static OM_uint32
153verify_mic_des3
154           (OM_uint32 * minor_status,
155            const gsskrb5_ctx context_handle,
156	    krb5_context context,
157            const gss_buffer_t message_buffer,
158            const gss_buffer_t token_buffer,
159            gss_qop_t * qop_state,
160	    krb5_keyblock *key,
161	    const char *type
162	    )
163{
164  u_char *p;
165  u_char *seq;
166  uint32_t seq_number;
167  OM_uint32 ret;
168  krb5_crypto crypto;
169  krb5_data seq_data;
170  int cmp, docompat;
171  Checksum csum;
172  char *tmp;
173  char ivec[8];
174
175  p = token_buffer->value;
176  ret = _gsskrb5_verify_header (&p,
177				   token_buffer->length,
178				   type,
179				   GSS_KRB5_MECHANISM);
180  if (ret)
181      return ret;
182
183  if (memcmp(p, "\x04\x00", 2) != 0) /* SGN_ALG = HMAC SHA1 DES3-KD */
184      return GSS_S_BAD_SIG;
185  p += 2;
186  if (memcmp (p, "\xff\xff\xff\xff", 4) != 0)
187    return GSS_S_BAD_MIC;
188  p += 4;
189
190  ret = krb5_crypto_init(context, key,
191			 ETYPE_DES3_CBC_NONE, &crypto);
192  if (ret){
193      *minor_status = ret;
194      return GSS_S_FAILURE;
195  }
196
197  /* verify sequence number */
198  docompat = 0;
199retry:
200  if (docompat)
201      memset(ivec, 0, 8);
202  else
203      memcpy(ivec, p + 8, 8);
204
205  ret = krb5_decrypt_ivec (context,
206			   crypto,
207			   KRB5_KU_USAGE_SEQ,
208			   p, 8, &seq_data, ivec);
209  if (ret) {
210      if (docompat++) {
211	  krb5_crypto_destroy (context, crypto);
212	  *minor_status = ret;
213	  return GSS_S_FAILURE;
214      } else
215	  goto retry;
216  }
217
218  if (seq_data.length != 8) {
219      krb5_data_free (&seq_data);
220      if (docompat++) {
221	  krb5_crypto_destroy (context, crypto);
222	  return GSS_S_BAD_MIC;
223      } else
224	  goto retry;
225  }
226
227  HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
228
229  seq = seq_data.data;
230  _gsskrb5_decode_om_uint32(seq, &seq_number);
231
232  if (context_handle->more_flags & LOCAL)
233      cmp = ct_memcmp(&seq[4], "\xff\xff\xff\xff", 4);
234  else
235      cmp = ct_memcmp(&seq[4], "\x00\x00\x00\x00", 4);
236
237  krb5_data_free (&seq_data);
238  if (cmp != 0) {
239      krb5_crypto_destroy (context, crypto);
240      *minor_status = 0;
241      HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
242      return GSS_S_BAD_MIC;
243  }
244
245  ret = _gssapi_msg_order_check(context_handle->order, seq_number);
246  if (ret) {
247      krb5_crypto_destroy (context, crypto);
248      *minor_status = 0;
249      HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
250      return ret;
251  }
252
253  /* verify checksum */
254
255  tmp = malloc (message_buffer->length + 8);
256  if (tmp == NULL) {
257      krb5_crypto_destroy (context, crypto);
258      HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
259      *minor_status = ENOMEM;
260      return GSS_S_FAILURE;
261  }
262
263  memcpy (tmp, p - 8, 8);
264  memcpy (tmp + 8, message_buffer->value, message_buffer->length);
265
266  csum.cksumtype = CKSUMTYPE_HMAC_SHA1_DES3;
267  csum.checksum.length = 20;
268  csum.checksum.data   = p + 8;
269
270  krb5_crypto_destroy (context, crypto);
271  ret = krb5_crypto_init(context, key,
272			 ETYPE_DES3_CBC_SHA1, &crypto);
273  if (ret) {
274      free (tmp);
275      *minor_status = ret;
276      return GSS_S_FAILURE;
277  }
278
279  ret = krb5_verify_checksum (context, crypto,
280			      KRB5_KU_USAGE_SIGN,
281			      tmp, message_buffer->length + 8,
282			      &csum);
283  free (tmp);
284  if (ret) {
285      krb5_crypto_destroy (context, crypto);
286      *minor_status = ret;
287      HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
288      return GSS_S_BAD_MIC;
289  }
290  HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
291
292  krb5_crypto_destroy (context, crypto);
293  return GSS_S_COMPLETE;
294}
295
296OM_uint32
297_gsskrb5_verify_mic_internal
298           (OM_uint32 * minor_status,
299            const gsskrb5_ctx ctx,
300	    krb5_context context,
301            const gss_buffer_t message_buffer,
302            const gss_buffer_t token_buffer,
303            gss_qop_t * qop_state,
304	    const char * type
305	    )
306{
307    krb5_keyblock *key;
308    OM_uint32 ret;
309
310    if (ctx->more_flags & IS_CFX)
311        return _gssapi_verify_mic_cfx (minor_status, ctx,
312				       context, message_buffer, token_buffer,
313				       qop_state);
314
315    HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
316    ret = _gsskrb5i_get_token_key(ctx, context, &key);
317    HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
318    if (ret) {
319	*minor_status = ret;
320	return GSS_S_FAILURE;
321    }
322    *minor_status = 0;
323
324    switch (key->keytype) {
325    case KRB5_ENCTYPE_DES_CBC_CRC :
326    case KRB5_ENCTYPE_DES_CBC_MD4 :
327    case KRB5_ENCTYPE_DES_CBC_MD5 :
328#ifdef HEIM_WEAK_CRYPTO
329	ret = verify_mic_des (minor_status, ctx, context,
330			      message_buffer, token_buffer, qop_state, key,
331			      type);
332#else
333      ret = GSS_S_FAILURE;
334#endif
335	break;
336    case KRB5_ENCTYPE_DES3_CBC_MD5 :
337    case KRB5_ENCTYPE_DES3_CBC_SHA1 :
338	ret = verify_mic_des3 (minor_status, ctx, context,
339			       message_buffer, token_buffer, qop_state, key,
340			       type);
341	break;
342    case KRB5_ENCTYPE_ARCFOUR_HMAC_MD5:
343    case KRB5_ENCTYPE_ARCFOUR_HMAC_MD5_56:
344	ret = _gssapi_verify_mic_arcfour (minor_status, ctx,
345					  context,
346					  message_buffer, token_buffer,
347					  qop_state, key, type);
348	break;
349    default :
350        abort();
351    }
352    krb5_free_keyblock (context, key);
353
354    return ret;
355}
356
357OM_uint32 GSSAPI_CALLCONV
358_gsskrb5_verify_mic
359           (OM_uint32 * minor_status,
360            gss_const_ctx_id_t context_handle,
361            const gss_buffer_t message_buffer,
362            const gss_buffer_t token_buffer,
363            gss_qop_t * qop_state
364	    )
365{
366    krb5_context context;
367    OM_uint32 ret;
368
369    GSSAPI_KRB5_INIT (&context);
370
371    if (qop_state != NULL)
372	*qop_state = GSS_C_QOP_DEFAULT;
373
374    ret = _gsskrb5_verify_mic_internal(minor_status,
375				       (gsskrb5_ctx)context_handle,
376				       context,
377				       message_buffer, token_buffer,
378				       qop_state, (void *)(intptr_t)"\x01\x01");
379
380    return ret;
381}
382