source: heimdal/trunk/lib/gssapi/krb5/unwrap.c

Last change on this file was 1, checked in by Paul Smedley, 10 years ago

Initial commit of Heimdal 1.5.3
File size: 11.8 KB
Line 
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#ifdef HEIM_WEAK_CRYPTO
37
38static OM_uint32
39unwrap_des
40 (OM_uint32 * minor_status,
41 const gsskrb5_ctx context_handle,
42 const gss_buffer_t input_message_buffer,
43 gss_buffer_t output_message_buffer,
44 int * conf_state,
45 gss_qop_t * qop_state,
46 krb5_keyblock *key
47 )
48{
49 u_char *p, *seq;
50 size_t len;
51 EVP_MD_CTX *md5;
52 u_char hash[16];
53 EVP_CIPHER_CTX des_ctx;
54 DES_key_schedule schedule;
55 DES_cblock deskey;
56 DES_cblock zero;
57 size_t i;
58 uint32_t seq_number;
59 size_t padlength;
60 OM_uint32 ret;
61 int cstate;
62 int cmp;
63 int token_len;
64
65 if (IS_DCE_STYLE(context_handle)) {
66 token_len = 22 + 8 + 15; /* 45 */
67 } else {
68 token_len = input_message_buffer->length;
69 }
70
71 p = input_message_buffer->value;
72 ret = _gsskrb5_verify_header (&p,
73 token_len,
74 "\x02\x01",
75 GSS_KRB5_MECHANISM);
76 if (ret)
77 return ret;
78
79 if (memcmp (p, "\x00\x00", 2) != 0)
80 return GSS_S_BAD_SIG;
81 p += 2;
82 if (memcmp (p, "\x00\x00", 2) == 0) {
83 cstate = 1;
84 } else if (memcmp (p, "\xFF\xFF", 2) == 0) {
85 cstate = 0;
86 } else
87 return GSS_S_BAD_MIC;
88 p += 2;
89 if(conf_state != NULL)
90 *conf_state = cstate;
91 if (memcmp (p, "\xff\xff", 2) != 0)
92 return GSS_S_DEFECTIVE_TOKEN;
93 p += 2;
94 p += 16;
95
96 len = p - (u_char *)input_message_buffer->value;
97
98 if(cstate) {
99 /* decrypt data */
100 memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
101 memset (&zero, 0, sizeof(zero));
102
103 for (i = 0; i < sizeof(deskey); ++i)
104 deskey[i] ^= 0xf0;
105
106
107 EVP_CIPHER_CTX_init(&des_ctx);
108 EVP_CipherInit_ex(&des_ctx, EVP_des_cbc(), NULL, deskey, zero, 0);
109 EVP_Cipher(&des_ctx, p, p, input_message_buffer->length - len);
110 EVP_CIPHER_CTX_cleanup(&des_ctx);
111
112 memset (&schedule, 0, sizeof(schedule));
113 }
114
115 if (IS_DCE_STYLE(context_handle)) {
116 padlength = 0;
117 } else {
118 /* check pad */
119 ret = _gssapi_verify_pad(input_message_buffer,
120 input_message_buffer->length - len,
121 &padlength);
122 if (ret)
123 return ret;
124 }
125
126 md5 = EVP_MD_CTX_create();
127 EVP_DigestInit_ex(md5, EVP_md5(), NULL);
128 EVP_DigestUpdate(md5, p - 24, 8);
129 EVP_DigestUpdate(md5, p, input_message_buffer->length - len);
130 EVP_DigestFinal_ex(md5, hash, NULL);
131 EVP_MD_CTX_destroy(md5);
132
133 memset (&zero, 0, sizeof(zero));
134 memcpy (&deskey, key->keyvalue.data, sizeof(deskey));
135 DES_set_key_unchecked (&deskey, &schedule);
136 DES_cbc_cksum ((void *)hash, (void *)hash, sizeof(hash),
137 &schedule, &zero);
138 if (ct_memcmp (p - 8, hash, 8) != 0)
139 return GSS_S_BAD_MIC;
140
141 /* verify sequence number */
142
143 HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
144
145 p -= 16;
146
147 EVP_CIPHER_CTX_init(&des_ctx);
148 EVP_CipherInit_ex(&des_ctx, EVP_des_cbc(), NULL, key->keyvalue.data, hash, 0);
149 EVP_Cipher(&des_ctx, p, p, 8);
150 EVP_CIPHER_CTX_cleanup(&des_ctx);
151
152 memset (deskey, 0, sizeof(deskey));
153 memset (&schedule, 0, sizeof(schedule));
154
155 seq = p;
156 _gsskrb5_decode_om_uint32(seq, &seq_number);
157
158 if (context_handle->more_flags & LOCAL)
159 cmp = ct_memcmp(&seq[4], "\xff\xff\xff\xff", 4);
160 else
161 cmp = ct_memcmp(&seq[4], "\x00\x00\x00\x00", 4);
162
163 if (cmp != 0) {
164 HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
165 return GSS_S_BAD_MIC;
166 }
167
168 ret = _gssapi_msg_order_check(context_handle->order, seq_number);
169 if (ret) {
170 HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
171 return ret;
172 }
173
174 HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
175
176 /* copy out data */
177
178 output_message_buffer->length = input_message_buffer->length
179 - len - padlength - 8;
180 output_message_buffer->value = malloc(output_message_buffer->length);
181 if(output_message_buffer->length != 0 && output_message_buffer->value == NULL)
182 return GSS_S_FAILURE;
183 memcpy (output_message_buffer->value,
184 p + 24,
185 output_message_buffer->length);
186 return GSS_S_COMPLETE;
187}
188#endif
189
190static OM_uint32
191unwrap_des3
192 (OM_uint32 * minor_status,
193 const gsskrb5_ctx context_handle,
194 krb5_context context,
195 const gss_buffer_t input_message_buffer,
196 gss_buffer_t output_message_buffer,
197 int * conf_state,
198 gss_qop_t * qop_state,
199 krb5_keyblock *key
200 )
201{
202 u_char *p;
203 size_t len;
204 u_char *seq;
205 krb5_data seq_data;
206 u_char cksum[20];
207 uint32_t seq_number;
208 size_t padlength;
209 OM_uint32 ret;
210 int cstate;
211 krb5_crypto crypto;
212 Checksum csum;
213 int cmp;
214 int token_len;
215
216 if (IS_DCE_STYLE(context_handle)) {
217 token_len = 34 + 8 + 15; /* 57 */
218 } else {
219 token_len = input_message_buffer->length;
220 }
221
222 p = input_message_buffer->value;
223 ret = _gsskrb5_verify_header (&p,
224 token_len,
225 "\x02\x01",
226 GSS_KRB5_MECHANISM);
227 if (ret)
228 return ret;
229
230 if (memcmp (p, "\x04\x00", 2) != 0) /* HMAC SHA1 DES3_KD */
231 return GSS_S_BAD_SIG;
232 p += 2;
233 if (ct_memcmp (p, "\x02\x00", 2) == 0) {
234 cstate = 1;
235 } else if (ct_memcmp (p, "\xff\xff", 2) == 0) {
236 cstate = 0;
237 } else
238 return GSS_S_BAD_MIC;
239 p += 2;
240 if(conf_state != NULL)
241 *conf_state = cstate;
242 if (ct_memcmp (p, "\xff\xff", 2) != 0)
243 return GSS_S_DEFECTIVE_TOKEN;
244 p += 2;
245 p += 28;
246
247 len = p - (u_char *)input_message_buffer->value;
248
249 if(cstate) {
250 /* decrypt data */
251 krb5_data tmp;
252
253 ret = krb5_crypto_init(context, key,
254 ETYPE_DES3_CBC_NONE, &crypto);
255 if (ret) {
256 *minor_status = ret;
257 return GSS_S_FAILURE;
258 }
259 ret = krb5_decrypt(context, crypto, KRB5_KU_USAGE_SEAL,
260 p, input_message_buffer->length - len, &tmp);
261 krb5_crypto_destroy(context, crypto);
262 if (ret) {
263 *minor_status = ret;
264 return GSS_S_FAILURE;
265 }
266 assert (tmp.length == input_message_buffer->length - len);
267
268 memcpy (p, tmp.data, tmp.length);
269 krb5_data_free(&tmp);
270 }
271
272 if (IS_DCE_STYLE(context_handle)) {
273 padlength = 0;
274 } else {
275 /* check pad */
276 ret = _gssapi_verify_pad(input_message_buffer,
277 input_message_buffer->length - len,
278 &padlength);
279 if (ret)
280 return ret;
281 }
282
283 /* verify sequence number */
284
285 HEIMDAL_MUTEX_lock(&context_handle->ctx_id_mutex);
286
287 p -= 28;
288
289 ret = krb5_crypto_init(context, key,
290 ETYPE_DES3_CBC_NONE, &crypto);
291 if (ret) {
292 *minor_status = ret;
293 HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
294 return GSS_S_FAILURE;
295 }
296 {
297 DES_cblock ivec;
298
299 memcpy(&ivec, p + 8, 8);
300 ret = krb5_decrypt_ivec (context,
301 crypto,
302 KRB5_KU_USAGE_SEQ,
303 p, 8, &seq_data,
304 &ivec);
305 }
306 krb5_crypto_destroy (context, crypto);
307 if (ret) {
308 *minor_status = ret;
309 HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
310 return GSS_S_FAILURE;
311 }
312 if (seq_data.length != 8) {
313 krb5_data_free (&seq_data);
314 *minor_status = 0;
315 HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
316 return GSS_S_BAD_MIC;
317 }
318
319 seq = seq_data.data;
320 _gsskrb5_decode_om_uint32(seq, &seq_number);
321
322 if (context_handle->more_flags & LOCAL)
323 cmp = ct_memcmp(&seq[4], "\xff\xff\xff\xff", 4);
324 else
325 cmp = ct_memcmp(&seq[4], "\x00\x00\x00\x00", 4);
326
327 krb5_data_free (&seq_data);
328 if (cmp != 0) {
329 *minor_status = 0;
330 HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
331 return GSS_S_BAD_MIC;
332 }
333
334 ret = _gssapi_msg_order_check(context_handle->order, seq_number);
335 if (ret) {
336 *minor_status = 0;
337 HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
338 return ret;
339 }
340
341 HEIMDAL_MUTEX_unlock(&context_handle->ctx_id_mutex);
342
343 /* verify checksum */
344
345 memcpy (cksum, p + 8, 20);
346
347 memcpy (p + 20, p - 8, 8);
348
349 csum.cksumtype = CKSUMTYPE_HMAC_SHA1_DES3;
350 csum.checksum.length = 20;
351 csum.checksum.data = cksum;
352
353 ret = krb5_crypto_init(context, key, 0, &crypto);
354 if (ret) {
355 *minor_status = ret;
356 return GSS_S_FAILURE;
357 }
358
359 ret = krb5_verify_checksum (context, crypto,
360 KRB5_KU_USAGE_SIGN,
361 p + 20,
362 input_message_buffer->length - len + 8,
363 &csum);
364 krb5_crypto_destroy (context, crypto);
365 if (ret) {
366 *minor_status = ret;
367 return GSS_S_FAILURE;
368 }
369
370 /* copy out data */
371
372 output_message_buffer->length = input_message_buffer->length
373 - len - padlength - 8;
374 output_message_buffer->value = malloc(output_message_buffer->length);
375 if(output_message_buffer->length != 0 && output_message_buffer->value == NULL)
376 return GSS_S_FAILURE;
377 memcpy (output_message_buffer->value,
378 p + 36,
379 output_message_buffer->length);
380 return GSS_S_COMPLETE;
381}
382
383OM_uint32 GSSAPI_CALLCONV _gsskrb5_unwrap
384 (OM_uint32 * minor_status,
385 const gss_ctx_id_t context_handle,
386 const gss_buffer_t input_message_buffer,
387 gss_buffer_t output_message_buffer,
388 int * conf_state,
389 gss_qop_t * qop_state
390 )
391{
392 krb5_keyblock *key;
393 krb5_context context;
394 OM_uint32 ret;
395 krb5_keytype keytype;
396 gsskrb5_ctx ctx = (gsskrb5_ctx) context_handle;
397
398 output_message_buffer->value = NULL;
399 output_message_buffer->length = 0;
400 if (qop_state != NULL)
401 *qop_state = GSS_C_QOP_DEFAULT;
402
403 GSSAPI_KRB5_INIT (&context);
404
405 if (ctx->more_flags & IS_CFX)
406 return _gssapi_unwrap_cfx (minor_status, ctx, context,
407 input_message_buffer, output_message_buffer,
408 conf_state, qop_state);
409
410 HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
411 ret = _gsskrb5i_get_token_key(ctx, context, &key);
412 HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
413 if (ret) {
414 *minor_status = ret;
415 return GSS_S_FAILURE;
416 }
417 krb5_enctype_to_keytype (context, key->keytype, &keytype);
418
419 *minor_status = 0;
420
421 switch (keytype) {
422 case KEYTYPE_DES :
423#ifdef HEIM_WEAK_CRYPTO
424 ret = unwrap_des (minor_status, ctx,
425 input_message_buffer, output_message_buffer,
426 conf_state, qop_state, key);
427#else
428 ret = GSS_S_FAILURE;
429#endif
430 break;
431 case KEYTYPE_DES3 :
432 ret = unwrap_des3 (minor_status, ctx, context,
433 input_message_buffer, output_message_buffer,
434 conf_state, qop_state, key);
435 break;
436 case KEYTYPE_ARCFOUR:
437 case KEYTYPE_ARCFOUR_56:
438 ret = _gssapi_unwrap_arcfour (minor_status, ctx, context,
439 input_message_buffer, output_message_buffer,
440 conf_state, qop_state, key);
441 break;
442 default :
443 abort();
444 break;
445 }
446 krb5_free_keyblock (context, key);
447 return ret;
448}
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