1 /*
2 * Generic ASN.1 parsing
3 *
4 * Copyright The Mbed TLS Contributors
5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
6 *
7 * This file is provided under the Apache License 2.0, or the
8 * GNU General Public License v2.0 or later.
9 *
10 * **********
11 * Apache License 2.0:
12 *
13 * Licensed under the Apache License, Version 2.0 (the "License"); you may
14 * not use this file except in compliance with the License.
15 * You may obtain a copy of the License at
16 *
17 * http://www.apache.org/licenses/LICENSE-2.0
18 *
19 * Unless required by applicable law or agreed to in writing, software
20 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
21 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
22 * See the License for the specific language governing permissions and
23 * limitations under the License.
24 *
25 * **********
26 *
27 * **********
28 * GNU General Public License v2.0 or later:
29 *
30 * This program is free software; you can redistribute it and/or modify
31 * it under the terms of the GNU General Public License as published by
32 * the Free Software Foundation; either version 2 of the License, or
33 * (at your option) any later version.
34 *
35 * This program is distributed in the hope that it will be useful,
36 * but WITHOUT ANY WARRANTY; without even the implied warranty of
37 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
38 * GNU General Public License for more details.
39 *
40 * You should have received a copy of the GNU General Public License along
41 * with this program; if not, write to the Free Software Foundation, Inc.,
42 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
43 *
44 * **********
45 */
46
47 #if !defined(MBEDTLS_CONFIG_FILE)
48 #include "mbedtls/config.h"
49 #else
50 #include MBEDTLS_CONFIG_FILE
51 #endif
52
53 #if defined(MBEDTLS_ASN1_PARSE_C)
54
55 #include "mbedtls/asn1.h"
56
57 #include <string.h>
58
59 #if defined(MBEDTLS_BIGNUM_C)
60 #include "mbedtls/bignum.h"
61 #endif
62
63 #if defined(MBEDTLS_PLATFORM_C)
64 #include "mbedtls/platform.h"
65 #else
66 #include <stdlib.h>
67 #define mbedtls_calloc calloc
68 #define mbedtls_free free
69 #endif
70
71 /* Implementation that should never be optimized out by the compiler */
mbedtls_zeroize(void * v,size_t n)72 static void mbedtls_zeroize( void *v, size_t n ) {
73 volatile unsigned char *p = (unsigned char*)v; while( n-- ) *p++ = 0;
74 }
75
76 /*
77 * ASN.1 DER decoding routines
78 */
mbedtls_asn1_get_len(unsigned char ** p,const unsigned char * end,size_t * len)79 int mbedtls_asn1_get_len( unsigned char **p,
80 const unsigned char *end,
81 size_t *len )
82 {
83 if( ( end - *p ) < 1 )
84 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
85
86 if( ( **p & 0x80 ) == 0 )
87 *len = *(*p)++;
88 else
89 {
90 switch( **p & 0x7F )
91 {
92 case 1:
93 if( ( end - *p ) < 2 )
94 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
95
96 *len = (*p)[1];
97 (*p) += 2;
98 break;
99
100 case 2:
101 if( ( end - *p ) < 3 )
102 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
103
104 *len = ( (size_t)(*p)[1] << 8 ) | (*p)[2];
105 (*p) += 3;
106 break;
107
108 case 3:
109 if( ( end - *p ) < 4 )
110 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
111
112 *len = ( (size_t)(*p)[1] << 16 ) |
113 ( (size_t)(*p)[2] << 8 ) | (*p)[3];
114 (*p) += 4;
115 break;
116
117 case 4:
118 if( ( end - *p ) < 5 )
119 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
120
121 *len = ( (size_t)(*p)[1] << 24 ) | ( (size_t)(*p)[2] << 16 ) |
122 ( (size_t)(*p)[3] << 8 ) | (*p)[4];
123 (*p) += 5;
124 break;
125
126 default:
127 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
128 }
129 }
130
131 if( *len > (size_t) ( end - *p ) )
132 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
133
134 return( 0 );
135 }
136
mbedtls_asn1_get_tag(unsigned char ** p,const unsigned char * end,size_t * len,int tag)137 int mbedtls_asn1_get_tag( unsigned char **p,
138 const unsigned char *end,
139 size_t *len, int tag )
140 {
141 if( ( end - *p ) < 1 )
142 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
143
144 if( **p != tag )
145 return( MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
146
147 (*p)++;
148
149 return( mbedtls_asn1_get_len( p, end, len ) );
150 }
151
mbedtls_asn1_get_bool(unsigned char ** p,const unsigned char * end,int * val)152 int mbedtls_asn1_get_bool( unsigned char **p,
153 const unsigned char *end,
154 int *val )
155 {
156 int ret;
157 size_t len;
158
159 if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_BOOLEAN ) ) != 0 )
160 return( ret );
161
162 if( len != 1 )
163 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
164
165 *val = ( **p != 0 ) ? 1 : 0;
166 (*p)++;
167
168 return( 0 );
169 }
170
mbedtls_asn1_get_int(unsigned char ** p,const unsigned char * end,int * val)171 int mbedtls_asn1_get_int( unsigned char **p,
172 const unsigned char *end,
173 int *val )
174 {
175 int ret;
176 size_t len;
177
178 if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_INTEGER ) ) != 0 )
179 return( ret );
180
181 if( len == 0 || len > sizeof( int ) || ( **p & 0x80 ) != 0 )
182 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
183
184 *val = 0;
185
186 while( len-- > 0 )
187 {
188 *val = ( *val << 8 ) | **p;
189 (*p)++;
190 }
191
192 return( 0 );
193 }
194
195 #if defined(MBEDTLS_BIGNUM_C)
mbedtls_asn1_get_mpi(unsigned char ** p,const unsigned char * end,mbedtls_mpi * X)196 int mbedtls_asn1_get_mpi( unsigned char **p,
197 const unsigned char *end,
198 mbedtls_mpi *X )
199 {
200 int ret;
201 size_t len;
202
203 if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_INTEGER ) ) != 0 )
204 return( ret );
205
206 ret = mbedtls_mpi_read_binary( X, *p, len );
207
208 *p += len;
209
210 return( ret );
211 }
212 #endif /* MBEDTLS_BIGNUM_C */
213
mbedtls_asn1_get_bitstring(unsigned char ** p,const unsigned char * end,mbedtls_asn1_bitstring * bs)214 int mbedtls_asn1_get_bitstring( unsigned char **p, const unsigned char *end,
215 mbedtls_asn1_bitstring *bs)
216 {
217 int ret;
218
219 /* Certificate type is a single byte bitstring */
220 if( ( ret = mbedtls_asn1_get_tag( p, end, &bs->len, MBEDTLS_ASN1_BIT_STRING ) ) != 0 )
221 return( ret );
222
223 /* Check length, subtract one for actual bit string length */
224 if( bs->len < 1 )
225 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
226 bs->len -= 1;
227
228 /* Get number of unused bits, ensure unused bits <= 7 */
229 bs->unused_bits = **p;
230 if( bs->unused_bits > 7 )
231 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
232 (*p)++;
233
234 /* Get actual bitstring */
235 bs->p = *p;
236 *p += bs->len;
237
238 if( *p != end )
239 return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
240
241 return( 0 );
242 }
243
244 /*
245 * Get a bit string without unused bits
246 */
mbedtls_asn1_get_bitstring_null(unsigned char ** p,const unsigned char * end,size_t * len)247 int mbedtls_asn1_get_bitstring_null( unsigned char **p, const unsigned char *end,
248 size_t *len )
249 {
250 int ret;
251
252 if( ( ret = mbedtls_asn1_get_tag( p, end, len, MBEDTLS_ASN1_BIT_STRING ) ) != 0 )
253 return( ret );
254
255 if( (*len)-- < 2 || *(*p)++ != 0 )
256 return( MBEDTLS_ERR_ASN1_INVALID_DATA );
257
258 return( 0 );
259 }
260
261
262
263 /*
264 * Parses and splits an ASN.1 "SEQUENCE OF <tag>"
265 */
mbedtls_asn1_get_sequence_of(unsigned char ** p,const unsigned char * end,mbedtls_asn1_sequence * cur,int tag)266 int mbedtls_asn1_get_sequence_of( unsigned char **p,
267 const unsigned char *end,
268 mbedtls_asn1_sequence *cur,
269 int tag)
270 {
271 int ret;
272 size_t len;
273 mbedtls_asn1_buf *buf;
274
275 /* Get main sequence tag */
276 if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
277 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
278 return( ret );
279
280 if( *p + len != end )
281 return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
282
283 while( *p < end )
284 {
285 buf = &(cur->buf);
286 buf->tag = **p;
287
288 if( ( ret = mbedtls_asn1_get_tag( p, end, &buf->len, tag ) ) != 0 )
289 return( ret );
290
291 buf->p = *p;
292 *p += buf->len;
293
294 /* Allocate and assign next pointer */
295 if( *p < end )
296 {
297 cur->next = (mbedtls_asn1_sequence*)mbedtls_calloc( 1,
298 sizeof( mbedtls_asn1_sequence ) );
299
300 if( cur->next == NULL )
301 return( MBEDTLS_ERR_ASN1_ALLOC_FAILED );
302
303 cur = cur->next;
304 }
305 }
306
307 /* Set final sequence entry's next pointer to NULL */
308 cur->next = NULL;
309
310 if( *p != end )
311 return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
312
313 return( 0 );
314 }
315
mbedtls_asn1_get_alg(unsigned char ** p,const unsigned char * end,mbedtls_asn1_buf * alg,mbedtls_asn1_buf * params)316 int mbedtls_asn1_get_alg( unsigned char **p,
317 const unsigned char *end,
318 mbedtls_asn1_buf *alg, mbedtls_asn1_buf *params )
319 {
320 int ret;
321 size_t len;
322
323 if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
324 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
325 return( ret );
326
327 if( ( end - *p ) < 1 )
328 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
329
330 alg->tag = **p;
331 end = *p + len;
332
333 if( ( ret = mbedtls_asn1_get_tag( p, end, &alg->len, MBEDTLS_ASN1_OID ) ) != 0 )
334 return( ret );
335
336 alg->p = *p;
337 *p += alg->len;
338
339 if( *p == end )
340 {
341 mbedtls_zeroize( params, sizeof(mbedtls_asn1_buf) );
342 return( 0 );
343 }
344
345 params->tag = **p;
346 (*p)++;
347
348 if( ( ret = mbedtls_asn1_get_len( p, end, ¶ms->len ) ) != 0 )
349 return( ret );
350
351 params->p = *p;
352 *p += params->len;
353
354 if( *p != end )
355 return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
356
357 return( 0 );
358 }
359
mbedtls_asn1_get_alg_null(unsigned char ** p,const unsigned char * end,mbedtls_asn1_buf * alg)360 int mbedtls_asn1_get_alg_null( unsigned char **p,
361 const unsigned char *end,
362 mbedtls_asn1_buf *alg )
363 {
364 int ret;
365 mbedtls_asn1_buf params;
366
367 memset( ¶ms, 0, sizeof(mbedtls_asn1_buf) );
368
369 if( ( ret = mbedtls_asn1_get_alg( p, end, alg, ¶ms ) ) != 0 )
370 return( ret );
371
372 if( ( params.tag != MBEDTLS_ASN1_NULL && params.tag != 0 ) || params.len != 0 )
373 return( MBEDTLS_ERR_ASN1_INVALID_DATA );
374
375 return( 0 );
376 }
377
mbedtls_asn1_free_named_data(mbedtls_asn1_named_data * cur)378 void mbedtls_asn1_free_named_data( mbedtls_asn1_named_data *cur )
379 {
380 if( cur == NULL )
381 return;
382
383 mbedtls_free( cur->oid.p );
384 mbedtls_free( cur->val.p );
385
386 mbedtls_zeroize( cur, sizeof( mbedtls_asn1_named_data ) );
387 }
388
mbedtls_asn1_free_named_data_list(mbedtls_asn1_named_data ** head)389 void mbedtls_asn1_free_named_data_list( mbedtls_asn1_named_data **head )
390 {
391 mbedtls_asn1_named_data *cur;
392
393 while( ( cur = *head ) != NULL )
394 {
395 *head = cur->next;
396 mbedtls_asn1_free_named_data( cur );
397 mbedtls_free( cur );
398 }
399 }
400
mbedtls_asn1_find_named_data(mbedtls_asn1_named_data * list,const char * oid,size_t len)401 mbedtls_asn1_named_data *mbedtls_asn1_find_named_data( mbedtls_asn1_named_data *list,
402 const char *oid, size_t len )
403 {
404 while( list != NULL )
405 {
406 if( list->oid.len == len &&
407 memcmp( list->oid.p, oid, len ) == 0 )
408 {
409 break;
410 }
411
412 list = list->next;
413 }
414
415 return( list );
416 }
417
418 #endif /* MBEDTLS_ASN1_PARSE_C */
419