1 /*
2 * Generic ASN.1 parsing
3 *
4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
5 * SPDX-License-Identifier: Apache-2.0
6 *
7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
8 * not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 *
19 * This file is part of mbed TLS (https://tls.mbed.org)
20 */
21
22 #if !defined(MBEDTLS_CONFIG_FILE)
23 #include "mbedtls/config.h"
24 #else
25 #include MBEDTLS_CONFIG_FILE
26 #endif
27
28 #if defined(MBEDTLS_ASN1_PARSE_C)
29
30 #include "mbedtls/asn1.h"
31 #include "mbedtls/platform_util.h"
32
33 #include <string.h>
34
35 #if defined(MBEDTLS_BIGNUM_C)
36 #include "mbedtls/bignum.h"
37 #endif
38
39 #if defined(MBEDTLS_PLATFORM_C)
40 #include "mbedtls/platform.h"
41 #else
42 #include <stdlib.h>
43 #define mbedtls_calloc calloc
44 #define mbedtls_free free
45 #endif
46
47 /*
48 * ASN.1 DER decoding routines
49 */
mbedtls_asn1_get_len(unsigned char ** p,const unsigned char * end,size_t * len)50 int mbedtls_asn1_get_len( unsigned char **p,
51 const unsigned char *end,
52 size_t *len )
53 {
54 if( ( end - *p ) < 1 )
55 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
56
57 if( ( **p & 0x80 ) == 0 )
58 *len = *(*p)++;
59 else
60 {
61 switch( **p & 0x7F )
62 {
63 case 1:
64 if( ( end - *p ) < 2 )
65 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
66
67 *len = (*p)[1];
68 (*p) += 2;
69 break;
70
71 case 2:
72 if( ( end - *p ) < 3 )
73 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
74
75 *len = ( (size_t)(*p)[1] << 8 ) | (*p)[2];
76 (*p) += 3;
77 break;
78
79 case 3:
80 if( ( end - *p ) < 4 )
81 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
82
83 *len = ( (size_t)(*p)[1] << 16 ) |
84 ( (size_t)(*p)[2] << 8 ) | (*p)[3];
85 (*p) += 4;
86 break;
87
88 case 4:
89 if( ( end - *p ) < 5 )
90 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
91
92 *len = ( (size_t)(*p)[1] << 24 ) | ( (size_t)(*p)[2] << 16 ) |
93 ( (size_t)(*p)[3] << 8 ) | (*p)[4];
94 (*p) += 5;
95 break;
96
97 default:
98 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
99 }
100 }
101
102 if( *len > (size_t) ( end - *p ) )
103 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
104
105 return( 0 );
106 }
107
mbedtls_asn1_get_tag(unsigned char ** p,const unsigned char * end,size_t * len,int tag)108 int mbedtls_asn1_get_tag( unsigned char **p,
109 const unsigned char *end,
110 size_t *len, int tag )
111 {
112 if( ( end - *p ) < 1 )
113 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
114
115 if( **p != tag )
116 return( MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
117
118 (*p)++;
119
120 return( mbedtls_asn1_get_len( p, end, len ) );
121 }
122
mbedtls_asn1_get_bool(unsigned char ** p,const unsigned char * end,int * val)123 int mbedtls_asn1_get_bool( unsigned char **p,
124 const unsigned char *end,
125 int *val )
126 {
127 int ret;
128 size_t len;
129
130 if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_BOOLEAN ) ) != 0 )
131 return( ret );
132
133 if( len != 1 )
134 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
135
136 *val = ( **p != 0 ) ? 1 : 0;
137 (*p)++;
138
139 return( 0 );
140 }
141
mbedtls_asn1_get_int(unsigned char ** p,const unsigned char * end,int * val)142 int mbedtls_asn1_get_int( unsigned char **p,
143 const unsigned char *end,
144 int *val )
145 {
146 int ret;
147 size_t len;
148
149 if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_INTEGER ) ) != 0 )
150 return( ret );
151
152 if( len == 0 || len > sizeof( int ) || ( **p & 0x80 ) != 0 )
153 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
154
155 *val = 0;
156
157 while( len-- > 0 )
158 {
159 *val = ( *val << 8 ) | **p;
160 (*p)++;
161 }
162
163 return( 0 );
164 }
165
166 #if defined(MBEDTLS_BIGNUM_C)
mbedtls_asn1_get_mpi(unsigned char ** p,const unsigned char * end,mbedtls_mpi * X)167 int mbedtls_asn1_get_mpi( unsigned char **p,
168 const unsigned char *end,
169 mbedtls_mpi *X )
170 {
171 int ret;
172 size_t len;
173
174 if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_INTEGER ) ) != 0 )
175 return( ret );
176
177 ret = mbedtls_mpi_read_binary( X, *p, len );
178
179 *p += len;
180
181 return( ret );
182 }
183 #endif /* MBEDTLS_BIGNUM_C */
184
mbedtls_asn1_get_bitstring(unsigned char ** p,const unsigned char * end,mbedtls_asn1_bitstring * bs)185 int mbedtls_asn1_get_bitstring( unsigned char **p, const unsigned char *end,
186 mbedtls_asn1_bitstring *bs)
187 {
188 int ret;
189
190 /* Certificate type is a single byte bitstring */
191 if( ( ret = mbedtls_asn1_get_tag( p, end, &bs->len, MBEDTLS_ASN1_BIT_STRING ) ) != 0 )
192 return( ret );
193
194 /* Check length, subtract one for actual bit string length */
195 if( bs->len < 1 )
196 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
197 bs->len -= 1;
198
199 /* Get number of unused bits, ensure unused bits <= 7 */
200 bs->unused_bits = **p;
201 if( bs->unused_bits > 7 )
202 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
203 (*p)++;
204
205 /* Get actual bitstring */
206 bs->p = *p;
207 *p += bs->len;
208
209 if( *p != end )
210 return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
211
212 return( 0 );
213 }
214
215 /*
216 * Get a bit string without unused bits
217 */
mbedtls_asn1_get_bitstring_null(unsigned char ** p,const unsigned char * end,size_t * len)218 int mbedtls_asn1_get_bitstring_null( unsigned char **p, const unsigned char *end,
219 size_t *len )
220 {
221 int ret;
222
223 if( ( ret = mbedtls_asn1_get_tag( p, end, len, MBEDTLS_ASN1_BIT_STRING ) ) != 0 )
224 return( ret );
225
226 if( (*len)-- < 2 || *(*p)++ != 0 )
227 return( MBEDTLS_ERR_ASN1_INVALID_DATA );
228
229 return( 0 );
230 }
231
232
233
234 /*
235 * Parses and splits an ASN.1 "SEQUENCE OF <tag>"
236 */
mbedtls_asn1_get_sequence_of(unsigned char ** p,const unsigned char * end,mbedtls_asn1_sequence * cur,int tag)237 int mbedtls_asn1_get_sequence_of( unsigned char **p,
238 const unsigned char *end,
239 mbedtls_asn1_sequence *cur,
240 int tag)
241 {
242 int ret;
243 size_t len;
244 mbedtls_asn1_buf *buf;
245
246 /* Get main sequence tag */
247 if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
248 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
249 return( ret );
250
251 if( *p + len != end )
252 return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
253
254 while( *p < end )
255 {
256 buf = &(cur->buf);
257 buf->tag = **p;
258
259 if( ( ret = mbedtls_asn1_get_tag( p, end, &buf->len, tag ) ) != 0 )
260 return( ret );
261
262 buf->p = *p;
263 *p += buf->len;
264
265 /* Allocate and assign next pointer */
266 if( *p < end )
267 {
268 cur->next = (mbedtls_asn1_sequence*)mbedtls_calloc( 1,
269 sizeof( mbedtls_asn1_sequence ) );
270
271 if( cur->next == NULL )
272 return( MBEDTLS_ERR_ASN1_ALLOC_FAILED );
273
274 cur = cur->next;
275 }
276 }
277
278 /* Set final sequence entry's next pointer to NULL */
279 cur->next = NULL;
280
281 if( *p != end )
282 return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
283
284 return( 0 );
285 }
286
mbedtls_asn1_get_alg(unsigned char ** p,const unsigned char * end,mbedtls_asn1_buf * alg,mbedtls_asn1_buf * params)287 int mbedtls_asn1_get_alg( unsigned char **p,
288 const unsigned char *end,
289 mbedtls_asn1_buf *alg, mbedtls_asn1_buf *params )
290 {
291 int ret;
292 size_t len;
293
294 if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
295 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
296 return( ret );
297
298 if( ( end - *p ) < 1 )
299 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
300
301 alg->tag = **p;
302 end = *p + len;
303
304 if( ( ret = mbedtls_asn1_get_tag( p, end, &alg->len, MBEDTLS_ASN1_OID ) ) != 0 )
305 return( ret );
306
307 alg->p = *p;
308 *p += alg->len;
309
310 if( *p == end )
311 {
312 mbedtls_platform_zeroize( params, sizeof(mbedtls_asn1_buf) );
313 return( 0 );
314 }
315
316 params->tag = **p;
317 (*p)++;
318
319 if( ( ret = mbedtls_asn1_get_len( p, end, ¶ms->len ) ) != 0 )
320 return( ret );
321
322 params->p = *p;
323 *p += params->len;
324
325 if( *p != end )
326 return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
327
328 return( 0 );
329 }
330
mbedtls_asn1_get_alg_null(unsigned char ** p,const unsigned char * end,mbedtls_asn1_buf * alg)331 int mbedtls_asn1_get_alg_null( unsigned char **p,
332 const unsigned char *end,
333 mbedtls_asn1_buf *alg )
334 {
335 int ret;
336 mbedtls_asn1_buf params;
337
338 memset( ¶ms, 0, sizeof(mbedtls_asn1_buf) );
339
340 if( ( ret = mbedtls_asn1_get_alg( p, end, alg, ¶ms ) ) != 0 )
341 return( ret );
342
343 if( ( params.tag != MBEDTLS_ASN1_NULL && params.tag != 0 ) || params.len != 0 )
344 return( MBEDTLS_ERR_ASN1_INVALID_DATA );
345
346 return( 0 );
347 }
348
mbedtls_asn1_free_named_data(mbedtls_asn1_named_data * cur)349 void mbedtls_asn1_free_named_data( mbedtls_asn1_named_data *cur )
350 {
351 if( cur == NULL )
352 return;
353
354 mbedtls_free( cur->oid.p );
355 mbedtls_free( cur->val.p );
356
357 mbedtls_platform_zeroize( cur, sizeof( mbedtls_asn1_named_data ) );
358 }
359
mbedtls_asn1_free_named_data_list(mbedtls_asn1_named_data ** head)360 void mbedtls_asn1_free_named_data_list( mbedtls_asn1_named_data **head )
361 {
362 mbedtls_asn1_named_data *cur;
363
364 while( ( cur = *head ) != NULL )
365 {
366 *head = cur->next;
367 mbedtls_asn1_free_named_data( cur );
368 mbedtls_free( cur );
369 }
370 }
371
mbedtls_asn1_find_named_data(mbedtls_asn1_named_data * list,const char * oid,size_t len)372 mbedtls_asn1_named_data *mbedtls_asn1_find_named_data( mbedtls_asn1_named_data *list,
373 const char *oid, size_t len )
374 {
375 while( list != NULL )
376 {
377 if( list->oid.len == len &&
378 memcmp( list->oid.p, oid, len ) == 0 )
379 {
380 break;
381 }
382
383 list = list->next;
384 }
385
386 return( list );
387 }
388
389 #endif /* MBEDTLS_ASN1_PARSE_C */
390