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
32 #include <string.h>
33
34 #if defined(MBEDTLS_BIGNUM_C)
35 #include "mbedtls/bignum.h"
36 #endif
37
38 #if defined(MBEDTLS_PLATFORM_C)
39 #include "mbedtls/platform.h"
40 #else
41 #include <stdlib.h>
42 #define mbedtls_calloc calloc
43 #define mbedtls_free free
44 #endif
45
46 /* Implementation that should never be optimized out by the compiler */
mbedtls_zeroize(void * v,size_t n)47 static void mbedtls_zeroize( void *v, size_t n ) {
48 volatile unsigned char *p = (unsigned char*)v; while( n-- ) *p++ = 0;
49 }
50
51 /*
52 * ASN.1 DER decoding routines
53 */
mbedtls_asn1_get_len(unsigned char ** p,const unsigned char * end,size_t * len)54 int mbedtls_asn1_get_len( unsigned char **p,
55 const unsigned char *end,
56 size_t *len )
57 {
58 if( ( end - *p ) < 1 )
59 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
60
61 if( ( **p & 0x80 ) == 0 )
62 *len = *(*p)++;
63 else
64 {
65 switch( **p & 0x7F )
66 {
67 case 1:
68 if( ( end - *p ) < 2 )
69 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
70
71 *len = (*p)[1];
72 (*p) += 2;
73 break;
74
75 case 2:
76 if( ( end - *p ) < 3 )
77 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
78
79 *len = ( (size_t)(*p)[1] << 8 ) | (*p)[2];
80 (*p) += 3;
81 break;
82
83 case 3:
84 if( ( end - *p ) < 4 )
85 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
86
87 *len = ( (size_t)(*p)[1] << 16 ) |
88 ( (size_t)(*p)[2] << 8 ) | (*p)[3];
89 (*p) += 4;
90 break;
91
92 case 4:
93 if( ( end - *p ) < 5 )
94 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
95
96 *len = ( (size_t)(*p)[1] << 24 ) | ( (size_t)(*p)[2] << 16 ) |
97 ( (size_t)(*p)[3] << 8 ) | (*p)[4];
98 (*p) += 5;
99 break;
100
101 default:
102 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
103 }
104 }
105
106 if( *len > (size_t) ( end - *p ) )
107 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
108
109 return( 0 );
110 }
111
mbedtls_asn1_get_tag(unsigned char ** p,const unsigned char * end,size_t * len,int tag)112 int mbedtls_asn1_get_tag( unsigned char **p,
113 const unsigned char *end,
114 size_t *len, int tag )
115 {
116 if( ( end - *p ) < 1 )
117 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
118
119 if( **p != tag )
120 return( MBEDTLS_ERR_ASN1_UNEXPECTED_TAG );
121
122 (*p)++;
123
124 return( mbedtls_asn1_get_len( p, end, len ) );
125 }
126
mbedtls_asn1_get_bool(unsigned char ** p,const unsigned char * end,int * val)127 int mbedtls_asn1_get_bool( unsigned char **p,
128 const unsigned char *end,
129 int *val )
130 {
131 int ret;
132 size_t len;
133
134 if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_BOOLEAN ) ) != 0 )
135 return( ret );
136
137 if( len != 1 )
138 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
139
140 *val = ( **p != 0 ) ? 1 : 0;
141 (*p)++;
142
143 return( 0 );
144 }
145
mbedtls_asn1_get_int(unsigned char ** p,const unsigned char * end,int * val)146 int mbedtls_asn1_get_int( unsigned char **p,
147 const unsigned char *end,
148 int *val )
149 {
150 int ret;
151 size_t len;
152
153 if( ( ret = mbedtls_asn1_get_tag( p, end, &len, MBEDTLS_ASN1_INTEGER ) ) != 0 )
154 return( ret );
155
156 if( len == 0 || len > sizeof( int ) || ( **p & 0x80 ) != 0 )
157 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
158
159 *val = 0;
160
161 while( len-- > 0 )
162 {
163 *val = ( *val << 8 ) | **p;
164 (*p)++;
165 }
166
167 return( 0 );
168 }
169
170 #if defined(MBEDTLS_BIGNUM_C)
mbedtls_asn1_get_mpi(unsigned char ** p,const unsigned char * end,mbedtls_mpi * X)171 int mbedtls_asn1_get_mpi( unsigned char **p,
172 const unsigned char *end,
173 mbedtls_mpi *X )
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 ret = mbedtls_mpi_read_binary( X, *p, len );
182
183 *p += len;
184
185 return( ret );
186 }
187 #endif /* MBEDTLS_BIGNUM_C */
188
mbedtls_asn1_get_bitstring(unsigned char ** p,const unsigned char * end,mbedtls_asn1_bitstring * bs)189 int mbedtls_asn1_get_bitstring( unsigned char **p, const unsigned char *end,
190 mbedtls_asn1_bitstring *bs)
191 {
192 int ret;
193
194 /* Certificate type is a single byte bitstring */
195 if( ( ret = mbedtls_asn1_get_tag( p, end, &bs->len, MBEDTLS_ASN1_BIT_STRING ) ) != 0 )
196 return( ret );
197
198 /* Check length, subtract one for actual bit string length */
199 if( bs->len < 1 )
200 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
201 bs->len -= 1;
202
203 /* Get number of unused bits, ensure unused bits <= 7 */
204 bs->unused_bits = **p;
205 if( bs->unused_bits > 7 )
206 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
207 (*p)++;
208
209 /* Get actual bitstring */
210 bs->p = *p;
211 *p += bs->len;
212
213 if( *p != end )
214 return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
215
216 return( 0 );
217 }
218
219 /*
220 * Get a bit string without unused bits
221 */
mbedtls_asn1_get_bitstring_null(unsigned char ** p,const unsigned char * end,size_t * len)222 int mbedtls_asn1_get_bitstring_null( unsigned char **p, const unsigned char *end,
223 size_t *len )
224 {
225 int ret;
226
227 if( ( ret = mbedtls_asn1_get_tag( p, end, len, MBEDTLS_ASN1_BIT_STRING ) ) != 0 )
228 return( ret );
229
230 if( (*len)-- < 2 || *(*p)++ != 0 )
231 return( MBEDTLS_ERR_ASN1_INVALID_DATA );
232
233 return( 0 );
234 }
235
236
237
238 /*
239 * Parses and splits an ASN.1 "SEQUENCE OF <tag>"
240 */
mbedtls_asn1_get_sequence_of(unsigned char ** p,const unsigned char * end,mbedtls_asn1_sequence * cur,int tag)241 int mbedtls_asn1_get_sequence_of( unsigned char **p,
242 const unsigned char *end,
243 mbedtls_asn1_sequence *cur,
244 int tag)
245 {
246 int ret;
247 size_t len;
248 mbedtls_asn1_buf *buf;
249
250 /* Get main sequence tag */
251 if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
252 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
253 return( ret );
254
255 if( *p + len != end )
256 return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
257
258 while( *p < end )
259 {
260 buf = &(cur->buf);
261 buf->tag = **p;
262
263 if( ( ret = mbedtls_asn1_get_tag( p, end, &buf->len, tag ) ) != 0 )
264 return( ret );
265
266 buf->p = *p;
267 *p += buf->len;
268
269 /* Allocate and assign next pointer */
270 if( *p < end )
271 {
272 cur->next = (mbedtls_asn1_sequence*)mbedtls_calloc( 1,
273 sizeof( mbedtls_asn1_sequence ) );
274
275 if( cur->next == NULL )
276 return( MBEDTLS_ERR_ASN1_ALLOC_FAILED );
277
278 cur = cur->next;
279 }
280 }
281
282 /* Set final sequence entry's next pointer to NULL */
283 cur->next = NULL;
284
285 if( *p != end )
286 return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
287
288 return( 0 );
289 }
290
mbedtls_asn1_get_alg(unsigned char ** p,const unsigned char * end,mbedtls_asn1_buf * alg,mbedtls_asn1_buf * params)291 int mbedtls_asn1_get_alg( unsigned char **p,
292 const unsigned char *end,
293 mbedtls_asn1_buf *alg, mbedtls_asn1_buf *params )
294 {
295 int ret;
296 size_t len;
297
298 if( ( ret = mbedtls_asn1_get_tag( p, end, &len,
299 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
300 return( ret );
301
302 if( ( end - *p ) < 1 )
303 return( MBEDTLS_ERR_ASN1_OUT_OF_DATA );
304
305 alg->tag = **p;
306 end = *p + len;
307
308 if( ( ret = mbedtls_asn1_get_tag( p, end, &alg->len, MBEDTLS_ASN1_OID ) ) != 0 )
309 return( ret );
310
311 alg->p = *p;
312 *p += alg->len;
313
314 if( *p == end )
315 {
316 mbedtls_zeroize( params, sizeof(mbedtls_asn1_buf) );
317 return( 0 );
318 }
319
320 params->tag = **p;
321 (*p)++;
322
323 if( ( ret = mbedtls_asn1_get_len( p, end, ¶ms->len ) ) != 0 )
324 return( ret );
325
326 params->p = *p;
327 *p += params->len;
328
329 if( *p != end )
330 return( MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
331
332 return( 0 );
333 }
334
mbedtls_asn1_get_alg_null(unsigned char ** p,const unsigned char * end,mbedtls_asn1_buf * alg)335 int mbedtls_asn1_get_alg_null( unsigned char **p,
336 const unsigned char *end,
337 mbedtls_asn1_buf *alg )
338 {
339 int ret;
340 mbedtls_asn1_buf params;
341
342 memset( ¶ms, 0, sizeof(mbedtls_asn1_buf) );
343
344 if( ( ret = mbedtls_asn1_get_alg( p, end, alg, ¶ms ) ) != 0 )
345 return( ret );
346
347 if( ( params.tag != MBEDTLS_ASN1_NULL && params.tag != 0 ) || params.len != 0 )
348 return( MBEDTLS_ERR_ASN1_INVALID_DATA );
349
350 return( 0 );
351 }
352
mbedtls_asn1_free_named_data(mbedtls_asn1_named_data * cur)353 void mbedtls_asn1_free_named_data( mbedtls_asn1_named_data *cur )
354 {
355 if( cur == NULL )
356 return;
357
358 mbedtls_free( cur->oid.p );
359 mbedtls_free( cur->val.p );
360
361 mbedtls_zeroize( cur, sizeof( mbedtls_asn1_named_data ) );
362 }
363
mbedtls_asn1_free_named_data_list(mbedtls_asn1_named_data ** head)364 void mbedtls_asn1_free_named_data_list( mbedtls_asn1_named_data **head )
365 {
366 mbedtls_asn1_named_data *cur;
367
368 while( ( cur = *head ) != NULL )
369 {
370 *head = cur->next;
371 mbedtls_asn1_free_named_data( cur );
372 mbedtls_free( cur );
373 }
374 }
375
mbedtls_asn1_find_named_data(mbedtls_asn1_named_data * list,const char * oid,size_t len)376 mbedtls_asn1_named_data *mbedtls_asn1_find_named_data( mbedtls_asn1_named_data *list,
377 const char *oid, size_t len )
378 {
379 while( list != NULL )
380 {
381 if( list->oid.len == len &&
382 memcmp( list->oid.p, oid, len ) == 0 )
383 {
384 break;
385 }
386
387 list = list->next;
388 }
389
390 return( list );
391 }
392
393 #endif /* MBEDTLS_ASN1_PARSE_C */
394
