1 /*
2 * ASN.1 buffer writing functionality
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_WRITE_C)
29
30 #include "mbedtls/asn1write.h"
31
32 #include <string.h>
33
34 #if defined(MBEDTLS_PLATFORM_C)
35 #include "mbedtls/platform.h"
36 #else
37 #include <stdlib.h>
38 #define mbedtls_calloc calloc
39 #define mbedtls_free free
40 #endif
41
mbedtls_asn1_write_len(unsigned char ** p,unsigned char * start,size_t len)42 int mbedtls_asn1_write_len( unsigned char **p, unsigned char *start, size_t len )
43 {
44 if( len < 0x80 )
45 {
46 if( *p - start < 1 )
47 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
48
49 *--(*p) = (unsigned char) len;
50 return( 1 );
51 }
52
53 if( len <= 0xFF )
54 {
55 if( *p - start < 2 )
56 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
57
58 *--(*p) = (unsigned char) len;
59 *--(*p) = 0x81;
60 return( 2 );
61 }
62
63 if( len <= 0xFFFF )
64 {
65 if( *p - start < 3 )
66 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
67
68 *--(*p) = ( len ) & 0xFF;
69 *--(*p) = ( len >> 8 ) & 0xFF;
70 *--(*p) = 0x82;
71 return( 3 );
72 }
73
74 if( len <= 0xFFFFFF )
75 {
76 if( *p - start < 4 )
77 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
78
79 *--(*p) = ( len ) & 0xFF;
80 *--(*p) = ( len >> 8 ) & 0xFF;
81 *--(*p) = ( len >> 16 ) & 0xFF;
82 *--(*p) = 0x83;
83 return( 4 );
84 }
85
86 #if SIZE_MAX > 0xFFFFFFFF
87 if( len <= 0xFFFFFFFF )
88 #endif
89 {
90 if( *p - start < 5 )
91 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
92
93 *--(*p) = ( len ) & 0xFF;
94 *--(*p) = ( len >> 8 ) & 0xFF;
95 *--(*p) = ( len >> 16 ) & 0xFF;
96 *--(*p) = ( len >> 24 ) & 0xFF;
97 *--(*p) = 0x84;
98 return( 5 );
99 }
100
101 #if SIZE_MAX > 0xFFFFFFFF
102 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
103 #endif
104 }
105
mbedtls_asn1_write_tag(unsigned char ** p,unsigned char * start,unsigned char tag)106 int mbedtls_asn1_write_tag( unsigned char **p, unsigned char *start, unsigned char tag )
107 {
108 if( *p - start < 1 )
109 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
110
111 *--(*p) = tag;
112
113 return( 1 );
114 }
115
mbedtls_asn1_write_raw_buffer(unsigned char ** p,unsigned char * start,const unsigned char * buf,size_t size)116 int mbedtls_asn1_write_raw_buffer( unsigned char **p, unsigned char *start,
117 const unsigned char *buf, size_t size )
118 {
119 size_t len = 0;
120
121 if( *p < start || (size_t)( *p - start ) < size )
122 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
123
124 len = size;
125 (*p) -= len;
126 memcpy( *p, buf, len );
127
128 return( (int) len );
129 }
130
131 #if defined(MBEDTLS_BIGNUM_C)
mbedtls_asn1_write_mpi(unsigned char ** p,unsigned char * start,const mbedtls_mpi * X)132 int mbedtls_asn1_write_mpi( unsigned char **p, unsigned char *start, const mbedtls_mpi *X )
133 {
134 int ret;
135 size_t len = 0;
136
137 // Write the MPI
138 //
139 len = mbedtls_mpi_size( X );
140
141 if( *p < start || (size_t)( *p - start ) < len )
142 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
143
144 (*p) -= len;
145 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( X, *p, len ) );
146
147 // DER format assumes 2s complement for numbers, so the leftmost bit
148 // should be 0 for positive numbers and 1 for negative numbers.
149 //
150 if( X->s ==1 && **p & 0x80 )
151 {
152 if( *p - start < 1 )
153 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
154
155 *--(*p) = 0x00;
156 len += 1;
157 }
158
159 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
160 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );
161
162 ret = (int) len;
163
164 cleanup:
165 return( ret );
166 }
167 #endif /* MBEDTLS_BIGNUM_C */
168
mbedtls_asn1_write_null(unsigned char ** p,unsigned char * start)169 int mbedtls_asn1_write_null( unsigned char **p, unsigned char *start )
170 {
171 int ret;
172 size_t len = 0;
173
174 // Write NULL
175 //
176 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, 0) );
177 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_NULL ) );
178
179 return( (int) len );
180 }
181
mbedtls_asn1_write_oid(unsigned char ** p,unsigned char * start,const char * oid,size_t oid_len)182 int mbedtls_asn1_write_oid( unsigned char **p, unsigned char *start,
183 const char *oid, size_t oid_len )
184 {
185 int ret;
186 size_t len = 0;
187
188 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
189 (const unsigned char *) oid, oid_len ) );
190 MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_len( p, start, len ) );
191 MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OID ) );
192
193 return( (int) len );
194 }
195
mbedtls_asn1_write_algorithm_identifier(unsigned char ** p,unsigned char * start,const char * oid,size_t oid_len,size_t par_len)196 int mbedtls_asn1_write_algorithm_identifier( unsigned char **p, unsigned char *start,
197 const char *oid, size_t oid_len,
198 size_t par_len )
199 {
200 int ret;
201 size_t len = 0;
202
203 if( par_len == 0 )
204 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_null( p, start ) );
205 else
206 len += par_len;
207
208 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) );
209
210 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
211 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start,
212 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
213
214 return( (int) len );
215 }
216
mbedtls_asn1_write_bool(unsigned char ** p,unsigned char * start,int boolean)217 int mbedtls_asn1_write_bool( unsigned char **p, unsigned char *start, int boolean )
218 {
219 int ret;
220 size_t len = 0;
221
222 if( *p - start < 1 )
223 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
224
225 *--(*p) = (boolean) ? 255 : 0;
226 len++;
227
228 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
229 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BOOLEAN ) );
230
231 return( (int) len );
232 }
233
mbedtls_asn1_write_int(unsigned char ** p,unsigned char * start,int val)234 int mbedtls_asn1_write_int( unsigned char **p, unsigned char *start, int val )
235 {
236 int ret;
237 size_t len = 0;
238
239 if( *p - start < 1 )
240 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
241
242 len += 1;
243 *--(*p) = val;
244
245 if( val > 0 && **p & 0x80 )
246 {
247 if( *p - start < 1 )
248 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
249
250 *--(*p) = 0x00;
251 len += 1;
252 }
253
254 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
255 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );
256
257 return( (int) len );
258 }
259
mbedtls_asn1_write_tagged_string(unsigned char ** p,unsigned char * start,int tag,const char * text,size_t text_len)260 int mbedtls_asn1_write_tagged_string( unsigned char **p, unsigned char *start, int tag,
261 const char *text, size_t text_len )
262 {
263 int ret;
264 size_t len = 0;
265
266 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
267 (const unsigned char *) text, text_len ) );
268
269 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
270 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, tag ) );
271
272 return( (int) len );
273 }
274
mbedtls_asn1_write_utf8_string(unsigned char ** p,unsigned char * start,const char * text,size_t text_len)275 int mbedtls_asn1_write_utf8_string( unsigned char **p, unsigned char *start,
276 const char *text, size_t text_len )
277 {
278 return( mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_UTF8_STRING, text, text_len) );
279 }
280
mbedtls_asn1_write_printable_string(unsigned char ** p,unsigned char * start,const char * text,size_t text_len)281 int mbedtls_asn1_write_printable_string( unsigned char **p, unsigned char *start,
282 const char *text, size_t text_len )
283 {
284 return( mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_PRINTABLE_STRING, text, text_len) );
285 }
286
mbedtls_asn1_write_ia5_string(unsigned char ** p,unsigned char * start,const char * text,size_t text_len)287 int mbedtls_asn1_write_ia5_string( unsigned char **p, unsigned char *start,
288 const char *text, size_t text_len )
289 {
290 return( mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_IA5_STRING, text, text_len) );
291 }
292
mbedtls_asn1_write_bitstring(unsigned char ** p,unsigned char * start,const unsigned char * buf,size_t bits)293 int mbedtls_asn1_write_bitstring( unsigned char **p, unsigned char *start,
294 const unsigned char *buf, size_t bits )
295 {
296 int ret;
297 size_t len = 0, size;
298
299 size = ( bits / 8 ) + ( ( bits % 8 ) ? 1 : 0 );
300
301 // Calculate byte length
302 //
303 if( *p < start || (size_t)( *p - start ) < size + 1 )
304 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
305
306 len = size + 1;
307 (*p) -= size;
308 memcpy( *p, buf, size );
309
310 // Write unused bits
311 //
312 *--(*p) = (unsigned char) (size * 8 - bits);
313
314 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
315 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BIT_STRING ) );
316
317 return( (int) len );
318 }
319
mbedtls_asn1_write_octet_string(unsigned char ** p,unsigned char * start,const unsigned char * buf,size_t size)320 int mbedtls_asn1_write_octet_string( unsigned char **p, unsigned char *start,
321 const unsigned char *buf, size_t size )
322 {
323 int ret;
324 size_t len = 0;
325
326 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, buf, size ) );
327
328 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
329 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OCTET_STRING ) );
330
331 return( (int) len );
332 }
333
334
335 /* This is a copy of the ASN.1 parsing function mbedtls_asn1_find_named_data(),
336 * which is replicated to avoid a dependency ASN1_WRITE_C on ASN1_PARSE_C. */
asn1_find_named_data(mbedtls_asn1_named_data * list,const char * oid,size_t len)337 static mbedtls_asn1_named_data *asn1_find_named_data(
338 mbedtls_asn1_named_data *list,
339 const char *oid, size_t len )
340 {
341 while( list != NULL )
342 {
343 if( list->oid.len == len &&
344 memcmp( list->oid.p, oid, len ) == 0 )
345 {
346 break;
347 }
348
349 list = list->next;
350 }
351
352 return( list );
353 }
354
mbedtls_asn1_store_named_data(mbedtls_asn1_named_data ** head,const char * oid,size_t oid_len,const unsigned char * val,size_t val_len)355 mbedtls_asn1_named_data *mbedtls_asn1_store_named_data(
356 mbedtls_asn1_named_data **head,
357 const char *oid, size_t oid_len,
358 const unsigned char *val,
359 size_t val_len )
360 {
361 mbedtls_asn1_named_data *cur;
362
363 if( ( cur = asn1_find_named_data( *head, oid, oid_len ) ) == NULL )
364 {
365 // Add new entry if not present yet based on OID
366 //
367 cur = (mbedtls_asn1_named_data*)mbedtls_calloc( 1,
368 sizeof(mbedtls_asn1_named_data) );
369 if( cur == NULL )
370 return( NULL );
371
372 cur->oid.len = oid_len;
373 cur->oid.p = mbedtls_calloc( 1, oid_len );
374 if( cur->oid.p == NULL )
375 {
376 mbedtls_free( cur );
377 return( NULL );
378 }
379
380 memcpy( cur->oid.p, oid, oid_len );
381
382 cur->val.len = val_len;
383 cur->val.p = mbedtls_calloc( 1, val_len );
384 if( cur->val.p == NULL )
385 {
386 mbedtls_free( cur->oid.p );
387 mbedtls_free( cur );
388 return( NULL );
389 }
390
391 cur->next = *head;
392 *head = cur;
393 }
394 else if( cur->val.len < val_len )
395 {
396 /*
397 * Enlarge existing value buffer if needed
398 * Preserve old data until the allocation succeeded, to leave list in
399 * a consistent state in case allocation fails.
400 */
401 void *p = mbedtls_calloc( 1, val_len );
402 if( p == NULL )
403 return( NULL );
404
405 mbedtls_free( cur->val.p );
406 cur->val.p = p;
407 cur->val.len = val_len;
408 }
409
410 if( val != NULL )
411 memcpy( cur->val.p, val, val_len );
412
413 return( cur );
414 }
415 #endif /* MBEDTLS_ASN1_WRITE_C */
416