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 "config.h"
24 #else
25 #include MBEDTLS_CONFIG_FILE
26 #endif
27
28
29 #if defined(MBEDTLS_ASN1_WRITE_C)
30
31 #include "asn1write.h"
32
33 #include <string.h>
34
35 #if defined(MBEDTLS_PLATFORM_C)
36 #include "mbedtls/platform.h"
37 #else
38 #include <stdlib.h>
39 #define mbedtls_calloc calloc
40 #define mbedtls_free free
41 #endif
42
mbedtls_asn1_write_len(unsigned char ** p,unsigned char * start,size_t len)43 int mbedtls_asn1_write_len( unsigned char **p, unsigned char *start, size_t len )
44 {
45 if( len < 0x80 )
46 {
47 if( *p - start < 1 )
48 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
49
50 *--(*p) = (unsigned char) len;
51 return( 1 );
52 }
53
54 if( len <= 0xFF )
55 {
56 if( *p - start < 2 )
57 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
58
59 *--(*p) = (unsigned char) len;
60 *--(*p) = 0x81;
61 return( 2 );
62 }
63
64 if( len <= 0xFFFF )
65 {
66 if( *p - start < 3 )
67 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
68
69 *--(*p) = ( len ) & 0xFF;
70 *--(*p) = ( len >> 8 ) & 0xFF;
71 *--(*p) = 0x82;
72 return( 3 );
73 }
74
75 if( len <= 0xFFFFFF )
76 {
77 if( *p - start < 4 )
78 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
79
80 *--(*p) = ( len ) & 0xFF;
81 *--(*p) = ( len >> 8 ) & 0xFF;
82 *--(*p) = ( len >> 16 ) & 0xFF;
83 *--(*p) = 0x83;
84 return( 4 );
85 }
86
87 if( len <= 0xFFFFFFFF )
88 {
89 if( *p - start < 5 )
90 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
91
92 *--(*p) = ( len ) & 0xFF;
93 *--(*p) = ( len >> 8 ) & 0xFF;
94 *--(*p) = ( len >> 16 ) & 0xFF;
95 *--(*p) = ( len >> 24 ) & 0xFF;
96 *--(*p) = 0x84;
97 return( 5 );
98 }
99
100 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
101 }
102
mbedtls_asn1_write_tag(unsigned char ** p,unsigned char * start,unsigned char tag)103 int mbedtls_asn1_write_tag( unsigned char **p, unsigned char *start, unsigned char tag )
104 {
105 if( *p - start < 1 )
106 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
107
108 *--(*p) = tag;
109
110 return( 1 );
111 }
112
mbedtls_asn1_write_raw_buffer(unsigned char ** p,unsigned char * start,const unsigned char * buf,size_t size)113 int mbedtls_asn1_write_raw_buffer( unsigned char **p, unsigned char *start,
114 const unsigned char *buf, size_t size )
115 {
116 size_t len = 0;
117
118 if( *p < start || (size_t)( *p - start ) < size )
119 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
120
121 len = size;
122 (*p) -= len;
123 memcpy( *p, buf, len );
124
125 return( (int) len );
126 }
127
128 #if defined(MBEDTLS_BIGNUM_C)
mbedtls_asn1_write_mpi(unsigned char ** p,unsigned char * start,const mbedtls_mpi * X)129 int mbedtls_asn1_write_mpi( unsigned char **p, unsigned char *start, const mbedtls_mpi *X )
130 {
131 int ret;
132 size_t len = 0;
133
134 // Write the MPI
135 //
136 len = mbedtls_mpi_size( X );
137
138 if( *p < start || (size_t)( *p - start ) < len )
139 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
140
141 (*p) -= len;
142 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( X, *p, len ) );
143
144 // DER format assumes 2s complement for numbers, so the leftmost bit
145 // should be 0 for positive numbers and 1 for negative numbers.
146 //
147 if( X->s ==1 && **p & 0x80 )
148 {
149 if( *p - start < 1 )
150 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
151
152 *--(*p) = 0x00;
153 len += 1;
154 }
155
156 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
157 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );
158
159 ret = (int) len;
160
161 cleanup:
162 return( ret );
163 }
164 #endif /* MBEDTLS_BIGNUM_C */
165
mbedtls_asn1_write_null(unsigned char ** p,unsigned char * start)166 int mbedtls_asn1_write_null( unsigned char **p, unsigned char *start )
167 {
168 int ret;
169 size_t len = 0;
170
171 // Write NULL
172 //
173 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, 0) );
174 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_NULL ) );
175
176 return( (int) len );
177 }
178
mbedtls_asn1_write_oid(unsigned char ** p,unsigned char * start,const char * oid,size_t oid_len)179 int mbedtls_asn1_write_oid( unsigned char **p, unsigned char *start,
180 const char *oid, size_t oid_len )
181 {
182 int ret;
183 size_t len = 0;
184
185 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
186 (const unsigned char *) oid, oid_len ) );
187 MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_len( p, start, len ) );
188 MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OID ) );
189
190 return( (int) len );
191 }
192
mbedtls_asn1_write_algorithm_identifier(unsigned char ** p,unsigned char * start,const char * oid,size_t oid_len,size_t par_len)193 int mbedtls_asn1_write_algorithm_identifier( unsigned char **p, unsigned char *start,
194 const char *oid, size_t oid_len,
195 size_t par_len )
196 {
197 int ret;
198 size_t len = 0;
199
200 if( par_len == 0 )
201 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_null( p, start ) );
202 else
203 len += par_len;
204
205 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) );
206
207 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
208 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start,
209 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
210
211 return( (int) len );
212 }
213
mbedtls_asn1_write_bool(unsigned char ** p,unsigned char * start,int boolean)214 int mbedtls_asn1_write_bool( unsigned char **p, unsigned char *start, int boolean )
215 {
216 int ret;
217 size_t len = 0;
218
219 if( *p - start < 1 )
220 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
221
222 *--(*p) = (boolean) ? 255 : 0;
223 len++;
224
225 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
226 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BOOLEAN ) );
227
228 return( (int) len );
229 }
230
mbedtls_asn1_write_int(unsigned char ** p,unsigned char * start,int val)231 int mbedtls_asn1_write_int( unsigned char **p, unsigned char *start, int val )
232 {
233 int ret;
234 size_t len = 0;
235
236 // TODO negative values and values larger than 128
237 // DER format assumes 2s complement for numbers, so the leftmost bit
238 // should be 0 for positive numbers and 1 for negative numbers.
239 //
240 if( *p - start < 1 )
241 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
242
243 len += 1;
244 *--(*p) = val;
245
246 if( val > 0 && **p & 0x80 )
247 {
248 if( *p - start < 1 )
249 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
250
251 *--(*p) = 0x00;
252 len += 1;
253 }
254
255 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
256 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );
257
258 return( (int) len );
259 }
260
mbedtls_asn1_write_printable_string(unsigned char ** p,unsigned char * start,const char * text,size_t text_len)261 int mbedtls_asn1_write_printable_string( unsigned char **p, unsigned char *start,
262 const char *text, size_t text_len )
263 {
264 int ret;
265 size_t len = 0;
266
267 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
268 (const unsigned char *) text, text_len ) );
269
270 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
271 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_PRINTABLE_STRING ) );
272
273 return( (int) len );
274 }
275
mbedtls_asn1_write_ia5_string(unsigned char ** p,unsigned char * start,const char * text,size_t text_len)276 int mbedtls_asn1_write_ia5_string( unsigned char **p, unsigned char *start,
277 const char *text, size_t text_len )
278 {
279 int ret;
280 size_t len = 0;
281
282 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
283 (const unsigned char *) text, text_len ) );
284
285 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
286 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_IA5_STRING ) );
287
288 return( (int) len );
289 }
290
mbedtls_asn1_write_bitstring(unsigned char ** p,unsigned char * start,const unsigned char * buf,size_t bits)291 int mbedtls_asn1_write_bitstring( unsigned char **p, unsigned char *start,
292 const unsigned char *buf, size_t bits )
293 {
294 int ret;
295 size_t len = 0, size;
296
297 size = ( bits / 8 ) + ( ( bits % 8 ) ? 1 : 0 );
298
299 // Calculate byte length
300 //
301 if( *p < start || (size_t)( *p - start ) < size + 1 )
302 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
303
304 len = size + 1;
305 (*p) -= size;
306 memcpy( *p, buf, size );
307
308 // Write unused bits
309 //
310 *--(*p) = (unsigned char) (size * 8 - bits);
311
312 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
313 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BIT_STRING ) );
314
315 return( (int) len );
316 }
317
mbedtls_asn1_write_octet_string(unsigned char ** p,unsigned char * start,const unsigned char * buf,size_t size)318 int mbedtls_asn1_write_octet_string( unsigned char **p, unsigned char *start,
319 const unsigned char *buf, size_t size )
320 {
321 int ret;
322 size_t len = 0;
323
324 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, buf, size ) );
325
326 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
327 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OCTET_STRING ) );
328
329 return( (int) len );
330 }
331
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)332 mbedtls_asn1_named_data *mbedtls_asn1_store_named_data( mbedtls_asn1_named_data **head,
333 const char *oid, size_t oid_len,
334 const unsigned char *val,
335 size_t val_len )
336 {
337 mbedtls_asn1_named_data *cur;
338
339 if( ( cur = mbedtls_asn1_find_named_data( *head, oid, oid_len ) ) == NULL )
340 {
341 // Add new entry if not present yet based on OID
342 //
343 cur = (mbedtls_asn1_named_data*)mbedtls_calloc( 1,
344 sizeof(mbedtls_asn1_named_data) );
345 if( cur == NULL )
346 return( NULL );
347
348 cur->oid.len = oid_len;
349 cur->oid.p = mbedtls_calloc( 1, oid_len );
350 if( cur->oid.p == NULL )
351 {
352 mbedtls_free( cur );
353 return( NULL );
354 }
355
356 memcpy( cur->oid.p, oid, oid_len );
357
358 cur->val.len = val_len;
359 cur->val.p = mbedtls_calloc( 1, val_len );
360 if( cur->val.p == NULL )
361 {
362 mbedtls_free( cur->oid.p );
363 mbedtls_free( cur );
364 return( NULL );
365 }
366
367 cur->next = *head;
368 *head = cur;
369 }
370 else if( cur->val.len < val_len )
371 {
372 /*
373 * Enlarge existing value buffer if needed
374 * Preserve old data until the allocation succeeded, to leave list in
375 * a consistent state in case allocation fails.
376 */
377 void *p = mbedtls_calloc( 1, val_len );
378 if( p == NULL )
379 return( NULL );
380
381 mbedtls_free( cur->val.p );
382 cur->val.p = p;
383 cur->val.len = val_len;
384 }
385
386 if( val != NULL )
387 memcpy( cur->val.p, val, val_len );
388
389 return( cur );
390 }
391 #endif /* MBEDTLS_ASN1_WRITE_C */
392