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( len <= 0xFFFFFFFF )
87 {
88 if( *p - start < 5 )
89 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
90
91 *--(*p) = ( len ) & 0xFF;
92 *--(*p) = ( len >> 8 ) & 0xFF;
93 *--(*p) = ( len >> 16 ) & 0xFF;
94 *--(*p) = ( len >> 24 ) & 0xFF;
95 *--(*p) = 0x84;
96 return( 5 );
97 }
98
99 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
100 }
101
mbedtls_asn1_write_tag(unsigned char ** p,unsigned char * start,unsigned char tag)102 int mbedtls_asn1_write_tag( unsigned char **p, unsigned char *start, unsigned char tag )
103 {
104 if( *p - start < 1 )
105 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
106
107 *--(*p) = tag;
108
109 return( 1 );
110 }
111
mbedtls_asn1_write_raw_buffer(unsigned char ** p,unsigned char * start,const unsigned char * buf,size_t size)112 int mbedtls_asn1_write_raw_buffer( unsigned char **p, unsigned char *start,
113 const unsigned char *buf, size_t size )
114 {
115 size_t len = 0;
116
117 if( *p < start || (size_t)( *p - start ) < size )
118 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
119
120 len = size;
121 (*p) -= len;
122 memcpy( *p, buf, len );
123
124 return( (int) len );
125 }
126
127 #if defined(MBEDTLS_BIGNUM_C)
mbedtls_asn1_write_mpi(unsigned char ** p,unsigned char * start,const mbedtls_mpi * X)128 int mbedtls_asn1_write_mpi( unsigned char **p, unsigned char *start, const mbedtls_mpi *X )
129 {
130 int ret;
131 size_t len = 0;
132
133 // Write the MPI
134 //
135 len = mbedtls_mpi_size( X );
136
137 if( *p < start || (size_t)( *p - start ) < len )
138 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
139
140 (*p) -= len;
141 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( X, *p, len ) );
142
143 // DER format assumes 2s complement for numbers, so the leftmost bit
144 // should be 0 for positive numbers and 1 for negative numbers.
145 //
146 if( X->s ==1 && **p & 0x80 )
147 {
148 if( *p - start < 1 )
149 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
150
151 *--(*p) = 0x00;
152 len += 1;
153 }
154
155 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
156 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );
157
158 ret = (int) len;
159
160 cleanup:
161 return( ret );
162 }
163 #endif /* MBEDTLS_BIGNUM_C */
164
mbedtls_asn1_write_null(unsigned char ** p,unsigned char * start)165 int mbedtls_asn1_write_null( unsigned char **p, unsigned char *start )
166 {
167 int ret;
168 size_t len = 0;
169
170 // Write NULL
171 //
172 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, 0) );
173 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_NULL ) );
174
175 return( (int) len );
176 }
177
mbedtls_asn1_write_oid(unsigned char ** p,unsigned char * start,const char * oid,size_t oid_len)178 int mbedtls_asn1_write_oid( unsigned char **p, unsigned char *start,
179 const char *oid, size_t oid_len )
180 {
181 int ret;
182 size_t len = 0;
183
184 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
185 (const unsigned char *) oid, oid_len ) );
186 MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_len( p, start, len ) );
187 MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OID ) );
188
189 return( (int) len );
190 }
191
mbedtls_asn1_write_algorithm_identifier(unsigned char ** p,unsigned char * start,const char * oid,size_t oid_len,size_t par_len)192 int mbedtls_asn1_write_algorithm_identifier( unsigned char **p, unsigned char *start,
193 const char *oid, size_t oid_len,
194 size_t par_len )
195 {
196 int ret;
197 size_t len = 0;
198
199 if( par_len == 0 )
200 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_null( p, start ) );
201 else
202 len += par_len;
203
204 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) );
205
206 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
207 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start,
208 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
209
210 return( (int) len );
211 }
212
mbedtls_asn1_write_bool(unsigned char ** p,unsigned char * start,int boolean)213 int mbedtls_asn1_write_bool( unsigned char **p, unsigned char *start, int boolean )
214 {
215 int ret;
216 size_t len = 0;
217
218 if( *p - start < 1 )
219 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
220
221 *--(*p) = (boolean) ? 255 : 0;
222 len++;
223
224 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
225 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BOOLEAN ) );
226
227 return( (int) len );
228 }
229
mbedtls_asn1_write_int(unsigned char ** p,unsigned char * start,int val)230 int mbedtls_asn1_write_int( unsigned char **p, unsigned char *start, int val )
231 {
232 int ret;
233 size_t len = 0;
234
235 // TODO negative values and values larger than 128
236 // DER format assumes 2s complement for numbers, so the leftmost bit
237 // should be 0 for positive numbers and 1 for negative numbers.
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_printable_string(unsigned char ** p,unsigned char * start,const char * text,size_t text_len)260 int mbedtls_asn1_write_printable_string( unsigned char **p, unsigned char *start,
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, MBEDTLS_ASN1_PRINTABLE_STRING ) );
271
272 return( (int) len );
273 }
274
mbedtls_asn1_write_ia5_string(unsigned char ** p,unsigned char * start,const char * text,size_t text_len)275 int mbedtls_asn1_write_ia5_string( unsigned char **p, unsigned char *start,
276 const char *text, size_t text_len )
277 {
278 int ret;
279 size_t len = 0;
280
281 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
282 (const unsigned char *) text, text_len ) );
283
284 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
285 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_IA5_STRING ) );
286
287 return( (int) len );
288 }
289
mbedtls_asn1_write_bitstring(unsigned char ** p,unsigned char * start,const unsigned char * buf,size_t bits)290 int mbedtls_asn1_write_bitstring( unsigned char **p, unsigned char *start,
291 const unsigned char *buf, size_t bits )
292 {
293 int ret;
294 size_t len = 0, size;
295
296 size = ( bits / 8 ) + ( ( bits % 8 ) ? 1 : 0 );
297
298 // Calculate byte length
299 //
300 if( *p < start || (size_t)( *p - start ) < size + 1 )
301 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
302
303 len = size + 1;
304 (*p) -= size;
305 memcpy( *p, buf, size );
306
307 // Write unused bits
308 //
309 *--(*p) = (unsigned char) (size * 8 - bits);
310
311 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
312 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BIT_STRING ) );
313
314 return( (int) len );
315 }
316
mbedtls_asn1_write_octet_string(unsigned char ** p,unsigned char * start,const unsigned char * buf,size_t size)317 int mbedtls_asn1_write_octet_string( unsigned char **p, unsigned char *start,
318 const unsigned char *buf, size_t size )
319 {
320 int ret;
321 size_t len = 0;
322
323 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, buf, size ) );
324
325 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
326 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OCTET_STRING ) );
327
328 return( (int) len );
329 }
330
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)331 mbedtls_asn1_named_data *mbedtls_asn1_store_named_data( mbedtls_asn1_named_data **head,
332 const char *oid, size_t oid_len,
333 const unsigned char *val,
334 size_t val_len )
335 {
336 mbedtls_asn1_named_data *cur;
337
338 if( ( cur = mbedtls_asn1_find_named_data( *head, oid, oid_len ) ) == NULL )
339 {
340 // Add new entry if not present yet based on OID
341 //
342 cur = (mbedtls_asn1_named_data*)mbedtls_calloc( 1,
343 sizeof(mbedtls_asn1_named_data) );
344 if( cur == NULL )
345 return( NULL );
346
347 cur->oid.len = oid_len;
348 cur->oid.p = mbedtls_calloc( 1, oid_len );
349 if( cur->oid.p == NULL )
350 {
351 mbedtls_free( cur );
352 return( NULL );
353 }
354
355 memcpy( cur->oid.p, oid, oid_len );
356
357 cur->val.len = val_len;
358 cur->val.p = mbedtls_calloc( 1, val_len );
359 if( cur->val.p == NULL )
360 {
361 mbedtls_free( cur->oid.p );
362 mbedtls_free( cur );
363 return( NULL );
364 }
365
366 cur->next = *head;
367 *head = cur;
368 }
369 else if( cur->val.len < val_len )
370 {
371 /*
372 * Enlarge existing value buffer if needed
373 * Preserve old data until the allocation succeeded, to leave list in
374 * a consistent state in case allocation fails.
375 */
376 void *p = mbedtls_calloc( 1, val_len );
377 if( p == NULL )
378 return( NULL );
379
380 mbedtls_free( cur->val.p );
381 cur->val.p = p;
382 cur->val.len = val_len;
383 }
384
385 if( val != NULL )
386 memcpy( cur->val.p, val, val_len );
387
388 return( cur );
389 }
390 #endif /* MBEDTLS_ASN1_WRITE_C */
391
