1 /*
2 * X.509 certificate writing
3 *
4 * Copyright The Mbed TLS Contributors
5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
6 */
7 /*
8 * References:
9 * - certificates: RFC 5280, updated by RFC 6818
10 * - CSRs: PKCS#10 v1.7 aka RFC 2986
11 * - attributes: PKCS#9 v2.0 aka RFC 2985
12 */
13
14 #include "x509_internal.h"
15
16 #if defined(MBEDTLS_X509_CRT_WRITE_C)
17
18 #include "mbedtls/x509_crt.h"
19 #include "mbedtls/asn1write.h"
20 #include "mbedtls/error.h"
21 #include "mbedtls/oid.h"
22 #include "x509_oid.h"
23 #include "mbedtls/platform.h"
24 #include "mbedtls/platform_util.h"
25 #include "mbedtls/md.h"
26
27 #include <string.h>
28 #include <stdint.h>
29
30 #if defined(MBEDTLS_PEM_WRITE_C)
31 #include "mbedtls/pem.h"
32 #endif /* MBEDTLS_PEM_WRITE_C */
33
34 #include "psa/crypto.h"
35 #include "psa_util_internal.h"
36 #include "mbedtls/psa_util.h"
37
mbedtls_x509write_crt_init(mbedtls_x509write_cert * ctx)38 void mbedtls_x509write_crt_init(mbedtls_x509write_cert *ctx)
39 {
40 memset(ctx, 0, sizeof(mbedtls_x509write_cert));
41
42 ctx->version = MBEDTLS_X509_CRT_VERSION_3;
43 }
44
mbedtls_x509write_crt_free(mbedtls_x509write_cert * ctx)45 void mbedtls_x509write_crt_free(mbedtls_x509write_cert *ctx)
46 {
47 if (ctx == NULL) {
48 return;
49 }
50
51 mbedtls_asn1_free_named_data_list(&ctx->subject);
52 mbedtls_asn1_free_named_data_list(&ctx->issuer);
53 mbedtls_asn1_free_named_data_list(&ctx->extensions);
54
55 mbedtls_platform_zeroize(ctx, sizeof(mbedtls_x509write_cert));
56 }
57
mbedtls_x509write_crt_set_version(mbedtls_x509write_cert * ctx,int version)58 void mbedtls_x509write_crt_set_version(mbedtls_x509write_cert *ctx,
59 int version)
60 {
61 ctx->version = version;
62 }
63
mbedtls_x509write_crt_set_md_alg(mbedtls_x509write_cert * ctx,mbedtls_md_type_t md_alg)64 void mbedtls_x509write_crt_set_md_alg(mbedtls_x509write_cert *ctx,
65 mbedtls_md_type_t md_alg)
66 {
67 ctx->md_alg = md_alg;
68 }
69
mbedtls_x509write_crt_set_subject_key(mbedtls_x509write_cert * ctx,mbedtls_pk_context * key)70 void mbedtls_x509write_crt_set_subject_key(mbedtls_x509write_cert *ctx,
71 mbedtls_pk_context *key)
72 {
73 ctx->subject_key = key;
74 }
75
mbedtls_x509write_crt_set_issuer_key(mbedtls_x509write_cert * ctx,mbedtls_pk_context * key)76 void mbedtls_x509write_crt_set_issuer_key(mbedtls_x509write_cert *ctx,
77 mbedtls_pk_context *key)
78 {
79 ctx->issuer_key = key;
80 }
81
mbedtls_x509write_crt_set_subject_name(mbedtls_x509write_cert * ctx,const char * subject_name)82 int mbedtls_x509write_crt_set_subject_name(mbedtls_x509write_cert *ctx,
83 const char *subject_name)
84 {
85 mbedtls_asn1_free_named_data_list(&ctx->subject);
86 return mbedtls_x509_string_to_names(&ctx->subject, subject_name);
87 }
88
mbedtls_x509write_crt_set_issuer_name(mbedtls_x509write_cert * ctx,const char * issuer_name)89 int mbedtls_x509write_crt_set_issuer_name(mbedtls_x509write_cert *ctx,
90 const char *issuer_name)
91 {
92 mbedtls_asn1_free_named_data_list(&ctx->issuer);
93 return mbedtls_x509_string_to_names(&ctx->issuer, issuer_name);
94 }
95
mbedtls_x509write_crt_set_serial_raw(mbedtls_x509write_cert * ctx,const unsigned char * serial,size_t serial_len)96 int mbedtls_x509write_crt_set_serial_raw(mbedtls_x509write_cert *ctx,
97 const unsigned char *serial, size_t serial_len)
98 {
99 if (serial_len > MBEDTLS_X509_RFC5280_MAX_SERIAL_LEN) {
100 return MBEDTLS_ERR_X509_BAD_INPUT_DATA;
101 }
102
103 ctx->serial_len = serial_len;
104 memcpy(ctx->serial, serial, serial_len);
105
106 return 0;
107 }
108
mbedtls_x509write_crt_set_validity(mbedtls_x509write_cert * ctx,const char * not_before,const char * not_after)109 int mbedtls_x509write_crt_set_validity(mbedtls_x509write_cert *ctx,
110 const char *not_before,
111 const char *not_after)
112 {
113 if (strlen(not_before) != MBEDTLS_X509_RFC5280_UTC_TIME_LEN - 1 ||
114 strlen(not_after) != MBEDTLS_X509_RFC5280_UTC_TIME_LEN - 1) {
115 return MBEDTLS_ERR_X509_BAD_INPUT_DATA;
116 }
117 strncpy(ctx->not_before, not_before, MBEDTLS_X509_RFC5280_UTC_TIME_LEN);
118 strncpy(ctx->not_after, not_after, MBEDTLS_X509_RFC5280_UTC_TIME_LEN);
119 ctx->not_before[MBEDTLS_X509_RFC5280_UTC_TIME_LEN - 1] = 'Z';
120 ctx->not_after[MBEDTLS_X509_RFC5280_UTC_TIME_LEN - 1] = 'Z';
121
122 return 0;
123 }
124
mbedtls_x509write_crt_set_subject_alternative_name(mbedtls_x509write_cert * ctx,const mbedtls_x509_san_list * san_list)125 int mbedtls_x509write_crt_set_subject_alternative_name(mbedtls_x509write_cert *ctx,
126 const mbedtls_x509_san_list *san_list)
127 {
128 return mbedtls_x509_write_set_san_common(&ctx->extensions, san_list);
129 }
130
131
mbedtls_x509write_crt_set_extension(mbedtls_x509write_cert * ctx,const char * oid,size_t oid_len,int critical,const unsigned char * val,size_t val_len)132 int mbedtls_x509write_crt_set_extension(mbedtls_x509write_cert *ctx,
133 const char *oid, size_t oid_len,
134 int critical,
135 const unsigned char *val, size_t val_len)
136 {
137 return mbedtls_x509_set_extension(&ctx->extensions, oid, oid_len,
138 critical, val, val_len);
139 }
140
mbedtls_x509write_crt_set_basic_constraints(mbedtls_x509write_cert * ctx,int is_ca,int max_pathlen)141 int mbedtls_x509write_crt_set_basic_constraints(mbedtls_x509write_cert *ctx,
142 int is_ca, int max_pathlen)
143 {
144 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
145 unsigned char buf[9];
146 unsigned char *c = buf + sizeof(buf);
147 size_t len = 0;
148
149 memset(buf, 0, sizeof(buf));
150
151 if (is_ca && max_pathlen > 127) {
152 return MBEDTLS_ERR_X509_BAD_INPUT_DATA;
153 }
154
155 if (is_ca) {
156 if (max_pathlen >= 0) {
157 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_int(&c, buf,
158 max_pathlen));
159 }
160 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_bool(&c, buf, 1));
161 }
162
163 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
164 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf,
165 MBEDTLS_ASN1_CONSTRUCTED |
166 MBEDTLS_ASN1_SEQUENCE));
167
168 return
169 mbedtls_x509write_crt_set_extension(ctx, MBEDTLS_OID_BASIC_CONSTRAINTS,
170 MBEDTLS_OID_SIZE(MBEDTLS_OID_BASIC_CONSTRAINTS),
171 is_ca, buf + sizeof(buf) - len, len);
172 }
173
174 #if defined(PSA_WANT_ALG_SHA_1)
mbedtls_x509write_crt_set_key_identifier(mbedtls_x509write_cert * ctx,int is_ca,unsigned char tag)175 static int mbedtls_x509write_crt_set_key_identifier(mbedtls_x509write_cert *ctx,
176 int is_ca,
177 unsigned char tag)
178 {
179 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
180 unsigned char buf[MBEDTLS_MPI_MAX_SIZE * 2 + 20]; /* tag, length + 2xMPI */
181 unsigned char *c = buf + sizeof(buf);
182 size_t len = 0;
183 psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
184 size_t hash_length;
185
186 memset(buf, 0, sizeof(buf));
187 MBEDTLS_ASN1_CHK_ADD(len,
188 mbedtls_pk_write_pubkey(&c,
189 buf,
190 is_ca ?
191 ctx->issuer_key :
192 ctx->subject_key));
193
194
195 status = psa_hash_compute(PSA_ALG_SHA_1,
196 buf + sizeof(buf) - len,
197 len,
198 buf + sizeof(buf) - 20,
199 20,
200 &hash_length);
201 if (status != PSA_SUCCESS) {
202 return MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED;
203 }
204
205 c = buf + sizeof(buf) - 20;
206 len = 20;
207
208 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
209 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf, tag));
210
211 if (is_ca) { // writes AuthorityKeyIdentifier sequence
212 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
213 MBEDTLS_ASN1_CHK_ADD(len,
214 mbedtls_asn1_write_tag(&c,
215 buf,
216 MBEDTLS_ASN1_CONSTRUCTED |
217 MBEDTLS_ASN1_SEQUENCE));
218 }
219
220 if (is_ca) {
221 return mbedtls_x509write_crt_set_extension(ctx,
222 MBEDTLS_OID_AUTHORITY_KEY_IDENTIFIER,
223 MBEDTLS_OID_SIZE(
224 MBEDTLS_OID_AUTHORITY_KEY_IDENTIFIER),
225 0, buf + sizeof(buf) - len, len);
226 } else {
227 return mbedtls_x509write_crt_set_extension(ctx,
228 MBEDTLS_OID_SUBJECT_KEY_IDENTIFIER,
229 MBEDTLS_OID_SIZE(
230 MBEDTLS_OID_SUBJECT_KEY_IDENTIFIER),
231 0, buf + sizeof(buf) - len, len);
232 }
233 }
234
mbedtls_x509write_crt_set_subject_key_identifier(mbedtls_x509write_cert * ctx)235 int mbedtls_x509write_crt_set_subject_key_identifier(mbedtls_x509write_cert *ctx)
236 {
237 return mbedtls_x509write_crt_set_key_identifier(ctx,
238 0,
239 MBEDTLS_ASN1_OCTET_STRING);
240 }
241
mbedtls_x509write_crt_set_authority_key_identifier(mbedtls_x509write_cert * ctx)242 int mbedtls_x509write_crt_set_authority_key_identifier(mbedtls_x509write_cert *ctx)
243 {
244 return mbedtls_x509write_crt_set_key_identifier(ctx,
245 1,
246 (MBEDTLS_ASN1_CONTEXT_SPECIFIC | 0));
247 }
248 #endif /* PSA_WANT_ALG_SHA_1 */
249
mbedtls_x509write_crt_set_key_usage(mbedtls_x509write_cert * ctx,unsigned int key_usage)250 int mbedtls_x509write_crt_set_key_usage(mbedtls_x509write_cert *ctx,
251 unsigned int key_usage)
252 {
253 unsigned char buf[5] = { 0 }, ku[2] = { 0 };
254 unsigned char *c;
255 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
256 const unsigned int allowed_bits = MBEDTLS_X509_KU_DIGITAL_SIGNATURE |
257 MBEDTLS_X509_KU_NON_REPUDIATION |
258 MBEDTLS_X509_KU_KEY_ENCIPHERMENT |
259 MBEDTLS_X509_KU_DATA_ENCIPHERMENT |
260 MBEDTLS_X509_KU_KEY_AGREEMENT |
261 MBEDTLS_X509_KU_KEY_CERT_SIGN |
262 MBEDTLS_X509_KU_CRL_SIGN |
263 MBEDTLS_X509_KU_ENCIPHER_ONLY |
264 MBEDTLS_X509_KU_DECIPHER_ONLY;
265
266 /* Check that nothing other than the allowed flags is set */
267 if ((key_usage & ~allowed_bits) != 0) {
268 return MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE;
269 }
270
271 c = buf + 5;
272 MBEDTLS_PUT_UINT16_LE(key_usage, ku, 0);
273 ret = mbedtls_asn1_write_named_bitstring(&c, buf, ku, 9);
274
275 if (ret < 0) {
276 return ret;
277 } else if (ret < 3 || ret > 5) {
278 return MBEDTLS_ERR_X509_INVALID_FORMAT;
279 }
280
281 ret = mbedtls_x509write_crt_set_extension(ctx, MBEDTLS_OID_KEY_USAGE,
282 MBEDTLS_OID_SIZE(MBEDTLS_OID_KEY_USAGE),
283 1, c, (size_t) ret);
284 if (ret != 0) {
285 return ret;
286 }
287
288 return 0;
289 }
290
mbedtls_x509write_crt_set_ext_key_usage(mbedtls_x509write_cert * ctx,const mbedtls_asn1_sequence * exts)291 int mbedtls_x509write_crt_set_ext_key_usage(mbedtls_x509write_cert *ctx,
292 const mbedtls_asn1_sequence *exts)
293 {
294 unsigned char buf[256];
295 unsigned char *c = buf + sizeof(buf);
296 int ret;
297 size_t len = 0;
298 const mbedtls_asn1_sequence *last_ext = NULL;
299 const mbedtls_asn1_sequence *ext;
300
301 memset(buf, 0, sizeof(buf));
302
303 /* We need at least one extension: SEQUENCE SIZE (1..MAX) OF KeyPurposeId */
304 if (exts == NULL) {
305 return MBEDTLS_ERR_X509_BAD_INPUT_DATA;
306 }
307
308 /* Iterate over exts backwards, so we write them out in the requested order */
309 while (last_ext != exts) {
310 for (ext = exts; ext->next != last_ext; ext = ext->next) {
311 }
312 if (ext->buf.tag != MBEDTLS_ASN1_OID) {
313 return MBEDTLS_ERR_X509_BAD_INPUT_DATA;
314 }
315 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(&c, buf, ext->buf.p, ext->buf.len));
316 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, ext->buf.len));
317 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_OID));
318 last_ext = ext;
319 }
320
321 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
322 MBEDTLS_ASN1_CHK_ADD(len,
323 mbedtls_asn1_write_tag(&c, buf,
324 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));
325
326 return mbedtls_x509write_crt_set_extension(ctx,
327 MBEDTLS_OID_EXTENDED_KEY_USAGE,
328 MBEDTLS_OID_SIZE(MBEDTLS_OID_EXTENDED_KEY_USAGE),
329 1, c, len);
330 }
331
mbedtls_x509write_crt_set_ns_cert_type(mbedtls_x509write_cert * ctx,unsigned char ns_cert_type)332 int mbedtls_x509write_crt_set_ns_cert_type(mbedtls_x509write_cert *ctx,
333 unsigned char ns_cert_type)
334 {
335 unsigned char buf[4] = { 0 };
336 unsigned char *c;
337 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
338
339 c = buf + 4;
340
341 ret = mbedtls_asn1_write_named_bitstring(&c, buf, &ns_cert_type, 8);
342 if (ret < 3 || ret > 4) {
343 return ret;
344 }
345
346 ret = mbedtls_x509write_crt_set_extension(ctx, MBEDTLS_OID_NS_CERT_TYPE,
347 MBEDTLS_OID_SIZE(MBEDTLS_OID_NS_CERT_TYPE),
348 0, c, (size_t) ret);
349 if (ret != 0) {
350 return ret;
351 }
352
353 return 0;
354 }
355
x509_write_time(unsigned char ** p,unsigned char * start,const char * t,size_t size)356 static int x509_write_time(unsigned char **p, unsigned char *start,
357 const char *t, size_t size)
358 {
359 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
360 size_t len = 0;
361
362 /*
363 * write MBEDTLS_ASN1_UTC_TIME if year < 2050 (2 bytes shorter)
364 */
365 if (t[0] < '2' || (t[0] == '2' && t[1] == '0' && t[2] < '5')) {
366 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start,
367 (const unsigned char *) t + 2,
368 size - 2));
369 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
370 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start,
371 MBEDTLS_ASN1_UTC_TIME));
372 } else {
373 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start,
374 (const unsigned char *) t,
375 size));
376 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
377 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start,
378 MBEDTLS_ASN1_GENERALIZED_TIME));
379 }
380
381 return (int) len;
382 }
383
mbedtls_x509write_crt_der(mbedtls_x509write_cert * ctx,unsigned char * buf,size_t size)384 int mbedtls_x509write_crt_der(mbedtls_x509write_cert *ctx,
385 unsigned char *buf, size_t size)
386 {
387 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
388 const char *sig_oid;
389 size_t sig_oid_len = 0;
390 unsigned char *c, *c2;
391 unsigned char sig[MBEDTLS_PK_SIGNATURE_MAX_SIZE];
392 size_t hash_length = 0;
393 unsigned char hash[MBEDTLS_MD_MAX_SIZE];
394 psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
395 psa_algorithm_t psa_algorithm;
396
397 size_t sub_len = 0, pub_len = 0, sig_and_oid_len = 0, sig_len;
398 size_t len = 0;
399 mbedtls_pk_type_t pk_alg;
400 int write_sig_null_par;
401
402 /*
403 * Prepare data to be signed at the end of the target buffer
404 */
405 c = buf + size;
406
407 /* Signature algorithm needed in TBS, and later for actual signature */
408
409 /* There's no direct way of extracting a signature algorithm
410 * (represented as an element of mbedtls_pk_type_t) from a PK instance. */
411 if (mbedtls_pk_can_do(ctx->issuer_key, MBEDTLS_PK_RSA)) {
412 pk_alg = MBEDTLS_PK_RSA;
413 } else if (mbedtls_pk_can_do(ctx->issuer_key, MBEDTLS_PK_ECDSA)) {
414 pk_alg = MBEDTLS_PK_ECDSA;
415 } else {
416 return MBEDTLS_ERR_X509_INVALID_ALG;
417 }
418
419 if ((ret = mbedtls_x509_oid_get_oid_by_sig_alg((mbedtls_pk_sigalg_t) pk_alg, ctx->md_alg,
420 &sig_oid, &sig_oid_len)) != 0) {
421 return ret;
422 }
423
424 /*
425 * Extensions ::= SEQUENCE SIZE (1..MAX) OF Extension
426 */
427
428 /* Only for v3 */
429 if (ctx->version == MBEDTLS_X509_CRT_VERSION_3) {
430 MBEDTLS_ASN1_CHK_ADD(len,
431 mbedtls_x509_write_extensions(&c,
432 buf, ctx->extensions));
433 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
434 MBEDTLS_ASN1_CHK_ADD(len,
435 mbedtls_asn1_write_tag(&c, buf,
436 MBEDTLS_ASN1_CONSTRUCTED |
437 MBEDTLS_ASN1_SEQUENCE));
438 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
439 MBEDTLS_ASN1_CHK_ADD(len,
440 mbedtls_asn1_write_tag(&c, buf,
441 MBEDTLS_ASN1_CONTEXT_SPECIFIC |
442 MBEDTLS_ASN1_CONSTRUCTED | 3));
443 }
444
445 /*
446 * SubjectPublicKeyInfo
447 */
448 MBEDTLS_ASN1_CHK_ADD(pub_len,
449 mbedtls_pk_write_pubkey_der(ctx->subject_key,
450 buf, (size_t) (c - buf)));
451 c -= pub_len;
452 len += pub_len;
453
454 /*
455 * Subject ::= Name
456 */
457 MBEDTLS_ASN1_CHK_ADD(len,
458 mbedtls_x509_write_names(&c, buf,
459 ctx->subject));
460
461 /*
462 * Validity ::= SEQUENCE {
463 * notBefore Time,
464 * notAfter Time }
465 */
466 sub_len = 0;
467
468 MBEDTLS_ASN1_CHK_ADD(sub_len,
469 x509_write_time(&c, buf, ctx->not_after,
470 MBEDTLS_X509_RFC5280_UTC_TIME_LEN));
471
472 MBEDTLS_ASN1_CHK_ADD(sub_len,
473 x509_write_time(&c, buf, ctx->not_before,
474 MBEDTLS_X509_RFC5280_UTC_TIME_LEN));
475
476 len += sub_len;
477 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, sub_len));
478 MBEDTLS_ASN1_CHK_ADD(len,
479 mbedtls_asn1_write_tag(&c, buf,
480 MBEDTLS_ASN1_CONSTRUCTED |
481 MBEDTLS_ASN1_SEQUENCE));
482
483 /*
484 * Issuer ::= Name
485 */
486 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_x509_write_names(&c, buf,
487 ctx->issuer));
488
489 /*
490 * Signature ::= AlgorithmIdentifier
491 */
492 if (pk_alg == MBEDTLS_PK_ECDSA) {
493 /*
494 * The AlgorithmIdentifier's parameters field must be absent for DSA/ECDSA signature
495 * algorithms, see https://www.rfc-editor.org/rfc/rfc5480#page-17 and
496 * https://www.rfc-editor.org/rfc/rfc5758#section-3.
497 */
498 write_sig_null_par = 0;
499 } else {
500 write_sig_null_par = 1;
501 }
502 MBEDTLS_ASN1_CHK_ADD(len,
503 mbedtls_asn1_write_algorithm_identifier_ext(&c, buf,
504 sig_oid, strlen(sig_oid),
505 0, write_sig_null_par));
506
507 /*
508 * Serial ::= INTEGER
509 *
510 * Written data is:
511 * - "ctx->serial_len" bytes for the raw serial buffer
512 * - if MSb of "serial" is 1, then prepend an extra 0x00 byte
513 * - 1 byte for the length
514 * - 1 byte for the TAG
515 */
516 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(&c, buf,
517 ctx->serial, ctx->serial_len));
518 if (*c & 0x80) {
519 if (c - buf < 1) {
520 return MBEDTLS_ERR_X509_BUFFER_TOO_SMALL;
521 }
522 *(--c) = 0x0;
523 len++;
524 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf,
525 ctx->serial_len + 1));
526 } else {
527 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf,
528 ctx->serial_len));
529 }
530 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf,
531 MBEDTLS_ASN1_INTEGER));
532
533 /*
534 * Version ::= INTEGER { v1(0), v2(1), v3(2) }
535 */
536
537 /* Can be omitted for v1 */
538 if (ctx->version != MBEDTLS_X509_CRT_VERSION_1) {
539 sub_len = 0;
540 MBEDTLS_ASN1_CHK_ADD(sub_len,
541 mbedtls_asn1_write_int(&c, buf, ctx->version));
542 len += sub_len;
543 MBEDTLS_ASN1_CHK_ADD(len,
544 mbedtls_asn1_write_len(&c, buf, sub_len));
545 MBEDTLS_ASN1_CHK_ADD(len,
546 mbedtls_asn1_write_tag(&c, buf,
547 MBEDTLS_ASN1_CONTEXT_SPECIFIC |
548 MBEDTLS_ASN1_CONSTRUCTED | 0));
549 }
550
551 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
552 MBEDTLS_ASN1_CHK_ADD(len,
553 mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_CONSTRUCTED |
554 MBEDTLS_ASN1_SEQUENCE));
555
556 /*
557 * Make signature
558 */
559
560 /* Compute hash of CRT. */
561 psa_algorithm = mbedtls_md_psa_alg_from_type(ctx->md_alg);
562
563 status = psa_hash_compute(psa_algorithm,
564 c,
565 len,
566 hash,
567 sizeof(hash),
568 &hash_length);
569 if (status != PSA_SUCCESS) {
570 return MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED;
571 }
572
573
574 if ((ret = mbedtls_pk_sign(ctx->issuer_key, ctx->md_alg,
575 hash, hash_length, sig, sizeof(sig), &sig_len)) != 0) {
576 return ret;
577 }
578
579 /* Move CRT to the front of the buffer to have space
580 * for the signature. */
581 memmove(buf, c, len);
582 c = buf + len;
583
584 /* Add signature at the end of the buffer,
585 * making sure that it doesn't underflow
586 * into the CRT buffer. */
587 c2 = buf + size;
588 MBEDTLS_ASN1_CHK_ADD(sig_and_oid_len, mbedtls_x509_write_sig(&c2, c,
589 sig_oid, sig_oid_len,
590 sig, sig_len,
591 (mbedtls_pk_sigalg_t) pk_alg));
592
593 /*
594 * Memory layout after this step:
595 *
596 * buf c=buf+len c2 buf+size
597 * [CRT0,...,CRTn, UNUSED, ..., UNUSED, SIG0, ..., SIGm]
598 */
599
600 /* Move raw CRT to just before the signature. */
601 c = c2 - len;
602 memmove(c, buf, len);
603
604 len += sig_and_oid_len;
605 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
606 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf,
607 MBEDTLS_ASN1_CONSTRUCTED |
608 MBEDTLS_ASN1_SEQUENCE));
609
610 return (int) len;
611 }
612
613 #define PEM_BEGIN_CRT "-----BEGIN CERTIFICATE-----\n"
614 #define PEM_END_CRT "-----END CERTIFICATE-----\n"
615
616 #if defined(MBEDTLS_PEM_WRITE_C)
mbedtls_x509write_crt_pem(mbedtls_x509write_cert * crt,unsigned char * buf,size_t size)617 int mbedtls_x509write_crt_pem(mbedtls_x509write_cert *crt,
618 unsigned char *buf, size_t size)
619 {
620 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
621 size_t olen;
622
623 if ((ret = mbedtls_x509write_crt_der(crt, buf, size)) < 0) {
624 return ret;
625 }
626
627 if ((ret = mbedtls_pem_write_buffer(PEM_BEGIN_CRT, PEM_END_CRT,
628 buf + size - ret, ret,
629 buf, size, &olen)) != 0) {
630 return ret;
631 }
632
633 return 0;
634 }
635 #endif /* MBEDTLS_PEM_WRITE_C */
636
637 #endif /* MBEDTLS_X509_CRT_WRITE_C */
638