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 "common.h"
15
16 #if defined(MBEDTLS_X509_CRT_WRITE_C)
17
18 #include "mbedtls/x509_crt.h"
19 #include "x509_internal.h"
20 #include "mbedtls/asn1write.h"
21 #include "mbedtls/error.h"
22 #include "mbedtls/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 #if defined(MBEDTLS_USE_PSA_CRYPTO)
35 #include "psa/crypto.h"
36 #include "psa_util_internal.h"
37 #include "mbedtls/psa_util.h"
38 #endif /* MBEDTLS_USE_PSA_CRYPTO */
39
mbedtls_x509write_crt_init(mbedtls_x509write_cert * ctx)40 void mbedtls_x509write_crt_init(mbedtls_x509write_cert *ctx)
41 {
42 memset(ctx, 0, sizeof(mbedtls_x509write_cert));
43
44 ctx->version = MBEDTLS_X509_CRT_VERSION_3;
45 }
46
mbedtls_x509write_crt_free(mbedtls_x509write_cert * ctx)47 void mbedtls_x509write_crt_free(mbedtls_x509write_cert *ctx)
48 {
49 mbedtls_asn1_free_named_data_list(&ctx->subject);
50 mbedtls_asn1_free_named_data_list(&ctx->issuer);
51 mbedtls_asn1_free_named_data_list(&ctx->extensions);
52
53 mbedtls_platform_zeroize(ctx, sizeof(mbedtls_x509write_cert));
54 }
55
mbedtls_x509write_crt_set_version(mbedtls_x509write_cert * ctx,int version)56 void mbedtls_x509write_crt_set_version(mbedtls_x509write_cert *ctx,
57 int version)
58 {
59 ctx->version = version;
60 }
61
mbedtls_x509write_crt_set_md_alg(mbedtls_x509write_cert * ctx,mbedtls_md_type_t md_alg)62 void mbedtls_x509write_crt_set_md_alg(mbedtls_x509write_cert *ctx,
63 mbedtls_md_type_t md_alg)
64 {
65 ctx->md_alg = md_alg;
66 }
67
mbedtls_x509write_crt_set_subject_key(mbedtls_x509write_cert * ctx,mbedtls_pk_context * key)68 void mbedtls_x509write_crt_set_subject_key(mbedtls_x509write_cert *ctx,
69 mbedtls_pk_context *key)
70 {
71 ctx->subject_key = key;
72 }
73
mbedtls_x509write_crt_set_issuer_key(mbedtls_x509write_cert * ctx,mbedtls_pk_context * key)74 void mbedtls_x509write_crt_set_issuer_key(mbedtls_x509write_cert *ctx,
75 mbedtls_pk_context *key)
76 {
77 ctx->issuer_key = key;
78 }
79
mbedtls_x509write_crt_set_subject_name(mbedtls_x509write_cert * ctx,const char * subject_name)80 int mbedtls_x509write_crt_set_subject_name(mbedtls_x509write_cert *ctx,
81 const char *subject_name)
82 {
83 return mbedtls_x509_string_to_names(&ctx->subject, subject_name);
84 }
85
mbedtls_x509write_crt_set_issuer_name(mbedtls_x509write_cert * ctx,const char * issuer_name)86 int mbedtls_x509write_crt_set_issuer_name(mbedtls_x509write_cert *ctx,
87 const char *issuer_name)
88 {
89 return mbedtls_x509_string_to_names(&ctx->issuer, issuer_name);
90 }
91
92 #if defined(MBEDTLS_BIGNUM_C) && !defined(MBEDTLS_DEPRECATED_REMOVED)
mbedtls_x509write_crt_set_serial(mbedtls_x509write_cert * ctx,const mbedtls_mpi * serial)93 int mbedtls_x509write_crt_set_serial(mbedtls_x509write_cert *ctx,
94 const mbedtls_mpi *serial)
95 {
96 int ret;
97 size_t tmp_len;
98
99 /* Ensure that the MPI value fits into the buffer */
100 tmp_len = mbedtls_mpi_size(serial);
101 if (tmp_len > MBEDTLS_X509_RFC5280_MAX_SERIAL_LEN) {
102 return MBEDTLS_ERR_X509_BAD_INPUT_DATA;
103 }
104
105 ctx->serial_len = tmp_len;
106
107 ret = mbedtls_mpi_write_binary(serial, ctx->serial, tmp_len);
108 if (ret < 0) {
109 return ret;
110 }
111
112 return 0;
113 }
114 #endif // MBEDTLS_BIGNUM_C && !MBEDTLS_DEPRECATED_REMOVED
115
mbedtls_x509write_crt_set_serial_raw(mbedtls_x509write_cert * ctx,unsigned char * serial,size_t serial_len)116 int mbedtls_x509write_crt_set_serial_raw(mbedtls_x509write_cert *ctx,
117 unsigned char *serial, size_t serial_len)
118 {
119 if (serial_len > MBEDTLS_X509_RFC5280_MAX_SERIAL_LEN) {
120 return MBEDTLS_ERR_X509_BAD_INPUT_DATA;
121 }
122
123 ctx->serial_len = serial_len;
124 memcpy(ctx->serial, serial, serial_len);
125
126 return 0;
127 }
128
mbedtls_x509write_crt_set_validity(mbedtls_x509write_cert * ctx,const char * not_before,const char * not_after)129 int mbedtls_x509write_crt_set_validity(mbedtls_x509write_cert *ctx,
130 const char *not_before,
131 const char *not_after)
132 {
133 if (strlen(not_before) != MBEDTLS_X509_RFC5280_UTC_TIME_LEN - 1 ||
134 strlen(not_after) != MBEDTLS_X509_RFC5280_UTC_TIME_LEN - 1) {
135 return MBEDTLS_ERR_X509_BAD_INPUT_DATA;
136 }
137 strncpy(ctx->not_before, not_before, MBEDTLS_X509_RFC5280_UTC_TIME_LEN);
138 strncpy(ctx->not_after, not_after, MBEDTLS_X509_RFC5280_UTC_TIME_LEN);
139 ctx->not_before[MBEDTLS_X509_RFC5280_UTC_TIME_LEN - 1] = 'Z';
140 ctx->not_after[MBEDTLS_X509_RFC5280_UTC_TIME_LEN - 1] = 'Z';
141
142 return 0;
143 }
144
mbedtls_x509write_crt_set_subject_alternative_name(mbedtls_x509write_cert * ctx,const mbedtls_x509_san_list * san_list)145 int mbedtls_x509write_crt_set_subject_alternative_name(mbedtls_x509write_cert *ctx,
146 const mbedtls_x509_san_list *san_list)
147 {
148 return mbedtls_x509_write_set_san_common(&ctx->extensions, san_list);
149 }
150
151
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)152 int mbedtls_x509write_crt_set_extension(mbedtls_x509write_cert *ctx,
153 const char *oid, size_t oid_len,
154 int critical,
155 const unsigned char *val, size_t val_len)
156 {
157 return mbedtls_x509_set_extension(&ctx->extensions, oid, oid_len,
158 critical, val, val_len);
159 }
160
mbedtls_x509write_crt_set_basic_constraints(mbedtls_x509write_cert * ctx,int is_ca,int max_pathlen)161 int mbedtls_x509write_crt_set_basic_constraints(mbedtls_x509write_cert *ctx,
162 int is_ca, int max_pathlen)
163 {
164 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
165 unsigned char buf[9];
166 unsigned char *c = buf + sizeof(buf);
167 size_t len = 0;
168
169 memset(buf, 0, sizeof(buf));
170
171 if (is_ca && max_pathlen > 127) {
172 return MBEDTLS_ERR_X509_BAD_INPUT_DATA;
173 }
174
175 if (is_ca) {
176 if (max_pathlen >= 0) {
177 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_int(&c, buf,
178 max_pathlen));
179 }
180 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_bool(&c, buf, 1));
181 }
182
183 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
184 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf,
185 MBEDTLS_ASN1_CONSTRUCTED |
186 MBEDTLS_ASN1_SEQUENCE));
187
188 return
189 mbedtls_x509write_crt_set_extension(ctx, MBEDTLS_OID_BASIC_CONSTRAINTS,
190 MBEDTLS_OID_SIZE(MBEDTLS_OID_BASIC_CONSTRAINTS),
191 is_ca, buf + sizeof(buf) - len, len);
192 }
193
194 #if defined(MBEDTLS_MD_CAN_SHA1)
mbedtls_x509write_crt_set_key_identifier(mbedtls_x509write_cert * ctx,int is_ca,unsigned char tag)195 static int mbedtls_x509write_crt_set_key_identifier(mbedtls_x509write_cert *ctx,
196 int is_ca,
197 unsigned char tag)
198 {
199 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
200 unsigned char buf[MBEDTLS_MPI_MAX_SIZE * 2 + 20]; /* tag, length + 2xMPI */
201 unsigned char *c = buf + sizeof(buf);
202 size_t len = 0;
203 #if defined(MBEDTLS_USE_PSA_CRYPTO)
204 psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
205 size_t hash_length;
206 #endif /* MBEDTLS_USE_PSA_CRYPTO */
207
208 memset(buf, 0, sizeof(buf));
209 MBEDTLS_ASN1_CHK_ADD(len,
210 mbedtls_pk_write_pubkey(&c,
211 buf,
212 is_ca ?
213 ctx->issuer_key :
214 ctx->subject_key));
215
216
217 #if defined(MBEDTLS_USE_PSA_CRYPTO)
218 status = psa_hash_compute(PSA_ALG_SHA_1,
219 buf + sizeof(buf) - len,
220 len,
221 buf + sizeof(buf) - 20,
222 20,
223 &hash_length);
224 if (status != PSA_SUCCESS) {
225 return MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED;
226 }
227 #else
228 ret = mbedtls_md(mbedtls_md_info_from_type(MBEDTLS_MD_SHA1),
229 buf + sizeof(buf) - len, len,
230 buf + sizeof(buf) - 20);
231 if (ret != 0) {
232 return ret;
233 }
234 #endif /* MBEDTLS_USE_PSA_CRYPTO */
235
236 c = buf + sizeof(buf) - 20;
237 len = 20;
238
239 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
240 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf, tag));
241
242 if (is_ca) { // writes AuthorityKeyIdentifier sequence
243 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
244 MBEDTLS_ASN1_CHK_ADD(len,
245 mbedtls_asn1_write_tag(&c,
246 buf,
247 MBEDTLS_ASN1_CONSTRUCTED |
248 MBEDTLS_ASN1_SEQUENCE));
249 }
250
251 if (is_ca) {
252 return mbedtls_x509write_crt_set_extension(ctx,
253 MBEDTLS_OID_AUTHORITY_KEY_IDENTIFIER,
254 MBEDTLS_OID_SIZE(
255 MBEDTLS_OID_AUTHORITY_KEY_IDENTIFIER),
256 0, buf + sizeof(buf) - len, len);
257 } else {
258 return mbedtls_x509write_crt_set_extension(ctx,
259 MBEDTLS_OID_SUBJECT_KEY_IDENTIFIER,
260 MBEDTLS_OID_SIZE(
261 MBEDTLS_OID_SUBJECT_KEY_IDENTIFIER),
262 0, buf + sizeof(buf) - len, len);
263 }
264 }
265
mbedtls_x509write_crt_set_subject_key_identifier(mbedtls_x509write_cert * ctx)266 int mbedtls_x509write_crt_set_subject_key_identifier(mbedtls_x509write_cert *ctx)
267 {
268 return mbedtls_x509write_crt_set_key_identifier(ctx,
269 0,
270 MBEDTLS_ASN1_OCTET_STRING);
271 }
272
mbedtls_x509write_crt_set_authority_key_identifier(mbedtls_x509write_cert * ctx)273 int mbedtls_x509write_crt_set_authority_key_identifier(mbedtls_x509write_cert *ctx)
274 {
275 return mbedtls_x509write_crt_set_key_identifier(ctx,
276 1,
277 (MBEDTLS_ASN1_CONTEXT_SPECIFIC | 0));
278 }
279 #endif /* MBEDTLS_MD_CAN_SHA1 */
280
mbedtls_x509write_crt_set_key_usage(mbedtls_x509write_cert * ctx,unsigned int key_usage)281 int mbedtls_x509write_crt_set_key_usage(mbedtls_x509write_cert *ctx,
282 unsigned int key_usage)
283 {
284 unsigned char buf[5] = { 0 }, ku[2] = { 0 };
285 unsigned char *c;
286 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
287 const unsigned int allowed_bits = MBEDTLS_X509_KU_DIGITAL_SIGNATURE |
288 MBEDTLS_X509_KU_NON_REPUDIATION |
289 MBEDTLS_X509_KU_KEY_ENCIPHERMENT |
290 MBEDTLS_X509_KU_DATA_ENCIPHERMENT |
291 MBEDTLS_X509_KU_KEY_AGREEMENT |
292 MBEDTLS_X509_KU_KEY_CERT_SIGN |
293 MBEDTLS_X509_KU_CRL_SIGN |
294 MBEDTLS_X509_KU_ENCIPHER_ONLY |
295 MBEDTLS_X509_KU_DECIPHER_ONLY;
296
297 /* Check that nothing other than the allowed flags is set */
298 if ((key_usage & ~allowed_bits) != 0) {
299 return MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE;
300 }
301
302 c = buf + 5;
303 MBEDTLS_PUT_UINT16_LE(key_usage, ku, 0);
304 ret = mbedtls_asn1_write_named_bitstring(&c, buf, ku, 9);
305
306 if (ret < 0) {
307 return ret;
308 } else if (ret < 3 || ret > 5) {
309 return MBEDTLS_ERR_X509_INVALID_FORMAT;
310 }
311
312 ret = mbedtls_x509write_crt_set_extension(ctx, MBEDTLS_OID_KEY_USAGE,
313 MBEDTLS_OID_SIZE(MBEDTLS_OID_KEY_USAGE),
314 1, c, (size_t) ret);
315 if (ret != 0) {
316 return ret;
317 }
318
319 return 0;
320 }
321
mbedtls_x509write_crt_set_ext_key_usage(mbedtls_x509write_cert * ctx,const mbedtls_asn1_sequence * exts)322 int mbedtls_x509write_crt_set_ext_key_usage(mbedtls_x509write_cert *ctx,
323 const mbedtls_asn1_sequence *exts)
324 {
325 unsigned char buf[256];
326 unsigned char *c = buf + sizeof(buf);
327 int ret;
328 size_t len = 0;
329 const mbedtls_asn1_sequence *last_ext = NULL;
330 const mbedtls_asn1_sequence *ext;
331
332 memset(buf, 0, sizeof(buf));
333
334 /* We need at least one extension: SEQUENCE SIZE (1..MAX) OF KeyPurposeId */
335 if (exts == NULL) {
336 return MBEDTLS_ERR_X509_BAD_INPUT_DATA;
337 }
338
339 /* Iterate over exts backwards, so we write them out in the requested order */
340 while (last_ext != exts) {
341 for (ext = exts; ext->next != last_ext; ext = ext->next) {
342 }
343 if (ext->buf.tag != MBEDTLS_ASN1_OID) {
344 return MBEDTLS_ERR_X509_BAD_INPUT_DATA;
345 }
346 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(&c, buf, ext->buf.p, ext->buf.len));
347 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, ext->buf.len));
348 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_OID));
349 last_ext = ext;
350 }
351
352 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
353 MBEDTLS_ASN1_CHK_ADD(len,
354 mbedtls_asn1_write_tag(&c, buf,
355 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));
356
357 return mbedtls_x509write_crt_set_extension(ctx,
358 MBEDTLS_OID_EXTENDED_KEY_USAGE,
359 MBEDTLS_OID_SIZE(MBEDTLS_OID_EXTENDED_KEY_USAGE),
360 1, c, len);
361 }
362
mbedtls_x509write_crt_set_ns_cert_type(mbedtls_x509write_cert * ctx,unsigned char ns_cert_type)363 int mbedtls_x509write_crt_set_ns_cert_type(mbedtls_x509write_cert *ctx,
364 unsigned char ns_cert_type)
365 {
366 unsigned char buf[4] = { 0 };
367 unsigned char *c;
368 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
369
370 c = buf + 4;
371
372 ret = mbedtls_asn1_write_named_bitstring(&c, buf, &ns_cert_type, 8);
373 if (ret < 3 || ret > 4) {
374 return ret;
375 }
376
377 ret = mbedtls_x509write_crt_set_extension(ctx, MBEDTLS_OID_NS_CERT_TYPE,
378 MBEDTLS_OID_SIZE(MBEDTLS_OID_NS_CERT_TYPE),
379 0, c, (size_t) ret);
380 if (ret != 0) {
381 return ret;
382 }
383
384 return 0;
385 }
386
x509_write_time(unsigned char ** p,unsigned char * start,const char * t,size_t size)387 static int x509_write_time(unsigned char **p, unsigned char *start,
388 const char *t, size_t size)
389 {
390 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
391 size_t len = 0;
392
393 /*
394 * write MBEDTLS_ASN1_UTC_TIME if year < 2050 (2 bytes shorter)
395 */
396 if (t[0] < '2' || (t[0] == '2' && t[1] == '0' && t[2] < '5')) {
397 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start,
398 (const unsigned char *) t + 2,
399 size - 2));
400 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
401 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start,
402 MBEDTLS_ASN1_UTC_TIME));
403 } else {
404 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start,
405 (const unsigned char *) t,
406 size));
407 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
408 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start,
409 MBEDTLS_ASN1_GENERALIZED_TIME));
410 }
411
412 return (int) len;
413 }
414
mbedtls_x509write_crt_der(mbedtls_x509write_cert * ctx,unsigned char * buf,size_t size,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng)415 int mbedtls_x509write_crt_der(mbedtls_x509write_cert *ctx,
416 unsigned char *buf, size_t size,
417 int (*f_rng)(void *, unsigned char *, size_t),
418 void *p_rng)
419 {
420 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
421 const char *sig_oid;
422 size_t sig_oid_len = 0;
423 unsigned char *c, *c2;
424 unsigned char sig[MBEDTLS_PK_SIGNATURE_MAX_SIZE];
425 size_t hash_length = 0;
426 unsigned char hash[MBEDTLS_MD_MAX_SIZE];
427 #if defined(MBEDTLS_USE_PSA_CRYPTO)
428 psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
429 psa_algorithm_t psa_algorithm;
430 #endif /* MBEDTLS_USE_PSA_CRYPTO */
431
432 size_t sub_len = 0, pub_len = 0, sig_and_oid_len = 0, sig_len;
433 size_t len = 0;
434 mbedtls_pk_type_t pk_alg;
435 int write_sig_null_par;
436
437 /*
438 * Prepare data to be signed at the end of the target buffer
439 */
440 c = buf + size;
441
442 /* Signature algorithm needed in TBS, and later for actual signature */
443
444 /* There's no direct way of extracting a signature algorithm
445 * (represented as an element of mbedtls_pk_type_t) from a PK instance. */
446 if (mbedtls_pk_can_do(ctx->issuer_key, MBEDTLS_PK_RSA)) {
447 pk_alg = MBEDTLS_PK_RSA;
448 } else if (mbedtls_pk_can_do(ctx->issuer_key, MBEDTLS_PK_ECDSA)) {
449 pk_alg = MBEDTLS_PK_ECDSA;
450 } else {
451 return MBEDTLS_ERR_X509_INVALID_ALG;
452 }
453
454 if ((ret = mbedtls_oid_get_oid_by_sig_alg(pk_alg, ctx->md_alg,
455 &sig_oid, &sig_oid_len)) != 0) {
456 return ret;
457 }
458
459 /*
460 * Extensions ::= SEQUENCE SIZE (1..MAX) OF Extension
461 */
462
463 /* Only for v3 */
464 if (ctx->version == MBEDTLS_X509_CRT_VERSION_3) {
465 MBEDTLS_ASN1_CHK_ADD(len,
466 mbedtls_x509_write_extensions(&c,
467 buf, ctx->extensions));
468 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
469 MBEDTLS_ASN1_CHK_ADD(len,
470 mbedtls_asn1_write_tag(&c, buf,
471 MBEDTLS_ASN1_CONSTRUCTED |
472 MBEDTLS_ASN1_SEQUENCE));
473 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
474 MBEDTLS_ASN1_CHK_ADD(len,
475 mbedtls_asn1_write_tag(&c, buf,
476 MBEDTLS_ASN1_CONTEXT_SPECIFIC |
477 MBEDTLS_ASN1_CONSTRUCTED | 3));
478 }
479
480 /*
481 * SubjectPublicKeyInfo
482 */
483 MBEDTLS_ASN1_CHK_ADD(pub_len,
484 mbedtls_pk_write_pubkey_der(ctx->subject_key,
485 buf, (size_t) (c - buf)));
486 c -= pub_len;
487 len += pub_len;
488
489 /*
490 * Subject ::= Name
491 */
492 MBEDTLS_ASN1_CHK_ADD(len,
493 mbedtls_x509_write_names(&c, buf,
494 ctx->subject));
495
496 /*
497 * Validity ::= SEQUENCE {
498 * notBefore Time,
499 * notAfter Time }
500 */
501 sub_len = 0;
502
503 MBEDTLS_ASN1_CHK_ADD(sub_len,
504 x509_write_time(&c, buf, ctx->not_after,
505 MBEDTLS_X509_RFC5280_UTC_TIME_LEN));
506
507 MBEDTLS_ASN1_CHK_ADD(sub_len,
508 x509_write_time(&c, buf, ctx->not_before,
509 MBEDTLS_X509_RFC5280_UTC_TIME_LEN));
510
511 len += sub_len;
512 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, sub_len));
513 MBEDTLS_ASN1_CHK_ADD(len,
514 mbedtls_asn1_write_tag(&c, buf,
515 MBEDTLS_ASN1_CONSTRUCTED |
516 MBEDTLS_ASN1_SEQUENCE));
517
518 /*
519 * Issuer ::= Name
520 */
521 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_x509_write_names(&c, buf,
522 ctx->issuer));
523
524 /*
525 * Signature ::= AlgorithmIdentifier
526 */
527 if (pk_alg == MBEDTLS_PK_ECDSA) {
528 /*
529 * The AlgorithmIdentifier's parameters field must be absent for DSA/ECDSA signature
530 * algorithms, see https://www.rfc-editor.org/rfc/rfc5480#page-17 and
531 * https://www.rfc-editor.org/rfc/rfc5758#section-3.
532 */
533 write_sig_null_par = 0;
534 } else {
535 write_sig_null_par = 1;
536 }
537 MBEDTLS_ASN1_CHK_ADD(len,
538 mbedtls_asn1_write_algorithm_identifier_ext(&c, buf,
539 sig_oid, strlen(sig_oid),
540 0, write_sig_null_par));
541
542 /*
543 * Serial ::= INTEGER
544 *
545 * Written data is:
546 * - "ctx->serial_len" bytes for the raw serial buffer
547 * - if MSb of "serial" is 1, then prepend an extra 0x00 byte
548 * - 1 byte for the length
549 * - 1 byte for the TAG
550 */
551 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(&c, buf,
552 ctx->serial, ctx->serial_len));
553 if (*c & 0x80) {
554 if (c - buf < 1) {
555 return MBEDTLS_ERR_X509_BUFFER_TOO_SMALL;
556 }
557 *(--c) = 0x0;
558 len++;
559 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf,
560 ctx->serial_len + 1));
561 } else {
562 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf,
563 ctx->serial_len));
564 }
565 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf,
566 MBEDTLS_ASN1_INTEGER));
567
568 /*
569 * Version ::= INTEGER { v1(0), v2(1), v3(2) }
570 */
571
572 /* Can be omitted for v1 */
573 if (ctx->version != MBEDTLS_X509_CRT_VERSION_1) {
574 sub_len = 0;
575 MBEDTLS_ASN1_CHK_ADD(sub_len,
576 mbedtls_asn1_write_int(&c, buf, ctx->version));
577 len += sub_len;
578 MBEDTLS_ASN1_CHK_ADD(len,
579 mbedtls_asn1_write_len(&c, buf, sub_len));
580 MBEDTLS_ASN1_CHK_ADD(len,
581 mbedtls_asn1_write_tag(&c, buf,
582 MBEDTLS_ASN1_CONTEXT_SPECIFIC |
583 MBEDTLS_ASN1_CONSTRUCTED | 0));
584 }
585
586 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
587 MBEDTLS_ASN1_CHK_ADD(len,
588 mbedtls_asn1_write_tag(&c, buf, MBEDTLS_ASN1_CONSTRUCTED |
589 MBEDTLS_ASN1_SEQUENCE));
590
591 /*
592 * Make signature
593 */
594
595 /* Compute hash of CRT. */
596 #if defined(MBEDTLS_USE_PSA_CRYPTO)
597 psa_algorithm = mbedtls_md_psa_alg_from_type(ctx->md_alg);
598
599 status = psa_hash_compute(psa_algorithm,
600 c,
601 len,
602 hash,
603 sizeof(hash),
604 &hash_length);
605 if (status != PSA_SUCCESS) {
606 return MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED;
607 }
608 #else
609 if ((ret = mbedtls_md(mbedtls_md_info_from_type(ctx->md_alg), c,
610 len, hash)) != 0) {
611 return ret;
612 }
613 #endif /* MBEDTLS_USE_PSA_CRYPTO */
614
615
616 if ((ret = mbedtls_pk_sign(ctx->issuer_key, ctx->md_alg,
617 hash, hash_length, sig, sizeof(sig), &sig_len,
618 f_rng, p_rng)) != 0) {
619 return ret;
620 }
621
622 /* Move CRT to the front of the buffer to have space
623 * for the signature. */
624 memmove(buf, c, len);
625 c = buf + len;
626
627 /* Add signature at the end of the buffer,
628 * making sure that it doesn't underflow
629 * into the CRT buffer. */
630 c2 = buf + size;
631 MBEDTLS_ASN1_CHK_ADD(sig_and_oid_len, mbedtls_x509_write_sig(&c2, c,
632 sig_oid, sig_oid_len,
633 sig, sig_len, pk_alg));
634
635 /*
636 * Memory layout after this step:
637 *
638 * buf c=buf+len c2 buf+size
639 * [CRT0,...,CRTn, UNUSED, ..., UNUSED, SIG0, ..., SIGm]
640 */
641
642 /* Move raw CRT to just before the signature. */
643 c = c2 - len;
644 memmove(c, buf, len);
645
646 len += sig_and_oid_len;
647 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
648 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&c, buf,
649 MBEDTLS_ASN1_CONSTRUCTED |
650 MBEDTLS_ASN1_SEQUENCE));
651
652 return (int) len;
653 }
654
655 #define PEM_BEGIN_CRT "-----BEGIN CERTIFICATE-----\n"
656 #define PEM_END_CRT "-----END CERTIFICATE-----\n"
657
658 #if defined(MBEDTLS_PEM_WRITE_C)
mbedtls_x509write_crt_pem(mbedtls_x509write_cert * crt,unsigned char * buf,size_t size,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng)659 int mbedtls_x509write_crt_pem(mbedtls_x509write_cert *crt,
660 unsigned char *buf, size_t size,
661 int (*f_rng)(void *, unsigned char *, size_t),
662 void *p_rng)
663 {
664 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
665 size_t olen;
666
667 if ((ret = mbedtls_x509write_crt_der(crt, buf, size,
668 f_rng, p_rng)) < 0) {
669 return ret;
670 }
671
672 if ((ret = mbedtls_pem_write_buffer(PEM_BEGIN_CRT, PEM_END_CRT,
673 buf + size - ret, ret,
674 buf, size, &olen)) != 0) {
675 return ret;
676 }
677
678 return 0;
679 }
680 #endif /* MBEDTLS_PEM_WRITE_C */
681
682 #endif /* MBEDTLS_X509_CRT_WRITE_C */
683
