1 /*
2 * X.509 Certificate Signing Request writing
3 *
4 * Copyright The Mbed TLS Contributors
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 /*
20 * References:
21 * - CSRs: PKCS#10 v1.7 aka RFC 2986
22 * - attributes: PKCS#9 v2.0 aka RFC 2985
23 */
24
25 #include "common.h"
26
27 #if defined(MBEDTLS_X509_CSR_WRITE_C)
28
29 #include "mbedtls/x509.h"
30 #include "mbedtls/x509_csr.h"
31 #include "mbedtls/asn1write.h"
32 #include "mbedtls/error.h"
33 #include "mbedtls/oid.h"
34 #include "mbedtls/platform_util.h"
35
36 #if defined(MBEDTLS_USE_PSA_CRYPTO)
37 #include "psa/crypto.h"
38 #include "mbedtls/psa_util.h"
39 #endif /* MBEDTLS_USE_PSA_CRYPTO */
40 #include "hash_info.h"
41
42 #include <string.h>
43 #include <stdlib.h>
44
45 #if defined(MBEDTLS_PEM_WRITE_C)
46 #include "mbedtls/pem.h"
47 #endif
48
49 #include "mbedtls/platform.h"
50
mbedtls_x509write_csr_init(mbedtls_x509write_csr * ctx)51 void mbedtls_x509write_csr_init(mbedtls_x509write_csr *ctx)
52 {
53 memset(ctx, 0, sizeof(mbedtls_x509write_csr));
54 }
55
mbedtls_x509write_csr_free(mbedtls_x509write_csr * ctx)56 void mbedtls_x509write_csr_free(mbedtls_x509write_csr *ctx)
57 {
58 mbedtls_asn1_free_named_data_list(&ctx->subject);
59 mbedtls_asn1_free_named_data_list(&ctx->extensions);
60
61 mbedtls_platform_zeroize(ctx, sizeof(mbedtls_x509write_csr));
62 }
63
mbedtls_x509write_csr_set_md_alg(mbedtls_x509write_csr * ctx,mbedtls_md_type_t md_alg)64 void mbedtls_x509write_csr_set_md_alg(mbedtls_x509write_csr *ctx, mbedtls_md_type_t md_alg)
65 {
66 ctx->md_alg = md_alg;
67 }
68
mbedtls_x509write_csr_set_key(mbedtls_x509write_csr * ctx,mbedtls_pk_context * key)69 void mbedtls_x509write_csr_set_key(mbedtls_x509write_csr *ctx, mbedtls_pk_context *key)
70 {
71 ctx->key = key;
72 }
73
mbedtls_x509write_csr_set_subject_name(mbedtls_x509write_csr * ctx,const char * subject_name)74 int mbedtls_x509write_csr_set_subject_name(mbedtls_x509write_csr *ctx,
75 const char *subject_name)
76 {
77 return mbedtls_x509_string_to_names(&ctx->subject, subject_name);
78 }
79
mbedtls_x509write_csr_set_extension(mbedtls_x509write_csr * ctx,const char * oid,size_t oid_len,int critical,const unsigned char * val,size_t val_len)80 int mbedtls_x509write_csr_set_extension(mbedtls_x509write_csr *ctx,
81 const char *oid, size_t oid_len,
82 int critical,
83 const unsigned char *val, size_t val_len)
84 {
85 return mbedtls_x509_set_extension(&ctx->extensions, oid, oid_len,
86 critical, val, val_len);
87 }
88
mbedtls_x509write_csr_set_subject_alternative_name(mbedtls_x509write_csr * ctx,const mbedtls_x509_san_list * san_list)89 int mbedtls_x509write_csr_set_subject_alternative_name(mbedtls_x509write_csr *ctx,
90 const mbedtls_x509_san_list *san_list)
91 {
92 int ret = 0;
93 const mbedtls_x509_san_list *cur;
94 unsigned char *buf;
95 unsigned char *p;
96 size_t len;
97 size_t buflen = 0;
98
99 /* Determine the maximum size of the SubjectAltName list */
100 for (cur = san_list; cur != NULL; cur = cur->next) {
101 /* Calculate size of the required buffer */
102 switch (cur->node.type) {
103 case MBEDTLS_X509_SAN_DNS_NAME:
104 case MBEDTLS_X509_SAN_UNIFORM_RESOURCE_IDENTIFIER:
105 case MBEDTLS_X509_SAN_IP_ADDRESS:
106 /* length of value for each name entry,
107 * maximum 4 bytes for the length field,
108 * 1 byte for the tag/type.
109 */
110 buflen += cur->node.san.unstructured_name.len + 4 + 1;
111 break;
112
113 default:
114 /* Not supported - skip. */
115 break;
116 }
117 }
118
119 /* Add the extra length field and tag */
120 buflen += 4 + 1;
121
122 /* Allocate buffer */
123 buf = mbedtls_calloc(1, buflen);
124 if (buf == NULL) {
125 return MBEDTLS_ERR_ASN1_ALLOC_FAILED;
126 }
127
128 mbedtls_platform_zeroize(buf, buflen);
129 p = buf + buflen;
130
131 /* Write ASN.1-based structure */
132 cur = san_list;
133 len = 0;
134 while (cur != NULL) {
135 switch (cur->node.type) {
136 case MBEDTLS_X509_SAN_DNS_NAME:
137 case MBEDTLS_X509_SAN_UNIFORM_RESOURCE_IDENTIFIER:
138 case MBEDTLS_X509_SAN_IP_ADDRESS:
139 {
140 const unsigned char *unstructured_name =
141 (const unsigned char *) cur->node.san.unstructured_name.p;
142 size_t unstructured_name_len = cur->node.san.unstructured_name.len;
143
144 MBEDTLS_ASN1_CHK_CLEANUP_ADD(len,
145 mbedtls_asn1_write_raw_buffer(
146 &p, buf,
147 unstructured_name, unstructured_name_len));
148 MBEDTLS_ASN1_CHK_CLEANUP_ADD(len, mbedtls_asn1_write_len(
149 &p, buf, unstructured_name_len));
150 MBEDTLS_ASN1_CHK_CLEANUP_ADD(len,
151 mbedtls_asn1_write_tag(
152 &p, buf,
153 MBEDTLS_ASN1_CONTEXT_SPECIFIC | cur->node.type));
154 }
155 break;
156 default:
157 /* Skip unsupported names. */
158 break;
159 }
160 cur = cur->next;
161 }
162
163 MBEDTLS_ASN1_CHK_CLEANUP_ADD(len, mbedtls_asn1_write_len(&p, buf, len));
164 MBEDTLS_ASN1_CHK_CLEANUP_ADD(len,
165 mbedtls_asn1_write_tag(&p, buf,
166 MBEDTLS_ASN1_CONSTRUCTED |
167 MBEDTLS_ASN1_SEQUENCE));
168
169 ret = mbedtls_x509write_csr_set_extension(
170 ctx,
171 MBEDTLS_OID_SUBJECT_ALT_NAME,
172 MBEDTLS_OID_SIZE(MBEDTLS_OID_SUBJECT_ALT_NAME),
173 0,
174 buf + buflen - len,
175 len);
176
177 /* If we exceeded the allocated buffer it means that maximum size of the SubjectAltName list
178 * was incorrectly calculated and memory is corrupted. */
179 if (p < buf) {
180 ret = MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
181 }
182
183 cleanup:
184 mbedtls_free(buf);
185 return ret;
186 }
187
mbedtls_x509write_csr_set_key_usage(mbedtls_x509write_csr * ctx,unsigned char key_usage)188 int mbedtls_x509write_csr_set_key_usage(mbedtls_x509write_csr *ctx, unsigned char key_usage)
189 {
190 unsigned char buf[4] = { 0 };
191 unsigned char *c;
192 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
193
194 c = buf + 4;
195
196 ret = mbedtls_asn1_write_named_bitstring(&c, buf, &key_usage, 8);
197 if (ret < 3 || ret > 4) {
198 return ret;
199 }
200
201 ret = mbedtls_x509write_csr_set_extension(ctx, MBEDTLS_OID_KEY_USAGE,
202 MBEDTLS_OID_SIZE(MBEDTLS_OID_KEY_USAGE),
203 0, c, (size_t) ret);
204 if (ret != 0) {
205 return ret;
206 }
207
208 return 0;
209 }
210
mbedtls_x509write_csr_set_ns_cert_type(mbedtls_x509write_csr * ctx,unsigned char ns_cert_type)211 int mbedtls_x509write_csr_set_ns_cert_type(mbedtls_x509write_csr *ctx,
212 unsigned char ns_cert_type)
213 {
214 unsigned char buf[4] = { 0 };
215 unsigned char *c;
216 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
217
218 c = buf + 4;
219
220 ret = mbedtls_asn1_write_named_bitstring(&c, buf, &ns_cert_type, 8);
221 if (ret < 3 || ret > 4) {
222 return ret;
223 }
224
225 ret = mbedtls_x509write_csr_set_extension(ctx, MBEDTLS_OID_NS_CERT_TYPE,
226 MBEDTLS_OID_SIZE(MBEDTLS_OID_NS_CERT_TYPE),
227 0, c, (size_t) ret);
228 if (ret != 0) {
229 return ret;
230 }
231
232 return 0;
233 }
234
x509write_csr_der_internal(mbedtls_x509write_csr * ctx,unsigned char * buf,size_t size,unsigned char * sig,size_t sig_size,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng)235 static int x509write_csr_der_internal(mbedtls_x509write_csr *ctx,
236 unsigned char *buf,
237 size_t size,
238 unsigned char *sig, size_t sig_size,
239 int (*f_rng)(void *, unsigned char *, size_t),
240 void *p_rng)
241 {
242 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
243 const char *sig_oid;
244 size_t sig_oid_len = 0;
245 unsigned char *c, *c2;
246 unsigned char hash[MBEDTLS_HASH_MAX_SIZE];
247 size_t pub_len = 0, sig_and_oid_len = 0, sig_len;
248 size_t len = 0;
249 mbedtls_pk_type_t pk_alg;
250 #if defined(MBEDTLS_USE_PSA_CRYPTO)
251 size_t hash_len;
252 psa_algorithm_t hash_alg = mbedtls_hash_info_psa_from_md(ctx->md_alg);
253 #endif /* MBEDTLS_USE_PSA_CRYPTO */
254
255 /* Write the CSR backwards starting from the end of buf */
256 c = buf + size;
257
258 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_x509_write_extensions(&c, buf,
259 ctx->extensions));
260
261 if (len) {
262 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
263 MBEDTLS_ASN1_CHK_ADD(len,
264 mbedtls_asn1_write_tag(
265 &c, buf,
266 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));
267
268 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
269 MBEDTLS_ASN1_CHK_ADD(len,
270 mbedtls_asn1_write_tag(
271 &c, buf,
272 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SET));
273
274 MBEDTLS_ASN1_CHK_ADD(len,
275 mbedtls_asn1_write_oid(
276 &c, buf, MBEDTLS_OID_PKCS9_CSR_EXT_REQ,
277 MBEDTLS_OID_SIZE(MBEDTLS_OID_PKCS9_CSR_EXT_REQ)));
278
279 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
280 MBEDTLS_ASN1_CHK_ADD(len,
281 mbedtls_asn1_write_tag(
282 &c, buf,
283 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));
284 }
285
286 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
287 MBEDTLS_ASN1_CHK_ADD(len,
288 mbedtls_asn1_write_tag(
289 &c, buf,
290 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC));
291
292 MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_pk_write_pubkey_der(ctx->key,
293 buf, c - buf));
294 c -= pub_len;
295 len += pub_len;
296
297 /*
298 * Subject ::= Name
299 */
300 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_x509_write_names(&c, buf,
301 ctx->subject));
302
303 /*
304 * Version ::= INTEGER { v1(0), v2(1), v3(2) }
305 */
306 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_int(&c, buf, 0));
307
308 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
309 MBEDTLS_ASN1_CHK_ADD(len,
310 mbedtls_asn1_write_tag(
311 &c, buf,
312 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));
313
314 /*
315 * Sign the written CSR data into the sig buffer
316 * Note: hash errors can happen only after an internal error
317 */
318 #if defined(MBEDTLS_USE_PSA_CRYPTO)
319 if (psa_hash_compute(hash_alg,
320 c,
321 len,
322 hash,
323 sizeof(hash),
324 &hash_len) != PSA_SUCCESS) {
325 return MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED;
326 }
327 #else /* MBEDTLS_USE_PSA_CRYPTO */
328 ret = mbedtls_md(mbedtls_md_info_from_type(ctx->md_alg), c, len, hash);
329 if (ret != 0) {
330 return ret;
331 }
332 #endif
333 if ((ret = mbedtls_pk_sign(ctx->key, ctx->md_alg, hash, 0,
334 sig, sig_size, &sig_len,
335 f_rng, p_rng)) != 0) {
336 return ret;
337 }
338
339 if (mbedtls_pk_can_do(ctx->key, MBEDTLS_PK_RSA)) {
340 pk_alg = MBEDTLS_PK_RSA;
341 } else if (mbedtls_pk_can_do(ctx->key, MBEDTLS_PK_ECDSA)) {
342 pk_alg = MBEDTLS_PK_ECDSA;
343 } else {
344 return MBEDTLS_ERR_X509_INVALID_ALG;
345 }
346
347 if ((ret = mbedtls_oid_get_oid_by_sig_alg(pk_alg, ctx->md_alg,
348 &sig_oid, &sig_oid_len)) != 0) {
349 return ret;
350 }
351
352 /*
353 * Move the written CSR data to the start of buf to create space for
354 * writing the signature into buf.
355 */
356 memmove(buf, c, len);
357
358 /*
359 * Write sig and its OID into buf backwards from the end of buf.
360 * Note: mbedtls_x509_write_sig will check for c2 - ( buf + len ) < sig_len
361 * and return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL if needed.
362 */
363 c2 = buf + size;
364 MBEDTLS_ASN1_CHK_ADD(sig_and_oid_len,
365 mbedtls_x509_write_sig(&c2, buf + len, sig_oid, sig_oid_len,
366 sig, sig_len));
367
368 /*
369 * Compact the space between the CSR data and signature by moving the
370 * CSR data to the start of the signature.
371 */
372 c2 -= len;
373 memmove(c2, buf, len);
374
375 /* ASN encode the total size and tag the CSR data with it. */
376 len += sig_and_oid_len;
377 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c2, buf, len));
378 MBEDTLS_ASN1_CHK_ADD(len,
379 mbedtls_asn1_write_tag(
380 &c2, buf,
381 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));
382
383 /* Zero the unused bytes at the start of buf */
384 memset(buf, 0, c2 - buf);
385
386 return (int) len;
387 }
388
mbedtls_x509write_csr_der(mbedtls_x509write_csr * ctx,unsigned char * buf,size_t size,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng)389 int mbedtls_x509write_csr_der(mbedtls_x509write_csr *ctx, unsigned char *buf,
390 size_t size,
391 int (*f_rng)(void *, unsigned char *, size_t),
392 void *p_rng)
393 {
394 int ret;
395 unsigned char *sig;
396
397 if ((sig = mbedtls_calloc(1, MBEDTLS_PK_SIGNATURE_MAX_SIZE)) == NULL) {
398 return MBEDTLS_ERR_X509_ALLOC_FAILED;
399 }
400
401 ret = x509write_csr_der_internal(ctx, buf, size,
402 sig, MBEDTLS_PK_SIGNATURE_MAX_SIZE,
403 f_rng, p_rng);
404
405 mbedtls_free(sig);
406
407 return ret;
408 }
409
410 #define PEM_BEGIN_CSR "-----BEGIN CERTIFICATE REQUEST-----\n"
411 #define PEM_END_CSR "-----END CERTIFICATE REQUEST-----\n"
412
413 #if defined(MBEDTLS_PEM_WRITE_C)
mbedtls_x509write_csr_pem(mbedtls_x509write_csr * ctx,unsigned char * buf,size_t size,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng)414 int mbedtls_x509write_csr_pem(mbedtls_x509write_csr *ctx, unsigned char *buf, size_t size,
415 int (*f_rng)(void *, unsigned char *, size_t),
416 void *p_rng)
417 {
418 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
419 size_t olen = 0;
420
421 if ((ret = mbedtls_x509write_csr_der(ctx, buf, size,
422 f_rng, p_rng)) < 0) {
423 return ret;
424 }
425
426 if ((ret = mbedtls_pem_write_buffer(PEM_BEGIN_CSR, PEM_END_CSR,
427 buf + size - ret,
428 ret, buf, size, &olen)) != 0) {
429 return ret;
430 }
431
432 return 0;
433 }
434 #endif /* MBEDTLS_PEM_WRITE_C */
435
436 #endif /* MBEDTLS_X509_CSR_WRITE_C */
437