1 /*
2 * X.509 Certificate Signing Request 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 * - CSRs: PKCS#10 v1.7 aka RFC 2986
10 * - attributes: PKCS#9 v2.0 aka RFC 2985
11 */
12
13 #include "common.h"
14
15 #if defined(MBEDTLS_X509_CSR_WRITE_C)
16
17 #include "x509_internal.h"
18 #include "mbedtls/x509_csr.h"
19 #include "mbedtls/asn1write.h"
20 #include "mbedtls/error.h"
21 #include "mbedtls/oid.h"
22 #include "mbedtls/platform_util.h"
23
24 #if defined(MBEDTLS_USE_PSA_CRYPTO)
25 #include "psa/crypto.h"
26 #include "psa_util_internal.h"
27 #include "mbedtls/psa_util.h"
28 #endif /* MBEDTLS_USE_PSA_CRYPTO */
29
30 #include <string.h>
31 #include <stdlib.h>
32
33 #if defined(MBEDTLS_PEM_WRITE_C)
34 #include "mbedtls/pem.h"
35 #endif
36
37 #include "mbedtls/platform.h"
38
mbedtls_x509write_csr_init(mbedtls_x509write_csr * ctx)39 void mbedtls_x509write_csr_init(mbedtls_x509write_csr *ctx)
40 {
41 memset(ctx, 0, sizeof(mbedtls_x509write_csr));
42 }
43
mbedtls_x509write_csr_free(mbedtls_x509write_csr * ctx)44 void mbedtls_x509write_csr_free(mbedtls_x509write_csr *ctx)
45 {
46 if (ctx == NULL) {
47 return;
48 }
49
50 mbedtls_asn1_free_named_data_list(&ctx->subject);
51 mbedtls_asn1_free_named_data_list(&ctx->extensions);
52
53 mbedtls_platform_zeroize(ctx, sizeof(mbedtls_x509write_csr));
54 }
55
mbedtls_x509write_csr_set_md_alg(mbedtls_x509write_csr * ctx,mbedtls_md_type_t md_alg)56 void mbedtls_x509write_csr_set_md_alg(mbedtls_x509write_csr *ctx, mbedtls_md_type_t md_alg)
57 {
58 ctx->md_alg = md_alg;
59 }
60
mbedtls_x509write_csr_set_key(mbedtls_x509write_csr * ctx,mbedtls_pk_context * key)61 void mbedtls_x509write_csr_set_key(mbedtls_x509write_csr *ctx, mbedtls_pk_context *key)
62 {
63 ctx->key = key;
64 }
65
mbedtls_x509write_csr_set_subject_name(mbedtls_x509write_csr * ctx,const char * subject_name)66 int mbedtls_x509write_csr_set_subject_name(mbedtls_x509write_csr *ctx,
67 const char *subject_name)
68 {
69 mbedtls_asn1_free_named_data_list(&ctx->subject);
70 return mbedtls_x509_string_to_names(&ctx->subject, subject_name);
71 }
72
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)73 int mbedtls_x509write_csr_set_extension(mbedtls_x509write_csr *ctx,
74 const char *oid, size_t oid_len,
75 int critical,
76 const unsigned char *val, size_t val_len)
77 {
78 return mbedtls_x509_set_extension(&ctx->extensions, oid, oid_len,
79 critical, val, val_len);
80 }
81
mbedtls_x509write_csr_set_subject_alternative_name(mbedtls_x509write_csr * ctx,const mbedtls_x509_san_list * san_list)82 int mbedtls_x509write_csr_set_subject_alternative_name(mbedtls_x509write_csr *ctx,
83 const mbedtls_x509_san_list *san_list)
84 {
85 return mbedtls_x509_write_set_san_common(&ctx->extensions, san_list);
86 }
87
mbedtls_x509write_csr_set_key_usage(mbedtls_x509write_csr * ctx,unsigned char key_usage)88 int mbedtls_x509write_csr_set_key_usage(mbedtls_x509write_csr *ctx, unsigned char key_usage)
89 {
90 unsigned char buf[4] = { 0 };
91 unsigned char *c;
92 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
93
94 c = buf + 4;
95
96 ret = mbedtls_asn1_write_named_bitstring(&c, buf, &key_usage, 8);
97 if (ret < 3 || ret > 4) {
98 return ret;
99 }
100
101 ret = mbedtls_x509write_csr_set_extension(ctx, MBEDTLS_OID_KEY_USAGE,
102 MBEDTLS_OID_SIZE(MBEDTLS_OID_KEY_USAGE),
103 0, c, (size_t) ret);
104 if (ret != 0) {
105 return ret;
106 }
107
108 return 0;
109 }
110
mbedtls_x509write_csr_set_ns_cert_type(mbedtls_x509write_csr * ctx,unsigned char ns_cert_type)111 int mbedtls_x509write_csr_set_ns_cert_type(mbedtls_x509write_csr *ctx,
112 unsigned char ns_cert_type)
113 {
114 unsigned char buf[4] = { 0 };
115 unsigned char *c;
116 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
117
118 c = buf + 4;
119
120 ret = mbedtls_asn1_write_named_bitstring(&c, buf, &ns_cert_type, 8);
121 if (ret < 3 || ret > 4) {
122 return ret;
123 }
124
125 ret = mbedtls_x509write_csr_set_extension(ctx, MBEDTLS_OID_NS_CERT_TYPE,
126 MBEDTLS_OID_SIZE(MBEDTLS_OID_NS_CERT_TYPE),
127 0, c, (size_t) ret);
128 if (ret != 0) {
129 return ret;
130 }
131
132 return 0;
133 }
134
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)135 static int x509write_csr_der_internal(mbedtls_x509write_csr *ctx,
136 unsigned char *buf,
137 size_t size,
138 unsigned char *sig, size_t sig_size,
139 int (*f_rng)(void *, unsigned char *, size_t),
140 void *p_rng)
141 {
142 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
143 const char *sig_oid;
144 size_t sig_oid_len = 0;
145 unsigned char *c, *c2;
146 unsigned char hash[MBEDTLS_MD_MAX_SIZE];
147 size_t pub_len = 0, sig_and_oid_len = 0, sig_len;
148 size_t len = 0;
149 mbedtls_pk_type_t pk_alg;
150 #if defined(MBEDTLS_USE_PSA_CRYPTO)
151 size_t hash_len;
152 psa_algorithm_t hash_alg = mbedtls_md_psa_alg_from_type(ctx->md_alg);
153 #endif /* MBEDTLS_USE_PSA_CRYPTO */
154
155 /* Write the CSR backwards starting from the end of buf */
156 c = buf + size;
157
158 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_x509_write_extensions(&c, buf,
159 ctx->extensions));
160
161 if (len) {
162 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
163 MBEDTLS_ASN1_CHK_ADD(len,
164 mbedtls_asn1_write_tag(
165 &c, buf,
166 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));
167
168 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
169 MBEDTLS_ASN1_CHK_ADD(len,
170 mbedtls_asn1_write_tag(
171 &c, buf,
172 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SET));
173
174 MBEDTLS_ASN1_CHK_ADD(len,
175 mbedtls_asn1_write_oid(
176 &c, buf, MBEDTLS_OID_PKCS9_CSR_EXT_REQ,
177 MBEDTLS_OID_SIZE(MBEDTLS_OID_PKCS9_CSR_EXT_REQ)));
178
179 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
180 MBEDTLS_ASN1_CHK_ADD(len,
181 mbedtls_asn1_write_tag(
182 &c, buf,
183 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));
184 }
185
186 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
187 MBEDTLS_ASN1_CHK_ADD(len,
188 mbedtls_asn1_write_tag(
189 &c, buf,
190 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC));
191
192 MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_pk_write_pubkey_der(ctx->key,
193 buf, (size_t) (c - buf)));
194 c -= pub_len;
195 len += pub_len;
196
197 /*
198 * Subject ::= Name
199 */
200 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_x509_write_names(&c, buf,
201 ctx->subject));
202
203 /*
204 * Version ::= INTEGER { v1(0), v2(1), v3(2) }
205 */
206 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_int(&c, buf, 0));
207
208 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
209 MBEDTLS_ASN1_CHK_ADD(len,
210 mbedtls_asn1_write_tag(
211 &c, buf,
212 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));
213
214 /*
215 * Sign the written CSR data into the sig buffer
216 * Note: hash errors can happen only after an internal error
217 */
218 #if defined(MBEDTLS_USE_PSA_CRYPTO)
219 if (psa_hash_compute(hash_alg,
220 c,
221 len,
222 hash,
223 sizeof(hash),
224 &hash_len) != PSA_SUCCESS) {
225 return MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED;
226 }
227 #else /* MBEDTLS_USE_PSA_CRYPTO */
228 ret = mbedtls_md(mbedtls_md_info_from_type(ctx->md_alg), c, len, hash);
229 if (ret != 0) {
230 return ret;
231 }
232 #endif
233 if ((ret = mbedtls_pk_sign(ctx->key, ctx->md_alg, hash, 0,
234 sig, sig_size, &sig_len,
235 f_rng, p_rng)) != 0) {
236 return ret;
237 }
238
239 if (mbedtls_pk_can_do(ctx->key, MBEDTLS_PK_RSA)) {
240 pk_alg = MBEDTLS_PK_RSA;
241 } else if (mbedtls_pk_can_do(ctx->key, MBEDTLS_PK_ECDSA)) {
242 pk_alg = MBEDTLS_PK_ECDSA;
243 } else {
244 return MBEDTLS_ERR_X509_INVALID_ALG;
245 }
246
247 if ((ret = mbedtls_oid_get_oid_by_sig_alg(pk_alg, ctx->md_alg,
248 &sig_oid, &sig_oid_len)) != 0) {
249 return ret;
250 }
251
252 /*
253 * Move the written CSR data to the start of buf to create space for
254 * writing the signature into buf.
255 */
256 memmove(buf, c, len);
257
258 /*
259 * Write sig and its OID into buf backwards from the end of buf.
260 * Note: mbedtls_x509_write_sig will check for c2 - ( buf + len ) < sig_len
261 * and return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL if needed.
262 */
263 c2 = buf + size;
264 MBEDTLS_ASN1_CHK_ADD(sig_and_oid_len,
265 mbedtls_x509_write_sig(&c2, buf + len, sig_oid, sig_oid_len,
266 sig, sig_len, pk_alg));
267
268 /*
269 * Compact the space between the CSR data and signature by moving the
270 * CSR data to the start of the signature.
271 */
272 c2 -= len;
273 memmove(c2, buf, len);
274
275 /* ASN encode the total size and tag the CSR data with it. */
276 len += sig_and_oid_len;
277 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c2, buf, len));
278 MBEDTLS_ASN1_CHK_ADD(len,
279 mbedtls_asn1_write_tag(
280 &c2, buf,
281 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));
282
283 /* Zero the unused bytes at the start of buf */
284 memset(buf, 0, (size_t) (c2 - buf));
285
286 return (int) len;
287 }
288
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)289 int mbedtls_x509write_csr_der(mbedtls_x509write_csr *ctx, unsigned char *buf,
290 size_t size,
291 int (*f_rng)(void *, unsigned char *, size_t),
292 void *p_rng)
293 {
294 int ret;
295 unsigned char *sig;
296
297 if ((sig = mbedtls_calloc(1, MBEDTLS_PK_SIGNATURE_MAX_SIZE)) == NULL) {
298 return MBEDTLS_ERR_X509_ALLOC_FAILED;
299 }
300
301 ret = x509write_csr_der_internal(ctx, buf, size,
302 sig, MBEDTLS_PK_SIGNATURE_MAX_SIZE,
303 f_rng, p_rng);
304
305 mbedtls_free(sig);
306
307 return ret;
308 }
309
310 #define PEM_BEGIN_CSR "-----BEGIN CERTIFICATE REQUEST-----\n"
311 #define PEM_END_CSR "-----END CERTIFICATE REQUEST-----\n"
312
313 #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)314 int mbedtls_x509write_csr_pem(mbedtls_x509write_csr *ctx, unsigned char *buf, size_t size,
315 int (*f_rng)(void *, unsigned char *, size_t),
316 void *p_rng)
317 {
318 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
319 size_t olen = 0;
320
321 if ((ret = mbedtls_x509write_csr_der(ctx, buf, size,
322 f_rng, p_rng)) < 0) {
323 return ret;
324 }
325
326 if ((ret = mbedtls_pem_write_buffer(PEM_BEGIN_CSR, PEM_END_CSR,
327 buf + size - ret,
328 ret, buf, size, &olen)) != 0) {
329 return ret;
330 }
331
332 return 0;
333 }
334 #endif /* MBEDTLS_PEM_WRITE_C */
335
336 #endif /* MBEDTLS_X509_CSR_WRITE_C */
337