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