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 39 void mbedtls_x509write_csr_init(mbedtls_x509write_csr *ctx) 40 { 41 memset(ctx, 0, sizeof(mbedtls_x509write_csr)); 42 } 43 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 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 61 void mbedtls_x509write_csr_set_key(mbedtls_x509write_csr *ctx, mbedtls_pk_context *key) 62 { 63 ctx->key = key; 64 } 65 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 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 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 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 } 109 110 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 } 133 134 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 } 287 288 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) 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