1 /* 2 * X.509 Certificate Signing Request (CSR) parsing 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 * The ITU-T X.509 standard defines a certificate format for PKI. 21 * 22 * http://www.ietf.org/rfc/rfc5280.txt (Certificates and CRLs) 23 * http://www.ietf.org/rfc/rfc3279.txt (Alg IDs for CRLs) 24 * http://www.ietf.org/rfc/rfc2986.txt (CSRs, aka PKCS#10) 25 * 26 * http://www.itu.int/ITU-T/studygroups/com17/languages/X.680-0207.pdf 27 * http://www.itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf 28 */ 29 30 #include "common.h" 31 32 #if defined(MBEDTLS_X509_CSR_PARSE_C) 33 34 #include "mbedtls/x509_csr.h" 35 #include "mbedtls/error.h" 36 #include "mbedtls/oid.h" 37 #include "mbedtls/platform_util.h" 38 39 #include <string.h> 40 41 #if defined(MBEDTLS_PEM_PARSE_C) 42 #include "mbedtls/pem.h" 43 #endif 44 45 #if defined(MBEDTLS_PLATFORM_C) 46 #include "mbedtls/platform.h" 47 #else 48 #include <stdlib.h> 49 #include <stdio.h> 50 #define mbedtls_free free 51 #define mbedtls_calloc calloc 52 #define mbedtls_snprintf snprintf 53 #endif 54 55 #if defined(MBEDTLS_FS_IO) || defined(EFIX64) || defined(EFI32) 56 #include <stdio.h> 57 #endif 58 59 /* 60 * Version ::= INTEGER { v1(0) } 61 */ 62 static int x509_csr_get_version( unsigned char **p, 63 const unsigned char *end, 64 int *ver ) 65 { 66 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 67 68 if( ( ret = mbedtls_asn1_get_int( p, end, ver ) ) != 0 ) 69 { 70 if( ret == MBEDTLS_ERR_ASN1_UNEXPECTED_TAG ) 71 { 72 *ver = 0; 73 return( 0 ); 74 } 75 76 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_VERSION, ret ) ); 77 } 78 79 return( 0 ); 80 } 81 82 /* 83 * Parse a CSR in DER format 84 */ 85 int mbedtls_x509_csr_parse_der( mbedtls_x509_csr *csr, 86 const unsigned char *buf, size_t buflen ) 87 { 88 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 89 size_t len; 90 unsigned char *p, *end; 91 mbedtls_x509_buf sig_params; 92 93 memset( &sig_params, 0, sizeof( mbedtls_x509_buf ) ); 94 95 /* 96 * Check for valid input 97 */ 98 if( csr == NULL || buf == NULL || buflen == 0 ) 99 return( MBEDTLS_ERR_X509_BAD_INPUT_DATA ); 100 101 mbedtls_x509_csr_init( csr ); 102 103 /* 104 * first copy the raw DER data 105 */ 106 p = mbedtls_calloc( 1, len = buflen ); 107 108 if( p == NULL ) 109 return( MBEDTLS_ERR_X509_ALLOC_FAILED ); 110 111 memcpy( p, buf, buflen ); 112 113 csr->raw.p = p; 114 csr->raw.len = len; 115 end = p + len; 116 117 /* 118 * CertificationRequest ::= SEQUENCE { 119 * certificationRequestInfo CertificationRequestInfo, 120 * signatureAlgorithm AlgorithmIdentifier, 121 * signature BIT STRING 122 * } 123 */ 124 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, 125 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 ) 126 { 127 mbedtls_x509_csr_free( csr ); 128 return( MBEDTLS_ERR_X509_INVALID_FORMAT ); 129 } 130 131 if( len != (size_t) ( end - p ) ) 132 { 133 mbedtls_x509_csr_free( csr ); 134 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, 135 MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) ); 136 } 137 138 /* 139 * CertificationRequestInfo ::= SEQUENCE { 140 */ 141 csr->cri.p = p; 142 143 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, 144 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 ) 145 { 146 mbedtls_x509_csr_free( csr ); 147 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) ); 148 } 149 150 end = p + len; 151 csr->cri.len = end - csr->cri.p; 152 153 /* 154 * Version ::= INTEGER { v1(0) } 155 */ 156 if( ( ret = x509_csr_get_version( &p, end, &csr->version ) ) != 0 ) 157 { 158 mbedtls_x509_csr_free( csr ); 159 return( ret ); 160 } 161 162 if( csr->version != 0 ) 163 { 164 mbedtls_x509_csr_free( csr ); 165 return( MBEDTLS_ERR_X509_UNKNOWN_VERSION ); 166 } 167 168 csr->version++; 169 170 /* 171 * subject Name 172 */ 173 csr->subject_raw.p = p; 174 175 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, 176 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 ) 177 { 178 mbedtls_x509_csr_free( csr ); 179 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) ); 180 } 181 182 if( ( ret = mbedtls_x509_get_name( &p, p + len, &csr->subject ) ) != 0 ) 183 { 184 mbedtls_x509_csr_free( csr ); 185 return( ret ); 186 } 187 188 csr->subject_raw.len = p - csr->subject_raw.p; 189 190 /* 191 * subjectPKInfo SubjectPublicKeyInfo 192 */ 193 if( ( ret = mbedtls_pk_parse_subpubkey( &p, end, &csr->pk ) ) != 0 ) 194 { 195 mbedtls_x509_csr_free( csr ); 196 return( ret ); 197 } 198 199 /* 200 * attributes [0] Attributes 201 * 202 * The list of possible attributes is open-ended, though RFC 2985 203 * (PKCS#9) defines a few in section 5.4. We currently don't support any, 204 * so we just ignore them. This is a safe thing to do as the worst thing 205 * that could happen is that we issue a certificate that does not match 206 * the requester's expectations - this cannot cause a violation of our 207 * signature policies. 208 */ 209 if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, 210 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC ) ) != 0 ) 211 { 212 mbedtls_x509_csr_free( csr ); 213 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, ret ) ); 214 } 215 216 p += len; 217 218 end = csr->raw.p + csr->raw.len; 219 220 /* 221 * signatureAlgorithm AlgorithmIdentifier, 222 * signature BIT STRING 223 */ 224 if( ( ret = mbedtls_x509_get_alg( &p, end, &csr->sig_oid, &sig_params ) ) != 0 ) 225 { 226 mbedtls_x509_csr_free( csr ); 227 return( ret ); 228 } 229 230 if( ( ret = mbedtls_x509_get_sig_alg( &csr->sig_oid, &sig_params, 231 &csr->sig_md, &csr->sig_pk, 232 &csr->sig_opts ) ) != 0 ) 233 { 234 mbedtls_x509_csr_free( csr ); 235 return( MBEDTLS_ERR_X509_UNKNOWN_SIG_ALG ); 236 } 237 238 if( ( ret = mbedtls_x509_get_sig( &p, end, &csr->sig ) ) != 0 ) 239 { 240 mbedtls_x509_csr_free( csr ); 241 return( ret ); 242 } 243 244 if( p != end ) 245 { 246 mbedtls_x509_csr_free( csr ); 247 return( MBEDTLS_ERROR_ADD( MBEDTLS_ERR_X509_INVALID_FORMAT, 248 MBEDTLS_ERR_ASN1_LENGTH_MISMATCH ) ); 249 } 250 251 return( 0 ); 252 } 253 254 /* 255 * Parse a CSR, allowing for PEM or raw DER encoding 256 */ 257 int mbedtls_x509_csr_parse( mbedtls_x509_csr *csr, const unsigned char *buf, size_t buflen ) 258 { 259 #if defined(MBEDTLS_PEM_PARSE_C) 260 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 261 size_t use_len; 262 mbedtls_pem_context pem; 263 #endif 264 265 /* 266 * Check for valid input 267 */ 268 if( csr == NULL || buf == NULL || buflen == 0 ) 269 return( MBEDTLS_ERR_X509_BAD_INPUT_DATA ); 270 271 #if defined(MBEDTLS_PEM_PARSE_C) 272 /* Avoid calling mbedtls_pem_read_buffer() on non-null-terminated string */ 273 if( buf[buflen - 1] == '\0' ) 274 { 275 mbedtls_pem_init( &pem ); 276 ret = mbedtls_pem_read_buffer( &pem, 277 "-----BEGIN CERTIFICATE REQUEST-----", 278 "-----END CERTIFICATE REQUEST-----", 279 buf, NULL, 0, &use_len ); 280 if( ret == MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT ) 281 { 282 ret = mbedtls_pem_read_buffer( &pem, 283 "-----BEGIN NEW CERTIFICATE REQUEST-----", 284 "-----END NEW CERTIFICATE REQUEST-----", 285 buf, NULL, 0, &use_len ); 286 } 287 288 if( ret == 0 ) 289 { 290 /* 291 * Was PEM encoded, parse the result 292 */ 293 ret = mbedtls_x509_csr_parse_der( csr, pem.buf, pem.buflen ); 294 } 295 296 mbedtls_pem_free( &pem ); 297 if( ret != MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT ) 298 return( ret ); 299 } 300 #endif /* MBEDTLS_PEM_PARSE_C */ 301 return( mbedtls_x509_csr_parse_der( csr, buf, buflen ) ); 302 } 303 304 #if defined(MBEDTLS_FS_IO) 305 /* 306 * Load a CSR into the structure 307 */ 308 int mbedtls_x509_csr_parse_file( mbedtls_x509_csr *csr, const char *path ) 309 { 310 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 311 size_t n; 312 unsigned char *buf; 313 314 if( ( ret = mbedtls_pk_load_file( path, &buf, &n ) ) != 0 ) 315 return( ret ); 316 317 ret = mbedtls_x509_csr_parse( csr, buf, n ); 318 319 mbedtls_platform_zeroize( buf, n ); 320 mbedtls_free( buf ); 321 322 return( ret ); 323 } 324 #endif /* MBEDTLS_FS_IO */ 325 326 #define BEFORE_COLON 14 327 #define BC "14" 328 /* 329 * Return an informational string about the CSR. 330 */ 331 int mbedtls_x509_csr_info( char *buf, size_t size, const char *prefix, 332 const mbedtls_x509_csr *csr ) 333 { 334 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 335 size_t n; 336 char *p; 337 char key_size_str[BEFORE_COLON]; 338 339 p = buf; 340 n = size; 341 342 ret = mbedtls_snprintf( p, n, "%sCSR version : %d", 343 prefix, csr->version ); 344 MBEDTLS_X509_SAFE_SNPRINTF; 345 346 ret = mbedtls_snprintf( p, n, "\n%ssubject name : ", prefix ); 347 MBEDTLS_X509_SAFE_SNPRINTF; 348 ret = mbedtls_x509_dn_gets( p, n, &csr->subject ); 349 MBEDTLS_X509_SAFE_SNPRINTF; 350 351 ret = mbedtls_snprintf( p, n, "\n%ssigned using : ", prefix ); 352 MBEDTLS_X509_SAFE_SNPRINTF; 353 354 ret = mbedtls_x509_sig_alg_gets( p, n, &csr->sig_oid, csr->sig_pk, csr->sig_md, 355 csr->sig_opts ); 356 MBEDTLS_X509_SAFE_SNPRINTF; 357 358 if( ( ret = mbedtls_x509_key_size_helper( key_size_str, BEFORE_COLON, 359 mbedtls_pk_get_name( &csr->pk ) ) ) != 0 ) 360 { 361 return( ret ); 362 } 363 364 ret = mbedtls_snprintf( p, n, "\n%s%-" BC "s: %d bits\n", prefix, key_size_str, 365 (int) mbedtls_pk_get_bitlen( &csr->pk ) ); 366 MBEDTLS_X509_SAFE_SNPRINTF; 367 368 return( (int) ( size - n ) ); 369 } 370 371 /* 372 * Initialize a CSR 373 */ 374 void mbedtls_x509_csr_init( mbedtls_x509_csr *csr ) 375 { 376 memset( csr, 0, sizeof(mbedtls_x509_csr) ); 377 } 378 379 /* 380 * Unallocate all CSR data 381 */ 382 void mbedtls_x509_csr_free( mbedtls_x509_csr *csr ) 383 { 384 mbedtls_x509_name *name_cur; 385 mbedtls_x509_name *name_prv; 386 387 if( csr == NULL ) 388 return; 389 390 mbedtls_pk_free( &csr->pk ); 391 392 #if defined(MBEDTLS_X509_RSASSA_PSS_SUPPORT) 393 mbedtls_free( csr->sig_opts ); 394 #endif 395 396 name_cur = csr->subject.next; 397 while( name_cur != NULL ) 398 { 399 name_prv = name_cur; 400 name_cur = name_cur->next; 401 mbedtls_platform_zeroize( name_prv, sizeof( mbedtls_x509_name ) ); 402 mbedtls_free( name_prv ); 403 } 404 405 if( csr->raw.p != NULL ) 406 { 407 mbedtls_platform_zeroize( csr->raw.p, csr->raw.len ); 408 mbedtls_free( csr->raw.p ); 409 } 410 411 mbedtls_platform_zeroize( csr, sizeof( mbedtls_x509_csr ) ); 412 } 413 414 #endif /* MBEDTLS_X509_CSR_PARSE_C */ 415