1 // SPDX-License-Identifier: Apache-2.0 2 /* 3 * X.509 Certificate Signing Request writing 4 * 5 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved 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 * This file is part of mbed TLS (https://tls.mbed.org) 20 */ 21 /* 22 * References: 23 * - CSRs: PKCS#10 v1.7 aka RFC 2986 24 * - attributes: PKCS#9 v2.0 aka RFC 2985 25 */ 26 27 #if !defined(MBEDTLS_CONFIG_FILE) 28 #include "mbedtls/config.h" 29 #else 30 #include MBEDTLS_CONFIG_FILE 31 #endif 32 33 #if defined(MBEDTLS_X509_CSR_WRITE_C) 34 35 #include "mbedtls/x509_csr.h" 36 #include "mbedtls/oid.h" 37 #include "mbedtls/asn1write.h" 38 #include "mbedtls/platform_util.h" 39 40 #include <string.h> 41 #include <stdlib.h> 42 43 #if defined(MBEDTLS_PEM_WRITE_C) 44 #include "mbedtls/pem.h" 45 #endif 46 47 /* 48 * For the currently used signature algorithms the buffer to store any signature 49 * must be at least of size MAX(MBEDTLS_ECDSA_MAX_LEN, MBEDTLS_MPI_MAX_SIZE) 50 */ 51 #if MBEDTLS_ECDSA_MAX_LEN > MBEDTLS_MPI_MAX_SIZE 52 #define SIGNATURE_MAX_SIZE MBEDTLS_ECDSA_MAX_LEN 53 #else 54 #define SIGNATURE_MAX_SIZE MBEDTLS_MPI_MAX_SIZE 55 #endif 56 57 void mbedtls_x509write_csr_init( mbedtls_x509write_csr *ctx ) 58 { 59 memset( ctx, 0, sizeof( mbedtls_x509write_csr ) ); 60 } 61 62 void mbedtls_x509write_csr_free( mbedtls_x509write_csr *ctx ) 63 { 64 mbedtls_asn1_free_named_data_list( &ctx->subject ); 65 mbedtls_asn1_free_named_data_list( &ctx->extensions ); 66 67 mbedtls_platform_zeroize( ctx, sizeof( mbedtls_x509write_csr ) ); 68 } 69 70 void mbedtls_x509write_csr_set_md_alg( mbedtls_x509write_csr *ctx, mbedtls_md_type_t md_alg ) 71 { 72 ctx->md_alg = md_alg; 73 } 74 75 void mbedtls_x509write_csr_set_key( mbedtls_x509write_csr *ctx, mbedtls_pk_context *key ) 76 { 77 ctx->key = key; 78 } 79 80 int mbedtls_x509write_csr_set_subject_name( mbedtls_x509write_csr *ctx, 81 const char *subject_name ) 82 { 83 return mbedtls_x509_string_to_names( &ctx->subject, subject_name ); 84 } 85 86 int mbedtls_x509write_csr_set_extension( mbedtls_x509write_csr *ctx, 87 const char *oid, size_t oid_len, 88 const unsigned char *val, size_t val_len ) 89 { 90 return mbedtls_x509_set_extension( &ctx->extensions, oid, oid_len, 91 0, val, val_len ); 92 } 93 94 static size_t csr_get_unused_bits_for_named_bitstring( unsigned char bitstring, 95 size_t bit_offset ) 96 { 97 size_t unused_bits; 98 99 /* Count the unused bits removing trailing 0s */ 100 for( unused_bits = bit_offset; unused_bits < 8; unused_bits++ ) 101 if( ( ( bitstring >> unused_bits ) & 0x1 ) != 0 ) 102 break; 103 104 return( unused_bits ); 105 } 106 107 int mbedtls_x509write_csr_set_key_usage( mbedtls_x509write_csr *ctx, unsigned char key_usage ) 108 { 109 unsigned char buf[4]; 110 unsigned char *c; 111 size_t unused_bits; 112 int ret; 113 114 c = buf + 4; 115 116 unused_bits = csr_get_unused_bits_for_named_bitstring( key_usage, 0 ); 117 ret = mbedtls_asn1_write_bitstring( &c, buf, &key_usage, 8 - unused_bits ); 118 119 if( ret < 0 ) 120 return( ret ); 121 else if( ret < 3 || ret > 4 ) 122 return( MBEDTLS_ERR_X509_INVALID_FORMAT ); 123 124 ret = mbedtls_x509write_csr_set_extension( ctx, MBEDTLS_OID_KEY_USAGE, 125 MBEDTLS_OID_SIZE( MBEDTLS_OID_KEY_USAGE ), 126 c, (size_t)ret ); 127 if( ret != 0 ) 128 return( ret ); 129 130 return( 0 ); 131 } 132 133 int mbedtls_x509write_csr_set_ns_cert_type( mbedtls_x509write_csr *ctx, 134 unsigned char ns_cert_type ) 135 { 136 unsigned char buf[4]; 137 unsigned char *c; 138 size_t unused_bits; 139 int ret; 140 141 c = buf + 4; 142 143 unused_bits = csr_get_unused_bits_for_named_bitstring( ns_cert_type, 0 ); 144 ret = mbedtls_asn1_write_bitstring( &c, 145 buf, 146 &ns_cert_type, 147 8 - unused_bits ); 148 149 if( ret < 0 ) 150 return( ret ); 151 else if( ret < 3 || ret > 4 ) 152 return( ret ); 153 154 ret = mbedtls_x509write_csr_set_extension( ctx, MBEDTLS_OID_NS_CERT_TYPE, 155 MBEDTLS_OID_SIZE( MBEDTLS_OID_NS_CERT_TYPE ), 156 c, (size_t)ret ); 157 if( ret != 0 ) 158 return( ret ); 159 160 return( 0 ); 161 } 162 163 int mbedtls_x509write_csr_der( mbedtls_x509write_csr *ctx, unsigned char *buf, size_t size, 164 int (*f_rng)(void *, unsigned char *, size_t), 165 void *p_rng ) 166 { 167 int ret; 168 const char *sig_oid; 169 size_t sig_oid_len = 0; 170 unsigned char *c, *c2; 171 unsigned char hash[64]; 172 unsigned char sig[SIGNATURE_MAX_SIZE]; 173 unsigned char tmp_buf[2048]; 174 size_t pub_len = 0, sig_and_oid_len = 0, sig_len; 175 size_t len = 0; 176 mbedtls_pk_type_t pk_alg; 177 178 /* 179 * Prepare data to be signed in tmp_buf 180 */ 181 c = tmp_buf + sizeof( tmp_buf ); 182 183 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_x509_write_extensions( &c, tmp_buf, ctx->extensions ) ); 184 185 if( len ) 186 { 187 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) ); 188 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED | 189 MBEDTLS_ASN1_SEQUENCE ) ); 190 191 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) ); 192 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED | 193 MBEDTLS_ASN1_SET ) ); 194 195 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( &c, tmp_buf, MBEDTLS_OID_PKCS9_CSR_EXT_REQ, 196 MBEDTLS_OID_SIZE( MBEDTLS_OID_PKCS9_CSR_EXT_REQ ) ) ); 197 198 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) ); 199 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED | 200 MBEDTLS_ASN1_SEQUENCE ) ); 201 } 202 203 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) ); 204 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED | 205 MBEDTLS_ASN1_CONTEXT_SPECIFIC ) ); 206 207 MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_pk_write_pubkey_der( ctx->key, 208 tmp_buf, c - tmp_buf ) ); 209 c -= pub_len; 210 len += pub_len; 211 212 /* 213 * Subject ::= Name 214 */ 215 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_x509_write_names( &c, tmp_buf, ctx->subject ) ); 216 217 /* 218 * Version ::= INTEGER { v1(0), v2(1), v3(2) } 219 */ 220 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_int( &c, tmp_buf, 0 ) ); 221 222 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) ); 223 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED | 224 MBEDTLS_ASN1_SEQUENCE ) ); 225 226 /* 227 * Prepare signature 228 */ 229 ret = mbedtls_md( mbedtls_md_info_from_type( ctx->md_alg ), c, len, hash ); 230 if( ret != 0 ) 231 return( ret ); 232 233 if( ( ret = mbedtls_pk_sign( ctx->key, ctx->md_alg, hash, 0, sig, &sig_len, 234 f_rng, p_rng ) ) != 0 ) 235 { 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 if( ( ret = mbedtls_oid_get_oid_by_sig_alg( pk_alg, ctx->md_alg, 247 &sig_oid, &sig_oid_len ) ) != 0 ) 248 { 249 return( ret ); 250 } 251 252 /* 253 * Write data to output buffer 254 */ 255 c2 = buf + size; 256 MBEDTLS_ASN1_CHK_ADD( sig_and_oid_len, mbedtls_x509_write_sig( &c2, buf, 257 sig_oid, sig_oid_len, sig, sig_len ) ); 258 259 if( len > (size_t)( c2 - buf ) ) 260 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL ); 261 262 c2 -= len; 263 memcpy( c2, c, len ); 264 265 len += sig_and_oid_len; 266 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c2, buf, len ) ); 267 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c2, buf, MBEDTLS_ASN1_CONSTRUCTED | 268 MBEDTLS_ASN1_SEQUENCE ) ); 269 270 return( (int) len ); 271 } 272 273 #define PEM_BEGIN_CSR "-----BEGIN CERTIFICATE REQUEST-----\n" 274 #define PEM_END_CSR "-----END CERTIFICATE REQUEST-----\n" 275 276 #if defined(MBEDTLS_PEM_WRITE_C) 277 int mbedtls_x509write_csr_pem( mbedtls_x509write_csr *ctx, unsigned char *buf, size_t size, 278 int (*f_rng)(void *, unsigned char *, size_t), 279 void *p_rng ) 280 { 281 int ret; 282 unsigned char output_buf[4096]; 283 size_t olen = 0; 284 285 if( ( ret = mbedtls_x509write_csr_der( ctx, output_buf, sizeof(output_buf), 286 f_rng, p_rng ) ) < 0 ) 287 { 288 return( ret ); 289 } 290 291 if( ( ret = mbedtls_pem_write_buffer( PEM_BEGIN_CSR, PEM_END_CSR, 292 output_buf + sizeof(output_buf) - ret, 293 ret, buf, size, &olen ) ) != 0 ) 294 { 295 return( ret ); 296 } 297 298 return( 0 ); 299 } 300 #endif /* MBEDTLS_PEM_WRITE_C */ 301 302 #endif /* MBEDTLS_X509_CSR_WRITE_C */ 303