/* * X.509 Certificate Signing Request writing * * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later * * This file is provided under the Apache License 2.0, or the * GNU General Public License v2.0 or later. * * ********** * Apache License 2.0: * * Licensed under the Apache License, Version 2.0 (the "License"); you may * not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * * ********** * * ********** * GNU General Public License v2.0 or later: * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. * * ********** * * This file is part of mbed TLS (https://tls.mbed.org) */ /* * References: * - CSRs: PKCS#10 v1.7 aka RFC 2986 * - attributes: PKCS#9 v2.0 aka RFC 2985 */ #if !defined(MBEDTLS_CONFIG_FILE) #include "mbedtls/config.h" #else #include MBEDTLS_CONFIG_FILE #endif #if defined(MBEDTLS_X509_CSR_WRITE_C) #include "mbedtls/x509_csr.h" #include "mbedtls/oid.h" #include "mbedtls/asn1write.h" #include "mbedtls/platform_util.h" #include #include #if defined(MBEDTLS_PEM_WRITE_C) #include "mbedtls/pem.h" #endif /* * For the currently used signature algorithms the buffer to store any signature * must be at least of size MAX(MBEDTLS_ECDSA_MAX_LEN, MBEDTLS_MPI_MAX_SIZE) */ #if MBEDTLS_ECDSA_MAX_LEN > MBEDTLS_MPI_MAX_SIZE #define SIGNATURE_MAX_SIZE MBEDTLS_ECDSA_MAX_LEN #else #define SIGNATURE_MAX_SIZE MBEDTLS_MPI_MAX_SIZE #endif #if defined(MBEDTLS_PLATFORM_C) #include "mbedtls/platform.h" #else #include #define mbedtls_calloc calloc #define mbedtls_free free #endif void mbedtls_x509write_csr_init( mbedtls_x509write_csr *ctx ) { memset( ctx, 0, sizeof( mbedtls_x509write_csr ) ); } void mbedtls_x509write_csr_free( mbedtls_x509write_csr *ctx ) { mbedtls_asn1_free_named_data_list( &ctx->subject ); mbedtls_asn1_free_named_data_list( &ctx->extensions ); mbedtls_platform_zeroize( ctx, sizeof( mbedtls_x509write_csr ) ); } void mbedtls_x509write_csr_set_md_alg( mbedtls_x509write_csr *ctx, mbedtls_md_type_t md_alg ) { ctx->md_alg = md_alg; } void mbedtls_x509write_csr_set_key( mbedtls_x509write_csr *ctx, mbedtls_pk_context *key ) { ctx->key = key; } int mbedtls_x509write_csr_set_subject_name( mbedtls_x509write_csr *ctx, const char *subject_name ) { return mbedtls_x509_string_to_names( &ctx->subject, subject_name ); } int mbedtls_x509write_csr_set_extension( mbedtls_x509write_csr *ctx, const char *oid, size_t oid_len, const unsigned char *val, size_t val_len ) { return mbedtls_x509_set_extension( &ctx->extensions, oid, oid_len, 0, val, val_len ); } static size_t csr_get_unused_bits_for_named_bitstring( unsigned char bitstring, size_t bit_offset ) { size_t unused_bits; /* Count the unused bits removing trailing 0s */ for( unused_bits = bit_offset; unused_bits < 8; unused_bits++ ) if( ( ( bitstring >> unused_bits ) & 0x1 ) != 0 ) break; return( unused_bits ); } int mbedtls_x509write_csr_set_key_usage( mbedtls_x509write_csr *ctx, unsigned char key_usage ) { unsigned char buf[4]; unsigned char *c; size_t unused_bits; int ret; c = buf + 4; unused_bits = csr_get_unused_bits_for_named_bitstring( key_usage, 0 ); ret = mbedtls_asn1_write_bitstring( &c, buf, &key_usage, 8 - unused_bits ); if( ret < 0 ) return( ret ); else if( ret < 3 || ret > 4 ) return( MBEDTLS_ERR_X509_INVALID_FORMAT ); ret = mbedtls_x509write_csr_set_extension( ctx, MBEDTLS_OID_KEY_USAGE, MBEDTLS_OID_SIZE( MBEDTLS_OID_KEY_USAGE ), c, (size_t)ret ); if( ret != 0 ) return( ret ); return( 0 ); } int mbedtls_x509write_csr_set_ns_cert_type( mbedtls_x509write_csr *ctx, unsigned char ns_cert_type ) { unsigned char buf[4]; unsigned char *c; size_t unused_bits; int ret; c = buf + 4; unused_bits = csr_get_unused_bits_for_named_bitstring( ns_cert_type, 0 ); ret = mbedtls_asn1_write_bitstring( &c, buf, &ns_cert_type, 8 - unused_bits ); if( ret < 0 ) return( ret ); else if( ret < 3 || ret > 4 ) return( ret ); ret = mbedtls_x509write_csr_set_extension( ctx, MBEDTLS_OID_NS_CERT_TYPE, MBEDTLS_OID_SIZE( MBEDTLS_OID_NS_CERT_TYPE ), c, (size_t)ret ); if( ret != 0 ) return( ret ); return( 0 ); } static int x509write_csr_der_internal( mbedtls_x509write_csr *ctx, unsigned char *buf, size_t size, unsigned char *sig, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng ) { int ret; const char *sig_oid; size_t sig_oid_len = 0; unsigned char *c, *c2; unsigned char hash[64]; size_t pub_len = 0, sig_and_oid_len = 0, sig_len; size_t len = 0; mbedtls_pk_type_t pk_alg; /* Write the CSR backwards starting from the end of buf */ c = buf + size; MBEDTLS_ASN1_CHK_ADD( len, mbedtls_x509_write_extensions( &c, buf, ctx->extensions ) ); if( len ) { MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SET ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( &c, buf, MBEDTLS_OID_PKCS9_CSR_EXT_REQ, MBEDTLS_OID_SIZE( MBEDTLS_OID_PKCS9_CSR_EXT_REQ ) ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ); } MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC ) ); MBEDTLS_ASN1_CHK_ADD( pub_len, mbedtls_pk_write_pubkey_der( ctx->key, buf, c - buf ) ); c -= pub_len; len += pub_len; /* * Subject ::= Name */ MBEDTLS_ASN1_CHK_ADD( len, mbedtls_x509_write_names( &c, buf, ctx->subject ) ); /* * Version ::= INTEGER { v1(0), v2(1), v3(2) } */ MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_int( &c, buf, 0 ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, buf, len ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, buf, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ); /* * Sign the written CSR data into the sig buffer * Note: hash errors can happen only after an internal error */ ret = mbedtls_md( mbedtls_md_info_from_type( ctx->md_alg ), c, len, hash ); if( ret != 0 ) return( ret ); if( ( ret = mbedtls_pk_sign( ctx->key, ctx->md_alg, hash, 0, sig, &sig_len, f_rng, p_rng ) ) != 0 ) { return( ret ); } if( mbedtls_pk_can_do( ctx->key, MBEDTLS_PK_RSA ) ) pk_alg = MBEDTLS_PK_RSA; else if( mbedtls_pk_can_do( ctx->key, MBEDTLS_PK_ECDSA ) ) pk_alg = MBEDTLS_PK_ECDSA; else return( MBEDTLS_ERR_X509_INVALID_ALG ); if( ( ret = mbedtls_oid_get_oid_by_sig_alg( pk_alg, ctx->md_alg, &sig_oid, &sig_oid_len ) ) != 0 ) { return( ret ); } /* * Move the written CSR data to the start of buf to create space for * writing the signature into buf. */ memmove( buf, c, len ); /* * Write sig and its OID into buf backwards from the end of buf. * Note: mbedtls_x509_write_sig will check for c2 - ( buf + len ) < sig_len * and return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL if needed. */ c2 = buf + size; MBEDTLS_ASN1_CHK_ADD( sig_and_oid_len, mbedtls_x509_write_sig( &c2, buf + len, sig_oid, sig_oid_len, sig, sig_len ) ); /* * Compact the space between the CSR data and signature by moving the * CSR data to the start of the signature. */ c2 -= len; memmove( c2, buf, len ); /* ASN encode the total size and tag the CSR data with it. */ len += sig_and_oid_len; MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c2, buf, len ) ); MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c2, buf, MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ); /* Zero the unused bytes at the start of buf */ memset( buf, 0, c2 - buf); return( (int) len ); } int 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 ) { int ret; unsigned char *sig; if( ( sig = mbedtls_calloc( 1, SIGNATURE_MAX_SIZE ) ) == NULL ) { return( MBEDTLS_ERR_X509_ALLOC_FAILED ); } ret = x509write_csr_der_internal( ctx, buf, size, sig, f_rng, p_rng ); mbedtls_free( sig ); return( ret ); } #define PEM_BEGIN_CSR "-----BEGIN CERTIFICATE REQUEST-----\n" #define PEM_END_CSR "-----END CERTIFICATE REQUEST-----\n" #if defined(MBEDTLS_PEM_WRITE_C) int 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 ) { int ret; unsigned char output_buf[4096]; size_t olen = 0; if( ( ret = mbedtls_x509write_csr_der( ctx, output_buf, sizeof(output_buf), f_rng, p_rng ) ) < 0 ) { return( ret ); } if( ( ret = mbedtls_pem_write_buffer( PEM_BEGIN_CSR, PEM_END_CSR, output_buf + sizeof(output_buf) - ret, ret, buf, size, &olen ) ) != 0 ) { return( ret ); } return( 0 ); } #endif /* MBEDTLS_PEM_WRITE_C */ #endif /* MBEDTLS_X509_CSR_WRITE_C */