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mbedtls/library/x509write_csr.c
Gilles Peskine f00f152444 Add output size parameter to signature functions 
The functions mbedtls_pk_sign(), mbedtls_pk_sign_restartable(),
mbedtls_ecdsa_write_signature() and mbedtls_ecdsa_write_signature_restartable()
now take an extra parameter indicating the size of the output buffer for the
signature.

No change to RSA because for RSA, the output size is trivial to calculate.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
2021-06-25 00:46:22 +02:00

346 lines
11 KiB
C
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/*
* X.509 Certificate Signing Request writing
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-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.
*/
/*
* References:
* - CSRs: PKCS#10 v1.7 aka RFC 2986
* - attributes: PKCS#9 v2.0 aka RFC 2985
*/
#include "common.h"
#if defined(MBEDTLS_X509_CSR_WRITE_C)
#include "mbedtls/x509_csr.h"
#include "mbedtls/asn1write.h"
#include "mbedtls/error.h"
#include "mbedtls/oid.h"
#include "mbedtls/platform_util.h"
#if defined(MBEDTLS_USE_PSA_CRYPTO)
#include "psa/crypto.h"
#include "mbedtls/psa_util.h"
#endif
#include <string.h>
#include <stdlib.h>
#if defined(MBEDTLS_PEM_WRITE_C)
#include "mbedtls/pem.h"
#endif
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdlib.h>
#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,
int critical,
const unsigned char *val, size_t val_len )
{
return mbedtls_x509_set_extension( &ctx->extensions, oid, oid_len,
critical, val, val_len );
}
int mbedtls_x509write_csr_set_key_usage( mbedtls_x509write_csr *ctx, unsigned char key_usage )
{
unsigned char buf[4] = {0};
unsigned char *c;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
c = buf + 4;
ret = mbedtls_asn1_write_named_bitstring( &c, buf, &key_usage, 8 );
if( ret < 3 || ret > 4 )
return( ret );
ret = mbedtls_x509write_csr_set_extension( ctx, MBEDTLS_OID_KEY_USAGE,
MBEDTLS_OID_SIZE( MBEDTLS_OID_KEY_USAGE ),
0, 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] = {0};
unsigned char *c;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
c = buf + 4;
ret = mbedtls_asn1_write_named_bitstring( &c, buf, &ns_cert_type, 8 );
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 ),
0, 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, size_t sig_size,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_hash_operation_t hash_operation = PSA_HASH_OPERATION_INIT;
size_t hash_len;
psa_algorithm_t hash_alg = mbedtls_psa_translate_md( ctx->md_alg );
#endif /* MBEDTLS_USE_PSA_CRYPTO */
/* 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
*/
#if defined(MBEDTLS_USE_PSA_CRYPTO)
if( psa_hash_setup( &hash_operation, hash_alg ) != PSA_SUCCESS )
return( MBEDTLS_ERR_X509_FATAL_ERROR );
if( psa_hash_update( &hash_operation, c, len ) != PSA_SUCCESS )
return( MBEDTLS_ERR_X509_FATAL_ERROR );
if( psa_hash_finish( &hash_operation, hash, sizeof( hash ), &hash_len )
!= PSA_SUCCESS )
{
return( MBEDTLS_ERR_X509_FATAL_ERROR );
}
#else /* MBEDTLS_USE_PSA_CRYPTO */
ret = mbedtls_md( mbedtls_md_info_from_type( ctx->md_alg ), c, len, hash );
if( ret != 0 )
return( ret );
#endif
if( ( ret = mbedtls_pk_sign( ctx->key, ctx->md_alg, hash, 0,
sig, sig_size, &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, MBEDTLS_PK_SIGNATURE_MAX_SIZE ) ) == NULL )
{
return( MBEDTLS_ERR_X509_ALLOC_FAILED );
}
ret = x509write_csr_der_internal( ctx, buf, size,
sig, MBEDTLS_PK_SIGNATURE_MAX_SIZE,
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 = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t olen = 0;
if( ( ret = mbedtls_x509write_csr_der( ctx, buf, size,
f_rng, p_rng ) ) < 0 )
{
return( ret );
}
if( ( ret = mbedtls_pem_write_buffer( PEM_BEGIN_CSR, PEM_END_CSR,
buf + size - ret,
ret, buf, size, &olen ) ) != 0 )
{
return( ret );
}
return( 0 );
}
#endif /* MBEDTLS_PEM_WRITE_C */
#endif /* MBEDTLS_X509_CSR_WRITE_C */
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