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mbedtls/library/x509write_csr.c
Manuel Pégourié-Gonnard 2be8c63af7 Create psa_util_internal.h 
Most functions in psa_util.h are going to end up there (except those
that can be static in one file), but I wanted to have separate commits
for file creation and moving code around, so for now the new file's
pretty empty but that will change in the next few commits.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
2023-07-06 12:42:33 +02:00

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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.h"
#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 "psa_util_internal.h"
#include "md_psa.h"
#endif /* MBEDTLS_USE_PSA_CRYPTO */
#include <string.h>
#include <stdlib.h>
#if defined(MBEDTLS_PEM_WRITE_C)
#include "mbedtls/pem.h"
#endif
#include "mbedtls/platform.h"
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_subject_alternative_name(mbedtls_x509write_csr *ctx,
const mbedtls_x509_san_list *san_list)
{
int ret = 0;
const mbedtls_x509_san_list *cur;
unsigned char *buf;
unsigned char *p;
size_t len;
size_t buflen = 0;
/* Determine the maximum size of the SubjectAltName list */
for (cur = san_list; cur != NULL; cur = cur->next) {
/* Calculate size of the required buffer */
switch (cur->node.type) {
case MBEDTLS_X509_SAN_DNS_NAME:
case MBEDTLS_X509_SAN_UNIFORM_RESOURCE_IDENTIFIER:
case MBEDTLS_X509_SAN_IP_ADDRESS:
/* length of value for each name entry,
* maximum 4 bytes for the length field,
* 1 byte for the tag/type.
*/
buflen += cur->node.san.unstructured_name.len + 4 + 1;
break;
default:
/* Not supported - skip. */
break;
}
}
/* Add the extra length field and tag */
buflen += 4 + 1;
/* Allocate buffer */
buf = mbedtls_calloc(1, buflen);
if (buf == NULL) {
return MBEDTLS_ERR_ASN1_ALLOC_FAILED;
}
mbedtls_platform_zeroize(buf, buflen);
p = buf + buflen;
/* Write ASN.1-based structure */
cur = san_list;
len = 0;
while (cur != NULL) {
switch (cur->node.type) {
case MBEDTLS_X509_SAN_DNS_NAME:
case MBEDTLS_X509_SAN_UNIFORM_RESOURCE_IDENTIFIER:
case MBEDTLS_X509_SAN_IP_ADDRESS:
{
const unsigned char *unstructured_name =
(const unsigned char *) cur->node.san.unstructured_name.p;
size_t unstructured_name_len = cur->node.san.unstructured_name.len;
MBEDTLS_ASN1_CHK_CLEANUP_ADD(len,
mbedtls_asn1_write_raw_buffer(
&p, buf,
unstructured_name, unstructured_name_len));
MBEDTLS_ASN1_CHK_CLEANUP_ADD(len, mbedtls_asn1_write_len(
&p, buf, unstructured_name_len));
MBEDTLS_ASN1_CHK_CLEANUP_ADD(len,
mbedtls_asn1_write_tag(
&p, buf,
MBEDTLS_ASN1_CONTEXT_SPECIFIC | cur->node.type));
}
break;
default:
/* Skip unsupported names. */
break;
}
cur = cur->next;
}
MBEDTLS_ASN1_CHK_CLEANUP_ADD(len, mbedtls_asn1_write_len(&p, buf, len));
MBEDTLS_ASN1_CHK_CLEANUP_ADD(len,
mbedtls_asn1_write_tag(&p, buf,
MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SEQUENCE));
ret = mbedtls_x509write_csr_set_extension(
ctx,
MBEDTLS_OID_SUBJECT_ALT_NAME,
MBEDTLS_OID_SIZE(MBEDTLS_OID_SUBJECT_ALT_NAME),
0,
buf + buflen - len,
len);
/* If we exceeded the allocated buffer it means that maximum size of the SubjectAltName list
* was incorrectly calculated and memory is corrupted. */
if (p < buf) {
ret = MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
}
cleanup:
mbedtls_free(buf);
return ret;
}
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[MBEDTLS_MD_MAX_SIZE];
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)
size_t hash_len;
psa_algorithm_t hash_alg = mbedtls_md_psa_alg_from_type(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_compute(hash_alg,
c,
len,
hash,
sizeof(hash),
&hash_len) != PSA_SUCCESS) {
return MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED;
}
#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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