/*

 *  X.509 Certificate Signing Request writing

 *

 *  Copyright The Mbed TLS Contributors

 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later

 */

/*

 * 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

#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,

                                        const unsigned char *val, size_t val_len)

{

    return mbedtls_x509_set_extension(&ctx->extensions, oid, oid_len,

                                      0, 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),

                                              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),

                                              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 = 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_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, pk_alg));

    /*

     * 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, 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 */