/* * 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 "x509_internal.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 "mbedtls/psa_util.h" #endif /* MBEDTLS_USE_PSA_CRYPTO */ #include #include #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) { return mbedtls_x509_write_set_san_common(&ctx->extensions, san_list); } 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, (size_t) (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, 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, (size_t) (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 */