[PATCH v6 24/28] mbedtls: add RSA helper layer on MbedTLS
Ilias Apalodimas
ilias.apalodimas at linaro.org
Wed Aug 28 12:28:51 CEST 2024
On Sat, 17 Aug 2024 at 00:54, Raymond Mao <raymond.mao at linaro.org> wrote:
>
> Add RSA helper layer on top on MbedTLS PK and RSA library.
> Introduce _LEGACY and _MBEDTLS kconfigs for RSA helper legacy and
> MbedTLS implementations respectively.
>
> Signed-off-by: Raymond Mao <raymond.mao at linaro.org>
> ---
> Changes in v2
> - Initial patch.
> Changes in v3
> - None.
> Changes in v4
> - Introduce _LEGACY and _MBEDTLS kconfigs for RSA helper legacy and
> MbedTLS implementations respectively.
> - Remove unnecessary type casting.
> Changes in v5
> - Correct header file include directories.
> - Correct kconfig dependence.
> - Kconfig rename.
> - Refactored MbedTLS makefile.
> Changes in v6
> - None.
>
> lib/mbedtls/Kconfig | 36 +++++++++++++++
> lib/mbedtls/Makefile | 3 +-
> lib/mbedtls/rsa_helper.c | 95 ++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 133 insertions(+), 1 deletion(-)
> create mode 100644 lib/mbedtls/rsa_helper.c
>
> diff --git a/lib/mbedtls/Kconfig b/lib/mbedtls/Kconfig
> index ecdf4d3008f..797da0df938 100644
> --- a/lib/mbedtls/Kconfig
> +++ b/lib/mbedtls/Kconfig
> @@ -119,11 +119,13 @@ config LEGACY_CRYPTO_CERT
> bool "legacy certificate libraries"
> select ASYMMETRIC_PUBLIC_KEY_LEGACY if \
> ASYMMETRIC_PUBLIC_KEY_SUBTYPE
> + select RSA_PUBLIC_KEY_PARSER_LEGACY if RSA_PUBLIC_KEY_PARSER
> select X509_CERTIFICATE_PARSER_LEGACY if X509_CERTIFICATE_PARSER
> select PKCS7_MESSAGE_PARSER_LEGACY if PKCS7_MESSAGE_PARSER
> select MSCODE_PARSER_LEGACY if MSCODE_PARSER
> select SPL_ASYMMETRIC_PUBLIC_KEY_LEGACY if \
> SPL_ASYMMETRIC_PUBLIC_KEY_SUBTYPE
> + select SPL_RSA_PUBLIC_KEY_PARSER_LEGACY if SPL_RSA_PUBLIC_KEY_PARSER
> help
> Enable legacy certificate libraries.
>
> @@ -136,6 +138,14 @@ config ASYMMETRIC_PUBLIC_KEY_LEGACY
> This option chooses legacy certificate library for asymmetric public
> key crypto algorithm.
>
> +config RSA_PUBLIC_KEY_PARSER_LEGACY
> + bool "RSA public key parser with legacy certificate library"
> + depends on ASYMMETRIC_PUBLIC_KEY_LEGACY
> + select ASN1_DECODER_LEGACY
> + help
> + This option chooses legacy certificate library for RSA public key
> + parser.
> +
> config X509_CERTIFICATE_PARSER_LEGACY
> bool "X.509 certificate parser with legacy certificate library"
> depends on ASYMMETRIC_PUBLIC_KEY_LEGACY
> @@ -169,6 +179,14 @@ config SPL_ASYMMETRIC_PUBLIC_KEY_LEGACY
> This option chooses legacy certificate library for asymmetric public
> key crypto algorithm in SPL.
>
> +config SPL_RSA_PUBLIC_KEY_PARSER_LEGACY
> + bool "RSA public key parser with legacy certificate library in SPL"
> + depends on SPL_ASYMMETRIC_PUBLIC_KEY_LEGACY
> + select SPL_ASN1_DECODER_LEGACY
> + help
> + This option chooses legacy certificate library for RSA public key
> + parser in SPL.
> +
> endif # SPL
>
> endif # LEGACY_CRYPTO_CERT
> @@ -301,11 +319,13 @@ config MBEDTLS_LIB_X509
> bool "MbedTLS certificate libraries"
> select ASYMMETRIC_PUBLIC_KEY_MBEDTLS if \
> ASYMMETRIC_PUBLIC_KEY_SUBTYPE
> + select RSA_PUBLIC_KEY_PARSER_MBEDTLS if RSA_PUBLIC_KEY_PARSER
> select X509_CERTIFICATE_PARSER_MBEDTLS if X509_CERTIFICATE_PARSER
> select PKCS7_MESSAGE_PARSER_MBEDTLS if PKCS7_MESSAGE_PARSER
> select MSCODE_PARSER_MBEDTLS if MSCODE_PARSER
> select SPL_ASYMMETRIC_PUBLIC_KEY_MBEDTLS if \
> SPL_ASYMMETRIC_PUBLIC_KEY_SUBTYPE
> + select SPL_RSA_PUBLIC_KEY_PARSER_MBEDTLS if SPL_RSA_PUBLIC_KEY_PARSER
> help
> Enable MbedTLS certificate libraries.
>
> @@ -318,6 +338,14 @@ config ASYMMETRIC_PUBLIC_KEY_MBEDTLS
> This option chooses MbedTLS certificate library for asymmetric public
> key crypto algorithm.
>
> +config RSA_PUBLIC_KEY_PARSER_MBEDTLS
> + bool "RSA public key parser with MbedTLS certificate library"
> + depends on ASYMMETRIC_PUBLIC_KEY_MBEDTLS
> + select ASN1_DECODER_MBEDTLS
> + help
> + This option chooses MbedTLS certificate library for RSA public key
> + parser.
> +
> config X509_CERTIFICATE_PARSER_MBEDTLS
> bool "X.509 certificate parser with MbedTLS certificate library"
> depends on ASYMMETRIC_PUBLIC_KEY_MBEDTLS
> @@ -351,6 +379,14 @@ config SPL_ASYMMETRIC_PUBLIC_KEY_MBEDTLS
> This option chooses MbedTLS certificate library for asymmetric public
> key crypto algorithm in SPL.
>
> +config SPL_RSA_PUBLIC_KEY_PARSER_MBEDTLS
> + bool "RSA public key parser with MbedTLS certificate library in SPL"
> + depends on SPL_ASYMMETRIC_PUBLIC_KEY_MBEDTLS
> + select SPL_ASN1_DECODER_MBEDTLS
> + help
> + This option chooses MbedTLS certificate library for RSA public key
> + parser in SPL.
> +
> endif # SPL
>
> endif # MBEDTLS_LIB_X509
> diff --git a/lib/mbedtls/Makefile b/lib/mbedtls/Makefile
> index 83333b1b6a5..40031994708 100644
> --- a/lib/mbedtls/Makefile
> +++ b/lib/mbedtls/Makefile
> @@ -18,6 +18,7 @@ obj-$(CONFIG_$(SPL_)X509_CERTIFICATE_PARSER_MBEDTLS) += \
> x509_cert_parser.o
> obj-$(CONFIG_$(SPL_)PKCS7_MESSAGE_PARSER_MBEDTLS) += pkcs7_parser.o
> obj-$(CONFIG_$(SPL_)MSCODE_PARSER_MBEDTLS) += mscode_parser.o
> +obj-$(CONFIG_$(SPL_)RSA_PUBLIC_KEY_PARSER_MBEDTLS) += rsa_helper.o
>
> # MbedTLS crypto library
> obj-$(CONFIG_MBEDTLS_LIB_CRYPTO) += mbedtls_lib_crypto.o
> @@ -39,7 +40,7 @@ mbedtls_lib_x509-$(CONFIG_$(SPL_)ASN1_DECODER) += \
> $(MBEDTLS_LIB_DIR)/asn1parse.o \
> $(MBEDTLS_LIB_DIR)/asn1write.o \
> $(MBEDTLS_LIB_DIR)/oid.o
> -mbedtls_lib_x509-$(CONFIG_$(SPL_)RSA_PUBLIC_KEY_PARSER) += \
> +mbedtls_lib_x509-$(CONFIG_$(SPL_)RSA_PUBLIC_KEY_PARSER_MBEDTLS) += \
> $(MBEDTLS_LIB_DIR)/bignum.o \
> $(MBEDTLS_LIB_DIR)/bignum_core.o \
> $(MBEDTLS_LIB_DIR)/rsa.o \
> diff --git a/lib/mbedtls/rsa_helper.c b/lib/mbedtls/rsa_helper.c
> new file mode 100644
> index 00000000000..3d94eee9954
> --- /dev/null
> +++ b/lib/mbedtls/rsa_helper.c
> @@ -0,0 +1,95 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * RSA helper functions using MbedTLS
> + *
> + * Copyright (c) 2024 Linaro Limited
> + * Author: Raymond Mao <raymond.mao at linaro.org>
> + */
> +
> +#include <linux/err.h>
> +#include <crypto/internal/rsa.h>
> +#include <library/common.h>
> +#include <mbedtls/pk.h>
> +#include <mbedtls/rsa.h>
> +#include <mbedtls/asn1.h>
> +
> +/**
> + * rsa_parse_pub_key() - decodes the BER encoded buffer and stores in the
> + * provided struct rsa_key, pointers to the raw key as is,
> + * so that the caller can copy it or MPI parse it, etc.
> + *
> + * @rsa_key: struct rsa_key key representation
> + * @key: key in BER format
> + * @key_len: length of key
> + *
> + * Return: 0 on success or error code in case of error
> + */
> +int rsa_parse_pub_key(struct rsa_key *rsa_key, const void *key,
> + unsigned int key_len)
> +{
> + int ret = 0;
> + mbedtls_pk_context pk;
> + mbedtls_rsa_context *rsa;
> +
> + mbedtls_pk_init(&pk);
> +
> + ret = mbedtls_pk_parse_public_key(&pk, (const unsigned char *)key,
> + key_len);
> + if (ret) {
> + pr_err("Failed to parse public key, ret:-0x%04x\n", -ret);
> + ret = -EINVAL;
> + goto clean_pubkey;
> + }
> +
> + /* Ensure that it is a RSA key */
> + if (mbedtls_pk_get_type(&pk) != MBEDTLS_PK_RSA) {
> + pr_err("Non-RSA keys are not supported\n");
> + ret = -EKEYREJECTED;
> + goto clean_pubkey;
> + }
> +
> + /* Get RSA key context */
> + rsa = mbedtls_pk_rsa(pk);
> + if (!rsa) {
> + pr_err("Failed to get RSA key context, ret:-0x%04x\n", -ret);
> + ret = -EINVAL;
> + goto clean_pubkey;
> + }
> +
> + /* Parse modulus (n) */
> + rsa_key->n_sz = mbedtls_mpi_size(&rsa->N);
> + rsa_key->n = kzalloc(rsa_key->n_sz, GFP_KERNEL);
> + if (!rsa_key->n) {
> + ret = -ENOMEM;
> + goto clean_pubkey;
> + }
> + ret = mbedtls_mpi_write_binary(&rsa->N, (unsigned char *)rsa_key->n,
> + rsa_key->n_sz);
> + if (ret) {
> + pr_err("Failed to parse modulus (n), ret:-0x%04x\n", -ret);
> + ret = -EINVAL;
> + goto clean_modulus;
> + }
> +
> + /* Parse public exponent (e) */
> + rsa_key->e_sz = mbedtls_mpi_size(&rsa->E);
> + rsa_key->e = kzalloc(rsa_key->e_sz, GFP_KERNEL);
> + if (!rsa_key->e) {
> + ret = -ENOMEM;
> + goto clean_modulus;
> + }
> + ret = mbedtls_mpi_write_binary(&rsa->E, (unsigned char *)rsa_key->e,
> + rsa_key->e_sz);
> + if (!ret)
> + return 0;
> +
> + pr_err("Failed to parse public exponent (e), ret:-0x%04x\n", -ret);
> + ret = -EINVAL;
> +
> + kfree(rsa_key->e);
> +clean_modulus:
> + kfree(rsa_key->n);
> +clean_pubkey:
> + mbedtls_pk_free(&pk);
> + return ret;
> +}
> --
> 2.25.1
>
Acked-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
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