On Sat, 17 Aug 2024 at 00:51, Raymond Mao <raymond....@linaro.org> wrote:
>
> Add porting layer for public key on top of MbedTLS X509 library.
> Introduce _LEGACY and _MBEDTLS kconfigs for public key legacy and
> MbedTLS implementations respectively.
>
> Signed-off-by: Raymond Mao <raymond....@linaro.org>
> ---
> Changes in v2
> - Move the porting layer to MbedTLS dir.
> Changes in v3
> - None.
> Changes in v4
> - Introduce _LEGACY and _MBEDTLS kconfigs for public key legacy and
> MbedTLS implementations respectively.
> - Move common functions to helper.
> Changes in v5
> - Correct kconfig dependence.
> - Kconfig rename.
> - Refactored MbedTLS makefile.
> - Adjust a few inline comments.
> Changes in v6
> - None.
>
> lib/mbedtls/Kconfig | 52 +++++++++++++++++++++++++
> lib/mbedtls/Makefile | 6 ++-
> lib/mbedtls/public_key.c | 82 ++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 139 insertions(+), 1 deletion(-)
> create mode 100644 lib/mbedtls/public_key.c
>
> diff --git a/lib/mbedtls/Kconfig b/lib/mbedtls/Kconfig
> index 0e22edf1b6c..dbbcdba8bc6 100644
> --- a/lib/mbedtls/Kconfig
> +++ b/lib/mbedtls/Kconfig
> @@ -117,9 +117,35 @@ endif # LEGACY_CRYPTO_BASIC
>
> config LEGACY_CRYPTO_CERT
> bool "legacy certificate libraries"
> + select ASYMMETRIC_PUBLIC_KEY_LEGACY if \
> + ASYMMETRIC_PUBLIC_KEY_SUBTYPE
> + select SPL_ASYMMETRIC_PUBLIC_KEY_LEGACY if \
> + SPL_ASYMMETRIC_PUBLIC_KEY_SUBTYPE
> help
> Enable legacy certificate libraries.
>
> +if LEGACY_CRYPTO_CERT
> +
> +config ASYMMETRIC_PUBLIC_KEY_LEGACY
> + bool "Asymmetric public key crypto with legacy certificate library"
> + depends on LEGACY_CRYPTO_CERT && ASYMMETRIC_PUBLIC_KEY_SUBTYPE
> + help
> + This option chooses legacy certificate library for asymmetric public
> + key crypto algorithm.
> +
> +if SPL
> +
> +config SPL_ASYMMETRIC_PUBLIC_KEY_LEGACY
> + bool "Asymmetric public key crypto with legacy certificate library in
> SPL"
> + depends on LEGACY_CRYPTO_CERT && SPL_ASYMMETRIC_PUBLIC_KEY_SUBTYPE
> + help
> + This option chooses legacy certificate library for asymmetric public
> + key crypto algorithm in SPL.
> +
> +endif # SPL
> +
> +endif # LEGACY_CRYPTO_CERT
> +
> endif # LEGACY_CRYPTO
>
> if MBEDTLS_LIB
> @@ -246,7 +272,33 @@ endif # MBEDTLS_LIB_CRYPTO
>
> config MBEDTLS_LIB_X509
> bool "MbedTLS certificate libraries"
> + select ASYMMETRIC_PUBLIC_KEY_MBEDTLS if \
> + ASYMMETRIC_PUBLIC_KEY_SUBTYPE
> + select SPL_ASYMMETRIC_PUBLIC_KEY_MBEDTLS if \
> + SPL_ASYMMETRIC_PUBLIC_KEY_SUBTYPE
> help
> Enable MbedTLS certificate libraries.
>
> +if MBEDTLS_LIB_X509
> +
> +config ASYMMETRIC_PUBLIC_KEY_MBEDTLS
> + bool "Asymmetric public key crypto with MbedTLS certificate library"
> + depends on MBEDTLS_LIB_X509 && ASYMMETRIC_PUBLIC_KEY_SUBTYPE
> + help
> + This option chooses MbedTLS certificate library for asymmetric
> public
> + key crypto algorithm.
> +
> +if SPL
> +
> +config SPL_ASYMMETRIC_PUBLIC_KEY_MBEDTLS
> + bool "Asymmetric public key crypto with MbedTLS certificate library
> in SPL"
> + depends on MBEDTLS_LIB_X509 && SPL_ASYMMETRIC_PUBLIC_KEY_SUBTYPE
> + help
> + This option chooses MbedTLS certificate library for asymmetric
> public
> + key crypto algorithm in SPL.
> +
> +endif # SPL
> +
> +endif # MBEDTLS_LIB_X509
> +
> endif # MBEDTLS_LIB
> diff --git a/lib/mbedtls/Makefile b/lib/mbedtls/Makefile
> index 50c1ba5f88e..2d2220dd4fd 100644
> --- a/lib/mbedtls/Makefile
> +++ b/lib/mbedtls/Makefile
> @@ -11,6 +11,10 @@ obj-$(CONFIG_$(SPL_)SHA1_MBEDTLS) += sha1.o
> obj-$(CONFIG_$(SPL_)SHA256_MBEDTLS) += sha256.o
> obj-$(CONFIG_$(SPL_)SHA512_MBEDTLS) += sha512.o
>
> +# x509 libraries
> +obj-$(CONFIG_$(SPL_)ASYMMETRIC_PUBLIC_KEY_MBEDTLS) += \
> + public_key.o
> +
> # MbedTLS crypto library
> obj-$(CONFIG_MBEDTLS_LIB_CRYPTO) += mbedtls_lib_crypto.o
> mbedtls_lib_crypto-y := \
> @@ -36,7 +40,7 @@ mbedtls_lib_x509-$(CONFIG_$(SPL_)RSA_PUBLIC_KEY_PARSER) += \
> $(MBEDTLS_LIB_DIR)/bignum_core.o \
> $(MBEDTLS_LIB_DIR)/rsa.o \
> $(MBEDTLS_LIB_DIR)/rsa_alt_helpers.o
> -mbedtls_lib_x509-$(CONFIG_$(SPL_)ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += \
> +mbedtls_lib_x509-$(CONFIG_$(SPL_)ASYMMETRIC_PUBLIC_KEY_MBEDTLS) += \
> $(MBEDTLS_LIB_DIR)/pk.o \
> $(MBEDTLS_LIB_DIR)/pk_wrap.o \
> $(MBEDTLS_LIB_DIR)/pkparse.o
> diff --git a/lib/mbedtls/public_key.c b/lib/mbedtls/public_key.c
> new file mode 100644
> index 00000000000..5f73b99d4f2
> --- /dev/null
> +++ b/lib/mbedtls/public_key.c
> @@ -0,0 +1,82 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Public key helper functions using MbedTLS X509 library
> + *
> + * Copyright (c) 2024 Linaro Limited
> + * Author: Raymond Mao <raymond....@linaro.org>
> + */
> +
> +#include <linux/compat.h>
> +#include <crypto/public_key.h>
> +
> +int public_key_verify_signature(const struct public_key *pkey,
> + const struct public_key_signature *sig)
> +{
> + mbedtls_md_type_t mb_hash_algo;
> + mbedtls_pk_context pk_ctx;
> + int ret;
> +
> + if (!pkey || !sig || pkey->key_is_private)
> + return -EINVAL;
> +
> + /*
> + * ECRDSA (Elliptic Curve Russian Digital Signature Algorithm) is not
> + * supported by MbedTLS.
> + */
> + if (strcmp(pkey->pkey_algo, "rsa")) {
> + pr_err("Encryption is not RSA: %s\n", sig->pkey_algo);
> + return -EINVAL;
> + }
> +
> + /*
> + * Can be pkcs1 or raw, but pkcs1 is expected.
> + * This is just for argument checking, not necessarily passed to
> MbedTLS,
> + * For RSA signatures, MbedTLS typically supports the PKCS#1 v1.5
> + * (aka. pkcs1) encoding by default.
> + * The library internally handles the details of decoding and
> verifying
> + * the signature according to the expected encoding for the specified
> algorithm.
> + */
> + if (strcmp(sig->encoding, "pkcs1")) {
> + pr_err("Encoding %s is not supported, only supports pkcs1\n",
> + sig->encoding);
> + return -EINVAL;
> + }
> +
> + if (!strcmp(sig->hash_algo, "sha1"))
> + mb_hash_algo = MBEDTLS_MD_SHA1;
> + else if (!strcmp(sig->hash_algo, "sha224"))
> + mb_hash_algo = MBEDTLS_MD_SHA224;
> + else if (!strcmp(sig->hash_algo, "sha256"))
> + mb_hash_algo = MBEDTLS_MD_SHA256;
> + else if (!strcmp(sig->hash_algo, "sha384"))
> + mb_hash_algo = MBEDTLS_MD_SHA384;
> + else if (!strcmp(sig->hash_algo, "sha512"))
> + mb_hash_algo = MBEDTLS_MD_SHA512;
> + else /* Unknown or unsupported hash algorithm */
> + return -EINVAL;
> + /* Initialize the mbedtls_pk_context with RSA key type */
> + mbedtls_pk_init(&pk_ctx);
> +
> + /* Parse the DER-encoded public key */
> + ret = mbedtls_pk_parse_public_key(&pk_ctx, pkey->key, pkey->keylen);
> + if (ret) {
> + pr_err("Failed to parse public key, ret:-0x%04x\n", -ret);
> + ret = -EINVAL;
> + goto err_key;
> + }
> +
> + /* Ensure that it is a RSA key */
> + if (mbedtls_pk_get_type(&pk_ctx) != MBEDTLS_PK_RSA) {
> + pr_err("Only RSA keys are supported\n");
> + ret = -EKEYREJECTED;
> + goto err_key;
> + }
> +
> + /* Verify the hash */
> + ret = mbedtls_pk_verify(&pk_ctx, mb_hash_algo, sig->digest,
> + sig->digest_size, sig->s, sig->s_size);
> +
> +err_key:
> + mbedtls_pk_free(&pk_ctx);
> + return ret;
> +}
> --
> 2.25.1
>
Reviewed-by: Ilias Apalodimas <ilias.apalodi...@linaro.org>
