[PATCH v4 25/29] mbedtls: add RSA helper layer on MbedTLS
Raymond Mao
raymond.mao at linaro.org
Tue Jul 2 20:23:01 CEST 2024
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.
- Minor fix of the include directories.
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 d8a8f87e031..87c500d6ca9 100644
--- a/lib/mbedtls/Kconfig
+++ b/lib/mbedtls/Kconfig
@@ -124,11 +124,13 @@ config LEGACY_CRYPTO_CERT
bool "legacy certificate libraries"
select ASYMMETRIC_PUBLIC_KEY_SUBTYPE_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_SUBTYPE_LEGACY if \
ASYMMETRIC_PUBLIC_KEY_SUBTYPE && SPL
+ select SPL_RSA_PUBLIC_KEY_PARSER_LEGACY if RSA_PUBLIC_KEY_PARSER && SPL
help
Enable legacy certificate libraries.
@@ -141,6 +143,14 @@ config ASYMMETRIC_PUBLIC_KEY_SUBTYPE_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_SUBTYPE_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_SUBTYPE_LEGACY
@@ -174,6 +184,14 @@ config SPL_ASYMMETRIC_PUBLIC_KEY_SUBTYPE_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_SUBTYPE_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
@@ -287,11 +305,13 @@ config MBEDTLS_LIB_X509
bool "MbedTLS certificate libraries"
select ASYMMETRIC_PUBLIC_KEY_SUBTYPE_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_SUBTYPE_MBEDTLS if \
ASYMMETRIC_PUBLIC_KEY_SUBTYPE && SPL
+ select SPL_RSA_PUBLIC_KEY_PARSER_MBEDTLS if RSA_PUBLIC_KEY_PARSER && SPL
help
Enable MbedTLS certificate libraries.
@@ -303,6 +323,14 @@ config ASYMMETRIC_PUBLIC_KEY_SUBTYPE_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_SUBTYPE_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_SUBTYPE_MBEDTLS
@@ -334,6 +362,14 @@ config SPL_ASYMMETRIC_PUBLIC_KEY_SUBTYPE_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_SUBTYPE_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 ac7c487449d..9c6991f8783 100644
--- a/lib/mbedtls/Makefile
+++ b/lib/mbedtls/Makefile
@@ -28,6 +28,7 @@ x509_mbedtls-$(CONFIG_$(SPL_)X509_CERTIFICATE_PARSER_MBEDTLS) += \
x509_cert_parser.o
x509_mbedtls-$(CONFIG_$(SPL_)PKCS7_MESSAGE_PARSER_MBEDTLS) += pkcs7_parser.o
x509_mbedtls-$(CONFIG_$(SPL_)MSCODE_PARSER_MBEDTLS) += mscode_parser.o
+x509_mbedtls-$(CONFIG_$(SPL_)RSA_PUBLIC_KEY_PARSER_MBEDTLS) += rsa_helper.o
# MbedTLS crypto library
obj-$(CONFIG_MBEDTLS_LIB_CRYPTO) += mbedtls_lib_crypto.o
@@ -49,7 +50,7 @@ mbedtls_lib_x509-$(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
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