Add porting layer for public key on top of MbedTLS X509 library.
Signed-off-by: Raymond Mao raymond.mao@linaro.org --- Changes in v2 - Move the porting layer to MbedTLS dir.
lib/mbedtls/Makefile | 4 ++ lib/mbedtls/public_key.c | 105 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 109 insertions(+) create mode 100644 lib/mbedtls/public_key.c
diff --git a/lib/mbedtls/Makefile b/lib/mbedtls/Makefile index b8eda9638f4..cd0144eac1c 100644 --- a/lib/mbedtls/Makefile +++ b/lib/mbedtls/Makefile @@ -21,6 +21,10 @@ hash_mbedtls-$(CONFIG_$(SPL_)SHA1) += sha1.o hash_mbedtls-$(CONFIG_$(SPL_)SHA256) += sha256.o hash_mbedtls-$(CONFIG_$(SPL_)SHA512) += sha512.o
+# x509 libraries +obj-$(CONFIG_MBEDTLS_LIB_X509) += x509_mbedtls.o +x509_mbedtls-$(CONFIG_$(SPL_)ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += public_key.o + obj-$(CONFIG_MBEDTLS_LIB_CRYPTO) += mbedtls_lib_crypto.o mbedtls_lib_crypto-y := \ $(MBEDTLS_LIB_DIR)/aes.o \ diff --git a/lib/mbedtls/public_key.c b/lib/mbedtls/public_key.c new file mode 100644 index 00000000000..2297b4397ba --- /dev/null +++ b/lib/mbedtls/public_key.c @@ -0,0 +1,105 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Public key helper functions using MbedTLS X509 library + * + * Copyright (c) 2024 Linaro Limited + * Author: Raymond Mao raymond.mao@linaro.org + */ + +#include <linux/compat.h> +#include <crypto/public_key.h> + +void public_key_free(struct public_key *key) +{ + if (key) { + kfree(key->key); + kfree(key->params); + kfree(key); + } +} + +void public_key_signature_free(struct public_key_signature *sig) +{ + int i; + + if (sig) { + for (i = 0; i < ARRAY_SIZE(sig->auth_ids); i++) + kfree(sig->auth_ids[i]); + kfree(sig->s); + kfree(sig->digest); + kfree(sig); + } +} + +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 RedDSA) from Red Hat 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", + (unsigned int)-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; +}