Add CC crypto driver to the Auth module
This patch adds a crypto driver which utilizes the ARM® TrustZone®
CryptoCell-712 to verify signature and hash during Trusted Board Boot. Along
with this driver, the CryptoCell SBROM library is required to successfully
build the BL image. The path to this library is specified via
the `CCSBROM_LIB_PATH` variable. Please note that, mbedTLS is still required
to do the X509 certificate ASN.1 parsing and CryptoCell is only utilized for
signature and hash verification.
Change-Id: If82dfbae0d7772ba1c64839f0b27850c103fe253
Signed-off-by: Soby Mathew <soby.mathew@arm.com>
diff --git a/drivers/auth/cryptocell/cryptocell_crypto.c b/drivers/auth/cryptocell/cryptocell_crypto.c
new file mode 100644
index 0000000..bf7dff4
--- /dev/null
+++ b/drivers/auth/cryptocell/cryptocell_crypto.c
@@ -0,0 +1,290 @@
+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch_helpers.h>
+#include <crypto_mod.h>
+#include <crypto_driver.h>
+#include <debug.h>
+#include <mbedtls_common.h>
+#include <platform_def.h>
+#include <rsa.h>
+#include <sbrom_bsv_api.h>
+#include <secureboot_base_func.h>
+#include <secureboot_gen_defs.h>
+#include <stddef.h>
+#include <string.h>
+#include <utils.h>
+#include <util.h>
+
+#include <mbedtls/oid.h>
+
+#define LIB_NAME "CryptoCell SBROM"
+#define RSA_SALT_LEN 32
+#define RSA_EXPONENT 65537
+
+/*
+ * AlgorithmIdentifier ::= SEQUENCE {
+ * algorithm OBJECT IDENTIFIER,
+ * parameters ANY DEFINED BY algorithm OPTIONAL
+ * }
+ *
+ * SubjectPublicKeyInfo ::= SEQUENCE {
+ * algorithm AlgorithmIdentifier,
+ * subjectPublicKey BIT STRING
+ * }
+ *
+ * DigestInfo ::= SEQUENCE {
+ * digestAlgorithm AlgorithmIdentifier,
+ * digest OCTET STRING
+ * }
+ *
+ * RSASSA-PSS-params ::= SEQUENCE {
+ * hashAlgorithm [0] HashAlgorithm,
+ * maskGenAlgorithm [1] MaskGenAlgorithm,
+ * saltLength [2] INTEGER,
+ * trailerField [3] TrailerField DEFAULT trailerFieldBC
+ * }
+ */
+
+/*
+ * Initialize the library and export the descriptor
+ */
+static void init(void)
+{
+ CCError_t ret;
+
+ /* Initialize CC SBROM */
+ ret = CC_BsvSbromInit((uintptr_t)PLAT_CRYPTOCELL_BASE);
+ if (ret != CC_OK) {
+ ERROR("CryptoCell CC_BsvSbromInit() error %x\n", ret);
+ panic();
+ }
+}
+
+/*
+ * Verify a signature.
+ *
+ * Parameters are passed using the DER encoding format following the ASN.1
+ * structures detailed above.
+ */
+static int verify_signature(void *data_ptr, unsigned int data_len,
+ void *sig_ptr, unsigned int sig_len,
+ void *sig_alg, unsigned int sig_alg_len,
+ void *pk_ptr, unsigned int pk_len)
+{
+ CCError_t error;
+ CCSbNParams_t pk;
+ CCSbSignature_t signature;
+ int rc, exp;
+ mbedtls_asn1_buf sig_oid, alg_oid, params;
+ mbedtls_md_type_t md_alg;
+ mbedtls_pk_type_t pk_alg;
+ mbedtls_pk_rsassa_pss_options pss_opts;
+ size_t len;
+ uint8_t *p, *end;
+ /* Temp buf to store the public key modulo (N) in LE format */
+ uint32_t RevN[SB_RSA_MOD_SIZE_IN_WORDS];
+
+ /* Verify the signature algorithm */
+ /* Get pointers to signature OID and parameters */
+ p = sig_alg;
+ end = p + sig_alg_len;
+ rc = mbedtls_asn1_get_alg(&p, end, &sig_oid, ¶ms);
+ if (rc != 0)
+ return CRYPTO_ERR_SIGNATURE;
+
+ /* Get the actual signature algorithm (MD + PK) */
+ rc = mbedtls_oid_get_sig_alg(&sig_oid, &md_alg, &pk_alg);
+ if (rc != 0)
+ return CRYPTO_ERR_SIGNATURE;
+
+ /* The CryptoCell only supports RSASSA-PSS signature */
+ if (pk_alg != MBEDTLS_PK_RSASSA_PSS || md_alg != MBEDTLS_MD_NONE)
+ return CRYPTO_ERR_SIGNATURE;
+
+ /* Verify the RSASSA-PSS params */
+ /* The trailer field is verified to be 0xBC internally by this API */
+ rc = mbedtls_x509_get_rsassa_pss_params(¶ms, &md_alg,
+ &pss_opts.mgf1_hash_id,
+ &pss_opts.expected_salt_len);
+ if (rc != 0)
+ return CRYPTO_ERR_SIGNATURE;
+
+ /* The CryptoCell only supports SHA256 as hash algorithm */
+ if (md_alg != MBEDTLS_MD_SHA256 || pss_opts.mgf1_hash_id != MBEDTLS_MD_SHA256)
+ return CRYPTO_ERR_SIGNATURE;
+
+ if (pss_opts.expected_salt_len != RSA_SALT_LEN)
+ return CRYPTO_ERR_SIGNATURE;
+
+ /* Parse the public key */
+ p = pk_ptr;
+ end = p + pk_len;
+ rc = mbedtls_asn1_get_tag(&p, end, &len,
+ MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE);
+ if (rc != 0)
+ return CRYPTO_ERR_SIGNATURE;
+
+ end = p + len;
+ rc = mbedtls_asn1_get_alg_null(&p, end, &alg_oid);
+ if (rc != 0)
+ return CRYPTO_ERR_SIGNATURE;
+
+ if (mbedtls_oid_get_pk_alg(&alg_oid, &pk_alg) != 0)
+ return CRYPTO_ERR_SIGNATURE;
+
+ if (pk_alg != MBEDTLS_PK_RSA)
+ return CRYPTO_ERR_SIGNATURE;
+
+ rc = mbedtls_asn1_get_bitstring_null(&p, end, &len);
+ if (rc != 0)
+ return CRYPTO_ERR_SIGNATURE;
+
+ rc = mbedtls_asn1_get_tag(&p, end, &len,
+ MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE);
+ if (rc != 0)
+ return CRYPTO_ERR_SIGNATURE;
+
+ rc = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_INTEGER);
+ if (rc != 0)
+ return CRYPTO_ERR_SIGNATURE;
+
+ if (*p == 0) {
+ p++; len--;
+ }
+ if (len != RSA_MOD_SIZE_IN_BYTES || ((p + len) > end))
+ return CRYPTO_ERR_SIGNATURE;
+
+ /*
+ * The CCSbVerifySignature() API expects N and Np in BE format and
+ * the signature in LE format. Copy N from certificate.
+ */
+ memcpy(pk.N, p, RSA_MOD_SIZE_IN_BYTES);
+
+ /* Verify the RSA exponent */
+ p += len;
+ rc = mbedtls_asn1_get_int(&p, end, &exp);
+ if (rc != 0)
+ return CRYPTO_ERR_SIGNATURE;
+
+ if (exp != RSA_EXPONENT)
+ return CRYPTO_ERR_SIGNATURE;
+
+ /*
+ * Calculate the Np (Barrett n' value). The RSA_CalcNp() API expects
+ * N in LE format. Hence reverse N into a temporary buffer `RevN`.
+ */
+ UTIL_ReverseMemCopy((uint8_t *)RevN, (uint8_t *)pk.N, sizeof(RevN));
+
+ RSA_CalcNp((uintptr_t)PLAT_CRYPTOCELL_BASE, RevN, pk.Np);
+
+ /* Np is in LE format. Reverse it to BE */
+ UTIL_ReverseBuff((uint8_t *)pk.Np, sizeof(pk.Np));
+
+ /* Get the signature (bitstring) */
+ p = sig_ptr;
+ end = p + sig_len;
+ rc = mbedtls_asn1_get_bitstring_null(&p, end, &len);
+ if (rc != 0)
+ return CRYPTO_ERR_SIGNATURE;
+
+ if (len != RSA_MOD_SIZE_IN_BYTES || ((p + len) > end))
+ return CRYPTO_ERR_SIGNATURE;
+
+ /*
+ * The signature is BE format. Convert it to LE before calling
+ * CCSbVerifySignature().
+ */
+ UTIL_ReverseMemCopy((uint8_t *)signature.sig, p, RSA_MOD_SIZE_IN_BYTES);
+
+ /*
+ * CryptoCell utilises DMA internally to transfer data. Flush the data
+ * from caches.
+ */
+ flush_dcache_range((uintptr_t)data_ptr, data_len);
+
+ /* Verify the signature */
+ error = CCSbVerifySignature((uintptr_t)PLAT_CRYPTOCELL_BASE,
+ (uint32_t *)data_ptr, &pk, &signature,
+ data_len, RSA_PSS_2048);
+ if (error != CC_OK)
+ return CRYPTO_ERR_SIGNATURE;
+
+ /* Signature verification success */
+ return CRYPTO_SUCCESS;
+}
+
+/*
+ * Match a hash
+ *
+ * Digest info is passed in DER format following the ASN.1 structure detailed
+ * above.
+ */
+static int verify_hash(void *data_ptr, unsigned int data_len,
+ void *digest_info_ptr, unsigned int digest_info_len)
+{
+ mbedtls_asn1_buf hash_oid, params;
+ mbedtls_md_type_t md_alg;
+ uint8_t *p, *end, *hash;
+ CCHashResult_t pubKeyHash;
+ size_t len;
+ int rc;
+ CCError_t error;
+
+ /* Digest info should be an MBEDTLS_ASN1_SEQUENCE */
+ p = digest_info_ptr;
+ end = p + digest_info_len;
+ rc = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_CONSTRUCTED |
+ MBEDTLS_ASN1_SEQUENCE);
+ if (rc != 0)
+ return CRYPTO_ERR_HASH;
+
+ /* Get the hash algorithm */
+ rc = mbedtls_asn1_get_alg(&p, end, &hash_oid, ¶ms);
+ if (rc != 0)
+ return CRYPTO_ERR_HASH;
+
+ rc = mbedtls_oid_get_md_alg(&hash_oid, &md_alg);
+ if (rc != 0)
+ return CRYPTO_ERR_HASH;
+ /* Verify that hash algorithm is SHA256 */
+ if (md_alg != MBEDTLS_MD_SHA256)
+ return CRYPTO_ERR_HASH;
+
+ /* Hash should be octet string type */
+ rc = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_OCTET_STRING);
+ if (rc != 0)
+ return CRYPTO_ERR_HASH;
+
+ /* Length of hash must match the algorithm's size */
+ if (len != HASH_RESULT_SIZE_IN_BYTES)
+ return CRYPTO_ERR_HASH;
+
+ /*
+ * CryptoCell utilises DMA internally to transfer data. Flush the data
+ * from caches.
+ */
+ flush_dcache_range((uintptr_t)data_ptr, data_len);
+
+ hash = p;
+ error = SBROM_CryptoHash((uintptr_t)PLAT_CRYPTOCELL_BASE,
+ (uintptr_t)data_ptr, data_len, pubKeyHash);
+ if (error != CC_OK)
+ return CRYPTO_ERR_HASH;
+
+ rc = memcmp(pubKeyHash, hash, HASH_RESULT_SIZE_IN_BYTES);
+ if (rc != 0)
+ return CRYPTO_ERR_HASH;
+
+ return CRYPTO_SUCCESS;
+}
+
+/*
+ * Register crypto library descriptor
+ */
+REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash);
+
+