| /* |
| * Copyright (c) 2023, Arm Limited. All rights reserved. |
| * |
| * SPDX-License-Identifier: BSD-3-Clause |
| */ |
| |
| #include <assert.h> |
| #include <stddef.h> |
| #include <string.h> |
| |
| /* mbed TLS headers */ |
| #include <mbedtls/gcm.h> |
| #include <mbedtls/md.h> |
| #include <mbedtls/memory_buffer_alloc.h> |
| #include <mbedtls/oid.h> |
| #include <mbedtls/platform.h> |
| #include <mbedtls/version.h> |
| #include <mbedtls/x509.h> |
| #include <psa/crypto.h> |
| #include <psa/crypto_platform.h> |
| #include <psa/crypto_types.h> |
| #include <psa/crypto_values.h> |
| |
| #include <common/debug.h> |
| #include <drivers/auth/crypto_mod.h> |
| #include <drivers/auth/mbedtls/mbedtls_common.h> |
| #include <plat/common/platform.h> |
| |
| #define LIB_NAME "mbed TLS PSA" |
| |
| #if CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY || \ |
| CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC |
| /* |
| * CRYPTO_MD_MAX_SIZE value is as per current stronger algorithm available |
| * so make sure that mbed TLS MD maximum size must be lesser than this. |
| */ |
| CASSERT(CRYPTO_MD_MAX_SIZE >= MBEDTLS_MD_MAX_SIZE, |
| assert_mbedtls_md_size_overflow); |
| |
| #endif /* |
| * CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY || \ |
| * CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC |
| */ |
| |
| static inline psa_algorithm_t mbedtls_md_psa_alg_from_type( |
| mbedtls_md_type_t md_type) |
| { |
| assert((md_type == MBEDTLS_MD_SHA256) || |
| (md_type == MBEDTLS_MD_SHA384) || |
| (md_type == MBEDTLS_MD_SHA512)); |
| |
| return PSA_ALG_CATEGORY_HASH | (psa_algorithm_t) (md_type + 0x5); |
| } |
| |
| /* |
| * 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 |
| * } |
| */ |
| |
| /* |
| * We pretend using an external RNG (through MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG |
| * mbedTLS config option) so we need to provide an implementation of |
| * mbedtls_psa_external_get_random(). Provide a fake one, since we do not |
| * actually have any external RNG and TF-A itself doesn't engage in |
| * cryptographic operations that demands randomness. |
| */ |
| psa_status_t mbedtls_psa_external_get_random( |
| mbedtls_psa_external_random_context_t *context, |
| uint8_t *output, size_t output_size, |
| size_t *output_length) |
| { |
| return PSA_ERROR_INSUFFICIENT_ENTROPY; |
| } |
| |
| /* |
| * Initialize the library and export the descriptor |
| */ |
| static void init(void) |
| { |
| /* Initialize mbed TLS */ |
| mbedtls_init(); |
| |
| /* Initialise PSA mbedTLS */ |
| psa_status_t status = psa_crypto_init(); |
| |
| if (status != PSA_SUCCESS) { |
| ERROR("Failed to initialize %s crypto (%d).\n", LIB_NAME, status); |
| panic(); |
| } |
| |
| INFO("PSA crypto initialized successfully!\n"); |
| } |
| |
| #if CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_ONLY || \ |
| CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC |
| |
| static void construct_psa_key_alg_and_type(mbedtls_pk_type_t pk_alg, |
| mbedtls_md_type_t md_alg, |
| psa_algorithm_t *psa_alg, |
| psa_key_type_t *psa_key_type) |
| { |
| psa_algorithm_t psa_md_alg = mbedtls_md_psa_alg_from_type(md_alg); |
| |
| switch (pk_alg) { |
| case MBEDTLS_PK_RSASSA_PSS: |
| *psa_alg = PSA_ALG_RSA_PSS(psa_md_alg); |
| *psa_key_type = PSA_KEY_TYPE_RSA_PUBLIC_KEY; |
| break; |
| default: |
| *psa_alg = PSA_ALG_NONE; |
| *psa_key_type = PSA_KEY_TYPE_NONE; |
| break; |
| } |
| } |
| |
| /* |
| * 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) |
| { |
| mbedtls_asn1_buf sig_oid, sig_params; |
| mbedtls_asn1_buf signature; |
| mbedtls_md_type_t md_alg; |
| mbedtls_pk_type_t pk_alg; |
| int rc; |
| void *sig_opts = NULL; |
| unsigned char *p, *end; |
| |
| /* construct PSA key algo and type */ |
| psa_status_t status = PSA_SUCCESS; |
| psa_key_attributes_t psa_key_attr = PSA_KEY_ATTRIBUTES_INIT; |
| psa_key_id_t psa_key_id = PSA_KEY_ID_NULL; |
| psa_key_type_t psa_key_type; |
| psa_algorithm_t psa_alg; |
| |
| /* Get pointers to signature OID and parameters */ |
| p = (unsigned char *)sig_alg; |
| end = (unsigned char *)(p + sig_alg_len); |
| rc = mbedtls_asn1_get_alg(&p, end, &sig_oid, &sig_params); |
| if (rc != 0) { |
| return CRYPTO_ERR_SIGNATURE; |
| } |
| |
| /* Get the actual signature algorithm (MD + PK) */ |
| rc = mbedtls_x509_get_sig_alg(&sig_oid, &sig_params, &md_alg, &pk_alg, &sig_opts); |
| if (rc != 0) { |
| return CRYPTO_ERR_SIGNATURE; |
| } |
| |
| /* Get the signature (bitstring) */ |
| p = (unsigned char *)sig_ptr; |
| end = (unsigned char *)(p + sig_len); |
| signature.tag = *p; |
| rc = mbedtls_asn1_get_bitstring_null(&p, end, &signature.len); |
| if ((rc != 0) || ((size_t)(end - p) != signature.len)) { |
| rc = CRYPTO_ERR_SIGNATURE; |
| goto end2; |
| } |
| signature.p = p; |
| |
| /* Convert this pk_alg and md_alg to PSA key type and key algorithm */ |
| construct_psa_key_alg_and_type(pk_alg, md_alg, |
| &psa_alg, &psa_key_type); |
| |
| |
| if ((psa_alg == PSA_ALG_NONE) || (psa_key_type == PSA_KEY_TYPE_NONE)) { |
| rc = CRYPTO_ERR_SIGNATURE; |
| goto end2; |
| } |
| |
| /* filled-in key_attributes */ |
| psa_set_key_algorithm(&psa_key_attr, psa_alg); |
| psa_set_key_type(&psa_key_attr, psa_key_type); |
| psa_set_key_usage_flags(&psa_key_attr, PSA_KEY_USAGE_VERIFY_MESSAGE); |
| |
| /* Get the key_id using import API */ |
| status = psa_import_key(&psa_key_attr, |
| pk_ptr, |
| (size_t)pk_len, |
| &psa_key_id); |
| |
| if (status != PSA_SUCCESS) { |
| rc = CRYPTO_ERR_SIGNATURE; |
| goto end2; |
| } |
| |
| /* |
| * Hash calculation and Signature verification of the given data payload |
| * is wrapped under the psa_verify_message function. |
| */ |
| status = psa_verify_message(psa_key_id, psa_alg, |
| data_ptr, data_len, |
| signature.p, signature.len); |
| |
| if (status != PSA_SUCCESS) { |
| rc = CRYPTO_ERR_SIGNATURE; |
| goto end1; |
| } |
| |
| /* Signature verification success */ |
| rc = CRYPTO_SUCCESS; |
| |
| end1: |
| /* |
| * Destroy the key if it is created successfully |
| */ |
| psa_destroy_key(psa_key_id); |
| end2: |
| mbedtls_free(sig_opts); |
| return rc; |
| } |
| |
| /* |
| * 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; |
| unsigned char *p, *end, *hash; |
| size_t len; |
| int rc; |
| psa_status_t status; |
| psa_algorithm_t psa_md_alg; |
| |
| /* |
| * Digest info should be an MBEDTLS_ASN1_SEQUENCE, but padding after |
| * it is allowed. This is necessary to support multiple hash |
| * algorithms. |
| */ |
| p = (unsigned char *)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; |
| } |
| |
| end = p + len; |
| |
| /* Get the hash algorithm */ |
| rc = mbedtls_asn1_get_alg(&p, end, &hash_oid, ¶ms); |
| if (rc != 0) { |
| return CRYPTO_ERR_HASH; |
| } |
| |
| /* Hash should be octet string type and consume all bytes */ |
| rc = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_OCTET_STRING); |
| if ((rc != 0) || ((size_t)(end - p) != len)) { |
| return CRYPTO_ERR_HASH; |
| } |
| hash = p; |
| |
| rc = mbedtls_oid_get_md_alg(&hash_oid, &md_alg); |
| if (rc != 0) { |
| return CRYPTO_ERR_HASH; |
| } |
| |
| /* convert the md_alg to psa_algo */ |
| psa_md_alg = mbedtls_md_psa_alg_from_type(md_alg); |
| |
| /* Length of hash must match the algorithm's size */ |
| if (len != PSA_HASH_LENGTH(psa_md_alg)) { |
| return CRYPTO_ERR_HASH; |
| } |
| |
| /* |
| * Calculate Hash and compare it against the retrieved hash from |
| * the certificate (one shot API). |
| */ |
| status = psa_hash_compare(psa_md_alg, |
| data_ptr, (size_t)data_len, |
| (const uint8_t *)hash, len); |
| |
| if (status != PSA_SUCCESS) { |
| return CRYPTO_ERR_HASH; |
| } |
| |
| return CRYPTO_SUCCESS; |
| } |
| #endif /* |
| * CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_ONLY || \ |
| * CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC |
| */ |
| |
| #if CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY || \ |
| CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC |
| /* |
| * Map a generic crypto message digest algorithm to the corresponding macro used |
| * by Mbed TLS. |
| */ |
| static inline mbedtls_md_type_t md_type(enum crypto_md_algo algo) |
| { |
| switch (algo) { |
| case CRYPTO_MD_SHA512: |
| return MBEDTLS_MD_SHA512; |
| case CRYPTO_MD_SHA384: |
| return MBEDTLS_MD_SHA384; |
| case CRYPTO_MD_SHA256: |
| return MBEDTLS_MD_SHA256; |
| default: |
| /* Invalid hash algorithm. */ |
| return MBEDTLS_MD_NONE; |
| } |
| } |
| |
| /* |
| * Calculate a hash |
| * |
| * output points to the computed hash |
| */ |
| static int calc_hash(enum crypto_md_algo md_algo, void *data_ptr, |
| unsigned int data_len, |
| unsigned char output[CRYPTO_MD_MAX_SIZE]) |
| { |
| size_t hash_length; |
| psa_status_t status; |
| psa_algorithm_t psa_md_alg; |
| |
| /* convert the md_alg to psa_algo */ |
| psa_md_alg = mbedtls_md_psa_alg_from_type(md_type(md_algo)); |
| |
| /* |
| * Calculate the hash of the data, it is safe to pass the |
| * 'output' hash buffer pointer considering its size is always |
| * bigger than or equal to MBEDTLS_MD_MAX_SIZE. |
| */ |
| status = psa_hash_compute(psa_md_alg, data_ptr, (size_t)data_len, |
| (uint8_t *)output, CRYPTO_MD_MAX_SIZE, |
| &hash_length); |
| if (status != PSA_SUCCESS) { |
| return CRYPTO_ERR_HASH; |
| } |
| |
| return CRYPTO_SUCCESS; |
| } |
| #endif /* |
| * CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY || \ |
| * CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC |
| */ |
| |
| #if TF_MBEDTLS_USE_AES_GCM |
| /* |
| * Stack based buffer allocation for decryption operation. It could |
| * be configured to balance stack usage vs execution speed. |
| */ |
| #define DEC_OP_BUF_SIZE 128 |
| |
| static int aes_gcm_decrypt(void *data_ptr, size_t len, const void *key, |
| unsigned int key_len, const void *iv, |
| unsigned int iv_len, const void *tag, |
| unsigned int tag_len) |
| { |
| mbedtls_gcm_context ctx; |
| mbedtls_cipher_id_t cipher = MBEDTLS_CIPHER_ID_AES; |
| unsigned char buf[DEC_OP_BUF_SIZE]; |
| unsigned char tag_buf[CRYPTO_MAX_TAG_SIZE]; |
| unsigned char *pt = data_ptr; |
| size_t dec_len; |
| int diff, i, rc; |
| size_t output_length __unused; |
| |
| mbedtls_gcm_init(&ctx); |
| |
| rc = mbedtls_gcm_setkey(&ctx, cipher, key, key_len * 8); |
| if (rc != 0) { |
| rc = CRYPTO_ERR_DECRYPTION; |
| goto exit_gcm; |
| } |
| |
| #if (MBEDTLS_VERSION_MAJOR < 3) |
| rc = mbedtls_gcm_starts(&ctx, MBEDTLS_GCM_DECRYPT, iv, iv_len, NULL, 0); |
| #else |
| rc = mbedtls_gcm_starts(&ctx, MBEDTLS_GCM_DECRYPT, iv, iv_len); |
| #endif |
| if (rc != 0) { |
| rc = CRYPTO_ERR_DECRYPTION; |
| goto exit_gcm; |
| } |
| |
| while (len > 0) { |
| dec_len = MIN(sizeof(buf), len); |
| |
| #if (MBEDTLS_VERSION_MAJOR < 3) |
| rc = mbedtls_gcm_update(&ctx, dec_len, pt, buf); |
| #else |
| rc = mbedtls_gcm_update(&ctx, pt, dec_len, buf, sizeof(buf), &output_length); |
| #endif |
| |
| if (rc != 0) { |
| rc = CRYPTO_ERR_DECRYPTION; |
| goto exit_gcm; |
| } |
| |
| memcpy(pt, buf, dec_len); |
| pt += dec_len; |
| len -= dec_len; |
| } |
| |
| #if (MBEDTLS_VERSION_MAJOR < 3) |
| rc = mbedtls_gcm_finish(&ctx, tag_buf, sizeof(tag_buf)); |
| #else |
| rc = mbedtls_gcm_finish(&ctx, NULL, 0, &output_length, tag_buf, sizeof(tag_buf)); |
| #endif |
| |
| if (rc != 0) { |
| rc = CRYPTO_ERR_DECRYPTION; |
| goto exit_gcm; |
| } |
| |
| /* Check tag in "constant-time" */ |
| for (diff = 0, i = 0; i < tag_len; i++) |
| diff |= ((const unsigned char *)tag)[i] ^ tag_buf[i]; |
| |
| if (diff != 0) { |
| rc = CRYPTO_ERR_DECRYPTION; |
| goto exit_gcm; |
| } |
| |
| /* GCM decryption success */ |
| rc = CRYPTO_SUCCESS; |
| |
| exit_gcm: |
| mbedtls_gcm_free(&ctx); |
| return rc; |
| } |
| |
| /* |
| * Authenticated decryption of an image |
| */ |
| static int auth_decrypt(enum crypto_dec_algo dec_algo, void *data_ptr, |
| size_t len, const void *key, unsigned int key_len, |
| unsigned int key_flags, const void *iv, |
| unsigned int iv_len, const void *tag, |
| unsigned int tag_len) |
| { |
| int rc; |
| |
| assert((key_flags & ENC_KEY_IS_IDENTIFIER) == 0); |
| |
| switch (dec_algo) { |
| case CRYPTO_GCM_DECRYPT: |
| rc = aes_gcm_decrypt(data_ptr, len, key, key_len, iv, iv_len, |
| tag, tag_len); |
| if (rc != 0) |
| return rc; |
| break; |
| default: |
| return CRYPTO_ERR_DECRYPTION; |
| } |
| |
| return CRYPTO_SUCCESS; |
| } |
| #endif /* TF_MBEDTLS_USE_AES_GCM */ |
| |
| /* |
| * Register crypto library descriptor |
| */ |
| #if CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC |
| #if TF_MBEDTLS_USE_AES_GCM |
| REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, calc_hash, |
| auth_decrypt, NULL); |
| #else |
| REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, calc_hash, |
| NULL, NULL); |
| #endif |
| #elif CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_ONLY |
| #if TF_MBEDTLS_USE_AES_GCM |
| REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, NULL, |
| auth_decrypt, NULL); |
| #else |
| REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, NULL, |
| NULL, NULL); |
| #endif |
| #elif CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY |
| REGISTER_CRYPTO_LIB(LIB_NAME, init, NULL, NULL, calc_hash, NULL, NULL); |
| #endif /* CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC */ |