diff options
Diffstat (limited to 'drivers/auth/mbedtls/mbedtls_crypto.c')
| -rw-r--r-- | drivers/auth/mbedtls/mbedtls_crypto.c | 394 |
1 files changed, 394 insertions, 0 deletions
diff --git a/drivers/auth/mbedtls/mbedtls_crypto.c b/drivers/auth/mbedtls/mbedtls_crypto.c new file mode 100644 index 0000000..d231179 --- /dev/null +++ b/drivers/auth/mbedtls/mbedtls_crypto.c @@ -0,0 +1,394 @@ +/* + * Copyright (c) 2015-2022, Arm Limited and Contributors. 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/x509.h> + +#include <common/debug.h> +#include <drivers/auth/crypto_mod.h> +#include <drivers/auth/mbedtls/mbedtls_common.h> +#include <drivers/auth/mbedtls/mbedtls_config.h> +#include <plat/common/platform.h> + +#define LIB_NAME "mbed TLS" + +#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 */ + +/* + * 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 + * } + */ + +/* + * Initialize the library and export the descriptor + */ +static void init(void) +{ + /* Initialize mbed TLS */ + mbedtls_init(); +} + +#if CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_ONLY || \ +CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC +/* + * 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; + mbedtls_pk_context pk = {0}; + int rc; + void *sig_opts = NULL; + const mbedtls_md_info_t *md_info; + unsigned char *p, *end; + unsigned char hash[MBEDTLS_MD_MAX_SIZE]; + + /* 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; + } + + /* Parse the public key */ + mbedtls_pk_init(&pk); + p = (unsigned char *)pk_ptr; + end = (unsigned char *)(p + pk_len); + rc = mbedtls_pk_parse_subpubkey(&p, end, &pk); + if (rc != 0) { + rc = CRYPTO_ERR_SIGNATURE; + goto end2; + } + + /* 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) { + rc = CRYPTO_ERR_SIGNATURE; + goto end1; + } + signature.p = p; + + /* Calculate the hash of the data */ + md_info = mbedtls_md_info_from_type(md_alg); + if (md_info == NULL) { + rc = CRYPTO_ERR_SIGNATURE; + goto end1; + } + p = (unsigned char *)data_ptr; + rc = mbedtls_md(md_info, p, data_len, hash); + if (rc != 0) { + rc = CRYPTO_ERR_SIGNATURE; + goto end1; + } + + /* Verify the signature */ + rc = mbedtls_pk_verify_ext(pk_alg, sig_opts, &pk, md_alg, hash, + mbedtls_md_get_size(md_info), + signature.p, signature.len); + if (rc != 0) { + rc = CRYPTO_ERR_SIGNATURE; + goto end1; + } + + /* Signature verification success */ + rc = CRYPTO_SUCCESS; + +end1: + mbedtls_pk_free(&pk); +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; + const mbedtls_md_info_t *md_info; + unsigned char *p, *end, *hash; + unsigned char data_hash[MBEDTLS_MD_MAX_SIZE]; + size_t len; + int rc; + + /* Digest info should be an MBEDTLS_ASN1_SEQUENCE */ + 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; + } + + /* 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; + } + + md_info = mbedtls_md_info_from_type(md_alg); + if (md_info == NULL) { + 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 != mbedtls_md_get_size(md_info)) { + return CRYPTO_ERR_HASH; + } + hash = p; + + /* Calculate the hash of the data */ + p = (unsigned char *)data_ptr; + rc = mbedtls_md(md_info, p, data_len, data_hash); + if (rc != 0) { + return CRYPTO_ERR_HASH; + } + + /* Compare values */ + rc = memcmp(data_hash, hash, mbedtls_md_get_size(md_info)); + if (rc != 0) { + 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]) +{ + const mbedtls_md_info_t *md_info; + + md_info = mbedtls_md_info_from_type(md_type(md_algo)); + if (md_info == NULL) { + return CRYPTO_ERR_HASH; + } + + /* + * 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. + */ + return mbedtls_md(md_info, data_ptr, data_len, output); +} +#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; + + mbedtls_gcm_init(&ctx); + + rc = mbedtls_gcm_setkey(&ctx, cipher, key, key_len * 8); + if (rc != 0) { + rc = CRYPTO_ERR_DECRYPTION; + goto exit_gcm; + } + + rc = mbedtls_gcm_starts(&ctx, MBEDTLS_GCM_DECRYPT, iv, iv_len, NULL, 0); + if (rc != 0) { + rc = CRYPTO_ERR_DECRYPTION; + goto exit_gcm; + } + + while (len > 0) { + dec_len = MIN(sizeof(buf), len); + + rc = mbedtls_gcm_update(&ctx, dec_len, pt, buf); + if (rc != 0) { + rc = CRYPTO_ERR_DECRYPTION; + goto exit_gcm; + } + + memcpy(pt, buf, dec_len); + pt += dec_len; + len -= dec_len; + } + + rc = mbedtls_gcm_finish(&ctx, tag_buf, sizeof(tag_buf)); + 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); +#else +REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, calc_hash, + 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, + auth_decrypt); +#else +REGISTER_CRYPTO_LIB(LIB_NAME, init, verify_signature, verify_hash, NULL); +#endif +#elif CRYPTO_SUPPORT == CRYPTO_HASH_CALC_ONLY +REGISTER_CRYPTO_LIB(LIB_NAME, init, calc_hash); +#endif /* CRYPTO_SUPPORT == CRYPTO_AUTH_VERIFY_AND_HASH_CALC */ |