feat(mbedtls-psa): register an ad-hoc PSA crypto driver
An ad-hoc MbedTLS PSA crypto driver is registered by compiling
a new driver file, namely mbedtls_psa_crypto.c when PSA_CRYPTO=1.
As of now, this file is the same as mbedtls_crypto.c, but subsequent
patches will update crypto functions in this file to trigger
PSA crypto APIs.
Change-Id: I404c347990661d87dcf5d0501d238e36914ec3ee
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
diff --git a/drivers/auth/mbedtls/mbedtls_psa_crypto.c b/drivers/auth/mbedtls/mbedtls_psa_crypto.c
new file mode 100644
index 0000000..eaeca79
--- /dev/null
+++ b/drivers/auth/mbedtls/mbedtls_psa_crypto.c
@@ -0,0 +1,423 @@
+/*
+ * 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 <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
+ */
+
+/*
+ * 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) || ((size_t)(end - p) != signature.len)) {
+ 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, 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;
+ }
+
+ 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 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;
+ }
+
+ /* 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;
+ 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 */