1 files changed, 244 insertions, 0 deletions
diff --git a/drivers/io/io_encrypted.c b/drivers/io/io_encrypted.c
new file mode 100644
index 0000000..744ca83
--- /dev/null
+++ b/drivers/io/io_encrypted.c
@@ -0,0 +1,244 @@
+/*
+ * Copyright (c) 2020, Linaro Limited. All rights reserved.
+ * Author: Sumit Garg <sumit.garg@linaro.org>
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <platform_def.h>
+
+#include <common/bl_common.h>
+#include <common/debug.h>
+#include <drivers/auth/crypto_mod.h>
+#include <drivers/io/io_driver.h>
+#include <drivers/io/io_encrypted.h>
+#include <drivers/io/io_storage.h>
+#include <lib/utils.h>
+#include <plat/common/platform.h>
+#include <tools_share/firmware_encrypted.h>
+#include <tools_share/uuid.h>
+
+static uintptr_t backend_dev_handle;
+static uintptr_t backend_dev_spec;
+static uintptr_t backend_handle;
+static uintptr_t backend_image_spec;
+
+static io_dev_info_t enc_dev_info;
+
+/* Encrypted firmware driver functions */
+static int enc_dev_open(const uintptr_t dev_spec, io_dev_info_t **dev_info);
+static int enc_file_open(io_dev_info_t *dev_info, const uintptr_t spec,
+			  io_entity_t *entity);
+static int enc_file_len(io_entity_t *entity, size_t *length);
+static int enc_file_read(io_entity_t *entity, uintptr_t buffer, size_t length,
+			  size_t *length_read);
+static int enc_file_close(io_entity_t *entity);
+static int enc_dev_init(io_dev_info_t *dev_info, const uintptr_t init_params);
+static int enc_dev_close(io_dev_info_t *dev_info);
+
+static inline int is_valid_header(struct fw_enc_hdr *header)
+{
+	if (header->magic == ENC_HEADER_MAGIC)
+		return 1;
+	else
+		return 0;
+}
+
+static io_type_t device_type_enc(void)
+{
+	return IO_TYPE_ENCRYPTED;
+}
+
+static const io_dev_connector_t enc_dev_connector = {
+	.dev_open = enc_dev_open
+};
+
+static const io_dev_funcs_t enc_dev_funcs = {
+	.type = device_type_enc,
+	.open = enc_file_open,
+	.seek = NULL,
+	.size = enc_file_len,
+	.read = enc_file_read,
+	.write = NULL,
+	.close = enc_file_close,
+	.dev_init = enc_dev_init,
+	.dev_close = enc_dev_close,
+};
+
+static int enc_dev_open(const uintptr_t dev_spec, io_dev_info_t **dev_info)
+{
+	assert(dev_info != NULL);
+
+	enc_dev_info.funcs = &enc_dev_funcs;
+	*dev_info = &enc_dev_info;
+
+	return 0;
+}
+
+static int enc_dev_init(io_dev_info_t *dev_info, const uintptr_t init_params)
+{
+	int result;
+	unsigned int image_id = (unsigned int)init_params;
+
+	/* Obtain a reference to the image by querying the platform layer */
+	result = plat_get_image_source(image_id, &backend_dev_handle,
+				       &backend_dev_spec);
+	if (result != 0) {
+		WARN("Failed to obtain reference to image id=%u (%i)\n",
+			image_id, result);
+		return -ENOENT;
+	}
+
+	return result;
+}
+
+static int enc_dev_close(io_dev_info_t *dev_info)
+{
+	backend_dev_handle = (uintptr_t)NULL;
+	backend_dev_spec = (uintptr_t)NULL;
+
+	return 0;
+}
+
+static int enc_file_open(io_dev_info_t *dev_info, const uintptr_t spec,
+			 io_entity_t *entity)
+{
+	int result;
+
+	assert(spec != 0);
+	assert(entity != NULL);
+
+	backend_image_spec = spec;
+
+	result = io_open(backend_dev_handle, backend_image_spec,
+			 &backend_handle);
+	if (result != 0) {
+		WARN("Failed to open backend device (%i)\n", result);
+		result = -ENOENT;
+	}
+
+	return result;
+}
+
+static int enc_file_len(io_entity_t *entity, size_t *length)
+{
+	int result;
+
+	assert(entity != NULL);
+	assert(length != NULL);
+
+	result = io_size(backend_handle, length);
+	if (result != 0) {
+		WARN("Failed to read blob length (%i)\n", result);
+		return -ENOENT;
+	}
+
+	/*
+	 * Encryption header is attached at the beginning of the encrypted file
+	 * and is not considered a part of the payload.
+	 */
+	if (*length < sizeof(struct fw_enc_hdr))
+		return -EIO;
+
+	*length -= sizeof(struct fw_enc_hdr);
+
+	return result;
+}
+
+static int enc_file_read(io_entity_t *entity, uintptr_t buffer, size_t length,
+			 size_t *length_read)
+{
+	int result;
+	struct fw_enc_hdr header;
+	enum fw_enc_status_t fw_enc_status;
+	size_t bytes_read;
+	uint8_t key[ENC_MAX_KEY_SIZE];
+	size_t key_len = sizeof(key);
+	unsigned int key_flags = 0;
+	const io_uuid_spec_t *uuid_spec = (io_uuid_spec_t *)backend_image_spec;
+
+	assert(entity != NULL);
+	assert(length_read != NULL);
+
+	result = io_read(backend_handle, (uintptr_t)&header, sizeof(header),
+			 &bytes_read);
+	if (result != 0) {
+		WARN("Failed to read encryption header (%i)\n", result);
+		return -ENOENT;
+	}
+
+	if (!is_valid_header(&header)) {
+		WARN("Encryption header check failed.\n");
+		return -ENOENT;
+	}
+
+	VERBOSE("Encryption header looks OK.\n");
+	fw_enc_status = header.flags & FW_ENC_STATUS_FLAG_MASK;
+
+	if ((header.iv_len > ENC_MAX_IV_SIZE) ||
+	    (header.tag_len > ENC_MAX_TAG_SIZE)) {
+		WARN("Incorrect IV or tag length\n");
+		return -ENOENT;
+	}
+
+	result = io_read(backend_handle, buffer, length, &bytes_read);
+	if (result != 0) {
+		WARN("Failed to read encrypted payload (%i)\n", result);
+		return -ENOENT;
+	}
+
+	*length_read = bytes_read;
+
+	result = plat_get_enc_key_info(fw_enc_status, key, &key_len, &key_flags,
+				       (uint8_t *)&uuid_spec->uuid,
+				       sizeof(uuid_t));
+	if (result != 0) {
+		WARN("Failed to obtain encryption key (%i)\n", result);
+		return -ENOENT;
+	}
+
+	result = crypto_mod_auth_decrypt(header.dec_algo,
+					 (void *)buffer, *length_read, key,
+					 key_len, key_flags, header.iv,
+					 header.iv_len, header.tag,
+					 header.tag_len);
+	memset(key, 0, key_len);
+
+	if (result != 0) {
+		ERROR("File decryption failed (%i)\n", result);
+		return -ENOENT;
+	}
+
+	return result;
+}
+
+static int enc_file_close(io_entity_t *entity)
+{
+	io_close(backend_handle);
+
+	backend_image_spec = (uintptr_t)NULL;
+	entity->info = 0;
+
+	return 0;
+}
+
+/* Exported functions */
+
+/* Register the Encrypted Firmware driver with the IO abstraction */
+int register_io_dev_enc(const io_dev_connector_t **dev_con)
+{
+	int result;
+
+	assert(dev_con != NULL);
+
+	result = io_register_device(&enc_dev_info);
+	if (result == 0)
+		*dev_con = &enc_dev_connector;
+
+	return result;
+}