diff options
Diffstat (limited to 'drivers/io/io_encrypted.c')
| -rw-r--r-- | drivers/io/io_encrypted.c | 244 |
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; +} |