Commit d82afbfa authored by George Beckstein's avatar George Beckstein Committed by Fabio Utzig
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Mbed-OS porting layer implementation for mcuboot 

This PR provides a porting layer implementation and framework for building an mcuboot-based bootloader with Mbed-OS. Some symbols are not provided by the Mbed-OS port within mcuboot, namely:

- The secondary storage device (see below)
- The signing keys
- The encryption keys, if used

Use of this port is demonstrated by the following projects:
- https://github.com/AGlass0fMilk/mbed-mcuboot-demo (a complete mcuboot/Mbed-OS-based bootloader)
- https://github.com/AGlass0fMilk/mbed-mcuboot-blinky

 (example showing how to make an Mbed-OS application that is bootable by mcuboot)

Memory porting implementation:

The underlying implemenation uses Mbed's BlockDevice API as the storage backend for mcuboot's memory operations. This provides a very flexible way of configuring the location and layout of the secondary flash storage area. To build an mcuboot-based bootloader with Mbed-OS, the user must implement a hook function, mbed::BlockDevice* get_secondary_bd(), to provide the secondary BlockDevice that mcuboot will use.

The signing and encryption keys must also be provided by the user. They can be generated using the existing imgtool utility in the same manner used by Zephyr. There are no automated build steps currently provided by Mbed-OS to sign/encrypt build artifacts.

Known limitations:

The update candidate encryption features have not yet been fully tested. A truly secure implementation will require integration with Mbed's TRNG API in the future to inhibit side-channel attacks on the decryption process.

The TinyCrypt backend is currently only supported for Mbed-OS builds when building with the GCC toolchain. The new cmake-based Mbed-OS build system will fix the underlying issue (file name uniqueness).

Signed-off-by: default avatarGeorge Beckstein <becksteing@embeddedplanet.com>
Signed-off-by: default avatarEvelyne Donnaes <evelyne.donnaes@arm.com>
Signed-off-by: default avatarLingkai Dong <lingkai.dong@arm.com>

Co-authored-by: default avatarLingkai Dong <lingkai.dong@arm.com>
Co-authored-by: default avatarFabio Utzig <fabio.utzig@nordicsemi.no>
parent ea30ef3c

.mbedignore

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boot/boot_serial/*

boot/mynewt/*

boot/zephyr/*

boot/cypress/*

ci/*

docs/*

ptest/*

samples/*

scripts/*

sim/*

testplan/*

ext/cddl_gen/*

ext/fiat/*

ext/mbedtls/*

ext/mbedtls-asn1/*

ext/nrf/*

ext/tinycrypt/tests/*
 
 No newline at end of file

boot/mbed/app_enc_keys.c

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/*

 * Copyright (c) 2020 Embedded Planet

 * SPDX-License-Identifier: Apache-2.0

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License

 */



#include <bootutil/sign_key.h>

#include <mcuboot_config/mcuboot_config.h>



#if defined(MCUBOOT_SIGN_RSA)

#define HAVE_KEYS

extern const unsigned char rsa_pub_key[];

extern unsigned int rsa_pub_key_len;

#elif defined(MCUBOOT_SIGN_EC256)

#define HAVE_KEYS

extern const unsigned char ecdsa_pub_key[];

extern unsigned int ecdsa_pub_key_len;

#elif defined(MCUBOOT_SIGN_ED25519)

#define HAVE_KEYS

extern const unsigned char ed25519_pub_key[];

extern unsigned int ed25519_pub_key_len;

#else

#error "No public key available for given signing algorithm."

#endif



/*

 * Note: Keys for both signing and encryption must be provided by the application.

 * mcuboot's imgtool utility can be used to generate these keys and convert them into compatible C code.

 * See imgtool's documentation, specifically the section: "Incorporating the public key into the code" which can be found here:

 * https://github.com/JuulLabs-OSS/mcuboot/blob/master/docs/imgtool.md#incorporating-the-public-key-into-the-code

 */

#if defined(HAVE_KEYS)

const struct bootutil_key bootutil_keys[] = {

    {

#if defined(MCUBOOT_SIGN_RSA)

        .key = rsa_pub_key,

        .len = &rsa_pub_key_len,

#elif defined(MCUBOOT_SIGN_EC256)

        .key = ecdsa_pub_key,

        .len = &ecdsa_pub_key_len,

#elif defined(MCUBOOT_SIGN_ED25519)

        .key = ed25519_pub_key,

        .len = &ed25519_pub_key_len,

#endif

    },

};

const int bootutil_key_cnt = 1;



#if defined(MCUBOOT_ENCRYPT_RSA)



extern const unsigned char enc_priv_key[];

extern const unsigned int enc_priv_key_len;



const struct bootutil_key bootutil_enc_key = {

    .key = enc_priv_key,

    .len = &enc_priv_key_len,

};

#elif defined(MCUBOOT_ENCRYPT_KW)

#error "Encrypted images with AES-KW is not implemented yet."

#endif



#endif

boot/mbed/include/flash_map_backend/flash_map_backend.h

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/*

 * Copyright (c) 2018 Nordic Semiconductor ASA

 * Copyright (c) 2015 Runtime Inc

 * Copyright (c) 2020 Embedded Planet

 * SPDX-License-Identifier: Apache-2.0

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the Licens

 */



#ifndef H_UTIL_FLASH_MAP_

#define H_UTIL_FLASH_MAP_



#ifdef __cplusplus

extern "C" {

#endif



/**

 *

 * Provides abstraction of flash regions for type of use.

 * I.e. dude where's my image?

 *

 * System will contain a map which contains flash areas. Every

 * region will contain flash identifier, offset within flash and length.

 *

 * 1. This system map could be in a file within filesystem (Initializer

 * must know/figure out where the filesystem is at).

 * 2. Map could be at fixed location for project (compiled to code)

 * 3. Map could be at specific place in flash (put in place at mfg time).

 *

 * Note that the map you use must be valid for BSP it's for,

 * match the linker scripts when platform executes from flash,

 * and match the target offset specified in download script.

 */

#include <inttypes.h>



/**

 * @brief Structure describing an area on a flash device.

 *

 * Multiple flash devices may be available in the system, each of

 * which may have its own areas. For this reason, flash areas track

 * which flash device they are part of.

 */

struct flash_area {

    /**

     * This flash area's ID; unique in the system.

     */

    uint8_t fa_id;



    /**

     * ID of the flash device this area is a part of.

     */

    uint8_t fa_device_id;



    uint16_t pad16;



    /**

     * This area's offset, relative to the beginning of its flash

     * device's storage.

     */

    uint32_t fa_off;



    /**

     * This area's size, in bytes.

     */

    uint32_t fa_size;

};



/**

 * @brief Structure describing a sector within a flash area.

 *

 * Each sector has an offset relative to the start of its flash area

 * (NOT relative to the start of its flash device), and a size. A

 * flash area may contain sectors with different sizes.

 */

struct flash_sector {

    /**

     * Offset of this sector, from the start of its flash area (not device).

     */

    uint32_t fs_off;



    /**

     * Size of this sector, in bytes.

     */

    uint32_t fs_size;

};



/*

 * Start using flash area.

 */

int flash_area_open(uint8_t id, const struct flash_area ** fapp);



void flash_area_close(const struct flash_area * fap);



/*

 * Read/write/erase. Offset is relative from beginning of flash area.

 */

int flash_area_read(const struct flash_area * fap, uint32_t off, void *dst,

  uint32_t len);

int flash_area_write(const struct flash_area * fap, uint32_t off, const void *src,

  uint32_t len);

int flash_area_erase(const struct flash_area * fap, uint32_t off, uint32_t len);



/*

 * Alignment restriction for flash writes.

 */

uint8_t flash_area_align(const struct flash_area * fap);



/*

 * What is value is read from erased flash bytes.

 */

uint8_t flash_area_erased_val(const struct flash_area * fap);



/*

 * Given flash area ID, return info about sectors within the area.

 */

int flash_area_get_sectors(int fa_id, uint32_t *count,

  struct flash_sector *sectors);





int flash_area_id_from_image_slot(int slot);

int flash_area_id_from_multi_image_slot(int image_index, int slot);





int flash_area_id_to_image_slot(int area_id);

/**

 * Converts the specified flash area ID and image index (in multi-image setup)

 * to an image slot index.

 *

 * Returns image slot index (0 or 1), or -1 if ID doesn't correspond to an image

 * slot.

 */

int flash_area_id_to_multi_image_slot(int image_index, int area_id);



#ifdef __cplusplus

}

#endif



#endif /* H_UTIL_FLASH_MAP_ */

boot/mbed/include/flash_map_backend/secondary_bd.h

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/*

 * Copyright (c) 2020 Embedded Planet

 * SPDX-License-Identifier: Apache-2.0

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the Licens

 *

 * Created on: Jul 30, 2020

 * Author: gdbeckstein

 */



#ifndef MCUBOOT_BOOT_MBED_INCLUDE_FLASH_MAP_BACKEND_SECONDARY_BD_H_

#define MCUBOOT_BOOT_MBED_INCLUDE_FLASH_MAP_BACKEND_SECONDARY_BD_H_



#include "blockdevice/BlockDevice.h"



/**

 * This is implemented as a weak function and may be redefined

 * by the application. The default case is to return the

 * BlockDevice object returned by BlockDevice::get_default_instance();

 *

 * @retval secondary_bd Secondary BlockDevice where update candidates are stored

 */

mbed::BlockDevice* get_secondary_bd(void);



#endif /* MCUBOOT_BOOT_MBED_INCLUDE_FLASH_MAP_BACKEND_SECONDARY_BD_H_ */

boot/mbed/include/mcuboot_config/mcuboot_assert.h

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/*

 * Copyright (c) 2018 Open Source Foundries Limited

 *

 * Copyright (c) 2020 Embedded Planet

 * SPDX-License-Identifier: Apache-2.0

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the Licens

 */



#include "platform/mbed_assert.h"

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