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118 lines
4.4 KiB
C
118 lines
4.4 KiB
C
// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef __ESP32_FLASH_ENCRYPT_H
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#define __ESP32_FLASH_ENCRYPT_H
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#include <stdbool.h>
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#include "esp_attr.h"
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#include "esp_err.h"
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#ifndef BOOTLOADER_BUILD
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#include "esp_spi_flash.h"
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#endif
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#include "soc/efuse_reg.h"
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/**
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* @file esp_partition.h
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* @brief Support functions for flash encryption features
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*
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* Can be compiled as part of app or bootloader code.
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*/
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/** @brief Is flash encryption currently enabled in hardware?
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*
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* Flash encryption is enabled if the FLASH_CRYPT_CNT efuse has an odd number of bits set.
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*
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* @return true if flash encryption is enabled.
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*/
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static inline /** @cond */ IRAM_ATTR /** @endcond */ bool esp_flash_encryption_enabled(void) {
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uint32_t flash_crypt_cnt = REG_GET_FIELD(EFUSE_BLK0_RDATA0_REG, EFUSE_RD_FLASH_CRYPT_CNT);
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/* __builtin_parity is in flash, so we calculate parity inline */
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bool enabled = false;
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while(flash_crypt_cnt) {
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if (flash_crypt_cnt & 1) {
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enabled = !enabled;
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}
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flash_crypt_cnt >>= 1;
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}
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return enabled;
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}
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/* @brief Update on-device flash encryption
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*
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* Intended to be called as part of the bootloader process if flash
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* encryption is enabled in device menuconfig.
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*
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* If FLASH_CRYPT_CNT efuse parity is 1 (ie odd number of bits set),
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* then return ESP_OK immediately (indicating flash encryption is enabled
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* and functional).
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*
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* If FLASH_CRYPT_CNT efuse parity is 0 (ie even number of bits set),
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* assume the flash has just been written with plaintext that needs encrypting.
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*
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* The following regions of flash are encrypted in place:
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*
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* - The bootloader image, if a valid plaintext image is found.[*]
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* - The partition table, if a valid plaintext table is found.
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* - Any app partition that contains a valid plaintext app image.
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* - Any other partitions with the "encrypt" flag set. [**]
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*
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* After the re-encryption process completes, a '1' bit is added to the
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* FLASH_CRYPT_CNT value (setting the parity to 1) and the EFUSE is re-burned.
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*
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* [*] If reflashing bootloader with secure boot enabled, pre-encrypt
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* the bootloader before writing it to flash or secure boot will fail.
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*
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* [**] For this reason, if serial re-flashing a previous flashed
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* device with secure boot enabled and using FLASH_CRYPT_CNT to
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* trigger re-encryption, you must simultaneously re-flash plaintext
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* content to all partitions with the "encrypt" flag set or this
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* data will be corrupted (encrypted twice).
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*
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* @note The post-condition of this function is that all
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* partitions that should be encrypted are encrypted.
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*
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* @note Take care not to power off the device while this function
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* is running, or the partition currently being encrypted will be lost.
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*
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* @note RTC_WDT will reset while encryption operations will be performed (if RTC_WDT is configured).
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*
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* @return ESP_OK if all operations succeeded, ESP_ERR_INVALID_STATE
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* if a fatal error occured during encryption of all partitions.
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*/
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esp_err_t esp_flash_encrypt_check_and_update(void);
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/** @brief Encrypt-in-place a block of flash sectors
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*
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* @note This function resets RTC_WDT between operations with sectors.
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* @param src_addr Source offset in flash. Should be multiple of 4096 bytes.
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* @param data_length Length of data to encrypt in bytes. Will be rounded up to next multiple of 4096 bytes.
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*
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* @return ESP_OK if all operations succeeded, ESP_ERR_FLASH_OP_FAIL
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* if SPI flash fails, ESP_ERR_FLASH_OP_TIMEOUT if flash times out.
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*/
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esp_err_t esp_flash_encrypt_region(uint32_t src_addr, size_t data_length);
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/** @brief Write protect FLASH_CRYPT_CNT
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*
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* Intended to be called as a part of boot process if flash encryption
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* is enabled but secure boot is not used. This should protect against
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* serial re-flashing of an unauthorised code in absence of secure boot.
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*
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* @return
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*/
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void esp_flash_write_protect_crypt_cnt();
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#endif
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