OVMS3-idf/components/bootloader_support/src/flash_encrypt.c

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// Copyright 2015-2019 Espressif Systems (Shanghai) PTE LTD
//
// 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 <strings.h>
#include "sdkconfig.h"
#include "esp_log.h"
#include "esp_efuse.h"
#include "esp_efuse_table.h"
#include "esp_flash_encrypt.h"
#include "esp_secure_boot.h"
#ifndef BOOTLOADER_BUILD
static const char *TAG = "flash_encrypt";
void esp_flash_encryption_init_checks()
{
esp_flash_enc_mode_t mode;
// First check is: if Release mode flash encryption & secure boot are enabled then
// FLASH_CRYPT_CNT *must* be write protected. This will have happened automatically
// if bootloader is IDF V4.0 or newer but may not have happened for previous ESP-IDF bootloaders.
#ifdef CONFIG_SECURE_FLASH_ENCRYPTION_MODE_RELEASE
#ifdef CONFIG_SECURE_BOOT_ENABLED
if (esp_secure_boot_enabled() && esp_flash_encryption_enabled()) {
uint8_t flash_crypt_cnt_wr_dis = 0;
esp_efuse_read_field_blob(ESP_EFUSE_WR_DIS_FLASH_CRYPT_CNT, &flash_crypt_cnt_wr_dis, 1);
if (!flash_crypt_cnt_wr_dis) {
ESP_EARLY_LOGE(TAG, "Flash encryption & Secure Boot together requires FLASH_CRYPT_CNT efuse to be write protected. Fixing now...");
esp_flash_write_protect_crypt_cnt();
}
}
#endif // CONFIG_SECURE_BOOT_ENABLED
#endif // CONFIG_SECURE_FLASH_ENCRYPTION_MODE_RELEASE
// Second check is to print a warning or error if the current running flash encryption mode
// doesn't match the expectation from project config (due to mismatched bootloader and app, probably)
mode = esp_get_flash_encryption_mode();
if (mode == ESP_FLASH_ENC_MODE_DEVELOPMENT) {
#ifdef CONFIG_SECURE_FLASH_ENCRYPTION_MODE_RELEASE
ESP_EARLY_LOGE(TAG, "Flash encryption settings error: app is configured for RELEASE but efuses are set for DEVELOPMENT");
ESP_EARLY_LOGE(TAG, "Mismatch found in security options in bootloader menuconfig and efuse settings. Device is not secure.");
#else
ESP_EARLY_LOGW(TAG, "Flash encryption mode is DEVELOPMENT (not secure)");
#endif
} else if (mode == ESP_FLASH_ENC_MODE_RELEASE) {
ESP_EARLY_LOGI(TAG, "Flash encryption mode is RELEASE");
}
}
#endif
void esp_flash_write_protect_crypt_cnt(void)
{
uint8_t flash_crypt_cnt_wr_dis = 0;
esp_efuse_read_field_blob(ESP_EFUSE_WR_DIS_FLASH_CRYPT_CNT, &flash_crypt_cnt_wr_dis, 1);
if (!flash_crypt_cnt_wr_dis) {
esp_efuse_write_field_cnt(ESP_EFUSE_WR_DIS_FLASH_CRYPT_CNT, 1);
}
}
esp_flash_enc_mode_t esp_get_flash_encryption_mode(void)
{
uint8_t efuse_flash_crypt_cnt_wr_protected = 0;
uint8_t dis_dl_enc = 0, dis_dl_dec = 0, dis_dl_cache = 0;
esp_flash_enc_mode_t mode = ESP_FLASH_ENC_MODE_DEVELOPMENT;
if (esp_flash_encryption_enabled()) {
/* Check if FLASH CRYPT CNT is write protected */
esp_efuse_read_field_blob(ESP_EFUSE_WR_DIS_FLASH_CRYPT_CNT, &efuse_flash_crypt_cnt_wr_protected, 1);
if (efuse_flash_crypt_cnt_wr_protected) {
esp_efuse_read_field_blob(ESP_EFUSE_DISABLE_DL_CACHE, &dis_dl_cache, 1);
esp_efuse_read_field_blob(ESP_EFUSE_DISABLE_DL_ENCRYPT, &dis_dl_enc, 1);
esp_efuse_read_field_blob(ESP_EFUSE_DISABLE_DL_DECRYPT, &dis_dl_dec, 1);
/* Check if DISABLE_DL_DECRYPT, DISABLE_DL_ENCRYPT & DISABLE_DL_CACHE are set */
if ( dis_dl_cache && dis_dl_enc && dis_dl_dec ) {
mode = ESP_FLASH_ENC_MODE_RELEASE;
}
}
} else {
mode = ESP_FLASH_ENC_MODE_DISABLED;
}
return mode;
}