This is an automated email from the ASF dual-hosted git repository.
gustavonihei pushed a commit to branch feature/esp32_flash_encryption
in repository https://gitbox.apache.org/repos/asf/incubator-nuttx.git
commit 3e420f562dddff294e0c34b58474628bea6d6d15
Author: Gustavo Henrique Nihei <gustavo.ni...@espressif.com>
AuthorDate: Wed Oct 6 10:27:07 2021 -0300
xtensa/esp32: Enable building a bootloader with Flash Encryption support
Signed-off-by: Gustavo Henrique Nihei <gustavo.ni...@espressif.com>
---
arch/xtensa/src/esp32/Bootloader.mk | 18 ++++++
arch/xtensa/src/esp32/Kconfig | 119 ++++++++++++++++++++++++++++++++++++
2 files changed, 137 insertions(+)
diff --git a/arch/xtensa/src/esp32/Bootloader.mk
b/arch/xtensa/src/esp32/Bootloader.mk
index 51db177..55ba7f5 100644
--- a/arch/xtensa/src/esp32/Bootloader.mk
+++ b/arch/xtensa/src/esp32/Bootloader.mk
@@ -75,6 +75,24 @@ $(BOOTLOADER_CONFIG): $(TOPDIR)/.config
[ "$(CONFIG_ESP32_FLASH_FREQ_40M)" = "y" ] && echo
"CONFIG_ESPTOOLPY_FLASHFREQ_40M=y"; \
[ "$(CONFIG_ESP32_FLASH_FREQ_26M)" = "y" ] && echo
"CONFIG_ESPTOOLPY_FLASHFREQ_26M=y"; \
[ "$(CONFIG_ESP32_FLASH_FREQ_20M)" = "y" ] && echo
"CONFIG_ESPTOOLPY_FLASHFREQ_20M=y"; \
+ [ "$(CONFIG_ESP32_SECURE_FLASH_ENC_ENABLED)" = "y" ] && \
+ echo "CONFIG_SECURE_FLASH_ENC_ENABLED=y"; \
+ [ "$(CONFIG_ESP32_SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT)" =
"y" ] && \
+ echo
"CONFIG_SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT=y"; \
+ [ "$(CONFIG_ESP32_SECURE_FLASH_ENCRYPTION_MODE_RELEASE)" = "y"
] && \
+ echo "CONFIG_SECURE_FLASH_ENCRYPTION_MODE_RELEASE=y"; \
+ [ "$(CONFIG_ESP32_SECURE_BOOT_ALLOW_ROM_BASIC)" = "y" ] && \
+ echo "CONFIG_SECURE_BOOT_ALLOW_ROM_BASIC=y"; \
+ [ "$(CONFIG_ESP32_SECURE_BOOT_ALLOW_JTAG)" = "y" ] && \
+ echo "CONFIG_SECURE_BOOT_ALLOW_JTAG=y"; \
+ [ "$(CONFIG_ESP32_SECURE_FLASH_UART_BOOTLOADER_ALLOW_ENC)" =
"y" ] && \
+ echo "CONFIG_SECURE_FLASH_UART_BOOTLOADER_ALLOW_ENC=y";
\
+ [ "$(CONFIG_ESP32_SECURE_FLASH_UART_BOOTLOADER_ALLOW_DEC)" =
"y" ] && \
+ echo "CONFIG_SECURE_FLASH_UART_BOOTLOADER_ALLOW_DEC=y";
\
+ [ "$(CONFIG_ESP32_FLASH_UART_BOOTLOADER_ALLOW_CACHE)" = "y" ]
&& \
+ echo "CONFIG_FLASH_UART_BOOTLOADER_ALLOW_CACHE=y"; \
+ [ "$(CONFIG_ESP32_SECURE_FLASH_REQUIRE_ALREADY_ENABLED)" = "y"
] && \
+ echo "CONFIG_SECURE_FLASH_REQUIRE_ALREADY_ENABLED=y"; \
echo "CONFIG_PARTITION_TABLE_CUSTOM=y";
\
echo
"CONFIG_PARTITION_TABLE_CUSTOM_FILENAME=\"partitions.csv\"";
\
} > $(BOOTLOADER_CONFIG)
diff --git a/arch/xtensa/src/esp32/Kconfig b/arch/xtensa/src/esp32/Kconfig
index 6b2e60d..5d7ac19 100644
--- a/arch/xtensa/src/esp32/Kconfig
+++ b/arch/xtensa/src/esp32/Kconfig
@@ -907,6 +907,125 @@ config ESP32_SPIFLASH_DEBUG
Enable this option, read and write of SPI Flash
will show input arguments and result.
+comment "Flash Encryption"
+
+config ESP32_SECURE_FLASH_ENC_ENABLED
+ bool "Enable flash encryption on boot"
+ default n
+ ---help---
+ If this option is set, flash contents will be encrypted by the
bootloader on first boot.
+
+ Note: After first boot, the system will be permanently
encrypted. Re-flashing an encrypted
+ system is complicated and not always possible.
+
+ Read
https://docs.espressif.com/projects/esp-idf/en/latest/security/flash-encryption.html
+ before enabling.
+
+comment "Flash Encryption support requires building bootloader from source
(ESP32_BOOTLOADER_BUILD_FROM_SOURCE)"
+ depends on ESP32_SECURE_FLASH_ENC_ENABLED &&
!ESP32_BOOTLOADER_BUILD_FROM_SOURCE
+
+if ESP32_SECURE_FLASH_ENC_ENABLED
+
+choice ESP32_SECURE_FLASH_ENCRYPTION_MODE
+ bool "Enable usage mode"
+ default ESP32_SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT
+ ---help---
+ By default, Development mode is enabled which allows ROM
download mode to perform flash encryption
+ operations (plaintext is sent to the device, and it encrypts it
internally and writes ciphertext
+ to flash). This mode is not secure, it's possible for an
attacker to write their own chosen plaintext
+ to flash.
+
+ Release mode should always be selected for production or
manufacturing. Once enabled it's no longer
+ possible for the device in ROM Download Mode to use the flash
encryption hardware.
+
+ Refer to the Flash Encryption section of the ESP-IDF
Programmer's Guide for details:
+
https://docs.espressif.com/projects/esp-idf/en/latest/esp32/security/flash-encryption.html#flash-encryption-configuration
+
+ config ESP32_SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT
+ bool "Development (NOT SECURE)"
+ select ESP32_SECURE_FLASH_UART_BOOTLOADER_ALLOW_ENC
+
+ config ESP32_SECURE_FLASH_ENCRYPTION_MODE_RELEASE
+ bool "Release"
+
+endchoice
+
+if ESP32_SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT
+
+menu "Potentially insecure options"
+
+config ESP32_SECURE_BOOT_ALLOW_ROM_BASIC
+ bool "Leave ROM BASIC Interpreter available on reset"
+ default n
+ ---help---
+ By default, the BASIC ROM Console starts on reset if no valid
bootloader is
+ read from the flash.
+
+ When either flash encryption or secure boot are enabled, the
default is to
+ disable this BASIC fallback mode permanently via eFuse.
+
+ If this option is set, this eFuse is not burned and the BASIC
ROM Console may
+ remain accessible. Only set this option in testing
environments.
+
+config ESP32_SECURE_BOOT_ALLOW_JTAG
+ bool "Allow JTAG Debugging"
+ default n
+ ---help---
+ If not set (default), the bootloader will permanently disable
JTAG (across entire chip) on first boot
+ when either secure boot or flash encryption is enabled.
+
+ Setting this option leaves JTAG on for debugging, which negates
all protections of flash encryption
+ and some of the protections of secure boot.
+
+ Only set this option in testing environments.
+
+config ESP32_SECURE_FLASH_UART_BOOTLOADER_ALLOW_ENC
+ bool "Leave UART bootloader encryption enabled"
+ default n
+ ---help---
+ If not set (default), the bootloader will permanently disable
UART bootloader encryption access on
+ first boot. If set, the UART bootloader will still be able to
access hardware encryption.
+
+ It is recommended to only set this option in testing
environments.
+
+config ESP32_SECURE_FLASH_UART_BOOTLOADER_ALLOW_DEC
+ bool "Leave UART bootloader decryption enabled"
+ default n
+ ---help---
+ If not set (default), the bootloader will permanently disable
UART bootloader decryption access on
+ first boot. If set, the UART bootloader will still be able to
access hardware decryption.
+
+ Only set this option in testing environments. Setting this
option allows complete bypass of flash
+ encryption.
+
+config ESP32_SECURE_FLASH_UART_BOOTLOADER_ALLOW_CACHE
+ bool "Leave UART bootloader flash cache enabled"
+ default n
+ ---help---
+ If not set (default), the bootloader will permanently disable
UART bootloader flash cache access on
+ first boot. If set, the UART bootloader will still be able to
access the flash cache.
+
+ Only set this option in testing environments.
+
+config ESP32_SECURE_FLASH_REQUIRE_ALREADY_ENABLED
+ bool "Require flash encryption to be already enabled"
+ default n
+ ---help---
+ If not set (default), and flash encryption is not yet enabled
in eFuses, the 2nd stage bootloader
+ will enable flash encryption: generate the flash encryption key
and program eFuses.
+ If this option is set, and flash encryption is not yet enabled,
the bootloader will error out and
+ reboot.
+ If flash encryption is enabled in eFuses, this option does not
change the bootloader behavior.
+
+ Only use this option in testing environments, to avoid
accidentally enabling flash encryption on
+ the wrong device. The device needs to have flash encryption
already enabled using espefuse.py.
+
+endmenu # Potentially Insecure
+
+endif # ESP32_SECURE_FLASH_ENCRYPTION_MODE_DEVELOPMENT
+
+endif # ESP32_SECURE_FLASH_ENC_ENABLED
+
endmenu # ESP32_SPIFLASH
menu "SPI RAM Config"
