esp-idf/components/bootloader/Kconfig.projbuild
Angus Gratton 506c8cd964 secure boot & flash encryption: Rework configuration options
Add UART bootloader disable options for flash encryption
2016-12-01 23:49:12 -08:00

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menu "Bootloader config"
choice LOG_BOOTLOADER_LEVEL
bool "Bootloader log verbosity"
default LOG_BOOTLOADER_LEVEL_INFO
help
Specify how much output to see in bootloader logs.
config LOG_BOOTLOADER_LEVEL_NONE
bool "No output"
config LOG_BOOTLOADER_LEVEL_ERROR
bool "Error"
config LOG_BOOTLOADER_LEVEL_WARN
bool "Warning"
config LOG_BOOTLOADER_LEVEL_INFO
bool "Info"
config LOG_BOOTLOADER_LEVEL_DEBUG
bool "Debug"
config LOG_BOOTLOADER_LEVEL_VERBOSE
bool "Verbose"
endchoice
config LOG_BOOTLOADER_LEVEL
int
default 0 if LOG_BOOTLOADER_LEVEL_NONE
default 1 if LOG_BOOTLOADER_LEVEL_ERROR
default 2 if LOG_BOOTLOADER_LEVEL_WARN
default 3 if LOG_BOOTLOADER_LEVEL_INFO
default 4 if LOG_BOOTLOADER_LEVEL_DEBUG
default 5 if LOG_BOOTLOADER_LEVEL_VERBOSE
endmenu
menu "Security features"
config SECURE_BOOT_ENABLED
bool "Enable secure boot in bootloader"
default N
help
Build a bootloader which enables secure boot on first boot.
Once enabled, secure boot will not boot a modified bootloader. The bootloader will only load a partition table or boot an app if the data has a verified digital signature.
When enabling secure boot, JTAG and ROM BASIC Interpreter are permanently disabled by default.
See docs/security/secure-boot.rst for details.
choice SECURE_BOOTLOADER_MODE
bool "Secure bootloader mode"
depends on SECURE_BOOT_ENABLED
default SECURE_BOOTLOADER_ONE_TIME_FLASH
config SECURE_BOOTLOADER_ONE_TIME_FLASH
bool "One-time flash"
help
On first boot, the bootloader will generate a key which is not readable externally or by software. A digest is generated from the bootloader image itself. This digest will be verified on each subsequent boot.
Enabling this option means that the bootloader cannot be changed after the first time it is booted.
config SECURE_BOOTLOADER_REFLASHABLE
bool "Reflashable"
help
Generate a reusable secure bootloader key, derived (via SHA-256) from the secure boot signing key.
This allows the secure bootloader to be re-flashed by anyone with access to the secure boot signing key.
This option is less secure than one-time flash, because a leak of the digest key from one device allows reflashing of any device that uses it.
endchoice
config SECURE_BOOT_SIGNING_KEY
string "Secure boot signing key"
depends on SECURE_BOOT_ENABLED
default secure_boot_signing_key.pem
help
Path to the key file used to sign partition tables and app images for secure boot. Once secure boot is enabled, bootloader will only boot if partition table and app image are signed.
Key file is an ECDSA private key (NIST256p curve) in PEM format.
Path is evaluated relative to the project directory.
You can generate a new signing key by running the following command:
espsecure.py generate_signing_key secure_boot_signing_key.pem
See docs/security/secure-boot.rst for details.
config SECURE_BOOT_INSECURE
bool "Allow potentially insecure options"
depends on SECURE_BOOT_ENABLED
default N
help
You can disable some of the default protections offered by secure boot, in order to enable testing or a custom combination of security features.
Only enable these options if you are very sure.
Refer to docs/security/secure-boot.rst and docs/security/flash-encryption.rst for details.
config FLASH_ENCRYPTION_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.
See docs/securityflash-encryption.rst for details.
config FLASH_ENCRYPTION_INSECURE
bool "Allow potentially insecure options"
depends on FLASH_ENCRYPTION_ENABLED
default N
help
You can disable some of the default protections offered by flash encryption, in order to enable testing or a custom combination of security features.
Only enable these options if you are very sure.
Refer to docs/security/secure-boot.rst and docs/security/flash-encryption.rst for details.
menu "Potentially insecure options"
visible if FLASH_ENCRYPTION_INSECURE || SECURE_BOOT_INSECURE
# NOTE: Options in this menu NEED to have SECURE_BOOT_INSECURE
# and/or FLASH_ENCRYPTION_INSECURE in "depends on", as the menu
# itself doesn't enable/disable its children (if it's not set,
# it's possible for the insecure menu to be disabled but the insecure option
# to remain on which is very bad.)
config SECURE_BOOT_ALLOW_ROM_BASIC
bool "Leave ROM BASIC Interpreter available on reset"
depends on SECURE_BOOT_INSECURE
default N
help
If not set (default), bootloader permanently disables ROM BASIC (on UART console) as a fallback if the bootloader image becomes invalid. This happens on first boot.
Only set this option in testing environments.
config SECURE_BOOT_ALLOW_JTAG
bool "Allow JTAG Debugging"
depends on SECURE_BOOT_INSECURE || FLASH_ENCRYPTION_INSECURE
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 FLASH_ENCRYPTION_UART_BOOTLOADER_ALLOW_ENCRYPT
bool "Leave UART bootloader encryption enabled"
depends on FLASH_ENCRYPTION_INSECURE
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 FLASH_ENCRYPTION_UART_BOOTLOADER_ALLOW_DECRYPT
bool "Leave UART bootloader decryption enabled"
depends on FLASH_ENCRYPTION_INSECURE
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 FLASH_ENCRYPTION_UART_BOOTLOADER_ALLOW_CACHE
bool "Leave UART bootloader flash cache enabled"
depends on FLASH_ENCRYPTION_INSECURE
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 SECURE_BOOT_TEST_MODE
bool "Secure boot test mode: don't permanently set any efuses"
depends on SECURE_BOOT_INSECURE
default N
help
If this option is set, all permanent secure boot changes (via Efuse) are disabled.
Log output will state changes which would be applied, but they will not be.
This option is for testing purposes only - it completely disables secure boot protection.
endmenu # potentially insecure
endmenu