![]() We were calling g_module_symbol() 2703 times, which is actually more expensive than you'd think. It also means the plugins are actually what we tell people they are: A set of vfuncs that get run. The reality before that they were dlsym'd functions that get called at pretty random times. |
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.. | ||
fuzzing | ||
dbxtool.1 | ||
fu-dbxtool.c | ||
fu-efi-image.c | ||
fu-efi-image.h | ||
fu-plugin-uefi-dbx.c | ||
fu-self-test.c | ||
fu-uefi-dbx-common.c | ||
fu-uefi-dbx-common.h | ||
fu-uefi-dbx-device.c | ||
fu-uefi-dbx-device.h | ||
meson.build | ||
README.md |
UEFI dbx
Introduction
Updating the UEFI revocation database prevents starting EFI binaries with known security issues, and is typically no longer done from a firmware update due to the risk of the machine being "bricked" if the bootloader is not updated first.
This plugin also checks if the UEFI dbx contains all the most recent revoked checksums. The result will be stored in an security attribute for HSI.
Firmware Format
The daemon will decompress the cabinet archive and extract a firmware blob in EFI_SIGNATURE_LIST format.
See https://www.uefi.org/sites/default/files/resources/UEFI%20Spec%202_6.pdf for details.
This plugin supports the following protocol ID:
- org.uefi.dbx
GUID Generation
These devices use the GUID constructed of the uppercase SHA256 of the X509 certificates found in the system KEK and optionally the EFI architecture. e.g.
UEFI\CRT_{sha256}
UEFI\CRT_{sha256}&ARCH_{arch}
...where arch
is typically one of IA32
, X64
, ARM
or AA64
Update Behavior
The firmware is deployed when the machine is in normal runtime mode, but it is only activated when the system is restarted.
Vendor ID Security
The vendor ID is hardcoded to UEFI:Microsoft
for all devices.
External Interface Access
This plugin requires:
- read/write access to
/sys/firmware/efi/efivars