LAS16-200: Firmware Summit - UEFI secure boot
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The document discusses the current status of UEFI Secure Boot on AArch64, indicating that progress remains largely unchanged from the previous year. It highlights the lack of a tamper-proof, replay-protected non-volatile variable store implementation, which is a requirement of the UEFI Secure Boot specification. Additionally, it notes challenges related to specification support and suggests a potential stopgap solution involving external manipulation of certain variables to make them immutable.
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LAS16-200: Firmware Summit - UEFI secure boot
- 1. UEFI Secure Boot Ard Biesheuvel <ard.biesheuvel@linaro.org>
- 2. ENGINEERS AND DEVICES WORKING TOGETHER UEFI Secure Boot - current status on AArch64 ● Essentially the same as a year ago ○ Software layers above the non-volatile variable store are working and regression tested through CI (both AArch64 and ARM) ○ No implementation exists to make the non-volatile variable store tamper proof and replay protected, as the UEFI Secure Boot spec requires ● What is holding us back? ○ Spec based reference implementation of the tamper proof varstore requires (S)MM support, which is not even in the spec yet for AArch64. ○ Non-spec based ref implementation is likely too platform specific, which complicates sharing between members and/or open sourcing ● Is there a plan B? ○ External manipulation of PK/KEK/db/dbx variables, while making them immutable from the OS/firmware pov. Stop gap solution, but effective
- 3. Thank You #LAS16 For further information: www.linaro.org LAS16 keynotes and videos on: connect.linaro.org