於 四，2013-08-29 於 23:32 +0200，Pavel Machek 提到：
Hi!
- Bootloader store the public key to EFI boottime variable by itself - Bootloader put The private key to S4SignKey EFI variable for forward to kernel.
Is the UEFI NVRAM really suited for such regular updates?
Yes, Matthew raised this concern at before. I modified patch to load private key in efi stub kernel, before ExitBootServices(), that means we don't need generate key-pair at every system boot. So, the above procedure of efi bootloader will only run one time.
User can enable SNAPSHOT_REGEN_KEYS kernel config to notify efi booloader regenerate key-pair for every S4 to improve security if he want. So, the key-pair re-generate procedure will only launched when S4 resume, not every system boot.
How many writes can UEFI NVRAM survive? (Is it NOR?)
Currently doesn't have enough information for normal. Yes, I don't know.
"every S4 resume" may be approximately "every boot" for some users... Pavel
Yes, it's possible. So, this option will be disabled by default. Default will only generate one key-pair for every hibernate. If "re-generate key-pair for every S4" is still hurt lift of UEFI NVRAM too much, then another thinking for re-generate key-pair are: + Re-generate key-pair after a number of hibernates. e.g. after 5, 10, 20... times or + Random re-generate key-pair? On the other hand... In current design, GenS4Key EFI variable could be write by userland hibernate tool, kernel will respect GenS4Key value from userland when hibernate launch. So, userland can tell bootloader to lunch the key-pair regeneration procedure. Thanks a lot! Joey LEe -- To unsubscribe, e-mail: opensuse-kernel+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse-kernel+owner@opensuse.org