vboot: Use kernel max rollforward NV storage field
Kernel verification will now roll forward the minimum allowable
version in the TPM no farther than the kernel_max_rollforward setting.
Note that CL:765573 changes chromeos-setgoodkernel so it always sets
kernel_max_rollforward to 0xfffffffe when marking a kernel as good.
That ensures that firmware with this setting will behave the same for
now as existing firmware.
BUG=chromium:783997
BRANCH=none
CQ-DEPEND=CL:765573
TEST=make runtests
Manual testing:
crossystem tpm_kernvel --> print current kernel version in TPM
- Resign the kernel with a higher version
- Reboot
- Wait a minute for chromeos-setgoodkernel to run
crossystem kernel_max_rollforward=0
- Reboot
crossystem tpm_kernvel --> has not changed
- Wait a minute for chromeos-setgoodkernel to run
crossystem kernel_max_rollforward -> 0xfffffffe
- Reboot
crossystem tpm_kernvel --> has changed to the higher version
Change-Id: Ia32ecb7fa4078548cd311541ccbe120570cf1bc5
Reviewed-on: https://chromium-review.googlesource.com/765574
Commit-Ready: Randall Spangler <rspangler@chromium.org>
Tested-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Stefan Reinauer <reinauer@google.com>
2 files changed
