Re: [PATCH] tpm: Pass unknown error as non-fatal, but debug print the error we got

[Mathieu Trudel-Lapierre]

On Fri, Oct 25, 2019 at 10:28 AM Mathieu Trudel-Lapierre
<address@hidden> wrote:
>
> Signed-off-by: Mathieu Trudel-Lapierre <address@hidden>
> Patch-Name: ubuntu-tpm-unknown-error-non-fatal.patch
> ---
>  grub-core/commands/efi/tpm.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>

I see I omitted to explain why I'm proposing this.

I've seen a couple of reports so far of issues with booting with TPM
measurement enabled, when the firmware has TPM enabled, on some
hardware.

In particular, this has happened on a Dell laptop at Plumbers this
year (an older model XPS15 IIRC), and a few different models of
laptops/motherboards. Some report having a TPM, and some do not:

HP EliteBook 820 G4 (Infineon SLB9670?)
ASUS M32CD4-K motherboard (unknown)
ASUS ROG GL553VE Laptop (unknown)
ASUS ZenBook 3 UX390UA (unknown)
ASUS Zenbook UX305FA (unspecified TPM)
ASUS ZenBook UX303UA (unknown)
ASUS 2O7HSV6 ??

See https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1848892.

Unfortunately the reports are not of great quality, but I'm starting
to worry about what exactly is wrong, if it's really a firmware / TPM
issue or a bug in the TPM code.

For now, it seems like the best is to get more information as to what
exactly the failure is (hence grub_dprintf()), and treating these
errors as non-fatal so people can still boot.

After briefly discussing this with others, it's not clear whether all
the affected systems really do have a TPM, but they might still report
in firmware that they do. Are we running into a case where the
firmware wrongly reports there is a TPM, but fails to do any
measurements?

Kindly,

-- 

Mathieu Trudel-Lapierre <address@hidden>
Freenode: cyphermox, Jabber: address@hidden
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