Marc-André Lureau 8d65d3b25e OvmfPkg/PlatformBootManagerLib: process TPM PPI request
Call Tcg2PhysicalPresenceLibProcessRequest() to process pending PPI
requests from PlatformBootManagerAfterConsole().

Laszlo understanding of edk2 is that the PPI operation processing was
meant to occur *entirely* before End-Of-Dxe, so that 3rd party UEFI
drivers couldn't interfere with PPI opcode processing *at all*.

He suggested that we should *not* call
Tcg2PhysicalPresenceLibProcessRequest() from BeforeConsole(). Because,
an "auth" console, i.e. one that does not depend on a 3rd party
driver, is *in general* impossible to guarantee. Instead we could opt
to trust 3rd party drivers, and use the "normal" console(s) in
AfterConsole(), in order to let the user confirm the PPI requests. It
will depend on the user to enable Secure Boot, so that the
trustworthiness of those 3rd party drivers is ensured. If an attacker
roots the guest OS from within, queues some TPM2 PPI requests, and
also modifies drivers on the EFI system partition and/or in GPU option
ROMs (?), then those drivers will not load after guest reboot, and
thus the dependent console(s) won't be used for confirming the PPI
requests.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
2018-05-22 16:30:44 +02:00

EDK II Project

A modern, feature-rich, cross-platform firmware development environment for the UEFI and PI specifications from www.uefi.org.

Contributions to the EDK II open source project are covered by the TianoCore Contribution Agreement 1.1

The majority of the content in the EDK II open source project uses a BSD 2-Clause License. The EDK II open source project contains the following components that are covered by additional licenses:

The EDK II Project is composed of packages. The maintainers for each package are listed in Maintainers.txt.

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Acidanthera UEFI Development Kit based on EDK II edk2-stable202405
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