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The library registers a security management handler, to measure images
that are not measure in PEI phase. For example with the qemu PXE rom:
Loading driver at 0x0003E6C2000 EntryPoint=0x0003E6C9076 8086100e.efi
And the following binary_bios_measurements log entry seems to be
added:
PCR: 2 type: EV_EFI_BOOT_SERVICES_DRIVER size: 0x4e digest: 70a22475e9f18806d2ed9193b48d80d26779d9a4
The following order of operations ensures that 3rd party UEFI modules,
such as PCI option ROMs and other modules possibly loaded from outside
of firmware volumes, are measured into the TPM:
(1) Tcg2Dxe is included in DXEFV, therefore it produces the TCG2
protocol sometime in the DXE phase (assuming a TPM2 chip is present,
reported via PcdTpmInstanceGuid).
(2) The DXE core finds that no more drivers are left to dispatch from
DXEFV, and we enter the BDS phase.
(3) OVMF's PlatformBootManagerLib connects all PCI root bridges
non-recursively, producing PciIo instances and discovering PCI
oproms.
(4) The dispatching of images that don't originate from FVs is deferred
at this point, by
"MdeModulePkg/Universal/SecurityStubDxe/Defer3rdPartyImageLoad.c".
(5) OVMF's PlatformBootManagerLib signals EndOfDxe.
(6) OVMF's PlatformBootManagerLib calls
EfiBootManagerDispatchDeferredImages() -- the images deferred in
step (4) are now dispatched.
(7) Image dispatch invokes the Security / Security2 Arch protocols
(produced by SecurityStubDxe). In this patch, we hook
DxeTpm2MeasureBootLib into SecurityStubDxe, therefore image dispatch
will try to locate the TCG2 protocol, and measure the image into the
TPM2 chip with the protocol. Because of step (1), the TCG2 protocol
will always be found and used (assuming a TPM2 chip is present).
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Stefan Berger <stefanb@linux.vnet.ibm.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
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:
- AppPkg/Applications/Python/Python-2.7.2/Tools/pybench
- AppPkg/Applications/Python/Python-2.7.2
- AppPkg/Applications/Python/Python-2.7.10
- BaseTools/Source/C/BrotliCompress
- MdeModulePkg/Library/BrotliCustomDecompressLib
- OvmfPkg
- CryptoPkg/Library/OpensslLib/openssl
The EDK II Project is composed of packages. The maintainers for each package are listed in Maintainers.txt.