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Re: [Qemu-devel] [edk2] [PATCH 4/4] ovmf: process TPM PPI request in Aft
From: |
Laszlo Ersek |
Subject: |
Re: [Qemu-devel] [edk2] [PATCH 4/4] ovmf: process TPM PPI request in AfterConsole() |
Date: |
Thu, 17 May 2018 12:24:53 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 |
On 05/15/18 14:30, address@hidden wrote:
> From: Marc-André Lureau <address@hidden>
>
> 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.
>
> Signed-off-by: Marc-André Lureau <address@hidden>
> ---
> OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c | 8 ++++++++
> .../PlatformBootManagerLib/PlatformBootManagerLib.inf | 2 ++
> 2 files changed, 10 insertions(+)
>
> diff --git a/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c
> b/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c
> index 004b753f4d26..8b1beaa3e207 100644
> --- a/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c
> +++ b/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c
> @@ -16,6 +16,7 @@
> #include <Guid/XenInfo.h>
> #include <Guid/RootBridgesConnectedEventGroup.h>
> #include <Protocol/FirmwareVolume2.h>
> +#include <Library/Tcg2PhysicalPresenceLib.h>
>
>
> //
> @@ -1410,6 +1411,13 @@ PlatformBootManagerAfterConsole (
> //
> PciAcpiInitialization ();
>
> +
> + //
> + // Process TPM PPI request
> + //
> + Tcg2PhysicalPresenceLibProcessRequest (NULL);
> +
> +
Please just keep one empty line before and after the new code. With that
cleanup, for this patch:
Reviewed-by: Laszlo Ersek <address@hidden>
This series is a very nice work IMO, thank you both Stefan and
Marc-André. I hope v2 can be merged!
Thanks!
Laszlo
> //
> // Process QEMU's -kernel command line option
> //
> diff --git
> a/OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf
> b/OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf
> index 27789b7377bc..4b72c44bcf0a 100644
> --- a/OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf
> +++ b/OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf
> @@ -38,6 +38,7 @@ [Packages]
> IntelFrameworkModulePkg/IntelFrameworkModulePkg.dec
> SourceLevelDebugPkg/SourceLevelDebugPkg.dec
> OvmfPkg/OvmfPkg.dec
> + SecurityPkg/SecurityPkg.dec
>
> [LibraryClasses]
> BaseLib
> @@ -56,6 +57,7 @@ [LibraryClasses]
> LoadLinuxLib
> QemuBootOrderLib
> UefiLib
> + Tcg2PhysicalPresenceLib
>
> [Pcd]
> gUefiOvmfPkgTokenSpaceGuid.PcdEmuVariableEvent
>
- [Qemu-devel] [PATCH 0/4] RFC: ovmf: Add support for TPM Physical Presence interface, marcandre . lureau, 2018/05/15
- [Qemu-devel] [PATCH 1/4] ovmf: add and link with Tcg2PhysicalPresenceLibNull when !TPM2_ENABLE, marcandre . lureau, 2018/05/15
- [Qemu-devel] [PATCH 2/4] ovmf: add QemuTpm.h header, marcandre . lureau, 2018/05/15
- [Qemu-devel] [PATCH 4/4] ovmf: process TPM PPI request in AfterConsole(), marcandre . lureau, 2018/05/15
- Re: [Qemu-devel] [edk2] [PATCH 4/4] ovmf: process TPM PPI request in AfterConsole(),
Laszlo Ersek <=
- [Qemu-devel] [PATCH 3/4] ovmf: replace SecurityPkg with OvfmPkg Tcg2PhysicalPresenceLibQemu, marcandre . lureau, 2018/05/15
- Re: [Qemu-devel] [edk2] [PATCH 0/4] RFC: ovmf: Add support for TPM Physical Presence interface, Laszlo Ersek, 2018/05/16
- Re: [Qemu-devel] [edk2] [PATCH 0/4] RFC: ovmf: Add support for TPM Physical Presence interface, Laszlo Ersek, 2018/05/17