Re: [PATCH V3 1/1] OvmfPkg/AcpiPlatformDxe: Measure ACPI table from QEMU in TDVF

["Yao, Jiewen" <jiewen.yao@intel.com>]

Reviewed-by: Jiewen Yao <Jiewen.yao@intel.com>

> -----Original Message-----
> From: Xu, Min M <min.m.xu@intel.com>
> Sent: Thursday, February 2, 2023 5:03 PM
> To: devel@edk2.groups.io
> Cc: Xu, Min M <min.m.xu@intel.com>; Aktas, Erdem
> <erdemaktas@google.com>; James Bottomley <jejb@linux.ibm.com>; Yao,
> Jiewen <jiewen.yao@intel.com>; Gerd Hoffmann <kraxel@redhat.com>; Tom
> Lendacky <thomas.lendacky@amd.com>; Michael Roth
> <michael.roth@amd.com>
> Subject: [PATCH V3 1/1] OvmfPkg/AcpiPlatformDxe: Measure ACPI table from
> QEMU in TDVF
> 
> From: Min M Xu <min.m.xu@intel.com>
> 
> https://bugzilla.tianocore.org/show_bug.cgi?id=4245
> 
> QEMU provides the following three files for guest to install the ACPI
> tables:
>  - etc/acpi/rsdp
>  - etc/acpi/tables
>  - etc/table-loader
> 
> "etc/acpi/rsdp" and "etc/acpi/tables" are similar, they are only kept
> separate because they have different allocation requirements in SeaBIOS.
> 
> Both of these fw_cfg files contain preformatted ACPI payload.
> "etc/acpi/rsdp" contains only the RSDP table, while "etc/acpi/tables"
> contains all other tables, concatenated. To be noted, the tables in these
> two files have been filled in by qemu, but two kinds of fields are
> incomplete: pointers to other tables and checksums (which depend on the
> pointers).
> 
> "/etc/table-loader" is a linker/loader which provides the commands to
> "patch" the tables in "etc/acpi/tables" and then install them. "Patch"
> means to fill the pointers and compute the checksum.
> 
> From the security perspective these 3 files are the raw data downloaded
> from qemu. They should be measured and extended before they're consumed.
> 
> Cc: Erdem Aktas <erdemaktas@google.com>
> Cc: James Bottomley <jejb@linux.ibm.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Cc: Michael Roth <michael.roth@amd.com>
> Signed-off-by: Min Xu <min.m.xu@intel.com>
> ---
>  OvmfPkg/AcpiPlatformDxe/AcpiPlatformDxe.inf |  1 +
>  OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpi.c     | 32 +++++++++++++++++++++
>  2 files changed, 33 insertions(+)
> 
> diff --git a/OvmfPkg/AcpiPlatformDxe/AcpiPlatformDxe.inf
> b/OvmfPkg/AcpiPlatformDxe/AcpiPlatformDxe.inf
> index 8939dde42549..3fd0483b50eb 100644
> --- a/OvmfPkg/AcpiPlatformDxe/AcpiPlatformDxe.inf
> +++ b/OvmfPkg/AcpiPlatformDxe/AcpiPlatformDxe.inf
> @@ -46,6 +46,7 @@
>    UefiBootServicesTableLib
>    UefiDriverEntryPoint
>    HobLib
> +  TpmMeasurementLib
> 
>  [Protocols]
>    gEfiAcpiTableProtocolGuid                     # PROTOCOL ALWAYS_CONSUMED
> diff --git a/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpi.c
> b/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpi.c
> index f0d81d6fd73d..68abc34f2280 100644
> --- a/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpi.c
> +++ b/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpi.c
> @@ -10,6 +10,7 @@
> 
>  #include <IndustryStandard/Acpi.h>            // EFI_ACPI_DESCRIPTION_HEADER
>  #include <IndustryStandard/QemuLoader.h>      // QEMU_LOADER_FNAME_SIZE
> +#include <IndustryStandard/UefiTcgPlatform.h>
>  #include <Library/BaseLib.h>                  // AsciiStrCmp()
>  #include <Library/BaseMemoryLib.h>            // CopyMem()
>  #include <Library/DebugLib.h>                 // DEBUG()
> @@ -18,6 +19,7 @@
>  #include <Library/QemuFwCfgLib.h>             // QemuFwCfgFindFile()
>  #include <Library/QemuFwCfgS3Lib.h>           // QemuFwCfgS3Enabled()
>  #include <Library/UefiBootServicesTableLib.h> // gBS
> +#include <Library/TpmMeasurementLib.h>
> 
>  #include "AcpiPlatform.h"
> 
> @@ -415,6 +417,21 @@ ProcessCmdAllocate (
>      (UINT64)Blob->Size,
>      (UINT64)(UINTN)Blob->Base
>      ));
> +
> +  //
> +  // Measure the data which is downloaded from QEMU.
> +  // It has to be done before it is consumed. Because the data will
> +  // be updated in the following operations.
> +  //
> +  TpmMeasureAndLogData (
> +    1,
> +    EV_PLATFORM_CONFIG_FLAGS,
> +    EV_POSTCODE_INFO_ACPI_DATA,
> +    ACPI_DATA_LEN,
> +    (VOID *)(UINTN)Blob->Base,
> +    Blob->Size
> +    );
> +
>    return EFI_SUCCESS;
> 
>  FreeBlob:
> @@ -1126,6 +1143,21 @@ InstallQemuFwCfgTables (
>    QemuFwCfgSelectItem (FwCfgItem);
>    QemuFwCfgReadBytes (FwCfgSize, LoaderStart);
>    RestorePciDecoding (OriginalPciAttributes, OriginalPciAttributesCount);
> +
> +  //
> +  // Measure the "etc/table-loader" which is downloaded from QEMU.
> +  // It has to be done before it is consumed. Because it would be
> +  // updated in the following operations.
> +  //
> +  TpmMeasureAndLogData (
> +    1,
> +    EV_PLATFORM_CONFIG_FLAGS,
> +    EV_POSTCODE_INFO_ACPI_DATA,
> +    ACPI_DATA_LEN,
> +    (VOID *)(UINTN)LoaderStart,
> +    FwCfgSize
> +    );
> +
>    LoaderEnd = LoaderStart + FwCfgSize / sizeof *LoaderEntry;
> 
>    AllocationsRestrictedTo32Bit = NULL;
> --
> 2.29.2.windows.2