Re: [edk2-devel] [PATCH v2 5/9] MdeModulePkg/Core: Create Migrated FV Info Hob for calculating hash (CVE-2019-11098)

["Laszlo Ersek" <lersek@redhat.com>]

On 07/02/20 07:15, Guomin Jiang wrote:
> REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1614
> 
> When we allocate pool to save rebased the PEIMs, the address will change
> randomly, therefore the hash will change and result PCR0 change as well.
> To avoid this, we save the raw PEIMs and use it to calculate hash.

(1) Please extend the commit message. We should state that
"gEdkiiMigratedFvInfoGuid" HOBs are *never* produced if
"PcdMigrateTemporaryRamFirmwareVolumes" is FALSE.

> 
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Hao A Wu <hao.a.wu@intel.com>
> Cc: Dandan Bi <dandan.bi@intel.com>
> Cc: Liming Gao <liming.gao@intel.com>
> Cc: Debkumar De <debkumar.de@intel.com>
> Cc: Harry Han <harry.han@intel.com>
> Cc: Catharine West <catharine.west@intel.com>
> Signed-off-by: Guomin Jiang <guomin.jiang@intel.com>
> ---
>  MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c | 15 +++++++++++++
>  MdeModulePkg/Core/Pei/PeiMain.h               |  1 +
>  MdeModulePkg/Core/Pei/PeiMain.inf             |  1 +
>  MdeModulePkg/Include/Guid/MigratedFvInfo.h    | 22 +++++++++++++++++++
>  MdeModulePkg/MdeModulePkg.dec                 |  3 +++
>  5 files changed, 42 insertions(+)
>  create mode 100644 MdeModulePkg/Include/Guid/MigratedFvInfo.h
> 
> diff --git a/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c b/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c
> index ef88b3423376..7e1ac38f35c8 100644
> --- a/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c
> +++ b/MdeModulePkg/Core/Pei/Dispatcher/Dispatcher.c
> @@ -1223,10 +1223,12 @@ EvacuateTempRam (
>    EFI_FIRMWARE_VOLUME_HEADER    *FvHeader;
>    EFI_FIRMWARE_VOLUME_HEADER    *ChildFvHeader;
>    EFI_FIRMWARE_VOLUME_HEADER    *MigratedFvHeader;
> +  EFI_FIRMWARE_VOLUME_HEADER    *RawDataFvHeader;
>    EFI_FIRMWARE_VOLUME_HEADER    *MigratedChildFvHeader;
>  
>    PEI_CORE_FV_HANDLE            PeiCoreFvHandle;
>    EFI_PEI_CORE_FV_LOCATION_PPI  *PeiCoreFvLocationPpi;
> +  EDKII_MIGRATED_FV_INFO        MigratedFvInfo;
>  
>    ASSERT (Private->PeiMemoryInstalled);
>  
> @@ -1270,6 +1272,13 @@ EvacuateTempRam (
>                    );
>        ASSERT_EFI_ERROR (Status);
>  
> +      Status =  PeiServicesAllocatePages (
> +                  EfiBootServicesCode,
> +                  EFI_SIZE_TO_PAGES ((UINTN) FvHeader->FvLength),
> +                  (EFI_PHYSICAL_ADDRESS *) &RawDataFvHeader
> +                  );
> +      ASSERT_EFI_ERROR (Status);
> +
>        DEBUG ((
>          DEBUG_VERBOSE,
>          "  Migrating FV[%d] from 0x%08X to 0x%08X\n",
> @@ -1279,6 +1288,12 @@ EvacuateTempRam (
>          ));
>  
>        CopyMem (MigratedFvHeader, FvHeader, (UINTN) FvHeader->FvLength);
> +      CopyMem (RawDataFvHeader, MigratedFvHeader, (UINTN) FvHeader->FvLength);
> +      MigratedFvInfo.FvOrgBase  = (UINT32) (UINTN) FvHeader;
> +      MigratedFvInfo.FvNewBase  = (UINT32) (UINTN) MigratedFvHeader;
> +      MigratedFvInfo.FvDataBase = (UINT32) (UINTN) RawDataFvHeader;
> +      MigratedFvInfo.FvLength   = (UINT32) (UINTN) FvHeader->FvLength;
> +      BuildGuidDataHob (&gEdkiiMigratedFvInfoGuid, &MigratedFvInfo, sizeof (MigratedFvInfo));
>  
>        //
>        // Migrate any children for this FV now

(2) Please repeat the same statement here (from the commit message).

That statement is very important for understanding the control flow of
this feature. Some of the other modules do not consult
"PcdMigrateTemporaryRamFirmwareVolumes"; instead, they consume
"gEdkiiMigratedFvInfoGuid" HOBs.

We should explain (both in the commit message and in the code) that
"PcdMigrateTemporaryRamFirmwareVolumes" controls the *latter* kind of
modules too, via the production of "gEdkiiMigratedFvInfoGuid" HOBs. (In
other words, if the PCD is FALSE, such HOBs are never produced.)

Thanks
Laszlo

> diff --git a/MdeModulePkg/Core/Pei/PeiMain.h b/MdeModulePkg/Core/Pei/PeiMain.h
> index b0101dba5e30..cbf74d5b9d9a 100644
> --- a/MdeModulePkg/Core/Pei/PeiMain.h
> +++ b/MdeModulePkg/Core/Pei/PeiMain.h
> @@ -44,6 +44,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
>  #include <Guid/FirmwareFileSystem2.h>
>  #include <Guid/FirmwareFileSystem3.h>
>  #include <Guid/AprioriFileName.h>
> +#include <Guid/MigratedFvInfo.h>
>  
>  ///
>  /// It is an FFS type extension used for PeiFindFileEx. It indicates current
> diff --git a/MdeModulePkg/Core/Pei/PeiMain.inf b/MdeModulePkg/Core/Pei/PeiMain.inf
> index 5ff14100a65f..c80d16b4efa6 100644
> --- a/MdeModulePkg/Core/Pei/PeiMain.inf
> +++ b/MdeModulePkg/Core/Pei/PeiMain.inf
> @@ -77,6 +77,7 @@ [Guids]
>    ## CONSUMES   ## GUID      # Used to compare with FV's file system GUID and get the FV's file system format
>    gEfiFirmwareFileSystem3Guid
>    gStatusCodeCallbackGuid
> +  gEdkiiMigratedFvInfoGuid                      ## SOMETIMES_PRODUCES     ## HOB
>  
>  [Ppis]
>    gEfiPeiStatusCodePpiGuid                      ## SOMETIMES_CONSUMES # PeiReportStatusService is not ready if this PPI doesn't exist
> diff --git a/MdeModulePkg/Include/Guid/MigratedFvInfo.h b/MdeModulePkg/Include/Guid/MigratedFvInfo.h
> new file mode 100644
> index 000000000000..061c17ed0e48
> --- /dev/null
> +++ b/MdeModulePkg/Include/Guid/MigratedFvInfo.h
> @@ -0,0 +1,22 @@
> +/** @file
> +  Migrated FV information
> +
> +Copyright (c) 2020, Intel Corporation. All rights reserved.<BR>
> +SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +**/
> +
> +#ifndef __EDKII_MIGRATED_FV_INFO_GUID_H__
> +#define __EDKII_MIGRATED_FV_INFO_GUID_H__
> +
> +typedef struct {
> +  UINT32           FvOrgBase;  // original FV address
> +  UINT32           FvNewBase;  // new FV address
> +  UINT32           FvDataBase; // original FV data
> +  UINT32           FvLength;   // Fv Length
> +} EDKII_MIGRATED_FV_INFO;
> +
> +extern EFI_GUID gEdkiiMigratedFvInfoGuid;
> +
> +#endif // #ifndef __EDKII_MIGRATED_FV_INFO_GUID_H__
> +
> diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
> index 843e963ad34b..5e25cbe98ada 100644
> --- a/MdeModulePkg/MdeModulePkg.dec
> +++ b/MdeModulePkg/MdeModulePkg.dec
> @@ -389,6 +389,9 @@ [Guids]
>    ## GUID indicates the capsule is to store Capsule On Disk file names.
>    gEdkiiCapsuleOnDiskNameGuid = { 0x98c80a4f, 0xe16b, 0x4d11, { 0x93, 0x9a, 0xab, 0xe5, 0x61, 0x26, 0x3, 0x30 } }
>  
> +  ## Include/Guid/MigratedFvInfo.h
> +  gEdkiiMigratedFvInfoGuid = { 0xc1ab12f7, 0x74aa, 0x408d, { 0xa2, 0xf4, 0xc6, 0xce, 0xfd, 0x17, 0x98, 0x71 } }
> +
>  [Ppis]
>    ## Include/Ppi/AtaController.h
>    gPeiAtaControllerPpiGuid       = { 0xa45e60d1, 0xc719, 0x44aa, { 0xb0, 0x7a, 0xaa, 0x77, 0x7f, 0x85, 0x90, 0x6d }}
>