system76-edk2/SecurityPkg/Tcg/Tcg2Dxe/MeasureBootPeCoff.c

/** @file
  This module implements measuring PeCoff image for Tcg2 Protocol.

  Caution: This file requires additional review when modified.
  This driver will have external input - PE/COFF image.
  This external input must be validated carefully to avoid security issue like
  buffer overflow, integer overflow.

Copyright (c) 2015 - 2018, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent

**/

#include <PiDxe.h>

#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/MemoryAllocationLib.h>
#include <Library/DevicePathLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/PeCoffLib.h>
#include <Library/Tpm2CommandLib.h>
#include <Library/HashLib.h>

UINTN  mTcg2DxeImageSize = 0;

/**
  Reads contents of a PE/COFF image in memory buffer.

  Caution: This function may receive untrusted input.
  PE/COFF image is external input, so this function will make sure the PE/COFF image content
  read is within the image buffer.

  @param  FileHandle      Pointer to the file handle to read the PE/COFF image.
  @param  FileOffset      Offset into the PE/COFF image to begin the read operation.
  @param  ReadSize        On input, the size in bytes of the requested read operation.
                          On output, the number of bytes actually read.
  @param  Buffer          Output buffer that contains the data read from the PE/COFF image.

  @retval EFI_SUCCESS     The specified portion of the PE/COFF image was read and the size
**/
EFI_STATUS
EFIAPI
Tcg2DxeImageRead (
  IN     VOID   *FileHandle,
  IN     UINTN  FileOffset,
  IN OUT UINTN  *ReadSize,
  OUT    VOID   *Buffer
  )
{
  UINTN  EndPosition;

  if ((FileHandle == NULL) || (ReadSize == NULL) || (Buffer == NULL)) {
    return EFI_INVALID_PARAMETER;
  }

  if (MAX_ADDRESS - FileOffset < *ReadSize) {
    return EFI_INVALID_PARAMETER;
  }

  EndPosition = FileOffset + *ReadSize;
  if (EndPosition > mTcg2DxeImageSize) {
    *ReadSize = (UINT32)(mTcg2DxeImageSize - FileOffset);
  }

  if (FileOffset >= mTcg2DxeImageSize) {
    *ReadSize = 0;
  }

  CopyMem (Buffer, (UINT8 *)((UINTN)FileHandle + FileOffset), *ReadSize);

  return EFI_SUCCESS;
}

/**
  Measure PE image into TPM log based on the authenticode image hashing in
  PE/COFF Specification 8.0 Appendix A.

  Caution: This function may receive untrusted input.
  PE/COFF image is external input, so this function will validate its data structure
  within this image buffer before use.

  Notes: PE/COFF image is checked by BasePeCoffLib PeCoffLoaderGetImageInfo().

  @param[in]  PCRIndex       TPM PCR index
  @param[in]  ImageAddress   Start address of image buffer.
  @param[in]  ImageSize      Image size
  @param[out] DigestList     Digest list of this image.

  @retval EFI_SUCCESS            Successfully measure image.
  @retval EFI_OUT_OF_RESOURCES   No enough resource to measure image.
  @retval other error value
**/
EFI_STATUS
MeasurePeImageAndExtend (
  IN  UINT32                PCRIndex,
  IN  EFI_PHYSICAL_ADDRESS  ImageAddress,
  IN  UINTN                 ImageSize,
  OUT TPML_DIGEST_VALUES    *DigestList
  )
{
  EFI_STATUS                           Status;
  EFI_IMAGE_DOS_HEADER                 *DosHdr;
  UINT32                               PeCoffHeaderOffset;
  EFI_IMAGE_SECTION_HEADER             *Section;
  UINT8                                *HashBase;
  UINTN                                HashSize;
  UINTN                                SumOfBytesHashed;
  EFI_IMAGE_SECTION_HEADER             *SectionHeader;
  UINTN                                Index;
  UINTN                                Pos;
  EFI_IMAGE_OPTIONAL_HEADER_PTR_UNION  Hdr;
  UINT32                               NumberOfRvaAndSizes;
  UINT32                               CertSize;
  HASH_HANDLE                          HashHandle;
  PE_COFF_LOADER_IMAGE_CONTEXT         ImageContext;

  HashHandle = 0xFFFFFFFF; // Know bad value

  Status        = EFI_UNSUPPORTED;
  SectionHeader = NULL;

  //
  // Check PE/COFF image
  //
  ZeroMem (&ImageContext, sizeof (ImageContext));
  ImageContext.Handle    = (VOID *)(UINTN)ImageAddress;
  mTcg2DxeImageSize      = ImageSize;
  ImageContext.ImageRead = (PE_COFF_LOADER_READ_FILE)Tcg2DxeImageRead;

  //
  // Get information about the image being loaded
  //
  Status = PeCoffLoaderGetImageInfo (&ImageContext);
  if (EFI_ERROR (Status)) {
    //
    // The information can't be got from the invalid PeImage
    //
    DEBUG ((DEBUG_INFO, "Tcg2Dxe: PeImage invalid. Cannot retrieve image information.\n"));
    goto Finish;
  }

  DosHdr             = (EFI_IMAGE_DOS_HEADER *)(UINTN)ImageAddress;
  PeCoffHeaderOffset = 0;
  if (DosHdr->e_magic == EFI_IMAGE_DOS_SIGNATURE) {
    PeCoffHeaderOffset = DosHdr->e_lfanew;
  }

  Hdr.Pe32 = (EFI_IMAGE_NT_HEADERS32 *)((UINT8 *)(UINTN)ImageAddress + PeCoffHeaderOffset);
  if (Hdr.Pe32->Signature != EFI_IMAGE_NT_SIGNATURE) {
    Status = EFI_UNSUPPORTED;
    goto Finish;
  }

  //
  // PE/COFF Image Measurement
  //
  //    NOTE: The following codes/steps are based upon the authenticode image hashing in
  //      PE/COFF Specification 8.0 Appendix A.
  //
  //

  // 1.  Load the image header into memory.

  // 2.  Initialize a SHA hash context.

  Status = HashStart (&HashHandle);
  if (EFI_ERROR (Status)) {
    goto Finish;
  }

  //
  // Measuring PE/COFF Image Header;
  // But CheckSum field and SECURITY data directory (certificate) are excluded
  //

  //
  // 3.  Calculate the distance from the base of the image header to the image checksum address.
  // 4.  Hash the image header from its base to beginning of the image checksum.
  //
  HashBase = (UINT8 *)(UINTN)ImageAddress;
  if (Hdr.Pe32->OptionalHeader.Magic == EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
    //
    // Use PE32 offset
    //
    NumberOfRvaAndSizes = Hdr.Pe32->OptionalHeader.NumberOfRvaAndSizes;
    HashSize            = (UINTN)(&Hdr.Pe32->OptionalHeader.CheckSum) - (UINTN)HashBase;
  } else {
    //
    // Use PE32+ offset
    //
    NumberOfRvaAndSizes = Hdr.Pe32Plus->OptionalHeader.NumberOfRvaAndSizes;
    HashSize            = (UINTN)(&Hdr.Pe32Plus->OptionalHeader.CheckSum) - (UINTN)HashBase;
  }

  Status = HashUpdate (HashHandle, HashBase, HashSize);
  if (EFI_ERROR (Status)) {
    goto Finish;
  }

  //
  // 5.  Skip over the image checksum (it occupies a single ULONG).
  //
  if (NumberOfRvaAndSizes <= EFI_IMAGE_DIRECTORY_ENTRY_SECURITY) {
    //
    // 6.  Since there is no Cert Directory in optional header, hash everything
    //     from the end of the checksum to the end of image header.
    //
    if (Hdr.Pe32->OptionalHeader.Magic == EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
      //
      // Use PE32 offset.
      //
      HashBase = (UINT8 *)&Hdr.Pe32->OptionalHeader.CheckSum + sizeof (UINT32);
      HashSize = Hdr.Pe32->OptionalHeader.SizeOfHeaders - (UINTN)(HashBase - ImageAddress);
    } else {
      //
      // Use PE32+ offset.
      //
      HashBase = (UINT8 *)&Hdr.Pe32Plus->OptionalHeader.CheckSum + sizeof (UINT32);
      HashSize = Hdr.Pe32Plus->OptionalHeader.SizeOfHeaders - (UINTN)(HashBase - ImageAddress);
    }

    if (HashSize != 0) {
      Status = HashUpdate (HashHandle, HashBase, HashSize);
      if (EFI_ERROR (Status)) {
        goto Finish;
      }
    }
  } else {
    //
    // 7.  Hash everything from the end of the checksum to the start of the Cert Directory.
    //
    if (Hdr.Pe32->OptionalHeader.Magic == EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
      //
      // Use PE32 offset
      //
      HashBase = (UINT8 *)&Hdr.Pe32->OptionalHeader.CheckSum + sizeof (UINT32);
      HashSize = (UINTN)(&Hdr.Pe32->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY]) - (UINTN)HashBase;
    } else {
      //
      // Use PE32+ offset
      //
      HashBase = (UINT8 *)&Hdr.Pe32Plus->OptionalHeader.CheckSum + sizeof (UINT32);
      HashSize = (UINTN)(&Hdr.Pe32Plus->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY]) - (UINTN)HashBase;
    }

    if (HashSize != 0) {
      Status = HashUpdate (HashHandle, HashBase, HashSize);
      if (EFI_ERROR (Status)) {
        goto Finish;
      }
    }

    //
    // 8.  Skip over the Cert Directory. (It is sizeof(IMAGE_DATA_DIRECTORY) bytes.)
    // 9.  Hash everything from the end of the Cert Directory to the end of image header.
    //
    if (Hdr.Pe32->OptionalHeader.Magic == EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
      //
      // Use PE32 offset
      //
      HashBase = (UINT8 *)&Hdr.Pe32->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY + 1];
      HashSize = Hdr.Pe32->OptionalHeader.SizeOfHeaders - (UINTN)(HashBase - ImageAddress);
    } else {
      //
      // Use PE32+ offset
      //
      HashBase = (UINT8 *)&Hdr.Pe32Plus->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY + 1];
      HashSize = Hdr.Pe32Plus->OptionalHeader.SizeOfHeaders - (UINTN)(HashBase - ImageAddress);
    }

    if (HashSize != 0) {
      Status = HashUpdate (HashHandle, HashBase, HashSize);
      if (EFI_ERROR (Status)) {
        goto Finish;
      }
    }
  }

  //
  // 10. Set the SUM_OF_BYTES_HASHED to the size of the header
  //
  if (Hdr.Pe32->OptionalHeader.Magic == EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
    //
    // Use PE32 offset
    //
    SumOfBytesHashed = Hdr.Pe32->OptionalHeader.SizeOfHeaders;
  } else {
    //
    // Use PE32+ offset
    //
    SumOfBytesHashed = Hdr.Pe32Plus->OptionalHeader.SizeOfHeaders;
  }

  //
  // 11. Build a temporary table of pointers to all the IMAGE_SECTION_HEADER
  //     structures in the image. The 'NumberOfSections' field of the image
  //     header indicates how big the table should be. Do not include any
  //     IMAGE_SECTION_HEADERs in the table whose 'SizeOfRawData' field is zero.
  //
  SectionHeader = (EFI_IMAGE_SECTION_HEADER *)AllocateZeroPool (sizeof (EFI_IMAGE_SECTION_HEADER) * Hdr.Pe32->FileHeader.NumberOfSections);
  if (SectionHeader == NULL) {
    Status = EFI_OUT_OF_RESOURCES;
    goto Finish;
  }

  //
  // 12.  Using the 'PointerToRawData' in the referenced section headers as
  //      a key, arrange the elements in the table in ascending order. In other
  //      words, sort the section headers according to the disk-file offset of
  //      the section.
  //
  Section = (EFI_IMAGE_SECTION_HEADER *)(
                                         (UINT8 *)(UINTN)ImageAddress +
                                         PeCoffHeaderOffset +
                                         sizeof (UINT32) +
                                         sizeof (EFI_IMAGE_FILE_HEADER) +
                                         Hdr.Pe32->FileHeader.SizeOfOptionalHeader
                                         );
  for (Index = 0; Index < Hdr.Pe32->FileHeader.NumberOfSections; Index++) {
    Pos = Index;
    while ((Pos > 0) && (Section->PointerToRawData < SectionHeader[Pos - 1].PointerToRawData)) {
      CopyMem (&SectionHeader[Pos], &SectionHeader[Pos - 1], sizeof (EFI_IMAGE_SECTION_HEADER));
      Pos--;
    }

    CopyMem (&SectionHeader[Pos], Section, sizeof (EFI_IMAGE_SECTION_HEADER));
    Section += 1;
  }

  //
  // 13.  Walk through the sorted table, bring the corresponding section
  //      into memory, and hash the entire section (using the 'SizeOfRawData'
  //      field in the section header to determine the amount of data to hash).
  // 14.  Add the section's 'SizeOfRawData' to SUM_OF_BYTES_HASHED .
  // 15.  Repeat steps 13 and 14 for all the sections in the sorted table.
  //
  for (Index = 0; Index < Hdr.Pe32->FileHeader.NumberOfSections; Index++) {
    Section = (EFI_IMAGE_SECTION_HEADER *)&SectionHeader[Index];
    if (Section->SizeOfRawData == 0) {
      continue;
    }

    HashBase = (UINT8 *)(UINTN)ImageAddress + Section->PointerToRawData;
    HashSize = (UINTN)Section->SizeOfRawData;

    Status = HashUpdate (HashHandle, HashBase, HashSize);
    if (EFI_ERROR (Status)) {
      goto Finish;
    }

    SumOfBytesHashed += HashSize;
  }

  //
  // 16.  If the file size is greater than SUM_OF_BYTES_HASHED, there is extra
  //      data in the file that needs to be added to the hash. This data begins
  //      at file offset SUM_OF_BYTES_HASHED and its length is:
  //             FileSize  -  (CertDirectory->Size)
  //
  if (ImageSize > SumOfBytesHashed) {
    HashBase = (UINT8 *)(UINTN)ImageAddress + SumOfBytesHashed;

    if (NumberOfRvaAndSizes <= EFI_IMAGE_DIRECTORY_ENTRY_SECURITY) {
      CertSize = 0;
    } else {
      if (Hdr.Pe32->OptionalHeader.Magic == EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
        //
        // Use PE32 offset.
        //
        CertSize = Hdr.Pe32->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY].Size;
      } else {
        //
        // Use PE32+ offset.
        //
        CertSize = Hdr.Pe32Plus->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY].Size;
      }
    }

    if (ImageSize > CertSize + SumOfBytesHashed) {
      HashSize = (UINTN)(ImageSize - CertSize - SumOfBytesHashed);

      Status = HashUpdate (HashHandle, HashBase, HashSize);
      if (EFI_ERROR (Status)) {
        goto Finish;
      }
    } else if (ImageSize < CertSize + SumOfBytesHashed) {
      Status = EFI_UNSUPPORTED;
      goto Finish;
    }
  }

  //
  // 17.  Finalize the SHA hash.
  //
  Status = HashCompleteAndExtend (HashHandle, PCRIndex, NULL, 0, DigestList);
  if (EFI_ERROR (Status)) {
    goto Finish;
  }

Finish:
  if (SectionHeader != NULL) {
    FreePool (SectionHeader);
  }

  return Status;
}