MdeModulePkg/Core/Dxe/FwVol/Ffs.c

   1 /** @file
   2   FFS file access utilities.
   3
   4 Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>
   5 SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include "DxeMain.h"
  10 #include "FwVolDriver.h"
  11
  12 /**
  13   Get the FFS file state by checking the highest bit set in the header's state field.
  14
  15   @param  ErasePolarity  Erase polarity attribute of the firmware volume
  16   @param  FfsHeader      Points to the FFS file header
  17
  18   @return FFS File state
  19
  20 **/
  21 EFI_FFS_FILE_STATE
  22 GetFileState (
  23   IN UINT8                ErasePolarity,
  24   IN EFI_FFS_FILE_HEADER  *FfsHeader
  25   )
  26 {
  27   EFI_FFS_FILE_STATE  FileState;
  28   UINT8               HighestBit;
  29
  30   FileState = FfsHeader->State;
  31
  32   if (ErasePolarity != 0) {
  33     FileState = (EFI_FFS_FILE_STATE) ~FileState;
  34   }
  35
  36   HighestBit = 0x80;
  37   while (HighestBit != 0 && ((HighestBit & FileState) == 0)) {
  38     HighestBit >>= 1;
  39   }
  40
  41   return (EFI_FFS_FILE_STATE)HighestBit;
  42 }
  43
  44 /**
  45   Check if a block of buffer is erased.
  46
  47   @param  ErasePolarity  Erase polarity attribute of the firmware volume
  48   @param  InBuffer       The buffer to be checked
  49   @param  BufferSize     Size of the buffer in bytes
  50
  51   @retval TRUE           The block of buffer is erased
  52   @retval FALSE          The block of buffer is not erased
  53
  54 **/
  55 BOOLEAN
  56 IsBufferErased (
  57   IN UINT8  ErasePolarity,
  58   IN VOID   *InBuffer,
  59   IN UINTN  BufferSize
  60   )
  61 {
  62   UINTN  Count;
  63   UINT8  EraseByte;
  64   UINT8  *Buffer;
  65
  66   if (ErasePolarity == 1) {
  67     EraseByte = 0xFF;
  68   } else {
  69     EraseByte = 0;
  70   }
  71
  72   Buffer = InBuffer;
  73   for (Count = 0; Count < BufferSize; Count++) {
  74     if (Buffer[Count] != EraseByte) {
  75       return FALSE;
  76     }
  77   }
  78
  79   return TRUE;
  80 }
  81
  82 /**
  83   Verify checksum of the firmware volume header.
  84
  85   @param  FvHeader       Points to the firmware volume header to be checked
  86
  87   @retval TRUE           Checksum verification passed
  88   @retval FALSE          Checksum verification failed
  89
  90 **/
  91 BOOLEAN
  92 VerifyFvHeaderChecksum (
  93   IN EFI_FIRMWARE_VOLUME_HEADER  *FvHeader
  94   )
  95 {
  96   UINT16  Checksum;
  97
  98   Checksum = CalculateSum16 ((UINT16 *)FvHeader, FvHeader->HeaderLength);
  99
 100   if (Checksum == 0) {
 101     return TRUE;
 102   } else {
 103     return FALSE;
 104   }
 105 }
 106
 107 /**
 108   Verify checksum of the FFS file header.
 109
 110   @param  FfsHeader      Points to the FFS file header to be checked
 111
 112   @retval TRUE           Checksum verification passed
 113   @retval FALSE          Checksum verification failed
 114
 115 **/
 116 BOOLEAN
 117 VerifyHeaderChecksum (
 118   IN EFI_FFS_FILE_HEADER  *FfsHeader
 119   )
 120 {
 121   UINT8  HeaderChecksum;
 122
 123   if (IS_FFS_FILE2 (FfsHeader)) {
 124     HeaderChecksum = CalculateSum8 ((UINT8 *)FfsHeader, sizeof (EFI_FFS_FILE_HEADER2));
 125   } else {
 126     HeaderChecksum = CalculateSum8 ((UINT8 *)FfsHeader, sizeof (EFI_FFS_FILE_HEADER));
 127   }
 128
 129   HeaderChecksum = (UINT8)(HeaderChecksum - FfsHeader->State - FfsHeader->IntegrityCheck.Checksum.File);
 130
 131   if (HeaderChecksum == 0) {
 132     return TRUE;
 133   } else {
 134     return FALSE;
 135   }
 136 }
 137
 138 /**
 139   Check if it's a valid FFS file header.
 140
 141   @param  ErasePolarity  Erase polarity attribute of the firmware volume
 142   @param  FfsHeader      Points to the FFS file header to be checked
 143   @param  FileState      FFS file state to be returned
 144
 145   @retval TRUE           Valid FFS file header
 146   @retval FALSE          Invalid FFS file header
 147
 148 **/
 149 BOOLEAN
 150 IsValidFfsHeader (
 151   IN UINT8                ErasePolarity,
 152   IN EFI_FFS_FILE_HEADER  *FfsHeader,
 153   OUT EFI_FFS_FILE_STATE  *FileState
 154   )
 155 {
 156   *FileState = GetFileState (ErasePolarity, FfsHeader);
 157
 158   switch (*FileState) {
 159     case EFI_FILE_HEADER_VALID:
 160     case EFI_FILE_DATA_VALID:
 161     case EFI_FILE_MARKED_FOR_UPDATE:
 162     case EFI_FILE_DELETED:
 163       //
 164       // Here we need to verify header checksum
 165       //
 166       return VerifyHeaderChecksum (FfsHeader);
 167
 168     case EFI_FILE_HEADER_CONSTRUCTION:
 169     case EFI_FILE_HEADER_INVALID:
 170     default:
 171       return FALSE;
 172   }
 173 }
 174
 175 /**
 176   Check if it's a valid FFS file.
 177   Here we are sure that it has a valid FFS file header since we must call IsValidFfsHeader() first.
 178
 179   @param  ErasePolarity  Erase polarity attribute of the firmware volume
 180   @param  FfsHeader      Points to the FFS file to be checked
 181
 182   @retval TRUE           Valid FFS file
 183   @retval FALSE          Invalid FFS file
 184
 185 **/
 186 BOOLEAN
 187 IsValidFfsFile (
 188   IN UINT8                ErasePolarity,
 189   IN EFI_FFS_FILE_HEADER  *FfsHeader
 190   )
 191 {
 192   EFI_FFS_FILE_STATE  FileState;
 193   UINT8               DataCheckSum;
 194
 195   FileState = GetFileState (ErasePolarity, FfsHeader);
 196   switch (FileState) {
 197     case EFI_FILE_DELETED:
 198     case EFI_FILE_DATA_VALID:
 199     case EFI_FILE_MARKED_FOR_UPDATE:
 200       DataCheckSum = FFS_FIXED_CHECKSUM;
 201       if ((FfsHeader->Attributes & FFS_ATTRIB_CHECKSUM) == FFS_ATTRIB_CHECKSUM) {
 202         if (IS_FFS_FILE2 (FfsHeader)) {
 203           DataCheckSum = CalculateCheckSum8 ((CONST UINT8 *)FfsHeader + sizeof (EFI_FFS_FILE_HEADER2), FFS_FILE2_SIZE (FfsHeader) - sizeof (EFI_FFS_FILE_HEADER2));
 204         } else {
 205           DataCheckSum = CalculateCheckSum8 ((CONST UINT8 *)FfsHeader + sizeof (EFI_FFS_FILE_HEADER), FFS_FILE_SIZE (FfsHeader) - sizeof (EFI_FFS_FILE_HEADER));
 206         }
 207       }
 208
 209       if (FfsHeader->IntegrityCheck.Checksum.File == DataCheckSum) {
 210         return TRUE;
 211       }
 212
 213     default:
 214       return FALSE;
 215   }
 216 }