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
  10 #include "DxeMain.h"
  11 #include "FwVolDriver.h"
  12
  13
  14 /**
  15   Get the FFS file state by checking the highest bit set in the header's state field.
  16
  17   @param  ErasePolarity  Erase polarity attribute of the firmware volume
  18   @param  FfsHeader      Points to the FFS file header
  19
  20   @return FFS File state
  21
  22 **/
  23 EFI_FFS_FILE_STATE
  24 GetFileState (
  25   IN UINT8                ErasePolarity,
  26   IN EFI_FFS_FILE_HEADER  *FfsHeader
  27   )
  28 {
  29   EFI_FFS_FILE_STATE      FileState;
  30   UINT8                   HighestBit;
  31
  32   FileState = FfsHeader->State;
  33
  34   if (ErasePolarity != 0) {
  35     FileState = (EFI_FFS_FILE_STATE)~FileState;
  36   }
  37
  38   HighestBit = 0x80;
  39   while (HighestBit != 0 && ((HighestBit & FileState) == 0)) {
  40     HighestBit >>= 1;
  41   }
  42
  43   return (EFI_FFS_FILE_STATE) HighestBit;
  44 }
  45
  46
  47
  48 /**
  49   Check if a block of buffer is erased.
  50
  51   @param  ErasePolarity  Erase polarity attribute of the firmware volume
  52   @param  InBuffer       The buffer to be checked
  53   @param  BufferSize     Size of the buffer in bytes
  54
  55   @retval TRUE           The block of buffer is erased
  56   @retval FALSE          The block of buffer is not erased
  57
  58 **/
  59 BOOLEAN
  60 IsBufferErased (
  61   IN UINT8    ErasePolarity,
  62   IN VOID     *InBuffer,
  63   IN UINTN    BufferSize
  64   )
  65 {
  66   UINTN   Count;
  67   UINT8   EraseByte;
  68   UINT8   *Buffer;
  69
  70   if(ErasePolarity == 1) {
  71     EraseByte = 0xFF;
  72   } else {
  73     EraseByte = 0;
  74   }
  75
  76   Buffer = InBuffer;
  77   for (Count = 0; Count < BufferSize; Count++) {
  78     if (Buffer[Count] != EraseByte) {
  79       return FALSE;
  80     }
  81   }
  82
  83   return TRUE;
  84 }
  85
  86
  87
  88 /**
  89   Verify checksum of the firmware volume header.
  90
  91   @param  FvHeader       Points to the firmware volume header to be checked
  92
  93   @retval TRUE           Checksum verification passed
  94   @retval FALSE          Checksum verification failed
  95
  96 **/
  97 BOOLEAN
  98 VerifyFvHeaderChecksum (
  99   IN EFI_FIRMWARE_VOLUME_HEADER *FvHeader
 100   )
 101 {
 102   UINT16  Checksum;
 103
 104   Checksum = CalculateSum16 ((UINT16 *) FvHeader, FvHeader->HeaderLength);
 105
 106   if (Checksum == 0) {
 107     return TRUE;
 108   } else {
 109     return FALSE;
 110   }
 111 }
 112
 113
 114 /**
 115   Verify checksum of the FFS file header.
 116
 117   @param  FfsHeader      Points to the FFS file header to be checked
 118
 119   @retval TRUE           Checksum verification passed
 120   @retval FALSE          Checksum verification failed
 121
 122 **/
 123 BOOLEAN
 124 VerifyHeaderChecksum (
 125   IN EFI_FFS_FILE_HEADER  *FfsHeader
 126   )
 127 {
 128   UINT8 HeaderChecksum;
 129
 130   if (IS_FFS_FILE2 (FfsHeader)) {
 131     HeaderChecksum = CalculateSum8 ((UINT8 *) FfsHeader, sizeof (EFI_FFS_FILE_HEADER2));
 132   } else {
 133     HeaderChecksum = CalculateSum8 ((UINT8 *) FfsHeader, sizeof (EFI_FFS_FILE_HEADER));
 134   }
 135   HeaderChecksum = (UINT8) (HeaderChecksum - FfsHeader->State - FfsHeader->IntegrityCheck.Checksum.File);
 136
 137   if (HeaderChecksum == 0) {
 138     return TRUE;
 139   } else {
 140     return FALSE;
 141   }
 142 }
 143
 144
 145
 146 /**
 147   Check if it's a valid FFS file header.
 148
 149   @param  ErasePolarity  Erase polarity attribute of the firmware volume
 150   @param  FfsHeader      Points to the FFS file header to be checked
 151   @param  FileState      FFS file state to be returned
 152
 153   @retval TRUE           Valid FFS file header
 154   @retval FALSE          Invalid FFS file header
 155
 156 **/
 157 BOOLEAN
 158 IsValidFfsHeader (
 159   IN UINT8                ErasePolarity,
 160   IN EFI_FFS_FILE_HEADER  *FfsHeader,
 161   OUT EFI_FFS_FILE_STATE  *FileState
 162   )
 163 {
 164   *FileState = GetFileState (ErasePolarity, FfsHeader);
 165
 166   switch (*FileState) {
 167   case EFI_FILE_HEADER_VALID:
 168   case EFI_FILE_DATA_VALID:
 169   case EFI_FILE_MARKED_FOR_UPDATE:
 170   case EFI_FILE_DELETED:
 171     //
 172     // Here we need to verify header checksum
 173     //
 174     return VerifyHeaderChecksum (FfsHeader);
 175
 176   case EFI_FILE_HEADER_CONSTRUCTION:
 177   case EFI_FILE_HEADER_INVALID:
 178   default:
 179     return FALSE;
 180   }
 181 }
 182
 183
 184 /**
 185   Check if it's a valid FFS file.
 186   Here we are sure that it has a valid FFS file header since we must call IsValidFfsHeader() first.
 187
 188   @param  ErasePolarity  Erase polarity attribute of the firmware volume
 189   @param  FfsHeader      Points to the FFS file to be checked
 190
 191   @retval TRUE           Valid FFS file
 192   @retval FALSE          Invalid FFS file
 193
 194 **/
 195 BOOLEAN
 196 IsValidFfsFile (
 197   IN UINT8                ErasePolarity,
 198   IN EFI_FFS_FILE_HEADER  *FfsHeader
 199   )
 200 {
 201   EFI_FFS_FILE_STATE  FileState;
 202   UINT8               DataCheckSum;
 203
 204   FileState = GetFileState (ErasePolarity, FfsHeader);
 205   switch (FileState) {
 206
 207   case EFI_FILE_DELETED:
 208   case EFI_FILE_DATA_VALID:
 209   case EFI_FILE_MARKED_FOR_UPDATE:
 210     DataCheckSum = FFS_FIXED_CHECKSUM;
 211     if ((FfsHeader->Attributes & FFS_ATTRIB_CHECKSUM) == FFS_ATTRIB_CHECKSUM) {
 212       if (IS_FFS_FILE2 (FfsHeader)) {
 213         DataCheckSum = CalculateCheckSum8 ((CONST UINT8 *) FfsHeader + sizeof (EFI_FFS_FILE_HEADER2), FFS_FILE2_SIZE (FfsHeader) - sizeof(EFI_FFS_FILE_HEADER2));
 214       } else {
 215         DataCheckSum = CalculateCheckSum8 ((CONST UINT8 *) FfsHeader + sizeof (EFI_FFS_FILE_HEADER), FFS_FILE_SIZE (FfsHeader) - sizeof(EFI_FFS_FILE_HEADER));
 216       }
 217     }
 218     if (FfsHeader->IntegrityCheck.Checksum.File == DataCheckSum) {
 219       return TRUE;
 220     }
 221
 222   default:
 223     return FALSE;
 224   }
 225 }
 226
 227