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 This program and the accompanying materials
   6 are licensed and made available under the terms and conditions of the BSD License
   7 which accompanies this distribution.  The full text of the license may be found at
   8 http://opensource.org/licenses/bsd-license.php
   9
  10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15
  16 #include "DxeMain.h"
  17 #include "FwVolDriver.h"
  18
  19
  20 /**
  21   Get the FFS file state by checking the highest bit set in the header's state field.
  22
  23   @param  ErasePolarity  Erase polarity attribute of the firmware volume
  24   @param  FfsHeader      Points to the FFS file header
  25
  26   @return FFS File state
  27
  28 **/
  29 EFI_FFS_FILE_STATE
  30 GetFileState (
  31   IN UINT8                ErasePolarity,
  32   IN EFI_FFS_FILE_HEADER  *FfsHeader
  33   )
  34 {
  35   EFI_FFS_FILE_STATE      FileState;
  36   UINT8                   HighestBit;
  37
  38   FileState = FfsHeader->State;
  39
  40   if (ErasePolarity != 0) {
  41     FileState = (EFI_FFS_FILE_STATE)~FileState;
  42   }
  43
  44   HighestBit = 0x80;
  45   while (HighestBit != 0 && ((HighestBit & FileState) == 0)) {
  46     HighestBit >>= 1;
  47   }
  48
  49   return (EFI_FFS_FILE_STATE) HighestBit;
  50 }
  51
  52
  53
  54 /**
  55   Check if a block of buffer is erased.
  56
  57   @param  ErasePolarity  Erase polarity attribute of the firmware volume
  58   @param  InBuffer       The buffer to be checked
  59   @param  BufferSize     Size of the buffer in bytes
  60
  61   @retval TRUE           The block of buffer is erased
  62   @retval FALSE          The block of buffer is not erased
  63
  64 **/
  65 BOOLEAN
  66 IsBufferErased (
  67   IN UINT8    ErasePolarity,
  68   IN VOID     *InBuffer,
  69   IN UINTN    BufferSize
  70   )
  71 {
  72   UINTN   Count;
  73   UINT8   EraseByte;
  74   UINT8   *Buffer;
  75
  76   if(ErasePolarity == 1) {
  77     EraseByte = 0xFF;
  78   } else {
  79     EraseByte = 0;
  80   }
  81
  82   Buffer = InBuffer;
  83   for (Count = 0; Count < BufferSize; Count++) {
  84     if (Buffer[Count] != EraseByte) {
  85       return FALSE;
  86     }
  87   }
  88
  89   return TRUE;
  90 }
  91
  92
  93
  94 /**
  95   Verify checksum of the firmware volume header.
  96
  97   @param  FvHeader       Points to the firmware volume header to be checked
  98
  99   @retval TRUE           Checksum verification passed
 100   @retval FALSE          Checksum verification failed
 101
 102 **/
 103 BOOLEAN
 104 VerifyFvHeaderChecksum (
 105   IN EFI_FIRMWARE_VOLUME_HEADER *FvHeader
 106   )
 107 {
 108   UINT16  Checksum;
 109
 110   Checksum = CalculateSum16 ((UINT16 *) FvHeader, FvHeader->HeaderLength);
 111
 112   if (Checksum == 0) {
 113     return TRUE;
 114   } else {
 115     return FALSE;
 116   }
 117 }
 118
 119
 120 /**
 121   Verify checksum of the FFS file header.
 122
 123   @param  FfsHeader      Points to the FFS file header to be checked
 124
 125   @retval TRUE           Checksum verification passed
 126   @retval FALSE          Checksum verification failed
 127
 128 **/
 129 BOOLEAN
 130 VerifyHeaderChecksum (
 131   IN EFI_FFS_FILE_HEADER  *FfsHeader
 132   )
 133 {
 134   UINT8 HeaderChecksum;
 135
 136   if (IS_FFS_FILE2 (FfsHeader)) {
 137     HeaderChecksum = CalculateSum8 ((UINT8 *) FfsHeader, sizeof (EFI_FFS_FILE_HEADER2));
 138   } else {
 139     HeaderChecksum = CalculateSum8 ((UINT8 *) FfsHeader, sizeof (EFI_FFS_FILE_HEADER));
 140   }
 141   HeaderChecksum = (UINT8) (HeaderChecksum - FfsHeader->State - FfsHeader->IntegrityCheck.Checksum.File);
 142
 143   if (HeaderChecksum == 0) {
 144     return TRUE;
 145   } else {
 146     return FALSE;
 147   }
 148 }
 149
 150
 151
 152 /**
 153   Check if it's a valid FFS file header.
 154
 155   @param  ErasePolarity  Erase polarity attribute of the firmware volume
 156   @param  FfsHeader      Points to the FFS file header to be checked
 157   @param  FileState      FFS file state to be returned
 158
 159   @retval TRUE           Valid FFS file header
 160   @retval FALSE          Invalid FFS file header
 161
 162 **/
 163 BOOLEAN
 164 IsValidFfsHeader (
 165   IN UINT8                ErasePolarity,
 166   IN EFI_FFS_FILE_HEADER  *FfsHeader,
 167   OUT EFI_FFS_FILE_STATE  *FileState
 168   )
 169 {
 170   *FileState = GetFileState (ErasePolarity, FfsHeader);
 171
 172   switch (*FileState) {
 173   case EFI_FILE_HEADER_VALID:
 174   case EFI_FILE_DATA_VALID:
 175   case EFI_FILE_MARKED_FOR_UPDATE:
 176   case EFI_FILE_DELETED:
 177     //
 178     // Here we need to verify header checksum
 179     //
 180     return VerifyHeaderChecksum (FfsHeader);
 181
 182   case EFI_FILE_HEADER_CONSTRUCTION:
 183   case EFI_FILE_HEADER_INVALID:
 184   default:
 185     return FALSE;
 186   }
 187 }
 188
 189
 190 /**
 191   Check if it's a valid FFS file.
 192   Here we are sure that it has a valid FFS file header since we must call IsValidFfsHeader() first.
 193
 194   @param  ErasePolarity  Erase polarity attribute of the firmware volume
 195   @param  FfsHeader      Points to the FFS file to be checked
 196
 197   @retval TRUE           Valid FFS file
 198   @retval FALSE          Invalid FFS file
 199
 200 **/
 201 BOOLEAN
 202 IsValidFfsFile (
 203   IN UINT8                ErasePolarity,
 204   IN EFI_FFS_FILE_HEADER  *FfsHeader
 205   )
 206 {
 207   EFI_FFS_FILE_STATE  FileState;
 208   UINT8               DataCheckSum;
 209
 210   FileState = GetFileState (ErasePolarity, FfsHeader);
 211   switch (FileState) {
 212
 213   case EFI_FILE_DELETED:
 214   case EFI_FILE_DATA_VALID:
 215   case EFI_FILE_MARKED_FOR_UPDATE:
 216     DataCheckSum = FFS_FIXED_CHECKSUM;
 217     if ((FfsHeader->Attributes & FFS_ATTRIB_CHECKSUM) == FFS_ATTRIB_CHECKSUM) {
 218       if (IS_FFS_FILE2 (FfsHeader)) {
 219         DataCheckSum = CalculateCheckSum8 ((CONST UINT8 *) FfsHeader + sizeof (EFI_FFS_FILE_HEADER2), FFS_FILE2_SIZE (FfsHeader) - sizeof(EFI_FFS_FILE_HEADER2));
 220       } else {
 221         DataCheckSum = CalculateCheckSum8 ((CONST UINT8 *) FfsHeader + sizeof (EFI_FFS_FILE_HEADER), FFS_FILE_SIZE (FfsHeader) - sizeof(EFI_FFS_FILE_HEADER));
 222       }
 223     }
 224     if (FfsHeader->IntegrityCheck.Checksum.File == DataCheckSum) {
 225       return TRUE;
 226     }
 227
 228   default:
 229     return FALSE;
 230   }
 231 }
 232
 233