MdeModulePkg/Core/Dxe/FwVol/Ffs.c

   1 /** @file
   2
   3   FFS file access utilities.
   4
   5 Copyright (c) 2006 - 2008, Intel Corporation
   6 All rights reserved. This program and the accompanying materials
   7 are licensed and made available under the terms and conditions of the BSD License
   8 which accompanies this distribution.  The full text of the license may be found at
   9 http://opensource.org/licenses/bsd-license.php
  10
  11 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  12 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  13
  14 **/
  15
  16
  17 #include <DxeMain.h>
  18
  19 #define PHYSICAL_ADDRESS_TO_POINTER(Address) ((VOID *)((UINTN)(Address)))
  20
  21
  22 /**
  23   Get the FFS file state by checking the highest bit set in the header's state field.
  24
  25   @param  ErasePolarity  Erase polarity attribute of the firmware volume
  26   @param  FfsHeader      Points to the FFS file header
  27
  28   @return FFS File state
  29
  30 **/
  31 EFI_FFS_FILE_STATE
  32 GetFileState (
  33   IN UINT8                ErasePolarity,
  34   IN EFI_FFS_FILE_HEADER  *FfsHeader
  35   )
  36 {
  37   EFI_FFS_FILE_STATE      FileState;
  38   UINT8                   HighestBit;
  39
  40   FileState = FfsHeader->State;
  41
  42   if (ErasePolarity != 0) {
  43     FileState = (EFI_FFS_FILE_STATE)~FileState;
  44   }
  45
  46   HighestBit = 0x80;
  47   while (HighestBit != 0 && ((HighestBit & FileState) == 0)) {
  48     HighestBit >>= 1;
  49   }
  50
  51   return (EFI_FFS_FILE_STATE)HighestBit;
  52 }
  53
  54
  55
  56 /**
  57   Check if a block of buffer is erased.
  58
  59   @param  ErasePolarity  Erase polarity attribute of the firmware volume
  60   @param  InBuffer       The buffer to be checked
  61   @param  BufferSize     Size of the buffer in bytes
  62
  63   @retval TRUE           The block of buffer is erased
  64   @retval FALSE          The block of buffer is not erased
  65
  66 **/
  67 BOOLEAN
  68 IsBufferErased (
  69   IN UINT8    ErasePolarity,
  70   IN VOID     *InBuffer,
  71   IN UINTN    BufferSize
  72   )
  73 {
  74   UINTN   Count;
  75   UINT8   EraseByte;
  76   UINT8   *Buffer;
  77
  78   if(ErasePolarity == 1) {
  79     EraseByte = 0xFF;
  80   } else {
  81     EraseByte = 0;
  82   }
  83
  84   Buffer = InBuffer;
  85   for (Count = 0; Count < BufferSize; Count++) {
  86     if (Buffer[Count] != EraseByte) {
  87       return FALSE;
  88     }
  89   }
  90
  91   return TRUE;
  92 }
  93
  94
  95
  96 /**
  97   Verify checksum of the firmware volume header.
  98
  99   @param  FvHeader       Points to the firmware volume header to be checked
 100
 101   @retval TRUE           Checksum verification passed
 102   @retval FALSE          Checksum verification failed
 103
 104 **/
 105 BOOLEAN
 106 VerifyFvHeaderChecksum (
 107   IN EFI_FIRMWARE_VOLUME_HEADER *FvHeader
 108   )
 109 {
 110   UINT32  Index;
 111   UINT32  HeaderLength;
 112   UINT16  Checksum;
 113   UINT16  *Ptr;
 114
 115   HeaderLength = FvHeader->HeaderLength;
 116   Ptr = (UINT16 *)FvHeader;
 117   Checksum = 0;
 118
 119   for (Index = 0; Index < HeaderLength / sizeof (UINT16); Index++) {
 120     Checksum = (UINT16)(Checksum + Ptr[Index]);
 121   }
 122
 123   if (Checksum == 0) {
 124     return TRUE;
 125   } else {
 126     return FALSE;
 127   }
 128 }
 129
 130
 131 /**
 132   Verify checksum of the FFS file header.
 133
 134   @param  FfsHeader      Points to the FFS file header to be checked
 135
 136   @retval TRUE           Checksum verification passed
 137   @retval FALSE          Checksum verification failed
 138
 139 **/
 140 STATIC
 141 BOOLEAN
 142 VerifyHeaderChecksum (
 143   IN EFI_FFS_FILE_HEADER  *FfsHeader
 144   )
 145 {
 146   UINT32            Index;
 147   UINT8             *Ptr;
 148   UINT8             HeaderChecksum;
 149
 150   Ptr = (UINT8 *)FfsHeader;
 151   HeaderChecksum = 0;
 152   for (Index = 0; Index < sizeof(EFI_FFS_FILE_HEADER); Index++) {
 153     HeaderChecksum = (UINT8)(HeaderChecksum + Ptr[Index]);
 154   }
 155
 156   HeaderChecksum = (UINT8) (HeaderChecksum - FfsHeader->State - FfsHeader->IntegrityCheck.Checksum.File);
 157
 158   if (HeaderChecksum == 0) {
 159     return TRUE;
 160   } else {
 161     return FALSE;
 162   }
 163 }
 164
 165
 166
 167 /**
 168   Check if it's a valid FFS file header.
 169
 170   @param  ErasePolarity  Erase polarity attribute of the firmware volume
 171   @param  FfsHeader      Points to the FFS file header to be checked
 172   @param  FileState      FFS file state to be returned
 173
 174   @retval TRUE           Valid FFS file header
 175   @retval FALSE          Invalid FFS file header
 176
 177 **/
 178 BOOLEAN
 179 IsValidFfsHeader (
 180   IN UINT8                ErasePolarity,
 181   IN EFI_FFS_FILE_HEADER  *FfsHeader,
 182   OUT EFI_FFS_FILE_STATE  *FileState
 183   )
 184 {
 185   *FileState = GetFileState (ErasePolarity, FfsHeader);
 186
 187   switch (*FileState) {
 188     case EFI_FILE_HEADER_VALID:
 189     case EFI_FILE_DATA_VALID:
 190     case EFI_FILE_MARKED_FOR_UPDATE:
 191     case EFI_FILE_DELETED:
 192       //
 193       // Here we need to verify header checksum
 194       //
 195       return VerifyHeaderChecksum (FfsHeader);
 196
 197     case EFI_FILE_HEADER_CONSTRUCTION:
 198     case EFI_FILE_HEADER_INVALID:
 199     default:
 200       return FALSE;
 201   }
 202 }
 203
 204
 205
 206 /**
 207   Check if it's a valid FFS file.
 208   Here we are sure that it has a valid FFS file header since we must call IsValidFfsHeader() first.
 209
 210   @param  ErasePolarity  Erase polarity attribute of the firmware volume
 211   @param  FfsHeader      Points to the FFS file to be checked
 212
 213   @retval TRUE           Valid FFS file
 214   @retval FALSE          Invalid FFS file
 215
 216 **/
 217 BOOLEAN
 218 IsValidFfsFile (
 219   IN UINT8                ErasePolarity,
 220   IN EFI_FFS_FILE_HEADER  *FfsHeader
 221   )
 222 {
 223   EFI_FFS_FILE_STATE  FileState;
 224
 225   FileState = GetFileState (ErasePolarity, FfsHeader);
 226   switch (FileState) {
 227
 228     case EFI_FILE_DELETED:
 229     case EFI_FILE_DATA_VALID:
 230     case EFI_FILE_MARKED_FOR_UPDATE:
 231       //
 232       // Some other vliadation like file content checksum might be done here.
 233       // For performance issue, Tiano only do FileState check.
 234       //
 235       return TRUE;
 236
 237     default:
 238       return FALSE;
 239   }
 240 }
 241
 242