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Annotation of truecrypt/boot/windows/bootencryptedio.cpp, revision 1.1.1.3

1.1       root        1: /*
                      2:  Copyright (c) 2008 TrueCrypt Foundation. All rights reserved.
                      3: 
1.1.1.3 ! root        4:  Governed by the TrueCrypt License 2.5 the full text of which is contained
1.1       root        5:  in the file License.txt included in TrueCrypt binary and source code
                      6:  distribution packages.
                      7: */
                      8: 
                      9: #include "Crypto.h"
                     10: #include "Platform.h"
                     11: #include "BootConfig.h"
                     12: #include "BootDebug.h"
1.1.1.2   root       13: #include "BootDefs.h"
1.1       root       14: #include "BootDiskIo.h"
                     15: #include "BootEncryptedIo.h"
                     16: 
                     17: 
                     18: BiosResult ReadEncryptedSectors (uint16 destSegment, uint16 destOffset, byte drive, uint64 sector, uint16 sectorCount)
                     19: {
                     20:        BiosResult result;
1.1.1.3 ! root       21:        bool decrypt = true;
        !            22: 
        !            23:        if (BootCryptoInfo->hiddenVolume)
        !            24:        {
        !            25:                if (ReadWritePartiallyCoversEncryptedArea (sector, sectorCount))
        !            26:                        return BiosResultInvalidFunction;
        !            27: 
        !            28:                if (sector >= EncryptedVirtualPartition.StartSector && sector <= EncryptedVirtualPartition.EndSector)
        !            29:                {
        !            30:                        // Remap the request to the hidden volume
        !            31:                        sector -= EncryptedVirtualPartition.StartSector;
        !            32:                        sector += HiddenVolumeStartSector;
        !            33:                }
        !            34:                else
        !            35:                        decrypt = false;
        !            36:        }
1.1       root       37: 
1.1.1.2   root       38:        result = ReadSectors (destSegment, destOffset, drive, sector, sectorCount);
1.1       root       39: 
1.1.1.3 ! root       40:        if (result != BiosResultSuccess || !decrypt)
1.1.1.2   root       41:                return result;
1.1       root       42: 
1.1.1.3 ! root       43:        if (BootCryptoInfo->hiddenVolume)
        !            44:        {
        !            45:                // Convert sector number to data unit number of the hidden volume
        !            46:                sector -= HiddenVolumeStartSector;
        !            47:                sector += HiddenVolumeStartUnitNo;
        !            48:        }
        !            49: 
1.1.1.2   root       50:        if (drive == EncryptedVirtualPartition.Drive)
                     51:        {
                     52:                while (sectorCount-- > 0)
1.1       root       53:                {
1.1.1.3 ! root       54:                        if (BootCryptoInfo->hiddenVolume
        !            55:                                || (sector >= EncryptedVirtualPartition.StartSector && sector <= EncryptedVirtualPartition.EndSector))
1.1.1.2   root       56:                        {
                     57:                                AcquireSectorBuffer();
                     58:                                CopyMemory (destSegment, destOffset, SectorBuffer, TC_LB_SIZE);
                     59: 
                     60:                                DecryptDataUnits (SectorBuffer, &sector, 1, BootCryptoInfo);
                     61: 
                     62:                                CopyMemory (SectorBuffer, destSegment, destOffset, TC_LB_SIZE);
                     63:                                ReleaseSectorBuffer();
                     64:                        }
1.1       root       65: 
1.1.1.2   root       66:                        ++sector;
                     67:                        destOffset += TC_LB_SIZE;
                     68:                }
1.1       root       69:        }
                     70: 
                     71:        return result;
                     72: }
                     73: 
                     74: 
                     75: BiosResult WriteEncryptedSectors (uint16 sourceSegment, uint16 sourceOffset, byte drive, uint64 sector, uint16 sectorCount)
                     76: {
                     77:        BiosResult result;
1.1.1.2   root       78:        AcquireSectorBuffer();
1.1.1.3 ! root       79:        uint64 dataUnitNo;
        !            80:        uint64 writeOffset;
        !            81: 
        !            82:        dataUnitNo = sector;
        !            83:        writeOffset.HighPart = 0;
        !            84:        writeOffset.LowPart = 0;
        !            85: 
        !            86:        if (BootCryptoInfo->hiddenVolume)
        !            87:        {
        !            88:                if (ReadWritePartiallyCoversEncryptedArea (sector, sectorCount))
        !            89:                        return BiosResultInvalidFunction;
        !            90: 
        !            91:                // Remap the request to the hidden volume
        !            92:                writeOffset = HiddenVolumeStartSector;
        !            93:                writeOffset -= EncryptedVirtualPartition.StartSector;
        !            94:                dataUnitNo -= EncryptedVirtualPartition.StartSector;
        !            95:                dataUnitNo += HiddenVolumeStartUnitNo;
        !            96:        }
1.1       root       97: 
                     98:        while (sectorCount-- > 0)
                     99:        {
1.1.1.2   root      100:                CopyMemory (sourceSegment, sourceOffset, SectorBuffer, TC_LB_SIZE);
1.1       root      101: 
                    102:                if (drive == EncryptedVirtualPartition.Drive && sector >= EncryptedVirtualPartition.StartSector && sector <= EncryptedVirtualPartition.EndSector)
                    103:                {
1.1.1.3 ! root      104:                        EncryptDataUnits (SectorBuffer, &dataUnitNo, 1, BootCryptoInfo);
1.1       root      105:                }
                    106: 
1.1.1.3 ! root      107:                result = WriteSectors (SectorBuffer, drive, sector + writeOffset, 1);
1.1       root      108: 
                    109:                if (result != BiosResultSuccess)
1.1.1.2   root      110:                        break;
1.1       root      111: 
                    112:                ++sector;
1.1.1.3 ! root      113:                ++dataUnitNo;
1.1.1.2   root      114:                sourceOffset += TC_LB_SIZE;
1.1       root      115:        }
                    116: 
1.1.1.2   root      117:        ReleaseSectorBuffer();
1.1       root      118:        return result;
                    119: }
1.1.1.3 ! root      120: 
        !           121: 
        !           122: static bool ReadWritePartiallyCoversEncryptedArea (const uint64 &sector, uint16 sectorCount)
        !           123: {
        !           124:        uint64 readWriteEnd = sector + --sectorCount;
        !           125: 
        !           126:        return ((sector < EncryptedVirtualPartition.StartSector && readWriteEnd >= EncryptedVirtualPartition.StartSector)
        !           127:                || (sector >= EncryptedVirtualPartition.StartSector && readWriteEnd > EncryptedVirtualPartition.EndSector));
        !           128: }

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