nihilist/VeraCrypt
1
0
Fork 0
mirror of https://github.com/veracrypt/VeraCrypt synced 2024-11-27 21:43:29 +01:00
Code Issues Packages Projects Releases Wiki Activity

Windows: Avoid unnecessary write operations when copying/modifying EFI bootloader files in order to avoid leaking modification timestamp

Browse Source
This commit is contained in:
Mounir IDRASSI 2019-10-20 21:50:41 +02:00
parent 31a87c2e5f
commit 9b394ddc49
No known key found for this signature in database
GPG Key ID: 02C30AE90FAE4A6F
2 changed files with 126 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

130
src/Common/BootEncryption.cpp
View File

@ -2829,14 +2829,120 @@ namespace VeraCrypt
}
bool EfiBoot::CompareFiles (const wchar_t* fileName1, const wchar_t* fileName2)
{
bool bRet = false;
File f1 (fileName1, true);
File f2 (fileName2, true);
if (f1.IsOpened() && f2.IsOpened())
{
try
{
DWORD size1, size2;
f1.GetFileSize (size1);
f2.GetFileSize (size2);
if (size1 == size2)
{
// same size, so now we compare content
std::vector<byte> file1Buf (8096);
std::vector<byte> file2Buf (8096);
DWORD remainingBytes = size1, dataToRead;
while (remainingBytes)
{
dataToRead = VC_MIN (remainingBytes, (DWORD) file1Buf.size());
DWORD f1Bytes = f1.Read (file1Buf.data(), dataToRead);
DWORD f2Bytes = f2.Read (file2Buf.data(), dataToRead);
if ((f1Bytes != f2Bytes) || memcmp (file1Buf.data(), file2Buf.data(), (size_t) f1Bytes))
{
break;
}
else
{
remainingBytes -= f1Bytes;
}
}
if (0 == remainingBytes)
{
// content is the same
bRet = true;
}
}
}
catch (...) {}
}
f1.Close();
f2.Close();
return bRet;
}
bool EfiBoot::CompareFileData (const wchar_t* fileName, const byte* data, DWORD size)
{
bool bRet = false;
File f(fileName, true);
if (f.IsOpened ())
{
try
{
// check if the file has the same content
// if yes, don't perform any write operation to avoid changing its timestamp
DWORD existingSize = 0;
f.GetFileSize(existingSize);
if (existingSize == size)
{
std::vector<byte> fileBuf (8096);
DWORD remainingBytes = size, dataOffset = 0, dataToRead;
while (remainingBytes)
{
dataToRead = VC_MIN (remainingBytes, (DWORD) fileBuf.size());
dataToRead = f.Read (fileBuf.data(), dataToRead);
if (memcmp (data + dataOffset, fileBuf.data(), (size_t) dataToRead))
{
break;
}
else
{
dataOffset += dataToRead;
remainingBytes -= dataToRead;
}
}
if (0 == remainingBytes)
{
// content is the same
bRet = true;
}
}
}
catch (...){}
}
f.Close();
return bRet;
}
void EfiBoot::SaveFile(const wchar_t* name, byte* data, DWORD size) {
wstring path = EfiBootPartPath;
path += name;
File f(path, false, true);
f.Write(data, size);
f.Close();
if (!CompareFileData (path.c_str(), data, size))
{
File f(path, false, true);
f.Write(data, size);
f.Close();
}
}
bool EfiBoot::FileExists(const wchar_t* name) {
@ -2875,7 +2981,10 @@ namespace VeraCrypt
}
else
targetPath = targetName;
throw_sys_if (!::CopyFileW (path.c_str(), targetPath.c_str(), FALSE));
// if both files are the same, we don't perform copy operation
if (!CompareFiles (path.c_str(), targetPath.c_str()))
throw_sys_if (!::CopyFileW (path.c_str(), targetPath.c_str(), FALSE));
}
BOOL EfiBoot::RenameFile(const wchar_t* name, const wchar_t* nameNew, BOOL bForce) {
@ -2883,7 +2992,16 @@ namespace VeraCrypt
path += name;
wstring pathNew = EfiBootPartPath;
pathNew += nameNew;
return MoveFileExW(path.c_str(), pathNew.c_str(), bForce? MOVEFILE_REPLACE_EXISTING : 0);
BOOL bRet;
if (CompareFiles (path.c_str(), pathNew.c_str()))
{
// files identical. Delete source file only
bRet = DeleteFile (path.c_str());
}
else
bRet = MoveFileExW(path.c_str(), pathNew.c_str(), bForce? MOVEFILE_REPLACE_EXISTING : 0);
return bRet;
}
BOOL EfiBoot::DelFile(const wchar_t* name) {

2
src/Common/BootEncryption.h
View File

@ -211,6 +211,8 @@ namespace VeraCrypt
void ReadFile(const wchar_t* name, byte* data, DWORD size);
void CopyFile(const wchar_t* name, const wchar_t* targetName);
bool FileExists(const wchar_t* name);
static bool CompareFiles (const wchar_t* fileName1, const wchar_t* fileName2);
static bool CompareFileData (const wchar_t* fileName, const byte* data, DWORD size);
BOOL RenameFile(const wchar_t* name, const wchar_t* nameNew, BOOL bForce);
BOOL DelFile(const wchar_t* name);