VeraCrypt
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authorMounir IDRASSI <mounir.idrassi@idrix.fr>2019-10-20 21:50:41 +0200
committerMounir IDRASSI <mounir.idrassi@idrix.fr>2019-10-20 22:17:12 +0200
commit9b394ddc49c54765c4a0abf75472221963c108d2 (patch)
treec87ef65132fbac903b0500b9caf2861afe35e603
parent31a87c2e5ff2d6a66d72dea662bb2beb7a7de6f1 (diff)
downloadVeraCrypt-9b394ddc49c54765c4a0abf75472221963c108d2.tar.gz
VeraCrypt-9b394ddc49c54765c4a0abf75472221963c108d2.zip
Windows: Avoid unnecessary write operations when copying/modifying EFI bootloader files in order to avoid leaking modification timestamp
Diffstat
-rw-r--r--src/Common/BootEncryption.cpp130
-rw-r--r--src/Common/BootEncryption.h2
2 files changed, 126 insertions, 6 deletions
diff --git a/src/Common/BootEncryption.cpp b/src/Common/BootEncryption.cpp
index 50fd23d2..6131ede5 100644
--- a/src/Common/BootEncryption.cpp
+++ b/src/Common/BootEncryption.cpp
@@ -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) {
diff --git a/src/Common/BootEncryption.h b/src/Common/BootEncryption.h
index cc782966..9ae90942 100644
--- a/src/Common/BootEncryption.h
+++ b/src/Common/BootEncryption.h
@@ -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);