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moveToTrash/Unix: avoid TOCTOU in creating the unique file name

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This is not a security issue because we still use QIODevice::NewOnly
(O_EXCL) and loop again. But because we do so, we don't need to check
for existence with QFile::exists() in the first place.

Change-Id: I9d43e5b91eb142d6945cfffd1786c98a39781517
(cherry picked from commit de24134aa7795a05ba271a751bf76792f9a3ff98)
Reviewed-by: Ahmad Samir <a.samirh78@gmail.com>
This commit is contained in:
Thiago Macieira 2023-09-20 19:38:25 -07:00 committed by Ahmad Samir
parent 4aba04d2ca
commit 28064908e0
1 changed files with 6 additions and 11 deletions
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17
src/corelib/io/qfilesystemengine_unix.cpp
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@ -1329,14 +1329,9 @@ bool QFileSystemEngine::moveFileToTrash(const QFileSystemEntry &source,
*/
QString uniqueTrashedName = u'/' + sourcePath.fileName();
QString infoFileName;
int counter = 0;
QFile infoFile;
auto makeUniqueTrashedName = [sourcePath, &counter]() -> QString {
return QString::asprintf("/%ls-%04d", qUtf16Printable(sourcePath.fileName()), ++counter);
};
do {
while (QFile::exists(trashDir.filePath(filesDir) + uniqueTrashedName))
uniqueTrashedName = makeUniqueTrashedName();
auto openMode = QIODevice::NewOnly | QIODevice::WriteOnly | QIODevice::Text;
for (int counter = 0; !infoFile.open(openMode); ++counter) {
/*
"The $trash/info directory contains an "information file" for every file and directory
in $trash/files. This file MUST have exactly the same name as the file or directory in
@ -1349,12 +1344,12 @@ bool QFileSystemEngine::moveFileToTrash(const QFileSystemEntry &source,
filename, and then opening with O_EXCL. If that succeeds the creation was atomic
(at least on the same machine), if it fails you need to pick another filename."
*/
infoFileName = trashDir.filePath(infoDir)
uniqueTrashedName = QString::asprintf("/%ls-%04d", qUtf16Printable(sourcePath.fileName()),
counter);
QString infoFileName = trashDir.filePath(infoDir)
+ uniqueTrashedName + ".trashinfo"_L1;
infoFile.setFileName(infoFileName);
if (!infoFile.open(QIODevice::NewOnly | QIODevice::WriteOnly | QIODevice::Text))
uniqueTrashedName = makeUniqueTrashedName();
} while (!infoFile.isOpen());
}
QString pathForInfo = sourcePath.filePath();
const QStorageInfo storageInfo(pathForInfo);