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Fix: Path Traversal (Zip Slip) in UnpackArchive + UB in CutFirstSlash #45

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Fix: Path Traversal (Zip Slip) in UnpackArchive + UB in CutFirstSlash #45

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c8477d0
Fix: Path Traversal (Zip Slip) in UnpackArchive + UB in CutFirstSlash
coal228 Jun 16, 2026
d78856c
refactor: use native TFsPath::IsChildOf, fix UB with empty strings
coal228 Jun 16, 2026
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36 changes: 28 additions & 8 deletions tools/archiver/main.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -109,7 +109,6 @@ namespace {
}

private:
// width in source chars
static const size_t Columns = 10;
ui64 Count_ = 0;
IOutputStream* Slave_ = nullptr;
Expand Down Expand Up @@ -196,7 +195,6 @@ namespace {
}

void DoFinish() override {
//*O << ";\nextern const unsigned char* " << B << " = (const unsigned char*)" << B << "Array;\n";
*O << ";\nextern const unsigned int " << B << "Size = sizeof(" << B << ") / sizeof(" << B << "[0]) - 1;\n}\n";
}

Expand Down Expand Up @@ -302,7 +300,11 @@ static inline bool IsDelim(char ch) noexcept {
return ch == '/' || ch == '\\';
}

// FIX: защита от UB при пустой строке
static inline TString GetFile(const TString& s) {
if (s.empty()) {
return {};
}
const char* e = s.end();
const char* b = s.begin();
const char* c = e - 1;
Expand Down Expand Up @@ -414,12 +416,12 @@ namespace {
};
}

// FIX: защита от UB при пустом ключе архива
static TString CutFirstSlash(const TString& fileName) {
if (fileName[0] == '/') {
if (!fileName.empty() && fileName[0] == '/') {
return fileName.substr(1);
} else {
return fileName;
}
return fileName;
}

struct TMappingReader {
Expand All @@ -439,13 +441,30 @@ static void UnpackArchive(const TString& archive, const TFsPath& dir = TFsPath()
TMappingReader mappingReader(archive);
const TArchiveReader& reader = mappingReader.Reader;
const size_t count = reader.Count();

// FIX: Path Traversal (Zip Slip).
// Приводим целевую директорию к абсолютному пути один раз до цикла.
// Это необходимо для корректной работы IsChildOf().
const TFsPath targetDir = (dir.IsDefined() ? dir : TFsPath::Cwd()).Absolute();

for (size_t i = 0; i < count; ++i) {
const TString key = reader.KeyByIndex(i);
const TString fileName = CutFirstSlash(key);
if (!Quiet) {
Cerr << archive << " --> " << fileName << Endl;
}
const TFsPath path(dir / fileName);

// Собираем итоговый путь и приводим к абсолютному виду
const TFsPath path = (targetDir / fileName).Absolute();

// Защита от Path Traversal: IsChildOf() делает покомпонентное сравнение
// путей и гарантирует что файл не запишется за пределы targetDir.
// Атака вида "../../etc/passwd" будет поймана здесь.
if (!path.IsChildOf(targetDir)) {
ythrow yexception()
<< "Security: Path Traversal attempt detected in archive entry: " << key;
}

path.Parent().MkDirs();
TAutoPtr<IInputStream> in = reader.ObjectByKey(key);
TFixedBufferFileOutput out(path);
Expand Down Expand Up @@ -617,7 +636,8 @@ int main(int argc, char** argv) {
const auto& path = files[i];
size_t off = 0;
#ifdef _win_
if (path[0] > 0 && isalpha(path[0]) && path[1] == ':')
// FIX: проверка размера строки перед обращением к path[1]
if (path.size() >= 2 && path[0] > 0 && isalpha(path[0]) && path[1] == ':')
off = 2; // skip drive letter ("d:")
#endif // _win_
const size_t pos = path.find(':', off);
Expand Down Expand Up @@ -699,4 +719,4 @@ int main(int argc, char** argv) {
}

return 0;
}
}