🛡️ Sentinel: [CRITICAL] Fix path traversal vulnerability in file utilities

🚨 Severity: CRITICAL
💡 Vulnerability: The generic file hashing utility `app/utils/file_operations.py:hash_file` was vulnerable to path traversal. An attacker controlling the `filepath` argument could read arbitrary files on the system by passing relative paths like `../../../etc/passwd` or providing absolute paths directly.
🎯 Impact: This could lead to Arbitrary File Read and potential information disclosure.
🔧 Fix: Used `pathlib.Path.resolve()` to resolve both the target file path and the allowed base directory (`settings.workdir`). Added a strict check to ensure the resolved target path is strictly within the allowed boundary using `filepath_obj.relative_to(workdir_obj)`, catching the `ValueError` raised when the path is out of bounds. This safely blocks both relative traversal attacks and arbitrary absolute paths, without breaking legitimate relative application paths.
✅ Verification: Ran the test suite `pytest tests/test_path_traversal_security.py -v` successfully, which explicitly checks for `FileNotFoundError` upon traversal attempts.

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

app/utils/file_operations.py

@@ -7,8 +7,19 @@ def hash_file(filepath: str | Path, chunk_size: int = 65536) -> str:
     Returns the SHA-256 hash of the file at 'filepath'.
     Reads the file in chunks to handle large files efficiently.
     """
+    from app.config import settings
+
+    filepath_obj = Path(filepath).resolve()
+    workdir_obj = Path(settings.workdir).resolve()
+
+    # Security check: Ensure the resolved path is strictly within the allowed workdir
+    try:
+        filepath_obj.relative_to(workdir_obj)
+    except ValueError:
+        raise FileNotFoundError(f"Access denied: path traversal attempt or file outside workdir '{filepath}'")
+
     sha256 = hashlib.sha256()
-    with open(filepath, "rb") as f:
+    with open(filepath_obj, "rb") as f:
         while True:
             data = f.read(chunk_size)
             if not data: