Merge pull request #818 from christianlouis/sentinel/fix-path-traversal-3335474446649715249

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

.jules/sentinel.md

@@ -1,4 +1,8 @@
+## 2026-03-20 - Safe Path Traversal Prevention in Low-Level Utilities
+**Vulnerability:** The generic file utility `hash_file` in `app/utils/file_operations.py` accepted any file path and was vulnerable to reading arbitrary files via path traversal (e.g., `../../../etc/passwd`) or absolute paths if an attacker could control the `filepath` argument.
+**Learning:** Naively checking for `".." in path` breaks legitimate relative paths used internally by the application. Blocking absolute paths entirely also breaks functionality. Input validation should occur at the API boundary, but for defense-in-depth, low-level utilities must enforce expected boundaries (e.g., the application's `workdir`).
+**Prevention:** Use `pathlib.Path.resolve()` on both the target path and the allowed base directory (`settings.workdir`). Ensure the resolved target path is strictly within the allowed boundary using `filepath_obj.relative_to(workdir_obj)`, catching the `ValueError` that is raised when the path is out of bounds. This safely blocks both relative traversal attacks and arbitrary absolute paths.
 ## 2025-05-18 - [SSRF Bypass via DNS Resolution Failure]
 **Vulnerability:** The `is_private_ip` function in `app/utils/network.py` failed open (returned `False`) when a hostname could not be resolved (`socket.gaierror`).
 **Learning:** This fail-open pattern was originally added to allow external domains in tests, but in production, it created a severe SSRF risk. An attacker could bypass SSRF protections by providing a URL that fails to resolve during the security check but resolves later (DNS rebinding), or by exploiting internal routing behaviors via unresolvable addresses.
-**Prevention:** Always fail securely in network authorization functions. If a domain cannot be resolved to verify its safety, the request must be blocked (`return True` / default-deny). Tests should mock DNS resolution correctly instead of compromising production security logic.
+**Prevention:** Always fail securely in network authorization functions. If a domain cannot be resolved to verify its safety, the request must be blocked (`return True` / default-deny). Tests should mock DNS resolution correctly instead of compromising production security logic.

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: