🛡️ Sentinel: [HIGH] hmac.compare_digest DoS 취약점 수정

.jules/sentinel.md

@@ -65,3 +65,7 @@
 **Vulnerability:** Path traversal in `media_shrinker.py` via unresolved `..` segments or symlink escapes before deriving conversion output paths.
 **Learning:** `Path.relative_to()` is only a lexical containment check unless both the source and root have first been resolved into canonical absolute paths. Relative paths and symlinks can otherwise bypass root-boundary assumptions.
 **Prevention:** Resolve both source and root once, reject sources outside the resolved root with a sanitized `MediaShrinkerError`, and derive `rel_source` from the resolved paths before planning outputs.
+## 2024-09-02 - hmac.compare_digest DoS Vulnerability
+**Vulnerability:** `hmac.compare_digest` throws a `TypeError` when comparing strings with non-ASCII characters, which could lead to an unhandled exception and Denial of Service (DoS) when used with user-provided HTTP headers like API keys.
+**Learning:** Python's `hmac.compare_digest` does not support non-ASCII string comparisons.
+**Prevention:** Always encode strings to bytes (e.g., `.encode('utf-8')`) before passing them to `hmac.compare_digest`, especially when the input is user-controlled.

saas_web.py

@@ -113,8 +113,9 @@ async def require_api_key(request: Request, call_next):
     configured_keys = get_configured_api_keys()
     if configured_keys and not (request.method == "GET" and request.url.path == "/"):
         provided_key = request.headers.get("x-api-key", "")
+        provided_key_bytes = provided_key.encode("utf-8")
         if not any(
-            hmac.compare_digest(provided_key, key) for key in configured_keys
+            hmac.compare_digest(provided_key_bytes, key.encode("utf-8")) for key in configured_keys
         ):
             return JSONResponse(
                 status_code=401,

tests/test_saas_web.py

@@ -1225,3 +1225,28 @@ def test_video_content_type_accepted_by_validator(self):
 
 if __name__ == "__main__":
     unittest.main()
+
+
+@unittest.skipUnless(
+    _HAS_FASTAPI, "fastapi not installed (optional integration dependency)"
+)
+class TestApiKeyAuthAsync(unittest.IsolatedAsyncioTestCase):
+    async def test_non_ascii_key_rejected_safely(self):
+        from starlette.requests import Request
+        import saas_web
+        import json
+
+        async def mock_call_next(request):
+            return "SUCCESS"
+
+        with patch.dict(os.environ, {"CODEC_CARVER_API_KEYS": "secret-key"}):
+            scope = {
+                "type": "http",
+                "method": "POST",
+                "path": "/shrink",
+                "headers": [(b"x-api-key", "non-ascii-é".encode("utf-8"))],
+            }
+            request = Request(scope)
+            response = await saas_web.require_api_key(request, mock_call_next)
+            self.assertEqual(response.status_code, 401)
+            self.assertEqual(json.loads(response.body), {"error": "Invalid or missing API key"})