ENH harden Card by adding a flag to allow/disallow insecure pickle loading

docs/changes.rst

@@ -11,6 +11,9 @@ skops Changelog
 
 v0.13
 -----
+- `Card` now requires a new parameter, `allow_pickle`, to call `get_model` with
+  models that are not `.skops` files. This change is to mitigate security risks
+  associated with pickles. :pr:`485` by `Io_no`_.
 
 v0.12
 -----

skops/card/_model_card.py

@@ -227,7 +227,9 @@ def __repr__(self) -> str:
         return f"{self.__class__.__name__}({nrows}x{ncols})"
 
 
-def _load_model(model: Any, trusted=False) -> Any:
+def _load_model(
+    model: Any, trusted: Optional[Sequence[str]] = None, allow_pickle: bool = False
+) -> Any:
     """Return a model instance.
 
     Loads the model if provided a file path, if already a model instance return
@@ -238,10 +240,14 @@ def _load_model(model: Any, trusted=False) -> Any:
     model : pathlib.Path, str, or sklearn estimator
         Path/str or the actual model instance. if a Path or str, loads the model.
 
-    trusted : bool, default=False
+    trusted: list of str, default=None
         Passed to :func:`skops.io.load` if the model is a file path and it's
         a `skops` file.
 
+    allow_pickle : bool, default=False
+        If `True`, allows loading models using `joblib.load`. This may lead to
+        security issues if the model file is not trustworthy.
+
     Returns
     -------
     model : object
@@ -255,13 +261,28 @@ def _load_model(model: Any, trusted=False) -> Any:
     if not model_path.exists():
         raise FileNotFoundError(f"File is not present: {model_path}")
 
+    if trusted and allow_pickle:
+        raise ValueError(
+            "`allow_pickle` cannot be `True` if `trusted` is not empty. "
+            "Pickles cannot be trusted or checked for security issues."
+        )
+
+    msg = ""
     try:
         if zipfile.is_zipfile(model_path):
             model = load(model_path, trusted=trusted)
-        else:
+        elif allow_pickle:
             model = joblib.load(model_path)
+        else:
+            msg = (
+                "Model file is not a skops file, and allow_pickle is set to False. "
+                "Please set allow_pickle=True to load the model."
+                "This may lead to security issues if the model file is not trustworthy."
+            )
+            raise RuntimeError(msg)
     except Exception as ex:
-        msg = f'An "{type(ex).__name__}" occurred during model loading.'
+        if not msg:
+            msg = f'"{type(ex).__name__}" occurred during model loading.'
         raise RuntimeError(msg) from ex
 
     return model
@@ -310,10 +331,14 @@ class Card:
         not work, e.g. :meth:`Card.add_metrics`, since it's not clear where to
         put the metrics when there is no template or a custom template.
 
-    trusted: bool, default=False
+    trusted: list of str, default=None
         Passed to :func:`skops.io.load` if the model is a file path and it's
         a `skops` file.
 
+    allow_pickle: bool, default=False
+        If `True`, allows loading models using `joblib.load`. This may lead to
+        security issues if the model file is not trustworthy.
+
     Attributes
     ----------
     model: estimator object
@@ -379,11 +404,13 @@ def __init__(
         model_diagram: bool | Literal["auto"] | str = "auto",
         template: Literal["skops"] | dict[str, str] | None = "skops",
         trusted: Optional[List[str]] = None,
+        allow_pickle: bool = False,
     ) -> None:
         self.model = model
         self.model_format = model_format
         self.template = template
         self.trusted = trusted
+        self.allow_pickle = allow_pickle
 
         self._data: dict[str, Section] = {}
         self._metrics: dict[str, str | float | int] = {}
@@ -465,7 +492,7 @@ def get_model(self) -> Any:
 
     @cached_property
     def _model(self):
-        model = _load_model(self.model, self.trusted)
+        model = _load_model(self.model, self.trusted, self.allow_pickle)
         return model
 
     def add(self, folded: bool = False, **kwargs: str) -> Self:

skops/card/tests/test_card.py

@@ -82,18 +82,49 @@ def test_load_model(suffix):
     _, save_file = save_model_to_file(model0, suffix)
     if suffix == ".skops":
         untrusted_types = get_untrusted_types(file=save_file)
+        allow_pickle = False
     else:
         untrusted_types = None
-    loaded_model_str = _load_model(save_file, trusted=untrusted_types)
+        allow_pickle = True
+    loaded_model_str = _load_model(
+        save_file, trusted=untrusted_types, allow_pickle=allow_pickle
+    )
     save_file_path = Path(save_file)
-    loaded_model_path = _load_model(save_file_path, trusted=untrusted_types)
+    loaded_model_path = _load_model(
+        save_file_path, trusted=untrusted_types, allow_pickle=allow_pickle
+    )
     loaded_model_instance = _load_model(model0, trusted=untrusted_types)
 
     assert loaded_model_str.param_1 == 10
     assert loaded_model_path.param_1 == 10
     assert loaded_model_instance.param_1 == 10
 
 
+@pytest.mark.parametrize("suffix", [".pkl", ".pickle"])
+def test_load_model_exception_allow_pickle(suffix):
+    model0 = MyRegressor(param_1=10)
+    _, save_file = save_model_to_file(model0, suffix)
+
+    with pytest.raises(
+        RuntimeError,
+        match=(
+            "Model file is not a skops file, and allow_pickle is set to False. "
+            "Please set allow_pickle=True to load the model."
+            "This may lead to security issues if the model file is not trustworthy."
+        ),
+    ):
+        _load_model(save_file, trusted=None, allow_pickle=False)
+
+    with pytest.raises(
+        ValueError,
+        match=(
+            "`allow_pickle` cannot be `True` if `trusted` is not empty. "
+            "Pickles cannot be trusted or checked for security issues."
+        ),
+    ):
+        _load_model(save_file, trusted=[""], allow_pickle=True)
+
+
 @pytest.fixture
 def model_card(model_diagram=True):
     model = fit_model()
@@ -166,7 +197,9 @@ def test_model_caching(skops_model_card, iris_skops_file, destination_path):
 
     new_model = MyClassifier(param_1=10)
     # mock _load_model, it still loads the model but we can track call count
-    mock_load_model = mock.Mock(side_effect=load)
+    mock_load_model = mock.Mock(
+        side_effect=lambda path, trusted, _: load(path, trusted=trusted)
+    )
     card = Card(iris_skops_file, trusted=[MyClassifier])
     with mock.patch("skops.card._model_card._load_model", mock_load_model):
         model1 = card.get_model()
@@ -1133,7 +1166,7 @@ def path_to_card(self, path, suffix):
         if suffix == ".skops":
             card = Card(model=path, trusted=get_untrusted_types(file=path))
         else:
-            card = Card(model=path)
+            card = Card(model=path, allow_pickle=True)
         return card
 
     @pytest.mark.parametrize("meth", [repr, str])
@@ -1178,7 +1211,7 @@ def test_load_model_exception(self, meth, suffix):
         os.close(file_handle)
 
         with pytest.raises(Exception, match="occurred during model loading."):
-            card = Card(file_name)
+            card = Card(file_name, allow_pickle=True)
             meth(card)
 
     @pytest.mark.parametrize("meth", [repr, str])