gh-121999: Change default tarfile filter to 'data'

Author: WilliamRoyNelson

Doc/library/tarfile.rst

@@ -40,9 +40,11 @@ Some facts and figures:
    Archives are extracted using a :ref:`filter <tarfile-extraction-filter>`,
    which makes it possible to either limit surprising/dangerous features,
    or to acknowledge that they are expected and the archive is fully trusted.
-   By default, archives are fully trusted, but this default is deprecated
-   and slated to change in Python 3.14.
 
+.. versionchanged:: 3.14
+   The default extraction filter was 'fully trusted' but is now 'data' which
+   which disallows dangerous features like links to absolute paths or paths
+   outside the destination.
 
 .. function:: open(name=None, mode='r', fileobj=None, bufsize=10240, **kwargs)
 
@@ -495,19 +497,23 @@ be finalized; only the internally used file object will be closed. See the
    The *filter* argument specifies how ``members`` are modified or rejected
    before extraction.
    See :ref:`tarfile-extraction-filter` for details.
-   It is recommended to set this explicitly depending on which *tar* features
-   you need to support.
+   It is recommended to set this explicitly only if unusual *tar* features
+   are required.
 
    .. warning::
 
-      Never extract archives from untrusted sources without prior inspection.
+      The default filter is set to ``filter='data'`` to prevent the most
+      dangerous security issues, read the :ref:`tarfile-extraction-filter`
+      section for details.
+
+      Never extract archives from untrusted sources without prior inspection,
+      even when using the `data` filter, but especially if using the `tar` or
+      `fully_trusted` filters.
+
       It is possible that files are created outside of *path*, e.g. members
       that have absolute filenames starting with ``"/"`` or filenames with two
       dots ``".."``.
 
-      Set ``filter='data'`` to prevent the most dangerous security issues,
-      and read the :ref:`tarfile-extraction-filter` section for details.
-
    .. versionchanged:: 3.5
       Added the *numeric_owner* parameter.
 
@@ -538,8 +544,9 @@ be finalized; only the internally used file object will be closed. See the
 
       See the warning for :meth:`extractall`.
 
-      Set ``filter='data'`` to prevent the most dangerous security issues,
-      and read the :ref:`tarfile-extraction-filter` section for details.
+      The default filter is set to ``filter='data'`` to prevent the most
+      dangerous security issues, read the :ref:`tarfile-extraction-filter`
+      section for details.
 
    .. versionchanged:: 3.2
       Added the *set_attrs* parameter.
@@ -603,12 +610,7 @@ be finalized; only the internally used file object will be closed. See the
    argument to :meth:`~TarFile.extract`.
 
    If ``extraction_filter`` is ``None`` (the default),
-   calling an extraction method without a *filter* argument will raise a
-   ``DeprecationWarning``,
-   and fall back to the :func:`fully_trusted <fully_trusted_filter>` filter,
-   whose dangerous behavior matches previous versions of Python.
-
-   In Python 3.14+, leaving ``extraction_filter=None`` will cause
+   calling an extraction method without a *filter* argument will cause
    extraction methods to use the :func:`data <data_filter>` filter by default.
 
    The attribute may be set on instances or overridden in subclasses.
@@ -992,12 +994,7 @@ can be:
 
 * ``None`` (default): Use :attr:`TarFile.extraction_filter`.
 
-  If that is also ``None`` (the default), raise a ``DeprecationWarning``,
-  and fall back to the ``'fully_trusted'`` filter, whose dangerous behavior
-  matches previous versions of Python.
-
-  In Python 3.14, the ``'data'`` filter will become the default instead.
-  It's possible to switch earlier; see :attr:`TarFile.extraction_filter`.
+  If that is also ``None`` (the default), the ``'data'`` filter will be used.
 
 * A callable which will be called for each extracted member with a
   :ref:`TarInfo <tarinfo-objects>` describing the member and the destination

Lib/tarfile.py

@@ -2248,13 +2248,7 @@ def _get_filter_function(self, filter):
         if filter is None:
             filter = self.extraction_filter
             if filter is None:
-                import warnings
-                warnings.warn(
-                    'Python 3.14 will, by default, filter extracted tar '
-                    + 'archives and reject files or modify their metadata. '
-                    + 'Use the filter argument to control this behavior.',
-                    DeprecationWarning, stacklevel=3)
-                return fully_trusted_filter
+                return data_filter
             if isinstance(filter, str):
                 raise TypeError(
                     'String names are not supported for '

Lib/test/test_tarfile.py

@@ -738,31 +738,6 @@ def test_extract_directory(self):
         finally:
             os_helper.rmtree(DIR)
 
-    def test_deprecation_if_no_filter_passed_to_extractall(self):
-        DIR = pathlib.Path(TEMPDIR) / "extractall"
-        with (
-            os_helper.temp_dir(DIR),
-            tarfile.open(tarname, encoding="iso8859-1") as tar
-        ):
-            directories = [t for t in tar if t.isdir()]
-            with self.assertWarnsRegex(DeprecationWarning, "Use the filter argument") as cm:
-                tar.extractall(DIR, directories)
-            # check that the stacklevel of the deprecation warning is correct:
-            self.assertEqual(cm.filename, __file__)
-
-    def test_deprecation_if_no_filter_passed_to_extract(self):
-        dirtype = "ustar/dirtype"
-        DIR = pathlib.Path(TEMPDIR) / "extractall"
-        with (
-            os_helper.temp_dir(DIR),
-            tarfile.open(tarname, encoding="iso8859-1") as tar
-        ):
-            tarinfo = tar.getmember(dirtype)
-            with self.assertWarnsRegex(DeprecationWarning, "Use the filter argument") as cm:
-                tar.extract(tarinfo, path=DIR)
-            # check that the stacklevel of the deprecation warning is correct:
-            self.assertEqual(cm.filename, __file__)
-
     def test_extractall_pathlike_dir(self):
         DIR = os.path.join(TEMPDIR, "extractall")
         with os_helper.temp_dir(DIR), \
@@ -4011,15 +3986,6 @@ def test_data_filter(self):
                 self.assertIs(filtered.name, tarinfo.name)
                 self.assertIs(filtered.type, tarinfo.type)
 
-    def test_default_filter_warns(self):
-        """Ensure the default filter warns"""
-        with ArchiveMaker() as arc:
-            arc.add('foo')
-        with warnings_helper.check_warnings(
-                ('Python 3.14', DeprecationWarning)):
-            with self.check_context(arc.open(), None):
-                self.expect_file('foo')
-
     def test_change_default_filter_on_instance(self):
         tar = tarfile.TarFile(tarname, 'r')
         def strict_filter(tarinfo, path):

Misc/NEWS.d/next/Core_and_Builtins/2024-07-18-21-19-04.gh-issue-121999.8IBbTK.rst

@@ -0,0 +1 @@
+Update tarfile library to use 'data' filter by default when extracting