[3.14] gh-151987: Pass filter_function to `TarFile._extract_one()` during `.extract...

(cherry picked from commit 7ccdbaba2c54250a70d7f25632152df7655a5e0a)

Co-authored-by: Petr Viktorin <encukou@gmail.com>
Co-authored-by: Seth Michael Larson <seth@python.org>

diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index cb09e307c469bdd30b5ff6963cba9a28948776ae..d3c489997006e7a9013cb9d63e9ce2898b3529b3 100644 (file)
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -2538,7 +2538,8 @@ class TarFile(object):
         tarinfo, unfiltered = self._get_extract_tarinfo(
             member, filter_function, path)
         if tarinfo is not None:
-            self._extract_one(tarinfo, path, set_attrs, numeric_owner)
+            self._extract_one(tarinfo, path, set_attrs, numeric_owner,
+                              filter_function=filter_function)
 
     def _get_extract_tarinfo(self, member, filter_function, path):
         """Get (filtered, unfiltered) TarInfos from *member*

diff --git a/Lib/test/test_tarfile.py b/Lib/test/test_tarfile.py
index 804c3e6d809487ad9969312322dcb40183f1e448..f3b61d9fbad6a619879c5c66bbaa3ba22f1de9c1 100644 (file)
--- a/Lib/test/test_tarfile.py
+++ b/Lib/test/test_tarfile.py
@@ -4470,6 +4470,98 @@ class TestExtractionFilters(unittest.TestCase):
                     st_mode = cc.outerdir.stat().st_mode
                     self.assertNotEqual(st_mode & 0o777, 0o777)
 
+    @symlink_test
+    @unittest.skipUnless(hasattr(os, 'chown'), "missing os.chown")
+    @unittest.skipUnless(hasattr(os, 'lchown'), "missing os.lchown")
+    @unittest.skipUnless(hasattr(os, 'geteuid'), "missing os.geteuid")
+    @support.subTests('link_type', (tarfile.SYMTYPE, tarfile.LNKTYPE))
+    def test_chown_links_on_extract(self, link_type):
+        with ArchiveMaker() as arc:
+            arc.add("test.txt",
+                    uid=1337, gid=1337, uname="", gname="", mode='-rwxr-xr-x')
+            arc.add("link",
+                    type=link_type,
+                    linkname='test.txt',
+                    uid=1337, gid=1337, uname="", gname="", mode='-rwxr-xr-x')
+
+        with (
+            os_helper.temp_dir() as tmpdir,
+            arc.open() as tar,
+            unittest.mock.patch("os.chown") as mock_chown,
+            unittest.mock.patch("os.lchown") as mock_lchown,
+            unittest.mock.patch("os.geteuid") as mock_geteuid,
+        ):
+            # Set UID to 0 so chown() is attempted.
+            mock_geteuid.return_value = 0
+            tar.extract("link", path=tmpdir, filter='data')
+            extract_path = os.path.join(tmpdir, "link")
+
+            if link_type == tarfile.SYMTYPE:
+                mock_chown.assert_not_called()
+                mock_lchown.assert_called_once_with(extract_path, -1, -1)
+            else:
+                mock_chown.assert_has_calls([
+                    unittest.mock.call(extract_path, -1, -1),
+                    unittest.mock.call(extract_path, -1, -1)
+                ])
+                mock_lchown.assert_not_called()
+
+    @symlink_test
+    @unittest.skipUnless(hasattr(os, 'chown'), "missing os.chown")
+    @unittest.skipUnless(hasattr(os, 'lchown'), "missing os.lchown")
+    @unittest.skipUnless(hasattr(os, 'geteuid'), "missing os.geteuid")
+    @support.subTests('link_type', (tarfile.SYMTYPE, tarfile.LNKTYPE))
+    def test_chown_links_on_extractall(self, link_type):
+        with ArchiveMaker() as arc:
+            arc.add("test.txt",
+                    uid=1337, gid=1337, uname="", gname="", mode='-rwxr-xr-x')
+            arc.add("link",
+                    type=link_type,
+                    linkname='test.txt',
+                    uid=1337, gid=1337, uname="", gname="", mode='-rwxr-xr-x')
+
+        with (
+            os_helper.temp_dir() as tmpdir,
+            arc.open() as tar,
+            unittest.mock.patch("os.chown") as mock_chown,
+            unittest.mock.patch("os.lchown") as mock_lchown,
+            unittest.mock.patch("os.geteuid") as mock_geteuid,
+        ):
+            # Set UID to 0 so chown() is attempted.
+            mock_geteuid.return_value = 0
+            tar.extractall(path=tmpdir, filter='data')
+            extract_link_path = os.path.join(tmpdir, "link")
+            extract_file_path = os.path.join(tmpdir, "test.txt")
+
+            if link_type == tarfile.SYMTYPE:
+                mock_chown.assert_called_once_with(extract_file_path, -1, -1)
+                mock_lchown.assert_called_once_with(extract_link_path, -1, -1)
+            else:
+                mock_chown.assert_has_calls([
+                    unittest.mock.call(extract_file_path, -1, -1),
+                    unittest.mock.call(extract_link_path, -1, -1)
+                ])
+                mock_lchown.assert_not_called()
+
+    def test_extract_filters_target(self):
+        # Test that when extract() falls back to extracting (rather than
+        # linking) a hardlink target, it filters the target.
+        with ArchiveMaker() as arc:
+            arc.add("target")
+            arc.add("link", hardlink_to="target")
+        def testing_filter(member, path):
+            if member.name == 'target':
+                # target: set read-only
+                return member.replace(mode=stat.S_IRUSR)
+            # link: don't overwrite the mode
+            return member.replace(mode=None)
+        tempdir = pathlib.Path(TEMPDIR) / 'extract'
+        with os_helper.temp_dir(tempdir), arc.open() as tar:
+            tar.extract("link", path=tempdir, filter=testing_filter)
+            path = tempdir / 'link'
+            if os_helper.can_chmod():
+                self.assertFalse(path.stat().st_mode & stat.S_IWUSR)
+
     def test_link_fallback_normalizes(self):
         # Make sure hardlink fallbacks work for non-normalized paths for all
         # filters

diff --git a/Misc/NEWS.d/next/Security/2026-06-23-14-19-30.gh-issue-151987.8mNIMf.rst b/Misc/NEWS.d/next/Security/2026-06-23-14-19-30.gh-issue-151987.8mNIMf.rst
new file mode 100644 (file)
index 0000000..9eea7b3
--- /dev/null
+++ b/Misc/NEWS.d/next/Security/2026-06-23-14-19-30.gh-issue-151987.8mNIMf.rst
@@ -0,0 +1,2 @@
+The :meth:`tarfile.TarFile.extract` method now applies the given filter when
+it extracts a link target from the archive as a fallback.