filter data is safe for tarfile extractall (#1111)

* filter data is safe for tarfile extractall

* add versionchanged to the docstring

bandit/plugins/tarfile_unsafe_members.py

@@ -42,6 +42,9 @@
 
 .. versionadded:: 1.7.5
 
+.. versionchanged:: 1.7.8
+    Added check for filter parameter
+
 """
 import ast
 
@@ -91,6 +94,13 @@ def get_members_value(context):
                 return {"Other": value}
 
 
+def is_filter_data(context):
+    for keyword in context.node.keywords:
+        if keyword.arg == "filter":
+            arg = keyword.value
+            return isinstance(arg, ast.Str) and arg.s == "data"
+
+
 @test.test_id("B202")
 @test.checks("Call")
 def tarfile_unsafe_members(context):
@@ -100,6 +110,8 @@ def tarfile_unsafe_members(context):
             "extractall" in context.call_function_name,
         ]
     ):
+        if "filter" in context.call_keywords and is_filter_data(context):
+            return None
         if "members" in context.call_keywords:
             members = get_members_value(context)
             if "Function" in members:

examples/tarfile_extractall.py

@@ -15,6 +15,18 @@ def managed_members_archive_handler(filename):
     tar.close()
 
 
+def filter_data_archive_handler(filename):
+    tar = tarfile.open(filename)
+    tar.extractall(path=tempfile.mkdtemp(), filter="data")
+    tar.close()
+
+
+def filter_fully_trusted_archive_handler(filename):
+    tar = tarfile.open(filename)
+    tar.extractall(path=tempfile.mkdtemp(), filter="fully_trusted")
+    tar.close()
+
+
 def list_members_archive_handler(filename):
     tar = tarfile.open(filename)
     tar.extractall(path=tempfile.mkdtemp(), members=[])
@@ -45,3 +57,5 @@ def members_filter(tarfile):
         filename = sys.argv[1]
         unsafe_archive_handler(filename)
         managed_members_archive_handler(filename)
+        filter_data_archive_handler(filename)
+        filter_fully_trusted_archive_handler(filename)

tests/functional/test_functional.py

@@ -926,7 +926,7 @@ def test_snmp_security_check(self):
     def test_tarfile_unsafe_members(self):
         """Test insecure usage of tarfile."""
         expect = {
-            "SEVERITY": {"UNDEFINED": 0, "LOW": 1, "MEDIUM": 2, "HIGH": 1},
-            "CONFIDENCE": {"UNDEFINED": 0, "LOW": 1, "MEDIUM": 2, "HIGH": 1},
+            "SEVERITY": {"UNDEFINED": 0, "LOW": 1, "MEDIUM": 2, "HIGH": 2},
+            "CONFIDENCE": {"UNDEFINED": 0, "LOW": 1, "MEDIUM": 2, "HIGH": 2},
         }
         self.check_example("tarfile_extractall.py", expect)