Deny access to dict.__init__() to protect __builtins__

And set version to 1.0.3

ChangeLog

@@ -1,3 +1,7 @@
+Version 1.0.3 (2010-09-16)
+
+    * SECURITY FIX: Deny access to dict.__init__() to protect __builtins__.
+
 Version 1.0.2 (2010-09-15)
 
     * SECURITY FIX: Deny access to all dict methods able to modify a dict, not

sandbox/attributes.py

@@ -30,7 +30,7 @@ def enable(self, sandbox):
         # Blacklist all dict methods able to modify a dict, to protect
         # ReadOnlyBuiltins
         for name in (
-        'clear', '__delitem__', 'pop', 'popitem',
+        '__init__', 'clear', '__delitem__', 'pop', 'popitem',
         'setdefault', '__setitem__', 'update'):
             del self.dict_dict[name]
         if version_info < (3, 0):

sandbox/blacklist_proxy.py

@@ -8,34 +8,41 @@
 
 from .proxy import proxy, readOnlyError
 
-# If you update this class, update also HideAttributes.enable()
-class ReadOnlyBuiltins(dict):
-    """
-    Type used for a read only version of the __builtins__ dictionary.
+def createReadOnlyBuiltins(builtins):
+    # If you update this class, update also HideAttributes.enable()
+    class ReadOnlyBuiltins(dict):
+        """
+        Type used for a read only version of the __builtins__ dictionary.
 
-    Don't proxy __getattr__ because we suppose that __builtins__ only contains
-    safe functions (not mutable objects).
-    """
-    __slots__ = tuple()
+        Don't proxy __getattr__ because we suppose that __builtins__ only contains
+        safe functions (not mutable objects).
+        """
+        __slots__ = tuple()
 
-    def clear(self):
-        readOnlyError()
+        def clear(self):
+            readOnlyError()
 
-    def __delitem__(self, key):
-        readOnlyError()
+        def __delitem__(self, key):
+            readOnlyError()
 
-    def pop(self, key, default=None):
-        readOnlyError()
+        def pop(self, key, default=None):
+            readOnlyError()
 
-    def popitem(self):
-        readOnlyError()
+        def popitem(self):
+            readOnlyError()
 
-    def setdefault(self, key, value):
-        readOnlyError()
+        def setdefault(self, key, value):
+            readOnlyError()
 
-    def __setitem__(self, key, value):
-        readOnlyError()
+        def __setitem__(self, key, value):
+            readOnlyError()
+
+        def update(self, dict, **kw):
+            readOnlyError()
 
-    def update(self, dict, **kw):
+    safe = ReadOnlyBuiltins(builtins)
+    def __init__(*args, **kw):
         readOnlyError()
+    ReadOnlyBuiltins.__init__ = __init__
+    return safe
 

sandbox/builtins.py

@@ -9,7 +9,7 @@
 from .safe_import import _safe_import
 from .restorable_dict import RestorableDict
 from .proxy import createReadOnlyObject
-from .blacklist_proxy import ReadOnlyBuiltins
+from .blacklist_proxy import createReadOnlyBuiltins
 if USE_CSANDBOX:
     from _sandbox import set_frame_builtins, set_interp_builtins
 
@@ -74,7 +74,7 @@ def safe_exit(code=0):
                 del self.builtin_dict['help']
 
         # Make builtins read only (enable restricted mode)
-        safe_builtins = ReadOnlyBuiltins(self.builtin_dict.dict)
+        safe_builtins = createReadOnlyBuiltins(self.builtin_dict.dict)
         if USE_CSANDBOX:
             set_frame_builtins(self.frame, safe_builtins)
             if not config.cpython_restricted:

sandbox/version.py

@@ -1,4 +1,4 @@
 PACKAGE = "pysandbox"
-VERSION = "1.0.2"
+VERSION = "1.0.3"
 LICENSE = "BSD"
 URL = "http://github.com/haypo/pysandbox/"

tests.py

@@ -55,13 +55,11 @@ def access_denied():
         read_first_line(open)
 
     def test_exec_builtins():
-        from sandbox.builtins import ReadOnlyBuiltins
-
         def check_builtins_type():
             result = []
             exec "result.append(type(__builtins__))" in {'result': result}
             builtin_type = result[0]
-            assert builtin_type == ReadOnlyBuiltins
+            assert builtin_type != dict
         createSandbox().call(check_builtins_type)
 else:
     print "USE_CSANDBOX=False: disable test_open_whitelist(), test_exec_builtins()"
@@ -605,7 +603,7 @@ def test(*lines, **kw):
         globals=namespace)
     assert set(namespace.keys()) == set(('a', 'x', '__builtins__'))
     assert namespace['a'] == 10
-    assert namespace['x'] == 42 
+    assert namespace['x'] == 42
 
     namespace = {'b': 2}
     test(
@@ -626,12 +624,12 @@ def test(*lines, **kw):
         "x=42",
         "a=10",
         "b=20",
-        globals=my_globals, 
+        globals=my_globals,
         locals=namespace)
     assert set(my_globals.keys()) == set(('a', '__builtins__'))
     assert my_globals['a'] == 1
     assert namespace == {'a': 10, 'b': 20, 'x': 42}
-    
+
     namespace = {}
     test('a=1', locals=namespace)
     assert namespace == {'a': 1}, namespace