Test that `str.format` checks security for accessed attributes (#93)

* Test that `str.format` checks the security for attributes that are accessed.

Part of PloneHotfix20170117.

This needs https://github.com/zopefoundation/AccessControl/pull/23
This was merged, but not released yet, so we add AccessControl to auto-checkout for now.

* AccessControl has a release, no need for auto-checkout anymore.

doc/CHANGES.rst

@@ -8,6 +8,9 @@ http://docs.zope.org/zope2/
 2.13.26 (unreleased)
 --------------------
 
+- In ``str.format``, check the security for attributes that are accessed.
+  Part of PloneHotfix20170117.  [maurits]
+
 - Fixed reflective XSS in findResult.
   This applies PloneHotfix20170117.  [maurits]
 

src/Zope2/App/tests/normal_zope3_page_template.pt

+<p tal:content="python:('%s' % context).lower()" />
+<p tal:content="python:(u'%s' % context).upper()" />

src/Zope2/App/tests/test_formatter.py

+from Testing.ZopeTestCase import FunctionalTestCase
+from zExceptions import Unauthorized
+
+import unittest
+
+
+BAD_STR = """
+<p tal:content="python:'class of {0} is {0.__class__}'.format(context)" />
+"""
+BAD_UNICODE = """
+<p tal:content="python:u'class of {0} is {0.__class__}'.format(context)" />
+"""
+GOOD_STR = '<p tal:content="python:(\'%s\' % context).lower()" />'
+GOOD_UNICODE = '<p tal:content="python:(\'%s\' % context).lower()" />'
+
+
+def noop(context=None):
+    return lambda: context
+
+
+def hack_pt(pt, context=None):
+    # hacks to avoid getting error in pt_render.
+    pt.getPhysicalRoot = noop()
+    pt._getContext = noop(context)
+    pt._getContainer = noop(context)
+    pt.context = context
+
+
+class FormatterTest(unittest.TestCase):
+
+    def test_cook_zope2_page_templates_bad_str(self):
+        from Products.PageTemplates.ZopePageTemplate import ZopePageTemplate
+        pt = ZopePageTemplate('mytemplate', BAD_STR)
+        hack_pt(pt)
+        self.assertRaises(Unauthorized, pt.pt_render)
+
+    def test_cook_zope2_page_templates_bad_unicode(self):
+        from Products.PageTemplates.ZopePageTemplate import ZopePageTemplate
+        pt = ZopePageTemplate('mytemplate', BAD_UNICODE)
+        hack_pt(pt)
+        self.assertRaises(Unauthorized, pt.pt_render)
+
+    def test_cook_zope2_page_templates_good_str(self):
+        from Products.PageTemplates.ZopePageTemplate import ZopePageTemplate
+        pt = ZopePageTemplate('mytemplate', GOOD_STR)
+        hack_pt(pt)
+        self.assertEqual(pt.pt_render().strip(), '<p>none</p>')
+
+    def test_cook_zope2_page_templates_good_unicode(self):
+        from Products.PageTemplates.ZopePageTemplate import ZopePageTemplate
+        pt = ZopePageTemplate('mytemplate', unicode(GOOD_UNICODE))
+        hack_pt(pt)
+        self.assertEqual(pt.pt_render().strip(), '<p>none</p>')
+
+
+class FormatterFunctionalTest(FunctionalTestCase):
+
+    def test_access_to_private_content_not_allowed_via_any_attribute(self):
+        from Products.PageTemplates.ZopePageTemplate import ZopePageTemplate
+        # If access to _delObject would be allowed, it would still only say
+        # something like 'bound method _delObject', without actually deleting
+        # anything, because methods are not executed in str.format, but there
+        # may be @properties that give an attacker secret info.
+        pt = ZopePageTemplate('mytemplate', '''
+<p tal:content="structure python:'access {0._delObject}'.format(context)" />
+''')
+        hack_pt(pt, context=self.app)
+        self.assertRaises(Unauthorized, pt.pt_render)
+
+    # Zope 3 templates are always file system templates.  So we actually have
+    # no problems allowing str.format there.
+
+    def test_cook_zope3_page_templates_normal(self):
+        from Products.Five.browser.pagetemplatefile import ViewPageTemplateFile
+        pt = ViewPageTemplateFile('normal_zope3_page_template.pt')
+        hack_pt(pt)
+        # Need to pass a namespace.
+        namespace = {'context': self.app}
+        self.assertEqual(
+            pt.pt_render(namespace).strip(),
+            u'<p>&lt;application at &gt;</p>\n'
+            u'<p>&lt;APPLICATION AT &gt;</p>')
+
+    def test_cook_zope3_page_templates_using_format(self):
+        from Products.Five.browser.pagetemplatefile import ViewPageTemplateFile
+        pt = ViewPageTemplateFile('using_format_zope3_page_template.pt')
+        hack_pt(pt)
+        # Need to pass a namespace.
+        namespace = {'context': self.app}
+        self.assertEqual(
+            pt.pt_render(namespace).strip(),
+            u"<p>class of &lt;application at &gt; is "
+            u"&lt;class 'ofs.application.application'&gt;</p>\n"
+            u"<p>CLASS OF &lt;APPLICATION AT &gt; IS "
+            u"&lt;CLASS 'OFS.APPLICATION.APPLICATION'&gt;</p>")

src/Zope2/App/tests/using_format_zope3_page_template.pt

+<p tal:content="python:'class of {0} is {0.__class__}'.format(context).lower()" />
+<p tal:content="python:u'class of {0} is {0.__class__}'.format(context).upper()" />