Patch CSRF-protection system to deal with reported security issue. Announcement and details to follow.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@13698 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/middleware/csrf.py

@@ -13,6 +13,7 @@ from django.conf import settings
 from django.core.urlresolvers import get_callable
 from django.utils.cache import patch_vary_headers
 from django.utils.hashcompat import md5_constructor
+from django.utils.html import escape
 from django.utils.safestring import mark_safe
 
 _POST_FORM_RE = \
@@ -52,7 +53,8 @@ def _make_legacy_session_token(session_id):
 
 def get_token(request):
     """
-    Returns the the CSRF token required for a POST form.
+    Returns the the CSRF token required for a POST form. No assumptions should
+    be made about what characters might be in the CSRF token.
 
     A side effect of calling this function is to make the the csrf_protect
     decorator and the CsrfViewMiddleware add a CSRF cookie and a 'Vary: Cookie'
@@ -247,7 +249,7 @@ class CsrfResponseMiddleware(object):
                 """Returns the matched <form> tag plus the added <input> element"""
                 return mark_safe(match.group() + "<div style='display:none;'>" + \
                 "<input type='hidden' " + idattributes.next() + \
-                " name='csrfmiddlewaretoken' value='" + csrf_token + \
+                " name='csrfmiddlewaretoken' value='" + escape(csrf_token) + \
                 "' /></div>")
 
             # Modify any POST forms

django/template/defaulttags.py

@@ -9,6 +9,7 @@ from django.template import TemplateSyntaxError, VariableDoesNotExist, BLOCK_TAG
 from django.template import get_library, Library, InvalidTemplateLibrary
 from django.template.smartif import IfParser, Literal
 from django.conf import settings
+from django.utils.html import escape
 from django.utils.encoding import smart_str, smart_unicode
 from django.utils.safestring import mark_safe
 
@@ -42,7 +43,7 @@ class CsrfTokenNode(Node):
             if csrf_token == 'NOTPROVIDED':
                 return mark_safe(u"")
             else:
-                return mark_safe(u"<div style='display:none'><input type='hidden' name='csrfmiddlewaretoken' value='%s' /></div>" % (csrf_token))
+                return mark_safe(u"<div style='display:none'><input type='hidden' name='csrfmiddlewaretoken' value='%s' /></div>" % escape(csrf_token))
         else:
             # It's very probable that the token is missing because of
             # misconfiguration, so we raise a warning

tests/regressiontests/csrf_tests/tests.py

@@ -6,6 +6,7 @@ from django.middleware.csrf import CsrfMiddleware, CsrfViewMiddleware
 from django.views.decorators.csrf import csrf_exempt, csrf_view_exempt
 from django.core.context_processors import csrf
 from django.contrib.sessions.middleware import SessionMiddleware
+from django.utils.html import escape
 from django.utils.importlib import import_module
 from django.conf import settings
 from django.template import RequestContext, Template
@@ -56,7 +57,9 @@ class TestingHttpRequest(HttpRequest):
         return getattr(self, '_is_secure', False)
 
 class CsrfMiddlewareTest(TestCase):
-    _csrf_id = "1"
+    # The csrf token is potentially from an untrusted source, so could have
+    # characters that need escaping
+    _csrf_id = "<1>"
 
     # This is a valid session token for this ID and secret key.  This was generated using
     # the old code that we're to be backwards-compatible with.  Don't use the CSRF code
@@ -101,7 +104,7 @@ class CsrfMiddlewareTest(TestCase):
         return req
 
     def _check_token_present(self, response, csrf_id=None):
-        self.assertContains(response, "name='csrfmiddlewaretoken' value='%s'" % (csrf_id or self._csrf_id))
+        self.assertContains(response, "name='csrfmiddlewaretoken' value='%s'" % escape(csrf_id or self._csrf_id))
 
     # Check the post processing and outgoing cookie
     def test_process_response_no_csrf_cookie(self):