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[1.2.X] Fixed #14235 - UnicodeDecodeError in CSRF middleware

  
Thanks to jbg for the report.
  
This changeset essentially backs out [13698] in favour of a method that
sanitizes the token rather than escaping it.

Backport of [13732] from trunk.




git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@13733 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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commit 890b0b6234f3ae742a9cb97f27fe0bb7d900b93b 1 parent 43988e9
Luke Plant spookylukey authored
23 django/middleware/csrf.py
View
@@ -13,7 +13,6 @@
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 = \
@@ -53,8 +52,8 @@ def _make_legacy_session_token(session_id):
def get_token(request):
"""
- Returns the the CSRF token required for a POST form. No assumptions should
- be made about what characters might be in the CSRF token.
+ Returns the the CSRF token required for a POST form. The token is an
+ alphanumeric value.
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'
@@ -65,6 +64,17 @@ def get_token(request):
return request.META.get("CSRF_COOKIE", None)
+def _sanitize_token(token):
+ # Allow only alphanum, and ensure we return a 'str' for the sake of the post
+ # processing middleware.
+ token = re.sub('[^a-zA-Z0-9]', '', str(token.decode('ascii', 'ignore')))
+ if token == "":
+ # In case the cookie has been truncated to nothing at some point.
+ return _get_new_csrf_key()
+ else:
+ return token
+
+
class CsrfViewMiddleware(object):
"""
Middleware that requires a present and correct csrfmiddlewaretoken
@@ -90,7 +100,10 @@ def accept():
# request, so it's available to the view. We'll store it in a cookie when
# we reach the response.
try:
- request.META["CSRF_COOKIE"] = request.COOKIES[settings.CSRF_COOKIE_NAME]
+ # In case of cookies from untrusted sources, we strip anything
+ # dangerous at this point, so that the cookie + token will have the
+ # same, sanitized value.
+ request.META["CSRF_COOKIE"] = _sanitize_token(request.COOKIES[settings.CSRF_COOKIE_NAME])
cookie_is_new = False
except KeyError:
# No cookie, so create one. This will be sent with the next
@@ -235,7 +248,7 @@ def add_csrf_field(match):
"""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='" + escape(csrf_token) + \
+ " name='csrfmiddlewaretoken' value='" + csrf_token + \
"' /></div>")
# Modify any POST forms
3  django/template/defaulttags.py
View
@@ -9,7 +9,6 @@
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
@@ -43,7 +42,7 @@ def render(self, context):
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>" % escape(csrf_token))
+ return mark_safe(u"<div style='display:none'><input type='hidden' name='csrfmiddlewaretoken' value='%s' /></div>" % csrf_token)
else:
# It's very probable that the token is missing because of
# misconfiguration, so we raise a warning
25 tests/regressiontests/csrf_tests/tests.py
View
@@ -6,15 +6,14 @@
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
# Response/views used for CsrfResponseMiddleware and CsrfViewMiddleware tests
def post_form_response():
- resp = HttpResponse(content="""
-<html><body><form method="post"><input type="text" /></form></body></html>
+ resp = HttpResponse(content=u"""
+<html><body><h1>\u00a1Unicode!<form method="post"><input type="text" /></form></body></html>
""", mimetype="text/html")
return resp
@@ -58,8 +57,9 @@ def is_secure(self):
class CsrfMiddlewareTest(TestCase):
# The csrf token is potentially from an untrusted source, so could have
- # characters that need escaping
- _csrf_id = "<1>"
+ # characters that need dealing with.
+ _csrf_id_cookie = "<1>\xc2\xa1"
+ _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
@@ -74,7 +74,7 @@ def _get_GET_no_csrf_cookie_request(self):
def _get_GET_csrf_cookie_request(self):
req = TestingHttpRequest()
- req.COOKIES[settings.CSRF_COOKIE_NAME] = self._csrf_id
+ req.COOKIES[settings.CSRF_COOKIE_NAME] = self._csrf_id_cookie
return req
def _get_POST_csrf_cookie_request(self):
@@ -104,7 +104,7 @@ def _get_POST_session_request_no_token(self):
return req
def _check_token_present(self, response, csrf_id=None):
- self.assertContains(response, "name='csrfmiddlewaretoken' value='%s'" % escape(csrf_id or self._csrf_id))
+ self.assertContains(response, "name='csrfmiddlewaretoken' value='%s'" % (csrf_id or self._csrf_id))
# Check the post processing and outgoing cookie
def test_process_response_no_csrf_cookie(self):
@@ -290,6 +290,17 @@ def test_token_node_no_csrf_cookie(self):
resp = token_view(req)
self.assertEquals(u"", resp.content)
+ def test_token_node_empty_csrf_cookie(self):
+ """
+ Check that we get a new token if the csrf_cookie is the empty string
+ """
+ req = self._get_GET_no_csrf_cookie_request()
+ req.COOKIES[settings.CSRF_COOKIE_NAME] = ""
+ CsrfViewMiddleware().process_view(req, token_view, (), {})
+ resp = token_view(req)
+
+ self.assertNotEqual(u"", resp.content)
+
def test_token_node_with_csrf_cookie(self):
"""
Check that CsrfTokenNode works when a CSRF cookie is set
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