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Fixed #32596 -- Added CsrfViewMiddleware._check_referer(). 

This encapsulates CsrfViewMiddleware's referer logic into a method and
updates existing tests to check the "seam" introduced by the refactor,
when doing so would improve the test.
This commit is contained in:
Chris Jerdonek 2021-03-26 02:37:55 -07:00 committed by Mariusz Felisiak
parent e93eb3d971
commit 71179a6124
2 changed files with 77 additions and 44 deletions
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95
django/middleware/csrf.py
View File

@ -132,6 +132,11 @@ def _compare_masked_tokens(request_csrf_token, csrf_token):
)
class RejectRequest(Exception):
def __init__(self, reason):
self.reason = reason
class CsrfViewMiddleware(MiddlewareMixin):
"""
Require a present and correct csrfmiddlewaretoken for POST requests that
@ -251,6 +256,50 @@ class CsrfViewMiddleware(MiddlewareMixin):
for host in self.allowed_origin_subdomains.get(request_scheme, ())
)
def _check_referer(self, request):
referer = request.META.get('HTTP_REFERER')
if referer is None:
raise RejectRequest(REASON_NO_REFERER)
try:
referer = urlparse(referer)
except ValueError:
raise RejectRequest(REASON_MALFORMED_REFERER)
# Make sure we have a valid URL for Referer.
if '' in (referer.scheme, referer.netloc):
raise RejectRequest(REASON_MALFORMED_REFERER)
# Ensure that our Referer is also secure.
if referer.scheme != 'https':
raise RejectRequest(REASON_INSECURE_REFERER)
good_referer = (
settings.SESSION_COOKIE_DOMAIN
if settings.CSRF_USE_SESSIONS
else settings.CSRF_COOKIE_DOMAIN
)
if good_referer is None:
# If no cookie domain is configured, allow matching the current
# host:port exactly if it's permitted by ALLOWED_HOSTS.
try:
# request.get_host() includes the port.
good_referer = request.get_host()
except DisallowedHost:
pass
else:
server_port = request.get_port()
if server_port not in ('443', '80'):
good_referer = '%s:%s' % (good_referer, server_port)
# Create an iterable of all acceptable HTTP referers.
good_hosts = self.csrf_trusted_origins_hosts
if good_referer is not None:
good_hosts = (*good_hosts, good_referer)
if not any(is_same_domain(referer.netloc, host) for host in good_hosts):
raise RejectRequest(REASON_BAD_REFERER % referer.geturl())
def process_request(self, request):
csrf_token = self._get_token(request)
if csrf_token is not None:
@ -300,50 +349,10 @@ class CsrfViewMiddleware(MiddlewareMixin):
# Barth et al. found that the Referer header is missing for
# same-domain requests in only about 0.2% of cases or less, so
# we can use strict Referer checking.
referer = request.META.get('HTTP_REFERER')
if referer is None:
return self._reject(request, REASON_NO_REFERER)
try:
referer = urlparse(referer)
except ValueError:
return self._reject(request, REASON_MALFORMED_REFERER)
# Make sure we have a valid URL for Referer.
if '' in (referer.scheme, referer.netloc):
return self._reject(request, REASON_MALFORMED_REFERER)
# Ensure that our Referer is also secure.
if referer.scheme != 'https':
return self._reject(request, REASON_INSECURE_REFERER)
good_referer = (
settings.SESSION_COOKIE_DOMAIN
if settings.CSRF_USE_SESSIONS
else settings.CSRF_COOKIE_DOMAIN
)
if good_referer is None:
# If no cookie domain is configured, allow matching the
# current host:port exactly if it's permitted by
# ALLOWED_HOSTS.
try:
# request.get_host() includes the port.
good_referer = request.get_host()
except DisallowedHost:
pass
else:
server_port = request.get_port()
if server_port not in ('443', '80'):
good_referer = '%s:%s' % (good_referer, server_port)
# Create an iterable of all acceptable HTTP referers.
good_hosts = self.csrf_trusted_origins_hosts
if good_referer is not None:
good_hosts = (*good_hosts, good_referer)
if not any(is_same_domain(referer.netloc, host) for host in good_hosts):
reason = REASON_BAD_REFERER % referer.geturl()
return self._reject(request, reason)
self._check_referer(request)
except RejectRequest as exc:
return self._reject(request, exc.reason)
# Access csrf_token via self._get_token() as rotate_token() may
# have been called by an authentication middleware during the

26
tests/csrf_tests/tests.py
View File

@ -6,7 +6,7 @@ from django.core.exceptions import ImproperlyConfigured
from django.http import HttpRequest, HttpResponse
from django.middleware.csrf import (
CSRF_SESSION_KEY, CSRF_TOKEN_LENGTH, REASON_BAD_ORIGIN, REASON_BAD_TOKEN,
REASON_NO_CSRF_COOKIE, CsrfViewMiddleware,
REASON_NO_CSRF_COOKIE, CsrfViewMiddleware, RejectRequest,
_compare_masked_tokens as equivalent_tokens, get_token,
)
from django.test import SimpleTestCase, override_settings
@ -305,12 +305,17 @@ class CsrfViewMiddlewareTestMixin:
status_code=403,
)
def _check_referer_rejects(self, mw, req):
with self.assertRaises(RejectRequest):
mw._check_referer(req)
@override_settings(DEBUG=True)
def test_https_no_referer(self):
"""A POST HTTPS request with a missing referer is rejected."""
req = self._get_POST_request_with_token()
req._is_secure_override = True
mw = CsrfViewMiddleware(post_form_view)
self._check_referer_rejects(mw, req)
response = mw.process_view(req, post_form_view, (), {})
self.assertContains(
response,
@ -329,6 +334,12 @@ class CsrfViewMiddlewareTestMixin:
req.META['HTTP_REFERER'] = 'https://www.evil.org/somepage'
req.META['SERVER_PORT'] = '443'
mw = CsrfViewMiddleware(token_view)
expected = (
'Referer checking failed - https://www.evil.org/somepage does not '
'match any trusted origins.'
)
with self.assertRaisesMessage(RejectRequest, expected):
mw._check_referer(req)
response = mw.process_view(req, token_view, (), {})
self.assertEqual(response.status_code, 403)
@ -338,6 +349,7 @@ class CsrfViewMiddlewareTestMixin:
req.META['HTTP_HOST'] = '@malformed'
req.META['HTTP_ORIGIN'] = 'https://www.evil.org'
mw = CsrfViewMiddleware(token_view)
self._check_referer_rejects(mw, req)
response = mw.process_view(req, token_view, (), {})
self.assertEqual(response.status_code, 403)
@ -351,6 +363,7 @@ class CsrfViewMiddlewareTestMixin:
req._is_secure_override = True
req.META['HTTP_REFERER'] = 'http://http://www.example.com/'
mw = CsrfViewMiddleware(post_form_view)
self._check_referer_rejects(mw, req)
response = mw.process_view(req, post_form_view, (), {})
self.assertContains(
response,
@ -359,28 +372,33 @@ class CsrfViewMiddlewareTestMixin:
)
# Empty
req.META['HTTP_REFERER'] = ''
self._check_referer_rejects(mw, req)
response = mw.process_view(req, post_form_view, (), {})
self.assertContains(response, malformed_referer_msg, status_code=403)
# Non-ASCII
req.META['HTTP_REFERER'] = 'ØBöIß'
self._check_referer_rejects(mw, req)
response = mw.process_view(req, post_form_view, (), {})
self.assertContains(response, malformed_referer_msg, status_code=403)
# missing scheme
# >>> urlparse('//example.com/')
# ParseResult(scheme='', netloc='example.com', path='/', params='', query='', fragment='')
req.META['HTTP_REFERER'] = '//example.com/'
self._check_referer_rejects(mw, req)
response = mw.process_view(req, post_form_view, (), {})
self.assertContains(response, malformed_referer_msg, status_code=403)
# missing netloc
# >>> urlparse('https://')
# ParseResult(scheme='https', netloc='', path='', params='', query='', fragment='')
req.META['HTTP_REFERER'] = 'https://'
self._check_referer_rejects(mw, req)
response = mw.process_view(req, post_form_view, (), {})
self.assertContains(response, malformed_referer_msg, status_code=403)
# Invalid URL
# >>> urlparse('https://[')
# ValueError: Invalid IPv6 URL
req.META['HTTP_REFERER'] = 'https://['
self._check_referer_rejects(mw, req)
response = mw.process_view(req, post_form_view, (), {})
self.assertContains(response, malformed_referer_msg, status_code=403)
@ -562,6 +580,7 @@ class CsrfViewMiddlewareTestMixin:
req.META['HTTP_HOST'] = 'www.example.com'
req.META['HTTP_ORIGIN'] = 'https://www.evil.org'
mw = CsrfViewMiddleware(post_form_view)
self._check_referer_rejects(mw, req)
self.assertIs(mw._origin_verified(req), False)
with self.assertLogs('django.security.csrf', 'WARNING') as cm:
response = mw.process_view(req, post_form_view, (), {})
@ -576,6 +595,7 @@ class CsrfViewMiddlewareTestMixin:
req.META['HTTP_HOST'] = 'www.example.com'
req.META['HTTP_ORIGIN'] = 'null'
mw = CsrfViewMiddleware(post_form_view)
self._check_referer_rejects(mw, req)
self.assertIs(mw._origin_verified(req), False)
with self.assertLogs('django.security.csrf', 'WARNING') as cm:
response = mw.process_view(req, post_form_view, (), {})
@ -591,6 +611,7 @@ class CsrfViewMiddlewareTestMixin:
req.META['HTTP_HOST'] = 'www.example.com'
req.META['HTTP_ORIGIN'] = 'http://example.com'
mw = CsrfViewMiddleware(post_form_view)
self._check_referer_rejects(mw, req)
self.assertIs(mw._origin_verified(req), False)
with self.assertLogs('django.security.csrf', 'WARNING') as cm:
response = mw.process_view(req, post_form_view, (), {})
@ -617,6 +638,7 @@ class CsrfViewMiddlewareTestMixin:
req.META['HTTP_HOST'] = 'www.example.com'
req.META['HTTP_ORIGIN'] = 'http://foo.example.com'
mw = CsrfViewMiddleware(post_form_view)
self._check_referer_rejects(mw, req)
self.assertIs(mw._origin_verified(req), False)
with self.assertLogs('django.security.csrf', 'WARNING') as cm:
response = mw.process_view(req, post_form_view, (), {})
@ -639,6 +661,7 @@ class CsrfViewMiddlewareTestMixin:
req.META['HTTP_HOST'] = 'www.example.com'
req.META['HTTP_ORIGIN'] = 'https://['
mw = CsrfViewMiddleware(post_form_view)
self._check_referer_rejects(mw, req)
self.assertIs(mw._origin_verified(req), False)
with self.assertLogs('django.security.csrf', 'WARNING') as cm:
response = mw.process_view(req, post_form_view, (), {})
@ -867,6 +890,7 @@ class CsrfViewMiddlewareTests(CsrfViewMiddlewareTestMixin, SimpleTestCase):
req.META['HTTP_REFERER'] = 'http://example.com/'
req.META['SERVER_PORT'] = '443'
mw = CsrfViewMiddleware(post_form_view)
self._check_referer_rejects(mw, req)
response = mw.process_view(req, post_form_view, (), {})
self.assertContains(
response,