From e3e7d40514e5dd0c3847682a719577efcfae1d8f Mon Sep 17 00:00:00 2001
From: Benjamin Peterson <benjamin@python.org>
Date: Sun, 23 Nov 2014 21:02:02 -0600
Subject: pep 476: verify certificates by default (#22417)
---
Doc/library/httplib.rst | 8 +++++---
Doc/library/xmlrpclib.rst | 7 +++----
Doc/whatsnew/2.7.rst | 23 +++++++++++++++++++++++
Lib/httplib.py | 2 +-
Lib/ssl.py | 11 +++++++++--
Lib/test/test_httplib.py | 3 +--
Lib/test/test_urllib2_localnet.py | 27 +++++++++++++++++++++++++--
Misc/NEWS | 2 ++
8 files changed, 69 insertions(+), 14 deletions(-)
diff --git a/Doc/library/httplib.rst b/Doc/library/httplib.rst
index 23b0e64..b659fd0 100644
--- a/Doc/library/httplib.rst
+++ b/Doc/library/httplib.rst
@@ -90,9 +90,6 @@ The module provides the following classes:
server's certificate. If you want to change that behaviour, you can
explicitly set *check_hostname* to False.
- .. warning::
- This does not do any verification of the server's certificate.
-
.. versionadded:: 2.0
.. versionchanged:: 2.6
@@ -104,6 +101,11 @@ The module provides the following classes:
.. versionchanged:: 2.7.9
*context* and *check_hostname* was added.
+ This class now performs all the necessary certificate and hostname checks
+ by default. To revert to the previous, unverified, behavior
+ :func:`ssl._create_unverified_context` can be passed to the *context*
+ parameter.
+
.. class:: HTTPResponse(sock, debuglevel=0, strict=0)
diff --git a/Doc/library/xmlrpclib.rst b/Doc/library/xmlrpclib.rst
index 720da39..3aa8be0 100644
--- a/Doc/library/xmlrpclib.rst
+++ b/Doc/library/xmlrpclib.rst
@@ -34,11 +34,10 @@ between conformable Python objects and XML on the wire.
constructed data. If you need to parse untrusted or unauthenticated data see
:ref:`xml-vulnerabilities`.
-.. warning::
-
- In the case of https URIs, :mod:`xmlrpclib` does not do any verification of
- the server's certificate.
+.. versionchanged:: 2.7.9
+ For https URIs, :mod:`xmlrpclib` now performs all the necessary certificate
+ and hostname checks by default
.. class:: ServerProxy(uri[, transport[, encoding[, verbose[, allow_none[, use_datetime]]]]])
diff --git a/Doc/whatsnew/2.7.rst b/Doc/whatsnew/2.7.rst
index 9b02687..65eaf17 100644
--- a/Doc/whatsnew/2.7.rst
+++ b/Doc/whatsnew/2.7.rst
@@ -2646,6 +2646,29 @@ and :ref:`distutils-index`.
PEP written by Donald Stufft and Nick Coghlan, implemented by
Donald Stufft, Nick Coghlan, Martin von Löwis and Ned Deily.
+PEP 476: Enabling certificate verification by default for stdlib http clients
+-----------------------------------------------------------------------------
+
+:mod:`httplib` and modules which use it, such as :mod:`urllib2` and
+:mod:`xmlrpclib`, will now verify that the server presents a certificate
+which is signed by a CA in the platform trust store and whose hostname matches
+the hostname being requested by default, significantly improving security for
+many applications.
+
+For applications which require the old previous behavior, they can pass an
+alternate context::
+
+ import urllib2
+ import ssl
+
+ # This disables all verification
+ context = ssl._create_unverified_context()
+
+ # This allows using a specific certificate for the host, which doesn't need
+ # to be in the trust store
+ context = ssl.create_default_context(cafile="/path/to/file.crt")
+
+ urllib2.urlopen("https://invalid-cert", context=context)
.. ======================================================================
diff --git a/Lib/httplib.py b/Lib/httplib.py
index 48fbcb6..7c27906 100644
--- a/Lib/httplib.py
+++ b/Lib/httplib.py
@@ -1193,7 +1193,7 @@ else:
self.key_file = key_file
self.cert_file = cert_file
if context is None:
- context = ssl.create_default_context()
+ context = ssl._create_default_https_context()
will_verify = context.verify_mode != ssl.CERT_NONE
if check_hostname is None:
check_hostname = will_verify
diff --git a/Lib/ssl.py b/Lib/ssl.py
index c9f25c0..0f82227 100644
--- a/Lib/ssl.py
+++ b/Lib/ssl.py
@@ -427,8 +427,7 @@ def create_default_context(purpose=Purpose.SERVER_AUTH, cafile=None,
context.load_default_certs(purpose)
return context
-
-def _create_stdlib_context(protocol=PROTOCOL_SSLv23, cert_reqs=None,
+def _create_unverified_context(protocol=PROTOCOL_SSLv23, cert_reqs=None,
check_hostname=False, purpose=Purpose.SERVER_AUTH,
certfile=None, keyfile=None,
cafile=None, capath=None, cadata=None):
@@ -469,6 +468,14 @@ def _create_stdlib_context(protocol=PROTOCOL_SSLv23, cert_reqs=None,
return context
+# Used by http.client if no context is explicitly passed.
+_create_default_https_context = create_default_context
+
+
+# Backwards compatibility alias, even though it's not a public name.
+_create_stdlib_context = _create_unverified_context
+
+
class SSLSocket(socket):
"""This class implements a subtype of socket.socket that wraps
the underlying OS socket in an SSL context when necessary, and
diff --git a/Lib/test/test_httplib.py b/Lib/test/test_httplib.py
index 60165c1..e68555a 100644
--- a/Lib/test/test_httplib.py
+++ b/Lib/test/test_httplib.py
@@ -1,10 +1,9 @@
import httplib
import array
-import httplib
-import os
import StringIO
import socket
import errno
+import os
import unittest
TestCase = unittest.TestCase
diff --git a/Lib/test/test_urllib2_localnet.py b/Lib/test/test_urllib2_localnet.py
index 8fc90af..a24a077 100644
--- a/Lib/test/test_urllib2_localnet.py
+++ b/Lib/test/test_urllib2_localnet.py
@@ -5,6 +5,7 @@ import urllib2
import BaseHTTPServer
import unittest
import hashlib
+import ssl
from test import test_support
@@ -562,15 +563,37 @@ class TestUrlopen(BaseTestCase):
cafile=CERT_localhost)
self.assertEqual(data, b"we care a bit")
# Bad cert
- with self.assertRaises(urllib2.URLError) as cm:
+ with self.assertRaises(urllib2.URLError):
self.urlopen("https://localhost:%s/bizarre" % handler.port,
cafile=CERT_fakehostname)
# Good cert, but mismatching hostname
handler = self.start_https_server(certfile=CERT_fakehostname)
- with self.assertRaises(ssl.CertificateError) as cm:
+ with self.assertRaises(ssl.CertificateError):
self.urlopen("https://localhost:%s/bizarre" % handler.port,
cafile=CERT_fakehostname)
+ def test_https_with_cadefault(self):
+ handler = self.start_https_server(certfile=CERT_localhost)
+ # Self-signed cert should fail verification with system certificate store
+ with self.assertRaises(urllib2.URLError):
+ self.urlopen("https://localhost:%s/bizarre" % handler.port,
+ cadefault=True)
+
+ def test_https_sni(self):
+ if ssl is None:
+ self.skipTest("ssl module required")
+ if not ssl.HAS_SNI:
+ self.skipTest("SNI support required in OpenSSL")
+ sni_name = [None]
+ def cb_sni(ssl_sock, server_name, initial_context):
+ sni_name[0] = server_name
+ context = ssl.SSLContext(ssl.PROTOCOL_TLSv1)
+ context.set_servername_callback(cb_sni)
+ handler = self.start_https_server(context=context, certfile=CERT_localhost)
+ context = ssl.create_default_context(cafile=CERT_localhost)
+ self.urlopen("https://localhost:%s" % handler.port, context=context)
+ self.assertEqual(sni_name[0], "localhost")
+
def test_sending_headers(self):
handler = self.start_server([(200, [], "we don't care")])
diff --git a/Misc/NEWS b/Misc/NEWS
index 3ad4862..923bfb7 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -42,6 +42,8 @@ Core and Builtins
Library
-------
+- Issue #22417: Verify certificates by default in httplib (PEP 476).
+
- Issue #22927: Allow urllib.urlopen to take a *context* parameter to control
SSL settings for HTTPS connections.
--
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