diff options
Diffstat (limited to 'urllib3/contrib/pyopenssl.py')
| -rw-r--r-- | urllib3/contrib/pyopenssl.py | 85 |
1 files changed, 77 insertions, 8 deletions
diff --git a/urllib3/contrib/pyopenssl.py b/urllib3/contrib/pyopenssl.py index d43bcd6..7c513f3 100644 --- a/urllib3/contrib/pyopenssl.py +++ b/urllib3/contrib/pyopenssl.py @@ -1,4 +1,4 @@ -'''SSL with SNI-support for Python 2. +'''SSL with SNI_-support for Python 2. This needs the following packages installed: @@ -18,17 +18,36 @@ your application begins using ``urllib3``, like this:: Now you can use :mod:`urllib3` as you normally would, and it will support SNI when the required modules are installed. + +Activating this module also has the positive side effect of disabling SSL/TLS +encryption in Python 2 (see `CRIME attack`_). + +If you want to configure the default list of supported cipher suites, you can +set the ``urllib3.contrib.pyopenssl.DEFAULT_SSL_CIPHER_LIST`` variable. + +Module Variables +---------------- + +:var DEFAULT_SSL_CIPHER_LIST: The list of supported SSL/TLS cipher suites. + Default: ``ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:ECDH+AES128:DH+AES: + ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+3DES:!aNULL:!MD5:!DSS`` + +.. _sni: https://en.wikipedia.org/wiki/Server_Name_Indication +.. _crime attack: https://en.wikipedia.org/wiki/CRIME_(security_exploit) + ''' from ndg.httpsclient.ssl_peer_verification import SUBJ_ALT_NAME_SUPPORT -from ndg.httpsclient.subj_alt_name import SubjectAltName +from ndg.httpsclient.subj_alt_name import SubjectAltName as BaseSubjectAltName import OpenSSL.SSL from pyasn1.codec.der import decoder as der_decoder -from socket import _fileobject +from pyasn1.type import univ, constraint +from socket import _fileobject, timeout import ssl +import select from cStringIO import StringIO -from .. import connectionpool +from .. import connection from .. import util __all__ = ['inject_into_urllib3', 'extract_from_urllib3'] @@ -49,26 +68,54 @@ _openssl_verify = { + OpenSSL.SSL.VERIFY_FAIL_IF_NO_PEER_CERT, } +# A secure default. +# Sources for more information on TLS ciphers: +# +# - https://wiki.mozilla.org/Security/Server_Side_TLS +# - https://www.ssllabs.com/projects/best-practices/index.html +# - https://hynek.me/articles/hardening-your-web-servers-ssl-ciphers/ +# +# The general intent is: +# - Prefer cipher suites that offer perfect forward secrecy (DHE/ECDHE), +# - prefer ECDHE over DHE for better performance, +# - prefer any AES-GCM over any AES-CBC for better performance and security, +# - use 3DES as fallback which is secure but slow, +# - disable NULL authentication, MD5 MACs and DSS for security reasons. +DEFAULT_SSL_CIPHER_LIST = "ECDH+AESGCM:DH+AESGCM:ECDH+AES256:DH+AES256:" + \ + "ECDH+AES128:DH+AES:ECDH+3DES:DH+3DES:RSA+AESGCM:RSA+AES:RSA+3DES:" + \ + "!aNULL:!MD5:!DSS" + orig_util_HAS_SNI = util.HAS_SNI -orig_connectionpool_ssl_wrap_socket = connectionpool.ssl_wrap_socket +orig_connection_ssl_wrap_socket = connection.ssl_wrap_socket def inject_into_urllib3(): 'Monkey-patch urllib3 with PyOpenSSL-backed SSL-support.' - connectionpool.ssl_wrap_socket = ssl_wrap_socket + connection.ssl_wrap_socket = ssl_wrap_socket util.HAS_SNI = HAS_SNI def extract_from_urllib3(): 'Undo monkey-patching by :func:`inject_into_urllib3`.' - connectionpool.ssl_wrap_socket = orig_connectionpool_ssl_wrap_socket + connection.ssl_wrap_socket = orig_connection_ssl_wrap_socket util.HAS_SNI = orig_util_HAS_SNI ### Note: This is a slightly bug-fixed version of same from ndg-httpsclient. +class SubjectAltName(BaseSubjectAltName): + '''ASN.1 implementation for subjectAltNames support''' + + # There is no limit to how many SAN certificates a certificate may have, + # however this needs to have some limit so we'll set an arbitrarily high + # limit. + sizeSpec = univ.SequenceOf.sizeSpec + \ + constraint.ValueSizeConstraint(1, 1024) + + +### Note: This is a slightly bug-fixed version of same from ndg-httpsclient. def get_subj_alt_name(peer_cert): # Search through extensions dns_name = [] @@ -101,6 +148,13 @@ def get_subj_alt_name(peer_cert): class fileobject(_fileobject): + def _wait_for_sock(self): + rd, wd, ed = select.select([self._sock], [], [], + self._sock.gettimeout()) + if not rd: + raise timeout() + + def read(self, size=-1): # Use max, disallow tiny reads in a loop as they are very inefficient. # We never leave read() with any leftover data from a new recv() call @@ -118,6 +172,7 @@ class fileobject(_fileobject): try: data = self._sock.recv(rbufsize) except OpenSSL.SSL.WantReadError: + self._wait_for_sock() continue if not data: break @@ -145,6 +200,7 @@ class fileobject(_fileobject): try: data = self._sock.recv(left) except OpenSSL.SSL.WantReadError: + self._wait_for_sock() continue if not data: break @@ -196,6 +252,7 @@ class fileobject(_fileobject): break buffers.append(data) except OpenSSL.SSL.WantReadError: + self._wait_for_sock() continue break return "".join(buffers) @@ -206,6 +263,7 @@ class fileobject(_fileobject): try: data = self._sock.recv(self._rbufsize) except OpenSSL.SSL.WantReadError: + self._wait_for_sock() continue if not data: break @@ -233,7 +291,8 @@ class fileobject(_fileobject): try: data = self._sock.recv(self._rbufsize) except OpenSSL.SSL.WantReadError: - continue + self._wait_for_sock() + continue if not data: break left = size - buf_len @@ -328,6 +387,15 @@ def ssl_wrap_socket(sock, keyfile=None, certfile=None, cert_reqs=None, ctx.load_verify_locations(ca_certs, None) except OpenSSL.SSL.Error as e: raise ssl.SSLError('bad ca_certs: %r' % ca_certs, e) + else: + ctx.set_default_verify_paths() + + # Disable TLS compression to migitate CRIME attack (issue #309) + OP_NO_COMPRESSION = 0x20000 + ctx.set_options(OP_NO_COMPRESSION) + + # Set list of supported ciphersuites. + ctx.set_cipher_list(DEFAULT_SSL_CIPHER_LIST) cnx = OpenSSL.SSL.Connection(ctx, sock) cnx.set_tlsext_host_name(server_hostname) @@ -336,6 +404,7 @@ def ssl_wrap_socket(sock, keyfile=None, certfile=None, cert_reqs=None, try: cnx.do_handshake() except OpenSSL.SSL.WantReadError: + select.select([sock], [], []) continue except OpenSSL.SSL.Error as e: raise ssl.SSLError('bad handshake', e) |