mirror of https://github.com/python/cpython
Issue #12551: Provide a get_channel_binding() method on SSL sockets so as
to get channel binding data for the current SSL session (only the "tls-unique" channel binding is implemented). This allows the implementation of certain authentication mechanisms such as SCRAM-SHA-1-PLUS. Patch by Jacek Konieczny.
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d649480739
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@ -386,6 +386,13 @@ Constants
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.. versionadded:: 3.2
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.. data:: CHANNEL_BINDING_TYPES
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List of supported TLS channel binding types. Strings in this list
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can be used as arguments to :meth:`SSLSocket.get_channel_binding`.
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.. versionadded:: 3.3
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.. data:: OPENSSL_VERSION
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The version string of the OpenSSL library loaded by the interpreter::
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@ -495,6 +502,18 @@ SSL sockets also have the following additional methods and attributes:
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version of the SSL protocol that defines its use, and the number of secret
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bits being used. If no connection has been established, returns ``None``.
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.. method:: SSLSocket.get_channel_binding(cb_type="tls-unique")
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Get channel binding data for current connection, as a bytes object. Returns
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``None`` if not connected or the handshake has not been completed.
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The *cb_type* parameter allow selection of the desired channel binding
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type. Valid channel binding types are listed in the
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:data:`CHANNEL_BINDING_TYPES` list. Currently only the 'tls-unique' channel
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binding, defined by :rfc:`5929`, is supported. :exc:`ValueError` will be
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raised if an unsupported channel binding type is requested.
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.. versionadded:: 3.3
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.. method:: SSLSocket.unwrap()
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19
Lib/ssl.py
19
Lib/ssl.py
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@ -99,6 +99,10 @@ import base64 # for DER-to-PEM translation
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import traceback
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import errno
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if _ssl.HAS_TLS_UNIQUE:
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CHANNEL_BINDING_TYPES = ['tls-unique']
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else:
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CHANNEL_BINDING_TYPES = []
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class CertificateError(ValueError):
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pass
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@ -495,6 +499,21 @@ class SSLSocket(socket):
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self.do_handshake_on_connect),
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addr)
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def get_channel_binding(self, cb_type="tls-unique"):
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"""Get channel binding data for current connection. Raise ValueError
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if the requested `cb_type` is not supported. Return bytes of the data
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or None if the data is not available (e.g. before the handshake).
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"""
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if cb_type not in CHANNEL_BINDING_TYPES:
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raise ValueError("Unsupported channel binding type")
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if cb_type != "tls-unique":
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raise NotImplementedError(
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"{0} channel binding type not implemented"
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.format(cb_type))
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if self._sslobj is None:
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return None
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return self._sslobj.tls_unique_cb()
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def __del__(self):
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# sys.stderr.write("__del__ on %s\n" % repr(self))
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self._real_close()
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@ -321,6 +321,25 @@ class BasicSocketTests(unittest.TestCase):
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self.assertRaises(ValueError, ctx.wrap_socket, sock, True,
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server_hostname="some.hostname")
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def test_unknown_channel_binding(self):
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# should raise ValueError for unknown type
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s = socket.socket(socket.AF_INET)
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ss = ssl.wrap_socket(s)
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with self.assertRaises(ValueError):
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ss.get_channel_binding("unknown-type")
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@unittest.skipUnless("tls-unique" in ssl.CHANNEL_BINDING_TYPES,
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"'tls-unique' channel binding not available")
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def test_tls_unique_channel_binding(self):
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# unconnected should return None for known type
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s = socket.socket(socket.AF_INET)
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ss = ssl.wrap_socket(s)
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self.assertIsNone(ss.get_channel_binding("tls-unique"))
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# the same for server-side
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s = socket.socket(socket.AF_INET)
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ss = ssl.wrap_socket(s, server_side=True, certfile=CERTFILE)
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self.assertIsNone(ss.get_channel_binding("tls-unique"))
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class ContextTests(unittest.TestCase):
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@skip_if_broken_ubuntu_ssl
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@ -826,6 +845,11 @@ else:
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self.sslconn = None
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if support.verbose and self.server.connectionchatty:
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sys.stdout.write(" server: connection is now unencrypted...\n")
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elif stripped == b'CB tls-unique':
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if support.verbose and self.server.connectionchatty:
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sys.stdout.write(" server: read CB tls-unique from client, sending our CB data...\n")
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data = self.sslconn.get_channel_binding("tls-unique")
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self.write(repr(data).encode("us-ascii") + b"\n")
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else:
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if (support.verbose and
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self.server.connectionchatty):
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@ -1625,6 +1649,73 @@ else:
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t.join()
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server.close()
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@unittest.skipUnless("tls-unique" in ssl.CHANNEL_BINDING_TYPES,
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"'tls-unique' channel binding not available")
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def test_tls_unique_channel_binding(self):
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"""Test tls-unique channel binding."""
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if support.verbose:
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sys.stdout.write("\n")
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server = ThreadedEchoServer(CERTFILE,
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certreqs=ssl.CERT_NONE,
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ssl_version=ssl.PROTOCOL_TLSv1,
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cacerts=CERTFILE,
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chatty=True,
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connectionchatty=False)
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flag = threading.Event()
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server.start(flag)
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# wait for it to start
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flag.wait()
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# try to connect
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s = ssl.wrap_socket(socket.socket(),
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server_side=False,
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certfile=CERTFILE,
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ca_certs=CERTFILE,
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cert_reqs=ssl.CERT_NONE,
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ssl_version=ssl.PROTOCOL_TLSv1)
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s.connect((HOST, server.port))
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try:
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# get the data
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cb_data = s.get_channel_binding("tls-unique")
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if support.verbose:
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sys.stdout.write(" got channel binding data: {0!r}\n"
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.format(cb_data))
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# check if it is sane
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self.assertIsNotNone(cb_data)
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self.assertEqual(len(cb_data), 12) # True for TLSv1
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# and compare with the peers version
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s.write(b"CB tls-unique\n")
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peer_data_repr = s.read().strip()
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self.assertEqual(peer_data_repr,
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repr(cb_data).encode("us-ascii"))
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s.close()
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# now, again
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s = ssl.wrap_socket(socket.socket(),
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server_side=False,
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certfile=CERTFILE,
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ca_certs=CERTFILE,
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cert_reqs=ssl.CERT_NONE,
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ssl_version=ssl.PROTOCOL_TLSv1)
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s.connect((HOST, server.port))
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new_cb_data = s.get_channel_binding("tls-unique")
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if support.verbose:
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sys.stdout.write(" got another channel binding data: {0!r}\n"
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.format(new_cb_data))
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# is it really unique
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self.assertNotEqual(cb_data, new_cb_data)
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self.assertIsNotNone(cb_data)
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self.assertEqual(len(cb_data), 12) # True for TLSv1
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s.write(b"CB tls-unique\n")
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peer_data_repr = s.read().strip()
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self.assertEqual(peer_data_repr,
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repr(new_cb_data).encode("us-ascii"))
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s.close()
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finally:
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server.stop()
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server.join()
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def test_main(verbose=False):
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if support.verbose:
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@ -516,6 +516,7 @@ Lenny Kneler
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Pat Knight
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Greg Kochanski
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Damon Kohler
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Jacek Konieczny
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Марк Коренберг
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Vlad Korolev
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Joseph Koshy
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@ -234,6 +234,12 @@ Core and Builtins
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Library
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-------
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- Issue #12551: Provide a get_channel_binding() method on SSL sockets so as
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to get channel binding data for the current SSL session (only the
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"tls-unique" channel binding is implemented). This allows the implementation
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of certain authentication mechanisms such as SCRAM-SHA-1-PLUS. Patch by
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Jacek Konieczny.
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- Issue #665194: email.utils now has format_datetime and parsedate_to_datetime
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functions, allowing for round tripping of RFC2822 format dates.
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@ -124,6 +124,17 @@ static unsigned int _ssl_locks_count = 0;
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# undef HAVE_SSL_CTX_CLEAR_OPTIONS
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#endif
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/* In case of 'tls-unique' it will be 12 bytes for TLS, 36 bytes for
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* older SSL, but let's be safe */
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#define PySSL_CB_MAXLEN 128
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/* SSL_get_finished got added to OpenSSL in 0.9.5 */
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#if OPENSSL_VERSION_NUMBER >= 0x0090500fL
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# define HAVE_OPENSSL_FINISHED 1
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#else
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# define HAVE_OPENSSL_FINISHED 0
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#endif
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typedef struct {
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PyObject_HEAD
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SSL_CTX *ctx;
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@ -135,6 +146,7 @@ typedef struct {
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SSL *ssl;
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X509 *peer_cert;
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int shutdown_seen_zero;
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enum py_ssl_server_or_client socket_type;
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} PySSLSocket;
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static PyTypeObject PySSLContext_Type;
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@ -328,6 +340,7 @@ newPySSLSocket(SSL_CTX *ctx, PySocketSockObject *sock,
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SSL_set_accept_state(self->ssl);
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PySSL_END_ALLOW_THREADS
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self->socket_type = socket_type;
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self->Socket = PyWeakref_NewRef((PyObject *) sock, NULL);
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return self;
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}
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@ -1377,6 +1390,41 @@ PyDoc_STRVAR(PySSL_SSLshutdown_doc,
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Does the SSL shutdown handshake with the remote end, and returns\n\
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the underlying socket object.");
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#if HAVE_OPENSSL_FINISHED
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static PyObject *
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PySSL_tls_unique_cb(PySSLSocket *self)
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{
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PyObject *retval = NULL;
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char buf[PySSL_CB_MAXLEN];
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int len;
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if (SSL_session_reused(self->ssl) ^ !self->socket_type) {
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/* if session is resumed XOR we are the client */
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len = SSL_get_finished(self->ssl, buf, PySSL_CB_MAXLEN);
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}
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else {
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/* if a new session XOR we are the server */
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len = SSL_get_peer_finished(self->ssl, buf, PySSL_CB_MAXLEN);
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}
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/* It cannot be negative in current OpenSSL version as of July 2011 */
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assert(len >= 0);
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if (len == 0)
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Py_RETURN_NONE;
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retval = PyBytes_FromStringAndSize(buf, len);
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return retval;
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}
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PyDoc_STRVAR(PySSL_tls_unique_cb_doc,
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"tls_unique_cb() -> bytes\n\
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\n\
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Returns the 'tls-unique' channel binding data, as defined by RFC 5929.\n\
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\n\
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If the TLS handshake is not yet complete, None is returned");
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#endif /* HAVE_OPENSSL_FINISHED */
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static PyMethodDef PySSLMethods[] = {
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{"do_handshake", (PyCFunction)PySSL_SSLdo_handshake, METH_NOARGS},
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@ -1391,6 +1439,10 @@ static PyMethodDef PySSLMethods[] = {
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{"cipher", (PyCFunction)PySSL_cipher, METH_NOARGS},
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{"shutdown", (PyCFunction)PySSL_SSLshutdown, METH_NOARGS,
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PySSL_SSLshutdown_doc},
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#if HAVE_OPENSSL_FINISHED
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{"tls_unique_cb", (PyCFunction)PySSL_tls_unique_cb, METH_NOARGS,
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PySSL_tls_unique_cb_doc},
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#endif
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{NULL, NULL}
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};
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@ -2221,6 +2273,14 @@ PyInit__ssl(void)
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Py_INCREF(r);
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PyModule_AddObject(m, "HAS_SNI", r);
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#if HAVE_OPENSSL_FINISHED
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r = Py_True;
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#else
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r = Py_False;
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#endif
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Py_INCREF(r);
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PyModule_AddObject(m, "HAS_TLS_UNIQUE", r);
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/* OpenSSL version */
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/* SSLeay() gives us the version of the library linked against,
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which could be different from the headers version.
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