Share an SSL context object between SSL connections
This involves changing how the info callbacks work.
This commit is contained in:
Richard van der Hoff
parent
7c455a86bc
commit
c2b6e945e1
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@ -15,10 +15,12 @@
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import logging
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from service_identity import VerificationError
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from service_identity.pyopenssl import verify_hostname
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from zope.interface import implementer
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from OpenSSL import SSL, crypto
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from twisted.internet._sslverify import ClientTLSOptions, _defaultCurveName
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from twisted.internet._sslverify import _defaultCurveName
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from twisted.internet.abstract import isIPAddress, isIPv6Address
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from twisted.internet.interfaces import IOpenSSLClientConnectionCreator
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from twisted.internet.ssl import CertificateOptions, ContextFactory, platformTrust
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@ -70,65 +72,19 @@ def _idnaBytes(text):
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return idna.encode(text)
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def _tolerateErrors(wrapped):
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"""
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Wrap up an info_callback for pyOpenSSL so that if something goes wrong
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the error is immediately logged and the connection is dropped if possible.
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This is a copy of twisted.internet._sslverify._tolerateErrors. For
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documentation, see the twisted documentation.
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"""
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def infoCallback(connection, where, ret):
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try:
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return wrapped(connection, where, ret)
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except: # noqa: E722, taken from the twisted implementation
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f = Failure()
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logger.exception("Error during info_callback")
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connection.get_app_data().failVerification(f)
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return infoCallback
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@implementer(IOpenSSLClientConnectionCreator)
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class ClientTLSOptionsNoVerify(object):
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"""
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Client creator for TLS without certificate identity verification. This is a
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copy of twisted.internet._sslverify.ClientTLSOptions with the identity
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verification left out. For documentation, see the twisted documentation.
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"""
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def __init__(self, hostname, ctx):
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self._ctx = ctx
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if isIPAddress(hostname) or isIPv6Address(hostname):
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self._hostnameBytes = hostname.encode('ascii')
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self._sendSNI = False
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else:
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self._hostnameBytes = _idnaBytes(hostname)
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self._sendSNI = True
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ctx.set_info_callback(_tolerateErrors(self._identityVerifyingInfoCallback))
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def clientConnectionForTLS(self, tlsProtocol):
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context = self._ctx
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connection = SSL.Connection(context, None)
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connection.set_app_data(tlsProtocol)
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return connection
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def _identityVerifyingInfoCallback(self, connection, where, ret):
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# Literal IPv4 and IPv6 addresses are not permitted
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# as host names according to the RFCs
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if where & SSL.SSL_CB_HANDSHAKE_START and self._sendSNI:
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connection.set_tlsext_host_name(self._hostnameBytes)
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class ClientTLSOptionsFactory(object):
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"""Factory for Twisted ClientTLSOptions that are used to make connections
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to remote servers for federation."""
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"""Factory for Twisted SSLClientConnectionCreators that are used to make connections
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to remote servers for federation.
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Uses one of two OpenSSL context objects for all connections, depending on whether
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we should do SSL certificate verification.
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get_options decides whether we should do SSL certificate verification and
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constructs an SSLClientConnectionCreator factory accordingly.
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"""
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def __init__(self, config):
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self._config = config
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self._options_noverify = CertificateOptions()
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# Check if we're using a custom list of a CA certificates
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trust_root = config.federation_ca_trust_root
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@ -136,11 +92,13 @@ class ClientTLSOptionsFactory(object):
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# Use CA root certs provided by OpenSSL
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trust_root = platformTrust()
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self._options_verify = CertificateOptions(trustRoot=trust_root)
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self._verify_ssl_context = CertificateOptions(trustRoot=trust_root).getContext()
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self._verify_ssl_context.set_info_callback(self._context_info_cb)
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self._no_verify_ssl_context = CertificateOptions().getContext()
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self._no_verify_ssl_context.set_info_callback(self._context_info_cb)
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def get_options(self, host):
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# Use _makeContext so that we get a fresh OpenSSL CTX each time.
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# Check if certificate verification has been enabled
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should_verify = self._config.federation_verify_certificates
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@ -151,6 +109,77 @@ class ClientTLSOptionsFactory(object):
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should_verify = False
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break
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if should_verify:
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return ClientTLSOptions(host, self._options_verify._makeContext())
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return ClientTLSOptionsNoVerify(host, self._options_noverify._makeContext())
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ssl_context = (
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self._verify_ssl_context if should_verify else self._no_verify_ssl_context
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)
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return SSLClientConnectionCreator(host, ssl_context, should_verify)
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@staticmethod
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def _context_info_cb(ssl_connection, where, ret):
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"""The 'information callback' for our openssl context object."""
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# we assume that the app_data on the connection object has been set to
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# a TLSMemoryBIOProtocol object. (This is done by SSLClientConnectionCreator)
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tls_protocol = ssl_connection.get_app_data()
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try:
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# ... we further assume that SSLClientConnectionCreator has set the
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# 'tls_verifier' attribute to a ConnectionVerifier object.
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tls_protocol.tls_verifier.verify_context_info_cb(ssl_connection, where)
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except: # noqa: E722, taken from the twisted implementation
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logger.exception("Error during info_callback")
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f = Failure()
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tls_protocol.failVerification(f)
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@implementer(IOpenSSLClientConnectionCreator)
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class SSLClientConnectionCreator(object):
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"""Creates openssl connection objects for client connections.
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Replaces twisted.internet.ssl.ClientTLSOptions
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"""
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def __init__(self, hostname, ctx, verify_certs):
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self._ctx = ctx
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self._verifier = ConnectionVerifier(hostname, verify_certs)
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def clientConnectionForTLS(self, tls_protocol):
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context = self._ctx
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connection = SSL.Connection(context, None)
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# as per twisted.internet.ssl.ClientTLSOptions, we set the application
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# data to our TLSMemoryBIOProtocol...
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connection.set_app_data(tls_protocol)
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# ... and we also gut-wrench a 'tls_verifier' attribute into the
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# tls_protocol so that the SSL context's info callback has something to
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# call to do the cert verification.
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setattr(tls_protocol, "tls_verifier", self._verifier)
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return connection
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class ConnectionVerifier(object):
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"""Set the SNI, and do cert verification
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This is a thing which is attached to the TLSMemoryBIOProtocol, and is called by
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the ssl context's info callback.
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"""
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def __init__(self, hostname, verify_certs):
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self._verify_certs = verify_certs
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if isIPAddress(hostname) or isIPv6Address(hostname):
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self._hostnameBytes = hostname.encode('ascii')
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self._sendSNI = False
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else:
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self._hostnameBytes = _idnaBytes(hostname)
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self._sendSNI = True
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self._hostnameASCII = self._hostnameBytes.decode("ascii")
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def verify_context_info_cb(self, ssl_connection, where):
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if where & SSL.SSL_CB_HANDSHAKE_START and self._sendSNI:
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ssl_connection.set_tlsext_host_name(self._hostnameBytes)
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if where & SSL.SSL_CB_HANDSHAKE_DONE and self._verify_certs:
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try:
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verify_hostname(ssl_connection, self._hostnameASCII)
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except VerificationError:
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f = Failure()
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tls_protocol = ssl_connection.get_app_data()
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tls_protocol.failVerification(f)
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