diff options
Diffstat (limited to 'synapse/crypto/context_factory.py')
| -rw-r--r-- | synapse/crypto/context_factory.py | 180 |
1 files changed, 106 insertions, 74 deletions
diff --git a/synapse/crypto/context_factory.py b/synapse/crypto/context_factory.py index 59ea087e66..2bc5cc3807 100644 --- a/synapse/crypto/context_factory.py +++ b/synapse/crypto/context_factory.py @@ -15,10 +15,13 @@ import logging +import idna +from service_identity import VerificationError +from service_identity.pyopenssl import verify_hostname, verify_ip_address from zope.interface import implementer from OpenSSL import SSL, crypto -from twisted.internet._sslverify import ClientTLSOptions, _defaultCurveName +from twisted.internet._sslverify import _defaultCurveName from twisted.internet.abstract import isIPAddress, isIPv6Address from twisted.internet.interfaces import IOpenSSLClientConnectionCreator from twisted.internet.ssl import CertificateOptions, ContextFactory, platformTrust @@ -56,79 +59,19 @@ class ServerContextFactory(ContextFactory): return self._context -def _idnaBytes(text): - """ - Convert some text typed by a human into some ASCII bytes. This is a - copy of twisted.internet._idna._idnaBytes. For documentation, see the - twisted documentation. - """ - try: - import idna - except ImportError: - return text.encode("idna") - else: - return idna.encode(text) - - -def _tolerateErrors(wrapped): - """ - Wrap up an info_callback for pyOpenSSL so that if something goes wrong - the error is immediately logged and the connection is dropped if possible. - This is a copy of twisted.internet._sslverify._tolerateErrors. For - documentation, see the twisted documentation. - """ - - def infoCallback(connection, where, ret): - try: - return wrapped(connection, where, ret) - except: # noqa: E722, taken from the twisted implementation - f = Failure() - logger.exception("Error during info_callback") - connection.get_app_data().failVerification(f) - - return infoCallback +class ClientTLSOptionsFactory(object): + """Factory for Twisted SSLClientConnectionCreators that are used to make connections + to remote servers for federation. + Uses one of two OpenSSL context objects for all connections, depending on whether + we should do SSL certificate verification. -@implementer(IOpenSSLClientConnectionCreator) -class ClientTLSOptionsNoVerify(object): - """ - Client creator for TLS without certificate identity verification. This is a - copy of twisted.internet._sslverify.ClientTLSOptions with the identity - verification left out. For documentation, see the twisted documentation. + get_options decides whether we should do SSL certificate verification and + constructs an SSLClientConnectionCreator factory accordingly. """ - def __init__(self, hostname, ctx): - self._ctx = ctx - - if isIPAddress(hostname) or isIPv6Address(hostname): - self._hostnameBytes = hostname.encode('ascii') - self._sendSNI = False - else: - self._hostnameBytes = _idnaBytes(hostname) - self._sendSNI = True - - ctx.set_info_callback(_tolerateErrors(self._identityVerifyingInfoCallback)) - - def clientConnectionForTLS(self, tlsProtocol): - context = self._ctx - connection = SSL.Connection(context, None) - connection.set_app_data(tlsProtocol) - return connection - - def _identityVerifyingInfoCallback(self, connection, where, ret): - # Literal IPv4 and IPv6 addresses are not permitted - # as host names according to the RFCs - if where & SSL.SSL_CB_HANDSHAKE_START and self._sendSNI: - connection.set_tlsext_host_name(self._hostnameBytes) - - -class ClientTLSOptionsFactory(object): - """Factory for Twisted ClientTLSOptions that are used to make connections - to remote servers for federation.""" - def __init__(self, config): self._config = config - self._options_noverify = CertificateOptions() # Check if we're using a custom list of a CA certificates trust_root = config.federation_ca_trust_root @@ -136,11 +79,13 @@ class ClientTLSOptionsFactory(object): # Use CA root certs provided by OpenSSL trust_root = platformTrust() - self._options_verify = CertificateOptions(trustRoot=trust_root) + self._verify_ssl_context = CertificateOptions(trustRoot=trust_root).getContext() + self._verify_ssl_context.set_info_callback(self._context_info_cb) - def get_options(self, host): - # Use _makeContext so that we get a fresh OpenSSL CTX each time. + self._no_verify_ssl_context = CertificateOptions().getContext() + self._no_verify_ssl_context.set_info_callback(self._context_info_cb) + def get_options(self, host): # Check if certificate verification has been enabled should_verify = self._config.federation_verify_certificates @@ -151,6 +96,93 @@ class ClientTLSOptionsFactory(object): should_verify = False break - if should_verify: - return ClientTLSOptions(host, self._options_verify._makeContext()) - return ClientTLSOptionsNoVerify(host, self._options_noverify._makeContext()) + ssl_context = ( + self._verify_ssl_context if should_verify else self._no_verify_ssl_context + ) + + return SSLClientConnectionCreator(host, ssl_context, should_verify) + + @staticmethod + def _context_info_cb(ssl_connection, where, ret): + """The 'information callback' for our openssl context object.""" + # we assume that the app_data on the connection object has been set to + # a TLSMemoryBIOProtocol object. (This is done by SSLClientConnectionCreator) + tls_protocol = ssl_connection.get_app_data() + try: + # ... we further assume that SSLClientConnectionCreator has set the + # '_synapse_tls_verifier' attribute to a ConnectionVerifier object. + tls_protocol._synapse_tls_verifier.verify_context_info_cb( + ssl_connection, where + ) + except: # noqa: E722, taken from the twisted implementation + logger.exception("Error during info_callback") + f = Failure() + tls_protocol.failVerification(f) + + +@implementer(IOpenSSLClientConnectionCreator) +class SSLClientConnectionCreator(object): + """Creates openssl connection objects for client connections. + + Replaces twisted.internet.ssl.ClientTLSOptions + """ + + def __init__(self, hostname, ctx, verify_certs): + self._ctx = ctx + self._verifier = ConnectionVerifier(hostname, verify_certs) + + def clientConnectionForTLS(self, tls_protocol): + context = self._ctx + connection = SSL.Connection(context, None) + + # as per twisted.internet.ssl.ClientTLSOptions, we set the application + # data to our TLSMemoryBIOProtocol... + connection.set_app_data(tls_protocol) + + # ... and we also gut-wrench a '_synapse_tls_verifier' attribute into the + # tls_protocol so that the SSL context's info callback has something to + # call to do the cert verification. + setattr(tls_protocol, "_synapse_tls_verifier", self._verifier) + return connection + + +class ConnectionVerifier(object): + """Set the SNI, and do cert verification + + This is a thing which is attached to the TLSMemoryBIOProtocol, and is called by + the ssl context's info callback. + """ + + # This code is based on twisted.internet.ssl.ClientTLSOptions. + + def __init__(self, hostname, verify_certs): + self._verify_certs = verify_certs + + if isIPAddress(hostname) or isIPv6Address(hostname): + self._hostnameBytes = hostname.encode("ascii") + self._is_ip_address = True + else: + # twisted's ClientTLSOptions falls back to the stdlib impl here if + # idna is not installed, but points out that lacks support for + # IDNA2008 (http://bugs.python.org/issue17305). + # + # We can rely on having idna. + self._hostnameBytes = idna.encode(hostname) + self._is_ip_address = False + + self._hostnameASCII = self._hostnameBytes.decode("ascii") + + def verify_context_info_cb(self, ssl_connection, where): + if where & SSL.SSL_CB_HANDSHAKE_START and not self._is_ip_address: + ssl_connection.set_tlsext_host_name(self._hostnameBytes) + + if where & SSL.SSL_CB_HANDSHAKE_DONE and self._verify_certs: + try: + if self._is_ip_address: + verify_ip_address(ssl_connection, self._hostnameASCII) + else: + verify_hostname(ssl_connection, self._hostnameASCII) + except VerificationError: + f = Failure() + tls_protocol = ssl_connection.get_app_data() + tls_protocol.failVerification(f) |