From 6824ddd93df1cfc347e4c8f423d54fab5bb732fb Mon Sep 17 00:00:00 2001 From: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com> Date: Thu, 25 Apr 2019 06:22:49 -0700 Subject: Config option for verifying federation certificates (MSC 1711) (#4967) --- synapse/config/server.py | 6 +- synapse/config/tls.py | 95 ++++++++++++++++++++-- synapse/crypto/context_factory.py | 33 ++++++-- synapse/http/federation/matrix_federation_agent.py | 2 +- 4 files changed, 121 insertions(+), 15 deletions(-) (limited to 'synapse') diff --git a/synapse/config/server.py b/synapse/config/server.py index c5e5679d52..cdf1e4d286 100644 --- a/synapse/config/server.py +++ b/synapse/config/server.py @@ -114,11 +114,13 @@ class ServerConfig(Config): # FIXME: federation_domain_whitelist needs sytests self.federation_domain_whitelist = None federation_domain_whitelist = config.get( - "federation_domain_whitelist", None + "federation_domain_whitelist", None, ) - # turn the whitelist into a hash for speed of lookup + if federation_domain_whitelist is not None: + # turn the whitelist into a hash for speed of lookup self.federation_domain_whitelist = {} + for domain in federation_domain_whitelist: self.federation_domain_whitelist[domain] = True diff --git a/synapse/config/tls.py b/synapse/config/tls.py index f0014902da..72dd5926f9 100644 --- a/synapse/config/tls.py +++ b/synapse/config/tls.py @@ -24,8 +24,10 @@ import six from unpaddedbase64 import encode_base64 from OpenSSL import crypto +from twisted.internet._sslverify import Certificate, trustRootFromCertificates from synapse.config._base import Config, ConfigError +from synapse.util import glob_to_regex logger = logging.getLogger(__name__) @@ -70,6 +72,53 @@ class TlsConfig(Config): self.tls_fingerprints = list(self._original_tls_fingerprints) + # Whether to verify certificates on outbound federation traffic + self.federation_verify_certificates = config.get( + "federation_verify_certificates", False, + ) + + # Whitelist of domains to not verify certificates for + fed_whitelist_entries = config.get( + "federation_certificate_verification_whitelist", [], + ) + + # Support globs (*) in whitelist values + self.federation_certificate_verification_whitelist = [] + for entry in fed_whitelist_entries: + # Convert globs to regex + entry_regex = glob_to_regex(entry) + self.federation_certificate_verification_whitelist.append(entry_regex) + + # List of custom certificate authorities for federation traffic validation + custom_ca_list = config.get( + "federation_custom_ca_list", None, + ) + + # Read in and parse custom CA certificates + self.federation_ca_trust_root = None + if custom_ca_list is not None: + if len(custom_ca_list) == 0: + # A trustroot cannot be generated without any CA certificates. + # Raise an error if this option has been specified without any + # corresponding certificates. + raise ConfigError("federation_custom_ca_list specified without " + "any certificate files") + + certs = [] + for ca_file in custom_ca_list: + logger.debug("Reading custom CA certificate file: %s", ca_file) + content = self.read_file(ca_file) + + # Parse the CA certificates + try: + cert_base = Certificate.loadPEM(content) + certs.append(cert_base) + except Exception as e: + raise ConfigError("Error parsing custom CA certificate file %s: %s" + % (ca_file, e)) + + self.federation_ca_trust_root = trustRootFromCertificates(certs) + # This config option applies to non-federation HTTP clients # (e.g. for talking to recaptcha, identity servers, and such) # It should never be used in production, and is intended for @@ -99,15 +148,15 @@ class TlsConfig(Config): try: with open(self.tls_certificate_file, 'rb') as f: cert_pem = f.read() - except Exception: - logger.exception("Failed to read existing certificate off disk!") - raise + except Exception as e: + raise ConfigError("Failed to read existing certificate file %s: %s" + % (self.tls_certificate_file, e)) try: tls_certificate = crypto.load_certificate(crypto.FILETYPE_PEM, cert_pem) - except Exception: - logger.exception("Failed to parse existing certificate off disk!") - raise + except Exception as e: + raise ConfigError("Failed to parse existing certificate file %s: %s" + % (self.tls_certificate_file, e)) if not allow_self_signed: if tls_certificate.get_subject() == tls_certificate.get_issuer(): @@ -192,6 +241,40 @@ class TlsConfig(Config): # #tls_private_key_path: "%(tls_private_key_path)s" + # Whether to verify TLS certificates when sending federation traffic. + # + # This currently defaults to `false`, however this will change in + # Synapse 1.0 when valid federation certificates will be required. + # + #federation_verify_certificates: true + + # Skip federation certificate verification on the following whitelist + # of domains. + # + # This setting should only be used in very specific cases, such as + # federation over Tor hidden services and similar. For private networks + # of homeservers, you likely want to use a private CA instead. + # + # Only effective if federation_verify_certicates is `true`. + # + #federation_certificate_verification_whitelist: + # - lon.example.com + # - *.domain.com + # - *.onion + + # List of custom certificate authorities for federation traffic. + # + # This setting should only normally be used within a private network of + # homeservers. + # + # Note that this list will replace those that are provided by your + # operating environment. Certificates must be in PEM format. + # + #federation_custom_ca_list: + # - myCA1.pem + # - myCA2.pem + # - myCA3.pem + # ACME support: This will configure Synapse to request a valid TLS certificate # for your configured `server_name` via Let's Encrypt. # diff --git a/synapse/crypto/context_factory.py b/synapse/crypto/context_factory.py index 49cbc7098f..59ea087e66 100644 --- a/synapse/crypto/context_factory.py +++ b/synapse/crypto/context_factory.py @@ -18,10 +18,10 @@ import logging from zope.interface import implementer from OpenSSL import SSL, crypto -from twisted.internet._sslverify import _defaultCurveName +from twisted.internet._sslverify import ClientTLSOptions, _defaultCurveName from twisted.internet.abstract import isIPAddress, isIPv6Address from twisted.internet.interfaces import IOpenSSLClientConnectionCreator -from twisted.internet.ssl import CertificateOptions, ContextFactory +from twisted.internet.ssl import CertificateOptions, ContextFactory, platformTrust from twisted.python.failure import Failure logger = logging.getLogger(__name__) @@ -90,7 +90,7 @@ def _tolerateErrors(wrapped): @implementer(IOpenSSLClientConnectionCreator) -class ClientTLSOptions(object): +class ClientTLSOptionsNoVerify(object): """ Client creator for TLS without certificate identity verification. This is a copy of twisted.internet._sslverify.ClientTLSOptions with the identity @@ -127,9 +127,30 @@ class ClientTLSOptionsFactory(object): to remote servers for federation.""" def __init__(self, config): - # We don't use config options yet - self._options = CertificateOptions(verify=False) + 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 + if trust_root is None: + # Use CA root certs provided by OpenSSL + trust_root = platformTrust() + + self._options_verify = CertificateOptions(trustRoot=trust_root) def get_options(self, host): # Use _makeContext so that we get a fresh OpenSSL CTX each time. - return ClientTLSOptions(host, self._options._makeContext()) + + # Check if certificate verification has been enabled + should_verify = self._config.federation_verify_certificates + + # Check if we've disabled certificate verification for this host + if should_verify: + for regex in self._config.federation_certificate_verification_whitelist: + if regex.match(host): + should_verify = False + break + + if should_verify: + return ClientTLSOptions(host, self._options_verify._makeContext()) + return ClientTLSOptionsNoVerify(host, self._options_noverify._makeContext()) diff --git a/synapse/http/federation/matrix_federation_agent.py b/synapse/http/federation/matrix_federation_agent.py index 1334c630cc..b4cbe97b41 100644 --- a/synapse/http/federation/matrix_federation_agent.py +++ b/synapse/http/federation/matrix_federation_agent.py @@ -149,7 +149,7 @@ class MatrixFederationAgent(object): tls_options = None else: tls_options = self._tls_client_options_factory.get_options( - res.tls_server_name.decode("ascii") + res.tls_server_name.decode("ascii"), ) # make sure that the Host header is set correctly -- cgit 1.4.1