diff --git a/synapse/config/tls.py b/synapse/config/tls.py
index 8fcf801418..ca508a224f 100644
--- a/synapse/config/tls.py
+++ b/synapse/config/tls.py
@@ -23,7 +23,7 @@ import six
from unpaddedbase64 import encode_base64
-from OpenSSL import crypto
+from OpenSSL import SSL, crypto
from twisted.internet._sslverify import Certificate, trustRootFromCertificates
from synapse.config._base import Config, ConfigError
@@ -81,6 +81,27 @@ class TlsConfig(Config):
"federation_verify_certificates", True
)
+ # Minimum TLS version to use for outbound federation traffic
+ self.federation_client_minimum_tls_version = str(
+ config.get("federation_client_minimum_tls_version", 1)
+ )
+
+ if self.federation_client_minimum_tls_version not in ["1", "1.1", "1.2", "1.3"]:
+ raise ConfigError(
+ "federation_client_minimum_tls_version must be one of: 1, 1.1, 1.2, 1.3"
+ )
+
+ # Prevent people shooting themselves in the foot here by setting it to
+ # the biggest number blindly
+ if self.federation_client_minimum_tls_version == "1.3":
+ if getattr(SSL, "OP_NO_TLSv1_3", None) is None:
+ raise ConfigError(
+ (
+ "federation_client_minimum_tls_version cannot be 1.3, "
+ "your OpenSSL does not support it"
+ )
+ )
+
# Whitelist of domains to not verify certificates for
fed_whitelist_entries = config.get(
"federation_certificate_verification_whitelist", []
@@ -261,6 +282,15 @@ class TlsConfig(Config):
#
#federation_verify_certificates: false
+ # The minimum TLS version that will be used for outbound federation requests.
+ #
+ # Defaults to `1`. Configurable to `1`, `1.1`, `1.2`, or `1.3`. Note
+ # that setting this value higher than `1.2` will prevent federation to most
+ # of the public Matrix network: only configure it to `1.3` if you have an
+ # entirely private federation setup and you can ensure TLS 1.3 support.
+ #
+ #federation_client_minimum_tls_version: 1.2
+
# Skip federation certificate verification on the following whitelist
# of domains.
#
diff --git a/synapse/crypto/context_factory.py b/synapse/crypto/context_factory.py
index 2bc5cc3807..4f48e8e88d 100644
--- a/synapse/crypto/context_factory.py
+++ b/synapse/crypto/context_factory.py
@@ -24,12 +24,25 @@ from OpenSSL import SSL, crypto
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
+from twisted.internet.ssl import (
+ CertificateOptions,
+ ContextFactory,
+ TLSVersion,
+ platformTrust,
+)
from twisted.python.failure import Failure
logger = logging.getLogger(__name__)
+_TLS_VERSION_MAP = {
+ "1": TLSVersion.TLSv1_0,
+ "1.1": TLSVersion.TLSv1_1,
+ "1.2": TLSVersion.TLSv1_2,
+ "1.3": TLSVersion.TLSv1_3,
+}
+
+
class ServerContextFactory(ContextFactory):
"""Factory for PyOpenSSL SSL contexts that are used to handle incoming
connections."""
@@ -43,16 +56,18 @@ class ServerContextFactory(ContextFactory):
try:
_ecCurve = crypto.get_elliptic_curve(_defaultCurveName)
context.set_tmp_ecdh(_ecCurve)
-
except Exception:
logger.exception("Failed to enable elliptic curve for TLS")
- context.set_options(SSL.OP_NO_SSLv2 | SSL.OP_NO_SSLv3)
+
+ context.set_options(
+ SSL.OP_NO_SSLv2 | SSL.OP_NO_SSLv3 | SSL.OP_NO_TLSv1 | SSL.OP_NO_TLSv1_1
+ )
context.use_certificate_chain_file(config.tls_certificate_file)
context.use_privatekey(config.tls_private_key)
# https://hynek.me/articles/hardening-your-web-servers-ssl-ciphers/
context.set_cipher_list(
- "ECDH+AESGCM:ECDH+CHACHA20:ECDH+AES256:ECDH+AES128:!aNULL:!SHA1"
+ "ECDH+AESGCM:ECDH+CHACHA20:ECDH+AES256:ECDH+AES128:!aNULL:!SHA1:!AESCCM"
)
def getContext(self):
@@ -79,10 +94,22 @@ class ClientTLSOptionsFactory(object):
# Use CA root certs provided by OpenSSL
trust_root = platformTrust()
- self._verify_ssl_context = CertificateOptions(trustRoot=trust_root).getContext()
+ # "insecurelyLowerMinimumTo" is the argument that will go lower than
+ # Twisted's default, which is why it is marked as "insecure" (since
+ # Twisted's defaults are reasonably secure). But, since Twisted is
+ # moving to TLS 1.2 by default, we want to respect the config option if
+ # it is set to 1.0 (which the alternate option, raiseMinimumTo, will not
+ # let us do).
+ minTLS = _TLS_VERSION_MAP[config.federation_client_minimum_tls_version]
+
+ self._verify_ssl = CertificateOptions(
+ trustRoot=trust_root, insecurelyLowerMinimumTo=minTLS
+ )
+ self._verify_ssl_context = self._verify_ssl.getContext()
self._verify_ssl_context.set_info_callback(self._context_info_cb)
- self._no_verify_ssl_context = CertificateOptions().getContext()
+ self._no_verify_ssl = CertificateOptions(insecurelyLowerMinimumTo=minTLS)
+ self._no_verify_ssl_context = self._no_verify_ssl.getContext()
self._no_verify_ssl_context.set_info_callback(self._context_info_cb)
def get_options(self, host):
|
