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Support ACME for certificate provisioning (#4384)

This commit is contained in:
Amber Brown 2019-01-23 19:39:06 +11:00 committed by GitHub
parent 12699a701f
commit 6129e52f43
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8 changed files with 301 additions and 39 deletions
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1
changelog.d/4384.feature Normal file
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@ -0,0 +1 @@
Synapse can now automatically provision TLS certificates via ACME (the protocol used by CAs like Let's Encrypt).

2
scripts-dev/build_debian_packages
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@ -10,12 +10,12 @@
# can be passed on the commandline for debugging.
import argparse
from concurrent.futures import ThreadPoolExecutor
import os
import signal
import subprocess
import sys
import threading
from concurrent.futures import ThreadPoolExecutor
DISTS = (
"debian:stretch",

56
synapse/app/homeserver.py
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@ -13,10 +13,12 @@
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import gc
import logging
import os
import sys
import traceback
from six import iteritems
@ -324,17 +326,12 @@ def setup(config_options):
events.USE_FROZEN_DICTS = config.use_frozen_dicts
tls_server_context_factory = context_factory.ServerContextFactory(config)
tls_client_options_factory = context_factory.ClientTLSOptionsFactory(config)
database_engine = create_engine(config.database_config)
config.database_config["args"]["cp_openfun"] = database_engine.on_new_connection
hs = SynapseHomeServer(
config.server_name,
db_config=config.database_config,
tls_server_context_factory=tls_server_context_factory,
tls_client_options_factory=tls_client_options_factory,
config=config,
version_string="Synapse/" + get_version_string(synapse),
database_engine=database_engine,
@ -361,12 +358,53 @@ def setup(config_options):
logger.info("Database prepared in %s.", config.database_config['name'])
hs.setup()
hs.start_listening()
@defer.inlineCallbacks
def start():
hs.get_pusherpool().start()
hs.get_datastore().start_profiling()
hs.get_datastore().start_doing_background_updates()
try:
# Check if the certificate is still valid.
cert_days_remaining = hs.config.is_disk_cert_valid()
if hs.config.acme_enabled:
# If ACME is enabled, we might need to provision a certificate
# before starting.
acme = hs.get_acme_handler()
# Start up the webservices which we will respond to ACME
# challenges with.
yield acme.start_listening()
# We want to reprovision if cert_days_remaining is None (meaning no
# certificate exists), or the days remaining number it returns
# is less than our re-registration threshold.
if (cert_days_remaining is None) or (
not cert_days_remaining > hs.config.acme_reprovision_threshold
):
yield acme.provision_certificate()
# Read the certificate from disk and build the context factories for
# TLS.
hs.config.read_certificate_from_disk()
hs.tls_server_context_factory = context_factory.ServerContextFactory(config)
hs.tls_client_options_factory = context_factory.ClientTLSOptionsFactory(
config
)
# It is now safe to start your Synapse.
hs.start_listening()
hs.get_pusherpool().start()
hs.get_datastore().start_profiling()
hs.get_datastore().start_doing_background_updates()
except Exception as e:
# If a DeferredList failed (like in listening on the ACME listener),
# we need to print the subfailure explicitly.
if isinstance(e, defer.FirstError):
e.subFailure.printTraceback(sys.stderr)
sys.exit(1)
# Something else went wrong when starting. Print it and bail out.
traceback.print_exc(file=sys.stderr)
sys.exit(1)
reactor.callWhenRunning(start)

4
synapse/config/_base.py
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@ -367,7 +367,7 @@ class Config(object):
if not keys_directory:
keys_directory = os.path.dirname(config_files[-1])
config_dir_path = os.path.abspath(keys_directory)
self.config_dir_path = os.path.abspath(keys_directory)
specified_config = {}
for config_file in config_files:
@ -379,7 +379,7 @@ class Config(object):
server_name = specified_config["server_name"]
config_string = self.generate_config(
config_dir_path=config_dir_path,
config_dir_path=self.config_dir_path,
data_dir_path=os.getcwd(),
server_name=server_name,
generate_secrets=False,

121
synapse/config/tls.py
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@ -13,45 +13,38 @@
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
import os
from datetime import datetime
from hashlib import sha256
from unpaddedbase64 import encode_base64
from OpenSSL import crypto
from ._base import Config
from synapse.config._base import Config
logger = logging.getLogger()
class TlsConfig(Config):
def read_config(self, config):
self.tls_certificate = self.read_tls_certificate(
config.get("tls_certificate_path")
)
self.tls_certificate_file = config.get("tls_certificate_path")
acme_config = config.get("acme", {})
self.acme_enabled = acme_config.get("enabled", False)
self.acme_url = acme_config.get(
"url", "https://acme-v01.api.letsencrypt.org/directory"
)
self.acme_port = acme_config.get("port", 8449)
self.acme_bind_addresses = acme_config.get("bind_addresses", ["127.0.0.1"])
self.acme_reprovision_threshold = acme_config.get("reprovision_threshold", 30)
self.tls_certificate_file = os.path.abspath(config.get("tls_certificate_path"))
self.tls_private_key_file = os.path.abspath(config.get("tls_private_key_path"))
self._original_tls_fingerprints = config["tls_fingerprints"]
self.tls_fingerprints = list(self._original_tls_fingerprints)
self.no_tls = config.get("no_tls", False)
if self.no_tls:
self.tls_private_key = None
else:
self.tls_private_key = self.read_tls_private_key(
config.get("tls_private_key_path")
)
self.tls_fingerprints = config["tls_fingerprints"]
# Check that our own certificate is included in the list of fingerprints
# and include it if it is not.
x509_certificate_bytes = crypto.dump_certificate(
crypto.FILETYPE_ASN1,
self.tls_certificate
)
sha256_fingerprint = encode_base64(sha256(x509_certificate_bytes).digest())
sha256_fingerprints = set(f["sha256"] for f in self.tls_fingerprints)
if sha256_fingerprint not in sha256_fingerprints:
self.tls_fingerprints.append({u"sha256": sha256_fingerprint})
# 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
@ -60,13 +53,70 @@ class TlsConfig(Config):
"use_insecure_ssl_client_just_for_testing_do_not_use"
)
self.tls_certificate = None
self.tls_private_key = None
def is_disk_cert_valid(self):
"""
Is the certificate we have on disk valid, and if so, for how long?
Returns:
int: Days remaining of certificate validity.
None: No certificate exists.
"""
if not os.path.exists(self.tls_certificate_file):
return None
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
try:
tls_certificate = crypto.load_certificate(crypto.FILETYPE_PEM, cert_pem)
except Exception:
logger.exception("Failed to parse existing certificate off disk!")
raise
# YYYYMMDDhhmmssZ -- in UTC
expires_on = datetime.strptime(
tls_certificate.get_notAfter().decode('ascii'), "%Y%m%d%H%M%SZ"
)
now = datetime.utcnow()
days_remaining = (expires_on - now).days
return days_remaining
def read_certificate_from_disk(self):
"""
Read the certificates from disk.
"""
self.tls_certificate = self.read_tls_certificate(self.tls_certificate_file)
if not self.no_tls:
self.tls_private_key = self.read_tls_private_key(self.tls_private_key_file)
self.tls_fingerprints = list(self._original_tls_fingerprints)
# Check that our own certificate is included in the list of fingerprints
# and include it if it is not.
x509_certificate_bytes = crypto.dump_certificate(
crypto.FILETYPE_ASN1, self.tls_certificate
)
sha256_fingerprint = encode_base64(sha256(x509_certificate_bytes).digest())
sha256_fingerprints = set(f["sha256"] for f in self.tls_fingerprints)
if sha256_fingerprint not in sha256_fingerprints:
self.tls_fingerprints.append({u"sha256": sha256_fingerprint})
def default_config(self, config_dir_path, server_name, **kwargs):
base_key_name = os.path.join(config_dir_path, server_name)
tls_certificate_path = base_key_name + ".tls.crt"
tls_private_key_path = base_key_name + ".tls.key"
return """\
return (
"""\
# PEM encoded X509 certificate for TLS.
# You can replace the self-signed certificate that synapse
# autogenerates on launch with your own SSL certificate + key pair
@ -107,7 +157,24 @@ class TlsConfig(Config):
#
tls_fingerprints: []
# tls_fingerprints: [{"sha256": "<base64_encoded_sha256_fingerprint>"}]
""" % locals()
## Support for ACME certificate auto-provisioning.
# acme:
# enabled: false
## ACME path.
## If you only want to test, use the staging url:
## https://acme-staging.api.letsencrypt.org/directory
# url: 'https://acme-v01.api.letsencrypt.org/directory'
## Port number (to listen for the HTTP-01 challenge).
## Using port 80 requires utilising something like authbind, or proxying to it.
# port: 8449
## Hosts to bind to.
# bind_addresses: ['127.0.0.1']
## How many days remaining on a certificate before it is renewed.
# reprovision_threshold: 30
"""
% locals()
)
def read_tls_certificate(self, cert_path):
cert_pem = self.read_file(cert_path, "tls_certificate")

147
synapse/handlers/acme.py Normal file
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@ -0,0 +1,147 @@
# -*- coding: utf-8 -*-
# Copyright 2019 New Vector Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
import attr
from zope.interface import implementer
from twisted.internet import defer
from twisted.internet.endpoints import serverFromString
from twisted.python.filepath import FilePath
from twisted.python.url import URL
from twisted.web import server, static
from twisted.web.resource import Resource
logger = logging.getLogger(__name__)
try:
from txacme.interfaces import ICertificateStore
@attr.s
@implementer(ICertificateStore)
class ErsatzStore(object):
"""
A store that only stores in memory.
"""
certs = attr.ib(default=attr.Factory(dict))
def store(self, server_name, pem_objects):
self.certs[server_name] = [o.as_bytes() for o in pem_objects]
return defer.succeed(None)
except ImportError:
# txacme is missing
pass
class AcmeHandler(object):
def __init__(self, hs):
self.hs = hs
self.reactor = hs.get_reactor()
@defer.inlineCallbacks
def start_listening(self):
# Configure logging for txacme, if you need to debug
# from eliot import add_destinations
# from eliot.twisted import TwistedDestination
#
# add_destinations(TwistedDestination())
from txacme.challenges import HTTP01Responder
from txacme.service import AcmeIssuingService
from txacme.endpoint import load_or_create_client_key
from txacme.client import Client
from josepy.jwa import RS256
self._store = ErsatzStore()
responder = HTTP01Responder()
self._issuer = AcmeIssuingService(
cert_store=self._store,
client_creator=(
lambda: Client.from_url(
reactor=self.reactor,
url=URL.from_text(self.hs.config.acme_url),
key=load_or_create_client_key(
FilePath(self.hs.config.config_dir_path)
),
alg=RS256,
)
),
clock=self.reactor,
responders=[responder],
)
well_known = Resource()
well_known.putChild(b'acme-challenge', responder.resource)
responder_resource = Resource()
responder_resource.putChild(b'.well-known', well_known)
responder_resource.putChild(b'check', static.Data(b'OK', b'text/plain'))
srv = server.Site(responder_resource)
listeners = []
for host in self.hs.config.acme_bind_addresses:
logger.info(
"Listening for ACME requests on %s:%s", host, self.hs.config.acme_port
)
endpoint = serverFromString(
self.reactor, "tcp:%s:interface=%s" % (self.hs.config.acme_port, host)
)
listeners.append(endpoint.listen(srv))
# Make sure we are registered to the ACME server. There's no public API
# for this, it is usually triggered by startService, but since we don't
# want it to control where we save the certificates, we have to reach in
# and trigger the registration machinery ourselves.
self._issuer._registered = False
yield self._issuer._ensure_registered()
# Return a Deferred that will fire when all the servers have started up.
yield defer.DeferredList(listeners, fireOnOneErrback=True, consumeErrors=True)
@defer.inlineCallbacks
def provision_certificate(self):
logger.warning("Reprovisioning %s", self.hs.hostname)
try:
yield self._issuer.issue_cert(self.hs.hostname)
except Exception:
logger.exception("Fail!")
raise
logger.warning("Reprovisioned %s, saving.", self.hs.hostname)
cert_chain = self._store.certs[self.hs.hostname]
try:
with open(self.hs.config.tls_private_key_file, "wb") as private_key_file:
for x in cert_chain:
if x.startswith(b"-----BEGIN RSA PRIVATE KEY-----"):
private_key_file.write(x)
with open(self.hs.config.tls_certificate_file, "wb") as certificate_file:
for x in cert_chain:
if x.startswith(b"-----BEGIN CERTIFICATE-----"):
certificate_file.write(x)
except Exception:
logger.exception("Failed saving!")
raise
defer.returnValue(True)

4
synapse/python_dependencies.py
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@ -79,6 +79,10 @@ CONDITIONAL_REQUIREMENTS = {
# ConsentResource uses select_autoescape, which arrived in jinja 2.9
"resources.consent": ["Jinja2>=2.9"],
# ACME support is required to provision TLS certificates from authorities
# that use the protocol, such as Let's Encrypt.
"acme": ["txacme>=0.9.2"],
"saml2": ["pysaml2>=4.5.0"],
"url_preview": ["lxml>=3.5.0"],
"test": ["mock>=2.0"],

5
synapse/server.py
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@ -46,6 +46,7 @@ from synapse.federation.transport.client import TransportLayerClient
from synapse.groups.attestations import GroupAttestationSigning, GroupAttestionRenewer
from synapse.groups.groups_server import GroupsServerHandler
from synapse.handlers import Handlers
from synapse.handlers.acme import AcmeHandler
from synapse.handlers.appservice import ApplicationServicesHandler
from synapse.handlers.auth import AuthHandler, MacaroonGenerator
from synapse.handlers.deactivate_account import DeactivateAccountHandler
@ -129,6 +130,7 @@ class HomeServer(object):
'sync_handler',
'typing_handler',
'room_list_handler',
'acme_handler',
'auth_handler',
'device_handler',
'e2e_keys_handler',
@ -310,6 +312,9 @@ class HomeServer(object):
def build_e2e_room_keys_handler(self):
return E2eRoomKeysHandler(self)
def build_acme_handler(self):
return AcmeHandler(self)
def build_application_service_api(self):
return ApplicationServiceApi(self)