diff options
Diffstat (limited to '')
| -rw-r--r-- | synapse/http/client.py | 377 | ||||
| -rw-r--r-- | synapse/http/endpoint.py | 35 | ||||
| -rw-r--r-- | synapse/rest/media/v1/preview_url_resource.py | 14 |
3 files changed, 255 insertions, 171 deletions
diff --git a/synapse/http/client.py b/synapse/http/client.py index 3d05f83b8c..afcf698b29 100644 --- a/synapse/http/client.py +++ b/synapse/http/client.py @@ -21,28 +21,25 @@ from six.moves import urllib import treq from canonicaljson import encode_canonical_json, json +from netaddr import IPAddress from prometheus_client import Counter +from zope.interface import implementer, provider from OpenSSL import SSL from OpenSSL.SSL import VERIFY_NONE -from twisted.internet import defer, protocol, reactor, ssl -from twisted.internet.endpoints import HostnameEndpoint, wrapClientTLS -from twisted.web._newclient import ResponseDone -from twisted.web.client import ( - Agent, - BrowserLikeRedirectAgent, - ContentDecoderAgent, - GzipDecoder, - HTTPConnectionPool, - PartialDownloadError, - readBody, +from twisted.internet import defer, protocol, ssl +from twisted.internet.interfaces import ( + IReactorPluggableNameResolver, + IResolutionReceiver, ) +from twisted.python.failure import Failure +from twisted.web._newclient import ResponseDone +from twisted.web.client import Agent, HTTPConnectionPool, PartialDownloadError, readBody from twisted.web.http import PotentialDataLoss from twisted.web.http_headers import Headers from synapse.api.errors import Codes, HttpResponseException, SynapseError from synapse.http import cancelled_to_request_timed_out_error, redact_uri -from synapse.http.endpoint import SpiderEndpoint from synapse.util.async_helpers import timeout_deferred from synapse.util.caches import CACHE_SIZE_FACTOR from synapse.util.logcontext import make_deferred_yieldable @@ -50,8 +47,125 @@ from synapse.util.logcontext import make_deferred_yieldable logger = logging.getLogger(__name__) outgoing_requests_counter = Counter("synapse_http_client_requests", "", ["method"]) -incoming_responses_counter = Counter("synapse_http_client_responses", "", - ["method", "code"]) +incoming_responses_counter = Counter( + "synapse_http_client_responses", "", ["method", "code"] +) + + +def check_against_blacklist(ip_address, ip_whitelist, ip_blacklist): + """ + Args: + ip_address (netaddr.IPAddress) + ip_whitelist (netaddr.IPSet) + ip_blacklist (netaddr.IPSet) + """ + if ip_address in ip_blacklist: + if ip_whitelist is None or ip_address not in ip_whitelist: + return True + return False + + +class IPBlacklistingResolver(object): + """ + A proxy for reactor.nameResolver which only produces non-blacklisted IP + addresses, preventing DNS rebinding attacks on URL preview. + """ + + def __init__(self, reactor, ip_whitelist, ip_blacklist): + """ + Args: + reactor (twisted.internet.reactor) + ip_whitelist (netaddr.IPSet) + ip_blacklist (netaddr.IPSet) + """ + self._reactor = reactor + self._ip_whitelist = ip_whitelist + self._ip_blacklist = ip_blacklist + + def resolveHostName(self, recv, hostname, portNumber=0): + + r = recv() + d = defer.Deferred() + addresses = [] + + @provider(IResolutionReceiver) + class EndpointReceiver(object): + @staticmethod + def resolutionBegan(resolutionInProgress): + pass + + @staticmethod + def addressResolved(address): + ip_address = IPAddress(address.host) + + if check_against_blacklist( + ip_address, self._ip_whitelist, self._ip_blacklist + ): + logger.info( + "Dropped %s from DNS resolution to %s" % (ip_address, hostname) + ) + raise SynapseError(403, "IP address blocked by IP blacklist entry") + + addresses.append(address) + + @staticmethod + def resolutionComplete(): + d.callback(addresses) + + self._reactor.nameResolver.resolveHostName( + EndpointReceiver, hostname, portNumber=portNumber + ) + + def _callback(addrs): + r.resolutionBegan(None) + for i in addrs: + r.addressResolved(i) + r.resolutionComplete() + + d.addCallback(_callback) + + return r + + +class BlacklistingAgentWrapper(Agent): + """ + An Agent wrapper which will prevent access to IP addresses being accessed + directly (without an IP address lookup). + """ + + def __init__(self, agent, reactor, ip_whitelist=None, ip_blacklist=None): + """ + Args: + agent (twisted.web.client.Agent): The Agent to wrap. + reactor (twisted.internet.reactor) + ip_whitelist (netaddr.IPSet) + ip_blacklist (netaddr.IPSet) + """ + self._agent = agent + self._ip_whitelist = ip_whitelist + self._ip_blacklist = ip_blacklist + + def request(self, method, uri, headers=None, bodyProducer=None): + h = urllib.parse.urlparse(uri.decode('ascii')) + + try: + ip_address = IPAddress(h.hostname) + + if check_against_blacklist( + ip_address, self._ip_whitelist, self._ip_blacklist + ): + logger.info( + "Blocking access to %s because of blacklist" % (ip_address,) + ) + e = SynapseError(403, "IP address blocked by IP blacklist entry") + return defer.fail(Failure(e)) + except Exception: + # Not an IP + pass + + return self._agent.request( + method, uri, headers=headers, bodyProducer=bodyProducer + ) class SimpleHttpClient(object): @@ -59,14 +173,54 @@ class SimpleHttpClient(object): A simple, no-frills HTTP client with methods that wrap up common ways of using HTTP in Matrix """ - def __init__(self, hs): + + def __init__(self, hs, treq_args={}, ip_whitelist=None, ip_blacklist=None): + """ + Args: + hs (synapse.server.HomeServer) + treq_args (dict): Extra keyword arguments to be given to treq.request. + ip_blacklist (netaddr.IPSet): The IP addresses that are blacklisted that + we may not request. + ip_whitelist (netaddr.IPSet): The whitelisted IP addresses, that we can + request if it were otherwise caught in a blacklist. + """ self.hs = hs - pool = HTTPConnectionPool(reactor) + self._ip_whitelist = ip_whitelist + self._ip_blacklist = ip_blacklist + self._extra_treq_args = treq_args + + self.user_agent = hs.version_string + self.clock = hs.get_clock() + if hs.config.user_agent_suffix: + self.user_agent = "%s %s" % (self.user_agent, hs.config.user_agent_suffix) + + self.user_agent = self.user_agent.encode('ascii') + + if self._ip_blacklist: + real_reactor = hs.get_reactor() + # If we have an IP blacklist, we need to use a DNS resolver which + # filters out blacklisted IP addresses, to prevent DNS rebinding. + nameResolver = IPBlacklistingResolver( + real_reactor, self._ip_whitelist, self._ip_blacklist + ) + + @implementer(IReactorPluggableNameResolver) + class Reactor(object): + def __getattr__(_self, attr): + if attr == "nameResolver": + return nameResolver + else: + return getattr(real_reactor, attr) + + self.reactor = Reactor() + else: + self.reactor = hs.get_reactor() # the pusher makes lots of concurrent SSL connections to sygnal, and - # tends to do so in batches, so we need to allow the pool to keep lots - # of idle connections around. + # tends to do so in batches, so we need to allow the pool to keep + # lots of idle connections around. + pool = HTTPConnectionPool(self.reactor) pool.maxPersistentPerHost = max((100 * CACHE_SIZE_FACTOR, 5)) pool.cachedConnectionTimeout = 2 * 60 @@ -74,20 +228,35 @@ class SimpleHttpClient(object): # BrowserLikePolicyForHTTPS which will do regular cert validation # 'like a browser' self.agent = Agent( - reactor, + self.reactor, connectTimeout=15, - contextFactory=hs.get_http_client_context_factory(), + contextFactory=self.hs.get_http_client_context_factory(), pool=pool, ) - self.user_agent = hs.version_string - self.clock = hs.get_clock() - if hs.config.user_agent_suffix: - self.user_agent = "%s %s" % (self.user_agent, hs.config.user_agent_suffix,) - self.user_agent = self.user_agent.encode('ascii') + if self._ip_blacklist: + # If we have an IP blacklist, we then install the blacklisting Agent + # which prevents direct access to IP addresses, that are not caught + # by the DNS resolution. + self.agent = BlacklistingAgentWrapper( + self.agent, + self.reactor, + ip_whitelist=self._ip_whitelist, + ip_blacklist=self._ip_blacklist, + ) @defer.inlineCallbacks def request(self, method, uri, data=b'', headers=None): + """ + Args: + method (str): HTTP method to use. + uri (str): URI to query. + data (bytes): Data to send in the request body, if applicable. + headers (t.w.http_headers.Headers): Request headers. + + Raises: + SynapseError: If the IP is blacklisted. + """ # A small wrapper around self.agent.request() so we can easily attach # counters to it outgoing_requests_counter.labels(method).inc() @@ -97,25 +266,34 @@ class SimpleHttpClient(object): try: request_deferred = treq.request( - method, uri, agent=self.agent, data=data, headers=headers + method, + uri, + agent=self.agent, + data=data, + headers=headers, + **self._extra_treq_args ) request_deferred = timeout_deferred( - request_deferred, 60, self.hs.get_reactor(), + request_deferred, + 60, + self.hs.get_reactor(), cancelled_to_request_timed_out_error, ) response = yield make_deferred_yieldable(request_deferred) incoming_responses_counter.labels(method, response.code).inc() logger.info( - "Received response to %s %s: %s", - method, redact_uri(uri), response.code + "Received response to %s %s: %s", method, redact_uri(uri), response.code ) defer.returnValue(response) except Exception as e: incoming_responses_counter.labels(method, "ERR").inc() logger.info( "Error sending request to %s %s: %s %s", - method, redact_uri(uri), type(e).__name__, e.args[0] + method, + redact_uri(uri), + type(e).__name__, + e.args[0], ) raise @@ -140,8 +318,9 @@ class SimpleHttpClient(object): # TODO: Do we ever want to log message contents? logger.debug("post_urlencoded_get_json args: %s", args) - query_bytes = urllib.parse.urlencode( - encode_urlencode_args(args), True).encode("utf8") + query_bytes = urllib.parse.urlencode(encode_urlencode_args(args), True).encode( + "utf8" + ) actual_headers = { b"Content-Type": [b"application/x-www-form-urlencoded"], @@ -151,10 +330,7 @@ class SimpleHttpClient(object): actual_headers.update(headers) response = yield self.request( - "POST", - uri, - headers=Headers(actual_headers), - data=query_bytes + "POST", uri, headers=Headers(actual_headers), data=query_bytes ) if 200 <= response.code < 300: @@ -193,10 +369,7 @@ class SimpleHttpClient(object): actual_headers.update(headers) response = yield self.request( - "POST", - uri, - headers=Headers(actual_headers), - data=json_str + "POST", uri, headers=Headers(actual_headers), data=json_str ) body = yield make_deferred_yieldable(readBody(response)) @@ -264,10 +437,7 @@ class SimpleHttpClient(object): actual_headers.update(headers) response = yield self.request( - "PUT", - uri, - headers=Headers(actual_headers), - data=json_str + "PUT", uri, headers=Headers(actual_headers), data=json_str ) body = yield make_deferred_yieldable(readBody(response)) @@ -299,17 +469,11 @@ class SimpleHttpClient(object): query_bytes = urllib.parse.urlencode(args, True) uri = "%s?%s" % (uri, query_bytes) - actual_headers = { - b"User-Agent": [self.user_agent], - } + actual_headers = {b"User-Agent": [self.user_agent]} if headers: actual_headers.update(headers) - response = yield self.request( - "GET", - uri, - headers=Headers(actual_headers), - ) + response = yield self.request("GET", uri, headers=Headers(actual_headers)) body = yield make_deferred_yieldable(readBody(response)) @@ -334,22 +498,18 @@ class SimpleHttpClient(object): headers, absolute URI of the response and HTTP response code. """ - actual_headers = { - b"User-Agent": [self.user_agent], - } + actual_headers = {b"User-Agent": [self.user_agent]} if headers: actual_headers.update(headers) - response = yield self.request( - "GET", - url, - headers=Headers(actual_headers), - ) + response = yield self.request("GET", url, headers=Headers(actual_headers)) resp_headers = dict(response.headers.getAllRawHeaders()) - if (b'Content-Length' in resp_headers and - int(resp_headers[b'Content-Length']) > max_size): + if ( + b'Content-Length' in resp_headers + and int(resp_headers[b'Content-Length'][0]) > max_size + ): logger.warn("Requested URL is too large > %r bytes" % (self.max_size,)) raise SynapseError( 502, @@ -359,26 +519,20 @@ class SimpleHttpClient(object): if response.code > 299: logger.warn("Got %d when downloading %s" % (response.code, url)) - raise SynapseError( - 502, - "Got error %d" % (response.code,), - Codes.UNKNOWN, - ) + raise SynapseError(502, "Got error %d" % (response.code,), Codes.UNKNOWN) # TODO: if our Content-Type is HTML or something, just read the first # N bytes into RAM rather than saving it all to disk only to read it # straight back in again try: - length = yield make_deferred_yieldable(_readBodyToFile( - response, output_stream, max_size, - )) + length = yield make_deferred_yieldable( + _readBodyToFile(response, output_stream, max_size) + ) except Exception as e: logger.exception("Failed to download body") raise SynapseError( - 502, - ("Failed to download remote body: %s" % e), - Codes.UNKNOWN, + 502, ("Failed to download remote body: %s" % e), Codes.UNKNOWN ) defer.returnValue( @@ -387,13 +541,14 @@ class SimpleHttpClient(object): resp_headers, response.request.absoluteURI.decode('ascii'), response.code, - ), + ) ) # XXX: FIXME: This is horribly copy-pasted from matrixfederationclient. # The two should be factored out. + class _ReadBodyToFileProtocol(protocol.Protocol): def __init__(self, stream, deferred, max_size): self.stream = stream @@ -405,11 +560,13 @@ class _ReadBodyToFileProtocol(protocol.Protocol): self.stream.write(data) self.length += len(data) if self.max_size is not None and self.length >= self.max_size: - self.deferred.errback(SynapseError( - 502, - "Requested file is too large > %r bytes" % (self.max_size,), - Codes.TOO_LARGE, - )) + self.deferred.errback( + SynapseError( + 502, + "Requested file is too large > %r bytes" % (self.max_size,), + Codes.TOO_LARGE, + ) + ) self.deferred = defer.Deferred() self.transport.loseConnection() @@ -427,6 +584,7 @@ class _ReadBodyToFileProtocol(protocol.Protocol): # XXX: FIXME: This is horribly copy-pasted from matrixfederationclient. # The two should be factored out. + def _readBodyToFile(response, stream, max_size): d = defer.Deferred() response.deliverBody(_ReadBodyToFileProtocol(stream, d, max_size)) @@ -449,10 +607,12 @@ class CaptchaServerHttpClient(SimpleHttpClient): "POST", url, data=query_bytes, - headers=Headers({ - b"Content-Type": [b"application/x-www-form-urlencoded"], - b"User-Agent": [self.user_agent], - }) + headers=Headers( + { + b"Content-Type": [b"application/x-www-form-urlencoded"], + b"User-Agent": [self.user_agent], + } + ), ) try: @@ -463,57 +623,6 @@ class CaptchaServerHttpClient(SimpleHttpClient): defer.returnValue(e.response) -class SpiderEndpointFactory(object): - def __init__(self, hs): - self.blacklist = hs.config.url_preview_ip_range_blacklist - self.whitelist = hs.config.url_preview_ip_range_whitelist - self.policyForHTTPS = hs.get_http_client_context_factory() - - def endpointForURI(self, uri): - logger.info("Getting endpoint for %s", uri.toBytes()) - - if uri.scheme == b"http": - endpoint_factory = HostnameEndpoint - elif uri.scheme == b"https": - tlsCreator = self.policyForHTTPS.creatorForNetloc(uri.host, uri.port) - - def endpoint_factory(reactor, host, port, **kw): - return wrapClientTLS( - tlsCreator, - HostnameEndpoint(reactor, host, port, **kw)) - else: - logger.warn("Can't get endpoint for unrecognised scheme %s", uri.scheme) - return None - return SpiderEndpoint( - reactor, uri.host, uri.port, self.blacklist, self.whitelist, - endpoint=endpoint_factory, endpoint_kw_args=dict(timeout=15), - ) - - -class SpiderHttpClient(SimpleHttpClient): - """ - Separate HTTP client for spidering arbitrary URLs. - Special in that it follows retries and has a UA that looks - like a browser. - - used by the preview_url endpoint in the content repo. - """ - def __init__(self, hs): - SimpleHttpClient.__init__(self, hs) - # clobber the base class's agent and UA: - self.agent = ContentDecoderAgent( - BrowserLikeRedirectAgent( - Agent.usingEndpointFactory( - reactor, - SpiderEndpointFactory(hs) - ) - ), [(b'gzip', GzipDecoder)] - ) - # We could look like Chrome: - # self.user_agent = ("Mozilla/5.0 (%s) (KHTML, like Gecko) - # Chrome Safari" % hs.version_string) - - def encode_urlencode_args(args): return {k: encode_urlencode_arg(v) for k, v in args.items()} diff --git a/synapse/http/endpoint.py b/synapse/http/endpoint.py index 91025037a3..f86a0b624e 100644 --- a/synapse/http/endpoint.py +++ b/synapse/http/endpoint.py @@ -218,41 +218,6 @@ class _WrappedConnection(object): return d -class SpiderEndpoint(object): - """An endpoint which refuses to connect to blacklisted IP addresses - Implements twisted.internet.interfaces.IStreamClientEndpoint. - """ - def __init__(self, reactor, host, port, blacklist, whitelist, - endpoint=HostnameEndpoint, endpoint_kw_args={}): - self.reactor = reactor - self.host = host - self.port = port - self.blacklist = blacklist - self.whitelist = whitelist - self.endpoint = endpoint - self.endpoint_kw_args = endpoint_kw_args - - @defer.inlineCallbacks - def connect(self, protocolFactory): - address = yield self.reactor.resolve(self.host) - - from netaddr import IPAddress - ip_address = IPAddress(address) - - if ip_address in self.blacklist: - if self.whitelist is None or ip_address not in self.whitelist: - raise ConnectError( - "Refusing to spider blacklisted IP address %s" % address - ) - - logger.info("Connecting to %s:%s", address, self.port) - endpoint = self.endpoint( - self.reactor, address, self.port, **self.endpoint_kw_args - ) - connection = yield endpoint.connect(protocolFactory) - defer.returnValue(connection) - - class SRVClientEndpoint(object): """An endpoint which looks up SRV records for a service. Cycles through the list of servers starting with each call to connect diff --git a/synapse/rest/media/v1/preview_url_resource.py b/synapse/rest/media/v1/preview_url_resource.py index d0ecf241b6..ba3ab1d37d 100644 --- a/synapse/rest/media/v1/preview_url_resource.py +++ b/synapse/rest/media/v1/preview_url_resource.py @@ -35,7 +35,7 @@ from twisted.web.resource import Resource from twisted.web.server import NOT_DONE_YET from synapse.api.errors import Codes, SynapseError -from synapse.http.client import SpiderHttpClient +from synapse.http.client import SimpleHttpClient from synapse.http.server import ( respond_with_json, respond_with_json_bytes, @@ -69,7 +69,12 @@ class PreviewUrlResource(Resource): self.max_spider_size = hs.config.max_spider_size self.server_name = hs.hostname self.store = hs.get_datastore() - self.client = SpiderHttpClient(hs) + self.client = SimpleHttpClient( + hs, + treq_args={"browser_like_redirects": True}, + ip_whitelist=hs.config.url_preview_ip_range_whitelist, + ip_blacklist=hs.config.url_preview_ip_range_blacklist, + ) self.media_repo = media_repo self.primary_base_path = media_repo.primary_base_path self.media_storage = media_storage @@ -318,6 +323,11 @@ class PreviewUrlResource(Resource): length, headers, uri, code = yield self.client.get_file( url, output_stream=f, max_size=self.max_spider_size, ) + except SynapseError: + # Pass SynapseErrors through directly, so that the servlet + # handler will return a SynapseError to the client instead of + # blank data or a 500. + raise except Exception as e: # FIXME: pass through 404s and other error messages nicely logger.warn("Error downloading %s: %r", url, e) |