Reject invalid server names (#3480)

Make sure that server_names used in auth headers are sane, and reject them with
a sensible error code, before they disappear off into the depths of the system.
This commit is contained in:
Richard van der Hoff 2018-07-03 14:36:14 +01:00 committed by GitHub
parent f741630847
commit 508196e08a
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5 changed files with 122 additions and 25 deletions

1
changelog.d/3480.feature Normal file
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@ -0,0 +1 @@
Reject invalid server names in federation requests

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@ -18,6 +18,7 @@ from twisted.internet import defer
from synapse.api.urls import FEDERATION_PREFIX as PREFIX
from synapse.api.errors import Codes, SynapseError, FederationDeniedError
from synapse.http.endpoint import parse_server_name
from synapse.http.server import JsonResource
from synapse.http.servlet import (
parse_json_object_from_request, parse_integer_from_args, parse_string_from_args,
@ -99,26 +100,6 @@ class Authenticator(object):
origin = None
def parse_auth_header(header_str):
try:
params = auth.split(" ")[1].split(",")
param_dict = dict(kv.split("=") for kv in params)
def strip_quotes(value):
if value.startswith("\""):
return value[1:-1]
else:
return value
origin = strip_quotes(param_dict["origin"])
key = strip_quotes(param_dict["key"])
sig = strip_quotes(param_dict["sig"])
return (origin, key, sig)
except Exception:
raise AuthenticationError(
400, "Malformed Authorization header", Codes.UNAUTHORIZED
)
auth_headers = request.requestHeaders.getRawHeaders(b"Authorization")
if not auth_headers:
@ -127,8 +108,8 @@ class Authenticator(object):
)
for auth in auth_headers:
if auth.startswith("X-Matrix"):
(origin, key, sig) = parse_auth_header(auth)
if auth.startswith(b"X-Matrix"):
(origin, key, sig) = _parse_auth_header(auth)
json_request["origin"] = origin
json_request["signatures"].setdefault(origin, {})[key] = sig
@ -165,6 +146,47 @@ class Authenticator(object):
logger.exception("Error resetting retry timings on %s", origin)
def _parse_auth_header(header_bytes):
"""Parse an X-Matrix auth header
Args:
header_bytes (bytes): header value
Returns:
Tuple[str, str, str]: origin, key id, signature.
Raises:
AuthenticationError if the header could not be parsed
"""
try:
header_str = header_bytes.decode('utf-8')
params = header_str.split(" ")[1].split(",")
param_dict = dict(kv.split("=") for kv in params)
def strip_quotes(value):
if value.startswith(b"\""):
return value[1:-1]
else:
return value
origin = strip_quotes(param_dict["origin"])
# ensure that the origin is a valid server name
parse_server_name(origin)
key = strip_quotes(param_dict["key"])
sig = strip_quotes(param_dict["sig"])
return origin, key, sig
except Exception as e:
logger.warn(
"Error parsing auth header '%s': %s",
header_bytes.decode('ascii', 'replace'),
e,
)
raise AuthenticationError(
400, "Malformed Authorization header", Codes.UNAUTHORIZED,
)
class BaseFederationServlet(object):
REQUIRE_AUTH = True

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@ -38,6 +38,36 @@ _Server = collections.namedtuple(
)
def parse_server_name(server_name):
"""Split a server name into host/port parts.
Does some basic sanity checking of the
Args:
server_name (str): server name to parse
Returns:
Tuple[str, int|None]: host/port parts.
Raises:
ValueError if the server name could not be parsed.
"""
try:
if server_name[-1] == ']':
# ipv6 literal, hopefully
if server_name[0] != '[':
raise Exception()
return server_name, None
domain_port = server_name.rsplit(":", 1)
domain = domain_port[0]
port = int(domain_port[1]) if domain_port[1:] else None
return domain, port
except Exception:
raise ValueError("Invalid server name '%s'" % server_name)
def matrix_federation_endpoint(reactor, destination, ssl_context_factory=None,
timeout=None):
"""Construct an endpoint for the given matrix destination.
@ -50,9 +80,7 @@ def matrix_federation_endpoint(reactor, destination, ssl_context_factory=None,
timeout (int): connection timeout in seconds
"""
domain_port = destination.split(":")
domain = domain_port[0]
port = int(domain_port[1]) if domain_port[1:] else None
domain, port = parse_server_name(destination)
endpoint_kw_args = {}

0
tests/http/__init__.py Normal file
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@ -0,0 +1,46 @@
# -*- coding: utf-8 -*-
# Copyright 2018 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.
from synapse.http.endpoint import parse_server_name
from tests import unittest
class ServerNameTestCase(unittest.TestCase):
def test_parse_server_name(self):
test_data = {
'localhost': ('localhost', None),
'my-example.com:1234': ('my-example.com', 1234),
'1.2.3.4': ('1.2.3.4', None),
'[0abc:1def::1234]': ('[0abc:1def::1234]', None),
'1.2.3.4:1': ('1.2.3.4', 1),
'[0abc:1def::1234]:8080': ('[0abc:1def::1234]', 8080),
}
for i, o in test_data.items():
self.assertEqual(parse_server_name(i), o)
def test_parse_bad_server_names(self):
test_data = [
"", # empty
"localhost:http", # non-numeric port
"1234]", # smells like ipv6 literal but isn't
]
for i in test_data:
try:
parse_server_name(i)
self.fail(
"Expected parse_server_name(\"%s\") to throw" % i,
)
except ValueError:
pass