Rip out half-implemented m.login.saml2 support (#4265)

* Rip out half-implemented m.login.saml2 support

This was implemented in an odd way that left most of the work to the client, in
a way that I really didn't understand. It's going to be a pain to maintain, so
let's start by ripping it out.

* drop undocumented dependency on dateutil

It turns out we were relying on dateutil being pulled in transitively by
pysaml2. There's no need for that bloat.

7 files changed, 4 insertions, 169 deletions

diff --git a/changelog.d/4265.feature b/changelog.d/4265.feature
new file mode 100644
index 0000000000..da36986e2b
--- /dev/null
+++ b/changelog.d/4265.feature
@@ -0,0 +1 @@
+Rework SAML2 authentication
diff --git a/synapse/config/homeserver.py b/synapse/config/homeserver.py
index 10dd40159f..36182267c2 100644
--- a/synapse/config/homeserver.py
+++ b/synapse/config/homeserver.py
@@ -32,7 +32,6 @@ from .ratelimiting import RatelimitConfig
 from .registration import RegistrationConfig
 from .repository import ContentRepositoryConfig
 from .room_directory import RoomDirectoryConfig
-from .saml2 import SAML2Config
 from .server import ServerConfig
 from .server_notices_config import ServerNoticesConfig
 from .spam_checker import SpamCheckerConfig
@@ -45,7 +44,7 @@ from .workers import WorkerConfig
 class HomeServerConfig(TlsConfig, ServerConfig, DatabaseConfig, LoggingConfig,
                        RatelimitConfig, ContentRepositoryConfig, CaptchaConfig,
                        VoipConfig, RegistrationConfig, MetricsConfig, ApiConfig,
-                       AppServiceConfig, KeyConfig, SAML2Config, CasConfig,
+                       AppServiceConfig, KeyConfig, CasConfig,
                        JWTConfig, PasswordConfig, EmailConfig,
                        WorkerConfig, PasswordAuthProviderConfig, PushConfig,
                        SpamCheckerConfig, GroupsConfig, UserDirectoryConfig,
diff --git a/synapse/config/saml2.py b/synapse/config/saml2.py
deleted file mode 100644
index 8d7f443021..0000000000
--- a/synapse/config/saml2.py
+++ /dev/null
@@ -1,55 +0,0 @@
-# -*- coding: utf-8 -*-
-# Copyright 2015 Ericsson
-#
-# 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 ._base import Config
-
-
-class SAML2Config(Config):
-    """SAML2 Configuration
-    Synapse uses pysaml2 libraries for providing SAML2 support
-
-    config_path:      Path to the sp_conf.py configuration file
-    idp_redirect_url: Identity provider URL which will redirect
-                      the user back to /login/saml2 with proper info.
-
-    sp_conf.py file is something like:
-    https://github.com/rohe/pysaml2/blob/master/example/sp-repoze/sp_conf.py.example
-
-    More information: https://pythonhosted.org/pysaml2/howto/config.html
-    """
-
-    def read_config(self, config):
-        saml2_config = config.get("saml2_config", None)
-        if saml2_config:
-            self.saml2_enabled = saml2_config.get("enabled", True)
-            self.saml2_config_path = saml2_config["config_path"]
-            self.saml2_idp_redirect_url = saml2_config["idp_redirect_url"]
-        else:
-            self.saml2_enabled = False
-            self.saml2_config_path = None
-            self.saml2_idp_redirect_url = None
-
-    def default_config(self, config_dir_path, server_name, **kwargs):
-        return """
-        # Enable SAML2 for registration and login. Uses pysaml2
-        # config_path:      Path to the sp_conf.py configuration file
-        # idp_redirect_url: Identity provider URL which will redirect
-        #                   the user back to /login/saml2 with proper info.
-        # See pysaml2 docs for format of config.
-        #saml2_config:
-        #   enabled: true
-        #   config_path: "%s/sp_conf.py"
-        #   idp_redirect_url: "http://%s/idp"
-        """ % (config_dir_path, server_name)
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index 015909bb26..0f87c4610e 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -328,35 +328,6 @@ class RegistrationHandler(BaseHandler):
             logger.info("Valid captcha entered from %s", ip)
 
     @defer.inlineCallbacks
-    def register_saml2(self, localpart):
-        """
-        Registers email_id as SAML2 Based Auth.
-        """
-        if types.contains_invalid_mxid_characters(localpart):
-            raise SynapseError(
-                400,
-                "User ID can only contain characters a-z, 0-9, or '=_-./'",
-            )
-        yield self.auth.check_auth_blocking()
-        user = UserID(localpart, self.hs.hostname)
-        user_id = user.to_string()
-
-        yield self.check_user_id_not_appservice_exclusive(user_id)
-        token = self.macaroon_gen.generate_access_token(user_id)
-        try:
-            yield self.store.register(
-                user_id=user_id,
-                token=token,
-                password_hash=None,
-                create_profile_with_localpart=user.localpart,
-            )
-        except Exception as e:
-            yield self.store.add_access_token_to_user(user_id, token)
-            # Ignore Registration errors
-            logger.exception(e)
-        defer.returnValue((user_id, token))
-
-    @defer.inlineCallbacks
     def register_email(self, threepidCreds):
         """
         Registers emails with an identity server.
diff --git a/synapse/python_dependencies.py b/synapse/python_dependencies.py
index ca62ee7637..75ba9947cc 100644
--- a/synapse/python_dependencies.py
+++ b/synapse/python_dependencies.py
@@ -53,7 +53,6 @@ REQUIREMENTS = {
     "pillow>=3.1.2": ["PIL"],
     "sortedcontainers>=1.4.4": ["sortedcontainers"],
     "psutil>=2.0.0": ["psutil>=2.0.0"],
-    "pysaml2>=3.0.0": ["saml2"],
     "pymacaroons-pynacl>=0.9.3": ["pymacaroons"],
     "msgpack-python>=0.4.2": ["msgpack"],
     "phonenumbers>=8.2.0": ["phonenumbers"],
diff --git a/synapse/rest/client/v1/login.py b/synapse/rest/client/v1/login.py
index f6b4a85e40..011e84e8b1 100644
--- a/synapse/rest/client/v1/login.py
+++ b/synapse/rest/client/v1/login.py
@@ -18,10 +18,6 @@ import xml.etree.ElementTree as ET
 
 from six.moves import urllib
 
-from canonicaljson import json
-from saml2 import BINDING_HTTP_POST, config
-from saml2.client import Saml2Client
-
 from twisted.internet import defer
 from twisted.web.client import PartialDownloadError
 
@@ -81,7 +77,6 @@ def login_id_thirdparty_from_phone(identifier):
 
 class LoginRestServlet(ClientV1RestServlet):
     PATTERNS = client_path_patterns("/login$")
-    SAML2_TYPE = "m.login.saml2"
     CAS_TYPE = "m.login.cas"
     SSO_TYPE = "m.login.sso"
     TOKEN_TYPE = "m.login.token"
@@ -89,8 +84,6 @@ class LoginRestServlet(ClientV1RestServlet):
 
     def __init__(self, hs):
         super(LoginRestServlet, self).__init__(hs)
-        self.idp_redirect_url = hs.config.saml2_idp_redirect_url
-        self.saml2_enabled = hs.config.saml2_enabled
         self.jwt_enabled = hs.config.jwt_enabled
         self.jwt_secret = hs.config.jwt_secret
         self.jwt_algorithm = hs.config.jwt_algorithm
@@ -103,8 +96,6 @@ class LoginRestServlet(ClientV1RestServlet):
         flows = []
         if self.jwt_enabled:
             flows.append({"type": LoginRestServlet.JWT_TYPE})
-        if self.saml2_enabled:
-            flows.append({"type": LoginRestServlet.SAML2_TYPE})
         if self.cas_enabled:
             flows.append({"type": LoginRestServlet.SSO_TYPE})
 
@@ -134,18 +125,8 @@ class LoginRestServlet(ClientV1RestServlet):
     def on_POST(self, request):
         login_submission = parse_json_object_from_request(request)
         try:
-            if self.saml2_enabled and (login_submission["type"] ==
-                                       LoginRestServlet.SAML2_TYPE):
-                relay_state = ""
-                if "relay_state" in login_submission:
-                    relay_state = "&RelayState=" + urllib.parse.quote(
-                                  login_submission["relay_state"])
-                result = {
-                    "uri": "%s%s" % (self.idp_redirect_url, relay_state)
-                }
-                defer.returnValue((200, result))
-            elif self.jwt_enabled and (login_submission["type"] ==
-                                       LoginRestServlet.JWT_TYPE):
+            if self.jwt_enabled and (login_submission["type"] ==
+                                     LoginRestServlet.JWT_TYPE):
                 result = yield self.do_jwt_login(login_submission)
                 defer.returnValue(result)
             elif login_submission["type"] == LoginRestServlet.TOKEN_TYPE:
@@ -345,50 +326,6 @@ class LoginRestServlet(ClientV1RestServlet):
         )
 
 
-class SAML2RestServlet(ClientV1RestServlet):
-    PATTERNS = client_path_patterns("/login/saml2", releases=())
-
-    def __init__(self, hs):
-        super(SAML2RestServlet, self).__init__(hs)
-        self.sp_config = hs.config.saml2_config_path
-        self.handlers = hs.get_handlers()
-
-    @defer.inlineCallbacks
-    def on_POST(self, request):
-        saml2_auth = None
-        try:
-            conf = config.SPConfig()
-            conf.load_file(self.sp_config)
-            SP = Saml2Client(conf)
-            saml2_auth = SP.parse_authn_request_response(
-                request.args['SAMLResponse'][0], BINDING_HTTP_POST)
-        except Exception as e:        # Not authenticated
-            logger.exception(e)
-        if saml2_auth and saml2_auth.status_ok() and not saml2_auth.not_signed:
-            username = saml2_auth.name_id.text
-            handler = self.handlers.registration_handler
-            (user_id, token) = yield handler.register_saml2(username)
-            # Forward to the RelayState callback along with ava
-            if 'RelayState' in request.args:
-                request.redirect(urllib.parse.unquote(
-                                 request.args['RelayState'][0]) +
-                                 '?status=authenticated&access_token=' +
-                                 token + '&user_id=' + user_id + '&ava=' +
-                                 urllib.quote(json.dumps(saml2_auth.ava)))
-                finish_request(request)
-                defer.returnValue(None)
-            defer.returnValue((200, {"status": "authenticated",
-                                     "user_id": user_id, "token": token,
-                                     "ava": saml2_auth.ava}))
-        elif 'RelayState' in request.args:
-            request.redirect(urllib.parse.unquote(
-                             request.args['RelayState'][0]) +
-                             '?status=not_authenticated')
-            finish_request(request)
-            defer.returnValue(None)
-        defer.returnValue((200, {"status": "not_authenticated"}))
-
-
 class CasRedirectServlet(RestServlet):
     PATTERNS = client_path_patterns("/login/(cas|sso)/redirect")
 
@@ -517,8 +454,6 @@ class CasTicketServlet(ClientV1RestServlet):
 
 def register_servlets(hs, http_server):
     LoginRestServlet(hs).register(http_server)
-    if hs.config.saml2_enabled:
-        SAML2RestServlet(hs).register(http_server)
     if hs.config.cas_enabled:
         CasRedirectServlet(hs).register(http_server)
         CasTicketServlet(hs).register(http_server)
diff --git a/tests/handlers/test_register.py b/tests/handlers/test_register.py
index 90a2a76475..23bce6ee7d 100644
--- a/tests/handlers/test_register.py
+++ b/tests/handlers/test_register.py
@@ -130,21 +130,6 @@ class RegistrationTestCase(unittest.TestCase):
             yield self.handler.register(localpart="local_part")
 
     @defer.inlineCallbacks
-    def test_register_saml2_mau_blocked(self):
-        self.hs.config.limit_usage_by_mau = True
-        self.store.get_monthly_active_count = Mock(
-            return_value=defer.succeed(self.lots_of_users)
-        )
-        with self.assertRaises(ResourceLimitError):
-            yield self.handler.register_saml2(localpart="local_part")
-
-        self.store.get_monthly_active_count = Mock(
-            return_value=defer.succeed(self.hs.config.max_mau_value)
-        )
-        with self.assertRaises(ResourceLimitError):
-            yield self.handler.register_saml2(localpart="local_part")
-
-    @defer.inlineCallbacks
     def test_auto_create_auto_join_rooms(self):
         room_alias_str = "#room:test"
         self.hs.config.auto_join_rooms = [room_alias_str]