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-rw-r--r--synapse/handlers/auth.py37
-rw-r--r--synapse/handlers/cas_handler.py204
-rw-r--r--synapse/handlers/password_policy.py93
-rw-r--r--synapse/handlers/profile.py16
-rw-r--r--synapse/handlers/saml_handler.py4
-rw-r--r--synapse/handlers/set_password.py2
-rw-r--r--synapse/handlers/sync.py4
7 files changed, 354 insertions, 6 deletions
diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index 7860f9625e..2ce1425dfa 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -125,7 +125,11 @@ class AuthHandler(BaseHandler):
 
     @defer.inlineCallbacks
     def validate_user_via_ui_auth(
-        self, requester: Requester, request_body: Dict[str, Any], clientip: str
+        self,
+        requester: Requester,
+        request: SynapseRequest,
+        request_body: Dict[str, Any],
+        clientip: str,
     ):
         """
         Checks that the user is who they claim to be, via a UI auth.
@@ -137,6 +141,8 @@ class AuthHandler(BaseHandler):
         Args:
             requester: The user, as given by the access token
 
+            request: The request sent by the client.
+
             request_body: The body of the request sent by the client
 
             clientip: The IP address of the client.
@@ -172,7 +178,9 @@ class AuthHandler(BaseHandler):
         flows = [[login_type] for login_type in self._supported_login_types]
 
         try:
-            result, params, _ = yield self.check_auth(flows, request_body, clientip)
+            result, params, _ = yield self.check_auth(
+                flows, request, request_body, clientip
+            )
         except LoginError:
             # Update the ratelimite to say we failed (`can_do_action` doesn't raise).
             self._failed_uia_attempts_ratelimiter.can_do_action(
@@ -211,7 +219,11 @@ class AuthHandler(BaseHandler):
 
     @defer.inlineCallbacks
     def check_auth(
-        self, flows: List[List[str]], clientdict: Dict[str, Any], clientip: str
+        self,
+        flows: List[List[str]],
+        request: SynapseRequest,
+        clientdict: Dict[str, Any],
+        clientip: str,
     ):
         """
         Takes a dictionary sent by the client in the login / registration
@@ -231,6 +243,8 @@ class AuthHandler(BaseHandler):
                    strings representing auth-types. At least one full
                    flow must be completed in order for auth to be successful.
 
+            request: The request sent by the client.
+
             clientdict: The dictionary from the client root level, not the
                         'auth' key: this method prompts for auth if none is sent.
 
@@ -270,13 +284,27 @@ class AuthHandler(BaseHandler):
             # email auth link on there). It's probably too open to abuse
             # because it lets unauthenticated clients store arbitrary objects
             # on a homeserver.
-            # Revisit: Assumimg the REST APIs do sensible validation, the data
+            # Revisit: Assuming the REST APIs do sensible validation, the data
             # isn't arbintrary.
             session["clientdict"] = clientdict
             self._save_session(session)
         elif "clientdict" in session:
             clientdict = session["clientdict"]
 
+        # Ensure that the queried operation does not vary between stages of
+        # the UI authentication session. This is done by generating a stable
+        # comparator based on the URI, method, and body (minus the auth dict)
+        # and storing it during the initial query. Subsequent queries ensure
+        # that this comparator has not changed.
+        comparator = (request.uri, request.method, clientdict)
+        if "ui_auth" not in session:
+            session["ui_auth"] = comparator
+        elif session["ui_auth"] != comparator:
+            raise SynapseError(
+                403,
+                "Requested operation has changed during the UI authentication session.",
+            )
+
         if not authdict:
             raise InteractiveAuthIncompleteError(
                 self._auth_dict_for_flows(flows, session)
@@ -322,6 +350,7 @@ class AuthHandler(BaseHandler):
                     creds,
                     list(clientdict),
                 )
+
                 return creds, clientdict, session["id"]
 
         ret = self._auth_dict_for_flows(flows, session)
diff --git a/synapse/handlers/cas_handler.py b/synapse/handlers/cas_handler.py
new file mode 100644
index 0000000000..f8dc274b78
--- /dev/null
+++ b/synapse/handlers/cas_handler.py
@@ -0,0 +1,204 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 The Matrix.org Foundation C.I.C.
+#
+# 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 xml.etree.ElementTree as ET
+from typing import AnyStr, Dict, Optional, Tuple
+
+from six.moves import urllib
+
+from twisted.web.client import PartialDownloadError
+
+from synapse.api.errors import Codes, LoginError
+from synapse.http.site import SynapseRequest
+from synapse.types import UserID, map_username_to_mxid_localpart
+
+logger = logging.getLogger(__name__)
+
+
+class CasHandler:
+    """
+    Utility class for to handle the response from a CAS SSO service.
+
+    Args:
+        hs (synapse.server.HomeServer)
+    """
+
+    def __init__(self, hs):
+        self._hostname = hs.hostname
+        self._auth_handler = hs.get_auth_handler()
+        self._registration_handler = hs.get_registration_handler()
+
+        self._cas_server_url = hs.config.cas_server_url
+        self._cas_service_url = hs.config.cas_service_url
+        self._cas_displayname_attribute = hs.config.cas_displayname_attribute
+        self._cas_required_attributes = hs.config.cas_required_attributes
+
+        self._http_client = hs.get_proxied_http_client()
+
+    def _build_service_param(self, client_redirect_url: AnyStr) -> str:
+        return "%s%s?%s" % (
+            self._cas_service_url,
+            "/_matrix/client/r0/login/cas/ticket",
+            urllib.parse.urlencode({"redirectUrl": client_redirect_url}),
+        )
+
+    async def _handle_cas_response(
+        self, request: SynapseRequest, cas_response_body: str, client_redirect_url: str
+    ) -> None:
+        """
+        Retrieves the user and display name from the CAS response and continues with the authentication.
+
+        Args:
+            request: The original client request.
+            cas_response_body: The response from the CAS server.
+            client_redirect_url: The URl to redirect the client to when
+                everything is done.
+        """
+        user, attributes = self._parse_cas_response(cas_response_body)
+        displayname = attributes.pop(self._cas_displayname_attribute, None)
+
+        for required_attribute, required_value in self._cas_required_attributes.items():
+            # If required attribute was not in CAS Response - Forbidden
+            if required_attribute not in attributes:
+                raise LoginError(401, "Unauthorized", errcode=Codes.UNAUTHORIZED)
+
+            # Also need to check value
+            if required_value is not None:
+                actual_value = attributes[required_attribute]
+                # If required attribute value does not match expected - Forbidden
+                if required_value != actual_value:
+                    raise LoginError(401, "Unauthorized", errcode=Codes.UNAUTHORIZED)
+
+        await self._on_successful_auth(user, request, client_redirect_url, displayname)
+
+    def _parse_cas_response(
+        self, cas_response_body: str
+    ) -> Tuple[str, Dict[str, Optional[str]]]:
+        """
+        Retrieve the user and other parameters from the CAS response.
+
+        Args:
+            cas_response_body: The response from the CAS query.
+
+        Returns:
+            A tuple of the user and a mapping of other attributes.
+        """
+        user = None
+        attributes = {}
+        try:
+            root = ET.fromstring(cas_response_body)
+            if not root.tag.endswith("serviceResponse"):
+                raise Exception("root of CAS response is not serviceResponse")
+            success = root[0].tag.endswith("authenticationSuccess")
+            for child in root[0]:
+                if child.tag.endswith("user"):
+                    user = child.text
+                if child.tag.endswith("attributes"):
+                    for attribute in child:
+                        # ElementTree library expands the namespace in
+                        # attribute tags to the full URL of the namespace.
+                        # We don't care about namespace here and it will always
+                        # be encased in curly braces, so we remove them.
+                        tag = attribute.tag
+                        if "}" in tag:
+                            tag = tag.split("}")[1]
+                        attributes[tag] = attribute.text
+            if user is None:
+                raise Exception("CAS response does not contain user")
+        except Exception:
+            logger.exception("Error parsing CAS response")
+            raise LoginError(401, "Invalid CAS response", errcode=Codes.UNAUTHORIZED)
+        if not success:
+            raise LoginError(
+                401, "Unsuccessful CAS response", errcode=Codes.UNAUTHORIZED
+            )
+        return user, attributes
+
+    async def _on_successful_auth(
+        self,
+        username: str,
+        request: SynapseRequest,
+        client_redirect_url: str,
+        user_display_name: Optional[str] = None,
+    ) -> None:
+        """Called once the user has successfully authenticated with the SSO.
+
+        Registers the user if necessary, and then returns a redirect (with
+        a login token) to the client.
+
+        Args:
+            username: the remote user id. We'll map this onto
+                something sane for a MXID localpath.
+
+            request: the incoming request from the browser. We'll
+                respond to it with a redirect.
+
+            client_redirect_url: the redirect_url the client gave us when
+                it first started the process.
+
+            user_display_name: if set, and we have to register a new user,
+                we will set their displayname to this.
+        """
+        localpart = map_username_to_mxid_localpart(username)
+        user_id = UserID(localpart, self._hostname).to_string()
+        registered_user_id = await self._auth_handler.check_user_exists(user_id)
+        if not registered_user_id:
+            registered_user_id = await self._registration_handler.register_user(
+                localpart=localpart, default_display_name=user_display_name
+            )
+
+        self._auth_handler.complete_sso_login(
+            registered_user_id, request, client_redirect_url
+        )
+
+    def handle_redirect_request(self, client_redirect_url: bytes) -> bytes:
+        """
+        Generates a URL to the CAS server where the client should be redirected.
+
+        Args:
+            client_redirect_url: The final URL the client should go to after the
+                user has negotiated SSO.
+
+        Returns:
+            The URL to redirect to.
+        """
+        args = urllib.parse.urlencode(
+            {"service": self._build_service_param(client_redirect_url)}
+        )
+
+        return ("%s/login?%s" % (self._cas_server_url, args)).encode("ascii")
+
+    async def handle_ticket_request(
+        self, request: SynapseRequest, client_redirect_url: str, ticket: str
+    ) -> None:
+        """
+        Validates a CAS ticket sent by the client for login/registration.
+
+        On a successful request, writes a redirect to the request.
+        """
+        uri = self._cas_server_url + "/proxyValidate"
+        args = {
+            "ticket": ticket,
+            "service": self._build_service_param(client_redirect_url),
+        }
+        try:
+            body = await self._http_client.get_raw(uri, args)
+        except PartialDownloadError as pde:
+            # Twisted raises this error if the connection is closed,
+            # even if that's being used old-http style to signal end-of-data
+            body = pde.response
+
+        await self._handle_cas_response(request, body, client_redirect_url)
diff --git a/synapse/handlers/password_policy.py b/synapse/handlers/password_policy.py
new file mode 100644
index 0000000000..d06b110269
--- /dev/null
+++ b/synapse/handlers/password_policy.py
@@ -0,0 +1,93 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 New Vector Ltd
+# Copyright 2019 The Matrix.org Foundation C.I.C.
+#
+# 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 re
+
+from synapse.api.errors import Codes, PasswordRefusedError
+
+logger = logging.getLogger(__name__)
+
+
+class PasswordPolicyHandler(object):
+    def __init__(self, hs):
+        self.policy = hs.config.password_policy
+        self.enabled = hs.config.password_policy_enabled
+
+        # Regexps for the spec'd policy parameters.
+        self.regexp_digit = re.compile("[0-9]")
+        self.regexp_symbol = re.compile("[^a-zA-Z0-9]")
+        self.regexp_uppercase = re.compile("[A-Z]")
+        self.regexp_lowercase = re.compile("[a-z]")
+
+    def validate_password(self, password):
+        """Checks whether a given password complies with the server's policy.
+
+        Args:
+            password (str): The password to check against the server's policy.
+
+        Raises:
+            PasswordRefusedError: The password doesn't comply with the server's policy.
+        """
+
+        if not self.enabled:
+            return
+
+        minimum_accepted_length = self.policy.get("minimum_length", 0)
+        if len(password) < minimum_accepted_length:
+            raise PasswordRefusedError(
+                msg=(
+                    "The password must be at least %d characters long"
+                    % minimum_accepted_length
+                ),
+                errcode=Codes.PASSWORD_TOO_SHORT,
+            )
+
+        if (
+            self.policy.get("require_digit", False)
+            and self.regexp_digit.search(password) is None
+        ):
+            raise PasswordRefusedError(
+                msg="The password must include at least one digit",
+                errcode=Codes.PASSWORD_NO_DIGIT,
+            )
+
+        if (
+            self.policy.get("require_symbol", False)
+            and self.regexp_symbol.search(password) is None
+        ):
+            raise PasswordRefusedError(
+                msg="The password must include at least one symbol",
+                errcode=Codes.PASSWORD_NO_SYMBOL,
+            )
+
+        if (
+            self.policy.get("require_uppercase", False)
+            and self.regexp_uppercase.search(password) is None
+        ):
+            raise PasswordRefusedError(
+                msg="The password must include at least one uppercase letter",
+                errcode=Codes.PASSWORD_NO_UPPERCASE,
+            )
+
+        if (
+            self.policy.get("require_lowercase", False)
+            and self.regexp_lowercase.search(password) is None
+        ):
+            raise PasswordRefusedError(
+                msg="The password must include at least one lowercase letter",
+                errcode=Codes.PASSWORD_NO_LOWERCASE,
+            )
diff --git a/synapse/handlers/profile.py b/synapse/handlers/profile.py
index 50ce0c585b..6aa1c0f5e0 100644
--- a/synapse/handlers/profile.py
+++ b/synapse/handlers/profile.py
@@ -157,6 +157,15 @@ class BaseProfileHandler(BaseHandler):
         if not by_admin and target_user != requester.user:
             raise AuthError(400, "Cannot set another user's displayname")
 
+        if not by_admin and not self.hs.config.enable_set_displayname:
+            profile = yield self.store.get_profileinfo(target_user.localpart)
+            if profile.display_name:
+                raise SynapseError(
+                    400,
+                    "Changing display name is disabled on this server",
+                    Codes.FORBIDDEN,
+                )
+
         if len(new_displayname) > MAX_DISPLAYNAME_LEN:
             raise SynapseError(
                 400, "Displayname is too long (max %i)" % (MAX_DISPLAYNAME_LEN,)
@@ -218,6 +227,13 @@ class BaseProfileHandler(BaseHandler):
         if not by_admin and target_user != requester.user:
             raise AuthError(400, "Cannot set another user's avatar_url")
 
+        if not by_admin and not self.hs.config.enable_set_avatar_url:
+            profile = yield self.store.get_profileinfo(target_user.localpart)
+            if profile.avatar_url:
+                raise SynapseError(
+                    400, "Changing avatar is disabled on this server", Codes.FORBIDDEN
+                )
+
         if len(new_avatar_url) > MAX_AVATAR_URL_LEN:
             raise SynapseError(
                 400, "Avatar URL is too long (max %i)" % (MAX_AVATAR_URL_LEN,)
diff --git a/synapse/handlers/saml_handler.py b/synapse/handlers/saml_handler.py
index 72c109981b..dc04b53f43 100644
--- a/synapse/handlers/saml_handler.py
+++ b/synapse/handlers/saml_handler.py
@@ -26,6 +26,7 @@ from synapse.config import ConfigError
 from synapse.http.server import finish_request
 from synapse.http.servlet import parse_string
 from synapse.module_api import ModuleApi
+from synapse.module_api.errors import RedirectException
 from synapse.types import (
     UserID,
     map_username_to_mxid_localpart,
@@ -119,6 +120,9 @@ class SamlHandler:
 
         try:
             user_id = await self._map_saml_response_to_user(resp_bytes, relay_state)
+        except RedirectException:
+            # Raise the exception as per the wishes of the SAML module response
+            raise
         except Exception as e:
             # If decoding the response or mapping it to a user failed, then log the
             # error and tell the user that something went wrong.
diff --git a/synapse/handlers/set_password.py b/synapse/handlers/set_password.py
index 12657ca698..7d1263caf2 100644
--- a/synapse/handlers/set_password.py
+++ b/synapse/handlers/set_password.py
@@ -32,6 +32,7 @@ class SetPasswordHandler(BaseHandler):
         super(SetPasswordHandler, self).__init__(hs)
         self._auth_handler = hs.get_auth_handler()
         self._device_handler = hs.get_device_handler()
+        self._password_policy_handler = hs.get_password_policy_handler()
 
     @defer.inlineCallbacks
     def set_password(
@@ -44,6 +45,7 @@ class SetPasswordHandler(BaseHandler):
         if not self.hs.config.password_localdb_enabled:
             raise SynapseError(403, "Password change disabled", errcode=Codes.FORBIDDEN)
 
+        self._password_policy_handler.validate_password(new_password)
         password_hash = yield self._auth_handler.hash(new_password)
 
         try:
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 669dbc8a48..5746fdea14 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -26,7 +26,7 @@ from prometheus_client import Counter
 from synapse.api.constants import EventTypes, Membership
 from synapse.api.filtering import FilterCollection
 from synapse.events import EventBase
-from synapse.logging.context import LoggingContext
+from synapse.logging.context import current_context
 from synapse.push.clientformat import format_push_rules_for_user
 from synapse.storage.roommember import MemberSummary
 from synapse.storage.state import StateFilter
@@ -301,7 +301,7 @@ class SyncHandler(object):
         else:
             sync_type = "incremental_sync"
 
-        context = LoggingContext.current_context()
+        context = current_context()
         if context:
             context.tag = sync_type