Merge commit '6a3504636' into dinsic-release-v1.12.x

* commit '6a3504636': (29 commits)
  Revert "Add options to disable setting profile info for prevent changes. (#7053)"
  Populate the room version from state events (#7070)
  Fix buggy condition in account validity handler (#7074)
  Use innerText instead of innerHTML
  Add type annotations and comments to auth handler (#7063)
  Lint
  Put the file in the templates directory
  Update wording and config
  Changelog
  Move the default SAML2 error HTML to a dedicated file
  Refactor a bit
  Also don't fail on aliases events in this case
  Lint
  Changelog
  Also don't filter out events sent by ignored users when checking state visibility
  Fix condition
  Don't filter out dummy events when we're checking the visibility of state
  Update sample_config.yaml
  Update synapse/config/registration.py
  lint, fix tests
  ...

15 files changed, 302 insertions, 149 deletions

diff --git a/changelog.d/7063.misc b/changelog.d/7063.misc
new file mode 100644
index 0000000000..e7b1cd3cd8
--- /dev/null
+++ b/changelog.d/7063.misc
@@ -0,0 +1 @@
+Add type annotations and comments to the auth handler.
diff --git a/changelog.d/7066.bugfix b/changelog.d/7066.bugfix
new file mode 100644
index 0000000000..94bb096287
--- /dev/null
+++ b/changelog.d/7066.bugfix
@@ -0,0 +1 @@
+Fix a bug that would cause Synapse to respond with an error about event visibility if a client tried to request the state of a room at a given token.
diff --git a/changelog.d/7067.feature b/changelog.d/7067.feature
new file mode 100644
index 0000000000..53ea485e03
--- /dev/null
+++ b/changelog.d/7067.feature
@@ -0,0 +1 @@
+Render a configurable and comprehensible error page if something goes wrong during the SAML2 authentication process.
diff --git a/changelog.d/7070.bugfix b/changelog.d/7070.bugfix
new file mode 100644
index 0000000000..9031927546
--- /dev/null
+++ b/changelog.d/7070.bugfix
@@ -0,0 +1 @@
+Repair a data-corruption issue which was introduced in Synapse 1.10, and fixed in Synapse 1.11, and which could cause `/sync` to return with 404 errors about missing events and unknown rooms.
diff --git a/changelog.d/7074.bugfix b/changelog.d/7074.bugfix
new file mode 100644
index 0000000000..38d7455971
--- /dev/null
+++ b/changelog.d/7074.bugfix
@@ -0,0 +1 @@
+Fix a bug causing account validity renewal emails to be sent even if the feature is turned off in some cases.
diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml
index 2114b4fc68..34bdc3759f 100644
--- a/docs/sample_config.yaml
+++ b/docs/sample_config.yaml
@@ -1497,12 +1497,24 @@ saml2_config:
   #
   #grandfathered_mxid_source_attribute: upn
 
-  # Path to a file containing HTML content to serve in case an error happens
-  # when the user gets redirected from the SAML IdP back to Synapse.
-  # If no file is provided, this defaults to some minimalistic HTML telling the
-  # user that something went wrong and they should try authenticating again.
+  # Directory in which Synapse will try to find the template files below.
+  # If not set, default templates from within the Synapse package will be used.
+  #
+  # DO NOT UNCOMMENT THIS SETTING unless you want to customise the templates.
+  # If you *do* uncomment it, you will need to make sure that all the templates
+  # below are in the directory.
+  #
+  # Synapse will look for the following templates in this directory:
+  #
+  # * HTML page to display to users if something goes wrong during the
+  #   authentication process: 'saml_error.html'.
   #
-  #error_html_path: /path/to/static/content/saml_error.html
+  #   This template doesn't currently need any variable to render.
+  #
+  # You can see the default templates at:
+  # https://github.com/matrix-org/synapse/tree/master/synapse/res/templates
+  #
+  #template_dir: "res/templates"
 
 
 
diff --git a/synapse/config/saml2_config.py b/synapse/config/saml2_config.py
index 07895c4315..8fe64d90f8 100644
--- a/synapse/config/saml2_config.py
+++ b/synapse/config/saml2_config.py
@@ -15,6 +15,9 @@
 # limitations under the License.
 
 import logging
+import os
+
+import pkg_resources
 
 from synapse.python_dependencies import DependencyException, check_requirements
 from synapse.util.module_loader import load_module, load_python_module
@@ -27,18 +30,6 @@ DEFAULT_USER_MAPPING_PROVIDER = (
     "synapse.handlers.saml_handler.DefaultSamlMappingProvider"
 )
 
-SAML2_ERROR_DEFAULT_HTML = """
-<html>
-    <body>
-        <p>Oops! Something went wrong</p>
-        <p>
-            Try logging in again from your Matrix client and if the problem persists
-            please contact the server's administrator.
-        </p>
-    </body>
-</html>
-"""
-
 
 def _dict_merge(merge_dict, into_dict):
     """Do a deep merge of two dicts
@@ -172,12 +163,13 @@ class SAML2Config(Config):
             saml2_config.get("saml_session_lifetime", "5m")
         )
 
-        if "error_html_path" in config:
-            self.saml2_error_html_content = self.read_file(
-                config["error_html_path"], "saml2_config.error_html_path",
-            )
-        else:
-            self.saml2_error_html_content = SAML2_ERROR_DEFAULT_HTML
+        template_dir = saml2_config.get("template_dir")
+        if not template_dir:
+            template_dir = pkg_resources.resource_filename("synapse", "res/templates",)
+
+        self.saml2_error_html_content = self.read_file(
+            os.path.join(template_dir, "saml_error.html"), "saml2_config.saml_error",
+        )
 
     def _default_saml_config_dict(
         self, required_attributes: set, optional_attributes: set
@@ -345,12 +337,24 @@ class SAML2Config(Config):
           #
           #grandfathered_mxid_source_attribute: upn
 
-          # Path to a file containing HTML content to serve in case an error happens
-          # when the user gets redirected from the SAML IdP back to Synapse.
-          # If no file is provided, this defaults to some minimalistic HTML telling the
-          # user that something went wrong and they should try authenticating again.
+          # Directory in which Synapse will try to find the template files below.
+          # If not set, default templates from within the Synapse package will be used.
+          #
+          # DO NOT UNCOMMENT THIS SETTING unless you want to customise the templates.
+          # If you *do* uncomment it, you will need to make sure that all the templates
+          # below are in the directory.
+          #
+          # Synapse will look for the following templates in this directory:
+          #
+          # * HTML page to display to users if something goes wrong during the
+          #   authentication process: 'saml_error.html'.
+          #
+          #   This template doesn't currently need any variable to render.
+          #
+          # You can see the default templates at:
+          # https://github.com/matrix-org/synapse/tree/master/synapse/res/templates
           #
-          #error_html_path: /path/to/static/content/saml_error.html
+          #template_dir: "res/templates"
         """ % {
             "config_dir_path": config_dir_path
         }
diff --git a/synapse/handlers/account_validity.py b/synapse/handlers/account_validity.py
index 6c46c995d2..f4bf92f775 100644
--- a/synapse/handlers/account_validity.py
+++ b/synapse/handlers/account_validity.py
@@ -48,7 +48,11 @@ class AccountValidityHandler(object):
         self._show_users_in_user_directory = self.hs.config.show_users_in_user_directory
         self.profile_handler = self.hs.get_profile_handler()
 
-        if self._account_validity.renew_by_email_enabled and load_jinja2_templates:
+        if (
+            self._account_validity.enabled
+            and self._account_validity.renew_by_email_enabled
+            and load_jinja2_templates
+        ):
             # Don't do email-specific configuration if renewal by email is disabled.
             try:
                 app_name = self.hs.config.email_app_name
diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index 7ca90f91c4..7860f9625e 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -18,10 +18,10 @@ import logging
 import time
 import unicodedata
 import urllib.parse
-from typing import Any
+from typing import Any, Dict, Iterable, List, Optional
 
 import attr
-import bcrypt
+import bcrypt  # type: ignore[import]
 import pymacaroons
 
 from twisted.internet import defer
@@ -45,7 +45,7 @@ from synapse.http.site import SynapseRequest
 from synapse.logging.context import defer_to_thread
 from synapse.module_api import ModuleApi
 from synapse.push.mailer import load_jinja2_templates
-from synapse.types import UserID
+from synapse.types import Requester, UserID
 from synapse.util.caches.expiringcache import ExpiringCache
 
 from ._base import BaseHandler
@@ -63,11 +63,11 @@ class AuthHandler(BaseHandler):
         """
         super(AuthHandler, self).__init__(hs)
 
-        self.checkers = {}  # type: dict[str, UserInteractiveAuthChecker]
+        self.checkers = {}  # type: Dict[str, UserInteractiveAuthChecker]
         for auth_checker_class in INTERACTIVE_AUTH_CHECKERS:
             inst = auth_checker_class(hs)
             if inst.is_enabled():
-                self.checkers[inst.AUTH_TYPE] = inst
+                self.checkers[inst.AUTH_TYPE] = inst  # type: ignore
 
         self.bcrypt_rounds = hs.config.bcrypt_rounds
 
@@ -124,7 +124,9 @@ class AuthHandler(BaseHandler):
         self._whitelisted_sso_clients = tuple(hs.config.sso_client_whitelist)
 
     @defer.inlineCallbacks
-    def validate_user_via_ui_auth(self, requester, request_body, clientip):
+    def validate_user_via_ui_auth(
+        self, requester: Requester, request_body: Dict[str, Any], clientip: str
+    ):
         """
         Checks that the user is who they claim to be, via a UI auth.
 
@@ -133,11 +135,11 @@ class AuthHandler(BaseHandler):
         that it isn't stolen by re-authenticating them.
 
         Args:
-            requester (Requester): The user, as given by the access token
+            requester: The user, as given by the access token
 
-            request_body (dict): The body of the request sent by the client
+            request_body: The body of the request sent by the client
 
-            clientip (str): The IP address of the client.
+            clientip: The IP address of the client.
 
         Returns:
             defer.Deferred[dict]: the parameters for this request (which may
@@ -208,7 +210,9 @@ class AuthHandler(BaseHandler):
         return self.checkers.keys()
 
     @defer.inlineCallbacks
-    def check_auth(self, flows, clientdict, clientip):
+    def check_auth(
+        self, flows: List[List[str]], clientdict: Dict[str, Any], clientip: str
+    ):
         """
         Takes a dictionary sent by the client in the login / registration
         protocol and handles the User-Interactive Auth flow.
@@ -223,14 +227,14 @@ class AuthHandler(BaseHandler):
         decorator.
 
         Args:
-            flows (list): A list of login flows. Each flow is an ordered list of
-                          strings representing auth-types. At least one full
-                          flow must be completed in order for auth to be successful.
+            flows: A list of login flows. Each flow is an ordered list of
+                   strings representing auth-types. At least one full
+                   flow must be completed in order for auth to be successful.
 
             clientdict: The dictionary from the client root level, not the
                         'auth' key: this method prompts for auth if none is sent.
 
-            clientip (str): The IP address of the client.
+            clientip: The IP address of the client.
 
         Returns:
             defer.Deferred[dict, dict, str]: a deferred tuple of
@@ -250,7 +254,7 @@ class AuthHandler(BaseHandler):
         """
 
         authdict = None
-        sid = None
+        sid = None  # type: Optional[str]
         if clientdict and "auth" in clientdict:
             authdict = clientdict["auth"]
             del clientdict["auth"]
@@ -283,9 +287,9 @@ class AuthHandler(BaseHandler):
         creds = session["creds"]
 
         # check auth type currently being presented
-        errordict = {}
+        errordict = {}  # type: Dict[str, Any]
         if "type" in authdict:
-            login_type = authdict["type"]
+            login_type = authdict["type"]  # type: str
             try:
                 result = yield self._check_auth_dict(authdict, clientip)
                 if result:
@@ -326,7 +330,7 @@ class AuthHandler(BaseHandler):
         raise InteractiveAuthIncompleteError(ret)
 
     @defer.inlineCallbacks
-    def add_oob_auth(self, stagetype, authdict, clientip):
+    def add_oob_auth(self, stagetype: str, authdict: Dict[str, Any], clientip: str):
         """
         Adds the result of out-of-band authentication into an existing auth
         session. Currently used for adding the result of fallback auth.
@@ -348,7 +352,7 @@ class AuthHandler(BaseHandler):
             return True
         return False
 
-    def get_session_id(self, clientdict):
+    def get_session_id(self, clientdict: Dict[str, Any]) -> Optional[str]:
         """
         Gets the session ID for a client given the client dictionary
 
@@ -356,7 +360,7 @@ class AuthHandler(BaseHandler):
             clientdict: The dictionary sent by the client in the request
 
         Returns:
-            str|None: The string session ID the client sent. If the client did
+            The string session ID the client sent. If the client did
                 not send a session ID, returns None.
         """
         sid = None
@@ -366,40 +370,42 @@ class AuthHandler(BaseHandler):
                 sid = authdict["session"]
         return sid
 
-    def set_session_data(self, session_id, key, value):
+    def set_session_data(self, session_id: str, key: str, value: Any) -> None:
         """
         Store a key-value pair into the sessions data associated with this
         request. This data is stored server-side and cannot be modified by
         the client.
 
         Args:
-            session_id (string): The ID of this session as returned from check_auth
-            key (string): The key to store the data under
-            value (any): The data to store
+            session_id: The ID of this session as returned from check_auth
+            key: The key to store the data under
+            value: The data to store
         """
         sess = self._get_session_info(session_id)
         sess.setdefault("serverdict", {})[key] = value
         self._save_session(sess)
 
-    def get_session_data(self, session_id, key, default=None):
+    def get_session_data(
+        self, session_id: str, key: str, default: Optional[Any] = None
+    ) -> Any:
         """
         Retrieve data stored with set_session_data
 
         Args:
-            session_id (string): The ID of this session as returned from check_auth
-            key (string): The key to store the data under
-            default (any): Value to return if the key has not been set
+            session_id: The ID of this session as returned from check_auth
+            key: The key to store the data under
+            default: Value to return if the key has not been set
         """
         sess = self._get_session_info(session_id)
         return sess.setdefault("serverdict", {}).get(key, default)
 
     @defer.inlineCallbacks
-    def _check_auth_dict(self, authdict, clientip):
+    def _check_auth_dict(self, authdict: Dict[str, Any], clientip: str):
         """Attempt to validate the auth dict provided by a client
 
         Args:
-            authdict (object): auth dict provided by the client
-            clientip (str): IP address of the client
+            authdict: auth dict provided by the client
+            clientip: IP address of the client
 
         Returns:
             Deferred: result of the stage verification.
@@ -425,10 +431,10 @@ class AuthHandler(BaseHandler):
         (canonical_id, callback) = yield self.validate_login(user_id, authdict)
         return canonical_id
 
-    def _get_params_recaptcha(self):
+    def _get_params_recaptcha(self) -> dict:
         return {"public_key": self.hs.config.recaptcha_public_key}
 
-    def _get_params_terms(self):
+    def _get_params_terms(self) -> dict:
         return {
             "policies": {
                 "privacy_policy": {
@@ -445,7 +451,9 @@ class AuthHandler(BaseHandler):
             }
         }
 
-    def _auth_dict_for_flows(self, flows, session):
+    def _auth_dict_for_flows(
+        self, flows: List[List[str]], session: Dict[str, Any]
+    ) -> Dict[str, Any]:
         public_flows = []
         for f in flows:
             public_flows.append(f)
@@ -455,7 +463,7 @@ class AuthHandler(BaseHandler):
             LoginType.TERMS: self._get_params_terms,
         }
 
-        params = {}
+        params = {}  # type: Dict[str, Any]
 
         for f in public_flows:
             for stage in f:
@@ -468,7 +476,13 @@ class AuthHandler(BaseHandler):
             "params": params,
         }
 
-    def _get_session_info(self, session_id):
+    def _get_session_info(self, session_id: Optional[str]) -> dict:
+        """
+        Gets or creates a session given a session ID.
+
+        The session can be used to track data across multiple requests, e.g. for
+        interactive authentication.
+        """
         if session_id not in self.sessions:
             session_id = None
 
@@ -481,7 +495,9 @@ class AuthHandler(BaseHandler):
         return self.sessions[session_id]
 
     @defer.inlineCallbacks
-    def get_access_token_for_user_id(self, user_id, device_id, valid_until_ms):
+    def get_access_token_for_user_id(
+        self, user_id: str, device_id: Optional[str], valid_until_ms: Optional[int]
+    ):
         """
         Creates a new access token for the user with the given user ID.
 
@@ -491,11 +507,11 @@ class AuthHandler(BaseHandler):
         The device will be recorded in the table if it is not there already.
 
         Args:
-            user_id (str): canonical User ID
-            device_id (str|None): the device ID to associate with the tokens.
+            user_id: canonical User ID
+            device_id: the device ID to associate with the tokens.
                None to leave the tokens unassociated with a device (deprecated:
                we should always have a device ID)
-            valid_until_ms (int|None): when the token is valid until. None for
+            valid_until_ms: when the token is valid until. None for
                 no expiry.
         Returns:
               The access token for the user's session.
@@ -530,13 +546,13 @@ class AuthHandler(BaseHandler):
         return access_token
 
     @defer.inlineCallbacks
-    def check_user_exists(self, user_id):
+    def check_user_exists(self, user_id: str):
         """
         Checks to see if a user with the given id exists. Will check case
         insensitively, but return None if there are multiple inexact matches.
 
         Args:
-            (unicode|bytes) user_id: complete @user:id
+            user_id: complete @user:id
 
         Returns:
             defer.Deferred: (unicode) canonical_user_id, or None if zero or
@@ -551,7 +567,7 @@ class AuthHandler(BaseHandler):
         return None
 
     @defer.inlineCallbacks
-    def _find_user_id_and_pwd_hash(self, user_id):
+    def _find_user_id_and_pwd_hash(self, user_id: str):
         """Checks to see if a user with the given id exists. Will check case
         insensitively, but will return None if there are multiple inexact
         matches.
@@ -581,7 +597,7 @@ class AuthHandler(BaseHandler):
             )
         return result
 
-    def get_supported_login_types(self):
+    def get_supported_login_types(self) -> Iterable[str]:
         """Get a the login types supported for the /login API
 
         By default this is just 'm.login.password' (unless password_enabled is
@@ -589,20 +605,20 @@ class AuthHandler(BaseHandler):
         other login types.
 
         Returns:
-            Iterable[str]: login types
+            login types
         """
         return self._supported_login_types
 
     @defer.inlineCallbacks
-    def validate_login(self, username, login_submission):
+    def validate_login(self, username: str, login_submission: Dict[str, Any]):
         """Authenticates the user for the /login API
 
         Also used by the user-interactive auth flow to validate
         m.login.password auth types.
 
         Args:
-            username (str): username supplied by the user
-            login_submission (dict): the whole of the login submission
+            username: username supplied by the user
+            login_submission: the whole of the login submission
                 (including 'type' and other relevant fields)
         Returns:
             Deferred[str, func]: canonical user id, and optional callback
@@ -690,13 +706,13 @@ class AuthHandler(BaseHandler):
         raise LoginError(403, "Invalid password", errcode=Codes.FORBIDDEN)
 
     @defer.inlineCallbacks
-    def check_password_provider_3pid(self, medium, address, password):
+    def check_password_provider_3pid(self, medium: str, address: str, password: str):
         """Check if a password provider is able to validate a thirdparty login
 
         Args:
-            medium (str): The medium of the 3pid (ex. email).
-            address (str): The address of the 3pid (ex. jdoe@example.com).
-            password (str): The password of the user.
+            medium: The medium of the 3pid (ex. email).
+            address: The address of the 3pid (ex. jdoe@example.com).
+            password: The password of the user.
 
         Returns:
             Deferred[(str|None, func|None)]: A tuple of `(user_id,
@@ -724,15 +740,15 @@ class AuthHandler(BaseHandler):
         return None, None
 
     @defer.inlineCallbacks
-    def _check_local_password(self, user_id, password):
+    def _check_local_password(self, user_id: str, password: str):
         """Authenticate a user against the local password database.
 
         user_id is checked case insensitively, but will return None if there are
         multiple inexact matches.
 
         Args:
-            user_id (unicode): complete @user:id
-            password (unicode): the provided password
+            user_id: complete @user:id
+            password: the provided password
         Returns:
             Deferred[unicode] the canonical_user_id, or Deferred[None] if
                 unknown user/bad password
@@ -755,7 +771,7 @@ class AuthHandler(BaseHandler):
         return user_id
 
     @defer.inlineCallbacks
-    def validate_short_term_login_token_and_get_user_id(self, login_token):
+    def validate_short_term_login_token_and_get_user_id(self, login_token: str):
         auth_api = self.hs.get_auth()
         user_id = None
         try:
@@ -769,11 +785,11 @@ class AuthHandler(BaseHandler):
         return user_id
 
     @defer.inlineCallbacks
-    def delete_access_token(self, access_token):
+    def delete_access_token(self, access_token: str):
         """Invalidate a single access token
 
         Args:
-            access_token (str): access token to be deleted
+            access_token: access token to be deleted
 
         Returns:
             Deferred
@@ -798,15 +814,17 @@ class AuthHandler(BaseHandler):
 
     @defer.inlineCallbacks
     def delete_access_tokens_for_user(
-        self, user_id, except_token_id=None, device_id=None
+        self,
+        user_id: str,
+        except_token_id: Optional[str] = None,
+        device_id: Optional[str] = None,
     ):
         """Invalidate access tokens belonging to a user
 
         Args:
-            user_id (str):  ID of user the tokens belong to
-            except_token_id (str|None): access_token ID which should *not* be
-                deleted
-            device_id (str|None):  ID of device the tokens are associated with.
+            user_id:  ID of user the tokens belong to
+            except_token_id: access_token ID which should *not* be deleted
+            device_id:  ID of device the tokens are associated with.
                 If None, tokens associated with any device (or no device) will
                 be deleted
         Returns:
@@ -830,7 +848,7 @@ class AuthHandler(BaseHandler):
         )
 
     @defer.inlineCallbacks
-    def add_threepid(self, user_id, medium, address, validated_at):
+    def add_threepid(self, user_id: str, medium: str, address: str, validated_at: int):
         # check if medium has a valid value
         if medium not in ["email", "msisdn"]:
             raise SynapseError(
@@ -856,19 +874,20 @@ class AuthHandler(BaseHandler):
         )
 
     @defer.inlineCallbacks
-    def delete_threepid(self, user_id, medium, address, id_server=None):
+    def delete_threepid(
+        self, user_id: str, medium: str, address: str, id_server: Optional[str] = None
+    ):
         """Attempts to unbind the 3pid on the identity servers and deletes it
         from the local database.
 
         Args:
-            user_id (str)
-            medium (str)
-            address (str)
-            id_server (str|None): Use the given identity server when unbinding
+            user_id: ID of user to remove the 3pid from.
+            medium: The medium of the 3pid being removed: "email" or "msisdn".
+            address: The 3pid address to remove.
+            id_server: Use the given identity server when unbinding
                 any threepids. If None then will attempt to unbind using the
                 identity server specified when binding (if known).
 
-
         Returns:
             Deferred[bool]: Returns True if successfully unbound the 3pid on
             the identity server, False if identity server doesn't support the
@@ -887,17 +906,18 @@ class AuthHandler(BaseHandler):
         yield self.store.user_delete_threepid(user_id, medium, address)
         return result
 
-    def _save_session(self, session):
+    def _save_session(self, session: Dict[str, Any]) -> None:
+        """Update the last used time on the session to now and add it back to the session store."""
         # TODO: Persistent storage
         logger.debug("Saving session %s", session)
         session["last_used"] = self.hs.get_clock().time_msec()
         self.sessions[session["id"]] = session
 
-    def hash(self, password):
+    def hash(self, password: str):
         """Computes a secure hash of password.
 
         Args:
-            password (unicode): Password to hash.
+            password: Password to hash.
 
         Returns:
             Deferred(unicode): Hashed password.
@@ -914,12 +934,12 @@ class AuthHandler(BaseHandler):
 
         return defer_to_thread(self.hs.get_reactor(), _do_hash)
 
-    def validate_hash(self, password, stored_hash):
+    def validate_hash(self, password: str, stored_hash: bytes):
         """Validates that self.hash(password) == stored_hash.
 
         Args:
-            password (unicode): Password to hash.
-            stored_hash (bytes): Expected hash value.
+            password: Password to hash.
+            stored_hash: Expected hash value.
 
         Returns:
             Deferred(bool): Whether self.hash(password) == stored_hash.
@@ -1007,7 +1027,9 @@ class MacaroonGenerator(object):
 
     hs = attr.ib()
 
-    def generate_access_token(self, user_id, extra_caveats=None):
+    def generate_access_token(
+        self, user_id: str, extra_caveats: Optional[List[str]] = None
+    ) -> str:
         extra_caveats = extra_caveats or []
         macaroon = self._generate_base_macaroon(user_id)
         macaroon.add_first_party_caveat("type = access")
@@ -1020,16 +1042,9 @@ class MacaroonGenerator(object):
             macaroon.add_first_party_caveat(caveat)
         return macaroon.serialize()
 
-    def generate_short_term_login_token(self, user_id, duration_in_ms=(2 * 60 * 1000)):
-        """
-
-        Args:
-            user_id (unicode):
-            duration_in_ms (int):
-
-        Returns:
-            unicode
-        """
+    def generate_short_term_login_token(
+        self, user_id: str, duration_in_ms: int = (2 * 60 * 1000)
+    ) -> str:
         macaroon = self._generate_base_macaroon(user_id)
         macaroon.add_first_party_caveat("type = login")
         now = self.hs.get_clock().time_msec()
@@ -1037,12 +1052,12 @@ class MacaroonGenerator(object):
         macaroon.add_first_party_caveat("time < %d" % (expiry,))
         return macaroon.serialize()
 
-    def generate_delete_pusher_token(self, user_id):
+    def generate_delete_pusher_token(self, user_id: str) -> str:
         macaroon = self._generate_base_macaroon(user_id)
         macaroon.add_first_party_caveat("type = delete_pusher")
         return macaroon.serialize()
 
-    def _generate_base_macaroon(self, user_id):
+    def _generate_base_macaroon(self, user_id: str) -> pymacaroons.Macaroon:
         macaroon = pymacaroons.Macaroon(
             location=self.hs.config.server_name,
             identifier="key",
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 0c84c6cec4..b743fc2dcc 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -160,7 +160,7 @@ class MessageHandler(object):
                 raise NotFoundError("Can't find event for token %s" % (at_token,))
 
             visible_events = yield filter_events_for_client(
-                self.storage, user_id, last_events, apply_retention_policies=False
+                self.storage, user_id, last_events, filter_send_to_client=False
             )
 
             event = last_events[0]
diff --git a/synapse/res/templates/saml_error.html b/synapse/res/templates/saml_error.html
new file mode 100644
index 0000000000..bfd6449c5d
--- /dev/null
+++ b/synapse/res/templates/saml_error.html
@@ -0,0 +1,45 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <title>SSO error</title>
+</head>
+<body>
+    <p>Oops! Something went wrong during authentication<span id="errormsg"></span>.</p>
+    <p>
+        If you are seeing this page after clicking a link sent to you via email, make
+        sure you only click the confirmation link once, and that you open the
+        validation link in the same client you're logging in from.
+    </p>
+    <p>
+        Try logging in again from your Matrix client and if the problem persists
+        please contact the server's administrator.
+    </p>
+
+    <script type="text/javascript">
+        // Error handling to support Auth0 errors that we might get through a GET request
+        // to the validation endpoint. If an error is provided, it's either going to be
+        // located in the query string or in a query string-like URI fragment.
+        // We try to locate the error from any of these two locations, but if we can't
+        // we just don't print anything specific.
+        let searchStr = "";
+        if (window.location.search) {
+            // window.location.searchParams isn't always defined when
+            // window.location.search is, so it's more reliable to parse the latter.
+            searchStr = window.location.search;
+        } else if (window.location.hash) {
+            // Replace the # with a ? so that URLSearchParams does the right thing and
+            // doesn't parse the first parameter incorrectly.
+            searchStr = window.location.hash.replace("#", "?");
+        }
+
+        // We might end up with no error in the URL, so we need to check if we have one
+        // to print one.
+        let errorDesc = new URLSearchParams(searchStr).get("error_description")
+        if (errorDesc) {
+
+            document.getElementById("errormsg").innerText = ` ("${errorDesc}")`;
+        }
+    </script>
+</body>
+</html>
\ No newline at end of file
diff --git a/synapse/storage/data_stores/main/schema/delta/57/rooms_version_column_3.sql.postgres b/synapse/storage/data_stores/main/schema/delta/57/rooms_version_column_3.sql.postgres
new file mode 100644
index 0000000000..92aaadde0d
--- /dev/null
+++ b/synapse/storage/data_stores/main/schema/delta/57/rooms_version_column_3.sql.postgres
@@ -0,0 +1,39 @@
+/* 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.
+ */
+
+-- When we first added the room_version column to the rooms table, it was populated from
+-- the current_state_events table. However, there was an issue causing a background
+-- update to clean up the current_state_events table for rooms where the server is no
+-- longer participating, before that column could be populated. Therefore, some rooms had
+-- a NULL room_version.
+
+-- The rooms_version_column_2.sql.* delta files were introduced to make the populating
+-- synchronous instead of running it in a background update, which fixed this issue.
+-- However, all of the instances of Synapse installed or updated in the meantime got
+-- their rooms table corrupted with NULL room_versions.
+
+-- This query fishes out the room versions from the create event using the state_events
+-- table instead of the current_state_events one, as the former still have all of the
+-- create events.
+
+UPDATE rooms SET room_version=(
+    SELECT COALESCE(json::json->'content'->>'room_version','1')
+    FROM state_events se INNER JOIN event_json ej USING (event_id)
+    WHERE se.room_id=rooms.room_id AND se.type='m.room.create' AND se.state_key=''
+    LIMIT 1
+) WHERE rooms.room_version IS NULL;
+
+-- see also rooms_version_column_3.sql.sqlite which has a copy of the above query, using
+-- sqlite syntax for the json extraction.
diff --git a/synapse/storage/data_stores/main/schema/delta/57/rooms_version_column_3.sql.sqlite b/synapse/storage/data_stores/main/schema/delta/57/rooms_version_column_3.sql.sqlite
new file mode 100644
index 0000000000..e19dab97cb
--- /dev/null
+++ b/synapse/storage/data_stores/main/schema/delta/57/rooms_version_column_3.sql.sqlite
@@ -0,0 +1,23 @@
+/* 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.
+ */
+
+-- see rooms_version_column_3.sql.postgres for details of what's going on here.
+
+UPDATE rooms SET room_version=(
+    SELECT COALESCE(json_extract(ej.json, '$.content.room_version'), '1')
+    FROM state_events se INNER JOIN event_json ej USING (event_id)
+    WHERE se.room_id=rooms.room_id AND se.type='m.room.create' AND se.state_key=''
+    LIMIT 1
+) WHERE rooms.room_version IS NULL;
diff --git a/synapse/visibility.py b/synapse/visibility.py
index a48a4f3dfe..bab41182b9 100644
--- a/synapse/visibility.py
+++ b/synapse/visibility.py
@@ -49,7 +49,7 @@ def filter_events_for_client(
     events,
     is_peeking=False,
     always_include_ids=frozenset(),
-    apply_retention_policies=True,
+    filter_send_to_client=True,
 ):
     """
     Check which events a user is allowed to see. If the user can see the event but its
@@ -65,10 +65,9 @@ def filter_events_for_client(
             events
         always_include_ids (set(event_id)): set of event ids to specifically
             include (unless sender is ignored)
-        apply_retention_policies (bool): Whether to filter out events that's older than
-            allowed by the room's retention policy. Useful when this function is called
-            to e.g. check whether a user should be allowed to see the state at a given
-            event rather than to know if it should send an event to a user's client(s).
+        filter_send_to_client (bool): Whether we're checking an event that's going to be
+            sent to a client. This might not always be the case since this function can
+            also be called to check whether a user can see the state at a given point.
 
     Returns:
         Deferred[list[synapse.events.EventBase]]
@@ -96,7 +95,7 @@ def filter_events_for_client(
 
     erased_senders = yield storage.main.are_users_erased((e.sender for e in events))
 
-    if apply_retention_policies:
+    if filter_send_to_client:
         room_ids = {e.room_id for e in events}
         retention_policies = {}
 
@@ -119,30 +118,36 @@ def filter_events_for_client(
 
                the original event if they can see it as normal.
         """
-        if event.type == "org.matrix.dummy_event":
-            return None
-
-        if not event.is_state() and event.sender in ignore_list:
-            return None
-
-        # Until MSC2261 has landed we can't redact malicious alias events, so for
-        # now we temporarily filter out m.room.aliases entirely to mitigate
-        # abuse, while we spec a better solution to advertising aliases
-        # on rooms.
-        if event.type == EventTypes.Aliases:
-            return None
-
-        # Don't try to apply the room's retention policy if the event is a state event, as
-        # MSC1763 states that retention is only considered for non-state events.
-        if apply_retention_policies and not event.is_state():
-            retention_policy = retention_policies[event.room_id]
-            max_lifetime = retention_policy.get("max_lifetime")
-
-            if max_lifetime is not None:
-                oldest_allowed_ts = storage.main.clock.time_msec() - max_lifetime
-
-                if event.origin_server_ts < oldest_allowed_ts:
-                    return None
+        # Only run some checks if these events aren't about to be sent to clients. This is
+        # because, if this is not the case, we're probably only checking if the users can
+        # see events in the room at that point in the DAG, and that shouldn't be decided
+        # on those checks.
+        if filter_send_to_client:
+            if event.type == "org.matrix.dummy_event":
+                return None
+
+            if not event.is_state() and event.sender in ignore_list:
+                return None
+
+            # Until MSC2261 has landed we can't redact malicious alias events, so for
+            # now we temporarily filter out m.room.aliases entirely to mitigate
+            # abuse, while we spec a better solution to advertising aliases
+            # on rooms.
+            if event.type == EventTypes.Aliases:
+                return None
+
+            # Don't try to apply the room's retention policy if the event is a state
+            # event, as MSC1763 states that retention is only considered for non-state
+            # events.
+            if not event.is_state():
+                retention_policy = retention_policies[event.room_id]
+                max_lifetime = retention_policy.get("max_lifetime")
+
+                if max_lifetime is not None:
+                    oldest_allowed_ts = storage.main.clock.time_msec() - max_lifetime
+
+                    if event.origin_server_ts < oldest_allowed_ts:
+                        return None
 
         if event.event_id in always_include_ids:
             return event
diff --git a/tox.ini b/tox.ini
index 871810b3fc..24ff2cc0b7 100644
--- a/tox.ini
+++ b/tox.ini
@@ -185,6 +185,7 @@ commands = mypy \
             synapse/federation/federation_client.py \
             synapse/federation/sender \
             synapse/federation/transport \
+            synapse/handlers/auth.py \
             synapse/handlers/directory.py \
             synapse/handlers/presence.py \
             synapse/handlers/sync.py \