Merge tag 'v1.15.2'

Synapse 1.15.2 (2020-07-02)
===========================

Due to the two security issues highlighted below, server administrators are
encouraged to update Synapse. We are not aware of these vulnerabilities being
exploited in the wild.

Security advisory
-----------------

* A malicious homeserver could force Synapse to reset the state in a room to a
  small subset of the correct state. This affects all Synapse deployments which
  federate with untrusted servers. ([96e9afe6](https://github.com/matrix-org/synapse/commit/96e9afe62500310977dc3cbc99a8d16d3d2fa15c))
* HTML pages served via Synapse were vulnerable to clickjacking attacks. This
  predominantly affects homeservers with single-sign-on enabled, but all server
  administrators are encouraged to upgrade. ([ea26e9a9](https://github.com/matrix-org/synapse/commit/ea26e9a98b0541fc886a1cb826a38352b7599dbe))

  This was reported by [Quentin Gliech](https://sandhose.fr/).

6 files changed, 22 insertions, 53 deletions

diff --git a/synapse/rest/client/v1/pusher.py b/synapse/rest/client/v1/pusher.py
index 550a2f1b44..5f65cb7d83 100644
--- a/synapse/rest/client/v1/pusher.py
+++ b/synapse/rest/client/v1/pusher.py
@@ -16,7 +16,7 @@
 import logging
 
 from synapse.api.errors import Codes, StoreError, SynapseError
-from synapse.http.server import finish_request
+from synapse.http.server import respond_with_html_bytes
 from synapse.http.servlet import (
     RestServlet,
     assert_params_in_dict,
@@ -177,13 +177,9 @@ class PushersRemoveRestServlet(RestServlet):
 
         self.notifier.on_new_replication_data()
 
-        request.setResponseCode(200)
-        request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
-        request.setHeader(
-            b"Content-Length", b"%d" % (len(PushersRemoveRestServlet.SUCCESS_HTML),)
+        respond_with_html_bytes(
+            request, 200, PushersRemoveRestServlet.SUCCESS_HTML,
         )
-        request.write(PushersRemoveRestServlet.SUCCESS_HTML)
-        finish_request(request)
         return None
 
     def on_OPTIONS(self, _):
diff --git a/synapse/rest/client/v2_alpha/account.py b/synapse/rest/client/v2_alpha/account.py
index 1dc4a3247f..b58a77826f 100644
--- a/synapse/rest/client/v2_alpha/account.py
+++ b/synapse/rest/client/v2_alpha/account.py
@@ -21,7 +21,7 @@ from six.moves import http_client
 from synapse.api.constants import LoginType
 from synapse.api.errors import Codes, SynapseError, ThreepidValidationError
 from synapse.config.emailconfig import ThreepidBehaviour
-from synapse.http.server import finish_request
+from synapse.http.server import finish_request, respond_with_html
 from synapse.http.servlet import (
     RestServlet,
     assert_params_in_dict,
@@ -199,16 +199,15 @@ class PasswordResetSubmitTokenServlet(RestServlet):
 
             # Otherwise show the success template
             html = self.config.email_password_reset_template_success_html
-            request.setResponseCode(200)
+            status_code = 200
         except ThreepidValidationError as e:
-            request.setResponseCode(e.code)
+            status_code = e.code
 
             # Show a failure page with a reason
             template_vars = {"failure_reason": e.msg}
             html = self.failure_email_template.render(**template_vars)
 
-        request.write(html.encode("utf-8"))
-        finish_request(request)
+        respond_with_html(request, status_code, html)
 
 
 class PasswordRestServlet(RestServlet):
@@ -571,16 +570,15 @@ class AddThreepidEmailSubmitTokenServlet(RestServlet):
 
             # Otherwise show the success template
             html = self.config.email_add_threepid_template_success_html_content
-            request.setResponseCode(200)
+            status_code = 200
         except ThreepidValidationError as e:
-            request.setResponseCode(e.code)
+            status_code = e.code
 
             # Show a failure page with a reason
             template_vars = {"failure_reason": e.msg}
             html = self.failure_email_template.render(**template_vars)
 
-        request.write(html.encode("utf-8"))
-        finish_request(request)
+        respond_with_html(request, status_code, html)
 
 
 class AddThreepidMsisdnSubmitTokenServlet(RestServlet):
diff --git a/synapse/rest/client/v2_alpha/account_validity.py b/synapse/rest/client/v2_alpha/account_validity.py
index 2f10fa64e2..d06336ceea 100644
--- a/synapse/rest/client/v2_alpha/account_validity.py
+++ b/synapse/rest/client/v2_alpha/account_validity.py
@@ -16,7 +16,7 @@
 import logging
 
 from synapse.api.errors import AuthError, SynapseError
-from synapse.http.server import finish_request
+from synapse.http.server import respond_with_html
 from synapse.http.servlet import RestServlet
 
 from ._base import client_patterns
@@ -26,9 +26,6 @@ logger = logging.getLogger(__name__)
 
 class AccountValidityRenewServlet(RestServlet):
     PATTERNS = client_patterns("/account_validity/renew$")
-    SUCCESS_HTML = (
-        b"<html><body>Your account has been successfully renewed.</body><html>"
-    )
 
     def __init__(self, hs):
         """
@@ -59,11 +56,7 @@ class AccountValidityRenewServlet(RestServlet):
             status_code = 404
             response = self.failure_html
 
-        request.setResponseCode(status_code)
-        request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
-        request.setHeader(b"Content-Length", b"%d" % (len(response),))
-        request.write(response.encode("utf8"))
-        finish_request(request)
+        respond_with_html(request, status_code, response)
 
 
 class AccountValiditySendMailServlet(RestServlet):
diff --git a/synapse/rest/client/v2_alpha/auth.py b/synapse/rest/client/v2_alpha/auth.py
index 75590ebaeb..8e585e9153 100644
--- a/synapse/rest/client/v2_alpha/auth.py
+++ b/synapse/rest/client/v2_alpha/auth.py
@@ -18,7 +18,7 @@ import logging
 from synapse.api.constants import LoginType
 from synapse.api.errors import SynapseError
 from synapse.api.urls import CLIENT_API_PREFIX
-from synapse.http.server import finish_request
+from synapse.http.server import respond_with_html
 from synapse.http.servlet import RestServlet, parse_string
 
 from ._base import client_patterns
@@ -200,13 +200,7 @@ class AuthRestServlet(RestServlet):
             raise SynapseError(404, "Unknown auth stage type")
 
         # Render the HTML and return.
-        html_bytes = html.encode("utf8")
-        request.setResponseCode(200)
-        request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
-        request.setHeader(b"Content-Length", b"%d" % (len(html_bytes),))
-
-        request.write(html_bytes)
-        finish_request(request)
+        respond_with_html(request, 200, html)
         return None
 
     async def on_POST(self, request, stagetype):
@@ -263,13 +257,7 @@ class AuthRestServlet(RestServlet):
             raise SynapseError(404, "Unknown auth stage type")
 
         # Render the HTML and return.
-        html_bytes = html.encode("utf8")
-        request.setResponseCode(200)
-        request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
-        request.setHeader(b"Content-Length", b"%d" % (len(html_bytes),))
-
-        request.write(html_bytes)
-        finish_request(request)
+        respond_with_html(request, 200, html)
         return None
 
     def on_OPTIONS(self, _):
diff --git a/synapse/rest/client/v2_alpha/register.py b/synapse/rest/client/v2_alpha/register.py
index b9ffe86b2a..c8d2de7b54 100644
--- a/synapse/rest/client/v2_alpha/register.py
+++ b/synapse/rest/client/v2_alpha/register.py
@@ -38,7 +38,7 @@ from synapse.config.ratelimiting import FederationRateLimitConfig
 from synapse.config.registration import RegistrationConfig
 from synapse.config.server import is_threepid_reserved
 from synapse.handlers.auth import AuthHandler
-from synapse.http.server import finish_request
+from synapse.http.server import finish_request, respond_with_html
 from synapse.http.servlet import (
     RestServlet,
     assert_params_in_dict,
@@ -306,17 +306,15 @@ class RegistrationSubmitTokenServlet(RestServlet):
 
             # Otherwise show the success template
             html = self.config.email_registration_template_success_html_content
-
-            request.setResponseCode(200)
+            status_code = 200
         except ThreepidValidationError as e:
-            request.setResponseCode(e.code)
+            status_code = e.code
 
             # Show a failure page with a reason
             template_vars = {"failure_reason": e.msg}
             html = self.failure_email_template.render(**template_vars)
 
-        request.write(html.encode("utf-8"))
-        finish_request(request)
+        respond_with_html(request, status_code, html)
 
 
 class UsernameAvailabilityRestServlet(RestServlet):
diff --git a/synapse/rest/consent/consent_resource.py b/synapse/rest/consent/consent_resource.py
index 1ddf9997ff..4a20282d1b 100644
--- a/synapse/rest/consent/consent_resource.py
+++ b/synapse/rest/consent/consent_resource.py
@@ -29,7 +29,7 @@ from synapse.api.errors import NotFoundError, StoreError, SynapseError
 from synapse.config import ConfigError
 from synapse.http.server import (
     DirectServeResource,
-    finish_request,
+    respond_with_html,
     wrap_html_request_handler,
 )
 from synapse.http.servlet import parse_string
@@ -197,12 +197,8 @@ class ConsentResource(DirectServeResource):
         template_html = self._jinja_env.get_template(
             path.join(TEMPLATE_LANGUAGE, template_name)
         )
-        html_bytes = template_html.render(**template_args).encode("utf8")
-
-        request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
-        request.setHeader(b"Content-Length", b"%i" % len(html_bytes))
-        request.write(html_bytes)
-        finish_request(request)
+        html = template_html.render(**template_args)
+        respond_with_html(request, 200, html)
 
     def _check_hash(self, userid, userhmac):
         """