Merge tag 'v1.10.0rc2' into develop

Synapse 1.10.0rc2 (2020-02-06)
==============================

Bugfixes
--------

- Fix an issue with cross-signing where device signatures were not sent to remote servers. ([\#6844](https://github.com/matrix-org/synapse/issues/6844))
- Fix to the unknown remote device detection which was introduced in 1.10.rc1. ([\#6848](https://github.com/matrix-org/synapse/issues/6848))

Internal Changes
----------------

- Detect unexpected sender keys on remote encrypted events and resync device lists. ([\#6850](https://github.com/matrix-org/synapse/issues/6850))

8 files changed, 90 insertions, 23 deletions

diff --git a/CHANGES.md b/CHANGES.md
index ab6fce3e7d..c2aa735908 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,7 +1,23 @@
+Synapse 1.10.0rc2 (2020-02-06)
+==============================
+
+Bugfixes
+--------
+
+- Fix an issue with cross-signing where device signatures were not sent to remote servers. ([\#6844](https://github.com/matrix-org/synapse/issues/6844))
+- Fix to the unknown remote device detection which was introduced in 1.10.rc1. ([\#6848](https://github.com/matrix-org/synapse/issues/6848))
+
+
+Internal Changes
+----------------
+
+- Detect unexpected sender keys on remote encrypted events and resync device lists. ([\#6850](https://github.com/matrix-org/synapse/issues/6850))
+
+
 Synapse 1.10.0rc1 (2020-01-31)
 ==============================
 
-**WARNING**: As of this release Synapse validates `client_secret` parameters in the Client-Server API as per the spec. See [\#6766](https://github.com/matrix-org/synapse/issues/6766) for details.
+**WARNING to client developers**: As of this release Synapse validates `client_secret` parameters in the Client-Server API as per the spec. See [\#6766](https://github.com/matrix-org/synapse/issues/6766) for details.
 
 
 Features
diff --git a/synapse/__init__.py b/synapse/__init__.py
index bd942d3e1c..4f1859bd57 100644
--- a/synapse/__init__.py
+++ b/synapse/__init__.py
@@ -36,7 +36,7 @@ try:
 except ImportError:
     pass
 
-__version__ = "1.10.0rc1"
+__version__ = "1.10.0rc2"
 
 if bool(os.environ.get("SYNAPSE_TEST_PATCH_LOG_CONTEXTS", False)):
     # We import here so that we don't have to install a bunch of deps when
diff --git a/synapse/api/constants.py b/synapse/api/constants.py
index 0ade47e624..cc8577552b 100644
--- a/synapse/api/constants.py
+++ b/synapse/api/constants.py
@@ -77,12 +77,11 @@ class EventTypes(object):
     Aliases = "m.room.aliases"
     Redaction = "m.room.redaction"
     ThirdPartyInvite = "m.room.third_party_invite"
-    Encryption = "m.room.encryption"
     RelatedGroups = "m.room.related_groups"
 
     RoomHistoryVisibility = "m.room.history_visibility"
     CanonicalAlias = "m.room.canonical_alias"
-    Encryption = "m.room.encryption"
+    Encrypted = "m.room.encrypted"
     RoomAvatar = "m.room.avatar"
     RoomEncryption = "m.room.encryption"
     GuestAccess = "m.room.guest_access"
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index 26ef5e150c..a9bd431486 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -598,7 +598,13 @@ class DeviceListUpdater(object):
             # happens if we've missed updates.
             resync = yield self._need_to_do_resync(user_id, pending_updates)
 
-            logger.debug("Need to re-sync devices for %r? %r", user_id, resync)
+            if logger.isEnabledFor(logging.INFO):
+                logger.info(
+                    "Received device list update for %s, requiring resync: %s. Devices: %s",
+                    user_id,
+                    resync,
+                    ", ".join(u[0] for u in pending_updates),
+                )
 
             if resync:
                 yield self.user_device_resync(user_id)
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index 5728ea2ee7..8c6a142991 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -752,29 +752,75 @@ class FederationHandler(BaseHandler):
 
         # For encrypted messages we check that we know about the sending device,
         # if we don't then we mark the device cache for that user as stale.
-        if event.type == EventTypes.Encryption:
+        if event.type == EventTypes.Encrypted:
             device_id = event.content.get("device_id")
+            sender_key = event.content.get("sender_key")
+
+            cached_devices = await self.store.get_cached_devices_for_user(event.sender)
+
+            resync = False  # Whether we should resync device lists.
+
+            device = None
             if device_id is not None:
-                cached_devices = await self.store.get_cached_devices_for_user(
-                    event.sender
-                )
-                if device_id not in cached_devices:
+                device = cached_devices.get(device_id)
+                if device is None:
                     logger.info(
                         "Received event from remote device not in our cache: %s %s",
                         event.sender,
                         device_id,
                     )
-                    await self.store.mark_remote_user_device_cache_as_stale(
-                        event.sender
+                    resync = True
+
+            # We also check if the `sender_key` matches what we expect.
+            if sender_key is not None:
+                # Figure out what sender key we're expecting. If we know the
+                # device and recognize the algorithm then we can work out the
+                # exact key to expect. Otherwise check it matches any key we
+                # have for that device.
+                if device:
+                    keys = device.get("keys", {}).get("keys", {})
+
+                    if event.content.get("algorithm") == "m.megolm.v1.aes-sha2":
+                        # For this algorithm we expect a curve25519 key.
+                        key_name = "curve25519:%s" % (device_id,)
+                        current_keys = [keys.get(key_name)]
+                    else:
+                        # We don't know understand the algorithm, so we just
+                        # check it matches a key for the device.
+                        current_keys = keys.values()
+                elif device_id:
+                    # We don't have any keys for the device ID.
+                    current_keys = []
+                else:
+                    # The event didn't include a device ID, so we just look for
+                    # keys across all devices.
+                    current_keys = (
+                        key
+                        for device in cached_devices
+                        for key in device.get("keys", {}).get("keys", {}).values()
                     )
 
-                    # Immediately attempt a resync in the background
-                    if self.config.worker_app:
-                        return run_in_background(self._user_device_resync, event.sender)
-                    else:
-                        return run_in_background(
-                            self._device_list_updater.user_device_resync, event.sender
-                        )
+                # We now check that the sender key matches (one of) the expected
+                # keys.
+                if sender_key not in current_keys:
+                    logger.info(
+                        "Received event from remote device with unexpected sender key: %s %s: %s",
+                        event.sender,
+                        device_id or "<no device_id>",
+                        sender_key,
+                    )
+                    resync = True
+
+            if resync:
+                await self.store.mark_remote_user_device_cache_as_stale(event.sender)
+
+                # Immediately attempt a resync in the background
+                if self.config.worker_app:
+                    return run_in_background(self._user_device_resync, event.sender)
+                else:
+                    return run_in_background(
+                        self._device_list_updater.user_device_resync, event.sender
+                    )
 
     @log_function
     async def backfill(self, dest, room_id, limit, extremities):
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 1382399557..b609a65f47 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -360,7 +360,7 @@ class RoomCreationHandler(BaseHandler):
             (EventTypes.RoomHistoryVisibility, ""),
             (EventTypes.GuestAccess, ""),
             (EventTypes.RoomAvatar, ""),
-            (EventTypes.Encryption, ""),
+            (EventTypes.RoomEncryption, ""),
             (EventTypes.ServerACL, ""),
             (EventTypes.RelatedGroups, ""),
             (EventTypes.PowerLevels, ""),
diff --git a/synapse/handlers/stats.py b/synapse/handlers/stats.py
index 7f7d56390e..68e6edace5 100644
--- a/synapse/handlers/stats.py
+++ b/synapse/handlers/stats.py
@@ -286,7 +286,7 @@ class StatsHandler(StateDeltasHandler):
                 room_state["history_visibility"] = event_content.get(
                     "history_visibility"
                 )
-            elif typ == EventTypes.Encryption:
+            elif typ == EventTypes.RoomEncryption:
                 room_state["encryption"] = event_content.get("algorithm")
             elif typ == EventTypes.Name:
                 room_state["name"] = event_content.get("name")
diff --git a/synapse/storage/data_stores/main/stats.py b/synapse/storage/data_stores/main/stats.py
index 7bc186e9a1..7af1495e47 100644
--- a/synapse/storage/data_stores/main/stats.py
+++ b/synapse/storage/data_stores/main/stats.py
@@ -744,7 +744,7 @@ class StatsStore(StateDeltasStore):
                     EventTypes.Create,
                     EventTypes.JoinRules,
                     EventTypes.RoomHistoryVisibility,
-                    EventTypes.Encryption,
+                    EventTypes.RoomEncryption,
                     EventTypes.Name,
                     EventTypes.Topic,
                     EventTypes.RoomAvatar,
@@ -816,7 +816,7 @@ class StatsStore(StateDeltasStore):
                 room_state["history_visibility"] = event.content.get(
                     "history_visibility"
                 )
-            elif event.type == EventTypes.Encryption:
+            elif event.type == EventTypes.RoomEncryption:
                 room_state["encryption"] = event.content.get("algorithm")
             elif event.type == EventTypes.Name:
                 room_state["name"] = event.content.get("name")