From c2de2ca63060324cf2f80ddf3289b0fd7a4d861b Mon Sep 17 00:00:00 2001 From: Erik Johnston Date: Fri, 9 Dec 2022 09:37:07 +0000 Subject: [PATCH] Delete stale non-e2e devices for users, take 2 (#14595) This should help reduce the number of devices e.g. simple bots the repeatedly login rack up. We only delete non-e2e devices as they should be safe to delete, whereas if we delete e2e devices for a user we may accidentally break their ability to receive e2e keys for a message. --- changelog.d/14595.misc | 1 + synapse/handlers/device.py | 31 ++++++++- synapse/storage/databases/main/devices.py | 79 ++++++++++++++++++++++- tests/handlers/test_device.py | 2 +- tests/storage/test_client_ips.py | 4 +- 5 files changed, 113 insertions(+), 4 deletions(-) create mode 100644 changelog.d/14595.misc diff --git a/changelog.d/14595.misc b/changelog.d/14595.misc new file mode 100644 index 000000000..f9bfc581a --- /dev/null +++ b/changelog.d/14595.misc @@ -0,0 +1 @@ +Prune user's old devices on login if they have too many. diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py index d4750a32e..7674c187e 100644 --- a/synapse/handlers/device.py +++ b/synapse/handlers/device.py @@ -52,6 +52,7 @@ from synapse.util import stringutils from synapse.util.async_helpers import Linearizer from synapse.util.caches.expiringcache import ExpiringCache from synapse.util.cancellation import cancellable +from synapse.util.iterutils import batch_iter from synapse.util.metrics import measure_func from synapse.util.retryutils import NotRetryingDestination @@ -421,6 +422,9 @@ class DeviceHandler(DeviceWorkerHandler): self._check_device_name_length(initial_device_display_name) + # Prune the user's device list if they already have a lot of devices. + await self._prune_too_many_devices(user_id) + if device_id is not None: new_device = await self.store.store_device( user_id=user_id, @@ -452,6 +456,31 @@ class DeviceHandler(DeviceWorkerHandler): raise errors.StoreError(500, "Couldn't generate a device ID.") + async def _prune_too_many_devices(self, user_id: str) -> None: + """Delete any excess old devices this user may have.""" + device_ids = await self.store.check_too_many_devices_for_user(user_id) + if not device_ids: + return + + # We don't want to block and try and delete tonnes of devices at once, + # so we cap the number of devices we delete synchronously. + first_batch, remaining_device_ids = device_ids[:10], device_ids[10:] + await self.delete_devices(user_id, first_batch) + + if not remaining_device_ids: + return + + # Now spawn a background loop that deletes the rest. + async def _prune_too_many_devices_loop() -> None: + for batch in batch_iter(remaining_device_ids, 10): + await self.delete_devices(user_id, batch) + + await self.clock.sleep(1) + + run_as_background_process( + "_prune_too_many_devices_loop", _prune_too_many_devices_loop + ) + async def _delete_stale_devices(self) -> None: """Background task that deletes devices which haven't been accessed for more than a configured time period. @@ -481,7 +510,7 @@ class DeviceHandler(DeviceWorkerHandler): device_ids = [d for d in device_ids if d != except_device_id] await self.delete_devices(user_id, device_ids) - async def delete_devices(self, user_id: str, device_ids: List[str]) -> None: + async def delete_devices(self, user_id: str, device_ids: Collection[str]) -> None: """Delete several devices Args: diff --git a/synapse/storage/databases/main/devices.py b/synapse/storage/databases/main/devices.py index a5bb4d404..08ccd46a2 100644 --- a/synapse/storage/databases/main/devices.py +++ b/synapse/storage/databases/main/devices.py @@ -1569,6 +1569,72 @@ class DeviceBackgroundUpdateStore(SQLBaseStore): return rows + async def check_too_many_devices_for_user(self, user_id: str) -> List[str]: + """Check if the user has a lot of devices, and if so return the set of + devices we can prune. + + This does *not* return hidden devices or devices with E2E keys. + """ + + num_devices = await self.db_pool.simple_select_one_onecol( + table="devices", + keyvalues={"user_id": user_id, "hidden": False}, + retcol="COALESCE(COUNT(*), 0)", + desc="count_devices", + ) + + # We let users have up to ten devices without pruning. + if num_devices <= 10: + return [] + + # We prune everything older than N days. + max_last_seen = self._clock.time_msec() - 14 * 24 * 60 * 60 * 1000 + + if num_devices > 50: + # If the user has more than 50 devices, then we chose a last seen + # that ensures we keep at most 50 devices. + sql = """ + SELECT last_seen FROM devices + LEFT JOIN e2e_device_keys_json USING (user_id, device_id) + WHERE + user_id = ? + AND NOT hidden + AND last_seen IS NOT NULL + AND key_json IS NULL + ORDER BY last_seen DESC + LIMIT 1 + OFFSET 50 + """ + + rows = await self.db_pool.execute( + "check_too_many_devices_for_user_last_seen", None, sql, (user_id,) + ) + if rows: + max_last_seen = max(rows[0][0], max_last_seen) + + # Now fetch the devices to delete. + sql = """ + SELECT DISTINCT device_id FROM devices + LEFT JOIN e2e_device_keys_json USING (user_id, device_id) + WHERE + user_id = ? + AND NOT hidden + AND last_seen < ? + AND key_json IS NULL + ORDER BY last_seen + """ + + def check_too_many_devices_for_user_txn( + txn: LoggingTransaction, + ) -> List[str]: + txn.execute(sql, (user_id, max_last_seen)) + return [device_id for device_id, in txn] + + return await self.db_pool.runInteraction( + "check_too_many_devices_for_user", + check_too_many_devices_for_user_txn, + ) + class DeviceStore(DeviceWorkerStore, DeviceBackgroundUpdateStore): # Because we have write access, this will be a StreamIdGenerator @@ -1627,6 +1693,7 @@ class DeviceStore(DeviceWorkerStore, DeviceBackgroundUpdateStore): values={}, insertion_values={ "display_name": initial_device_display_name, + "last_seen": self._clock.time_msec(), "hidden": False, }, desc="store_device", @@ -1672,7 +1739,15 @@ class DeviceStore(DeviceWorkerStore, DeviceBackgroundUpdateStore): ) raise StoreError(500, "Problem storing device.") - async def delete_devices(self, user_id: str, device_ids: List[str]) -> None: + @cached(max_entries=0) + async def delete_device(self, user_id: str, device_id: str) -> None: + raise NotImplementedError() + + # Note: sometimes deleting rows out of `device_inbox` can take a long time, + # so we use a cache so that we deduplicate in flight requests to delete + # devices. + @cachedList(cached_method_name="delete_device", list_name="device_ids") + async def delete_devices(self, user_id: str, device_ids: Collection[str]) -> dict: """Deletes several devices. Args: @@ -1709,6 +1784,8 @@ class DeviceStore(DeviceWorkerStore, DeviceBackgroundUpdateStore): for device_id in device_ids: self.device_id_exists_cache.invalidate((user_id, device_id)) + return {} + async def update_device( self, user_id: str, device_id: str, new_display_name: Optional[str] = None ) -> None: diff --git a/tests/handlers/test_device.py b/tests/handlers/test_device.py index ce7525e29..a456bffd6 100644 --- a/tests/handlers/test_device.py +++ b/tests/handlers/test_device.py @@ -115,7 +115,7 @@ class DeviceTestCase(unittest.HomeserverTestCase): "device_id": "xyz", "display_name": "display 0", "last_seen_ip": None, - "last_seen_ts": None, + "last_seen_ts": 1000000, }, device_map["xyz"], ) diff --git a/tests/storage/test_client_ips.py b/tests/storage/test_client_ips.py index 49ad3c132..a9af1babe 100644 --- a/tests/storage/test_client_ips.py +++ b/tests/storage/test_client_ips.py @@ -169,6 +169,8 @@ class ClientIpStoreTestCase(unittest.HomeserverTestCase): ) ) + last_seen = self.clock.time_msec() + if after_persisting: # Trigger the storage loop self.reactor.advance(10) @@ -189,7 +191,7 @@ class ClientIpStoreTestCase(unittest.HomeserverTestCase): "device_id": device_id, "ip": None, "user_agent": None, - "last_seen": None, + "last_seen": last_seen, }, ], )