From 482d06774ac456943fb7e519a78431c82da305ca Mon Sep 17 00:00:00 2001 From: Matthew Hodgson Date: Tue, 15 Jan 2019 21:38:07 +0000 Subject: don't store remote device lists if they have more than 10K devices --- synapse/handlers/device.py | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) (limited to 'synapse/handlers/device.py') diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py index 6f80a7dce9..5bca62418e 100644 --- a/synapse/handlers/device.py +++ b/synapse/handlers/device.py @@ -533,18 +533,19 @@ class DeviceListEduUpdater(object): stream_id = result["stream_id"] devices = result["devices"] - # Emergency hack to prevent DoS from - # @bot:oliviervandertoorn.nl and @bot:matrix-beta.igalia.com - # on Jan 15 2019: only store the most recent 1000 devices for - # a given user. (We assume we receive them in chronological - # order, which is dubious given _get_e2e_device_keys_txn does - # not explicitly order its results). Otherwise it can take - # longer than 60s to persist the >100K devices, at which point - # the internal replication request to handle the - # m.device_list_update EDU times out, causing the remote - # server to retry the transaction and thus DoS synapse master - # CPU and DB. - devices = devices[-1000:] + # If the remote server has more than ~10000 devices for this user + # we assume that something is going horribly wrong (e.g. a bot + # that logs in and creates a new device every time it tries to + # send a message). Maintaining lots of devices per user in the + # cache can cause serious performance issues as if this request + # takes more than 60s to complete, internal replication from the + # inbound federation worker to the synapse master may time out + # causing the inbound federation to fail and causing the remote + # server to retry, causing a DoS. So in this scenario we give + # up on storing the total list of devices and only handle the + # delta instead. + if len(devices) > 10000: + devices = [] yield self.store.update_remote_device_list_cache( user_id, devices, stream_id, -- cgit 1.5.1