Allow capping a room's retention policy (#8104)

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Brendan Abolivier 2020-08-24 18:21:04 +01:00 committed by GitHub
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6 changed files with 132 additions and 112 deletions

1
changelog.d/8104.bugfix Normal file
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@ -0,0 +1 @@
Fix a bug introduced in v1.7.2 impacting message retention policies that would allow federated homeservers to dictate a retention period that's lower than the configured minimum allowed duration in the configuration file.

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@ -378,11 +378,10 @@ retention:
# min_lifetime: 1d
# max_lifetime: 1y
# Retention policy limits. If set, a user won't be able to send a
# 'm.room.retention' event which features a 'min_lifetime' or a 'max_lifetime'
# that's not within this range. This is especially useful in closed federations,
# in which server admins can make sure every federating server applies the same
# rules.
# Retention policy limits. If set, and the state of a room contains a
# 'm.room.retention' event in its state which contains a 'min_lifetime' or a
# 'max_lifetime' that's out of these bounds, Synapse will cap the room's policy
# to these limits when running purge jobs.
#
#allowed_lifetime_min: 1d
#allowed_lifetime_max: 1y
@ -408,12 +407,19 @@ retention:
# (e.g. every 12h), but not want that purge to be performed by a job that's
# iterating over every room it knows, which could be heavy on the server.
#
# If any purge job is configured, it is strongly recommended to have at least
# a single job with neither 'shortest_max_lifetime' nor 'longest_max_lifetime'
# set, or one job without 'shortest_max_lifetime' and one job without
# 'longest_max_lifetime' set. Otherwise some rooms might be ignored, even if
# 'allowed_lifetime_min' and 'allowed_lifetime_max' are set, because capping a
# room's policy to these values is done after the policies are retrieved from
# Synapse's database (which is done using the range specified in a purge job's
# configuration).
#
#purge_jobs:
# - shortest_max_lifetime: 1d
# longest_max_lifetime: 3d
# - longest_max_lifetime: 3d
# interval: 12h
# - shortest_max_lifetime: 3d
# longest_max_lifetime: 1y
# interval: 1d
# Inhibits the /requestToken endpoints from returning an error that might leak

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@ -961,11 +961,10 @@ class ServerConfig(Config):
# min_lifetime: 1d
# max_lifetime: 1y
# Retention policy limits. If set, a user won't be able to send a
# 'm.room.retention' event which features a 'min_lifetime' or a 'max_lifetime'
# that's not within this range. This is especially useful in closed federations,
# in which server admins can make sure every federating server applies the same
# rules.
# Retention policy limits. If set, and the state of a room contains a
# 'm.room.retention' event in its state which contains a 'min_lifetime' or a
# 'max_lifetime' that's out of these bounds, Synapse will cap the room's policy
# to these limits when running purge jobs.
#
#allowed_lifetime_min: 1d
#allowed_lifetime_max: 1y
@ -991,12 +990,19 @@ class ServerConfig(Config):
# (e.g. every 12h), but not want that purge to be performed by a job that's
# iterating over every room it knows, which could be heavy on the server.
#
# If any purge job is configured, it is strongly recommended to have at least
# a single job with neither 'shortest_max_lifetime' nor 'longest_max_lifetime'
# set, or one job without 'shortest_max_lifetime' and one job without
# 'longest_max_lifetime' set. Otherwise some rooms might be ignored, even if
# 'allowed_lifetime_min' and 'allowed_lifetime_max' are set, because capping a
# room's policy to these values is done after the policies are retrieved from
# Synapse's database (which is done using the range specified in a purge job's
# configuration).
#
#purge_jobs:
# - shortest_max_lifetime: 1d
# longest_max_lifetime: 3d
# - longest_max_lifetime: 3d
# interval: 12h
# - shortest_max_lifetime: 3d
# longest_max_lifetime: 1y
# interval: 1d
# Inhibits the /requestToken endpoints from returning an error that might leak

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@ -74,15 +74,14 @@ class EventValidator(object):
)
if event.type == EventTypes.Retention:
self._validate_retention(event, config)
self._validate_retention(event)
def _validate_retention(self, event, config):
def _validate_retention(self, event):
"""Checks that an event that defines the retention policy for a room respects the
boundaries imposed by the server's administrator.
format enforced by the spec.
Args:
event (FrozenEvent): The event to validate.
config (Config): The homeserver's configuration.
"""
min_lifetime = event.content.get("min_lifetime")
max_lifetime = event.content.get("max_lifetime")
@ -95,32 +94,6 @@ class EventValidator(object):
errcode=Codes.BAD_JSON,
)
if (
config.retention_allowed_lifetime_min is not None
and min_lifetime < config.retention_allowed_lifetime_min
):
raise SynapseError(
code=400,
msg=(
"'min_lifetime' can't be lower than the minimum allowed"
" value enforced by the server's administrator"
),
errcode=Codes.BAD_JSON,
)
if (
config.retention_allowed_lifetime_max is not None
and min_lifetime > config.retention_allowed_lifetime_max
):
raise SynapseError(
code=400,
msg=(
"'min_lifetime' can't be greater than the maximum allowed"
" value enforced by the server's administrator"
),
errcode=Codes.BAD_JSON,
)
if max_lifetime is not None:
if not isinstance(max_lifetime, int):
raise SynapseError(
@ -129,32 +102,6 @@ class EventValidator(object):
errcode=Codes.BAD_JSON,
)
if (
config.retention_allowed_lifetime_min is not None
and max_lifetime < config.retention_allowed_lifetime_min
):
raise SynapseError(
code=400,
msg=(
"'max_lifetime' can't be lower than the minimum allowed value"
" enforced by the server's administrator"
),
errcode=Codes.BAD_JSON,
)
if (
config.retention_allowed_lifetime_max is not None
and max_lifetime > config.retention_allowed_lifetime_max
):
raise SynapseError(
code=400,
msg=(
"'max_lifetime' can't be greater than the maximum allowed"
" value enforced by the server's administrator"
),
errcode=Codes.BAD_JSON,
)
if (
min_lifetime is not None
and max_lifetime is not None

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@ -82,6 +82,9 @@ class PaginationHandler(object):
self._retention_default_max_lifetime = hs.config.retention_default_max_lifetime
self._retention_allowed_lifetime_min = hs.config.retention_allowed_lifetime_min
self._retention_allowed_lifetime_max = hs.config.retention_allowed_lifetime_max
if hs.config.retention_enabled:
# Run the purge jobs described in the configuration file.
for job in hs.config.retention_purge_jobs:
@ -111,7 +114,7 @@ class PaginationHandler(object):
the range to handle (inclusive). If None, it means that the range has no
upper limit.
"""
# We want the storage layer to to include rooms with no retention policy in its
# We want the storage layer to include rooms with no retention policy in its
# return value only if a default retention policy is defined in the server's
# configuration and that policy's 'max_lifetime' is either lower (or equal) than
# max_ms or higher than min_ms (or both).
@ -152,13 +155,32 @@ class PaginationHandler(object):
)
continue
max_lifetime = retention_policy["max_lifetime"]
# If max_lifetime is None, it means that the room has no retention policy.
# Given we only retrieve such rooms when there's a default retention policy
# defined in the server's configuration, we can safely assume that's the
# case and use it for this room.
max_lifetime = (
retention_policy["max_lifetime"] or self._retention_default_max_lifetime
)
if max_lifetime is None:
# If max_lifetime is None, it means that include_null equals True,
# therefore we can safely assume that there is a default policy defined
# in the server's configuration.
max_lifetime = self._retention_default_max_lifetime
# Cap the effective max_lifetime to be within the range allowed in the
# config.
# We do this in two steps:
# 1. Make sure it's higher or equal to the minimum allowed value, and if
# it's not replace it with that value. This is because the server
# operator can be required to not delete information before a given
# time, e.g. to comply with freedom of information laws.
# 2. Make sure the resulting value is lower or equal to the maximum allowed
# value, and if it's not replace it with that value. This is because the
# server operator can be required to delete any data after a specific
# amount of time.
if self._retention_allowed_lifetime_min is not None:
max_lifetime = max(self._retention_allowed_lifetime_min, max_lifetime)
if self._retention_allowed_lifetime_max is not None:
max_lifetime = min(max_lifetime, self._retention_allowed_lifetime_max)
logger.debug("[purge] max_lifetime for room %s: %s", room_id, max_lifetime)
# Figure out what token we should start purging at.
ts = self.clock.time_msec() - max_lifetime

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@ -45,33 +45,16 @@ class RetentionTestCase(unittest.HomeserverTestCase):
}
self.hs = self.setup_test_homeserver(config=config)
return self.hs
def prepare(self, reactor, clock, homeserver):
self.user_id = self.register_user("user", "password")
self.token = self.login("user", "password")
def test_retention_state_event(self):
"""Tests that the server configuration can limit the values a user can set to the
room's retention policy.
"""
room_id = self.helper.create_room_as(self.user_id, tok=self.token)
self.helper.send_state(
room_id=room_id,
event_type=EventTypes.Retention,
body={"max_lifetime": one_day_ms * 4},
tok=self.token,
expect_code=400,
)
self.helper.send_state(
room_id=room_id,
event_type=EventTypes.Retention,
body={"max_lifetime": one_hour_ms},
tok=self.token,
expect_code=400,
)
self.store = self.hs.get_datastore()
self.serializer = self.hs.get_event_client_serializer()
self.clock = self.hs.get_clock()
def test_retention_event_purged_with_state_event(self):
"""Tests that expired events are correctly purged when the room's retention policy
@ -90,6 +73,36 @@ class RetentionTestCase(unittest.HomeserverTestCase):
self._test_retention_event_purged(room_id, one_day_ms * 1.5)
def test_retention_event_purged_with_state_event_outside_allowed(self):
"""Tests that the server configuration can override the policy for a room when
running the purge jobs.
"""
room_id = self.helper.create_room_as(self.user_id, tok=self.token)
# Set a max_lifetime higher than the maximum allowed value.
self.helper.send_state(
room_id=room_id,
event_type=EventTypes.Retention,
body={"max_lifetime": one_day_ms * 4},
tok=self.token,
)
# Check that the event is purged after waiting for the maximum allowed duration
# instead of the one specified in the room's policy.
self._test_retention_event_purged(room_id, one_day_ms * 1.5)
# Set a max_lifetime lower than the minimum allowed value.
self.helper.send_state(
room_id=room_id,
event_type=EventTypes.Retention,
body={"max_lifetime": one_hour_ms},
tok=self.token,
)
# Check that the event is purged after waiting for the minimum allowed duration
# instead of the one specified in the room's policy.
self._test_retention_event_purged(room_id, one_day_ms * 0.5)
def test_retention_event_purged_without_state_event(self):
"""Tests that expired events are correctly purged when the room's retention policy
is defined by the server's configuration's default retention policy.
@ -140,7 +153,27 @@ class RetentionTestCase(unittest.HomeserverTestCase):
# That event should be the second, not outdated event.
self.assertEqual(filtered_events[0].event_id, valid_event_id, filtered_events)
def _test_retention_event_purged(self, room_id, increment):
def _test_retention_event_purged(self, room_id: str, increment: float):
"""Run the following test scenario to test the message retention policy support:
1. Send event 1
2. Increment time by `increment`
3. Send event 2
4. Increment time by `increment`
5. Check that event 1 has been purged
6. Check that event 2 has not been purged
7. Check that state events that were sent before event 1 aren't purged.
The main reason for sending a second event is because currently Synapse won't
purge the latest message in a room because it would otherwise result in a lack of
forward extremities for this room. It's also a good thing to ensure the purge jobs
aren't too greedy and purge messages they shouldn't.
Args:
room_id: The ID of the room to test retention in.
increment: The number of milliseconds to advance the clock each time. Must be
defined so that events in the room aren't purged if they are `increment`
old but are purged if they are `increment * 2` old.
"""
# Get the create event to, later, check that we can still access it.
message_handler = self.hs.get_message_handler()
create_event = self.get_success(
@ -156,7 +189,7 @@ class RetentionTestCase(unittest.HomeserverTestCase):
expired_event_id = resp.get("event_id")
# Check that we can retrieve the event.
expired_event = self.get_event(room_id, expired_event_id)
expired_event = self.get_event(expired_event_id)
self.assertEqual(
expired_event.get("content", {}).get("body"), "1", expired_event
)
@ -174,26 +207,31 @@ class RetentionTestCase(unittest.HomeserverTestCase):
# one should still be kept.
self.reactor.advance(increment / 1000)
# Check that the event has been purged from the database.
self.get_event(room_id, expired_event_id, expected_code=404)
# Check that the first event has been purged from the database, i.e. that we
# can't retrieve it anymore, because it has expired.
self.get_event(expired_event_id, expect_none=True)
# Check that the event that hasn't been purged can still be retrieved.
valid_event = self.get_event(room_id, valid_event_id)
# Check that the event that hasn't expired can still be retrieved.
valid_event = self.get_event(valid_event_id)
self.assertEqual(valid_event.get("content", {}).get("body"), "2", valid_event)
# Check that we can still access state events that were sent before the event that
# has been purged.
self.get_event(room_id, create_event.event_id)
def get_event(self, room_id, event_id, expected_code=200):
url = "/_matrix/client/r0/rooms/%s/event/%s" % (room_id, event_id)
def get_event(self, event_id, expect_none=False):
event = self.get_success(self.store.get_event(event_id, allow_none=True))
request, channel = self.make_request("GET", url, access_token=self.token)
self.render(request)
if expect_none:
self.assertIsNone(event)
return {}
self.assertEqual(channel.code, expected_code, channel.result)
self.assertIsNotNone(event)
return channel.json_body
time_now = self.clock.time_msec()
serialized = self.get_success(self.serializer.serialize_event(event, time_now))
return serialized
class RetentionNoDefaultPolicyTestCase(unittest.HomeserverTestCase):