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When joining a remote room limit the number of events we concurrently check signatures/hashes for (#10117)

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If we do hundreds of thousands at once the memory overhead can easily reach 500+ MB.
This commit is contained in:
Erik Johnston 2021-06-08 11:07:46 +01:00 committed by GitHub
parent a0101fc021
commit c842c581ed
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
5 changed files with 210 additions and 264 deletions
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1
changelog.d/10117.feature Normal file
View file

@ -0,0 +1 @@
Significantly reduce memory usage of joining large remote rooms.

46
synapse/crypto/keyring.py
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@ -233,41 +233,19 @@ class Keyring:
for server_name, json_object, validity_time in server_and_json
]
def verify_events_for_server(
self, server_and_events: Iterable[Tuple[str, EventBase, int]]
) -> List[defer.Deferred]:
"""Bulk verification of signatures on events.
Args:
server_and_events:
Iterable of `(server_name, event, validity_time)` tuples.
`server_name` is which server we are verifying the signature for
on the event.
`event` is the event that we'll verify the signatures of for
the given `server_name`.
`validity_time` is a timestamp at which the signing key must be
valid.
Returns:
List<Deferred[None]>: for each input triplet, a deferred indicating success
or failure to verify each event's signature for the given
server_name. The deferreds run their callbacks in the sentinel
logcontext.
"""
return [
run_in_background(
self.process_request,
VerifyJsonRequest.from_event(
server_name,
event,
validity_time,
),
async def verify_event_for_server(
self,
server_name: str,
event: EventBase,
validity_time: int,
) -> None:
await self.process_request(
VerifyJsonRequest.from_event(
server_name,
event,
validity_time,
)
for server_name, event, validity_time in server_and_events
]
)
async def process_request(self, verify_request: VerifyJsonRequest) -> None:
"""Processes the `VerifyJsonRequest`. Raises if the object is not signed

253
synapse/federation/federation_base.py
View file

@ -14,11 +14,6 @@
# limitations under the License.
import logging
from collections import namedtuple
from typing import Iterable, List
from twisted.internet import defer
from twisted.internet.defer import Deferred, DeferredList
from twisted.python.failure import Failure
from synapse.api.constants import MAX_DEPTH, EventTypes, Membership
from synapse.api.errors import Codes, SynapseError
@ -28,11 +23,6 @@ from synapse.crypto.keyring import Keyring
from synapse.events import EventBase, make_event_from_dict
from synapse.events.utils import prune_event, validate_canonicaljson
from synapse.http.servlet import assert_params_in_dict
from synapse.logging.context import (
PreserveLoggingContext,
current_context,
make_deferred_yieldable,
)
from synapse.types import JsonDict, get_domain_from_id
logger = logging.getLogger(__name__)
@ -48,112 +38,82 @@ class FederationBase:
self.store = hs.get_datastore()
self._clock = hs.get_clock()
def _check_sigs_and_hash(
async def _check_sigs_and_hash(
self, room_version: RoomVersion, pdu: EventBase
) -> Deferred:
return make_deferred_yieldable(
self._check_sigs_and_hashes(room_version, [pdu])[0]
)
def _check_sigs_and_hashes(
self, room_version: RoomVersion, pdus: List[EventBase]
) -> List[Deferred]:
"""Checks that each of the received events is correctly signed by the
sending server.
) -> EventBase:
"""Checks that event is correctly signed by the sending server.
Args:
room_version: The room version of the PDUs
pdus: the events to be checked
room_version: The room version of the PDU
pdu: the event to be checked
Returns:
For each input event, a deferred which:
* returns the original event if the checks pass
* returns a redacted version of the event (if the signature
* the original event if the checks pass
* a redacted version of the event (if the signature
matched but the hash did not)
* throws a SynapseError if the signature check failed.
The deferreds run their callbacks in the sentinel
"""
deferreds = _check_sigs_on_pdus(self.keyring, room_version, pdus)
ctx = current_context()
@defer.inlineCallbacks
def callback(_, pdu: EventBase):
with PreserveLoggingContext(ctx):
if not check_event_content_hash(pdu):
# let's try to distinguish between failures because the event was
# redacted (which are somewhat expected) vs actual ball-tampering
# incidents.
#
# This is just a heuristic, so we just assume that if the keys are
# about the same between the redacted and received events, then the
# received event was probably a redacted copy (but we then use our
# *actual* redacted copy to be on the safe side.)
redacted_event = prune_event(pdu)
if set(redacted_event.keys()) == set(pdu.keys()) and set(
redacted_event.content.keys()
) == set(pdu.content.keys()):
logger.info(
"Event %s seems to have been redacted; using our redacted "
"copy",
pdu.event_id,
)
else:
logger.warning(
"Event %s content has been tampered, redacting",
pdu.event_id,
)
return redacted_event
result = yield defer.ensureDeferred(
self.spam_checker.check_event_for_spam(pdu)
)
if result:
logger.warning(
"Event contains spam, redacting %s: %s",
pdu.event_id,
pdu.get_pdu_json(),
)
return prune_event(pdu)
return pdu
def errback(failure: Failure, pdu: EventBase):
failure.trap(SynapseError)
with PreserveLoggingContext(ctx):
logger.warning(
"Signature check failed for %s: %s",
pdu.event_id,
failure.getErrorMessage(),
)
return failure
for deferred, pdu in zip(deferreds, pdus):
deferred.addCallbacks(
callback, errback, callbackArgs=[pdu], errbackArgs=[pdu]
* throws a SynapseError if the signature check failed."""
try:
await _check_sigs_on_pdu(self.keyring, room_version, pdu)
except SynapseError as e:
logger.warning(
"Signature check failed for %s: %s",
pdu.event_id,
e,
)
raise
return deferreds
if not check_event_content_hash(pdu):
# let's try to distinguish between failures because the event was
# redacted (which are somewhat expected) vs actual ball-tampering
# incidents.
#
# This is just a heuristic, so we just assume that if the keys are
# about the same between the redacted and received events, then the
# received event was probably a redacted copy (but we then use our
# *actual* redacted copy to be on the safe side.)
redacted_event = prune_event(pdu)
if set(redacted_event.keys()) == set(pdu.keys()) and set(
redacted_event.content.keys()
) == set(pdu.content.keys()):
logger.info(
"Event %s seems to have been redacted; using our redacted copy",
pdu.event_id,
)
else:
logger.warning(
"Event %s content has been tampered, redacting",
pdu.event_id,
)
return redacted_event
result = await self.spam_checker.check_event_for_spam(pdu)
if result:
logger.warning(
"Event contains spam, redacting %s: %s",
pdu.event_id,
pdu.get_pdu_json(),
)
return prune_event(pdu)
return pdu
class PduToCheckSig(namedtuple("PduToCheckSig", ["pdu", "sender_domain", "deferreds"])):
pass
def _check_sigs_on_pdus(
keyring: Keyring, room_version: RoomVersion, pdus: Iterable[EventBase]
) -> List[Deferred]:
async def _check_sigs_on_pdu(
keyring: Keyring, room_version: RoomVersion, pdu: EventBase
) -> None:
"""Check that the given events are correctly signed
Raise a SynapseError if the event wasn't correctly signed.
Args:
keyring: keyring object to do the checks
room_version: the room version of the PDUs
pdus: the events to be checked
Returns:
A Deferred for each event in pdus, which will either succeed if
the signatures are valid, or fail (with a SynapseError) if not.
"""
# we want to check that the event is signed by:
@ -177,90 +137,47 @@ def _check_sigs_on_pdus(
# let's start by getting the domain for each pdu, and flattening the event back
# to JSON.
pdus_to_check = [
PduToCheckSig(
pdu=p,
sender_domain=get_domain_from_id(p.sender),
deferreds=[],
)
for p in pdus
]
# First we check that the sender event is signed by the sender's domain
# (except if its a 3pid invite, in which case it may be sent by any server)
pdus_to_check_sender = [p for p in pdus_to_check if not _is_invite_via_3pid(p.pdu)]
more_deferreds = keyring.verify_events_for_server(
[
(
p.sender_domain,
p.pdu,
p.pdu.origin_server_ts if room_version.enforce_key_validity else 0,
if not _is_invite_via_3pid(pdu):
try:
await keyring.verify_event_for_server(
get_domain_from_id(pdu.sender),
pdu,
pdu.origin_server_ts if room_version.enforce_key_validity else 0,
)
for p in pdus_to_check_sender
]
)
def sender_err(e, pdu_to_check):
errmsg = "event id %s: unable to verify signature for sender %s: %s" % (
pdu_to_check.pdu.event_id,
pdu_to_check.sender_domain,
e.getErrorMessage(),
)
raise SynapseError(403, errmsg, Codes.FORBIDDEN)
for p, d in zip(pdus_to_check_sender, more_deferreds):
d.addErrback(sender_err, p)
p.deferreds.append(d)
except Exception as e:
errmsg = "event id %s: unable to verify signature for sender %s: %s" % (
pdu.event_id,
get_domain_from_id(pdu.sender),
e,
)
raise SynapseError(403, errmsg, Codes.FORBIDDEN)
# now let's look for events where the sender's domain is different to the
# event id's domain (normally only the case for joins/leaves), and add additional
# checks. Only do this if the room version has a concept of event ID domain
# (ie, the room version uses old-style non-hash event IDs).
if room_version.event_format == EventFormatVersions.V1:
pdus_to_check_event_id = [
p
for p in pdus_to_check
if p.sender_domain != get_domain_from_id(p.pdu.event_id)
]
more_deferreds = keyring.verify_events_for_server(
[
(
get_domain_from_id(p.pdu.event_id),
p.pdu,
p.pdu.origin_server_ts if room_version.enforce_key_validity else 0,
)
for p in pdus_to_check_event_id
]
)
def event_err(e, pdu_to_check):
if room_version.event_format == EventFormatVersions.V1 and get_domain_from_id(
pdu.event_id
) != get_domain_from_id(pdu.sender):
try:
await keyring.verify_event_for_server(
get_domain_from_id(pdu.event_id),
pdu,
pdu.origin_server_ts if room_version.enforce_key_validity else 0,
)
except Exception as e:
errmsg = (
"event id %s: unable to verify signature for event id domain: %s"
% (pdu_to_check.pdu.event_id, e.getErrorMessage())
"event id %s: unable to verify signature for event id domain %s: %s"
% (
pdu.event_id,
get_domain_from_id(pdu.event_id),
e,
)
)
raise SynapseError(403, errmsg, Codes.FORBIDDEN)
for p, d in zip(pdus_to_check_event_id, more_deferreds):
d.addErrback(event_err, p)
p.deferreds.append(d)
# replace lists of deferreds with single Deferreds
return [_flatten_deferred_list(p.deferreds) for p in pdus_to_check]
def _flatten_deferred_list(deferreds: List[Deferred]) -> Deferred:
"""Given a list of deferreds, either return the single deferred,
combine into a DeferredList, or return an already resolved deferred.
"""
if len(deferreds) > 1:
return DeferredList(deferreds, fireOnOneErrback=True, consumeErrors=True)
elif len(deferreds) == 1:
return deferreds[0]
else:
return defer.succeed(None)
def _is_invite_via_3pid(event: EventBase) -> bool:
return (

153
synapse/federation/federation_client.py
View file

@ -21,6 +21,7 @@ from typing import (
Any,
Awaitable,
Callable,
Collection,
Dict,
Iterable,
List,
@ -35,9 +36,6 @@ from typing import (
import attr
from prometheus_client import Counter
from twisted.internet import defer
from twisted.internet.defer import Deferred
from synapse.api.constants import EventTypes, Membership
from synapse.api.errors import (
CodeMessageException,
@ -56,10 +54,9 @@ from synapse.api.room_versions import (
from synapse.events import EventBase, builder
from synapse.federation.federation_base import FederationBase, event_from_pdu_json
from synapse.federation.transport.client import SendJoinResponse
from synapse.logging.context import make_deferred_yieldable, preserve_fn
from synapse.logging.utils import log_function
from synapse.types import JsonDict, get_domain_from_id
from synapse.util import unwrapFirstError
from synapse.util.async_helpers import concurrently_execute
from synapse.util.caches.expiringcache import ExpiringCache
from synapse.util.retryutils import NotRetryingDestination
@ -360,10 +357,9 @@ class FederationClient(FederationBase):
async def _check_sigs_and_hash_and_fetch(
self,
origin: str,
pdus: List[EventBase],
pdus: Collection[EventBase],
room_version: RoomVersion,
outlier: bool = False,
include_none: bool = False,
) -> List[EventBase]:
"""Takes a list of PDUs and checks the signatures and hashes of each
one. If a PDU fails its signature check then we check if we have it in
@ -380,57 +376,87 @@ class FederationClient(FederationBase):
pdu
room_version
outlier: Whether the events are outliers or not
include_none: Whether to include None in the returned list
for events that have failed their checks
Returns:
A list of PDUs that have valid signatures and hashes.
"""
deferreds = self._check_sigs_and_hashes(room_version, pdus)
async def handle_check_result(pdu: EventBase, deferred: Deferred):
# We limit how many PDUs we check at once, as if we try to do hundreds
# of thousands of PDUs at once we see large memory spikes.
valid_pdus = []
async def _execute(pdu: EventBase) -> None:
valid_pdu = await self._check_sigs_and_hash_and_fetch_one(
pdu=pdu,
origin=origin,
outlier=outlier,
room_version=room_version,
)
if valid_pdu:
valid_pdus.append(valid_pdu)
await concurrently_execute(_execute, pdus, 10000)
return valid_pdus
async def _check_sigs_and_hash_and_fetch_one(
self,
pdu: EventBase,
origin: str,
room_version: RoomVersion,
outlier: bool = False,
) -> Optional[EventBase]:
"""Takes a PDU and checks its signatures and hashes. If the PDU fails
its signature check then we check if we have it in the database and if
not then request if from the originating server of that PDU.
If then PDU fails its content hash check then it is redacted.
Args:
origin
pdu
room_version
outlier: Whether the events are outliers or not
include_none: Whether to include None in the returned list
for events that have failed their checks
Returns:
The PDU (possibly redacted) if it has valid signatures and hashes.
"""
res = None
try:
res = await self._check_sigs_and_hash(room_version, pdu)
except SynapseError:
pass
if not res:
# Check local db.
res = await self.store.get_event(
pdu.event_id, allow_rejected=True, allow_none=True
)
pdu_origin = get_domain_from_id(pdu.sender)
if not res and pdu_origin != origin:
try:
res = await make_deferred_yieldable(deferred)
res = await self.get_pdu(
destinations=[pdu_origin],
event_id=pdu.event_id,
room_version=room_version,
outlier=outlier,
timeout=10000,
)
except SynapseError:
res = None
pass
if not res:
# Check local db.
res = await self.store.get_event(
pdu.event_id, allow_rejected=True, allow_none=True
)
if not res:
logger.warning(
"Failed to find copy of %s with valid signature", pdu.event_id
)
pdu_origin = get_domain_from_id(pdu.sender)
if not res and pdu_origin != origin:
try:
res = await self.get_pdu(
destinations=[pdu_origin],
event_id=pdu.event_id,
room_version=room_version,
outlier=outlier,
timeout=10000,
)
except SynapseError:
pass
if not res:
logger.warning(
"Failed to find copy of %s with valid signature", pdu.event_id
)
return res
handle = preserve_fn(handle_check_result)
deferreds2 = [handle(pdu, deferred) for pdu, deferred in zip(pdus, deferreds)]
valid_pdus = await make_deferred_yieldable(
defer.gatherResults(deferreds2, consumeErrors=True)
).addErrback(unwrapFirstError)
if include_none:
return valid_pdus
else:
return [p for p in valid_pdus if p]
return res
async def get_event_auth(
self, destination: str, room_id: str, event_id: str
@ -671,8 +697,6 @@ class FederationClient(FederationBase):
state = response.state
auth_chain = response.auth_events
pdus = {p.event_id: p for p in itertools.chain(state, auth_chain)}
create_event = None
for e in state:
if (e.type, e.state_key) == (EventTypes.Create, ""):
@ -696,14 +720,29 @@ class FederationClient(FederationBase):
% (create_room_version,)
)
valid_pdus = await self._check_sigs_and_hash_and_fetch(
destination,
list(pdus.values()),
outlier=True,
room_version=room_version,
logger.info(
"Processing from send_join %d events", len(state) + len(auth_chain)
)
valid_pdus_map = {p.event_id: p for p in valid_pdus}
# We now go and check the signatures and hashes for the event. Note
# that we limit how many events we process at a time to keep the
# memory overhead from exploding.
valid_pdus_map: Dict[str, EventBase] = {}
async def _execute(pdu: EventBase) -> None:
valid_pdu = await self._check_sigs_and_hash_and_fetch_one(
pdu=pdu,
origin=destination,
outlier=True,
room_version=room_version,
)
if valid_pdu:
valid_pdus_map[valid_pdu.event_id] = valid_pdu
await concurrently_execute(
_execute, itertools.chain(state, auth_chain), 10000
)
# NB: We *need* to copy to ensure that we don't have multiple
# references being passed on, as that causes... issues.

21
synapse/util/async_helpers.py
View file

@ -15,6 +15,7 @@
import collections
import inspect
import itertools
import logging
from contextlib import contextmanager
from typing import (
@ -160,8 +161,11 @@ class ObservableDeferred:
)
T = TypeVar("T")
def concurrently_execute(
func: Callable, args: Iterable[Any], limit: int
func: Callable[[T], Any], args: Iterable[T], limit: int
) -> defer.Deferred:
"""Executes the function with each argument concurrently while limiting
the number of concurrent executions.
@ -173,20 +177,27 @@ def concurrently_execute(
limit: Maximum number of conccurent executions.
Returns:
Deferred[list]: Resolved when all function invocations have finished.
Deferred: Resolved when all function invocations have finished.
"""
it = iter(args)
async def _concurrently_execute_inner():
async def _concurrently_execute_inner(value: T) -> None:
try:
while True:
await maybe_awaitable(func(next(it)))
await maybe_awaitable(func(value))
value = next(it)
except StopIteration:
pass
# We use `itertools.islice` to handle the case where the number of args is
# less than the limit, avoiding needlessly spawning unnecessary background
# tasks.
return make_deferred_yieldable(
defer.gatherResults(
[run_in_background(_concurrently_execute_inner) for _ in range(limit)],
[
run_in_background(_concurrently_execute_inner, value)
for value in itertools.islice(it, limit)
],
consumeErrors=True,
)
).addErrback(unwrapFirstError)