Make RateLimiter class check for ratelimit overrides (#9711)

This should fix a class of bug where we forget to check if e.g. the appservice shouldn't be ratelimited.

We also check the `ratelimit_override` table to check if the user has ratelimiting disabled. That table is really only meant to override the event sender ratelimiting, so we don't use any values from it (as they might not make sense for different rate limits), but we do infer that if ratelimiting is disabled for the user we should disabled all ratelimits.

Fixes #9663
This commit is contained in:
Erik Johnston 2021-03-30 12:06:09 +01:00 committed by GitHub
parent 3a446c21f8
commit 963f4309fe
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16 changed files with 241 additions and 154 deletions

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@ -17,6 +17,7 @@ from collections import OrderedDict
from typing import Hashable, Optional, Tuple
from synapse.api.errors import LimitExceededError
from synapse.storage.databases.main import DataStore
from synapse.types import Requester
from synapse.util import Clock
@ -31,10 +32,13 @@ class Ratelimiter:
burst_count: How many actions that can be performed before being limited.
"""
def __init__(self, clock: Clock, rate_hz: float, burst_count: int):
def __init__(
self, store: DataStore, clock: Clock, rate_hz: float, burst_count: int
):
self.clock = clock
self.rate_hz = rate_hz
self.burst_count = burst_count
self.store = store
# A ordered dictionary keeping track of actions, when they were last
# performed and how often. Each entry is a mapping from a key of arbitrary type
@ -46,45 +50,10 @@ class Ratelimiter:
OrderedDict()
) # type: OrderedDict[Hashable, Tuple[float, int, float]]
def can_requester_do_action(
async def can_do_action(
self,
requester: Requester,
rate_hz: Optional[float] = None,
burst_count: Optional[int] = None,
update: bool = True,
_time_now_s: Optional[int] = None,
) -> Tuple[bool, float]:
"""Can the requester perform the action?
Args:
requester: The requester to key off when rate limiting. The user property
will be used.
rate_hz: The long term number of actions that can be performed in a second.
Overrides the value set during instantiation if set.
burst_count: How many actions that can be performed before being limited.
Overrides the value set during instantiation if set.
update: Whether to count this check as performing the action
_time_now_s: The current time. Optional, defaults to the current time according
to self.clock. Only used by tests.
Returns:
A tuple containing:
* A bool indicating if they can perform the action now
* The reactor timestamp for when the action can be performed next.
-1 if rate_hz is less than or equal to zero
"""
# Disable rate limiting of users belonging to any AS that is configured
# not to be rate limited in its registration file (rate_limited: true|false).
if requester.app_service and not requester.app_service.is_rate_limited():
return True, -1.0
return self.can_do_action(
requester.user.to_string(), rate_hz, burst_count, update, _time_now_s
)
def can_do_action(
self,
key: Hashable,
requester: Optional[Requester],
key: Optional[Hashable] = None,
rate_hz: Optional[float] = None,
burst_count: Optional[int] = None,
update: bool = True,
@ -92,9 +61,16 @@ class Ratelimiter:
) -> Tuple[bool, float]:
"""Can the entity (e.g. user or IP address) perform the action?
Checks if the user has ratelimiting disabled in the database by looking
for null/zero values in the `ratelimit_override` table. (Non-zero
values aren't honoured, as they're specific to the event sending
ratelimiter, rather than all ratelimiters)
Args:
key: The key we should use when rate limiting. Can be a user ID
(when sending events), an IP address, etc.
requester: The requester that is doing the action, if any. Used to check
if the user has ratelimits disabled in the database.
key: An arbitrary key used to classify an action. Defaults to the
requester's user ID.
rate_hz: The long term number of actions that can be performed in a second.
Overrides the value set during instantiation if set.
burst_count: How many actions that can be performed before being limited.
@ -109,6 +85,30 @@ class Ratelimiter:
* The reactor timestamp for when the action can be performed next.
-1 if rate_hz is less than or equal to zero
"""
if key is None:
if not requester:
raise ValueError("Must supply at least one of `requester` or `key`")
key = requester.user.to_string()
if requester:
# Disable rate limiting of users belonging to any AS that is configured
# not to be rate limited in its registration file (rate_limited: true|false).
if requester.app_service and not requester.app_service.is_rate_limited():
return True, -1.0
# Check if ratelimiting has been disabled for the user.
#
# Note that we don't use the returned rate/burst count, as the table
# is specifically for the event sending ratelimiter. Instead, we
# only use it to (somewhat cheekily) infer whether the user should
# be subject to any rate limiting or not.
override = await self.store.get_ratelimit_for_user(
requester.authenticated_entity
)
if override and not override.messages_per_second:
return True, -1.0
# Override default values if set
time_now_s = _time_now_s if _time_now_s is not None else self.clock.time()
rate_hz = rate_hz if rate_hz is not None else self.rate_hz
@ -175,9 +175,10 @@ class Ratelimiter:
else:
del self.actions[key]
def ratelimit(
async def ratelimit(
self,
key: Hashable,
requester: Optional[Requester],
key: Optional[Hashable] = None,
rate_hz: Optional[float] = None,
burst_count: Optional[int] = None,
update: bool = True,
@ -185,8 +186,16 @@ class Ratelimiter:
):
"""Checks if an action can be performed. If not, raises a LimitExceededError
Checks if the user has ratelimiting disabled in the database by looking
for null/zero values in the `ratelimit_override` table. (Non-zero
values aren't honoured, as they're specific to the event sending
ratelimiter, rather than all ratelimiters)
Args:
key: An arbitrary key used to classify an action
requester: The requester that is doing the action, if any. Used to check for
if the user has ratelimits disabled.
key: An arbitrary key used to classify an action. Defaults to the
requester's user ID.
rate_hz: The long term number of actions that can be performed in a second.
Overrides the value set during instantiation if set.
burst_count: How many actions that can be performed before being limited.
@ -201,7 +210,8 @@ class Ratelimiter:
"""
time_now_s = _time_now_s if _time_now_s is not None else self.clock.time()
allowed, time_allowed = self.can_do_action(
allowed, time_allowed = await self.can_do_action(
requester,
key,
rate_hz=rate_hz,
burst_count=burst_count,