Reject mentions on the C-S API which are invalid. (#15311)

Invalid mentions data received over the Client-Server API should
be rejected with a 400 error. This will hopefully stop clients from
sending invalid data, although does not help with data received
over federation.
This commit is contained in:
Patrick Cloke 2023-03-24 08:31:14 -04:00 committed by GitHub
parent e6af49fbea
commit 68a6717312
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4 changed files with 105 additions and 54 deletions

1
changelog.d/15311.misc Normal file
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@ -0,0 +1 @@
Reject events with an invalid "mentions" property pert [MSC3952](https://github.com/matrix-org/matrix-spec-proposals/pull/3952).

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@ -12,11 +12,17 @@
# See the License for the specific language governing permissions and
# limitations under the License.
import collections.abc
from typing import Iterable, Type, Union, cast
from typing import Iterable, List, Type, Union, cast
import jsonschema
from pydantic import Field, StrictBool, StrictStr
from synapse.api.constants import MAX_ALIAS_LENGTH, EventTypes, Membership
from synapse.api.constants import (
MAX_ALIAS_LENGTH,
EventContentFields,
EventTypes,
Membership,
)
from synapse.api.errors import Codes, SynapseError
from synapse.api.room_versions import EventFormatVersions
from synapse.config.homeserver import HomeServerConfig
@ -28,6 +34,8 @@ from synapse.events.utils import (
validate_canonicaljson,
)
from synapse.federation.federation_server import server_matches_acl_event
from synapse.http.servlet import validate_json_object
from synapse.rest.models import RequestBodyModel
from synapse.types import EventID, JsonDict, RoomID, UserID
@ -88,27 +96,27 @@ class EventValidator:
Codes.INVALID_PARAM,
)
if event.type == EventTypes.Retention:
elif event.type == EventTypes.Retention:
self._validate_retention(event)
if event.type == EventTypes.ServerACL:
elif event.type == EventTypes.ServerACL:
if not server_matches_acl_event(config.server.server_name, event):
raise SynapseError(
400, "Can't create an ACL event that denies the local server"
)
if event.type == EventTypes.PowerLevels:
elif event.type == EventTypes.PowerLevels:
try:
jsonschema.validate(
instance=event.content,
schema=POWER_LEVELS_SCHEMA,
cls=plValidator,
cls=POWER_LEVELS_VALIDATOR,
)
except jsonschema.ValidationError as e:
if e.path:
# example: "users_default": '0' is not of type 'integer'
# cast safety: path entries can be integers, if we fail to validate
# items in an array. However the POWER_LEVELS_SCHEMA doesn't expect
# items in an array. However, the POWER_LEVELS_SCHEMA doesn't expect
# to see any arrays.
message = (
'"' + cast(str, e.path[-1]) + '": ' + e.message # noqa: B306
@ -125,6 +133,15 @@ class EventValidator:
errcode=Codes.BAD_JSON,
)
# If the event contains a mentions key, validate it.
if (
EventContentFields.MSC3952_MENTIONS in event.content
and config.experimental.msc3952_intentional_mentions
):
validate_json_object(
event.content[EventContentFields.MSC3952_MENTIONS], Mentions
)
def _validate_retention(self, event: EventBase) -> None:
"""Checks that an event that defines the retention policy for a room respects the
format enforced by the spec.
@ -253,10 +270,15 @@ POWER_LEVELS_SCHEMA = {
}
class Mentions(RequestBodyModel):
user_ids: List[StrictStr] = Field(default_factory=list)
room: StrictBool = False
# This could return something newer than Draft 7, but that's the current "latest"
# validator.
def _create_power_level_validator() -> Type[jsonschema.Draft7Validator]:
validator = jsonschema.validators.validator_for(POWER_LEVELS_SCHEMA)
def _create_validator(schema: JsonDict) -> Type[jsonschema.Draft7Validator]:
validator = jsonschema.validators.validator_for(schema)
# by default jsonschema does not consider a immutabledict to be an object so
# we need to use a custom type checker
@ -268,4 +290,4 @@ def _create_power_level_validator() -> Type[jsonschema.Draft7Validator]:
return jsonschema.validators.extend(validator, type_checker=type_checker)
plValidator = _create_power_level_validator()
POWER_LEVELS_VALIDATOR = _create_validator(POWER_LEVELS_SCHEMA)

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@ -778,17 +778,13 @@ def parse_json_object_from_request(
Model = TypeVar("Model", bound=BaseModel)
def parse_and_validate_json_object_from_request(
request: Request, model_type: Type[Model]
) -> Model:
"""Parse a JSON object from the body of a twisted HTTP request, then deserialise and
validate using the given pydantic model.
def validate_json_object(content: JsonDict, model_type: Type[Model]) -> Model:
"""Validate a deserialized JSON object using the given pydantic model.
Raises:
SynapseError if the request body couldn't be decoded as JSON or
if it wasn't a JSON object.
"""
content = parse_json_object_from_request(request, allow_empty_body=False)
try:
instance = model_type.parse_obj(content)
except ValidationError as e:
@ -811,6 +807,20 @@ def parse_and_validate_json_object_from_request(
return instance
def parse_and_validate_json_object_from_request(
request: Request, model_type: Type[Model]
) -> Model:
"""Parse a JSON object from the body of a twisted HTTP request, then deserialise and
validate using the given pydantic model.
Raises:
SynapseError if the request body couldn't be decoded as JSON or
if it wasn't a JSON object.
"""
content = parse_json_object_from_request(request, allow_empty_body=False)
return validate_json_object(content, model_type)
def assert_params_in_dict(body: JsonDict, required: Iterable[str]) -> None:
absent = []
for k in required:

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@ -243,6 +243,12 @@ class TestBulkPushRuleEvaluator(HomeserverTestCase):
)
# Non-dict mentions should be ignored.
#
# Avoid C-S validation as these aren't expected.
with patch(
"synapse.events.validator.EventValidator.validate_new",
new=lambda s, event, config: True,
):
mentions: Any
for mentions in (None, True, False, 1, "foo", []):
self.assertFalse(
@ -291,6 +297,12 @@ class TestBulkPushRuleEvaluator(HomeserverTestCase):
)
# Invalid entries in the list are ignored.
#
# Avoid C-S validation as these aren't expected.
with patch(
"synapse.events.validator.EventValidator.validate_new",
new=lambda s, event, config: True,
):
self.assertFalse(
self._create_and_process(
bulk_evaluator,
@ -351,6 +363,12 @@ class TestBulkPushRuleEvaluator(HomeserverTestCase):
)
# Invalid data should not notify.
#
# Avoid C-S validation as these aren't expected.
with patch(
"synapse.events.validator.EventValidator.validate_new",
new=lambda s, event, config: True,
):
mentions: Any
for mentions in (None, False, 1, "foo", [], {}):
self.assertFalse(