diff --git a/synapse/config/server.py b/synapse/config/server.py
index f200d0c1f1..a460cf25b4 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -489,6 +489,19 @@ class ServerConfig(Config):
# events with profile information that differ from the target's global profile.
self.allow_per_room_profiles = config.get("allow_per_room_profiles", True)
+ # The maximum size an avatar can have, in bytes.
+ self.max_avatar_size = config.get("max_avatar_size")
+ if self.max_avatar_size is not None:
+ self.max_avatar_size = self.parse_size(self.max_avatar_size)
+
+ # The MIME types allowed for an avatar.
+ self.allowed_avatar_mimetypes = config.get("allowed_avatar_mimetypes")
+ if self.allowed_avatar_mimetypes and not isinstance(
+ self.allowed_avatar_mimetypes,
+ list,
+ ):
+ raise ConfigError("allowed_avatar_mimetypes must be a list")
+
self.listeners = [parse_listener_def(x) for x in config.get("listeners", [])]
# no_tls is not really supported any more, but let's grandfather it in
@@ -1168,6 +1181,20 @@ class ServerConfig(Config):
#
#allow_per_room_profiles: false
+ # The largest allowed file size for a user avatar. Defaults to no restriction.
+ #
+ # Note that user avatar changes will not work if this is set without
+ # using Synapse's media repository.
+ #
+ #max_avatar_size: 10M
+
+ # The MIME types allowed for user avatars. Defaults to no restriction.
+ #
+ # Note that user avatar changes will not work if this is set without
+ # using Synapse's media repository.
+ #
+ #allowed_avatar_mimetypes: ["image/png", "image/jpeg", "image/gif"]
+
# How long to keep redacted events in unredacted form in the database. After
# this period redacted events get replaced with their redacted form in the DB.
#
diff --git a/synapse/handlers/profile.py b/synapse/handlers/profile.py
index 6b5a6ded8b..36e3ad2ba9 100644
--- a/synapse/handlers/profile.py
+++ b/synapse/handlers/profile.py
@@ -31,6 +31,8 @@ from synapse.types import (
create_requester,
get_domain_from_id,
)
+from synapse.util.caches.descriptors import cached
+from synapse.util.stringutils import parse_and_validate_mxc_uri
if TYPE_CHECKING:
from synapse.server import HomeServer
@@ -64,6 +66,11 @@ class ProfileHandler:
self.user_directory_handler = hs.get_user_directory_handler()
self.request_ratelimiter = hs.get_request_ratelimiter()
+ self.max_avatar_size = hs.config.server.max_avatar_size
+ self.allowed_avatar_mimetypes = hs.config.server.allowed_avatar_mimetypes
+
+ self.server_name = hs.config.server.server_name
+
if hs.config.worker.run_background_tasks:
self.clock.looping_call(
self._update_remote_profile_cache, self.PROFILE_UPDATE_MS
@@ -286,6 +293,9 @@ class ProfileHandler:
400, "Avatar URL is too long (max %i)" % (MAX_AVATAR_URL_LEN,)
)
+ if not await self.check_avatar_size_and_mime_type(new_avatar_url):
+ raise SynapseError(403, "This avatar is not allowed", Codes.FORBIDDEN)
+
avatar_url_to_set: Optional[str] = new_avatar_url
if new_avatar_url == "":
avatar_url_to_set = None
@@ -307,6 +317,63 @@ class ProfileHandler:
await self._update_join_states(requester, target_user)
+ @cached()
+ async def check_avatar_size_and_mime_type(self, mxc: str) -> bool:
+ """Check that the size and content type of the avatar at the given MXC URI are
+ within the configured limits.
+
+ Args:
+ mxc: The MXC URI at which the avatar can be found.
+
+ Returns:
+ A boolean indicating whether the file can be allowed to be set as an avatar.
+ """
+ if not self.max_avatar_size and not self.allowed_avatar_mimetypes:
+ return True
+
+ server_name, _, media_id = parse_and_validate_mxc_uri(mxc)
+
+ if server_name == self.server_name:
+ media_info = await self.store.get_local_media(media_id)
+ else:
+ media_info = await self.store.get_cached_remote_media(server_name, media_id)
+
+ if media_info is None:
+ # Both configuration options need to access the file's metadata, and
+ # retrieving remote avatars just for this becomes a bit of a faff, especially
+ # if e.g. the file is too big. It's also generally safe to assume most files
+ # used as avatar are uploaded locally, or if the upload didn't happen as part
+ # of a PUT request on /avatar_url that the file was at least previewed by the
+ # user locally (and therefore downloaded to the remote media cache).
+ logger.warning("Forbidding avatar change to %s: avatar not on server", mxc)
+ return False
+
+ if self.max_avatar_size:
+ # Ensure avatar does not exceed max allowed avatar size
+ if media_info["media_length"] > self.max_avatar_size:
+ logger.warning(
+ "Forbidding avatar change to %s: %d bytes is above the allowed size "
+ "limit",
+ mxc,
+ media_info["media_length"],
+ )
+ return False
+
+ if self.allowed_avatar_mimetypes:
+ # Ensure the avatar's file type is allowed
+ if (
+ self.allowed_avatar_mimetypes
+ and media_info["media_type"] not in self.allowed_avatar_mimetypes
+ ):
+ logger.warning(
+ "Forbidding avatar change to %s: mimetype %s not allowed",
+ mxc,
+ media_info["media_type"],
+ )
+ return False
+
+ return True
+
async def on_profile_query(self, args: JsonDict) -> JsonDict:
"""Handles federation profile query requests."""
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index 6aa910dd10..3dd5e1b6e4 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -590,6 +590,12 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
errcode=Codes.BAD_JSON,
)
+ if "avatar_url" in content:
+ if not await self.profile_handler.check_avatar_size_and_mime_type(
+ content["avatar_url"],
+ ):
+ raise SynapseError(403, "This avatar is not allowed", Codes.FORBIDDEN)
+
# The event content should *not* include the authorising user as
# it won't be properly signed. Strip it out since it might come
# back from a client updating a display name / avatar.
|
