synapse-product/synapse/handlers/e2e_keys.py
Amber Brown 020add5099
Update black to 19.10b0 (#6304)
* update version of black and also fix the mypy config being overridden
2019-11-01 02:43:24 +11:00

1061 lines
41 KiB
Python

# -*- coding: utf-8 -*-
# Copyright 2016 OpenMarket Ltd
# Copyright 2018-2019 New Vector Ltd
# Copyright 2019 The Matrix.org Foundation C.I.C.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
from six import iteritems
import attr
from canonicaljson import encode_canonical_json, json
from signedjson.key import decode_verify_key_bytes
from signedjson.sign import SignatureVerifyException, verify_signed_json
from unpaddedbase64 import decode_base64
from twisted.internet import defer
from synapse.api.errors import CodeMessageException, Codes, NotFoundError, SynapseError
from synapse.logging.context import make_deferred_yieldable, run_in_background
from synapse.logging.opentracing import log_kv, set_tag, tag_args, trace
from synapse.types import (
UserID,
get_domain_from_id,
get_verify_key_from_cross_signing_key,
)
from synapse.util import unwrapFirstError
from synapse.util.retryutils import NotRetryingDestination
logger = logging.getLogger(__name__)
class E2eKeysHandler(object):
def __init__(self, hs):
self.store = hs.get_datastore()
self.federation = hs.get_federation_client()
self.device_handler = hs.get_device_handler()
self.is_mine = hs.is_mine
self.clock = hs.get_clock()
# doesn't really work as part of the generic query API, because the
# query request requires an object POST, but we abuse the
# "query handler" interface.
hs.get_federation_registry().register_query_handler(
"client_keys", self.on_federation_query_client_keys
)
@trace
@defer.inlineCallbacks
def query_devices(self, query_body, timeout, from_user_id):
""" Handle a device key query from a client
{
"device_keys": {
"<user_id>": ["<device_id>"]
}
}
->
{
"device_keys": {
"<user_id>": {
"<device_id>": {
...
}
}
}
}
Args:
from_user_id (str): the user making the query. This is used when
adding cross-signing signatures to limit what signatures users
can see.
"""
device_keys_query = query_body.get("device_keys", {})
# separate users by domain.
# make a map from domain to user_id to device_ids
local_query = {}
remote_queries = {}
for user_id, device_ids in device_keys_query.items():
# we use UserID.from_string to catch invalid user ids
if self.is_mine(UserID.from_string(user_id)):
local_query[user_id] = device_ids
else:
remote_queries[user_id] = device_ids
set_tag("local_key_query", local_query)
set_tag("remote_key_query", remote_queries)
# First get local devices.
failures = {}
results = {}
if local_query:
local_result = yield self.query_local_devices(local_query)
for user_id, keys in local_result.items():
if user_id in local_query:
results[user_id] = keys
# Now attempt to get any remote devices from our local cache.
remote_queries_not_in_cache = {}
if remote_queries:
query_list = []
for user_id, device_ids in iteritems(remote_queries):
if device_ids:
query_list.extend((user_id, device_id) for device_id in device_ids)
else:
query_list.append((user_id, None))
(
user_ids_not_in_cache,
remote_results,
) = yield self.store.get_user_devices_from_cache(query_list)
for user_id, devices in iteritems(remote_results):
user_devices = results.setdefault(user_id, {})
for device_id, device in iteritems(devices):
keys = device.get("keys", None)
device_display_name = device.get("device_display_name", None)
if keys:
result = dict(keys)
unsigned = result.setdefault("unsigned", {})
if device_display_name:
unsigned["device_display_name"] = device_display_name
user_devices[device_id] = result
for user_id in user_ids_not_in_cache:
domain = get_domain_from_id(user_id)
r = remote_queries_not_in_cache.setdefault(domain, {})
r[user_id] = remote_queries[user_id]
# Get cached cross-signing keys
cross_signing_keys = yield self.get_cross_signing_keys_from_cache(
device_keys_query, from_user_id
)
# Now fetch any devices that we don't have in our cache
@trace
@defer.inlineCallbacks
def do_remote_query(destination):
"""This is called when we are querying the device list of a user on
a remote homeserver and their device list is not in the device list
cache. If we share a room with this user and we're not querying for
specific user we will update the cache
with their device list."""
destination_query = remote_queries_not_in_cache[destination]
# We first consider whether we wish to update the device list cache with
# the users device list. We want to track a user's devices when the
# authenticated user shares a room with the queried user and the query
# has not specified a particular device.
# If we update the cache for the queried user we remove them from further
# queries. We use the more efficient batched query_client_keys for all
# remaining users
user_ids_updated = []
for (user_id, device_list) in destination_query.items():
if user_id in user_ids_updated:
continue
if device_list:
continue
room_ids = yield self.store.get_rooms_for_user(user_id)
if not room_ids:
continue
# We've decided we're sharing a room with this user and should
# probably be tracking their device lists. However, we haven't
# done an initial sync on the device list so we do it now.
try:
user_devices = yield self.device_handler.device_list_updater.user_device_resync(
user_id
)
user_devices = user_devices["devices"]
for device in user_devices:
results[user_id] = {device["device_id"]: device["keys"]}
user_ids_updated.append(user_id)
except Exception as e:
failures[destination] = _exception_to_failure(e)
if len(destination_query) == len(user_ids_updated):
# We've updated all the users in the query and we do not need to
# make any further remote calls.
return
# Remove all the users from the query which we have updated
for user_id in user_ids_updated:
destination_query.pop(user_id)
try:
remote_result = yield self.federation.query_client_keys(
destination, {"device_keys": destination_query}, timeout=timeout
)
for user_id, keys in remote_result["device_keys"].items():
if user_id in destination_query:
results[user_id] = keys
for user_id, key in remote_result["master_keys"].items():
if user_id in destination_query:
cross_signing_keys["master_keys"][user_id] = key
for user_id, key in remote_result["self_signing_keys"].items():
if user_id in destination_query:
cross_signing_keys["self_signing_keys"][user_id] = key
except Exception as e:
failure = _exception_to_failure(e)
failures[destination] = failure
set_tag("error", True)
set_tag("reason", failure)
yield make_deferred_yieldable(
defer.gatherResults(
[
run_in_background(do_remote_query, destination)
for destination in remote_queries_not_in_cache
],
consumeErrors=True,
).addErrback(unwrapFirstError)
)
ret = {"device_keys": results, "failures": failures}
ret.update(cross_signing_keys)
return ret
@defer.inlineCallbacks
def get_cross_signing_keys_from_cache(self, query, from_user_id):
"""Get cross-signing keys for users from the database
Args:
query (Iterable[string]) an iterable of user IDs. A dict whose keys
are user IDs satisfies this, so the query format used for
query_devices can be used here.
from_user_id (str): the user making the query. This is used when
adding cross-signing signatures to limit what signatures users
can see.
Returns:
defer.Deferred[dict[str, dict[str, dict]]]: map from
(master|self_signing|user_signing) -> user_id -> key
"""
master_keys = {}
self_signing_keys = {}
user_signing_keys = {}
for user_id in query:
# XXX: consider changing the store functions to allow querying
# multiple users simultaneously.
key = yield self.store.get_e2e_cross_signing_key(
user_id, "master", from_user_id
)
if key:
master_keys[user_id] = key
key = yield self.store.get_e2e_cross_signing_key(
user_id, "self_signing", from_user_id
)
if key:
self_signing_keys[user_id] = key
# users can see other users' master and self-signing keys, but can
# only see their own user-signing keys
if from_user_id == user_id:
key = yield self.store.get_e2e_cross_signing_key(
user_id, "user_signing", from_user_id
)
if key:
user_signing_keys[user_id] = key
return {
"master_keys": master_keys,
"self_signing_keys": self_signing_keys,
"user_signing_keys": user_signing_keys,
}
@trace
@defer.inlineCallbacks
def query_local_devices(self, query):
"""Get E2E device keys for local users
Args:
query (dict[string, list[string]|None): map from user_id to a list
of devices to query (None for all devices)
Returns:
defer.Deferred: (resolves to dict[string, dict[string, dict]]):
map from user_id -> device_id -> device details
"""
set_tag("local_query", query)
local_query = []
result_dict = {}
for user_id, device_ids in query.items():
# we use UserID.from_string to catch invalid user ids
if not self.is_mine(UserID.from_string(user_id)):
logger.warning("Request for keys for non-local user %s", user_id)
log_kv(
{
"message": "Requested a local key for a user which"
" was not local to the homeserver",
"user_id": user_id,
}
)
set_tag("error", True)
raise SynapseError(400, "Not a user here")
if not device_ids:
local_query.append((user_id, None))
else:
for device_id in device_ids:
local_query.append((user_id, device_id))
# make sure that each queried user appears in the result dict
result_dict[user_id] = {}
results = yield self.store.get_e2e_device_keys(local_query)
# Build the result structure
for user_id, device_keys in results.items():
for device_id, device_info in device_keys.items():
result_dict[user_id][device_id] = device_info
log_kv(results)
return result_dict
@defer.inlineCallbacks
def on_federation_query_client_keys(self, query_body):
""" Handle a device key query from a federated server
"""
device_keys_query = query_body.get("device_keys", {})
res = yield self.query_local_devices(device_keys_query)
return {"device_keys": res}
@trace
@defer.inlineCallbacks
def claim_one_time_keys(self, query, timeout):
local_query = []
remote_queries = {}
for user_id, device_keys in query.get("one_time_keys", {}).items():
# we use UserID.from_string to catch invalid user ids
if self.is_mine(UserID.from_string(user_id)):
for device_id, algorithm in device_keys.items():
local_query.append((user_id, device_id, algorithm))
else:
domain = get_domain_from_id(user_id)
remote_queries.setdefault(domain, {})[user_id] = device_keys
set_tag("local_key_query", local_query)
set_tag("remote_key_query", remote_queries)
results = yield self.store.claim_e2e_one_time_keys(local_query)
json_result = {}
failures = {}
for user_id, device_keys in results.items():
for device_id, keys in device_keys.items():
for key_id, json_bytes in keys.items():
json_result.setdefault(user_id, {})[device_id] = {
key_id: json.loads(json_bytes)
}
@trace
@defer.inlineCallbacks
def claim_client_keys(destination):
set_tag("destination", destination)
device_keys = remote_queries[destination]
try:
remote_result = yield self.federation.claim_client_keys(
destination, {"one_time_keys": device_keys}, timeout=timeout
)
for user_id, keys in remote_result["one_time_keys"].items():
if user_id in device_keys:
json_result[user_id] = keys
except Exception as e:
failure = _exception_to_failure(e)
failures[destination] = failure
set_tag("error", True)
set_tag("reason", failure)
yield make_deferred_yieldable(
defer.gatherResults(
[
run_in_background(claim_client_keys, destination)
for destination in remote_queries
],
consumeErrors=True,
)
)
logger.info(
"Claimed one-time-keys: %s",
",".join(
(
"%s for %s:%s" % (key_id, user_id, device_id)
for user_id, user_keys in iteritems(json_result)
for device_id, device_keys in iteritems(user_keys)
for key_id, _ in iteritems(device_keys)
)
),
)
log_kv({"one_time_keys": json_result, "failures": failures})
return {"one_time_keys": json_result, "failures": failures}
@defer.inlineCallbacks
@tag_args
def upload_keys_for_user(self, user_id, device_id, keys):
time_now = self.clock.time_msec()
# TODO: Validate the JSON to make sure it has the right keys.
device_keys = keys.get("device_keys", None)
if device_keys:
logger.info(
"Updating device_keys for device %r for user %s at %d",
device_id,
user_id,
time_now,
)
log_kv(
{
"message": "Updating device_keys for user.",
"user_id": user_id,
"device_id": device_id,
}
)
# TODO: Sign the JSON with the server key
changed = yield self.store.set_e2e_device_keys(
user_id, device_id, time_now, device_keys
)
if changed:
# Only notify about device updates *if* the keys actually changed
yield self.device_handler.notify_device_update(user_id, [device_id])
else:
log_kv({"message": "Not updating device_keys for user", "user_id": user_id})
one_time_keys = keys.get("one_time_keys", None)
if one_time_keys:
log_kv(
{
"message": "Updating one_time_keys for device.",
"user_id": user_id,
"device_id": device_id,
}
)
yield self._upload_one_time_keys_for_user(
user_id, device_id, time_now, one_time_keys
)
else:
log_kv(
{"message": "Did not update one_time_keys", "reason": "no keys given"}
)
# the device should have been registered already, but it may have been
# deleted due to a race with a DELETE request. Or we may be using an
# old access_token without an associated device_id. Either way, we
# need to double-check the device is registered to avoid ending up with
# keys without a corresponding device.
yield self.device_handler.check_device_registered(user_id, device_id)
result = yield self.store.count_e2e_one_time_keys(user_id, device_id)
set_tag("one_time_key_counts", result)
return {"one_time_key_counts": result}
@defer.inlineCallbacks
def _upload_one_time_keys_for_user(
self, user_id, device_id, time_now, one_time_keys
):
logger.info(
"Adding one_time_keys %r for device %r for user %r at %d",
one_time_keys.keys(),
device_id,
user_id,
time_now,
)
# make a list of (alg, id, key) tuples
key_list = []
for key_id, key_obj in one_time_keys.items():
algorithm, key_id = key_id.split(":")
key_list.append((algorithm, key_id, key_obj))
# First we check if we have already persisted any of the keys.
existing_key_map = yield self.store.get_e2e_one_time_keys(
user_id, device_id, [k_id for _, k_id, _ in key_list]
)
new_keys = [] # Keys that we need to insert. (alg, id, json) tuples.
for algorithm, key_id, key in key_list:
ex_json = existing_key_map.get((algorithm, key_id), None)
if ex_json:
if not _one_time_keys_match(ex_json, key):
raise SynapseError(
400,
(
"One time key %s:%s already exists. "
"Old key: %s; new key: %r"
)
% (algorithm, key_id, ex_json, key),
)
else:
new_keys.append(
(algorithm, key_id, encode_canonical_json(key).decode("ascii"))
)
log_kv({"message": "Inserting new one_time_keys.", "keys": new_keys})
yield self.store.add_e2e_one_time_keys(user_id, device_id, time_now, new_keys)
@defer.inlineCallbacks
def upload_signing_keys_for_user(self, user_id, keys):
"""Upload signing keys for cross-signing
Args:
user_id (string): the user uploading the keys
keys (dict[string, dict]): the signing keys
"""
# if a master key is uploaded, then check it. Otherwise, load the
# stored master key, to check signatures on other keys
if "master_key" in keys:
master_key = keys["master_key"]
_check_cross_signing_key(master_key, user_id, "master")
else:
master_key = yield self.store.get_e2e_cross_signing_key(user_id, "master")
# if there is no master key, then we can't do anything, because all the
# other cross-signing keys need to be signed by the master key
if not master_key:
raise SynapseError(400, "No master key available", Codes.MISSING_PARAM)
try:
master_key_id, master_verify_key = get_verify_key_from_cross_signing_key(
master_key
)
except ValueError:
if "master_key" in keys:
# the invalid key came from the request
raise SynapseError(400, "Invalid master key", Codes.INVALID_PARAM)
else:
# the invalid key came from the database
logger.error("Invalid master key found for user %s", user_id)
raise SynapseError(500, "Invalid master key")
# for the other cross-signing keys, make sure that they have valid
# signatures from the master key
if "self_signing_key" in keys:
self_signing_key = keys["self_signing_key"]
_check_cross_signing_key(
self_signing_key, user_id, "self_signing", master_verify_key
)
if "user_signing_key" in keys:
user_signing_key = keys["user_signing_key"]
_check_cross_signing_key(
user_signing_key, user_id, "user_signing", master_verify_key
)
# if everything checks out, then store the keys and send notifications
deviceids = []
if "master_key" in keys:
yield self.store.set_e2e_cross_signing_key(user_id, "master", master_key)
deviceids.append(master_verify_key.version)
if "self_signing_key" in keys:
yield self.store.set_e2e_cross_signing_key(
user_id, "self_signing", self_signing_key
)
try:
deviceids.append(
get_verify_key_from_cross_signing_key(self_signing_key)[1].version
)
except ValueError:
raise SynapseError(400, "Invalid self-signing key", Codes.INVALID_PARAM)
if "user_signing_key" in keys:
yield self.store.set_e2e_cross_signing_key(
user_id, "user_signing", user_signing_key
)
# the signature stream matches the semantics that we want for
# user-signing key updates: only the user themselves is notified of
# their own user-signing key updates
yield self.device_handler.notify_user_signature_update(user_id, [user_id])
# master key and self-signing key updates match the semantics of device
# list updates: all users who share an encrypted room are notified
if len(deviceids):
yield self.device_handler.notify_device_update(user_id, deviceids)
return {}
@defer.inlineCallbacks
def upload_signatures_for_device_keys(self, user_id, signatures):
"""Upload device signatures for cross-signing
Args:
user_id (string): the user uploading the signatures
signatures (dict[string, dict[string, dict]]): map of users to
devices to signed keys. This is the submission from the user; an
exception will be raised if it is malformed.
Returns:
dict: response to be sent back to the client. The response will have
a "failures" key, which will be a dict mapping users to devices
to errors for the signatures that failed.
Raises:
SynapseError: if the signatures dict is not valid.
"""
failures = {}
# signatures to be stored. Each item will be a SignatureListItem
signature_list = []
# split between checking signatures for own user and signatures for
# other users, since we verify them with different keys
self_signatures = signatures.get(user_id, {})
other_signatures = {k: v for k, v in signatures.items() if k != user_id}
self_signature_list, self_failures = yield self._process_self_signatures(
user_id, self_signatures
)
signature_list.extend(self_signature_list)
failures.update(self_failures)
other_signature_list, other_failures = yield self._process_other_signatures(
user_id, other_signatures
)
signature_list.extend(other_signature_list)
failures.update(other_failures)
# store the signature, and send the appropriate notifications for sync
logger.debug("upload signature failures: %r", failures)
yield self.store.store_e2e_cross_signing_signatures(user_id, signature_list)
self_device_ids = [item.target_device_id for item in self_signature_list]
if self_device_ids:
yield self.device_handler.notify_device_update(user_id, self_device_ids)
signed_users = [item.target_user_id for item in other_signature_list]
if signed_users:
yield self.device_handler.notify_user_signature_update(
user_id, signed_users
)
return {"failures": failures}
@defer.inlineCallbacks
def _process_self_signatures(self, user_id, signatures):
"""Process uploaded signatures of the user's own keys.
Signatures of the user's own keys from this API come in two forms:
- signatures of the user's devices by the user's self-signing key,
- signatures of the user's master key by the user's devices.
Args:
user_id (string): the user uploading the keys
signatures (dict[string, dict]): map of devices to signed keys
Returns:
(list[SignatureListItem], dict[string, dict[string, dict]]):
a list of signatures to store, and a map of users to devices to failure
reasons
Raises:
SynapseError: if the input is malformed
"""
signature_list = []
failures = {}
if not signatures:
return signature_list, failures
if not isinstance(signatures, dict):
raise SynapseError(400, "Invalid parameter", Codes.INVALID_PARAM)
try:
# get our self-signing key to verify the signatures
(
_,
self_signing_key_id,
self_signing_verify_key,
) = yield self._get_e2e_cross_signing_verify_key(user_id, "self_signing")
# get our master key, since we may have received a signature of it.
# We need to fetch it here so that we know what its key ID is, so
# that we can check if a signature that was sent is a signature of
# the master key or of a device
(
master_key,
_,
master_verify_key,
) = yield self._get_e2e_cross_signing_verify_key(user_id, "master")
# fetch our stored devices. This is used to 1. verify
# signatures on the master key, and 2. to compare with what
# was sent if the device was signed
devices = yield self.store.get_e2e_device_keys([(user_id, None)])
if user_id not in devices:
raise NotFoundError("No device keys found")
devices = devices[user_id]
except SynapseError as e:
failure = _exception_to_failure(e)
failures[user_id] = {device: failure for device in signatures.keys()}
return signature_list, failures
for device_id, device in signatures.items():
# make sure submitted data is in the right form
if not isinstance(device, dict):
raise SynapseError(400, "Invalid parameter", Codes.INVALID_PARAM)
try:
if "signatures" not in device or user_id not in device["signatures"]:
# no signature was sent
raise SynapseError(
400, "Invalid signature", Codes.INVALID_SIGNATURE
)
if device_id == master_verify_key.version:
# The signature is of the master key. This needs to be
# handled differently from signatures of normal devices.
master_key_signature_list = self._check_master_key_signature(
user_id, device_id, device, master_key, devices
)
signature_list.extend(master_key_signature_list)
continue
# at this point, we have a device that should be signed
# by the self-signing key
if self_signing_key_id not in device["signatures"][user_id]:
# no signature was sent
raise SynapseError(
400, "Invalid signature", Codes.INVALID_SIGNATURE
)
try:
stored_device = devices[device_id]
except KeyError:
raise NotFoundError("Unknown device")
if self_signing_key_id in stored_device.get("signatures", {}).get(
user_id, {}
):
# we already have a signature on this device, so we
# can skip it, since it should be exactly the same
continue
_check_device_signature(
user_id, self_signing_verify_key, device, stored_device
)
signature = device["signatures"][user_id][self_signing_key_id]
signature_list.append(
SignatureListItem(
self_signing_key_id, user_id, device_id, signature
)
)
except SynapseError as e:
failures.setdefault(user_id, {})[device_id] = _exception_to_failure(e)
return signature_list, failures
def _check_master_key_signature(
self, user_id, master_key_id, signed_master_key, stored_master_key, devices
):
"""Check signatures of a user's master key made by their devices.
Args:
user_id (string): the user whose master key is being checked
master_key_id (string): the ID of the user's master key
signed_master_key (dict): the user's signed master key that was uploaded
stored_master_key (dict): our previously-stored copy of the user's master key
devices (iterable(dict)): the user's devices
Returns:
list[SignatureListItem]: a list of signatures to store
Raises:
SynapseError: if a signature is invalid
"""
# for each device that signed the master key, check the signature.
master_key_signature_list = []
sigs = signed_master_key["signatures"]
for signing_key_id, signature in sigs[user_id].items():
_, signing_device_id = signing_key_id.split(":", 1)
if (
signing_device_id not in devices
or signing_key_id not in devices[signing_device_id]["keys"]
):
# signed by an unknown device, or the
# device does not have the key
raise SynapseError(400, "Invalid signature", Codes.INVALID_SIGNATURE)
# get the key and check the signature
pubkey = devices[signing_device_id]["keys"][signing_key_id]
verify_key = decode_verify_key_bytes(signing_key_id, decode_base64(pubkey))
_check_device_signature(
user_id, verify_key, signed_master_key, stored_master_key
)
master_key_signature_list.append(
SignatureListItem(signing_key_id, user_id, master_key_id, signature)
)
return master_key_signature_list
@defer.inlineCallbacks
def _process_other_signatures(self, user_id, signatures):
"""Process uploaded signatures of other users' keys. These will be the
target user's master keys, signed by the uploading user's user-signing
key.
Args:
user_id (string): the user uploading the keys
signatures (dict[string, dict]): map of users to devices to signed keys
Returns:
(list[SignatureListItem], dict[string, dict[string, dict]]):
a list of signatures to store, and a map of users to devices to failure
reasons
Raises:
SynapseError: if the input is malformed
"""
signature_list = []
failures = {}
if not signatures:
return signature_list, failures
try:
# get our user-signing key to verify the signatures
(
user_signing_key,
user_signing_key_id,
user_signing_verify_key,
) = yield self._get_e2e_cross_signing_verify_key(user_id, "user_signing")
except SynapseError as e:
failure = _exception_to_failure(e)
for user, devicemap in signatures.items():
failures[user] = {device_id: failure for device_id in devicemap.keys()}
return signature_list, failures
for target_user, devicemap in signatures.items():
# make sure submitted data is in the right form
if not isinstance(devicemap, dict):
raise SynapseError(400, "Invalid parameter", Codes.INVALID_PARAM)
for device in devicemap.values():
if not isinstance(device, dict):
raise SynapseError(400, "Invalid parameter", Codes.INVALID_PARAM)
device_id = None
try:
# get the target user's master key, to make sure it matches
# what was sent
(
master_key,
master_key_id,
_,
) = yield self._get_e2e_cross_signing_verify_key(
target_user, "master", user_id
)
# make sure that the target user's master key is the one that
# was signed (and no others)
device_id = master_key_id.split(":", 1)[1]
if device_id not in devicemap:
logger.debug(
"upload signature: could not find signature for device %s",
device_id,
)
# set device to None so that the failure gets
# marked on all the signatures
device_id = None
raise NotFoundError("Unknown device")
key = devicemap[device_id]
other_devices = [k for k in devicemap.keys() if k != device_id]
if other_devices:
# other devices were signed -- mark those as failures
logger.debug("upload signature: too many devices specified")
failure = _exception_to_failure(NotFoundError("Unknown device"))
failures[target_user] = {
device: failure for device in other_devices
}
if user_signing_key_id in master_key.get("signatures", {}).get(
user_id, {}
):
# we already have the signature, so we can skip it
continue
_check_device_signature(
user_id, user_signing_verify_key, key, master_key
)
signature = key["signatures"][user_id][user_signing_key_id]
signature_list.append(
SignatureListItem(
user_signing_key_id, target_user, device_id, signature
)
)
except SynapseError as e:
failure = _exception_to_failure(e)
if device_id is None:
failures[target_user] = {
device_id: failure for device_id in devicemap.keys()
}
else:
failures.setdefault(target_user, {})[device_id] = failure
return signature_list, failures
@defer.inlineCallbacks
def _get_e2e_cross_signing_verify_key(self, user_id, key_type, from_user_id=None):
"""Fetch the cross-signing public key from storage and interpret it.
Args:
user_id (str): the user whose key should be fetched
key_type (str): the type of key to fetch
from_user_id (str): the user that we are fetching the keys for.
This affects what signatures are fetched.
Returns:
dict, str, VerifyKey: the raw key data, the key ID, and the
signedjson verify key
Raises:
NotFoundError: if the key is not found
"""
key = yield self.store.get_e2e_cross_signing_key(
user_id, key_type, from_user_id
)
if key is None:
logger.debug("no %s key found for %s", key_type, user_id)
raise NotFoundError("No %s key found for %s" % (key_type, user_id))
key_id, verify_key = get_verify_key_from_cross_signing_key(key)
return key, key_id, verify_key
def _check_cross_signing_key(key, user_id, key_type, signing_key=None):
"""Check a cross-signing key uploaded by a user. Performs some basic sanity
checking, and ensures that it is signed, if a signature is required.
Args:
key (dict): the key data to verify
user_id (str): the user whose key is being checked
key_type (str): the type of key that the key should be
signing_key (VerifyKey): (optional) the signing key that the key should
be signed with. If omitted, signatures will not be checked.
"""
if (
key.get("user_id") != user_id
or key_type not in key.get("usage", [])
or len(key.get("keys", {})) != 1
):
raise SynapseError(400, ("Invalid %s key" % (key_type,)), Codes.INVALID_PARAM)
if signing_key:
try:
verify_signed_json(key, user_id, signing_key)
except SignatureVerifyException:
raise SynapseError(
400, ("Invalid signature on %s key" % key_type), Codes.INVALID_SIGNATURE
)
def _check_device_signature(user_id, verify_key, signed_device, stored_device):
"""Check that a signature on a device or cross-signing key is correct and
matches the copy of the device/key that we have stored. Throws an
exception if an error is detected.
Args:
user_id (str): the user ID whose signature is being checked
verify_key (VerifyKey): the key to verify the device with
signed_device (dict): the uploaded signed device data
stored_device (dict): our previously stored copy of the device
Raises:
SynapseError: if the signature was invalid or the sent device is not the
same as the stored device
"""
# make sure that the device submitted matches what we have stored
stripped_signed_device = {
k: v for k, v in signed_device.items() if k not in ["signatures", "unsigned"]
}
stripped_stored_device = {
k: v for k, v in stored_device.items() if k not in ["signatures", "unsigned"]
}
if stripped_signed_device != stripped_stored_device:
logger.debug(
"upload signatures: key does not match %s vs %s",
signed_device,
stored_device,
)
raise SynapseError(400, "Key does not match")
try:
verify_signed_json(signed_device, user_id, verify_key)
except SignatureVerifyException:
logger.debug("invalid signature on key")
raise SynapseError(400, "Invalid signature", Codes.INVALID_SIGNATURE)
def _exception_to_failure(e):
if isinstance(e, SynapseError):
return {"status": e.code, "errcode": e.errcode, "message": str(e)}
if isinstance(e, CodeMessageException):
return {"status": e.code, "message": str(e)}
if isinstance(e, NotRetryingDestination):
return {"status": 503, "message": "Not ready for retry"}
# include ConnectionRefused and other errors
#
# Note that some Exceptions (notably twisted's ResponseFailed etc) don't
# give a string for e.message, which json then fails to serialize.
return {"status": 503, "message": str(e)}
def _one_time_keys_match(old_key_json, new_key):
old_key = json.loads(old_key_json)
# if either is a string rather than an object, they must match exactly
if not isinstance(old_key, dict) or not isinstance(new_key, dict):
return old_key == new_key
# otherwise, we strip off the 'signatures' if any, because it's legitimate
# for different upload attempts to have different signatures.
old_key.pop("signatures", None)
new_key_copy = dict(new_key)
new_key_copy.pop("signatures", None)
return old_key == new_key_copy
@attr.s
class SignatureListItem:
"""An item in the signature list as used by upload_signatures_for_device_keys.
"""
signing_key_id = attr.ib()
target_user_id = attr.ib()
target_device_id = attr.ib()
signature = attr.ib()