diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py
index be675197f1..5ea54f60be 100644
--- a/synapse/handlers/e2e_keys.py
+++ b/synapse/handlers/e2e_keys.py
@@ -19,12 +19,15 @@ 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, SynapseError
+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 (
@@ -602,6 +605,339 @@ class E2eKeysHandler(object):
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
@@ -630,7 +966,49 @@ def _check_cross_signing_key(key, user_id, key_type, signing_key=None):
)
+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)}
@@ -658,3 +1036,14 @@ def _one_time_keys_match(old_key_json, 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()
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