diff options
Diffstat (limited to 'synapse')
| -rw-r--r-- | synapse/handlers/e2e_keys.py | 36 | ||||
| -rw-r--r-- | synapse/rest/client/keys.py | 14 |
2 files changed, 48 insertions, 2 deletions
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py index 63e00f102e..1ece54ccfc 100644 --- a/synapse/handlers/e2e_keys.py +++ b/synapse/handlers/e2e_keys.py @@ -1476,6 +1476,42 @@ class E2eKeysHandler: else: return exists, self.clock.time_msec() < ts_replacable_without_uia_before + async def has_different_keys(self, user_id: str, body: JsonDict) -> bool: + """ + Check if a key provided in `body` differs from the same key stored in the DB. Returns + true on the first difference. If a key exists in `body` but does not exist in the DB, + returns True. If `body` has no keys, this always returns False. + Note by 'key' we mean Matrix key rather than JSON key. + + The purpose of this function is to detect whether or not we need to apply UIA checks. + We must apply UIA checks if any key in the database is being overwritten. If a key is + being inserted for the first time, or if the key exactly matches what is in the database, + then no UIA check needs to be performed. + + Args: + user_id: The user who sent the `body`. + body: The JSON request body from POST /keys/device_signing/upload + Returns: + True if any key in `body` has a different value in the database. + """ + # Ensure that each key provided in the request body exactly matches the one we have stored. + # The first time we see the DB having a different key to the matching request key, bail. + # Note: we do not care if the DB has a key which the request does not specify, as we only + # care about *replacements* or *insertions* (i.e UPSERT) + req_body_key_to_db_key = { + "master_key": "master", + "self_signing_key": "self_signing", + "user_signing_key": "user_signing", + } + for req_body_key, db_key in req_body_key_to_db_key.items(): + if req_body_key in body: + existing_key = await self.store.get_e2e_cross_signing_key( + user_id, db_key + ) + if existing_key != body[req_body_key]: + return True + return False + def _check_cross_signing_key( key: JsonDict, user_id: str, key_type: str, signing_key: Optional[VerifyKey] = None diff --git a/synapse/rest/client/keys.py b/synapse/rest/client/keys.py index b6d9ee074a..86c9515854 100644 --- a/synapse/rest/client/keys.py +++ b/synapse/rest/client/keys.py @@ -409,7 +409,18 @@ class SigningKeyUploadServlet(RestServlet): # But first-time setup is fine elif self.hs.config.experimental.msc3967_enabled: - # If we already have a master key then cross signing is set up and we require UIA to reset + # MSC3967 allows this endpoint to 200 OK for idempotency. Resending exactly the same + # keys should just 200 OK without doing a UIA prompt. + keys_are_different = await self.e2e_keys_handler.has_different_keys( + user_id, body + ) + if not keys_are_different: + # FIXME: we do not fallthrough to upload_signing_keys_for_user because confusingly + # if we do, we 500 as it looks like it tries to INSERT the same key twice, causing a + # unique key constraint violation. This sounds like a bug? + return 200, {} + # the keys are different, is x-signing set up? If no, then the keys don't exist which is + # why they are different. If yes, then we need to UIA to change them. if is_cross_signing_setup: await self.auth_handler.validate_user_via_ui_auth( requester, @@ -420,7 +431,6 @@ class SigningKeyUploadServlet(RestServlet): can_skip_ui_auth=False, ) # Otherwise we don't require UIA since we are setting up cross signing for first time - else: # Previous behaviour is to always require UIA but allow it to be skipped await self.auth_handler.validate_user_via_ui_auth( |