Keep around the old (buggy) version of the prune_event function so that we can use it to check signatures for events on old servers

synapse/api/auth.py

@@ -102,8 +102,6 @@ class Auth(object):
     def check_host_in_room(self, room_id, host):
         curr_state = yield self.state.get_current_state(room_id)
 
-        logger.debug("Got curr_state %s", curr_state)
-
         for event in curr_state:
             if event.type == EventTypes.Member:
                 try:

synapse/events/utils.py

@@ -94,6 +94,85 @@ def prune_event(event):
     )
 
 
+def old_prune_event(event):
+    """This is an old and buggy version of the prune event function. The
+    difference between this and the new version is that when including dicts
+    in the content they were included as frozen_dicts rather than dicts. This
+    caused the JSON encoder to encode as a list of the keys rather than the
+    dict.
+    """
+    event_type = event.type
+
+    allowed_keys = [
+        "event_id",
+        "sender",
+        "room_id",
+        "hashes",
+        "signatures",
+        "content",
+        "type",
+        "state_key",
+        "depth",
+        "prev_events",
+        "prev_state",
+        "auth_events",
+        "origin",
+        "origin_server_ts",
+        "membership",
+    ]
+
+    event_dict = event.get_dict()
+
+    new_content = {}
+
+    def add_fields(*fields):
+        for field in fields:
+            if field in event.content:
+                # This is the line that is buggy: event.content may return
+                # a frozen_dict which the json encoders encode as lists rather
+                # than dicts.
+                new_content[field] = event.content[field]
+
+    if event_type == EventTypes.Member:
+        add_fields("membership")
+    elif event_type == EventTypes.Create:
+        add_fields("creator")
+    elif event_type == EventTypes.JoinRules:
+        add_fields("join_rule")
+    elif event_type == EventTypes.PowerLevels:
+        add_fields(
+            "users",
+            "users_default",
+            "events",
+            "events_default",
+            "events_default",
+            "state_default",
+            "ban",
+            "kick",
+            "redact",
+        )
+    elif event_type == EventTypes.Aliases:
+        add_fields("aliases")
+
+    allowed_fields = {
+        k: v
+        for k, v in event_dict.items()
+        if k in allowed_keys
+    }
+
+    allowed_fields["content"] = new_content
+
+    allowed_fields["unsigned"] = {}
+
+    if "age_ts" in event.unsigned:
+        allowed_fields["unsigned"]["age_ts"] = event.unsigned["age_ts"]
+
+    return type(event)(
+        allowed_fields,
+        internal_metadata_dict=event.internal_metadata.get_dict()
+    )
+
+
 def format_event_raw(d):
     return d
 

synapse/federation/federation_client.py

@@ -16,17 +16,11 @@
 
 from twisted.internet import defer
 
+from .federation_base import FederationBase
 from .units import Edu
 
 from synapse.util.logutils import log_function
 from synapse.events import FrozenEvent
-from synapse.events.utils import prune_event
-
-from syutil.jsonutil import encode_canonical_json
-
-from synapse.crypto.event_signing import check_event_content_hash
-
-from synapse.api.errors import SynapseError
 
 import logging
 
@@ -34,7 +28,7 @@ import logging
 logger = logging.getLogger(__name__)
 
 
-class FederationClient(object):
+class FederationClient(FederationBase):
     @log_function
     def send_pdu(self, pdu, destinations):
         """Informs the replication layer about a new PDU generated within the
@@ -376,89 +370,3 @@ class FederationClient(object):
         event.internal_metadata.outlier = outlier
 
         return event
-
-    @defer.inlineCallbacks
-    def _check_sigs_and_hash_and_fetch(self, origin, pdus, outlier=False):
-        """Takes a list of PDUs and checks the signatures and hashs of each
-        one. If a PDU fails its signature check then we check if we have it in
-        the database and if not then request if from the originating server of
-        that PDU.
-
-        If a PDU fails its content hash check then it is redacted.
-
-        The given list of PDUs are not modified, instead the function returns
-        a new list.
-
-        Args:
-            pdu (list)
-            outlier (bool)
-
-        Returns:
-            Deferred : A list of PDUs that have valid signatures and hashes.
-        """
-        signed_pdus = []
-        for pdu in pdus:
-            try:
-                new_pdu = yield self._check_sigs_and_hash(pdu)
-                signed_pdus.append(new_pdu)
-            except SynapseError:
-                # FIXME: We should handle signature failures more gracefully.
-
-                # Check local db.
-                new_pdu = yield self.store.get_event(
-                    pdu.event_id,
-                    allow_rejected=True
-                )
-                if new_pdu:
-                    signed_pdus.append(new_pdu)
-                    continue
-
-                # Check pdu.origin
-                if pdu.origin != origin:
-                    new_pdu = yield self.get_pdu(
-                        destinations=[pdu.origin],
-                        event_id=pdu.event_id,
-                        outlier=outlier,
-                    )
-
-                    if new_pdu:
-                        signed_pdus.append(new_pdu)
-                        continue
-
-                logger.warn("Failed to find copy of %s with valid signature")
-
-        defer.returnValue(signed_pdus)
-
-    @defer.inlineCallbacks
-    def _check_sigs_and_hash(self, pdu):
-        """Throws a SynapseError if the PDU does not have the correct
-        signatures.
-
-        Returns:
-            FrozenEvent: Either the given event or it redacted if it failed the
-            content hash check.
-        """
-        # Check signatures are correct.
-        redacted_event = prune_event(pdu)
-        redacted_pdu_json = redacted_event.get_pdu_json()
-
-        try:
-            yield self.keyring.verify_json_for_server(
-                pdu.origin, redacted_pdu_json
-            )
-        except SynapseError:
-            logger.warn(
-                "Signature check failed for %s redacted to %s",
-                encode_canonical_json(pdu.get_pdu_json()),
-                encode_canonical_json(redacted_pdu_json),
-            )
-            raise
-
-        if not check_event_content_hash(pdu):
-            logger.warn(
-                "Event content has been tampered, redacting %s, %s",
-                pdu.event_id, encode_canonical_json(pdu.get_dict())
-            )
-            defer.returnValue(redacted_event)
-
-        defer.returnValue(pdu)

synapse/federation/federation_server.py

@@ -16,6 +16,7 @@
 
 from twisted.internet import defer
 
+from .federation_base import FederationBase
 from .units import Transaction, Edu
 
 from synapse.util.logutils import log_function
@@ -35,7 +36,7 @@ import logging
 logger = logging.getLogger(__name__)
 
 
-class FederationServer(object):
+class FederationServer(FederationBase):
     def set_handler(self, handler):
         """Sets the handler that the replication layer will use to communicate
         receipt of new PDUs from other home servers. The required methods are
@@ -251,17 +252,20 @@ class FederationServer(object):
             Deferred: Results in `dict` with the same format as `content`
         """
         auth_chain = [
-            (yield self._check_sigs_and_hash(self.event_from_pdu_json(e)))
+            self.event_from_pdu_json(e)
             for e in content["auth_chain"]
         ]
 
-        missing = [
+        signed_auth = yield self._check_sigs_and_hash_and_fetch(
-            (yield self._check_sigs_and_hash(self.event_from_pdu_json(e)))
+            origin, auth_chain, outlier=True
-            for e in content.get("missing", [])
+        )
-        ]
 
         ret = yield self.handler.on_query_auth(
-            origin, event_id, auth_chain, content.get("rejects", []), missing
+            origin,
+            event_id,
+            signed_auth,
+            content.get("rejects", []),
+            content.get("missing", []),
         )
 
         time_now = self._clock.time_msec()
@@ -426,37 +430,3 @@ class FederationServer(object):
         event.internal_metadata.outlier = outlier
 
         return event
-
-    @defer.inlineCallbacks
-    def _check_sigs_and_hash(self, pdu):
-        """Throws a SynapseError if the PDU does not have the correct
-        signatures.
-
-        Returns:
-            FrozenEvent: Either the given event or it redacted if it failed the
-            content hash check.
-        """
-        # Check signatures are correct.
-        redacted_event = prune_event(pdu)
-        redacted_pdu_json = redacted_event.get_pdu_json()
-
-        try:
-            yield self.keyring.verify_json_for_server(
-                pdu.origin, redacted_pdu_json
-            )
-        except SynapseError:
-            logger.warn(
-                "Signature check failed for %s redacted to %s",
-                encode_canonical_json(pdu.get_pdu_json()),
-                encode_canonical_json(redacted_pdu_json),
-            )
-            raise
-
-        if not check_event_content_hash(pdu):
-            logger.warn(
-                "Event content has been tampered, redacting %s, %s",
-                pdu.event_id, encode_canonical_json(pdu.get_dict())
-            )
-            defer.returnValue(redacted_event)
-
-        defer.returnValue(pdu)