Support room version 11 (#15912)

And fix a bug in the implementation of the updated redaction
format (MSC2174) where the top-level redacts field was not
properly added for backwards-compatibility.

19 files changed, 190 insertions, 290 deletions

diff --git a/changelog.d/15912.feature b/changelog.d/15912.feature
new file mode 100644
index 0000000000..0faed11eda
--- /dev/null
+++ b/changelog.d/15912.feature
@@ -0,0 +1 @@
+Support room version 11 from [MSC3820](https://github.com/matrix-org/matrix-spec-proposals/pull/3820).
diff --git a/scripts-dev/complement.sh b/scripts-dev/complement.sh
index fea76cb5af..8416b55674 100755
--- a/scripts-dev/complement.sh
+++ b/scripts-dev/complement.sh
@@ -214,7 +214,7 @@ fi
 
 extra_test_args=()
 
-test_tags="synapse_blacklist,msc3787,msc3874,msc3890,msc3391,msc3930,faster_joins"
+test_tags="synapse_blacklist,msc3874,msc3890,msc3391,msc3930,faster_joins"
 
 # All environment variables starting with PASS_ will be shared.
 # (The prefix is stripped off before reaching the container.)
diff --git a/synapse/api/room_versions.py b/synapse/api/room_versions.py
index 25c105a4c8..e7662d5b99 100644
--- a/synapse/api/room_versions.py
+++ b/synapse/api/room_versions.py
@@ -78,36 +78,29 @@ class RoomVersion:
     # MSC2209: Check 'notifications' key while verifying
     # m.room.power_levels auth rules.
     limit_notifications_power_levels: bool
-    # MSC2175: No longer include the creator in m.room.create events.
-    msc2175_implicit_room_creator: bool
-    # MSC2174/MSC2176: Apply updated redaction rules algorithm, move redacts to
-    # content property.
-    msc2176_redaction_rules: bool
-    # MSC3083: Support the 'restricted' join_rule.
-    msc3083_join_rules: bool
-    # MSC3375: Support for the proper redaction rules for MSC3083. This mustn't
-    #          be enabled if MSC3083 is not.
-    msc3375_redaction_rules: bool
-    # MSC2403: Allows join_rules to be set to 'knock', changes auth rules to allow sending
-    # m.room.membership event with membership 'knock'.
-    msc2403_knocking: bool
+    # No longer include the creator in m.room.create events.
+    implicit_room_creator: bool
+    # Apply updated redaction rules algorithm from room version 11.
+    updated_redaction_rules: bool
+    # Support the 'restricted' join rule.
+    restricted_join_rule: bool
+    # Support for the proper redaction rules for the restricted join rule. This requires
+    # restricted_join_rule to be enabled.
+    restricted_join_rule_fix: bool
+    # Support the 'knock' join rule.
+    knock_join_rule: bool
     # MSC3389: Protect relation information from redaction.
     msc3389_relation_redactions: bool
-    # MSC3787: Adds support for a `knock_restricted` join rule, mixing concepts of
-    # knocks and restricted join rules into the same join condition.
-    msc3787_knock_restricted_join_rule: bool
-    # MSC3667: Enforce integer power levels
-    msc3667_int_only_power_levels: bool
-    # MSC3821: Do not redact the third_party_invite content field for membership events.
-    msc3821_redaction_rules: bool
+    # Support the 'knock_restricted' join rule.
+    knock_restricted_join_rule: bool
+    # Enforce integer power levels
+    enforce_int_power_levels: bool
     # MSC3931: Adds a push rule condition for "room version feature flags", making
     # some push rules room version dependent. Note that adding a flag to this list
     # is not enough to mark it "supported": the push rule evaluator also needs to
     # support the flag. Unknown flags are ignored by the evaluator, making conditions
     # fail if used.
     msc3931_push_features: Tuple[str, ...]  # values from PushRuleRoomFlag
-    # MSC3989: Redact the origin field.
-    msc3989_redaction_rules: bool
 
 
 class RoomVersions:
@@ -120,17 +113,15 @@ class RoomVersions:
         special_case_aliases_auth=True,
         strict_canonicaljson=False,
         limit_notifications_power_levels=False,
-        msc2175_implicit_room_creator=False,
-        msc2176_redaction_rules=False,
-        msc3083_join_rules=False,
-        msc3375_redaction_rules=False,
-        msc2403_knocking=False,
+        implicit_room_creator=False,
+        updated_redaction_rules=False,
+        restricted_join_rule=False,
+        restricted_join_rule_fix=False,
+        knock_join_rule=False,
         msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=False,
-        msc3667_int_only_power_levels=False,
-        msc3821_redaction_rules=False,
+        knock_restricted_join_rule=False,
+        enforce_int_power_levels=False,
         msc3931_push_features=(),
-        msc3989_redaction_rules=False,
     )
     V2 = RoomVersion(
         "2",
@@ -141,17 +132,15 @@ class RoomVersions:
         special_case_aliases_auth=True,
         strict_canonicaljson=False,
         limit_notifications_power_levels=False,
-        msc2175_implicit_room_creator=False,
-        msc2176_redaction_rules=False,
-        msc3083_join_rules=False,
-        msc3375_redaction_rules=False,
-        msc2403_knocking=False,
+        implicit_room_creator=False,
+        updated_redaction_rules=False,
+        restricted_join_rule=False,
+        restricted_join_rule_fix=False,
+        knock_join_rule=False,
         msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=False,
-        msc3667_int_only_power_levels=False,
-        msc3821_redaction_rules=False,
+        knock_restricted_join_rule=False,
+        enforce_int_power_levels=False,
         msc3931_push_features=(),
-        msc3989_redaction_rules=False,
     )
     V3 = RoomVersion(
         "3",
@@ -162,17 +151,15 @@ class RoomVersions:
         special_case_aliases_auth=True,
         strict_canonicaljson=False,
         limit_notifications_power_levels=False,
-        msc2175_implicit_room_creator=False,
-        msc2176_redaction_rules=False,
-        msc3083_join_rules=False,
-        msc3375_redaction_rules=False,
-        msc2403_knocking=False,
+        implicit_room_creator=False,
+        updated_redaction_rules=False,
+        restricted_join_rule=False,
+        restricted_join_rule_fix=False,
+        knock_join_rule=False,
         msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=False,
-        msc3667_int_only_power_levels=False,
-        msc3821_redaction_rules=False,
+        knock_restricted_join_rule=False,
+        enforce_int_power_levels=False,
         msc3931_push_features=(),
-        msc3989_redaction_rules=False,
     )
     V4 = RoomVersion(
         "4",
@@ -183,17 +170,15 @@ class RoomVersions:
         special_case_aliases_auth=True,
         strict_canonicaljson=False,
         limit_notifications_power_levels=False,
-        msc2175_implicit_room_creator=False,
-        msc2176_redaction_rules=False,
-        msc3083_join_rules=False,
-        msc3375_redaction_rules=False,
-        msc2403_knocking=False,
+        implicit_room_creator=False,
+        updated_redaction_rules=False,
+        restricted_join_rule=False,
+        restricted_join_rule_fix=False,
+        knock_join_rule=False,
         msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=False,
-        msc3667_int_only_power_levels=False,
-        msc3821_redaction_rules=False,
+        knock_restricted_join_rule=False,
+        enforce_int_power_levels=False,
         msc3931_push_features=(),
-        msc3989_redaction_rules=False,
     )
     V5 = RoomVersion(
         "5",
@@ -204,17 +189,15 @@ class RoomVersions:
         special_case_aliases_auth=True,
         strict_canonicaljson=False,
         limit_notifications_power_levels=False,
-        msc2175_implicit_room_creator=False,
-        msc2176_redaction_rules=False,
-        msc3083_join_rules=False,
-        msc3375_redaction_rules=False,
-        msc2403_knocking=False,
+        implicit_room_creator=False,
+        updated_redaction_rules=False,
+        restricted_join_rule=False,
+        restricted_join_rule_fix=False,
+        knock_join_rule=False,
         msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=False,
-        msc3667_int_only_power_levels=False,
-        msc3821_redaction_rules=False,
+        knock_restricted_join_rule=False,
+        enforce_int_power_levels=False,
         msc3931_push_features=(),
-        msc3989_redaction_rules=False,
     )
     V6 = RoomVersion(
         "6",
@@ -225,38 +208,15 @@ class RoomVersions:
         special_case_aliases_auth=False,
         strict_canonicaljson=True,
         limit_notifications_power_levels=True,
-        msc2175_implicit_room_creator=False,
-        msc2176_redaction_rules=False,
-        msc3083_join_rules=False,
-        msc3375_redaction_rules=False,
-        msc2403_knocking=False,
+        implicit_room_creator=False,
+        updated_redaction_rules=False,
+        restricted_join_rule=False,
+        restricted_join_rule_fix=False,
+        knock_join_rule=False,
         msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=False,
-        msc3667_int_only_power_levels=False,
-        msc3821_redaction_rules=False,
+        knock_restricted_join_rule=False,
+        enforce_int_power_levels=False,
         msc3931_push_features=(),
-        msc3989_redaction_rules=False,
-    )
-    MSC2176 = RoomVersion(
-        "org.matrix.msc2176",
-        RoomDisposition.UNSTABLE,
-        EventFormatVersions.ROOM_V4_PLUS,
-        StateResolutionVersions.V2,
-        enforce_key_validity=True,
-        special_case_aliases_auth=False,
-        strict_canonicaljson=True,
-        limit_notifications_power_levels=True,
-        msc2175_implicit_room_creator=False,
-        msc2176_redaction_rules=True,
-        msc3083_join_rules=False,
-        msc3375_redaction_rules=False,
-        msc2403_knocking=False,
-        msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=False,
-        msc3667_int_only_power_levels=False,
-        msc3821_redaction_rules=False,
-        msc3931_push_features=(),
-        msc3989_redaction_rules=False,
     )
     V7 = RoomVersion(
         "7",
@@ -267,17 +227,15 @@ class RoomVersions:
         special_case_aliases_auth=False,
         strict_canonicaljson=True,
         limit_notifications_power_levels=True,
-        msc2175_implicit_room_creator=False,
-        msc2176_redaction_rules=False,
-        msc3083_join_rules=False,
-        msc3375_redaction_rules=False,
-        msc2403_knocking=True,
+        implicit_room_creator=False,
+        updated_redaction_rules=False,
+        restricted_join_rule=False,
+        restricted_join_rule_fix=False,
+        knock_join_rule=True,
         msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=False,
-        msc3667_int_only_power_levels=False,
-        msc3821_redaction_rules=False,
+        knock_restricted_join_rule=False,
+        enforce_int_power_levels=False,
         msc3931_push_features=(),
-        msc3989_redaction_rules=False,
     )
     V8 = RoomVersion(
         "8",
@@ -288,17 +246,15 @@ class RoomVersions:
         special_case_aliases_auth=False,
         strict_canonicaljson=True,
         limit_notifications_power_levels=True,
-        msc2175_implicit_room_creator=False,
-        msc2176_redaction_rules=False,
-        msc3083_join_rules=True,
-        msc3375_redaction_rules=False,
-        msc2403_knocking=True,
+        implicit_room_creator=False,
+        updated_redaction_rules=False,
+        restricted_join_rule=True,
+        restricted_join_rule_fix=False,
+        knock_join_rule=True,
         msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=False,
-        msc3667_int_only_power_levels=False,
-        msc3821_redaction_rules=False,
+        knock_restricted_join_rule=False,
+        enforce_int_power_levels=False,
         msc3931_push_features=(),
-        msc3989_redaction_rules=False,
     )
     V9 = RoomVersion(
         "9",
@@ -309,59 +265,15 @@ class RoomVersions:
         special_case_aliases_auth=False,
         strict_canonicaljson=True,
         limit_notifications_power_levels=True,
-        msc2175_implicit_room_creator=False,
-        msc2176_redaction_rules=False,
-        msc3083_join_rules=True,
-        msc3375_redaction_rules=True,
-        msc2403_knocking=True,
-        msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=False,
-        msc3667_int_only_power_levels=False,
-        msc3821_redaction_rules=False,
-        msc3931_push_features=(),
-        msc3989_redaction_rules=False,
-    )
-    MSC3787 = RoomVersion(
-        "org.matrix.msc3787",
-        RoomDisposition.UNSTABLE,
-        EventFormatVersions.ROOM_V4_PLUS,
-        StateResolutionVersions.V2,
-        enforce_key_validity=True,
-        special_case_aliases_auth=False,
-        strict_canonicaljson=True,
-        limit_notifications_power_levels=True,
-        msc2175_implicit_room_creator=False,
-        msc2176_redaction_rules=False,
-        msc3083_join_rules=True,
-        msc3375_redaction_rules=True,
-        msc2403_knocking=True,
-        msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=True,
-        msc3667_int_only_power_levels=False,
-        msc3821_redaction_rules=False,
-        msc3931_push_features=(),
-        msc3989_redaction_rules=False,
-    )
-    MSC3821 = RoomVersion(
-        "org.matrix.msc3821.opt1",
-        RoomDisposition.UNSTABLE,
-        EventFormatVersions.ROOM_V4_PLUS,
-        StateResolutionVersions.V2,
-        enforce_key_validity=True,
-        special_case_aliases_auth=False,
-        strict_canonicaljson=True,
-        limit_notifications_power_levels=True,
-        msc2175_implicit_room_creator=False,
-        msc2176_redaction_rules=False,
-        msc3083_join_rules=True,
-        msc3375_redaction_rules=True,
-        msc2403_knocking=True,
+        implicit_room_creator=False,
+        updated_redaction_rules=False,
+        restricted_join_rule=True,
+        restricted_join_rule_fix=True,
+        knock_join_rule=True,
         msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=False,
-        msc3667_int_only_power_levels=False,
-        msc3821_redaction_rules=True,
+        knock_restricted_join_rule=False,
+        enforce_int_power_levels=False,
         msc3931_push_features=(),
-        msc3989_redaction_rules=False,
     )
     V10 = RoomVersion(
         "10",
@@ -372,17 +284,15 @@ class RoomVersions:
         special_case_aliases_auth=False,
         strict_canonicaljson=True,
         limit_notifications_power_levels=True,
-        msc2175_implicit_room_creator=False,
-        msc2176_redaction_rules=False,
-        msc3083_join_rules=True,
-        msc3375_redaction_rules=True,
-        msc2403_knocking=True,
+        implicit_room_creator=False,
+        updated_redaction_rules=False,
+        restricted_join_rule=True,
+        restricted_join_rule_fix=True,
+        knock_join_rule=True,
         msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=True,
-        msc3667_int_only_power_levels=True,
-        msc3821_redaction_rules=False,
+        knock_restricted_join_rule=True,
+        enforce_int_power_levels=True,
         msc3931_push_features=(),
-        msc3989_redaction_rules=False,
     )
     MSC1767v10 = RoomVersion(
         # MSC1767 (Extensible Events) based on room version "10"
@@ -394,60 +304,34 @@ class RoomVersions:
         special_case_aliases_auth=False,
         strict_canonicaljson=True,
         limit_notifications_power_levels=True,
-        msc2175_implicit_room_creator=False,
-        msc2176_redaction_rules=False,
-        msc3083_join_rules=True,
-        msc3375_redaction_rules=True,
-        msc2403_knocking=True,
+        implicit_room_creator=False,
+        updated_redaction_rules=False,
+        restricted_join_rule=True,
+        restricted_join_rule_fix=True,
+        knock_join_rule=True,
         msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=True,
-        msc3667_int_only_power_levels=True,
-        msc3821_redaction_rules=False,
+        knock_restricted_join_rule=True,
+        enforce_int_power_levels=True,
         msc3931_push_features=(PushRuleRoomFlag.EXTENSIBLE_EVENTS,),
-        msc3989_redaction_rules=False,
     )
-    MSC3989 = RoomVersion(
-        "org.matrix.msc3989",
-        RoomDisposition.UNSTABLE,
-        EventFormatVersions.ROOM_V4_PLUS,
-        StateResolutionVersions.V2,
-        enforce_key_validity=True,
-        special_case_aliases_auth=False,
-        strict_canonicaljson=True,
-        limit_notifications_power_levels=True,
-        msc2175_implicit_room_creator=False,
-        msc2176_redaction_rules=False,
-        msc3083_join_rules=True,
-        msc3375_redaction_rules=True,
-        msc2403_knocking=True,
-        msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=True,
-        msc3667_int_only_power_levels=True,
-        msc3821_redaction_rules=False,
-        msc3931_push_features=(),
-        msc3989_redaction_rules=True,
-    )
-    MSC3820opt2 = RoomVersion(
-        # Based upon v10
-        "org.matrix.msc3820.opt2",
-        RoomDisposition.UNSTABLE,
+    V11 = RoomVersion(
+        "11",
+        RoomDisposition.STABLE,
         EventFormatVersions.ROOM_V4_PLUS,
         StateResolutionVersions.V2,
         enforce_key_validity=True,
         special_case_aliases_auth=False,
         strict_canonicaljson=True,
         limit_notifications_power_levels=True,
-        msc2175_implicit_room_creator=True,  # Used by MSC3820
-        msc2176_redaction_rules=True,  # Used by MSC3820
-        msc3083_join_rules=True,
-        msc3375_redaction_rules=True,
-        msc2403_knocking=True,
+        implicit_room_creator=True,  # Used by MSC3820
+        updated_redaction_rules=True,  # Used by MSC3820
+        restricted_join_rule=True,
+        restricted_join_rule_fix=True,
+        knock_join_rule=True,
         msc3389_relation_redactions=False,
-        msc3787_knock_restricted_join_rule=True,
-        msc3667_int_only_power_levels=True,
-        msc3821_redaction_rules=True,  # Used by MSC3820
+        knock_restricted_join_rule=True,
+        enforce_int_power_levels=True,
         msc3931_push_features=(),
-        msc3989_redaction_rules=True,  # Used by MSC3820
     )
 
 
@@ -460,14 +344,11 @@ KNOWN_ROOM_VERSIONS: Dict[str, RoomVersion] = {
         RoomVersions.V4,
         RoomVersions.V5,
         RoomVersions.V6,
-        RoomVersions.MSC2176,
         RoomVersions.V7,
         RoomVersions.V8,
         RoomVersions.V9,
-        RoomVersions.MSC3787,
         RoomVersions.V10,
-        RoomVersions.MSC3989,
-        RoomVersions.MSC3820opt2,
+        RoomVersions.V11,
     )
 }
 
@@ -496,12 +377,12 @@ MSC3244_CAPABILITIES = {
         RoomVersionCapability(
             "knock",
             RoomVersions.V7,
-            lambda room_version: room_version.msc2403_knocking,
+            lambda room_version: room_version.knock_join_rule,
         ),
         RoomVersionCapability(
             "restricted",
             RoomVersions.V9,
-            lambda room_version: room_version.msc3083_join_rules,
+            lambda room_version: room_version.restricted_join_rule,
         ),
     )
 }
diff --git a/synapse/event_auth.py b/synapse/event_auth.py
index 3aaf53dfbd..3a260a492b 100644
--- a/synapse/event_auth.py
+++ b/synapse/event_auth.py
@@ -126,7 +126,7 @@ def validate_event_for_room_version(event: "EventBase") -> None:
             raise AuthError(403, "Event not signed by sending server")
 
     is_invite_via_allow_rule = (
-        event.room_version.msc3083_join_rules
+        event.room_version.restricted_join_rule
         and event.type == EventTypes.Member
         and event.membership == Membership.JOIN
         and EventContentFields.AUTHORISING_USER in event.content
@@ -352,11 +352,9 @@ LENIENT_EVENT_BYTE_LIMITS_ROOM_VERSIONS = {
     RoomVersions.V4,
     RoomVersions.V5,
     RoomVersions.V6,
-    RoomVersions.MSC2176,
     RoomVersions.V7,
     RoomVersions.V8,
     RoomVersions.V9,
-    RoomVersions.MSC3787,
     RoomVersions.V10,
     RoomVersions.MSC1767v10,
 }
@@ -449,7 +447,7 @@ def _check_create(event: "EventBase") -> None:
 
     # 1.4 If content has no creator field, reject if the room version requires it.
     if (
-        not event.room_version.msc2175_implicit_room_creator
+        not event.room_version.implicit_room_creator
         and EventContentFields.ROOM_CREATOR not in event.content
     ):
         raise AuthError(403, "Create event lacks a 'creator' property")
@@ -486,7 +484,7 @@ def _is_membership_change_allowed(
         key = (EventTypes.Create, "")
         create = auth_events.get(key)
         if create and event.prev_event_ids()[0] == create.event_id:
-            if room_version.msc2175_implicit_room_creator:
+            if room_version.implicit_room_creator:
                 creator = create.sender
             else:
                 creator = create.content[EventContentFields.ROOM_CREATOR]
@@ -509,7 +507,7 @@ def _is_membership_change_allowed(
     caller_invited = caller and caller.membership == Membership.INVITE
     caller_knocked = (
         caller
-        and room_version.msc2403_knocking
+        and room_version.knock_join_rule
         and caller.membership == Membership.KNOCK
     )
 
@@ -609,9 +607,9 @@ def _is_membership_change_allowed(
         elif join_rule == JoinRules.PUBLIC:
             pass
         elif (
-            room_version.msc3083_join_rules and join_rule == JoinRules.RESTRICTED
+            room_version.restricted_join_rule and join_rule == JoinRules.RESTRICTED
         ) or (
-            room_version.msc3787_knock_restricted_join_rule
+            room_version.knock_restricted_join_rule
             and join_rule == JoinRules.KNOCK_RESTRICTED
         ):
             # This is the same as public, but the event must contain a reference
@@ -641,9 +639,9 @@ def _is_membership_change_allowed(
 
         elif (
             join_rule == JoinRules.INVITE
-            or (room_version.msc2403_knocking and join_rule == JoinRules.KNOCK)
+            or (room_version.knock_join_rule and join_rule == JoinRules.KNOCK)
             or (
-                room_version.msc3787_knock_restricted_join_rule
+                room_version.knock_restricted_join_rule
                 and join_rule == JoinRules.KNOCK_RESTRICTED
             )
         ):
@@ -677,9 +675,9 @@ def _is_membership_change_allowed(
                 "You don't have permission to ban",
                 errcode=Codes.INSUFFICIENT_POWER,
             )
-    elif room_version.msc2403_knocking and Membership.KNOCK == membership:
+    elif room_version.knock_join_rule and Membership.KNOCK == membership:
         if join_rule != JoinRules.KNOCK and (
-            not room_version.msc3787_knock_restricted_join_rule
+            not room_version.knock_restricted_join_rule
             or join_rule != JoinRules.KNOCK_RESTRICTED
         ):
             raise AuthError(403, "You don't have permission to knock")
@@ -836,7 +834,7 @@ def _check_power_levels(
     # Reject events with stringy power levels if required by room version
     if (
         event.type == EventTypes.PowerLevels
-        and room_version_obj.msc3667_int_only_power_levels
+        and room_version_obj.enforce_int_power_levels
     ):
         for k, v in event.content.items():
             if k in {
@@ -972,7 +970,7 @@ def get_user_power_level(user_id: str, auth_events: StateMap["EventBase"]) -> in
         key = (EventTypes.Create, "")
         create_event = auth_events.get(key)
         if create_event is not None:
-            if create_event.room_version.msc2175_implicit_room_creator:
+            if create_event.room_version.implicit_room_creator:
                 creator = create_event.sender
             else:
                 creator = create_event.content[EventContentFields.ROOM_CREATOR]
@@ -1110,7 +1108,7 @@ def auth_types_for_event(
                 )
                 auth_types.add(key)
 
-        if room_version.msc3083_join_rules and membership == Membership.JOIN:
+        if room_version.restricted_join_rule and membership == Membership.JOIN:
             if EventContentFields.AUTHORISING_USER in event.content:
                 key = (
                     EventTypes.Member,
diff --git a/synapse/events/__init__.py b/synapse/events/__init__.py
index 75b62adb33..35257a3b1b 100644
--- a/synapse/events/__init__.py
+++ b/synapse/events/__init__.py
@@ -346,7 +346,7 @@ class EventBase(metaclass=abc.ABCMeta):
     @property
     def redacts(self) -> Optional[str]:
         """MSC2176 moved the redacts field into the content."""
-        if self.room_version.msc2176_redaction_rules:
+        if self.room_version.updated_redaction_rules:
             return self.content.get("redacts")
         return self.get("redacts")
 
diff --git a/synapse/events/builder.py b/synapse/events/builder.py
index a254548c6c..14ea0e6640 100644
--- a/synapse/events/builder.py
+++ b/synapse/events/builder.py
@@ -175,7 +175,7 @@ class EventBuilder:
 
         # MSC2174 moves the redacts property to the content, it is invalid to
         # provide it as a top-level property.
-        if self._redacts is not None and not self.room_version.msc2176_redaction_rules:
+        if self._redacts is not None and not self.room_version.updated_redaction_rules:
             event_dict["redacts"] = self._redacts
 
         if self._origin_server_ts is not None:
diff --git a/synapse/events/utils.py b/synapse/events/utils.py
index a55efcca56..ecfc5c0568 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -108,13 +108,9 @@ def prune_event_dict(room_version: RoomVersion, event_dict: JsonDict) -> JsonDic
         "origin_server_ts",
     ]
 
-    # Room versions from before MSC2176 had additional allowed keys.
-    if not room_version.msc2176_redaction_rules:
-        allowed_keys.extend(["prev_state", "membership"])
-
-    # Room versions before MSC3989 kept the origin field.
-    if not room_version.msc3989_redaction_rules:
-        allowed_keys.append("origin")
+    # Earlier room versions from had additional allowed keys.
+    if not room_version.updated_redaction_rules:
+        allowed_keys.extend(["prev_state", "membership", "origin"])
 
     event_type = event_dict["type"]
 
@@ -127,9 +123,9 @@ def prune_event_dict(room_version: RoomVersion, event_dict: JsonDict) -> JsonDic
 
     if event_type == EventTypes.Member:
         add_fields("membership")
-        if room_version.msc3375_redaction_rules:
+        if room_version.restricted_join_rule_fix:
             add_fields(EventContentFields.AUTHORISING_USER)
-        if room_version.msc3821_redaction_rules:
+        if room_version.updated_redaction_rules:
             # Preserve the signed field under third_party_invite.
             third_party_invite = event_dict["content"].get("third_party_invite")
             if isinstance(third_party_invite, collections.abc.Mapping):
@@ -141,13 +137,13 @@ def prune_event_dict(room_version: RoomVersion, event_dict: JsonDict) -> JsonDic
 
     elif event_type == EventTypes.Create:
         # MSC2176 rules state that create events cannot be redacted.
-        if room_version.msc2176_redaction_rules:
+        if room_version.updated_redaction_rules:
             return event_dict
 
         add_fields("creator")
     elif event_type == EventTypes.JoinRules:
         add_fields("join_rule")
-        if room_version.msc3083_join_rules:
+        if room_version.restricted_join_rule:
             add_fields("allow")
     elif event_type == EventTypes.PowerLevels:
         add_fields(
@@ -161,14 +157,14 @@ def prune_event_dict(room_version: RoomVersion, event_dict: JsonDict) -> JsonDic
             "redact",
         )
 
-        if room_version.msc2176_redaction_rules:
+        if room_version.updated_redaction_rules:
             add_fields("invite")
 
     elif event_type == EventTypes.Aliases and room_version.special_case_aliases_auth:
         add_fields("aliases")
     elif event_type == EventTypes.RoomHistoryVisibility:
         add_fields("history_visibility")
-    elif event_type == EventTypes.Redaction and room_version.msc2176_redaction_rules:
+    elif event_type == EventTypes.Redaction and room_version.updated_redaction_rules:
         add_fields("redacts")
 
     # Protect the rel_type and event_id fields under the m.relates_to field.
@@ -477,6 +473,15 @@ def serialize_event(
     if config.as_client_event:
         d = config.event_format(d)
 
+    # If the event is a redaction, copy the redacts field from the content to
+    # top-level for backwards compatibility.
+    if (
+        e.type == EventTypes.Redaction
+        and e.room_version.updated_redaction_rules
+        and e.redacts is not None
+    ):
+        d["redacts"] = e.redacts
+
     only_event_fields = config.only_event_fields
     if only_event_fields:
         if not isinstance(only_event_fields, list) or not all(
diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py
index b77022b406..31e0260b83 100644
--- a/synapse/federation/federation_base.py
+++ b/synapse/federation/federation_base.py
@@ -231,7 +231,7 @@ async def _check_sigs_on_pdu(
     # If this is a join event for a restricted room it may have been authorised
     # via a different server from the sending server. Check those signatures.
     if (
-        room_version.msc3083_join_rules
+        room_version.restricted_join_rule
         and pdu.type == EventTypes.Member
         and pdu.membership == Membership.JOIN
         and EventContentFields.AUTHORISING_USER in pdu.content
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index e5359ca558..89bd597409 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -983,7 +983,7 @@ class FederationClient(FederationBase):
             if not room_version:
                 raise UnsupportedRoomVersionError()
 
-            if not room_version.msc2403_knocking and membership == Membership.KNOCK:
+            if not room_version.knock_join_rule and membership == Membership.KNOCK:
                 raise SynapseError(
                     400,
                     "This room version does not support knocking",
@@ -1069,7 +1069,7 @@ class FederationClient(FederationBase):
             # * Ensure the signatures are good.
             #
             # Otherwise, fallback to the provided event.
-            if room_version.msc3083_join_rules and response.event:
+            if room_version.restricted_join_rule and response.event:
                 event = response.event
 
                 valid_pdu = await self._check_sigs_and_hash_and_fetch_one(
@@ -1195,7 +1195,7 @@ class FederationClient(FederationBase):
 
         # MSC3083 defines additional error codes for room joins.
         failover_errcodes = None
-        if room_version.msc3083_join_rules:
+        if room_version.restricted_join_rule:
             failover_errcodes = (
                 Codes.UNABLE_AUTHORISE_JOIN,
                 Codes.UNABLE_TO_GRANT_JOIN,
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 61fa3b30af..fa61dd8c10 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -806,7 +806,7 @@ class FederationServer(FederationBase):
             raise IncompatibleRoomVersionError(room_version=room_version.identifier)
 
         # Check that this room supports knocking as defined by its room version
-        if not room_version.msc2403_knocking:
+        if not room_version.knock_join_rule:
             raise SynapseError(
                 403,
                 "This room version does not support knocking",
@@ -909,7 +909,7 @@ class FederationServer(FederationBase):
                 errcode=Codes.NOT_FOUND,
             )
 
-        if membership_type == Membership.KNOCK and not room_version.msc2403_knocking:
+        if membership_type == Membership.KNOCK and not room_version.knock_join_rule:
             raise SynapseError(
                 403,
                 "This room version does not support knocking",
@@ -933,7 +933,7 @@ class FederationServer(FederationBase):
         # the event is valid to be sent into the room. Currently this is only done
         # if the user is being joined via restricted join rules.
         if (
-            room_version.msc3083_join_rules
+            room_version.restricted_join_rule
             and event.membership == Membership.JOIN
             and EventContentFields.AUTHORISING_USER in event.content
         ):
diff --git a/synapse/handlers/event_auth.py b/synapse/handlers/event_auth.py
index 3e37c0cbe2..82a7617a08 100644
--- a/synapse/handlers/event_auth.py
+++ b/synapse/handlers/event_auth.py
@@ -277,7 +277,7 @@ class EventAuthHandler:
             True if the proper room version and join rules are set for restricted access.
         """
         # This only applies to room versions which support the new join rule.
-        if not room_version.msc3083_join_rules:
+        if not room_version.restricted_join_rule:
             return False
 
         # If there's no join rule, then it defaults to invite (so this doesn't apply).
@@ -292,7 +292,7 @@ class EventAuthHandler:
             return True
 
         # also check for MSC3787 behaviour
-        if room_version.msc3787_knock_restricted_join_rule:
+        if room_version.knock_restricted_join_rule:
             return content_join_rule == JoinRules.KNOCK_RESTRICTED
 
         return False
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index cc5ed97730..15b9fbe44a 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -957,7 +957,7 @@ class FederationHandler:
         # Note that this requires the /send_join request to come back to the
         # same server.
         prev_event_ids = None
-        if room_version.msc3083_join_rules:
+        if room_version.restricted_join_rule:
             # Note that the room's state can change out from under us and render our
             # nice join rules-conformant event non-conformant by the time we build the
             # event. When this happens, our validation at the end fails and we respond
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index bf907b7881..0513e28aab 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -1116,7 +1116,7 @@ class RoomCreationHandler:
         preset_config, config = self._room_preset_config(room_config)
 
         # MSC2175 removes the creator field from the create event.
-        if not room_version.msc2175_implicit_room_creator:
+        if not room_version.implicit_room_creator:
             creation_content["creator"] = creator_id
         creation_event, unpersisted_creation_context = await create_event(
             EventTypes.Create, creation_content, False
diff --git a/synapse/handlers/room_summary.py b/synapse/handlers/room_summary.py
index 807245160d..dad3e23470 100644
--- a/synapse/handlers/room_summary.py
+++ b/synapse/handlers/room_summary.py
@@ -564,9 +564,9 @@ class RoomSummaryHandler:
             join_rule = join_rules_event.content.get("join_rule")
             if (
                 join_rule == JoinRules.PUBLIC
-                or (room_version.msc2403_knocking and join_rule == JoinRules.KNOCK)
+                or (room_version.knock_join_rule and join_rule == JoinRules.KNOCK)
                 or (
-                    room_version.msc3787_knock_restricted_join_rule
+                    room_version.knock_restricted_join_rule
                     and join_rule == JoinRules.KNOCK_RESTRICTED
                 )
             ):
diff --git a/synapse/push/bulk_push_rule_evaluator.py b/synapse/push/bulk_push_rule_evaluator.py
index 67377c647b..990c079c81 100644
--- a/synapse/push/bulk_push_rule_evaluator.py
+++ b/synapse/push/bulk_push_rule_evaluator.py
@@ -375,7 +375,7 @@ class BulkPushRuleEvaluator:
         # _get_power_levels_and_sender_level in its call to get_user_power_level
         # (even for room V10.)
         notification_levels = power_levels.get("notifications", {})
-        if not event.room_version.msc3667_int_only_power_levels:
+        if not event.room_version.enforce_int_power_levels:
             keys = list(notification_levels.keys())
             for key in keys:
                 level = notification_levels.get(key, SENTINEL)
diff --git a/synapse/rest/client/room.py b/synapse/rest/client/room.py
index 951bd033f5..dc498001e4 100644
--- a/synapse/rest/client/room.py
+++ b/synapse/rest/client/room.py
@@ -1117,7 +1117,7 @@ class RoomRedactEventRestServlet(TransactionRestServlet):
         # Ensure the redacts property in the content matches the one provided in
         # the URL.
         room_version = await self._store.get_room_version(room_id)
-        if room_version.msc2176_redaction_rules:
+        if room_version.updated_redaction_rules:
             if "redacts" in content and content["redacts"] != event_id:
                 raise SynapseError(
                     400,
@@ -1151,7 +1151,7 @@ class RoomRedactEventRestServlet(TransactionRestServlet):
                     "sender": requester.user.to_string(),
                 }
                 # Earlier room versions had a top-level redacts property.
-                if not room_version.msc2176_redaction_rules:
+                if not room_version.updated_redaction_rules:
                     event_dict["redacts"] = event_id
 
                 (
diff --git a/synapse/storage/databases/main/room.py b/synapse/storage/databases/main/room.py
index ca8be8c80d..830658f328 100644
--- a/synapse/storage/databases/main/room.py
+++ b/synapse/storage/databases/main/room.py
@@ -2136,7 +2136,7 @@ class RoomStore(RoomBackgroundUpdateStore, RoomWorkerStore):
             raise StoreError(400, "No create event in state")
 
         # Before MSC2175, the room creator was a separate field.
-        if not room_version.msc2175_implicit_room_creator:
+        if not room_version.implicit_room_creator:
             room_creator = create_event.content.get(EventContentFields.ROOM_CREATOR)
 
             if not isinstance(room_creator, str):
diff --git a/tests/events/test_utils.py b/tests/events/test_utils.py
index c9a610db9a..6a52af4d82 100644
--- a/tests/events/test_utils.py
+++ b/tests/events/test_utils.py
@@ -140,18 +140,16 @@ class PruneEventTestCase(stdlib_unittest.TestCase):
             },
         )
 
-        # As of MSC2176 we now redact the membership and prev_states keys.
+        # As of room versions we now redact the membership, prev_states, and origin keys.
         self.run_test(
-            {"type": "A", "prev_state": "prev_state", "membership": "join"},
-            {"type": "A", "content": {}, "signatures": {}, "unsigned": {}},
-            room_version=RoomVersions.MSC2176,
-        )
-
-        # As of MSC3989 we now redact the origin key.
-        self.run_test(
-            {"type": "A", "origin": "example.com"},
+            {
+                "type": "A",
+                "prev_state": "prev_state",
+                "membership": "join",
+                "origin": "example.com",
+            },
             {"type": "A", "content": {}, "signatures": {}, "unsigned": {}},
-            room_version=RoomVersions.MSC3989,
+            room_version=RoomVersions.V11,
         )
 
     def test_unsigned(self) -> None:
@@ -236,7 +234,7 @@ class PruneEventTestCase(stdlib_unittest.TestCase):
                 "signatures": {},
                 "unsigned": {},
             },
-            room_version=RoomVersions.MSC2176,
+            room_version=RoomVersions.V11,
         )
 
     def test_power_levels(self) -> None:
@@ -286,7 +284,7 @@ class PruneEventTestCase(stdlib_unittest.TestCase):
                 "signatures": {},
                 "unsigned": {},
             },
-            room_version=RoomVersions.MSC2176,
+            room_version=RoomVersions.V11,
         )
 
     def test_alias_event(self) -> None:
@@ -349,7 +347,7 @@ class PruneEventTestCase(stdlib_unittest.TestCase):
                 "signatures": {},
                 "unsigned": {},
             },
-            room_version=RoomVersions.MSC2176,
+            room_version=RoomVersions.V11,
         )
 
     def test_join_rules(self) -> None:
@@ -472,7 +470,7 @@ class PruneEventTestCase(stdlib_unittest.TestCase):
                 "signatures": {},
                 "unsigned": {},
             },
-            room_version=RoomVersions.MSC3821,
+            room_version=RoomVersions.V11,
         )
 
         # Ensure this doesn't break if an invalid field is sent.
@@ -491,7 +489,7 @@ class PruneEventTestCase(stdlib_unittest.TestCase):
                 "signatures": {},
                 "unsigned": {},
             },
-            room_version=RoomVersions.MSC3821,
+            room_version=RoomVersions.V11,
         )
 
         self.run_test(
@@ -509,7 +507,7 @@ class PruneEventTestCase(stdlib_unittest.TestCase):
                 "signatures": {},
                 "unsigned": {},
             },
-            room_version=RoomVersions.MSC3821,
+            room_version=RoomVersions.V11,
         )
 
     def test_relations(self) -> None:
diff --git a/tests/rest/client/test_redactions.py b/tests/rest/client/test_redactions.py
index b43e95292c..6028886bd6 100644
--- a/tests/rest/client/test_redactions.py
+++ b/tests/rest/client/test_redactions.py
@@ -20,6 +20,8 @@ from synapse.api.room_versions import RoomVersions
 from synapse.rest import admin
 from synapse.rest.client import login, room, sync
 from synapse.server import HomeServer
+from synapse.storage._base import db_to_json
+from synapse.storage.database import LoggingTransaction
 from synapse.types import JsonDict
 from synapse.util import Clock
 
@@ -573,7 +575,7 @@ class RedactionsTestCase(HomeserverTestCase):
         room_id = self.helper.create_room_as(
             self.mod_user_id,
             tok=self.mod_access_token,
-            room_version=RoomVersions.MSC2176.identifier,
+            room_version=RoomVersions.V11.identifier,
         )
 
         # Create an event.
@@ -597,5 +599,20 @@ class RedactionsTestCase(HomeserverTestCase):
         redact_event = timeline[-1]
         self.assertEqual(redact_event["type"], EventTypes.Redaction)
         # The redacts key should be in the content.
-        self.assertNotIn("redacts", redact_event)
         self.assertEquals(redact_event["content"]["redacts"], event_id)
+
+        # It should also be copied as the top-level redacts field for backwards
+        # compatibility.
+        self.assertEquals(redact_event["redacts"], event_id)
+
+        # But it isn't actually part of the event.
+        def get_event(txn: LoggingTransaction) -> JsonDict:
+            return db_to_json(
+                main_datastore._fetch_event_rows(txn, [event_id])[event_id].json
+            )
+
+        main_datastore = self.hs.get_datastores().main
+        event_json = self.get_success(
+            main_datastore.db_pool.runInteraction("get_event", get_event)
+        )
+        self.assertNotIn("redacts", event_json)