matrix-spec/content/rooms/v10.md

title	type	weight
Room Version 10	docs	100

This room version builds on version 9 to enforce that power level values be integers, and to introduce a new knock_restricted join rule, allowing prospective members to more easily join such a room.

Client considerations

This room version adds a new knock_restricted join rule to allow prospective members of a room join either through knocking (introduced in room version 7) or through "join restrictions" (introduced in room version 8 and refined in room version 9).

Clients should render the new join rule accordingly for such rooms. For example:

This room is:
[ ] Public
[x] Private

Join rules (disabled when Public):
[x] Allow members of `#space:example.org` to join
[x] Allow knocking

Clients which implement the redaction algorithm locally should refer to the redactions section below for a full overview.

Server implementation components

{{% boxes/warning %}} The information contained in this section is strictly for server implementors. Applications which use the Client-Server API are generally unaffected by the intricacies contained here. The section above regarding client considerations is the resource that Client-Server API use cases should reference. {{% /boxes/warning %}}

Room version 7 added "knocking" and room version 8 added "join restrictions" (refined by room version 9) — both allow prospective members an avenue to join, however it was not possible to use the two mechanisms together. This room version adds a new knock_restricted join rule as a mix of the two behaviours, allowing a user to join the room if they meet either the restricted join rule criteria or the knock join rule criteria.

This room version additionally requires that values in the power levels event be integers and not string representations, unlike other room versions.

Room version 10 is based upon room version 9 with the following considerations.

Event format

The event format is unchanged by this room version. See below for details on the current event format.

Deprecated event content schemas

While this room version does not change the event format specifically, some deprecated behaviours are strictly no longer supported.

Values in m.room.power_levels events must be integers

In other room versions, such as v9, power levels could be represented as strings for backwards compatibility.

This backwards compatibility is removed in this room version - power levels MUST NOT be represented as strings within this room version. Power levels which are not correctly structured are rejected under the authorization rules below.

Authorization rules

Events must be signed by the server denoted by the sender key.

m.room.redaction events are not explicitly part of the auth rules. They are still subject to the minimum power level rules, but should always fall into "10. Otherwise, allow". Instead of being authorized at the time of receipt, they are authorized at a later stage: see the Redactions section below for more information.

The types of state events that affect authorization are:

• m.room.create
• m.room.member
• m.room.join_rules
• m.room.power_levels
• m.room.third_party_invite

{{% boxes/note %}} Power levels are inferred from defaults when not explicitly supplied. For example, mentions of the sender's power level can also refer to the default power level for users in the room. {{% /boxes/note %}}

The rules are as follows:

1. If type is m.room.create:
   1. If it has any previous events, reject.
   2. If the domain of the room_id does not match the domain of the sender, reject.
   3. If content.room_version is present and is not a recognised version, reject.
   4. If content has no creator field, reject.
   5. Otherwise, allow.
2. Considering the event's auth_events:
   1. If there are duplicate entries for a given type and state_key pair, reject.
   2. If there are entries whose type and state_key don't match those specified by the auth events selection algorithm described in the server specification, reject.
   3. If there are entries which were themselves rejected under the checks performed on receipt of a PDU, reject.
   4. If there is no m.room.create event among the entries, reject.
3. If the content of the m.room.create event in the room state has the property m.federate set to false, and the sender domain of the event does not match the sender domain of the create event, reject.
4. If type is m.room.member:
   1. If no state_key key or membership key in content, reject.
   2. If content has a join_authorised_via_users_server key:
      1. If the event is not validly signed by the homeserver of the user ID denoted by the key, reject.
   3. If membership is join:
      1. If the only previous event is an m.room.create and the state_key is the creator, allow.
      2. If the sender does not match state_key, reject.
      3. If the sender is banned, reject.
      4. If the join_rule is invite or knock then allow if membership state is invite or join.
      5. {{< changed-in this="true" >}} If the join_rule is restricted or knock_restricted:
         1. If membership state is join or invite, allow.
         2. If the join_authorised_via_users_server key in content is not a user with sufficient permission to invite other users, reject.
         3. Otherwise, allow.
      6. If the join_rule is public, allow.
      7. Otherwise, reject.
   4. If membership is invite:
      1. If content has third_party_invite key:
         1. If target user is banned, reject.
         2. If content.third_party_invite does not have a signed key, reject.
         3. If signed does not have mxid and token keys, reject.
         4. If mxid does not match state_key, reject.
         5. If there is no m.room.third_party_invite event in the current room state with state_key matching token, reject.
         6. If sender does not match sender of the m.room.third_party_invite, reject.
         7. If any signature in signed matches any public key in the m.room.third_party_invite event, allow. The public keys are in content of m.room.third_party_invite as:
            1. A single public key in the public_key field.
            2. A list of public keys in the public_keys field.
         8. Otherwise, reject.
      2. If the sender's current membership state is not join, reject.
      3. If target user's current membership state is join or ban, reject.
      4. If the sender's power level is greater than or equal to the invite level, allow.
      5. Otherwise, reject.
   5. If membership is leave:
      1. If the sender matches state_key, allow if and only if that user's current membership state is invite, join, or knock.
      2. If the sender's current membership state is not join, reject.
      3. If the target user's current membership state is ban, and the sender's power level is less than the ban level, reject.
      4. If the sender's power level is greater than or equal to the kick level, and the target user's power level is less than the sender's power level, allow.
      5. Otherwise, reject.
   6. If membership is ban:
      1. If the sender's current membership state is not join, reject.
      2. If the sender's power level is greater than or equal to the ban level, and the target user's power level is less than the sender's power level, allow.
      3. Otherwise, reject.
   7. If membership is knock:
      1. {{< changed-in this="true" >}} If the join_rule is anything other than knock or knock_restricted, reject.
      2. If sender does not match state_key, reject.
      3. If the sender's current membership is not ban or join, allow.
      4. Otherwise, reject.
   8. Otherwise, the membership is unknown. Reject.
5. If the sender's current membership state is not join, reject.
6. If type is m.room.third_party_invite:
   1. Allow if and only if sender's current power level is greater than or equal to the invite level.
7. If the event type's required power level is greater than the sender's power level, reject.
8. If the event has a state_key that starts with an @ and does not match the sender, reject.
9. If type is m.room.power_levels:
   1. {{< added-in this="true" >}} If any of the keys users_default, events_default, state_default, ban, redact, kick, or invite in content are present and not an integer, reject.
   2. {{< added-in this="true" >}} If either of the keys events or notifications in content are present and not a dictionary with values that are integers, reject.
   3. If users key in content is not a dictionary with keys that are valid user IDs with values that are integers, reject.
   4. If there is no previous m.room.power_levels event in the room, allow.
   5. For the keys users_default, events_default, state_default, ban, redact, kick, invite check if they were added, changed or removed. For each found alteration:
      1. If the current value is higher than the sender's current power level, reject.
      2. If the new value is higher than the sender's current power level, reject.
   6. For each entry being added, changed or removed in both the events, users, and notifications keys:
      1. If the current value is higher than the sender's current power level, reject.
      2. If the new value is higher than the sender's current power level, reject.
   7. For each entry being changed under the users key, other than the sender's own entry:
      1. If the current value is equal to the sender's current power level, reject.
   8. Otherwise, allow.
10. Otherwise, allow.

{{% boxes/note %}} Some consequences of these rules:

• Unless you are a member of the room, the only permitted operations (apart from the initial create/join) are: joining a public room; accepting or rejecting an invitation to a room.
• To unban somebody, you must have power level greater than or equal to both the kick and ban levels, and greater than the target user's power level. {{% /boxes/note %}}

Unchanged from v9

The following sections have not been modified since v9, but are included for completeness.

Redactions

{{% rver-fragment name="v9-redactions" %}}

Handling redactions

{{% rver-fragment name="v3-handling-redactions" %}}

Event IDs

{{% rver-fragment name="v4-event-ids" %}}

Event format

{{% rver-fragment name="v4-event-format" %}}

State resolution

{{% rver-fragment name="v2-state-res" %}}

Canonical JSON

{{% rver-fragment name="v6-canonical-json" %}}

Signing key validity period

{{% rver-fragment name="v5-signing-requirements" %}}