MIMI WG R. Mahy Internet-Draft Rohan Mahy Consulting Services Intended status: Informational 8 July 2024 Expires: 9 January 2025 Room Policy for the More Instant Messaging Interoperability (MIMI) Protocol draft-mahy-mimi-room-policy-00 Abstract This document describes a set of concrete room policies for the More Instant Messaging Interoperability (MIMI) Working Group. It describes several independent properties and policy attributes which can be combined to model a wide range of chat and multimedia conference types. About This Document This note is to be removed before publishing as an RFC. The latest revision of this draft can be found at https://rohanmahy.github.io/mimi-room-policy/draft-mahy-mimi-room- policy.html. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-mahy-mimi-room-policy/. Discussion of this document takes place on the MIMI WG Working Group mailing list (mailto:mimi@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/mimi/. Subscribe at https://www.ietf.org/mailman/listinfo/mimi/. Source for this draft and an issue tracker can be found at https://github.com/rohanmahy/mimi-room-policy. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Mahy Expires 9 January 2025 [Page 1] Internet-Draft MIMI Room Policy July 2024 Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 9 January 2025. Copyright Notice Copyright (c) 2024 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3 2.1. Moderation Terms . . . . . . . . . . . . . . . . . . . . 4 3. Room Capabilities . . . . . . . . . . . . . . . . . . . . . . 4 4. Room policy format syntax . . . . . . . . . . . . . . . . . . 5 4.1. Membership-related policy . . . . . . . . . . . . . . . . 5 4.2. Pre-authorized users . . . . . . . . . . . . . . . . . . 7 4.3. Delivery and Read notifications, Pseudonyms . . . . . . . 8 4.4. Link, Logging, History, and Bot policies . . . . . . . . 9 4.4.1. Link policies . . . . . . . . . . . . . . . . . . . . 11 4.4.2. Logging policies . . . . . . . . . . . . . . . . . . 11 4.4.3. Chat history policies . . . . . . . . . . . . . . . . 11 4.4.4. Chat bot policies . . . . . . . . . . . . . . . . . . 12 4.5. Extensibility of the policy format . . . . . . . . . . . 12 5. Role-Based Access Control . . . . . . . . . . . . . . . . . . 12 6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 8.1. Normative References . . . . . . . . . . . . . . . . . . 14 8.2. Informative References . . . . . . . . . . . . . . . . . 14 Appendix A. Complete TLS Presentation Language Syntax . . . . . 14 Appendix B. Example Roles and Permissions scheme . . . . . . . . 17 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 17 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 17 Mahy Expires 9 January 2025 [Page 2] Internet-Draft MIMI Room Policy July 2024 1. Introduction The MIMI architecture [I-D.ietf-mimi-arch] describes how each room has an associated policy. Providers offer a "policy envelope" of supported and allowed policy settings, from which the creator of a room selects a specific room policy. The room policy might further allow individual participants to make specific choices (for example, allowing but not requiring read-message notifications), while constraining other choices (for example, prohibiting self-deleting messages). Individual users can examine the room policy to determine if it is consistent with policies they accept either before or immediately on joining a room. Section 4.4 of [I-D.ietf-mimi-arch] Making rooms interoperable across existing clients is challenging, as rooms and clients can support different policies and capabilities across vendors and providers. Our goal is to balance the policy and authorization goals of the room with the policy and authorization goals of the end user, so we can support a broad range of vendors and providers. Each room is owned by one provider at a time. The owning provider controls the range of acceptable policies. The user responsible for the room can further choose among the acceptable policies. Users (regardless if on other providers) can either accept the policies of the room or not. However we want to make it as easy as possible for clients from other providers to comply with the room policy primitives without enumerating specific features or requiring all clients implementations to present an identical user experience. Configurable Role-based access control with permissions. An example scheme is described in the Appendix. 2. Conventions and Definitions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. Role: A long-lived position reflecting the privilege level of a participant in a room. Possible values are owner, admin, regular- user, visitor, none, or outcast. A role closely maps to the MUC concept of affiliation, not the MUC concept of role. Occupant: A user that has at least one client in the corresponding MLS group, and a role of owner, admin, regular-user, or visitor. Mahy Expires 9 January 2025 [Page 3] Internet-Draft MIMI Room Policy July 2024 Room ID: An identifier which uniquely identifies a room. User ID: An internal identifier which uniquely identifies a user. Nickname: The identifier by which a user is referred inside a room. Depending on the context it may be a display name, handle, pseudonym, or temporary identifier. The nickname in one room need not correlate with the nickname for the same user in a different room. Client ID: An internal identifier which uniquely identifies one client/device instance of one user account. *Persistent vs. Temporary rooms*: A temporary room is destroyed when the last occupant exits whereas a persistent room is not destroyed when the last occupant exist. As MLS has no notion of a group with no members, a persistent room could consist of a sequence of distinct MLS groups, zero or one of which would exist at a time. 2.1. Moderation Terms Knock: To request entry into a room. Ban: To remove a user from a room such that the user is not allowed to re-enter the room (until and unless the ban has been removed). A banned user has a role of "outcast". Typically this action is only used in an open or semi-open room. It is distinct than merely removing a user from an administered group. Kick: To temporarily remove a participant or visitor from a room. The user is allowed to re-enter the room at any time. Voice (noun): The privilege to send messages in a room. Revoke Voice: To remove the permission to send messages in a room. Grant Voice: To grant the permission to send messages in a room. Moderator: A client whose user has a role of admin or owner in the room. A moderator can ban users, and (when allowed in the room) can grant and revoke voice, kick individual clients, and grant access (ex: in response to a knock). 3. Room Capabilities Membership-Style: The overall approach of membership authorization in a room, which could be open, members-only (administrated), fixed- membership, or parent-dependent. Mahy Expires 9 January 2025 [Page 4] Internet-Draft MIMI Room Policy July 2024 Open room: An open room can be joined by any non-banned user. Members-Only room: A members-only room can only be joined by a user in the occupant list, or who is pre-authorized. Authorized users can add or remove users to the room. In an enterprise context, it is also common (but not required) for users from a particular domain, group, or workgroup to be pre-authorized to add themselves to a Members-Only room. Fixed-Membership room: Fixed-membership rooms have the list of occupants specified when they are created. Other users cannot be added. Occupants cannot leave or be removed, however a user can remove all its clients from the associated MLS group. The most common case of a fixed-membership room is a 1:1 conversation. This room membership style is used to implement Direct Message (DM) and Group DM features. Only a single fixed-membership room can exist for any unique set of occupants. Parent-dependent room: In a parent-dependent room, the list occupants of the room must be a strict subset of the occupants of the parent room. If a user leaves or is removed from the parent room, that user is automatically removed from any parent-dependent rooms of that parent. Multi-device vs. Single-device: A multi-device room can have multiple simultaneous clients of the same user as participants in the room. A single-device room can have a maximum of one client per user in the room at any moment. Knock-Enabled vs. Knock-Disabled: In a knock-enabled room, non-banned users are allowed to programmatically request entry into the room. In a knock-disabled room this functionality is disabled. Moderated vs. Unmoderated: An an unmoderated room, any occupant can send messages to the room. In a moderated room, only occupants who have "voice" can send messages to the room. 4. Room policy format syntax 4.1. Membership-related policy The membership_style of a room can be one of the following values: * open * members-only (default) * fixed-membership Mahy Expires 9 January 2025 [Page 5] Internet-Draft MIMI Room Policy July 2024 * parent-dependent enum { reserved(0) open(1), members-only(2), fixed-membership(3), parent-dependent(4), (255) } MembershipStyle; An open room allows any unbanned user. A members-only room allows only invited or preauthorized users to join. A fixed-membership room (which can be used for DMs or Group DMs) has a list of authorized users set at creation time that cannot be added to. A parent- dependent room always has a strict subset of the participants of its parent room. If the membership_style is parent-dependent the parent_room_uri MUST be set with the room ID of the parent. Otherwise the field is zero- length. If multi_device is true (the default), the MLS group may contain multiple clients per user. If false only a single client can be an MLS member at one time. If knock_allowed is true, a non-participant can send a knock requesting access to the target room. If false, a user cannot. This option can only be enabled if the membership_style is members-only. The default is false. If moderated is true, the room supports granting and revoking voice. The default is false. Mahy Expires 9 January 2025 [Page 6] Internet-Draft MIMI Room Policy July 2024 enum { false(0), true(1) } bool; struct { MembershipStyle membership_style; Uri parent_room_uri; bool multi_device; bool knock_allowed; bool moderated; bool persistent_room; bool password_protected; ... } RoomPolicy; If persistent_room is false, the room will be automatically deleted when the corresponding MLS group is destroyed (when there are no clients in the group). If persistent_room is true, the room policy will remain and a client whose user has appropriate authorization can create a new MLS group for the same room. (There is not a 1:1 correlation of MLS group to room ID in a persistent room.) If password_protected is true, the room requires a passcode or passphrase when a client of a new user requests access to the GroupInfo used to join a group. The default is false. 4.2. Pre-authorized users Mahy Expires 9 January 2025 [Page 7] Internet-Draft MIMI Room Policy July 2024 enum { reserved(0), system(1), owner(2), admin(3), regular_user(4), visitor(5), banned(6), (255) } Role; struct { Role target_role; /* preauth_domain consists of ASCII letters, digits, and hyphens */ opaque preauth_domain; /* the remaining fields are in the form of a URI */ opaque preauth_workgroup; opaque preauth_group; opaque preauth_user; } PreAuthPerRoleList; struct { ... PreAuthPerRoleList pre_auth_list; ... } RoomPolicy; In members-only rooms, it is convenient to pre-authorize specific users--or users from specific domains, workgroups/teams, and groups-- to specific roles. The workgroup, group, and user are expressed as a Uri. The domain is expressed in US-ASCII letters, digits, and hyphens only. If the domain is internationalized, the Internationalized Domain Names [RFC5890] conversion MUST be done before filling in this value. Note that the system role is used to authorize external proposals for operations for other users. For example, the system role can be used to authorize a provider to remove clients from groups when the corresponding user account is deleted. 4.3. Delivery and Read notifications, Pseudonyms Mahy Expires 9 January 2025 [Page 8] Internet-Draft MIMI Room Policy July 2024 enum { optional(0), required(1), forbidden(2) } Optionality; struct { ... Optionality delivery_notifications; Optionality read_receipts; bool pseudonymous_ids; ... } RoomPolicy; The delivery_notifications value can be set to "forbidden", "optional", or "required". If the value is set to "optional", the client uses its local configuration to determine if it should send delivery notifications in the group. The read_receipts value can be set to "forbidden", "optional", or "required". If the value is set to "optional", the client uses its local configuration to determine if it should send read receipts in the group. The format for delivery notifications and read receipts is described in Section 5.12 of [I-D.ietf-mimi-content]. If pseudonymous_ids is true, clients in the MLS group are free to use pseudonymous identifiers in their MLS credentials. Otherwise the policy of the room is that "real" long-term identifiers are required in MLS credentials in the room's corresponding MLS group. 4.4. Link, Logging, History, and Bot policies Mahy Expires 9 January 2025 [Page 9] Internet-Draft MIMI Room Policy July 2024 struct { bool on_request; Uri join_link; bool multiuser; uint32 expiration; Uri link_requests; } LinkPolicy; struct { Optionality logging; Uri logging_clients; Uri machine_readable_policy; Uri human_readable_policy; } LoggingPolicy; struct { Optionality history_sharing; Role who_can_share; bool automatically_share; uint32 max_time_period; } HistoryPolicy; struct { opaque name; opaque description; Uri homepage; Role bot_role; bool can_read; bool can_write; bool can_target_message_in_group; bool per_user_content; } Bot; struct { ... bool discoverable; LinkPolicy link_policy; LoggingPolicy logging_policy; HistoryPolicy history_sharing; Bot allowed_bots; ... } RoomPolicy; Mahy Expires 9 January 2025 [Page 10] Internet-Draft MIMI Room Policy July 2024 4.4.1. Link policies If discoverable is true, the room is searchable. Presumably this means the the only way to join the room in a client user interface is to be added by an administrator or to use a joining link. Inside the LinkPolicy are several fields that describe the behavior of links.If the on_request field is true, no joining link will be provided in the room policy; the client will need to fetch a joining link out-of-band or generate a valid one for itself. If present, the URI in link_requests can be used by the client to request an invite code. The value of join_link is empty and the other fields are ignored.If the on_request field is false, the join_link field will contain a joining link. If the link will work for multiple users, multiuser is true. The expiration field represents the time, in seconds after the start of the UNIX epoch (1-January-1970) when the link will expire. The link_requests field can be empty. 4.4.2. Logging policies Inside the LoggingPolicy, the logging field can be forbidden, optional, or required. If logging is forbidden then the other fields are empty. If logging is required, the list of logging_clients needs to contain at least one logging URI. Each provider should have no more than one logging client at a time in a room. The machine_readable_policy and human_readable_policy fields optionally contain pointers to the owning provider's machine readable and human readable logging policies, respectively. If logging is optional and there is at least one logging_client then logging is active for the room. 4.4.3. Chat history policies Inside the HistoryPolicy, if history_sharing is forbidden, this means that clients (including bots) are expected to not to share chat history with new joiners, in which case who_can_share is empty, automatically_share is false, and max_time_period is zero. Otherwise who_can_share is a list of roles that are authorized to share history (for example, only admins and owners can share). The values of none and outcast cannot be used in who_can_share. If automatically_share is true, clients can share history with new joiners without user initiation. The history that is shared is limited to max_time_period seconds worth of history. Mahy Expires 9 January 2025 [Page 11] Internet-Draft MIMI Room Policy July 2024 4.4.4. Chat bot policies Inside the RoomPolicy there is a list of allowed_bots. Each of which has several fields. The name, description, and homepage are merely descriptive. The bot_role indicates if the chat bot would be treated as a system-user, owner, admin, regular_user, or visitor. The can_read and can_write fields indicate if the chat bot is allowed to read messages or send messages in the MLS group, respectively. If can_target_message_in_group is true it indicates that the chat bot can send an MLS targeted message (see Section 2.2 of [I-D.ietf-mls- extensions]) or use a different conversation or out-of-band channel to send a message to specific individual users in the room. If per_user_content is true, the chat bot is allowed to send messages with distinct content to each member. (For example a poker bot could deal a different hand to each user in a chat).Users could set policies to reject or leave groups with bots rights that are inconsistent with the user's privacy goals. 4.5. Extensibility of the policy format Finally, The extensibility mechanism allows for future addition of new room policies. enum { null(0), boolean(1), number(2), string(3), jsonObject(4) } ExtType; struct { opaque name; ExtType type; opaque value; } PolicyExtension; struct { ... PolicyExtension policy_extensions; } RoomPolicy; foo 5. Role-Based Access Control Permissions Mahy Expires 9 January 2025 [Page 12] Internet-Draft MIMI Room Policy July 2024 * canSendMessage * canAddParticipant * canRemoveParticipant * canRemoveSelf * canReport * canBanish * canUnBanish * canKick * canRevokeVoice * canGrantVoice * canChangeRoomName,Subject,Avatar * canChangeOwnName,Presence,Mood,Avatar * canChangeRoomMembershipStyle * canChangeOtherPolicyAttribute * canDestroyRoom * canCreateJoinLink * canKnock * canAcceptKnock * MLS specific - update - reinit - PSK - external proposal - external commit Mahy Expires 9 January 2025 [Page 13] Internet-Draft MIMI Room Policy July 2024 6. Security Considerations TODO Security 7. IANA Considerations This document has no IANA actions. 8. References 8.1. Normative References [I-D.ietf-mimi-arch] Barnes, R., "An Architecture for More Instant Messaging Interoperability (MIMI)", Work in Progress, Internet- Draft, draft-ietf-mimi-arch-00, 2 April 2024, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC5890] Klensin, J., "Internationalized Domain Names for Applications (IDNA): Definitions and Document Framework", RFC 5890, DOI 10.17487/RFC5890, August 2010, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 8.2. Informative References [I-D.ietf-mimi-content] Mahy, R., "More Instant Messaging Interoperability (MIMI) message content", Work in Progress, Internet-Draft, draft- ietf-mimi-content-04, 10 June 2024, . Appendix A. Complete TLS Presentation Language Syntax Mahy Expires 9 January 2025 [Page 14] Internet-Draft MIMI Room Policy July 2024 enum { false(0), true(1) } bool; struct { /* a valid Uniform Resource Identifier (URI) */ opaque uri; } Uri; enum { optional(0), required(1), forbidden(2) } Optionality; enum { reserved(0), system(1), owner(2), admin(3), regular_user(4), visitor(5), banned(6), (255) } Role; struct { Role target_role; /* preauth_domain consists of ASCII letters, digits, and hyphens */ opaque preauth_domain; /* the remaining fields are in the form of a URI */ opaque preauth_workgroup; opaque preauth_group; opaque preauth_user; } PreAuthPerRoleList; enum { reserved(0) open(1), members-only(2), fixed-membership(3), parent-dependent(4), (255) } MembershipStyle; struct { Optionality logging; Mahy Expires 9 January 2025 [Page 15] Internet-Draft MIMI Room Policy July 2024 bool enabled; Uri logging_clients; Uri machine_readable_policy; Uri human_readable_policy; } LoggingPolicy; struct { bool on_request; Uri join_link; bool multiuser; uint32 expiration; Uri link_requests; } LinkPolicy; struct { opaque name; opaque description; Uri homepage; Role bot_role; bool can_read; bool can_write; bool can_target_message_in_group; bool per_user_content; } Bot; struct { Optionality history_sharing; Role who_can_share; bool automatically_share; uint32 max_time_period; } HistoryPolicy; enum { null(0), boolean(1), number(2), string(3), jsonObject(4) } ExtType; struct { opaque name; ExtType type; opaque value; } PolicyExtension; struct { MembershipStyle membership_style; Mahy Expires 9 January 2025 [Page 16] Internet-Draft MIMI Room Policy July 2024 bool multi_device; bool knock_allowed; bool moderated; bool password_protected; PreAuthPerRoleList pre_auth_list; Uri parent_room_uri; bool persistent_room; Optionality delivery_notifications; Optionality read_receipts; bool semi_anonymous_ids; bool discoverable; LinkPolicy link_policy; LoggingPolicy logging_policy; HistoryPolicy history_sharing; Bot allowed_bots; PolicyExtension policy_extensions; } RoomPolicy; RoomPolicy room_policy; Appendix B. Example Roles and Permissions scheme * Owner * Admin * Moderator * Ordinary-user * Guest Acknowledgments TODO acknowledge. Author's Address Rohan Mahy Rohan Mahy Consulting Services Email: rohan.ietf@gmail.com Mahy Expires 9 January 2025 [Page 17]