AVTCORE Working Group B. Aboba INTERNET-DRAFT Microsoft Corporation Updates: 7983, 5764 G. Salgueiro Category: Standards Track Cisco Systems Expires: July 30, 2023 C. Perkins University of Glasgow 28 January 2023 Multiplexing Scheme Updates for QUIC draft-ietf-avtcore-rfc7983bis-08.txt Abstract RFC 7983 defines a scheme for a Real-time Transport Protocol (RTP) receiver to demultiplex Datagram Transport Layer Security (DTLS), Session Traversal Utilities for NAT (STUN), Secure Real-time Transport Protocol (SRTP) / Secure Real-time Transport Control Protocol (SRTCP), ZRTP and Traversal Using Relays around NAT (TURN) Channel packets arriving on a single port. This document updates RFC 7983 and RFC 5764 to also allow QUIC packets to be multiplexed on a single receiving socket. 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 http://datatracker.ietf.org/drafts/current/. 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 July 30, 2023. Aboba, et. al Standards Track [Page 1] INTERNET-DRAFT Multiplexing Scheme Updates for QUIC 28 January 2023 Copyright Notice Copyright (c) 2022 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 (http://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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. Multiplexing of TURN Channels . . . . . . . . . . . . . . . . 4 3. Updates to RFC 7983 . . . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations . . . . . . . . . . . . . . . . . . . 7 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.1. Normative References . . . . . . . . . . . . . . . . . . 7 6.2. Informative References . . . . . . . . . . . . . . . . . 8 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Aboba, et. al Standards Track [Page 2] INTERNET-DRAFT Multiplexing Scheme Updates for QUIC 28 January 2023 1. Introduction "Multiplexing Scheme Updates for Secure Real-time Transport Protocol (SRTP) Extension for Datagram Transport Layer Security (DTLS)" [RFC7983] defines a scheme for a Real-time Transport Protocol (RTP) [RFC3550] receiver to demultiplex DTLS [RFC9147], Session Traversal Utilities for NAT (STUN) [RFC8489], Secure Real-time Transport Protocol (SRTP) / Secure Real-time Transport Control Protocol (SRTCP) [RFC3711], ZRTP [RFC6189] and TURN Channel packets arriving on a single port. This document updates [RFC7983] and [RFC5764] to also allow QUIC [RFC9000] to be multiplexed on the same port. The multiplexing scheme described in this document supports multiple use cases. Peer-to-peer QUIC in WebRTC scenarios, described in [P2P-QUIC] [P2P-QUIC-TRIAL], transports audio and video over SRTP, alongside QUIC, used for data exchange. For this use case, SRTP [RFC3711] is keyed using DTLS-SRTP [RFC5764] and therefore SRTP/SRTCP [RFC3550], STUN, TURN, DTLS and QUIC need to be multiplexed on the same port. Were SRTP to be keyed using QUIC-SRTP (not yet specified), SRTP/SRTCP, STUN, TURN and QUIC would need to be multiplexed on the same port. Where QUIC is used for peer-to-peer transport of data as well as RTP/RTCP [I-D.ietf-avtcore-rtp-over-quic] STUN, TURN and QUIC need to be multiplexed on the same port. While the scheme described in this document is compatible with QUIC version 2 [I-D.ietf-quic-v2], it is not compatible with QUIC bit greasing [RFC9287]. As a result, endpoints that wish to use multiplexing on their socket MUST NOT send the grease_quic_bit transport parameter. 1.1. Terminology 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. Aboba, et. al Standards Track [Page 3] INTERNET-DRAFT Multiplexing Scheme Updates for QUIC 28 January 2023 2. Multiplexing of TURN Channels TURN channels are an optimization where data packets are exchanged with a 4-byte prefix instead of the standard 36-byte STUN overhead (see Section 3.5 of [RFC8656]). [RFC7983] allocates the values from 64 to 79 in order to allow TURN channels to be demultiplexed when the TURN Client does the channel binding request in combination with the demultiplexing scheme described in [RFC7983]. In the absence of QUIC bit greasing, the first octet of a QUIC packet (e.g. a short header packet in QUIC v1 or v2) may fall in the range 64 to 127, thereby overlapping with the allocated range for TURN channels of 64 to 79. However, in practice this overlap does not represent a problem. TURN channel packets will only be received from a TURN server to which TURN allocation and channel-binding requests have been sent. Therefore a TURN client receiving packets from the source IP address and port of a TURN server only needs to disambiguate STUN (i.e. regular TURN) packets from TURN channel packets; (S)RTP, (S)RTCP, ZRTP, DTLS or QUIC packets will not be sent from a source IP address and port that had previously responded to TURN allocation or channel-binding requests. As a result, if the source IP address and port of a packet does not match that of a responding TURN server, a packet with a first octet of 64 to 127 can be unambiguously demultiplexed as QUIC. Aboba, et. al Standards Track [Page 4] INTERNET-DRAFT Multiplexing Scheme Updates for QUIC 28 January 2023 3. Updates to RFC 7983 This document updates the text in Section 7 of [RFC7983] (which in turn updates [RFC5764]) as follows: OLD TEXT The process for demultiplexing a packet is as follows. The receiver looks at the first byte of the packet. If the value of this byte is in between 0 and 3 (inclusive), then the packet is STUN. If the value is between 16 and 19 (inclusive), then the packet is ZRTP. If the value is between 20 and 63 (inclusive), then the packet is DTLS. If the value is between 64 and 79 (inclusive), then the packet is TURN Channel. If the value is in between 128 and 191 (inclusive), then the packet is RTP (or RTCP, if both RTCP and RTP are being multiplexed over the same destination port). If the value does not match any known range, then the packet MUST be dropped and an alert MAY be logged. This process is summarized in Figure 3. +----------------+ | [0..3] -+--> forward to STUN | | | [16..19] -+--> forward to ZRTP | | packet --> | [20..63] -+--> forward to DTLS | | | [64..79] -+--> forward to TURN Channel | | | [128..191] -+--> forward to RTP/RTCP +----------------+ Figure 3: The DTLS-SRTP receiver's packet demultiplexing algorithm. END OLD TEXT Aboba, et. al Standards Track [Page 5] INTERNET-DRAFT Multiplexing Scheme Updates for QUIC 28 January 2023 NEW TEXT The process for demultiplexing a packet is as follows. The receiver looks at the first byte of the packet. If the value of this byte is between 0 and 3 (inclusive), then the packet is STUN. If the value is between 16 and 19 (inclusive), then the packet is ZRTP. If the value is between 20 and 63 (inclusive), then the packet is DTLS. If the value is between 128 and 191 (inclusive) then the packet is RTP (or RTCP, if both RTCP and RTP are being multiplexed over the same destination port). If the value is between 80 and 127 (inclusive) or between 192 and 255 (inclusive) then the packet is QUIC. If the value is between 64 and 79 (inclusive) and the packet has a source IP address and port of a responding TURN server, then the packet is TURN channel; if the source IP address and port is not that of a responding TURN server, then the packet is QUIC. If the value does not match any known range, then the packet MUST be dropped and an alert MAY be logged. This process is summarized in Figure 3. +----------------+ | [0..3] -+--> forward to STUN | | | [4..15] -+--> DROP | | | [16..19] -+--> forward to ZRTP | | packet --> | [20..63] -+--> forward to DTLS | | | [64..79] -+--> forward to TURN Channel | | (if from TURN server), else QUIC | [80..127] -+--> forward to QUIC | | | [128..191] -+--> forward to RTP/RTCP | | | [192..255] -+--> forward to QUIC +----------------+ Figure 3: The receiver's packet demultiplexing algorithm. Note: Endpoints that wish to demultiplex QUIC MUST NOT send the grease_quic_bit transport parameter, described in [RFC9287]. END NEW TEXT Aboba, et. al Standards Track [Page 6] INTERNET-DRAFT Multiplexing Scheme Updates for QUIC 28 January 2023 4. Security Considerations The solution discussed in this document could potentially introduce some additional security issues beyond those described in [RFC7983]. These additional concerns are described below. In order to support multiplexing of QUIC, this document adds logic to the scheme defined in [RFC7983]. If mis-implemented, the logic could potentially mis-classify packets, exposing protocol handlers to unexpected input. When QUIC is used solely for data exchange, the TLS-within-QUIC exchange [RFC9001] derives keys used solely to protect QUIC data packets. If properly implemented, this should not affect the transport of SRTP nor the derivation of SRTP keys via DTLS-SRTP. However, if a future specification were to define use of the TLS- within-QUIC exchange to derive SRTP keys, both transport and SRTP key derivation could be aversely impacted by a vulnerability in the QUIC implementation. 5. IANA Considerations This document does not require actions by IANA. 6. References 6.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, July 2003, . [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. Norrman, "The Secure Real-time Transport Protocol (SRTP)", RFC 3711, DOI 10.17487/RFC3711, March 2004, . [RFC5764] McGrew, D. and E. Rescorla, "Datagram Transport Layer Security (DTLS) Extension to Establish Keys for the Secure Real-time Transport Protocol (SRTP)", RFC 5764, DOI 10.17487/RFC5764, May 2010, . Aboba, et. al Standards Track [Page 7] INTERNET-DRAFT Multiplexing Scheme Updates for QUIC 28 January 2023 [RFC7983] Petit-Huguenin, M. and G. Salgueiro, "Multiplexing Scheme Updates for Secure Real-time Transport Protocol (SRTP) Extension for Datagram Transport Layer Security (DTLS)", RFC 7983, DOI 10.17487/RFC7983, September 2016, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8489] Petit-Huguenin, M., Salgueiro, G., Rosenberg, J., Wing, D., Mahy, R. and P. Matthews, "Session Traversal Utilities for NAT (STUN)", RFC 8489, DOI 10.17487/RFC8489, February 2020, . [RFC8656] Reddy, T., Johnston, A., Matthews, P. and J. Rosenberg, "Traversal Using Relays around NAT (TURN): Relay Extensions to Session Traversal Utilities for NAT (STUN)", RFC 8656, DOI 10.17487/RFC8656, February 2020, . [RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Multiplexed and Secure Transport", RFC 9000, DOI 10.17487/RFC9000, May 2021, . [RFC9001] Thomson, M., Ed. and S. Turner, Ed., "Using TLS to Secure QUIC", RFC 9001, DOI 10.17487/RFC9001, May 2021, . [RFC9147] Rescorla, E., Tschofenig, H., and N. Modadugu, "The Datagram Transport Layer Security (DTLS) Protocol Version 1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022, . [RFC9287] Thomson, M., "Greasing the QUIC Bit", RFC 9287, DOI 10.17487/RFC9287, August 2022, . 6.2. Informative References [I-D.ietf-avtcore-rtp-over-quic] Ott, J. and M. Engelbart, "RTP over QUIC", draft-ietf- avtcore-rtp-over-quic (work in progress), October 24, 2022. [I-D.ietf-quic-v2] Duke, M., "QUIC Version 2", draft-ietf-quic-v2 (work in progress), December 15, 2022. Aboba, et. al Standards Track [Page 8] INTERNET-DRAFT Multiplexing Scheme Updates for QUIC 28 January 2023 [RFC6189] Zimmermann, P., Johnston, A., Ed., and J. Callas, "ZRTP: Media Path Key Agreement for Unicast Secure RTP", RFC 6189, DOI 10.17487/RFC6189, April 2011, . [P2P-QUIC] Thatcher, P., Aboba, B. and R. Raymond, "QUIC API For Peer- to-Peer Connections", W3C ORTC Community Group Draft (work in progress), 23 May 2021, [P2P-QUIC-TRIAL] Hampson, S., "RTCQuicTransport Coming to an Origin Trial Near You (Chrome 73)", January 2019, Acknowledgments We would like to thank Martin Thomson, Roni Even, Jonathan Lennox and other participants in the IETF QUIC and AVTCORE working groups for their discussion of the QUIC multiplexing issue, and their input relating to potential solutions. Authors' Addresses Bernard Aboba Microsoft Corporation One Microsoft Way Redmond, WA 98052 United States of America Email: bernard.aboba@gmail.com Gonzalo Salgueiro Cisco Systems 7200-12 Kit Creek Road Research Triangle Park, NC 27709 United States of America Email: gsalguei@cisco.com Colin Perkins School of Computing Science University of Glasgow Glasgow G12 8QQ United Kingdom Email: csp@csperkins.org Aboba, et. al Standards Track [Page 9]