Internet DRAFT - draft-ietf-avtcore-rfc7983bis
draft-ietf-avtcore-rfc7983bis
AVTCORE Working Group B. Aboba
INTERNET-DRAFT Microsoft Corporation
Updates: 7983, 5764 G. Salgueiro
Category: Standards Track Cisco Systems
Expires: September 30, 2023 C. Perkins
University of Glasgow
26 March 2023
Multiplexing Scheme Updates for QUIC
draft-ietf-avtcore-rfc7983bis-09.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 September 30, 2023.
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Copyright Notice
Copyright (c) 2023 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
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provided without warranty as described in the Revised 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
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
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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 Traversal Using Relays around NAT
(TURN) Channel packets arriving on a single port. This document
updates [RFC7983] and "Datagram Transport Layer Security (DTLS)
Extension to Establish Keys for the Secure Real-time Transport
Protocol (SRTP)" [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.
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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.
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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
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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
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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 adversely impacted by a vulnerability in the QUIC
implementation.
5. IANA Considerations
In the TLS ContentType registry, IANA will replace references to RFC
7983 with references to this document.
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, <http://www.rfc-
editor.org/info/rfc2119>.
[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, <http://www.rfc-editor.org/info/rfc3550>.
[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,
<http://www.rfc-editor.org/info/rfc3711>.
[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, <http://www.rfc-
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editor.org/info/rfc5764>.
[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,
<https://www.rfc-editor.org/info/rfc7983>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119
Key Words", RFC 8174, DOI 10.17487/RFC8174, May 2017,
<https://www.rfc-editor.org/info/rfc8174>.
[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,
<https://www.rfc-editor.org/info/rfc8489>.
[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, <https://www.rfc-
editor.org/info/rfc8656>.
[RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", RFC 9000, DOI
10.17487/RFC9000, May 2021, <https://www.rfc-
editor.org/info/rfc9000>.
[RFC9001] Thomson, M., Ed. and S. Turner, Ed., "Using TLS to Secure
QUIC", RFC 9001, DOI 10.17487/RFC9001, May 2021,
<https://www.rfc-editor.org/info/rfc9001>.
[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,
<https://www.rfc-editor.org/info/rfc9147>.
[RFC9287] Thomson, M., "Greasing the QUIC Bit", RFC 9287, DOI
10.17487/RFC9287, August 2022, <https://www.rfc-
editor.org/info/rfc9287>.
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.
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[I-D.ietf-quic-v2]
Duke, M., "QUIC Version 2", draft-ietf-quic-v2 (work in
progress), December 15, 2022.
[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, <http://www.rfc-
editor.org/info/rfc6189>.
[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, <https://github.com/w3c/p2p-
webtransport>
[P2P-QUIC-TRIAL]
Hampson, S., "RTCQuicTransport Coming to an Origin Trial
Near You (Chrome 73)", January 2019,
<https://developers.google.com/web/updates/
2019/01/rtcquictransport-api>
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
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Glasgow G12 8QQ
United Kingdom
Email: csp@csperkins.org
Aboba, et. al Standards Track [Page 10]
