< draft-ietf-tls-dtls-rrc-01.txt		draft-ietf-tls-dtls-rrc-02.txt >
	TLS H. Tschofenig, Ed.		TLS H. Tschofenig, Ed.
	Internet-Draft T. Fossati		Internet-Draft T. Fossati
	Updates: 6347 (if approved) Arm Limited		Updates: 6347 (if approved) Arm Limited
	Intended status: Standards Track 25 October 2021		Intended status: Standards Track 26 November 2021
	Expires: 28 April 2022		Expires: 30 May 2022
	Return Routability Check for DTLS 1.2 and DTLS 1.3		Return Routability Check for DTLS 1.2 and DTLS 1.3
	draft-ietf-tls-dtls-rrc-01		draft-ietf-tls-dtls-rrc-02
	Abstract		Abstract
	This document specifies a return routability check for use in context		This document specifies a return routability check for use in context
	of the Connection ID (CID) construct for the Datagram Transport Layer		of the Connection ID (CID) construct for the Datagram Transport Layer
	Security (DTLS) protocol versions 1.2 and 1.3.		Security (DTLS) protocol versions 1.2 and 1.3.
	Discussion Venues		Discussion Venues
	This note is to be removed before publishing as an RFC.		This note is to be removed before publishing as an RFC.
	skipping to change at page 1, line 44 ¶		skipping to change at page 1, line 44 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on 28 April 2022.		This Internet-Draft will expire on 30 May 2022.
	Copyright Notice		Copyright Notice
	Copyright (c) 2021 IETF Trust and the persons identified as the		Copyright (c) 2021 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents (https://trustee.ietf.org/		Provisions Relating to IETF Documents (https://trustee.ietf.org/
	license-info) in effect on the date of publication of this document.		license-info) in effect on the date of publication of this document.
	Please review these documents carefully, as they describe your rights		Please review these documents carefully, as they describe your rights
	and restrictions with respect to this document. Code Components		and restrictions with respect to this document. Code Components
	extracted from this document must include Simplified BSD License text		extracted from this document must include Revised BSD License text as
	as described in Section 4.e of the Trust Legal Provisions and are		described in Section 4.e of the Trust Legal Provisions and are
	provided without warranty as described in the Simplified BSD License.		provided without warranty as described in the Revised BSD License.
	This document may contain material from IETF Documents or IETF		This document may contain material from IETF Documents or IETF
	Contributions published or made publicly available before November		Contributions published or made publicly available before November
	10, 2008. The person(s) controlling the copyright in some of this		10, 2008. The person(s) controlling the copyright in some of this
	material may not have granted the IETF Trust the right to allow		material may not have granted the IETF Trust the right to allow
	modifications of such material outside the IETF Standards Process.		modifications of such material outside the IETF Standards Process.
	Without obtaining an adequate license from the person(s) controlling		Without obtaining an adequate license from the person(s) controlling
	the copyright in such materials, this document may not be modified		the copyright in such materials, this document may not be modified
	outside the IETF Standards Process, and derivative works of it may		outside the IETF Standards Process, and derivative works of it may
	not be created outside the IETF Standards Process, except to format		not be created outside the IETF Standards Process, except to format
	skipping to change at page 3, line 46 ¶		skipping to change at page 3, line 46 ¶
	BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all		BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	This document assumes familiarity with the CID format and protocol		This document assumes familiarity with the CID format and protocol
	defined for DTLS 1.2 [I-D.ietf-tls-dtls-connection-id] and for DTLS		defined for DTLS 1.2 [I-D.ietf-tls-dtls-connection-id] and for DTLS
	1.3 [I-D.ietf-tls-dtls13]. The presentation language used in this		1.3 [I-D.ietf-tls-dtls13]. The presentation language used in this
	document is described in Section 4 of [RFC8446].		document is described in Section 4 of [RFC8446].
	3. RRC Extension		3. RRC Extension
	This specification uses the tls_flags extension defined in		The use of RRC is negotiated via the rrc DTLS-only extension. On
	[I-D.ietf-tls-tlsflags] to allow a client and a server to negotiate		connecting, the client includes the rrc extension in its ClientHello
	support for this extension.		if it wishes to use RRC. If the server is capable of meeting this
			requirement, it responds with a rrc extension in its ServerHello.
			The extension_type value for this extension is TBD1 and the
			extension_data field of this extension is empty. The client and
			server MUST NOT use RRC unless both sides have successfully exchanged
			rrc extensions.
	The RRC flag is assigned the value (TBD1) and is used in the		Note that the RRC extension applies to both DTLS 1.2 and DTLS 1.3.
	ClientHello (CH) and the ServerHello (SH).
	4. The Return Routability Check Message		4. The Return Routability Check Message
	When a record with CID is received that has the source address of the		When a record with CID is received that has the source address of the
	enclosing UDP datagram different from the one previously associated		enclosing UDP datagram different from the one previously associated
	with that CID, the receiver MUST NOT update its view of the peer's IP		with that CID, the receiver MUST NOT update its view of the peer's IP
	address and port number with the source specified in the UDP datagram		address and port number with the source specified in the UDP datagram
	before cryptographically validating the enclosed record(s) but		before cryptographically validating the enclosed record(s) but
	instead perform a return routability check.		instead perform a return routability check.
	enum {		enum {
	invalid(0),		invalid(0),
	change_cipher_spec(20),		change_cipher_spec(20),
	alert(21),		alert(21),
	handshake(22),		handshake(22),
	application_data(23),		application_data(23),
	heartbeat(24), /* RFC 6520 */		heartbeat(24), /* RFC 6520 */
	return_routability_check(TBD), /* NEW */		return_routability_check(TBD2), /* NEW */
	(255)		(255)
	} ContentType;		} ContentType;
	uint64 Cookie;		uint64 Cookie;
	enum {		enum {
	path_challenge(0),		path_challenge(0),
	path_response(1),		path_response(1),
	reserved(2..255)		reserved(2..255)
	} rrc_msg_type;		} rrc_msg_type;
	skipping to change at page 6, line 10 ¶		skipping to change at page 6, line 10 ¶
	5. Example		5. Example
	The example TLS 1.3 handshake shown in Figure 1 shows a client and a		The example TLS 1.3 handshake shown in Figure 1 shows a client and a
	server negotiating the support for CID and for the RRC extension.		server negotiating the support for CID and for the RRC extension.
	Client Server		Client Server
	Key ^ ClientHello		Key ^ ClientHello
	Exch | + key_share		Exch | + key_share
	| + signature_algorithms		| + signature_algorithms
	| + tls_flags (RRC)		| + rrc
	v + connection_id=empty		v + connection_id=empty
	-------->		-------->
	ServerHello ^ Key		ServerHello ^ Key
	+ key_share | Exch		+ key_share | Exch
	+ connection_id=100 |		+ connection_id=100 |
	+ tls_flags (RRC) v		+ rrc v
	{EncryptedExtensions} ^ Server		{EncryptedExtensions} ^ Server
	{CertificateRequest} v Params		{CertificateRequest} v Params
	{Certificate} ^		{Certificate} ^
	{CertificateVerify} | Auth		{CertificateVerify} | Auth
	<-------- {Finished} v		<-------- {Finished} v
	^ {Certificate}		^ {Certificate}
	Auth | {CertificateVerify}		Auth | {CertificateVerify}
	v {Finished} -------->		v {Finished} -------->
	[Application Data] <-------> [Application Data]		[Application Data] <-------> [Application Data]
	skipping to change at page 8, line 15 ¶		skipping to change at page 8, line 15 ¶
	6. Security and Privacy Considerations		6. Security and Privacy Considerations
	Note that the return routability checks do not protect against		Note that the return routability checks do not protect against
	flooding of third-parties if the attacker is on-path, as the attacker		flooding of third-parties if the attacker is on-path, as the attacker
	can redirect the return routability checks to the real peer (even if		can redirect the return routability checks to the real peer (even if
	those datagrams are cryptographically authenticated). On-path		those datagrams are cryptographically authenticated). On-path
	adversaries can, in general, pose a harm to connectivity.		adversaries can, in general, pose a harm to connectivity.
	7. IANA Considerations		7. IANA Considerations
	IANA is requested to allocate an entry to the TLS "ContentType"		IANA is requested to allocate an entry to the TLS ContentType
	registry, for the return_routability_check(TBD) defined in this		registry, for the return_routability_check(TBD2) defined in this
	document.		document. The return_routability_check content type is only
			applicable to DTLS 1.2 and 1.3.
	IANA is requested to allocate an entry to the TLS Flags registry in
	the tls_flags type:
	* Value: [[IANA please assign a value from the 32-63 value range.]]
	* Flag Name: RRC
	* Message: CH,SH		IANA is requested to allocate the extension code point (TBD1) for the
			rrc extension to the TLS ExtensionType Values registry as described
			in Table 1.
	* Recommended: Y		+=======+===========+=====+===========+=============+===========+
			| Value | Extension | TLS | DTLS-Only | Recommended | Reference |
			| | Name | 1.3 | | | |
			+=======+===========+=====+===========+=============+===========+
			| TBD1 | rrc | CH, | Y | N | RFC-THIS |
			| | | SH | | | |
			+-------+-----------+-----+-----------+-------------+-----------+
	* Reference: [[This document]]		Table 1: rrc entry in the TLS ExtensionType Values registry
	8. Open Issues		8. Open Issues
	Issues against this document are tracked at https://github.com/tlswg/		Issues against this document are tracked at https://github.com/tlswg/
	dtls-rrc/issues		dtls-rrc/issues
	9. Acknowledgments		9. Acknowledgments
	We would like to thank Achim Kraus, Hanno Becker, Hanno Boeck, Manuel		We would like to thank Achim Kraus, Hanno Becker, Hanno Boeck, Manuel
	Pegourie-Gonnard, Mohit Sahni and Rich Salz for their input to this		Pegourie-Gonnard, Mohit Sahni and Rich Salz for their input to this
	skipping to change at page 9, line 13 ¶		skipping to change at page 9, line 13 ¶
	ietf-tls-dtls-connection-id-13>.		ietf-tls-dtls-connection-id-13>.
	[I-D.ietf-tls-dtls13]		[I-D.ietf-tls-dtls13]
	Rescorla, E., Tschofenig, H., and N. Modadugu, "The		Rescorla, E., Tschofenig, H., and N. Modadugu, "The
	Datagram Transport Layer Security (DTLS) Protocol Version		Datagram Transport Layer Security (DTLS) Protocol Version
	1.3", Work in Progress, Internet-Draft, draft-ietf-tls-		1.3", Work in Progress, Internet-Draft, draft-ietf-tls-
	dtls13-43, 30 April 2021,		dtls13-43, 30 April 2021,
	<https://datatracker.ietf.org/doc/html/draft-ietf-tls-		<https://datatracker.ietf.org/doc/html/draft-ietf-tls-
	dtls13-43>.		dtls13-43>.
	[I-D.ietf-tls-tlsflags]
	Nir, Y., "A Flags Extension for TLS 1.3", Work in
	Progress, Internet-Draft, draft-ietf-tls-tlsflags-06, 13
	July 2021, <https://datatracker.ietf.org/doc/html/draft-
	ietf-tls-tlsflags-06>.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/rfc/rfc2119>.		<https://www.rfc-editor.org/rfc/rfc2119>.
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.		May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
	[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol		[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
	Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,		Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
	<https://www.rfc-editor.org/rfc/rfc8446>.		<https://www.rfc-editor.org/rfc/rfc8446>.
	Appendix A. History		Appendix A. History
	RFC EDITOR: PLEASE REMOVE THE THIS SECTION		// RFC EDITOR: PLEASE REMOVE THIS SECTION
			draft-ietf-tls-dtls-rrc-02
			* Undo the TLS flags extension for negotiating RRC, use a new
			extension type
	draft-ietf-tls-dtls-rrc-01		draft-ietf-tls-dtls-rrc-01
	* Use the TLS flags extension for negotiating RRC		* Use the TLS flags extension for negotiating RRC
	* Enhanced IANA consideration section		* Enhanced IANA consideration section
	* Expanded example section		* Expanded example section
	* Revamp message layout:		* Revamp message layout:
End of changes. 15 change blocks.
	35 lines changed or deleted		40 lines changed or added
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