Return Routability Check for DTLS 1.2 and DTLS 1.3
draft-ietf-tls-dtls-rrc-06
The information below is for an old version of the document.
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|---|---|---|---|
| Authors | Hannes Tschofenig , Achim Kraus , Thomas Fossati | ||
| Last updated | 2022-07-11 (Latest revision 2022-07-06) | ||
| Replaces | draft-tschofenig-tls-dtls-rrc | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-tls-dtls-rrc-06
TLS H. Tschofenig, Ed.
Internet-Draft Arm Limited
Updates: 6347, 9147 (if approved) A. Kraus
Intended status: Standards Track
Expires: 7 January 2023 T. Fossati
Arm Limited
6 July 2022
Return Routability Check for DTLS 1.2 and DTLS 1.3
draft-ietf-tls-dtls-rrc-06
Abstract
This document specifies a return routability check for use in context
of the Connection ID (CID) construct for the Datagram Transport Layer
Security (DTLS) protocol versions 1.2 and 1.3.
Discussion Venues
This note is to be removed before publishing as an RFC.
Discussion of this document takes place on the Transport Layer
Security Working Group mailing list (tls@ietf.org), which is archived
at https://mailarchive.ietf.org/arch/browse/tls/.
Source for this draft and an issue tracker can be found at
https://github.com/tlswg/dtls-rrc.
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/.
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 7 January 2023.
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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 (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 Terminology . . . . . . . . . . . . . . . . . 4
3. RRC Extension . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Return Routability Check Message Types . . . . . . . . . . . 4
5. RRC and CID Interplay . . . . . . . . . . . . . . . . . . . . 5
6. Attacker Model . . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Amplification . . . . . . . . . . . . . . . . . . . . . . 7
6.2. Off-Path Packet Forwarding . . . . . . . . . . . . . . . 7
7. Path Validation Procedure . . . . . . . . . . . . . . . . . . 11
7.1. Basic . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.2. Enhanced . . . . . . . . . . . . . . . . . . . . . . . . 12
7.3. Path Challenge Requirements . . . . . . . . . . . . . . 13
7.4. Path Response/Drop Requirements . . . . . . . . . . . . . 14
7.5. Timer Choice . . . . . . . . . . . . . . . . . . . . . . 14
8. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
9. Security and Privacy Considerations . . . . . . . . . . . . . 17
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
10.1. New TLS ContentType . . . . . . . . . . . . . . . . . . 17
10.2. New TLS ExtensionType . . . . . . . . . . . . . . . . . 17
10.3. New RRC Message Type Sub-registry . . . . . . . . . . . 18
11. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 19
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
13.1. Normative References . . . . . . . . . . . . . . . . . . 19
13.2. Informative References . . . . . . . . . . . . . . . . . 19
Appendix A. History . . . . . . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
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1. Introduction
In "classical" DTLS, selecting a security context of an incoming DTLS
record is accomplished with the help of the 5-tuple, i.e. source IP
address, source port, transport protocol, destination IP address, and
destination port. Changes to this 5 tuple can happen for a variety
reasons over the lifetime of the DTLS session. In the IoT context,
NAT rebinding is common with sleepy devices. Other examples include
end host mobility and multi-homing. Without CID, if the source IP
address and/or source port changes during the lifetime of an ongoing
DTLS session then the receiver will be unable to locate the correct
security context. As a result, the DTLS handshake has to be re-run.
Of course, it is not necessary to re-run the full handshake if
session resumption is supported and negotiated.
A CID is an identifier carried in the record layer header of a DTLS
datagram that gives the receiver additional information for selecting
the appropriate security context. The CID mechanism has been
specified in [RFC9146] for DTLS 1.2 and in [RFC9147] for DTLS 1.3.
Section 6 of [RFC9146] describes how the use of CID increases the
attack surface by providing both on-path and off-path attackers an
opportunity for (D)DoS. It then goes on describing the steps a DTLS
principal must take when a record with a CID is received that has a
source address (and/or port) different from the one currently
associated with the DTLS connection. However, the actual mechanism
for ensuring that the new peer address is willing to receive and
process DTLS records is left open. This document standardizes a
return routability check (RRC) as part of the DTLS protocol itself.
The return routability check is performed by the receiving peer
before the CID-to-IP address/port binding is updated in that peer's
session state database. This is done in order to provide more
confidence to the receiving peer that the sending peer is reachable
at the indicated address and port.
Note however that, irrespective of CID, if RRC has been successfully
negotiated by the peers, path validation can be used at any time by
either endpoint. For instance, an endpoint might use RRC to check
that a peer is still in possession of its address after a period of
quiescence.
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2. Conventions and 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.
This document assumes familiarity with the CID format and protocol
defined for DTLS 1.2 [RFC9146] and for DTLS 1.3 [RFC9147]. The
presentation language used in this document is described in Section 4
of [RFC8446].
This document reuses the definition of "anti-amplification limit"
from [RFC9000] to mean three times the amount of data received from
an unvalidated address. This includes all DTLS records originating
from that source address, excluding discarded ones.
3. RRC Extension
The use of RRC is negotiated via the rrc DTLS-only extension. On
connecting, the client includes the rrc extension in its ClientHello
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.
Note that the RRC extension applies to both DTLS 1.2 and DTLS 1.3.
4. Return Routability Check Message Types
This document defines the return_routability_check content type
(Figure 1) to carry Return Routability Check protocol messages.
The protocol consists of three message types: path_challenge,
path_response and path_drop that are used for path validation and
selection as described in Section 7.
Each message carries a Cookie, a 8-byte field containing arbitrary
data.
The return_routability_check message MUST be authenticated and
encrypted using the currently active security context.
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enum {
invalid(0),
change_cipher_spec(20),
alert(21),
handshake(22),
application_data(23),
heartbeat(24), /* RFC 6520 */
tls12_cid(25), /* RFC 9146, DTLS 1.2 only */
return_routability_check(TBD2), /* NEW */
(255)
} ContentType;
uint64 Cookie;
enum {
path_challenge(0),
path_response(1),
path_drop(2),
(255)
} rrc_msg_type;
struct {
rrc_msg_type msg_type;
select (return_routability_check.msg_type) {
case path_challenge: Cookie;
case path_response: Cookie;
case path_drop: Cookie;
};
} return_routability_check;
Figure 1: Return Routability Check Message
Future extensions or additions to the Return Routability Check
protocol may define new message types. Implementations MUST be able
to parse and ignore messages with an unknown msg_type.
5. RRC and CID Interplay
RRC offers an in-protocol mechanism to perform peer address
validation that complements the "peer address update" procedure
described in Section 6 of [RFC9146]. Specifically, when both CID
[RFC9146] and RRC have been successfully negotiated for the session,
if a record with CID is received that has the source address of the
enclosing UDP datagram different from the one currently associated
with that CID value, the receiver SHOULD perform a return routability
check as described in Section 7, unless an application layer specific
address validation mechanism can be triggered instead.
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6. Attacker Model
We define two classes of attackers, off-path and on-path, with
increasing capabilities (see Figure 2) partly following terminology
introduced in QUIC [RFC9000]:
* An off-path attacker is not on the original path between the DTLS
peers, but is able to observe packets on the original path and has
faster routing compared to the DTLS peers, which allows it to make
copies of the observed packets, race its copies to either peer and
consistently win the race.
* An on-path attacker is on the original path between the DTLS peers
and is therefore capable, compared to the off-path attacker, to
also drop and delay records at will.
Note that in general, attackers cannot craft DTLS records in a way
that would successfully pass verification due to the cryptographic
protections applied by the DTLS record layer.
.--> .------------------------------------. <--.
| | Inspect un-encrypted portions | |
| +------------------------------------+ |
| | Inject | |
off-path +------------------------------------+ |
| | Reorder | |
| +------------------------------------+ |
| | Modify un-authenticated portions | on-path
'--> +------------------------------------+ |
| Delay | |
+------------------------------------+ |
| Drop | |
+------------------------------------+ |
| Manipulate the packetization layer | |
'------------------------------------' <--'
Figure 2: Attackers capabilities
RRC is designed to defend against the following attacks:
* On-path and off-path attackers that try to create an amplification
attack by spoofing the source address of the victim (Section 6.1).
* Off-path attackers that try to put themselves on-path
(Section 6.2), provided that the enhanced path validation
algorithm is used (Section 7.2).
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6.1. Amplification
Both on-path and off-path attackers can send a packet (either by
modifying it on the fly, or by copying, injecting and racing it,
respectively) with the source address modified to that of a victim
host. If the traffic generated by the server in response is larger
compared to the received packet (e.g., a CoAP server returning an
MTU's worth of data from a 20-bytes GET request) the attacker can use
the server as a traffic amplifier toward the victim.
When receiving a packet with a known CID and a spoofed source
address, an RRC-capable endpoint will not send a (potentially large)
response but instead a small path_challenge message to the victim
host. Since the host is not able to decrypt it and generate a valid
path_response, the address validation fails, which in turn keeps the
original address binding unaltered.
Note that in case of an off-path attacker, the original packet still
reaches the intended destination; therefore, an implementation could
use a different strategy to mitigate the attack.
6.2. Off-Path Packet Forwarding
An off-path attacker that can observe packets might forward copies of
genuine packets to endpoints over a different path. If the copied
packet arrives before the genuine packet, this will appear as a path
change, like in a genuine NAT rebinding occurrence. Any genuine
packet will be discarded as a duplicate. If the attacker is able to
continue forwarding packets, it might be able to cause migration to a
path via the attacker. This places the attacker on-path, giving it
the ability to observe or drop all subsequent packets.
This style of attack relies on the attacker using a path that has the
same or better characteristics (e.g., due to a more favourable
service level agreements) as the direct path between endpoints. The
attack is more reliable if relatively few packets are sent or if
packet loss coincides with the attempted attack.
A data packet received on the original path that increases the
maximum received packet number will cause the endpoint to move back
to that path. Therefore, eliciting packets on this path increases
the likelihood that the attack is unsuccessful. Note however that,
unlike QUIC, DTLS has no "non-probing" packets so this would require
application specific mechanisms.
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Figure 3 illustrates the case where a receiver receives a packet with
a new source IP address and/or new port number. In order to
determine whether this path change was not triggered by an off-path
attacker, the receiver will send a RRC message of type path_challenge
(1) on the old path.
new old
path .----------. path
| |
.-----+ Receiver +-----.
| | | |
| '----------' |
| |
| |
| |
.----+------. |
/ Attacker? / |
'------+----' |
| |
| |
| |
| .----------. |
| | | |
'-----+ Sender +-----'
| |
'----------'
Figure 3: Off-Path Packet Forwarding Scenario
Three cases need to be considered:
Case 1: The old path is dead (e.g., due to a NAT rebinding), which
leads to a timeout of (1).
As shown in Figure 4, a path_challenge (2) needs to be sent on the
new path. If the sender replies with a path_response on the new path
(3), the switch to the new path is considered legitimate.
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new old
path .----------. path
.------>| +-------.
| .-----+ Receiver +...... |
| | .---+ | . |
| | | '----------' . |
path- 3 | | . 1 path-
response | | | . | challenge
| | | . |
.--|-+-|----------------------v--.
/ | | NAT X / timeout
'----|-+-|-----------------------'
| | | .
| | 2 path- .
| | | challenge .
| | | .----------. .
| | '-->| | .
| '-----+ Sender +.....'
'-------+ |
'----------'
Figure 4: Old path is dead
Case 2: The old path is alive but not preferred.
This case is shown in Figure 5 whereby the sender replies with a
path_drop message (2) on the old path. This triggers the receiver to
send a path_challenge (3) on the new path. The sender will reply
with a path_response (4) on the new path, thus providing confirmation
for the path migration.
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new old
path .----------. path
.------>| |<------.
| .-----+ Receiver +-----. |
| | .---+ +---. | |
| | | '----------' | | |
path- 4 | | path- 1 | |
response | | | challenge | | |
| | | | | |
.---------|-+-|----. .--|-+-|-----------.
/ AP/NAT A | | / / | | AP/NAT B /
'-----------|---|--' '----|-+-|---------'
| | | | | |
| | 3 path- | | 2 path-
| | | challenge | | | drop
| | | .----------. | | |
| | '-->| |<--' | |
| '-----+ Sender +-----' |
'-------+ |<------'
'----------'
Figure 5: Old path is not preferred
Case 3: The old path is alive and preferred.
This is most likely the result of an off-path attacker trying to
place itself on path. The receiver sends a path_challenge on the old
path and the sender replies with a path_response (2) on the old path.
The interaction is shown in Figure 6. This results in the connection
not being migrated to the new path, thus thwarting the attack.
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new old
path .----------. path
| +-------.
.-----+ Receiver +-----. |
| | |<--. | |
| '----------' | | |
| | | 1 path-
| | | | challenge
| | | |
.---+------. .--|-+-|-----.
/ off-path / / AP| / |NAT /
/ attacker / '----|-+-|---'
'------+---' | | |
| | | |
| path- 2 | |
| response | | |
| .----------. | | |
| | +---' | |
'-----+ Sender +-----' |
| |<------'
'----------'
Figure 6: Old path is preferred
Note that this defense is imperfect, but this is not considered a
serious problem. If the path via the attack is reliably faster than
the old path despite multiple attempts to use that old path, it is
not possible to distinguish between an attack and an improvement in
routing.
An endpoint could also use heuristics to improve detection of this
style of attack. For instance, NAT rebinding is improbable if
packets were recently received on the old path; similarly, rebinding
is rare on IPv6 paths. Endpoints can also look for duplicated
packets. Conversely, a change in connection ID is more likely to
indicate an intentional migration rather than an attack. Note that
changes in connection IDs are supported in DTLS 1.3 but not in DTLS
1.2.
7. Path Validation Procedure
The receiver that observes the peer's address or port update MUST
stop sending any buffered application data, or limit the data sent to
the unvalidated address to the anti-amplification limit.
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It then initiates the return routability check that proceeds as
described either in Section 7.2 or Section 7.1, depending on whether
the off-path attacker scenario described in Section 6.2 is to be
taken into account or not.
(The decision on what strategy to choose depends mainly on the threat
model, but may also be influenced by other considerations. Examples
of impacting factors include: the need to minimise implementation
complexity, privacy concerns, the need to reduce the time it takes to
switch path. The choice may be offered as a configuration option to
the user.)
After the path validation procedure is completed, any pending send
operation is resumed to the bound peer address.
Section 7.3 and Section 7.4 list the requirements for the initiator
and responder roles, broken down per protocol phase.
7.1. Basic
1. The receiver creates a return_routability_check message of type
path_challenge and places the unpredictable cookie into the
message.
2. The message is sent to the observed new address and a timer T
(see Section 7.5) is started.
3. The peer endpoint cryptographically verifies the received
return_routability_check message of type path_challenge and
responds by echoing the cookie value in a
return_routability_check message of type path_response.
4. When the initiator receives the return_routability_check message
of type path_response and verifies that it contains the sent
cookie, it updates the peer address binding.
5. If T expires the peer address binding is not updated.
7.2. Enhanced
1. The receiver creates a return_routability_check message of type
path_challenge and places the unpredictable cookie into the
message.
2. The message is sent to the previously valid address, which
corresponds to the old path. Additionally, a timer T, see
Section 7.5, is started.
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3. If the path is still functional, the peer endpoint
cryptographically verifies the received return_routability_check
message of type path_challenge. The action to be taken depends
on whether the path through which the message was received is the
preferred one or not anymore:
* If the path through which the message was received is
preferred, a return_routability_check message of type
path_response MUST be returned.
* If the path through which the message was received is not
preferred, a return_routability_check message of type
path_drop MUST be returned. In either case, the peer endpoint
echoes the cookie value in the response.
4. The initiator receives and verifies that the
return_routability_check message contains the previously sent
cookie. The actions taken by the initiator differ based on the
received message:
* When a return_routability_check message of type path_response
was received, the initiator MUST continue using the previously
valid address, i.e. no switch to the new path takes place and
the peer address binding is not updated.
* When a return_routability_check message of type path_drop was
received, the initiator MUST perform a return routability
check on the observed new address, as described in
Section 7.1.
5. If T expires the peer address binding is not updated. In this
case, the initiator MUST perform a return routability check on
the observed new address, as described in Section 7.1.
7.3. Path Challenge Requirements
* The initiator MAY send multiple return_routability_check messages
of type path_challenge to cater for packet loss on the probed
path.
- Each path_challenge SHOULD go into different transport packets.
(Note that the DTLS implementation may not have control over
the packetization done by the transport layer.)
- The transmission of subsequent path_challenge messages SHOULD
be paced to decrease the chance of loss.
- Each path_challenge message MUST contain random data.
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* The initiator MAY use padding using the record padding mechanism
available in DTLS 1.3 (and in DTLS 1.2, when CID is enabled on the
sending direction) up to the anti-amplification limit to probe if
the path MTU (PMTU) for the new path is still acceptable.
7.4. Path Response/Drop Requirements
* The responder MUST NOT delay sending an elicited path_response or
path_drop messages.
* The responder MUST send exactly one path_response or path_drop
message for each received path_challenge.
* The responder MUST send the path_response or the path_drop on the
path where the corresponding path_challenge has been received, so
that validation succeeds only if the path is functional in both
directions. The initiator MUST NOT enforce this behaviour.
* The initiator MUST silently discard any invalid path_response or
path_drop it receives.
Note that RRC does not cater for PMTU discovery on the reverse path.
If the responder wants to do PMTU discovery using RRC, it should
initiate a new path validation procedure.
7.5. Timer Choice
When setting T, implementations are cautioned that the new path could
have a longer round-trip time (RTT) than the original.
In settings where there is external information about the RTT of the
active path, implementations SHOULD use T = 3xRTT.
If an implementation has no way to obtain information regarding the
RTT of the active path, a value of 1s SHOULD be used.
Profiles for specific deployment environments -- for example,
constrained networks [I-D.ietf-uta-tls13-iot-profile] -- MAY specify
a different, more suitable value.
8. Example
The example TLS 1.3 handshake shown in Figure 7 shows a client and a
server negotiating the support for CID and for the RRC extension.
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Client Server
Key ^ ClientHello
Exch | + key_share
| + signature_algorithms
| + rrc
v + connection_id=empty
-------->
ServerHello ^ Key
+ key_share | Exch
+ connection_id=100 |
+ rrc v
{EncryptedExtensions} ^ Server
{CertificateRequest} v Params
{Certificate} ^
{CertificateVerify} | Auth
<-------- {Finished} v
^ {Certificate}
Auth | {CertificateVerify}
v {Finished} -------->
[Application Data] <-------> [Application Data]
+ Indicates noteworthy extensions sent in the
previously noted message.
* Indicates optional or situation-dependent
messages/extensions that are not always sent.
{} Indicates messages protected using keys
derived from a [sender]_handshake_traffic_secret.
[] Indicates messages protected using keys
derived from [sender]_application_traffic_secret_N.
Figure 7: Message Flow for Full TLS Handshake
Once a connection has been established the client and the server
exchange application payloads protected by DTLS with an unilaterally
used CIDs. In our case, the client is requested to use CID 100 for
records sent to the server.
At some point in the communication interaction the IP address used by
the client changes and, thanks to the CID usage, the security context
to interpret the record is successfully located by the server.
However, the server wants to test the reachability of the client at
his new IP address.
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Client Server
------ ------
Application Data ========>
<CID=100>
Src-IP=A
Dst-IP=Z
<======== Application Data
Src-IP=Z
Dst-IP=A
<<------------->>
<< Some >>
<< Time >>
<< Later >>
<<------------->>
Application Data ========>
<CID=100>
Src-IP=B
Dst-IP=Z
<<< Unverified IP
Address B >>
<-------- Return Routability Check
path_challenge(cookie)
Src-IP=Z
Dst-IP=B
Return Routability Check -------->
path_response(cookie)
Src-IP=B
Dst-IP=Z
<<< IP Address B
Verified >>
<======== Application Data
Src-IP=Z
Dst-IP=B
Figure 8: Return Routability Example
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9. Security and Privacy Considerations
Note that the return routability checks do not protect against
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
those datagrams are cryptographically authenticated). On-path
adversaries can, in general, pose a harm to connectivity.
When using DTLS 1.3, peers SHOULD avoid using the same CID on
multiple network paths, in particular when initiating connection
migration or when probing a new network path, as described in
Section 7, as an adversary can otherwise correlate the communication
interaction across those different paths. DTLS 1.3 provides
mechanisms to ensure that a new CID can always be used. In general,
an endpoint should proactively send a RequestConnectionId message to
ask for new CIDs as soon as the pool of spare CIDs is depleted (or
goes below a threshold). Also, in case a peer might have exhausted
available CIDs, a migrating endpoint could include NewConnectionId in
packets sent on the new path to make sure that the subsequent path
validation can use fresh CIDs.
Note that DTLS 1.2 does not offer the ability to request new CIDs
during the session lifetime since CIDs have the same life-span of the
connection. Therefore, deployments that use DTLS in multihoming
environments SHOULD refuse to use CIDs with DTLS 1.2 and switch to
DTLS 1.3 if the correlation privacy threat is a concern.
10. IANA Considerations
// RFC Editor: please replace RFCthis with this RFC number and remove
// this note.
10.1. New TLS ContentType
IANA is requested to allocate an entry to the TLS ContentType
registry, for the return_routability_check(TBD2) message defined in
this document. The return_routability_check content type is only
applicable to DTLS 1.2 and 1.3.
10.2. New TLS ExtensionType
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.
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+=======+===========+=====+===========+=============+===========+
| Value | Extension | TLS | DTLS-Only | Recommended | Reference |
| | Name | 1.3 | | | |
+=======+===========+=====+===========+=============+===========+
| TBD1 | rrc | CH, | Y | N | RFCthis |
| | | SH | | | |
+-------+-----------+-----+-----------+-------------+-----------+
Table 1: rrc entry in the TLS ExtensionType Values registry
10.3. New RRC Message Type Sub-registry
IANA is requested to create a new sub-registry for RRC Message Types
in the TLS Parameters registry [IANA.tls-parameters], with the policy
"expert review" [RFC8126].
Each entry in the registry must include:
Value:
A number in the range from 0 to 255 (decimal)
Description:
a brief description of the message
DTLS-Only:
RRC is only available in DTLS, therefore this column will be set
to Y for all the entries in this registry
Reference:
a reference document
The initial state of this sub-registry is as follows:
+=======+================+===========+===========+
| Value | Description | DTLS-Only | Reference |
+=======+================+===========+===========+
| 0 | path_challenge | Y | RFCthis |
+-------+----------------+-----------+-----------+
| 1 | path_response | Y | RFCthis |
+-------+----------------+-----------+-----------+
| 2 | path_drop | Y | RFCthis |
+-------+----------------+-----------+-----------+
| 3-255 | Unassigned | | |
+-------+----------------+-----------+-----------+
Table 2: Initial Entries in RRC Message Type
registry
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11. Open Issues
Issues against this document are tracked at https://github.com/tlswg/
dtls-rrc/issues
12. Acknowledgments
We would like to thank Achim Kraus, Hanno Becker, Hanno Boeck, Manuel
Pegourie-Gonnard, Mohit Sahni and Rich Salz for their input to this
document.
13. References
13.1. Normative References
[IANA.tls-parameters]
IANA, "Transport Layer Security (TLS) Parameters",
<https://www.iana.org/assignments/tls-parameters>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/rfc/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/rfc/rfc8446>.
[RFC9146] Rescorla, E., Ed., Tschofenig, H., Ed., Fossati, T., and
A. Kraus, "Connection Identifier for DTLS 1.2", RFC 9146,
DOI 10.17487/RFC9146, March 2022,
<https://www.rfc-editor.org/rfc/rfc9146>.
[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/rfc/rfc9147>.
13.2. Informative References
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[I-D.ietf-uta-tls13-iot-profile]
Tschofenig, H. and T. Fossati, "TLS/DTLS 1.3 Profiles for
the Internet of Things", Work in Progress, Internet-Draft,
draft-ietf-uta-tls13-iot-profile-04, 7 March 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-uta-
tls13-iot-profile-04>.
[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/rfc/rfc9000>.
Appendix A. History
// RFC EDITOR: PLEASE REMOVE THIS SECTION
draft-ietf-tls-dtls-rrc-06
* Add Achim as co-author
* Added IANA registry for RRC message types (#14)
* Small fix in the path validation algorithm (#15)
* Renamed path_delete to path_drop (#16)
* Added an "attacker model" section (#17, #31, #44, #45, #48)
* Add criteria for choosing between basic and enhanced path
validation (#18)
* Reorganise Section 4 a bit (#19)
* Small fix in Path Response/Drop Requirements section (#20)
* Add privacy considerations wrt CID reuse (#30)
draft-ietf-tls-dtls-rrc-05
* Added text about off-path packet forwarding
draft-ietf-tls-dtls-rrc-04
* Re-submitted draft to fix references
draft-ietf-tls-dtls-rrc-03
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* Added details for challenge-response exchange
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
* Use the TLS flags extension for negotiating RRC
* Enhanced IANA consideration section
* Expanded example section
* Revamp message layout:
- Use 8-byte fixed size cookies
- Explicitly separate path challenge from response
draft-ietf-tls-dtls-rrc-00
* Draft name changed after WG adoption
draft-tschofenig-tls-dtls-rrc-01
* Removed text that overlapped with draft-ietf-tls-dtls-connection-
id
draft-tschofenig-tls-dtls-rrc-00
* Initial version
Authors' Addresses
Hannes Tschofenig (editor)
Arm Limited
Email: hannes.tschofenig@arm.com
Achim Kraus
Email: achimkraus@gmx.net
Thomas Fossati
Arm Limited
Email: thomas.fossati@arm.com
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