Internet DRAFT - draft-ietf-lisp-sec
draft-ietf-lisp-sec
Network Working Group F. Maino
Internet-Draft Cisco Systems
Intended status: Standards Track V. Ermagan
Expires: January 8, 2023 Google
A. Cabellos
Universitat Politecnica de Catalunya
D. Saucez
Inria
July 7, 2022
LISP-Security (LISP-SEC)
draft-ietf-lisp-sec-29
Abstract
This memo specifies LISP-SEC, a set of security mechanisms that
provides origin authentication, integrity and anti-replay protection
to LISP's EID-to-RLOC mapping data conveyed via the mapping lookup
process. LISP-SEC also enables verification of authorization on EID-
prefix claims in Map-Reply messages.
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 January 8, 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
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
Maino, et al. Expires January 8, 2023 [Page 1]
Internet-Draft LISP-SEC July 2022
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
2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 3
3. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 4
4. LISP-SEC Threat Model . . . . . . . . . . . . . . . . . . . . 4
5. Protocol Operations . . . . . . . . . . . . . . . . . . . . . 5
6. LISP-SEC Control Messages Details . . . . . . . . . . . . . . 7
6.1. Encapsulated Control Message LISP-SEC Extensions . . . . 7
6.2. Map-Reply LISP-SEC Extensions . . . . . . . . . . . . . . 10
6.3. Map-Register LISP-SEC Extensions . . . . . . . . . . . . 11
6.4. ITR Processing: Generating a Map-Request . . . . . . . . 11
6.5. Encrypting and Decrypting an OTK . . . . . . . . . . . . 12
6.5.1. Unencrypted OTK . . . . . . . . . . . . . . . . . . . 14
6.6. Map-Resolver Processing . . . . . . . . . . . . . . . . . 14
6.7. Map-Server Processing . . . . . . . . . . . . . . . . . . 15
6.7.1. Generating a LISP-SEC Protected Encapsulated Map-
Request . . . . . . . . . . . . . . . . . . . . . . . 16
6.7.2. Generating a Proxy Map-Reply . . . . . . . . . . . . 17
6.8. ETR Processing . . . . . . . . . . . . . . . . . . . . . 17
6.9. ITR Processing: Receiving a Map-Reply . . . . . . . . . . 18
6.9.1. Map-Reply Record Validation . . . . . . . . . . . . . 20
7. Security Considerations . . . . . . . . . . . . . . . . . . . 21
7.1. Mapping System Security . . . . . . . . . . . . . . . . . 21
7.2. Random Number Generation . . . . . . . . . . . . . . . . 21
7.3. Map-Server and ETR Colocation . . . . . . . . . . . . . . 21
7.4. Deploying LISP-SEC . . . . . . . . . . . . . . . . . . . 22
7.5. Shared Keys Provisioning . . . . . . . . . . . . . . . . 22
7.6. Replay Attacks . . . . . . . . . . . . . . . . . . . . . 22
7.7. Message Privacy . . . . . . . . . . . . . . . . . . . . . 22
7.8. Denial of Service and Distributed Denial of Service
Attacks . . . . . . . . . . . . . . . . . . . . . . . . . 23
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
8.1. ECM AD Type Registry . . . . . . . . . . . . . . . . . . 23
8.2. Map-Reply AD Type Registry . . . . . . . . . . . . . . . 24
8.3. HMAC Functions . . . . . . . . . . . . . . . . . . . . . 24
8.4. Key Wrap Functions . . . . . . . . . . . . . . . . . . . 24
8.5. Key Derivation Functions . . . . . . . . . . . . . . . . 25
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 25
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
10.1. Normative References . . . . . . . . . . . . . . . . . . 25
10.2. Informational References . . . . . . . . . . . . . . . . 27
Maino, et al. Expires January 8, 2023 [Page 2]
Internet-Draft LISP-SEC July 2022
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
1. Introduction
The Locator/ID Separation Protocol
[I-D.ietf-lisp-rfc6830bis],[I-D.ietf-lisp-rfc6833bis] is a network-
layer-based protocol that enables separation of IP addresses into two
new numbering spaces: Endpoint Identifiers (EIDs) and Routing
Locators (RLOCs). EID-to-RLOC mappings are stored in a database, the
LISP Mapping System, and made available via the Map-Request/Map-Reply
lookup process. If these EID-to-RLOC mappings, carried through Map-
Reply messages, are transmitted without integrity protection, an
adversary can manipulate them and hijack the communication,
impersonate the requested EID, or mount Denial of Service or
Distributed Denial of Service attacks. Also, if the Map-Reply
message is transported unauthenticated, an adversarial LISP entity
can overclaim an EID-prefix and maliciously redirect traffic. The
LISP-SEC threat model, described in Section 4, is built on top of the
LISP threat model defined in [RFC7835], that includes a detailed
description of "overclaiming" attack.
This memo specifies LISP-SEC, a set of security mechanisms that
provides origin authentication, integrity and anti-replay protection
to LISP's EID-to-RLOC mapping data conveyed via mapping lookup
process. LISP-SEC also enables verification of authorization on EID-
prefix claims in Map-Reply messages, ensuring that the sender of a
Map-Reply that provides the location for a given EID-prefix is
entitled to do so according to the EID prefix registered in the
associated Map-Server. Map-Register/Map-Notify security, including
the right for a LISP entity to register an EID-prefix or to claim
presence at an RLOC, is out of the scope of LISP-SEC as those
protocols are protected by the security mechanisms specified in
[I-D.ietf-lisp-rfc6833bis]. However, LISP-SEC extends the Map-
Register message to allow an ITR to downgrade to non LISP-SEC Map-
Requests. Additional security considerations are described in
Section 6.
2. Requirements Notation
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.
Maino, et al. Expires January 8, 2023 [Page 3]
Internet-Draft LISP-SEC July 2022
3. Definition of Terms
One-Time Key (OTK): An ephemeral randomly generated key that must
be used for a single Map-Request/Map-Reply exchange.
ITR One-Time Key (ITR-OTK): The One-Time Key generated at the
Ingress Tunnel Router (ITR).
MS One-Time Key (MS-OTK): The One-Time Key generated at the Map-
Server.
Authentication Data (AD): Metadata that is included either in a
LISP Encapsulated Control Message (ECM) header, as defined in
[I-D.ietf-lisp-rfc6833bis], or in a Map-Reply message to support
confidentiality, integrity protection, and verification of EID-
prefix authorization.
OTK Authentication Data (OTK-AD): The portion of ECM
Authentication Data that contains a One-Time Key.
EID Authentication Data (EID-AD): The portion of ECM and Map-Reply
Authentication Data used for verification of EID-prefix
authorization.
Packet Authentication Data (PKT-AD): The portion of Map-Reply
Authentication Data used to protect the integrity of the Map-Reply
message.
For definitions of other terms, notably Map-Request, Map-Reply,
Ingress Tunnel Router (ITR), Egress Tunnel Router (ETR), Map-Server
(MS), and Map-Resolver (MR) please consult the LISP specification
[I-D.ietf-lisp-rfc6833bis].
4. LISP-SEC Threat Model
LISP-SEC addresses the control plane threats, described in section
3.7 and 3.8 of [RFC7835], that target EID-to-RLOC mappings, including
manipulations of Map-Request and Map-Reply messages, and malicious
ETR EID prefix overclaiming. LISP-SEC makes two main assumptions:
(1) the LISP mapping system is expected to deliver a Map-Request
message to their intended destination ETR as identified by the EID,
and (2) no on-path attack can be mounted within the LISP Mapping
System. How the Mapping System is protected from on-path attacks
depends from the particular Mapping System used, and is out of the
scope of this memo. Furthermore, while LISP-SEC enables detection of
Maino, et al. Expires January 8, 2023 [Page 4]
Internet-Draft LISP-SEC July 2022
EID prefix overclaiming attacks, it assumes that Map-Servers can
verify the EID prefix authorization at registration time.
According to the threat model described in [RFC7835] LISP-SEC assumes
that any kind of attack, including on-path attacks, can be mounted
outside of the boundaries of the LISP mapping system. An on-path
attacker, outside of the LISP mapping system can, for example, hijack
Map-Request and Map-Reply messages, spoofing the identity of a LISP
node. Another example of on-path attack, called overclaiming attack,
can be mounted by a malicious Egress Tunnel Router (ETR), by
overclaiming the EID-prefixes for which it is authoritative. In this
way the ETR can maliciously redirect traffic.
5. Protocol Operations
The goal of the security mechanisms defined in
[I-D.ietf-lisp-rfc6833bis] is to prevent unauthorized insertion of
mapping data by providing origin authentication and integrity
protection for the Map-Register, and by using the nonce to detect
unsolicited Map-Reply sent by off-path attackers.
LISP-SEC builds on top of the security mechanisms defined in to
address the threats described in Section 4 by leveraging the trust
relationships existing among the LISP entities
([I-D.ietf-lisp-rfc6833bis]) participating in the exchange of the
Map-Request/Map-Reply messages. Those trust relationships (see also
Section 7 and [I-D.ietf-lisp-rfc6833bis]) are used to securely
distribute, as described in Section 8.4, a per-message One-Time Key
(OTK) that provides origin authentication, integrity and anti-replay
protection to mapping data conveyed via the mapping lookup process,
and that effectively prevent overclaiming attacks. The processing of
security parameters during the Map-Request/Map-Reply exchange is as
follows:
o Per each Map-Request message a new ITR-OTK is generated and stored
at the ITR, and securely transported to the Map-Server.
o The Map-Server uses the ITR-OTK to compute a Keyed-Hashing for
Message Authentication (HMAC) [RFC2104] that protects the
integrity of the mapping data known to the Map-Server to prevent
overclaiming attacks. The Map-Server also derives a new OTK, the
MS-OTK, that is passed to the ETR, by applying a Key Derivation
Function (KDF) (e.g. [RFC5869]) to the ITR-OTK.
o The ETR uses the MS-OTK to compute an HMAC that protects the
integrity of the Map-Reply sent to the ITR.
Maino, et al. Expires January 8, 2023 [Page 5]
Internet-Draft LISP-SEC July 2022
o Finally, the ITR uses the stored ITR-OTK to verify the integrity
of the mapping data provided by both the Map-Server and the ETR,
and to verify that no overclaiming attacks were mounted along the
path between the Map-Server and the ITR.
Section 6 provides the detailed description of the LISP-SEC control
messages and their processing, while the rest of this section
describes the flow of LISP protocol operations at each entity
involved in the Map-Request/Map-Reply exchange:
1. The ITR, upon needing to transmit a Map-Request message,
generates and stores an OTK (ITR-OTK). This ITR-OTK is encrypted
and included into the Encapsulated Control Message (ECM) that
contains the Map-Request sent to the Map-Resolver.
2. The Map-Resolver decapsulates the ECM message, decrypts the ITR-
OTK, if needed, and forwards through the Mapping System the
received Map-Request and the ITR-OTK, as part of a new ECM
message. The LISP Mapping System delivers the ECM to the
appropriate Map-Server, as identified by the EID destination
address of the Map-Request.
3. The Map-Server is configured with the location mappings and
policy information for the ETR responsible for the EID
destination address. Using this preconfigured information, the
Map-Server, after the decapsulation of the ECM message, finds the
longest match EID-prefix that covers the requested EID in the
received Map-Request. The Map-Server adds this EID-prefix,
together with an HMAC computed using the ITR-OTK, to a new
Encapsulated Control Message that contains the received Map-
Request.
4. The Map-Server derives a new OTK, the MS-OTK, by applying a Key
Derivation Function (KDF) to the ITR-OTK. This MS-OTK is
included in the Encapsulated Control Message that the Map-Server
uses to forward the Map-Request to the ETR.
5. If the Map-Server is acting in proxy mode, as specified in
[I-D.ietf-lisp-rfc6833bis], the ETR is not involved in the
generation of the Map-Reply and steps 6 and 7 are skipped. In
this case the Map-Server generates the Map-Reply on behalf of the
ETR as described in Section 6.7.2.
6. The ETR, upon receiving the ECM encapsulated Map-Request from the
Map-Server, decrypts the MS-OTK, if needed, and originates a Map-
Reply that contains the EID-to-RLOC mapping information as
specified in [I-D.ietf-lisp-rfc6833bis].
Maino, et al. Expires January 8, 2023 [Page 6]
Internet-Draft LISP-SEC July 2022
7. The ETR computes an HMAC over the Map-Reply, keyed with MS-OTK to
protect the integrity of the whole Map-Reply. The ETR also
copies the EID-prefix authorization data that the Map-Server
included in the ECM encapsulated Map-Request into the Map-Reply
message. The ETR then sends the complete Map-Reply message to
the requesting ITR.
8. The ITR, upon receiving the Map-Reply, uses the locally stored
ITR-OTK to verify the integrity of the EID-prefix authorization
data included in the Map-Reply by the Map-Server. The ITR
computes the MS-OTK by applying the same KDF (as specified in the
ECM encapsulated Map-Reply) used by the Map-Server, and verifies
the integrity of the Map-Reply.
6. LISP-SEC Control Messages Details
LISP-SEC metadata associated with a Map-Request is transported within
the Encapsulated Control Message that contains the Map-Request.
LISP-SEC metadata associated with the Map-Reply is transported within
the Map-Reply itself.
These specifications use Keyed-Hashing for Message Authentication
(HMAC) in various places (as described in the following). The HMAC
function AUTH-HMAC-SHA-256-128 [RFC6234] MUST be supported in LISP-
SEC implementations. LISP-SEC deployments SHOULD use AUTH-HMAC-SHA-
256-128 HMAC function, except when communicating with older
implementations that only support AUTH-HMAC-SHA-1-96 [RFC2104].
6.1. Encapsulated Control Message LISP-SEC Extensions
LISP-SEC uses the ECM defined in [I-D.ietf-lisp-rfc6833bis] with S
bit set to 1 to indicate that the LISP header includes Authentication
Data (AD). The format of the LISP-SEC ECM Authentication Data is
defined in Figure 1 . OTK-AD stands for One-Time Key Authentication
Data and EID-AD stands for EID Authentication Data.
Maino, et al. Expires January 8, 2023 [Page 7]
Internet-Draft LISP-SEC July 2022
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ECM AD Type | Unassigned | Requested HMAC ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+\
| OTK Length | Key ID | OTK Wrap. ID | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| One-Time-Key Preamble ... | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+OTK-AD
| ... One-Time-Key Preamble | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
~ One-Time Key (128 bits) ~/
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ <---+
| EID-AD Length | KDF ID | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Record Count |E| Unassigned | EID HMAC ID |EID-AD
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+\ |
| Unassigned | EID mask-len | EID-AFI | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Rec |
~ EID-prefix ... ~ | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+/ |
~ EID HMAC ~ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ <---+
Figure 1: LISP-SEC ECM Authentication Data
ECM AD Type: 1 (LISP-SEC Authentication Data). See Section 8.
Unassigned: Set to 0 on transmission and ignored on receipt.
Requested HMAC ID: The HMAC algorithm, that will be used to
protect the mappings, requested by the ITR. Permitted values are
registered in the LISP-SEC Authentication Data HMAC ID (see
Section 8.3). Refer to Section 6.4 for more details.
OTK Length: The length (in bytes) of the OTK Authentication Data
(OTK-AD), that contains the OTK Preamble and the OTK.
Key ID: The identifier of the pre-shared secret shared by an ITR
and the Map-Resolver, and by the Map-Server and an ETR. Per-
message keys are derived from the pre-shared secret to encrypt,
authenticate the origin and protect the integrity of the OTK. The
Key ID allows to rotate between multiple pre-shared secrets in a
non disruptive way.
OTK Wrapping ID (OTK Wrap. ID): The identifier of the key
derivation function and of the key wrapping algorithm used to
encrypt the One-Time-Key. Permitted values are registered in the
Maino, et al. Expires January 8, 2023 [Page 8]
Internet-Draft LISP-SEC July 2022
LISP-SEC Authentication Data Key Wrap ID (see Section 8.4). Refer
to Section 6.5 for more details.
One-Time-Key Preamble: set to 0 if the OTK is not encrypted. When
the OTK is encrypted, this field MAY carry additional metadata
resulting from the key wrapping operation. When a 128-bit OTK is
sent unencrypted by a Map-Resolver, the OTK Preamble is set to
0x0000000000000000 (64 bits). See Section 6.5.1 for details.
One-Time-Key: the OTK wrapped as specified by OTK Wrapping ID.
See Section 6.5 for details.
EID-AD Length: length (in bytes) of the EID Authentication Data
(EID-AD). The ITR MUST set the EID-AD Length to 4 bytes, as it
only fills the KDF ID field, and all the remaining fields part of
the EID-AD are not present. An EID-AD MAY contain multiple EID-
records. Each EID-record is 4-byte long plus the length of the
AFI-encoded EID-prefix.
KDF ID: Identifier of the Key Derivation Function used to derive
the MS-OTK. Permitted values are registered in the LISP-SEC
Authentication Data Key Derivation Function ID (see Section 8.5).
Refer to Section 6.7 for more details.
Record Count: As defined in Section 5.2 of
[I-D.ietf-lisp-rfc6833bis].
E: ETR-Cant-Sign bit. If this bit is set to 1, it signals to the
ITR that at least one of the ETRs authoritative for the EID
prefixes of this Map-Reply has not enabled LISP-SEC. Only a Map-
Server can set this bit. See Section 6.7 for more details.
Unassigned: Set to 0 on transmission and ignored on receipt.
EID HMAC ID: Identifier of the HMAC algorithm used to protect the
integrity of the EID-AD. This field is filled by the Map-Server
that computed the EID-prefix HMAC. See Section 6.7.1 for more
details.
EID mask-len: As defined in Section 5.2 of
[I-D.ietf-lisp-rfc6833bis].
EID-AFI: As defined in Section 5.2 of [I-D.ietf-lisp-rfc6833bis].
EID-prefix: As defined in Section 5.2 of
[I-D.ietf-lisp-rfc6833bis].
Maino, et al. Expires January 8, 2023 [Page 9]
Internet-Draft LISP-SEC July 2022
EID HMAC: HMAC of the EID-AD computed and inserted by a Map-Server
See Section 6.7.1 for more details.
6.2. Map-Reply LISP-SEC Extensions
LISP-SEC uses the Map-Reply defined in [I-D.ietf-lisp-rfc6833bis],
with Type set to 2, and S-bit set to 1 to indicate that the Map-Reply
message includes Authentication Data (AD). The format of the LISP-
SEC Map-Reply Authentication Data is defined in Figure 2. PKT-AD is
the Packet Authentication Data that covers the Map-Reply payload.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MR AD Type | Unassigned |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ <---+
| EID-AD Length | KDF ID | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Record Count | Unassigned | EID HMAC ID |EID-AD
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+\ |
| Unassigned | EID mask-len | EID-AFI | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Rec |
~ EID-prefix ... ~ | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+/ |
~ EID HMAC ~ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ <---+
| PKT-AD Length | PKT HMAC ID |\
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
~ PKT HMAC ~PKT-AD
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+/
Figure 2: LISP-SEC Map-Reply Authentication Data
MR AD Type: 1 (LISP-SEC Authentication Data). See Section 8.
EID-AD Length: length (in bytes) of the EID-AD (see Section 6.1).
KDF ID: Identifier of the Key Derivation Function used to derive
MS-OTK (see Section 6.1).
Record Count: The number of records in this Map-Reply message (see
Section 6.1).
Unassigned: Set to 0 on transmission and ignored on receipt.
EID HMAC ID: Identifier of the HMAC algorithm used to protect the
integrity of the EID-AD (see Section 6.1).
Maino, et al. Expires January 8, 2023 [Page 10]
Internet-Draft LISP-SEC July 2022
EID mask-len: Mask length for EID-prefix (see Section 6.1).
EID-AFI: See Section 6.1. .
EID-prefix: See Section 6.1.
EID HMAC: See Section 6.1.
PKT-AD Length: length (in bytes) of the Packet Authentication Data
(PKT-AD).
PKT HMAC ID: Identifier of the HMAC algorithm used to protect the
integrity of the Map-Reply (see Section 6.5).
PKT HMAC: HMAC of the whole Map-Reply packet, so to protect its
integrity; including the LISP-SEC Authentication Data (from the
Map-Reply Type field to the PKT HMAC field), which allow message
authetification.
6.3. Map-Register LISP-SEC Extensions
The S bit in the Map-Register message (see
[I-D.ietf-lisp-rfc6833bis]) indicates to the Map-Server that the
registering ETR is LISP-SEC enabled. An ETR that supports LISP-SEC
MUST set the S bit in its Map-Register messages.
6.4. ITR Processing: Generating a Map-Request
Upon creating a Map-Request, the ITR generates a random ITR-OTK that
is stored locally, until the corresponding Map-Reply is received (see
Section 6.9), together with the nonce generated as specified in
[I-D.ietf-lisp-rfc6833bis].
The ITR MAY use the KDF ID field to indicate the recommended KDF
algorithm, according to local policy. The Map-Server can overwrite
the KDF ID if it does not support the KDF ID recommended by the ITR
(see Section 6.7). A KDF value of NOPREF (0) may be used to specify
that the ITR has no preferred KDF ID.
ITR-OTK confidentiality and integrity protection MUST be provided in
the path between the ITR and the Map-Resolver. This can be achieved
either by encrypting the ITR-OTK with the pre-shared secret known to
the ITR and the Map-Resolver (see Section 6.5), or by enabling DTLS
[RFC9147] between the ITR and the Map-Resolver.
The Map-Request (as defined in [I-D.ietf-lisp-rfc6833bis]) MUST be
encapsulated as a LISP Control Message in an ECM, with the S-bit set
Maino, et al. Expires January 8, 2023 [Page 11]
Internet-Draft LISP-SEC July 2022
to 1, to indicate the presence of Authentication Data. Such a
message is also called "Protected Map-Request" in this memo.
The ITR-OTK is wrapped with the algorithm specified by the OTK
Wrapping ID field. See Section 6.5 for further details on OTK
encryption. If the NULL-KEY-WRAP-128 algorithm (see Section 8.4) is
selected, and no other encryption mechanism (e.g. DTLS) is enabled
in the path between the ITR and the Map-Resolver, the Map-Request
MUST be dropped, and an appropriate log action SHOULD be taken.
Implementations may include mechanisms (which are beyond the scope of
this document) to avoid log resource exhaustion attacks.
The Requested HMAC ID field contains the suggested HMAC algorithm to
be used by the Map-Server and the ETR to protect the integrity of the
ECM Authentication data and of the Map-Reply. A HMAC ID Value of
NONE (0), MAY be used to specify that the ITR has no preferred HMAC
ID.
The KDF ID field specifies the suggested key derivation function to
be used by the Map-Server to derive the MS-OTK. A KDF Value of NONE
(0) may be used to specify that the ITR has no preferred KDF ID.
The EID-AD length is set to 4 bytes, since the Authentication Data
does not contain EID-prefix Authentication Data, and the EID-AD
contains only the KDF ID field.
If the ITR is directly connected to a Mapping System, such as
LISP+ALT [RFC6836], it performs the functions of both the ITR and the
Map-Resolver, forwarding the Protected Map-Request as described in
Section 6.6.
The processing performed by Proxy ITRs (PITRs) is equivalent to the
processing of an ITR, hence the procedure described above applies.
6.5. Encrypting and Decrypting an OTK
MS-OTK confidentiality and integrity protection MUST be provided in
the path between the Map-Server and the ETR. This can be achieved
either by enabling DTLS between the Map-Server and the ETR or by
encrypting the MS-OTK with the pre-shared secret known to the Map-
Server and the ETR [I-D.ietf-lisp-rfc6833bis].
Similarly, ITR-OTK confidentiality and integrity protection MUST be
provided in the path between the ITR and the Map-Resolver. This can
be achieved either by enabling DTLS between the Map-Server and the
ITR, or by encrypting the ITR-OTK with the pre-shared secret known to
the ITR and the Map-Resolver. The ITR/Map-Resolver pre-shared key is
similar to the Map-Server/ETR pre-shared key.
Maino, et al. Expires January 8, 2023 [Page 12]
Internet-Draft LISP-SEC July 2022
This section describes OTK processing in the ITR/Map-Resolver path,
as well as in the Map-Server/ETR path.
It's important to note that, to prevent ETR's overclaiming attacks,
the ITR/Map-Resolver pre-shared secret MUST be independent from the
Map-Server/ETR pre-shared secret.
The OTK is wrapped using the algorithm specified in the OTK Wrapping
ID field. This field identifies both the:
o Key Encryption Algorithm used to encrypt the wrapped OTK.
o Key Derivation Function used to derive a per-message encryption
key.
Implementations of this specification MUST support OTK Wrapping ID
AES-KEY-WRAP-128+HKDF-SHA256 that specifies the use of the HKDF-
SHA256 Key Derivation Function specified in [RFC5869] to derive a
per-message encryption key (per-msg-key), as well as the AES-KEY-
WRAP-128 Key Wrap algorithm used to encrypt a 128-bit OTK, according
to [RFC3394].
Implementations of this specification MUST support OTK Wrapping NULL-
KEY-WRAP-128. NULL-KEY-WRAP-128 is used to carry an unencrypted
128-bit OTK, with a 64-bit preamble set to 0x0000000000000000 (64
bits).
The key wrapping process for OTK Wrapping ID AES-KEY-WRAP-128+HKDF-
SHA256 is described below:
1. The KDF and Key Wrap algorithms are identified by the value of
the 'OTK Wrapping ID' field. The initial values are documented
in Table 5.
2. If the NULL-KEY-WRAP-128 algorithm (see Section 8.4) is selected
and DTLS is not enabled, the Map-Request MUST be dropped and an
appropriate log action SHOULD be taken. Implementations may
include mechanisms (which are beyond the scope of this document)
to avoid log resource exhaustion attacks.
3. The pre-shared secret used to derive the per-msg-key is
represented by PSK[Key ID], that is the pre-shared secret
identified by the 'Key ID'.
4. The 128-bits long per-message encryption key is computed as:
* per-msg-key = KDF( nonce + s + PSK[Key ID] )
Maino, et al. Expires January 8, 2023 [Page 13]
Internet-Draft LISP-SEC July 2022
where the nonce is the value in the Nonce field of the Map-
Request, 's' is the string "OTK-Key-Wrap", and the operation'+'
just indicates string concatenation.
5. According to [RFC3394] the per-msg-key is used to wrap the OTK
with AES-KEY-WRAP-128. The AES Key Wrap Initialization Value
MUST be set to 0xA6A6A6A6A6A6A6A6 (64 bits). The output of the
AES Key Wrap operation is 192-bit long. The most significant
64-bit are copied in the One-Time Key Preamble field, while the
128 less significant bits are copied in the One-Time Key field of
the LISP-SEC Authentication Data.
When decrypting an encrypted OTK the receiver MUST verify that the
Initialization Value resulting from the AES Key Wrap decryption
operation is equal to 0xA6A6A6A6A6A6A6A6. If this verification fails
the receiver MUST discard the entire message.
6.5.1. Unencrypted OTK
However, when DTLS is enabled the OTK MAY be sent unencrypted as
transport layer security is providing confidentiality and integrity
protection.
When a 128-bit OTK is sent unencrypted the OTK Wrapping ID is set to
NULL_KEY_WRAP_128, and the OTK Preamble is set to 0x0000000000000000
(64 bits).
6.6. Map-Resolver Processing
Upon receiving a Protected Map-Request, the Map-Resolver decapsulates
the ECM message. The ITR-OTK, if encrypted, is decrypted as
specified in Section 6.5.
Protecting the confidentiality of the ITR-OTK and, in general, the
security of how the Map-Request is handed by the Map-Resolver to the
Map-Server, is specific to the particular Mapping System used, and
outside of the scope of this memo.
In Mapping Systems where the Map-Server is compliant with
[I-D.ietf-lisp-rfc6833bis], the Map-Resolver originates a new ECM
header with the S-bit set, that contains the unencrypted ITR-OTK, as
specified in Section 6.5, and the other data derived from the ECM
Authentication Data of the received encapsulated Map-Request.
The Map-Resolver then forwards to the Map-Server the received Map-
Request, encapsulated in the new ECM header that includes the newly
computed Authentication Data fields.
Maino, et al. Expires January 8, 2023 [Page 14]
Internet-Draft LISP-SEC July 2022
6.7. Map-Server Processing
Upon receiving a Protected Map-Request, the Map-Server processes it
according to the setting of the S-bit and the P-bit in the Map-
Register received from the ETRs authoritative for that prefix, as
described below.
While processing the Map-Request, the Map-Server can overwrite the
KDF ID field if it does not support the KDF ID recommended by the
ITR. Processing of the Map-Request MUST proceed in the order
described in the table below, applying the processing corresponding
to the first rule that matches the conditions indicated in the first
column:
Maino, et al. Expires January 8, 2023 [Page 15]
Internet-Draft LISP-SEC July 2022
+---------------------+---------------------------------------------+
| Matching Condition | Processing |
+---------------------+---------------------------------------------+
| 1. At least one of | The Map-Server MUST generate a LISP-SEC |
| the ETRs | protected Map-Reply as specified in |
| authoritative for | Section 6.7.2. The ETR-Cant-Sign E-bit in |
| the EID prefix | the EID Authentication Data (EID-AD) MUST |
| included in the | be set to 0. |
| Map-Request | |
| registered with the | |
| P-bit set to 1 | |
| | |
| 2. At least one of | The Map-Server MUST generate a LISP-SEC |
| the ETRs | protected Encapsulated Map-Request (as |
| authoritative for | specified in Section 6.7.1), to be sent to |
| the EID prefix | one of the authoritative ETRs that |
| included in the | registered with the S-bit set to 1 (and the |
| Map-Request | P-bit set to 0). If there is at least one |
| registered with the | ETR that registered with the S-bit set to |
| S-bit set to 1 | 0, the ETR-Cant-Sign E-bit of the EID-AD |
| | MUST be set to 1 to signal the ITR that a |
| | non LISP-SEC Map-Request might reach |
| | additional ETRs that have LISP-SEC |
| | disabled. |
| | |
| 3. All the ETRs | The Map-Server MUST send a Negative Map- |
| authoritative for | Reply protected with LISP-SEC, as described |
| the EID prefix | in Section 6.7.2. The ETR-Cant-Sign E-bit |
| included in the | MUST be set to 1 to signal the ITR that a |
| Map-Request | non LISP-SEC Map-Request might reach |
| registered with the | additional ETRs that have LISP-SEC |
| S-bit set to 0 | disabled. |
+---------------------+---------------------------------------------+
Table 1: Map-Request Processing.
In this way the ITR that sent a LISP-SEC protected Map-Request always
receives a LISP-SEC protected Map-Reply. However, the ETR-Cant-Sign
E-bit set to 1 specifies that a non LISP-SEC Map-Request might reach
additional ETRs that have LISP-SEC disabled. This mechanism allows
the ITR to downgrade to non LISP-SEC requests, which does not protect
against threats described in Section 4.
6.7.1. Generating a LISP-SEC Protected Encapsulated Map-Request
The Map-Server decapsulates the ECM and generates a new ECM
Authentication Data. The Authentication Data includes the OTK-AD and
Maino, et al. Expires January 8, 2023 [Page 16]
Internet-Draft LISP-SEC July 2022
the EID-AD, that contains EID-prefix authorization information, that
are eventually received by the requesting ITR.
The Map-Server updates the OTK-AD by deriving a new OTK (MS-OTK) from
the ITR-OTK received with the Map-Request. MS-OTK is derived
applying the key derivation function specified in the KDF ID field.
If the algorithm specified in the KDF ID field is not supported, the
Map-Server uses a different algorithm to derive the key and updates
the KDF ID field accordingly.
The Map-Request MUST be encapsulated in an ECM, with the S-bit set to
1, to indicate the presence of Authentication Data.
MS-OTK is wrapped with the algorithm specified by the OTK Wrapping ID
field. See Section 6.5 for further details on OTK encryption. If
the NULL-KEY-WRAP-128 algorithm is selected and DTLS is not enabled
in the path between the Map-Server and the ETR, the Map-Request MUST
be dropped and an appropriate log action SHOULD be taken.
The Map-Server includes in the EID-AD the longest match registered
EID-prefix for the destination EID, and an HMAC of this EID-prefix.
The HMAC is keyed with the ITR-OTK contained in the received ECM
Authentication Data, and the HMAC algorithm is chosen according to
the Requested HMAC ID field. If the Map-Server does not support this
algorithm, the Map-Server uses a different algorithm and specifies it
in the EID HMAC ID field. The scope of the HMAC operation MUST cover
the entire EID-AD, from the EID-AD Length field to the EID HMAC
field, which MUST be set to 0 before the computation.
The Map-Server then forwards the updated ECM encapsulated Map-
Request, that contains the OTK-AD, the EID-AD, and the received Map-
Request to an authoritative ETR as specified in
[I-D.ietf-lisp-rfc6833bis].
6.7.2. Generating a Proxy Map-Reply
LISP-SEC proxy Map-Reply are generated according to
[I-D.ietf-lisp-rfc6833bis], with the Map-Reply S-bit set to 1. The
Map-Reply includes the Authentication Data that contains the EID-AD,
computed as specified in Section 6.7.1, as well as the PKT-AD
computed as specified in Section 6.8.
6.8. ETR Processing
Upon receiving an ECM encapsulated Map-Request with the S-bit set,
the ETR decapsulates the ECM message. The OTK field, if encrypted,
is decrypted as specified in Section 6.5 to obtain the unencrypted
MS-OTK.
Maino, et al. Expires January 8, 2023 [Page 17]
Internet-Draft LISP-SEC July 2022
The ETR then generates a Map-Reply as specified in
[I-D.ietf-lisp-rfc6833bis] and includes the Authentication Data that
contains the EID-AD, as received in the encapsulated Map-Request, as
well as the PKT-AD.
The EID-AD is copied from the Authentication Data of the received
encapsulated Map-Request.
The PKT-AD contains the HMAC of the whole Map-Reply packet, keyed
with the MS-OTK and computed using the HMAC algorithm specified in
the Requested HMAC ID field of the received encapsulated Map-Request.
If the ETR does not support the Requested HMAC ID, it uses a
different algorithm and updates the PKT HMAC ID field accordingly.
The HMAC operation MUST cover the entire Map-Reply, where the PKT
HMAC field MUST be set to 0 before the computation.
Finally the ETR sends the Map-Reply to the requesting ITR as
specified in [I-D.ietf-lisp-rfc6833bis].
6.9. ITR Processing: Receiving a Map-Reply
In response to a Protected Map-Request, an ITR expects a Map-Reply
with the S-bit set to 1 including an EID-AD and a PKT-AD. The ITR
MUST discard the Map-Reply otherwise.
Upon receiving a Map-Reply, the ITR must verify the integrity of both
the EID-AD and the PKT-AD, and MUST discard the Map-Reply if one of
the integrity checks fails. After processing the Map-Reply, the ITR
MUST discard the <nonce,ITR-OTK> pair associated to the Map-Reply
The integrity of the EID-AD is verified using the ITR-OTK (stored
locally for the duration of this exchange) to re-compute the HMAC of
the EID-AD using the algorithm specified in the EID HMAC ID field.
If the ITR did indicate a Requested HMAC ID in the Map-Request and
the PKT HAMC ID in the corresponding Map-Reply is different, or if
the ITR did not indicate a Requested HMAC ID in the Map-Request and
the PKT HMAC ID in the corresponding Map-Reply is not supported, then
the ITR MUST discard the Map-Reply and send, according to rate
limitation policies defined in [I-D.ietf-lisp-rfc6833bis], a new Map-
Request with a different Requested HMAC ID field, according to ITR's
local policy. The scope of the HMAC operation covers the entire EID-
AD, from the EID-AD Length field to the EID HMAC field.
ITR MUST set the EID HMAC ID field to 0 before computing the HMAC.
To verify the integrity of the PKT-AD, first the MS-OTK is derived
from the locally stored ITR-OTK using the algorithm specified in the
KDF ID field. This is because the PKT-AD is generated by the ETR
Maino, et al. Expires January 8, 2023 [Page 18]
Internet-Draft LISP-SEC July 2022
using the MS-OTK. If the ITR did indicate a recommended KDF ID in
the Map-Request and the KDF ID in the corresponding Map-Reply is
different, or if the ITR did not indicate a recommended KDF ID in the
Map-Request and the KDF ID in the corresponding Map-Reply is not
supported, then the ITR MUST discard the Map-Reply and send,
according to rate limitation policies defined in
[I-D.ietf-lisp-rfc6833bis], a new Map-Request with a different KDF
ID, according to ITR's local policy. The key derivation function
HKDF-SHA256 MUST be supported in LISP-SEC implementations. LISP-SEC
deployments SHOULD use the HKDF-SHA256 HKDF function, unless older
implementations using HKDF-SHA1-128 are present in the same
deployment. Without consistent configuration of involved entities,
extra delays may be experienced. However, since HKDF-SHA1-128 and
HKDF-SHA256 are supported, the process will eventually converge.
The derived MS-OTK is then used to re-compute the HMAC of the PKT-AD
using the Algorithm specified in the PKT HMAC ID field. If the PKT
HMAC ID field does not match the Requested HMAC ID the ITR MUST
discard the Map-Reply and send, according to rate limitation policies
defined in [I-D.ietf-lisp-rfc6833bis], a new Map-Request with a
different Requested HMAC ID according to ITR's local policy or until
all HMAC IDs supported by the ITR have been attempted. When the PKT
HMAC ID field does not match the Requested HMAC ID it is not possible
to validate the Map-Reply.
Each individual Map-Reply EID-record is considered valid only if: (1)
both EID-AD and PKT-AD are valid, and (2) the intersection of the
EID-prefix in the Map-Reply EID-record with one of the EID-prefixes
contained in the EID-AD is not empty. After identifying the Map-
Reply record as valid, the ITR sets the EID-prefix in the Map-Reply
record to the value of the intersection set computed before, and adds
the Map-Reply EID-record to its EID-to-RLOC cache, as described in
[I-D.ietf-lisp-rfc6833bis]. An example of Map-Reply record
validation is provided in Section 6.9.1.
[I-D.ietf-lisp-rfc6833bis] allows ETRs to send Solicit-Map-Requests
(SMR) directly to the ITR. The corresponding SMR-invoked Map-Request
will be sent through the mapping system, hence, secured with the
specifications of this memo if in use. If an ITR accepts Map-Replies
piggybacked in Map-Requests and its content is not already present in
its EID-to-RLOC cache, it MUST send a Map-Request over the mapping
system in order to verify its content with a secured Map-Reply,
before using the content.
Maino, et al. Expires January 8, 2023 [Page 19]
Internet-Draft LISP-SEC July 2022
6.9.1. Map-Reply Record Validation
The payload of a Map-Reply may contain multiple EID-records. The
whole Map-Reply is signed by the ETR, with the PKT HMAC, to provide
integrity protection and origin authentication to the EID-prefix
records claimed by the ETR. The Authentication Data field of a Map-
Reply may contain multiple EID-records in the EID-AD. The EID-AD is
signed by the Map-Server, with the EID HMAC, to provide integrity
protection and origin authentication to the EID-prefix records
inserted by the Map-Server.
Upon receiving a Map-Reply with the S-bit set, the ITR first checks
the validity of both the EID HMAC and of the PKT-AD HMAC. If either
one of the HMACs is not valid, a log action SHOULD be taken and the
Map-Reply MUST NOT be processed any further. Implementations may
include mechanisms (which are beyond the scope of this document) to
avoid log resource exhaustion attacks. If both HMACs are valid, the
ITR proceeds with validating each individual EID-record claimed by
the ETR by computing the intersection of each one of the EID-prefix
contained in the payload of the Map-Reply with each one of the EID-
prefixes contained in the EID-AD. An EID-record is valid only if at
least one of the intersections is not the empty set, otherwise, a log
action MUST be taken and the EID-record MUST be discarded.
Implementations may include mechanisms (which are beyond the scope of
this document) to avoid log resource exhaustion attacks.
For instance, the Map-Reply payload contains 3 mapping record EID-
prefixes:
2001:db8:102::/48
2001:db8:103::/48
2001:db8:200::/40
The EID-AD contains two EID-prefixes:
2001:db8:103::/48
2001:db8:203::/48
The EID-record with EID-prefix 2001:db8:102::/48 is not eligible to
be used by the ITR since it is not included in any of the EID-ADs
signed by the Map-Server. A log action MUST be taken and the EID-
record MUST be discarded. Implementations may include mechanisms
(which are beyond the scope of this document) to avoid log resource
exhaustion attacks.
Maino, et al. Expires January 8, 2023 [Page 20]
Internet-Draft LISP-SEC July 2022
The EID-record with EID-prefix 2001:db8:103::/48 is eligible to be
used by the ITR because it matches the second EID-prefix contained in
the EID-AD.
The EID-record with EID-prefix 2001:db8:200::/40 is not eligible to
be used by the ITR since it is not included in any of the EID-ADs
signed by the Map-Server. A log action MUST be taken and the EID-
record MUST be discarded. Implementations may include mechanisms
(which are beyond the scope of this document) to avoid log resource
exhaustion attacks. In this last example the ETR is trying to over
claim the EID-prefix 2001:db8:200::/40, but the Map-Server authorized
only 2001:db8:203::/48, hence the EID-record is discarded.
7. Security Considerations
This document extends the LISP Control-Plane defined in
[I-D.ietf-lisp-rfc6833bis], hence, its Security Considerations apply
as well to this document.
7.1. Mapping System Security
The LISP-SEC threat model described in Section 4, assumes that the
LISP Mapping System is working properly and delivers Map-Request
messages to a Map-Server that is authoritative for the requested EID.
It is assumed that the Mapping System ensures the confidentiality of
the OTK, and the integrity of the Map-Reply data. However, how the
LISP Mapping System is secured is out of the scope of this document.
Similarly, Map-Register security, including the right for a LISP
entity to register an EID-prefix or to claim presence at an RLOC, is
out of the scope of LISP-SEC.
7.2. Random Number Generation
The ITR-OTK MUST be generated by a properly seeded pseudo-random (or
strong random) source. See [RFC4086] for advice on generating
security-sensitive random data.
7.3. Map-Server and ETR Colocation
If the Map-Server and the ETR are colocated, LISP-SEC does not
provide protection from overclaiming attacks mounted by the ETR.
However, in this particular case, since the ETR is within the trust
boundaries of the Map-Server, ETR's overclaiming attacks are not
included in the threat model.
Maino, et al. Expires January 8, 2023 [Page 21]
Internet-Draft LISP-SEC July 2022
7.4. Deploying LISP-SEC
Those deploying LISP-SEC according to this memo, should carefully
weight how the LISP-SEC threat model applies to their particular use
case or deployment. If they decide to ignore a particular
recommendation, they should make sure the risk associated with the
corresponding threats is well understood.
As an example, in certain other deployments, attackers may be very
sophisticated, and force the deployers to enforce very strict
policies in term of HMAC algorithms accepted by an ITR.
Similar considerations apply to the entire LISP-SEC threat model, and
should guide the deployers and implementors whenever they encounter
the key word SHOULD across this memo.
7.5. Shared Keys Provisioning
Provisioning of the keys shared between ITR and Map-Resolver paris as
well as between ETR and Map-Server pairs should be performed via an
orchestration infrastructure and it is out of the scope of this memo.
It is recommended that both shared keys are refreshed at periodical
intervals to address key aging or attackers gaining unauthorized
access to the shared keys. Shared keys should be unpredictable
random values.
7.6. Replay Attacks
An attacker can capture a valid Map-Request and/or Map-Reply and
replay it, however once the ITR receives the original Map-Reply the
<nonce,ITR-OTK> pair stored at the ITR will be discarded. If a
replayed Map-Reply arrives at the ITR, there is no <nonce,ITR-OTK>
that matches the incoming Map-Reply and will be discarded.
In case of replayed Map-Request, the Map-Server, Map-Resolver and ETR
will have to do a LISP-SEC computation. This is equivalent, in terms
of resources, to a valid LISP-SEC computation and, beyond a risk of
DoS attack, an attacker does not obtain any additional effect, since
the corresponding Map-Reply is discarded as previously explained.
7.7. Message Privacy
DTLS [RFC9147] SHOULD be used (conforming to [RFC7525]) to provide
communication privacy and to prevent eavesdropping, tampering, or
message forgery to the messages exchanged between the ITR, Map-
Resolver, Map-Server, and ETR, unless the OTK is encrypted in another
way, e.g. using a pre-shared secret. DTLS has the responder be
Maino, et al. Expires January 8, 2023 [Page 22]
Internet-Draft LISP-SEC July 2022
verified by the initiator, which enables an ITR to autheticate the
Map-Resolver, and the Map-Server to authenticate the responding ETR.
7.8. Denial of Service and Distributed Denial of Service Attacks
LISP-SEC mitigates the risks of Denial of Service and Distributed
Denial of Service attacks by protecting the integrity and
authenticating the origin of the Map-Request/Map-Reply messages, and
by preventing malicious ETRs from overclaiming EID prefixes that
could re-direct traffic directed to a potentially large number of
hosts.
8. IANA Considerations
IANA is requested to create the sub-registries listed in the
following sections in the "Locator/ID Separation Protocol (LISP)
Parameters" registry.
For all of the sub-registries, new values beyond this document have
to be assigned according to the "Specification Required" policy
defined in [RFC8126]. Expert review should assess the security
properties of newly added functions, so that encryption robustness is
remains strong. For instance, at the time of this writing the use of
SHA-256-based functions is considered to provide sufficient
protection. Consultation with security experts may be needed.
8.1. ECM AD Type Registry
IANA is requested to create the "ECM Authentication Data Type"
registry with values 0-255, for use in the ECM LISP-SEC Extensions
Section 6.1. Initial allocation of this registry is shown in
Table 2.
+------------------+--------+------------+
| Name | Number | Defined in |
+------------------+--------+------------+
| Reserved | 0 | This memo |
| LISP-SEC-ECM-EXT | 1 | This memo |
+------------------+--------+------------+
Table 2: ECM Authentication Data Types.
Values 2-255 are unassigned.
Maino, et al. Expires January 8, 2023 [Page 23]
Internet-Draft LISP-SEC July 2022
8.2. Map-Reply AD Type Registry
IANA is requested to create the "Map-Reply Authentication Data Type"
registry with values 0-255, for use in the Map-Reply LISP-SEC
Extensions Section 6.2. Initial allocation of this registry is shown
in Table 3.
+-----------------+--------+------------+
| Name | Number | Defined in |
+-----------------+--------+------------+
| Reserved | 0 | This memo |
| LISP-SEC-MR-EXT | 1 | This memo |
+-----------------+--------+------------+
Table 3: Map-Reply Authentication Data Types.
Values 2-255 are unassigned.
8.3. HMAC Functions
IANA is requested to create the "LISP-SEC Preferred Authentication
Data HMAC ID" registry with values 0-65535 for use as Requested HMAC
ID, EID HMAC ID, and PKT HMAC ID in the LISP-SEC Authentication Data.
Initial allocation of this registry is shown in Table 4.
+-----------------------+--------+------------+
| Name | Number | Defined in |
+-----------------------+--------+------------+
| NOPREF | 0 | This memo |
| AUTH-HMAC-SHA-1-96 | 1 | [RFC2104] |
| AUTH-HMAC-SHA-256-128 | 2 | [RFC6234] |
+-----------------------+--------+------------+
Table 4: LISP-SEC Authentication Data HMAC Functions.
Values 3-65535 are unassigned.
8.4. Key Wrap Functions
IANA is requested to create the "LISP-SEC Authentication Data Key
Wrap ID" registry with values 0-65535 for use as OTK key wrap
algorithms ID in the LISP-SEC Authentication Data. Initial
allocation of this registry is shown in Table 5.
Maino, et al. Expires January 8, 2023 [Page 24]
Internet-Draft LISP-SEC July 2022
+------------------------------+--------+-----------+-----------+
| Name | Number | KEY WRAP | KDF |
+------------------------------+--------+-----------+-----------+
| Reserved | 0 | None | None |
| NULL-KEY-WRAP-128 | 1 | This memo | None |
| AES-KEY-WRAP-128+HKDF-SHA256 | 2 | [RFC3394] | [RFC4868] |
+------------------------------+--------+-----------+-----------+
Table 5: LISP-SEC Authentication Data Key Wrap Functions.
Values 3-65535 are unassigned.
8.5. Key Derivation Functions
IANA is requested to create the "LISP-SEC Authentication Data Key
Derivation Function ID" registry with values 0-65535 for use as KDF
ID. Initial allocation of this registry is shown in Table 6.
+----------------+--------------+------------+
| Name | Number | Defined in |
+----------------+--------------+------------+
| NOPREF | 0 | This memo |
| HKDF-SHA1-128 | 1 | [RFC5869] |
| HKDF-SHA256 | 2 | [RFC5869] |
+----------------+--------------+------------+
Table 6: LISP-SEC Authentication Data Key Derivation Function ID.
Values 2-65535 are unassigned.
9. Acknowledgements
The authors would like to acknowledge Luigi Iannone, Pere Monclus,
Dave Meyer, Dino Farinacci, Brian Weis, David McGrew, Darrel Lewis
and Landon Curt Noll for their valuable suggestions provided during
the preparation of this document.
10. References
10.1. Normative References
[I-D.ietf-lisp-rfc6830bis]
lispers.net, vaf.net Internet Consulting, 1-4-5.net, Cisco
Systems, and UPC/BarcelonaTech, "The Locator/ID Separation
Protocol (LISP)", draft-ietf-lisp-rfc6830bis-38 (work in
progress), May 2022.
Maino, et al. Expires January 8, 2023 [Page 25]
Internet-Draft LISP-SEC July 2022
[I-D.ietf-lisp-rfc6833bis]
lispers.net, Cisco Systems, vaf.net Internet Consulting,
and UPC/BarcelonaTech, "Locator/ID Separation Protocol
(LISP) Control-Plane", draft-ietf-lisp-rfc6833bis-31 (work
in progress), May 2022.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104,
DOI 10.17487/RFC2104, February 1997,
<https://www.rfc-editor.org/info/rfc2104>.
[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/info/rfc2119>.
[RFC3394] Schaad, J. and R. Housley, "Advanced Encryption Standard
(AES) Key Wrap Algorithm", RFC 3394, DOI 10.17487/RFC3394,
September 2002, <https://www.rfc-editor.org/info/rfc3394>.
[RFC4868] Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA-
384, and HMAC-SHA-512 with IPsec", RFC 4868,
DOI 10.17487/RFC4868, May 2007,
<https://www.rfc-editor.org/info/rfc4868>.
[RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand
Key Derivation Function (HKDF)", RFC 5869,
DOI 10.17487/RFC5869, May 2010,
<https://www.rfc-editor.org/info/rfc5869>.
[RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234,
DOI 10.17487/RFC6234, May 2011,
<https://www.rfc-editor.org/info/rfc6234>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <https://www.rfc-editor.org/info/rfc7525>.
[RFC7835] Saucez, D., Iannone, L., and O. Bonaventure, "Locator/ID
Separation Protocol (LISP) Threat Analysis", RFC 7835,
DOI 10.17487/RFC7835, April 2016,
<https://www.rfc-editor.org/info/rfc7835>.
Maino, et al. Expires January 8, 2023 [Page 26]
Internet-Draft LISP-SEC July 2022
[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/info/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/info/rfc8174>.
[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>.
10.2. Informational References
[RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086,
DOI 10.17487/RFC4086, June 2005,
<https://www.rfc-editor.org/info/rfc4086>.
[RFC6836] Fuller, V., Farinacci, D., Meyer, D., and D. Lewis,
"Locator/ID Separation Protocol Alternative Logical
Topology (LISP+ALT)", RFC 6836, DOI 10.17487/RFC6836,
January 2013, <https://www.rfc-editor.org/info/rfc6836>.
Authors' Addresses
Fabio Maino
Cisco Systems
170 Tasman Drive
San Jose, California 95134
USA
Email: fmaino@cisco.com
Vina Ermagan
Google
California
USA
Email: ermagan@gmail.com
Maino, et al. Expires January 8, 2023 [Page 27]
Internet-Draft LISP-SEC July 2022
Albert Cabellos
Universitat Politecnica de Catalunya
c/ Jordi Girona s/n
Barcelona 08034
Spain
Email: acabello@ac.upc.edu
Damien Saucez
Inria
2004 route des Lucioles - BP 93
Sophia Antipolis
France
Email: damien.saucez@inria.fr
Maino, et al. Expires January 8, 2023 [Page 28]
