Network Working Group
Internet Engineering Task Force (IETF) F. Maino
Internet-Draft
Request for Comments: 9303 Cisco Systems
Intended status:
Category: Standards Track V. Ermagan
Expires: January 8, 2023 Google
ISSN: 2070-1721 Google, Inc.
A. Cabellos
Universitat Politecnica de Catalunya
D. Saucez
Inria
July 7,
October 2022
LISP-Security
Locator/ID Separation Protocol Security (LISP-SEC)
draft-ietf-lisp-sec-29
Abstract
This memo specifies LISP-SEC, Locator/ID Separation Protocol Security (LISP-
SEC), a set of security mechanisms that provides origin
authentication, integrity integrity, and anti-replay protection to the LISP's EID-to-RLOC
Endpoint-ID-to-Routing-Locator (EID-to-RLOC) mapping data conveyed
via the mapping lookup process. LISP-SEC also enables verification
of authorization on EID-
prefix EID-Prefix claims in Map-Reply messages.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on January 8, 2023.
https://www.rfc-editor.org/info/rfc9303.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 3
3. Definition Definitions 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 LISP-SEC-Protected Encapsulated Map-
Request . . . . . . . . . . . . . . . . . . . . . . . 16
Map-Request
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 Denial-of-Service and Distributed Denial of Service Denial-of-Service Attacks . . . . . . . . . . . . . . . . . . . . . . . . . 23
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
8.1. ECM AD Type Registry . . . . . . . . . . . . . . . . . . 23
8.2. Map-Reply AD Type Types 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.
9.1. Normative References . . . . . . . . . . . . . . . . . . 25
10.2. Informational
9.2. Informative References . . . . . . . . . . . . . . . . 27
Acknowledgments
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
1. Introduction
The Locator/ID Separation Protocol
[I-D.ietf-lisp-rfc6830bis],[I-D.ietf-lisp-rfc6833bis] (LISP) [RFC9300] [RFC9301] is a network-
layer-based
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,
database and the LISP Mapping System, and they are made available via
the Map-Request/Map-Reply lookup process. If these EID-to-RLOC
mappings, carried through Map-
Reply 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 Denial-of-
Service (DoS) or Distributed Denial of Service Denial-of-Service (DDoS) attacks. Also,
if the Map-Reply message is transported unauthenticated, an
adversarial LISP entity can overclaim an EID-prefix 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 which
includes a detailed description of an "overclaiming" attack.
This memo specifies LISP-SEC, a set of security mechanisms that
provides origin authentication, integrity 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
Prefix claims in Map-Reply messages, ensuring that the sender of a
Map-Reply that provides the location for a given EID-prefix EID-Prefix is
entitled to do so according to the EID prefix 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 EID-Prefix or to claim
presence at an RLOC, is out of the scope of LISP-SEC LISP-SEC, as those
protocols are protected by the security mechanisms specified in
[I-D.ietf-lisp-rfc6833bis].
[RFC9301]. However, LISP-SEC extends the Map-
Register Map-Register message to
allow an ITR Ingress Tunnel Router (ITR) to downgrade to non LISP-SEC Map-
Requests. non-LISP-SEC
Map-Requests. Additional security considerations are described in
Section 6. 7.
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.
3. Definition Definitions 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, header as defined in
[I-D.ietf-lisp-rfc6833bis], [RFC9301],
or in a Map-Reply message to support confidentiality, integrity
protection, and verification of EID-
prefix 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 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) (MR), please consult the LISP specification
[I-D.ietf-lisp-rfc6833bis].
[RFC9301].
4. LISP-SEC Threat Model
LISP-SEC addresses the control plane threats, described in section Sections
3.7 and 3.8 of [RFC7835], that target EID-to-RLOC mappings, including
manipulations of Map-Request and Map-Reply messages, messages and malicious ETR EID prefix
EID-Prefix overclaiming. LISP-SEC makes two main assumptions: (1)
the LISP mapping system 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 on the
particular Mapping System used, used and is out of the scope of this memo.
Furthermore, while LISP-SEC enables detection of
EID prefix EID-Prefix
overclaiming attacks, it assumes that Map-Servers can verify the EID prefix EID-
Prefix authorization at registration time.
According to the threat model described in [RFC7835] [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. Mapping System. An on-path
attacker, on-
path attacker outside of the LISP mapping system Mapping System can, for example,
hijack Map-Request and Map-Reply messages, spoofing the identity of a
LISP node. Another example of an on-path attack, called an
overclaiming attack, can be mounted by a malicious Egress Tunnel Router (ETR), ETR by
overclaiming the EID-prefixes EID-Prefixes for which it is authoritative. In this
way
way, the ETR can maliciously redirect traffic.
5. Protocol Operations
The goal of the security mechanisms defined in
[I-D.ietf-lisp-rfc6833bis] [RFC9301] is to
prevent unauthorized insertion of mapping data by providing origin
authentication and integrity protection for the Map-Register, Map-Register and by
using the nonce to detect an unsolicited Map-Reply sent by off-path
attackers.
LISP-SEC builds on top of the security mechanisms defined in
[RFC9301] to address the threats described in Section 4 by leveraging
the trust relationships existing among the LISP entities
([I-D.ietf-lisp-rfc6833bis]) [RFC9301]
participating in the exchange of the Map-Request/Map-Reply messages.
Those trust relationships (see also Section 7 and [I-D.ietf-lisp-rfc6833bis]) [RFC9301]) are used
to securely distribute, as described in Section 8.4, a per-message
One-Time Key (OTK) that provides origin authentication, integrity integrity,
and anti-replay protection to mapping data conveyed via the mapping
lookup process, process and that effectively prevent prevents overclaiming attacks.
The processing of security parameters during the Map-Request/Map-Reply Map-Request/Map-
Reply exchange is as follows:
o
* Per each Map-Request message message, a new ITR-OTK is generated and
stored at the ITR, ITR and is securely transported to the Map-Server.
o
* The Map-Server uses the ITR-OTK to compute a Keyed-Hashing for Hashed Message
Authentication Code (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, ETR by applying a Key Derivation
Function (KDF) (e.g. (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.
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, ECM, decrypts the ITR-
OTK, if needed, 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. ECM. 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, ECM, finds the
longest match EID-prefix
longest-match EID-Prefix that covers the requested EID in the
received Map-Request. The Map-Server adds this EID-prefix, EID-Prefix,
together with an HMAC computed using the ITR-OTK, to a new
Encapsulated Control Message ECM
that contains the received Map-
Request. Map-Request.
4. The Map-Server derives a new OTK, the MS-OTK, by applying a Key
Derivation Function (KDF) KDF
to the ITR-OTK. This MS-OTK is included in the Encapsulated Control Message ECM that the Map-Server 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],
[RFC9301], the ETR is not involved in the generation of the Map-Reply Map-
Reply and steps 6 and 7 are skipped. In this case case, the Map-Server Map-
Server generates the Map-Reply on behalf of the
ETR ETR, as described
in Section 6.7.2.
6. The ETR, upon receiving the ECM encapsulated ECM-Encapsulated Map-Request from the
Map-Server, decrypts the MS-OTK, if needed, MS-OTK (if needed), and originates a Map-
Reply
Map-Reply that contains the EID-to-RLOC mapping information as
specified in [I-D.ietf-lisp-rfc6833bis]. [RFC9301].
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 EID-Prefix authorization data that the Map-Server
included in the ECM encapsulated 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 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
ECM-Encapsulated Map-Reply) used by the Map-Server, 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) an HMAC in various places (as described in
the following). The HMAC function AUTH-HMAC-SHA-256-128 [RFC6234]
MUST be supported in LISP-
SEC LISP-SEC implementations. LISP-SEC deployments
SHOULD use AUTH-HMAC-SHA-
256-128 the AUTH-HMAC-SHA-256-128 HMAC function, except when
communicating with older implementations that only support AUTH-HMAC-SHA-1-96 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] [RFC9301] with S
bit the S-bit set to 1 to
indicate that the LISP header includes Authentication Data (AD). The
format of the LISP-SEC ECM Authentication Data AD is defined in Figure 1 . 1. OTK-AD stands
for One-Time Key Authentication Data and EID-AD stands for EID
Authentication Data.
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-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 which 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 which 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 Per-message
keys are derived from the pre-shared secret to encrypt,
authenticate the origin origin, and protect the integrity of the OTK.
The Key ID allows to rotate between multiple pre-shared secrets in
a
non disruptive nondisruptive way.
OTK Wrapping ID (OTK Wrap. ID): The identifier of the key
derivation function Key Derivation
Function and of the key wrapping algorithm used to encrypt the
One-Time-Key. Permitted values are registered in the LISP-SEC
Authentication Data Key Wrap ID (see Section 8.4). Refer to
Section 6.5 for more details.
One-Time-Key Preamble: set 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 The OTK wrapped as specified by OTK Wrapping ID. See
Section 6.5 for details.
EID-AD Length: 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 'KDF ID' field, and all the remaining fields part
of the EID-AD are not present. An EID-AD MAY contain multiple EID-
records.
EID-Records. Each EID-record EID-Record is 4-byte long 4 bytes long, plus the length of
the AFI-encoded EID-prefix. 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]. [RFC9301].
E: ETR-Cant-Sign bit. If this bit is set to 1, it signals to the
ITR that at least one of the ETRs that is authoritative for the EID
prefixes
EID-Prefixes of this Map-Reply has not enabled LISP-SEC. Only a Map-
Server
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 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]. [RFC9301].
EID-AFI: As defined in Section 5.2 of [I-D.ietf-lisp-rfc6833bis].
EID-prefix: [RFC9301].
EID-Prefix: As defined in Section 5.2 of
[I-D.ietf-lisp-rfc6833bis]. [RFC9301].
EID HMAC: HMAC of the EID-AD computed and inserted by a Map-Server 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], [RFC9301], with Type set to 2, 2
and S-bit set to 1 to indicate that the Map-Reply message includes
Authentication Data (AD). The format of the LISP-
SEC 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-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 Length (in bytes) of the EID-AD (see Section 6.1).
KDF ID: Identifier of the Key Derivation Function used to derive
MS-OTK 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).
EID mask-len: Mask length for EID-prefix EID-Prefix (see Section 6.1).
EID-AFI: See Section 6.1. .
EID-prefix:
EID-Prefix: See Section 6.1.
EID HMAC: See Section 6.1.
PKT-AD Length: 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 packet to protect its
integrity;
integrity, including the LISP-SEC Authentication Data (from the
Map-Reply Type
'Map-Reply Type' field to the PKT HMAC 'PKT HMAC' field), which allow
message
authetification. authentication.
6.3. Map-Register LISP-SEC Extensions
The S bit S-bit in the Map-Register message (see
[I-D.ietf-lisp-rfc6833bis]) [RFC9301]) indicates to
the Map-Server that the registering ETR is LISP-SEC enabled. An ETR
that supports LISP-SEC MUST set the S bit 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].
[RFC9301].
The ITR MAY use the KDF ID 'KDF ID' field to indicate the recommended KDF
algorithm,
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), 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]) [RFC9301]) MUST be encapsulated as a
LISP Control Message in an ECM, with the S-bit set to 1, to indicate
the presence of Authentication Data. Such a message is also called a
"Protected Map-Request" in this memo.
The ITR-OTK is wrapped with the algorithm specified by the OTK 'OTK
Wrapping ID 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. (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 'Requested HMAC ID 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 Data and of the Map-Reply. A HMAC ID Value value of
NONE (0), (0) MAY be used to specify that the ITR has no preferred HMAC
ID.
The KDF ID 'KDF ID' field specifies the suggested key derivation function Key Derivation Function to
be used by the Map-Server to derive the MS-OTK. A KDF Value value of NONE
(0) may be used to specify that the ITR has no preferred KDF ID.
The EID-AD length Length is set to 4 bytes, since the Authentication Data
does not contain EID-prefix EID-Prefix Authentication Data, and the EID-AD
contains only the KDF ID '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 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]. [RFC9301].
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,
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.
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 'OTK Wrapping
ID
ID' field. This field identifies both the:
o
* Key Encryption Algorithm used to encrypt the wrapped OTK.
o OTK and
* Key Derivation Function used to derive a per-message encryption
key.
Implementations of this specification MUST support the OTK Wrapping
ID
AES-KEY-WRAP-128+HKDF-SHA256 that AES-KEY-WRAP-128+HKDF-SHA256, which 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 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 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 which is the pre-shared secret
identified by the 'Key ID'.
4. The 128-bits long 128-bit-long per-message encryption key is computed as:
*
per-msg-key = KDF( nonce + s + PSK[Key ID] )
where the nonce is the value in the Nonce '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 The per-msg-key is then used to wrap the OTK with AES-KEY-WRAP-128. AES-KEY-WRAP-
128, as specified in Section 2.2.1 of [RFC3394]. The AES Key
Wrap Initialization Value MUST be set to 0xA6A6A6A6A6A6A6A6 (64
bits). The output of the AES Key Wrap key wrap operation is 192-bit 192 bits
long. The most significant
64-bit 64 bits are copied in the One-Time 'One-Time
Key Preamble Preamble' field, while the 128 less least significant bits are
copied in the One-Time Key 'One-Time Key' field of the LISP-SEC Authentication
Data.
When decrypting an encrypted OTK OTK, the receiver MUST verify that the
Initialization Value resulting from the AES Key Wrap key wrap decryption
operation is equal to 0xA6A6A6A6A6A6A6A6. If this verification fails
fails, the receiver MUST discard the entire message.
6.5.1. Unencrypted OTK
However, when DTLS is enabled 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 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. ECM. 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,
Map-Server is specific to the particular Mapping System used, used and is
outside of the scope of this memo.
In Mapping Systems where the Map-Server is compliant with
[I-D.ietf-lisp-rfc6833bis], [RFC9301],
the Map-Resolver originates a new ECM header with the S-bit set, that
which 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 Encapsulated Map-Request.
The Map-Resolver then forwards to the Map-Server the received Map-
Request, which is encapsulated in the new ECM header that includes
the newly computed Authentication Data 'Authentication Data' fields.
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
'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 process corresponding to
the first rule that matches the conditions indicated in the first
column:
+---------------------+---------------------------------------------+
+=================+==============================================+
| Matching Condition | Processing |
+---------------------+---------------------------------------------+
| Condition | |
+=================+==============================================+
| 1. At least one of | The Map-Server MUST generate a LISP-SEC LISP-SEC- |
| one of the ETRs | protected Map-Reply Map-Reply, as specified in |
| authoritative for | Section 6.7.2. The ETR-Cant-Sign E-bit in |
| for the EID prefix EID- | the EID Authentication Data (EID-AD) MUST be |
| Prefix included in the | be set to 0. |
| Map-Request in the Map- | |
| Request | |
| registered with the | |
| the P-bit set to 1 | |
| to 1 | |
+-----------------+----------------------------------------------+
| 2. At least one of | The Map-Server MUST generate a LISP-SEC LISP-SEC- |
| one of the ETRs | protected Encapsulated Map-Request (as |
| authoritative for | specified in Section 6.7.1), 6.7.1) to be sent to |
| for the EID prefix EID- | one of the authoritative ETRs that |
| Prefix included in the | registered with the S-bit set to 1 (and the |
| Map-Request in the Map- | P-bit set to 0). If there is at least one |
| registered with the Request | ETR that registered with the S-bit set to 0, |
| S-bit set to 1 registered with | 0, the ETR-Cant-Sign E-bit of the EID-AD MUST |
| the S-bit set | MUST be set to 1 to signal the ITR that a non- |
| to 1 | non LISP-SEC Map-Request might reach additional |
| | additional ETRs that have LISP-SEC |
| | disabled. |
| | |
+-----------------+----------------------------------------------+
| 3. All the ETRs | The Map-Server MUST send a Negative Map- |
| authoritative for ETRs | Reply protected with LISP-SEC, as described |
| the EID prefix authoritative | in Section 6.7.2. The ETR-Cant-Sign E-bit |
| included in for the EID- | MUST be set to 1 to signal the ITR that a |
| Map-Request Prefix included | non LISP-SEC non-LISP-SEC Map-Request might reach |
| registered with in the Map- | additional ETRs that have LISP-SEC disabled. |
| Request | |
| registered with | |
| the S-bit set | |
| to 0 | disabled. |
+---------------------+---------------------------------------------+
+-----------------+----------------------------------------------+
Table 1: Map-Request Processing. Processing
In this way way, the ITR that sent a LISP-SEC protected LISP-SEC-protected Map-Request
always receives a LISP-SEC protected LISP-SEC-protected Map-Reply. However, the ETR-Cant-Sign ETR-
Cant-Sign E-bit set to 1 specifies that a non LISP-SEC 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 non-LISP-SEC requests, which
does not protect against threats described in Section 4.
6.7.1. Generating a LISP-SEC Protected 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
the EID-AD, that which contains EID-prefix EID-Prefix authorization information, 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 by
applying the key derivation function Key Derivation Function specified in the KDF ID 'KDF ID' field.
If the algorithm specified in the KDF ID 'KDF ID' field is not supported,
the Map-Server uses a different algorithm to derive the key and
updates the KDF ID '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 'OTK Wrapping ID
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 Map-
Request MUST be dropped and an appropriate log action SHOULD be
taken.
The
In the EID-AD, the Map-Server includes in the EID-AD the longest match registered
EID-prefix longest-
match-registered EID-Prefix for the destination EID, EID and an HMAC of
this EID-prefix. 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 'Requested HMAC ID ID' field. If the Map-Server does
not support this algorithm, the Map-Server uses a different algorithm
and specifies it in the EID 'EID HMAC ID ID' field. The scope of the HMAC
operation MUST cover the entire EID-AD, from the EID-AD Length 'EID-AD Length'
field to the EID HMAC 'EID HMAC' field, which MUST be set to 0 before the
computation.
The Map-Server then forwards the updated ECM encapsulated ECM-Encapsulated Map-
Request, that which contains the OTK-AD, the EID-AD, and the received Map-
Request to an authoritative ETR as specified in
[I-D.ietf-lisp-rfc6833bis]. [RFC9301].
6.7.2. Generating a Proxy Map-Reply
A LISP-SEC proxy Map-Reply are is generated according to
[I-D.ietf-lisp-rfc6833bis], [RFC9301], with
the Map-Reply S-bit set to 1. The Map-Reply includes the
Authentication Data that contains the EID-AD, 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 ECM-Encapsulated Map-Request with the S-bit set,
the ETR decapsulates the ECM message. ECM. The OTK 'OTK' field, if encrypted, is
decrypted as specified in Section 6.5 to obtain the unencrypted
MS-OTK. MS-
OTK.
The ETR then generates a Map-Reply as specified in
[I-D.ietf-lisp-rfc6833bis] [RFC9301] and
includes the Authentication Data that contains the EID-AD, as
received in the encapsulated Encapsulated Map-Request, as well as the PKT-AD.
The EID-AD is copied from the Authentication Data of the received
encapsulated
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 'Requested HMAC ID ID' field of the received encapsulated Map-Request. Encapsulated Map-
Request. If the ETR does not support the Requested HMAC ID, it uses
a different algorithm and updates the PKT 'PKT HMAC ID ID' field
accordingly. The HMAC operation MUST cover the entire Map-Reply,
where the PKT
HMAC 'PKT HMAC' field MUST be set to 0 before the computation.
Finally
Finally, the ETR sends the Map-Reply to the requesting ITR as
specified in [I-D.ietf-lisp-rfc6833bis]. [RFC9301].
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 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, 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 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 recompute the HMAC of
the EID-AD using the algorithm specified in the EID 'EID HMAC ID 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 rate-
limitation policies defined in [I-D.ietf-lisp-rfc6833bis], [RFC9301], a new Map-
Request Map-Request with a
different Requested 'Requested HMAC ID ID' field, according to ITR's local policy.
The scope of the HMAC operation covers the entire EID-
AD, EID-AD, from the EID-AD Length
'EID-AD Length' field to the EID HMAC 'EID HMAC' field.
ITR MUST set the EID 'EID HMAC ID 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
'KDF ID' field. This is because the PKT-AD is generated by the ETR
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,
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 rate-limitation policies defined in
[I-D.ietf-lisp-rfc6833bis], [RFC9301], a new
Map-Request with a different KDF ID, according to ITR's local policy.
The key derivation function 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 recompute the HMAC of the PKT-AD
using the Algorithm algorithm specified in the PKT 'PKT HMAC ID ID' field. If the PKT
'PKT HMAC ID ID' field does not match the Requested HMAC ID ID, the ITR
MUST discard the Map-Reply and send, according to rate limitation rate-limitation
policies defined in [I-D.ietf-lisp-rfc6833bis], [RFC9301], a new Map-Request with a different
Requested HMAC ID ID, according to ITR's local policy or until all HMAC
IDs supported by the ITR have been attempted. When the PKT 'PKT HMAC ID ID'
field does not match the Requested HMAC ID ID, it is not possible to
validate the Map-Reply.
Each individual Map-Reply EID-record EID-Record is considered valid only if: (1)
both EID-AD and PKT-AD are valid, valid and (2) the intersection of the
EID-prefix EID-
Prefix in the Map-Reply EID-record EID-Record with one of the EID-prefixes EID-Prefixes
contained in the EID-AD is not empty. After identifying the Map-
Reply record as valid, the ITR sets the EID-prefix EID-Prefix in the Map-Reply
record to the value of the intersection set computed before, before and adds
the Map-Reply EID-record EID-Record to its EID-to-RLOC cache, Map-Cache, as described
in
[I-D.ietf-lisp-rfc6833bis]. [RFC9301]. An example of Map-Reply record validation is provided
in Section 6.9.1.
[I-D.ietf-lisp-rfc6833bis]
[RFC9301] allows ETRs to send Solicit-Map-Requests
(SMR) (SMRs) directly to
the ITR. The corresponding SMR-invoked Map-Request will be sent
through the mapping system, 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, EID-to-
RLOC Map-Cache, it MUST send a Map-Request over the mapping
system Mapping System in
order to verify its content with a secured Map-Reply, Map-Reply before using the
content.
6.9.1. Map-Reply Record Validation
The payload of a Map-Reply may contain multiple EID-records. 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 EID-Prefix
records claimed by the ETR. The Authentication Data 'Authentication Data' field of a Map-
Reply
Map-Reply may contain multiple EID-records 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 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 EID-Record claimed by
the ETR by computing the intersection of each one of the EID-prefix EID-Prefixes
contained in the payload of the Map-Reply Map-Reply, with each one of the EID-
prefixes
Prefixes contained in the EID-AD. An EID-record EID-Record is valid only if at
least one of the intersections is not the empty set, set; otherwise, a log
action MUST be taken and the EID-record 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:
Prefixes:
2001:db8:102::/48
2001:db8:103::/48
2001:db8:200::/40
The EID-AD contains two EID-prefixes: EID-Prefixes:
2001:db8:103::/48
2001:db8:203::/48
The EID-record EID-Record with EID-prefix EID-Prefix 2001:db8:102::/48 is not eligible to
be used by the ITR ITR, since it is not included in any of the EID-ADs
signed by the Map-Server. A log action MUST be taken taken, and the EID-
record
Record MUST be discarded. Implementations may include mechanisms
(which are beyond the scope of this document) to avoid log resource
exhaustion attacks.
The EID-record EID-Record with EID-prefix EID-Prefix 2001:db8:103::/48 is eligible to be
used by the ITR because it matches the second EID-prefix EID-Prefix contained in
the EID-AD.
The EID-record EID-Record with EID-prefix EID-Prefix 2001:db8:200::/40 is not eligible to
be used by the ITR 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
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 example, the ETR is trying to over
claim the EID-prefix EID-Prefix 2001:db8:200::/40, but the Map-Server authorized
only 2001:db8:203::/48, hence 2001:db8:203::/48; hence, the EID-record EID-Record is discarded.
7. Security Considerations
This document extends the LISP Control-Plane control plane defined in
[I-D.ietf-lisp-rfc6833bis], [RFC9301];
hence, its Security Considerations security considerations apply
as well to this document. document as well.
7.1. Mapping System Security
The LISP-SEC threat model described in Section 4, 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, 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 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.
7.4. Deploying LISP-SEC
Those deploying LISP-SEC according to this memo, memo should carefully
weight
weigh 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,
sophisticated and force the deployers to enforce very strict policies
in term terms of HMAC algorithms accepted by an ITR.
Similar considerations apply to the entire LISP-SEC threat model, 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 pairs as
well as between ETR and Map-Server pairs should be performed via an
orchestration infrastructure infrastructure, and it is out of the scope of this memo.
It is recommended that both shared keys are be 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 it; however, once the ITR receives the original Map-Reply 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 the replayed Map-Reply will
be discarded.
In the case of a replayed Map-Request, the Map-Server, Map-Resolver 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. e.g., using a pre-shared secret. DTLS has the responder be
verified by the initiator, which enables an ITR to autheticate authenticate the
Map-Resolver,
Map-Resolver and the Map-Server to authenticate the responding ETR.
7.8. Denial of Service Denial-of-Service and Distributed Denial of Service Denial-of-Service Attacks
LISP-SEC mitigates the risks of Denial of Service DoS and Distributed
Denial of Service DDoS attacks by protecting
the integrity and authenticating the origin of the Map-Request/Map-Reply messages, Map-Request/Map-
Reply messages and by preventing malicious ETRs from overclaiming EID prefixes
EID-Prefixes that could re-direct redirect traffic directed to a potentially
large number of hosts.
8. IANA Considerations
IANA is requested to create has created the sub-registries subregistries listed in the following sections
in the "Locator/ID Separation Protocol (LISP) Parameters" registry.
For all of the sub-registries, subregistries, new values beyond this document have
to be are assigned according to
the "Specification Required" Specification Required policy defined in [RFC8126]. Expert review
Review should assess the security properties of newly added functions, functions
so that encryption robustness is remains strong. For instance, at the
time of this writing 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 has created the "ECM "LISP ECM Authentication Data Type" Types" registry
with values 0-255, 0-255 for use in the ECM LISP-SEC Extensions extensions (see
Section 6.1. 6.1). Initial allocation of this registry is allocations are shown in Table 2.
+------------------+--------+------------+
+==================+========+============+
| Name | Number | Defined in |
+------------------+--------+------------+
+==================+========+============+
| Reserved | 0 | This memo RFC 9303 |
+------------------+--------+------------+
| LISP-SEC-ECM-EXT | 1 | This memo RFC 9303 |
+------------------+--------+------------+
Table 2: LISP ECM Authentication Data Types.
Types
Values 2-255 are unassigned.
8.2. Map-Reply AD Type Types Registry
IANA is requested to create has created the "Map-Reply "LISP Map-Reply Authentication Data Type" Types"
registry with values 0-255, 0-255 for use in the Map-Reply LISP-SEC
Extensions
extensions (see Section 6.2. 6.2). Initial allocation of this registry is allocations are shown in
Table 3.
+-----------------+--------+------------+
+=================+========+============+
| Name | Number | Defined in |
+-----------------+--------+------------+
+=================+========+============+
| Reserved | 0 | This memo RFC 9303 |
+-----------------+--------+------------+
| LISP-SEC-MR-EXT | 1 | This memo RFC 9303 |
+-----------------+--------+------------+
Table 3: Map-Reply Authentication
Data Types. Types
Values 2-255 are unassigned.
8.3. HMAC Functions
IANA is requested to create the "LISP-SEC Preferred Authentication
Data HMAC ID" IDs" registry with values 0-65535 for use as Requested HMAC
ID,
IDs, EID HMAC ID, IDs, and PKT HMAC ID IDs in the LISP-SEC Authentication
Data. Initial allocation of this registry is allocations are shown in Table 4.
+-----------------------+--------+------------+
+=======================+========+============+
| Name | Number | Defined in |
+-----------------------+--------+------------+
+=======================+========+============+
| NOPREF | 0 | This memo RFC 9303 |
+-----------------------+--------+------------+
| AUTH-HMAC-SHA-1-96 | 1 | [RFC2104] |
+-----------------------+--------+------------+
| AUTH-HMAC-SHA-256-128 | 2 | [RFC6234] |
+-----------------------+--------+------------+
Table 4: LISP-SEC Preferred Authentication
Data HMAC Functions. IDs
Values 3-65535 are unassigned.
8.4. Key Wrap Functions
IANA is requested to create has created the "LISP-SEC Authentication Data Key Wrap ID" IDs"
registry with values 0-65535 for use as OTK key wrap
algorithms ID algorithm IDs in
the LISP-SEC Authentication Data. Initial
allocation of this registry is allocations are shown in
Table 5.
+------------------------------+--------+-----------+-----------+
+==============================+======+=========+=========+=========+
| Name | Number | KEY WRAP | KDF |
+------------------------------+--------+-----------+-----------+ |Number|Key Wrap |KDF |Reference|
+==============================+======+=========+=========+=========+
| Reserved | 0 |None |None |RFC 9303 | None | None |
+------------------------------+------+---------+---------+---------+
| NULL-KEY-WRAP-128 | 1 |RFC 9303 |None |RFC 9303 | This memo | None |
+------------------------------+------+---------+---------+---------+
| AES-KEY-WRAP-128+HKDF-SHA256 | 2 |[RFC3394]|[RFC4868]|RFC 9303 | [RFC3394] | [RFC4868] |
+------------------------------+--------+-----------+-----------+
+------------------------------+------+---------+---------+---------+
Table 5: LISP-SEC Authentication Data Key Wrap Functions. IDs
Values 3-65535 are unassigned.
8.5. Key Derivation Functions
IANA is requested to create has created the "LISP-SEC Authentication Data Key Derivation
Function ID" IDs" registry with values 0-65535 for use as KDF
ID. IDs.
Initial allocation of this registry is allocations are shown in Table 6.
+----------------+--------------+------------+
+===============+========+===========+
| Name | Number | Defined in Reference |
+----------------+--------------+------------+
+===============+========+===========+
| NOPREF | 0 | This memo RFC 9303 |
+---------------+--------+-----------+
| HKDF-SHA1-128 | 1 | [RFC5869] |
+---------------+--------+-----------+
| HKDF-SHA256 | 2 | [RFC5869] |
+----------------+--------------+------------+
+---------------+--------+-----------+
Table 6: LISP-SEC Authentication
Data Key Derivation Function ID. IDs
Values 2-65535 3-65535 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.
9.1. 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.
[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>.
[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
[RFC9300] Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A.
Cabellos, Ed., "The Locator/ID Separation Protocol
(LISP)", RFC 9300, DOI 10.17487/RFC9300, October 2022,
<https://www.rfc-editor.org/info/rfc9300>.
[RFC9301] Farinacci, D., Maino, F., Fuller, V., and A. Cabellos,
Ed., "Locator/ID Separation Protocol (LISP) Control
Plane", RFC 9301, DOI 10.17487/RFC9301, October 2022,
<https://www.rfc-editor.org/info/rfc9301>.
9.2. Informative 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>.
Acknowledgments
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.
Authors' Addresses
Fabio Maino
Cisco Systems
170 Tasman Drive
San Jose, California 95134
USA CA
United States of America
Email: fmaino@cisco.com
Vina Ermagan
Google
California
USA
Google, Inc.
1600 Amphitheatre Parkway
Mountain View, CA 94043
United States of America
Email: ermagan@gmail.com
Albert Cabellos
Universitat Politecnica de Catalunya
c/ Jordi Girona s/n
Barcelona
08034 Barcelona
Spain
Email: acabello@ac.upc.edu
Damien Saucez
Inria
2004 route des Lucioles - BP 93
Sophia Antipolis
France
Email: damien.saucez@inria.fr