--- 1/draft-ietf-lisp-sec-17.txt 2019-06-02 08:13:14.113021445 -0700 +++ 2/draft-ietf-lisp-sec-18.txt 2019-06-02 08:13:14.173022957 -0700 @@ -1,106 +1,115 @@ Network Working Group F. Maino -Internet-Draft V. Ermagan -Intended status: Standards Track Cisco Systems -Expires: June 2, 2019 A. Cabellos +Internet-Draft Cisco Systems +Intended status: Standards Track V. Ermagan +Expires: December 4, 2019 Google + A. Cabellos Universitat Politecnica de Catalunya D. Saucez INRIA - November 29, 2018 + June 2, 2019 LISP-Security (LISP-SEC) - draft-ietf-lisp-sec-17 + draft-ietf-lisp-sec-18 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 mapping lookup process. LISP-SEC also enables verification of authorization on EID- prefix claims in Map-Reply messages. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this - document are to be interpreted as described in [RFC2119]. + document are to be interpreted as described in BCP14 [RFC2119] + [RFC8174] when, and only when, they appear in all capitals, as shown + here. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on June 2, 2019. + This Internet-Draft will expire on December 4, 2019. Copyright Notice - Copyright (c) 2018 IETF Trust and the persons identified as the + Copyright (c) 2019 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 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include 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. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 3 + 2. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 4 3. LISP-SEC Threat Model . . . . . . . . . . . . . . . . . . . . 4 4. Protocol Operations . . . . . . . . . . . . . . . . . . . . . 5 5. LISP-SEC Control Messages Details . . . . . . . . . . . . . . 7 5.1. Encapsulated Control Message LISP-SEC Extensions . . . . 7 - 5.2. Map-Reply LISP-SEC Extensions . . . . . . . . . . . . . . 9 + 5.2. Map-Reply LISP-SEC Extensions . . . . . . . . . . . . . . 10 5.3. Map-Register LISP-SEC Extentions . . . . . . . . . . . . 11 - 5.4. ITR Processing . . . . . . . . . . . . . . . . . . . . . 11 - 5.4.1. Map-Reply Record Validation . . . . . . . . . . . . . 13 - 5.4.2. PITR Processing . . . . . . . . . . . . . . . . . . . 14 - 5.5. Encrypting and Decrypting an OTK . . . . . . . . . . . . 14 - 5.6. Map-Resolver Processing . . . . . . . . . . . . . . . . . 15 + 5.4. ITR Processing: Generating a Map-Request . . . . . . . . 12 + 5.4.1. PITR Processing . . . . . . . . . . . . . . . . . . . 12 + 5.5. Encrypting and Decrypting an OTK . . . . . . . . . . . . 12 + 5.5.1. Unencrypted OTK . . . . . . . . . . . . . . . . . . . 14 + 5.6. Map-Resolver Processing . . . . . . . . . . . . . . . . . 14 5.7. Map-Server Processing . . . . . . . . . . . . . . . . . . 15 - 5.7.1. Map-Server Processing in Proxy mode . . . . . . . . . 16 - 5.8. ETR Processing . . . . . . . . . . . . . . . . . . . . . 16 - 6. Security Considerations . . . . . . . . . . . . . . . . . . . 17 - 6.1. Mapping System Security . . . . . . . . . . . . . . . . . 17 - 6.2. Random Number Generation . . . . . . . . . . . . . . . . 17 - 6.3. Map-Server and ETR Colocation . . . . . . . . . . . . . . 17 - 6.4. Deploying LISP-SEC . . . . . . . . . . . . . . . . . . . 18 - 6.5. Shared Keys Provisioning . . . . . . . . . . . . . . . . 18 - 6.6. Replay Attacks . . . . . . . . . . . . . . . . . . . . . 18 - 6.7. Message Privacy . . . . . . . . . . . . . . . . . . . . . 19 + 5.7.1. Generating a LISP-SEC Protected Encapsulated Map- + Request . . . . . . . . . . . . . . . . . . . . . . . 17 + 5.7.2. Generating a Proxy Map-Reply . . . . . . . . . . . . 18 + 5.8. ETR Processing . . . . . . . . . . . . . . . . . . . . . 18 + 5.9. ITR Processing: Receiving a Map-Reply . . . . . . . . . . 18 + 5.9.1. Map-Reply Record Validation . . . . . . . . . . . . . 20 + 6. Security Considerations . . . . . . . . . . . . . . . . . . . 21 + 6.1. Mapping System Security . . . . . . . . . . . . . . . . . 21 + 6.2. Random Number Generation . . . . . . . . . . . . . . . . 21 + 6.3. Map-Server and ETR Colocation . . . . . . . . . . . . . . 21 + 6.4. Deploying LISP-SEC . . . . . . . . . . . . . . . . . . . 21 + 6.5. Shared Keys Provisioning . . . . . . . . . . . . . . . . 22 + 6.6. Replay Attacks . . . . . . . . . . . . . . . . . . . . . 22 + 6.7. Message Privacy . . . . . . . . . . . . . . . . . . . . . 22 6.8. Denial of Service and Distributed Denial of Service - Attacks . . . . . . . . . . . . . . . . . . . . . . . . . 19 - 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 - 7.1. ECM AD Type Registry . . . . . . . . . . . . . . . . . . 19 - 7.2. Map-Reply AD Type Registry . . . . . . . . . . . . . . . 19 - 7.3. HMAC Functions . . . . . . . . . . . . . . . . . . . . . 20 - 7.4. Key Wrap Functions . . . . . . . . . . . . . . . . . . . 20 - 7.5. Key Derivation Functions . . . . . . . . . . . . . . . . 21 - 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21 - 9. Normative References . . . . . . . . . . . . . . . . . . . . 21 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 + Attacks . . . . . . . . . . . . . . . . . . . . . . . . . 23 + 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 + 7.1. ECM AD Type Registry . . . . . . . . . . . . . . . . . . 23 + 7.2. Map-Reply AD Type Registry . . . . . . . . . . . . . . . 23 + 7.3. HMAC Functions . . . . . . . . . . . . . . . . . . . . . 24 + 7.4. Key Wrap Functions . . . . . . . . . . . . . . . . . . . 24 + 7.5. Key Derivation Functions . . . . . . . . . . . . . . . . 25 + 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 25 + 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 + 9.1. Normative References . . . . . . . . . . . . . . . . . . 25 + 9.2. Informative References . . . . . . . . . . . . . . . . . 27 + 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- @@ -115,40 +124,45 @@ [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 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. Additional security - considerations are described in Section 6. + 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 securely downgrade to non LISP- + SEC Map-Requests. Additional security considerations are described + in Section 6. 2. 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 ITR. + 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 - Section 6.1.8 of [I-D.ietf-lisp-rfc6833bis], or in a Map-Reply - message to support confidentiality, integrity protection, and - verification of EID-prefix authorization. + [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 @@ -169,491 +183,482 @@ message to their intended destination ETR as identified by the EID, and (2) no man-in-the-middle (MITM) attack can be mounted within the LISP Mapping System. How the Mapping System is protected from MITM attacks depends from the particular Mapping Systems used, and is out of the scope of this memo. Furthermore, while LISP-SEC enables detection of EID prefix overclaiming attacks, it assumes that Map- Servers can verify the EID prefix authorization at time of registration. According to the threat model described in [RFC7835] LISP-SEC assumes - that any kind of attack, including MITM attacks, can be mounted in - the access network, 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 - directed to a large number of hosts. + that any kind of attack, including MITM 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 directed to a large + number of hosts. 4. 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-Registration, and by using the nonce to detect + 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 [I-D.ietf-lisp-rfc6833bis] to address the threats described in Section 3 by leveraging the trust relationships existing among the LISP entities participating to the exchange of the Map-Request/Map- Reply messages. Those trust relationships are used to securely - distribute a 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: + distribute, as described in Section 7.4, 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 The ITR-OTK is generated and stored at the ITR, and securely - transported to the Map-Server. + 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) to the ITR-OTK. + 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. 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 5 provides the detailed description of the LISP-SEC control messages and their processing, while the rest of this section - describes the flow of protocol operations at each entity involved in - the Map-Request/Map-Reply exchange: + describes the flow of LISP protocol operations at each entity + involved in the Map-Request/Map-Reply exchange: - o The ITR, upon needing to transmit a Map-Request message, generates - and stores an OTK (ITR-OTK). This ITR-OTK is included into the - Encapsulated Control Message (ECM) that contains the Map-Request - sent to the Map-Resolver. To provide confidentiality to the ITR- - OTK over the path between the ITR and its Map-Resolver, the ITR- - OTK SHOULD be encrypted using a preconfigured key shared between - the ITR and the Map-Resolver, similar to the key shared between - the ETR and the Map-Server in order to secure ETR registration - [I-D.ietf-lisp-rfc6833bis]. + 1. The ITR, upon needing to transmit a Map-Request message, + generates and stores an OTK (ITR-OTK). This ITR-OTK is included + into the Encapsulated Control Message (ECM) that contains the + Map-Request sent to the Map-Resolver. 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 (as specified in Section 5.5), or by + enabling DTLS between the ITR and the Map-Resolver. - o The Map-Resolver decapsulates the ECM message, decrypts the ITR- + 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. As described in Section 5.6, the LISP Mapping System - delivers the ECM to the appropriate Map-Server, as identified by - the EID destination address of the Map-Request. + message. The LISP Mapping System delivers the ECM to the + appropriate Map-Server, as identified by the EID destination + address of the Map-Request. As mentioned in Section 3, how the + Mapping System is protected from MITM attacks depends from the + particular Mapping Systems used, and is out of the scope of this + memo. - o 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. + 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. - o 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. To provide MS-OTK - confidentiality over the path between the Map-Server and the ETR, - the MS-OTK SHOULD be encrypted using the key shared between the - ETR and the Map-Server in order to secure ETR registration - [I-D.ietf-lisp-rfc6833bis]. + 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. 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 encrypting the MS-OTK with the pre-shared secret known + to the Map-Server and the ETR (as specified in Section 5.5), or + by enabling DTLS between the Map-Server and the ETR. - o If the Map-Server is acting in proxy mode, as specified in + 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. In this case the Map-Server - generates the Map-Reply on behalf of the ETR as described below. + 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 5.7.2. - o The ETR, upon receiving the ECM encapsulated Map-Request from the - Map-Server, decrypts the MS-OTK, if needed, and originates a - standard Map-Reply that contains the EID-to-RLOC mapping - information as specified in [I-D.ietf-lisp-rfc6833bis]. + 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]. - o The ETR computes an HMAC over this standard 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 + 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 this complete Map-Reply message to + message. The ETR then sends the complete Map-Reply message to the requesting ITR. - o The ITR, upon receiving the Map-Reply, uses the locally stored + 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 used by the Map- - Server, and verifies the integrity of the Map-Reply. If the - integrity checks fail, the Map-Reply MUST be discarded. Also, if - the EID-prefixes claimed by the ETR in the Map-Reply are not equal - or more specific than the EID-prefix authorization data inserted - by the Map-Server, the ITR MUST discard the Map-Reply. + 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. If the integrity checks fail, + the Map-Reply MUST be discarded. Also, if the EID-prefixes + claimed by the ETR in the Map-Reply are not equal or more + specific than the EID-prefix authorization data inserted by the + Map-Server, the ITR MUST discard the Map-Reply. 5. 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. 5.1. Encapsulated Control Message LISP-SEC Extensions - LISP-SEC uses the ECM (Encapsulated Control Message) defined in - [I-D.ietf-lisp-rfc6833bis] with Type set to 8, and 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 the - following figure. OTK-AD stands for One-Time Key Authentication Data - and EID-AD stands for EID Authentication Data. + 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. 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 |V| Reserved | Requested HMAC ID | + | ECM AD Type |V| Unassigned | Requested HMAC ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+\ - | OTK Length | OTK Encryption 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 | Reserved | EID HMAC ID |EID-AD + | Record Count |E| Unassigned | EID HMAC ID |EID-AD +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+\ | - | Reserved | EID mask-len | EID-AFI | | | + | Unassigned | EID mask-len | EID-AFI | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Rec | ~ EID-prefix ... ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+/ | ~ EID HMAC ~ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ <---+ - LISP-SEC ECM Authentication Data + Figure 1: LISP-SEC ECM Authentication Data ECM AD Type: 1 (LISP-SEC Authentication Data). See Section 7. V: Key Version bit. This bit is toggled when the sender switches to a new OTK wrapping key - Reserved: Set to 0 on transmission and ignored on receipt. + Unassigned: Set to 0 on transmission and ignored on receipt. - Requested HMAC ID: The HMAC algorithm requested by the ITR. See - Section 5.4 for details. + Requested HMAC ID: The HMAC algorithm, that will be used to + protect the mappings, requested by the ITR. See Section 5.4 for + details, and Section 7.3 for HMAC IDs that MUST be supported. OTK Length: The length (in bytes) of the OTK Authentication Data (OTK-AD), that contains the OTK Preamble and the OTK. - OTK Encryption ID: The identifier of the key wrapping algorithm - used to encrypt the One-Time-Key. When a 128-bit OTK is sent - unencrypted by the Map-Resolver, the OTK Encryption ID is set to - NULL_KEY_WRAP_128. See Section 5.5 for more details. + 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: The identifier of the key derivation function and + of the key wrapping algorithm used to encrypt the One-Time-Key. + See Section 5.5 for more details, and Section 7.4 for Wrapping IDs + that MUST be supported. 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 Map-Resolver, the OTK Preamble is set to - 0x0000000000000000 (64 bits). See Section 5.5 for details. + 0x0000000000000000 (64 bits). See Section 5.5.1 for details. - One-Time-Key: the OTK encrypted (or not) as specified by OTK - Encryption ID. See Section 5.5 for details. + One-Time-Key: the OTK wrapped as specified by OTK Wrapping ID. + See Section 5.5 for details. EID-AD Length: length (in bytes) of the EID Authentication Data (EID-AD). The ITR MUST set 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. The ITR MAY use this 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 5.4 for more details. + recommended by the ITR. See Section 5.4 for more details, and + Section 7.5 for KDF IDs that MUST be supported. Record Count: The number of records in this Map-Request message. A record is comprised of the portion of the packet that is labeled 'Rec' above and occurs the number of times equal to Record Count. - Reserved: Set to 0 on transmission and ignored on receipt. + E: ETR-Cant-Sign bit. This bit is set to 1 to signal to the ITR + that at least one of the ETRs authoritative for the EID prefixes + of this Map-Reply has not enabled LISP-SEC. This allows the ITR + to securely downgrade to non LISP-SEC requests, as specified in + Section 5.7, if so desired. + + 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 Map-Server that - computed the EID-prefix HMAC. See Section 5.4 for more details. + computed the EID-prefix HMAC. See Section 5.4 for more details, + and Section 7.3 for HMAC IDs that MUST be supported. EID mask-len: Mask length for EID-prefix. EID-AFI: Address family of EID-prefix according to [RFC5226] - EID-prefix: The Map-Server uses this field to specify the EID- prefix that the destination ETR is authoritative for, and is the longest match for the requested EID. EID HMAC: HMAC of the EID-AD computed and inserted by Map-Server. Before computing the HMAC operation the EID HMAC field MUST be set - to 0. The HMAC covers the entire EID-AD. + to 0. The HMAC MUST cover the entire EID-AD. 5.2. 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 + 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 the following figure. - - PKT-AD is the Packet Authentication Data that covers the Map-Reply - payload. + 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 | Reserved | + | MR AD Type | Unassigned | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ <---+ | EID-AD Length | KDF ID | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | - | Record Count | Reserved | EID HMAC ID |EID-AD + | Record Count | Unassigned | EID HMAC ID |EID-AD +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+\ | - | Reserved | EID mask-len | EID-AFI | | | + | Unassigned | EID mask-len | EID-AFI | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Rec | ~ EID-prefix ... ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+/ | ~ EID HMAC ~ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ <---+ | PKT-AD Length | PKT HMAC ID |\ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ~ PKT HMAC ~PKT-AD +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+/ - LISP-SEC Map-Reply Authentication Data + Figure 2: LISP-SEC Map-Reply Authentication Data MR AD Type: 1 (LISP-SEC Authentication Data). See Section 7. EID-AD Length: length (in bytes) of the EID-AD. 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 - MS-OTK. See Section 5.7 for more details. + MS-OTK. See Section 5.7 for more details, and Section 7.5 for KDF + IDs that MUST be supported. Record Count: The number of records in this Map-Reply message. A record is comprised of the portion of the packet that is labeled 'Rec' above and occurs the number of times equal to Record Count. - Reserved: Set to 0 on transmission and ignored on receipt. + 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 5.7 for more details. + integrity of the EID-AD. See Section 5.7 for more details, and + Section 7.3 for HMAC IDs that MUST be supported. EID mask-len: Mask length for EID-prefix. - EID-AFI: Address family of EID-prefix according to [RFC5226]. + EID-AFI: Address family of EID-prefix according to [RFC8060]. EID-prefix: This field contains an EID-prefix that the destination ETR is authoritative for, and is the longest match for the requested EID. EID HMAC: HMAC of the EID-AD, as computed by the Map-Server. Before computing the HMAC operation the EID HMAC field MUST be set to 0. The HMAC covers the entire EID-AD. 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. + integrity of the Map-Reply. See Section 7.3 for HMAC IDs that + MUST be supported. PKT HMAC: HMAC of the whole Map-Reply packet, including the LISP- SEC Authentication Data. The scope of the authentication goes from the Map-Reply Type field to the PKT HMAC field included. Before computing the HMAC operation the PKT HMAC field MUST be set to 0. See Section 5.8 for more details. 5.3. Map-Register LISP-SEC Extentions - This memo is allocating one of the bits marked as Reserved in the - Map-Register message defined in Section 6.1.6 of - [I-D.ietf-lisp-rfc6833bis]. More precisely, the second bit after the - Type field in a Map-Register message is allocated as the S bit. The - S bit 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. + This memo is allocating one of the bits marked as Unassigned in the + Map-Register message defined in [I-D.ietf-lisp-rfc6833bis]. More + precisely, the second bit after the Type field in a Map-Register + message is allocated as the S bit. The S bit 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. -5.4. ITR Processing +5.4. ITR Processing: Generating a Map-Request Upon creating a Map-Request, the ITR generates a random ITR-OTK that - is stored locally, together with the nonce generated as specified in + is stored locally (until the corresponding Map-Reply is received), + together with the nonce generated as specified in [I-D.ietf-lisp-rfc6833bis]. + 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 5.5), or by enabling DTLS + between the ITR and the Map-Resolver. + The Map-Request MUST be encapsulated in an ECM, with the S-bit set to - 1, to indicate the presence of Authentication Data. If the ITR and - the Map-Resolver are configured with a shared key, the ITR-OTK - confidentiality SHOULD be protected by wrapping the ITR-OTK with the - algorithm specified by the OTK Encryption ID field. See Section 5.5 - for further details on OTK encryption. + 1, to indicate the presence of Authentication Data. + + ITR-OTK is wrapped with the algorithm specified by the OTK Wrapping + ID field. See Section 5.5 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 ITR and the Map-Resolver, the Map-Request + MUST be dropped and an appropiate log action SHOULD be taken. 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. 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. - In response to an encapsulated Map-Request that has the S-bit set, an - ITR MUST receive a Map-Reply with the S-bit set, that includes an - EID-AD and a PKT-AD. If the Map-Reply does not include both ADs, the - ITR MUST discard it. In response to an encapsulated Map-Request with - S-bit set to 0, the ITR expects a Map-Reply with S-bit set to 0, and - the ITR SHOULD discard the Map-Reply if the S-bit is set. - - 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 pair associated to the Map-Reply - - The integrity of the EID-AD is verified using the locally stored ITR- - OTK to re-compute the HMAC of the EID-AD using the algorithm - specified in the EID HMAC ID field. If the EID HMAC ID field does - not match the Requested HMAC ID the ITR SHOULD discard the Map-Reply - and send, at the first opportunity it needs to, 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, which must be set - to 0 before the computation of the HMAC. - - 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 - using the MS-OTK. If the KDF ID in the Map-Reply does not match the - KDF ID requested in the Map-Request, the ITR SHOULD discard the Map- - Reply and send, at the first opportunity it needs to, a new Map- - Request with a different KDF ID, according to ITR's local policy. - - 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 SHOULD - discard the Map-Reply and send, at the first opportunity it needs to, - 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. +5.4.1. PITR Processing - 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 5.4.1. + The processing performed by a PITR is equivalent to the processing of + an ITR. However, if the PITR is directly connected to a Mapping + System such as LISP+ALT [RFC6836], the PITR performs the functions of + both the ITR and the Map-Resolver forwarding the Map-Request + encapsulated in an ECM header that includes the Authentication Data + fields as described in Section 5.6. - The ITR SHOULD send SMR triggered Map-Requests over the mapping - system in order to receive a secure Map-Reply. If an ITR accepts - piggybacked Map-Replies, it SHOULD also send a Map-Request over the - mapping system in order to verify the piggybacked Map-Reply with a - secure Map-Reply. +5.5. Encrypting and Decrypting an OTK -5.4.1. Map-Reply Record Validation + 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 ITR or by + encrypting the MS-OTK with the pre-shared secret known to the Map- + Server and the ETR [I-D.ietf-lisp-rfc6833bis]. - 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. + 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. However, to prevent + ETR's overclaiming attacks, the ITR/Map-Resolver pre-shared secret + MUST have a different value than the Map-Server/ETR pre-shared + secret. - 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 MUST be taken and the - Map-Reply MUST NOT be processed any further. 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. + This section describes OTK processing in the ITR/Map-Resolver path, + as well as in the Map-Server/ETR path. - For instance, the Map-Reply payload contains 3 mapping record EID- - prefixes: + It's important to note that, to prevent ETR's overclaiming attacks, + the ITR/Map-Resolver pre-shared secret MUST be different from the + Map-Server/ETR pre-shared secret. - 2001:db8:0102::/48 + The OTK is wrapped using the algorithm specified in the OTK Wrapping + ID field. This field identifies both the: - 2001:db8:0103::/48 + o Key Encryption Algorithm used to encrypt the wrapped OTK, as well + as the - 2001:db8:0200::/40 + o Key Derivation Function used to derive a per-message encryption + key. - The EID-AD contains two EID-prefixes: + 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[RFC4868] 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]. - 2001:db8:0103::/48 + The key wrapping process for OTK Wrapping ID AES-KEY-WRAP-128+HKDF- + SHA256 is described below: - 2001:db8:0203::/48 + 1. The KDF algorithm is identified by the field 'OTK Wrapping ID' + according to the table in Section Section 7.4. - The EID-record with EID-prefix 2001:db8:0102::/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. + 2. The Key Wrap algorithm is identified by the field 'OTK Wrapping + ID' according to the table in Section Section 7.4. - The EID-record with EID-prefix 2001:db8:0103::/48 is eligible to be - used by the ITR because it matches the second EID-prefix contained in - the EID-AD. + 3. If the NULL-KEY-WRAP-128 algorithm (defined in (Section 7.4)) is + selected and DTLS is not enabled, the Map-Request MUST be dropped + and an appropiate log action SHOULD be taken. - The EID-record with EID-prefix 2001:db8:0200::/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. In this last - example the ETR is trying to over claim the EID-prefix - 2001:db8:0200::/40, but the Map-Server authorized only - 2001:db8:0203::/48, hence the EID-record is discarded. + 4. 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'. -5.4.2. PITR Processing + 5. The per-message encryption key key is computed as: - The processing performed by a PITR is equivalent to the processing of - an ITR. However, if the PITR is directly connected to a Mapping - System such as LISP+ALT [RFC6836], the PITR performs the functions of - both the ITR and the Map-Resolver forwarding the Map-Request - encapsulated in an ECM header that includes the Authentication Data - fields as described in Section 5.6. + * per-msg-key = KDF( nonce + s + PSK[Key ID] ) -5.5. Encrypting and Decrypting an OTK + * where the nonce is the value in the Nonce field of the Map- + Request, and - MS-OTK confidentiality is required in the path between the Map-Server - and the ETR, the MS-OTK SHOULD be encrypted using the preconfigured - key shared between the Map-Server and the ETR for the purpose of - securing ETR registration [I-D.ietf-lisp-rfc6833bis]. Similarly, if - ITR-OTK confidentiality is required in the path between the ITR and - the Map-Resolver, the ITR-OTK SHOULD be encrypted with a key shared - between the ITR and the Map-Resolver. + * 's' is the string "OTK-Key-Wrap" - The OTK is encrypted using the algorithm specified in the OTK - Encryption ID field. When the AES Key Wrap algorithm is used to - encrypt a 128-bit OTK, according to [RFC3394], 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. + 6. 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. - When a 128-bit OTK is sent unencrypted the OTK Encryption ID is set - to NULL_KEY_WRAP_128, and the OTK Preamble is set to - 0x0000000000000000 (64 bits). +5.5.1. Unencrypted OTK + + MS-OTK confidentiality and integrity protection MUST be provided in + the path between the Map-Server and the ETR. Similarly, ITR-OTK + confidentiality and integrity protection MUST be provided in the path + between the ITR and the Map-Resolver. + + 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). 5.6. Map-Resolver Processing Upon receiving an encapsulated Map-Request with the S-bit set, the Map-Resolver decapsulates the ECM message. The ITR-OTK, if encrypted, is decrypted as specified in Section 5.5. 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 @@ -664,71 +669,130 @@ header with the S-bit set, that contains the unencrypted ITR-OTK, as specified in Section 5.5, 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. 5.7. Map-Server Processing - Upon receiving an ECM encapsulated Map-Request with the S-bit set, - the Map-Server process the Map-Request according to the value of the - S-bit contained in the Map-Register sent by the ETR during - registration. + Upon receiving an ECM encapsulated Map-Request with the S-bit set to + 1, the Map-Server process the Map-Request according to the value of + the security-capable S-bit and of the proxy map-reply P-bit contained + in the Map-Register sent by the ETRs authoritative for that prefix + during registration. - If the S-bit contained in the Map-Register was clear the Map-Server - decapsulates the ECM and generates a new ECM encapsulated Map-Request - that does not contain an ECM Authentication Data, as specified in - [I-D.ietf-lisp-rfc6833bis]. The Map-Server does not perform any - further LISP-SEC processing, and the Map-Reply will not be protected. + 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: - If the S-bit contained in the Map-Register was set 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 - contains EID-prefix authorization information, that are ultimately - sent to the requesting ITR. + +----------------+--------------------------------------------------+ + | Matching | Processing | + | Condition | | + +----------------+--------------------------------------------------+ + | 1. At least | The Map-Server MUST generate a LISP-SEC | + | one of the | protected Map-Reply as specified in Section | + | ETRs | 5.7.2. The ETR-Cant-Sign E-bit in the EID | + | authoritative | Authentication Data (EID-AD) MUST be set to 0. | + | for the EID | | + | prefix | | + | included in | | + | the Map- | | + | Request | | + | registered | | + | with the P-bit | | + | set to 1 | | + | | | + | 2. At least | The Map-Server MUST generate a LISP-SEC | + | one of the | protected Encapsulated Map-Request (as specified | + | ETRs | in Section 5.7.1), to be sent to one of the | + | authoritative | authoritative ETRs that registered with the | + | for the EID | S-bit set to 1 (and the P-bit set to 0). If | + | prefix | there is at least one ETR that registered with | + | included in | the S-bit set to 0, the ETR-Cant-Sign E-bit of | + | the Map- | the EID-AD MUST be set to 1 to signal the ITR | + | Request | that a non LISP-SEC Map-Request might reach | + | registered | additional ETRs that have LISP-SEC disabled. | + | with the S-bit | | + | set to 1 | | + | | | + | 3. All the | The Map-Server MUST send a Negative Map-Reply | + | ETRs | protected with LISP-SEC, as described in Section | + | authoritative | 5.7.2. The ETR-Cant-Sign E-bit MUST be set to 1 | + | for the EID | to signal the ITR that a non LISP-SEC Map- | + | prefix | Request might reach additional ETRs that have | + | included in | LISP-SEC disabled. | + | the Map- | | + | Request | | + | registered | | + | with the S-bit | | + | set to 0 | | + +----------------+--------------------------------------------------+ + + 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 securely downgrade to non LISP-SEC requests, if so + desired. + +5.7.1. 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 + 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-Server and the ETR MUST be configured with a shared key for - mapping registration according to [I-D.ietf-lisp-rfc6833bis]. If MS- - OTK confidentiality is required, then the MS-OTK SHOULD be encrypted, - by wrapping the MS-OTK with the algorithm specified by the OTK - Encryption ID field as specified in Section 5.5. + 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. + + 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 5.5 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 appropiate 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 covers 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]. -5.7.1. Map-Server Processing in Proxy mode +5.7.2. Generating a Proxy Map-Reply - If the Map-Server is in proxy mode, it generates a Map-Reply, as - specified in [I-D.ietf-lisp-rfc6833bis], with the S-bit set to 1. - The Map-Reply includes the Authentication Data that contains the EID- - AD, computed as specified in Section 5.7, as well as the PKT-AD + LISP-SEC proxy Map-Reply are generated according to + [I-D.ietf-lisp-rfc6833bis], with the Map-Replay S-bit set to 1. The + Map-Reply includes the Authentication Data that contains the EID-AD, + computed as specified in Section 5.7.1, as well as the PKT-AD computed as specified in Section 5.8. 5.8. 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 5.5 to obtain the unencrypted MS-OTK. The ETR then generates a Map-Reply as specified in @@ -739,25 +803,138 @@ 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 scope of the HMAC operation covers the entire PKT-AD, from the Map-Reply Type field to the PKT HMAC field, which must be set to 0 - before the computation. + bendlfore the computation. Finally the ETR sends the Map-Reply to the requesting ITR as specified in [I-D.ietf-lisp-rfc6833bis]. +5.9. ITR Processing: Receiving a Map-Reply + + In response to an encapsulated Map-Request that has the S-bit set, an + ITR MUST receive a Map-Reply with the S-bit set, that includes an + EID-AD and a PKT-AD. If the Map-Reply does not include both ADs, the + ITR MUST discard it. In response to an encapsulated Map-Request with + S-bit set to 0, the ITR expects a Map-Reply with S-bit set to 0, and + the ITR SHOULD discard the Map-Reply if the S-bit is set. + + 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 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 EID HMAC ID field does not match the Requested HMAC ID the ITR + SHOULD discard the Map-Reply and send, at the first opportunity it + needs to, 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, which must be set to 0 before the computation of the + HMAC. + + 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 + using the MS-OTK. If the KDF ID in the Map-Reply does not match the + KDF ID requested in the Map-Request, the ITR SHOULD discard the Map- + Reply and send, at the first opportunity it needs to, a new Map- + Request with a different KDF ID, according to ITR's local policy. + Without consistent configuration of involved entities, extra delays + may be experienced. However, since HKDF-SHA1-128 is specified as + mandatory to implement in Section 7.5, 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 SHOULD + discard the Map-Reply and send, at the first opportunity it needs to, + 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. + + 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 5.9.1. + + The ITR SHOULD send SMR triggered Map-Requests over the mapping + system in order to receive a secure Map-Reply. If an ITR accepts + piggybacked Map-Replies, it SHOULD also send a Map-Request over the + mapping system in order to verify the piggybacked Map-Reply with a + secure Map-Reply. + +5.9.1. 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 MUST be taken and the + Map-Reply MUST NOT be processed any further. 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. + + 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. + + 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. 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. + 6. Security Considerations 6.1. Mapping System Security The LISP-SEC threat model described in Section 3, assumes that the LISP Mapping System is working properly and eventually 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 @@ -853,38 +1030,38 @@ 7.1. 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 5.1. The registry MUST be initially populated with the following values: Name Value Defined In ------------------------------------------------- - Reserved 0 This memo + Unassigned 0 This memo LISP-SEC-ECM-EXT 1 This memo HMAC Functions Values 2-255 are unassigned. They are to be assigned according to the "Specification Required" policy defined in [RFC5226]. 7.2. 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 5.2. The registry MUST be initially populated with the following values: Name Value Defined In ------------------------------------------------- - Reserved 0 This memo + Unassigned 0 This memo LISP-SEC-MR-EXT 1 This memo HMAC Functions Values 2-255 are unassigned. They are to be assigned according to the "Specification Required" policy defined in [RFC5226]. 7.3. HMAC Functions IANA is requested to create the "LISP-SEC Authentication Data HMAC @@ -904,32 +1081,33 @@ AUTH-HMAC-SHA-1-96 MUST be supported, AUTH-HMAC-SHA-256-128 SHOULD be supported. 7.4. 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: - Name Number Defined In - ------------------------------------------------- - Reserved 0 This memo - NULL-KEY-WRAP-128 1 This memo - AES-KEY-WRAP-128 2 [RFC3394] + Name Number KEY WRAP KDF + ----------------------------------------------------------------- + Unassigned 0 None None + NULL-KEY-WRAP-128 1 This memo None + AES-KEY-WRAP-128+HKDF-SHA256 2 [RFC3394] [RFC4868] Key Wrap Functions Values 3-65535 are unassigned. They are to be assigned according to the "Specification Required" policy defined in [RFC5226]. - NULL-KEY-WRAP-128, and AES-KEY-WRAP-128 MUST be supported. + NULL-KEY-WRAP-128, and AES-KEY-WRAP-128+HKDF-SHA256 MUST be + supported. NULL-KEY-WRAP-128 is used to carry an unencrypted 128-bit OTK, with a 64-bit preamble set to 0x0000000000000000 (64 bits). 7.5. 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 in the LISP-SEC Authentication Data: @@ -945,99 +1123,110 @@ HKDF-SHA1-128 MUST be supported 8. Acknowledgements The authors would like to acknowledge 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. -9. Normative References +9. References - [I-D.ietf-lisp-rfc6830bis] - Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A. - Cabellos-Aparicio, "The Locator/ID Separation Protocol - (LISP)", draft-ietf-lisp-rfc6830bis-26 (work in progress), - November 2018. +9.1. Normative References [I-D.ietf-lisp-rfc6833bis] Fuller, V., Farinacci, D., and A. Cabellos-Aparicio, "Locator/ID Separation Protocol (LISP) Control-Plane", - draft-ietf-lisp-rfc6833bis-22 (work in progress), November - 2018. + draft-ietf-lisp-rfc6833bis-24 (work in progress), February + 2019. [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- Hashing for Message Authentication", RFC 2104, DOI 10.17487/RFC2104, February 1997, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC3394] Schaad, J. and R. Housley, "Advanced Encryption Standard (AES) Key Wrap Algorithm", RFC 3394, DOI 10.17487/RFC3394, September 2002, . [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, "Randomness Requirements for Security", BCP 106, RFC 4086, DOI 10.17487/RFC4086, June 2005, . + [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, . + [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", RFC 5226, DOI 10.17487/RFC5226, May 2008, . [RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)", RFC 5869, DOI 10.17487/RFC5869, May 2010, . - [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, . - [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, January 2012, . [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, . [RFC7835] Saucez, D., Iannone, L., and O. Bonaventure, "Locator/ID Separation Protocol (LISP) Threat Analysis", RFC 7835, DOI 10.17487/RFC7835, April 2016, . + [RFC8060] Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical + Address Format (LCAF)", RFC 8060, DOI 10.17487/RFC8060, + February 2017, . + + [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC + 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, + May 2017, . + +9.2. Informative References + + [I-D.ietf-lisp-rfc6830bis] + Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A. + Cabellos-Aparicio, "The Locator/ID Separation Protocol + (LISP)", draft-ietf-lisp-rfc6830bis-26 (work in progress), + November 2018. + Authors' Addresses Fabio Maino Cisco Systems 170 Tasman Drive San Jose, California 95134 USA Email: fmaino@cisco.com Vina Ermagan - Cisco Systems - 170 Tasman Drive - San Jose, California 95134 + Google + California USA - Email: vermagan@cisco.com + Email: ermagan@gmail.com Albert Cabellos Universitat Politecnica de Catalunya c/ Jordi Girona s/n Barcelona 08034 Spain Email: acabello@ac.upc.edu Damien Saucez