Internet DRAFT - draft-liu-nasr-requirements

draft-liu-nasr-requirements







Network Working Group                                             C. Liu
Internet-Draft                                                L. Iannone
Intended status: Informational                                    Huawei
Expires: 4 September 2024                                       D. Lopez
                                                               A. Pastor
                                                              Telefonica
                                                                 M. Chen
                                                                   L. Su
                                                            China Mobile
                                                            3 March 2024


                     NASR Use Case and Requirements
                     draft-liu-nasr-requirements-01

Abstract

   This document describes the use cases and requirements that guide the
   specification of a Network Attestation for Secure Routing framework
   (NASR).

About This Document

   This note is to be removed before publishing as an RFC.

   The latest revision of this draft can be found at
   https://liuchunchi.github.io/draft-liu-nasr-requirements/draft-liu-
   nasr-requirements.html.  Status information for this document may be
   found at https://datatracker.ietf.org/doc/draft-liu-nasr-
   requirements/.

   Source for this draft and an issue tracker can be found at
   https://github.com/liuchunchi/draft-liu-nasr-requirements.

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
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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."



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   This Internet-Draft will expire on 4 September 2024.

Copyright Notice

   Copyright (c) 2024 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
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   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Note for NASR participants  . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Backgrounds . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     5.1.  Use Case 1: Network Path Validation . . . . . . . . . . .   4
     5.2.  Use Case 2: Verifying Path Properties . . . . . . . . . .   5
     5.3.  Use Case 3: Sensitive Data Routing  . . . . . . . . . . .   5
     5.4.  Use Case 4: Ingress Filtering . . . . . . . . . . . . . .   5
   6.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  Requirement 1: Proof-of-Transit (POT) Mechanisms  . . . .   6
       6.1.1.  Per-hop POT header extensions . . . . . . . . . . . .   6
       6.1.2.  Out-of-band POT extensions  . . . . . . . . . . . . .   7
     6.2.  Requirement 2: Attributes of a network element  . . . . .   7
     6.3.  Requirement 3: Path Attestation Procedures  . . . . . . .   8
   7.  Non-Requirements  . . . . . . . . . . . . . . . . . . . . . .   8
     7.1.  Non-Requirements 1: Proof-of-Non-Transit (PONT)
           Mechanisms  . . . . . . . . . . . . . . . . . . . . . . .   8
     7.2.  Future Requirement 2: Packet Steering and Preventive
           Mechanisms  . . . . . . . . . . . . . . . . . . . . . . .   9
   8.  Commonly Asked Questions and Answers  . . . . . . . . . . . .   9
     8.1.  Why not use static routing? . . . . . . . . . . . . . . .   9
     8.2.  Initially targeting for intra-domain or inter-domain
           scenario? . . . . . . . . . . . . . . . . . . . . . . . .   9
     8.3.  Does tunneling solve the problem? . . . . . . . . . . . .   9
     8.4.  Does all nodes on the path need to compute the POT? . . .   9
   9.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   9
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  10
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10



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   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     12.2.  Informative References . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   This document outlines the use cases and requirements that guide the
   specification of a Network Attestation for Secure Routing framework
   (NASR).

   NASR is targeted to help attest a specific network path and verify if
   actual forwarding result is compliant to the attested path and
   attributes.  The components of this network path can be any
   combination of physical devices and links, and virtual links and
   virtual network functions.  The target network path can correspond to
   a network overlay, or to an underlay supporting it, at any level in
   the applicable overlay recursion hierarchy.

1.1.  Note for NASR participants

   This document collates and synthesizes discussion outcomes of NASR
   mailing list and IETF 118 path validation side meeting.

   It is created to help 1.  Foster consensus among list members.  2.
   Orient non-list members to NASR goals and current progress

   This document may become a WG-draft but will stay as an informational
   draft.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119], [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Backgrounds

   TBA

4.  Definitions

   We summarize the terms discussed in the list.

   *  NASR: Network Attestation For Secure Routing, a proposed framework
      that mainly does the following:



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      1.  Attest to a network path

      2.  Verify actual forwarding path complies with the attested path

      3.  Prevent non-compliant forwarding (optional)

   [Details to be added]

   *  Routing Security: [RFC4593], [RFC2828]

   *  Path Validation: [I-D.liu-path-validation-problem-statement]

   *  Secure Routing: [I-D.chen-secure-routing-use-cases-00]

   *  Proof-of-Transit: [I-D.ietf-sfc-proof-of-transit-08]

   *  Trustworthy Path Routing: [I-D.voit-rats-trustworthy-path-routing]

   ...

5.  Use Cases

5.1.  Use Case 1: Network Path Validation

   Explicit routing protocols permit explicit control over the traffic
   path, in order to meet certain performance, security or compliance
   requirements.  For example, operators can use SRv6 to orchestrate a
   Service Function Chaining (SFC) path and provide packaged security
   services or compliance services.  For either of them, validating the
   actual traffic path in the forwarding plane as an auditing measure is
   needed for clients and/or authorities.  NASR can help operator to
   attest to an orchestrated path and provide verifiable forwarding
   proofs to help clients/authorities audit the service.

   SFC is used as an (possibly canon cal) example, therefor network
   elements are not limited to Service Functions, and paths are not
   limited to a SFC path.  Other devices or network functions may
   incorporate features (built-in security capabilities, roots of trust
   and attestation mechanisms, etc.) suitable to support path
   validation.











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5.2.  Use Case 2: Verifying Path Properties

   In use case 1, the orchestrated path is explicit and specific down to
   each network element.  Sometimes, clients do not need to know every
   detail of the network path.  Rather, clients will request the
   verification of a certain property within the path, such as
   trustworthiness, security level, geolocation, vendor characteristics,
   transit provider, etc. from the operator.  Using NASR, the operator
   can orchestrate this path by selecting network elements and links
   with the requested properties, attest to the path, and verifiably
   prove to clients the path properties and that the traffic did follow
   this path.

   In both this and the previous case, the order of the elements in the
   path may not be important, as the requests may be limited to a set of
   attributes for the path nodes, or the guarantee that traffic
   traversed a certain (set of) node(s).

5.3.  Use Case 3: Sensitive Data Routing

   Clients from specific industries such as finance or governments have
   very low tolerance to data leakage.  These clients require assurance
   that their data only travels on top of their selected leased line,
   MPLS VPN or SD-WAN path, and have (preferably real-time) visibility
   evidence or proof.  Some compliance requirements also prohibit
   customer data escape a specific geolocation without permission.  To
   avoid data leakage and compliance risks, some clients are willing to
   pay a premium for high data routing security guarantees.  NASR can
   detect such violations and make corrections promptly, therefore
   supporting SLAs incorporating these guarantees.

   Compared to the first and second use case, this use case also
   requires some preventive measures before a wrongful forwarding
   happens at the first place.

5.4.  Use Case 4: Ingress Filtering

   Ingress Filtering techniques help prevent source IP address spoofing
   and denial-of-service (DoS) attacks [RFC8704][RFC5635].  It works by
   validating the source IP address of a received packet by performing a
   reverse path lookup in FIB table, all the way to the source.  If the
   path does not exist, the packet is dropped.  NASR can be used to
   regularly validate the path stored in the FIB table, and tell if it
   continues to exist.  Furthermore, when uRPF is not available and
   source address cannot be trusted, NASR can offer a way to filter
   malicious traffic based on the path used to carry out such an attack
   [Yaar03].  The other usage is to check if a packet carries a valid
   trail of transit proofs.  If it does then the packet is verified.



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6.  Requirements

   Based on the main use-cases described in the previous section the
   following requirements are identified.

6.1.  Requirement 1: Proof-of-Transit (POT) Mechanisms

   All use cases requested public verifiability of packet transit
   history.  Proof-of-Transit (POT) is a proof that a packet DID transit
   certain network elements, and it can include a verification of the
   order in which those elements where transited (Ordered POT, OPoO) or
   not.  A secure POT mechanism should verifiably reflect the identity
   of the transited network elements and their relevant attributes, if
   applicable:

   *  For basic POT, there is no further attribute than the identity of
      the transited element and, optionally, its relative position/order
      within the path.  This is the goal of the POT mechanism defined in
      [I-D.ietf-sfc-proof-of-transit-08].

   *  For extended POT, different attributes can be considered from a
      list of relevant ones: trustworthiness measure, available security
      capabilities, geolocation, vendor, etc.  This needs the definition
      of the relevant attributes of a network element, which is
      discussed in Section 6.2

   According to use case 2, the granularity of POT may also differ.  POT
   can be generated and recorded on a per-hop basis, or can be merged
   into one collective summary at the path level.

   The most appropriate POT mechanism for each scenarios may differ--
   inter-domain or intra-domain, with or without a pre-attest, per-
   packet or on-demand, privacy-preserving or not, etc.

6.1.1.  Per-hop POT header extensions

   POT could be either encapsulated and passed along the original path,
   or sent out-of-band.  It depends on the different operation modes:
   who should verify the POT (other elements on the path, the end host,
   or external security operation center (SOC)), timeliness of
   verification, etc.

   When the POT is passed along the path, it should be encapsulated in
   hop-by-hop header extensions, such as IPv6 hop-by-hop options header,
   In-situ OAM hop-by-hop option etc.  Exact size and specifications of
   data fields are subject to different POT mechanisms.





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6.1.2.  Out-of-band POT extensions

   For situations requiring real-time or near-real-time verification,
   meaning some external security operation center (SOC) wishes to have
   real-time visibility of the forwarding path, out-of-band methods are
   needed to encapsulate and transmit POT.  In this way, the SOC can
   verify the POT of each packet in order to make sure the forwarding is
   correct.  For example, traffic monitoring protocols like IPFIX
   [RFC7011] or ICMP [RFC792], specific management and control
   protocols, etc.  Similarly, exact size and specifications of data
   fields are subject to different POT mechanisms.

6.2.  Requirement 2: Attributes of a network element

   The identity of a subject should be defined by the attributes (or
   claims) it owns.  Attribute-defined identity is a paradigm widely
   accepted in SCIM [RFC7643], OAuth [RFC7519], SAML [SAML2], etc.  POT
   proof should reflect the identity and associated attributes, such as
   element type, security level, security capability it has, remotely-
   attested or not, vendor, deployed geolocation, current timestamp,
   path it is on, hop index on the path etc.

   Such attributes/claims/attestation results can reuse existing
   specifications, for example [I-D.ietf-rats-eat],
   [I-D.ietf-rats-ar4si] in RATS WG.  Some existing claims that we can
   reuse:

   *  hwmodel (Hardware Model)

   *  hwversion (Hardware Version)

   *  swname (Software Name )

   *  swversion (Software Version)

   *  location (location)

   Some new claim extensions can be made:

   elemtype
   pathid
   index
   secfunctions
   vendor
   ...

   (subject to discussion, add, change)




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   NASR could work closely with RATS on the standardization of above
   attributes and means of proving them.

6.3.  Requirement 3: Path Attestation Procedures

   After a path is selected, it should be

   1.  Committed to prevent changes,

   2.  Publicized for common referencing and retrieval.

   The stored path should contain this information: unique ID (within a
   domain), all network elements on the path, and attributes of them.
   (Schemas may vary depending on scenarios)

   TBA

7.  Non-Requirements

7.1.  Non-Requirements 1: Proof-of-Non-Transit (PONT) Mechanisms

   Proof-of-Non-Transit (PONT) is a proof that a packet did NOT transit
   certain network elements.  It is, essentially, the opposite to Req. 1
   Proof-of-Transit.  Certain potential user have expressed their
   interest on PONT for compliance or security purposes.

   First of all, PONT is a non-inclusion proof, and such non-existence
   proof cannot be directly given.  Second, under certain circumstances,
   PONT can be _inferred_ from POT, especially when Ordered POT (OPOT)
   is enforced.  For example, assume devices are perfectly secure and
   their behaviors completely compliant to expectations, then POT over
   A-B-C indicates the packet did not transit X/Y/Z.  To relax the
   security assumptions, if the devices are remotely attested and such
   claim is proved by POT, then the packet _should_ only transited these
   trusted devices, assuming the RATS procedure is secure.  The
   reliability of such reasoning decreases as the security level of
   device decreases.

   NASR mailing list has agreed NOT to provide PONT mechanisms, but
   could provide some informational measures and conditions that could
   indicate PONT from POT results.  For example, under xxx constraints
   and circumstances, if traffic passed X AND Y (device or geolocation),
   then it did NOT (or with a quantifiably low probability it did not)
   pass Z.

   Since this part is research-related, NASR will work with PANRG and
   academia for counseling.




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7.2.  Future Requirement 2: Packet Steering and Preventive Mechanisms

   In the sensitive data routing use case, it is certainly necessary to
   know and verify the transit path of a packet using POT mechanisms.
   However, it might be too late to have the data already exposed to the
   insecure devices and risk leakage.  There should be packet steering
   mechanisms or other preventive measures that help traffic stay in the
   desired path.  For example, doing an egress check before sending to
   the next hop, preventing sending packet to a device with a non-
   desirable attribute.

   The mailing list and side meeting has received requests to this
   requirement, it should fall in NASR interest, but also agreed this
   may not be part of the initial scope of NASR-- it is a topic to be
   included in further stages of NASR, in case of a rechartering.

8.  Commonly Asked Questions and Answers

   (From side meeting and mailing list feedbacks, to be updated)

8.1.  Why not use static routing?

   Static routing severely limits the scalability and flexibility for
   performance optimizations and reconfigurations.  Flexible
   orchestration of paths will be prohibited.  Also, even when static
   routing is used, we still need proof of transit for compliance
   checks.

8.2.  Initially targeting for intra-domain or inter-domain scenario?

   Limited domain with some trust assumptions and controls to devices
   will be easy to start with.  Then we can go do the interdomain.

8.3.  Does tunneling solve the problem?

8.4.  Does all nodes on the path need to compute the POT?

   Whether the validation is strict or loose depends on the scenario.
   For example, in SFC use cases, we are only interested in verifying
   some important elements of interest processed the traffic.

9.  Contributors

   This document is made possible by NASR proponents, active mailing
   list members and side meeting participants.  Including but not
   limited to: Andrew Alston, Nicola Rustignoli, Michael Richardson,
   Mingxing Liu, Adnan Rashid and many others.




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   Please create *Github issues* to comment, or raise a question.
   Please create new commits and *Github Pull Requests* to propose new
   contents.

10.  Security Considerations

   This document has no further security considerations.

11.  IANA Considerations

   This document has no IANA actions.

12.  References

12.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/rfc/rfc2119>.

   [RFC7011]  Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
              "Specification of the IP Flow Information Export (IPFIX)
              Protocol for the Exchange of Flow Information", STD 77,
              RFC 7011, DOI 10.17487/RFC7011, September 2013,
              <https://www.rfc-editor.org/rfc/rfc7011>.

   [RFC7519]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
              (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
              <https://www.rfc-editor.org/rfc/rfc7519>.

   [RFC7643]  Hunt, P., Ed., Grizzle, K., Wahlstroem, E., and C.
              Mortimore, "System for Cross-domain Identity Management:
              Core Schema", RFC 7643, DOI 10.17487/RFC7643, September
              2015, <https://www.rfc-editor.org/rfc/rfc7643>.

   [RFC792]   Postel, J., "Internet Control Message Protocol", STD 5,
              RFC 792, DOI 10.17487/RFC0792, September 1981,
              <https://www.rfc-editor.org/rfc/rfc792>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

   [RFC8704]  Sriram, K., Montgomery, D., and J. Haas, "Enhanced
              Feasible-Path Unicast Reverse Path Forwarding", BCP 84,
              RFC 8704, DOI 10.17487/RFC8704, February 2020,
              <https://www.rfc-editor.org/rfc/rfc8704>.



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12.2.  Informative References

   [I-D.chen-secure-routing-use-cases-00]
              Chen, M. and L. Su, "The Use Cases for Secure Routing",
              Work in Progress, Internet-Draft, draft-chen-secure-
              routing-use-cases-00, 5 March 2023,
              <https://datatracker.ietf.org/doc/html/draft-chen-secure-
              routing-use-cases-00>.

   [I-D.ietf-rats-ar4si]
              Voit, E., Birkholz, H., Hardjono, T., Fossati, T., and V.
              Scarlata, "Attestation Results for Secure Interactions",
              Work in Progress, Internet-Draft, draft-ietf-rats-ar4si-
              05, 30 August 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-rats-
              ar4si-05>.

   [I-D.ietf-rats-eat]
              Lundblade, L., Mandyam, G., O'Donoghue, J., and C.
              Wallace, "The Entity Attestation Token (EAT)", Work in
              Progress, Internet-Draft, draft-ietf-rats-eat-25, 15
              January 2024, <https://datatracker.ietf.org/doc/html/
              draft-ietf-rats-eat-25>.

   [I-D.ietf-sfc-proof-of-transit-08]
              Brockners, F., Bhandari, S., Mizrahi, T., Dara, S., and S.
              Youell, "Proof of Transit", Work in Progress, Internet-
              Draft, draft-ietf-sfc-proof-of-transit-08, 1 November
              2020, <https://datatracker.ietf.org/doc/html/draft-ietf-
              sfc-proof-of-transit-08>.

   [I-D.liu-path-validation-problem-statement]
              Liu, P. C., Wu, Q., and L. Xia, "Path Validation Problem
              Statement, History, Gap Analysis and Use Cases", Work in
              Progress, Internet-Draft, draft-liu-path-validation-
              problem-statement-00, 23 October 2023,
              <https://datatracker.ietf.org/doc/html/draft-liu-path-
              validation-problem-statement-00>.

   [I-D.voit-rats-trustworthy-path-routing]
              Voit, E., Gaddam, C. R., Fedorkow, G., Birkholz, H., and
              M. Chen, "Trusted Path Routing", Work in Progress,
              Internet-Draft, draft-voit-rats-trustworthy-path-routing-
              09, 22 February 2024,
              <https://datatracker.ietf.org/doc/html/draft-voit-rats-
              trustworthy-path-routing-09>.





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   [RFC2828]  Shirey, R., "Internet Security Glossary", RFC 2828,
              DOI 10.17487/RFC2828, May 2000,
              <https://www.rfc-editor.org/rfc/rfc2828>.

   [RFC4593]  Barbir, A., Murphy, S., and Y. Yang, "Generic Threats to
              Routing Protocols", RFC 4593, DOI 10.17487/RFC4593,
              October 2006, <https://www.rfc-editor.org/rfc/rfc4593>.

   [RFC5635]  Kumari, W. and D. McPherson, "Remote Triggered Black Hole
              Filtering with Unicast Reverse Path Forwarding (uRPF)",
              RFC 5635, DOI 10.17487/RFC5635, August 2009,
              <https://www.rfc-editor.org/rfc/rfc5635>.

   [SAML2]    "Assertions and Protocols for the OASIS Security Assertion
              Markup Language (SAML) V2.0", March 2005,
              <https://docs.oasis-open.org/security/saml/v2.0/saml-core-
              2.0-os.pdf>.

   [Yaar03]   Yaar, A., Perrig, A., and D. Song, "Pi: a path
              identification mechanism to defend against DDoS attacks",
              IEEE Comput. Soc, Proceedings 19th International
              Conference on Data Engineering (Cat. No.03CH37405),
              DOI 10.1109/secpri.2003.1199330, May 2004,
              <https://doi.org/10.1109/secpri.2003.1199330>.

Authors' Addresses

   Chunchi Liu
   Huawei
   Email: liuchunchi@huawei.com


   Luigi Iannone
   Huawei
   Email: luigi.iannone@huawei.com


   Diego Lopez
   Telefonica
   Email: diego.r.lopez@telefonica.com


   Antonio Pastor
   Telefonica
   Email: antonio.pastorperales@telefonica.com






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   Meiling Chen
   China Mobile
   Email: chenmeiling@chinamobile.com


   Li Su
   China Mobile
   Email: suli@chinamobile.com











































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