PCE working group                                               D. Lopez
Internet-Draft                                            Telefonica I+D
Updates: 5088, 5089, 8231, 8306, 8623 (if                          Q. Wu
         approved)                                              D. Dhody
Intended status: Standards Track                                   Q. Ma
Expires: 22 February 2022                                         Huawei
                                                                 D. King
                                                      Old Dog Consulting
                                                          21 August 2021


IGP extension for PCEP security capability support in the PCE discovery
            draft-ietf-lsr-pce-discovery-security-support-09

Abstract

   When a Path Computation Element (PCE) is a Label Switching Router
   (LSR) participating in the Interior Gateway Protocol (IGP), or even a
   server participating in IGP, its presence and path computation
   capabilities can be advertised using IGP flooding.  The IGP
   extensions for PCE discovery (RFC 5088 and RFC 5089) define a method
   to advertise path computation capabilities using IGP flooding for
   OSPF and IS-IS respectively.  However these specifications lack a
   method to advertise PCEP security (e.g., Transport Layer Security
   (TLS), TCP Authentication Option (TCP-AO)) support capability.

   This document defines capability flag bits for PCE-CAP-FLAGS sub-TLV
   that can be announced as an attribute in the IGP advertisement to
   distribute PCEP security support information.  In addition, this
   document updates RFC 5088 and RFC 5089 to allow advertisement of Key
   ID or Key Chain Name Sub-TLV to support TCP-AO security capability.
   RFC 8231, RFC 8306, and RFC 8623 are also updated to reflect the
   movement of the IANA "PCE Capability Flags" registry.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."



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   This Internet-Draft will expire on 22 February 2022.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include 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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   3
   3.  IGP extension for PCEP security capability support  . . . . .   3
     3.1.  Use of PCEP security capability support for PCE
           discovery . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  KEY-ID Sub-TLV  . . . . . . . . . . . . . . . . . . . . .   4
     3.3.  KEY-CHAIN-NAME Sub-TLV  . . . . . . . . . . . . . . . . .   5
   4.  Update to RFC5088 and RFC5089 . . . . . . . . . . . . . . . .   5
   5.  Backward Compatibility Consideration  . . . . . . . . . . . .   6
   6.  Management Considerations . . . . . . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  PCE Capability Flag . . . . . . . . . . . . . . . . . . .   7
     8.2.  PCED sub-TLV Type Indicators  . . . . . . . . . . . . . .   7
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   7
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   8
     10.2.  Informative References . . . . . . . . . . . . . . . . .   9
   Appendix A.  No MD5 Capability Support  . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   As described in [RFC5440], PCEP communication privacy is one
   importance issue, as an attacker that intercepts a Path Computation
   Element (PCE) message could obtain sensitive information related to
   computed paths and resources.






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   Among the possible solutions mentioned in these documents, Transport
   Layer Security (TLS) [RFC8446] provides support for peer
   authentication, and message encryption and integrity while TCP
   Authentication Option (TCP-AO) [RFC5925] and Cryptographic Algorithms
   for TCP-AO [RFC5926] offer significantly improved security for
   applications using TCP.  As specified in section 4 of [RFC8253], in
   order for a Path Computation Client (PCC) to establish a connection
   with a PCE server using TLS or TCP-AO, PCC needs to know whether PCE
   server supports TLS or TCP-AO as a secure transport.

   [RFC5088] and [RFC5089] define a method to advertise path computation
   capabilities using IGP flooding for OSPF and IS-IS respectively.
   However these specifications lack a method to advertise PCEP security
   (e.g., TLS) support capability.

   This document defines capability flag bits for PCE-CAP-FLAGS sub-TLV
   that can be announced as attributes in the IGP advertisement to
   distribute PCEP security support information.  In addition, this
   document updates RFC5088 and RFC5089 to allow advertisement of Key ID
   or Key Chain Name Sub-TLV to support TCP-AO security capability.

   Note that the PCEP Open message exchange is another way to discover
   PCE capabilities information, but in this instance, the TCP security
   related key parameters need to be known before the PCEP session is
   established and the PCEP Open messages are exchanged.  Thus, the use
   of the PCE discovery and capabilities advertisement of the IGP needs
   to be leveraged.

2.  Conventions used in this document

   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.  IGP extension for PCEP security capability support

   [RFC5088] defines a PCE Discovery (PCED) TLV carried in an OSPF
   Router Information Link State Advertisement (LSA) as defined in
   [RFC7770] to facilitate PCE discovery using OSPF.  This document
   defines two capability flag bits in the OSPF PCE Capability Flags to
   indicate TCP Authentication Option (TCP-AO) support
   [RFC5925][RFC5926] and PCEP over TLS support [RFC8253] respectively.







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   Similarly, [RFC5089] defines the PCED sub-TLV for use in PCE
   discovery using IS-IS.  This document will use the same flag for the
   OSPF PCE Capability Flags sub-TLV to allow IS-IS to indicate TCP
   Authentication Option (TCP-AO) support, PCEP over TLS support
   respectively.

   The IANA assignments for shared OSPF and IS-IS Security Capability
   Flags are documented in Section 8.1 ("OSPF PCE Capability Flags") of
   this document.

3.1.  Use of PCEP security capability support for PCE discovery

   TCP-AO, PCEP over TLS support flag bits are advertised using IGP
   flooding.

   *  PCE supports TCP-AO: IGP advertisement SHOULD include TCP-AO
      support flag bit.

   *  PCE supports TLS: IGP advertisement SHOULD include PCEP over TLS
      support flag bit.

   If PCE supports multiple security mechanisms, it SHOULD include all
   corresponding flag bits in IGP advertisement.

   If the client is restricted to a PCE server with TCP-AO support, the
   client MUST check if TCP-AO support flag bit in the PCE- CAP-FLAGS
   sub-TLV is set.  If not, the client SHOULD NOT consider this PCE.  If
   the client is restriced to a PCE server using TLS, the client MUST
   check if PCEP over TLS support flag bit in the PCE-CAP-FLAGS sub-TLV
   is set.  If not, the client SHOULD NOT consider this PCE.  Note that
   this can be overridden based on a local policy at the PCC.

3.2.  KEY-ID Sub-TLV

   The KEY-ID sub-TLV specifies a key that can be used by the PCC to
   identify the TCP-AO key [RFC5925].

   The KEY-ID sub-TLV MAY be present in the PCED sub-TLV carried within
   the IS-IS Router Information Capability TLV when the capability flag
   bit of PCE-CAP-FLAGS sub-TLV in IS-IS is set to indicate TCP
   Authentication Option (TCP-AO) support.  Similarly, this sub-TLV MAY
   be present in the PCED TLV carried within OSPF Router Information LSA
   when the capability flag bit of PCE-CAP-FLAGS sub-TLV in OSPF is set
   to indicate TCP-AO support.

   The KEY-ID sub-TLV has the following format:

      Type: 6



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      Length: 4

      KeyID: The one octet Key ID as per [RFC5925] to uniquely identify
      the Master Key Tuple (MKT).

      Reserved: MUST be set to zero while sending and ignored on
      receipt.

3.3.  KEY-CHAIN-NAME Sub-TLV

   The KEY-CHAIN-NAME sub-TLV specifies a keychain name that can be used
   by the PCC to identify the keychain [RFC8177].

   The KEY-CHAIN-NAME sub-TLV MAY be present in the PCED sub-TLV carried
   within the IS-IS Router Information Capability TLV when the
   capability flag bit of PCE-CAP-FLAGS sub-TLV in IS-IS is set to
   indicate TCP Authentication Option (TCP-AO) support.  Similarly, this
   sub-TLV MAY be present in the PCED TLV carried within OSPF Router
   Information LSA when the capability flag bit of PCE-CAP-FLAGS sub-TLV
   in OSPF is set to indicate TCP-AO support.

   The KEY-CHAIN-NAME sub-TLV has the following format:

      Type: 7

      Length: Variable

      Key Name: The Key Chain Name contains a string to be used to
      identify the key chain.  It SHOULD be a string of printable ASCII
      characters, without a NULL terminator.  The sub-TLV MUST be zero-
      padded so that the sub-TLV is 4-octet aligned.

4.  Update to RFC5088 and RFC5089

   Section 4 of [RFC5088] states that no new sub-TLVs will be added to
   the PCED TLV, and no new PCE information will be carried in the
   Router Information LSA.  This document updates [RFC5088] by allowing
   the two sub-TLVs defined in this document to be carried in the PCED
   TLV advertised in the Router Information LSA.

   Section 4 of [RFC5089] states that no new sub-TLVs will be added to
   the PCED TLV, and no new PCE information will be carried in the
   Router CAPABLITY TLV.  This document updates [RFC5089] by allowing
   the two sub-TLVs defined in this document to be carried in the PCED
   TLV advertised in the Router CAPABILITY TLV.






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   The introduction of the additional sub-TLVs should be viewed as an
   exception to the [RFC5088][RFC5089] policy justified by the
   requirements to discover the PCEP security support prior to
   establishing a PCEP session.  The restrictions defined in
   [RFC5089][RFC5089] should still be considered to be in place.

   The registry for the PCE Capability Flags assigned in section 8.2 of
   [RFC8231], section 6.9 of [RFC8306], and section 11.1 of [RFC8623]
   has changed to the IGP Parameters "Path Computation Element (PCE)
   Capability Flags" registry created in this document.

5.  Backward Compatibility Consideration

   An LSR that does not support the IGP PCE capability bits specified in
   this document silently ignores those bits.

   An LSR that does not support the KEYNAME sub-TLV specified in this
   document silently ignores the sub-TLV.

   IGP extensions defined in this document do not introduce any new
   interoperability issues.

6.  Management Considerations

   A configuration option may be provided for advertising and
   withdrawing PCEP security capability via OSPF and IS-IS.

7.  Security Considerations

   Security considerations as specified by [RFC5088] and [RFC5089] are
   applicable to this document.

   The information related to PCEP security is sensitive and due care
   needs to be taken by the operator.  This document defines new
   capability bits that are susceptible to a downgrade attack by
   toggling them.  The content of Key ID or Key Chain Name Sub-TLV can
   be tweaked to enable a man-in-the-middle attack.  Thus before
   advertising the PCEP security parameters, using the mechanism
   described in this document, the IGP MUST be known to provide
   authentication and integrity for the PCED TLV using the mechanisms
   defined in [RFC5304], [RFC5310] or [RFC5709].

   Moreover, as stated in [RFC5088] and [RFC5089], if the IGP does not
   provide any encryption mechanisms to protect the secrecy of the PCED
   TLV, then the operator must ensure that no private data is carried in
   the TLV, e.g. that key-ids or key-chain names do not reveal sensitive
   information about the network.




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8.  IANA Considerations

8.1.  PCE Capability Flag

   IANA is requested to move the "PCE Capability Flags" registry from
   "Open Shortest Path First v2 (OSPFv2) Parameters" to under the IANA
   Common IGP parameters registry and allocate new bits assignments for
   the IGP Parameters "Path Computation Element (PCE) Capability Flags"
   registry.

        Bit           Meaning                 Reference
        xx            TCP-AO Support          [This.I.D]
        xx            PCEP over TLS support   [This.I.D]

   The registry is located at: https://www.iana.org/assignments/igp-
   parameters/igp-parameters.xhtml

8.2.  PCED sub-TLV Type Indicators

   The PCED sub-TLVs were defined in [RFC5088] and [RFC5089], but they
   did not create a registry for it.  This document requests IANA to
   create a new subregistry called "PCED sub-TLV type indicators" under
   the "Interior Gateway Protocol (IGP) Parameters" registry.  The
   registration policy for this subregistry is "IETF Review" [RFC8126].
   Values in this subregistry come from the range 0-65535.

   This subregistry should be populated with:

        Value         Description             Reference
        0             Reserved                [This.I.D][RFC5088]
        1             PCE-ADDRESS             [This.I.D][RFC5088]
        2             PATH-SCOPE              [This.I.D][RFC5088]
        3             PCE-DOMAIN              [This.I.D][RFC5088]
        5             PCE-CAP-FLAGS           [This.I.D][RFC5088]
        4             NEIG-PCE-DOMAIN         [This.I.D][RFC5088]
        6             KEY-ID                  [This.I.D]
        7             KEY-CHAIN-NAME          [This.I.D]

   This registry is located at: https://www.iana.org/assignments/igp-
   parameters/igp-parameters.xhtml and used by both OSPF PCED TLV and
   IS-IS PCED sub-TLV.

9.  Acknowledgments

   The authors of this document would also like to thank Acee Lindem,
   Julien Meuric, Les Ginsberg, Ketan Talaulikar, Yaron Sheffer, Tom
   Petch, Aijun Wang, Adrian Farrel for the review and comments.




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   The authors would also like to speical thank Michale Wang for his
   major contributions to the initial version.

10.  References

10.1.  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/info/rfc2119>.

   [RFC5088]  Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
              Zhang, "OSPF Protocol Extensions for Path Computation
              Element (PCE) Discovery", RFC 5088, DOI 10.17487/RFC5088,
              January 2008, <https://www.rfc-editor.org/info/rfc5088>.

   [RFC5089]  Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
              Zhang, "IS-IS Protocol Extensions for Path Computation
              Element (PCE) Discovery", RFC 5089, DOI 10.17487/RFC5089,
              January 2008, <https://www.rfc-editor.org/info/rfc5089>.

   [RFC5925]  Touch, J., Mankin, A., and R. Bonica, "The TCP
              Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
              June 2010, <https://www.rfc-editor.org/info/rfc5925>.

   [RFC5926]  Lebovitz, G. and E. Rescorla, "Cryptographic Algorithms
              for the TCP Authentication Option (TCP-AO)", RFC 5926,
              DOI 10.17487/RFC5926, June 2010,
              <https://www.rfc-editor.org/info/rfc5926>.

   [RFC8253]  Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
              "PCEPS: Usage of TLS to Provide a Secure Transport for the
              Path Computation Element Communication Protocol (PCEP)",
              RFC 8253, DOI 10.17487/RFC8253, October 2017,
              <https://www.rfc-editor.org/info/rfc8253>.

   [RFC8177]  Lindem, A., Ed., Qu, Y., Yeung, D., Chen, I., and J.
              Zhang, "YANG Data Model for Key Chains", RFC 8177,
              DOI 10.17487/RFC8177, June 2017,
              <https://www.rfc-editor.org/info/rfc8177>.

   [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>.






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   [RFC7770]  Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
              S. Shaffer, "Extensions to OSPF for Advertising Optional
              Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
              February 2016, <https://www.rfc-editor.org/info/rfc7770>.

   [RFC5304]  Li, T. and R. Atkinson, "IS-IS Cryptographic
              Authentication", RFC 5304, DOI 10.17487/RFC5304, October
              2008, <https://www.rfc-editor.org/info/rfc5304>.

   [RFC5310]  Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
              and M. Fanto, "IS-IS Generic Cryptographic
              Authentication", RFC 5310, DOI 10.17487/RFC5310, February
              2009, <https://www.rfc-editor.org/info/rfc5310>.

   [RFC5709]  Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M.,
              Li, T., and R. Atkinson, "OSPFv2 HMAC-SHA Cryptographic
              Authentication", RFC 5709, DOI 10.17487/RFC5709, October
              2009, <https://www.rfc-editor.org/info/rfc5709>.

   [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>.

   [RFC8231]  Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path
              Computation Element Communication Protocol (PCEP)
              Extensions for Stateful PCE", RFC 8231,
              DOI 10.17487/RFC8231, September 2017,
              <https://www.rfc-editor.org/info/rfc8231>.

   [RFC8306]  Zhao, Q., Dhody, D., Ed., Palleti, R., and D. King,
              "Extensions to the Path Computation Element Communication
              Protocol (PCEP) for Point-to-Multipoint Traffic
              Engineering Label Switched Paths", RFC 8306,
              DOI 10.17487/RFC8306, November 2017,
              <https://www.rfc-editor.org/info/rfc8306>.

   [RFC8623]  Palle, U., Dhody, D., Tanaka, Y., and V. Beeram, "Stateful
              Path Computation Element (PCE) Protocol Extensions for
              Usage with Point-to-Multipoint TE Label Switched Paths
              (LSPs)", RFC 8623, DOI 10.17487/RFC8623, June 2019,
              <https://www.rfc-editor.org/info/rfc8623>.

10.2.  Informative References







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   [RFC5440]  Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
              Element (PCE) Communication Protocol (PCEP)", RFC 5440,
              DOI 10.17487/RFC5440, March 2009,
              <https://www.rfc-editor.org/info/rfc5440>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

Appendix A.  No MD5 Capability Support

   To be compliant with Section 10.2 of RFC5440, this document doesn't
   consider adding capability for TCP-MD5.  Therefore by default, a PCEP
   Speaker supports the capability for TCP-MD5 (See section 10.2,
   [RFC5440]).  A method to advertise TCP-MD5 Capability support using
   IGP flooding is not required.  If the client is looking for a PCE
   server with other Security capability support (e.g., TLS support)
   than TCP-MD5, the client MUST check if the corresponding flag bit in
   the PCE-CAP-FLAGS sub-TLV is set (See section 3.1).  Irrespective of
   which security capability (e.g., TCP-MD5) is selected, the same key-
   ids or key-chain names on the PCC and PCE server should be
   configured.

Authors' Addresses

   Diego R. Lopez
   Telefonica I+D
   Spain

   Email: diego.r.lopez@telefonica.com


   Qin Wu
   Huawei Technologies
   101 Software Avenue, Yuhua District
   Nanjing
   Jiangsu, 210012
   China

   Email: bill.wu@huawei.com











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   Dhruv Dhody
   Huawei Technologies
   Divyashree Techno Park, Whitefield
   Bangalore 560037
   Karnataka
   India

   Email: dhruv.ietf@gmail.com


   Qiufang Ma
   Huawei
   101 Software Avenue, Yuhua District
   Nanjing
   Jiangsu, 210012
   China

   Email: maqiufang1@huawei.com


   Daniel King
   Old Dog Consulting
   United Kingdom

   Email: daniel@olddog.co.uk


























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