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Versions: (draft-wu-lsr-pce-discovery-security-support) 00 01 02 03

PCE working group                                               D. Lopez
Internet-Draft                                            Telefonica I+D
Updates: 5088,5089 (if approved)                                   Q. Wu
Intended status: Standards Track                                D. Dhody
Expires: May 2, 2020                                             Z. Wang
                                                                  Huawei
                                                                 D. King
                                                      Old Dog Consulting
                                                        October 30, 2019


IGP extension for PCEP security capability support in the PCE discovery
            draft-ietf-lsr-pce-discovery-security-support-03

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 proposes new capability flag bits for PCE-CAP-FLAGS
   sub-TLV that can be announced as 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.

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 May 2, 2020.

Copyright Notice

   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
   (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.

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.

   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 begin 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 proposes new 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



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   established and the PCEP Open messages are exchanged, thus the use of
   the PCE discovery and capabilities advertisement in the IGP needs to
   be used.

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 new capability flag bits in the OSPF PCE Capability Flags
   to indicate TCP Authentication Option (TCP-AO) support
   [RFC5925][RFC5926], PCEP over TLS support [RFC8253] respectively.

   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 Flag") 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.

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

   o  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 looking for connecting with 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



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   this PCE.  If the client is looking for connecting with 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 format of the KEY-ID sub-TLV is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+
      |           Type = 6            |         Length = 4            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    KeyID      |                 Reserved                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                           KEY-ID sub-TLV format

   Type: 6

   Length: 4

   KeyID: The one octed 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



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   Information LSA when the capability flag bit of PCE-CAP-FLAGS sub-TLV
   in OSPF is set to indicate TCP-AO support.

   The format of the KEY-CHAIN-NAME sub-TLV is as follows:

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+-+-+-+-+-++-+-+-+-+-+
      |           Type = 7            |         Length                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      //                      Key Chain Name                         //
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                           KEY-CHAIN-NAME sub-TLV 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 TLV MUST be zero-padded so that the
   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 new sub-TLVs defined in this document to be carried in the
   PCED TLV of the for use 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 new sub-TLVs defined in this document to be carried in the
   PCED TLV of the for use in the Router CAPABILITY TLV.

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








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5.  Backward Compatibility Consideration

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

   An LSR that does not support the new 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 PCE security capability via IGP.

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 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 advertisement of
   the PCE security parameters, it MUST be insured that the IGP is
   protected for authentication and integrity of the PCED TLV if the
   mechanism described in this document is used.  As stated in [RFC5088]
   and [RFC5089], the IGP do not provide encryption mechanism to protect
   the privacy of the PCED TLV, if this information can make the PCEP
   session less secure then the operator should take that into
   consideration.

8.  IANA Considerations

8.1.  OSPF PCE Capability Flag

   IANA is requested to allocate new bits assignments for the OSPF
   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/ospfv2-
   parameters/ospfv2-parameters.xml#ospfv2-parameters-14.xml



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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 top-level OSPF registry, the "PCED sub-TLV type
   indicators" registry.  This registry 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]
        4             NEIG-PCE-DOMAIN         [This.I.D][RFC5088]
        6             KEY-ID                  [This.I.D]
        7             KEY-CHAIN-NAME          [This.I.D]

   This registry is also used by IS-IS PCED sub-TLV.

9.  Acknowledgments

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

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>.





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   [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>.

   [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>.

   [RFC7981]  Ginsberg, L., Previdi, S., and M. Chen, "IS-IS Extensions
              for Advertising Router Information", RFC 7981,
              DOI 10.17487/RFC7981, October 2016,
              <https://www.rfc-editor.org/info/rfc7981>.

   [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>.

   [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>.

   [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>.

10.2.  Informative References

   [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 to add capability for TCP-MD5.  Therefore by default, PCEP
   Speaker in communication supports 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



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   connecting with PCE server with other Security capability support
   (e.g., TLS support) than TCP-MD5, the client MUST check if flag bit
   in the PCE- CAP-FLAGS sub-TLV for specific capability is set (See
   section 3.1).

Authors' Addresses

   Diego R. Lopez
   Telefonica I+D
   Spain

   Email: diego.r.lopez@telefonica.com


   Qin Wu
   Huawei Technologies
   12 Mozhou East Road, Jiangning District
   Nanjing, Jiangsu  210012
   China

   Email: bill.wu@huawei.com


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

   Email: dhruv.ietf@gmail.com


   Michael Wang
   Huawei
   12 Mozhou East Road, Jiangning District
   Nanjing, Jiangsu  210012
   China

   Email: wangzitao@huawei.com


   Daniel King
   Old Dog Consulting
   UK

   Email: daniel@olddog.co.uk





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