PCE working group D. Lopez
Internet-Draft Telefonica I+D
Updates: 5088,5089 (if approved) Q. Wu
Intended status: Standards Track D. Dhody
Expires: April 24, 2021 Q. Ma
Huawei
D. King
Old Dog Consulting
October 21, 2020
IGP extension for PCEP security capability support in the PCE discovery
draft-ietf-lsr-pce-discovery-security-support-04
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 April 24, 2021.
Copyright Notice
Copyright (c) 2020 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.
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>.
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[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>.
[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>.
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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
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
101 Software Avenue, Yuhua 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
Qiufang Ma
Huawei
101 Software Avenue, Yuhua District
Nanjing, Jiangsu 210012
China
Email: maqiufang1@huawei.com
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Daniel King
Old Dog Consulting
UK
Email: daniel@olddog.co.uk
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