Routing Working Group M. Jethanandani Internet-Draft Ciena Corporation Intended status: Informational D. Zhang Expires: November 22, 2013 Huawei Technologies co., LTD. May 21, 2013 Analysis of RSVP-TE Security According to KARP Design Guide draft-mahesh-karp-rsvp-te-analysis-01.txt Abstract This document analyzes Resource reSerVation Protocol-Traffic Engineering (RSVP-TE) according to guidelines set forth in section 4.2 of KARP Design Guidelines (RFC 6518). 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 November 22, 2013. Copyright Notice Copyright (c) 2013 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. Jethanandani & Zhang Expires November 22, 2013 [Page 1] Internet-Draft RSVP-TE Analysis May 2013 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3 2. Current Assessment of RSVP-TE . . . . . . . . . . . . . . . . 4 2.1. Transport Layer . . . . . . . . . . . . . . . . . . . . . 4 2.1.1. UDP Encapsulation . . . . . . . . . . . . . . . . . . 4 2.2. Keying Mechanism . . . . . . . . . . . . . . . . . . . . 4 2.3. Message Integrity and Node Authentication . . . . . . . . 5 2.4. Replay Protection . . . . . . . . . . . . . . . . . . . . 5 2.5. Out of Order Protection . . . . . . . . . . . . . . . . . 6 2.6. Denial of Service Attack Protection . . . . . . . . . . . 6 3. Gap Analysis for RSVP-TE . . . . . . . . . . . . . . . . . . 6 4. IANA Requirements . . . . . . . . . . . . . . . . . . . . . . 7 5. Security Consideration . . . . . . . . . . . . . . . . . . . 7 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 7.1. Normative References . . . . . . . . . . . . . . . . . . 7 7.2. Informative References . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction In March 2006, the Internet Architecture Board (IAB) described an attack on core routing infrastructure as an ideal attack that would inflict the greatest amount of damage, in their Report from the IAB workshop on Unwanted Traffic March 9-10, 2006 [RFC4948], and suggested steps to tighten the infrastructure against the attack. Four main steps were identified for that tightening: 1. Create secure mechanisms and practices for operating routers. 2. Clean up the Internet Routing Registry (IRR) repository, and securing both the database and the access, so that it can be used for routing verifications. 3. Create specifications for cryptographic validation of routing message content. 4. Secure the routing protocols' packets on the wire. In order to secure the routing protocols this document performs an initial analysis of the current state of RSVP-TE according to the requirements of KARP Design Guidelines [RFC6518]. This draft builds on several previous analysis efforts into routing security: Jethanandani & Zhang Expires November 22, 2013 [Page 2] Internet-Draft RSVP-TE Analysis May 2013 o Issues with existing Cryptographic Protection Methods for Routing Protocols [RFC6039] an analysis of cryptographic issues with routing protocols. o Analysis of OSPF Security According to KARP Design Guide [RFC6863]. o Analysis of BGP, LDP, PCEP, and MSDP Issues According to KARP Design Guide [I-D.ietf-karp-routing-tcp-analysis] which is a analysis of the four routing protocols. Resource reSerVation Protocol (RSVP) [RFC2205] is a resource reservation setup protocol designed for an integrated services. RSVP Security Properties [RFC4230] indicates the unfeasibility of using IPSec to secure RSVP signaling messages. RSVP Cryptographic Authentication [RFC2747] describes the format and use of RSVP's INTEGRITY objects to provide hop-by-hop integrity and authentication of RSVP messages. RSVP-TE: Extensions to RSVP for LSP Tunnels [RFC3209] is an extension of the RSVP protocol to establish Multi- Protocol Label Switching (MPLS) Label Switch Paths (LSPs). RSVP-TE signaling messages are used to establish both intra- and inter-domain TE LSPs. The security mechanisms for RSVP, RSVP Cryptographic Authentication [RFC2747] can be used by RSVP-TE to provide the security protection for the RSVP-TE message transportation. Therefore, the rest of the document will focus on the current state of security efforts for RSVP and assume that will apply to RSVP-TE also. Section 2 looks at the current security state of RSVP-TE. Section 3 does an analysis of the gap between the existing and the optimal security state of the protocol and suggest some areas where we need to improve. 1.1. Abbreviations BGP - Border Gateway Protocol DoS - Denial of Service KARP - Key and Authentication for Routing Protocols KDF - Key Derivation Function KEK - Key Encrypting Key KMP - Key Management Protocol LDP - Label Distribution Protocol Jethanandani & Zhang Expires November 22, 2013 [Page 3] Internet-Draft RSVP-TE Analysis May 2013 LSP - Label Switch Path MAC - Message Authentication Code MKT - Master Key Tuple MPLS - Multi Protocol Label Switching MSDP - Multicast Source Distribution Protocol MD5 - Message Digest algorithm 5 PCEP - Path Computation Element Protocol RSVP - Resource reSerVation Protocol TCP - Transmission Control Protocol UDP - User Datagram Protocol 2. Current Assessment of RSVP-TE This section looks at RSVP-TE and the underlying transport protocol and key mechanisms built for the protocol. 2.1. Transport Layer RSVP operates on top of IPv4 or IPv6, occupying the place of a transport protocol in the protocol stack. However, RSVP does not transport application data but is rather an Internet control protocol, like ICMP, IGMP, or routing protocols. 2.1.1. UDP Encapsulation An RSVP implementation generally requires the ability to perform "raw" network I/O. However, some systems may not support raw network I/O. To use RSVP, such hosts must encapsulate RSVP messages in UDP. 2.2. Keying Mechanism Section 7 of RSVP Cryptographic Authentication discusses the possibility of using Kerberos to generate and distribute RSVP authentication keys. However, the design of Automated Key Management (AKM) mechanism for RSVP is still incomplete. There is no other AKM solution proposed at this time. If anything, manual key management is used. Jethanandani & Zhang Expires November 22, 2013 [Page 4] Internet-Draft RSVP-TE Analysis May 2013 The protocol states that manual keying should be supported and states the need for a key management protocol to distribute keys. It even states that the Key Identifier be the hook between RSVP and the key management protocol. But it deliberately excludes defining a integrated key management protocol technique in the document. It does define a key lifetime that should be recorded for all systems although how they are presented e.g. using the start time and the end time of the key life period, is not specified. It even advises that the keys should be changed on a regular basis and that multiple keys should be used to transition from one key to another. 2.3. Message Integrity and Node Authentication RSVP-TE makes use of RSVP Cryptographic Authentication [RFC2747]. Note that there is currently no RSVP-TE specific security mechanism. It is required that RSVP-TE headers and payload be authenticated, but there is no requirement that RSVP-TE headers be encrypted. RSVP Cryptographic Authentication [RFC2747] defines the use HMAC-MD5 for both message integrity and node authentication. The length of the keyed digests is 128 bits. In these cases RSVP checksum can be disabled in lieu of message digest. In addition, no algorithm agility is supported. 2.4. Replay Protection RSVP uses 64 bit monotonically increasing sequence numbers to prevent against replay attacks. The sequence number space is large enough to guarantee that a sequence number will never reach its maximum and roll back within a reasonable long period. The solution provides three approaches to generate unique monotonically increasing sequence numbers across a failure or a restart. The solutions include: 1. Maintaining sequence numbers in stable memory 2. Introducing the data from a local time clock into the generation of sequence numbers after a restart 3. Introducing the timing information from a Network Recovered Clock into the generation of sequence numbers after a restart. In addition, a handshake is defined for a receiver to get the latest value of a sequence number. Therefore, this solution is effective in addressing the issues caused by the rollback of sequence numbers across a system restart or failure. However, when a router uses the approach to generating sequence numbers with the time information Jethanandani & Zhang Expires November 22, 2013 [Page 5] Internet-Draft RSVP-TE Analysis May 2013 from NTP, an attacker may try to deceive the router to generate a sequence number which is less than the sequence numbers it used to have, by sending replayed or foiled NTP information. 2.5. Out of Order Protection To address the issue of out-of-order message delivery, the solution proposed in RSVP Cryptographic Authentication [RFC2747] allows administrators to specify a sequence number window corresponding to the worst case reordering behavior. Instead of requiring the sequence number of an incoming packet to be strictly larger than the ones previously received, a packet will be accepted if its sequence number is within the window. 2.6. Denial of Service Attack Protection RSVP does not explicitly mention Denial of Service (DoS) attacks and how to prevent against it. However, a RSVP-TE node does know the peers that it should be communicating with and can therefore accept packets from known hosts only. This feature can largely mitigate the security risks caused by DoS attacks. 3. Gap Analysis for RSVP-TE This section outlines the differences between the current state of RSVP-TE and the desired state as outlined in sections 4.1 and 4.2 of KARP Design Guidelines [RFC6518]. In RSVP Cryptographic Authentication [RFC2747], only the usage of MD5 to generate digests for RSVP-TE messages is defined. In order to fulfill the requirement of supporting strong algorithms and cryptographic algorithm agility, at least the support of SHA-2 and the ability to indicate additional algorithms needs to be provided.. In addition, in RSVP Cryptographic Authentication [RFC2747], three approaches to generating unique monotonically increasing sequence numbers across a failure and restart are introduced, but no approach is mandated. However, as mentioned above, when using Network Recovered Clocks into the generation of sequence numbers, the capability of RSVP-TE in tolerating inter-connection replay attacks will largely rely on the security of network timing protocols. Therefore, in future this approach should not be recommended. Jethanandani & Zhang Expires November 22, 2013 [Page 6] Internet-Draft RSVP-TE Analysis May 2013 4. IANA Requirements This document makes no IANA requests, and the RFC Editor may consider deleting this section on publication of this document as a RFC. 5. Security Consideration This document is all about security considerations for RSVP-TE. 6. Acknowledgements The authors would like to thank Sean Turner for his review and comments on the draft. 7. References 7.1. Normative References [RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S. Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, September 1997. [RFC2385] Heffernan, A., "Protection of BGP Sessions via the TCP MD5 Signature Option", RFC 2385, August 1998. [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, December 2001. [RFC5926] Lebovitz, G. and E. Rescorla, "Cryptographic Algorithms for the TCP Authentication Option (TCP-AO)", RFC 5926, June 2010. [RFC6518] Lebovitz, G. and M. Bhatia, "Keying and Authentication for Routing Protocols (KARP) Design Guidelines", RFC 6518, February 2012. 7.2. Informative References [I-D.ietf-karp-routing-tcp-analysis] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of BGP, LDP, PCEP and MSDP Issues According to KARP Design Guide", draft-ietf-karp-routing-tcp-analysis-07 (work in progress), April 2013. [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- Hashing for Message Authentication", RFC 2104, February 1997. Jethanandani & Zhang Expires November 22, 2013 [Page 7] Internet-Draft RSVP-TE Analysis May 2013 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2409] Harkins, D. and D. Carrel, "The Internet Key Exchange (IKE)", RFC 2409, November 1998. [RFC2747] Baker, F., Lindell, B., and M. Talwar, "RSVP Cryptographic Authentication", RFC 2747, January 2000. [RFC3547] Baugher, M., Weis, B., Hardjono, T., and H. Harney, "The Group Domain of Interpretation", RFC 3547, July 2003. [RFC4230] Tschofenig, H. and R. Graveman, "RSVP Security Properties", RFC 4230, December 2005. [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006. [RFC4948] Andersson, L., Davies, E., and L. Zhang, "Report from the IAB workshop on Unwanted Traffic March 9-10, 2006", RFC 4948, August 2007. [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP Specification", RFC 5036, October 2007. [RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., and C. Pignataro, "The Generalized TTL Security Mechanism (GTSM)", RFC 5082, October 2007. [RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, March 2009. [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP Authentication Option", RFC 5925, June 2010. [RFC5961] Ramaiah, A., Stewart, R., and M. Dalal, "Improving TCP's Robustness to Blind In-Window Attacks", RFC 5961, August 2010. [RFC6039] Manral, V., Bhatia, M., Jaeggli, J., and R. White, "Issues with Existing Cryptographic Protection Methods for Routing Protocols", RFC 6039, October 2010. [RFC6862] Lebovitz, G., Bhatia, M., and B. Weis, "Keying and Authentication for Routing Protocols (KARP) Overview, Threats, and Requirements", RFC 6862, March 2013. Jethanandani & Zhang Expires November 22, 2013 [Page 8] Internet-Draft RSVP-TE Analysis May 2013 [RFC6863] Hartman, S. and D. Zhang, "Analysis of OSPF Security According to the Keying and Authentication for Routing Protocols (KARP) Design Guide", RFC 6863, March 2013. Authors' Addresses Mahesh Jethanandani Ciena Corporation 1741 Technology Drive San Jose, CA 95110 USA Phone: +1 (408) 436-3313 Email: mjethanandani@gmail.com Dacheng Zhang Huawei Technologies co., LTD. Beijing China Email: zhangdacheng@huawei.com Jethanandani & Zhang Expires November 22, 2013 [Page 9]