Mext WG Gabor Bajko Internet Draft Basavaraj Patil Intended Status: Proposed Standard Teemu Savolainen Expires: August 28, 2010 Nokia February 28, 2010 Security On Demand for Mobile IPv6 and Dual-stack Mobile IPv6 draft-bajko-mext-sod-00.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on DATE. Copyright Notice Copyright (c) 2010 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. Abstract The Mobile IPv6 and Dual-stack Mobile IPv6 protocols only provide a means to secure the user plane traffic but do not provide any mechanisms by which the security is triggered as a result of mobility or the MN attaching via different access networks. Bajko Expires August 28, 2010 [Page 1] Security On Demand Feb 28, 2010 This document proposes extensions to Mobile IPv6 and Dual-stack Mobile IPv6 protocols, allowing the Mobile Node to signal to the Home Agent its preference for user plane traffic security, and for the Home Agent to override that preference based on policy settings. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119. Terminology and abbreviations used in this document HSPA LTE Table of Content 1. Introduction Mobile IPv6 [MIP6] and Dual-stack Mobile IPv6 [DSMIP6] provide the option to secure the user plane data between the Mobile Node (MN) and and the Home Agent (HA) when needed. The user plane traffic between the MN and HA is secured via an IPsec security association (SA) which is established between them specifically for the purpose of user plane data. IPsec is used for securing the user plane traffic when the security between the MN and HA is based on IPsec. However security between the MN and HA could also be enabled via other means such as the use of TLS and keys that are exchanged. This alternative security solution is now being proposed in the IETF and details of this are in [draft-korhonen]. As per the current specifications for MIP6 and DSMIP6, security of the user plane traffic is optional. When the MN is attached to networks such as HSPA, LTE or EV-DO, the MN may not require security for the user plane traffic since these networks already provide ciphering over the air-interface and deploy hop-by-hop security, which makes these networks secure. However the MN may attach to less secure or unsecured accesses such as wireless lan (WLAN) or it may roam in countries where the user may prefer the data between the MN and the HA to be encrypted (even when using cellular accesses). There is no solution in the protocol specification today which provides the capability to trigger the security for the user plane traffic on a need basis. The problem that is being addressed is the triggering of security for user plane traffic between the MN and HA on a need basis. Policy information at the MN or information provided to the MN via other means at the time of attachment may assist the MN to determine if Bajko Expires August 28, 2010 [Page 2] Security On Demand Feb 28, 2010 security needs to be enabled for user plane traffic. The user may also consciously decide to enable security when attached to certain networks. Furthermore, the operator of HA may have policies that define when user plane security is to be used. This document describes a mechanism which can enable security for user plane traffic on-demand or need. An obvious implementation alternative would be to encrypt user plane traffic always (as is commonly done with VPN use-cases), but that would unnecessarily consume resources on the HA. For the HA operator there is clear economic incentive to encrypt user-plane data only when necessary. The MIP6/DSMIP6 protocols only provide a means to secure the user plane traffic but do not provide any mechanisms by which the security is triggered as a result of mobility or the MN attaching via different access networks. 2. When to apply Security to user plane traffic When the MN attaches to an access network, it is usually able to determine if the access network is viewed as trusted or untrusted. The MN can make this determination, for example, based on the PLMN ID of the cellular network; or wifi_SSID/MAC_address of a wifi network; or location information provided by the MN, or user input. The MN has either a stored policy about trusted and untrusted access networks or it may be provided with such information from policy stores such as the ANDSF [23.402] or AAA server at the time of network attachment. An interface exists generally between the policy store such as AAA or ANDSF and the Home Agent (HA). If the MN is attached to an access network which is viewed as trusted or where encryption is not allowed, the MN chooses not to secure the user plane traffic. If the MN is attached to an access network which is not trusted, the MN may want to secure its user plane traffic. The HA may also be able to determine from the source address of the binding update (BU) message the access network to which the MN is currently attached. Based on this information, the HA may require that the user plane traffic be encrypted on the MN-HA link. The MN or HA can determine when to use security for the user plane traffic using static policies or dynamic policies which can be obtained at the time of network attachment - or e.g. which are provisioned and maintained on a smartcard (eg, a UICC or SIM). 3GPP policy stores such as the ANDSF can also provide information about the access networks to which an MN is attached. Location of the MN can also be used as input. 3. Triggering user plane traffic security Bajko Expires August 28, 2010 [Page 3] Security On Demand Feb 28, 2010 This document proposes extensions to MIPv6/DSMIPv6 protocol, allowing the MN to signal to the HA its preference for user plane traffic security, and for the HA to override that preference based on the policy settings. One of the reserved bits of the Binding Update [RFC3775] message is defined to be the 'Security' flag "S", and one of the reserved bits of the Binding Acknowledgement [RFC3775] message is also defined to be the 'Security' flag "S". The MN sends a binding update with the "S" flag set to 0, when indicating that the user plane traffic will not be encrypted. The HA processes the binding update message from the MN and sends a response acknowledging the request and setting the flag for user plane traffic security to Null indicating to the MN that the traffic on the link between the MN and HA will not be encrypted. The MN sends a binding update with the "S" flag set to 1, when indicating that prefers the user plane traffic be encrypted. The HA processes the binding update message from the MN and sends a response acknowledging the request and setting the flag for user plane traffic security to 1, indicating to the MN that the traffic on the link between the MN and HA will be encrypted. The HA MAY always overwrite the MN's security preference on the user plane traffic indicated in the Binding Update message, by setting the "S" flag in the Binding Acknowledgement to a different value. The MN SHALL always follow the indication in the Binding Acknowledgement to set the security of the MN to HA user plane traffic. Bajko Expires August 28, 2010 [Page 4] Security On Demand Feb 28, 2010 4. Extensions to Mobile IPv6 4.1 Extensions to Binding Update and Binding Acknowledgement This section defines the new "S" flag for the Binding Update and the corresponding Binding Acknowledgement message: 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence # | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |A|H|L|K|M|R|P|F|S| Reserved | Lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . . Mobility options . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ S When set, this flag indicates MN prefers to turn on user plane traffic encryption. When clear, MN prefers not to use security for user plane data. The corresponding Binding Acknowledgement Message looks as follows: 0 1 2 3 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Status |K|S| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence # | Lifetime | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . . . Mobility options . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ S When set, this flag indicates HA acknowledges, or strongly recommends, use of user plane encryption. When clear, HA does not support or allow use of user plane encryption. Bajko Expires August 28, 2010 [Page 5] Security On Demand Feb 28, 2010 4.2 New binding Update Mobility Options A new mobility Options for carrying location of the MN is defined to be used in a Binding Update message with the following format: 0 1 2 3 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 | Length |N| Reserved | Data ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Data ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type: tbd. N set to 1 indicates that the data contains a location in XML format as defined in RFC5429, N set to zero indicates that the data part contains an http URI pointing to a resource where the MN uploaded its location 5. IANA considerations 6. Security considerations TBD. 7. Normative References 8. Informative References [draft-korhonen] http://www.ietf.org/id/draft-korhonen-mext-mip6- altsec-01.txt, work in progress [23.402] 3GPP TS 23.402, Architecture enhancements for non-3GPP accesses, http://www.3gpp.org/ftp/Specs/latest/Rel- 9/23_series/23402-930.zip 8. Author's Addresses Gabor Bajko gabor(dot)bajko(at)nokia(dot)com Basavaraj Patil Nokia 6021 Connection drive Irving, TX 75019 USA Email: basavaraj.patil@nokia.com Bajko Expires August 28, 2010 [Page 6] Security On Demand Feb 28, 2010 Teemu Savolainen Nokia Hermiankatu 12 D TAMPERE, FI-33720 FINLAND Email: teemu.savolainen@nokia.com Bajko Expires August 28, 2010 [Page 7]