Internet DRAFT - draft-bajko-mext-sod
draft-bajko-mext-sod
Individual Submission G. Bajko
Internet-Draft B. Patil
Intended status: Standards Track T. Savolainen
Expires: May 4, 2012 Nokia
November 1, 2011
Security on Demand for Mobile IPv6 and Dual-stack Mobile IPv6
draft-bajko-mext-sod-03
Abstract
Mobile IPv6 and Dual-stack Mobile IPv6 protocols require the
signaling messages between the mobile node and home agent to be
secured. However security for the user plane/traffic is optional and
is a choice left to the mobile node. This document proposes
extensions to Mobile IPv6 signaling which enables the user plane
traffic to be secured on a need or on-demand basis. The mobile node
or the home agent can request at any time security for the user plane
traffic. Security for user plane traffic can be triggered as a
result of policy or, mobility or, at the user's choice.
Status of this Memo
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This Internet-Draft will expire on May 4, 2012.
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Copyright (c) 2011 IETF Trust and the persons identified as the
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. When to apply Security to user plane traffic . . . . . . . . . 4
3. Triggering user plane traffic security . . . . . . . . . . . . 4
4. Extensions to Mobile IPv6 . . . . . . . . . . . . . . . . . . . 5
4.1. Extensions to Binding Update and Binding
Acknowledgement . . . . . . . . . . . . . . . . . . . . . . 5
4.2. New binding Update Mobility Options . . . . . . . . . . . . 6
5. HA initiated security for user plane traffic . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
8. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
10.1. Informative References . . . . . . . . . . . . . . . . . . 7
10.2. Normative References . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
Mobile IPv6 [RFC6275] and Dual-stack Mobile IPv6 [RFC5555] 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 protocols. The MEXT WG is evaluating on an experimental basis
various alternatives to IPsec such as the one specified in
[I-D.ietf-mext-mip6-tls].
As per the current specifications for MIP6 and DSMIP6, security of
the user plane traffic is optional. When the MN is attached to 3G/4G
network 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
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.
As per the current MIP6 [RFC6275] specification, only the MN has the
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ability to enable security for user-plane traffic. The HA has no
ability to force the MN to secure user traffic.
2. When to apply Security to user plane traffic
An MN MUST have security for the control plane messages. Hence all
signaling between the MN and HA are secured. The MN establishes an
IPsec SA between itself and the assigned HA prior to sending a
Binding Update. However, the MN is not required to establish an SA
for securing the user plane traffic. It is up to the MN whether it
establishes SAs for the control plane and user plane at the same time
or if it only establishes the control plane SA. The MN may choose to
establish the SA for user plane traffic at any time [RFC4877].
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
This document proposes extensions to MIPv6/DSMIPv6 protocol, allowing
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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.
A new mobility option called as the "Security-on-demand" (SoD) is
specified which is used to switch on or off the security for the user
plane traffic.
The MN sends a binding update which includes the "Security-on-demand"
mobility option set which is used to indicate whether security for
the user plane traffic is to be switched On or Off. The HA processes
the binding update message from the MN and sends a response
acknowledging the request and including the "SoD" option for user
plane traffic security.
The HA MAY always overwrite the MN's security preference on the user
plane traffic indicated in the Binding Update message, by setting the
SoD option in the 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.
4. Extensions to Mobile IPv6
4.1. Extensions to Binding Update and Binding Acknowledgement
This section defines the new Security-on-demand mobility option for
the Binding Update and the corresponding Binding Acknowledgement
message.
The security-on-demand mobility option has an alignment requirement
of 2n. Its format is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = | Length = |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SoD option | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Security on demand mobility option
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Type = TBD (To be assigned by IANA)
Length = 4
SoD Option = This option field defines whether security is enabled
or disabled as well as whether security is integrity protected or
encrypted
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 ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: MN location
Type: tbd
N set to 1 indicates that the data contains a location in XML format
as defined in RFC5139, N set to zero indicates that the data part
contains an http URI pointing to a resource where the MN uploaded its
location
5. HA initiated security for user plane traffic
Mobile IPv6 signaling is primarily mobile initiated. The security
for user plane traffic can be requested by the MN via the Binding
Update request message and the HA has the ability to either approve
or deny via the Binding Acknowledgment message. However the HA does
not have a way to send an insolicited message to the MN and trigger
the establishment of security for the user plane traffic.
Mobile IPv6 defines Binding Revocation [RFC5846] which enables an HA
to send an unsolicited message to the MN to revoke a binding. This
is the only unsolicited signaling message that can be sent by HA to
an MN. This I-D proposes extending the binding revocation message to
indicate to the MN that security for the user plane traffic is
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required. The effect of sending the binding revocation message to
the MN with the appropriate option included in it will cause the MN
to send a Binding update with the SoD mobility option requesting
security for user plane traffic.
6. IANA Considerations
This document will require actions on the part of IANA to assign
values for the new binding update mobility option.
7. Security Considerations
This I-D introduces extensions to Mobile IPv6 signaling messages.
There is no impact to the security model and architecture that is
currently specified for MIP6 [RFC6275]. The extensions specified in
this document do not introduce any new vulnerabilities of threats to
the security architecture of Mobile IPv6.
8. Summary
Security for the user plane traffic between the MN and Home agent can
be switched on or off as a result of policy, location or, request by
the user. The ability to control and trigger the security for the
user plane traffic rests with the MN as well as the HA with the HA
having the final say.
9. Acknowledgments
The authors acknowledge the reviews by Julien Laganier, Jouni
Korhonen, Stefano Faccin and Kent Leung. Their comments and
suggestions will be incorporated in the next revision.
10. References
10.1. Informative References
[23.402] 3rd generation partnership project (3GPP), "3GPP TS
23.402, Architecture enhancements for non-3GPP
accesses,".
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10.2. Normative References
[I-D.ietf-mext-mip6-tls]
Korhonen, J., Patil, B., Tschofenig, H., and D.
Kroeselberg, "Transport Layer Security-based Mobile IPv6
Security Framework for Mobile Node to Home Agent
Communication", draft-ietf-mext-mip6-tls-02 (work in
progress), October 2011.
[RFC4877] Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with
IKEv2 and the Revised IPsec Architecture", RFC 4877,
April 2007.
[RFC5555] Soliman, H., "Mobile IPv6 Support for Dual Stack Hosts and
Routers", RFC 5555, June 2009.
[RFC5846] Muhanna, A., Khalil, M., Gundavelli, S., Chowdhury, K.,
and P. Yegani, "Binding Revocation for IPv6 Mobility",
RFC 5846, June 2010.
[RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
in IPv6", RFC 6275, July 2011.
Authors' Addresses
Gabor Bajko
Nokia
200 S Mathilda Avenue
Sunnyvale, CA 94086
USA
Email: gabor.bajko@nokia.com
Basavaraj Patil
Nokia
6021 Connection drive
Irving, TX 75039
USA
Email: basavaraj.patil@nokia.com
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Teemu Savolainen
Nokia
Hermainkatu 12 D
Tampere, FI 33720
Finland
Email: teemu.savolainen@nokia.com
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