Geopriv J. Winterbottom Internet-Draft M. Thomson Intended status: Standards Track Andrew Corporation Expires: August 29, 2009 H. Tschofenig Nokia Siemens Networks R. Barnes BBN Technologies February 25, 2009 Use of Target Identity in HTTP-Enabled Location Delivery (HELD) draft-winterbottom-geopriv-held-identity-extensions-09 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 August 29, 2009. Copyright Notice Copyright (c) 2009 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 in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Winterbottom, et al. Expires August 29, 2009 [Page 1] Internet-Draft HELD Identity February 2009 Abstract When a Location Information Server receives a request for location information (using the locationRequest message), described in the base HTTP Enabled Location Delivery (HELD) specification, it uses the source IP address of arriving message as a pointer to the location determination process. This is sufficient in environments where a Target's location can be determined based on its IP address. Two additional use cases are addresses by this document. In the first, location configuration requires additional or alternative identifiers from the source IP address provided in the request. In the second, an entity other than the Target requests the Target's location. This document extends the HELD protocol to allow the location request message to carry Target identifiers. Privacy and security considerations describe the conditions where requests containing identifiers are permitted. Winterbottom, et al. Expires August 29, 2009 [Page 2] Internet-Draft HELD Identity February 2009 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Applications . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Target Identity . . . . . . . . . . . . . . . . . . . . . . . 5 3.1. Identifier Format and Protocol Details . . . . . . . . . . 6 3.2. Identifiers . . . . . . . . . . . . . . . . . . . . . . . 7 3.2.1. IP Address . . . . . . . . . . . . . . . . . . . . . . 7 3.2.2. MAC Address . . . . . . . . . . . . . . . . . . . . . 7 3.2.3. TCP or UDP Port Number . . . . . . . . . . . . . . . . 8 3.2.4. Network Access Identifier . . . . . . . . . . . . . . 8 3.2.5. URI . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.2.6. Hostname . . . . . . . . . . . . . . . . . . . . . . . 9 3.2.7. Directory Number . . . . . . . . . . . . . . . . . . . 9 3.2.8. Cellular Telephony Identifiers . . . . . . . . . . . . 9 3.2.9. DHCP Unique Identifier . . . . . . . . . . . . . . . . 10 4. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5. Privacy Considerations . . . . . . . . . . . . . . . . . . . . 12 6. Security Considerations . . . . . . . . . . . . . . . . . . . 13 6.1. Location Configuration Protocol Requests . . . . . . . . . 14 6.2. Third Party Requests . . . . . . . . . . . . . . . . . . . 14 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 7.1. URN Sub-Namespace Registration for urn:ietf:params:xml:ns:geopriv:held:id . . . . . . . . . . 14 7.2. XML Schema Registration . . . . . . . . . . . . . . . . . 15 7.3. Registration of HELD 'badIdentifier' Error Code . . . . . 15 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16 9.1. Normative references . . . . . . . . . . . . . . . . . . . 16 9.2. Informative references . . . . . . . . . . . . . . . . . . 17 Winterbottom, et al. Expires August 29, 2009 [Page 3] Internet-Draft HELD Identity February 2009 1. Introduction Protocols for requesting and providing location information require a way for the requestor to specify the location that should be returned. In a location configuration protocol (LCP), the location being requested is the requestor's location. This fact can make the problem of identifying the Device simpler for LCPs, since IP datagrams that carry the request already carry an identifier for the Device, namely the source IP address of an incoming request. Existing LCPs, such as HELD [I-D.ietf-geopriv-http-location-delivery] and DHCP ([RFC3825], [RFC4776]) rely on the source IP address, and possibly lower-layer identifiers to identify a Device. Aside from the datagrams that form a request, a location information server (LIS) does not necessarily have access to information that could further identify the Target. In some circumstances, as shown in [I-D.ietf-geopriv-l7-lcp-ps], additional identification information can be included in a request to identify a Target. This document extends the HELD protocol to support the inclusion of additional identifiers for the Target in HELD location requests. An XML schema is defined that provides a structure for including these identifiers in HELD requests. An important characteristic of this addition to the HELD protocol is that is also expands the potential scope of HELD beyond that of an LCP. The scope of an LCP is limited to the interaction between a Device and a LIS. That is, an LCP is limited to the Device retrieving information about their own location. With this addition, third party location recipients (LRs) are able to make requests that include identifiers to retrieve location information about a particular Target. The usage of HELD for purposes beyond the Device-LIS interaction obviously introduces a new set of privacy concerns. In an LCP, the requester is implicitly authorized to access the requested location information, because it is their own location. In contrast, when a third party LR requests a Target's location, the LR MUST be explicitly authorized. Establishing appropriate authorization and other related privacy concerns are discussed in Section 5. 1.1. Applications The use of additional identifiers in HELD falls into two categories. A Device can use these parameters to provide additional identification information to a LIS. Identification such as the hardware address of the Device can be used to reduce the time required to determine the location of the Device. In other cases, a Winterbottom, et al. Expires August 29, 2009 [Page 4] Internet-Draft HELD Identity February 2009 LIS might require Device identification before any location information can be generated. A third party LR can be granted authorization to make requests for a given Target. In particular, network services can be permitted to retrieve location for a Device that is unable to acquire location information for itself (see Section 6.3 of [I-D.ietf-ecrit-phonebcp]). This allows use of location-dependent applications--particularly essential services like emergency calling--where Devices do not support a location configuration protocol (LCP) or they are unable to successfully retrieve location information. 2. Terminology This document uses the term Location Information Server (LIS) and location configuration protocol (LCP) as described in [I-D.ietf-geopriv-l7-lcp-ps]. This document reuses the term Target to refer to the subject of any request for location information. The term Device is used specifically as the subject of an LCP, consistent with [I-D.ietf-geopriv-http-location-delivery]. Both these terms are defined in [RFC3693]. 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 [RFC2119]. 3. Target Identity Identifiers are used as the starting point in location determination. They should not be confused with measurement information ([I-D.thomson-geopriv-held-measurements]). Measurement information is information about a Device and the time varying details of its network attachment. Identifiers might be associated with a different Target over time, but the their purpose is to identify the Target, not to describe its environment or network attachment. Use of any identifier MUST only be allowed if it uniquely identifies a single Target. In some circumstances, certain of these identifiers are either temporary or could potentially identify multiple devices. Identifiers that are transient or ambiguous could be exploited by an attacker to either gain information about another device or to obtain misleading information. The identifiers described in this section SHOULD only be used where that identifier is used as the basis for location determination. It Winterbottom, et al. Expires August 29, 2009 [Page 5] Internet-Draft HELD Identity February 2009 is tempting for a LIS implementation to allow alternative identifiers for convenience or some other perceived benefit. However, care needs to be taken to ensure that the binding between the indicated identifier and the identifier that is used for location determination is unique and not subject to attacks. 3.1. Identifier Format and Protocol Details XML elements are used to express the Target identity. The "target" element is used as a general container for identity information. This document defines a basic set of identifiers. An example HELD request, shown in Figure 1, includes an IP version 4 address. geodetic 192.0.2.5 Figure 1 A LIS that supports this specification echoes the "target" element in a successful HELD response, including the identifiers that were used as the basis for location determination. Absence of this indication means that the location information was generated using the source IP address in the request. If an identifier is invalid, not supported by the LIS, or the requester is not authorized to use that identifier, a HELD error response of "badIdentifier". This code is registered in Section 7.3. If the LIS requires an identifier that is not provided in the request, the desired identifiers MAY be identified in the HELD error response, using the "requiredIdentifiers" element. This element contains a list of XML qualified names [W3C.REC-xml-names11-20060816] that identify the identifier elements required by the LIS. Namespace prefix bindings for the qualified names are taken from document context. Figure 2 shows an example error indicating that the requester needs to include a MAC address (Section 3.2.2) if the request is to succeed. Winterbottom, et al. Expires August 29, 2009 [Page 6] Internet-Draft HELD Identity February 2009 mac Figure 2 3.2. Identifiers A limited selection of identifiers are included in this document. The basic Target identity schema allows for the inclusion of elements from any namespace, therefore additional elements can be defined using different XML namespaces. 3.2.1. IP Address The "ip" element can express a Target identity as an IP address. An optional "v" attribute identifies the IP version. The element uses the textual format specific to the indicated IP version. 2001:DB8::1:ea7:fee1:d1e In situations where location configuration does not require additional identifiers, using IP address as an identifier enables third party requests. 3.2.2. MAC Address The media access control (MAC) address used by the IEEE 802 family of access technologies is an identifier that is assigned to a particular network device. A MAC address is a unique sequence that is either assigned at the time of manufacture of a device, or assigned by a local administrator. A MAC address rarely changes; therefore, a MAC address is an appropriate identifier for a Device. A0-12-34-56-78-90 Winterbottom, et al. Expires August 29, 2009 [Page 7] Internet-Draft HELD Identity February 2009 3.2.3. TCP or UDP Port Number On its own, a TCP or UDP port number is insufficient to uniquely identify a single host, but in combination with an IP address, it can be used to identify a Target. Use of a particular port number can be transient; often significantly more than use of any given IP address. However, widespread use of network address translation (NAT) means that some Targets cannot be uniquely identified by IP address alone. An individual Target might be identified by a flow of packets that it generates. Providing that a LIS has sufficient knowledge of the mappings used by the NAT, an individual target on the remote side of the NAT might be able to be identified uniquely. 2001:DB8::1:ea7:fee1:d1e 51393 As with any identifier, use of port numbers is contingent on the value remaining consistent over time. Use of port numbers is not suitable if port numbers cannot be deterministically attributed to a unique Target over a sufficient period of time. 3.2.4. Network Access Identifier A Network Access Identifier (NAI) [RFC4282] is an identifier used in network authentication in a range of networks. The identifier establishes a user identity within a particular domain. Often, network services use an NAI in relation to location records, tying network access to user authentication and authorization. user@example.net Note: The formal grammar for NAI permits invalid Unicode, which cannot be expressed using XML. This is a known problem with that grammar. Any NAI that contains invalid character sequences cannot be used as a Target identifier. 3.2.5. URI A Target can be identified by a URI. Any URI can be used providing that the requester and LIS have a common understanding of the semantics implied by use of the URI. Winterbottom, et al. Expires August 29, 2009 [Page 8] Internet-Draft HELD Identity February 2009 sip:user@example.net;gr=kjh29x97us97d 3.2.6. Hostname A domain name can be used as the basis for identification using the "hostname" element. host.example.net 3.2.7. Directory Number Telephony devices are typically identified by the number that is used to reach them. Within enterprises, where globally accessible telephone numbers might not be used, a directory number is the usual form of identification. 7515 3.2.8. Cellular Telephony Identifiers A range of different forms of mobile station identifiers are used for different cellular telephony systems. Elements are defined for these identifiers. The following identifiers are defined: msisdn: The Mobile Subscriber Integrated Services Digital Network Number (MSISDN) is an E.164 number between 6 and 15 digits long. imsi: The International Mobile Subscriber Identity (IMSI) an identifier associated with all GSM and UMTS mobile subscribers. imei: The International Mobile Equipment Identifier (IMEI) is a unique device serial number up to 15 digits long. min: The Mobile Identification Number (MIN) is a unique number assigned to CDMA handsets. mdn: The Mobile Directory Number (MDN) is an E.164 number, with usage similar to MSISDN. 11235550123 Winterbottom, et al. Expires August 29, 2009 [Page 9] Internet-Draft HELD Identity February 2009 3.2.9. DHCP Unique Identifier The Dynamic Host Configuration Protocol (DHCP) uses a binary identifier for its clients. The DHCP Unique Identifier (DUID) is expressed in Option 61 of DHCPv4 (see [RFC4361]) or Option 1 of DHCPv6 and follows the format defined in Section 9 of [RFC3315]. The "duid" element includes the binary value of the DUID expressed in hexadecimal. 1234567890AaBbCcDdEeFf 4. XML Schema Winterbottom, et al. Expires August 29, 2009 [Page 10] Internet-Draft HELD Identity February 2009 Winterbottom, et al. Expires August 29, 2009 [Page 11] Internet-Draft HELD Identity February 2009 5. Privacy Considerations A location configuration protocol has a very simple privacy model. Because the requester is also the Target, it can be assumed that providing that requester with location information is allowed. This "LCP policy" makes the simple assumption that as the subject of the location information, the Target is also permitted access to that information. In effect, an LCP server (that is, the LIS) follows a single rule policy that states that the Target is the only authorized Location Recipient. Note: HELD explicitly takes the position that the Target is a Device and not a person. For the purpose of discussion related to privacy, this distinction is not important. In this section, Target refers equally to Device and person. When Target identity is used, the "LCP policy" is only applicable if the identity of requester and Target are identical. If the authenticated identity of the requester and the Target are the same, the security and privacy considerations of the base HELD protocol [I-D.ietf-geopriv-http-location-delivery] MAY be applied by a LIS. The LIS MUST NOT use LCP policy unless it can authenticate the requester identity is the same as the requested identity. Requester and target identities MUST be identical, related identities are not sufficient. For example, it is not appropriate to apply LCP policy where a requester is authenticated by NAI and the supplied Target identity is a MAC address, even if that MAC address is currently registered Winterbottom, et al. Expires August 29, 2009 [Page 12] Internet-Draft HELD Identity February 2009 with the network under the given NAI. In this case, the requester might be requesting from a different MAC address registered under the same NAI. The correct way of gaining authorization is to establish a policy that permits this particular request as a third party request. The LCP policy does not allow requests made by third parties. If a LIS permits requests from third parties using identity extensions, it assumes the rule of a Location Server (LS). HELD becomes a more general location request protocol--a "using protocol" by the definitions in [RFC3693]--and the privacy considerations for using protocols apply. As a Location Server, the LIS MUST explicitly authorize requests according to the policies that are provided by Rule Makers, including the Target. This includes authentication of requesters where required by the authorization policies. An organization that provides a LIS that allows third party requests SHOULD provide a means for a Rule Maker to specify authorization policies before allowing third party requests for that Target's location. Until an authorization policy is established, the LIS MUST reject requests by third parties. When the LIS is operated by the Target's access network, the relationship between the Target and the LIS can be transient. However, the process of establishing network access usually results in a form of agreement between the Target and the network provider. This process offers a natural vehicle for establishing location privacy policies. Establishing authorization policy might be a manual process, an explicit part of the terms of service for the network, or an automated system that accepts formal authorization policies (see [RFC4745], [RFC4825]). This document does not mandate any particular mechanism for establishing an authorization policy. 6. Security Considerations The security considerations in [I-D.ietf-geopriv-http-location-delivery] describe the use of TLS for server authentication, confidentiality and protection from modification. These protections apply to both LCP requests and the requests made by third parties. All HELD requests MUST be authenticated by the LIS. How authentication is accomplished and what assurances are desired is a matter for policy. The base HELD protocol uses return reachability-- the proof of ownership of an IP address implied by the requester being able to successfully complete a TCP handshake. It is RECOMMENDED that any means of authentication provide at least this degree of assurance. [[MT: last sentence too subjective?]] For Winterbottom, et al. Expires August 29, 2009 [Page 13] Internet-Draft HELD Identity February 2009 requests that include Target identity, the LIS MUST support authentication of TLS clients. 6.1. Location Configuration Protocol Requests Requests made by a Device in the context of a location configuration protocol are covered by the same set of protections offered by HELD. LCP requests are authorized under an "LCP policy" that permits a Target access to location information about itself. Identity information provided by the Device is private data that might be sensitive. The Device provides this information in the expectation that it assists the LIS in providing the Device a service. The LIS MUST NOT use identity information for any other purpose other than serving the request that includes that information. 6.2. Third Party Requests Requests from third parties have the same requirements for server authentication, confidentiality and protection from modification as LCP requests. However, because the third party needs to be authorized, the requester MUST be authenticated by the LIS. In addition, third party requests MUST be explicitly authorized by a policy that is established by a Rule Maker. More detail on the privacy implications of third party requests are covered in Section 5. 7. IANA Considerations This document registers an XML namespace and schema with IANA in accordance with guidelines in [RFC3688]. It also creates a new registry for device identity types, and stipulates how new types are to be added. 7.1. URN Sub-Namespace Registration for urn:ietf:params:xml:ns:geopriv:held:id This section registers a new XML namespace, "urn:ietf:params:xml:ns:geopriv:held:id", as per the guidelines in [RFC3688]. URI: urn:ietf:params:xml:ns:geopriv:held:id Registrant Contact: IETF, GEOPRIV working group, (geopriv@ietf.org), James Winterbottom (james.winterbottom@andrew.com). Winterbottom, et al. Expires August 29, 2009 [Page 14] Internet-Draft HELD Identity February 2009 XML: BEGIN HELD Target Identity Parameters

Namespace for HELD Target Identity Parameters

urn:ietf:params:xml:ns:geopriv:held:id

[[NOTE TO IANA/RFC-EDITOR: Please update RFC URL and replace XXXX with the RFC number for this specification.]]

See RFCXXXX.

END 7.2. XML Schema Registration This section registers an XML schema as per the guidelines in [RFC3688]. URI: urn:ietf:params:xml:schema:geopriv:held:id Registrant Contact: IETF, GEOPRIV working group, (geopriv@ietf.org), James Winterbottom (james.winterbottom@andrew.com). Schema: The XML for this schema can be found as the entirety of Section 4 of this document. 7.3. Registration of HELD 'badIdentifier' Error Code This section registers the "badIdentifier" error code in the "Geopriv HELD Registries, Error codes for HELD" IANA registry. badIdentifier This error code indicates that the Target identifiers used in the HELD request were either: not supported by the LIS, badly formatted, or that the requester was not authorized to make a erquest for that identifier. 8. Acknowledgements The authors wish to thank the NENA VoIP location working group for their assistance in the definition of the schema used in this document. Special thanks go to Barbara Stark, Guy Caron, Nadine Winterbottom, et al. Expires August 29, 2009 [Page 15] Internet-Draft HELD Identity February 2009 Abbott, Jerome Grenier and Martin Dawson. Bob Sherry provided input on use of URIs. Thanks to Adam Muhlbauer and Eddy Corbett for providing further corrections. Bernard Aboba provided extensive feedback on use cases and the security model; Bernard, along with Alan DeKok, also helped resolve an issue with NAIs. Ray Bellis provided motivation for the protocol port parameters. 9. References 9.1. Normative references [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003. [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January 2004. [RFC4282] Aboba, B., Beadles, M., Arkko, J., and P. Eronen, "The Network Access Identifier", RFC 4282, December 2005. [RFC4361] Lemon, T. and B. Sommerfeld, "Node-specific Client Identifiers for Dynamic Host Configuration Protocol Version Four (DHCPv4)", RFC 4361, February 2006. [I-D.ietf-geopriv-http-location-delivery] Barnes, M., Winterbottom, J., Thomson, M., and B. Stark, "HTTP Enabled Location Delivery (HELD)", draft-ietf-geopriv-http- Winterbottom, et al. Expires August 29, 2009 [Page 16] Internet-Draft HELD Identity February 2009 location-delivery-12 (work in progress), January 2009. [I-D.ietf-geopriv-l7-lcp-ps] Tschofenig, H. and H. Schulzrinne, "GEOPRIV Layer 7 Location Configuration Protocol; Problem Statement and Requirements", draft-ietf- geopriv-l7-lcp-ps-09 (work in progress), February 2009. [W3C.REC-xml-names11-20060816] Tobin, R., Layman, A., Bray, T., and D. Hollander, "Namespaces in XML 1.1 (Second Edition)", World Wide Web Consortium Recommendation REC-xml- names11-20060816, August 2006, . 9.2. Informative references [RFC3693] Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and J. Polk, "Geopriv Requirements", RFC 3693, February 2004. [RFC3825] Polk, J., Schnizlein, J., and M. Linsner, "Dynamic Host Configuration Protocol Option for Coordinate-based Location Configuration Information", RFC 3825, July 2004. [RFC4388] Woundy, R. and K. Kinnear, "Dynamic Host Configuration Protocol (DHCP) Leasequery", RFC 4388, February 2006. Winterbottom, et al. Expires August 29, 2009 [Page 17] Internet-Draft HELD Identity February 2009 [RFC4745] Schulzrinne, H., Tschofenig, H., Morris, J., Cuellar, J., Polk, J., and J. Rosenberg, "Common Policy: A Document Format for Expressing Privacy Preferences", RFC 4745, February 2007. [RFC4776] Schulzrinne, H., "Dynamic Host Configuration Protocol (DHCPv4 and DHCPv6) Option for Civic Addresses Configuration Information", RFC 4776, November 2006. [RFC4825] Rosenberg, J., "The Extensible Markup Language (XML) Configuration Access Protocol (XCAP)", RFC 4825, May 2007. [I-D.ietf-ecrit-phonebcp] Rosen, B. and J. Polk, "Best Current Practice for Communications Services in support of Emergency Calling", draft-ietf- ecrit-phonebcp-07 (work in progress), January 2009. [I-D.thomson-geopriv-held-measurements] Thomson, M. and J. Winterbottom, "Using Device-provided Location- Related Measurements in Location Configuration Protocols", draft-thomson- geopriv-held-measurements- 03 (work in progress), October 2008. [LLDP] IEEE, "802.1AB, IEEE Standard for Local and Metropolitan area networks, Station and Media Access Control Connectivity Discovery", June 2005. Winterbottom, et al. Expires August 29, 2009 [Page 18] Internet-Draft HELD Identity February 2009 Authors' Addresses James Winterbottom Andrew Corporation PO Box U40 University of Wollongong, NSW 2500 AU EMail: james.winterbottom@andrew.com Martin Thomson Andrew Corporation PO Box U40 University of Wollongong, NSW 2500 AU EMail: martin.thomson@andrew.com Hannes Tschofenig Nokia Siemens Networks Linnoitustie 6 Espoo 02600 Finland Phone: +358 (50) 4871445 EMail: Hannes.Tschofenig@gmx.net URI: http://www.tschofenig.priv.at Richard Barnes BBN Technologies 9861 Broken Land Pkwy, Suite 400 Columbia, MD 21046 USA Phone: +1 410 290 6169 EMail: rbarnes@bbn.com Winterbottom, et al. Expires August 29, 2009 [Page 19]