Internet Engineering Task Force Vasu K INTERNET-DRAFT Rahul A J Intended Status: Standard Track Yangneng Expires: Oct 15, 2016 Huawei April 15, 2016 Access Privilege Provisioning for Constrained Devices draft-vasu-ace-core-access-privilege-provisioning-00 Abstract As more constrained devices are integrating with current Internet, the ubiquitous computing in scenarios like smart home is very important. In smart home, the constrained devices (ex. thermostat) need to be provisioned in such a way that it can inter-operate with any kind of devices like other constrained devices (ex. Air conditioner) or client devices (ex. smart phone). This document provides a method to support access privilege provisioning based on pre-configured admission and resource control policies, where this method explains device's service access in two different use cases: first provisioning the service when a constrained device accessing the service provided by other constrained device, second, accessing the service provided by constrained device from the client device (non constrained device). 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/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on Oct 15, 2016. Vasu K Expires Oct 15, 2016 [Page 1] Internet-Draft Access Privilege Provisioning April 15, 2016 Copyright and License Notice Copyright (c) 2016 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. 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Table of Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 System Architecture . . . . . . . . . . . . . . . . . . . . . . 6 5 Network Topology . . . . . . . . . . . . . . . . . . . . . . . . 10 6 Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.1 Discover Provisioning Server . . . . . . . . . . . . . . . . 11 6.2 Register Service . . . . . . . . . . . . . . . . . . . . . . 12 6.3 Verify pre-registered service . . . . . . . . . . . . . . . 13 6.4 Define policies on resource control . . . . . . . . . . . . 14 6.4.1 Resource Control . . . . . . . . . . . . . . . . . . . . 16 6.5 Search for services by device . . . . . . . . . . . . . . . 19 6.6 Service request and response . . . . . . . . . . . . . . . . 20 7 Alternative Solution . . . . . . . . . . . . . . . . . . . . . . 24 7.1 System Architecture . . . . . . . . . . . . . . . . . . . . 24 7.2 Service Request . . . . . . . . . . . . . . . . . . . . . . 25 8 Security Considerations . . . . . . . . . . . . . . . . . . . . 27 9 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 28 10 References . . . . . . . . . . . . . . . . . . . . . . . . . . 28 10.1 Normative References . . . . . . . . . . . . . . . . . . . 28 10.2 Informative References . . . . . . . . . . . . . . . . . . 28 11 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 30 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 30 Vasu K Expires Oct 15, 2016 [Page 2] Internet-Draft Access Privilege Provisioning April 15, 2016 1 Introduction The work on Constrained Restful Environment (CoRE) aimed to realize the restful architecture for constrained devices [RFC7228] in constrained networks [RFC4944]. The CORE work group has recently standardized constrained application protocol (CoAP) [RFC7252] for interacting with constrained resources where general HTTP is not memory/energy efficient. The use of web linking for resources description and discovery hosted by constrained web servers is specified by CORE [RFC6690]. Even though, CoAP allows the direct resource access for constrained devices, it is not advisable for direct access of resources in networks where multicast procedures are infeasible due to heavy network load, and the networks where sleepy nodes exist. So, the CoRE working group comes up with a solution called resource directory (RD) [draft-ietf-core-resource-directory] to host the devices service information, and allow other devices to perform lookup procedures through .well-known/core path to resources. Once the services are advertised by any device, those services need to be verified using commissioner. CORE RD provides a standard procedure to interact with commissioner, where commissioner acts like a client device to look up and verify the advertised services. Once the commissioner verifies the pre-registered services, commissioner can put some policy rules on services hosted by devices for resource control. These rules defined on (1) how to access the services either with other constrained devices or client devices, and (2) on operational instructions. Architecture is defined to authenticate and authorize client requests for a resource on a server using logical entities such as client(C), client authorization manager (CAM), server(S), and server authorization manager (SAM) [draft-gerdes-ace-actors]. The main goal of delegated CoAP authentication and authorization framework (DCAF) is the setup of a datagram transport layer security channel between two nodes to securely transmit authorization tickets [draft-gerdes- core-dcaf-authorize]. The CAM sends an access request message on behalf of client by embedding requested permissions in client authorization information (CAI) field of access request message to SAM. A ticket grant message is sent from SAM by embedding the permissions given from the server on a specific resource in server authorization information (SAI) field of ticket grant message to the client. These SAI, CAI use authorization information format (AIF) that describes the permissions requested from access request in a ticket request, where the underlying access control model will be that of an access matrix, which gives a set of permissions for each possible combination of a subject and an object [draft-bormann-core- ace-aif]. This simple information model also doesn't allow conditional access (e.g.,"resource /s/tempC is accessible only if client belongs to group1 and does not belong to group2"). Vasu K Expires Oct 15, 2016 [Page 3] Internet-Draft Access Privilege Provisioning April 15, 2016 Admission control is addressed with the draft (draft-seitz-ace-oauth- authz) provides a mechanism for pre-configuring secure/authorization policies with token mechanism to access the resource. It is not possible to manage the rest resources by using only tokens that authorize the clients to access the resource. Because, it also needs to handle resource control interms of various other parameters such as priority of request, QoS, Operations that can be performed on resource by various clients. The draft (draft-seitz-ace-oauth-authz) talks about how to provide admission control (conditional authorization) for resource access from client device, but it does not consider constrained device access from another constrained device. So, we integrated our solution with RD, and commissioning procedures along with admission control (AC), and resource control (RC) of resources. Moreover, we provide the mechanism for resource access from another constrained device. For example, consider a user leaves the home in the morning in hot summer and leaves the office in the evening to reach to home. But, before he reaches his room he wants to make his room cool enough. So he has to switch on the air-conditioner from his mobile one hour before he leaves the office. So, before adjusting his air-conditioner to make the room cool enough, he might have to know the current room temperature. Thus he access the service provided by the thermostat to read the room temperature and adjust the air-conditioner. However, there is a problem here on how to access these services which are provided by user's home devices because there may be issues at device such as 1) what is the authenticity level 2) the device might be overloaded from other resource access 3) the device is protected at that time to keep long lifetime 4) Allow only specified users to control it and 5) how to set quality control on resource access. The access privilege provisioning presented in this document provides method to configure the policies for admission as well as resource control in constrained environment (including both constrained and non-constrained devices) that includes complete system architecture, methods for defining policies, and with commissioning procedures. Here, the service provisioning includes authentication, authorization, admission and resource control. 2 Motivation CORE RD solution provides various automated operations such as service registrations, service update, service removal, and service lookups initiated by endpoints and clients. However, managing this centralized directory server by allowing authorized users to perform these tasks, setting some service level agreements on clients to access these services, and providing limited or scope oriented lookups by other endpoints or clients require efficient service Vasu K Expires Oct 15, 2016 [Page 4] Internet-Draft Access Privilege Provisioning April 15, 2016 provisioning mechanism. The access privilege provisioning method presented in this document deals on how a registered service from devices can be accessed by various clients or other devices. Moreover, it also provides a method for handling resource/service access control mechanism for efficient service provisioning from outside the constrained home environment. 3 Terminology 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]. o "CORE", CORE is a Constrained RESTful Environment providing a framework for resource-oriented application intended to run on constrained networks [RFC7228]. o "COAP" The Constrained Application Protocol (CoAP) is a specialized web transfer protocol for use with constrained nodes and networks [RFC7252]. o "RD" The Resource Directory (RD) is a directory based server to host the descriptions of resources and allowing the lookups to be performed for those resources by various client devices. o "Commissioner" Commissioning agent is tool/device that verifies the devices operation, integrity check with the network. o "Constrained Device" These are embedded computing devices that are expected to be as resource constrained in terms of RAM/ROM size, and to be deployed with the constrained environment such as 6LoWPAN Networks. This is also known as Thing. o "Client" A client device is like resource constrained client such as other constrained device (ex. Air conditioner) or rich client devices such as Mobile/Laptop/Tablet etc, which access the services hosted by constrained devices (ex. thermostat). o "Provisioning Server" this server is a process of verifying service requester, providing access control/admission control and resource control on resources to be accessed and inter-operating with various devices without bothering about kind of network protocols used. It provides a method to access a resource either inside or outside the constrained environment. o "Device Profile" A device profile comprises a set of attributes that are associated with a particular device. These include services, features, names, descriptions etc. Vasu K Expires Oct 15, 2016 [Page 5] Internet-Draft Access Privilege Provisioning April 15, 2016 4 System Architecture +--------+ IF-e +--------+ |Thing |............|Thing | |(Client)`. |(Server)| +---X----+ `. IF-d .'----+---+ X `. .' | X `-.' | IF-a IF-h X .' `. | X .' `. | +----------+ +---X----+ .'IF-f `.---+----+ | | | .' | RD | | Client XXXXXXXXXXX PS | | | | | IF-g | | +----+----+ +----------+ +------+-+ / \ / \ IF-c / IF-b XXXXXXX Client Access Resource \ / ----------+-+ -------- Service Registration & | | Configuring Policies | CA | ........ Constrained device access | | resource | | +------------+ PS-Provisionig Server RD-Resource Directory CA-Commissioning Agent Fig 1. System Architecture The system architecture is as shown in Fig 1. The thing (device), always registers its service with RD server. CA verifies registered service with RD server and configures policies at provisioning server for resource access by various other devices or clients. The following interfaces are used in the system architecture IF-a: register service (coap) IF-b: verify service (coap) IF-c: configure policies (http) IF-d: service search (coap) IF-e: obtain resource for constrained devices (coap) IF-f: check for admission/resource control policies for service (coap) IF-g: Service request for non-constrained device (http) IF-h: Obtain resource for non-constrained devices (coap) Vasu K Expires Oct 15, 2016 [Page 6] Internet-Draft Access Privilege Provisioning April 15, 2016 The system architecture is better explained with two different scenarios: (1) Constrained device access the service advertised by other constrained device is as shown in Fig 2. Here, one constrained device such as air-conditioner can access the service such as current room temperature advertised by other constrained device (ex. thermostat). This advertised service is to be commissioned by commissioner, and then it should be set with some admission and resource control policies by provisioning server. And, finally the service is allowed to advertise its service access from other constrained devices. Any device that is interested in that advertised service, need to do service lookup from RD Server. Once obtaining the path to the advertised service, the constrained client device can request a service to the device which hosts the service. Before sending the request, it MUST establish a secure channel between these two nodes [draft-schmitt- ace-twowayauth-for-iot]. Once the incoming request comes from the constrained client device, the device which hosts the service MUST authorize and provision for conditional access of its service from the provisioning server. The notification regarding the registered services to the commissioning agent can be sent from the RD server, which can be implementation specific and left for the user to choose any standard procedures and is out of scope of present document. Detailed operational procedure will be explained in the later sections of this document. 2) Client device access the service advertised by constrained device is as shown in Fig 3. For example, the client device such as smart phone can access the service (ex. room temperature) advertised by other constrained device (ex. thermostat). The client can access the service within a home environment or outside the home environment. So, in this scenario, the provisioning server maintains the service as a web service. This advertised service is to be commissioned by commissioner, then to be set with some admission and resource control policies by provisioning server. And, finally the service is allowed to advertise its access from the client devices. Any client that wishes to access this web service looks for corresponding operations provided from the provisioning server. Vasu K Expires Oct 15, 2016 [Page 7] Internet-Draft Access Privilege Provisioning April 15, 2016 +------+ +-------+ +-----+ +--------+ +----------+ |Device1 |Device2| | RD | |Provis | |Commision |(Air |(Thermo| | | |ioning | |ing | |Condi | | stat)| |Serv |Sever | |Agent | |tioner) | | |er | | | | | +--|---+ +----|--+ +--|--+ +----|---+ +-----|----+ | | | | | | | | | | | |Register | | | | ----------// | | | | Service/| Verify Preregistered\ |/ | | ------------------------// | | | Service| // | | | | | / | | | | | | | | | | | | | | | | | | | |//Define | | | | /------------- | | | / \ Policies | |Search a Service \ | | | ---------------------// | | | | //| | | | | / | | | | | | | | | | | | | |Request | | | | -----------/ | | | |Service /| | | | | / | | | | | |Check for authorization | | |admission, Resource | | | ---------------------// | | | Control Policies //| | | | | / | | | | | | | | | | | | | | // Service Grant/Deny | | /--------------------- | | /|\ | | | | / | | | | \//Service | | | | /\---------- | | | | Grant/Deny | | | | | | | | Fig 2.Constrained device accessing service from constrained device Vasu K Expires Oct 15, 2016 [Page 8] Internet-Draft Access Privilege Provisioning April 15, 2016 +--------+ +-------+ +-------+ +---------+ +---------+ |Client | |Device2| |RD | |Provision| |Commissi | |(Smart | |(Thermo| |Server | |ing Server |oning | | Phone) | | stat) | | | | | |Agent | | | | | | | | | | | | | | | | | | | | | +---|----+ +---|---+ +---|---+ +----|----+ +-----|---+ | | | | | | | | | | | |Register | | | | -----------/ | | | |Service / | | | | /| | | | | | / | | | | |//Verify Preregistered | | | -------------------------- | | |\ Service | | | | | | | | | | | | | | | / | | | | |//Define | | | | ------------- | | | |\ Policies | | | | | | | Request for Service | \ | ----------------------------------// | | | | //| | | | | / | | | | | | | | | / | | | | |// Request| for Service | | ----------------------- | | | | | | | | | | | | | | | | | | Service Grant/Deny\ | | | ----------------------/ | | | | //| | | | | / | | | | | | | | | | | | | // | | | | |// Service Grant/Deny | | \---------------------------------- | | \ | | | | | | | | | Fig 3. Client accessing service from Constrained device Vasu K Expires Oct 15, 2016 [Page 9] Internet-Draft Access Privilege Provisioning April 15, 2016 5 Network Topology ------- -------- // \ // \ / // \ / / / / | +--------+ | | +--------+| | |RD Server---| | | +-----+ |Thermostat| | +--------+ | | LAN | |Edge | +--------+ | | |------|------- | | | +----------+ | | | | |Router 6LoWPAN | | |Provision --|| | |+-----+ | |Server | / | +--------+ / +----------+ / | |Aircondioner / | \ +--------+// \ // | \ // ------- | -------- | | -|----- //- | -\ // +-|----+ \ / |Edge | / |Router| | +------+ | | | | WiFi | | +-------+ +-----+ | | |Smart | |Commisioning | |Phone | | Agent| +-------+ +-----+/ / \ // \- -// ------- Fig 4. Network Topology The constrained devices such as Thermostat, Airconditioner may use small memory constrained sensors/actuators for simple services such as cooling/heating the room or just to measure the current room temperature. These memory constrained embedded devices may implement the 6LoWPAN stack such as uIP (provided by Contiki), and provide access for communication to other external queries from client devices such as smart phone which typically implements rich stack TCP/IP. Even though RD server or Provisioning server are shown as separate servers in the LAN as given in Fig 4, these can Vasu K Expires Oct 15, 2016 [Page 10] Internet-Draft Access Privilege Provisioning April 15, 2016 be hosted on a single server running two different processes. Moreover, the commissioner implements a standard procedure to interact with devices as a separate agent process which is out of scope of the present document and has been left to user's choice while satisfying the mentioned operations in the current draft. On the other hand, these specific operations can be implemented separately as a third party and to be used at the commissioning agent. The lower level communication technology can be implemented either through Bluetooth (BT) or near field communication (NFC) to verify the devices unique ID (for ex. using MAC). Even though, the implementation procedure for commissioner is out of scope for the present document, it is shown as sample interaction with RD server/provisioning server as part of commissioning procedure in subsequent sections. Even though the present document discusses about 6LoWPAN based sensor network, it can be easily moved to any other technology such as Zigbee/BLE/Wireless HART without any changes in the architecture or design, because the present document abstracted the communication networks with their edge routers. The communication and routing mechanisms or procedure between edge router and sensor devices/client devices are out of scope of the present document. 6 Operations 6.1 Discover Provisioning Server Suppose a client device request for a resource which is hosted on device that 1) might be unreachable 2) far distant from the requesting client/device 3) cannot hold more requests 4) might not intend to provide any resource and 5) want to allow limited operations; querying that resource is waste of communication resource. Because, the resource directory server won't be aware until the device/thing do explicit delete operation. The client or device which accesses the resource should be provisioned dynamically for admission and resource control. To query for resource, the client or device should only query for resource type, kind of operation it want, and optionally an endpoint. With this information, the provisioning server should be able to decide which resource to grant, where the PS might use the conditional statements made for each resource. When the PS is in network, client or device can make the following well-known queries for the provisioning server: rt=core.ps ---- Provisioning server =core.ps.search ---- Resource search Here, core.ps returns resource type as provisioning server, and "core.ps.search" is used to search for any specific resource Vasu K Expires Oct 15, 2016 [Page 11] Internet-Draft Access Privilege Provisioning April 15, 2016 queries, the following query options are allowed under provisioning server: op --- operation rt --- resource type ep --- endpoint The following example explains about how a well-know query for provisioning server should be done: REQ: GET /.well-known/core rt=core.ps RES: ; "rt=core.ps" And, the following example explains about how a query options can be used to search for resource on provisioning server. REQ: GET coap://ps.example.com/core.ps.search/ep?op=read&rt=temp RES: ; ep=node1; rt=temp; 6.2 Register Service +---------+ +---------+ | | | | | Device | |RD Server| | | | | +----+----+ +-----+---+ | | | | | `. | | POST /rd?ep=node1&d=example.com&et=temperature-no`.| +--------------------------------------------------,'. | gp=thermostat&con=DeviceID(100) ,' | | ,' | | ,' | | ,' 2.01 Created Location: /rd/7521 | `.---------------------------------------------------- | `-. | | `. | | | Fig. 5 Registering a Service The constrained device which hosts the service MUST register its service with the RD server using its unique identifier (for ex. MAC id, UDDI registry etc.) and IP address as shown in Fig 5. The device MUST send a POST request for registering its service. Before sending a request, it MUST establish a secure channel Vasu K Expires Oct 15, 2016 [Page 12] Internet-Draft Access Privilege Provisioning April 15, 2016 between these two nodes [draft-schmitt-ace-twowayauth-for-iot]. Once the service has been registered with the RD server, the RD server may notify the registered information of a device (for ex.its unique identifier and device name) to a commissioning agent. 6.3 Verify pre-registered service +---------------+ +----------+ |Commissioning | | RD Server| |Agent | | | +------+--------+ +--------+-+ | | | | | GET /rd-lookup/d `. | +--------------------------------------------------:'. | .' | | | | .'2.05 Content ;d=example.com,;d=example.com ::---------------------------------------------------+ | `-. | | GET /rd-lookup/gp?ep=node1&d=example.com `. | +---------------------------------------------------/. | .' | | | | .'2.05 Content ;gp=thermostat;ep=node1 ::---------------------------------------------------+ | `-. | | `. | | GET /rd-lookup/res?rt=temp&gp=thermostat&d=example.com +--------------------------------------------------:'. | .' | | | | .'2.05 Content ;rt=temp;gp=thermostat ::---------------------------------------------------+ | `-. d=example.com | +---------------------------+ | |Authentication of Service | | |Info and DeviceID | | +---------------------------+ POST Verified User; DeviceID`. | +---------------------------------------------------:: | .' .-' | .`.__________________________________________________| | `. 2.00 OK | Fig. 6 Verify pre registered service Vasu K Expires Oct 15, 2016 [Page 13] Internet-Draft Access Privilege Provisioning April 15, 2016 SRV { Name: Node1 Group: Thermostat Domain: myhome.com Type: Temperature node Device ID: 1001 Device IP: } Fig 7. Example Service Information The commissioning agent MUST verify any pre registered service with the RD server as shown in Fig 6. The commissioning agent sends a GET request for domain lookup. Before sending the request, it MUST establish a secure channel between these two nodes [DTLS][TLS]. Once obtaining the specific domain, it MUST look for the group to which the service belongs. Once obtaining the specific domain and group, it MUST send a service look up with the RD server for the registered service. Once obtaining the service information about a specific device, the commissioning agent MUST verify the registered service. This service information is later used to create service registry in the provisioning server as explained in the following section. The example service information (denoted as SRV) looks like as shown in Fig 7. 6.4 Define policies on resource control Once the hosted service has been verified by commissioning agent (CA), the CA MUST create a service registry with the provisioning server as explained in Fig 8. The provisioning server SHOULD send a service ID as a response back to the commissioning agent after creating the service entry. This service ID can be later used by the commissioning agent to permanently DELETE the service entry ( if required). The commissioning agent MUST create some admission control policies such as read (R), write (W), read/write (R/W), delete (D), number of simultaneous connection on resource etc. on the registered service. Once the admission control policies has been set on a specific device, the resource control policies such as conditional access of a service, quality of service agreements (based on the priority levels set for clients) can be set on that registered service. These conditional access on service can be implemented with simple conditional statements as explained in section 6.3.1 (for ex. "client (c) can access service with only read (R), write (W) permissions if it only belongs to group (g)"). Vasu K Expires Oct 15, 2016 [Page 14] Internet-Draft Access Privilege Provisioning April 15, 2016 +----------------+ +---------------+ |Commissioning | |Provisioning | | Agent | | Server | +------+---------+ +--------+------+ | POST /thermostat /HTTP/1.1 `. | +------------------------------------------/. | HOST thermostat.ps.example.com .' | | Content-Type: application/text | | SRV { Name: Node1 | | Group: Thermostat | | Domain: myhome.com | | Type: Temperature-node | | DeviceID: 1001 | | DeviceIP: } | | | | .' HTTP/1.1 200 OK | ::------------------------------------------' | `. Content-Type: application/text | | { sID (service ID) } | | | | POST /thermostat /HTTP/1.1 `. | +------------------------------------------:: | HOST thermostat.ps.example.com .' | | Content-Type: application/text | | AC { ServiceID: 1234 | | Auth: Basic Auth Support | | Count: 10 | | Admission Control: R,W,R/W,D } | | | | .' HTTP/1.1 200 OK | ::------------------------------------------+ | `. Content-Type: application/text | | | | POST /thermostat /HTTP/1.1 `. | +------------------------------------------:: | HOST thermostat.ps.example.com .' | | Content-Type: application/text | | RC { If C is from G1 allow {R,W}; | | If C is from G2&!G3 allow {R}; | | If C is from d1&g1 allow {R,W,D}; | | : } | | .' HTTP/1.1 200 OK | ::------------------------------------------+ | `. Content-Type: application/text | | | Fig. 8 Defining Policies on Resource and Access Control The implementation or information format details of these conditional statements is out of scope of the present document Vasu K Expires Oct 15, 2016 [Page 15] Internet-Draft Access Privilege Provisioning April 15, 2016 (TBD). The example admission control and resource control policies are as shown in Fig 9, and Fig 10 respectively. AC { Service ID: 12345 Auth: Basic Auth Support Count: 10 Admission Control: R, W, R/W, D : : } Fig 9. Example Admission Control Policies RC { If c is from g1 allow {R,W} If C is from g2 & !g3 {R} If C is from d1 & g1 allow {R, W, D} : : } Fig 10. Example Resource Control Policies 6.4.1 Resource Control Resource control policies for constrained devices are expressed in terms of conditional expressions as explained in Fig. 10. Consider a scenario where we define the client (C) (who accesses the resource) in terms of groups/levels. For example in a typical home building, we assign each floor as a group. Suppose for a three floor building, the clients such as mobile phone/air conditioner can belong to any of the floor within a building. And we allow various permissions for the clients according to the group it belongs to, as specified in Fig 11. --------------------------- | | | | | | |Client | R | W | U | D | |-------------|---|---|---| |G1 | * | - | * | - | | | | | | | |G2 | * | * | - | - | | | | | | | |G3 | - | - | - | * | |-------------------------- Fig 11. Example Permissions on Methods Vasu K Expires Oct 15, 2016 [Page 16] Internet-Draft Access Privilege Provisioning April 15, 2016 Suppose, we assigned the priorities for different groups as C belongs to {G1, G2, G3} => {P1, P3, P2}. Moreover, if we would like to assign different QoS classes for clients, depending on the applications they use then it is required to control QoS policies in resource control. QoS is defined in terms of various parameters such as {availability, reliability, serviceability, data accuracy, aggregation delay, coverage, fault tolerance, network lifetime} in wireless sensor networks. It is assumed that based on these parameters, QoS is defined in terms of various classes such as {Q1, Q2, Q3}, then it is required that some of the clients can make some pre-level agreements on QoS requirement for their applications either based on the groups it belongs to or based on the priority of the clients request (Suppose, C belongs to {Q1, Q2, Q3}). Method for defining QoS classes is out of scope of the present document. Once defining the groups, its priorities, QoS classes, and permissions, then the conditional statements which define the resource control policies can be defined as follows: ST1: If the client belongs to G1 then it is allowed with permissions {R, R/W, U}, priority {P1}, QoS {Q1}, and operations {turn it up, read}; else if the client belongs to G2 then it is allowed with permissions {R, W, R/W}, priority {P3}, QoS {Q2}, and operations {turn it up, read}; else if the client belongs to G3 then it is allowed with permissions {D}, priority {P2}, QoS {Q3}, and operations {turn it down}. ST2: Allow the client with priority {P1}, QoS {Q1}, operations {turn it up, turn it down, read}, and allow only with permissions {R} in G1; permissions {R, R/W, D} in G2; and permissions {D} in G3. ST3: Allow the client with priority {P1}, QoS {Q1}, and allow with permissions {R}, operations {read} in G1; allow with permissions {R, R/W, D}, operations {turn it up, turn it down, read} in G2; and allow with permissions {D}, operations {turn it down} in G3. Above conditional statements are few examples on how to define the conditional statements, the statements can be defined on any manner based on the resource control policies we would like to achieve. The above statements can be better explained in plain semantic notation as shown in Fig 12(a)-14(a), and the corresponding JSON representations for message exchange is explained in Fig 12(b)-14(b). These statements can be even implemented using data modeling language such as YANG or ASN 1.1 which is out of scope of the present document. Vasu K Expires Oct 15, 2016 [Page 17] Internet-Draft Access Privilege Provisioning April 15, 2016 C { G1 |"[ { |"C":{"G1":{"Allow":"R,U", Allow {R,U} |"Priority":"P1","QoS":"Q1", Priority {P1} |"Operations":"turnup,read"}, QoS {Q1} |"G2":{"Allow":"R,W", Operations {tunr it up, read}|"Priority":"P3","QoS":"Q2", } |"Operations":"turn it G2 |up,read"},"G3":{"Allow":"D", { |"Priority":"P2","QoS":"Q3", Allow {R,W} |"Operations":"turn it down" Priority {P3} |}}]" QoS {Q2} | Operations {turn it up, read}| } | G3 | { | Allow {D} | Priority {P2} | QoS {Q2} | Operations {turn it down} | } | } | (a) (b) Fig 12. ST1: (a) Semantic Notation (b) JSON Representation C | "[ { | "Priority":"P1","QoS":"Q1", Priority {P1} | "Operations":"turn it up, QoS {Q1} | turn it down, read", Operations {turn it up,turn it | "C":{"G1":{"Allow":"R"}, down, read} | "G2":{"Allow":"R,W,D"}, G1 | "G3":{"Allow":"D"}} { | ]" Allow {R} | }; | G2 | { | Allow {R,W,D} | }; | G3 | { | Allow {D} | }; | } | (a) (b) Fig 13. ST2: (a) Semantic Notation (b) JSON Representation Vasu K Expires Oct 15, 2016 [Page 18] Internet-Draft Access Privilege Provisioning April 15, 2016 C | "[ { | "Priority":"P1","QoS": Priority {P1} | "Q1","C":{"G1": {"Allow": QoS {Q1} | "R","Operations":"read"}, G1 | "G2":{"Allow":"R,W,D", { | "Operations":"turn it up, Allow {R} | turn it down, read"}, Operations {read} | "G3":{"Allow":"D", }; | "Operations":"turn it G2 | down"}}]" { | Allow {R,W,D} | Operations {turn it up, turn | down, read} | }; | G3 | { | Allow {D} | Operations {turn it down} | }; | } | (a) (b) Fig 14. ST3: (a) Semantic Notation (b) JSON Representation 6.5 Search for services by device Any client device (as explained for scenario 2) MUST interacts with the provisioning server and looks for deployed services by devices. Moreover, the provisioning server can verify the complete authorization, admission, and resource control of any device's services. Whereas, if any other constrained devices (ex. air conditioner) searches for services hosted by other constrained device (as explained for scenario 1) MUST interact with the RD server as shown in Fig 15. Here, initially the device queries for all services that are hosted by other devices, then it searches within the domain for specific service, its SRV info, and path to the hosted service. Before sending a request, it MUST establish a secure channel between these two nodes [draft-schmitt-ace- twowayauth-for-iot]. Vasu K Expires Oct 15, 2016 [Page 19] Internet-Draft Access Privilege Provisioning April 15, 2016 +---------------+ +----------+ | Device | | RD Server| | (aircondit | | | | ioner) | | | +-----+---------+ +-------+--+ | | | GET /rd-lookup/gp?d=example.com `. | +---------------------------------------------------`.: | .-' | | .'2.05 Content | ::----------------------------------------------------+ | `-. | | GET /rd-lookup/ep?gp=thermostat `. | +----------------------------------------------------:: | .' | | .'2.05 Content | ::----------------------------------------------------+ | `. | | | | GET /rd-lookup/ep?et=temperature&gp=thermostat `. | +----------------------------------------------------`. | .' | | | | .'2.05 Content ;ep="Node1" | ::----------------------------------------------------+ | `-. | | | Fig. 15 Search for services by device 6.6 Service request and response In scenario 1 (as shown in Fig 2), service request and response MUST use coap based communication to access the service as shown in Fig 16. Before sending a request, it MUST establish a secure channel between these two nodes [draft-schmitt-ace-twowayauth-for- iot]. Suppose, the constrained client device (for ex. airconditioner) want to access the service hosted by another constrained device (for ex. thermostat), then the client device MUST send a coap based GET request to thermostat. Then, this device (thermostat) SHOULD send a POST request to provision this service request with the provisioning server by sending clients . Based on the clients , the provisioning server MUST find the client (ex. airconditioner) details such as service information, group, domain, and type details. Vasu K Expires Oct 15, 2016 [Page 20] Internet-Draft Access Privilege Provisioning April 15, 2016 +------------+ +-------------+ +-----------+ |Airconditi | |Thermostat | |Provision | |oner | | (IP1) | |ining Server | (IP2) | | | | (IP3) | +-----+------+ +------+------+ +--------+--+ | | | |coap://thermostat. `.| | +----------------------------:: | | example.com/temp .' |POST /thermostat `. | | +-------------------------:: | |HOST thermostat.ps. .' | | | example.com | | |Content-Type: application/txt | |{ SRC: | | | DST: | | | Client: } | | | | | | +--------------------------+ | | |Check for Admission, | | | |ResourceControl of thermost | | |for airconditioner | | | +--------------------------+ | | | | | .'2.00 OK { Permit/Deny }| | .'URI-Path: temp CON 200 ::------------------------+ ::---------------------------+ `-. | | `.("thermostat","aaaa::212.| | | 7402.2.202","temp",27) | | | | | Fig. 16 Request/Response within Constrained Environment Once the client is identified, the provisioning server MUST check for authorization, admission and resource control policies of hosted service (ex. thermostat). Once the service request is authorized to access then the URI-Path for hosted service along with the value is sent as a coap response to client device (air conditioner). Here, the request is conditional i.e. based on the resource control policies of a resource (such as thermostat) for a client (airconditioner), the permissions are given to access the resource. Vasu K Expires Oct 15, 2016 [Page 21] Internet-Draft Access Privilege Provisioning April 15, 2016 +-------------+ +------------+ +---------+ | | |Provision | | | | Client | |ining Server| |Thermostat | | | | | | +-----+-------+ +-----+------+ +------+--+ | | | |http://thermostat. `. | | +----------------------------:: | | example.com/temp .' | | | +-----------------------------+ | | |Check for Admission, | | | |Resource Control of thermostat | | |for airconditioner | | | +-----------------------------+ | | | | | | coap://thermostat. `. | | +------------------------:: | |example.com/temp .' | | | | | | | | | .'URI-Path: temp CON 200| | ::------------------------+ | | `. | | .' HTTP/1.1 200 OK | | ::----------------------------+ | | `. Temperature: 27 | | | | | Fig. 17 Request/Response from outside Constrained Environment Service request and response in scenario 2 (as shown in Fig 3), uses simple http based communication to access the service from the PS. Provisioning Server then sends a coap based GET request to the ultimate device that hosts service. Before sending this request to the actual device for service, PS authorizes the service request. Once, the service request is authorized to access, then the URI-path for hosted service along with the value is sent as HTTP response to client device. PS can implement a reverse proxy case for HTTP-CoAP protocol translation defined in [draft-ietf-core-http-mapping]. ------------------HTTP begin ------------------------------------- HTTP POST Request: POST /thermostat /HTTP/1.1 HOST thermostat.example.com Content-Type: application/x-www-form-urlencoded Vasu K Expires Oct 15, 2016 [Page 22] Internet-Draft Access Privilege Provisioning April 15, 2016 Content-Length: length licenseID=string & content=string & paramsXML=string Response: HTTP/1.1 200 OK Content-Type: text/xml; charset=utf-8 Content-Length: length string ------------------HTTP end ------------------------------------- ------------------ REST via HTTP begin -------------------------- REST via HTTP POST Request: POST /thermostat /HTTP/1.1 HOST thermostat.example.com Content-Type: application/x-www-form-urlencoded Content-Length: length licenseID=string & content=string & paramsXML=string Response: HTTP/1.1 200 OK Content-Type: text/xml; charset=utf-8 Content-Length: length string ------------------REST via HTTP end ----------------------------- ------------------SOAP begin ------------------------------------ SOAP 1.2 Request: POST /Thermostat /HTTP/1.1 HOST: www.example.org Content-Type: application/soap+xml; charset=utf-8 Content-Length: length Xmlns:soap=http://www.w3.org/2001/12/soap-envelop Soap:encodingStyle=http://www.w3.org/2001/12/soapencoding> Vasu K Expires Oct 15, 2016 [Page 23] Internet-Draft Access Privilege Provisioning April 15, 2016 1 Response: HTTP/1.1 200 OK Content-Type: application/soap+xml; charset=utf-8 Content-Length: length Xmlns:soap=http://www.w3.org/2001/12/soap-envelop Soap:encodingStyle=http://www.w3.org/2001/12/soapencoding> 27.8 ------------------SOAP end ---------------------------------- 7 Alternative Solution 7.1 System Architecture The system architecture is as shown in the Fig 18, the thing (device) always registers its service with RD server. CA verifies registered service with RD server and configures policies at provisioning server for resource access by various other devices or clients. The provisioning server can access any resource from the RD server and also has right to provision any device or client before assigning the resource. This provisioning server not only authorizes the client, it also controls the resource access with the configured policies with various non security parameters. The client or device should always talk to provisioning sever for resource access. Once authorized and provisioned completely it is allowed to access the resource. The following interfaces are defined in the architecture. IF-a: register service (coap) IF-b: verify service (coap) IF-c: configure policies (coap or http) IF-d: obtain resource (coap) IF-e: assign resource (coap or http) Vasu K Expires Oct 15, 2016 [Page 24] Internet-Draft Access Privilege Provisioning April 15, 2016 +-------+ |Thing | |(Server| +---+---+ | |IF-a | | +-------+ +--------+ +--+---+ | | | | | | |Client |________| |___________| | |(Thning| IF-e | PS | IF-d | RD | |/Client) | | | | +-------+ +-------++ +-+----+ \ / IF-c \ / \ /IF-b \ / +--+----+-+ | | | CA | | | PS-Provisioning Server +---------+ RD-Resource Directory CA-Commissioning Agent Fig 18. System Architecture 7.2 Service Request The device either constrained (ex. air conditioner) or non- constrained (ex. mobile phone) that searches for services hosted by other constrained device MUST interact with the Provisioning Server (PS) as shown in Fig 19. Here, the device queries to the provisioning server by query options for example, "op=read & rt=temp", which means "obtain resource with read operation". Before sending a request, it MUST establish a secure channel between these two nodes [draft-schmitt-ace-twowayauth-for-iot]. Whenever the provisioning server receives the resource request from device or client, it MUST find the group to which the device or client belongs to from the preconfigured information. Vasu K Expires Oct 15, 2016 [Page 25] Internet-Draft Access Privilege Provisioning April 15, 2016 +-------------+ +-------------+ +--------------+ |Device | | | | | |(AirCondition| |Provisioning | |RD Server | |er) | |Server | | | | | | | | | +----|--------+ +-------|-----+ +--------|-----+ |GET | | |coap://ps.example.com/c | | |ore.ps.search/ep?op=rea | | |d&rt=temp \ | --------------------------/ | | / | | +-------------------------+ | | | | | | | | find the group to which | | | | the device belongs to | | | +-------------------------+ | | |GET | | |/rd-lookup/res?rt= \| | -temp-----------------/ | | /| | | / | | | / ;-ep=node1;------ | | rt=temp;...... | | | | | | | | +-----------------------------+ | | | Parse the conditional | | | | statements for each | | | | resource obtained | | | +-----------------------------+ | | | | | | | | +------------------------------+ | | |Obtain the most suited | | | |resource from the list and | | | |increase the count field in | | | |AC. And assign that resource | | | +------------------------------+ | | | | \-----------------------| | | \ | | Fig 19. Search for Service Vasu K Expires Oct 15, 2016 [Page 26] Internet-Draft Access Privilege Provisioning April 15, 2016 Once obtaining the group information of device or client, PS SHOULD do rt-lookup query to RD server. After obtaining the resource information, the PS MUST parse the conditional statements for each resource to detect most suited resource to be assigned to the client or device. The method for detecting the best resource can use any well-know MADM or fuzzy logic techniques which is out of scope of the present document. And finally, the provisioning server should increase the count field in admission control, and assign the resource to device/client. Once the service request is authorized and provisioned to control the resource, the device or client can obtain the resource directly as shown in Fig 20. +---------------+ +--------------+ | | | | |Device | |Thermostat | |(Airconditione | | | |r | | | | | | | +-------|-------+ +-------|------+ | | | | | | |coap://[aaaa::212.7402.2.202]:61 | |616/temp \ | -------------------------------------/- | / | | / | | | | | | | | | | / | |// { et:"thermostat"; "temp":27} | /-------------------------------------- | |\ | | | | | Fig 20. Service Request and Response 8 Security Considerations Security level for message authentication is out of scope of the present document. However, the following security consideration needs to be considered for the present proposed method. Services that run over UDP are unprotected and vulnerable to unknowingly Vasu K Expires Oct 15, 2016 [Page 27] Internet-Draft Access Privilege Provisioning April 15, 2016 become part of a DDoS attack as UDP does not require return routability check. Therefore, an attacker can easily spoof the source IP of the target entity and send requests to such a service which would then respond to the target entity. The TLS/DTLS based security solution can be considered for secure message communication. 9 IANA Considerations core.ps and "core.ps.search" to be registered with the resource type registry defined by [RFC6690]. Under "CoRE Parameters" , a new query parameter needs to be defined as shown below. The query parameter MUST be a valid URI query key [RFC3986]. +--------+---------+----------+---------+ |Name | Query |Validity |Description |________|_________|__________|_________| | | | |Used for | |Operatio| op | string |operation| | n| | |on device| | | | | | +--------+---------+----------+---------+ 10 References 10.1 Normative References 10.2 Informative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for Constrained-Node Networks", RFC 7228, May 2014. [RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler, "Transmission of IPv6 Packets over IEEE 802.15.4 Networks", RFC 4944, September 2007. [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained Application Protocol (CoAP)", RFC 7252, June 2014. [RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link Format", RFC 6690, August 2012. Vasu K Expires Oct 15, 2016 [Page 28] Internet-Draft Access Privilege Provisioning April 15, 2016 [draft-ietf-core-resource-directory] Shelby, Z., and Bormann, C., "CoRE Resource Directory", draft-ietf-core-resource-directory-02 (work in progress), November 2014. [draft-gerdes-ace-actors] Gerdes, S., "Actors in the ACE Architecture", draft-gerdes-ace-actors-03 (work in progress), March 2015. [draft-gerdes-ace-dcaf-authorize] Gerdes, S., Bergmann, O., Bormann, C., "Delegated CoAP Authentication and Authorization Framework (DCAF)", draft-gerdes-ace-dcaf-authorize-02, March 2015. [draft-bormann-core-ace-aif] Bormann, C., "An Authorization Information Format (AIF) for ACE", draft-bormann-core-ace-aif-oo, January 2014. [draft-schmitt-ace-twowayauth-for-iot] Schmitt, C., Stiller, B., "Two-way Authentication for IoT", draft-schmitt-ace- twowayauth- for-iot-01, December 2014. [DTLS] Rescorla, E. and N. Modadugu, "Datagram Transport Layer Security", RFC 6347, January 2012. [TLS] Dierks, T. and C. Allen, "The TLS Protocol Version 1.2", RFC 5246, August 2008. [draft-ietf-core-http-mapping] Castellani, A., Loreto, S., Rahman, A., Fossati, T., and Dijk, E., "Guidelines for HTTP-CoAP Mapping Implementations", draft-ietf-core-http-mapping-05, (work in progress), Oct 2015. [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, January 2005, . [draft-seitz-ace-oauth-authz] Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., Tschofenig, H., "Authorization for the Internet of Things using OAuth 2.0", draft-seitz-ace-oauth-authz-00, (work in progress), Oct 2015. Vasu K Expires Oct 15, 2016 [Page 29] Internet-Draft Access Privilege Provisioning April 15, 2016 11 Acknowledgements Special thanks to Amit Kumar S,Zhengfei, Fubaicheng, zuojing, Yangjun,Vijayachandran Mariappan, Shashidhar C Shekar, Jayaraghavendran K, Ajay Sankar, Puneet Balmukund Sharma, and Rabi Narayan Sahoo for extensive comments and contributions that improved the text. Special Thanks to Caozhen, Hedanping (Ana), Behcet Sarikaya, and Carsten Bormann for helpful comments and discussions that have shaped the document. Thanks to IETF 94th participants to give valuable comments that shaped the draft with clear information. Authors' Addresses Vasu K Huawei Technologies Bangalore India EMail: vasu.kantubukta@huawei.com Rahul A Jadhav Huawei Technologies Bangalore India EMail: rahul.jadhav@huawei.com yangneng Huawei Technologies Shenzhen China EMail: yangneng@huawei.com Vasu K Expires Oct 15, 2016 [Page 30]