--- 1/draft-ietf-netconf-access-control-01.txt 2011-02-03 16:15:14.000000000 +0100 +++ 2/draft-ietf-netconf-access-control-02.txt 2011-02-03 16:15:15.000000000 +0100 @@ -1,19 +1,19 @@ Internet Engineering Task Force A. Bierman Internet-Draft Brocade Intended status: Standards Track M. Bjorklund -Expires: April 28, 2011 Tail-f Systems - October 25, 2010 +Expires: August 7, 2011 Tail-f Systems + February 3, 2011 Network Configuration Protocol Access Control Model - draft-ietf-netconf-access-control-01 + draft-ietf-netconf-access-control-02 Abstract The standardization of network configuration interfaces for use with the NETCONF protocol requires a structured and secure operating environment, which promotes human usability and multi-vendor interoperability. There is a need for standard mechanisms to restrict NETCONF protocol access for particular users to a pre- configured subset of all available NETCONF operations and content. This document discusses requirements for a suitable access control @@ -27,166 +27,157 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on April 28, 2011. + This Internet-Draft will expire on August 7, 2011. Copyright Notice - Copyright (c) 2010 IETF Trust and the persons identified as the + Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. - This document may contain material from IETF Documents or IETF - Contributions published or made publicly available before November - 10, 2008. The person(s) controlling the copyright in some of this - material may not have granted the IETF Trust the right to allow - modifications of such material outside the IETF Standards Process. - Without obtaining an adequate license from the person(s) controlling - the copyright in such materials, this document may not be modified - outside the IETF Standards Process, and derivative works of it may - not be created outside the IETF Standards Process, except to format - it for publication as an RFC or to translate it into languages other - than English. - Table of Contents - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 - 1.1.1. Requirements Notation . . . . . . . . . . . . . . . . 5 - 1.1.2. NETCONF Terms . . . . . . . . . . . . . . . . . . . . 5 - 1.1.3. NACM Terms . . . . . . . . . . . . . . . . . . . . . . 6 - 2. Authentication Requirements . . . . . . . . . . . . . . . . . 7 - 3. Access Control Requirements . . . . . . . . . . . . . . . . . 8 - 3.1. Protocol Control Points . . . . . . . . . . . . . . . . . 8 - 3.2. Simplicity . . . . . . . . . . . . . . . . . . . . . . . . 9 - 3.3. Procedural Interface . . . . . . . . . . . . . . . . . . . 9 - 3.4. Database Access . . . . . . . . . . . . . . . . . . . . . 9 - 3.4.1. Access Rights . . . . . . . . . . . . . . . . . . . . 10 - 3.4.2. and Operations . . . . . . . . . . 10 - 3.4.3. Operation . . . . . . . . . . . . . . . 10 - 3.4.4. Operation . . . . . . . . . . . . . . . 11 - 3.5. Users and Groups . . . . . . . . . . . . . . . . . . . . . 12 - 3.6. Maintenance . . . . . . . . . . . . . . . . . . . . . . . 12 - 3.7. Configuration Capabilities . . . . . . . . . . . . . . . . 12 - 3.8. Identifying Security Holes . . . . . . . . . . . . . . . . 13 - 3.9. Data Shadowing . . . . . . . . . . . . . . . . . . . . . . 13 - 3.10. NETCONF Specific Requirements . . . . . . . . . . . . . . 14 - 4. NETCONF Authentication and Authorization Model . . . . . . . . 15 - 4.1. SSH Public Key Authentication . . . . . . . . . . . . . . 15 - 4.2. Local User Password Authentication . . . . . . . . . . . . 16 - 4.3. RADIUS Password Authentication and Service - Authorization . . . . . . . . . . . . . . . . . . . . . . 16 - 4.3.1. Operation . . . . . . . . . . . . . . . . . . . . . . 16 - 5. NETCONF Access Control Model (NACM) . . . . . . . . . . . . . 18 - 5.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 18 - 5.1.1. Features . . . . . . . . . . . . . . . . . . . . . . . 18 - 5.1.2. External Dependencies . . . . . . . . . . . . . . . . 19 - 5.1.3. Message Processing Model . . . . . . . . . . . . . . . 19 - 5.2. Model Components . . . . . . . . . . . . . . . . . . . . . 21 - 5.2.1. Users . . . . . . . . . . . . . . . . . . . . . . . . 21 - 5.2.2. Groups . . . . . . . . . . . . . . . . . . . . . . . . 22 - 5.2.3. Sessions . . . . . . . . . . . . . . . . . . . . . . . 22 - 5.2.4. Access Permissions . . . . . . . . . . . . . . . . . . 22 - 5.2.5. Global Enforcement Controls . . . . . . . . . . . . . 23 - 5.2.6. Access Control Rules . . . . . . . . . . . . . . . . . 23 - 5.3. Access Control Enforcement Procedures . . . . . . . . . . 23 - 5.3.1. Initial Operation . . . . . . . . . . . . . . . . . . 24 - 5.3.2. Session Establishment . . . . . . . . . . . . . . . . 24 - 5.3.3. 'access-denied' Error Handling . . . . . . . . . . . . 24 - 5.3.4. Incoming RPC Message Validation . . . . . . . . . . . 24 - 5.3.5. Data Node Access Validation . . . . . . . . . . . . . 27 - 5.3.6. Outgoing Authorization . . . . . . . . . . 29 - 5.3.7. Outgoing Authorization . . . . . . . . 30 - 5.4. Data Model Definitions . . . . . . . . . . . . . . . . . . 33 - 5.4.1. High Level Procedures . . . . . . . . . . . . . . . . 33 - 5.4.2. Data Organization . . . . . . . . . . . . . . . . . . 33 - 5.4.3. YANG Module . . . . . . . . . . . . . . . . . . . . . 34 - 5.5. IANA Considerations . . . . . . . . . . . . . . . . . . . 50 - 5.6. Security Considerations . . . . . . . . . . . . . . . . . 50 - 6. Normative References . . . . . . . . . . . . . . . . . . . . . 52 - Appendix A. Usage Examples . . . . . . . . . . . . . . . . . . . 53 - A.1. Example . . . . . . . . . . . . . . . . . . . . . 53 - A.2. Example . . . . . . . . . . . . . . . . . . 54 - A.3. Example . . . . . . . . . . . . . . . . . . . . 55 - A.4. Example . . . . . . . . . . . . . . . . . . . 57 - A.5. Example . . . . . . . . . . . . . . . 59 - Appendix B. Open Issues . . . . . . . . . . . . . . . . . . . . . 60 - Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 61 - C.1. 00-01 . . . . . . . . . . . . . . . . . . . . . . . . . . 61 - C.2. 00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 62 + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 + 1.1.1. Requirements Notation . . . . . . . . . . . . . . . . 4 + 1.1.2. NETCONF Terms . . . . . . . . . . . . . . . . . . . . 4 + 1.1.3. YANG Terms . . . . . . . . . . . . . . . . . . . . . . 5 + 1.1.4. NACM Terms . . . . . . . . . . . . . . . . . . . . . . 5 + 2. Access Control Requirements . . . . . . . . . . . . . . . . . 6 + 2.1. Protocol Control Points . . . . . . . . . . . . . . . . . 6 + 2.2. Simplicity . . . . . . . . . . . . . . . . . . . . . . . . 7 + 2.3. Procedural Interface . . . . . . . . . . . . . . . . . . . 7 + 2.4. Datastore Access . . . . . . . . . . . . . . . . . . . . . 7 + 2.4.1. Access Rights . . . . . . . . . . . . . . . . . . . . 8 + 2.4.2. and Operations . . . . . . . . . . 8 + 2.4.3. Operation . . . . . . . . . . . . . . . 8 + 2.4.4. Operation . . . . . . . . . . . . . . . 9 + 2.5. Users and Groups . . . . . . . . . . . . . . . . . . . . . 10 + 2.6. Maintenance . . . . . . . . . . . . . . . . . . . . . . . 10 + 2.7. Configuration Capabilities . . . . . . . . . . . . . . . . 10 + 2.8. Identifying Security Holes . . . . . . . . . . . . . . . . 11 + 2.9. Data Shadowing . . . . . . . . . . . . . . . . . . . . . . 12 + 2.10. NETCONF Specific Requirements . . . . . . . . . . . . . . 12 + 3. NETCONF Access Control Model (NACM) . . . . . . . . . . . . . 14 + 3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 14 + 3.1.1. Features . . . . . . . . . . . . . . . . . . . . . . . 14 + 3.1.2. External Dependencies . . . . . . . . . . . . . . . . 15 + 3.1.3. Message Processing Model . . . . . . . . . . . . . . . 15 + 3.2. Model Components . . . . . . . . . . . . . . . . . . . . . 17 + 3.2.1. Users . . . . . . . . . . . . . . . . . . . . . . . . 17 + 3.2.2. Groups . . . . . . . . . . . . . . . . . . . . . . . . 18 + 3.2.3. Sessions . . . . . . . . . . . . . . . . . . . . . . . 18 + 3.2.4. Access Permissions . . . . . . . . . . . . . . . . . . 18 + 3.2.5. Global Enforcement Controls . . . . . . . . . . . . . 19 + 3.2.6. Access Control Rules . . . . . . . . . . . . . . . . . 19 + 3.3. Access Control Enforcement Procedures . . . . . . . . . . 19 + 3.3.1. Initial Operation . . . . . . . . . . . . . . . . . . 19 + 3.3.2. Session Establishment . . . . . . . . . . . . . . . . 20 + 3.3.3. 'access-denied' Error Handling . . . . . . . . . . . . 20 + 3.3.4. Incoming RPC Message Validation . . . . . . . . . . . 20 + 3.3.5. Data Node Access Validation . . . . . . . . . . . . . 23 + 3.3.6. Outgoing Authorization . . . . . . . . . . 26 + 3.3.7. Outgoing Authorization . . . . . . . . 26 + 3.4. Data Model Definitions . . . . . . . . . . . . . . . . . . 29 + 3.4.1. High Level Procedures . . . . . . . . . . . . . . . . 29 + 3.4.2. Data Organization . . . . . . . . . . . . . . . . . . 29 + 3.4.3. YANG Module . . . . . . . . . . . . . . . . . . . . . 30 + 3.5. IANA Considerations . . . . . . . . . . . . . . . . . . . 41 + 3.6. Security Considerations . . . . . . . . . . . . . . . . . 41 + 4. References . . . . . . . . . . . . . . . . . . . . . . . . . . 44 + 4.1. Normative References . . . . . . . . . . . . . . . . . . . 44 + 4.2. Informative References . . . . . . . . . . . . . . . . . . 44 + Appendix A. Usage Examples . . . . . . . . . . . . . . . . . . . 45 + A.1. Example . . . . . . . . . . . . . . . . . . . . . 45 + A.2. Example . . . . . . . . . . . . . . . . . . 46 + A.3. Example . . . . . . . . . . . . . . . . . . . . 47 + A.4. Example . . . . . . . . . . . . . . . . . . . 49 + A.5. Example . . . . . . . . . . . . . . . 51 + Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 52 + B.1. 01-02 . . . . . . . . . . . . . . . . . . . . . . . . . . 52 + B.2. 00-01 . . . . . . . . . . . . . . . . . . . . . . . . . . 52 + B.3. 00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 53 1. Introduction The NETCONF protocol does not provide any standard mechanisms to restrict the operations and content that each user is authorized to use. There is a need for inter-operable management of the controlled access to operator selected portions of the available NETCONF content within a particular server. - This document addresses NETCONF protocol authentication and access - control mechanisms for the Operation and Content layers, as defined - in [RFC4741], and [RFC5277]. It contains five main sections: - - 1. Authentication Requirements - - 2. Access Control Requirements + This document addresses access control mechanisms for the Operation + and Content layers of NETCONF, as defined in + [I-D.ietf-netconf-4741bis], and [RFC5277]. It contains three main + sections: - 3. NETCONF Authentication and Authorization Model + 1. Access Control Requirements - 4. NETCONF Access Control Model (NACM) + 2. NETCONF Access Control Model (NACM) - 5. YANG Data Model (ietf-nacm.yang) + 3. YANG Data Model (ietf-netconf-acm.yang) 1.1. Terminology 1.1.1. Requirements Notation 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]. 1.1.2. NETCONF Terms - The following terms are defined in RFC 4741 and are not redefined - here: + The following terms are defined in [I-D.ietf-netconf-4741bis] and are + not redefined here: o client + o datastore + o operation - o RPC operation + o protocol operation o server o session + o user -1.1.3. NACM Terms +1.1.3. YANG Terms + + The following terms are defined in [RFC6020] and are not redefined + here: + + o data node + +1.1.4. NACM Terms The following terms are used throughout this documentation: access control: A security feature provided by the NETCONF server, which allows an operator to restrict access to a subset of all NETCONF protocol operations and data, based on various criteria. access control model (ACM): A conceptual model used to configure and monitor the access control procedures desired by the operator to enforce a particular access control policy. @@ -194,286 +185,275 @@ access control rule: The conceptual criteria used to determine if a particular NETCONF protocol operation should be permitted or denied. authentication: The process of verifying a user's identity. superuser: The special administrative user account which is given unlimited NETCONF access, and is exempt from all access control enforcement. -2. Authentication Requirements - - The authentication mechanism must support password authentication - over RADIUS, to support deployment scenarios with centralized - authentication servers. Additionally, local users must be supported, - for scenarios when no centralized authentication server exists, or - for situations where the centralized authentication server cannot be - reached from the device. - - Since the mandatory transport protocol for NETCONF is SSH NETCONF - Over SSH [RFC4742], the authentication model must support SSH's - "publickey" and "password" authentication methods [RFC4252] - - The model for authentication configuration should be flexible enough - to support authentication methods defined by other standard documents - or by vendors. - -3. Access Control Requirements +2. Access Control Requirements -3.1. Protocol Control Points +2.1. Protocol Control Points The NETCONF protocol allows new operations to be added at any time, and the YANG data modeling language supports this feature. It is not possible to design an ACM for NETCONF which only focuses on a static set of operations, like some other protocols. Since few assumptions can be made about an arbitrary protocol operation, the NETCONF architectural server components must be protected at several conceptual control points. +-------------+ +-------------+ - client | RPC | | prune | client + client | protocol | | prune | client request --> | operation | | restricted | ---> reply | allowed? | | | +-------------+ | nodes? | | +-------------+ - | if any database or + | if any datastore or | state data is accessed | by the operation V +-------------+ +----------------+ | data node | | prune | | access | | restricted | | allowed? | | | ---> client +-------------+ | event or data? | session +----------------+ Figure 1 The following access control points are defined: - RPC operation: Configurable permission to invoke specific RPC - operations is required. Wildcard or multiple target mechanisms to - reduce configuration and effort are also required. + protocol operation: Configurable permission to invoke specific + protocol operations is required. Wildcard or multiple target + mechanisms to reduce configuration and effort are also required. - NETCONF database: Configurable permission to read and/or alter - specific data nodes within any conceptual database is required. + NETCONF datastore: Configurable permission to read and/or alter + specific data nodes within any conceptual datastore is required. Wildcard or multiple target mechanisms to reduce configuration and effort are also required. RPC Reply Content: Configurable permission to read specific data nodes within any conceptual RPC output section is required. Unauthorized data is silently omitted from the reply, instead of dropping the reply or sending an 'access-denied' error. Notification Content: Configurable permission to receive specific notification event types is required. -3.2. Simplicity +2.2. Simplicity Experience has shown that a complicated ACM will not be widely deployed, because it is too hard to use. The key factor that is ignored in such solutions is the concept of 'localized cost'. It should be easy to do simple things, and hard to do complex things, instead of hard to do everything. Configuration of the access control system must be simple to use. Simple and common tasks should be easy to configure, and require little expertise or domain-specific knowledge. Complex tasks should be possible using additional mechanisms which may require additional expertise. A single set of access control rules should be able to control all - types of NETCONF RPC operation invocation, all conceptual database - access, and all NETCONF session output. + types of NETCONF protocol operation invocation, all conceptual + datastore access, and all NETCONF session output. Default access control policy needs to be as secure as possible. Protocol access should be defined with a small and familiar set of - permissions, while still allowing full control of NETCONF database + permissions, while still allowing full control of NETCONF datastore access. Access control does not need to be applied to NETCONF messages. -3.3. Procedural Interface +2.3. Procedural Interface The NETCONF protocol uses a procedural interface model, and an extensible set of protocol operations. Access control for any possible protocol operation is required. It must be possible to configure the ACM to permit or deny access to specific NETCONF operations. YANG modules should be designed so that different access levels for - input parameters to RPC operations is not required. + input parameters to protocol operations is not required. -3.4. Database Access +2.4. Datastore Access - It must be possible control access to specific nodes and sub-trees - within the conceptual NETCONF database. + It must be possible to control access to specific nodes and sub-trees + within the conceptual NETCONF datastore. - In order for a user to obtain access to a particular database node, + In order for a user to obtain access to a particular datastore node, the user must be authorized to have the same requested access to the specified node, and all of its ancestors. - The same access control rules apply to all conceptual databases. For - example, the candidate configuration or the running configuration. + The same access control rules apply to all conceptual datastores. + For example, the candidate configuration or the running + configuration. - Only the standard NETCONF databases (candidate, running, and startup) - are controlled by the ACM. Local or remote files or databases - accessed via the parameter are optional to support. + Only the standard NETCONF datastores (candidate, running, and + startup) are controlled by the ACM. Local or remote files or + datastores accessed via the parameter are optional to support. The non-volatile startup configuration needs to be loaded into the running configuration without applying any access control rules. - Only a privileged user should be able to alter the factory-default - access control rules. - -3.4.1. Access Rights +2.4.1. Access Rights - A small set of hard-wired database access rights is needed to control - access to all possible NETCONF database operations, including vendor - extensions to the standard operation set. + A small set of hard-wired datastore access rights is needed to + control access to all possible NETCONF datastore operations, + including vendor extensions to the standard operation set. The familiar 'CRUDX' model can support all NETCONF operations: o Create: Allows the client to add a new data node instance to a - database. + datastore. o Read: Allows the client to read a data node instance from a - database, or receive the notification event type. + datastore, or receive the notification event type. o Update: Allows the client to update an existing data node instance - in a database. + in a datastore. o Delete: Allows the client to delete a data node instance from a - database. + datastore. o eXec: Allows the client to execute the protocol operation. -3.4.2. and Operations +2.4.2. and Operations - Read operations for restricted configuration data, either directly or - via wildcard access, are silently omitted from the - message. + Data nodes to which the client does not have 'read' access, either + directly or via wildcard access, are silently omitted from the message. -3.4.3. Operation +2.4.3. Operation - The NACM access rights are not directly coupled to the NETCONF - operation attribute, although they are similar. Instead, a NACM + The NACM access rights are not directly coupled to the + "operation" attribute, although they are similar. Instead, a NACM access right applies to all operations which would result in a - particular access operation to the target database. This section - describes how these access rights apply to the specific database + particular access operation to the target datastore. This section + describes how these access rights apply to the specific datastore operations supported by the operation. If the effective operation is 'none' (i.e., default-operation='none') for a particular data node, then no access control is applied to that data node. - A 'create', 'merge', or 'replace' operation on a database node which + A 'create', 'merge', or 'replace' operation on a datastore node which would result in the creation of a new data node instance, for which the user does not have 'create' access permission, is rejected with an 'access-denied' error. - A 'merge' or 'replace' operation on a database node which would + A 'merge' or 'replace' operation on a datastore node which would result in the modification of an existing data node instance, for which the user does not have 'update' access permission, is rejected with an 'access-denied' error. - A 'replace' or 'delete' operation on a database node which would - result in the deletion of an existing data node instance, for which - the user does not have 'delete' access permission, is rejected with - an 'access-denied' error. + A 'replace', 'delete', or 'remove' operation on a datastore node + which would result in the deletion of an existing data node instance, + for which the user does not have 'delete' access permission, is + rejected with an 'access-denied' error. A 'merge' operation may include data nodes which do not alter - portions of the existing database. For example, a container or list + portions of the existing datastore. For example, a container or list nodes may be present for naming purposes, which do not actually alter - the corresponding database node. These unaltered data nodes within + the corresponding datastore node. These unaltered data nodes within the scope of a 'merge' operation are ignored by the server, and do not require any access rights by the client. A 'merge' operation may include data nodes, but not include - particular child data nodes that are present in the database. These + particular child data nodes that are present in the datastore. These missing data nodes within the scope of a 'merge' operation are ignored by the server, and do not require any access rights by the client. - The contents of specific restricted database nodes must not be + The contents of specific restricted datastore nodes must not be exposed in any elements within the reply. -3.4.4. Operation +2.4.4. Operation Access control for the operation requires special consideration because the operator is replacing the entire target - database. Write access to the entire database is needed for this - operation to succeed. + datastore. Read access to the entire source datastore, and write + access to the entire target datastore is needed for this operation to + succeed. - A client must have access to every database node, even ones that are + A client must have access to every datastore node, even ones that are not present in the source configuration data. For example, consider a common use-case such as a simple backup and restore procedure. The operator must have full read access to the - database in order to receive a complete copy of its contents. If + datastore in order to receive a complete copy of its contents. If not, the server will simply omit these sub-trees from the reply. If - that copy is later used to restore the server database, the server + that copy is later used to restore the server datastore, the server will interpret the missing nodes as a request to delete those nodes, and return an error. -3.5. Users and Groups +2.5. Users and Groups The server must obtain a user name from the underlying NETCONF transport, such as an SSH user name. It must be possible to specify access control rules for a single user or a configurable group of users. A configurable superuser account is needed which bypasses all access control rules. This is needed in case the access control rules are mis-configured, and all access is denied. The ACM must support the concept of administrative groups, to support the well-established distinction between a root account and other types of less-privileged conceptual user accounts. These groups must be configurable by the operator. -3.6. Maintenance + It must be possible to delegate the user-to-group mapping to a + central server, such as RADIUS [RFC2865] [RFC5607]. Since + authentication is performed by the NETCONF transport layer, and + RADIUS performs authentication and service authorization at the same + time, it must be possible for the underlying NETCONF transport to + report a set of group names associated with the user to the server. + +2.6. Maintenance It should be possible to disable part or all of the access control model without deleting any configuration. By default, only the 'superuser' should be able to perform this task. It should be possible to configure a 'superuser' account so that all access control is disabled for just this user. This allows the access control rules to always be modified without completely disabling access control for all users. -3.7. Configuration Capabilities +2.7. Configuration Capabilities Suitable control and monitoring mechanisms are needed to allow an operator to easily manage all aspects of the ACM behavior. A standard data model, suitable for use with the operation must be available for this purpose. Access control rules to restrict operations on specific sub-trees - within the configuration database must be supported. Existing + within the configuration datastore must be supported. Existing mechanisms should be used to identify the sub-tree(s) for this purpose. -3.8. Identifying Security Holes +2.8. Identifying Security Holes One of the most important aspects of the data model documentation, and biggest concerns during deployment, is the identification of security-sensitive content. This applies to operations in NETCONF, not just data and notifications. - It is customary for security-sensitive objects to be documented in + It is mandatory for security-sensitive objects to be documented in the Security Considerations section of an RFC. This is nice, but it is not good enough, for the following reasons: o This documentation-only approach forces operators to study the RFC and determine if there are any potential security holes introduced by a new YANG module. o If any security holes are identified, then the operator must study some more RFC text, and determine how to close the security hole(s). @@ -486,255 +466,138 @@ of vulnerability, after the new module is loaded, and before the new access control rules for that module are configured, enabled, and debugged. Often, the operator just wants to disable default access to the secure content, so no inadvertent or malicious changes can be made to the server. This allows the default rules to be more lenient, without significantly increasing the security risk. A data model designer should be able to use machine-readable - statements to identity NETCONF content which should be protected by + statements to identify NETCONF content which should be protected by default. This will allow client and server tools to automatically close data-model specific security holes, by denying access to sensitive data unless the user is explicitly authorized to perform the requested operation. -3.9. Data Shadowing +2.9. Data Shadowing One of the more complicated security administration problems is identifying data nodes which shadow or mirror the content of another data node. An access control rule to prevent read operations for a particular node may be insufficient to prevent access to the data node with the copied value. If the YANG leafref data type is used, then this data shadowing can be detected by applications (and the server stack), and prevented. If the description statement, other documentation, or no documentation exists to identify a data shadow problem, then it may not be detected. Since NETCONF allows any vendor operation to be added to the protocol, there is no way to reliably identify all of the operations that may expose copies of sensitive data nodes in messages. - A NETCONF server must insure than unauthorized access to its - conceptual databases and non-configuration data nodes is prevented. + A NETCONF server must ensure that unauthorized access to its + conceptual datastores and non-configuration data nodes is prevented. It is beyond the scope of this document to define access control enforcement procedures for underlying device instrumentation that may exist to support the NETCONF server operation. An operator must identify each operation that the server provides, and decide if it needs any access control applied to it. Proprietary protocol operations should be properly documented by the vendor, so it is clear to operators what data nodes (if any) are affected by the operation, and what information (if any) is returned in the message. -3.10. NETCONF Specific Requirements +2.10. NETCONF Specific Requirements - The server must be able to identify the specific protocol access + The server MUST be able to identify the specific protocol access request at the 4 access control points defined above. - The server must be able to identify any database access request, even - for proprietary operations. + The server MUST be able to identify any datastore access request, + even for proprietary operations. - A session must always be authorized to invoke the - operation, defined in [RFC4741]. + A client MUST always be authorized to invoke the + operation, defined in [I-D.ietf-netconf-4741bis]. - A session must always be authorized to receive the + A client MUST always be authorized to receive the and notification events, defined in [RFC5277] - - The set of module name strings used within one particular server must + The set of module name strings used within one particular server MUST be unique. - Within a single server, the module namespace URI associated with a - specific module name string must persist across a reboot, and never - change, once assigned. - -4. NETCONF Authentication and Authorization Model - - This document defines three authentication methods for use with - NETCONF: - - publickey for local users over SSH - password for local users over any transport - password for RADIUS users over any transport - - Additional methods may be defined by other standard documents or by - vendors. - - Conceptually, the NETCONF transport subsystem authenticates the user, - and passes the name of the authenticated user to the NETCONF server. - The NETCONF server authorizes the user by mapping it to one or more - groups. Access to specific operations and content is then controlled - by access control rules as described in Section 5. - - Some protocols, such as RADIUS, performs both authentication and - authorization, and has a mechanism to report authorization attributes - to the client. These attributes are made available to the NETCONF - server in an implementation specific manner. - - This document defines two optional YANG features, 'local-users' and - 'radius', which the server advertises to indicate support for - configuring local users on the device, and for configuring RADIUS - access, respectively. - -4.1. SSH Public Key Authentication - - If the NETCONF server advertises the 'local-users' feature, - configuration of local users and their SSH public keys is supported - in the /nacm/authentication/user list. - - Public key authentication is requested by the SSH client. The SSH - server looks up the user name provided by the client in the /nacm/ - authentication/user list, and verifies the key as described in - [RFC4253]. - - If the 'local-users' feature is supported, then when a NETCONF client - starts an SSH session towards the server, using the "publickey" - authentication 'method name' [RFC4252], the SSH server looks up the - user name given in the SSH authentication request in the /nacm/ - authentication/user list, - -4.2. Local User Password Authentication - - If the NETCONF server advertises the 'local-users' feature, - configuration of local users and their passwords is supported in the - /nacm/authentication/user list. - - For NETCONF transport protocols that support password authentication, - the leaf-list 'user-authentication-order' is used to control if local - user password authentication should be used. - - In SSH, password authentication is requested by the client. Other - NETCONF transport protocols may also support password authentication. - - When local user password authentication is requested, the NETCONF - transport looks up the user name provided by the client in the /nacm/ - authentication/user list, and verifies the password. - -4.3. RADIUS Password Authentication and Service Authorization - - If the NETCONF server advertises the 'radius' feature, it supports - user authentication and service authorization with RADIUS, as - described in this section. - - For NETCONF transport protocols that support password authentication, - the leaf-list 'user-authentication-order' is used to control if - RADIUS password authentication should be used. - - In SSH, password authentication is requested by the client. Other - NETCONF transport protocols may also support password authentication. - -4.3.1. Operation - - [Editor's Note: I prefer to keep this section short, and just refer - to the relevant rfcs which have detailed information on radius usage, - instead of duplicating this info here...] - - When RADIUS user authentication is requested, the NETCONF transport - subsystem acts as a RADIUS client. In the Access-Request request - [RFC2865], the following RADIUS attributes SHOULD be sent by the - client [RFC5607]: - - o Service-Type with the value Framed-Management - - o Framed-Management-Protocol with the value NETCONF - - o Management-Transport-Protection with the value Integrity- - Confidentiality-Protection - - As described in RFC 5607, if an Access-Accept message is received - which does not authorize the requested service, access MUST be - denied. - - If any Management-Policy-Id attributes are present in the Access- - Accept message, they are treated as group names in the access control - procedure, as described in Section 5. - - The following RADIUS attributes MAY be sent by the RADIUS server: - - o Session-Timeout - - o Idle-Timeout - - See [RFC2865] for a description of these attributes. These timeout - values MUST be enforced by the NETCONF server. - -5. NETCONF Access Control Model (NACM) +3. NETCONF Access Control Model (NACM) -5.1. Introduction +3.1. Introduction This section provides a high-level overview of the access control model structure. It describes the NETCONF protocol message processing model, and the conceptual access control requirements within that model. -5.1.1. Features +3.1.1. Features The NACM data model provides the following features: o Independent control of RPC, data, and notification access. o Very simple access control rules configuration data model which is easy to use. o The concept of a 'superuser' type of account is supported, but configuration such an account is beyond the scope of this document. The server must be able to determine if a superuser account is available, and if so, the actual user name for this account. A session associated with the superuser account will bypass all access control enforcement. - o A simple and familiar set of database permissions is used. + o A simple and familiar set of datastore permissions is used. o Support for YANG security tagging (e.g., nacm:secure extension) allows default security modes to automatically exclude sensitive data. o Separate default access modes for read, write, and execute permissions. o Access control rules are applied to configurable groups of users. o The entire ACM can be disabled during operation, in order to debug operational problems. o Access control rules are simple to configure. - o The number of denied RPC operation requests and denied database - write requests can be monitored by the client. + o The number of denied protocol operation requests and denied + datastore write requests can be monitored by the client. o Simple unconstrained YANG instance identifiers are used to - configure access control rules for specific data nodes, or child - nodes within specific RPC input, RPC output, and notification - event type content. + configure access control rules for specific data nodes. -5.1.2. External Dependencies +3.1.2. External Dependencies - The NETCONF [RFC4741] protocol is used for all management purposes - within this document. The server must support the features - identified by the 'NETCONF-base' capability. It is expected that the - mandatory transport mapping NETCONF Over SSH [RFC4742] is also - supported by the server, and that the server has access to the user - name associated with each session. + The NETCONF [I-D.ietf-netconf-4741bis] protocol is used for all + management purposes within this document. It is expected that the + mandatory transport mapping NETCONF Over SSH + [I-D.ietf-netconf-rfc4742bis] is also supported by the server, and + that the server has access to the user name associated with each + session. The YANG Data Modeling Language [RFC6020] is used to define the NETCONF data models specified in this document. The YANG instance- - identifier data type can be used to configure data-node-specific - access control rules. + identifier data type is used to configure data-node-specific access + control rules. -5.1.3. Message Processing Model +3.1.3. Message Processing Model The following diagram shows the NETCONF message flow model, including the points at which access control is applied, during NETCONF message processing. +-------------------------+ | session | | (username) | +-------------------------+ | ^ @@ -758,212 +621,204 @@ | | ^ ^ V +----------------+ | | +===========+ | | | | data node | | | | | acc. ctl | -----------+ | | | +===========+ | | | | | | | | | V V V | | +---------------+ +-----------------+ | configuration | ---> | server | - | database | | instrumentation | + | datastore | | instrumentation | | | <--- | | +---------------+ +-----------------+ Figure 2 The following high-level sequence of conceptual processing steps is executed for each received message, if access control enforcement is enabled: o Access control is applied to all messages (except ) received by the server, individually, for each active - session, unless the user identity for the session is the - 'superuser'. + session, unless the session is associated with the 'superuser' + account. o If the session is authorized to execute the specified RPC operation, then processing continues, otherwise the request is rejected with an 'access-denied' error. - o If the configuration database or conceptual state data is accessed - by the RPC operation, then the configuration access must be - authorized first. If the session is authorized to perform the + o If the configuration datastore or conceptual state data is + accessed by the protocol operation, then the data node access must + be authorized. If the session is authorized to perform the requested operation on the requested data, then processing continues. The following sequence of conceptual processing steps is executed for each generated notification event, if access control enforcement is enabled: o Server instrumentation generates a conceptual notification, for a particular subscription. o The notification access control enforcer checks the notification event type, and if it is one which the session is not authorized to read, then the notification is dropped for that subscription. -5.2. Model Components +3.2. Model Components This section defines the conceptual components related to access control model. -5.2.1. Users +3.2.1. Users - A 'user' is the conceptual identity, which is associated with the + A 'user' is the conceptual entity, which is associated with the access permissions granted to a particular session. A user is identified by a string which must be unique within the server. - The user name string is usually derived from the transport layer - during session establishment. A server is required to have an - authenticated user name for a session before requests will be - accepted. Otherwise all write requests must be rejected with an - 'access-denied' error-tag value. If a read operation is not - authorized, then the requested data is silently dropped from the - reply. + As described in [I-D.ietf-netconf-4741bis], the user name string is + derived from the transport layer during session establishment. If + the transport layer cannot authenticate the user, the session is + terminated. The server MAY support a 'superuser' administrative user account, which will bypass all access control enforcement. This is useful for restricting initial access and repairing a broken access control configuration. This account may be configurable to use a specific user, or disabled completely. Some systems have factory-selected superuser account names. There is no need to standardize the exact user name for the superuser account. If no such account exists, then all NETCONF access will be controlled by NACM. -5.2.2. Groups +3.2.2. Groups Access to a specific NETCONF operation is granted to a session, associated with a group, not a user. A group is identified by its name. All group names must be unique within the server. A group member is identified by a user name string. The same user may be configured in multiple groups. - The server should support the 3 default group identities defined in - this document (admin, monitor, guest), however these roles are just - unique identities, provided for operator convenience. There is no - standard behavior defined for each group identity. That is up to the - operator who configures the groups. - -5.2.3. Sessions +3.2.3. Sessions A session is simply a NETCONF session, which is the entity which is granted access to specific NETCONF operations. A session is associated with a single user name for the lifetime of the session. -5.2.4. Access Permissions +3.2.4. Access Permissions The access permissions are the NETCONF protocol specific set of - permissions that have been assigned to a particular session role or - group. + permissions that have been assigned to a particular session. The same access permissions MUST stay in effect for the processing of a particular message. The server MUST use the access control rules in effect at the time the message is processed. - The access control model treats RPC operation execution separately - from configuration database access and outgoing messages: + The access control model treats protocol operation execution + separately from configuration datastore access and outgoing messages: create: Permission to create conceptual server data. read: Read access to conceptual server data, and content. update: Permission to modify existing conceptual server data. delete: Permission to delete existing conceptual server data. - exec: Permission to invoke an RPC operation. + exec: Permission to invoke an protocol operation. -5.2.5. Global Enforcement Controls +3.2.5. Global Enforcement Controls A global on/off switch is provided to enable or disable all access control enforcement. An on/off switch is provided to enable or disable default access to - invoke RPC operations. + invoke protocol operations. An on/off switch is provided to enable or disable default permission to receive data in replies and notifications. An on/off switch is provided to enable or disable default access to alter configuration data. -5.2.6. Access Control Rules +3.2.6. Access Control Rules There are 4 types of rules available in NACM: module rule: Controls access for definitions in a specific module, identified by its name. - RPC operation rule: Controls access for a specific RPC operation, - identified by its module and name. + protocol operation rule: Controls access for a specific protocol + operation, identified by its module and name. data node rule: Controls access for a specific data node, identified by its path location within the conceptual XML document for the data node. notification rule: Controls access for a specific notification event type, identified by its module and name. -5.3. Access Control Enforcement Procedures +3.3. Access Control Enforcement Procedures There are seven separate phases that must be addressed, four of which are related to the NETCONF message processing model. In addition, the initial start-up mode for a NETCONF server, session establishment, and 'access-denied' error handling procedures must also be considered. -5.3.1. Initial Operation +3.3.1. Initial Operation Upon the very first start-up of the NETCONF server, the access control configuration will probably not be present. If not, a server - should not allow any write access to any session role except + MUST NOT allow any write access to any session role except 'superuser' type of account in this state. There is no requirement to enforce access control rules before or while the non-volatile configuration data is processed and loaded into the running configuration. -5.3.2. Session Establishment +3.3.2. Session Establishment The access control model applies specifically to the well-formed XML content transferred between a client and a server, after session establishment has been completed, and after the exchange has been successfully completed. A server should not include any sensitive information in any elements within the exchange. Once session establishment is completed, and a user identity has been - authenticated, a NETCONF server will enforce the access control - rules, based on the supplied user identity and the configuration data - stored on the server. + authenticated, the NETCONF transport layer reports the username and a + possibly empty set of group names associated with the user to the + NETCONF server. The NETCONF server will enforce the access control + rules, based on the supplied user identity, group names, and the + configuration data stored on the server. -5.3.3. 'access-denied' Error Handling +3.3.3. 'access-denied' Error Handling The 'access-denied' error-tag is generated when the access control - system denies access to either a request to invoke an RPC operation - or a request to perform a particular operation on the configuration - database. + system denies access to either a request to invoke a protocol + operation or a request to perform a particular operation on the + configuration datastore. A server must not include any sensitive information in any elements within the response. -5.3.4. Incoming RPC Message Validation +3.3.4. Incoming RPC Message Validation The diagram below shows the basic conceptual structure of the access control processing model for incoming NETCONF messages, within a server. NETCONF server +------------+ | XML | | message | | dispatcher | @@ -982,136 +837,139 @@ +-----------+ +---------------+ +------------+ | acme NS | | NC-base NS | | NC-base NS | | | | | | | +-----------+ +---------------+ +------------+ | | | | V V +----------------------+ | | | configuration | - | database | + | datastore | +----------------------+ Figure 3 Access control begins with the message dispatcher. Only well-formed XML messages should be processed by the server. After the server validates the element, and determines the - namespace URI and the element name of the RPC operation being + namespace URI and the element name of the protocol operation being requested, the RPC access control enforcer verifies that the session - is authorized to invoke the RPC operation. + is authorized to invoke the protocol operation. - The RPC operation is authorized by following these steps: + The protocol operation is authorized by following these steps: - 1. If the parameter is set to 'false', then the RPC - operation is permitted. + 1. If the parameter is set to 'false', then the + protocol operation is permitted. 2. If the session is associated with the 'superuser' account, then - the RPC operation is permitted. + the protocol operation is permitted. 3. If the requested operation is the NETCONF - operation, then the RPC operation is permitted. + operation, then the protocol operation is permitted. 4. Check all the entries for ones that contain a entry that matches the user name for the session making - the request. + the request. Add to these groups the set of groups provided by + the transport layer. 5. If no groups are found: - * If the requested RPC operation is associated with a YANG + * If the requested protocol operation is associated with a YANG module advertised in the server capabilities, and the rpc statement contains a nacm:secure or nacm:very-secure - extension, then the RPC operation is denied. + extension, then the protocol operation is denied. * If the parameter is set to 'permit', then - permit the RPC operation, otherwise deny the request. + permit the protocol operation, otherwise deny the request. 6. Check if there are any matching entries for the - requested RPC operation. Any matching rules are processed in - user-defined order, in case there are multiple - entries for the requested RPC operation. + requested protocol operation. Any matching rules are processed + in user-defined order, in case there are multiple + entries for the requested protocol operation. 7. If an entry is found, then check the bits field for the entry, otherwise continue. The 'exec' bit MUST be present in the bits field for an , so it is not used in this procedure. - 8. If the entry is considered a match, the the 'nacm- - action' leaf is checked. If is equal to 'permit', then the RPC - operation is permitted, otherwise it is denied. + 8. If the entry is considered a match, then the 'nacm- + action' leaf is checked. If is equal to 'permit', then the + protocol operation is permitted, otherwise it is denied. 9. Check if there are any matching entries for the - same module as the requested RPC operation. Any matching rules - are processed in user-defined order, in case there are multiple - entries for the module containing the requested - RPC operation. + same module as the requested protocol operation. Any matching + rules are processed in user-defined order, in case there are + multiple entries for the module containing the + requested protocol operation. 10. If a entry is found, then check the bits field for the entry, otherwise continue. If the 'exec' bit is present in the bits field then the RPC rule is considered a match. otherwise it is not considered to match the request. - 11. If the entry is considered a match, the the 'nacm- - action' leaf is checked. If is equal to 'permit', then the RPC - operation is permitted, otherwise it is denied. + 11. If the entry is considered a match, then the + 'nacm-action' leaf is checked. If is equal to 'permit', then + the protocol operation is permitted, otherwise it is denied. 12. If the requested operation is identified an a nacm:secure or - nacm:very-secure RPC operation, then the RPC operation is - denied. + nacm:very-secure protocol operation, then the protocol operation + is denied. 13. If the parameter is set to 'permit', then permit - the RPC operation, otherwise the RPC operation is denied. + the protocol operation, otherwise the protocol operation is + denied. - If the session is not authorized to invoke the RPC operation then an - is generated with the following information: + If the session is not authorized to invoke the protocol operation + then an is generated with the following information: error-tag: access-denied error-path: /rpc/method-QName, where 'method-QName' is a qualified - name identifying the actual RPC operation name. For example, + name identifying the actual protocol operation name. For example, '/rpc/edit-config' represents the operation in the NETCONF base namespace. - If the configuration database is accessed, either directly or as a - side effect of the RPC operation, then the server must intercept the - operation and make sure the session is authorized to perform the + If the configuration datastore is accessed, either directly or as a + side effect of the protocol operation, then the server MUST intercept + the operation and make sure the session is authorized to perform the requested operation on the specified data. -5.3.5. Data Node Access Validation +3.3.5. Data Node Access Validation - If a data node within a configuration database is accessed, or a - conceptual non-configuration node is accessed, then the server must + If a data node within a configuration datastore is accessed, or a + conceptual non-configuration node is accessed, then the server MUST ensure that the client session is authorized to perform the requested operation create, read, update, or delete operation on the specified data node. The data node access request is authorized by following these steps: 1. If the parameter is set to 'false', then the data node access request is permitted. 2. If the session is associated with the 'superuser' account, then the data node access request is permitted. 3. Check all the entries for ones that contain a entry that matches the user name for the session making - the request. + the request. Add to these groups the set of groups provided by + the transport layer. 4. If no groups are found: * If the requested data node is associated with a YANG module advertised in the server capabilities, and the data - definition statements (or any of its ancestors) contains a - nacm:secure or nacm:very-secure extension, then the data node + definition statement or any of its ancestors contains a nacm: + secure or nacm:very-secure extension, then the data node access request is denied. * For a read request, if the parameter is set to 'permit', then permit the data node access request, otherwise deny the request. For a read operation, this means that the requested node is not included in the rpc-reply. * For a write request, if the parameter is set to 'permit', then permit the data node access request, otherwise deny the request. @@ -1133,21 +991,21 @@ be a match. 3. For an update (e.g., 'merge' or 'replace') operation, if the 'update' bit is present in the bits field then the entry is considered to be a match. 4. For a deletion (e.g., 'delete') operation, if the 'delete' bit is present in the bits field then the entry is considered to be a match. - 7. If the entry is considered a match, the the 'nacm- + 7. If the entry is considered a match, then the 'nacm- action' leaf is checked. If it is equal to 'permit', then the data operation is permitted, otherwise it is denied. For 'read' operations, 'denied' means the requested data is not returned in the reply. 8. Check if there are any matching entries for the same module as the requested data node. Any matching rules are processed in user-defined order, in case there are multiple entries for the module containing the requested data node. @@ -1164,54 +1022,54 @@ be a match. 3. For an update (e.g., 'merge' or 'replace') operation, if the 'update' bit is present in the bits field then the entry is considered to be a match. 4. For a deletion (e.g., 'delete') operation, if the 'delete' bit is present in the bits field then the entry is considered to be a match. - 10. If the entry is considered a match, the the 'nacm- - action' leaf is checked. If it is equal to 'permit', then the - data operation is permitted, otherwise it is denied. For 'read' - operations, 'denied' means the requested data is not returned in - the reply. + 10. If the entry is considered a match, then the + 'nacm-action' leaf is checked. If it is equal to 'permit', then + the data operation is permitted, otherwise it is denied. For + 'read' operations, 'denied' means the requested data is not + returned in the reply. 11. For a read request, if the requested data node is identified an a nacm:very-secure definition, then the requested data node is not included in the reply. 12. For a write request, if the requested data node is identified an a nacm:secure or nacm:very-secure definition, then the data node access request is denied. 13. For a read request, if the parameter is set to 'permit', then include the requested data in the reply, - otherwise do not inlcude the requested data in the reply. + otherwise do not include the requested data in the reply. 14. For a write request, if the parameter is set to 'permit', then permit the data node access request, otherwise deny the request. -5.3.6. Outgoing Authorization +3.3.6. Outgoing Authorization The message should be checked by the server to make sure no unauthorized data is contained within it. If so, the restricted data must be removed from the message before it is sent to the client. - For RPC operations which do not access any data nodes, then any - client authorized to invoke the RPC operation is also authorized to - receive the for that RPC operation. + For protocol operations which do not access any data nodes, then any + client authorized to invoke the protocol operation is also authorized + to receive the for that protocol operation. -5.3.7. Outgoing Authorization +3.3.7. Outgoing Authorization The message should be checked by the server to make sure no unauthorized data is contained within it. If so, the restricted data must be removed from the message before it is sent to the client. Configuration of access control rules specifically for descendent nodes of the notification event type element are outside the scope of this document. If the session is authorized to receive the notification event type, then it is also authorized to receive any @@ -1241,41 +1099,42 @@ +=================+ ^ | +------------------------+ | server instrumentation | +------------------------+ | ^ V | +----------------------+ | configuration | - | database | + | datastore | +----------------------+ Figure 4 The generation of a notification event for a specific subscription is authorized by following these steps: 1. If the parameter is set to 'false', then the notification event is permitted. 2. If the session is associated with the 'superuser' account, then the notification event is permitted. 3. If the requested operation is the NETCONF or event type, then the notification event is permitted. 4. Check all the entries for ones that contain a entry that matches the user name for the session that - started the notification subscription. + started the notification subscription. Add to these groups the + set of groups provided by the transport layer. 5. If no groups are found: * If the requested notification is associated with a YANG module advertised in the server capabilities, and the notification statement contains a nacm:secure or nacm:very- secure extension, then the notification event is dropped for the associated subscription. * If the parameter is set to 'permit', then @@ -1307,65 +1166,62 @@ dropped for the associated subscription. 10. If the requested event type is identified an a nacm:very-secure notification definition, then the notification event type is denied. 11. If the parameter is set to 'permit', then permit the notification event type, otherwise it is dropped for the associated subscription. -5.4. Data Model Definitions +3.4. Data Model Definitions This section defines the semantics of the conceptual data structures - found in the data model in Section 5.4. + found in the data model in Section 3.4. -5.4.1. High Level Procedures +3.4.1. High Level Procedures There are some high level management procedures that an administrator needs to consider before using this access control model: 1. Configure the global settings. 2. Configure one or more user groups. 3. Configure zero or more access control rules for specific modules. - 4. Configure zero or more access control rules for specific RPC + 4. Configure zero or more access control rules for specific protocol operations. 5. Configure zero or more access control rules for data node access. 6. Configure zero or more access control rules for notification event type access. -5.4.2. Data Organization +3.4.2. Data Organization The top-level element is called , and it is defined in the - 'nacm' module namespace. + 'ietf-netconf-acm' module namespace. There are several data structures defined as child nodes of the element: leaf : On/off boolean switch to enable or disable access control enforcement. - container : Configuration of the NETCONF server user - authentication mechanisms. - leaf : Enumeration to permit or deny default read access requests. leaf : Enumeration to permit or deny default write access requests. - leaf : Enumeration to permit or deny default RPC + leaf : Enumeration to permit or deny default protocol operation execution requests. leaf : Read-only counter of the number of times the server has denied an RPC operation request, since the last reboot of the server. leaf : Read-only counter of the number of times the server has denied a data node write request, since the last reboot of the server. @@ -1374,52 +1230,47 @@ list : A list of user names belonging to the same administrative group. container : Configures the access control rules used within the server. list : Configures the access control rules for a specific module. - list : Configures the access control rules for RPC + list : Configures the access control rules for protocol operation invocation. list : Configures the access control rules for - configuration database access. + configuration datastore access. list : Configures the access control rules for controlling delivery of events. -5.4.3. YANG Module +3.4.3. YANG Module The following YANG module is provided to specify the normative NETCONF content that must by supported by the server. - The ietf-nacm YANG module imports typedefs from [RFC6021]. + The ietf-netconf-acm YANG module imports typedefs from [RFC6021]. // RFC Ed.: please update the date to the date of publication - file="ietf-nacm@2010-10-25.yang" + file="ietf-netconf-acm@2011-02-03.yang" - module ietf-nacm { + module ietf-netconf-acm { - namespace "urn:ietf:params:xml:ns:yang:ietf-nacm"; + namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-acm"; prefix "nacm"; import ietf-yang-types { prefix yang; - - } - - import ietf-inet-types { - prefix inet; } organization "IETF NETCONF (Network Configuration) Working Group"; contact "WG Web: WG List: WG Chair: Mehmet Ersue @@ -1430,44 +1281,45 @@ Editor: Andy Bierman Editor: Martin Bjorklund "; description "NETCONF Server Access Control Model. - Copyright (c) 2010 IETF Trust and the persons identified as + Copyright (c) 2011 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Simplified BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info). - This version of this YANG module is part of RFC XXX; see + This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; - // RFC Ed.: replace XXXX with actual RFC number and remove this note - - //reference "RFC XXXX"; + // RFC Ed.: replace XXXX with actual RFC number and + // remove this note // RFC Ed.: remove this note - // Note: extracted from draft-ietf-netconf-access-control-01.txt + // Note: extracted from draft-ietf-netconf-access-control-02.txt + // RFC Ed.: please update the date to the date of publication - revision "2010-10-25" { + revision "2011-02-03" { description "Initial version"; reference - "RFC XXXX: Network Configuration Protocol Access Control Model"; + "RFC XXXX: Network Configuration Protocol + Access Control Model"; } /* * Extension statements */ extension secure { description "Used to indicate that the data model node represents a sensitive security system parameter. @@ -1491,77 +1343,20 @@ the designated 'superuser' to have read, write, or execute default nacm-rights-type for the node. An explicit access control rule is required for all other users. The 'very-secure' extension may appear within a data, rpc, or notification node definition. It is ignored otherwise."; } /* - * Features - */ - - feature authentication { - description - "Indicates that the NETCONF server can be configured - to do authentication of users."; - } - - feature radius { - if-feature authentication; - description - "Indicates that the NETCONF server can be - configured to act as a NAS and authenticate users - with RADIUS."; - reference - "RFC 2865: Remote Authentication Dial In User Service (RADIUS) - RFC 5607: Remote Authentication Dial-In User Service (RADIUS) - Authorization for Network Access Server (NAS) - Management"; - } - - feature local-users { - if-feature authentication; - description - "Indicates that the NETCONF server supports - local user authentication."; - } - - /* - * Identities - */ - - identity authentication-method { - description - "Base identity for NETCONF authentication methods."; - } - - identity radius { - base authentication-method; - description - "Indicates NETCONF authentication using RADIUS."; - reference - "RFC 2865: Remote Authentication Dial In User Service (RADIUS) - RFC 5607: Remote Authentication Dial-In User Service (RADIUS) - Authorization for Network Access Server (NAS) - Management"; - } - - identity local-users { - base authentication-method; - description - "Indicates password-based NETCONF authentication using locally - configured users."; - } - - /* * Derived types */ typedef nacm-user-name-type { type string { length "1..max"; } description "General Purpose User Name string."; } @@ -1672,200 +1466,26 @@ 'USER', which contains the name of user of the current session. o The function library is the core function library, but note that due to the syntax restrictions of an instance-identifier, no functions are allowed. o The context node is the root node in the data tree."; } - typedef md5-crypt { - type string { - pattern "$0$.* | $1$[a-zA-Z0-9./]{2,8}$.*"; - } - description - "The md5-crypt type is used to store a password hash based on the - MD5 message digest algorithm. When a clear text value is set to - a leaf of this type, the server calculates a MD5 password hash, - and stores the result in the datastore. Thus, the password is - never stored in clear text. - - When a leaf of this type is read, the stored password hash is - returned. - - A value of this type matches one of the forms: - - $0$ - $1$$ - - The '$0$' prefix signals that the value is clear text. When - such a value is received by the server, an MD5 digest is - calculated, and the string '$1$$' is prepended to the - result, where is a random 2-8 characters long salt used - to generate the digest. This value is stored in the - configuration data store. - - If a value starting with '$1$$' is received, the server - knows that the value already represents an MD5 digest, and - stores it as is in the data store. - - When a server needs to verify a password given by a user, it - finds the stored password hash string for that user, extracts - the salt, and calculates the hash with the salt and given - password as input. If the calculated hash value is the same as - the stored value, the password given by the client is correct. - - The digest algorithm is the md5 crypt function used for - encrypting passwords for various UNIX systems."; - reference - "RFC 1321: The MD5 Message-Digest Algorithm - http://en.wikipedia.org/wiki/Crypt_(Unix)"; - // FIXME: ref to wikipedia ok?? - } - container nacm { nacm:very-secure; - presence - "An empty nacm container indicates that the - NACM service is running, and using - all default parameters."; - description "Parameters for NETCONF Access Control Model."; - container authentication { - nacm:very-secure; - if-feature authentication; - - description - "The authentication configuration for the - NETCONF server."; - - leaf-list user-authentication-order { - type identityref { - base authentication-method; - } - must '(. = "nacm:radius" and ../radius/server) or' - + '(. != "nacm:radius")' { - error-message - "When 'radius' is used, a radius server - must be configured."; - } - ordered-by user; - - description - "When the NETCONF server authenticates a user with - a password, it tries the authentication methods in this - leaf-list in order. If authentication with one method - fails, the next method is used. If no method succeeds, - the user is denied access. - - If the 'radius' feature is advertised by the NETCONF - server, the 'radius' identity can be added to this - list. - - If the 'local-users' feature is advertised by the - NETCONF server, the 'local-users' identity can be - added to this list."; - } - - container radius { - if-feature radius; - - description - "The radius configuration for the NETCONF server."; - - list server { - key address; - - description - "The radius server configuration used by - the NETCONF server."; - - leaf address { - type inet:host; - description - "The address of the radius server."; - } - leaf port { - type inet:port-number; - default "1812"; - description - "The port number of the radius server."; - } - leaf shared-secret { - type string; // FIXME - /* - We're using a special type aes-cfb-128-encrypted-string which works - like the md5-crypt string, but encrypts the clear text value using a - pre-provisioned password (not part of the config db!). - - We use $0$ for cleartext and $4$ for the encrypted value. - (we also have a des-version which uses $3$). - - But I was thinking that maybe we could define a type for encrypted - values without specifying the encryption algorithm, just specifying - the format. $0$ | $x$, and how it is - encrypted is implementation specific. - - One alternative is to store this shared secret in clear text. It is - transmitted over a secure transport, and marked as very-secure. (The - same argument could be made for user passwords, but these are - personal and not even root should be able to read my passwd in clear - text, so it makes more sense to keep them hidden.) - */ - description - "The shared secret which is known to both the RADIUS - client and server."; - reference - "RFC 2865: Remote Authentication Dial In User Service"; - } - /* - How about configuration of number of retransmits - and timeout? - */ - } - } - - list user { - if-feature local-users; - key name; - - description - "The list of local users configured on this device."; - - leaf name { - type nacm-user-name-type; - description - "The user name string identifying this entry."; - - } - leaf password { - type md5-crypt; - description - "The password for this entry."; - } - leaf ssh-dsa { - type binary; - description - "The public DSA key for this entry."; - } - leaf ssh-rsa { - type binary; - description - "The public RSA key for this entry."; - } - } - } - leaf enable-nacm { type boolean; default true; description "Enable or disable all NETCONF access control enforcement. If 'true', then enforcement is enabled. If 'false', then enforcement is disabled."; } @@ -1907,20 +1527,23 @@ leaf denied-data-writes { type yang:zero-based-counter32; config false; mandatory true; description "Number of times a request to alter a data node was denied, since the server last restarted."; } container groups { + description + "NETCONF Access Control Groups."; + list group { key name; description "One NACM Group Entry."; leaf name { type nacm-group-name-type; description "Group name associated with this entry."; @@ -1933,20 +1556,23 @@ a member of the group associated with this entry."; } } } container rules { description "NETCONF Access Control Rules."; grouping common-rule-parms { + description + "Common rule parameters."; + leaf rule-name { type string { length "1..256"; } description "Arbitrary name assigned to the access control rule."; } leaf allowed-rights { @@ -2116,48 +1743,50 @@ leaf notification-name { type string; description "Name of the notification event."; } uses common-rule-parms; } } + } } + Figure 5 -5.5. IANA Considerations +3.5. IANA Considerations There are two actions that are requested of IANA: This document registers one URI in "The IETF XML Registry". Following the format in [RFC3688], the following has been registered. - URI: urn:ietf:params:xml:ns:yang:ietf-nacm + URI: urn:ietf:params:xml:ns:yang:ietf-netconf-acm Registrant Contact: The IESG. XML: N/A, the requested URI is an XML namespace. This document registers one module in the "YANG Module Names" registry. Following the format in [RFC6020], the following has been registered. - name: ietf-nacm - namespace: urn:ietf:params:xml:ns:yang:ietf-nacm + name: ietf-netconf-acm + namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-acm prefix: nacm reference: RFC XXXX // RFC Ed.: Replace XXX with actual RFC number // and remove this note -5.6. Security Considerations +3.6. Security Considerations This entire document discusses access control requirements and mechanisms for restricting NETCONF protocol behavior within a given session. Configuration of the access control system is highly sensitive to system security. A server may choose not to allow any user configuration to some portions of it, such as the global security level, or the groups which allowed access to system resources. @@ -2170,28 +1799,28 @@ If the server chooses to allow user configuration of the access control system, then only sessions using the 'superuser' administrative user should be allowed to have write access to the data model. If the server chooses to allow user retrieval of the access control system configuration, then only sessions using the 'superuser' administrative user should be allowed to have read access to the data model. - There is a risk that invocation of non-standard RPC operations will - have undocumented side effects. An administrator should construct - access control rules such that the configuration database is - protected from such side effects. Also, such RPC operations should - never be invoked by a session using the 'superuser' administrative - user. + There is a risk that invocation of non-standard protocol operations + will have undocumented side effects. An administrator should + construct access control rules such that the configuration datastore + is protected from such side effects. Also, such protocol operations + should never be invoked by a session using the 'superuser' + administrative user. - There is a risk that non-standard RPC operations, or even the + There is a risk that non-standard protocol operations, or even the standard operation, may return data which 'aliases' or 'copies' sensitive data from a different data object. In this case, the namespace and/or the element name will not match the values for the sensitive data, which is then fully or partially copied into a different namespace and/or element. An administrator should avoid using data models which use this practice. An administrator should restrict write access to all configurable objects within this data model. It is suggested that only sessions using the 'superuser' administrative role be permitted to configure @@ -2207,82 +1836,79 @@ o enable-nacm o read-default o write-default o exec-default o groups - o rules -6. Normative References +4. References + +4.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. - [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, - "Remote Authentication Dial In User Service (RADIUS)", - RFC 2865, June 2000. - [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January 2004. - [RFC4252] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) - Authentication Protocol", RFC 4252, January 2006. - - [RFC4253] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) - Transport Layer Protocol", RFC 4253, January 2006. - - [RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741, - December 2006. - - [RFC4742] Wasserman, M. and T. Goddard, "Using the NETCONF - Configuration Protocol over Secure SHell (SSH)", RFC 4742, - December 2006. - [RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event Notifications", RFC 5277, July 2008. - [RFC5607] Nelson, D. and G. Weber, "Remote Authentication Dial-In - User Service (RADIUS) Authorization for Network Access - Server (NAS) Management", RFC 5607, July 2009. - [RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, October 2010. [RFC6021] Schoenwaelder, J., "Common YANG Data Types", RFC 6021, October 2010. - [W3C.REC-xml] - Bray, T., Paoli, J., Sperberg-McQueen, C., and E. Maler, - "Extensible Markup Language (XML) 1.0 (2nd ed)", W3C REC- - xml, October 2000, . + [I-D.ietf-netconf-4741bis] + Enns, R., Bjorklund, M., Schoenwaelder, J., and A. + Bierman, "Network Configuration Protocol (NETCONF)", + draft-ietf-netconf-4741bis-07 (work in progress), + January 2011. + + [I-D.ietf-netconf-rfc4742bis] + Wasserman, M. and T. Goddard, "Using the NETCONF + Configuration Protocol over Secure Shell (SSH)", + draft-ietf-netconf-rfc4742bis-06 (work in progress), + January 2011. + +4.2. Informative References + + [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, + "Remote Authentication Dial In User Service (RADIUS)", + RFC 2865, June 2000. + + [RFC5607] Nelson, D. and G. Weber, "Remote Authentication Dial-In + User Service (RADIUS) Authorization for Network Access + Server (NAS) Management", RFC 5607, July 2009. Appendix A. Usage Examples The following XML snippets are provided as examples only, to demonstrate how NACM can be configured to perform some access control tasks. A.1. Example There must be at least one entry in order for any of the access control rules to be useful. The following XML shows arbitrary groups, and is not intended to represent any particular use-case. - + admin admin andy monitor wilma @@ -2307,21 +1933,21 @@ 3. The nacm:guest group contains 2 users named 'guest' and 'guest@example.com'. A.2. Example Module rules are used to control access to all the content defined in a specific module. These rules are checked after none of the specific rules (i.e., rpc-rule, data-rule, or notification-rule) matched the current access request. - + ietf-netconf-monitoring mod-1 * guest deny Do not allow guests any access to the netconf monitoring information. @@ -2367,32 +1993,33 @@ This example shows 4 module rules: mod-1: This rule prevents the guest group from reading any monitoring information in the ietf-netconf-monitoring YANG module. mod-2: This rule allows the monitor group to read the ietf-netconf- monitoring YANG module. - mod-3: This rule allows the monitor group to invoke any RPC + mod-3: This rule allows the monitor group to invoke any protocol operation supported by the server. mod-4: This rule allows the admin group complete access to all content in the server. No subsequent rule will match for the admin group, because of this module rule. A.3. Example - RPC rules are used to control access to a specific RPC operation. + RPC rules are used to control access to a specific protocol + operation. - + ietf-netconf kill-session rpc-1 monitor guest deny Do not allow the monitor or guest group @@ -2419,38 +2046,38 @@ rpc-3 monitor permit Allow the monitor group to edit the configuration. - This example shows 3 RPC operation rules: + This example shows 3 protocol operation rules: rpc-1: This rule prevents the monitor or guest groups from invoking - the NETCONF RPC operation. + the NETCONF protocol operation. rpc-2: This rule prevents the monitor or guest groups from invoking - the NETCONF RPC operation. + the NETCONF protocol operation. rpc-3: This rule allows the monitor group to invoke the NETCONF - RPC operation. This rule will have no real affect - unless the 'exec-default' leaf is set to 'deny'. + protocol operation. This rule will have no real + affect unless the 'exec-default' leaf is set to 'deny'. A.4. Example Data rules are used to control access to specific (config and non- config) data nodes within the NETCONF content provided by the server. - + data-1 /nacm * guest deny Deny the guest group any access to the /nacm data. @@ -2524,21 +2151,21 @@ admin-itf: This rule gives the admin group read-write access to all acme . entries. This is an example of an unreachable rule because the 'mod-3' rule already gives the admin group full access to this data. A.5. Example Notification rules are used to control access to a specific notification event type. - + acme-system sys-config-change notif-1 monitor guest deny Do not allow the guest or monitor groups @@ -2546,71 +2173,47 @@ This example shows 1 notification rule: notif-1: This rule prevents the monitor or guest groups from receiving the acme event type. -Appendix B. Open Issues +Appendix B. Change Log -- RFC Ed.: remove this section before publication. - 1. Do modules need to be identified by their XML namespace URI, or - is the module name good enough? - - 2. Are any more wildcard mechanisms needed to specify the scope of - an access control rule? - - 3. Should regular expressions (module='foo-*') be allowed in schema- - instance-identifier strings? - - 4. Should XPath be allowed for specifying access control rules for - data nodes? - - 5. Are any 'access-denied' notifications needed? - - 6. Should data rules support nodes that would not be eligible for - retrieval with the operation? If so, should schema nodes - such as rpc 'input' or 'output' be in the path expression? How - would notification content be identified? +B.1. 01-02 - 7. Do any external access control models need to be supported - somehow? For example, should the configuration be - optionally read-only, so it can just mirror the internal - (external or proprietary) group configuration? + Removed authentication text and objects. - 8. Should the nacm:secure and nacm:very-secure extensions be - optional to support, via a YANG feature? + Changed module name from ietf-nacm to ietf-netconf-acm. - 9. Should the default access levels (e.g., read-default) be more - restrictive by default? Shiuld these defaults be a vendor - decision? An operator decision? It is important that the server - be able to install a factory default container if needed. + Updated NETCONF and YANG terminology. -Appendix C. Change Log + Removed open issues section. - -- RFC Ed.: remove this section before publication. + Changed some must to MUST in requirements section. -C.1. 00-01 +B.2. 00-01 Updated YANG anf YANG Types references. Updated module namespace URI to standard format. Updated module header meta-data to standard format. Filled in IANA section. -C.2. 00 +B.3. 00 Initial version cloned from draft-bierman-netconf-access-control-02.txt. Authors' Addresses Andy Bierman Brocade Email: andy.bierman@brocade.com