draft-ietf-netconf-access-control-04.txt   draft-ietf-netconf-access-control-05.txt 
Internet Engineering Task Force A. Bierman Internet Engineering Task Force A. Bierman
Internet-Draft Brocade Internet-Draft Brocade
Intended status: Standards Track M. Bjorklund Intended status: Standards Track M. Bjorklund
Expires: December 16, 2011 Tail-f Systems Expires: April 6, 2012 Tail-f Systems
June 14, 2011 October 4, 2011
Network Configuration Protocol Access Control Model Network Configuration Protocol (NETCONF) Access Control Model
draft-ietf-netconf-access-control-04 draft-ietf-netconf-access-control-05
Abstract Abstract
The standardization of network configuration interfaces for use with The standardization of network configuration interfaces for use with
the NETCONF protocol requires a structured and secure operating the NETCONF protocol requires a structured and secure operating
environment that promotes human usability and multi-vendor environment that promotes human usability and multi-vendor
interoperability. There is a need for standard mechanisms to interoperability. There is a need for standard mechanisms to
restrict NETCONF protocol access for particular users to a pre- restrict NETCONF protocol access for particular users to a pre-
configured subset of all available NETCONF operations and content. configured subset of all available NETCONF protocol operations and
This document discusses requirements for a suitable access control content. This document defines such an access control model.
model, and provides one solution that meets these requirements.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 16, 2011. This Internet-Draft will expire on April 6, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 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 Design Objectives . . . . . . . . . . . . . . . 6 2. Access Control Design Objectives . . . . . . . . . . . . . . . 6
2.1. Protocol Control Points . . . . . . . . . . . . . . . . . 6 2.1. Access Control Points . . . . . . . . . . . . . . . . . . 6
2.2. Simplicity . . . . . . . . . . . . . . . . . . . . . . . . 7 2.2. Simplicity . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3. Procedural Interface . . . . . . . . . . . . . . . . . . . 7 2.3. Procedural Interface . . . . . . . . . . . . . . . . . . . 7
2.4. Datastore Access . . . . . . . . . . . . . . . . . . . . . 8 2.4. Datastore Access . . . . . . . . . . . . . . . . . . . . . 7
2.4.1. Access Rights . . . . . . . . . . . . . . . . . . . . 8 2.5. Users and Groups . . . . . . . . . . . . . . . . . . . . . 7
2.4.2. <get> and <get-config> Operations . . . . . . . . . . 8 2.6. Maintenance . . . . . . . . . . . . . . . . . . . . . . . 8
2.4.3. <edit-config> Operation . . . . . . . . . . . . . . . 9 2.7. Configuration Capabilities . . . . . . . . . . . . . . . . 8
2.4.4. <copy-config> Operation . . . . . . . . . . . . . . . 10 2.8. Identifying Security-Sensitive Content . . . . . . . . . . 8
2.5. Users and Groups . . . . . . . . . . . . . . . . . . . . . 10 3. NETCONF Access Control Model (NACM) . . . . . . . . . . . . . 10
2.6. Maintenance . . . . . . . . . . . . . . . . . . . . . . . 11 3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 10
2.7. Configuration Capabilities . . . . . . . . . . . . . . . . 11 3.1.1. Features . . . . . . . . . . . . . . . . . . . . . . . 10
2.8. Identifying Security Holes . . . . . . . . . . . . . . . . 11 3.1.2. External Dependencies . . . . . . . . . . . . . . . . 11
2.9. Data Shadowing . . . . . . . . . . . . . . . . . . . . . . 12 3.1.3. Message Processing Model . . . . . . . . . . . . . . . 11
2.10. NETCONF Specific Requirements . . . . . . . . . . . . . . 12 3.2. Datastore Access . . . . . . . . . . . . . . . . . . . . . 13
3. NETCONF Access Control Model (NACM) . . . . . . . . . . . . . 14 3.2.1. Access Rights . . . . . . . . . . . . . . . . . . . . 13
3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 14 3.2.2. <get> and <get-config> Operations . . . . . . . . . . 14
3.1.1. Features . . . . . . . . . . . . . . . . . . . . . . . 14 3.2.3. <edit-config> Operation . . . . . . . . . . . . . . . 14
3.1.2. External Dependencies . . . . . . . . . . . . . . . . 15 3.2.4. <copy-config> Operation . . . . . . . . . . . . . . . 15
3.1.3. Message Processing Model . . . . . . . . . . . . . . . 15 3.2.5. <delete-config> Operation . . . . . . . . . . . . . . 16
3.2. Model Components . . . . . . . . . . . . . . . . . . . . . 17 3.2.6. <commit> Operation . . . . . . . . . . . . . . . . . . 16
3.2.1. Users . . . . . . . . . . . . . . . . . . . . . . . . 17 3.2.7. <discard-changes> Operation . . . . . . . . . . . . . 16
3.2.2. Groups . . . . . . . . . . . . . . . . . . . . . . . . 17 3.2.8. <kill-session> Operation . . . . . . . . . . . . . . . 16
3.2.3. Sessions . . . . . . . . . . . . . . . . . . . . . . . 18 3.3. Model Components . . . . . . . . . . . . . . . . . . . . . 16
3.2.4. Access Permissions . . . . . . . . . . . . . . . . . . 18 3.3.1. Users . . . . . . . . . . . . . . . . . . . . . . . . 16
3.2.5. Global Enforcement Controls . . . . . . . . . . . . . 18 3.3.2. Groups . . . . . . . . . . . . . . . . . . . . . . . . 17
3.2.5.1. enable-nacm Switch . . . . . . . . . . . . . . . . 18 3.3.3. Global Enforcement Controls . . . . . . . . . . . . . 17
3.2.5.2. read-default Switch . . . . . . . . . . . . . . . 19 3.3.3.1. enable-nacm Switch . . . . . . . . . . . . . . . . 17
3.2.5.3. write-default Switch . . . . . . . . . . . . . . . 19 3.3.3.2. read-default Switch . . . . . . . . . . . . . . . 17
3.2.5.4. exec-default Switch . . . . . . . . . . . . . . . 19 3.3.3.3. write-default Switch . . . . . . . . . . . . . . . 18
3.2.6. Access Control Rules . . . . . . . . . . . . . . . . . 20 3.3.3.4. exec-default Switch . . . . . . . . . . . . . . . 18
3.3. Access Control Enforcement Procedures . . . . . . . . . . 20 3.3.4. Access Control Rules . . . . . . . . . . . . . . . . . 18
3.3.1. Initial Operation . . . . . . . . . . . . . . . . . . 20 3.4. Access Control Enforcement Procedures . . . . . . . . . . 19
3.3.2. Session Establishment . . . . . . . . . . . . . . . . 21 3.4.1. Initial Operation . . . . . . . . . . . . . . . . . . 19
3.3.3. "access-denied" Error Handling . . . . . . . . . . . . 21 3.4.2. Session Establishment . . . . . . . . . . . . . . . . 19
3.3.4. Incoming RPC Message Validation . . . . . . . . . . . 21 3.4.3. "access-denied" Error Handling . . . . . . . . . . . . 19
3.3.5. Data Node Access Validation . . . . . . . . . . . . . 24 3.4.4. Incoming RPC Message Validation . . . . . . . . . . . 20
3.3.6. Outgoing <notification> Authorization . . . . . . . . 26 3.4.5. Data Node Access Validation . . . . . . . . . . . . . 22
3.4. Data Model Definitions . . . . . . . . . . . . . . . . . . 28 3.4.6. Outgoing <notification> Authorization . . . . . . . . 24
3.4.1. Data Organization . . . . . . . . . . . . . . . . . . 28
3.4.2. YANG Module . . . . . . . . . . . . . . . . . . . . . 29 3.5. Data Model Definitions . . . . . . . . . . . . . . . . . . 26
3.5. IANA Considerations . . . . . . . . . . . . . . . . . . . 38 3.5.1. Data Organization . . . . . . . . . . . . . . . . . . 27
3.6. Security Considerations . . . . . . . . . . . . . . . . . 39 3.5.2. YANG Module . . . . . . . . . . . . . . . . . . . . . 27
3.6. IANA Considerations . . . . . . . . . . . . . . . . . . . 37
3.7. Security Considerations . . . . . . . . . . . . . . . . . 37
3.7.1. NACM Configuration and Monitoring Considerations . . . 37
3.7.2. General Configuration Issues . . . . . . . . . . . . . 39
3.7.3. Data Model Design Considerations . . . . . . . . . . . 40
4. References . . . . . . . . . . . . . . . . . . . . . . . . . . 41 4. References . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.1. Normative References . . . . . . . . . . . . . . . . . . . 41 4.1. Normative References . . . . . . . . . . . . . . . . . . . 41
4.2. Informative References . . . . . . . . . . . . . . . . . . 41 4.2. Informative References . . . . . . . . . . . . . . . . . . 41
Appendix A. Usage Examples . . . . . . . . . . . . . . . . . . . 42 Appendix A. Usage Examples . . . . . . . . . . . . . . . . . . . 42
A.1. <groups> Example . . . . . . . . . . . . . . . . . . . . . 42 A.1. <groups> Example . . . . . . . . . . . . . . . . . . . . . 42
A.2. Module Rule Example . . . . . . . . . . . . . . . . . . . 43 A.2. Module Rule Example . . . . . . . . . . . . . . . . . . . 43
A.3. RPC Rule Example . . . . . . . . . . . . . . . . . . . . . 44 A.3. RPC Rule Example . . . . . . . . . . . . . . . . . . . . . 44
A.4. Data Rule Example . . . . . . . . . . . . . . . . . . . . 46 A.4. Data Rule Example . . . . . . . . . . . . . . . . . . . . 46
A.5. Notification Rule Example . . . . . . . . . . . . . . . . 48 A.5. Notification Rule Example . . . . . . . . . . . . . . . . 48
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 50 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 50
B.1. 03-04 . . . . . . . . . . . . . . . . . . . . . . . . . . 50 B.1. 04-05 . . . . . . . . . . . . . . . . . . . . . . . . . . 50
B.2. 02-03 . . . . . . . . . . . . . . . . . . . . . . . . . . 50 B.2. 03-04 . . . . . . . . . . . . . . . . . . . . . . . . . . 50
B.3. 01-02 . . . . . . . . . . . . . . . . . . . . . . . . . . 50 B.3. 02-03 . . . . . . . . . . . . . . . . . . . . . . . . . . 50
B.4. 00-01 . . . . . . . . . . . . . . . . . . . . . . . . . . 50 B.4. 01-02 . . . . . . . . . . . . . . . . . . . . . . . . . . 51
B.5. 00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 B.5. 00-01 . . . . . . . . . . . . . . . . . . . . . . . . . . 51
B.6. 00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 52 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 52
1. Introduction 1. Introduction
The NETCONF protocol does not provide any standard mechanisms to The NETCONF protocol does not provide any standard mechanisms to
restrict the operations and content that each user is authorized to restrict the protocol operations and content that each user is
use. authorized to access.
There is a need for inter-operable management of the controlled There is a need for inter-operable management of the controlled
access to operator selected portions of the available NETCONF content access to administrator selected portions of the available NETCONF
within a particular server. content within a particular server.
This document addresses access control mechanisms for the Operation This document addresses access control mechanisms for the Operation
and Content layers of NETCONF, as defined in and Content layers of NETCONF, as defined in [RFC6241]. It contains
[I-D.ietf-netconf-4741bis], and [RFC5277]. It contains three main three main sections:
sections:
1. Access Control Design Objectives 1. Access Control Design Objectives
2. NETCONF Access Control Model (NACM) 2. NETCONF Access Control Model (NACM)
3. YANG Data Model (ietf-netconf-acm.yang) 3. YANG Data Model (ietf-netconf-acm.yang)
1.1. Terminology 1.1. Terminology
1.1.1. Requirements Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
1.1.2. NETCONF Terms The following terms are defined in [RFC6241] and are not redefined
here:
The following terms are defined in [I-D.ietf-netconf-4741bis] and are
not redefined here:
o client o client
o datastore o datastore
o operation
o protocol operation o protocol operation
o server o server
o session o session
o user o user
1.1.3. YANG Terms
The following terms are defined in [RFC6020] and are not redefined The following terms are defined in [RFC6020] and are not redefined
here: here:
o data node o data node
o data definition statement o data definition statement
1.1.4. NACM Terms
The following terms are used throughout this documentation: The following terms are used throughout this documentation:
access control: A security feature provided by the NETCONF server, access control: A security feature provided by the NETCONF server,
that allows an operator to restrict access to a subset of all that allows an administrator to restrict access to a subset of all
NETCONF protocol operations and data, based on various criteria. NETCONF protocol operations and data, based on various criteria.
access control model (ACM): A conceptual model used to configure and access control model (ACM): A conceptual model used to configure and
monitor the access control procedures desired by the operator to monitor the access control procedures desired by the administrator
enforce a particular access control policy. to enforce a particular access control policy.
access control rule: The conceptual criteria used to determine if a access control rule: The criteria used to determine if a particular
particular NETCONF protocol operation will be permitted or denied. NETCONF protocol operation will be permitted or denied.
access operation: How a request attempts to access a conceptual access operation: How a request attempts to access a conceptual
object. One of "read", "create", "delete", "update", and object. One of "none", "read", "create", "delete", "update", and
"execute". "execute".
recovery session: A special administrative session that is given recovery session: A special administrative session that is given
unlimited NETCONF access, and is exempt from all access control unlimited NETCONF access, and is exempt from all access control
enforcement. The specific mechanism(s) used by an implementation enforcement. The mechanism(s) used by a server to control and
to control and identify whether a session is a recovery session or identify whether a session is a recovery session or not are
not are outside the scope of this document. implementation-specific and outside the scope of this document.
write access: A shorthand for the "create", "delete", and "update"
access operations.
2. Access Control Design Objectives 2. Access Control Design Objectives
[Editor's note: some things described here are requirements (MUST, This section documents the design objectives for the NETCONF Access
SHOULD, etc), but some things are descriptions how NACM works, e.g. Control Model presented in Section 3.
2.4.1, 2.4.3...]
2.1. Protocol Control Points 2.1. Access Control Points
The NETCONF protocol allows new operations to be added at any time, NETCONF allows new protocol operations to be added at any time, and
and the YANG data modeling language supports this feature. It is not the YANG data modeling language supports this feature. It is not
possible to design an ACM for NETCONF which only focuses on a static possible to design an ACM for NETCONF that only focuses on a static
set of operations, like some other protocols. Since few assumptions set of protocol operations, like some other protocols. Since few
can be made about an arbitrary protocol operation, the NETCONF assumptions can be made about an arbitrary protocol operation, the
architectural server components need to be protected at several NETCONF architectural server components need to be protected at three
conceptual control points. conceptual control points.
+-------------+ +-------------+ +-------------+ +-------------+
client | protocol | | prune | client client | protocol | | data node |
request --> | operation | | restricted | ---> reply request --> | operation | -------------> | access |
| allowed? | | <rpc-reply> | | allowed? | datastore | allowed? |
+-------------+ | nodes? | +-------------+ or state +-------------+
| +-------------+ data access
| if any datastore or
| state data is accessed
| by the operation
V
+-------------+ +----------------+
| data node | | prune |
| access | | restricted |
| allowed? | | <notification> | ---> client
+-------------+ | event or data? | session
+----------------+
Figure 1 +----------------+
| notification |
event --> | allowed? |
+----------------+
The following access control points are defined: Figure 1
protocol operation: Configurable permission to invoke specific The following access control points, described in Figure 1, are
protocol operations is required. Wildcard or multiple target identified:
mechanisms to reduce configuration and effort are also required.
NETCONF datastore: Configurable permission to read and/or alter protocol operation: Permission to invoke specific protocol
specific data nodes within any conceptual datastore is required. operations.
Wildcard or multiple target mechanisms to reduce configuration and
effort are also required.
RPC Reply Content: Configurable permission to read specific data datastore: Permission to read and/or alter specific data nodes
nodes within any conceptual RPC output section is required. within any datastore.
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: Permission to receive specific notification event
notification event types is required. types.
2.2. Simplicity 2.2. Simplicity
Experience has shown that a complicated ACM will not be widely Experience has shown that a complicated ACM will not be widely
deployed, because it is too hard to use. The key factor that is deployed, because it is too hard to use. The key factor that is
ignored in such solutions is the concept of "localized cost". It ignored in such solutions is the concept of "localized cost". It
needs to be easy to do simple things, and possible to do complex needs to be easy to do simple things, and possible to do complex
things, instead of hard to do everything. things, instead of hard to do everything.
Configuration of the access control system needs to be as simple as Configuration of the access control system needs to be as simple as
possible. Simple and common tasks need to be easy to configure, and possible. Simple and common tasks need to be easy to configure, and
require little expertise or domain-specific knowledge. Complex tasks require little expertise or domain-specific knowledge. Complex tasks
are possible using additional mechanisms, which may require are possible using additional mechanisms, which may require
additional expertise. additional expertise.
A single set of access control rules SHOULD be able to control all A single set of access control rules ought to be able to control all
types of NETCONF protocol operation invocation, all conceptual types of NETCONF protocol operation invocation, all datastore access,
datastore access, and all NETCONF session output. and all notification events.
Access control SHOULD be defined with a small and familiar set of Access control ought to be defined with a small and familiar set of
permissions, while still allowing full control of NETCONF datastore permissions, while still allowing full control of NETCONF datastore
access. access.
Access control does not need to be applied to NETCONF <hello>
messages.
2.3. Procedural Interface 2.3. Procedural Interface
The NETCONF protocol uses a procedural interface model, and an The NETCONF protocol uses a remote procedure call model, and an
extensible set of protocol operations. Access control for any extensible set of protocol operations. Access control for any
possible protocol operation is required. possible protocol operation is necessary.
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 protocol operations is not required. Use of
generic operations should be avoided, and separate operations defined
instead, if different access levels are needed.
2.4. Datastore Access 2.4. Datastore Access
It MUST be possible to control access to specific nodes and subtrees It is necessary to control access to specific nodes and subtrees
within the conceptual NETCONF datastore. within the NETCONF datastore, regardless of which protocol operation,
standard or proprietary, was used to access the datastore.
The same access control rules apply to all conceptual datastores.
For example, the candidate configuration or the running
configuration.
Only the standard NETCONF datastores (candidate, running, and
startup) are controlled by the ACM. Local or remote files or
datastores accessed via the <url> parameter are optional to support.
The non-volatile startup configuration needs to be loaded at boot-
time into the running configuration without applying any access
control rules. Access control is applied after the server has
booted, and user sessions are active.
2.4.1. Access Rights
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
datastore.
o Read: Allows the client to read a data node instance from a
datastore, or receive the notification event type.
o Update: Allows the client to update an existing data node instance
in a datastore.
o Delete: Allows the client to delete a data node instance from a
datastore.
o eXec: Allows the client to execute the protocol operation.
2.4.2. <get> and <get-config> Operations
Data nodes to which the client does not have read access, either
directly or via wildcard access, are silently omitted from the <rpc-
reply> message. This is done to allow NETCONF filters for <get> and
<get-config> to function properly, instead of causing an "access-
denied" error because the filter criteria would otherwise include
unauthorized read access to some data nodes. For NETCONF filtering
purposes, the selection criteria is applied to the subset of nodes
that the client is authorized to read, not the entire datastore.
2.4.3. <edit-config> Operation
The NACM access rights are not directly coupled to the <edit-config>
"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 datastore. This section
describes how these access rights apply to the specific datastore
operations supported by the <edit-config> 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 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 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", "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 datastore. For example, a container or list
node may be present for naming purposes, but does not actually alter
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.
[Editor's note: ditto for "replace" (and copy-config...) Note that
with this rule, a client w/o read access can guess db content by
sending merge requests - if access-denied is not returned, it means
the db has that value.]
A "merge" operation may include data nodes, but not include
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 datastore nodes MUST NOT be
exposed in any <rpc-error> elements within the reply.
2.4.4. <copy-config> Operation
Access control for the <copy-config> operation requires special
consideration because the operator is replacing the entire target
datastore. Read access to the entire source datastore, and write
access to the entire target datastore is needed for this operation to
succeed.
The server SHOULD determine the exact nodes in the target datastore
which are actually different, and only check write access permissions
for this set of nodes, which could be empty. For example, if a
session can read the entire datastore, but only change one leaf, that
session SHOULD be able to edit and save that one leaf. E.g., the
<copy-config> operation from <running> to <startup> SHOULD succeed if
the only effective changes are for data nodes that session is
authorized to change.
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 (client) MUST have full read access
to the datastore in order to receive a complete copy of its contents.
If the server simply omits these subtrees from the reply, and 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.
2.5. Users and Groups 2.5. Users and Groups
The server MUST obtain a user name from the underlying NETCONF It is necessary that access control rules for a single user or a
transport, such as an SSH user name. configurable group of users can be configured.
It MUST be possible to specify access control rules for a single user
or a configurable group of users.
The ACM MUST support the concept of administrative groups, to support The ACM needs to support the concept of administrative groups, to
the well-established distinction between a root account and other support the well-established distinction between a root account and
types of less-privileged conceptual user accounts. These groups MUST other types of less-privileged conceptual user accounts. These
be configurable by the operator. groups needs to be configurable by the administrator.
It MUST be possible to delegate the user-to-group mapping to a It is necessary that the user-to-group mapping can be delegated to a
central server, such as a RADIUS server [RFC2865] [RFC5607]. Since central server, such as a RADIUS server [RFC2865] [RFC5607]. Since
authentication is performed by the NETCONF transport layer, and authentication is performed by the NETCONF transport layer, and
RADIUS performs authentication and service authorization at the same RADIUS performs authentication and service authorization at the same
time, it MUST be possible for the underlying NETCONF transport to time, the underlying NETCONF transport needs to be able to report a
report a set of group names associated with the user to the server. set of group names associated with the user to the server.
2.6. Maintenance 2.6. Maintenance
It SHOULD be possible to disable part or all of the access control It ought to be possible to disable part or all of the access control
model without deleting any configuration. model without deleting any access control rules.
2.7. Configuration Capabilities 2.7. Configuration Capabilities
Suitable control and monitoring mechanisms are needed to allow an Suitable configuration and monitoring mechanisms are needed to allow
operator to easily manage all aspects of the ACM behavior. A an administrator to easily manage all aspects of the ACM behavior. A
standard data model, suitable for use with the <edit-config> standard data model, suitable for use with the <edit-config> protocol
operation MUST be available for this purpose. operation needs to be available for this purpose.
Access control rules to restrict operations on specific subtrees Access control rules to restrict access operations on specific
within the configuration datastore MUST be supported. Existing subtrees within the configuration datastore needs to be supported.
mechanisms can be used to identify the subtree(s) for this purpose.
2.8. Identifying Security Holes 2.8. Identifying Security-Sensitive Content
One of the most important aspects of the data model documentation, One of the most important aspects of the data model documentation,
and biggest concerns during deployment, is the identification of and biggest concerns during deployment, is the identification of
security-sensitive content. This applies to operations in NETCONF, security-sensitive content. This applies to protocol operations in
not just data and notifications. NETCONF, not just data and notifications.
It is mandatory 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 the Security Considerations section of an RFC. This is nice, but it
is not good enough, for the following reasons: is not good enough, for the following reasons:
o This documentation-only approach forces operators to study the RFC o This documentation-only approach forces administrators to study
and determine if there are any potential security holes introduced the RFC and determine if there are any potential security risks
by a new YANG module. introduced by a new data model.
o If any security holes are identified, then the operator can study o If any security risks are identified, then the administrator can
some more RFC text, and determine how to close the security study some more RFC text, and determine how to mitigate the
hole(s). security risk(s).
o The ACM on each server can be configured to close the security o The ACM on each server can be configured to mitigate the security
holes, e.g., require privileged access to read or write the risks, e.g., require privileged access to read or write the
specific data identified in the Security Considerations section. specific data identified in the Security Considerations section.
o If the ACM is not pre-configured, then there will be a time window o If the ACM is not pre-configured, then there will be a time window
of vulnerability, after the new module is loaded, and before the of vulnerability, after the new data model is loaded, and before
new access control rules for that module are configured, enabled, the new access control rules for that data model are configured,
and debugged. enabled, and debugged.
Often, the operator just wants to disable default access to the Often, the administrator just wants to disable default access to the
secure content, so no inadvertent or malicious changes can be made to secure content, so no inadvertent or malicious changes can be made to
the server. This allows the default rules to be more lenient, the server. This allows the default rules to be more lenient,
without significantly increasing the security risk. without significantly increasing the security risk.
A data model designer needs to be able to use machine-readable A data model designer needs to be able to use machine-readable
statements to identify NETCONF content which needs to be protected by statements to identify NETCONF content which needs to be protected by
default. This will allow client and server tools to automatically default. This will allow client and server tools to automatically
close data-model specific security holes, by denying access to identify data-model specific security risks, by denying access to
sensitive data unless the user is explicitly authorized to perform sensitive data unless the user is explicitly authorized to perform
the requested operation. the requested access operation.
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 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 <rpc-reply>
messages.
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 can
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 <rpc-reply> message.
2.10. NETCONF Specific Requirements
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 datastore access request,
even for proprietary operations.
A client MUST always be authorized to invoke the <close-session>
operation, defined in [I-D.ietf-netconf-4741bis].
A client MUST always be authorized to receive the <replayComplete>
and <notificationComplete> notification events, defined in [RFC5277]
The set of module name strings used within one particular server MUST
be unique.
3. NETCONF Access Control Model (NACM) 3. NETCONF Access Control Model (NACM)
3.1. Introduction 3.1. Introduction
This section provides a high-level overview of the access control This section provides a high-level overview of the access control
model structure. It describes the NETCONF protocol message model structure. It describes the NETCONF protocol message
processing model, and the conceptual access control requirements processing model, and the conceptual access control requirements
within that model. within that model.
skipping to change at page 14, line 31 skipping to change at page 10, line 31
to use. to use.
o The concept of an emergency recovery session is supported, but o The concept of an emergency recovery session is supported, but
configuration of the server for this purpose is beyond the scope configuration of the server for this purpose is beyond the scope
of this document. An emergency recovery session will bypass all of this document. An emergency recovery session will bypass all
access control enforcement, in order to allow it to initialize or access control enforcement, in order to allow it to initialize or
repair the NACM configuration. repair the NACM configuration.
o A simple and familiar set of datastore 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) o Support for YANG security tagging (e.g., "nacm:default-deny-write"
allows default security modes to automatically exclude sensitive statement) allows default security modes to automatically exclude
data. sensitive data.
o Separate default access modes for read, write, and execute o Separate default access modes for read, write, and execute
permissions. permissions.
o Access control rules are applied to configurable groups of users. o Access control rules are applied to configurable groups of users.
o The entire ACM can be disabled during operation, in order to debug o The entire ACM can be disabled during operation, in order to debug
operational problems. operational problems.
o Access control rules are simple to configure. o Access control rules are simple to configure.
o The number of denied protocol operation requests and denied o The number of denied protocol operation requests and denied
datastore write requests can be monitored by the client. datastore write requests can be monitored by the client.
o Simple unconstrained YANG instance identifiers are used to o Simple unconstrained YANG instance identifiers are used to
configure access control rules for specific data nodes. configure access control rules for specific data nodes.
3.1.2. External Dependencies 3.1.2. External Dependencies
The NETCONF [I-D.ietf-netconf-4741bis] protocol is used for all The NETCONF [RFC6241] protocol is used for all management purposes
management purposes within this document. It is expected that the within this document. It is expected that the mandatory transport
mandatory transport mapping NETCONF Over SSH mapping NETCONF Over SSH [RFC6242] is also supported by the server,
[I-D.ietf-netconf-rfc4742bis] is also supported by the server, and and that the server has access to the user name associated with each
that the server has access to the user name associated with each
session. session.
The YANG Data Modeling Language [RFC6020] is used to define the The YANG Data Modeling Language [RFC6020] is used to define the
NETCONF data models specified in this document. NETCONF data models specified in this document.
3.1.3. Message Processing Model 3.1.3. Message Processing Model
The following diagram shows the NETCONF message flow model, including The following diagram shows the conceptual message flow model,
the points at which access control is applied, during NETCONF message including the points at which access control is applied, during
processing. NETCONF message processing.
+-------------------------+ +-------------------------+
| session | | session |
| (username) | | (username) |
+-------------------------+ +-------------------------+
| ^ | ^
V | V |
+--------------+ +---------------+ +--------------+ +---------------+
| message | | message | | message | | message |
| dispatcher | | generator | | dispatcher | | generator |
+--------------+ +---------------+ +--------------+ +---------------+
| ^ ^ | ^ ^
V | | V | |
+===========+ +-------------+ +----------------+ +===========+ +-------------+ +----------------+
| <rpc> |---> | <rpc-reply> | | <notification> | | <rpc> |---> | <rpc-reply> | | <notification> |
| acc. ctl | | generator | | generator | | acc. ctl | | generator | | generator |
+===========+ +-------------+ +----------------+ +===========+ +-------------+ +----------------+
| ^ ^ ^ | ^ ^ ^
V +------+ | | V +------+ | |
+-----------+ | +=============+ +================+ +-----------+ | +=============+ +================+
| <rpc> | | | <rpc-reply> | | <notification> | | <rpc> | | | read | | <notification> |
| processor |-+ | acc. ctl | | access ctl | | processor |-+ | data node | | access ctl |
| | | acc. ctl | | |
+-----------+ +=============+ +================+ +-----------+ +=============+ +================+
| | ^ ^ | | ^ ^
V +----------------+ | | V +----------------+ | |
+===========+ | | | +===========+ | | |
| write | | | |
| data node | | | | | data node | | | |
| acc. ctl | -----------+ | | | | acc. ctl | -----------+ | | |
+===========+ | | | | +===========+ | | | |
| | | | | | | | | |
V V V | | V V V | |
+---------------+ +-----------------+ +---------------+ +-----------------+
| configuration | ---> | server | | configuration | ---> | server |
| datastore | | instrumentation | | datastore | | instrumentation |
| | <--- | | | | <--- | |
+---------------+ +-----------------+ +---------------+ +-----------------+
skipping to change at page 17, line 5 skipping to change at page 13, line 6
Figure 2 Figure 2
The following high-level sequence of conceptual processing steps is The following high-level sequence of conceptual processing steps is
executed for each received <rpc> message, if access control executed for each received <rpc> message, if access control
enforcement is enabled: enforcement is enabled:
o Access control is applied to all <rpc> messages (except <close- o Access control is applied to all <rpc> messages (except <close-
session>) received by the server, individually, for each active session>) received by the server, individually, for each active
session, unless the session is identified as a "recovery session". session, unless the session is identified as a "recovery session".
o If the session is authorized to execute the specified RPC o If the user is authorized to execute the specified protocol
operation, then processing continues, otherwise the request is operation, then processing continues, otherwise the request is
rejected with an "access-denied" error. rejected with an "access-denied" error.
o If the configuration datastore or conceptual state data is o If the configuration datastore or conceptual state data is
accessed by the protocol operation, then the data node access MUST accessed by the protocol operation, then the data node access MUST
be authorized. If the session is authorized to perform the be authorized. If the user is authorized to perform the requested
requested operation on the requested data, then processing access operation on the requested data, then processing continues.
continues.
The following sequence of conceptual processing steps is executed for The following sequence of conceptual processing steps is executed for
each generated notification event, if access control enforcement is each generated notification event, if access control enforcement is
enabled: enabled:
o Server instrumentation generates a conceptual notification, for a o Server instrumentation generates a notification, for a particular
particular subscription. subscription.
o The notification access control enforcer checks the notification o The notification access control enforcer checks the notification
event type, and if it is one which the session is not authorized event type, and if it is one which the user is not authorized to
to read, then the notification is dropped for that subscription. read, then the notification is dropped for that subscription.
3.2. Model Components 3.2. Datastore Access
This section defines the conceptual components related to access The same access control rules apply to all datastores. For example,
control model. the candidate configuration datastore or the running configuration
datastore.
3.2.1. Users Only the standard NETCONF datastores (candidate, running, and
startup) are controlled by the ACM. Local or remote files or
datastores accessed via the <url> parameter are optional to support.
A "user" is the conceptual entity that is associated with the access 3.2.1. Access Rights
permissions granted to a particular session. A user is identified by
a string which MUST be unique within the server.
As described in [I-D.ietf-netconf-4741bis], the user name string is A small set of hard-wired datastore access rights is needed to
derived from the transport layer during session establishment. If control access to all possible NETCONF protocol operations, including
the transport layer cannot authenticate the user, the session is vendor extensions to the standard protocol operation set.
terminated.
The server MAY support a "recovery session" mechanism, which will The "CRUDX" model can support all NETCONF protocol operations:
bypass all access control enforcement. This is useful for
restricting initial access and repairing a broken access control
configuration.
3.2.2. Groups o Create: Allows the client to add a new data node instance to a
datastore.
Access to a specific NETCONF operation is granted to a session, o Read: Allows the client to read a data node instance from a
associated with a group, not a user. datastore, or receive the notification event type.
A group is identified by its name. All group names MUST be unique o Update: Allows the client to update an existing data node instance
within the server. in a datastore.
A group member is identified by a user name string. o Delete: Allows the client to delete a data node instance from a
datastore.
The same user may be configured in multiple groups. o eXec: Allows the client to execute the protocol operation.
3.2.3. Sessions 3.2.2. <get> and <get-config> Operations
A session is simply a NETCONF session, which is the entity that is Data nodes to which the client does not have read access are silently
granted access to specific NETCONF operations. omitted from the <rpc-reply> message. This is done to allow NETCONF
filters for <get> and <get-config> to function properly, instead of
causing an "access-denied" error because the filter criteria would
otherwise include unauthorized read access to some data nodes. For
NETCONF filtering purposes, the selection criteria is applied to the
subset of nodes that the user is authorized to read, not the entire
datastore.
A session is associated with a single user name for the lifetime of 3.2.3. <edit-config> Operation
the session.
3.2.4. Access Permissions The NACM access rights are not directly coupled to the <edit-config>
"operation" attribute, although they are similar. Instead, a NACM
access right applies to all protocol operations which would result in
a particular access operation to the target datastore. This section
describes how these access rights apply to the specific access
operations supported by the <edit-config> protocol operation.
The access permissions are the NETCONF protocol specific set of If the effective access operation is "none" (i.e., default-
permissions that have been assigned to a particular session. operation="none") for a particular data node, then no access control
is applied to that data node.
The same access permissions MUST stay in effect for the processing of If the protocol operation would result in the creation of a data
a particular message. store node, and the user does not have "create" access permission for
that node, the protocol operation is rejected with an "access-denied"
error.
The server MUST use the access control rules in effect at the time If the protocol operation would result in the deletion of a data
the message is processed. store node, and the user does not have "delete" access permission for
that node, the protocol operation is rejected with an "access-denied"
error.
The access control model treats protocol operation execution If the protocol operation would result in the modification of a data
separately from configuration datastore access and outgoing messages: store node, and the user does not have "update" access permission for
that node, the protocol operation is rejected with an "access-denied"
error.
create: Permission to create conceptual server data. A "merge" or "replace" <edit-config> operation may include data nodes
which do not alter portions of the existing datastore. For example,
a container or list node may be present for naming purposes, but does
not actually alter the corresponding datastore node. These unaltered
data nodes are ignored by the server, and do not require any access
rights by the client.
read: Read access to conceptual server data, <rpc-reply> and A "merge" <edit-config> operation may include data nodes, but not
<notification> content. include particular child data nodes that are present in the
datastore. These missing data nodes within the scope of a "merge"
<edit-config> operation are ignored by the server, and do not require
any access rights by the client.
update: Permission to modify existing conceptual server data. The contents of specific restricted datastore nodes MUST NOT be
exposed in any <rpc-error> elements within the reply.
delete: Permission to delete existing conceptual server data. 3.2.4. <copy-config> Operation
exec: Permission to invoke a protocol operation. Access control for the <copy-config> protocol operation requires
special consideration because the administrator may be replacing the
entire target datastore.
3.2.5. Global Enforcement Controls If the source of the <copy-config> protocol operation is the running
configuration datastore, and the target is the startup configuration
datastore, the client is only required to have permission to execute
the <copy-config> protocol operation.
Otherwise:
o If the source of the <copy-config> operation is a datastore, then
data nodes to which the client does not have read access are
silently omitted.
o If the target of the <copy-config> operation is a datastore, the
client needs access to the modified nodes. Specifically:
If the protocol operation would result in the creation of a
data store node, and the user does not have "create" access
permission for that node, the protocol operation is rejected
with an "access-denied" error.
If the protocol operation would result in the deletion of a
data store node, and the user does not have "delete" access
permission for that node, the protocol operation is rejected
with an "access-denied" error.
If the protocol operation would result in the modification of a
data store node, and the user does not have "update" access
permission for that node, the protocol operation is rejected
with an "access-denied" error.
3.2.5. <delete-config> Operation
Access to the <delete-config> protocol operation is denied by
default. The 'exec-default' parameter does not apply to this
protocol operation. Access control rules must be explicitly
configured to allow invocation by a non-recovery session.
3.2.6. <commit> Operation
The server MUST determine the exact nodes in the running
configuration datastore which are actually different, and only check
"create", "update", and "delete" access permissions for this set of
nodes, which could be empty.
For example, if a session can read the entire datastore, but only
change one leaf, that session needs to be able to edit and commit
that one leaf.
3.2.7. <discard-changes> Operation
The client is only required to have permission to execute the
<discard-changes> protocol operation. No datastore permissions are
needed.
3.2.8. <kill-session> Operation
The <kill-session> operation does not directly alter a datastore.
However, it allows one session to disrupt another session which is
editing a datastore.
Access to the <kill-session> protocol operation is denied by default.
The 'exec-default' parameter does not apply to this protocol
operation. Access control rules must be explicitly configured to
allow invocation by a non-recovery session.
3.3. Model Components
This section defines the conceptual components related to access
control model.
3.3.1. Users
A "user" is the conceptual entity that is associated with the access
permissions granted to a particular session. A user is identified by
a string which is unique within the server.
As described in [RFC6241], 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 "recovery session" mechanism, which will
bypass all access control enforcement. This is useful for
restricting initial access and repairing a broken access control
configuration.
3.3.2. Groups
Access to a specific NETCONF protocol operation is granted to a
session, associated with a group, not a user.
A group is identified by its name. All group names are unique within
the server.
A group member is identified by a user name string.
The same user can be a member of multiple groups.
3.3.3. Global Enforcement Controls
There are four global controls that are used to help control how There are four global controls that are used to help control how
access control is enforced. access control is enforced.
3.2.5.1. enable-nacm Switch 3.3.3.1. enable-nacm Switch
A global "enable-nacm" on/off switch is provided to enable or disable A global "enable-nacm" on/off switch is provided to enable or disable
all access control enforcement. When this global switch is set to all access control enforcement. When this global switch is set to
"true", then all access requested are checked against the access "true", then all requests are checked against the access control
control rules, and only permitted if configured to allow the specific rules, and only permitted if configured to allow the specific access
access request. When this global switch is set to "false", then all request. When this global switch is set to "false", then all access
access requested are permitted. requested are permitted.
3.2.5.2. read-default Switch 3.3.3.2. read-default Switch
An on/off "read-default" switch is provided to enable or disable An on/off "read-default" switch is provided to enable or disable
default access to receive data in replies and notifications. When default access to receive data in replies and notifications. When
the "enable-nacm" global switch is set to "true", then this global the "enable-nacm" global switch is set to "true", then this global
switch is relevant, if no matching access control rule is found to switch is relevant, if no matching access control rule is found to
explicitly permit or deny read access to the requested NETCONF explicitly permit or deny read access to the requested NETCONF
datastore data or notification event type. datastore data or notification event type.
When this global switch is set to "permit", and no matching access When this global switch is set to "permit", and no matching access
control rule is found for the NETCONF datastore read or notification control rule is found for the NETCONF datastore read or notification
event requested, then access is permitted. event requested, then access is permitted.
When this global switch is set to "deny", and no matching access When this global switch is set to "deny", and no matching access
control rule is found for the NETCONF datastore read or notification control rule is found for the NETCONF datastore read or notification
event requested, then access is denied. event requested, then access is denied.
3.2.5.3. write-default Switch 3.3.3.3. write-default Switch
An on/off "write-default" switch is provided to enable or disable An on/off "write-default" switch is provided to enable or disable
default access to alter configuration data. When the "enable-nacm" default access to alter configuration data. When the "enable-nacm"
global switch is set to "true", then this global switch is relevant, global switch is set to "true", then this global switch is relevant,
if no matching access control rule is found to explicitly permit or if no matching access control rule is found to explicitly permit or
deny write access to the requested NETCONF datastore data. deny write access to the requested NETCONF datastore data.
When this global switch is set to "permit", and no matching access When this global switch is set to "permit", and no matching access
control rule is found for the NETCONF datastore write requested, then control rule is found for the NETCONF datastore write requested, then
access is permitted. access is permitted.
When this global switch is set to "deny", and no matching access When this global switch is set to "deny", and no matching access
control rule is found for the NETCONF datastore write requested, then control rule is found for the NETCONF datastore write requested, then
access is denied. access is denied.
3.2.5.4. exec-default Switch 3.3.3.4. exec-default Switch
An on/off "exec-default" switch is provided to enable or disable An on/off "exec-default" switch is provided to enable or disable
default access to execute protocol operations. When the "enable- default access to execute protocol operations. When the "enable-
nacm" global switch is set to "true", then this global switch is nacm" global switch is set to "true", then this global switch is
relevant, if no matching access control rule is found to explicitly relevant, if no matching access control rule is found to explicitly
permit or deny access to the requested NETCONF protocol operation. permit or deny access to the requested NETCONF protocol operation.
When this global switch is set to "permit", and no matching access When this global switch is set to "permit", and no matching access
control rule is found for the NETCONF protocol operation requested, control rule is found for the NETCONF protocol operation requested,
then access is permitted. then access is permitted.
When this global switch is set to "deny", and no matching access When this global switch is set to "deny", and no matching access
control rule is found for the NETCONF protocol operation requested, control rule is found for the NETCONF protocol operation requested,
then access is denied. then access is denied.
3.2.6. Access Control Rules 3.3.4. Access Control Rules
There are 4 types of rules available in NACM: There are 4 types of rules available in NACM:
module rule: Controls access for definitions in a specific module, module rule: Controls access for definitions in a specific YANG
identified by its name. module, identified by its name.
protocol operation rule: Controls access for a specific protocol protocol operation rule: Controls access for a specific protocol
operation, identified by its module and name. operation, identified by its YANG module and name.
data node rule: Controls access for a specific data node, identified data node rule: Controls access for a specific data node, identified
by its path location within the conceptual XML document for the by its path location within the conceptual XML document for the
data node. data node.
notification rule: Controls access for a specific notification event notification rule: Controls access for a specific notification event
type, identified by its module and name. type, identified by its YANG module and name.
3.3. Access Control Enforcement Procedures 3.4. Access Control Enforcement Procedures
There are seven separate phases that need to be addressed, four of There are seven separate phases that need to be addressed, four of
which are related to the NETCONF message processing model. In which are related to the NETCONF message processing model. In
addition, the initial start-up mode for a NETCONF server, session addition, the initial start-up mode for a NETCONF server, session
establishment, and "access-denied" error handling procedures also establishment, and "access-denied" error handling procedures also
need to be considered. need to be considered.
3.3.1. Initial Operation The server MUST use the access control rules in effect at the time it
starts processing the message. The same access control rules MUST
stay in effect for the processing of the entire message.
3.4.1. Initial Operation
Upon the very first start-up of the NETCONF server, the access Upon the very first start-up of the NETCONF server, the access
control configuration will probably not be present. If it isn't, a control configuration will probably not be present. If it isn't, a
server MUST NOT allow any write access to any session role except a server MUST NOT allow any write access to any session role except a
"recovery session", if supported. "recovery session".
Access control rules are not enforced before or while the non- Access rules are enforced any time a request is initiated from a user
volatile configuration data is processed and loaded into the running session. Access control is not enforced for server-initiated access
configuration, when the server is booting or rebooting. Access rules requests, such as the initial load of the running datastore, during
are enforced any time a request is initiated from a user session. bootup.
Access control is not enforced for server-initiated access requests,
such as the initial load of the running datastore, during bootup.
3.3.2. Session Establishment 3.4.2. Session Establishment
The access control model applies specifically to the well-formed XML The access control model applies specifically to the well-formed XML
content transferred between a client and a server, after session content transferred between a client and a server, after session
establishment has been completed, and after the <hello> exchange has establishment has been completed, and after the <hello> exchange has
been successfully completed. been successfully completed.
A server SHOULD NOT include any sensitive information in any
<capability> elements within the <hello> exchange.
Once session establishment is completed, and a user has been Once session establishment is completed, and a user has been
authenticated, the NETCONF transport layer reports the user name and authenticated, the NETCONF transport layer reports the user name and
a possibly empty set of group names associated with the user to the a possibly empty set of group names associated with the user to the
NETCONF server. The NETCONF server will enforce the access control NETCONF server. The NETCONF server will enforce the access control
rules, based on the supplied user name, group names, and the rules, based on the supplied user name, group names, and the
configuration data stored on the server. configuration data stored on the server.
3.3.3. "access-denied" Error Handling 3.4.3. "access-denied" Error Handling
The "access-denied" error-tag is generated when the access control The "access-denied" error-tag is generated when the access control
system denies access to either a request to invoke a protocol system denies access to either a request to invoke a protocol
operation or a request to perform a particular operation on the operation or a request to perform a particular access operation on
configuration datastore. the configuration datastore.
A server MUST NOT include any sensitive information in any <error- A server MUST NOT include any sensitive information in any <error-
info> elements within the <rpc-error> response. info> elements within the <rpc-error> response.
3.3.4. Incoming RPC Message Validation 3.4.4. Incoming RPC Message Validation
The diagram below shows the basic conceptual structure of the access The diagram below shows the basic conceptual structure of the access
control processing model for incoming NETCONF <rpc> messages, within control processing model for incoming NETCONF <rpc> messages, within
a server. a server.
NETCONF server NETCONF server
+------------+ +------------+
| XML | | XML |
| message | | message |
| dispatcher | | dispatcher |
skipping to change at page 22, line 41 skipping to change at page 21, line 7
| configuration | | configuration |
| datastore | | datastore |
+----------------------+ +----------------------+
Figure 3 Figure 3
Access control begins with the message dispatcher. Access control begins with the message dispatcher.
After the server validates the <rpc> element, and determines the After the server validates the <rpc> element, and determines the
namespace URI and the element name of the protocol operation being namespace URI and the element name of the protocol operation being
requested, the RPC access control enforcer verifies that the session requested, the server verifies that the user is authorized to invoke
is authorized to invoke the protocol operation. the protocol operation.
The protocol operation is authorized by following these steps: The protocol operation is authorized by following these steps:
1. If the "enable-nacm" leaf is set to "false", then the protocol 1. If the "enable-nacm" leaf is set to "false", then the protocol
operation is permitted. operation is permitted.
2. If the requesting session is identified as a "recovery session", 2. If the requesting session is identified as a "recovery session",
then the protocol operation is permitted. then the protocol operation is permitted.
3. If the requested operation is the NETCONF <close-session> 3. If the requested operation is the NETCONF <close-session>
operation, then the protocol operation is permitted. protocol operation, then the protocol operation is permitted.
4. Check all the "group" entries for ones that contain a "user- 4. Check all the "group" entries for ones that contain a "user-
name" entry that equals the user name for the session making the name" entry that equals the user name for the session making the
request. Add to these groups the set of groups provided by the request. Add to these groups the set of groups provided by the
transport layer. transport layer.
5. If no groups are found, continue with step 10. 5. If no groups are found, continue with step 10.
6. Process all rule-list entries, in order. If a rule-list's 6. Process all rule-list entries, in the order they appear in the
"group" leaf-list does not match any of the user's groups, configuration. If a rule-list's "group" leaf-list does not
proceed to the next rule-list entry. match any of the user's groups, proceed to the next rule-list
entry.
7. For each rule-list entry found, process all rules, in order, 7. For each rule-list entry found, process all rules, in order,
until a rule that matches the requested operation is found. A until a rule that matches the requested access operation is
rule matches if all of the following criteria are met: found. A rule matches if all of the following criteria are met:
* The rule's "module-name" leaf is "*", or equals the name of * The rule's "module-name" leaf is "*", or equals the name of
the YANG module where the protocol operation is defined. the YANG module where the protocol operation is defined.
* The rule does not have a "rule-type" defined, or the "rule- * The rule does not have a "rule-type" defined, or the "rule-
type" is "protocol-operation" and the "rpc-name" is "*" or type" is "protocol-operation" and the "rpc-name" is "*" or
equals the name of the requested protocol operation. equals the name of the requested protocol operation.
* The rule's "access-operations" leaf has the "exec" bit set, * The rule's "access-operations" leaf has the "exec" bit set,
or has the special value "*". or has the special value "*".
8. If a matching rule is found, then the "action" leaf is checked. 8. If a matching rule is found, then the "action" leaf is checked.
If it is equal to "permit", then the protocol operation is If it is equal to "permit", then the protocol operation is
permitted, otherwise it is denied. permitted, otherwise it is denied.
9. Otherwise, no matching rule was found in any rule-list entry. 9. Otherwise, no matching rule was found in any rule-list entry.
10. If the requested protocol operation is defined in a YANG module 10. If the requested protocol operation is defined in a YANG module
advertised in the server capabilities, and the "rpc" statement advertised in the server capabilities, and the "rpc" statement
contains a "nacm:secure" or a "nacm:very-secure" statement, then contains a "nacm:default-deny-all" statement, then the protocol
the protocol operation is denied. operation is denied.
11. If the "exec-default" leaf is set to "permit", then permit the 11. If the requested protocol operation is the NETCONF <kill-
session> or <delete-config>, then the protocol operation is
denied.
12. If the "exec-default" leaf is set to "permit", then permit the
protocol operation, otherwise deny the request. protocol operation, otherwise deny the request.
If the session is not authorized to invoke the protocol operation If the user is not authorized to invoke the protocol operation then
then an <rpc-error> is generated with the following information: an <rpc-error> is generated with the following information:
error-tag: access-denied error-tag: access-denied
error-path: Identifies the requested protocol operation. For error-path: Identifies the requested protocol operation. For
example: example:
<error-path <error-path
xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0"> xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0">
/nc:rpc/nc:edit-config /nc:rpc/nc:edit-config
</error-path> </error-path>
represents the <edit-config> operation in the NETCONF base represents the <edit-config> protocol operation in the NETCONF
namespace. base namespace.
If a datastore is accessed, either directly or as a side effect of If a datastore is accessed, either directly or as a side effect of
the protocol operation, then the server MUST intercept the operation the protocol operation, then the server MUST intercept the access
and make sure the session is authorized to perform the requested operation and make sure the user is authorized to perform the
operation on the specified data, as defined in Section 3.3.5. requested access operation on the specified data, as defined in
Section 3.4.5.
3.3.5. Data Node Access Validation 3.4.5. Data Node Access Validation
If a data node within a datastore is accessed, then the server MUST If a data node within a datastore is accessed, then the server MUST
ensure that the client session is authorized to perform the requested ensure that the user is authorized to perform the requested read,
read, create, update, or delete operation on the specified data node. create, update, or delete access operation on the specified data
node.
The data node access request is authorized by following these steps: The data node access request is authorized by following these steps:
1. If the "enable-nacm" leaf is set to "false", then the protocol 1. If the "enable-nacm" leaf is set to "false", then the access
operation is permitted. operation is permitted.
2. If the requesting session is identified as a "recovery session", 2. If the requesting session is identified as a "recovery session",
then the protocol operation is permitted. then the access operation is permitted.
3. Check all the "group" entries for ones that contain a "user- 3. Check all the "group" entries for ones that contain a "user-
name" entry that equals the user name for the session making the name" entry that equals the user name for the session making the
request. Add to these groups the set of groups provided by the request. Add to these groups the set of groups provided by the
transport layer. transport layer.
4. If no groups are found, continue with step 9. 4. If no groups are found, continue with step 9.
5. Process all rule-list entries, in order. If a rule-list's 5. Process all rule-list entries, in the order they appear in the
"group" leaf-list does not match any of the user's groups, configuration. If a rule-list's "group" leaf-list does not
proceed to the next rule-list entry. match any of the user's groups, proceed to the next rule-list
entry.
6. For each rule-list entry found, process all rules, in order, 6. For each rule-list entry found, process all rules, in order,
until a rule that matches the requested operation is found. A until a rule that matches the requested access operation is
rule matches if all of the following criteria are met: found. A rule matches if all of the following criteria are met:
* The rule's "module-name" leaf is "*", or equals the name of * The rule's "module-name" leaf is "*", or equals the name of
the YANG module where the protocol operation is defined. the YANG module where the requested data node is defined.
* The rule does not have a "rule-type" defined, or the "rule- * The rule does not have a "rule-type" defined, or the "rule-
type" is "data-node" and the "path" matches the requested type" is "data-node" and the "path" matches the requested
data node. data node.
* For a read operation, the rule's "access-operations" leaf has * For a read access operation, the rule's "access-operations"
the "read" bit set, or has the special value "*". leaf has the "read" bit set, or has the special value "*".
* For a creation operation, the rule's "access-operations" leaf * For a create access operation, the rule's "access-operations"
has the "create" bit set, or has the special value "*". leaf has the "create" bit set, or has the special value "*".
* For a deletion operation, the rule's "access-operations" leaf * For a delete access operation, the rule's "access-operations"
has the "delete" bit set, or has the special value "*". leaf has the "delete" bit set, or has the special value "*".
* For an update operation, the rule's "access-operations" leaf * For an update access operation, the rule's "access-
has the "update" bit set, or has the special value "*". operations" leaf has the "update" bit set, or has the special
value "*".
7. If a matching rule is found, then the "action" leaf is checked. 7. If a matching rule is found, then the "action" leaf is checked.
If it is equal to "permit", then the data node access is If it is equal to "permit", then the data node access is
permitted, otherwise it is denied. For a read operation, permitted, otherwise it is denied. For a read access operation,
"denied" means that the requested data is not returned in the "denied" means that the requested data is not returned in the
reply. reply.
8. Otherwise, no matching rule was found in any rule-list entry. 8. Otherwise, no matching rule was found in any rule-list entry.
9. For a read operation, if the requested data node is defined in a 9. For a read access operation, if the requested data node is
YANG module advertised in the server capabilities, and the data defined in a YANG module advertised in the server capabilities,
definition statement contains a "nacm:very-secure" statement, and the data definition statement contains a "nacm:default-deny-
then the requested data node is not included in the reply. all" statement, then the requested data node is not included in
the reply.
10. For a write operation, if the requested data node is defined in 10. For a write access operation, if the requested data node is
a YANG module advertised in the server capabilities, and the defined in a YANG module advertised in the server capabilities,
data definition statement contains a "nacm:secure" or a "nacm: and the data definition statement contains a "nacm:default-deny-
very-secure" statement, then the data node access request is write" or a "nacm:default-deny-all" statement, then the data
denied. node access request is denied.
11. For a read operation, if the "read-default" leaf is set to 11. For a read access operation, if the "read-default" leaf is set
"permit", then include the requested data node in the reply, to "permit", then include the requested data node in the reply,
otherwise do not include the requested data node in the reply. otherwise do not include the requested data node in the reply.
12. For a write operation, if the "write-default" leaf is set to 12. For a write access operation, if the "write-default" leaf is set
"permit", then permit the data node access request, otherwise to "permit", then permit the data node access request, otherwise
deny the request. deny the request.
3.3.6. Outgoing <notification> Authorization 3.4.6. Outgoing <notification> Authorization
Configuration of access control rules specifically for descendant Configuration of access control rules specifically for descendant
nodes of the notification event type element are outside the scope of nodes of the notification event type element are outside the scope of
this document. If the session is authorized to receive the this document. If the user is authorized to receive the notification
notification event type, then it is also authorized to receive any event type, then it is also authorized to receive any data it
data it contains. contains.
The following figure shows the conceptual message processing model The following figure shows the conceptual message processing model
for outgoing <notification> messages. for outgoing <notification> messages.
NETCONF server NETCONF server
+------------+ +------------+
| XML | | XML |
| message | | message |
| generator | | generator |
+------------+ +------------+
skipping to change at page 27, line 15 skipping to change at page 25, line 48
The generation of a notification for a specific subscription is The generation of a notification for a specific subscription is
authorized by following these steps: authorized by following these steps:
1. If the "enable-nacm" leaf is set to "false", then the 1. If the "enable-nacm" leaf is set to "false", then the
notification is permitted. notification is permitted.
2. If the session is identified as a "recovery session", then the 2. If the session is identified as a "recovery session", then the
notification is permitted. notification is permitted.
3. If the notification is the NETCONF <replayComplete> or 3. If the notification is the NETCONF <replayComplete> or
<notificationComplete> event type, then the notification is <notificationComplete> event type [RFC5277], then the
permitted. notification is permitted.
4. Check all the "group" entries for ones that contain a "user- 4. Check all the "group" entries for ones that contain a "user-
name" entry that equals the user name for the session making the name" entry that equals the user name for the session making the
request. Add to these groups the set of groups provided by the request. Add to these groups the set of groups provided by the
transport layer. transport layer.
5. If no groups are found, continue with step 10. 5. If no groups are found, continue with step 10.
6. Process all rule-list entries, in order. If a rule-list's 6. Process all rule-list entries, in the order they appear in the
"group" leaf-list does not match any of the user's groups, configuration. If a rule-list's "group" leaf-list does not
proceed to the next rule-list entry. match any of the user's groups, proceed to the next rule-list
entry.
7. For each rule-list entry found, process all rules, in order, 7. For each rule-list entry found, process all rules, in order,
until a rule that matches the requested operation is found. A until a rule that matches the requested access operation is
rule matches if all of the following criteria are met: found. A rule matches if all of the following criteria are met:
* The rule's "module-name" leaf is "*", or equals the name of * The rule's "module-name" leaf is "*", or equals the name of
the YANG module where the protocol operation is defined. the YANG module where the notification is defined.
* The rule does not have a "rule-type" defined, or the "rule- * The rule does not have a "rule-type" defined, or the "rule-
type" is "notification" and the "notification-name" is "*", type" is "notification" and the "notification-name" is "*",
equals the name of the notification. equals the name of the notification.
* The rule's "access-operations" leaf has the "read" bit set, * The rule's "access-operations" leaf has the "read" bit set,
or has the special value "*". or has the special value "*".
8. If a matching rule is found, then the "action" leaf is checked. 8. If a matching rule is found, then the "action" leaf is checked.
If it is equal to "permit", then permit the notification, If it is equal to "permit", then permit the notification,
otherwise drop the notification for the associated subscription. otherwise drop the notification for the associated subscription.
9. Otherwise, no matching rule was found in any rule-list entry. 9. Otherwise, no matching rule was found in any rule-list entry.
10. If the requested notification is defined in a YANG module 10. If the requested notification is defined in a YANG module
advertised in the server capabilities, and the "notification" advertised in the server capabilities, and the "notification"
statement contains a "nacm:very-secure" statement, then the statement contains a "nacm:default-deny-all" statement, then the
notification is dropped for the associated subscription. notification is dropped for the associated subscription.
11. If the "read-default" leaf is set to "permit", then permit the 11. If the "read-default" leaf is set to "permit", then permit the
notification, otherwise drop the notification for the associated notification, otherwise drop the notification for the associated
subscription. subscription.
3.4. Data Model Definitions 3.5. Data Model Definitions
This section defines the semantics of the conceptual data structures This section defines the semantics of the conceptual data structures
found in the data model in Section 3.4. found in the data model in Section 3.5.
3.4.1. Data Organization
The top-level element is called <nacm>, and it is defined in the
"ietf-netconf-acm" module's namespace.
There are several data structures defined as child nodes of the
<nacm> element:
leaf <enable-nacm>: On/off boolean switch to enable or disable
access control enforcement.
leaf <read-default>: Enumeration to permit or deny default read
access requests.
leaf <write-default>: Enumeration to permit or deny default write
access requests.
leaf <exec-default>: Enumeration to permit or deny default protocol
operation execution requests.
leaf <denied-rpcs>: Read-only counter of the number of times the
server has denied an RPC operation request, since the last reboot
of the server.
leaf <denied-data-writes>: Read-only counter of the number of times
the server has denied a data node write request, since the last
reboot of the server.
leaf <denied-notifications>: Read-only counter of the number of
times the server has denied a notification, since the last reboot
of the server.
container <groups>: Configures the groups used within the access
control system.
list <group>: A list of user names belonging to the same
administrative group.
container <rules>: Configures the access control rules used within 3.5.1. Data Organization
the server.
list <rule-list>: An ordered collection of related access control The following diagram highlights the contents and structure of the
rules. NACM YANG module.
list <rule>: Configures the access control rules for protocol +--rw nacm
operation invocation, configuration datastore access, and +--rw enable-nacm? boolean
for controlling delivery of <notification> events. +--rw read-default? action-type
+--rw write-default? action-type
+--rw exec-default? action-type
+--ro denied-operations yang:zero-based-counter32
+--ro denied-data-writes yang:zero-based-counter32
+--ro denied-notifications yang:zero-based-counter32
+--rw groups
| +--rw group [name]
| +--rw name group-name-type
| +--rw user-name* user-name-type
+--rw rule-list [name]
+--rw name string
+--rw group* union
+--rw rule [name]
+--rw name string
+--rw module-name? union
+--rw (rule-type)?
| +--:(protocol-operation)
| | +--rw rpc-name? union
| +--:(notification)
| | +--rw notification-name? union
| +--:(data-node)
| +--rw path node-instance-identifier
+--rw access-operations? union
+--rw action action-type
+--rw comment? string
3.4.2. YANG Module 3.5.2. YANG Module
The following YANG module specifies the normative NETCONF content The following YANG module specifies the normative NETCONF content
that MUST by supported by the server. that MUST by supported by the server.
The ietf-netconf-acm 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
<CODE BEGINS> file="ietf-netconf-acm@2011-06-14.yang"
module ietf-netconf-acm {
namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-acm";
prefix "nacm";
import ietf-yang-types {
prefix yang;
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact // RFC Ed.: please update the date to the date of publication
"WG Web: <http://tools.ietf.org/wg/netconf/> <CODE BEGINS> file="ietf-netconf-acm@2011-10-04.yang"
WG List: <mailto:netconf@ietf.org>
WG Chair: Mehmet Ersue module ietf-netconf-acm {
<mailto:mehmet.ersue@nsn.com>
WG Chair: Bert Wijnen namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-acm";
<mailto:bertietf@bwijnen.net> prefix "nacm";
Editor: Andy Bierman import ietf-yang-types {
<mailto:andy.bierman@brocade.com> prefix yang;
}
Editor: Martin Bjorklund organization
<mailto:mbj@tail-f.com>"; "IETF NETCONF (Network Configuration) Working Group";
description contact
"NETCONF Server Access Control Model. "WG Web: <http://tools.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
Copyright (c) 2011 IETF Trust and the persons identified as WG Chair: Mehmet Ersue
authors of the code. All rights reserved. <mailto:mehmet.ersue@nsn.com>
Redistribution and use in source and binary forms, with or WG Chair: Bert Wijnen
without modification, is permitted pursuant to, and subject <mailto:bertietf@bwijnen.net>
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 XXXX; see Editor: Andy Bierman
the RFC itself for full legal notices."; <mailto:andy.bierman@brocade.com>
// RFC Ed.: replace XXXX with actual RFC number and
// remove this note
// RFC Ed.: remove this note Editor: Martin Bjorklund
// Note: extracted from draft-ietf-netconf-access-control-04.txt <mailto:mbj@tail-f.com>";
// RFC Ed.: please update the date to the date of publication
revision "2011-06-14" {
description description
"Initial version"; "NETCONF Access Control Model.
reference
"RFC XXXX: Network Configuration Protocol
Access Control Model";
}
/* Copyright (c) 2011 IETF Trust and the persons identified as
* Extension statements authors of the code. All rights reserved.
*/
extension secure { Redistribution and use in source and binary forms, with or
description without modification, is permitted pursuant to, and subject
"Used to indicate that the data model node to the license terms contained in, the Simplified BSD
represents a sensitive security system parameter. License set forth in Section 4.c of the IETF Trust's
Legal Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info).
If present, and the NACM module is enabled (i.e., This version of this YANG module is part of RFC XXXX; see
/nacm/enable-nacm object equals 'true'), the NETCONF server the RFC itself for full legal notices.";
will only allow the designated 'recovery session' to have // RFC Ed.: replace XXXX with actual RFC number and
write or execute access to the node. An explicit access // remove this note
control rule is required for all other users.
The 'secure' extension MAY appear within a data definition // RFC Ed.: remove this note
statement or rpc statement. It is ignored otherwise."; // Note: extracted from draft-ietf-netconf-access-control-05.txt
}
extension very-secure { // RFC Ed.: please update the date to the date of publication
description revision "2011-10-04" {
"Used to indicate that the data model node description
controls a very sensitive security system parameter. "Initial version";
reference
"RFC XXXX: Network Configuration Protocol
Access Control Model";
}
If present, and the NACM module is enabled (i.e., /*
/nacm/enable-nacm object equals 'true'), the NETCONF server * Extension statements
will only allow the designated 'recovery session' to have */
read, write, or execute access to the node. An explicit
access control rule is required for all other users.
The 'very-secure' extension MAY appear within a data extension default-deny-write {
definition statement, rpc statement, or notification description
statement. It is ignored otherwise."; "Used to indicate that the data model node
} represents a sensitive security system parameter.
/* If present, and the NACM module is enabled (i.e.,
* Derived types /nacm/enable-nacm object equals 'true'), the NETCONF server
*/ will only allow the designated 'recovery session' to have
write access to the node. An explicit access control rule is
required for all other users.
typedef user-name-type { The 'default-deny-write' extension MAY appear within a data
type string { definition statement. It is ignored otherwise.";
length "1..max";
} }
description
"General Purpose User Name string.";
}
typedef matchall-string-type { extension default-deny-all {
type string { description
pattern "\*"; "Used to indicate that the data model node
} controls a very sensitive security system parameter.
description
"The string containing a single asterisk '*' is used
to conceptually represent all possible values
for the particular leaf using this data type.";
}
typedef access-operations-type { If present, and the NACM module is enabled (i.e.,
type bits { /nacm/enable-nacm object equals 'true'), the NETCONF server
bit create { will only allow the designated 'recovery session' to have
description read, write, or execute access to the node. An explicit
"Any operation that creates a access control rule is required for all other users.
new instance of the specified data is a create
operation.";
}
bit read {
description
"Any operation or notification that
returns data to an application is a read
operation.";
}
bit update {
description
"Any operation that alters an existing
data node is an update operation.";
}
bit delete {
description
"Any operation that removes a datastore
node instance is a delete operation.";
}
bit exec {
description
"Execution access to the specified RPC operation.
Any RPC operation invocation is an exec operation.";
}
}
description
"NETCONF Access Operation.";
}
typedef group-name-type { The 'default-deny-all' extension MAY appear within a data
type string { definition statement, 'rpc' statement, or 'notification'
length "1..max"; statement. It is ignored otherwise.";
pattern "[^\*].*";
} }
description
"Name of administrative group that can be
assigned to the user, and specified in
an access control rule-list.";
}
typedef action-type { /*
type enumeration { * Derived types
enum permit { */
description
"Requested action is permitted.";
}
enum deny {
description
"Requested action is denied.";
typedef user-name-type {
type string {
length "1..max";
} }
}
description
"Action taken by the server when a particular
rule matches.";
}
typedef node-instance-identifier {
type yang:xpath1.0;
description
"Path expression used to represent a special
data node instance identifier string.
A node-instance-identifier value is an
unrestricted YANG instance-identifier expression.
All the same rules as an instance-identifier apply
except predicates for keys are optional. If a key
predicate is missing, then the node-instance-identifier
represents all possible server instances for that key.
This XPath expression is evaluated in the following context:
o The set of namespace declarations are those in scope on
the leaf element where this type is used.
o The set of variable bindings contains one variable,
'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.";
}
container nacm {
nacm:very-secure;
description
"Parameters for NETCONF Access Control Model.";
leaf enable-nacm {
type boolean;
default true;
description description
"Enable or disable all NETCONF access control "General Purpose User Name string.";
enforcement. If 'true', then enforcement
is enabled. If 'false', then enforcement
is disabled.";
} }
leaf read-default { typedef matchall-string-type {
type action-type; type string {
default "permit"; pattern "\*";
}
description description
"Controls whether read access is granted if "The string containing a single asterisk '*' is used
no appropriate rule is found for a to conceptually represent all possible values
particular read request."; for the particular leaf using this data type.";
} }
leaf write-default { typedef access-operations-type {
type action-type; type bits {
default "deny"; bit create {
description
"Any protocol operation that creates a
new data node.";
}
bit read {
description
"Any protocol operation or notification that
returns the value of a data node.";
}
bit update {
description
"Any protocol operation that alters an existing
data node.";
}
bit delete {
description
"Any protocol operation that removes a data node.";
}
bit exec {
description
"Execution access to the specified protocol operation.";
}
}
description description
"Controls whether create, update, or delete access "NETCONF Access Operation.";
is granted if no appropriate rule is found for a
particular write request.";
} }
leaf exec-default { typedef group-name-type {
type action-type; type string {
default "permit"; length "1..max";
pattern "[^\*].*";
}
description description
"Controls whether exec access is granted if no appropriate "Name of administrative group to which
rule is found for a particular RPC operation request."; users can be assigned.";
} }
leaf denied-rpcs { typedef action-type {
type yang:zero-based-counter32; type enumeration {
config false; enum permit {
mandatory true; description
"Requested action is permitted.";
}
enum deny {
description
"Requested action is denied.";
}
}
description description
"Number of times an RPC operation request was denied "Action taken by the server when a particular
since the server last restarted."; rule matches.";
} }
leaf denied-data-writes { typedef node-instance-identifier {
type yang:zero-based-counter32; type yang:xpath1.0;
config false;
mandatory true;
description
"Number of times a request to alter a data node
was denied, since the server last restarted.";
}
leaf denied-notifications {
type yang:zero-based-counter32;
config false;
mandatory true;
description description
"Number of times a notification was denied "Path expression used to represent a special
since the server last restarted."; data node instance identifier string.
A node-instance-identifier value is an
unrestricted YANG instance-identifier expression.
All the same rules as an instance-identifier apply
except predicates for keys are optional. If a key
predicate is missing, then the node-instance-identifier
represents all possible server instances for that key.
This XPath expression is evaluated in the following context:
o The set of namespace declarations are those in scope on
the leaf element where this type is used.
o The set of variable bindings contains one variable,
'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.";
} }
container groups { container nacm {
nacm:default-deny-all;
description description
"NETCONF Access Control Groups."; "Parameters for NETCONF Access Control Model.";
list group { leaf enable-nacm {
key name; 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.";
}
leaf read-default {
type action-type;
default "permit";
description description
"One NACM Group Entry."; "Controls whether read access is granted if
no appropriate rule is found for a
particular read request.";
}
leaf name { leaf write-default {
type group-name-type; type action-type;
description default "deny";
"Group name associated with this entry."; description
} "Controls whether create, update, or delete access
is granted if no appropriate rule is found for a
particular write request.";
}
leaf-list user-name { leaf exec-default {
type user-name-type; type action-type;
description default "permit";
"Each entry identifies the user name of description
a member of the group associated with "Controls whether exec access is granted if no appropriate
this entry."; rule is found for a particular protocol operation request.";
} }
leaf denied-operations {
type yang:zero-based-counter32;
config false;
mandatory true;
description
"Number of times a protocol operation request was denied
since the server last restarted.";
} }
}
list rule-list { leaf denied-data-writes {
key "name"; type yang:zero-based-counter32;
ordered-by user; config false;
description mandatory true;
"An ordered collection of access control rules."; description
"Number of times a protocol operation request to alter
a configuration datastore was denied, since the
server last restarted.";
}
leaf name { leaf denied-notifications {
type string { type yang:zero-based-counter32;
length "1..256"; config false;
} mandatory true;
description description
"Arbitrary name assigned to the rule-list."; "Number of times a notification was dropped
for a subscription because access to
the event type was denied, since the server
last restarted.";
} }
leaf-list group {
type union { container groups {
type matchall-string-type;
type group-name-type;
}
description description
"List of administrative groups that will be "NETCONF Access Control Groups.";
assigned the associated access rights
defined by the 'rule' list.
The string '*' indicates that all groups apply to the list group {
entry."; key name;
description
"One NACM Group Entry.";
leaf name {
type group-name-type;
description
"Group name associated with this entry.";
}
leaf-list user-name {
type user-name-type;
description
"Each entry identifies the user name of
a member of the group associated with
this entry.";
}
}
} }
list rule { list rule-list {
key "name"; key "name";
ordered-by user; ordered-by user;
description description
"One access control rule. "An ordered collection of access control rules.";
Rules are processed in user-defined order until a match is
found. A rule matches if 'module-name', 'rule-type', and
'access-operations' matches the request. If a rule
matches, the 'action' leaf determines if access is granted
or not.";
leaf name { leaf name {
type string { type string {
length "1..256"; length "1..max";
} }
description description
"Arbitrary name assigned to the rule."; "Arbitrary name assigned to the rule-list.";
} }
leaf-list group {
leaf module-name {
type union { type union {
type matchall-string-type; type matchall-string-type;
type string; type group-name-type;
} }
default "*";
description description
"Name of the module associated with this rule. "List of administrative groups that will be
assigned the associated access rights
defined by the 'rule' list.
This leaf matches if it has the value '*', or if the The string '*' indicates that all groups apply to the
object being accessed is defined in the module with the entry.";
specified module name.";
} }
choice rule-type {
list rule {
key "name";
ordered-by user;
description description
"This choice matches if all leafs present in the rule "One access control rule.
matches the request. If no leafs are present, the
choice matches all requests."; Rules are processed in user-defined order until a match is
case protocol-operation { found. A rule matches if 'module-name', 'rule-type', and
leaf rpc-name { 'access-operations' matches the request. If a rule
type union { matches, the 'action' leaf determines if access is granted
type matchall-string-type; or not.";
type string;
} leaf name {
description type string {
"This leaf matches if it has the value '*', or if its length "1..max";
value equals the requested RPC operation name.";
} }
description
"Arbitrary name assigned to the rule.";
} }
case notification {
leaf notification-name { leaf module-name {
type union { type union {
type matchall-string-type; type matchall-string-type;
type string; type string;
}
description
"This leaf matches if it has the value '*', or if its
value equals the requested notification name.";
} }
default "*";
description
"Name of the module associated with this rule.
This leaf matches if it has the value '*', or if the
object being accessed is defined in the module with the
specified module name.";
} }
case data-node { choice rule-type {
leaf path { description
type node-instance-identifier; "This choice matches if all leafs present in the rule
mandatory true; matches the request. If no leafs are present, the
description choice matches all requests.";
"Data Node Instance Identifier associated with the data case protocol-operation {
node controlled by this rule. leaf rpc-name {
type union {
type matchall-string-type;
type string;
}
description
"This leaf matches if it has the value '*', or if
its value equals the requested protocol operation
name.";
}
}
case notification {
leaf notification-name {
type union {
type matchall-string-type;
type string;
}
description
"This leaf matches if it has the value '*', or if its
value equals the requested notification name.";
}
}
case data-node {
leaf path {
type node-instance-identifier;
mandatory true;
description
"Data Node Instance Identifier associated with the
data node controlled by this rule.
Configuration data or state data instance Configuration data or state data instance
identifiers start with a top-level data node. A identifiers start with a top-level data node. A
complete instance identifier is required for this complete instance identifier is required for this
type of path value. type of path value.
The special value '/' refers to all possible data The special value '/' refers to all possible data
store contents."; store contents.";
}
} }
} }
}
leaf access-operations { leaf access-operations {
type union { type union {
type matchall-string-type; type matchall-string-type;
type access-operations-type; type access-operations-type;
}
default "*";
description
"Access operations associated with this rule.
This leaf matches if it has the value '*', or if the
bit corresponding to the requested operation is set.";
} }
default "*";
description
"Access operations associated with this rule.
This leaf matches if it has the value '*', or if the leaf action {
bit corresponding to the requested operation is set."; type action-type;
} mandatory true;
description
"The access control action associated with the
rule. If a rule is determined to match a
particular request, then this object is used
to determine whether to permit or deny the
request.";
}
leaf action { leaf comment {
type action-type; type string;
mandatory true; description
description "A textual description of the access rule.";
"The access control action associated with the }
rule. If a rule is determined to match a
particular request, then this object is used
to determine whether to permit or deny the
request.";
}
leaf comment {
type string;
description
"A textual description of the access rule.";
} }
} }
} }
} }
}
<CODE ENDS> <CODE ENDS>
Figure 5 Figure 5
3.5. IANA Considerations 3.6. IANA Considerations
There are two actions that are requested of IANA: This document There are two actions that are requested of IANA: This document
registers one URI in "The IETF XML Registry". Following the format registers one URI in "The IETF XML Registry". Following the format
in [RFC3688], the following has been registered. in [RFC3688], the following has been registered.
URI: urn:ietf:params:xml:ns:yang:ietf-netconf-acm URI: urn:ietf:params:xml:ns:yang:ietf-netconf-acm
Registrant Contact: The IESG. Registrant Contact: The IESG.
XML: N/A, the requested URI is an XML namespace. XML: N/A, the requested URI is an XML namespace.
This document registers one module in the "YANG Module Names" This document registers one module in the "YANG Module Names"
registry. Following the format in [RFC6020], the following has been registry. Following the format in [RFC6020], the following has been
registered. registered.
name: ietf-netconf-acm name: ietf-netconf-acm
namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-acm namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-acm
prefix: nacm prefix: nacm
reference: RFC XXXX reference: RFC XXXX
// RFC Ed.: Replace XXX with actual RFC number // RFC Ed.: Replace XXX with actual RFC number
// and remove this note // and remove this note
3.6. Security Considerations 3.7. Security Considerations
This entire document discusses access control requirements and This entire document discusses access control requirements and
mechanisms for restricting NETCONF protocol behavior within a given mechanisms for restricting NETCONF protocol behavior within a given
session. session.
This section highlights the issues for an administrator to consider
when configuring a NETCONF server with NACM.
3.7.1. NACM Configuration and Monitoring Considerations
Configuration of the access control system is highly sensitive to Configuration of the access control system is highly sensitive to
system security. A server may choose not to allow any user system security. A server may choose not to allow any user
configuration to some portions of it, such as the global security configuration to some portions of it, such as the global security
level, or the groups which allowed access to system resources. level, or the groups which allowed access to system resources.
This document incorporates the optional use of a "recovery session" By default, NACM enforcement is enabled. By default, "read" access
mechanism, which can be used to bypass access control enforcement in to all datastore contents enabled, (unless "nacm:default-deny-all" is
emergencies, such as NACM configuration errors which disable all specified for the data definition) and "exec" access is enabled for
access to the server. The configuration and identification of such a safe protocol operations. An administrator needs to ensure that NACM
recovery session mechanism are outside the scope of this document. is enabled, and also decide if the default access parameters are set
appropriately. Make sure the following data nodes are properly
configured:
There is a risk that invocation of non-standard protocol operations o /nacm/enable-nacm (default "true")
will have undocumented side effects. An administrator needs to
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 during a "recovery session".
There is a risk that non-standard protocol operations, or even the o /nacm/read-default (default "permit")
standard <get> operation, may return data which "aliases" or "copies"
sensitive data from a different data object. In this case, the o /nacm/write-default (default "deny")
namespace and/or the element name will not match the values for the
sensitive data, which is then fully or partially copied into a o /nacm/exec-default (default "permit")
different namespace and/or element. An administrator needs to avoid
using data models which use this practice.
An administrator needs to restrict write access to all configurable An administrator needs to restrict write access to all configurable
objects within this data model. objects within this data model.
If write access is allowed for configuration of access control rules, If write access is allowed for configuration of access control rules,
then care needs to be taken not to disrupt the access control then care needs to be taken not to disrupt the access control
enforcement. enforcement. For example, if the NACM access control rules are
editing directly within the running configuration datastore (i.e.,
:writable-running capability is supported and used), then care needs
to be taken not to allow unintended access while the edits are being
done.
NACM requires some a user name in each NACM group mapping. An
administrator needs to make sure that the translation from a
transport or implementation dependant user identity to a NACM user
name is unique.
An administrator needs to restrict read access to the following An administrator needs to restrict read access to the following
objects within this data model, which reveal access control objects within this data model, which reveal access control
configuration which could be considered sensitive. configuration which could be considered sensitive.
o enable-nacm o /nacm/enable-nacm
o read-default o /nacm/read-default
o write-default o /nacm/write-default
o exec-default o /nacm/exec-default
o groups o /nacm/groups
o rules o /nacm/rule-list
3.7.2. General Configuration Issues
There is a risk that invocation of non-standard protocol operations
will have undocumented side effects. An administrator needs to
construct access control rules such that the configuration datastore
is protected from such side effects.
It is possible for a session with some write access (e.g., allowed to
invoke <edit-config>), but without any access to a particular
datastore subtree containing sensitive data, to determine the
presence or non-presence of that data. This can be done by
repeatedly issuing some sort of edit request (create, update, or
delete) and possibly receiving "access-denied" errors in response.
These "fishing" attacks can identify the presence or non-presence of
specific sensitive data even without the "error-path" field being
present within the "rpc-error" response.
It is possible that the data model definition itself (e.g., YANG
when-stmt) will help an unauthorized session determine the presence
or even value of sensitive data nodes by examining the presence and
values of different data nodes.
There is a risk that non-standard protocol operations, or even the
standard <get> protocol operation, may return data which "aliases" or
"copies" sensitive data from a different data object. There may
simply be multiple data model definitions which expose or even
configure the same underlying system instrumentation.
A data model may contain external keys (e.g., YANG leafref), which
expose values from a different data structure. An administrator
needs to be aware of sensitive data models which contain leafref
nodes. This entails finding all the leafref objects that "point" at
the sensitive data (i.e., "path-stmt" values that implicitly or
explicitly include the sensitive data node.
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 administrator can
identify each protocol operation that the server provides, and decide
if it needs any access control applied to it.
This document incorporates the optional use of a "recovery session"
mechanism, which can be used to bypass access control enforcement in
emergencies, such as NACM configuration errors which disable all
access to the server. The configuration and identification of such a
recovery session mechanism are implementation-specific and outside
the scope of this document. An administrator needs to be aware of
any "recovery session" mechanisms available on the device, and make
sure they are used appropriately.
It is possible for a session to disrupt configuration management,
even without any write access to the configuration, by locking the
datastore. This may be done to insure all or part of the
configuration remains stable while it is being retrieved, ot it may
be done as a "denial-of-service" attack. There is no way for the
server to know the difference. An administrator may wish to restrict
"exec" access to the following protocol operations:
o <lock>
o <unlock>
o <partial-lock>
o <partial-unlock>
3.7.3. Data Model Design Considerations
Designers need to clearly identify any sensitive data, notifications,
or protocol operations defined within a YANG module. For such
definitions, a "nacm:default-deny-write" or "nacm:default-deny-all"
statement SHOULD be present, in addition to a clear description of
the security risks.
Protocol operations need to be properly documented by the data model
designer, so it is clear to administrators what data nodes (if any)
are affected by the protocol operation, and what information (if any)
is returned in the <rpc-reply> message.
Data models ought to be designed so that different access levels for
input parameters to protocol operations is not required. Use of
generic protocol operations should be avoided, and separate protocol
operations defined instead, if different access levels are needed.
4. References 4. References
4.1. Normative References 4.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004. January 2004.
skipping to change at page 41, line 25 skipping to change at page 41, line 25
[RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event [RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event
Notifications", RFC 5277, July 2008. Notifications", RFC 5277, July 2008.
[RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the [RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the
Network Configuration Protocol (NETCONF)", RFC 6020, Network Configuration Protocol (NETCONF)", RFC 6020,
October 2010. October 2010.
[RFC6021] Schoenwaelder, J., "Common YANG Data Types", RFC 6021, [RFC6021] Schoenwaelder, J., "Common YANG Data Types", RFC 6021,
October 2010. October 2010.
[I-D.ietf-netconf-4741bis] [RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
Bierman, "Network Configuration Protocol (NETCONF)", Bierman, "Network Configuration Protocol (NETCONF)",
draft-ietf-netconf-4741bis-10 (work in progress), RFC 6241, June 2011.
March 2011.
[I-D.ietf-netconf-rfc4742bis] [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Wasserman, M. and T. Goddard, "Using the NETCONF Shell (SSH)", RFC 6242, June 2011.
Configuration Protocol over Secure Shell (SSH)",
draft-ietf-netconf-rfc4742bis-08 (work in progress),
March 2011.
4.2. Informative References 4.2. Informative References
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)", "Remote Authentication Dial In User Service (RADIUS)",
RFC 2865, June 2000. RFC 2865, June 2000.
[RFC5607] Nelson, D. and G. Weber, "Remote Authentication Dial-In [RFC5607] Nelson, D. and G. Weber, "Remote Authentication Dial-In
User Service (RADIUS) Authorization for Network Access User Service (RADIUS) Authorization for Network Access
Server (NAS) Management", RFC 5607, July 2009. Server (NAS) Management", RFC 5607, July 2009.
skipping to change at page 42, line 28 skipping to change at page 42, line 28
<nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm"> <nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm">
<groups> <groups>
<group> <group>
<name>admin</name> <name>admin</name>
<user-name>admin</user-name> <user-name>admin</user-name>
<user-name>andy</user-name> <user-name>andy</user-name>
</group> </group>
<group> <group>
<name>monitor</name> <name>limited</name>
<user-name>wilma</user-name> <user-name>wilma</user-name>
<user-name>bam-bam</user-name> <user-name>bam-bam</user-name>
</group> </group>
<group> <group>
<name>guest</name> <name>guest</name>
<user-name>guest</user-name> <user-name>guest</user-name>
<user-name>guest@example.com</user-name> <user-name>guest@example.com</user-name>
</group> </group>
</groups> </groups>
</nacm> </nacm>
This example shows 3 groups: This example shows 3 groups:
1. The "admin" group contains 2 users named "admin" and "andy". 1. The "admin" group contains 2 users named "admin" and "andy".
2. The "monitor" group contains 2 users named "wilma" and "bam-bam". 2. The "limited" group contains 2 users named "wilma" and "bam-bam".
3. The "guest" group contains 2 users named "guest" and 3. The "guest" group contains 2 users named "guest" and
"guest@example.com". "guest@example.com".
A.2. Module Rule Example A.2. Module Rule Example
Module rules are used to control access to all the content defined in Module rules are used to control access to all the content defined in
a specific module. A module rule has the <module-name> leaf set, but a specific module. A module rule has the <module-name> leaf set, but
no case in the "rule-type" choice. no case in the "rule-type" choice.
<nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm"> <nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm">
<rule-list> <rule-list>
<name>guest</name> <name>guest-acl</name>
<group>guest</group> <group>guest</group>
<rule> <rule>
<name>mod-1</name> <name>deny-ncm</name>
<module-name>ietf-netconf-monitoring</module-name> <module-name>ietf-netconf-monitoring</module-name>
<access-operations>*</access-operations> <access-operations>*</access-operations>
<action>deny</action> <action>deny</action>
<comment> <comment>
Do not allow guests any access to the netconf Do not allow guests any access to the netconf
monitoring information. monitoring information.
</comment> </comment>
</rule> </rule>
</rule-list> </rule-list>
<rule-list> <rule-list>
<name>monitor example</name> <name>limited-acl</name>
<group>monitor</group> <group>limited</group>
<rule> <rule>
<name>mod-2</name> <name>permit-ncm</name>
<module-name>ietf-netconf-monitoring</module-name> <module-name>ietf-netconf-monitoring</module-name>
<access-operations>read</access-operations> <access-operations>read</access-operations>
<action>permit</action> <action>permit</action>
<comment> <comment>
Allow read access to the netconf Allow read access to the netconf
monitoring information. monitoring information.
</comment> </comment>
</rule> </rule>
<rule> <rule>
<name>mod-3</name> <name>permit-exec</name>
<module-name>*</module-name> <module-name>*</module-name>
<access-operations>exec</access-operations> <access-operations>exec</access-operations>
<action>permit</action> <action>permit</action>
<comment> <comment>
Allow invocation of the Allow invocation of the
supported server operations. supported server operations.
</comment> </comment>
</rule> </rule>
</rule-list> </rule-list>
<rule-list> <rule-list>
<name>admin example</name> <name>admin-acl</name>
<group>admin</group> <group>admin</group>
<rule> <rule>
<name>mod-4</name> <name>permit-all</name>
<module-name>*</module-name> <module-name>*</module-name>
<access-operations>*</access-operations> <access-operations>*</access-operations>
<action>permit</action> <action>permit</action>
<comment> <comment>
Allow the admin group complete access to all Allow the admin group complete access to all
operations and data. operations and data.
</comment> </comment>
</rule> </rule>
</rule-list> </rule-list>
</nacm> </nacm>
This example shows 4 module rules: This example shows 4 module rules:
mod-1: This rule prevents the guest group from reading any deny-ncm: This rule prevents the "guest" group from reading any
monitoring information in the ietf-netconf-monitoring YANG module. monitoring information in the "ietf-netconf-monitoring" YANG
module.
mod-2: This rule allows the monitor group to read the ietf-netconf- permit-ncm: This rule allows the "limited" group to read the "ietf-
monitoring YANG module. netconf-monitoring" YANG module.
mod-3: This rule allows the monitor group to invoke any protocol permit-exec: This rule allows the "limited" group to invoke any
operation supported by the server. protocol operation supported by the server.
mod-4: This rule allows the admin group complete access to all permit-all: This rule allows the "admin" group complete access to
content in the server. No subsequent rule will match for the all content in the server. No subsequent rule will match for the
admin group, because of this module rule. "admin" group, because of this module rule.
A.3. RPC Rule Example A.3. RPC Rule Example
RPC rules are used to control access to a specific protocol RPC rules are used to control access to a specific protocol
operation. operation.
<nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm"> <nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm">
<rule-list> <rule-list>
<name>guest</name> <name>guest-limited-acl</name>
<group>monitor</group> <group>limited</group>
<group>guest</group> <group>guest</group>
<rule> <rule>
<name>rpc-1</name> <name>deny-kill-session</name>
<module-name>ietf-netconf</module-name> <module-name>ietf-netconf</module-name>
<rpc-name>kill-session</rpc-name> <rpc-name>kill-session</rpc-name>
<access-operations>exec</access-operations> <access-operations>exec</access-operations>
<action>deny</action> <action>deny</action>
<comment> <comment>
Do not allow the monitor or guest group Do not allow the limited or guest group
to kill another session. to kill another session.
</comment> </comment>
</rule> </rule>
<rule> <rule>
<name>rpc-2</name> <name>deny-delete-config</name>
<module-name>ietf-netconf</module-name> <module-name>ietf-netconf</module-name>
<rpc-name>delete-config</rpc-name> <rpc-name>delete-config</rpc-name>
<access-operations>exec</access-operations> <access-operations>exec</access-operations>
<action>deny</action> <action>deny</action>
<comment> <comment>
Do not allow monitor or guest group Do not allow limited or guest group
to delete any configurations. to delete any configurations.
</comment> </comment>
</rule> </rule>
</rule-list> </rule-list>
<rule-list> <rule-list>
<name>monitor</name> <name>limited-acl</name>
<group>monitor</group> <group>limited</group>
<rule> <rule>
<name>rpc-3</name> <name>permit-edit-config</name>
<module-name>ietf-netconf</module-name> <module-name>ietf-netconf</module-name>
<rpc-name>edit-config</rpc-name> <rpc-name>edit-config</rpc-name>
<access-operations>exec</access-operations> <access-operations>exec</access-operations>
<action>permit</action> <action>permit</action>
<comment> <comment>
Allow the monitor group to edit the configuration. Allow the limited group to edit the configuration.
</comment> </comment>
</rule> </rule>
</rule-list> </rule-list>
</nacm> </nacm>
This example shows 3 protocol operation rules: This example shows 3 protocol operation rules:
rpc-1: This rule prevents the monitor or guest groups from invoking deny-kill-session: This rule prevents the "limited" or "guest"
the NETCONF <kill-session> protocol operation. groups from invoking the NETCONF <kill-session> protocol
operation.
rpc-2: This rule prevents the monitor or guest groups from invoking deny-delete-config: This rule prevents the "limited" or "guest"
the NETCONF <delete-config> protocol operation. groups from invoking the NETCONF <delete-config> protocol
operation.
rpc-3: This rule allows the monitor group to invoke the NETCONF permit-edit-config: This rule allows the "limited" group to invoke
<edit-config> protocol operation. This rule will have no real the NETCONF <edit-config> protocol operation. This rule will have
effect unless the "exec-default" leaf is set to "deny". no real effect unless the "exec-default" leaf is set to "deny".
A.4. Data Rule Example A.4. Data Rule Example
Data rules are used to control access to specific (config and non- Data rules are used to control access to specific (config and non-
config) data nodes within the NETCONF content provided by the server. config) data nodes within the NETCONF content provided by the server.
<nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm"> <nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm">
<rule-list> <rule-list>
<name>guest rules</name> <name>guest-acl</name>
<group>guest</group> <group>guest</group>
<rule> <rule>
<name>data-1</name> <name>deny-nacm</name>
<path xmlns:n="urn:ietf:params:xml:ns:yang:ietf-netconf-acm"> <path xmlns:n="urn:ietf:params:xml:ns:yang:ietf-netconf-acm">
/n:nacm /n:nacm
</path> </path>
<access-operations>*</access-operations> <access-operations>*</access-operations>
<action>deny</action> <action>deny</action>
<comment> <comment>
Deny the guest group any access to the /nacm data. Deny the guest group any access to the /nacm data.
</comment> </comment>
</rule> </rule>
</rule-list> </rule-list>
<rule-list> <rule-list>
<name>monitor rules</name> <name>limited-acl</name>
<group>monitor</group> <group>limited</group>
<rule> <rule>
<name>data-acme-config</name> <name>permit-acme-config</name>
<path xmlns:acme="http://example.com/ns/netconf"> <path xmlns:acme="http://example.com/ns/netconf">
/acme:acme-netconf/acme:config-parameters /acme:acme-netconf/acme:config-parameters
</path> </path>
<access-operations> <access-operations>
read create update delete read create update delete
</access-operations> </access-operations>
<action>permit</action> <action>permit</action>
<comment> <comment>
Allow the monitor group complete access to the acme Allow the limited group complete access to the acme
netconf configuration parameters. Showing long form netconf configuration parameters. Showing long form
of 'access-operations' instead of shorthand. of 'access-operations' instead of shorthand.
</comment> </comment>
</rule> </rule>
</rule-list> </rule-list>
<rule-list> <rule-list>
<name>dummy-itf</name> <name>guest-limited-acl</name>
<group>guest monitor</group> <group>guest</group>
<group>limited</group>
<rule> <rule>
<name>dummy-itf</name> <name>permit-dummy-interface</name>
<path xmlns:acme="http://example.com/ns/itf"> <path xmlns:acme="http://example.com/ns/itf">
/acme:interfaces/acme:interface[acme:name='dummy'] /acme:interfaces/acme:interface[acme:name='dummy']
</path> </path>
<access-operations>read update</access-operations> <access-operations>read update</access-operations>
<action>permit</action> <action>permit</action>
<comment> <comment>
Allow the monitor and guest groups read Allow the limited and guest groups read
and update access to the dummy interface. and update access to the dummy interface.
</comment> </comment>
</rule> </rule>
</rule-list> </rule-list>
<rule-list> <rule-list>
<name>admin rules</name> <name>admin-acl</name>
<rule> <rule>
<name>admin-itf</name> <name>permit-interface</name>
<path xmlns:acme="http://example.com/ns/itf"> <path xmlns:acme="http://example.com/ns/itf">
/acme:interfaces/acme:interface /acme:interfaces/acme:interface
</path> </path>
<access-operations>*</access-operations> <access-operations>*</access-operations>
<action>permit</action> <action>permit</action>
<comment> <comment>
Allow admin full access to all acme interfaces. Allow admin full access to all acme interfaces.
</comment> </comment>
</rule> </rule>
</rule-list> </rule-list>
skipping to change at page 47, line 46 skipping to change at page 48, line 4
/acme:interfaces/acme:interface /acme:interfaces/acme:interface
</path> </path>
<access-operations>*</access-operations> <access-operations>*</access-operations>
<action>permit</action> <action>permit</action>
<comment> <comment>
Allow admin full access to all acme interfaces. Allow admin full access to all acme interfaces.
</comment> </comment>
</rule> </rule>
</rule-list> </rule-list>
</nacm> </nacm>
This example shows 4 data rules: This example shows 4 data rules:
data-1: This rule denies the guest group any access to the <nacm> deny-nacm: This rule denies the "guest" group any access to the
subtree. Note that the default namespace is only applicable <nacm> subtree. Note that the default namespace is only
because this subtree is defined in the same namespace as the applicable because this subtree is defined in the same namespace
<data-rule> element. as the <data-rule> element.
data-acme-config: This rule gives the monitor group read-write permit-acme-config: This rule gives the "limited" group read-write
access to the acme <config-parameters>. access to the acme <config-parameters>.
dummy-itf: This rule gives the monitor and guest groups read-update permit-dummy-interface: This rule gives the "limited" and "guest"
access to the acme <interface>. entry named "dummy". This entry groups read-update access to the acme <interface>. entry named
cannot be created or deleted by these groups, just altered. "dummy". This entry cannot be created or deleted by these groups,
just altered.
admin-itf: This rule gives the admin group read-write access to all permit-interface: This rule gives the "admin" group read-write
acme <interface>. entries. This is an example of an unreachable access to all acme <interface>. entries. This is an example of an
rule because the "mod-3" rule already gives the admin group full unreachable rule because the "mod-3" rule already gives the
access to this data. "admin" group full access to this data.
A.5. Notification Rule Example A.5. Notification Rule Example
Notification rules are used to control access to a specific Notification rules are used to control access to a specific
notification event type. notification event type.
<nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm"> <nacm xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-acm">
<rule-list> <rule-list>
<name>sys</name> <name>sys-acl</name>
<group>monitor</group> <group>limited</group>
<group>guest</group> <group>guest</group>
<rule> <rule>
<name>notif-1</name> <name>deny-config-change</name>
<module-name>acme-system</module-name> <module-name>acme-system</module-name>
<notification-name>sys-config-change</notification-name> <notification-name>sys-config-change</notification-name>
<access-operations>read</access-operations> <access-operations>read</access-operations>
<action>deny</action> <action>deny</action>
<comment> <comment>
Do not allow the guest or monitor groups Do not allow the guest or limited groups
to receive config change events. to receive config change events.
</comment> </comment>
</rule> </rule>
</rule-list> </rule-list>
</nacm> </nacm>
This example shows 1 notification rule: This example shows 1 notification rule:
notif-1: This rule prevents the monitor or guest groups from deny-config-change: This rule prevents the "limited" or "guest"
receiving the acme <sys-config-change> event type. groups from receiving the acme <sys-config-change> event type.
Appendix B. Change Log Appendix B. Change Log
-- RFC Ed.: remove this section before publication. -- RFC Ed.: remove this section before publication.
B.1. 03-04 B.1. 04-05
Updated Security Considerations section.
Changed term 'operator' to 'administrator'.
Used the terms "access operation" and "protocol operation"
consistently.
Moved some normative text from section 2 to section 3. Also made it
more clear that section 2 is not a requirements section, but
documentation of the objectives for NACM.
Renamed "nacm:secure" to "nacm:default-deny-write", and "nacm:very-
secure" to "nacm:default-deny-all". Explained that "nacm:default-
deny-write" is ignored on rpc statements.
Described that <kill-session> and <delete-config> behave as if
specified with "nacm:default-deny-all".
B.2. 03-04
Introduced rule-lists to group related rules together. Introduced rule-lists to group related rules together.
Moved "module-rule", "rpc-rule", "notification-rule", and "data-rule" Moved "module-rule", "rpc-rule", "notification-rule", and "data-rule"
into one common "rule", with a choice to select between the four into one common "rule", with a choice to select between the four
variants. variants.
Changed "superuser" to "recovery session", and adjusted text Changed "superuser" to "recovery session", and adjusted text
throughout document for this change. throughout document for this change.
Clarified behavior of global default NACM parameters, enable-nacm, Clarified behavior of global default NACM parameters, enable-nacm,
read-default, write-default, exec-default. read-default, write-default, exec-default.
Clarified when access control is applied during system Clarified when access control is applied during system
initialization. initialization.
B.2. 02-03 B.3. 02-03
Fixed improper usage of RFC 2119 keywords. Fixed improper usage of RFC 2119 keywords.
Changed term usage of "database" to "datastore". Changed term usage of "database" to "datastore".
Clarified that "secure" and "very-secure" extensions only apply if Clarified that "secure" and "very-secure" extensions only apply if
the /nacm/enable-nacm object is "true". the /nacm/enable-nacm object is "true".
B.3. 01-02 B.4. 01-02
Removed authentication text and objects. Removed authentication text and objects.
Changed module name from ietf-nacm to ietf-netconf-acm. Changed module name from ietf-nacm to ietf-netconf-acm.
Updated NETCONF and YANG terminology. Updated NETCONF and YANG terminology.
Removed open issues section. Removed open issues section.
Changed some must to MUST in requirements section. Changed some must to MUST in requirements section.
B.4. 00-01 B.5. 00-01
Updated YANG anf YANG Types references. Updated YANG anf YANG Types references.
Updated module namespace URI to standard format. Updated module namespace URI to standard format.
Updated module header meta-data to standard format. Updated module header meta-data to standard format.
Filled in IANA section. Filled in IANA section.
B.5. 00 B.6. 00
Initial version cloned from Initial version cloned from
draft-bierman-netconf-access-control-02.txt. draft-bierman-netconf-access-control-02.txt.
Authors' Addresses Authors' Addresses
Andy Bierman Andy Bierman
Brocade Brocade
Email: andy.bierman@brocade.com Email: andy.bierman@brocade.com
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