draft-ietf-netconf-access-control-06.txt   draft-ietf-netconf-access-control-07.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: May 3, 2012 Tail-f Systems Expires: June 25, 2012 Tail-f Systems
October 31, 2011 December 23, 2011
Network Configuration Protocol (NETCONF) Access Control Model Network Configuration Protocol (NETCONF) Access Control Model
draft-ietf-netconf-access-control-06 draft-ietf-netconf-access-control-07
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 protocol operations and configured subset of all available NETCONF protocol operations and
content. This document defines such an access control model. content. This document defines such an access control model.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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 May 3, 2012. This Internet-Draft will expire on June 25, 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
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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3.2.2. <get> and <get-config> Operations . . . . . . . . . . 14 3.2.2. <get> and <get-config> Operations . . . . . . . . . . 14
3.2.3. <edit-config> Operation . . . . . . . . . . . . . . . 14 3.2.3. <edit-config> Operation . . . . . . . . . . . . . . . 14
3.2.4. <copy-config> Operation . . . . . . . . . . . . . . . 15 3.2.4. <copy-config> Operation . . . . . . . . . . . . . . . 15
3.2.5. <delete-config> Operation . . . . . . . . . . . . . . 16 3.2.5. <delete-config> Operation . . . . . . . . . . . . . . 16
3.2.6. <commit> Operation . . . . . . . . . . . . . . . . . . 16 3.2.6. <commit> Operation . . . . . . . . . . . . . . . . . . 16
3.2.7. <discard-changes> Operation . . . . . . . . . . . . . 16 3.2.7. <discard-changes> Operation . . . . . . . . . . . . . 16
3.2.8. <kill-session> Operation . . . . . . . . . . . . . . . 16 3.2.8. <kill-session> Operation . . . . . . . . . . . . . . . 16
3.3. Model Components . . . . . . . . . . . . . . . . . . . . . 16 3.3. Model Components . . . . . . . . . . . . . . . . . . . . . 16
3.3.1. Users . . . . . . . . . . . . . . . . . . . . . . . . 17 3.3.1. Users . . . . . . . . . . . . . . . . . . . . . . . . 17
3.3.2. Groups . . . . . . . . . . . . . . . . . . . . . . . . 17 3.3.2. Groups . . . . . . . . . . . . . . . . . . . . . . . . 17
3.3.3. Global Enforcement Controls . . . . . . . . . . . . . 17 3.3.3. Emergency Recovery Session . . . . . . . . . . . . . . 17
3.3.3.1. enable-nacm Switch . . . . . . . . . . . . . . . . 17 3.3.4. Global Enforcement Controls . . . . . . . . . . . . . 17
3.3.3.2. read-default Switch . . . . . . . . . . . . . . . 17 3.3.4.1. enable-nacm Switch . . . . . . . . . . . . . . . . 17
3.3.3.3. write-default Switch . . . . . . . . . . . . . . . 18 3.3.4.2. read-default Switch . . . . . . . . . . . . . . . 17
3.3.3.4. exec-default Switch . . . . . . . . . . . . . . . 18 3.3.4.3. write-default Switch . . . . . . . . . . . . . . . 18
3.3.4. Access Control Rules . . . . . . . . . . . . . . . . . 18 3.3.4.4. exec-default Switch . . . . . . . . . . . . . . . 18
3.3.4.5. enable-external-groups Switch . . . . . . . . . . 18
3.3.5. Access Control Rules . . . . . . . . . . . . . . . . . 19
3.4. Access Control Enforcement Procedures . . . . . . . . . . 19 3.4. Access Control Enforcement Procedures . . . . . . . . . . 19
3.4.1. Initial Operation . . . . . . . . . . . . . . . . . . 19 3.4.1. Initial Operation . . . . . . . . . . . . . . . . . . 19
3.4.2. Session Establishment . . . . . . . . . . . . . . . . 19 3.4.2. Session Establishment . . . . . . . . . . . . . . . . 20
3.4.3. "access-denied" Error Handling . . . . . . . . . . . . 20 3.4.3. "access-denied" Error Handling . . . . . . . . . . . . 20
3.4.4. Incoming RPC Message Validation . . . . . . . . . . . 20 3.4.4. Incoming RPC Message Validation . . . . . . . . . . . 20
3.4.5. Data Node Access Validation . . . . . . . . . . . . . 23 3.4.5. Data Node Access Validation . . . . . . . . . . . . . 23
3.4.6. Outgoing <notification> Authorization . . . . . . . . 25 3.4.6. Outgoing <notification> Authorization . . . . . . . . 25
3.5. Data Model Definitions . . . . . . . . . . . . . . . . . . 27 3.5. Data Model Definitions . . . . . . . . . . . . . . . . . . 27
3.5.1. Data Organization . . . . . . . . . . . . . . . . . . 28 3.5.1. Data Organization . . . . . . . . . . . . . . . . . . 27
3.5.2. YANG Module . . . . . . . . . . . . . . . . . . . . . 28 3.5.2. YANG Module . . . . . . . . . . . . . . . . . . . . . 28
3.6. IANA Considerations . . . . . . . . . . . . . . . . . . . 38 3.6. IANA Considerations . . . . . . . . . . . . . . . . . . . 38
3.7. Security Considerations . . . . . . . . . . . . . . . . . 38 3.7. Security Considerations . . . . . . . . . . . . . . . . . 39
3.7.1. NACM Configuration and Monitoring Considerations . . . 38 3.7.1. NACM Configuration and Monitoring Considerations . . . 39
3.7.2. General Configuration Issues . . . . . . . . . . . . . 40 3.7.2. General Configuration Issues . . . . . . . . . . . . . 40
3.7.3. Data Model Design Considerations . . . . . . . . . . . 41 3.7.3. Data Model Design Considerations . . . . . . . . . . . 42
4. References . . . . . . . . . . . . . . . . . . . . . . . . . . 43 4. References . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.1. Normative References . . . . . . . . . . . . . . . . . . . 43 4.1. Normative References . . . . . . . . . . . . . . . . . . . 43
4.2. Informative References . . . . . . . . . . . . . . . . . . 43 4.2. Informative References . . . . . . . . . . . . . . . . . . 43
Appendix A. Usage Examples . . . . . . . . . . . . . . . . . . . 44 Appendix A. Usage Examples . . . . . . . . . . . . . . . . . . . 44
A.1. <groups> Example . . . . . . . . . . . . . . . . . . . . . 44 A.1. <groups> Example . . . . . . . . . . . . . . . . . . . . . 44
A.2. Module Rule Example . . . . . . . . . . . . . . . . . . . 45 A.2. Module Rule Example . . . . . . . . . . . . . . . . . . . 45
A.3. RPC Rule Example . . . . . . . . . . . . . . . . . . . . . 46 A.3. RPC Rule Example . . . . . . . . . . . . . . . . . . . . . 46
A.4. Data Rule Example . . . . . . . . . . . . . . . . . . . . 48 A.4. Data Rule Example . . . . . . . . . . . . . . . . . . . . 48
A.5. Notification Rule Example . . . . . . . . . . . . . . . . 50 A.5. Notification Rule Example . . . . . . . . . . . . . . . . 50
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 52 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 52
B.1. 05-06 . . . . . . . . . . . . . . . . . . . . . . . . . . 52 B.1. 06-07 . . . . . . . . . . . . . . . . . . . . . . . . . . 52
B.2. 04-05 . . . . . . . . . . . . . . . . . . . . . . . . . . 52 B.2. 05-06 . . . . . . . . . . . . . . . . . . . . . . . . . . 52
B.3. 03-04 . . . . . . . . . . . . . . . . . . . . . . . . . . 52 B.3. 04-05 . . . . . . . . . . . . . . . . . . . . . . . . . . 52
B.4. 02-03 . . . . . . . . . . . . . . . . . . . . . . . . . . 53 B.4. 03-04 . . . . . . . . . . . . . . . . . . . . . . . . . . 52
B.5. 01-02 . . . . . . . . . . . . . . . . . . . . . . . . . . 53 B.5. 02-03 . . . . . . . . . . . . . . . . . . . . . . . . . . 53
B.6. 00-01 . . . . . . . . . . . . . . . . . . . . . . . . . . 53 B.6. 01-02 . . . . . . . . . . . . . . . . . . . . . . . . . . 53
B.7. 00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 B.7. 00-01 . . . . . . . . . . . . . . . . . . . . . . . . . . 53
B.8. 00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 54 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 54
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 protocol operations and content that each user is restrict the protocol operations and content that each user is
authorized to access. 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 administrator selected portions of the available NETCONF access to administrator selected portions of the available NETCONF
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standard or proprietary, was used to access the datastore. standard or proprietary, was used to access the datastore.
2.5. Users and Groups 2.5. Users and Groups
It is necessary that access control rules for a single user or a It is necessary that access control rules for a single user or a
configurable group of users can be configured. configurable group of users can be configured.
The ACM needs to support the concept of administrative groups, to The ACM needs to support the concept of administrative groups, to
support the well-established distinction between a root account and support the well-established distinction between a root account and
other types of less-privileged conceptual user accounts. These other types of less-privileged conceptual user accounts. These
groups needs to be configurable by the administrator. groups need to be configurable by the administrator.
It is necessary that the user-to-group mapping can be delegated 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, the underlying NETCONF transport needs to be able to report a time, the underlying NETCONF transport needs to be able to report a
set of group names associated with the user to the server. set of group names associated with the user to the server. It is
necessary that the administrator can disable the usage of these group
names within the ACM.
2.6. Maintenance 2.6. Maintenance
It ought to 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 access control rules. model enforcement procedures without deleting any access control
rules.
2.7. Configuration Capabilities 2.7. Configuration Capabilities
Suitable configuration and monitoring mechanisms are needed to allow Suitable configuration and monitoring mechanisms are needed to allow
an administrator 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> protocol standard data model, suitable for use with the <edit-config> protocol
operation needs to be available for this purpose. operation needs to be available for this purpose.
Access control rules to restrict access operations on specific Access control rules to restrict access operations on specific
subtrees within the configuration datastore needs to be supported. subtrees within the configuration datastore need to be supported.
2.8. Identifying Security-Sensitive Content 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 protocol operations in security-sensitive content. This applies to protocol operations in
NETCONF, 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
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o Support for YANG security tagging (e.g., "nacm:default-deny-write" o Support for YANG security tagging (e.g., "nacm:default-deny-write"
statement) allows default security modes to automatically exclude statement) allows default security modes to automatically exclude
sensitive 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 access control enforcement procedures can be disabled during
operational problems. operation, without deleting any access control rules, in order to
debug 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 [RFC6241] protocol is used for all management purposes The NETCONF [RFC6241] protocol is used for all management purposes
within this document. It is expected that the mandatory transport within this document.
mapping NETCONF Over SSH [RFC6242] is also supported by the server,
and that the server has access to the user name associated with each
session.
The YANG Data Modeling Language [RFC6020] is used to define the 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 conceptual message flow model, The following diagram shows the conceptual message flow model,
including the points at which access control is applied, during including the points at which access control is applied, during
NETCONF message processing. NETCONF message processing.
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3.3.1. Users 3.3.1. Users
A "user" is the conceptual entity that is associated with the access A "user" is the conceptual entity that is associated with the access
permissions granted to a particular session. A user is identified by permissions granted to a particular session. A user is identified by
a string which is unique within the server. a string which is unique within the server.
As described in [RFC6241], the user name string is derived from the As described in [RFC6241], the user name string is derived from the
transport layer during session establishment. If the transport layer transport layer during session establishment. If the transport layer
cannot authenticate the user, the session is terminated. 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 3.3.2. Groups
Access to a specific NETCONF protocol operation is granted to a Access to a specific NETCONF protocol operation is granted to a
session, associated with a group, not a user. session, associated with a group, not a user.
A group is identified by its name. All group names are unique within A group is identified by its name. All group names are unique within
the server. the server.
A group member is identified by a user name string. A group member is identified by a user name string.
The same user can be a member of multiple groups. The same user can be a member of multiple groups.
3.3.3. Global Enforcement Controls 3.3.3. Emergency Recovery Session
There are four global controls that are used to help control how 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.
3.3.4. Global Enforcement Controls
There are five global controls that are used to help control how
access control is enforced. access control is enforced.
3.3.3.1. enable-nacm Switch 3.3.4.1. 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 requests are checked against the access control "true", then all requests are checked against the access control
rules, and only permitted if configured to allow the specific access rules, and only permitted if configured to allow the specific access
request. When this global switch is set to "false", then all access request. When this global switch is set to "false", then all access
requested are permitted. requested are permitted.
3.3.3.2. read-default Switch 3.3.4.2. 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.
3.3.3.3. write-default Switch 3.3.4.3. 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.
3.3.3.4. exec-default Switch 3.3.4.4. 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.
3.3.4. Access Control Rules 3.3.4.5. enable-external-groups Switch
When this global switch is set to "true", the group names reported by
the NETCONF transport layer for a session are used together with the
locally configured group names, to determine the access control rules
for the session.
When this switch is set to "false", the group names reported by the
NETCONF transport layer are ignored by NACM.
3.3.5. 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 YANG module rule: Controls access for definitions in a specific YANG
module, 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 YANG 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
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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.
3.4.3. "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 access operation on operation or a request to perform a particular access operation on
the configuration datastore. the configuration datastore.
A server MUST NOT include any sensitive information in any <error- A server MUST NOT include any information the client is not allowed
info> elements within the <rpc-error> response. to read in any <error-info> elements within the <rpc-error> response.
3.4.4. 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 |
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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>
protocol 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. If the "enable-external-groups" leaf is "true", add to
transport layer. these groups the set of groups provided by the 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 the order they appear in the 6. Process all rule-list entries, in the order they appear in the
configuration. If a rule-list's "group" leaf-list does not configuration. If a rule-list's "group" leaf-list does not
match any of the user's groups, proceed to the next rule-list match any of the user's groups, proceed to the next rule-list
entry. 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 access operation is until a rule that matches the requested access operation is
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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 access 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 access 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. If the the "enable-external-groups" leaf is "true",
transport layer. add to these groups the set of groups provided by the 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 the order they appear in the 5. Process all rule-list entries, in the order they appear in the
configuration. If a rule-list's "group" leaf-list does not configuration. If a rule-list's "group" leaf-list does not
match any of the user's groups, proceed to the next rule-list match any of the user's groups, proceed to the next rule-list
entry. 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 access operation is until a rule that matches the requested access operation is
skipping to change at page 27, line 7 skipping to change at page 27, line 7
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 [RFC5277], then the <notificationComplete> event type [RFC5277], then the
notification is 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. If the "enable-external-groups" leaf is "true", add to
transport layer. these groups the set of groups provided by the 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 the order they appear in the 6. Process all rule-list entries, in the order they appear in the
configuration. If a rule-list's "group" leaf-list does not configuration. If a rule-list's "group" leaf-list does not
match any of the user's groups, proceed to the next rule-list match any of the user's groups, proceed to the next rule-list
entry. 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 access operation is until a rule that matches the requested access operation is
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advertised in the server capabilities, and the "notification" advertised in the server capabilities, and the "notification"
statement contains a "nacm:default-deny-all" 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.
3.5. Data Model Definitions 3.5. Data Model Definitions
This section defines the semantics of the conceptual data structures
found in the data model in Section 3.5.
3.5.1. Data Organization 3.5.1. Data Organization
The following diagram highlights the contents and structure of the The following diagram highlights the contents and structure of the
NACM YANG module. NACM YANG module.
+--rw nacm +--rw nacm
+--rw enable-nacm? boolean +--rw enable-nacm? boolean
+--rw read-default? action-type +--rw read-default? action-type
+--rw write-default? action-type +--rw write-default? action-type
+--rw exec-default? action-type +--rw exec-default? action-type
+--rw enable-external-groups? boolean
+--ro denied-operations yang:zero-based-counter32 +--ro denied-operations yang:zero-based-counter32
+--ro denied-data-writes yang:zero-based-counter32 +--ro denied-data-writes yang:zero-based-counter32
+--ro denied-notifications yang:zero-based-counter32 +--ro denied-notifications yang:zero-based-counter32
+--rw groups +--rw groups
| +--rw group [name] | +--rw group [name]
| +--rw name group-name-type | +--rw name group-name-type
| +--rw user-name* user-name-type | +--rw user-name* user-name-type
+--rw rule-list [name] +--rw rule-list [name]
+--rw name string +--rw name string
+--rw group* union +--rw group* union
skipping to change at page 28, line 47 skipping to change at page 28, line 43
+--rw comment? string +--rw comment? string
3.5.2. 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 // RFC Ed.: please update the date to the date of publication
<CODE BEGINS> file="ietf-netconf-acm@2011-10-31.yang" <CODE BEGINS> file="ietf-netconf-acm@2011-12-23.yang"
module ietf-netconf-acm { module 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";
import ietf-yang-types { import ietf-yang-types {
prefix yang; prefix yang;
} }
organization organization
"IETF NETCONF (Network Configuration) Working Group"; "IETF NETCONF (Network Configuration) Working Group";
contact contact
skipping to change at page 29, line 24 skipping to change at page 29, line 21
"WG Web: <http://tools.ietf.org/wg/netconf/> "WG Web: <http://tools.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org> WG List: <mailto:netconf@ietf.org>
WG Chair: Mehmet Ersue WG Chair: Mehmet Ersue
<mailto:mehmet.ersue@nsn.com> <mailto:mehmet.ersue@nsn.com>
WG Chair: Bert Wijnen WG Chair: Bert Wijnen
<mailto:bertietf@bwijnen.net> <mailto:bertietf@bwijnen.net>
Editor: Andy Bierman Editor: Andy Bierman
<mailto:andy.bierman@brocade.com> <mailto:andy@netconfcentral.org>
Editor: Martin Bjorklund Editor: Martin Bjorklund
<mailto:mbj@tail-f.com>"; <mailto:mbj@tail-f.com>";
description description
"NETCONF Access Control Model. "NETCONF Access Control Model.
Copyright (c) 2011 IETF Trust and the persons identified as Copyright (c) 2011 IETF Trust and the persons identified as
authors of the code. All rights reserved. authors of the code. All rights reserved.
skipping to change at page 29, line 48 skipping to change at page 29, line 45
License set forth in Section 4.c of the IETF Trust's License set forth in Section 4.c of the IETF Trust's
Legal Provisions Relating to IETF Documents Legal Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info). (http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices."; the RFC itself for full legal notices.";
// RFC Ed.: replace XXXX with actual RFC number and // RFC Ed.: replace XXXX with actual RFC number and
// remove this note // remove this note
// RFC Ed.: remove this note // RFC Ed.: remove this note
// Note: extracted from draft-ietf-netconf-access-control-06.txt // Note: extracted from draft-ietf-netconf-access-control-07.txt
// RFC Ed.: please update the date to the date of publication // RFC Ed.: please update the date to the date of publication
revision "2011-10-31" { revision "2011-12-23" {
description description
"Initial version"; "Initial version";
reference reference
"RFC XXXX: Network Configuration Protocol "RFC XXXX: Network Configuration Protocol
Access Control Model"; Access Control Model";
} }
/* /*
* Extension statements * Extension statements
*/ */
extension default-deny-write { extension default-deny-write {
skipping to change at page 33, line 10 skipping to change at page 33, line 8
'USER', which contains the name of user of the current 'USER', which contains the name of user of the current
session. session.
o The function library is the core function library, but o The function library is the core function library, but
note that due to the syntax restrictions of an note that due to the syntax restrictions of an
instance-identifier, no functions are allowed. instance-identifier, no functions are allowed.
o The context node is the root node in the data tree."; o The context node is the root node in the data tree.";
} }
/*
* Data definition statements
*/
container nacm { container nacm {
nacm:default-deny-all; nacm:default-deny-all;
description description
"Parameters for NETCONF Access Control Model."; "Parameters for NETCONF Access Control Model.";
leaf enable-nacm { leaf enable-nacm {
type boolean; type boolean;
default true; default true;
description description
skipping to change at page 34, line 4 skipping to change at page 34, line 4
particular write request."; particular write request.";
} }
leaf exec-default { leaf exec-default {
type action-type; type action-type;
default "permit"; default "permit";
description description
"Controls whether exec access is granted if no appropriate "Controls whether exec access is granted if no appropriate
rule is found for a particular protocol operation request."; rule is found for a particular protocol operation request.";
} }
leaf enable-external-groups {
type boolean;
default true;
description
"Controls whether the server uses the groups reported by the
NETCONF transport layer when it assigns the user to a set of
NACM groups. If this leaf has the value 'false', any group
names reported by the transport layer are ignored by the
server.";
}
leaf denied-operations { leaf denied-operations {
type yang:zero-based-counter32; type yang:zero-based-counter32;
config false; config false;
mandatory true; mandatory true;
description description
"Number of times a protocol operation request was denied "Number of times a protocol operation request was denied
since the server last restarted."; since the server last restarted.";
} }
leaf denied-data-writes { leaf denied-data-writes {
skipping to change at page 34, line 40 skipping to change at page 35, line 4
the event type was denied, since the server the event type was denied, since the server
last restarted."; last restarted.";
} }
container groups { container groups {
description description
"NETCONF Access Control Groups."; "NETCONF Access Control Groups.";
list group { list group {
key name; key name;
description description
"One NACM Group Entry."; "One NACM Group Entry. This list will only contain
configured entries, not any entries learned from
any transport protocols.";
leaf name { leaf name {
type group-name-type; type group-name-type;
description description
"Group name associated with this entry."; "Group name associated with this entry.";
} }
leaf-list user-name { leaf-list user-name {
type user-name-type; type user-name-type;
description description
skipping to change at page 39, line 6 skipping to change at page 39, line 22
when configuring a NETCONF server with NACM. when configuring a NETCONF server with NACM.
3.7.1. NACM Configuration and Monitoring Considerations 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.
By default, NACM enforcement is enabled. By default, "read" access By default, NACM enforcement is enabled. By default, "read" access
to all datastore contents enabled, (unless "nacm:default-deny-all" is to all datastore contents is enabled, (unless "nacm:default-deny-all"
specified for the data definition) and "exec" access is enabled for is specified for the data definition) and "exec" access is enabled
safe protocol operations. An administrator needs to ensure that NACM for safe protocol operations. An administrator needs to ensure that
is enabled, and also decide if the default access parameters are set NACM is enabled, and also decide if the default access parameters are
appropriately. Make sure the following data nodes are properly set appropriately. Make sure the following data nodes are properly
configured: configured:
o /nacm/enable-nacm (default "true") o /nacm/enable-nacm (default "true")
o /nacm/read-default (default "permit") o /nacm/read-default (default "permit")
o /nacm/write-default (default "deny") o /nacm/write-default (default "deny")
o /nacm/exec-default (default "permit") o /nacm/exec-default (default "permit")
skipping to change at page 39, line 48 skipping to change at page 40, line 16
representing access control rules (/nacm/rule-list and /nacm/ representing access control rules (/nacm/rule-list and /nacm/
rule-list/rule) are ordered by the client. The server will evaluate rule-list/rule) are ordered by the client. The server will evaluate
the access control rules according to their relative conceptual order the access control rules according to their relative conceptual order
within the running datastore configuration. within the running datastore configuration.
Note that the /nacm/groups data structure contains the administrative Note that the /nacm/groups data structure contains the administrative
group names used by the server. These group names may be configured group names used by the server. These group names may be configured
locally and/or provided through an external protocol, such as RADIUS locally and/or provided through an external protocol, such as RADIUS
[RFC2865] [RFC5607]. [RFC2865] [RFC5607].
An administrator needs to be aware of the security properties of any
external protocol used by the NETCONF transport layer to determine
group names. For example, if this protocol does not protect against
man-in-the-middle attacks, an attacker might be able to inject group
names that are configured in NACM, so that a user gets more
permissions than it should. In such cases, the administrator may
wish to disable the usage of such group names, by setting /nacm/
enable-external-groups to "false".
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 /nacm/enable-nacm o /nacm/enable-nacm
o /nacm/read-default o /nacm/read-default
o /nacm/write-default o /nacm/write-default
o /nacm/exec-default o /nacm/exec-default
o /nacm/enable-external-groups
o /nacm/groups o /nacm/groups
o /nacm/rule-list o /nacm/rule-list
3.7.2. General Configuration Issues 3.7.2. General Configuration Issues
There is a risk that invocation of non-standard protocol operations There is a risk that invocation of non-standard protocol operations
will have undocumented side effects. An administrator needs to will have undocumented side effects. An administrator needs to
construct access control rules such that the configuration datastore construct access control rules such that the configuration datastore
is protected from such side effects. is protected from such side effects.
skipping to change at page 41, line 48 skipping to change at page 42, line 26
o <partial-lock> o <partial-lock>
o <partial-unlock> o <partial-unlock>
3.7.3. Data Model Design Considerations 3.7.3. Data Model Design Considerations
Designers need to clearly identify any sensitive data, notifications, Designers need to clearly identify any sensitive data, notifications,
or protocol operations defined within a YANG module. For such or protocol operations defined within a YANG module. For such
definitions, a "nacm:default-deny-write" or "nacm:default-deny-all" definitions, a "nacm:default-deny-write" or "nacm:default-deny-all"
statement SHOULD be present, in addition to a clear description of statement ought to be present, in addition to a clear description of
the security risks. the security risks.
Protocol operations need to be properly documented by the data model Protocol operations need to be properly documented by the data model
designer, so it is clear to administrators what data nodes (if any) designer, so it is clear to administrators what data nodes (if any)
are affected by the protocol operation, and what information (if any) are affected by the protocol operation, and what information (if any)
is returned in the <rpc-reply> message. is returned in the <rpc-reply> message.
Data models ought to be designed so that different access levels for Data models ought to be designed so that different access levels for
input parameters to protocol operations is not required. Use of input parameters to protocol operations is not required. Use of
generic protocol operations should be avoided, and separate protocol generic protocol operations should be avoided, and separate protocol
skipping to change at page 43, line 29 skipping to change at page 43, line 29
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.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A. [RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
Bierman, "Network Configuration Protocol (NETCONF)", Bierman, "Network Configuration Protocol (NETCONF)",
RFC 6241, June 2011. RFC 6241, June 2011.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, June 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 52, line 9 skipping to change at page 52, line 9
This example shows 1 notification rule: This example shows 1 notification rule:
deny-config-change: This rule prevents the "limited" or "guest" deny-config-change: This rule prevents the "limited" or "guest"
groups from 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. 05-06 B.1. 06-07
Added the leaf "enable-external-groups".
Removed dependency to RFC 6242.
Some editorial changes after IESG review.
B.2. 05-06
Added clarification to Security Considerations section about Added clarification to Security Considerations section about
ordered-by user lists (/nacm/rule-list and /nacm/rule-list/rule). ordered-by user lists (/nacm/rule-list and /nacm/rule-list/rule).
Added clarifications to security considerations wrt/ user names and Added clarifications to security considerations wrt/ user names and
NETCONF capability changes. NETCONF capability changes.
Fixed typos found in review. Fixed typos found in review.
B.2. 04-05 B.3. 04-05
Updated Security Considerations section. Updated Security Considerations section.
Changed term 'operator' to 'administrator'. Changed term 'operator' to 'administrator'.
Used the terms "access operation" and "protocol operation" Used the terms "access operation" and "protocol operation"
consistently. consistently.
Moved some normative text from section 2 to section 3. Also made it Moved some normative text from section 2 to section 3. Also made it
more clear that section 2 is not a requirements section, but more clear that section 2 is not a requirements section, but
documentation of the objectives for NACM. documentation of the objectives for NACM.
Renamed "nacm:secure" to "nacm:default-deny-write", and "nacm:very- Renamed "nacm:secure" to "nacm:default-deny-write", and "nacm:very-
secure" to "nacm:default-deny-all". Explained that "nacm:default- secure" to "nacm:default-deny-all". Explained that "nacm:default-
deny-write" is ignored on rpc statements. deny-write" is ignored on rpc statements.
Described that <kill-session> and <delete-config> behave as if Described that <kill-session> and <delete-config> behave as if
specified with "nacm:default-deny-all". specified with "nacm:default-deny-all".
B.3. 03-04 B.4. 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.4. 02-03 B.5. 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.5. 01-02 B.6. 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.6. 00-01 B.7. 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.7. 00 B.8. 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@netconfcentral.org
Martin Bjorklund Martin Bjorklund
Tail-f Systems Tail-f Systems
Email: mbj@tail-f.com Email: mbj@tail-f.com
 End of changes. 53 change blocks. 
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