Internet DRAFT - draft-toutain-lpwan-access-control
draft-toutain-lpwan-access-control
lpwan Working Group A. Minaburo
Internet-Draft Acklio
Intended status: Standards Track L. Toutain
Expires: 24 August 2023 I. Martinez
Institut MINES TELECOM; IMT Atlantique
20 February 2023
SCHC Rule Access Control
draft-toutain-lpwan-access-control-01
Abstract
The framework for SCHC defines an abstract view of the rules,
formalized with through a YANG Data Model. In its original
description rules are static and share by 2 entities. The use of
YANG authorizes rules to be uploaded or modified in a SCHC instance
and leads to some possible attacks, if the changes are not
controlled. This document summarizes some possible attacks and
define augmentation to the existing Data Mode, to restrict the
changes in the rule.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 24 August 2023.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
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and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Attack scenario . . . . . . . . . . . . . . . . . . . . . . . 3
3. YANG Access Control . . . . . . . . . . . . . . . . . . . . . 3
4. YANG Data Model . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. leaf ac-modify-set-of-rules . . . . . . . . . . . . . . . 4
4.2. leaf ac-modify-compression-rule . . . . . . . . . . . . . 4
4.3. leaf ac-modify-field . . . . . . . . . . . . . . . . . . 4
5. Normative References . . . . . . . . . . . . . . . . . . . . 4
Appendix A. YANG Data Model . . . . . . . . . . . . . . . . . . 5
Appendix B. Security Considerations . . . . . . . . . . . . . . 8
Appendix C. IANA Considerations . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
Figure Figure 1 focuses on the management part of the SCHC
architecture.
.......................................................
. ................................. .
v ^ v ^
(--------) +----------+ +-------+ +-------+-------+
( Set of )<--->|coreconf |<=======|Access |<===| other end |<===
( Rules ) |request | |Control| | authentication|
(--------) |processing| +-------+ +---------------+
+----------+
Figure 1: Overview of management architecture.
When a management request arrives on a SCHC instance, the identity of
the requester must be checked:
* this can be implicit, for instance a LPWAN device receives it from
the SCHC core instance. Authentication is done at Layer 2.
* this can be a L2 address. In a LoRaWAN network, the DevEUI allows
the SCHC core instance to identify the device.
* IP addresses may also be used as well as cryptographic keys.
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The identification of the requester allows to retrieve the associated
Set of Rules. This rules are enriched with access control
information that will be defined in this document. If the Set of
Rules do not contains any access control information, the management
is not allowed to modify the Rules content.
2. Attack scenario
A LWM2M device, under control of an attacker, sends some management
messages to modify the SCHC rules in core in order to direct the
traffic to another application. This can be either to participate to
a DDoS attack or to send sensible information to another application.
SCHC rules are defined for a specific traffic. An attacker changes
en element (for instance, the dev UDP port number) and therefore no
rule matches the traffic, the link may be saturated by no-compressed
messages.
3. YANG Access Control
YANG language allows to specify read only or read write nodes. NACM
[RFC8341] extends this by allowing users or group od users to perform
specific actions.
This granularity do not fit this the rule model. For instance, the
goal is not to allow all the field-id leaves to be modified. The
objective is to allow a specific rule entry to be changed and
therefore some of the leaves to be modified. For instance an entry
with field-id containing Uri-path may have his target-value modified,
as in the same rule, the entry regarding the app-prefix should not be
changed.
The SCHC access control augments the YANG module defined in
[I-D.ietf-lpwan-schc-yang-data-model] to allow a remote entity to
manipulate the rules. Several levels are defined.
* in the set of rules, it authorizes or not a new rule to be added .
* in a compression rule, it allows to add or remove field
descriptions.
* in a compression rule, it allows to modify some elements of the
rule, such as the target-value, the matching-operator or/and the
comp-decomp-action and associated values.
* in a fragmentation rule, it allows to modify some parameters.
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4. YANG Data Model
The YANG DM proposed in Appendix A extends the SCHC YANG Data Model
introduced in [I-D.ietf-lpwan-schc-yang-data-model]. It adds read-
only leaves containing the access rights. If these leaves are not
presents, the information cannot be modified.
4.1. leaf ac-modify-set-of-rules
This leaf controls modifications applied to a set of rules. They are
specified with the rule-access-right enumeration:
* no-change (0): rules cannot be modified in the Set of Rules. This
is the equivalent of having no access control elements in the set
of rules.
* modify-existing-element (1): an existing rule may be modified.
* add-remove-element (2): a rule can be added or deleted from the
Set of Rules or an existing rule can be modified.
4.2. leaf ac-modify-compression-rule
This leaf allows to modify a compression element. To be active, leaf
ac-modify-set-of-rules MUST be set to modify-existing-element or add-
remove-element. This leaf uses the same enumeration as add-remove-
element:
* no-change (0): The rule cannot be modified.
* modify-existing-element (1): an existing Field Description may be
modified.
* add-remove-element (2): a Field Description can be added or
deleted from the Rule or an existing rule can be modified.
4.3. leaf ac-modify-field
This leaf allows to modify a Field Description in a compression rule.
To be active, leaves ac-modify-set-of-rules and ac-modify-
compression-rule MUST be set to modify-existing-element or add-
remove-element and ac-modifiy-compression-rule and leaf
5. Normative References
[I-D.ietf-lpwan-schc-yang-data-model]
Minaburo, A. and L. Toutain, "Data Model for Static
Context Header Compression (SCHC)", Work in Progress,
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Internet-Draft, draft-ietf-lpwan-schc-yang-data-model-21,
9 October 2022, <https://www.ietf.org/archive/id/draft-
ietf-lpwan-schc-yang-data-model-21.txt>.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
<https://www.rfc-editor.org/info/rfc8341>.
[RFC8824] Minaburo, A., Toutain, L., and R. Andreasen, "Static
Context Header Compression (SCHC) for the Constrained
Application Protocol (CoAP)", RFC 8824,
DOI 10.17487/RFC8824, June 2021,
<https://www.rfc-editor.org/info/rfc8824>.
Appendix A. YANG Data Model
<CODE BEGINS> file "ietf-schc-access-control@2023-02-14.yang"
module ietf-schc-access-control {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-schc-access-control";
prefix schc-ac;
import ietf-schc {
prefix schc;
}
organization
"IETF IPv6 over Low Power Wide-Area Networks (lpwan) working group";
contact
"WG Web: <https://datatracker.ietf.org/wg/lpwan/about/>
WG List: <mailto:lp-wan@ietf.org>
Editor: Juan-Carlos Zuniga
<mailto:juancarlos.zuniga@sigfox.com>";
description
"
Copyright (c) 2021 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject to
the license terms contained in, the Simplified BSD License set
forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
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for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
'MAY', and 'OPTIONAL' in this document are to be interpreted as
described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
they appear in all capitals, as shown here.
*************************************************************************
This module extends the ietf-schc module to include the compound-ack
behavior for Ack On Error as defined in RFC YYYY.
It introduces a new leaf for Ack on Error defining the format of the
SCHC Ack and add the possibility to send several bitmaps in a single
answer.";
revision 2023-02-14 {
description
"Initial version for RFC YYYY ";
reference
"RFC YYYY: Compound Ack";
}
typedef rule-access-right {
type enumeration {
enum no-changes {
value 0;
description
"No change are allowed.";
}
enum modify-existing-element {
value 1;
description
"can modify content inside an element.";
}
enum add-remove-element {
value 2;
description
"Allows to add or remove or modify an element.";
}
}
}
typedef field-access-right {
type enumeration {
enum no-change {
value 0;
description
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"Reserved slot number.";
}
enum change-tv {
value 1;
description
"Reserved slot number.";
}
enum change-mo-cda-tv {
value 2;
description
"Reserved slot number.";
}
}
}
augment "/schc:schc/schc:rule" {
leaf ac-modify-set-of-rules {
config false;
type rule-access-right;
}
}
augment "/schc:schc/schc:rule/schc:nature/schc:compression" {
leaf ac-modify-compression-rule {
config false;
type rule-access-right;
}
}
augment "/schc:schc/schc:rule/schc:nature/schc:compression/schc:entry" {
leaf ac-modify-field {
config false;
type field-access-right;
}
}
augment "/schc:schc/schc:rule/schc:nature/schc:fragmentation" {
leaf ac-modify-timers {
config false;
type boolean;
}
}
}
<CODE ENDS>
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Appendix B. Security Considerations
TBD
Appendix C. IANA Considerations
TBD
Authors' Addresses
Ana Minaburo
Acklio
1137A avenue des Champs Blancs
35510 Cesson-Sevigne Cedex
France
Email: ana@ackl.io
Laurent Toutain
Institut MINES TELECOM; IMT Atlantique
2 rue de la Chataigneraie
CS 17607
35576 Cesson-Sevigne Cedex
France
Email: Laurent.Toutain@imt-atlantique.fr
Ivan Martinez
Institut MINES TELECOM; IMT Atlantique
2 rue de la Chataigneraie
CS 17607
35576 Cesson-Sevigne Cedex
France
Email: ivan-marino.martinez-bolivar@imt-atlantique.fr
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