Labeled IPsec Traffic Selector support for IKEv2
draft-ietf-ipsecme-labeled-ipsec-06
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Paul Wouters
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Sahana Prasad
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Last updated |
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2021-10-25
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Aug 2020 - The security labels ...
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Tero Kivinen
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Tero Kivinen <kivinen@iki.fi>
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Network P. Wouters
Internet-Draft Aiven
Updates: 7296 (if approved) S. Prasad
Intended status: Standards Track Red Hat
Expires: 28 April 2022 25 October 2021
Labeled IPsec Traffic Selector support for IKEv2
draft-ietf-ipsecme-labeled-ipsec-06
Abstract
This document defines a new Traffic Selector (TS) Type for Internet
Key Exchange version 2 to add support for negotiating Mandatory
Access Control (MAC) security labels as a traffic selector of the
Security Policy Database (SPD). Security Labels for IPsec are also
known as "Labeled IPsec". The new TS type is TS_SECLABEL, which
consists of a variable length opaque field specifying the security
label. This document updates the IKEv2 TS negotiation specified in
RFC 7296 Section 2.9.
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
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 28 April 2022.
Copyright Notice
Copyright (c) 2021 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
and restrictions with respect to this document. Code Components
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extracted from this document must include Simplified BSD License text
as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
1.2. Traffic Selector clarification . . . . . . . . . . . . . 3
1.3. Traffic Selector update . . . . . . . . . . . . . . . . . 4
2. TS_SECLABEL Traffic Selector Type . . . . . . . . . . . . . . 4
2.1. TS_SECLABEL payload format . . . . . . . . . . . . . . . 4
2.2. TS_SECLABEL properties . . . . . . . . . . . . . . . . . 4
3. Traffic Selector negotiation . . . . . . . . . . . . . . . . 5
3.1. Example TS negotiation . . . . . . . . . . . . . . . . . 6
3.2. Considerations for using multiple TS_TYPEs in a TS . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Implementation Status . . . . . . . . . . . . . . . . . . . . 7
6.1. Libreswan . . . . . . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
In computer security, Mandatory Access Control usually refers to
systems in which all subjects and objects are assigned a security
label. A security label is comprised of a set of security
attributes. The security labels along with a system authorization
policy determine access. Rules within the system authorization
policy determine whether the access will be granted based on the
security attributes of the subject and object.
Traditionally, security labels used by Multilevel Systems (MLS) are
comprised of a sensitivity level (or classification) field and a
compartment (or category) field, as defined in [FIPS188] and
[RFC5570]. As MAC systems evolved, other MAC models gained in
popularity. For example, SELinux, a Flux Advanced Security Kernel
(FLASK) implementation, has security labels represented as colon-
separated ASCII strings composed of values for identity, role, and
type. The security labels are often referred to as security
contexts.
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Traffic Selector (TS) payloads specify the selection criteria for
packets that will be forwarded over the newly set up IPsec SA as
enforced by the Security Policy Database (SPD, see [RFC4301]). This
document updates the Traffic Selector negotiation specified in
Section 2.9 of [RFC7296].
This document specifies a new Traffic Selector Type TS_SECLABEL for
IKEv2 that can be used to negotiate security labels as additional
selectors for the Security Policy Database (SPD) to further restrict
the type of traffic allowed to be sent and received over the IPsec
SA.
1.1. Requirements Language
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 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.2. Traffic Selector clarification
The negotiation of Traffic Selectors is specified in Section 2.9 of
[RFC7296] where it defines two TS Types (TS_IPV4_ADDR_RANGE and
TS_IPV6_ADDR_RANGE). The Traffic Selector payload format is
specified in Section 3.13 of [RFC7296]. However, the term Traffic
Selector is used to denote the traffic selector payloads and
individual traffic selectors of that payload. Sometimes the exact
meaning can only be learned from context or if the item is written in
plural ("Traffic Selectors" or "TSs"). This section clarifies these
terms as follows:
A Traffic Selector (no acronym) is one selector for traffic of a
specific Traffic Selector Type (TS_TYPE). For example a Traffic
Selector of TS_TYPE TS_IPV4_ADDR_RANGE for UDP traffic in the IP
network 198.51.100.0/24 covering all ports, is denoted as (17, 0,
198.51.100.0-198.51.100.255)
A Traffic Selector payload (TS) is a set of one or more Traffic
Selectors of the same or different TS_TYPEs, but MUST include at
least one TS_TYPE of TS_IPV4_ADDR_RANGE or TS_IPV6_ADDR_RANGE. For
example, the above Traffic Selector by itself in a TS payload is
denoted as TS((17, 0, 198.51.100.0-198.51.100.255))
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1.3. Traffic Selector update
The negotiation of Traffic Selectors is specified in Section 2.9 of
[RFC7296] and states that the TSi/TSr payloads MUST contain at least
one Traffic Selector type. This document updates the text to mean
that the TSi/TSr payloads MUST contain at least one Traffic Selector
of type TS_IPV4_ADDR_RANGE or TS_IPV6_ADDR_RANGE, as other Traffic
Selector types can be defined that are complimentary to these Traffic
Selector Types and cannot be selected on their own without
TS_IPV4_ADDR_RANGE or TS_IPV6_ADDR_RANGE. The below defined
TS_SECLABEL Traffic Selector Type is an example of this.
2. TS_SECLABEL Traffic Selector Type
This document defines a new TS Type, TS_SECLABEL that contains a
single new opaque Security Label.
2.1. TS_SECLABEL payload format
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+---------------+---------------+-------------------------------+
| TS Type | Reserved | Selector Length |
+---------------+---------------+-------------------------------+
| |
~ Security Label* ~
| |
+---------------------------------------------------------------+
Figure 1: Labeled IPsec Traffic Selector
*Note: All fields other than TS Type and Selector Length depend on
the TS Type. The fields shown is for TS Type TS_SECLABEL, the
selector this document defines.
* TS Type (one octet) - Set to [TBD] for TS_SECLABEL,
* Selector Length (2 octets, unsigned integer) - Specifies the
length of this Traffic Selector substructure including the header.
* Security Label - An opaque byte stream of at least one octet.
2.2. TS_SECLABEL properties
The TS_SECLABEL Traffic Selector Type does not support narrowing or
wildcards. It MUST be used as an exact match value.
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The Security Label contents are opaque to the IKE implementation.
That is, the IKE implementation might not have any knowledge of the
meaning of this selector, other than as a type and opaque value to
pass to the SPD.
A zero length Security Label MUST NOT be used. If a received TS
payload contains a TS_TYPE of TS_SECLABEL with a zero length Security
Label, that specific Traffic Selector MUST be ignored. If no other
Traffic Selector of TS_TYPE TS_SECLABEL can be selected, a
TS_UNACCEPTABLE Error Notify message MUST be returned. A zero length
Security Label MUST NOT be interpreted as a wildcard security label.
If multiple Security Labels are allowed for a given IP protocol,
start and end address/port match, the initiator includes all of the
acceptable TS_SECLABEL's and the responder MUST select one of them.
If the Security Label traffic selector is optional from a
configuration point of view, the initiator will have to choose which
TS payload to attempt first. If it includes the Security Label and
receives a TS_UNACCEPTABLE, it can attempt a new Child SA negotiation
without that Security Label.
A responder that selected a TS with TS_SECLABEL MUST use the Security
Label for all selector operations on the resulting TS. It MUST NOT
select a TS_SECLABEL without using the specified Security Label, even
if it deems the Security Label optional, as the initiator has
indicated (and expects) that Security Label will be set for all
traffic matching the negotiated TS.
3. Traffic Selector negotiation
This document updates the [RFC7296] specification as follows:
Each TS payload (TSi and TSr) MUST contain at least one TS_TYPE of
TS_IPV4_ADDR_RANGE or TS_IPV6_ADDR_RANGE.
Each TS payload (TSi or TSr) MAY contain one or more other TS_TYPEs,
such as TS_SECLABEL.
A responder MUST create each TS response by creating one of more
(narrowed or not) TS_IPV4_ADDR_RANGE or TS_IPV6_ADDR_RANGE entries,
plus one of each further TS_TYPE present in the offered TS by the
initiator. If this is not possible, it MUST return a TS_UNACCEPTABLE
Error Notify payload.
If a specific TS_TYPE (other than TS_IPV4_ADDR_RANGE or
TS_IPV6_ADDR_RANGE which are mandatory) is deemed optional, the
initiator SHOULD first try to negotiate the Child SA with the TS
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payload including the optional TS_TYPE. Upon receiving
TS_UNACCEPTABLE, it SHOULD attempt a new Child SA negotiation using
the same TS but without the optional TS_TYPE.
3.1. Example TS negotiation
An initiator could send:
TSi = ((17,0,192.0.2.0-192.0.2.255),
(0,0,198.51.0-198.51.255),
TS_SECLABEL1, TS_SECLABEL2)
TSr = ((17,0,203.0.113.0-203.0.113.255),
(0,0,203.0.113.0-203.0.113.255),
TS_SECLABEL1, TS_SECLABEL2)
Figure 2: initiator TS payloads example
The responder could answer with the following example:
TSi = ((0,0,198.51.0-198.51.255),
TS_SECLABEL1)
TSr = (((0,0,203.0.113.0-203.0.113.255),
TS_SECLABEL1)
Figure 3: responder TS payloads example
3.2. Considerations for using multiple TS_TYPEs in a TS
It would be unlikely that the traffic for TSi and TSr would have a
different Security Label, but this specification does allow this to
be specified. If the initiator does not support this, and wants to
prevent the responder from picking different labels for the TSi / TSr
payloads, it should attempt a Child SA negotiation with only the
first Security Label first, and upon failure retry a new Child SA
negotiation with only the second Security Label.
If different IP ranges can only use different specific Security
Labels, than these should be negotiated in two different Child SA
negotiations. If in the example above, the initiator only allows
192.0.2.0/24 with TS_SECLABEL1, and 198.51.0/24 with TS_SECLABEL2,
than it MUST NOT combine these two ranges and security labels into
one Child SA negotiation.
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The mechanism of narrowing of Traffic Selectors with
TS_IPV4_ADDR_RANGE and TS_IPV6_ADDR_RANGE does not apply to
TS_SECLABEL as the Security Label itself is not interpreted and
cannot be narrowed. It MUST be matched exactly. Since a rekey MUST
NOT narrow down the Traffic Selectors narrower than the scope
currently in use, the only valid choice of TS_SECLABEL for a rekey is
the identical TS_SECLABEL that is in use by the Child SA being
rekeyed. If the TS_LABEL is missing from the TS during the rekey
negotiation, the negotiation MUST fail with TS_UNACCEPTABLE.
4. Security Considerations
It is assumed that the Security Label can be matched by the IKE
implementation to its own configured value, even if the IKE
implementation itself cannot interpret the Security Label value.
A packet that matches an SPD entry for all components except the
Security Label would be treated as "not matching". If no other SPD
entries match, the (mis-labeled) traffic might end up being
transmitted in the clear. It is presumed that other Mandatory Access
Control methods are in place to prevent mis-labeled traffic from
reaching the IPsec subsystem, or that the IPsec subsystem itself
would install a REJECT/DISCARD rule in the SPD to prevent unlabeled
traffic otherwise matching a labeled security SPD rule from being
transmitted without IPsec protection.
5. IANA Considerations
This document defines two new entries in the IKEv2 Traffic Selector
Types registry:
Value TS Type Reference
----- --------------------------- -----------------
TBD TS_SECLABEL [this document]
Figure 4
6. Implementation Status
[Note to RFC Editor: Please remove this section and the reference to
[RFC6982] before publication.]
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
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here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
Authors are requested to add a note to the RFC Editor at the top of
this section, advising the Editor to remove the entire section before
publication, as well as the reference to [RFC7942].
6.1. Libreswan
Organization: The Libreswan Project
Name: https://lists.libreswan.org/mailman/listinfo/swan-dev/
Description: Implementation has been released as part of libreswan
version 4.4.
Level of maturity: beta
Coverage: Implements the entire draft using SElinux based labels
Licensing: GPLv2
Implementation experience: No interop testing has been done yet.
The code works as proof of concept, but is not yet production
ready when using multiple different labels with on-demand kernel
ACQUIRES.
Contact: Libreswan Development: swan-dev@libreswan.org
7. Acknowledgements
A large part of the introduction text was taken verbatim from
[draft-jml-ipsec-ikev2-security-label] whose authors are J Latten, D.
Quigley and J. Lu. Valery Smyslov provided valuable input regarding
IKEv2 Traffic Selector semantics.
8. References
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8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kivinen, "Internet Key Exchange Protocol Version 2
(IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
2014, <https://www.rfc-editor.org/info/rfc7296>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
8.2. Informative References
[draft-jml-ipsec-ikev2-security-label]
Latten, J., Quigley, D., and J. Lu, "Security Label
Extension to IKE", 28 January 2011.
[FIPS188] NIST, "National Institute of Standards and Technology,
"Standard Security Label for Information Transfer"",
Federal Information Processing Standard (FIPS) Publication
188, September 1994,
<https://csrc.nist.gov/publications/detail/fips/188/
archive/1994-09-06>.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
December 2005, <https://www.rfc-editor.org/info/rfc4301>.
[RFC5570] StJohns, M., Atkinson, R., and G. Thomas, "Common
Architecture Label IPv6 Security Option (CALIPSO)",
RFC 5570, DOI 10.17487/RFC5570, July 2009,
<https://www.rfc-editor.org/info/rfc5570>.
[RFC6982] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", RFC 6982,
DOI 10.17487/RFC6982, July 2013,
<https://www.rfc-editor.org/info/rfc6982>.
[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>.
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Authors' Addresses
Paul Wouters
Aiven
Email: paul.wouters@aiven.io
Sahana Prasad
Red Hat
Email: sahana@redhat.com
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