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Wouters 3 Internet-Draft Aiven 4 Updates: 7296 (if approved) S. Prasad 5 Intended status: Standards Track Red Hat 6 Expires: 28 April 2022 25 October 2021 8 Labeled IPsec Traffic Selector support for IKEv2 9 draft-ietf-ipsecme-labeled-ipsec-06 11 Abstract 13 This document defines a new Traffic Selector (TS) Type for Internet 14 Key Exchange version 2 to add support for negotiating Mandatory 15 Access Control (MAC) security labels as a traffic selector of the 16 Security Policy Database (SPD). Security Labels for IPsec are also 17 known as "Labeled IPsec". The new TS type is TS_SECLABEL, which 18 consists of a variable length opaque field specifying the security 19 label. This document updates the IKEv2 TS negotiation specified in 20 RFC 7296 Section 2.9. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at https://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on 28 April 2022. 39 Copyright Notice 41 Copyright (c) 2021 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 46 license-info) in effect on the date of publication of this document. 47 Please review these documents carefully, as they describe your rights 48 and restrictions with respect to this document. Code Components 49 extracted from this document must include Simplified BSD License text 50 as described in Section 4.e of the Trust Legal Provisions and are 51 provided without warranty as described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 57 1.2. Traffic Selector clarification . . . . . . . . . . . . . 3 58 1.3. Traffic Selector update . . . . . . . . . . . . . . . . . 4 59 2. TS_SECLABEL Traffic Selector Type . . . . . . . . . . . . . . 4 60 2.1. TS_SECLABEL payload format . . . . . . . . . . . . . . . 4 61 2.2. TS_SECLABEL properties . . . . . . . . . . . . . . . . . 4 62 3. Traffic Selector negotiation . . . . . . . . . . . . . . . . 5 63 3.1. Example TS negotiation . . . . . . . . . . . . . . . . . 6 64 3.2. Considerations for using multiple TS_TYPEs in a TS . . . 6 65 4. Security Considerations . . . . . . . . . . . . . . . . . . . 7 66 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 67 6. Implementation Status . . . . . . . . . . . . . . . . . . . . 7 68 6.1. Libreswan . . . . . . . . . . . . . . . . . . . . . . . . 8 69 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 70 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 71 8.1. Normative References . . . . . . . . . . . . . . . . . . 9 72 8.2. Informative References . . . . . . . . . . . . . . . . . 9 73 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 75 1. Introduction 77 In computer security, Mandatory Access Control usually refers to 78 systems in which all subjects and objects are assigned a security 79 label. A security label is comprised of a set of security 80 attributes. The security labels along with a system authorization 81 policy determine access. Rules within the system authorization 82 policy determine whether the access will be granted based on the 83 security attributes of the subject and object. 85 Traditionally, security labels used by Multilevel Systems (MLS) are 86 comprised of a sensitivity level (or classification) field and a 87 compartment (or category) field, as defined in [FIPS188] and 88 [RFC5570]. As MAC systems evolved, other MAC models gained in 89 popularity. For example, SELinux, a Flux Advanced Security Kernel 90 (FLASK) implementation, has security labels represented as colon- 91 separated ASCII strings composed of values for identity, role, and 92 type. The security labels are often referred to as security 93 contexts. 95 Traffic Selector (TS) payloads specify the selection criteria for 96 packets that will be forwarded over the newly set up IPsec SA as 97 enforced by the Security Policy Database (SPD, see [RFC4301]). This 98 document updates the Traffic Selector negotiation specified in 99 Section 2.9 of [RFC7296]. 101 This document specifies a new Traffic Selector Type TS_SECLABEL for 102 IKEv2 that can be used to negotiate security labels as additional 103 selectors for the Security Policy Database (SPD) to further restrict 104 the type of traffic allowed to be sent and received over the IPsec 105 SA. 107 1.1. Requirements Language 109 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 110 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 111 "OPTIONAL" in this document are to be interpreted as described in BCP 112 14 [RFC2119] [RFC8174] when, and only when, they appear in all 113 capitals, as shown here. 115 1.2. Traffic Selector clarification 117 The negotiation of Traffic Selectors is specified in Section 2.9 of 118 [RFC7296] where it defines two TS Types (TS_IPV4_ADDR_RANGE and 119 TS_IPV6_ADDR_RANGE). The Traffic Selector payload format is 120 specified in Section 3.13 of [RFC7296]. However, the term Traffic 121 Selector is used to denote the traffic selector payloads and 122 individual traffic selectors of that payload. Sometimes the exact 123 meaning can only be learned from context or if the item is written in 124 plural ("Traffic Selectors" or "TSs"). This section clarifies these 125 terms as follows: 127 A Traffic Selector (no acronym) is one selector for traffic of a 128 specific Traffic Selector Type (TS_TYPE). For example a Traffic 129 Selector of TS_TYPE TS_IPV4_ADDR_RANGE for UDP traffic in the IP 130 network 198.51.100.0/24 covering all ports, is denoted as (17, 0, 131 198.51.100.0-198.51.100.255) 133 A Traffic Selector payload (TS) is a set of one or more Traffic 134 Selectors of the same or different TS_TYPEs, but MUST include at 135 least one TS_TYPE of TS_IPV4_ADDR_RANGE or TS_IPV6_ADDR_RANGE. For 136 example, the above Traffic Selector by itself in a TS payload is 137 denoted as TS((17, 0, 198.51.100.0-198.51.100.255)) 139 1.3. Traffic Selector update 141 The negotiation of Traffic Selectors is specified in Section 2.9 of 142 [RFC7296] and states that the TSi/TSr payloads MUST contain at least 143 one Traffic Selector type. This document updates the text to mean 144 that the TSi/TSr payloads MUST contain at least one Traffic Selector 145 of type TS_IPV4_ADDR_RANGE or TS_IPV6_ADDR_RANGE, as other Traffic 146 Selector types can be defined that are complimentary to these Traffic 147 Selector Types and cannot be selected on their own without 148 TS_IPV4_ADDR_RANGE or TS_IPV6_ADDR_RANGE. The below defined 149 TS_SECLABEL Traffic Selector Type is an example of this. 151 2. TS_SECLABEL Traffic Selector Type 153 This document defines a new TS Type, TS_SECLABEL that contains a 154 single new opaque Security Label. 156 2.1. TS_SECLABEL payload format 158 1 2 3 159 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 1 160 +---------------+---------------+-------------------------------+ 161 | TS Type | Reserved | Selector Length | 162 +---------------+---------------+-------------------------------+ 163 | | 164 ~ Security Label* ~ 165 | | 166 +---------------------------------------------------------------+ 168 Figure 1: Labeled IPsec Traffic Selector 170 *Note: All fields other than TS Type and Selector Length depend on 171 the TS Type. The fields shown is for TS Type TS_SECLABEL, the 172 selector this document defines. 174 * TS Type (one octet) - Set to [TBD] for TS_SECLABEL, 176 * Selector Length (2 octets, unsigned integer) - Specifies the 177 length of this Traffic Selector substructure including the header. 179 * Security Label - An opaque byte stream of at least one octet. 181 2.2. TS_SECLABEL properties 183 The TS_SECLABEL Traffic Selector Type does not support narrowing or 184 wildcards. It MUST be used as an exact match value. 186 The Security Label contents are opaque to the IKE implementation. 187 That is, the IKE implementation might not have any knowledge of the 188 meaning of this selector, other than as a type and opaque value to 189 pass to the SPD. 191 A zero length Security Label MUST NOT be used. If a received TS 192 payload contains a TS_TYPE of TS_SECLABEL with a zero length Security 193 Label, that specific Traffic Selector MUST be ignored. If no other 194 Traffic Selector of TS_TYPE TS_SECLABEL can be selected, a 195 TS_UNACCEPTABLE Error Notify message MUST be returned. A zero length 196 Security Label MUST NOT be interpreted as a wildcard security label. 198 If multiple Security Labels are allowed for a given IP protocol, 199 start and end address/port match, the initiator includes all of the 200 acceptable TS_SECLABEL's and the responder MUST select one of them. 202 If the Security Label traffic selector is optional from a 203 configuration point of view, the initiator will have to choose which 204 TS payload to attempt first. If it includes the Security Label and 205 receives a TS_UNACCEPTABLE, it can attempt a new Child SA negotiation 206 without that Security Label. 208 A responder that selected a TS with TS_SECLABEL MUST use the Security 209 Label for all selector operations on the resulting TS. It MUST NOT 210 select a TS_SECLABEL without using the specified Security Label, even 211 if it deems the Security Label optional, as the initiator has 212 indicated (and expects) that Security Label will be set for all 213 traffic matching the negotiated TS. 215 3. Traffic Selector negotiation 217 This document updates the [RFC7296] specification as follows: 219 Each TS payload (TSi and TSr) MUST contain at least one TS_TYPE of 220 TS_IPV4_ADDR_RANGE or TS_IPV6_ADDR_RANGE. 222 Each TS payload (TSi or TSr) MAY contain one or more other TS_TYPEs, 223 such as TS_SECLABEL. 225 A responder MUST create each TS response by creating one of more 226 (narrowed or not) TS_IPV4_ADDR_RANGE or TS_IPV6_ADDR_RANGE entries, 227 plus one of each further TS_TYPE present in the offered TS by the 228 initiator. If this is not possible, it MUST return a TS_UNACCEPTABLE 229 Error Notify payload. 231 If a specific TS_TYPE (other than TS_IPV4_ADDR_RANGE or 232 TS_IPV6_ADDR_RANGE which are mandatory) is deemed optional, the 233 initiator SHOULD first try to negotiate the Child SA with the TS 234 payload including the optional TS_TYPE. Upon receiving 235 TS_UNACCEPTABLE, it SHOULD attempt a new Child SA negotiation using 236 the same TS but without the optional TS_TYPE. 238 3.1. Example TS negotiation 240 An initiator could send: 242 TSi = ((17,0,192.0.2.0-192.0.2.255), 243 (0,0,198.51.0-198.51.255), 244 TS_SECLABEL1, TS_SECLABEL2) 246 TSr = ((17,0,203.0.113.0-203.0.113.255), 247 (0,0,203.0.113.0-203.0.113.255), 248 TS_SECLABEL1, TS_SECLABEL2) 250 Figure 2: initiator TS payloads example 252 The responder could answer with the following example: 254 TSi = ((0,0,198.51.0-198.51.255), 255 TS_SECLABEL1) 257 TSr = (((0,0,203.0.113.0-203.0.113.255), 258 TS_SECLABEL1) 260 Figure 3: responder TS payloads example 262 3.2. Considerations for using multiple TS_TYPEs in a TS 264 It would be unlikely that the traffic for TSi and TSr would have a 265 different Security Label, but this specification does allow this to 266 be specified. If the initiator does not support this, and wants to 267 prevent the responder from picking different labels for the TSi / TSr 268 payloads, it should attempt a Child SA negotiation with only the 269 first Security Label first, and upon failure retry a new Child SA 270 negotiation with only the second Security Label. 272 If different IP ranges can only use different specific Security 273 Labels, than these should be negotiated in two different Child SA 274 negotiations. If in the example above, the initiator only allows 275 192.0.2.0/24 with TS_SECLABEL1, and 198.51.0/24 with TS_SECLABEL2, 276 than it MUST NOT combine these two ranges and security labels into 277 one Child SA negotiation. 279 The mechanism of narrowing of Traffic Selectors with 280 TS_IPV4_ADDR_RANGE and TS_IPV6_ADDR_RANGE does not apply to 281 TS_SECLABEL as the Security Label itself is not interpreted and 282 cannot be narrowed. It MUST be matched exactly. Since a rekey MUST 283 NOT narrow down the Traffic Selectors narrower than the scope 284 currently in use, the only valid choice of TS_SECLABEL for a rekey is 285 the identical TS_SECLABEL that is in use by the Child SA being 286 rekeyed. If the TS_LABEL is missing from the TS during the rekey 287 negotiation, the negotiation MUST fail with TS_UNACCEPTABLE. 289 4. Security Considerations 291 It is assumed that the Security Label can be matched by the IKE 292 implementation to its own configured value, even if the IKE 293 implementation itself cannot interpret the Security Label value. 295 A packet that matches an SPD entry for all components except the 296 Security Label would be treated as "not matching". If no other SPD 297 entries match, the (mis-labeled) traffic might end up being 298 transmitted in the clear. It is presumed that other Mandatory Access 299 Control methods are in place to prevent mis-labeled traffic from 300 reaching the IPsec subsystem, or that the IPsec subsystem itself 301 would install a REJECT/DISCARD rule in the SPD to prevent unlabeled 302 traffic otherwise matching a labeled security SPD rule from being 303 transmitted without IPsec protection. 305 5. IANA Considerations 307 This document defines two new entries in the IKEv2 Traffic Selector 308 Types registry: 310 Value TS Type Reference 311 ----- --------------------------- ----------------- 312 TBD TS_SECLABEL [this document] 314 Figure 4 316 6. Implementation Status 318 [Note to RFC Editor: Please remove this section and the reference to 319 [RFC6982] before publication.] 321 This section records the status of known implementations of the 322 protocol defined by this specification at the time of posting of this 323 Internet-Draft, and is based on a proposal described in [RFC7942]. 324 The description of implementations in this section is intended to 325 assist the IETF in its decision processes in progressing drafts to 326 RFCs. Please note that the listing of any individual implementation 327 here does not imply endorsement by the IETF. Furthermore, no effort 328 has been spent to verify the information presented here that was 329 supplied by IETF contributors. This is not intended as, and must not 330 be construed to be, a catalog of available implementations or their 331 features. Readers are advised to note that other implementations may 332 exist. 334 According to [RFC7942], "this will allow reviewers and working groups 335 to assign due consideration to documents that have the benefit of 336 running code, which may serve as evidence of valuable experimentation 337 and feedback that have made the implemented protocols more mature. 338 It is up to the individual working groups to use this information as 339 they see fit". 341 Authors are requested to add a note to the RFC Editor at the top of 342 this section, advising the Editor to remove the entire section before 343 publication, as well as the reference to [RFC7942]. 345 6.1. Libreswan 347 Organization: The Libreswan Project 349 Name: https://lists.libreswan.org/mailman/listinfo/swan-dev/ 351 Description: Implementation has been released as part of libreswan 352 version 4.4. 354 Level of maturity: beta 356 Coverage: Implements the entire draft using SElinux based labels 358 Licensing: GPLv2 360 Implementation experience: No interop testing has been done yet. 361 The code works as proof of concept, but is not yet production 362 ready when using multiple different labels with on-demand kernel 363 ACQUIRES. 365 Contact: Libreswan Development: swan-dev@libreswan.org 367 7. Acknowledgements 369 A large part of the introduction text was taken verbatim from 370 [draft-jml-ipsec-ikev2-security-label] whose authors are J Latten, D. 371 Quigley and J. Lu. Valery Smyslov provided valuable input regarding 372 IKEv2 Traffic Selector semantics. 374 8. References 375 8.1. Normative References 377 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 378 Requirement Levels", BCP 14, RFC 2119, 379 DOI 10.17487/RFC2119, March 1997, 380 . 382 [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. 383 Kivinen, "Internet Key Exchange Protocol Version 2 384 (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October 385 2014, . 387 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 388 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 389 May 2017, . 391 8.2. Informative References 393 [draft-jml-ipsec-ikev2-security-label] 394 Latten, J., Quigley, D., and J. Lu, "Security Label 395 Extension to IKE", 28 January 2011. 397 [FIPS188] NIST, "National Institute of Standards and Technology, 398 "Standard Security Label for Information Transfer"", 399 Federal Information Processing Standard (FIPS) Publication 400 188, September 1994, 401 . 404 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 405 Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, 406 December 2005, . 408 [RFC5570] StJohns, M., Atkinson, R., and G. Thomas, "Common 409 Architecture Label IPv6 Security Option (CALIPSO)", 410 RFC 5570, DOI 10.17487/RFC5570, July 2009, 411 . 413 [RFC6982] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 414 Code: The Implementation Status Section", RFC 6982, 415 DOI 10.17487/RFC6982, July 2013, 416 . 418 [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 419 Code: The Implementation Status Section", BCP 205, 420 RFC 7942, DOI 10.17487/RFC7942, July 2016, 421 . 423 Authors' Addresses 425 Paul Wouters 426 Aiven 428 Email: paul.wouters@aiven.io 430 Sahana Prasad 431 Red Hat 433 Email: sahana@redhat.com