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Prasad 4 Updates: 7296 (if approved) Red Hat 5 Intended status: Standards Track October 30, 2020 6 Expires: May 3, 2021 8 Labeled IPsec Traffic Selector support for IKEv2 9 draft-ietf-ipsecme-labeled-ipsec-04 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 May 3, 2021. 39 Copyright Notice 41 Copyright (c) 2020 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 46 (https://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 57 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 58 1.2. Traffic Selector clarification . . . . . . . . . . . . . 3 59 1.3. Traffic Selector update . . . . . . . . . . . . . . . . . 4 60 2. TS_SECLABEL Traffic Selector Type . . . . . . . . . . . . . . 4 61 2.1. TS_SECLABEL payload format . . . . . . . . . . . . . . . 4 62 2.2. TS_SECLABEL properties . . . . . . . . . . . . . . . . . 4 63 3. Traffic Selector negotiation . . . . . . . . . . . . . . . . 5 64 3.1. Example TS negotiation . . . . . . . . . . . . . . . . . 6 65 3.2. Considerations for using multiple TS_TYPEs in a TS . . . 6 66 4. Security Considerations . . . . . . . . . . . . . . . . . . . 7 67 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 68 6. Implementation Status . . . . . . . . . . . . . . . . . . . . 7 69 6.1. Libreswan . . . . . . . . . . . . . . . . . . . . . . . . 8 70 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 71 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 72 8.1. Normative References . . . . . . . . . . . . . . . . . . 9 73 8.2. Informative References . . . . . . . . . . . . . . . . . 9 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 76 1. Introduction 78 In computer security, Mandatory Access Control usually refers to 79 systems in which all subjects and objects are assigned a security 80 label. A security label is comprised of a set of security 81 attributes. The security labels along with a system authorization 82 policy determine access. Rules within the system authorization 83 policy determine whether the access will be granted based on the 84 security attributes of the subject and object. 86 Traditionally, security labels used by Multilevel Systems (MLS) are 87 comprised of a sensitivity level (or classification) field and a 88 compartment (or category) field, as defined in [FIPS188] and 89 [RFC5570]. As MAC systems evolved, other MAC models gained in 90 popularity. For example, SELinux, a Flux Advanced Security Kernel 91 (FLASK) implementation, has security labels represented as colon- 92 separated ASCII strings composed of values for identity, role, and 93 type. The security labels are often referred to as security 94 contexts. 96 Traffic Selector (TS) payloads specify the selection criteria for 97 packets that will be forwarded over the newly set up IPsec SA as 98 enforced by the Security Policy Database (SPD, see [RFC4301]). This 99 document updates the Traffic Selector negotiation specified in 100 Section 2.9 of [RFC7296]. 102 This document specifies a new Traffic Selector Type TS_SECLABEL for 103 IKEv2 that can be used to negotiate security labels as additional 104 selectors for the Security Policy Database (SPD) to further restrict 105 the type of traffic allowed to be sent and received over the IPsec 106 SA. 108 1.1. Requirements Language 110 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 111 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 112 "OPTIONAL" in this document are to be interpreted as described in BCP 113 14 [RFC2119] [RFC8174] when, and only when, they appear in all 114 capitals, as shown here. 116 1.2. Traffic Selector clarification 118 The negotiation of Traffic Selectors is specified in Section 2.9 of 119 [RFC7296] where it defines two TS Types (TS_IPV4_ADDR_RANGE and 120 TS_IPV6_ADDR_RANGE). The Traffic Selector payload format is 121 specified in Section 3.13 of [RFC7296]. However, the term Traffic 122 Selector is used to denote the traffic selector payloads and 123 individual traffic selectors of that payload. Sometimes the exact 124 meaning can only be learned from context or if the item is written in 125 plural ("Traffic Selectors" or "TSs"). This section clarifies these 126 terms as follows: 128 A Traffic Selector (no acronym) is one selector for traffic of a 129 specific Traffic Selector Type (TS_TYPE). For example a Traffic 130 Selector of TS_TYPE TS_IPV4_ADDR_RANGE for UDP traffic in the IP 131 network 198.51.100.0/24 covering all ports, is denoted as (17, 0, 132 198.51.100.0-198.51.100.255) 134 A Traffic Selector payload (TS) is a set of one or more Traffic 135 Selectors of the same or different TS_TYPEs, but MUST include at 136 least one TS_TYPE of TS_IPV4_ADDR_RANGE or TS_IPV6_ADDR_RANGE. For 137 example, the above Traffic Selector by itself in a TS payload is 138 denoted as TS((17, 0, 198.51.100.0-198.51.100.255)) 140 1.3. Traffic Selector update 142 The negotiation of Traffic Selectors is specified in Section 2.9 of 143 [RFC7296] and states that the TSi/TSr payloads MUST contain at least 144 one Traffic Selector type. This document updates the text to mean 145 that the TSi/TSr payloads MUST contain at least one Traffic Selector 146 of type TS_IPV4_ADDR_RANGE or TS_IPV6_ADDR_RANGE, as other Traffic 147 Selector types can be defined that are complimentary to these Traffic 148 Selector Types and cannot be selected on their own without 149 TS_IPV4_ADDR_RANGE or TS_IPV6_ADDR_RANGE. The below defined 150 TS_SECLABEL Traffic Selector Type is an example of this. 152 2. TS_SECLABEL Traffic Selector Type 154 This document defines a new TS Type, TS_SECLABEL that contains a 155 single new opaque Security Label. 157 2.1. TS_SECLABEL payload format 159 1 2 3 160 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 1 161 +---------------+---------------+-------------------------------+ 162 | TS Type | Reserved | Selector Length | 163 +---------------+---------------+-------------------------------+ 164 | | 165 ~ Security Label* ~ 166 | | 167 +---------------------------------------------------------------+ 169 Figure 1: Labeled IPsec Traffic Selector 171 *Note: All fields other than TS Type and Selector Length depend on 172 the TS Type. The fields shown is for TS Type TS_SECLABEL, the 173 selector this document defines. 175 o TS Type (one octet) - Set to [TBD] for TS_SECLABEL, 177 o Selector Length (2 octets, unsigned integer) - Specifies the 178 length of this Traffic Selector substructure including the header. 180 o Security Label - An opaque byte stream of at least one octet. 182 2.2. TS_SECLABEL properties 184 The TS_SECLABEL Traffic Selector Type does not support narrowing or 185 wildcards. It MUST be used as an exact match value. 187 If the TS_SECLABEL is present in a TSi/TSr, at least one Traffic 188 Selector of type TS_IPV4_ADDR_RANGE or TS_IPV6_ADDR_RANGE MUST also 189 be present in that TSi/TSr. 191 The Security Label contents are opaque to the IKE implementation. 192 That is, the IKE implementation might not have any knowledge of the 193 meaning of this selector, other than as a type and opaque value to 194 pass to the SPD. 196 A zero length Security Label MUST NOT be used. If a received TS 197 payload contains a TS_TYPE of TS_SECLABEL with a zero length Security 198 Label, that specific Traffic Selector MUST be ignored. If no other 199 Traffic Selector of TS_TYPE TS_SECLABEL can be selected, a 200 TS_UNACCEPTABLE Error Notify message MUST be returned. A zero length 201 Security Label MUST NOT be interpreted as a wildcard security label. 203 If multiple Security Labels are allowed for a given IP protocol, 204 start and end address/port match, multiple TS_SECLABEL can be 205 included in a TS payload. 207 If the Security Label traffic selector is optional from a 208 configuration point of view, the initiator will have to choose which 209 TS payload to attempt first. If it includes the Security Label and 210 receives a TS_UNACCEPTABLE, it can attempt a new Child SA negotiation 211 without that Security Label. 213 A responder that selected a TS with TS_SECLABEL MUST use the Security 214 Label for all selector operations on the resulting IPsec SA. It MUST 215 NOT select a TS_set with a TS_SECLABEL without using the specified 216 Security Label, even if it deems the Security Label optional, as the 217 initiator TS_set with TS_SECLABEL means the initiator mandates using 218 that Security Label. 220 3. Traffic Selector negotiation 222 This document updates the [RFC7296] specification as follows: 224 Each TS payload (TSi and TSr) MUST contain at least one TS_TYPE of 225 TS_IPV4_ADDR_RANGE or TS_IPV6_ADDR_RANGE. 227 Each TS payload (TSi or TSr) MAY contain one or more other TS_TYPEs, 228 such as TS_SECLABEL. 230 A responder MUST create its TS response by selecting one of each 231 TS_TYPE present in the offered TS by the initiator. If it cannot 232 select one of each TS_TYPE, it MUST return a TS_UNACCEPTABLE Error 233 Notify payload. 235 If a specific TS_TYPE (other than TS_IPV4_ADDR_RANGE or 236 TS_IPV6_ADDR_RANGE which are mandatory) is deemed optional, the 237 initiator SHOULD first try to negotiate the Child SA with the TS 238 payload including the optional TS_TYPE. Upon receiving 239 TS_UNACCEPTABLE, it SHOULD attempt a new Child SA negotiation using 240 the same TS but without the optional TS_TYPE. 242 Some TS_TYPE's support narrowing, where the responder is allowed to 243 select a subset of the original TS. Narrowing MUST NOT result in an 244 empty selector for that TS_TYPE. 246 3.1. Example TS negotiation 248 An initiator could send: 250 TSi = ((17,0,192.0.2.0-192.0.2.255), 251 (0,0,198.51.0-198.51.255), 252 TS_SECLABEL1, TS_SECLABEL2) 254 TSr = ((17,0,203.0.113.0-203.0.113.255), 255 (0,0,203.0.113.0-203.0.113.255), 256 TS_SECLABEL1, TS_SECLABEL2) 258 Figure 2: initiator TS payloads example 260 The responder could answer with the following example: 262 TSi = ((0,0,198.51.0-198.51.255), 263 TS_SECLABEL1) 265 TSr = (((0,0,203.0.113.0-203.0.113.255), 266 TS_SECLABEL1) 268 Figure 3: responder TS payloads example 270 3.2. Considerations for using multiple TS_TYPEs in a TS 272 It would be unlikely that the traffic for TSi and TSr would have a 273 different Security Label, but this specification does allow this to 274 be specified. If the initiator does not support this, and wants to 275 prevent the responder from picking different labels for the TSi / TSr 276 payloads, it should attempt a Child SA negotiation with only the 277 first Security Label first, and upon failure retry a new Child SA 278 negotiation with only the second Security Label. 280 If different IP ranges can only use different specific Security 281 Labels, than these should be negotiated in two different Child SA 282 negotiations. If in the example above, the initiator only allows 283 192.0.2.0/24 with TS_SECLABEL1, and 198.51.0/24 with TS_SECLABEL2, 284 than it MUST NOT combine these two ranges and security labels into 285 one Child SA negotiation. 287 The mechanism of narrowing of Traffic Selectors with 288 TS_IPV4_ADDR_RANGE and TS_IPV6_ADDR_RANGE does not apply to 289 TS_SECLABEL as the Security Label itself is not interpreted and 290 cannot itself be narrowed. It MUST be matched exactly. Rekey of an 291 IPsec SA MUST only use identical Traffic Selectors, which means the 292 same TS Type and selectors MUST be used. This guarantees that a 293 Security Label once negotiated, remains part of the IPsec SA after a 294 rekey. 296 4. Security Considerations 298 It is assumed that the Security Label can be matched by the IKE 299 implementation to its own configured value, even if the IKE 300 implementation itself cannot interpret the Security Label value. 302 A packet that matches an SPD entry for all components except the 303 Security Label would be treated as "not matching". If no other SPD 304 entries match, the (mis-labeled) traffic might end up being 305 transmitted in the clear. It is presumed that other Mandatory Access 306 Control methods are in place to prevent mis-labeled traffic from 307 reaching the IPsec subsystem, or that the IPsec subsystem itself 308 would install a REJECT/DISCARD rule in the SPD to prevent unlabeled 309 traffic otherwise matching a labeled security SPD rule from being 310 transmitted without IPsec protection. 312 5. IANA Considerations 314 This document defines two new entries in the IKEv2 Traffic Selector 315 Types registry: 317 Value TS Type Reference 318 ----- --------------------------- ----------------- 319 TBD TS_SECLABEL [this document] 321 Figure 4 323 6. Implementation Status 325 [Note to RFC Editor: Please remove this section and the reference to 326 [RFC6982] before publication.] 327 This section records the status of known implementations of the 328 protocol defined by this specification at the time of posting of this 329 Internet-Draft, and is based on a proposal described in [RFC7942]. 330 The description of implementations in this section is intended to 331 assist the IETF in its decision processes in progressing drafts to 332 RFCs. Please note that the listing of any individual implementation 333 here does not imply endorsement by the IETF. Furthermore, no effort 334 has been spent to verify the information presented here that was 335 supplied by IETF contributors. This is not intended as, and must not 336 be construed to be, a catalog of available implementations or their 337 features. Readers are advised to note that other implementations may 338 exist. 340 According to [RFC7942], "this will allow reviewers and working groups 341 to assign due consideration to documents that have the benefit of 342 running code, which may serve as evidence of valuable experimentation 343 and feedback that have made the implemented protocols more mature. 344 It is up to the individual working groups to use this information as 345 they see fit". 347 Authors are requested to add a note to the RFC Editor at the top of 348 this section, advising the Editor to remove the entire section before 349 publication, as well as the reference to [RFC7942]. 351 6.1. Libreswan 353 Organization: The Libreswan Project 355 Name: https://lists.libreswan.org/mailman/listinfo/swan-dev/ 357 Description: A Proof of Concept branch is available for interop 358 testing. 360 Level of maturity: Alpha 362 Coverage: Implements the entire draft using SElinux based labels 364 Licensing: GPLv2 366 Implementation experience: TBD 368 Contact: Libreswan Development: swan-dev@libreswan.org 370 7. Acknowledgements 372 A large part of the introduction text was taken verbatim from 373 [draft-jml-ipsec-ikev2-security-label] whose authors are J Latten, D. 374 Quigley and J. Lu. 376 8. References 378 8.1. Normative References 380 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 381 Requirement Levels", BCP 14, RFC 2119, 382 DOI 10.17487/RFC2119, March 1997, 383 . 385 [RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T. 386 Kivinen, "Internet Key Exchange Protocol Version 2 387 (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October 388 2014, . 390 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 391 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 392 May 2017, . 394 8.2. Informative References 396 [draft-jml-ipsec-ikev2-security-label] 397 Latten, J., Quigley, D., and J. Lu, "Security Label 398 Extension to IKE", draft-wouters-edns-tcp-keeaplive (work 399 in progress), January 2011. 401 [FIPS188] NIST, "National Institute of Standards and Technology, 402 "Standard Security Label for Information Transfer"", 403 Federal Information Processing Standard (FIPS) Publication 404 188, September 1994. 406 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 407 Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, 408 December 2005, . 410 [RFC5570] StJohns, M., Atkinson, R., and G. Thomas, "Common 411 Architecture Label IPv6 Security Option (CALIPSO)", 412 RFC 5570, DOI 10.17487/RFC5570, July 2009, 413 . 415 [RFC6982] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 416 Code: The Implementation Status Section", RFC 6982, 417 DOI 10.17487/RFC6982, July 2013, 418 . 420 [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 421 Code: The Implementation Status Section", BCP 205, 422 RFC 7942, DOI 10.17487/RFC7942, July 2016, 423 . 425 Authors' Addresses 427 Paul Wouters 428 Red Hat 430 Email: pwouters@redhat.com 432 Sahana Prasad 433 Red Hat 435 Email: sahana@redhat.com