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Williams 3 Internet-Draft Sun 4 Expires: August 28, 2008 February 25, 2008 6 Extended Generic Security Service Mechanism Inquiry APIs 7 draft-ietf-kitten-extended-mech-inquiry-03.txt 9 Status of this Memo 11 By submitting this Internet-Draft, each author represents that any 12 applicable patent or other IPR claims of which he or she is aware 13 have been or will be disclosed, and any of which he or she becomes 14 aware will be disclosed, in accordance with Section 6 of BCP 79. 16 Internet-Drafts are working documents of the Internet Engineering 17 Task Force (IETF), its areas, and its working groups. Note that 18 other groups may also distribute working documents as Internet- 19 Drafts. 21 Internet-Drafts are draft documents valid for a maximum of six months 22 and may be updated, replaced, or obsoleted by other documents at any 23 time. It is inappropriate to use Internet-Drafts as reference 24 material or to cite them other than as "work in progress." 26 The list of current Internet-Drafts can be accessed at 27 http://www.ietf.org/ietf/1id-abstracts.txt. 29 The list of Internet-Draft Shadow Directories can be accessed at 30 http://www.ietf.org/shadow.html. 32 This Internet-Draft will expire on August 28, 2008. 34 Copyright Notice 36 Copyright (C) The IETF Trust (2008). 38 Abstract 40 This document introduces new application programming interfaces 41 (APIs) to the Generic Security Services API (GSS-API) for extended 42 mechanism attribute inquiry. These interfaces are primarily intended 43 to reduce instances of hardcoding of mechanism identifiers in GSS 44 applications. 46 These interfaces include: mechanism attributes and attribute sets, a 47 function for inquiring the attributes of a mechanism, a function for 48 indicating mechanisms that posses given attributes, and a function 49 for displaying mechanism attributes. 51 Table of Contents 53 1. Conventions used in this document . . . . . . . . . . . . 3 54 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . 3 55 3. New GSS-API Interfaces . . . . . . . . . . . . . . . . . . 3 56 3.1. Mechanism Attributes and Attribute Sets . . . . . . . . . 3 57 3.2. List of Known Mechanism Attributes . . . . . . . . . . . . 4 58 3.3. Mechanism Attribute Sets of Existing Mechs . . . . . . . . 6 59 3.4. New GSS-API Function Interfaces . . . . . . . . . . . . . 7 60 3.4.1. GSS_Indicate_mechs_by_attr() . . . . . . . . . . . . . . . 8 61 3.4.2. GSS_Inquire_attrs_for_mech() . . . . . . . . . . . . . . . 8 62 3.4.3. GSS_Display_mech_attr() . . . . . . . . . . . . . . . . . 9 63 3.4.4. New Major Status Values . . . . . . . . . . . . . . . . . 9 64 3.4.5. C-Bindings . . . . . . . . . . . . . . . . . . . . . . . . 9 65 4. Requirements for Mechanism Designers . . . . . . . . . . . 10 66 5. IANA Considerations . . . . . . . . . . . . . . . . . . . 10 67 6. Security considerations . . . . . . . . . . . . . . . . . 10 68 7. References . . . . . . . . . . . . . . . . . . . . . . . . 11 69 7.1. Normative References . . . . . . . . . . . . . . . . . . . 11 70 7.2. Informative References . . . . . . . . . . . . . . . . . . 11 71 Author's Address . . . . . . . . . . . . . . . . . . . . . 11 72 Intellectual Property and Copyright Statements . . . . . . 12 74 1. Conventions used in this document 76 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 77 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 78 document are to be interpreted as described in [RFC2119]. 80 2. Introduction 82 GSS-API [RFC2743] mechanisms have a number of properties that may be 83 of interest to applications. The lack of APIs for inquiring about 84 available mechanisms' properties has meant that many GSS-API 85 applications must hardcode mechanism OIDs. Ongoing work may result 86 in a variety of new GSS-API mechanisms. Applications should not have 87 to hardcode their OIDs. 89 For example, the SSHv2 protocol [RFC4251] supports the use of GSS-API 90 mechanisms for authentication [RFC4462], but it explicitly prohibits 91 the use of SPNEGO [RFC4178]. Future mechanisms that negotiate 92 mechanisms would have to be forbidden as well, but there is no way to 93 implement applications that inquire what mechanisms are available and 94 then programmatically exclude mechanisms "like SPNEGO". 96 3. New GSS-API Interfaces 98 We introduce a new concept: that of mechanism attributes. By 99 allowing applications to query the set of attributes associated with 100 individual mechanisms and to find out which mechanisms support a 101 given set of attributes we allow applications to select mechanisms 102 based on their attributes yet without having to hardcode mechanism 103 OIDs. 105 Section 3.1 describes the mechanism attributes concept. Sections 106 3.4.1, 3.4.2 and 3.4.3 describe three new interfaces that deal in 107 mechanisms and attribute sets: 109 o GSS_Indicate_mechs_by_attrs() 110 o GSS_Inquire_attrs_for_mech() 111 o GSS_Display_mech_attr() 113 3.1. Mechanism Attributes and Attribute Sets 115 An abstraction for the features provided by pseudo-mechanisms is 116 needed in order to facilitate the programmatic selection of 117 mechanisms. 119 Two data types are needed: one for individual mechanism attributes 120 and one for mechanism attribute sets. To simplify the mechanism 121 attributes interfaces we reuse the 'OID' and 'OID set' data types and 122 model individual mechanism attribute types as OIDs. 124 To this end we define an open namespace of mechanism attributes and 125 assign them arcs off of this OID: 127 [1.3.6.1.5.5.12 appears to be available] 129 Each mechanism has a set of mechanism attributes that it supports as 130 described in its specification. 132 3.2. List of Known Mechanism Attributes 134 +-------------------------+---------+-------------------------+ 135 | Mech Attr Name | OID Arc | Arc Name | 136 +-------------------------+---------+-------------------------+ 137 | GSS_C_MA_MECH_CONCRETE | (1) | concrete-mech | 138 | GSS_C_MA_MECH_PSEUDO | (2) | pseudo-mech | 139 | GSS_C_MA_MECH_COMPOSITE | (3) | composite-mech | 140 | GSS_C_MA_MECH_NEGO | (4) | mech-negotiation-mech | 141 | GSS_C_MA_MECH_GLUE | (5) | mech-glue | 142 | GSS_C_MA_NOT_MECH | (6) | not-mech | 143 | GSS_C_MA_DEPRECATED | (7) | mech-deprecated | 144 | GSS_C_MA_NOT_DFLT_MECH | (8) | mech-not-default | 145 | GSS_C_MA_ITOK_FRAMED | (9) | initial-is-framed | 146 | GSS_C_MA_AUTH_INIT | (10) | auth-init-princ | 147 | GSS_C_MA_AUTH_TARG | (11) | auth-targ-princ | 148 | GSS_C_MA_AUTH_INIT_INIT | (12) | auth-init-princ-initial | 149 | GSS_C_MA_AUTH_TARG_INIT | (13) | auth-targ-princ-initial | 150 | GSS_C_MA_AUTH_INIT_ANON | (14) | auth-init-princ-anon | 151 | GSS_C_MA_AUTH_TARG_ANON | (15) | auth-targ-princ-anon | 152 | GSS_C_MA_DELEG_CRED | (16) | deleg-cred | 153 | GSS_C_MA_INTEG_PROT | (17) | integ-prot | 154 | GSS_C_MA_CONF_PROT | (18) | conf-prot | 155 | GSS_C_MA_MIC | (19) | mic | 156 | GSS_C_MA_WRAP | (20) | wap | 157 | GSS_C_MA_PROT_READY | (21) | prot-ready | 158 | GSS_C_MA_REPLAY_DET | (22) | replay-detection | 159 | GSS_C_MA_OOS_DET | (23) | oos-detection | 160 | GSS_C_MA_CBINDINGS | (24) | channel-bindings | 161 | GSS_C_MA_PFS | (25) | pfs | 162 | GSS_C_MA_COMPRESS | (26) | compress | 163 | GSS_C_MA_CTX_TRANS | (27) | context-transfer | 164 | | (28..) | | 165 +-------------------------+---------+-------------------------+ 167 Table 1 169 +-------------------------+-----------------------------------------+ 170 | Mech Attr Name | Purpose | 171 +-------------------------+-----------------------------------------+ 172 | GSS_C_MA_MECH_CONCRETE | Indicates that a mech is neither a | 173 | | pseudo- mechanism nor a composite | 174 | | mechanism. | 175 | GSS_C_MA_MECH_PSEUDO | Indicates that a mech is a | 176 | | pseudo-mechanism. | 177 | GSS_C_MA_MECH_COMPOSITE | Indicates that a mech is a composite of | 178 | | other mechanisms. This is reserved for | 179 | | a specification of "stackable" | 180 | | pseudo-mechanisms. | 181 | GSS_C_MA_MECH_NEGO | Indicates that a mech negotiates other | 182 | | mechs (e.g., SPNEGO has this | 183 | | attribute). | 184 | GSS_C_MA_MECH_GLUE | Indicates that the OID is not for a | 185 | | mechanism but for the GSS-API itself. | 186 | GSS_C_MA_NOT_MECH | Indicates that the OID is known, yet | 187 | | also known not to be the OID of any | 188 | | GSS-API mechanism (or the GSS-API | 189 | | itself). | 190 | GSS_C_MA_DEPRECATED | Indicates that a mech (or its OID) is | 191 | | deprecated and MUST NOT be used as a | 192 | | default mechanism. | 193 | GSS_C_MA_NOT_DFLT_MECH | Indicates that a mech (or its OID) MUST | 194 | | NOT be used as a default mechanism. | 195 | GSS_C_MA_ITOK_FRAMED | Indicates that the given mechanism's | 196 | | initial context tokens are properly | 197 | | framed as per-section 3.1 of rfc2743. | 198 | GSS_C_MA_AUTH_INIT | Indicates support for authentication of | 199 | | initiator to acceptor. | 200 | GSS_C_MA_AUTH_TARG | Indicates support for authentication of | 201 | | acceptor to initiator. | 202 | GSS_C_MA_AUTH_INIT_INIT | Indicates support for "initial" | 203 | | authentication of initiator to | 204 | | acceptor. | 205 | GSS_C_MA_AUTH_TARG_INIT | Indicates support for initial | 206 | | authentication of acceptor to | 207 | | initiator. | 208 | GSS_C_MA_AUTH_INIT_ANON | Indicates support for | 209 | | GSS_C_NT_ANONYMOUS as an initiator | 210 | | principal name. | 211 | GSS_C_MA_AUTH_TARG_ANON | Indicates support for | 212 | | GSS_C_NT_ANONYMOUS as a target | 213 | | principal name. | 214 | GSS_C_MA_DELEG_CRED | Indicates support for credential | 215 | | delegation. | 216 | GSS_C_MA_INTEG_PROT | Indicates support for per-message | 217 | | integrity protection. | 218 | GSS_C_MA_CONF_PROT | Indicates support for per-message | 219 | | confidentiality protection. | 220 | GSS_C_MA_MIC | Indicates support for MIC tokens. | 221 | GSS_C_MA_WRAP | Indicates support for WRAP tokens. | 222 | GSS_C_MA_PROT_READY | Indicates support for per-message | 223 | | protection prior to full context | 224 | | establishment. | 225 | GSS_C_MA_REPLAY_DET | Indicates support for replay detection. | 226 | GSS_C_MA_OOS_DET | Indicates support for out-of-sequence | 227 | | detection. | 228 | GSS_C_MA_CBINDINGS | Indicates support for channel bindings. | 229 | GSS_C_MA_PFS | Indicates support for Perfect Forward | 230 | | Security. | 231 | GSS_C_MA_COMPRESS | Indicates support for compression of | 232 | | data inputs to GSS_Wrap(). | 233 | GSS_C_MA_CTX_TRANS | Indicates support for security context | 234 | | export/import. | 235 +-------------------------+-----------------------------------------+ 237 Table 2 239 3.3. Mechanism Attribute Sets of Existing Mechs 241 The Kerberos V mechanism [RFC1964] provides the following mechanism 242 attributes: 244 o GSS_C_MA_MECH_CONCRETE 245 o GSS_C_MA_ITOK_FRAMED 246 o GSS_C_MA_AUTH_INIT 247 o GSS_C_MA_AUTH_TARG 248 o GSS_C_MA_DELEG_CRED 249 o GSS_C_MA_INTEG_PROT 250 o GSS_C_MA_CONF_PROT 251 o GSS_C_MA_MIC 252 o GSS_C_MA_WRAP 253 o GSS_C_MA_PROT_READY 254 o GSS_C_MA_REPLAY_DET 255 o GSS_C_MA_OOS_DET 256 o GSS_C_MA_CBINDINGS 257 o GSS_C_MA_CTX_TRANS (some implementations, using implementation- 258 specific exported context token formats) 260 The Kerberos V mechanism also has a deprecated OID which has the same 261 mechanism attributes as above, and GSS_C_MA_DEPRECATED. 263 The mechanism attributes of the SPKM [RFC2025] family of mechanisms 264 will be provided in a separate document as SPKM is current being 265 reviewed for possibly significant changes due to problems in its 266 specifications. 268 The LIPKEY mechanism [RFC2847] offers the following attributes: 270 o GSS_C_MA_MECH_CONCRETE 271 o GSS_C_MA_ITOK_FRAMED 272 o GSS_C_MA_AUTH_INIT_INIT 273 o GSS_C_MA_AUTH_TARG (from SPKM-3) 274 o GSS_C_MA_AUTH_TARG_ANON (from SPKM-3) 275 o GSS_C_MA_INTEG_PROT 276 o GSS_C_MA_CONF_PROT 277 o GSS_C_MA_REPLAY_DET 278 o GSS_C_MA_OOS_DET 279 o GSS_C_MA_CTX_TRANS (some implementations, using implementation- 280 specific exported context token formats) 282 (LIPKEY should also provide GSS_C_MA_CBINDINGS, but SPKM-3 283 requires clarifications on this point.) 285 The SPNEGO mechanism [RFC4178] provides the following attributes: 286 o GSS_C_MA_MECH_NEGO 287 o GSS_C_MA_ITOK_FRAMED 289 The attributes of mechanisms negotiated by SPNEGO are not modified by 290 the use of SPNEGO. 292 All other mechanisms' attributes will be described elsewhere. 294 3.4. New GSS-API Function Interfaces 296 Several new interfaces are given by which, for example, GSS-API 297 applications may determine what features are provided by a given 298 mechanism and what mechanisms provide what features. 300 These new interfaces are all OPTIONAL. 302 Applications should use GSS_Indicate_mechs_by_attr() instead of 303 GSS_Indicate_mechs() wherever possible. 305 Applications can use GSS_Indicate_mechs_by_attr() to determine what, 306 if any, mechanisms provide a given set of features. 308 GSS_Indicate_mechs_by_attr() can also be used to indicate (as in 309 GSS_Indicate_mechs()) the set of available mechanisms of each type 310 (concrete, mechanism negotiation pseudo-mechanism, etc.). 312 3.4.1. GSS_Indicate_mechs_by_attr() 313 Inputs: 314 o desired_mech_attrs SET OF OBJECT IDENTIFIER -- set of GSS_C_MA_* 315 OIDs that the mechanisms indicated in the mechs output parameter 316 MUST offer. 317 o except_mech_attrs SET OF OBJECT IDENTIFIER -- set of GSS_C_MA_* 318 OIDs that the mechanisms indicated in the mechs output parameter 319 MUST NOT offer. 321 Outputs: 322 o major_status INTEGER, 323 o minor_status INTEGER, 324 o mechs SET OF OBJECT IDENTIFIER -- set of mechanisms that support 325 -- the desired_mech_attrs but not the except_mech_attrs. 327 Return major_status codes: 328 o GSS_S_COMPLETE indicates success; the output mechs parameter MAY 329 be the empty set (GSS_C_NO_OID_SET). 330 o GSS_BAD_MECH_ATTR indicates that at least one mechanism attribute 331 OID in desired_mech_attrs or except_mech_attrs is unknown to the 332 implementation. 333 o GSS_S_FAILURE indicates that the request failed for some other 334 reason. 336 GSS_Indicate_mechs_by_mech_attrs() returns the set of mechanism OIDs 337 that offer at least the desired_mech_attrs but none of the 338 except_mech_attrs. 340 When desired_mech_attrs and except_mech_attrs are the empty set this 341 function acts as a version of GSS_indicate_mechs() that outputs the 342 set of all supported mechanisms of all types. By setting the 343 desired_mechs input parameter to a set of a single GSS_C_MA_MECH* 344 feature applications can obtain the list of all supported mechanisms 345 of a given type (concrete, etc...). 347 3.4.2. GSS_Inquire_attrs_for_mech() 349 Inputs: 350 o mech OBJECT IDENTIFIER -- mechanism OID 352 Outputs: 353 o major_status INTEGER, 354 o minor_status INTEGER, 355 o mech_attrs SET OF OBJECT IDENTIFIER -- set of mech_attrs OIDs 356 (GSS_C_MA_*) 358 Return major_status codes: 359 o GSS_S_COMPLETE indicates success; the output mech_attrs parameter 360 MAY be the empty set (GSS_C_NO_OID_SET). 362 o GSS_S_BAD_MECH indicates that the mechanism named by the mech 363 parameter does not exist or that mech is GSS_C_NO_OID and no 364 default mechanism could be determined. 365 o GSS_S_FAILURE indicates that the request failed for some other 366 reason. 368 GSS_Inquire_mech_attrs_for_mech() indicates the set of mechanism 369 attributes supported by a given mechanism. 371 3.4.3. GSS_Display_mech_attr() 373 Inputs: 374 o mech_attr OBJECT IDENTIFIER -- mechanism attribute OID 376 Outputs: 377 o major_status INTEGER, 378 o minor_status INTEGER, 379 o name OCTET STRING, -- name of mechanism attribute (e.g., 380 GSS_C_MA_*) 381 o short_desc OCTET STRING, -- a short description of the mechanism 382 attribute 383 o long_desc OCTET STRING -- a longer description of the mechanism 384 attribute 386 Return major_status codes: 387 o GSS_S_COMPLETE indicates success. 388 o GSS_S_BAD_MECH_ATTR indicates that the mechanism attribute 389 referenced by the mech_attr parameter is unknown to the 390 implementation. 391 o GSS_S_FAILURE indicates that the request failed for some other 392 reason. 394 This function can be used to obtain human-readable descriptions of 395 GSS-API mechanism attributes. 397 3.4.4. New Major Status Values 399 A single new major status code is added for GSS_Display_mech_attr(): 400 o GSS_S_BAD_MECH_ATTR 401 roughly corresponding to GSS_S_BAD_MECH, but applicable to mechanism 402 attribute OIDs, rather than to mechanism OIDs. 404 For the C-bindings of the GSS-API [RFC2744] GSS_S_BAD_MECH_ATTR shall 405 have a routine error number of 19 (this is shifted to the left by 406 GSS_C_ROUTINE_ERROR_OFFSET). 408 3.4.5. C-Bindings 409 #define GSS_S_BAD_MECH_ATTR (19ul << GSS_C_ROUTINE_ERROR_OFFSET) 411 OM_uint32 gss_inquire_mechs_for_mech_attrs( 412 OM_uint32 *minor_status, 413 const gss_OID_set desired_mech_attrs, 414 gss_OID_set *mechs); 416 OM_uint32 gss_inquire_mech_attrs_for_mech( 417 OM_uint32 *minor_status, 418 const gss_OID mech, 419 gss_OID_set *mech_attrs); 421 OM_uint32 gss_display_mech_attr( 422 OM_uint32 *minor_status, 423 const gss_OID mech_attr, 424 gss_buffer_t name, 425 gss_buffer_t short_desc, 426 gss_buffer_t long_desc); 428 Figure 1 430 4. Requirements for Mechanism Designers 432 All future GSS-API mechanism specifications MUST: 433 o list the set of GSS-API mechanism attributes associated with them 435 5. IANA Considerations 437 The namsepace of programming language symbols with names beginning 438 with GSS_C_MA_* is reserved for allocation by IESG Protocol Action 439 (probably in the specifications of future GSS-API mechanisms). 441 6. Security considerations 443 This document specifies extensions to a security-related API. It 444 imposes new requirements on future GSS-API mechanisms, and the 445 specification of future protocols that use the GSS-API should make 446 reference to this document where applicable. The ability to inquire 447 about specific properties of mechanisms should improve security. 449 7. References 451 7.1. Normative References 453 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 454 Requirement Levels", BCP 14, RFC 2119, March 1997. 456 [RFC2743] Linn, J., "Generic Security Service Application Program 457 Interface Version 2, Update 1", RFC 2743, January 2000. 459 [RFC2744] Wray, J., "Generic Security Service API Version 2 : 460 C-bindings", RFC 2744, January 2000. 462 7.2. Informative References 464 [RFC1964] Linn, J., "The Kerberos Version 5 GSS-API Mechanism", 465 RFC 1964, June 1996. 467 [RFC2025] Adams, C., "The Simple Public-Key GSS-API Mechanism 468 (SPKM)", RFC 2025, October 1996. 470 [RFC2847] Eisler, M., "LIPKEY - A Low Infrastructure Public Key 471 Mechanism Using SPKM", RFC 2847, June 2000. 473 [RFC4178] Zhu, L., Leach, P., Jaganathan, K., and W. Ingersoll, "The 474 Simple and Protected Generic Security Service Application 475 Program Interface (GSS-API) Negotiation Mechanism", 476 RFC 4178, October 2005. 478 [RFC4251] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) 479 Protocol Architecture", RFC 4251, January 2006. 481 [RFC4462] Hutzelman, J., Salowey, J., Galbraith, J., and V. Welch, 482 "Generic Security Service Application Program Interface 483 (GSS-API) Authentication and Key Exchange for the Secure 484 Shell (SSH) Protocol", RFC 4462, May 2006. 486 Author's Address 488 Nicolas Williams 489 Sun Microsystems 490 5300 Riata Trace Ct 491 Austin, TX 78727 492 US 494 Email: Nicolas.Williams@sun.com 496 Full Copyright Statement 498 Copyright (C) The IETF Trust (2008). 500 This document is subject to the rights, licenses and restrictions 501 contained in BCP 78, and except as set forth therein, the authors 502 retain all their rights. 504 This document and the information contained herein are provided on an 505 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 506 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 507 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 508 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 509 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 510 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 512 Intellectual Property 514 The IETF takes no position regarding the validity or scope of any 515 Intellectual Property Rights or other rights that might be claimed to 516 pertain to the implementation or use of the technology described in 517 this document or the extent to which any license under such rights 518 might or might not be available; nor does it represent that it has 519 made any independent effort to identify any such rights. Information 520 on the procedures with respect to rights in RFC documents can be 521 found in BCP 78 and BCP 79. 523 Copies of IPR disclosures made to the IETF Secretariat and any 524 assurances of licenses to be made available, or the result of an 525 attempt made to obtain a general license or permission for the use of 526 such proprietary rights by implementers or users of this 527 specification can be obtained from the IETF on-line IPR repository at 528 http://www.ietf.org/ipr. 530 The IETF invites any interested party to bring to its attention any 531 copyrights, patents or patent applications, or other proprietary 532 rights that may cover technology that may be required to implement 533 this standard. Please address the information to the IETF at 534 ietf-ipr@ietf.org. 536 Acknowledgment 538 Funding for the RFC Editor function is provided by the IETF 539 Administrative Support Activity (IASA).