NETWORK WORKING GROUP N. Williams Internet-Draft Sun Expires:
August 12, 2005 February 11,April 19, 2006 October 16, 2005 Extended Generic Security Service Mechanism Inquiry APIs draft-ietf-kitten-extended-mech-inquiry-00.txtdraft-ietf-kitten-extended-mech-inquiry-01.txt Status of this Memo By submitting this Internet-Draft, I certifyeach author represents that any applicable patent or other IPR claims of which I amhe or she is aware have been or will be disclosed, and any of which I becomehe or she becomes aware will be disclosed, in accordance with RFC 3668.Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts.Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on August 12, 2005.April 19, 2006. Copyright Notice Copyright (C) The Internet Society (2005). All Rights Reserved.Abstract This document introduces new application programming interfaces (APIs) to the Generic Security Services API (GSS-API) for extended mechanism attribute inquiry. These interfaces are primarily intended for use in mechanism composition, but also to reduce instances of hardcoding of mechanism identifiers in GSS applications. These interfaces include: mechanism attributes and attribute sets, a function for inquiring the attributes of a mechanism, a function for indicating mechanisms that posses given attributes, and a function for displaying mechanism attributes. Table of Contents 1. Conventions used in this document . . . . . . . . . . . . .3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . .3 3. New GSS-API Interfaces . . . . . . . . . . . . . . . . . . .3 3.13.1. Mechanism Attributes and Attribute Sets . . . . . . . . . .3 3.23.2. Determination of Attribute Sets of Composite Mechs . . . . .4 3.33.3. List of Known Mechanism Attributes . . . . . . . . . . . . .4 3.43.4. Mechanism Attribute Sets of Existing Mechs . . . . . . . . . 7 3.56 3.5. New GSS-API Function Interfaces . . . . . . . . . . . . . .8 18.104.22.168.1. GSS_Indicate_mechs_by_attr() . . . . . . . . . . . . . . . . 9 3.5.28 3.5.2. GSS_Inquire_attrs_for_mech() . . . . . . . . . . . . . . . .9 22.214.171.124.3. GSS_Display_mech_attr() . . . . . . . . . . . . . . . . . .10 126.96.36.199.4. New Major Status Values . . . . . . . . . . . . . . . . . .10 188.8.131.52.5. C-Bindings . . . . . . . . . . . . . . . . . . . . . . . . . 1110 4. Requirements for Mechanism Designers . . . . . . . . . . . .11 5. IANA Considerations . . . . . . . . . . . . . . . . . . . .11 6. Security considerations . . . . . . . . . . . . . . . . . . 1211 7. References . . . . . . . . . . . . . . . . . . . . . . . . .12 7.17.1. Normative . . . . . . . . . . . . . . . . . . . . . . . . .12 7.27.2. Normative . . . . . . . . . . . . . . . . . . . . . . . . .12 Author's Address . . . . . . . . . . . . . . . . . . . . . . 1213 Intellectual Property and Copyright Statements . . . . . . . 1314 1. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 2. Introduction 3. New GSS-API Interfaces GSS-API applications face, today, the problem of how to select from multiple GSS-API mechanisms that may be available. For example, applications that support mechanism negotiation directly often have to be careful not to use SPNEGO to avoid two-layer mechanism negotiation, but since SPNEGO may be indicated by GSS_Indicate_mechs() and since there's no way to know that a mechanism negotiates mechanisms other than to hardcode the OIDs of such mechanisms, such applications must hardcode the SPNEGO OID. This problem is likely to be exacerbated by the introduction of composite mechanisms. To address this problem we introduce a new concept: that of mechanism attributes. By allowing applications to query the set of attributes associated with individual mechanisms and to find out which mechanisms support a given set of attributes we allow applications to select mechanisms based on their attributes yet without having to hardcode mechanism OIDs. Section 3.1 describes the mechanism attributes concept. Sections 3.5.1, 3.5.2 and 3.5.3 describe three new interfaces that deal in mechanisms and attribute sets: o GSS_Indicate_mechs_by_attrs() o GSS_Inquire_attrs_for_mech() o GSS_Display_mech_attr() 3.13.1. Mechanism Attributes and Attribute Sets An abstraction for the features provided by pseudo-mechanisms is needed in order to facilitate the programmatic selection of mechanisms as well as for the programmatic composition of mechanisms. Two data types are needed: one for individual mechanism attributes and one for mechanism attribute sets. To simplify the mechanism attributes interfaces we reuse the 'OID' and 'OID set' data types and model individual mechanism attribute types as OIDs. To this end we define an open namespace of mechanism attributes and assign them arcs off of this OID: <TBD> [184.108.40.206.5.5.12 appears to be available, registration w/ IANA TBD] 3.23.2. Determination of Attribute Sets of Composite Mechs Each mechanism, composite or otherwise, has a set of mechanism attributes that it supports as specified. The mechanism attribute set of a composite mechanism is to be determined by the top-most stackable pseudo-mechanism of the composite according to its own attribute set and that of the remainder of the composite mechanism stack below it. It may well be that some composite mechanisms' attribute sets consist of the union of those of their every component, however this need not be the case and MUST NOT be assumed. Every stackable pseudo-mechanism's specification MUST specify the rules for determining the mechanism attribute set of mechanisms composed by it. 3.33.3. List of Known Mechanism Attributes +-------------------------+---------+--------------------------------++-------------------------+--------+--------------------------------+ | Mech Attr Name | OID Arc| Arc Name | +-------------------------+---------+--------------------------------+| | Arc | | +-------------------------+--------+--------------------------------+ | GSS_C_MA_MECH_CONCRETE | (1) | concrete-mech | | GSS_C_MA_MECH_STACKABLE | (2) | pseudo-mech | | GSS_C_MA_MECH_COMPOSITE | (3) | composite-mech | | GSS_C_MA_MECH_NEGO | (4) | mech-negotiation-mech | | GSS_C_MA_MECH_GLUE | (5) | mech-glue | | GSS_C_MA_NOT_MECH | (6) | not-mech | | GSS_C_MA_DEPRECATED | (7) | mech-deprecated | | GSS_C_MA_NOT_DFLT_MECH | (8) | mech-not-default | | GSS_C_MA_ITOK_FRAMED | (9) | initial-is-framed | | GSS_C_MA_AUTH_INIT | (10) | auth-init-princ | | GSS_C_MA_AUTH_TARG | (11) | auth-targ-princ | | GSS_C_MA_AUTH_INIT_INIT | (12) | auth-init-princ-initial | | GSS_C_MA_AUTH_TARG_INIT | (13) | auth-targ-princ-initial | | GSS_C_MA_AUTH_INIT_ANON | (14) | auth-init-princ-anon | | GSS_C_MA_AUTH_TARG_ANON | (15) | auth-targ-princ-anon | | GSS_C_MA_DELEG_CRED | (16) | deleg-cred | | GSS_C_MA_INTEG_PROT | (17) | integ-prot | | GSS_C_MA_CONF_PROT | (18) | conf-prot | | GSS_C_MA_MIC | (19) | mic | | GSS_C_MA_WRAP | (20) | wap | | GSS_C_MA_PROT_READY | (21) | prot-ready | | GSS_C_MA_REPLAY_DET | (22) | replay-detection | | GSS_C_MA_OOS_DET | (23) | oos-detection | | GSS_C_MA_CBINDINGS | (24) | channel-bindings | | GSS_C_MA_CBINDINGS_BIDI | (25) | channel-bindings-bidirectional | | GSS_C_MA_CBINDINGS_NEGO | (26) | channel-bindings-negotiate | | GSS_C_MA_PFS | (27) | pfs | | GSS_C_MA_COMPRESS | (28) | compress | | GSS_C_MA_CTX_TRANS | (29) | context-transfer | | <reserved> | (30..) | | +-------------------------+---------+--------------------------------++-------------------------+--------+--------------------------------+ Table 1 +---------------------------------+---------------------------------++-------------------------+-----------------------------------------+ | Mech Attr Name | Purpose | +---------------------------------+---------------------------------++-------------------------+-----------------------------------------+ | GSS_C_MA_MECH_CONCRETE | Indicates that a mech is neither a | | | neither apseudo- mechanism nor a composite | | | a compositemechanism. | | GSS_C_MA_MECH_STACKABLE | Indicates that a mech is a | | | pseudo-mechanism. | | GSS_C_MA_MECH_COMPOSITE | Indicates that a mech is a composite | | | compositemechanism. | | GSS_C_MA_MECH_NEGO | Indicates that a mech | | |negotiates other mechs (e.g.,| | | mechs (e.g., SPNEGO has this | | | attribute). | | GSS_C_MA_MECH_GLUE | Indicates that the OID is not for a | | | for amechanism but for the | | |GSS-API itself. | | GSS_C_MA_NOT_MECH | Indicates that the OID is known, yet | | | known, yetalso known not to be | | |the OID of any GSS-API| | | GSS-API mechanism (or the GSS-API | | | itself). | | GSS_C_MA_DEPRECATED | Indicates that a mech (or its OID) is | | | OID) isdeprecated and MUST NOT | | |be used as a | | | default mechanism. | | GSS_C_MA_NOT_DFLT_MECH | Indicates that a mech (or its OID) MUST | | | OID) MUSTNOT be used as a | | |default mechanism. | | GSS_C_MA_ITOK_FRAMED | Indicates that the given mechanism's | | | mechanism'sinitial context | | |tokens are properly framed as| | | framed as per-section 3.1 of rfc2743. | | GSS_C_MA_AUTH_INIT | Indicates support for | | |authentication of initiator to| | | initiator to acceptor. | | GSS_C_MA_AUTH_TARG | Indicates support for | | |authentication of acceptor to| | | acceptor to initiator. | | GSS_C_MA_AUTH_INIT_INIT | Indicates support for initial | | | authentication of initiator to | | | acceptor. | | GSS_C_MA_AUTH_TARG_INIT | Indicates support for initial | | | authentication of acceptor to | | | initiator. | | GSS_C_MA_AUTH_INIT_ANON | Indicates support for initiator | | | anonymity. | | GSS_C_MA_AUTH_TARG_ANON | Indicates support for acceptor | | | anonymity. | | GSS_C_MA_DELEG_CRED | Indicates support for credential | | | credentialdelegation. | | GSS_C_MA_INTEG_PROT | Indicates support for | | |per-message integrity| | | integrity protection. | | GSS_C_MA_CONF_PROT | Indicates support for | | |per-message confidentiality| | | confidentiality protection. | | GSS_C_MA_MIC | Indicates support for MIC | | |tokens. | | GSS_C_MA_WRAP | Indicates support for WRAP | | |tokens. | | GSS_C_MA_PROT_READY | Indicates support for per-message | | | per-messageprotection prior to full context | | | full contextestablishment. | | GSS_C_MA_REPLAY_DET | Indicates support for replay | | |detection. | | GSS_C_MA_OOS_DET | Indicates support for out-of-sequence | | | out-of-sequencedetection. | | GSS_C_MA_CBINDINGS | Indicates support for channel | | |bindings. | | GSS_C_MA_CBINDINGS_BIDI | Indicates that acceptors | | | unconditionally indicate to initiators | | | initiatorswhether their | | |channel bindings were matched| | | matched the acceptors', even when the | | | acceptor applications use | | | GSS_C_NO_CHANNEL_BINDINGS.. | | GSS_C_MA_CBINDINGS_NEGO | Indicates that the mech acts as a | | | asignal for application | | |support for and willingness to| | | willingness to use channel bindings. | | GSS_C_MA_PFS | Indicates support for Perfect Forward | | | ForwardSecurity. | | GSS_C_MA_COMPRESS | Indicates support for compression of | | | compression ofdata inputs to | | |GSS_Wrap(). | | GSS_C_MA_CTX_TRANS | Indicates support for security context | | | contextexport/import. | +---------------------------------+---------------------------------++-------------------------+-----------------------------------------+ Table 2 3.43.4. Mechanism Attribute Sets of Existing Mechs The Kerberos V mechanism [RFC1964] [CFX] provides the following mechanism attributes: o GSS_C_MA_MECH_CONCRETE o GSS_C_MA_ITOK_FRAMED o GSS_C_MA_AUTH_INIT o GSS_C_MA_AUTH_TARG o GSS_C_MA_DELEG_CRED o GSS_C_MA_INTEG_PROT o GSS_C_MA_CONF_PROT o GSS_C_MA_MIC o GSS_C_MA_WRAP o GSS_C_MA_PROT_READY o GSS_C_MA_REPLAY_DET o GSS_C_MA_OOS_DET o GSS_C_MA_CBINDINGS o GSS_C_MA_CTX_TRANS (some implementations, using implementation-specificimplementation- specific exported context token formats) The Kerberos V mechanism also has a deprecated OID which has the same mechanism attributes as above, and GSS_C_MA_DEPRECATED. [The mechanism attributes of the SPKM family of mechanisms will be provided in a separate document as SPKM is current being reviewed for possibly significant changes due to problems in its specifications.] The LIPKEY mechanism offers the following attributes: o GSS_C_MA_MECH_CONCRETE (should be stackable, but does not compose) o GSS_C_MA_ITOK_FRAMED o GSS_C_MA_AUTH_INIT_INIT o GSS_C_MA_AUTH_TARG (from SPKM-3) o GSS_C_MA_AUTH_TARG_ANON (from SPKM-3) o GSS_C_MA_INTEG_PROT o GSS_C_MA_CONF_PROT o GSS_C_MA_REPLAY_DET o GSS_C_MA_OOS_DET o GSS_C_MA_CTX_TRANS (some implementations, using implementation-specificimplementation- specific exported context token formats) (LIPKEY should also provide GSS_C_MA_CBINDINGS, but SPKM-3 requires clarifications on this point.) The SPNEGO mechanism [SPNEGO] provides the following attributes: o GSS_C_MA_MECH_NEGO o GSS_C_MA_ITOK_FRAMED The attributes of mechanisms negotiated by SPNEGO are not modified by the use of SPNEGO. All other mechanisms' attributes will be described elsewhere. 3.53.5. New GSS-API Function Interfaces Several new interfaces are given by which, for example, GSS-API applications may determine what features are provided by a given mechanism, what mechanisms provide what features and what compositions are legal. These new interfaces are all OPTIONAL. In order to preserve backwards compatibility with applications that do not use the new interfaces GSS_Indicate_mechs() MUST NOT indicate support for any stackable pseduo-mechanisms. GSS_Indicate_mechs() MAY indicate support for some, all or none of the available composite mechanisms; which composite mechanisms, if any, are indicated through GSS_Indicate_mechs() SHOULD be configurable. GSS_Acquire_cred() and GSS_Add_cred() MUST NOT create credentials for composite mechanisms not explicitly requested or, if no desired mechanism or mechanisms are given, for composite mechanisms not indicated by GSS_Indicate_mechs(). Applications SHOULD use GSS_Indicate_mechs_by_attr() instead of GSS_Indicate_mechs() wherever possible. Applications can use GSS_Indicate_mechs_by_attr() to determine what, if any, mechanisms provide a given set of features. GSS_Indicate_mechs_by_attr() can also be used to indicate (as in GSS_Indicate_mechs()) the set of available mechanisms of each type (concrete, mechanism negotiation pseudo-mechanism, stackable pseudo-mechanismpseudo- mechanism and composite mechanisms). Applications may use GSS_Inquire_attrs_for_mech() to test whether a given composite mechanism is available and the set of features that it offers. 220.127.116.11.1. GSS_Indicate_mechs_by_attr() Inputs: o desired_mech_attrs SET OF OBJECT IDENTIFIER -- set of GSS_C_MA_* OIDs that the mechanisms indicated in the mechs output parameter MUST offer. o except_mech_attrs SET OF OBJECT IDENTIFIER -- set of GSS_C_MA_* OIDs that the mechanisms indicated in the mechs output parameter MUST NOT offer. Outputs: o major_status INTEGER, o minor_status INTEGER, o mechs SET OF OBJECT IDENTIFIER -- set of mechanisms that support -- the desired_mech_attrs but not the except_mech_attrs. Return major_status codes: o GSS_S_COMPLETE indicates success; the output mechs parameter MAY be the empty set (GSS_C_NO_OID_SET). o GSS_BAD_MECH_ATTR indicates that at least one mechanism attribute OID in desired_mech_attrs or except_mech_attrs is unknown to the implementation. o GSS_S_FAILURE indicates that the request failed for some other reason. GSS_Indicate_mechs_by_mech_attrs() returns the set of mechanism OIDs that offer at least the desired_mech_attrs but none of the except_mech_attrs. When desired_mech_attrs and except_mech_attrs are the empty set this function acts as a version of GSS_indicate_mechs() that outputs the set of all supported mechanisms of all types. By setting the desired_mechs input parameter to a set of a single GSS_C_MA_MECH* feature applications can obtain the list of all supported mechanisms of a given type (concrete, stackable, etc...). 18.104.22.168.2. GSS_Inquire_attrs_for_mech() Inputs: o mech OBJECT IDENTIFIER -- mechanism OID Outputs: o major_status INTEGER, o minor_status INTEGER, o mech_attrs SET OF OBJECT IDENTIFIER -- set of mech_attrs OIDs (GSS_C_MA_*) Return major_status codes: o GSS_S_COMPLETE indicates success; the output mech_attrs parameter MAY be the empty set (GSS_C_NO_OID_SET). o GSS_S_BAD_MECH indicates that the mechanism named by the mech parameter does not exist or that mech is GSS_C_NO_OID and no default mechanism could be determined. o GSS_S_FAILURE indicates that the request failed for some other reason. GSS_Inquire_mech_attrs_for_mech() indicates the set of mechanism attributes supported by a given mechanism. Because the mechanism attribute sets of composite mechanisms need not be the union of their components', when called to obtain the feature set of a composite mechanism GSS_Inquire_mech_attrs_for_mech() obtains it by querying the mechanism at the top of the stack. See Section 3.1. 22.214.171.124.3. GSS_Display_mech_attr() Inputs: o mech_attr OBJECT IDENTIFIER -- mechanism attribute OID Outputs: o major_status INTEGER, o minor_status INTEGER, o name OCTET STRING, -- name of mechanism attribute (e.g., GSS_C_MA_*) o short_desc OCTET STRING, -- a short description of the mechanism attribute o long_desc OCTET STRING -- a longer description of the mechanism attribute Return major_status codes: o GSS_S_COMPLETE indicates success. o GSS_S_BAD_MECH_ATTR indicates that the mechanism attribute referenced by the mech_attr parameter is unknown to the implementation. o GSS_S_FAILURE indicates that the request failed for some other reason. This function can be used to obtain human-readable descriptions of GSS-API mechanism attributes. 126.96.36.199.4. New Major Status Values A single new major status code is added for GSS_Display_mech_attr(): o GSS_S_BAD_MECH_ATTR roughly corresponding to GSS_S_BAD_MECH, but applicable to mechanism attribute OIDs, rather than to mechanism OIDs. For the C-bindings GSS_S_BAD_MECH_ATTR shall have a routine error number of 19 (this is shifted to the left by GSS_C_ROUTINE_ERROR_OFFSET). 188.8.131.52.5. C-Bindings #define GSS_S_BAD_MECH_ATTR (19ul << GSS_C_ROUTINE_ERROR_OFFSET) OM_uint32 gss_inquire_mechs_for_mech_attrs( OM_uint32 *minor_status, const gss_OID_set desired_mech_attrs, gss_OID_set *mechs); OM_uint32 gss_inquire_mech_attrs_for_mech( OM_uint32 *minor_status, const gss_OID mech, gss_OID_set *mech_attrs); OM_uint32 gss_display_mech_attr( OM_uint32 *minor_status, const gss_OID mech_attr, gss_buffer_t name, gss_buffer_t short_desc, gss_buffer_t long_desc); Figure 1 4. Requirements for Mechanism Designers Stackable pseudo-mechanisms specifications MUST: o list the set of GSS-API mechanism attributes associated with them o list their initial mechanism composition rules o specify a mechanism for updating their mechanism composition rules All other mechanism specifications MUST: o list the set of GSS-API mechanism attributes associated with them 5. IANA Considerations The namsepace of programming language symbols with names beginning with GSS_C_MA_* is reserved for allocation by the IANA. Allocation of arcs in the namespace of OIDs relative to the base mechanism attribute OID specified in Section 3.1 is reserved to the IANA. 6. Security considerations ... 7. References 7.17.1. Normative [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2743] Linn, J., "Generic Security Service Application Program Interface Version 2, Update 1", RFC 2743, January 2000. [RFC2744] Wray, J., "Generic Security Service API Version 2 : C-bindings", RFC 2744, January 2000. 7.27.2. Normative [RFC1964] Linn, J., "The Kerberos Version 5 GSS-API Mechanism", RFC 1964, June 1996. [RFC2478] Baize, E. and D. Pinkas, "The Simple and Protected GSS-API Negotiation Mechanism", RFC 2478, December 1998. Author's Address Nicolas Williams Sun Microsystems 5300 Riata Trace Ct Austin, TX 78727 US EMail:Email: Nicolas.Williams@sun.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at firstname.lastname@example.org. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society.