draft-ietf-kitten-extended-mech-inquiry-06.txt   rfc5587.txt 
NETWORK WORKING GROUP N. Williams Network Working Group N. Williams
Internet-Draft Sun Request for Comments: 5587 Sun
Intended status: Standards Track April 1, 2009
Expires: October 3, 2009
Extended Generic Security Service Mechanism Inquiry APIs Extended Generic Security Service Mechanism Inquiry APIs
draft-ietf-kitten-extended-mech-inquiry-06.txt
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Abstract
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months This document introduces new application programming interfaces
and may be updated, replaced, or obsoleted by other documents at any (APIs) to the Generic Security Services API (GSS-API) for extended
time. It is inappropriate to use Internet-Drafts as reference mechanism attribute inquiry. These interfaces are primarily intended
material or to cite them other than as "work in progress." to reduce instances of hardcoding of mechanism identifiers in GSS
applications.
The list of current Internet-Drafts can be accessed at These interfaces include mechanism attributes and attribute sets, a
http://www.ietf.org/ietf/1id-abstracts.txt. function for inquiring the attributes of a mechanism, a function for
indicating mechanisms that possess given attributes, and a function
for displaying mechanism attributes.
The list of Internet-Draft Shadow Directories can be accessed at Status of This Memo
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on October 3, 2009. This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
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Copyright (c) 2009 IETF Trust and the persons identified as the Copyright (c) 2009 IETF Trust and the persons identified as the
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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
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 Table of Contents
1. Conventions used in this document . . . . . . . . . . . . 3 1. Introduction ....................................................2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions Used in This Document ...............................2
3. New GSS-API Interfaces . . . . . . . . . . . . . . . . . . 3 3. New GSS-API Interfaces ..........................................3
3.1. Mechanism Attributes and Attribute Sets . . . . . . . . . 3 3.1. Mechanism Attributes and Attribute Sets ....................3
3.2. List of Known Mechanism Attributes . . . . . . . . . . . . 4 3.2. List of Known Mechanism Attributes .........................4
3.3. Mechanism Attribute Sets of Existing Mechs . . . . . . . . 6 3.3. Mechanism Attribute Sets of Existing Mechs .................6
3.4. New GSS-API Function Interfaces . . . . . . . . . . . . . 7 3.4. New GSS-API Function Interfaces ............................8
3.4.1. Mechanism Attribute Criticality . . . . . . . . . . . . . 8 3.4.1. Mechanism Attribute Criticality .....................8
3.4.2. GSS_Indicate_mechs_by_attr() . . . . . . . . . . . . . . . 8 3.4.2. GSS_Indicate_mechs_by_attrs() .......................9
3.4.3. GSS_Inquire_attrs_for_mech() . . . . . . . . . . . . . . . 9 3.4.3. GSS_Inquire_attrs_for_mech() .......................10
3.4.4. GSS_Display_mech_attr() . . . . . . . . . . . . . . . . . 9 3.4.4. GSS_Display_mech_attr() ............................10
3.4.5. New Major Status Values . . . . . . . . . . . . . . . . . 10 3.4.5. New Major Status Values ............................11
3.4.6. C-Bindings . . . . . . . . . . . . . . . . . . . . . . . . 10 3.4.6. C-Bindings .........................................11
4. Requirements for Mechanism Designers . . . . . . . . . . . 11 4. Requirements for Mechanism Designers ...........................13
5. IANA Considerations . . . . . . . . . . . . . . . . . . . 12 5. IANA Considerations ............................................13
6. Security considerations . . . . . . . . . . . . . . . . . 12 6. Security Considerations ........................................13
7. References . . . . . . . . . . . . . . . . . . . . . . . . 12 7. References .....................................................13
7.1. Normative References . . . . . . . . . . . . . . . . . . . 12 7.1. Normative References ......................................13
7.2. Informative References . . . . . . . . . . . . . . . . . . 12 7.2. Informative References ....................................14
Author's Address . . . . . . . . . . . . . . . . . . . . . 13 Appendix A. Typedefs and C Bindings ..................................15
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 1. Introduction
GSS-API [RFC2743] mechanisms have a number of properties that may be GSS-API [RFC2743] mechanisms have a number of properties that may be
of interest to applications. The lack of APIs for inquiring about of interest to applications. The lack of APIs for inquiring about
available mechanisms' properties has meant that many GSS-API available mechanisms' properties has meant that many GSS-API
applications must hardcode mechanism OIDs. Ongoing work may result applications must hardcode mechanism Object Identifiers (OIDs).
in a variety of new GSS-API mechanisms. Applications should not have Ongoing work may result in a variety of new GSS-API mechanisms.
to hardcode their OIDs. Applications should not have to hardcode their OIDs.
For example, the SSHv2 protocol [RFC4251] supports the use of GSS-API For example, the Secure Shell version 2 (SSHv2) protocol [RFC4251]
mechanisms for authentication [RFC4462], but it explicitly prohibits supports the use of GSS-API mechanisms for authentication [RFC4462]
the use of SPNEGO [RFC4178]. Future mechanisms that negotiate but explicitly prohibits the use of Simple and Protected GSS-API
Negotiation (SPNEGO) [RFC4178]. Future mechanisms that negotiate
mechanisms would have to be forbidden as well, but there is no way to mechanisms would have to be forbidden as well, but there is no way to
implement applications that inquire what mechanisms are available and implement applications that inquire what mechanisms are available and
then programmatically exclude mechanisms "like SPNEGO". then programmatically exclude mechanisms "like SPNEGO".
2. 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].
3. New GSS-API Interfaces 3. New GSS-API Interfaces
We introduce a new concept: that of mechanism attributes. By We introduce a new concept -- that of mechanism attributes. By
allowing applications to query the set of attributes associated with allowing applications to query the set of attributes associated with
individual mechanisms and to find out which mechanisms support a individual mechanisms and to find out which mechanisms support a
given set of attributes we allow applications to select mechanisms given set of attributes, we allow applications to select mechanisms
based on their attributes yet without having to hardcode mechanism based on their attributes without having to hardcode mechanism OIDs.
OIDs.
Section 3.1 describes the mechanism attributes concept. Sections Section 3.1 describes the mechanism attributes concept. Sections
3.4.2, 3.4.3 and 3.4.4 describe three new interfaces that deal in 3.4.2, 3.4.3, and 3.4.4 describe three new interfaces that deal in
mechanisms and attribute sets: mechanisms and attribute sets:
o GSS_Indicate_mechs_by_attrs() o GSS_Indicate_mechs_by_attrs()
o GSS_Inquire_attrs_for_mech() o GSS_Inquire_attrs_for_mech()
o GSS_Display_mech_attr() o GSS_Display_mech_attr()
3.1. Mechanism Attributes and Attribute Sets 3.1. Mechanism Attributes and Attribute Sets
An abstraction for the features provided by mechanisms and pseudo- An abstraction for the features provided by mechanisms and pseudo-
mechanisms is needed in order to facilitate the programmatic mechanisms is needed in order to facilitate the programmatic
selection of mechanisms. Pseudo-mechanisms are mechanisms which make selection of mechanisms. Pseudo-mechanisms are mechanisms that make
reference to other mechanisms in order to provide their services. reference to other mechanisms in order to provide their services.
For example, SPNEGO is a pseudo-mechanism, for without other For example, SPNEGO is a pseudo-mechanism, for without other
mechanisms SPNEGO is useless. mechanisms SPNEGO is useless.
Two data types are needed: one for individual mechanism attributes Two data types are needed: one for individual mechanism attributes
and one for mechanism attribute sets. To simplify the mechanism and one for mechanism attribute sets. To simplify the mechanism
attributes interfaces we reuse the 'OID' and 'OID set' data types and attribute interfaces, we reuse the 'OID' and 'OID set' data types and
model individual mechanism attribute types as OIDs. model individual mechanism attribute types as OIDs.
To this end we define an open namespace of mechanism attributes and To this end, we define an open namespace of mechanism attributes and
assign them arcs off of this OID: assign them arcs off of this OID:
<TBA by IANA> [1.3.6.1.5.5.13 appears to be available; see <1.3.6.1.5.5.13>
http://www.iana.org/assignments/smi-numbers]
Each mechanism has a set of mechanism attributes that it supports as Each mechanism has a set of mechanism attributes that it supports as
described in its specification. described in its specification.
3.2. List of Known Mechanism Attributes 3.2. List of Known Mechanism Attributes
+-------------------------+---------+-------------------------+ +-------------------------+---------+-------------------------+
| Mech Attr Name | OID Arc | Arc Name | | Mech Attr Name | OID Arc | Arc Name |
+-------------------------+---------+-------------------------+ +-------------------------+---------+-------------------------+
| GSS_C_MA_MECH_CONCRETE | (1) | concrete-mech | | GSS_C_MA_MECH_CONCRETE | (1) | concrete-mech |
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| GSS_C_MA_CONF_PROT | (18) | conf-prot | | GSS_C_MA_CONF_PROT | (18) | conf-prot |
| GSS_C_MA_MIC | (19) | mic | | GSS_C_MA_MIC | (19) | mic |
| GSS_C_MA_WRAP | (20) | wrap | | GSS_C_MA_WRAP | (20) | wrap |
| GSS_C_MA_PROT_READY | (21) | prot-ready | | GSS_C_MA_PROT_READY | (21) | prot-ready |
| GSS_C_MA_REPLAY_DET | (22) | replay-detection | | GSS_C_MA_REPLAY_DET | (22) | replay-detection |
| GSS_C_MA_OOS_DET | (23) | oos-detection | | GSS_C_MA_OOS_DET | (23) | oos-detection |
| GSS_C_MA_CBINDINGS | (24) | channel-bindings | | GSS_C_MA_CBINDINGS | (24) | channel-bindings |
| GSS_C_MA_PFS | (25) | pfs | | GSS_C_MA_PFS | (25) | pfs |
| GSS_C_MA_COMPRESS | (26) | compress | | GSS_C_MA_COMPRESS | (26) | compress |
| GSS_C_MA_CTX_TRANS | (27) | context-transfer | | GSS_C_MA_CTX_TRANS | (27) | context-transfer |
| <reserved> | (28..) | | | <reserved> | (28...) | |
+-------------------------+---------+-------------------------+ +-------------------------+---------+-------------------------+
Table 1 Table 1
+-------------------------+-----------------------------------------+ +-------------------------+-----------------------------------------+
| Mech Attr Name | Purpose | | Mech Attr Name | Purpose |
+-------------------------+-----------------------------------------+ +-------------------------+-----------------------------------------+
| GSS_C_MA_MECH_CONCRETE | Indicates that a mech is neither a | | GSS_C_MA_MECH_CONCRETE | Indicates that a mech is neither a |
| | pseudo- mechanism nor a composite | | | pseudo- mechanism nor a composite |
| | mechanism. | | | mechanism. |
| GSS_C_MA_MECH_PSEUDO | Indicates that a mech is a | | GSS_C_MA_MECH_PSEUDO | Indicates that a mech is a |
| | pseudo-mechanism. | | | pseudo-mechanism. |
| GSS_C_MA_MECH_COMPOSITE | Indicates that a mech is a composite of | | GSS_C_MA_MECH_COMPOSITE | Indicates that a mech is a composite of |
| | other mechanisms. This is reserved for | | | other mechanisms. This is reserved for |
skipping to change at page 5, line 26 skipping to change at page 5, line 21
| | pseudo-mechanism. | | | pseudo-mechanism. |
| GSS_C_MA_MECH_COMPOSITE | Indicates that a mech is a composite of | | GSS_C_MA_MECH_COMPOSITE | Indicates that a mech is a composite of |
| | other mechanisms. This is reserved for | | | other mechanisms. This is reserved for |
| | a specification of "stackable" | | | a specification of "stackable" |
| | pseudo-mechanisms. | | | pseudo-mechanisms. |
| GSS_C_MA_MECH_NEGO | Indicates that a mech negotiates other | | GSS_C_MA_MECH_NEGO | Indicates that a mech negotiates other |
| | mechs (e.g., SPNEGO has this | | | mechs (e.g., SPNEGO has this |
| | attribute). | | | attribute). |
| GSS_C_MA_MECH_GLUE | Indicates that the OID is not for a | | GSS_C_MA_MECH_GLUE | Indicates that the OID is not for a |
| | mechanism but for the GSS-API itself. | | | mechanism but for the GSS-API itself. |
| GSS_C_MA_NOT_MECH | Indicates that the OID is known, yet | | GSS_C_MA_NOT_MECH | Indicates that the OID is known, yet it |
| | also known not to be the OID of any | | | is also known not to be the OID of any |
| | GSS-API mechanism (or the GSS-API | | | GSS-API mechanism (or of the GSS-API |
| | itself). | | | itself). |
| GSS_C_MA_DEPRECATED | Indicates that a mech (or its OID) is | | GSS_C_MA_DEPRECATED | Indicates that a mech (or its OID) is |
| | deprecated and MUST NOT be used as a | | | deprecated and MUST NOT be used as a |
| | default mechanism. | | | default mechanism. |
| GSS_C_MA_NOT_DFLT_MECH | Indicates that a mech (or its OID) MUST | | GSS_C_MA_NOT_DFLT_MECH | Indicates that a mech (or its OID) MUST |
| | NOT be used as a default mechanism. | | | NOT be used as a default mechanism. |
| GSS_C_MA_ITOK_FRAMED | Indicates that the given mechanism's | | GSS_C_MA_ITOK_FRAMED | Indicates that the given mechanism's |
| | initial context tokens are properly | | | initial context tokens are properly |
| | framed as per-section 3.1 of rfc2743. | | | framed as per Section 3.1 of [RFC2743]. |
| GSS_C_MA_AUTH_INIT | Indicates support for authentication of | | GSS_C_MA_AUTH_INIT | Indicates support for authentication of |
| | initiator to acceptor. | | | initiator to acceptor. |
| GSS_C_MA_AUTH_TARG | Indicates support for authentication of | | GSS_C_MA_AUTH_TARG | Indicates support for authentication of |
| | acceptor to initiator. | | | acceptor to initiator. |
| GSS_C_MA_AUTH_INIT_INIT | Indicates support for "initial" | | GSS_C_MA_AUTH_INIT_INIT | Indicates support for "initial" |
| | authentication of initiator to | | | authentication of initiator to |
| | acceptor. "Initial authentication" | | | acceptor. "Initial authentication" |
| | refers to the use of passwords, or keys | | | refers to the use of passwords, or keys |
| | stored on tokens, for authentication. | | | stored on tokens, for authentication. |
| | Whether a mechanism supports initial | | | Whether a mechanism supports initial |
skipping to change at page 6, line 18 skipping to change at page 6, line 13
| | principal name. | | | principal name. |
| GSS_C_MA_AUTH_TARG_ANON | Indicates support for | | GSS_C_MA_AUTH_TARG_ANON | Indicates support for |
| | GSS_C_NT_ANONYMOUS as a target | | | GSS_C_NT_ANONYMOUS as a target |
| | principal name. | | | principal name. |
| GSS_C_MA_DELEG_CRED | Indicates support for credential | | GSS_C_MA_DELEG_CRED | Indicates support for credential |
| | delegation. | | | delegation. |
| GSS_C_MA_INTEG_PROT | Indicates support for per-message | | GSS_C_MA_INTEG_PROT | Indicates support for per-message |
| | integrity protection. | | | integrity protection. |
| GSS_C_MA_CONF_PROT | Indicates support for per-message | | GSS_C_MA_CONF_PROT | Indicates support for per-message |
| | confidentiality protection. | | | confidentiality protection. |
| GSS_C_MA_MIC | Indicates support for MIC tokens. | | GSS_C_MA_MIC | Indicates support for Message Integrity |
| | Code (MIC) tokens. |
| GSS_C_MA_WRAP | Indicates support for WRAP tokens. | | GSS_C_MA_WRAP | Indicates support for WRAP tokens. |
| GSS_C_MA_PROT_READY | Indicates support for per-message | | GSS_C_MA_PROT_READY | Indicates support for per-message |
| | protection prior to full context | | | protection prior to full context |
| | establishment. | | | establishment. |
| GSS_C_MA_REPLAY_DET | Indicates support for replay detection. | | GSS_C_MA_REPLAY_DET | Indicates support for replay detection. |
| GSS_C_MA_OOS_DET | Indicates support for out-of-sequence | | GSS_C_MA_OOS_DET | Indicates support for out-of-sequence |
| | detection. | | | detection. |
| GSS_C_MA_CBINDINGS | Indicates support for channel bindings. | | GSS_C_MA_CBINDINGS | Indicates support for channel bindings. |
| GSS_C_MA_PFS | Indicates support for Perfect Forward | | GSS_C_MA_PFS | Indicates support for Perfect Forward |
| | Security. | | | Security. |
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+-------------------------+-----------------------------------------+ +-------------------------+-----------------------------------------+
Table 2 Table 2
3.3. Mechanism Attribute Sets of Existing Mechs 3.3. Mechanism Attribute Sets of Existing Mechs
The Kerberos V mechanism [RFC1964] provides the following mechanism The Kerberos V mechanism [RFC1964] provides the following mechanism
attributes: attributes:
o GSS_C_MA_MECH_CONCRETE o GSS_C_MA_MECH_CONCRETE
o GSS_C_MA_ITOK_FRAMED o GSS_C_MA_ITOK_FRAMED
o GSS_C_MA_AUTH_INIT o GSS_C_MA_AUTH_INIT
o GSS_C_MA_AUTH_TARG o GSS_C_MA_AUTH_TARG
o GSS_C_MA_DELEG_CRED o GSS_C_MA_DELEG_CRED
o GSS_C_MA_INTEG_PROT o GSS_C_MA_INTEG_PROT
o GSS_C_MA_CONF_PROT o GSS_C_MA_CONF_PROT
o GSS_C_MA_MIC o GSS_C_MA_MIC
o GSS_C_MA_WRAP o GSS_C_MA_WRAP
o GSS_C_MA_PROT_READY o GSS_C_MA_PROT_READY
o GSS_C_MA_REPLAY_DET o GSS_C_MA_REPLAY_DET
o GSS_C_MA_OOS_DET o GSS_C_MA_OOS_DET
o GSS_C_MA_CBINDINGS o GSS_C_MA_CBINDINGS
o GSS_C_MA_CTX_TRANS (some implementations, using implementation- o GSS_C_MA_CTX_TRANS (some implementations, using implementation-
specific exported context token formats) specific exported context token formats)
The Kerberos V mechanism also has a deprecated OID which has the same The Kerberos V mechanism also has a deprecated OID that has the same
mechanism attributes as above, and GSS_C_MA_DEPRECATED. mechanism attributes as above as well as GSS_C_MA_DEPRECATED.
The mechanism attributes of the SPKM [RFC2025] family of mechanisms The mechanism attributes of the Simple Public-Key GSS-API Mechanism
will be provided in a separate document as SPKM is current being (SPKM) [RFC2025] family of mechanisms will be provided in a separate
reviewed for possibly significant changes due to problems in its document, as SPKM is currently being reviewed for possibly
specifications. significant changes due to problems in its specifications.
The LIPKEY mechanism [RFC2847] offers the following attributes: The Low Infrastructure Public Key (LIPKEY) mechanism [RFC2847] offers
the following attributes:
o GSS_C_MA_MECH_CONCRETE o GSS_C_MA_MECH_CONCRETE
o GSS_C_MA_ITOK_FRAMED o GSS_C_MA_ITOK_FRAMED
o GSS_C_MA_AUTH_INIT_INIT o GSS_C_MA_AUTH_INIT_INIT
o GSS_C_MA_AUTH_TARG (from SPKM-3) o GSS_C_MA_AUTH_TARG (from SPKM-3)
o GSS_C_MA_AUTH_TARG_ANON (from SPKM-3) o GSS_C_MA_AUTH_TARG_ANON (from SPKM-3)
o GSS_C_MA_INTEG_PROT o GSS_C_MA_INTEG_PROT
o GSS_C_MA_CONF_PROT o GSS_C_MA_CONF_PROT
o GSS_C_MA_REPLAY_DET o GSS_C_MA_REPLAY_DET
o GSS_C_MA_OOS_DET o GSS_C_MA_OOS_DET
o GSS_C_MA_CTX_TRANS (some implementations, using implementation- o GSS_C_MA_CTX_TRANS (some implementations, using implementation-
specific exported context token formats) specific exported context token formats)
(LIPKEY should also provide GSS_C_MA_CBINDINGS, but SPKM-3 (LIPKEY should also provide GSS_C_MA_CBINDINGS, but SPKM-3
requires clarifications on this point.) requires clarifications on this point.)
The SPNEGO mechanism [RFC4178] provides the following attributes: The SPNEGO mechanism [RFC4178] provides the following attributes:
o GSS_C_MA_MECH_NEGO o GSS_C_MA_MECH_NEGO
o GSS_C_MA_ITOK_FRAMED o GSS_C_MA_ITOK_FRAMED
All other mechanisms' attributes will be described elsewhere. All other mechanisms' attributes will be described elsewhere.
3.4. New GSS-API Function Interfaces 3.4. New GSS-API Function Interfaces
Several new interfaces are given by which, for example, GSS-API Several new interfaces are given by which, for example, GSS-API
applications may determine what features are provided by a given applications may determine what features are provided by a given
mechanism and what mechanisms provide what features. mechanism and what mechanisms provide what features.
skipping to change at page 7, line 49 skipping to change at page 8, line 23
All other mechanisms' attributes will be described elsewhere. All other mechanisms' attributes will be described elsewhere.
3.4. New GSS-API Function Interfaces 3.4. New GSS-API Function Interfaces
Several new interfaces are given by which, for example, GSS-API Several new interfaces are given by which, for example, GSS-API
applications may determine what features are provided by a given applications may determine what features are provided by a given
mechanism and what mechanisms provide what features. mechanism and what mechanisms provide what features.
These new interfaces are all OPTIONAL. These new interfaces are all OPTIONAL.
Applications should use GSS_Indicate_mechs_by_attr() instead of Applications should use GSS_Indicate_mechs_by_attrs() instead of
GSS_Indicate_mechs() wherever possible. GSS_Indicate_mechs() wherever possible.
Applications can use GSS_Indicate_mechs_by_attr() to determine what, Applications can use GSS_Indicate_mechs_by_attrs() to determine what,
if any, mechanisms provide a given set of features. 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_by_attrs() can also be used to indicate (as in
GSS_Indicate_mechs()) the set of available mechanisms of each type GSS_Indicate_mechs()) the set of available mechanisms of each type
(concrete, mechanism negotiation pseudo-mechanism, etc.). (concrete, mechanism negotiation pseudo-mechanism, etc.).
3.4.1. Mechanism Attribute Criticality 3.4.1. Mechanism Attribute Criticality
Mechanism attributes may be added at any time. Not only may Mechanism attributes may be added at any time. Not only may
attributes be added to the list of known mechanism attributes at any attributes be added to the list of known mechanism attributes at any
time, but the set of mechanism attributes supported by a mechanism time, but the set of mechanism attributes supported by a mechanism
can be changed at any time. can be changed at any time.
For example, new attributes might be added to reflect whether a For example, new attributes might be added to reflect whether a
mechanism's initiator must contact online infrastructure, and/or mechanism's initiator must contact an online infrastructure and/or
whether the acceptor must do so. In this example the Kerberos V whether the acceptor must do so. In this example, the Kerberos V
mechanism would gain a new attribute even though the mechanism itself mechanism would gain a new attribute even though the mechanism itself
is not modified. is not modified.
Applications making use of attributes not defined herein then would Applications making use of attributes not defined herein would then
have no way of knowing whether a GSS-API implementation and its have no way of knowing whether a GSS-API implementation and its
mechanisms know about new mechanism attributes. To address this mechanisms know about new mechanism attributes. To address this
problem GSS_Indicate_mechs_by_attr() and GSS_Indicate_mechs_by_attr() problem, GSS_Indicate_mechs_by_attrs() and
support a notion of critical mechanism attributes. Applications can GSS_Inquire_attrs_for_mech() support a notion of critical mechanism
search for mechanisms that understand mechanism attributes that are attributes. Applications can search for mechanisms that understand
critical to the application, and the application may ask what mechanism attributes that are critical to the application, and the
mechanism attributes are understood by a given mechanism. application may ask what mechanism attributes are understood by a
given mechanism.
3.4.2. GSS_Indicate_mechs_by_attr() 3.4.2. GSS_Indicate_mechs_by_attrs()
Inputs: Inputs:
o desired_mech_attrs SET OF OBJECT IDENTIFIER -- set of GSS_C_MA_* o desired_mech_attrs SET OF OBJECT IDENTIFIER -- set of GSS_C_MA_*
OIDs that the mechanisms indicated in the mechs output parameter OIDs that the mechanisms indicated in the mechs output parameter
MUST offer MUST offer.
o except_mech_attrs SET OF OBJECT IDENTIFIER -- set of GSS_C_MA_* o except_mech_attrs SET OF OBJECT IDENTIFIER -- set of GSS_C_MA_*
OIDs that the mechanisms indicated in the mechs output parameter OIDs that the mechanisms indicated in the mechs output parameter
MUST NOT offer MUST NOT offer.
o critical_mech_attrs SET OF OBJECT IDENTIFIER -- set of GSS_C_MA_* o critical_mech_attrs SET OF OBJECT IDENTIFIER -- set of GSS_C_MA_*
OIDs that the mechanisms indicated in the mechs output parameter OIDs that the mechanisms indicated in the mechs output parameter
MUST understand (i.e., mechs must know whether critical attributes MUST understand (i.e., mechs must know whether critical attributes
are or are not supported) are or are not supported).
Outputs: Outputs:
o major_status INTEGER o major_status INTEGER
o minor_status INTEGER o minor_status INTEGER
o mechs SET OF OBJECT IDENTIFIER -- set of mechanisms that support o mechs SET OF OBJECT IDENTIFIER -- set of mechanisms that support
the given desired_mech_attrs but not the except_mech_attrs, and the given desired_mech_attrs but not the except_mech_attrs, and
all of which understand the given critical_mech_attrs (the caller all of which understand the given critical_mech_attrs (the caller
must release this output with GSS_Release_oid_set()) must release this output with GSS_Release_oid_set()).
Return major_status codes: Return major_status codes:
o GSS_S_COMPLETE indicates success; the output mechs parameter MAY o GSS_S_COMPLETE indicates success; the output mechs parameter MAY
be the empty set (GSS_C_NO_OID_SET). be the empty set (GSS_C_NO_OID_SET).
o GSS_S_FAILURE indicates that the request failed for some other o GSS_S_FAILURE indicates that the request failed for some other
reason. reason.
GSS_Indicate_mechs_by_attrs() returns the set of OIDs corresponding GSS_Indicate_mechs_by_attrs() returns the set of OIDs corresponding
to mechanisms that offer at least the desired_mech_attrs but none of to mechanisms that offer at least the desired_mech_attrs but none of
the except_mech_attrs, and which understand all of the attributes the except_mech_attrs, and that understand all of the attributes
listed in critical_mech_attrs. listed in critical_mech_attrs.
When all three set of OID input parameters are the empty set this When all three sets of OID input parameters are the empty set, this
function acts as a version of GSS_indicate_mechs() that outputs the function acts as a version of GSS_indicate_mechs() that outputs the
set of all supported mechanisms. set of all supported mechanisms.
3.4.3. GSS_Inquire_attrs_for_mech() 3.4.3. GSS_Inquire_attrs_for_mech()
Inputs: Inputs:
o mech OBJECT IDENTIFIER -- mechanism OID o mech OBJECT IDENTIFIER -- mechanism OID
Outputs: Outputs:
o major_status INTEGER o major_status INTEGER
o minor_status INTEGER o minor_status INTEGER
o mech_attrs SET OF OBJECT IDENTIFIER -- set of mech_attrs OIDs o mech_attrs SET OF OBJECT IDENTIFIER -- set of mech_attrs OIDs
(GSS_C_MA_*) supported by the mechanism (the caller must release (GSS_C_MA_*) supported by the mechanism (the caller must release
this output with GSS_Release_oid_set()) this output with GSS_Release_oid_set()).
o known_mech_attrs SET OF OBJECT IDENTIFIER -- set of mech_attrs o known_mech_attrs SET OF OBJECT IDENTIFIER -- set of mech_attrs
OIDs known to the mechanism implementation (the caller must OIDs known to the mechanism implementation (the caller must
release this output with GSS_Release_oid_set()). release this output with GSS_Release_oid_set()).
Return major_status codes: Return major_status codes:
o GSS_S_COMPLETE indicates success; the output mech_attrs parameter o GSS_S_COMPLETE indicates success; the output mech_attrs parameter
MAY be the empty set (GSS_C_NO_OID_SET). MAY be the empty set (GSS_C_NO_OID_SET).
o GSS_S_BAD_MECH indicates that the mechanism named by the mech 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 parameter does not exist or that the mech is GSS_C_NO_OID and no
default mechanism could be determined. default mechanism could be determined.
o GSS_S_FAILURE indicates that the request failed for some other o GSS_S_FAILURE indicates that the request failed for some other
reason. reason.
GSS_Inquire_mech_attrs_for_mech() indicates the set of mechanism GSS_Inquire_attrs_for_mech() indicates the set of mechanism
attributes supported by a given mechanism. attributes supported by a given mechanism.
3.4.4. GSS_Display_mech_attr() 3.4.4. GSS_Display_mech_attr()
Inputs: Inputs:
o mech_attr OBJECT IDENTIFIER -- mechanism attribute OID o mech_attr OBJECT IDENTIFIER -- mechanism attribute OID
Outputs: Outputs:
o major_status INTEGER o major_status INTEGER
o minor_status INTEGER o minor_status INTEGER
o name OCTET STRING, -- name of mechanism attribute (e.g., o name OCTET STRING, -- name of mechanism attribute (e.g.,
GSS_C_MA_*) GSS_C_MA_*).
o short_desc OCTET STRING, -- a short description of the mechanism o short_desc OCTET STRING, -- a short description of the mechanism
attribute (the caller must release this output with attribute (the caller must release this output with
GSS_Release_buffer()) GSS_Release_buffer()).
o long_desc OCTET STRING -- a longer description of the mechanism o long_desc OCTET STRING -- a longer description of the mechanism
attribute (the caller must release this output with attribute (the caller must release this output with
GSS_Release_buffer()) GSS_Release_buffer()).
Return major_status codes: Return major_status codes:
o GSS_S_COMPLETE indicates success. o GSS_S_COMPLETE indicates success.
o GSS_S_BAD_MECH_ATTR indicates that the mechanism attribute o GSS_S_BAD_MECH_ATTR indicates that the mechanism attribute
referenced by the mech_attr parameter is unknown to the referenced by the mech_attr parameter is unknown to the
implementation. implementation.
o GSS_S_FAILURE indicates that the request failed for some other o GSS_S_FAILURE indicates that the request failed for some other
reason. reason.
This function can be used to obtain human-readable descriptions of This function can be used to obtain human-readable descriptions of
GSS-API mechanism attributes. GSS-API mechanism attributes.
3.4.5. New Major Status Values 3.4.5. New Major Status Values
A single new major status code is added for GSS_Display_mech_attr(): A single, new, major status code is added for
o GSS_S_BAD_MECH_ATTR GSS_Display_mech_attr():
roughly corresponding to GSS_S_BAD_MECH, but applicable to mechanism
attribute OIDs, rather than to mechanism OIDs.
For the C-bindings of the GSS-API [RFC2744] GSS_S_BAD_MECH_ATTR shall o GSS_S_BAD_MECH_ATTR,
have a routine error number of 19 (this is shifted to the left by
GSS_C_ROUTINE_ERROR_OFFSET). roughly corresponding to GSS_S_BAD_MECH but applicable to mechanism
attribute OIDs rather than to mechanism OIDs.
For the C-bindings of the GSS-API [RFC2744], 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).
3.4.6. C-Bindings 3.4.6. C-Bindings
Note that there is a bug in the C bindings of the GSS-APIv2u1 Note that there is a bug in the C bindings of the GSS-APIv2u1
[RFC2744] in that the C 'const' attribute is applied to types which [RFC2744] in that the C 'const' attribute is applied to types that
are pointer typedefs. This is a bug because this declares that the are pointer typedefs. This is a bug because it declares that the
pointer argument is 'const' rather than that the object pointed by it pointer argument is 'const' rather than that the object pointed by it
is const. To avoid this error we hereby define new typdefs which is const. To avoid this error, we hereby define new typedefs, which
include const properly: include const properly:
typedef const gss_buffer_desc * gss_const_buffer_t; typedef const gss_buffer_desc * gss_const_buffer_t;
typedef const struct gss_channel_bindings_struct * typedef const struct gss_channel_bindings_struct *
gss_const_channel_bindings_t; gss_const_channel_bindings_t;
typedef const <platform-specific> gss_const_ctx_id_t; typedef const <platform-specific> gss_const_ctx_id_t;
typedef const <platform-specific> gss_const_cred_id_t; typedef const <platform-specific> gss_const_cred_id_t;
typedef const <platform-specific> gss_const_name_t; typedef const <platform-specific> gss_const_name_t;
typedef const gss_OID_desc * gss_const_OID; typedef const gss_OID_desc * gss_const_OID;
typedef const gss_OID_set_desc * gss_const_OID_set; typedef const gss_OID_set_desc * gss_const_OID_set;
Figure 1: const typedefs Figure 1: const typedefs
Note that only gss_const_OID and gss_const_OID_set are used below. Note that only gss_const_OID and gss_const_OID_set are used below.
We include the other const typedefs for convenience since the C We include the other const typedefs for convenience since the C
bindings of the GSS-API do use const with pointer typedefs when it bindings of the GSS-API do use const with pointer typedefs when it
should often instead use the above typedefs instead. should often instead use the above typedefs instead.
#define GSS_S_BAD_MECH_ATTR (19ul << GSS_C_ROUTINE_ERROR_OFFSET) #define GSS_S_BAD_MECH_ATTR (19ul << GSS_C_ROUTINE_ERROR_OFFSET)
OM_uint32 gss_inquire_mechs_for_attrs( OM_uint32 gss_indicate_mechs_by_attrs(
OM_uint32 *minor_status, OM_uint32 *minor_status,
gss_const_OID_set desired_mech_attrs, gss_const_OID_set desired_mech_attrs,
gss_const_OID_set except_mech_attrs, gss_const_OID_set except_mech_attrs,
gss_const_OID_set critical_mech_attrs, gss_const_OID_set critical_mech_attrs,
gss_OID_set *mechs); gss_OID_set *mechs);
OM_uint32 gss_inquire_attrs_for_mech( OM_uint32 gss_inquire_attrs_for_mech(
OM_uint32 *minor_status, OM_uint32 *minor_status,
gss_const_OID mech, gss_const_OID mech,
gss_OID_set *mech_attrs, gss_OID_set *mech_attrs,
skipping to change at page 11, line 44 skipping to change at page 12, line 48
gss_const_OID mech_attr, gss_const_OID mech_attr,
gss_buffer_t name, gss_buffer_t name,
gss_buffer_t short_desc, gss_buffer_t short_desc,
gss_buffer_t long_desc); gss_buffer_t long_desc);
Figure 2: C bindings Figure 2: C bindings
Note that output buffers must be released via gss_release_buffer(). Note that output buffers must be released via gss_release_buffer().
Output OID sets must be released via gss_release_oid_set(). Output OID sets must be released via gss_release_oid_set().
Please see Appendix A for a full set of typedef fragments defined in
this document and the necessary code license.
4. Requirements for Mechanism Designers 4. Requirements for Mechanism Designers
All future GSS-API mechanism specifications MUST: All future GSS-API mechanism specifications MUST:
o list the set of GSS-API mechanism attributes associated with them
o list the set of GSS-API mechanism attributes associated with them.
5. IANA Considerations 5. IANA Considerations
The namsepace of programming language symbols with names beginning The namespace of programming-language symbols with names beginning
with GSS_C_MA_* is reserved for allocation by IESG Protocol Action. with GSS_C_MA_* is reserved for allocation by IETF Consensus. IANA
The IANA should allocate a base OID, as an arc of 1.3.6.1.5.5, for allocated a base OID, as an arc of 1.3.6.1.5.5, for the set of
the set of GSS_C_MA_* described herein, and it should register all of GSS_C_MA_* described herein, and registered all of the GSS_C_MA_*
the GSS_C_MA_* values described in Section 3.2 values described in Section 3.2.
6. Security considerations 6. Security Considerations
This document specifies extensions to a security-related API. It This document specifies extensions to a security-related API. It
imposes new requirements on future GSS-API mechanisms, and the imposes new requirements on future GSS-API mechanisms, and the
specification of future protocols that use the GSS-API should make specifications of future protocols that use the GSS-API should make
reference to this document where applicable. The ability to inquire reference to this document where applicable. The ability to inquire
about specific properties of mechanisms should improve security. about specific properties of mechanisms should improve security.
The semantics of each mechanism attribute may include a security The semantics of each mechanism attribute may include a security
component. component.
Application developers must understand that mechanism attributes may Application developers must understand that mechanism attributes may
be added at any time, both, to the set of known mechanism attributes, be added at any time -- both to the set of known mechanism attributes
as well as to existing mechanism's sets of supported mechanism as well as to existing mechanisms' sets of supported mechanism
attributes. Therefore application developers using the APIs attributes. Therefore, application developers using the APIs
described herein must understand what mechanism attributes their described herein must understand what mechanism attributes their
applications depend critically on, and must use the mechanism applications depend critically on, and must use the mechanism
attribute criticality features of these APIs. attribute criticality features of these APIs.
7. References 7. References
7.1. Normative References 7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
skipping to change at page 13, line 22 skipping to change at page 15, line 5
RFC 4178, October 2005. RFC 4178, October 2005.
[RFC4251] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) [RFC4251] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH)
Protocol Architecture", RFC 4251, January 2006. Protocol Architecture", RFC 4251, January 2006.
[RFC4462] Hutzelman, J., Salowey, J., Galbraith, J., and V. Welch, [RFC4462] Hutzelman, J., Salowey, J., Galbraith, J., and V. Welch,
"Generic Security Service Application Program Interface "Generic Security Service Application Program Interface
(GSS-API) Authentication and Key Exchange for the Secure (GSS-API) Authentication and Key Exchange for the Secure
Shell (SSH) Protocol", RFC 4462, May 2006. Shell (SSH) Protocol", RFC 4462, May 2006.
Appendix A. Typedefs and C Bindings
This appendix contains the full set of code fragments defined in this
document.
Copyright (c) 2009 IETF Trust and the persons identified as authors
of the code. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
- Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the
distribution.
- Neither the name of Internet Society, IETF or IETF Trust, nor the
names of specific contributors, may be used to endorse or promote
products derived from this software without specific prior written
permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
typedef const gss_buffer_desc * gss_const_buffer_t;
typedef const struct gss_channel_bindings_struct *
gss_const_channel_bindings_t;
typedef const <platform-specific> gss_const_ctx_id_t;
typedef const <platform-specific> gss_const_cred_id_t;
typedef const <platform-specific> gss_const_name_t;
typedef const gss_OID_desc * gss_const_OID;
typedef const gss_OID_set_desc * gss_const_OID_set;
#define GSS_S_BAD_MECH_ATTR (19ul << GSS_C_ROUTINE_ERROR_OFFSET)
OM_uint32 gss_indicate_mechs_by_attrs(
OM_uint32 *minor_status,
gss_const_OID_set desired_mech_attrs,
gss_const_OID_set except_mech_attrs,
gss_const_OID_set critical_mech_attrs,
gss_OID_set *mechs);
OM_uint32 gss_inquire_attrs_for_mech(
OM_uint32 *minor_status,
gss_const_OID mech,
gss_OID_set *mech_attrs,
gss_OID_set *known_mech_attrs);
OM_uint32 gss_display_mech_attr(
OM_uint32 *minor_status,
gss_const_OID mech_attr,
gss_buffer_t name,
gss_buffer_t short_desc,
gss_buffer_t long_desc);
Author's Address Author's Address
Nicolas Williams Nicolas Williams
Sun Microsystems Sun Microsystems
5300 Riata Trace Ct 5300 Riata Trace Ct
Austin, TX 78727 Austin, TX 78727
US US
Email: Nicolas.Williams@sun.com EMail: Nicolas.Williams@sun.com
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