NFSv4                                                         W. Adamson
Internet-Draft                                                    NetApp
Intended status: Standards Track                             N. Williams
Expires: April 20, August 7, 2014                                     Cryptonector
                                                        October 17, 2013
                                                       February 03, 2014

             Remote Procedure Call (RPC) Security Version 3
                  draft-ietf-nfsv4-rpcsec-gssv3-06.txt
                  draft-ietf-nfsv4-rpcsec-gssv3-07.txt

Abstract

   This document specifies version 3 of the Remote Procedure Call (RPC)
   security protocol (RPCSEC_GSS).  This protocol provides for compound
   authentication of client hosts and users to server (constructed by
   generic composition), security label assertions for multi-level and
   type enforcement, structured privilege assertions, and channel
   bindings.

Requirements Language

   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 RFC 2119 [1].

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on April 20, August 7, 2014.

Copyright Notice

   Copyright (c) 2013 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . and Motivation  . . . . . . . . . . . . . . . . .  3
     1.1.  Applications of
   2.  The RPCSEC_GSSv3 Protocol  . . . . . . . . . . . . . . .  4
   2.  The RPCSEC_GSSv3 Protocol  . . . . .  4
     2.1.  Compatibility with RPCSEC_GSSv2  . . . . . . . . . . . . .  5
     2.1.
     2.2.  New auth_stat Values . . . . . . . . REPLY verifier . . . . . . . . . . .  9
     2.2.  RPC Message Credential and Verifier . . . . . . . . .  5
     2.3.  New Version Number . . 10
     2.3.  Control Messages . . . . . . . . . . . . . . . . . .  5
     2.4.  New Control Procedures . . . 10
       2.3.1.  Create Request . . . . . . . . . . . . . . .  7
       2.4.1.  New Control Procedure - RPCSEC_GSS_CREATE  . . . . . 11
       2.3.2.  Destruction Request .  8
       2.4.2.  New Control Procedure - RPCSEC_GSS_LIST  . . . . . . . 14
     2.5.  Extensibility  . . . . . . . . . 15
       2.3.3.  List Request . . . . . . . . . . . . . 15
     2.6.  New auth_stat Values . . . . . . . . 15
       2.3.4.  Extensibility . . . . . . . . . . . 15
   3.  Version Negotiation  . . . . . . . . . 16
     2.4.  Data Messages . . . . . . . . . . . . 16
   4.  Operational Recommendation for Deployment  . . . . . . . . . . 16
   3.
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 17
   4. 16
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 18
   5. 17
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
     5.1. 17
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 18
     5.2. 17
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 19 18
   Appendix A.  Acknowledgments . . . . . . . . . . . . . . . . . . . 19 18
   Appendix B.  RFC Editor Notes  . . . . . . . . . . . . . . . . . . 19
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19

1.  Introduction and Motivation

   The original RPCSEC_GSS protocol [2] provided for authentication of
   RPC clients and servers to each other using the Generic Security
   Services Application Programming Interface (GSS-API) [3].  The second
   version of RPCSEC_GSS [4] added support for channel bindings [5].

   We find that GSS-API mechanisms are insufficient for communicating
   certain aspects of a client's authority to a server.  The GSS-API and its
   mechanisms certainly could be extended to address this shortcoming,
   but it seems be far simpler to address it at the application layer,
   namely, in this case, RPCSEC_GSS.

   The motivation for RPCSEC_GSSv3 is to add support for labeled
   security and server-side copy for NFSv4 NFSv4.

   Labeled NFS (see [6] and [9]).  Both of
   these features require assertions Section 8 of authority from [6]) uses the client.

   Assertions need to be verified.  One party that can verify an
   assertion is subject label provided by
   the client host, which can authenticate via the RPCSEC_GSSv3 layer to enforce MAC access to
   objects owned by the server
   using its own credentials.  We can also require users to verify an
   assertion as well.  This calls for compound authentication.

   Because enable server guest mode or full mode
   labeled NFS.

   A traditional inter-server file copy entails the design of RPCSEC_GSSv3 relies on either RPCSEC_GSS
   version 1 (though version 2 can be used) user gaining access
   to do the actual GSS-API
   security context establishment, we add support for channel binding so
   that implementors who have implemented RPCSEC_GSS version 1 but not
   version 2 can provide a (simplified) channel binding implementation
   using RPCSEC_GSSv3.

   We therefore describe file on the source, reading it, and writing it to a new version file on the
   destination.  In secure NFSv4 inter-server server-side copy (see
   Section 3.4.1 of RPCSEC_GSS that allows for [6]), the
   following client-side user first secures access to both source
   and destination files, and then uses RPCSEC_GSSv3 compound
   authentication and structured privileges to authorize the destination
   to copy the file from the source on behalf of the user.

   We therefore describe RPCSEC_GSS version 3 (RPCSEC_GSSv3).
   RPCSEC_GSSv3 is the same as RPCSEC_GSSv2 [4], except that the
   following assertions of authority: authority have been added.

   o  Security labels for multi-level, type enforcement, and other
      labeled security models.  See [9], [10], [11], [12], [6] and [9]. [12].

   o  Application-specific structured privileges.  For an example see
      server-side copy [6].

   o  Compound authentication of the client host and user to the server
      done by binding two RPCSEC_GSS handles.  For an example see
      server-side copy [6].

   o  Simplified channel binding.

   Assertions of labels and privileges are evaluated by the server,
   which may then map the asserted values to other values, all according
   to server-side policy.

   We add an option for enumerating server supported label format
   specifiers (LFS).  The LFS and Label Format Registry are described in
   detail in [13].

   This document contains the External Data Representation (XDR) ([7])
   definitions for the RPCSEC_GSSv3 protocol.  The XDR description is
   provided in this document in a way that makes it simple for the
   reader to extract into ready to compile form.  The reader can feed
   this document in the following shell script to produce the machine
   readable XDR description of RPCSEC_GSSv3:

   <CODE BEGINS>

   #!/bin/sh
   grep "^  *///" | sed 's?^  */// ??' | sed 's?^  *///$??'

   <CODE ENDS>

   I.e. if the above script is stored in a file called "extract.sh", and
   this document is in a file called "spec.txt", then the reader can do:

   <CODE BEGINS>

    sh extract.sh < spec.txt > rpcsec_gss_v3.x

   <CODE ENDS>

   The effect of the script is to remove leading white space from each
   line, plus a sentinel sequence of "///".

2.  The RPCSEC_GSSv3 Protocol

   RPCSEC_GSSv3 is the same as RPCSEC_GSSv2 [4], except that support for
   assertions has been added.  The entire RPCSEC_GSSv3 protocol is not
   presented.  Instead the differences between RPCSEC_GSSv3 and
   RPCSEC_GSSv2 are shown.

   RPCSEC_GSSv3 is patterned as follows:

   o  A client uses an existing RPCSEC_GSSv1 (or RPCSEC_GSSv2) RPCSEC_GSSv3 context handle to protect
      RPCSEC_GSSv3 exchanges (this exchanges, this will be termed the "parent" handle) handle.
      [[Comment.1: CAN A CHILD handle be used as a parent? --AA]]

   o  The server issues a "child" RPCSEC_GSSv3 handle in the
      RPCSEC_GSS_CREATE response which uses the underlying GSS-API
      security context of the parent handle in all subsequent exchanges
      that uses the child handle.

   o

2.1.  Compatibility with RPCSEC_GSSv2

   The child handle, however, has its own sequence number space
      distinct from that of the parent.

   [[Comment.1: I removed the "child has a window distinct from that functionality of
   the parent" because RFC2203 states: " In a successful response, the
   seq_window field RPCSEC_GSSv2 [4] is set to the sequence window length fully supported by
   RPCSEC_GSSv3.

2.2.  New REPLY verifier

   The RPCSEC_GSSv3 child handle uses the server for this context.  This window specifies same GSS context as the maximum
   number of client requests that may be outstanding for this context."
   If we want parent
   handle.  Since a distinct window, we will need to add that to child and parent RPCSEC_GSSv3 handle could have the
   rpc_gss3_create_res so that
   same RPCSEC_GSS sequence numbers, and the server can set it.  I see no point - verifier of RPCSEC_GSS
   replies computes a MIC on just use the parent window. --AA]]

   [[Comment.2: RFC2203 states that when data integrity is used, the
   seq_num sequence number, this provides
   opportunities for man in the rpc_gss_data_t must be middle attacks.

   This is easily addressed: RPCSEC_GSS version 3 MUST change the same as in
   verifier of the credential.
   This means that using data integrity with GSS3 context's can not
   simply construct it reply to compute the verifier using the parent context exact same
   input as the seq_num must be
   from the GSS3 context. --AA]]

   This means that RPCSEC_GSSv3 depends on an existing parent
   RPCSEC_GSSv1 or RPCSEC_GSSv2 context is used for actual GSS-API security
   context establishment.  This keeps the specification verifier of RPCSEC_GSSv3
   simple by avoiding the need to duplicate request, except for the core functionality of
   RPCSEC_GSS version 1.  This also means that an RPCSEC_GSSv3 context
   MUST be destroyed prior
   mtype change from CALL to it's parent context being destroyed.

   [[Comment.3: Destruction of the parent context => first destroy child
   handle.  IOW fail REPLY:

     unsigned int xid;
     msg_type mtype;    /* set to REPLY */
     unsigned int rpcvers;
     unsigned int prog;
     unsigned int vers;
     unsigned int proc;
     opaque_auth  cred; /* captures the RPCSEC_GSS_DESTROY of parent with new
   RPCSEC_GSS3_CONTEXT_EXISTS error code OR upon RPCSEC_GSS handle */

2.3.  New Version Number

   <CODE BEGINS>

      ///  /*
      ///   * Copyright (c) 2013 IETF Trust and the destruction of persons
      ///   * identified as the
   parent context destroy any associated RPCSEC_GSSv3 contexts OR.....
   --AA]]

1.1.  Applications of RPCSEC_GSSv3 document authors. All rights
      ///   * reserved.
      ///   *
      ///   * The common uses of RPCSEC_GSSv3, particularly for NFSv4 [6], are
   expected to be:

   a.  labeled security: client-side process label assertion [+
       privilege assertion] + compound client host & user
       authentication;

   b.  inter-server server-side copy: compound client host & user
       authentication [+ critical structured privilege assertions]

   Labeled NFS (see Section 8 of [6]) uses the subject label provided by
   the client via the RPCSEC_GSSv3 layer to enforce MAC access to
   objects owned by the server to enable server guest mode or full mode
   labeled NFS.

   [[Comment.4: check that this language states what NFSv4.2 labeled NFS
   problem we are really solving. (setting labels on the server) --AA]]

   A traditional inter-server file copy entails the user gaining access
   to a file on the source, reading it, and writing it to a file on the
   destination.  In secure NFSv4 inter-server server-side copy (see
   Section 3.4.1 of [6]), the user first secures access to both source
   and destination files, and then uses RPCSEC_GSSv3 compound
   authentication and structured privileges to authorize the destination
   to copy the file from the source on behalf of the user.

2.  The RPCSEC_GSSv3 Protocol

   This document contains the External Data Representation (XDR) ([7])
   definitions for the RPCSEC_GSSv3 protocol.

   The XDR description is provided in this document in a way that makes
   it simple for the reader to extract into ready to compile form.  The
   reader can feed this document in the following shell script to
   produce the machine readable XDR description of RPCSEC_GSSv3:

   #!/bin/sh
   grep "^  *///" | sed 's?^  */// ??' | sed 's?^  *///$??'

   I.e. if the above script is stored in a file called "extract.sh", and
   this document is in a file called "spec.txt", then the reader can do:

    sh extract.sh < spec.txt > rpcsec_gss_v3.x

   The effect of the script is to remove leading white space from each
   line, plus a sentinel sequence of "///".

   The XDR description, with the sentinel sequence follows:

      ///  /*
      ///   * Copyright (c) 2013 IETF Trust and the persons
      ///   * identified as the document authors. All rights
      ///   * reserved.
      ///   *
      ///   * The document authors are identified in [RFC2203],
      ///   * [RFC5403], and [RFCxxxx].
      ///   *
      ///   * Redistribution and use in source and binary forms,
      ///   * with or without modification, are permitted
      ///   * provided that the following conditions are met:
      ///   *
      ///   * o Redistributions of source code must retain the above
      ///   *   copyright notice, this list of conditions and the
      ///   *   following disclaimer.
      ///   *
      ///   * o 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.
      ///   *
      ///   * o 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 "AS IS" AND ANY EXPRESS OR IMPLIED
      ///   *   WARRANTIES, INCLUDING, BUT NOT 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.
      ///   */
      ///
      ///  /*
      ///   * This code was derived from [RFC2203]. Please
      ///   * reproduce this note if possible.
      ///   */
      ///
      ///  /*
      ///   * rpcsec_gss_v3.x
      ///   */
      ///
      ///  enum rpc_gss_service_t {
      ///          /* Note: the enumerated value for 0 is reserved. */
      ///          rpc_gss_svc_none         = 1,
      ///          rpc_gss_svc_integrity    = 2,
      ///          rpc_gss_svc_privacy      = 3,
      ///          rpc_gss_svc_channel_prot = 4
      ///  };
      ///
      ///  enum rpc_gss_proc_t {
      ///           RPCSEC_GSS_DATA          = 0,
      ///           RPCSEC_GSS_INIT          = 1,
      ///           RPCSEC_GSS_CONTINUE_INIT = 2,
      ///           RPCSEC_GSS_DESTROY       = 3,
      ///           RPCSEC_GSS_BIND_CHANNEL  = 4
      ///  };
      ///
      ///  struct rpc_gss_cred_vers_1_t {
      ///          rpc_gss_proc_t    gss_proc; /* control procedure */
      ///          unsigned int      seq_num;  /* sequence number */
      ///          rpc_gss_service_t service;  /* service used */
      ///          opaque            handle<>; /* context handle */
      ///  };
      ///
      ///  enum rpc_gss3_proc_t {
      ///          RPCSEC_GSS3_DATA = 0,
      ///          RPCSEC_GSS3_LIST = 5,
      ///          RPCSEC_GSS3_CREATE = 6,
      ///          RPCSEC_GSS3_DESTROY = 7
      ///  };
      ///
      ///  struct rpc_gss_cred_vers_3_t {
      ///          rpc_gss3_proc_t         gss_proc;
      ///          unsigned int            seq_num;
      ///          rpc_gss_service_t       service;
      ///          opaque                  handle<>;
      ///  };
      ///
      ///  const RPCSEC_GSS_VERS_1 = 1;
      ///  const RPCSEC_GSS_VERS_2 = 2;
      ///  const RPCSEC_GSS_VERS_3 = 3; /* new */
      ///
      ///  union rpc_gss_cred_t switch (unsigned int rgc_version) {
      ///  case RPCSEC_GSS_VERS_1:
      ///  case RPCSEC_GSS_VERS_2:

      ///          rpc_gss_cred_vers_1_t rgc_cred_v1;
      ///  case RPCSEC_GSS_VERS_3: /* new */
      ///          rpc_gss_cred_vers_3_t rgc_cred_v3;
      ///  };
      ///
      ///  const MAXSEQ = 0x80000000;
      ///
      ///  struct rpc_gss3_gss_binding {
      ///          unsigned int    vers;
      ///          opaque          handle<>;
      ///          opaque          nonce<>;
      ///          opaque          mic<>; document authors are identified in [RFC2203],
      ///  };   * [RFC5403], and [RFCxxxx].
      ///   *
      ///  typedef opaque rpc_gss3_chan_binding<>;   * Redistribution and use in source and binary forms,
      ///   * with or without modification, are permitted
      ///  struct rpc_gss3_lfs {   * provided that the following conditions are met:
      ///          unsigned int lfs_id;   *
      ///          unsigned int pi_id;   * o Redistributions of source code must retain the above
      ///  };   *   copyright notice, this list of conditions and the
      ///   *   following disclaimer.
      ///  struct rpc_gss3_label {   *
      ///          rpc_gss3_lfs    lfs;   * o Redistributions in binary form must reproduce the
      ///          opaque          label<>;   *   above copyright notice, this list of
      ///  };   *   conditions and the following disclaimer in
      ///   *   the documentation and/or other materials
      ///  struct rpc_gss3_privs {   *   provided with the distribution.
      ///          string          name; /* human readable */   *
      ///          opaque          privilege<>;   * o 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
      ///  enum rpc_gss3_assertion_type {   *   software without specific prior written permission.
      ///          LABEL = 0,   *
      ///          PRIVS = 1   *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS
      ///  };   *   AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
      ///   *   WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
      ///  union rpc_gss3_assertion_u   *   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
      ///        switch (rpc_gss3_assertion_type atype) {   *   FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
      ///  case LABEL:   *   EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
      ///          rpc_gss3_label  label;   *   LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
      ///  case PRIVS:   *   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
      ///          rpc_gss3_privs  privs;   *   NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
      ///  default:   *   SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
      ///          opaque          ext<>;   *   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
      ///  };   *   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
      ///   *   OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
      ///  struct rpc_gss3_assertion {   *   IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
      ///          bool                    critical;   *   ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
      ///          rpc_gss3_assertion_u    assertion;   */
      ///  };
      ///  /*
      ///  struct rpc_gss3_create_args {   * This code was derived from [RFC2203]. Please
      ///          rpc_gss3_gss_binding    *compound_binding;   * reproduce this note if possible.
      ///          rpc_gss3_chan_binding   *chan_binding_mic;   */
      ///          rpc_gss3_assertion      assertions<>;
      ///  };  enum rpc_gss_service_t {
      ///          /* Note: the enumerated value for 0 is reserved. */
      ///  struct rpc_gss3_create_res {          rpc_gss_svc_none         = 1,
      ///          opaque                  handle<>;          rpc_gss_svc_integrity    = 2,
      ///          rpc_gss3_chan_binding   *chan_binding_mic;          rpc_gss_svc_privacy      = 3,
      ///          rpc_gss3_assertion      granted_assertions<>;          rpc_gss_svc_channel_prot = 4
      ///  };
      ///
      ///  enum rpc_gss3_list_item rpc_gss_proc_t {
      ///          LABEL           RPCSEC_GSS_DATA          = 0,
      ///  };           RPCSEC_GSS_INIT          = 1,
      ///           RPCSEC_GSS_CONTINUE_INIT = 2,
      ///  struct rpc_gss3_list_args {           RPCSEC_GSS_DESTROY       = 3,
      ///          rpc_gss3_list_item      list_what<>;           RPCSEC_GSS_BIND_CHANNEL  = 4, /* not used */
      ///  };           RPCSEC_GSS_CREATE        = 5, /* new */
      ///           RPCSEC_GSS_LIST          = 6  /* new */
      ///  };
      ///  union rpc_gss3_list_item_u
      ///        switch (rpc_gss3_list_item itype)  struct rpc_gss_cred_vers_1_t {
      ///  case LABEL:          rpc_gss_proc_t    gss_proc; /* control procedure */
      ///          rpc_gss3_lable          labels<>;          unsigned int      seq_num;  /* sequence number */
      ///  default:          rpc_gss_service_t service;  /* service used */
      ///          opaque                  ext<>;            handle<>; /* context handle */
      ///  };
      ///
      ///  typedef rpc_gss3_list_item_u rpc_gss3_list_res<>;

2.1.  New auth_stat Values

   RPCSEC_GSSv3 requires the addition of several values to the auth_stat
   enumerated type definition:

              enum auth_stat {
                      ...
                      /*
                       * RPCSEC_GSSv3 errors
                       */
                      RPCSEC_GSS3_COMPOUND_PROBEM = <>,
                      RPCSEC_GSS3_LABEL_PROBLEM  const RPCSEC_GSS_VERS_1 = <>,
                      RPCSEC_GSS3_UNKNOWN_PRIVILEGE 1;
      ///  const RPCSEC_GSS_VERS_2 = <>
                      RPCSEC_GSS3_UNKNOWN_MESSAGE 2;
      ///  const RPCSEC_GSS_VERS_3 = <>
              };

   [[Comment.5: fix above into YYY.  All the entries are TBD... --NW]]
   [[Comment.6: The compound authentication problems are: can't find the
   handle plus handle version on the target, or the MIC of the nounce
   does not match.  Both of these errors already have auth_stat entries:
   RPCSEC_GSS_CREDPROBLEM for the first and "reply status of
   MSG_ACCEPTED, and an acceptance status of GARBAGE_ARGS." --AA]]

2.2.  RPC Message Credential and Verifier

   The rpc_gss_cred_vers_3_t type is used in much the same way that
   rpc_gss_cred_vers_1_t is used in RPCSEC_GSSv1, that is: as the arm of
   the rpc_gss_cred_t discriminated 3; /* new */
      ///
      ///  union in the RPC message header
   opaque_auth structure corresponding to version 3 (RPCSEC_GSS_VERS_3).
   It differs from rpc_gss_cred_vers_1_t in that:

   a.  the values for gss_proc corresponding to control messages are
       different.

   b.  the handle field is rpc_gss_cred_t switch (unsigned int rgc_version) {
      ///  case RPCSEC_GSS_VERS_1:
      ///  case RPCSEC_GSS_VERS_2:
      ///  case RPCSEC_GSS_VERS_3: /* new */
      ///          rpc_gss_cred_vers_1_t rgc_cred_v1;
      ///  };
      ///

   <CODE ENDS>

   As seen above, the RPCSEC_GSSv3 (child) handle, except for credential has the RPCSEC_GSS3_CREATE and RPCSEC_GSS3_LIST control messages
       where it is set to same format as the parent context handle.

   For all RPCSEC_GSSv3 data
   RPCSEC_GSSv1 [2] and control messages, RPCSEC_GSSv2 [4] credential.  Setting the verifier
   rgc_version field in
   the RPC message header is constructed in to 3 indicates that the RPCSEC_GSSv1 manner
   using initiator and target
   support the parent GSS-API security context.

2.3. new RPCSEC_GSSv3 control procedures.

2.4.  New Control Messages Procedures

   There are three two new RPCSEC_GSSv3 control messages: RPCSEC_GSS3_CREATE,
   RPCSEC_GSS3_DESTROY, and RPCSEC_GSS3_LIST. procedures: RPCSEC_GSS_CREATE,
   RPCSEC_GSS_LIST.

   The RPCSEC_GSS_CREATE procedure binds any combination of assertions:
   compound authentication, labels, structured privileges, or channel
   bindings to a new RPCSEC_GSSv3 context returned in the
   rgss3_create_res rcr_handle field.

   The RPCSEC_GSS_LIST procedure queries the target for supported
   assertions.

   RPCSEC_GSS version 3 control messages are similar to the RPCSEC_GSSv1 RPCSEC_GSS
   version 1 and version2 RPCSEC_GSS_DESTROY control message (see
   section 5.4 [2]) in that the sequence number in the request must be
   valid, and the header checksum in the verifier must be valid.  In other words, they look a lot like
   an RPCSEC_GSSv3 data message with the header procedure set to
   NULLPROC.  As in RPCSEC_GSSv1,
   RPCSEC_GSS version 1 and version 2, the RPCSEC_GSSv3 RPCSEC_GSSv version 3 control
   messages may contain
   information call data following the verifier in the body of
   the NULLPROC
   procedure.

   The client MUST use one of the following security services to protect
   any RPCSEC_GSSv3 control message:

   o  rpc_gss_svc_channel_prot (see RPCSEC_GSSv2)
   o  rpc_gss_svc_integrity

   o  rpc_gss_svc_privacy

   Specifically the client MUST NOT use rpc_gss_svc_none.

   For RPCSEC_GSSv3 control messages the rpc_gss_cred_vers_3_t in the
   RPC message opaque_auth structure is encoded as follows:

   o  the union rpc_gss_cred_t version is set to 3 with the value being
      of type rpc_gss_cred_vers_3_t instead of rpc_gss_cred_vers_1_t.

   o  the gss_proc is set to one of RPCSEC_GSS3_CREATE,
      RPCSEC_GSS3_DESTROY, or RPCSEC_GSS3_LIST.

   o  the seq_num is a valid sequence number for the context in the
      handle field.

   o  the rpc_gss_service_t is one of rpc_gss_svc_integrity,
      rpc_gss_svc_privacy, or rpc_gss_svc_channel_prot.

   o  the rpc_gss_cred_vers_3_t handle field is either set to the parent
      context handle for RPCSEC_GSS3_CREATE and RPCSEC_GSS3_LIST, or to
      the GSS3 child handle for RPCSEC_GSS3_DESTROY.

2.3.1.  Create Request

   As noted in the introduction, RPCSEC_GSSv3 relies on the procedure.  In other words, they look a lot like an
   RPCSEC_GSS
   version 1 parent context (though version 2 can be used) secure
   connection data message with the header procedure set to do NULLPROC.

   The client MUST use one of the actual GSS-API GSS3 following security context
   establishment.  As such, for the RPCSEC_GSS3_CREATE request, services to protect
   the
   rpc_gss_cred_vers_3_t fields in RPCSEC_GSS_CREATE or RPCSEC_GSS_LIST control message:

   o  rpc_gss_svc_channel_prot (see RPCSEC_GSSv2 [4])

   o  rpc_gss_svc_integrity

   o  rpc_gss_svc_privacy

   Specifically the RPC Call opaque_auth client MUST NOT use the
   parent context handle and seq_num stream. rpc_gss_svc_none.

2.4.1.  New Control Procedure - RPCSEC_GSS_CREATE

   <CODE BEGINS>

      ///  struct rgss3_create_args {
      ///          rgss3_gss_binding    *rca_comp_auth;
      ///          rgss3_chan_binding   *rca_chan_bind_mic;
      ///          rgss3_assertion      rca_assertions<>;
      ///  };
      ///
      ///  struct rgss3_create_res {
      ///          opaque               rcr_handle<>;
      ///          rgss3_gss_binding    *rcr_comp_auth;
      ///          rgss3_chan_binding   *rcr_chan_bind_mic;
      ///          rgss3_assertion      rcr_assertions<>;
      ///  };
      ///
      ///  enum rgss3_assertion_type {
      ///          LABEL = 0,
      ///          PRIVS = 1
      ///  };
      ///
      ///  union rgss3_assertion_u
      ///        switch (rgss3_assertion_type atype) {
      ///  case LABEL:
      ///          rgss3_label  rau_label;
      ///  case PRIVS:
      ///          rgss3_privs  rau_privs;
      ///  default:
      ///          opaque       rau_ext<>;
      ///  };
      ///
      ///  struct rgss3_assertion {
      ///          bool                 ra_critical;
      ///          rgss3_assertion_u    ra_assertion;
      ///  };
      ///

   <CODE ENDS>

   The RPCSEC_GSS3_CREATE call message data for an RPCSEC_GSS_CREATE request consists of an
   rgss3_create_args which binds one or more items of several kinds into a new to
   the returned rcr_handle RPCSEC_GSSv3 context handle called the
   "child" handle:

   o  Compound authentication: another RPCSEC_GSS (version 1, 2, or 3) context handle (compound
      authentication)

   o  a  Authorization assertions: labels and or privileges

   o  A channel binding

   o  authorization assertions (labels, privileges)

   The reply to this message consists of either an error or an
   rpc_gss3_create_res structure which includes a new RPCSEC_GSSv3
   handle, termed the "child" which is used for subsequent control and
   data messages.
   rgss3_create_res structure.

   Upon successful RPCSEC_GSS3_CREATE, RPCSEC_GSS_CREATE, both the client and the server
   should
   SHOULD associate the resultant GSSv3 child rcr_handle context handle with
   the parent context handle in their GSS context caches so as to be
   able to reference the parent context given the child context handle.

   RPCSEC_GSSv3 child handles MUST be destroyed upon the destruction of
   the associated parent handle.

   Server implementation and policy MAY result in labels, privileges,
   and identities being mapped to concepts and values that are local to
   the server.  Server policies should take into account the identity of
   the client and/or user as authenticated via the GSS-API.

2.3.1.1.

2.4.1.1.  Compound Authentication

   <CODE BEGINS>

      ///
      ///  struct rgss3_gss_binding {
      ///          opaque          rgb_handle<>; /* inner handle */
      ///          opaque          rgb_nonce<>;
      ///          opaque          rgb_nounc_mic<>;
      ///  };
      ///

   <CODE ENDS>

   RPCSEC_GSSv3 allows for clients MAY assert a compound authentication of client hosts and
   users to servers.  As in non-compound authentication, there is a
   parent handle used to protect the RPCSEC_GSS3_CREATE call message
   client host and a resultant RPCSEC_GSSv3 child handle. user.  This is done by including an assertion of
   type rgss3_gss_binding in the RPCSEC_GSS_CREATE rgss3_create_args
   call data.  In addition to the parent
   handle, handle (Section 2), the
   compound authentication create control message rgss3_gss_binding call data has a an RPCSEC_GSS
   version 3 handle referenced via the compound_binding rgb_handle field of the
   RPCSEC_GSS3_CREATE arguments structure (rpc_gss3_create_args) termed the
   "inner" handle, as well as a handle.  A nonce and a MIC of that nounce created using the
   GSS-API security context associated with the
   "inner" inner handle is also
   provided.

   The target verifies the compounding by verifying the rgb_nouce_mic.
   On a successful reply, the rgss3_gss_binding field in the
   rgss3_create_res reply uses the parent RPCSEC_GSSv3 context as the
   rgb_handle, the same rgb_nounce as was sent in the call data with the
   rgb_nounce_mic created using the GSS-API security context associate
   with the parent handle.  Verification of the rbg_nounce_mic by the
   initiator demonstrates that the target agrees to the compounding.  On
   failure, the rgss3_gss_binding field is not sent. (rgss3_gss_binding
   is an optional field)

   This feature is needed, for example, when a client wishes to use
   authority assertions that the server may only grant if a user and a
   client are authenticated together to the server.  Thus a server may
   refuse to grant requested authority to a user acting alone (e.g., via
   an unprivileged user-space program), or to a client acting alone
   (e.g. when a client is acting on behalf of a user) but may grant
   requested authority to a client acting on behalf of a user if the
   server identifies the user and trusts the client.

   It is assumed that an unprivileged user-space program would not have
   access to client host credentials needed to establish a GSS-API
   security context authenticating the client to the server, therefore
   an unprivileged user-space program could not create an RPCSEC_GSSv3
   RPCSEC_GSS3_CREATE
   RPCSEC_GSS_CREATE message that successfully binds a client and a user
   security context.

   Clients using RPCSEC_GSS context binding RPCSEC_GSSv3 compound authentication MUST use, as the parent
   context handle, use an RPCSEC_GSS
   RPCSEC_GSSv3 context handle that corresponds to a GSS-API security
   context that authenticates the client host, and host for the outer handle.  The
   inner context handle it SHOULD use a context handle to authenticate a
   user.  The reverse (parent (outer handle authenticates user, inner
   authenticates client) MUST NOT be used.  Other compounds might
   eventually make sense.

   An inner RPCSEC_GSSv3 context handle that is bound to another an outer
   RPCSEC_GSS context MUST be treated by servers as authenticating the
   GSS-API initiator principal authenticated by the inner context
   handle's GSS- API security context.  This principal may be mapped to
   a server-side notion of user or principal.

2.3.1.2.  Channel Binding

2.4.1.2.  Label Assertions

   <CODE BEGINS>

      ///  struct rgss3_label {
      ///          rgss3_lfs       rl_lfs;
      ///          opaque          rl_label<>;
      ///  };
      ///
      ///  struct rgss3_lfs {
      ///          unsigned int rlf_lfs_id;
      ///          unsigned int rlf_pi_id;
      ///  };
      ///

   <CODE ENDS>

   The client discovers which labels the server supports via the
   RPCSEC_GSS_LIST control message.

   RPCSEC_GSSv3 provides clients MAY assert a different way to do channel binding than
   RPCSEC_GSSv2.  Specifically:

   a.  RPCSEC_GSSv3 builds on RPCSEC_GSSv1 server security label in some LSF
   by reusing existing,
       established context handles rather than providing binding a different RPC
       security flavor for establishing context handles,

   b.  channel bindings data are not hashed because the community now
       agrees that it is the secure channel's responsibility label assertion to produce
       channel bindings data of manageable size.

   (a) is useful in keeping RPCSEC_GSSv3 simple in general, not just for
   channel binding. (b) is useful in keeping the RPCSEC_GSSv3 simple
   specifically for channel binding.

   Channel binding context handle.
   This is accomplished as follows.  The client prefixes the
   channel bindings data octet string with the channel done by including an assertion of type as described rgss3_label in [5], then the client calls GSS_GetMIC()
   RPCSEC_GSS_CREATE rgss3_create_args rca_assertions call data.

   The labels that are accepted by the target and bound to get a MIC of resulting
   octet string, using the parent RPCSEC_GSS
   RPCSEC_GSSv3 context handle's GSS-API
   security context.  The MIC is then placed will be enumerated in the chan_binding_mic rcr_assertions field
   of RPCSEC_GSS3_CREATE arguments (rpc_gss3_create_args).

   If the chan_binding_mic field of rgss3_create_res RPCSEC_GSS_CREATE reply.

   Label encoding is specified to mirror the arguments NFSv4.2 sec_label attribute
   described in Section 12.2.2 of a
   RPCSEC_GSS3_CREATE control message [6].  The label format specifier (LFS)
   is set, then the server MUST
   verify the client's channel binding MIC if an identifier used by the server supports this
   feature.  If channel binding verification succeeds then client to establish the server
   MUST generate a new MIC syntactic format
   of the same channel bindings security label and place it in the chan_binding_mic field semantic meaning of the RPCSEC_GSS3_CREATE results.  If
   channel binding verification fails or the server doesn't support
   channel binding then the server MUST indicate this in its reply by
   not including a chan_binding_mic value (chan_binding_mic components.
   The policy identifier (PI) is an optional field).

   The client MUST verify the result's chan_binding_mic value, if part of the definition of
   an LFS which allows for clients and server included it, by calling GSS_VerifyMIC() with to identify specific
   security policies.  The opaque label field of rgss3_label is
   dependent on the given MIC MAC model to interpret and enforce.

   Asserting a server supported label via RPCSEC_GSS_CREATE enables
   server guest mode labels.  Full mode is enabled when an
   RPCSEC_GSS_CREATE label assertion is combined with asserting the channel bindings data (including same
   label with the channel type prefix).  If
   client-side channel binding verification fails then NFSv4.2 sec_label attribute.

   [[Comment.2: Check that this Label discussion provides all the client MUST
   call RPCSEC_GSS3_DESTROY.  If
   required pieces to enable full mode when combined with NFSv4.2 LNFS.
   Specifically, how does the client requested channel binding
   but the find out and respond if a server did not include
   has changed a chan_binding_mic field in label. --AA]]
   If a label itself requires privacy protection (i.e., that the
   results, user
   can assert that label is a secret) then the client MAY continue to MUST use the resulting context
   rpc_gss_svc_privacy protection service for the RPCSEC_GSS_CREATE
   request or, if the parent handle as though is bound to a secure channel binding had never been requested, otherwise
   (if the that
   provides privacy protection, rpc_gss_svc_channel_prot.

   If a client really wanted channel binding) wants to ensure that the server understands the asserted
   label then it MUST call
   RPCSEC_GSS3_DESTROY.

   As per-RPCSEC_GSSv2 [4]:

      "Once a successful [channel binding] procedure has been performed
      on an [RPCSEC_GSSv3] context handle, set the initiator's
      implementation may map application requests for rpc_gss_svc_none
      and rpc_gss_svc_integrity to rpc_gss_svc_channel_prot credentials.
      And if 'critical' field of the secure channel has privacy enabled, requests for
      rpc_gss_svc_privacy can also be mapped label assertion to
      rpc_gss_svc_channel_prot."

   Any RPCSEC_GSSv3 context handle
   TRUE, otherwise it MUST set it to FALSE.

   Servers that has been bound do not support labeling MUST ignore non-critical label
   assertions.  Servers that do not support the requested LFS MUST
   either ignore non-critical label assertions or map them to a secure
   channel suitable
   label in this way SHOULD be used only with a supported LFS.  Servers that do not support labeling or do
   not support the
   rpc_gss_svc_channel_prot, and SHOULD NOT be used with
   rpc_gss_svc_none nor rpc_gss_svc_integrity -- requested LFS MUST return an error if the secure channel
   does not provide privacy protection then the client MAY use
   rpc_gss_svc_privacy where privacy protection label
   request is needed or desired.

2.3.1.3.  Label critical.  Servers that support labeling in the requested
   LFS MAY map the requested label to different label as a result of
   server-side policy evaluation.

2.4.1.3.  Structured Privilege Assertions

   <CODE BEGINS>

      ///
      ///  struct rgss3_privs {
      ///          string          rp_name<>; /* human readable */
      ///          opaque          rp_privilege<>;
      ///  };

   <CODE ENDS>

   A structured privilege is an RPC application defined privilege.
   RPCSEC_GSSv3 clients MAY assert a security label in some LSF structured privilege by binding this assertion into an the
   privilege to the RPCSEC_GSSv3 context handle.  This is done by
   including an assertion of type rpc_gss3_label rgss3_privs in the
   'assertions' field (discriminant: 'LABEL') of the RPCSEC_GSS3_CREATE
   arguments to the desired LSF RPCSEC_GSS_CREATE
   rgss3_create_args rca_assertions call data.  Encoding, server
   verification and label.

   Label encoding is specified to mirror the NFSv4 sec_label attribute any policies for structured privileges are described in Section 12.2.2 of [6].  The label format specifier (LFS)
   is an identifier used
   by the client to establish RPC application definition.

   A successful structured privilege assertion will be enumerated in the syntactic format
   rcr_assertions field of the security label and the semantic meaning rgss3_create_res RPCSEC_GSS_CREATE reply.

   Section 3.4.1.2.  "Inter-Server Copy with RPCSEC_GSSv3" of its components.
   The policy identifier (PI) is [6] shows
   an optional part example of the structured privilege definition of
   an LFS which allows for clients and server to identify specific
   security policies.  The use.

2.4.1.4.  Channel Binding

   <CODE BEGINS>

      ///
      ///  typedef opaque label field of rpc_gss3_label is
   dependent on the MAC model to interpret and enforce.

   [[Comment.7: Check that this Label definition rgss3_chan_binding<>;
      ///

   <CODE ENDS>

   RPCSEC_GSSv3 provides all the
   required pieces to enable full mode when combined with NFSv4.2 LNFS.
   Specifically, how does the client find out and respond if a server
   has changed a label. --AA]]

   If different way to do channel binding than
   RPCSEC_GSSv2 [4].  Specifically:

   a.  RPCSEC_GSSv3 builds on RPCSEC_GSSv1 by reusing existing,
       established context handles rather than providing a label itself requires privacy protection (i.e., that different RPC
       security flavor for establishing context handles,

   b.  channel bindings data are not hashed because the user
   can assert community now
       agrees that label it is a secret) then the client MUST use the
   rpc_gss_svc_privacy protection service secure channel's responsibility to produce
       channel bindings data of manageable size.

   (a) is useful in keeping RPCSEC_GSSv3 simple in general, not just for
   channel binding. (b) is useful in keeping RPCSEC_GSSv3 simple
   specifically for channel binding.

   Channel binding is accomplished as follows.  The client prefixes the RPCSEC_GSS3_CREATE
   request or, if
   channel bindings data octet string with the parent handle is bound to a secure channel that
   provides privacy protection, rpc_gss_svc_channel_prot.

   If a type as described
   in [5], then the client wants calls GSS_GetMIC() to ensure that the server understands get a MIC of resulting
   octet string, using the asserted
   label RPCSEC_GSSv3 context handle's GSS-API
   security context.  The MIC is then it MUST set placed in the 'critical' rca_chan_bind_mic
   field of RPCSEC_GSS_CREATE arguments (rgss3_create_args).

   If the label assertion to
   TRUE, otherwise it MUST set it to FALSE.

   Servers that do not support labeling MUST ignore non-critical label
   assertions.  Servers that do not support rca_chan_bind_mic field of the requested LFS MUST
   either ignore non-critical label assertions or map them to a suitable
   label in arguments of a supported LFS.  Servers that do not support labeling or do
   not support
   RPCSEC_GSS_CREATE control message is set, then the requested LFS server MUST return an error if the label
   request is critical.  Servers that support labeling in verify
   the requested
   LFS MAY map client's channel binding MIC if the requested label to different label as a result of
   server-side policy evaluation.

2.3.1.4.  Structured Privilege Assertions

   A structured privilege is an RPC application defined structure that
   is opaque, server supports this feature.
   If channel binding verification succeeds then the server MUST
   generate a new MIC of the same channel bindings and is encoded place it in the rpc_gss3_privs privilege field.
   Encoding, server
   rcr_chan_bind_mic field of the RPCSEC_GSS_CREATE rgss3_create_res
   results.  If channel binding verification and any fails or the server policies for structured
   privileges are described by doesn't
   support channel binding then the RPC application definition.

   A successful structured privilege assertion RPCSEC_GSS3_CREATE call
   must return all granted privileges server MUST indicate this in its
   reply by not including a rgss3_chan_binding value in rgss3_create_res
   (rgss3_chan_binding is an optional field).

   The client MUST verify the rpc_gss3_privs
   granted_assertions field.

   Section 3.4.1.2.  "Inter-Server Copy result's rcr_chan_bind_mic value by
   calling GSS_VerifyMIC() with RPCSEC_GSSv3" of [6] shows
   an example of structured privilege definition the given MIC and use.

2.3.2.  Destruction Request

   The RPCSEC_GSS3_DESTROY control message is the same as channel bindings
   data (including the
   RPCSEC_GSSv1 RPCSEC_GSS_DESTROY control message, but with channel type prefix).  If client-side channel
   binding verification fails then the version
   3 header.  Specifically, client MUST call
   RPCSEC_GSS_DESTROY.  If the client requested channel binding but the rpc_gss_cred_vers_3_t fields
   server did not include an rcr_chan_binding_mic field in the RPC
   Call opaque_auth results,
   then the client MAY continue to use the GSS3 resulting context handle and seq_num stream.  As
   with all RPCSEC_GSSv3 messages, as
   though channel binding had never been requested, otherwise (if the header checksum uses
   client really wanted channel binding) it MUST call
   RPCSEC_GSS_DESTROY.

   As per-RPCSEC_GSSv2 [4]:

      "Once a successful [channel binding] procedure has been performed
      on an [RPCSEC_GSSv3] context handle, the parent
   context, initiator's
      implementation may map application requests for rpc_gss_svc_none
      and needs rpc_gss_svc_integrity to rpc_gss_svc_channel_prot credentials.
      And if the secure channel has privacy enabled, requests for
      rpc_gss_svc_privacy can also be valid.

   The server sends a response as it would mapped to a data request.  The
   client and server must then destroy the
      rpc_gss_svc_channel_prot."

   Any RPCSEC_GSSv3 context for the session.

2.3.3.  List Request

   The RPCSEC_GSS3_LIST control message is similar handle that has been bound to RPCSEC_GSS3_CREATE
   message.  Specifically, the rpc_gss_cred_vers_3_t fields a secure
   channel in this way SHOULD be used only with the RPC
   Call opaque_auth use the parent context handle
   rpc_gss_svc_channel_prot, and seq_num stream.
   As SHOULD NOT be used with all RPCSEC_GSSv3 messages,
   rpc_gss_svc_none nor rpc_gss_svc_integrity -- if the header checksum uses secure channel
   does not provide privacy protection then the
   parent context, and needs to be valid. client MAY use
   rpc_gss_svc_privacy where privacy protection is needed or desired.

2.4.2.  New Control Procedure - RPCSEC_GSS_LIST

   <CODE BEGINS>

      ///  enum rgss3_list_item {
      ///          LABEL = 0,
      ///          PRIVS = 1
      ///  };
      ///
      ///  struct rgss3_list_args {
      ///          rgss3_list_item      rla_list_what<>;
      ///  };
      ///
      ///  union rgss3_list_item_u
      ///        switch (rgss3_list_item itype) {
      ///  case LABEL:
      ///          rgss3_label          rli_labels<>;
      ///  case PRIVS:
      ///          rgss3_privs          rli_privs<>;
      ///  default:
      ///          opaque               rli_ext<>;
      ///  };
      ///
      ///  typedef rgss3_list_item_u rgss3_list_res<>;
      ///

   <CODE ENDS>

   The RPCSEC_GSS3_LIST control message call data for an RPCSEC_GSS_LIST request consists of a single integer list of
   integers (rla_list_what<>) indicating what should assertions to be listed,
   and the reply consists of an error or the requested list.  The client may query

   [[Comment.3: What good is the server to list
   available LFSs. rli_ext field?  How should we describe
   it's use? --AA]]

   The result of requesting a list of rgss3_list_item LABEL is an opaque octet string containing a list of
   LFSs
   [encoding TBD].

2.3.4. supported by the server.  The client can then use the LFS list
   to assert labels via the RPCSEC_GSS_CREATE label assertions.  See
   Section 2.4.1.2.

2.5.  Extensibility

   Assertion types may be added in the future by adding arms to the
   'rpc_gss3_assertion_u'
   'rgss3_assertion_u' union.  Every assertion has a 'critical' flag
   that can be used to indicate criticality.  Other assertion types are
   described elsewhere and include:

   o  Client-side assertions of identity:

      *  Primary client/user identity

      *  Supplementary group memberships of the client/user, including
         support for specifying deltas to the membership list as seen on
         the server.

   New control message types may be added.

   Servers receiving unknown critical client assertions MUST return an
   error.

2.4.  Data Messages

   RPCSEC_GSS3_DATA messages differ from from RPCSEC_GSSv1 data messages
   in
   error.

2.6.  New auth_stat Values

   RPCSEC_GSSv3 requires the addition of several values to the auth_stat
   enumerated type definition:

              enum auth_stat {
                      ...
                      /*
                       * RPCSEC_GSSv3 errors
                       */
                      RPCSEC_GSS_COMPOUND_PROBLEM = <>,
                      RPCSEC_GSS_LABEL_PROBLEM = <>,
                      RPCSEC_GSS_UNKNOWN_PRIVILEGE = <>
                      RPCSEC_GSS_UNKNOWN_MESSAGE = <>

              };

   [[Comment.4: fix above into YYY.  All the entries are TBD... --NW]]
   [[Comment.5: The compound authentication problems are: can't find the
   handle plus handle version on the target, or the MIC of the nounce
   does not match.  Both of these errors already have auth_stat entries:
   RPCSEC_GSS_CREDPROBLEM for the first and "reply status of
   MSG_ACCEPTED, and an acceptance status of GARBAGE_ARGS." --AA]]

3.  Version Negotiation

   An initiator that the supports version number used MUST be '3' instead 3 of '1'.  As noted
   in Section 2.2 the RPCSEC_GSSv3 context handle is used along RPCSEC_GSS simply issues an
   RPCSEC_GSS request with
   it's sequence number stream.

   For RPCSEC_GSSv3 data messages the rpc_gss_cred_vers_3_t in rgc_version field set to
   RPCSEC_GSS_VERS_3.  If the RPC
   message opaque_auth structure is encoded as follows:

   1. target does not recognize
   RPCSEC_GSS_VERS_3, the union rpc_gss_cred_t version is set target will return an RPC error per Section
   5.1 of [2].

   The initiator MUST NOT attempt to use an RPCSEC_GSS handle returned
   by version 3 with the value being of type rpc_gss_cred_vers_3_t instead a target with version 1 or version 2 of rpc_gss_cred_vers_1_t.

   2. the gss_proc is set same
   target.  The initiator MUST NOT attempt to RPCSEC_GSS3_DATA

   3. use an RPCSEC_GSS handle
   returned by version 1 or version 2 of a target with version 3 of the seq_num
   same target.

4.  Operational Recommendation for Deployment

   RPCSEC_GSSv3 is a valid GSS3 context (child context) sequence
       number.

   4.  just as superset of RPCSEC_GSSv2 [4] which in RPCSEC_GSSv1, the rpc_gss_service_t turn is one a
   superset of
       rpc_gss_svc_none, rpc_gss_svc_integrity, rpc_gss_svc_privacy, RPCSEC_GSSv1 [2], and so can be used in all situations
   where RPCSEC_GSSv1 or
       rpc_gss_svc_channel_prot.

   5.  the handle field RPCSEC_GSSv2 is set to the (child) used.  RPCSEC_GSSv3 context
       handle

3. should be
   used when the new functionality is needed.

5.  Security Considerations

   This entire document deals with security issues.

   The RPCSEC_GSSv3 protocol allows for client-side assertions of data
   that is relevant to server-side authorization decisions.  These
   assertions must be evaludated by the server in the context of whether
   the client and/or user are authenticated, whether compound
   authentication was used, whether the client is trusted, what ranges
   of assertions are allowed for the client and the user (separately or
   together), and any relevant server-side policy.

   The security semantics of assertions carried by RPCSEC_GSSv3 are
   application protocol-specific.

   RPCSEC_GSSv3 supports a notion of critical assertions but there's no
   need for peers to tell each other what assertions were granted, or
   what they were mapped to.

   Note that RPSEC_GSSv3 is not a complete solution for labeling: it
   conveys the labels of actors, but not the labels of objects.  RPC
   application protocols may require extending in order to carry object
   label information.

   There may be interactions with NFSv4's callback security scheme and
   NFSv4.1's GSS-API "SSV" mechanisms.  Specifically, the NFSv4 callback
   scheme requires that the server initiate GSS-API security contexts,
   which does not work well in practice, and in the context of client-
   side processes running as the same user but with different privileges
   and security labels the NFSv4 callback security scheme seems
   particularly unlikely to work well.  NFSv4.1 has the server use an
   existing, client-initiated RPCSEC_GSS context handle to protect
   server-initiated callback RPCs.  The NFSv4.1 callback security scheme
   lacks all the problems of the NFSv4 scheme, however, it is important
   that the server pick an appropriate RPCSEC_GSS context handle to
   protect any callbacks.  Specifically, it is important that the server
   use RPCSEC_GSS context handles which authenticate the client to
   protect any callbacks relating to server state initiated by RPCs
   protected by RPCSEC_GSSv3 contexts.

   [[Comment.8:

   [[Comment.6: [Add text about interaction with GSS-SSV...] --NW]]

   [[Comment.9: I see no reason to use RPCSEC_GSSv3 contexts for NFSv4.x
   back channel. --AA]]

   [[Comment.10: Since GSS3 requires an RPCSEC_GSSv1 or v2 context
   handle to establish a GSS3 context, SSV can not be used as this draft
   is written.]]

   [[Comment.11:

   [[Comment.7: AFAICS the reason to use SSV is to avoid using a client
   machine credential which means compound authentication can not be
   used.  Since GSS3 requires an RPCSEC_GSSv1 or v2 context handle to
   establish a GSS3 context, SSV can not be used as the parent context
   for GSSv3. --AA]]

4.

6.  IANA Considerations

   This section uses terms that are defined in [8].

   There are no IANA considerations in this document.  TBDs in this
   document will be assigned by the ONC RPC registrar (which is not
   IANA, XXX: verify).

5.

7.  References

5.1.

7.1.  Normative References

   [1]   Bradner, S., "Key words for use in RFCs to Indicate Requirement
         Levels", RFC 2119, March 1997.

   [2]   Eisler, M., Chiu, A., and L. Ling, "RPCSEC_GSS Protocol
         Specification", RFC 2203, September 1997.

   [3]   Linn, J., "Generic Security Service Application Program
         Interface Version 2, Update 1", RFC 2743, January 2000.

   [4]   Srinivasan, R., "RPC: Remote Procedure Call Protocol
         Specification   Eisler, M., "RPCSEC_GSS Version 2", RFC 1831, August 1995. 5403, February 2009.

   [5]   Williams, N., "On the Use of Channel Bindings to Secure
         Channels", RFC 5056, November 2007.

   [6]   Haynes, T., "NFS Version 4 Minor Version 2",
         draft-ietf-nfsv4-minorversion2-19
         draft-ietf-nfsv4-minorversion2-21 (Work In Progress),
         March 2013.

   [7]   Eisler, M., "XDR: External Data Representation Standard",
         RFC 4506, May 2006.

   [8]   Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
         Considerations Section in RFCs", BCP 26, RFC 5226, May 2008.

5.2.

7.2.  Informative References

   [9]   Haynes, T., "Requirements for Labeled NFS",
         draft-ietf-nfsv4-labreqs-03 (work in progress).

   [10]   "Section 46.6. Multi-Level Security (MLS) of Deployment Guide:
         Deployment, configuration and administration of Red Hat
         Enterprise Linux 5, Edition 6", 2011.

   [11]

   [10]  Smalley, S., "The Distributed Trusted Operating System (DTOS)
         Home Page",
         <http://www.cs.utah.edu/flux/fluke/html/dtos/HTML/dtos.html>.

   [12]

   [11]  Carter, J., "Implementing SELinux Support for NFS",
         <http://www.nsa.gov/research/_files/selinux/papers/nfsv3.pdf>.

   [12]  Haynes, T., "Requirements for Labeled NFS",
         draft-ietf-nfsv4-labreqs-05 (work in progress).

   [13]  Quigley, D. and J. Lu, "Registry Specification for MAC Security
         Label Formats", draft-quigley-label-format-registry (work in
         progress), 2011.

Appendix A.  Acknowledgments
Appendix B.  RFC Editor Notes

   [RFC Editor: please remove this section prior to publishing this
   document as an RFC]

   [RFC Editor: prior to publishing this document as an RFC, please
   replace all occurrences of RFCTBD10 with RFCxxxx where xxxx is the
   RFC number of this document]

Authors' Addresses

   William A. (Andy) Adamson
   NetApp
   3629 Wagner Ridge Ctt
   Ann Arbor, MI  48103
   USA

   Phone: +1 734 665 1204
   Email: andros@netapp.com

   Nico Williams
   cryptonector.com
   13115 Tamayo Dr
   Austin, TX  78729
   USA

   Email: nico@cryptonector.com