draft-ietf-nfsv4-rpcsec-gssv3-13.txt   draft-ietf-nfsv4-rpcsec-gssv3-14.txt 
NFSv4 W. Adamson NFSv4 W. Adamson
Internet-Draft NetApp Internet-Draft NetApp
Intended status: Standards Track N. Williams Intended status: Standards Track N. Williams
Expires: May 5, 2016 Cryptonector Expires: June 16, 2016 Cryptonector
November 02, 2015 December 14, 2015
Remote Procedure Call (RPC) Security Version 3 Remote Procedure Call (RPC) Security Version 3
draft-ietf-nfsv4-rpcsec-gssv3-13 draft-ietf-nfsv4-rpcsec-gssv3-14
Abstract Abstract
This document specifies version 3 of the Remote Procedure Call (RPC) This document specifies version 3 of the Remote Procedure Call (RPC)
security protocol (RPCSEC_GSS). This protocol provides support for security protocol (RPCSEC_GSS). This protocol provides support for
multi-principal authentication of client hosts and user principals to multi-principal authentication of client hosts and user principals to
server (constructed by generic composition), security label a server (constructed by generic composition), security label
assertions for multi-level and type enforcement, structured privilege assertions for multi-level and type enforcement, structured privilege
assertions, and channel bindings. assertions, and channel bindings.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 5, 2016. This Internet-Draft will expire on June 16, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction and Motivation . . . . . . . . . . . . . . . . . 2 1. Introduction and Motivation . . . . . . . . . . . . . . . . . 2
1.1. Added Functionality . . . . . . . . . . . . . . . . . . . 3 1.1. Added Functionality . . . . . . . . . . . . . . . . . . . 4
1.2. XDR Code Extraction . . . . . . . . . . . . . . . . . . . 4 1.2. XDR Code Extraction . . . . . . . . . . . . . . . . . . . 5
2. The RPCSEC_GSSv3 Protocol . . . . . . . . . . . . . . . . . . 4 2. The RPCSEC_GSSv3 Protocol . . . . . . . . . . . . . . . . . . 5
2.1. Compatibility with RPCSEC_GSSv2 . . . . . . . . . . . . . 5 2.1. Compatibility with RPCSEC_GSSv2 . . . . . . . . . . . . . 6
2.2. Version Negotiation . . . . . . . . . . . . . . . . . . . 5 2.2. Version Negotiation . . . . . . . . . . . . . . . . . . . 6
2.3. New REPLY Verifier . . . . . . . . . . . . . . . . . . . 5 2.3. New REPLY Verifier . . . . . . . . . . . . . . . . . . . 6
2.4. XDR Code Preliminaries . . . . . . . . . . . . . . . . . 6 2.4. XDR Code Preliminaries . . . . . . . . . . . . . . . . . 7
2.5. RPCSEC_GSS_BIND_CHANNEL Operation . . . . . . . . . . . . 8 2.5. RPCSEC_GSS_BIND_CHANNEL Operation . . . . . . . . . . . . 9
2.6. New auth_stat Values . . . . . . . . . . . . . . . . . . 8 2.6. New auth_stat Values . . . . . . . . . . . . . . . . . . 9
2.7. New Control Procedures . . . . . . . . . . . . . . . . . 9 2.7. New Control Procedures . . . . . . . . . . . . . . . . . 10
2.7.1. New Control Procedure - RPCSEC_GSS_CREATE . . . . . . 10 2.7.1. New Control Procedure - RPCSEC_GSS_CREATE . . . . . . 10
2.7.2. New Control Procedure - RPCSEC_GSS_LIST . . . . . . . 17 2.7.2. New Control Procedure - RPCSEC_GSS_LIST . . . . . . . 17
2.8. Extensibility . . . . . . . . . . . . . . . . . . . . . . 17 2.8. Extensibility . . . . . . . . . . . . . . . . . . . . . . 18
3. Operational Recommendation for Deployment . . . . . . . . . . 18 3. Operational Recommendation for Deployment . . . . . . . . . . 19
4. Security Considerations . . . . . . . . . . . . . . . . . . . 18 4. Security Considerations . . . . . . . . . . . . . . . . . . . 19
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.1. Normative References . . . . . . . . . . . . . . . . . . 19 6.1. Normative References . . . . . . . . . . . . . . . . . . 20
6.2. Informative References . . . . . . . . . . . . . . . . . 19 6.2. Informative References . . . . . . . . . . . . . . . . . 20
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 20 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 21
Appendix B. RFC Editor Notes . . . . . . . . . . . . . . . . . . 20 Appendix B. RFC Editor Notes . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction and Motivation 1. Introduction and Motivation
The original RPCSEC_GSS protocol [RFC2203] provided for The original RPCSEC_GSS protocol [RFC2203] provided for
authentication of RPC clients and servers to each other using the authentication of RPC clients and servers to each other using the
Generic Security Services Application Programming Interface (GSS-API) Generic Security Services Application Programming Interface (GSS-API)
[RFC2743]. The second version of RPCSEC_GSS [RFC5403] added support [RFC2743]. The second version of RPCSEC_GSS [RFC5403] added support
for channel bindings [RFC5056]. for channel bindings [RFC5056].
Existing GSS-API mechanisms are insufficient for communicating Existing GSS-API mechanisms are insufficient for communicating
certain aspects of authority to a server. The GSS-API and its certain aspects of authority to a server. The GSS-API and its
mechanisms certainly could be extended to address this shortcoming. mechanisms certainly could be extended to address this shortcoming.
However, here it is addressed at the application layer, i.e. in However, here it is addressed at the application layer, i.e., in
RPCSEC_GSS. RPCSEC_GSS.
A major motivation for RPCSEC_GSSv3 is to add support for multi-level A major motivation for version 3 RPCSEC_GSS (RPCSEC_GSSv3) is to add
(labeled) security and server-side copy for NFSv4. support for multi-level (labeled) security and server-side copy for
NFSv4.
Multi-Level Security (MLS) is a traditional model where subjects are Multi-Level Security (MLS) is a traditional model where subjects
given a security level (Unclassified, Secret, Top Secret, etc.) and (processes) are given a security level (Unclassified, Secret, Top
objects are given security labels that mandate the access of the Secret, etc.) and objects (files) are given security labels that
subject to the object (see [BL73] and [RFC2401]). mandate the access of the subject to the object (see [BL73] and
[RFC4301]).
Labeled NFS (see Section 8 of [NFSv4.2]) uses the MLS subject label Labeled NFS (see Section 9 of [NFSv4.2]) uses an MLS policy with
provided by the client via the RPCSEC_GSSv3 layer to enforce MAC Mandatory Access Control (MAC) systems as defined in [RFC4949].
access to objects owned by the server to enable server guest mode. Labeled NFS stores MAC file object labels on the NFS server and
RPCSEC_GSSv3 label assertions provide the means to achieve full mode enables client Guest Mode MAC as described in Section 4.3 of
labeled NFS. [RFC7204]. RPCSEC_GSSv3 label assertions assert client MAC process
subject labels to enable Full Mode MAC when combined with Labeled NFS
as described in Section 3.3 of [RFC7204].
A traditional inter-server file copy entails the user gaining access 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 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 destination. In secure NFSv4 inter-server server-side copy (see
Section 3.4.1 of [NFSv4.2]), the user first secures access to both Section 4 of [NFSv4.2]), the user first secures access to both source
source and destination files, and then uses NFSv4.2 defined and destination files, and then uses NFSv4.2 defined RPCSEC_GSSv3
RPCSEC_GSSv3 structured privileges to authorize the destination to structured privileges to authorize the destination to copy the file
copy the file from the source on behalf of the user. from the source on behalf of the user.
Multi-principal assertions can be used to address shared cache Multi-principal assertions can be used to address shared cache
poisoning attacks on the client cache by a user. As described in poisoning attacks (see Section 9 of [AFS-RXGK]) on the client cache
Section 7 of [AFS-RXGK], multi-user machines with a single cache by a user. As described in Section 7 of [AFS-RXGK], multi-user
manager can fetch and cache data on a users' behalf, and re-display machines with a single cache manager can fetch and cache data on a
it for another user from the cache without re-fetching the data from users' behalf, and re-display it for another user from the cache
the server. The initial data acquisition is authenticated by the without re-fetching the data from the server. The initial data
first user's credentials, and if only that user's credentials are acquisition is authenticated by the first user's credentials, and if
used, it may be possible for a malicious user or users to "poison" only that user's credentials are used, it may be possible for a
the cache for other users by introducing bogus data into the cache. malicious user or users to "poison" the cache for other users by
introducing bogus data into the cache.
Another use of the multi-principal assertion is the secure conveyance Another use of the multi-principal assertion is the secure conveyance
of privilege information for processes running with more (or even of privilege information for processes running with more (or even
with less) privilege than the user normally would be accorded. with less) privilege than the user normally would be accorded.
1.1. Added Functionality 1.1. Added Functionality
We therefore describe RPCSEC_GSS version 3 (RPCSEC_GSSv3). We therefore describe RPCSEC_GSS version 3 (RPCSEC_GSSv3).
RPCSEC_GSSv3 is the same as RPCSEC_GSSv2 [RFC5403], except that the RPCSEC_GSSv3 is the same as RPCSEC_GSSv2 [RFC5403], except that the
following assertions of authority have been added. following assertions of authority have been added.
o Security labels for multi-level security type enforcement, and o Security labels for Full Mode security type enforcement, and other
other labeled security models (See [RFC7204]). labeled security models (See Section 5.5.1 in [RFC7204]).
o Application-specific structured privileges. For an example see o Application-specific structured privileges. For an example see
server-side copy [NFSv4.2]. server-side copy [NFSv4.2].
o Multi-principal authentication of the client host and user to the o Multi-principal authentication of the client host and user to the
server done by binding two RPCSEC_GSS handles. server done by binding two RPCSEC_GSS handles.
o Simplified channel binding. o Simplified channel binding.
Assertions of labels and privileges are evaluated by the server, Assertions of labels and privileges are evaluated by the server,
which may then map the asserted values to other values, all according which may then map the asserted values to other values, all according
to server-side policy. See [NFSv4.2]. to server-side policy. See [NFSv4.2].
An option for enumerating server supported label format specifiers An option for enumerating server supported label format specifiers
(LFS) is provided. See [RFC7204] for detail. (LFS) is provided. See Section 2 and Section 3.3 in [RFC7204] for
detail.
Note that there is no RPCSEC_GSS_CREATE payload that is REQUIRED to
implement. RPCSEC_GSSv3 implementations are feature driven. Besides
implementing the RPCSEC_GSS_CREATE operation and payloads for the
desired features, all RPCSEC_GSSv3 implementation MUST implement:
o The new GSS version number (Section 2.2).
o The new reply verifier (Section 2.3).
o The new auth stat values (Section 2.6).
RPCSEC_GSSv3 targets implementing a desired feature must also
implement the RPCSEC_GSS_LIST operation, and the RPCSEC_GSS_CREATE
operation replies for unsupported features.
o For multi-principal authentication (Section 2.7.1.1), the target
indicates no support by not including a rgss3_gss_mp_auth value in
the rgss3_create_res.
o For channel bindings (Section 2.7.1.2) the target indicates no
support by not including a rgss3_chan_binding value in the
rgss3_create_res.
o For label assertions the target indicates no support by returning
the new RPCSEC_GSS_LABEL_PROBLEM auth stat (See Section 2.7.1.3).
o For structured privilege assertions the target indicates no
support by returning the new RPCSEC_GSS_UNKNOWN_MESSAGE auth stat
(See Section 2.7.1.4).
1.2. XDR Code Extraction 1.2. XDR Code Extraction
This document contains the External Data Representation (XDR) This document contains the External Data Representation (XDR)
([RFC4506]) definitions for the RPCSEC_GSSv3 protocol. The XDR ([RFC4506]) definitions for the RPCSEC_GSSv3 protocol. The XDR
description is provided in this document in a way that makes it description is provided in this document in a way that makes it
simple for the reader to extract into ready to compile form. The simple for the reader to extract into ready to compile form. The
reader can feed this document in the following shell script to reader can feed this document in the following shell script to
produce the machine readable XDR description of RPCSEC_GSSv3: produce the machine readable XDR description of RPCSEC_GSSv3:
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security context of the parent handle in all subsequent exchanges security context of the parent handle in all subsequent exchanges
that uses the child handle. that uses the child handle.
o An RPCSEC_GSSv3 child handle MUST NOT be used as the parent handle o An RPCSEC_GSSv3 child handle MUST NOT be used as the parent handle
in an RPCSEC_GSS3_CREATE control message. in an RPCSEC_GSS3_CREATE control message.
2.1. Compatibility with RPCSEC_GSSv2 2.1. Compatibility with RPCSEC_GSSv2
The functionality of RPCSEC_GSSv2 [RFC5403] is fully supported by The functionality of RPCSEC_GSSv2 [RFC5403] is fully supported by
RPCSEC_GSSv3 with the exception of the RPCSEC_GSS_BIND_CHANNEL RPCSEC_GSSv3 with the exception of the RPCSEC_GSS_BIND_CHANNEL
operation which is deprecated (see Section 2.5). operation which is not supported when RPCSEC_GSSv3 is in use (see
Section 2.5).
2.2. Version Negotiation 2.2. Version Negotiation
An initiator that supports version 3 of RPCSEC_GSS simply issues an An initiator that supports version 3 of RPCSEC_GSS simply issues an
RPCSEC_GSS request with the rgc_version field set to RPCSEC_GSS request with the rgc_version field set to
RPCSEC_GSS_VERS_3. If the target does not recognize RPCSEC_GSS_VERS_3. If the target does not recognize
RPCSEC_GSS_VERS_3, the target will return an RPC error per RPCSEC_GSS_VERS_3, the target will return an RPC error per
Section 5.1 of [RFC2203]. Section 5.1 of [RFC2203].
The initiator MUST NOT attempt to use an RPCSEC_GSS handle returned The initiator MUST NOT attempt to use an RPCSEC_GSS handle returned
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same target. same target.
2.3. New REPLY Verifier 2.3. New REPLY Verifier
A new reply verifier is needed for RPCSEC_GSSv3 because of a A new reply verifier is needed for RPCSEC_GSSv3 because of a
situation that arises from the use of the same GSS context by child situation that arises from the use of the same GSS context by child
and parent handles. Because the RPCSEC_GSSv3 child handle uses the and parent handles. Because the RPCSEC_GSSv3 child handle uses the
same GSS context as the parent handle, a child and parent same GSS context as the parent handle, a child and parent
RPCSEC_GSSv3 handle could have the same RPCSEC_GSS sequence numbers. RPCSEC_GSSv3 handle could have the same RPCSEC_GSS sequence numbers.
Since the reply verifier of previous versions of RPCSEC_GSS computes Since the reply verifier of previous versions of RPCSEC_GSS computes
a MIC on just the sequence number, this provides opportunities for a Message Integrity Code (MIC) on just the sequence number, this
man in the middle attacks. provides opportunities for man in the middle attacks.
This issue is addressed in RPCSEC_GSS version 3 by computing the This issue is addressed in RPCSEC_GSS version 3 by computing the
reply verifier using the exact same input as is used to compute the verifier using the exact same input as is used to compute the request
request verifier, except for the mtype is changed from CALL to REPLY. verifier, except that the mtype is changed from CALL to REPLY. The
The new reply verifier computes a MIC over the following RPC request new reply verifier computes a MIC over the following RPC reply header
header data: data:
unsigned int xid; unsigned int xid;
msg_type mtype; /* set to REPLY */ msg_type mtype; /* set to REPLY */
unsigned int rpcvers; unsigned int rpcvers;
unsigned int prog; unsigned int prog;
unsigned int vers; unsigned int vers;
unsigned int proc; unsigned int proc;
opaque_auth cred; /* captures the RPCSEC_GSS handle */ opaque_auth cred; /* captures the RPCSEC_GSS handle */
To clarify; Section 5.2.2 in RPCSEC_GSSv1 [RFC2203] describes the
context creation requests and notes that the credential seq_num and
service fields are undefined and both must be ignored by the server.
The context creation request credential handle field is NULL. The
new reply verifier MIC data for the context creation reply includes
whatever values are sent in the context creation request credential
seq_num, service, and handle fields.
2.4. XDR Code Preliminaries 2.4. XDR Code Preliminaries
The following code fragment replaces the corresponding preliminary
code shown in Figure 1 of [RFC5403]. The values in the code fragment
in Section 2.6 are additions to the auth_stat enumeration.
Subsequent code fragments are additions to the code for version 2
that support the new procedures defined in version 3.
<CODE BEGINS> <CODE BEGINS>
/// /* /// /*
/// * Copyright (c) 2013 IETF Trust and the persons /// * Copyright (c) 2013 IETF Trust and the persons
/// * identified as the document authors. All rights /// * identified as the document authors. All rights
/// * reserved. /// * reserved.
/// * /// *
/// * The document authors are identified in [RFC2203], /// * The document authors are identified in [RFC2203],
/// * [RFC5403], and [RFCxxxx]. /// * [RFC5403], and [RFCTBD].
/// * /// *
/// * Redistribution and use in source and binary forms, /// * Redistribution and use in source and binary forms,
/// * with or without modification, are permitted /// * with or without modification, are permitted
/// * provided that the following conditions are met: /// * provided that the following conditions are met:
/// * /// *
/// * o Redistributions of source code must retain the above /// * o Redistributions of source code must retain the above
/// * copyright notice, this list of conditions and the /// * copyright notice, this list of conditions and the
/// * following disclaimer. /// * following disclaimer.
/// * /// *
/// * o Redistributions in binary form must reproduce the /// * o Redistributions in binary form must reproduce the
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/// * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR /// * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
/// * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS /// * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
/// * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF /// * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
/// * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, /// * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
/// * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING /// * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
/// * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF /// * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
/// * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. /// * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
/// */ /// */
/// ///
/// /* /// /*
/// * This code was derived from [RFC2203]. Please /// * This code was derived from RFC2203, RFC5403, and RFCTBD.
/// * reproduce this note if possible. /// * Please reproduce this note if possible.
/// */ /// */
/// ///
/// enum rpc_gss_service_t { /// enum rpc_gss_service_t {
/// /* Note: the enumerated value for 0 is reserved. */ /// /* Note: the enumerated value for 0 is reserved. */
/// rpc_gss_svc_none = 1, /// rpc_gss_svc_none = 1,
/// rpc_gss_svc_integrity = 2, /// rpc_gss_svc_integrity = 2,
/// rpc_gss_svc_privacy = 3, /// rpc_gss_svc_privacy = 3,
/// rpc_gss_svc_channel_prot = 4 /// rpc_gss_svc_channel_prot = 4
/// }; /// };
/// ///
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As seen above, the RPCSEC_GSSv3 credential has the same format as the As seen above, the RPCSEC_GSSv3 credential has the same format as the
RPCSEC_GSSv1 [RFC2203] and RPCSEC_GSSv2 [RFC5403] credential. RPCSEC_GSSv1 [RFC2203] and RPCSEC_GSSv2 [RFC5403] credential.
Setting the rgc_version field to 3 indicates that the initiator and Setting the rgc_version field to 3 indicates that the initiator and
target support the new RPCSEC_GSSv3 control procedures. target support the new RPCSEC_GSSv3 control procedures.
2.5. RPCSEC_GSS_BIND_CHANNEL Operation 2.5. RPCSEC_GSS_BIND_CHANNEL Operation
RPCSEC_GSSv3 provides a channel binding assertion that replaces the RPCSEC_GSSv3 provides a channel binding assertion that replaces the
RPCSEC_GSSv2 RPCSEC_GSS_BIND_CHANNEL operation. RPCSEC_GSSv2 RPCSEC_GSS_BIND_CHANNEL operation.
RPCSEC_GSS_BIND_CHANNEL MUST NOT be used on RPCSEC_GSS version 3 The RPCSEC_GSS_BIND_CHANNEL operation is not supported on RPCSEC_GSS
handles. version 3 handles. If a server receives an RPCSEC_GSS_BIND_CHANNEL
operation on an RPCSEC_GSSv3 handle, it MUST return a reply status of
MSG_ACCEPTED with an acccept stat of PROC_UNAVAIL.
2.6. New auth_stat Values 2.6. New auth_stat Values
RPCSEC_GSSv3 requires the addition of several values to the auth_stat RPCSEC_GSSv3 requires the addition of several values to the auth_stat
enumerated type definition. The use of these new auth_stat values is enumerated type definition. The use of these new auth_stat values is
explained throughout this document. explained throughout this document.
enum auth_stat { enum auth_stat {
... ...
/* /*
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o Authorization assertions: labels and or privileges o Authorization assertions: labels and or privileges
The reply to this message consists of either an error or an The reply to this message consists of either an error or an
rgss3_create_res structure. As noted in Section 2.7.1.3 and rgss3_create_res structure. As noted in Section 2.7.1.3 and
Section 2.7.1.4 successful rgss3_assertions are enumerated in Section 2.7.1.4 successful rgss3_assertions are enumerated in
rcr_assertions, and are REQUIRED be enumerated in the same order as rcr_assertions, and are REQUIRED be enumerated in the same order as
they appeared in the rca_assertions argument. they appeared in the rca_assertions argument.
Upon successful RPCSEC_GSS_CREATE, both the client and the server Upon successful RPCSEC_GSS_CREATE, both the client and the server
SHOULD associate the resultant child rcr_handle context handle with need to associate the resultant child rcr_handle context handle with
the parent context handle in their GSS context caches so as to be the parent context handle in their GSS context caches so as to be
able to reference the parent context given the child context handle. able to reference the parent context given the child context handle.
RPCSEC_GSSv3 child handles MUST be destroyed upon the destruction of RPCSEC_GSSv3 child handles MUST be destroyed upon the destruction of
the associated parent handle. the associated parent handle.
Server implementation and policy MAY result in labels, privileges, Server implementation and policy MAY result in labels, privileges,
and identities being mapped to concepts and values that are local to and identities being mapped to concepts and values that are local to
the server. Server policies should take into account the identity of the server. Server policies should take into account the identity of
the client and/or user as authenticated via the GSS-API. the client and/or user as authenticated via the GSS-API.
skipping to change at page 11, line 41 skipping to change at page 12, line 38
<CODE ENDS> <CODE ENDS>
RPCSEC_GSSv3 clients MAY assert a multi-principal authentication of RPCSEC_GSSv3 clients MAY assert a multi-principal authentication of
the RPC client host principal and a user principal. This feature is the RPC client host principal and a user principal. This feature is
needed, for example, when an RPC client host wishes to use authority needed, for example, when an RPC client host wishes to use authority
assertions that the server may only grant if a user and an RPC client assertions that the server may only grant if a user and an RPC client
host are authenticated together to the server. Thus a server may host are authenticated together to the server. Thus a server may
refuse to grant requested authority to a user acting alone (e.g., via refuse to grant requested authority to a user acting alone (e.g., via
an unprivileged user-space program), or to an RPC client host acting an unprivileged user-space program), or to an RPC client host acting
alone (e.g. when an RPC client host is acting on behalf of a user) alone (e.g., when an RPC client host is acting on behalf of a user)
but may grant requested authority to an RPC client host acting on but may grant requested authority to an RPC client host acting on
behalf of a user if the server identifies the user and trusts the RPC behalf of a user if the server identifies the user and trusts the RPC
client host. client host.
It is assumed that an unprivileged user-space program would not have It is assumed that an unprivileged user-space program would not have
access to RPC client host credentials needed to establish a GSS-API access to RPC client host credentials needed to establish a GSS-API
security context authenticating the RPC client host to the server, security context authenticating the RPC client host to the server,
therefore an unprivileged user-space program could not create an therefore an unprivileged user-space program could not create an
RPCSEC_GSSv3 RPCSEC_GSS_CREATE message that successfully binds an RPC RPCSEC_GSSv3 RPCSEC_GSS_CREATE message that successfully binds an RPC
client host and a user security context. client host and a user security context.
skipping to change at page 12, line 8 skipping to change at page 13, line 4
It is assumed that an unprivileged user-space program would not have It is assumed that an unprivileged user-space program would not have
access to RPC client host credentials needed to establish a GSS-API access to RPC client host credentials needed to establish a GSS-API
security context authenticating the RPC client host to the server, security context authenticating the RPC client host to the server,
therefore an unprivileged user-space program could not create an therefore an unprivileged user-space program could not create an
RPCSEC_GSSv3 RPCSEC_GSS_CREATE message that successfully binds an RPC RPCSEC_GSSv3 RPCSEC_GSS_CREATE message that successfully binds an RPC
client host and a user security context. client host and a user security context.
In addition to the parent handle (Section 2), the multi-principal In addition to the parent handle (Section 2), the multi-principal
authentication call data has an RPCSEC_GSS version 3 handle authentication call data has an RPCSEC_GSS version 3 handle
referenced via the rgmp_handle field termed the "inner" handle. referenced via the rgmp_handle field termed the "inner" handle.
Clients using RPCSEC_GSSv3 multi-principal authentication MUST use an Clients using RPCSEC_GSSv3 multi-principal authentication MUST use an
RPCSEC_GSSv3 context handle that corresponds to a GSS-API security RPCSEC_GSSv3 context handle that corresponds to a GSS-API security
context that authenticates the RPC client host for the parent handle. context that authenticates the RPC client host for the parent handle.
The inner context handle it SHOULD use a context handle to For the inner context handle with RPCSEC_GSSv3 it MUST use a context
authenticate a user. The reverse (parent handle authenticates user, handle to authenticate a user. The reverse (parent handle
inner authenticates an RPC client host) MUST NOT be used. Other authenticates user, inner authenticates an RPC client host) MUST NOT
multi-principal parent and inner context handle uses might eventually be used. Other multi-principal parent and inner context handle uses
make sense, but would need to be introduced in a new revision of the might eventually make sense, but would need to be introduced in a new
RPCSEC_GSS protocol. revision of the RPCSEC_GSS protocol.
The child context handle returned by a successful multi-principal The child context handle returned by a successful multi-principal
assertion binds the inner RPCSEC_GSSv3 context handle to the parent assertion binds the inner RPCSEC_GSSv3 context handle to the parent
RPCSEC_GSS context and MUST be treated by servers as authenticating RPCSEC_GSS context and MUST be treated by servers as authenticating
the GSS-API initiator principal authenticated by the inner context the GSS-API initiator principal authenticated by the inner context
handle's GSS-API security context. This principal may be mapped to a handle's GSS-API security context. This principal may be mapped to a
server-side notion of user or principal. server-side notion of user or principal.
Multi-principal binding is done by including an assertion of type Multi-principal binding is done by including an assertion of type
rgss3_gss_mp_auth in the RPCSEC_GSS_CREATE rgss3_create_args call rgss3_gss_mp_auth in the RPCSEC_GSS_CREATE rgss3_create_args call
data. The inner context handle is placed in the rgmp_handle field. data. The inner context handle is placed in the rgmp_handle field.
A MIC of the RPC call header up to and including the credential is A MIC of the RPC call header up to and including the credential is
computed using the GSS-API security context associated with the inner computed using the GSS-API security context associated with the inner
context handle is placed in rgmp_rpcheader_mic field. context handle and is placed in rgmp_rpcheader_mic field.
The target verifies the multi-principal authentication by first The target verifies the multi-principal authentication by first
confirming that the parent context used is an RPC client host confirming that the parent context used is an RPC client host
context, and then verifies the rgmp_rpcheader_mic using the GSS-API context, and then verifies the rgmp_rpcheader_mic using the GSS-API
security context associated with the rgmp_handle field. security context associated with the rgmp_handle field.
On a successful verification, the rgss3_gss_mp_auth field in the On a successful verification, the rgss3_gss_mp_auth field in the
rgss3_create_res reply MUST be filled in with the inner RPCSEC_GSSv3 rgss3_create_res reply MUST be filled in with the inner RPCSEC_GSSv3
context handle as the rgmp_handle, and a MIC computed over the RPC context handle as the rgmp_handle, and a MIC computed over the RPC
reply header (see section Section 2.3) using the GSS-API security reply header (see section Section 2.3) using the GSS-API security
skipping to change at page 15, line 17 skipping to change at page 16, line 17
/// }; /// };
/// ///
/// struct rgss3_lfs { /// struct rgss3_lfs {
/// unsigned int rlf_lfs_id; /// unsigned int rlf_lfs_id;
/// unsigned int rlf_pi_id; /// unsigned int rlf_pi_id;
/// }; /// };
/// ///
<CODE ENDS> <CODE ENDS>
Mandatory Access Control (MAC) label systems consist of two basic The client discovers which label format specifiers (LFS) the server
inputs to the MAC policy engine: subject labels and object labels. supports via the RPCSEC_GSS_LIST control message. Full mode MAC is
File object labels are communicated via the NFSv4.2 sec_label enabled when an RPCSEC_GSS_CREATE process subject label assertion is
described in Section 12.2.2 of [NFSv4.2]. RPCSEC_GSSv3 label combined with a file object label provided by the NFSv4.2 sec_label
assertions assert a set of client process subject labels on the attribute.
server process handling a request.
The client discovers which subject labels the server supports via the
RPCSEC_GSS_LIST control message. Asserting server supported subject
labels via RPCSEC_GSS_CREATE enables full mode labeling when it is
combined with file object labels communicated via the the NFSv4.2
sec_label attribute.
Label encoding is specified to mirror the NFSv4.2 sec_label attribute Label encoding is specified to mirror the NFSv4.2 sec_label attribute
described in Section 12.2.2 of [NFSv4.2]. The label format specifier described in Section 12.2.4 of [NFSv4.2]. The label format specifier
(LFS) is an identifier used to describe the syntactic format of the (LFS) is an identifier used by the client to establish the syntactic
security label and the semantic meaning of its components. The format of the security label and the semantic meaning of its
policy identifier (PI) is an optional part of the definition of an components. The policy identifier (PI) is an optional part of the
LFS which allows for clients and server to identify specific security definition of an LFS which allows for clients and server to identify
policies. The opaque label field of rgss3_label is dependent on the specific security policies. The opaque label field of rgss3_label is
MAC model to interpret and enforce. dependent on the MAC model to interpret and enforce.
If a subject label itself requires privacy protection (i.e., that the If a label itself requires privacy protection (i.e., that the user
user can assert that label is a secret) then the client MUST use the can assert that label is a secret) then the client MUST use the
rpc_gss_svc_privacy protection service for the RPCSEC_GSS_CREATE rpc_gss_svc_privacy protection service for the RPCSEC_GSS_CREATE
request. request.
RPCSEC_GSSv3 clients MAY assert a server security subject label in RPCSEC_GSSv3 clients MAY assert a server security label in some LSF
some LSF by binding a label assertion to the RPCSEC_GSSv3 context by binding a label assertion to the RPCSEC_GSSv3 context handle.
handle. This is done by including an assertion of type rgss3_label This is done by including an assertion of type rgss3_label in the
in the RPCSEC_GSS_CREATE rgss3_create_args rca_assertions call data. RPCSEC_GSS_CREATE rgss3_create_args rca_assertions call data.
Servers that support labeling in the requested LFS MAY map the Servers that support labeling in the requested LFS MAY map the
requested subject label to different subject label as a result of requested subject label to a different subject label as a result of
server-side policy evaluation. server-side policy evaluation.
The subject labels that are accepted by the target and bound to the The labels that are accepted by the target and bound to the
RPCSEC_GSSv3 context MUST be enumerated in the rcr_assertions field RPCSEC_GSSv3 context MUST be enumerated in the rcr_assertions field
of the rgss3_create_res RPCSEC_GSS_CREATE reply. of the rgss3_create_res RPCSEC_GSS_CREATE reply.
Servers that do not support labeling or that do not support the Servers that do not support labeling or that do not support the
requested LFS reject the label assertion with a reply status of requested LFS reject the label assertion with a reply status of
MSG_DENIED, a reject_status of AUTH_ERROR, and an auth_stat of MSG_DENIED, a reject_status of AUTH_ERROR, and an auth_stat of
RPCSEC_GSS_LABEL_PROBLEM. RPCSEC_GSS_LABEL_PROBLEM.
2.7.1.4. Structured Privilege Assertions 2.7.1.4. Structured Privilege Assertions
skipping to change at page 16, line 48 skipping to change at page 17, line 41
not recognize the assertion is rejected with a reply status of not recognize the assertion is rejected with a reply status of
MSG_DENIED, a reject_status of AUTH_ERROR, and an auth_stat of MSG_DENIED, a reject_status of AUTH_ERROR, and an auth_stat of
RPCSEC_GSS_UNKNOWN_MESSAGE. RPCSEC_GSS_UNKNOWN_MESSAGE.
If a server receives a structured privilege assertion that it fails If a server receives a structured privilege assertion that it fails
to verify according to the requirements of the RPC application to verify according to the requirements of the RPC application
defined behavior, the assertion is rejected with a reply status of defined behavior, the assertion is rejected with a reply status of
MSG_DENIED, a reject_status of AUTH_ERROR, and an auth_stat of MSG_DENIED, a reject_status of AUTH_ERROR, and an auth_stat of
RPCSEC_GSS_PRIVILEGE_PROBLEM. RPCSEC_GSS_PRIVILEGE_PROBLEM.
Section 3.4.1.2. "Inter-Server Copy with RPCSEC_GSSv3" of [NFSv4.2] Section 4.10.1.1. "Inter-Server Copy via ONC RPC with RPCSEC_GSSv3"
shows an example of structured privilege definition and use. of [NFSv4.2] shows an example of structured privilege definition and
use.
2.7.2. New Control Procedure - RPCSEC_GSS_LIST 2.7.2. New Control Procedure - RPCSEC_GSS_LIST
<CODE BEGINS> <CODE BEGINS>
/// enum rgss3_list_item { /// enum rgss3_list_item {
/// LABEL = 0, /// LABEL = 0,
/// PRIVS = 1 /// PRIVS = 1
/// }; /// };
/// ///
/// struct rgss3_list_args { /// struct rgss3_list_args {
/// rgss3_list_item rla_list_what<>; /// rgss3_list_item rla_list_what<>;
/// }; /// };
/// ///
/// union rgss3_list_item_u /// union rgss3_list_item_u
skipping to change at page 17, line 32 skipping to change at page 18, line 27
/// case PRIVS: /// case PRIVS:
/// rgss3_privs rli_privs<>; /// rgss3_privs rli_privs<>;
/// }; /// };
/// ///
/// typedef rgss3_list_item_u rgss3_list_res<>; /// typedef rgss3_list_item_u rgss3_list_res<>;
/// ///
<CODE ENDS> <CODE ENDS>
The call data for an RPCSEC_GSS_LIST request consists of a list of The call data for an RPCSEC_GSS_LIST request consists of a list of
integers (rla_list_what) indicating what assertions to be listed, and integers (rla_list_what) indicating what assertions are to be listed,
the reply consists of an error or the requested list. and the reply consists of an error or the requested list.
The result of requesting a list of rgss3_list_item LABEL is a list of The result of requesting a list of rgss3_list_item LABEL is a list of
LFSs supported by the server. The client can then use the LFS list LFSs supported by the server. The client can then use the LFS list
to assert labels via the RPCSEC_GSS_CREATE label assertions. See to assert labels via the RPCSEC_GSS_CREATE label assertions. See
Section 2.7.1.3. Section 2.7.1.3.
2.8. Extensibility 2.8. Extensibility
Assertion types may be added in the future by adding arms to the Assertion types may be added in the future by adding arms to the
'rgss3_assertion_u' union. Other assertion types are described 'rgss3_assertion_u' union. Examples of other potential assertion
elsewhere and include: types include:
o Client-side assertions of identity: o Client-side assertions of identity:
* Primary client/user identity * Primary client/user identity
* Supplementary group memberships of the client/user, including * Supplementary group memberships of the client/user, including
support for specifying deltas to the membership list as seen on support for specifying deltas to the membership list as seen on
the server. the server.
3. Operational Recommendation for Deployment 3. Operational Recommendation for Deployment
skipping to change at page 19, line 10 skipping to change at page 20, line 10
associate multiple RPCSEC_GSS handles with a single SSV GSS context. associate multiple RPCSEC_GSS handles with a single SSV GSS context.
RPCSEC_GSSv3 handles will work well with SSV in that the man-in-the- RPCSEC_GSSv3 handles will work well with SSV in that the man-in-the-
middle attacks described in Section 2.10.10 [RFC5661] are solved by middle attacks described in Section 2.10.10 [RFC5661] are solved by
the new reply verifier (Section 2.3). Using an RPCSEC_GSSv3 handle the new reply verifier (Section 2.3). Using an RPCSEC_GSSv3 handle
backed by a GSS-SSV mechanism context as a parent handle in an backed by a GSS-SSV mechanism context as a parent handle in an
RPCSEC_GSS_CREATE call while permitted is complicated by the lifetime RPCSEC_GSS_CREATE call while permitted is complicated by the lifetime
rules of SSV contexts and their associated RPCSEC_GSS handles. rules of SSV contexts and their associated RPCSEC_GSS handles.
5. IANA Considerations 5. IANA Considerations
There are no IANA considerations in this document. IANA request #884160 is being processed for the new RPC authenticaion
status numbers in Section 2.6.
6. References 6. References
6.1. Normative References 6.1. Normative References
[NFSv4.2] Haynes, T., "NFS Version 4 Minor Version 2", draft-ietf- [NFSv4.2] Haynes, T., "NFS Version 4 Minor Version 2", draft-ietf-
nfsv4-minorversion2-29 (Work In Progress), December 2014. nfsv4-minorversion2-29 (Work In Progress), December 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997. Requirement Levels", RFC 2119, March 1997.
skipping to change at page 19, line 41 skipping to change at page 20, line 42
[RFC5056] Williams, N., "On the Use of Channel Bindings to Secure [RFC5056] Williams, N., "On the Use of Channel Bindings to Secure
Channels", RFC 5056, November 2007. Channels", RFC 5056, November 2007.
[RFC5403] Eisler, M., "RPCSEC_GSS Version 2", RFC 5403, February [RFC5403] Eisler, M., "RPCSEC_GSS Version 2", RFC 5403, February
2009. 2009.
[RFC5661] Shepler, S., Eisler, M., and D. Noveck, "Network File [RFC5661] Shepler, S., Eisler, M., and D. Noveck, "Network File
System (NFS) Version 4 Minor Version 1 Protocol", RFC System (NFS) Version 4 Minor Version 1 Protocol", RFC
5661, January 2010. 5661, January 2010.
[RFC7204] Haynes, T., "Requirements for Labeled NFS", RFC 7204,
April 2014.
6.2. Informative References 6.2. Informative References
[AFS-RXGK] [AFS-RXGK]
Wilkinson, S. and B. Kaduk, "Integrating rxgk with AFS", Wilkinson, S. and B. Kaduk, "Integrating rxgk with AFS",
draft-wilkinson-afs3-rxgk-afs (work in progress), April draft-wilkinson-afs3-rxgk-afs (work in progress), April
2014. 2014.
[BL73] Bell, D. and L. LaPadula, "Secure Computer Systems: [BL73] Bell, D. and L. LaPadula, "Secure Computer Systems:
Mathematical Foundations and Model", Technical Report Mathematical Foundations and Model", Technical Report
M74-244, The MITRE Corporation Bedford, MA, May 1973. M74-244, The MITRE Corporation Bedford, MA, May 1973.
[RFC2401] Kent, S. and R. Atkinson, "Security Architecture for the [RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 2401, November 1998. Internet Protocol", RFC 4301, December 2005.
[RFC4949] Shirley, R., "Internet Security Glossary, Version 2", RFC
4949, August 2007.
[RFC7204] Haynes, T., "Requirements for Labeled NFS", RFC 7204,
April 2014.
Appendix A. Acknowledgments Appendix A. Acknowledgments
Andy Adamson would like to thank NetApp, Inc. for its funding of his Andy Adamson would like to thank NetApp, Inc. for its funding of his
time on this project. time on this project.
We thank Lars Eggert, Mike Eisler, Ben Kaduk, Bruce Fields, Tom We thank Lars Eggert, Mike Eisler, Ben Kaduk, Bruce Fields, Tom
Haynes, and Dave Noveck for their most helpful reviews. Haynes, and Dave Noveck for their most helpful reviews.
Appendix B. RFC Editor Notes Appendix B. RFC Editor Notes
[RFC Editor: please remove this section prior to publishing this [RFC Editor: please remove this section prior to publishing this
document as an RFC] document as an RFC]
[RFC Editor: prior to publishing this document as an RFC, please [RFC Editor: prior to publishing this document as an RFC, please
replace all occurrences of RFCTBD10 with RFCxxxx where xxxx is the replace all occurrences of RFCTBD with RFCxxxx where xxxx is the RFC
RFC number of this document] number of this document]
Authors' Addresses Authors' Addresses
William A. (Andy) Adamson William A. (Andy) Adamson
NetApp NetApp
3629 Wagner Ridge Ct 3629 Wagner Ridge Ct
Ann Arbor, MI 48103 Ann Arbor, MI 48103
USA USA
Phone: +1 734 665 1204 Phone: +1 734 665 1204
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