draft-ietf-nfsv4-rpcsec-gssv3-08.txt   draft-ietf-nfsv4-rpcsec-gssv3-09.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: December 29, 2014 Cryptonector Expires: May 22, 2015 Cryptonector
June 27, 2014 November 18, 2014
Remote Procedure Call (RPC) Security Version 3 Remote Procedure Call (RPC) Security Version 3
draft-ietf-nfsv4-rpcsec-gssv3-08.txt draft-ietf-nfsv4-rpcsec-gssv3-09.txt
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 for multi- security protocol (RPCSEC_GSS). This protocol provides for multi-
principal authentication of client hosts and user principals to principal authentication of client hosts and user principals to
server (constructed by generic composition), security label 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 [1]. document are to be interpreted as described in RFC 2119 [1].
Status of this Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
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 December 29, 2014. This Internet-Draft will expire on May 22, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction and Motivation . . . . . . . . . . . . . . . . . 3 1. Introduction and Motivation . . . . . . . . . . . . . . . . . 2
2. The RPCSEC_GSSv3 Protocol . . . . . . . . . . . . . . . . . . 4 2. The RPCSEC_GSSv3 Protocol . . . . . . . . . . . . . . . . . . 4
2.1. Compatibility with RPCSEC_GSSv2 . . . . . . . . . . . . . 5 2.1. Compatibility with RPCSEC_GSSv2 . . . . . . . . . . . . . 5
2.2. Version Negotiation . . . . . . . . . . . . . . . . . . . 5 2.2. Version Negotiation . . . . . . . . . . . . . . . . . . . 5
2.3. New REPLY verifier . . . . . . . . . . . . . . . . . . . . 5 2.3. New REPLY verifier . . . . . . . . . . . . . . . . . . . 5
2.4. New Version Number . . . . . . . . . . . . . . . . . . . . 6 2.4. New Version Number . . . . . . . . . . . . . . . . . . . 6
2.5. New auth_stat Values . . . . . . . . . . . . . . . . . . . 8 2.5. RPCSEC_GSS_BIND_CHANNEL Operation Deprecated . . . . . . 8
2.6. New Control Procedures . . . . . . . . . . . . . . . . . . 8 2.6. New auth_stat Values . . . . . . . . . . . . . . . . . . 8
2.6.1. New Control Procedure - RPCSEC_GSS_CREATE . . . . . . 9 2.7. New Control Procedures . . . . . . . . . . . . . . . . . 8
2.6.2. New Control Procedure - RPCSEC_GSS_LIST . . . . . . . 15 2.7.1. New Control Procedure - RPCSEC_GSS_CREATE . . . . . . 9
2.7. Extensibility . . . . . . . . . . . . . . . . . . . . . . 16 2.7.2. New Control Procedure - RPCSEC_GSS_LIST . . . . . . . 16
3. Operational Recommendation for Deployment . . . . . . . . . . 17 2.8. Extensibility . . . . . . . . . . . . . . . . . . . . . . 16
4. Security Considerations . . . . . . . . . . . . . . . . . . . 17 3. Operational Recommendation for Deployment . . . . . . . . . . 17
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 4. Security Considerations . . . . . . . . . . . . . . . . . . . 17
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
6.1. Normative References . . . . . . . . . . . . . . . . . . . 18 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.2. Informative References . . . . . . . . . . . . . . . . . . 19 6.1. Normative References . . . . . . . . . . . . . . . . . . 18
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 19 6.2. Informative References . . . . . . . . . . . . . . . . . 18
Appendix B. RFC Editor Notes . . . . . . . . . . . . . . . . . . 19 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19 Appendix B. RFC Editor Notes . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction and Motivation 1. Introduction and Motivation
The original RPCSEC_GSS protocol [2] provided for authentication of The original RPCSEC_GSS protocol [2] provided for authentication of
RPC clients and servers to each other using the Generic Security RPC clients and servers to each other using the Generic Security
Services Application Programming Interface (GSS-API) [3]. The second Services Application Programming Interface (GSS-API) [3]. The second
version of RPCSEC_GSS [4] added support for channel bindings [5]. version of RPCSEC_GSS [8] added support for channel bindings [6].
We find that GSS-API mechanisms are insufficient for communicating We find that 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,
but it seems be far simpler to address it at the application layer, but it seems be far simpler to address it at the application layer,
namely, in this case, RPCSEC_GSS. namely, in this case, RPCSEC_GSS.
The motivation for RPCSEC_GSSv3 is to add support for labeled A major motivation for RPCSEC_GSSv3 is to add support for labeled
security and server-side copy for NFSv4. security and server-side copy for NFSv4.
Labeled NFS (see Section 8 of [6]) uses the subject label provided by Labeled NFS (see Section 8 of [5]) uses the subject label provided by
the client via the RPCSEC_GSSv3 layer to enforce MAC access to 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 objects owned by the server to enable server guest mode or full mode
labeled NFS. labeled NFS.
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 [6]), the user first secures access to both source Section 3.4.1 of [5]), the user first secures access to both source
and destination files, and then uses RPCSEC_GSSv3 multi-principal and destination files, and then uses NFSv4.2 defined RPCSEC_GSSv3
authentication and structured privileges to authorize the destination structured privileges to authorize the destination to copy the file
to 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
poisoning attacks on the client cache by a user. As described in
Section 7 of [14], multi-user machines with a single cache manager
can fetch and cache data on a users' behalf, and re-display it for
another user from the cache without re-fetching the data from the
server. The initial data acquisition is authenticated by the first
user's credentials, and if only that user's credentials are used, it
may be possible for a 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
of privilege information for processes running with more (or even
with less) privilege than the user normally would be accorded.
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 [4], except that the RPCSEC_GSSv3 is the same as RPCSEC_GSSv2 [8], except that the
following assertions of authority have been added. following assertions of authority have been added.
o Security labels for multi-level, type enforcement, and other o Security labels for multi-level, type enforcement, and other
labeled security models. See [9], [10], [11], [6] and [12]. labeled security models. See [10], [11], [12], [5] and [9].
o Application-specific structured privileges. For an example see o Application-specific structured privileges. For an example see
server-side copy [6]. server-side copy [5].
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. For an example see server done by binding two RPCSEC_GSS handles.
server-side copy [6].
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. to server-side policy.
We add an option for enumerating server supported label format We add an option for enumerating server supported label format
specifiers (LFS). The LFS and Label Format Registry are described in specifiers (LFS). The LFS and Label Format Registry are described in
detail in [13]. detail in [13].
skipping to change at page 4, line 37 skipping to change at page 4, line 37
sh extract.sh < spec.txt > rpcsec_gss_v3.x sh extract.sh < spec.txt > rpcsec_gss_v3.x
<CODE ENDS> <CODE ENDS>
The effect of the script is to remove leading white space from each The effect of the script is to remove leading white space from each
line, plus a sentinel sequence of "///". line, plus a sentinel sequence of "///".
2. The RPCSEC_GSSv3 Protocol 2. The RPCSEC_GSSv3 Protocol
RPCSEC_GSSv3 is the same as RPCSEC_GSSv2 [4], except that support for RPCSEC_GSSv3 is the same as RPCSEC_GSSv2 [8], except that support for
assertions has been added. The entire RPCSEC_GSSv3 protocol is not assertions has been added. The entire RPCSEC_GSSv3 protocol is not
presented. Instead the differences between RPCSEC_GSSv3 and presented. Instead the differences between RPCSEC_GSSv3 and
RPCSEC_GSSv2 are shown. RPCSEC_GSSv2 are shown.
RPCSEC_GSSv3 is patterned as follows: RPCSEC_GSSv3 is patterned as follows:
o A client uses an existing RPCSEC_GSSv3 context handle to protect o A client uses an existing RPCSEC_GSSv3 context handle to protect
RPCSEC_GSSv3 exchanges, this will be termed the "parent" handle. RPCSEC_GSSv3 exchanges, this will be termed the "parent" handle.
o The server issues a "child" RPCSEC_GSSv3 handle in the o The server issues a "child" RPCSEC_GSSv3 handle in the
RPCSEC_GSS_CREATE response which uses the underlying GSS-API RPCSEC_GSS_CREATE response which uses the underlying GSS-API
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 [4] is fully supported by The functionality of RPCSEC_GSSv2 [8] is fully supported by
RPCSEC_GSSv3. RPCSEC_GSSv3 with the exception of the RPCSEC_GSS_BIND_CHANNEL
operation which is deprecated (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 Section RPCSEC_GSS_VERS_3, the target will return an RPC error per
5.1 of [2]. Section 5.1 of [2].
The initiator MUST NOT attempt to use an RPCSEC_GSS handle returned The initiator MUST NOT attempt to use an RPCSEC_GSS handle returned
by version 3 of a target with version 1 or version 2 of the same by version 3 of a target with version 1 or version 2 of the same
target. The initiator MUST NOT attempt to use an RPCSEC_GSS handle target. The initiator MUST NOT attempt to use an RPCSEC_GSS handle
returned by version 1 or version 2 of a target with version 3 of the returned by version 1 or version 2 of a target with version 3 of the
same target. same target.
2.3. New REPLY verifier 2.3. New REPLY verifier
The RPCSEC_GSSv3 child handle uses the same GSS context as the parent The RPCSEC_GSSv3 child handle uses the same GSS context as the parent
handle. Since a child and parent RPCSEC_GSSv3 handle could have the handle. Since a child and parent RPCSEC_GSSv3 handle could have the
same RPCSEC_GSS sequence numbers, and the verifier of RPCSEC_GSS same RPCSEC_GSS sequence numbers, and the verifier of RPCSEC_GSS
replies computes a MIC on just the sequence number, this provides replies computes a MIC on just the sequence number, this provides
opportunities for man in the middle attacks. opportunities for man in the middle attacks.
This is easily addressed: RPCSEC_GSS version 3 MUST change the This is easily addressed: RPCSEC_GSS version 3 changes the verifier
verifier of the reply to compute the verifier using the exact same of the reply to compute the verifier using the exact same input as
input as that is used for verifier of the request, except for the that is used for verifier of the request, except for the mtype change
mtype change from CALL to REPLY. The new reply verifier computes a from CALL to REPLY. The new reply verifier computes a MIC over the
MIC over the following data: following RPC reply header 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 */
2.4. New Version Number 2.4. New Version Number
skipping to change at page 7, line 49 skipping to change at page 7, line 49
/// case RPCSEC_GSS_VERS_1: /// case RPCSEC_GSS_VERS_1:
/// case RPCSEC_GSS_VERS_2: /// case RPCSEC_GSS_VERS_2:
/// case RPCSEC_GSS_VERS_3: /* new */ /// case RPCSEC_GSS_VERS_3: /* new */
/// rpc_gss_cred_vers_1_t rgc_cred_v1; /// rpc_gss_cred_vers_1_t rgc_cred_v1;
/// }; /// };
/// ///
<CODE ENDS> <CODE ENDS>
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 [2] and RPCSEC_GSSv2 [4] credential. Setting the RPCSEC_GSSv1 [2] and RPCSEC_GSSv2 [8] credential. Setting the
rgc_version field to 3 indicates that the initiator and target rgc_version field to 3 indicates that the initiator and target
support the new RPCSEC_GSSv3 control procedures. support the new RPCSEC_GSSv3 control procedures.
2.5. New auth_stat Values 2.5. RPCSEC_GSS_BIND_CHANNEL Operation Deprecated
RPCSEC_GSSv3 provides a channel binding assertion that replaces the
RPCSEC_GSSv2 RPCSEC_GSS_BIND_CHANNEL operation.
RPCSEC_GSS_BIND_CHANNEL MUST NOT be used on RPCSEC_GSS version 3
handles.
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 each of these new auth_stat enumerated type definition. The use of each of these new auth_stat
values is explained later in this document. values is explained later in this document.
enum auth_stat { enum auth_stat {
... ...
/* /*
* RPCSEC_GSSv3 errors * RPCSEC_GSSv3 errors
*/ */
RPCSEC_GSS_INNER_CREDPROBLEM = 15, RPCSEC_GSS_INNER_CREDPROBLEM = 15,
RPCSEC_GSS_LABEL_PROBLEM = 16, RPCSEC_GSS_LABEL_PROBLEM = 16,
RPCSEC_GSS_PRIVILEGE_PROBLEM = 17, RPCSEC_GSS_PRIVILEGE_PROBLEM = 17,
RPCSEC_GSS_UNKNOWN_MESSAGE = 18 RPCSEC_GSS_UNKNOWN_MESSAGE = 18
}; };
2.6. New Control Procedures 2.7. New Control Procedures
There are two new RPCSEC_GSSv3 control procedures: RPCSEC_GSS_CREATE, There are two new RPCSEC_GSSv3 control procedures: RPCSEC_GSS_CREATE,
RPCSEC_GSS_LIST. RPCSEC_GSS_LIST.
The RPCSEC_GSS_CREATE procedure binds any combination of assertions: The RPCSEC_GSS_CREATE procedure binds any combination of assertions:
multi-principal authentication, labels, structured privileges, or multi-principal authentication, labels, structured privileges, or
channel bindings to a new RPCSEC_GSSv3 context returned in the channel bindings to a new RPCSEC_GSSv3 context returned in the
rgss3_create_res rcr_handle field. rgss3_create_res rcr_handle field.
The RPCSEC_GSS_LIST procedure queries the target for supported The RPCSEC_GSS_LIST procedure queries the target for supported
assertions. assertions.
RPCSEC_GSS version 3 control messages are similar to the RPCSEC_GSS RPCSEC_GSS version 3 control messages are similar to the RPCSEC_GSS
version 1 and version2 RPCSEC_GSS_DESTROY control message (see version 1 and version 2 RPCSEC_GSS_DESTROY control message (see
section 5.4 [2]) in that the sequence number in the request must be 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. As in valid, and the header checksum in the verifier must be valid. As in
RPCSEC_GSS version 1 and version 2, the RPCSEC_GSSv version 3 control RPCSEC_GSS version 1 and version 2, the RPCSEC_GSSv version 3 control
messages may contain call data following the verifier in the body of messages may contain call data following the verifier in the body of
the NULLPROC procedure. In other words, they look a lot like an the NULLPROC procedure. In other words, they look a lot like an
RPCSEC_GSS data message with the header procedure set to NULLPROC. RPCSEC_GSS data message with the header procedure set to NULLPROC.
The client MUST use one of the following security services to protect The client MUST use one of the following security services to protect
the RPCSEC_GSS_CREATE or RPCSEC_GSS_LIST control message: the RPCSEC_GSS_CREATE or RPCSEC_GSS_LIST control message:
o rpc_gss_svc_channel_prot (see RPCSEC_GSSv2 [4]) o rpc_gss_svc_channel_prot (see RPCSEC_GSSv2 [8])
o rpc_gss_svc_integrity o rpc_gss_svc_integrity
o rpc_gss_svc_privacy o rpc_gss_svc_privacy
Specifically the client MUST NOT use rpc_gss_svc_none. Specifically the client MUST NOT use rpc_gss_svc_none.
2.6.1. New Control Procedure - RPCSEC_GSS_CREATE 2.7.1. New Control Procedure - RPCSEC_GSS_CREATE
<CODE BEGINS> <CODE BEGINS>
/// struct rgss3_create_args { /// struct rgss3_create_args {
/// rgss3_gss_mp_auth *rca_mp_auth; /// rgss3_gss_mp_auth *rca_mp_auth;
/// rgss3_chan_binding *rca_chan_bind_mic; /// rgss3_chan_binding *rca_chan_bind_mic;
/// rgss3_assertion rca_assertions<>; /// rgss3_assertion rca_assertions<>;
/// }; /// };
/// ///
/// struct rgss3_create_res { /// struct rgss3_create_res {
skipping to change at page 9, line 39 skipping to change at page 9, line 46
/// switch (rgss3_assertion_type atype) { /// switch (rgss3_assertion_type atype) {
/// case LABEL: /// case LABEL:
/// rgss3_label rau_label; /// rgss3_label rau_label;
/// case PRIVS: /// case PRIVS:
/// rgss3_privs rau_privs; /// rgss3_privs rau_privs;
/// default: /// default:
/// opaque rau_ext<>; /// opaque rau_ext<>;
/// }; /// };
/// ///
/// struct rgss3_assertion { /// struct rgss3_assertion {
/// bool ra_critical;
/// rgss3_assertion_u ra_assertion; /// rgss3_assertion_u ra_assertion;
/// }; /// };
/// ///
<CODE ENDS> <CODE ENDS>
The call data for an RPCSEC_GSS_CREATE request consists of an The call data for an RPCSEC_GSS_CREATE request consists of an
rgss3_create_args which binds one or more items of several kinds to rgss3_create_args which binds one or more items of several kinds to
the returned rcr_handle RPCSEC_GSSv3 context handle called the the returned rcr_handle RPCSEC_GSSv3 context handle called the
"child" handle: "child" handle:
o Multi-principal authentication: another RPCSEC_GSS context handle o Multi-principal authentication: another RPCSEC_GSS context handle
o Authorization assertions: labels and or privileges
o A channel binding o A channel binding
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. rgss3_create_res structure.
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 SHOULD 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.
2.6.1.1. Multi-principal Authentication 2.7.1.1. Multi-principal Authentication
<CODE BEGINS> <CODE BEGINS>
/// ///
/// struct rgss3_gss_mp_auth { /// struct rgss3_gss_mp_auth {
/// opaque rgmp_handle<>; /* inner handle */ /// opaque rgmp_handle<>; /* inner handle */
/// opaque rgmp_nonce<>; /// opaque rgmp_rpcheader_mic<>;
/// opaque rgmp_nounc_mic<>;
/// }; /// };
/// ///
<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 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 a client wishes to use authority assertions needed, for example, when an RPC client host wishes to use authority
that the server may only grant if a user and a client are assertions that the server may only grant if a user and an RPC client
authenticated together to the server. Thus a server may refuse to host are authenticated together to the server. Thus a server may
grant requested authority to a user acting alone (e.g., via an refuse to grant requested authority to a user acting alone (e.g., via
unprivileged user-space program), or to a client acting alone (e.g. an unprivileged user-space program), or to an RPC client host acting
when a client is acting on behalf of a user) but may grant requested alone (e.g. when an RPC client host is acting on behalf of a user)
authority to a client acting on behalf of a user if the server but may grant requested authority to an RPC client host acting on
identifies the user and trusts the client. behalf of a user if the server identifies the user and trusts the RPC
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 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 client to the server, therefore security context authenticating the RPC client host to the server,
an unprivileged user-space program could not create an RPCSEC_GSSv3 therefore an unprivileged user-space program could not create an
RPCSEC_GSS_CREATE message that successfully binds a client and a user RPCSEC_GSSv3 RPCSEC_GSS_CREATE message that successfully binds an RPC
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 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 The inner context handle it SHOULD use a context handle to
authenticate a user. The reverse (parent handle authenticates user, authenticate a user. The reverse (parent handle authenticates user,
inner authenticates client) MUST NOT be used. Other multi-principal inner authenticates an RPC client host) MUST NOT be used. Other
parent and inner context handle uses might eventually make sense. multi-principal parent and inner context handle uses might eventually
make sense, but would need to be introduced in a new revision of the
RPCSEC_GSS protocol.
An inner RPCSEC_GSSv3 context handle that is bound to a parent The child context handle returned by a successful multi-principal
RPCSEC_GSS context through multi-principal authentication MUST be assertion binds the inner RPCSEC_GSSv3 context handle to the parent
treated by servers as authenticating the GSS-API initiator principal RPCSEC_GSS context and MUST be treated by servers as authenticating
authenticated by the inner context handle's GSS-API security context. the GSS-API initiator principal authenticated by the inner context
This principal may be mapped to a server-side notion of user or handle's GSS-API security context. This principal may be mapped to a
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 place in the rbmp_handle field. A data. The inner context handle is placed in the rgmp_handle field.
nonce and a MIC of that nounce created using the GSS-API security A MIC of the RPC call header up to and including the credential is
context associated with the inner handle is also provided. computed using the GSS-API security context associated with the inner
context handle is placed in rgmp_rpcheader_mic field.
The target verifies the multi-principal authentication by verifying The target verifies the multi-principal authentication by first
the rgmp_nouce_mic. On a successful reply, the rgss3_gss_mp_auth confirming that the parent context used is an RPC client host
field in the rgss3_create_res reply uses the parent RPCSEC_GSSv3 context, and then verifies the rgmp_rpcheader_mic using the GSS-API
context as the rgmp_handle, the same rgmp_nounce as was sent in the security context associated with the rgmp_handle field.
call data with the rgmp_nounce_mic created using the GSS-API security
context associate with the parent handle. Verification of the On a successful verification, the rgss3_gss_mp_auth field in the
rbg_nounce_mic by the initiator demonstrates that the target agrees rgss3_create_res reply MUST be filled in with the inner RPCSEC_GSSv3
to the multi-principal authentication. 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
context associated with the inner handle.
On failure, the rgss3_gss_mp_auth field is not sent On failure, the rgss3_gss_mp_auth field is not sent
(rgss3_gss_mp_auth is an optional field). A MSG_DENIED reply to an (rgss3_gss_mp_auth is an optional field). A MSG_DENIED reply to the
RPCSEC_GSS_CREATE formulated as usual. A new value, RPCSEC_GSS_CREATE call is formulated as usual.
RPCSEC_GSS_INNER_CREDPROBLEM, has been added to the auth_stat type.
As described in Section 5.3.3.3 of [2] the server maintains a list of As described in Section 5.3.3.3 of [2] the server maintains a list of
contexts for the clients that are currently in session with it. When contexts for the clients that are currently in session with it. When
a client request comes in, there may not be a context corresponding a client request comes in, there may not be a context corresponding
to its handle. When this occurs on an RPCSEC_GSS3_CREATE request to its handle. When this occurs on an RPCSEC_GSS3_CREATE request
processing of the parent handle, the server rejects the request with processing of the parent handle, the server rejects the request with
a reply status of MSG_DENIED with the reject_stat of AUTH_ERROR and a reply status of MSG_DENIED with the reject_stat of AUTH_ERROR and
with an auth_stat value of RPCSEC_GSS_CREDPROBLEM. with an auth_stat value of RPCSEC_GSS_CREDPROBLEM.
With a multi-pricipal authorization request, the server must also A new value, RPCSEC_GSS_INNER_CREDPROBLEM, has been added to the
have a context corresponding to the inner context handle. When the auth_stat type. With a multi-pricipal authorization request, the
server does not have a context handle corresponding to the inner server must also have a context corresponding to the inner context
context handle of a multi-pricipal authorization request, the server handle. When the server does not have a context handle corresponding
send a reply status of MSG_DENIED with the reject_stat of AUTH_ERROR to the inner context handle of a multi-pricipal authorization
and with an auth_stat value of RPCSEC_GSS_INNER_CREDPROBLEM. request, the server send a reply status of MSG_DENIED with the
reject_stat of AUTH_ERROR and with an auth_stat value of
RPCSEC_GSS_INNER_CREDPROBLEM.
When processing the multi-principal authentication request, if the When processing the multi-principal authentication request, if the
GSS_VerifyMIC() call on the inner handle nouce fails to return GSS_VerifyMIC() call on the rgmp_rpcheader_mic fails to return
GSS_S_COMPLETE, the server sends a reply status of MSG_DENIED with GSS_S_COMPLETE, the server sends a reply status of MSG_DENIED with
the reject_stat of AUTH_ERROR and with an auth_stat value of the reject_stat of AUTH_ERROR and with an auth_stat value of
RPCSEC_GSS_INNER_CREDPROBLEM. RPCSEC_GSS_INNER_CREDPROBLEM.
2.6.1.2. Label Assertions 2.7.1.2. Channel Binding
<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 clients MAY assert a server security label in some LSF
by binding a label assertion to the RPCSEC_GSSv3 context handle.
This is done by including an assertion of type rgss3_label in the
RPCSEC_GSS_CREATE rgss3_create_args rca_assertions call data.
The labels that are accepted by the target and bound to the
RPCSEC_GSSv3 context will be enumerated in the rcr_assertions field
of the rgss3_create_res RPCSEC_GSS_CREATE reply.
Label encoding is specified to mirror the NFSv4.2 sec_label attribute
described in Section 12.2.2 of [6]. The label format specifier (LFS)
is an identifier used by the client to establish the syntactic format
of the security label and the semantic meaning of its components.
The policy identifier (PI) is an optional part of the definition of
an LFS which allows for clients and server to identify specific
security policies. The opaque label field of rgss3_label is
dependent on the 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 same
label with the NFSv4.2 sec_label attribute.
If a label itself requires privacy protection (i.e., that the user
can assert that label is a secret) then the client MUST use the
rpc_gss_svc_privacy protection service for the RPCSEC_GSS_CREATE
request or, if the parent handle is bound to a secure channel that
provides privacy protection, rpc_gss_svc_channel_prot.
If a client wants to ensure that the server understands the asserted
label then it MUST set the 'critical' field of 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 the requested LFS MUST
either ignore non-critical label assertions or map them to a suitable
label in a supported LFS. Servers that do not support labeling or do
not support the requested LFS MUST return an error if the label
request is 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.
2.6.1.3. 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 structured privilege by binding the
privilege to the RPCSEC_GSSv3 context handle. This is done by
including an assertion of type rgss3_privs in the RPCSEC_GSS_CREATE
rgss3_create_args rca_assertions call data. Encoding, server
verification and any policies for structured privileges are described
by the RPC application definition.
A successful structured privilege assertion will be enumerated in the
rcr_assertions field of the rgss3_create_res RPCSEC_GSS_CREATE reply.
If a server receives a structured privilege assertion that it does
not recognize the assertion is rejected with MSG_DENIED, a
reject_status of AUTH_ERROR, and an auth_stat of
RPCSEC_GSS_UNKNOWN_MESSAGE. If the server fails the RPC application
defined server verification for a structured privilege, the assertion
is rejected with MSG_DENIED, a reject_status of AUTH_ERROR, and an
auth_stat of RPCSEC_GSS_PRIVILEGE_PROBLEM.
Section 3.4.1.2. "Inter-Server Copy with RPCSEC_GSSv3" of [6] shows
an example of structured privilege definition and use.
2.6.1.4. Channel Binding
<CODE BEGINS> <CODE BEGINS>
/// ///
/// typedef opaque rgss3_chan_binding<>; /// typedef opaque rgss3_chan_binding<>;
/// ///
<CODE ENDS> <CODE ENDS>
RPCSEC_GSSv3 provides a different way to do channel binding than RPCSEC_GSSv3 provides a different way to do channel binding than
RPCSEC_GSSv2 [4]. Specifically: RPCSEC_GSSv2 [8]. Specifically:
a. RPCSEC_GSSv3 builds on RPCSEC_GSSv1 by reusing existing, a. RPCSEC_GSSv3 builds on RPCSEC_GSSv1 by reusing existing,
established context handles rather than providing a different RPC established context handles rather than providing a different RPC
security flavor for establishing context handles, security flavor for establishing context handles,
b. channel bindings data are not hashed because the community now b. channel bindings data are not hashed because the community now
agrees that it is the secure channel's responsibility to produce agrees that it is the secure channel's responsibility to produce
channel bindings data of manageable size. channel bindings data of manageable size.
(a) is useful in keeping RPCSEC_GSSv3 simple in general, not just for (a) is useful in keeping RPCSEC_GSSv3 simple in general, not just for
channel binding. (b) is useful in keeping RPCSEC_GSSv3 simple channel binding. (b) is useful in keeping RPCSEC_GSSv3 simple
specifically for channel binding. specifically for channel binding.
Channel binding is accomplished as follows. The client prefixes the Channel binding is accomplished as follows. The client prefixes the
channel bindings data octet string with the channel type as described channel bindings data octet string with the channel type as described
in [5], then the client calls GSS_GetMIC() to get a MIC of resulting in [6], then the client calls GSS_GetMIC() to get a MIC of resulting
octet string, using the RPCSEC_GSSv3 context handle's GSS-API octet string, using the parent RPCSEC_GSSv3 context handle's GSS-API
security context. The MIC is then placed in the rca_chan_bind_mic security context. The MIC is then placed in the rca_chan_bind_mic
field of RPCSEC_GSS_CREATE arguments (rgss3_create_args). field of RPCSEC_GSS_CREATE arguments (rgss3_create_args).
If the rca_chan_bind_mic field of the arguments of a If the rca_chan_bind_mic field of the arguments of a
RPCSEC_GSS_CREATE control message is set, then the server MUST verify RPCSEC_GSS_CREATE control message is set, then the server MUST verify
the client's channel binding MIC if the server supports this feature. the client's channel binding MIC if the server supports this feature.
If channel binding verification succeeds then the server MUST If channel binding verification succeeds then the server MUST
generate a new MIC of the same channel bindings and place it in the generate a new MIC of the same channel bindings and place it in the
rcr_chan_bind_mic field of the RPCSEC_GSS_CREATE rgss3_create_res rcr_chan_bind_mic field of the RPCSEC_GSS_CREATE rgss3_create_res
results. If channel binding verification fails or the server doesn't results. If channel binding verification fails or the server doesn't
skipping to change at page 15, line 23 skipping to change at page 13, line 34
reply by not including a rgss3_chan_binding value in rgss3_create_res reply by not including a rgss3_chan_binding value in rgss3_create_res
(rgss3_chan_binding is an optional field). (rgss3_chan_binding is an optional field).
The client MUST verify the result's rcr_chan_bind_mic value by The client MUST verify the result's rcr_chan_bind_mic value by
calling GSS_VerifyMIC() with the given MIC and the channel bindings calling GSS_VerifyMIC() with the given MIC and the channel bindings
data (including the channel type prefix). If client-side channel data (including the channel type prefix). If client-side channel
binding verification fails then the client MUST call binding verification fails then the client MUST call
RPCSEC_GSS_DESTROY. If the client requested channel binding but the RPCSEC_GSS_DESTROY. If the client requested channel binding but the
server did not include an rcr_chan_binding_mic field in the results, server did not include an rcr_chan_binding_mic field in the results,
then the client MAY continue to use the resulting context handle as then the client MAY continue to use the resulting context handle as
though channel binding had never been requested, otherwise (if the though channel binding had never been requested. If the client
client really wanted channel binding) it MUST call considers channel binding critical, it MUST call RPCSEC_GSS_DESTROY.
RPCSEC_GSS_DESTROY.
As per-RPCSEC_GSSv2 [4]: As per-RPCSEC_GSSv2 [8]:
"Once a successful [channel binding] procedure has been performed "Once a successful [channel binding] procedure has been performed
on an [RPCSEC_GSSv3] context handle, the initiator's on an [RPCSEC_GSSv3] context handle, the initiator's
implementation may map application requests for rpc_gss_svc_none implementation may map application requests for rpc_gss_svc_none
and rpc_gss_svc_integrity to rpc_gss_svc_channel_prot credentials. and rpc_gss_svc_integrity to rpc_gss_svc_channel_prot credentials.
And if the secure channel has privacy enabled, requests for And if the secure channel has privacy enabled, requests for
rpc_gss_svc_privacy can also be mapped to rpc_gss_svc_privacy can also be mapped to
rpc_gss_svc_channel_prot." rpc_gss_svc_channel_prot."
Any RPCSEC_GSSv3 context handle that has been bound to a secure Any RPCSEC_GSSv3 context handle that has been bound to a secure
channel in this way SHOULD be used only with the channel in this way SHOULD be used only with the
rpc_gss_svc_channel_prot, and SHOULD NOT be used with rpc_gss_svc_channel_prot, and SHOULD NOT be used with
rpc_gss_svc_none nor rpc_gss_svc_integrity -- if the secure channel rpc_gss_svc_none nor rpc_gss_svc_integrity -- if the secure channel
does not provide privacy protection then the client MAY use does not provide privacy protection then the client MAY use
rpc_gss_svc_privacy where privacy protection is needed or desired. rpc_gss_svc_privacy where privacy protection is needed or desired.
2.6.2. New Control Procedure - RPCSEC_GSS_LIST 2.7.1.3. 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. 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 same label with 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 [5]. The label format specifier (LFS)
is an identifier used by the client to establish the syntactic format
of the security label and the semantic meaning of its components.
The policy identifier (PI) is an optional part of the definition of
an LFS which allows for clients and server to identify specific
security policies. The opaque label field of rgss3_label is
dependent on the MAC model to interpret and enforce.
If a label itself requires privacy protection (i.e., that the user
can assert that label is a secret) then the client MUST use the
rpc_gss_svc_privacy protection service for the RPCSEC_GSS_CREATE
request.
RPCSEC_GSSv3 clients MAY assert a server security label in some LSF
by binding a label assertion to the RPCSEC_GSSv3 context handle.
This is done by including an assertion of type rgss3_label in the
RPCSEC_GSS_CREATE rgss3_create_args rca_assertions call data.
Servers that support labeling in the requested LFS MAY map the
requested label to different label as a result of server-side policy
evaluation.
The labels that are accepted by the target and bound to the
RPCSEC_GSSv3 context MUST be enumerated in the rcr_assertions field
of the rgss3_create_res RPCSEC_GSS_CREATE reply.
Servers that do not support labeling or that do not support the
requested LFS reject the label assertion with a reply status of
MSG_DENIED, a reject_status of AUTH_ERROR, and an auth_stat of
RPCSEC_GSS_LABEL_PROBLEM.
2.7.1.4. Structured Privilege Assertions
<CODE BEGINS> <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 structured privilege by binding the
privilege to the RPCSEC_GSSv3 context handle. This is done by
including an assertion of type rgss3_privs in the RPCSEC_GSS_CREATE
rgss3_create_args rca_assertions call data. Encoding, server
verification and any policies for structured privileges are described
by the RPC application definition.
A successful structured privilege assertion MUST be enumerated in the
rcr_assertions field of the rgss3_create_res RPCSEC_GSS_CREATE reply.
If a server receives a structured privilege assertion that it does
not recognize the assertion is rejected with a reply status of
MSG_DENIED, a reject_status of AUTH_ERROR, and an auth_stat of
RPCSEC_GSS_UNKNOWN_MESSAGE.
If a server receives a structured privilege assertion that it fails
to verify according to the requirements of the RPC application
defined behavior, the assertion is rejected with a reply status of
MSG_DENIED, a reject_status of AUTH_ERROR, and an auth_stat of
RPCSEC_GSS_PRIVILEGE_PROBLEM.
Section 3.4.1.2. "Inter-Server Copy with RPCSEC_GSSv3" of [5] shows
an example of structured privilege definition and use.
2.7.2. New Control Procedure - RPCSEC_GSS_LIST
<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
/// switch (rgss3_list_item itype) { /// switch (rgss3_list_item itype) {
/// case LABEL: /// case LABEL:
/// rgss3_label rli_labels<>; /// rgss3_label rli_labels<>;
/// case PRIVS: /// case PRIVS:
/// rgss3_privs rli_privs<>; /// rgss3_privs rli_privs<>;
/// default:
/// opaque rli_ext<>;
/// }; /// };
/// ///
/// 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, integers (rla_list_what) indicating what assertions to be listed, and
and the reply consists of an error or the requested list. the reply consists of an error or the requested list.
[[Comment.1: What good is the rli_ext field? How should we describe
it's use? --AA]]
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 2.6.1.2. Section 2.7.1.3.
2.7. 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. Every assertion has a 'critical' flag 'rgss3_assertion_u' union. Other assertion types are described
that can be used to indicate criticality. Other assertion types are elsewhere and include:
described elsewhere and 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.
New control message types may be added.
Servers receiving unknown critical client assertions MUST return an
error.
3. Operational Recommendation for Deployment 3. Operational Recommendation for Deployment
RPCSEC_GSSv3 is a superset of RPCSEC_GSSv2 [4] which in turn is a RPCSEC_GSSv3 is a superset of RPCSEC_GSSv2 [8] which in turn is a
superset of RPCSEC_GSSv1 [2], and so can be used in all situations superset of RPCSEC_GSSv1 [2], and so can be used in all situations
where RPCSEC_GSSv1 or RPCSEC_GSSv2 is used. RPCSEC_GSSv3 should be where RPCSEC_GSSv1 or RPCSEC_GSSv2 is used. RPCSEC_GSSv3 should be
used when the new functionality is needed. used when the new functionality is needed.
4. Security Considerations 4. Security Considerations
This entire document deals with security issues. This entire document deals with security issues.
The RPCSEC_GSSv3 protocol allows for client-side assertions of data The RPCSEC_GSSv3 protocol allows for client-side assertions of data
that is relevant to server-side authorization decisions. These that is relevant to server-side authorization decisions. These
assertions must be evaludated by the server in the context of whether assertions must be evaluated by the server in the context of whether
the client and/or user are authenticated, whether multi-principal the client and/or user are authenticated, whether multi-principal
authentication was used, whether the client is trusted, what ranges authentication was used, whether the client is trusted, what ranges
of assertions are allowed for the client and the user (separately or of assertions are allowed for the client and the user (separately or
together), and any relevant server-side policy. together), and any relevant server-side policy.
The security semantics of assertions carried by RPCSEC_GSSv3 are The security semantics of assertions carried by RPCSEC_GSSv3 are
application protocol-specific. 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 Note that RPSEC_GSSv3 is not a complete solution for labeling: it
conveys the labels of actors, but not the labels of objects. RPC conveys the labels of actors, but not the labels of objects. RPC
application protocols may require extending in order to carry object application protocols may require extending in order to carry object
label information. label information.
There may be interactions with NFSv4's callback security scheme and There may be interactions with NFSv4's callback security scheme and
NFSv4.1's GSS-API "SSV" mechanisms. Specifically, the NFSv4 callback NFSv4.1's GSS-API "SSV" mechanisms. Specifically, the NFSv4 callback
scheme requires that the server initiate GSS-API security contexts, scheme requires that the server initiate GSS-API security contexts,
which does not work well in practice, and in the context of client- which does not work well in practice, and in the context of client-
side processes running as the same user but with different privileges side processes running as the same user but with different privileges
skipping to change at page 18, line 14 skipping to change at page 17, line 48
particularly unlikely to work well. NFSv4.1 has the server use an particularly unlikely to work well. NFSv4.1 has the server use an
existing, client-initiated RPCSEC_GSS context handle to protect existing, client-initiated RPCSEC_GSS context handle to protect
server-initiated callback RPCs. The NFSv4.1 callback security scheme server-initiated callback RPCs. The NFSv4.1 callback security scheme
lacks all the problems of the NFSv4 scheme, however, it is important lacks all the problems of the NFSv4 scheme, however, it is important
that the server pick an appropriate RPCSEC_GSS context handle to that the server pick an appropriate RPCSEC_GSS context handle to
protect any callbacks. Specifically, it is important that the server protect any callbacks. Specifically, it is important that the server
use RPCSEC_GSS context handles which authenticate the client to use RPCSEC_GSS context handles which authenticate the client to
protect any callbacks relating to server state initiated by RPCs protect any callbacks relating to server state initiated by RPCs
protected by RPCSEC_GSSv3 contexts. protected by RPCSEC_GSSv3 contexts.
[[Comment.2: [Add text about interaction with GSS-SSV...] --NW]] [[AI6: [Add text about interaction with GSS-SSV...] --NW]]
[[Comment.3: AFAICS the reason to use SSV is to avoid using a client [[AI7: AFAICS the reason to use SSV is to avoid using a client
machine credential which means multi-principal authentication can not machine credential which means multi-principal authentication can not
be used. --AA]] be used. --AA]]
5. IANA Considerations 5. IANA Considerations
This section uses terms that are defined in [8]. This section uses terms that are defined in [4].
There are no IANA considerations in this document. TBDs in this There are no IANA considerations in this document.
document will be assigned by the ONC RPC registrar (which is not
IANA, XXX: verify).
6. References 6. References
6.1. Normative References 6.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate
Levels", RFC 2119, March 1997. Requirement Levels", RFC 2119, March 1997.
[2] Eisler, M., Chiu, A., and L. Ling, "RPCSEC_GSS Protocol [2] Eisler, M., Chiu, A., and L. Ling, "RPCSEC_GSS Protocol
Specification", RFC 2203, September 1997. Specification", RFC 2203, September 1997.
[3] Linn, J., "Generic Security Service Application Program [3] Linn, J., "Generic Security Service Application Program
Interface Version 2, Update 1", RFC 2743, January 2000. Interface Version 2, Update 1", RFC 2743, January 2000.
[4] Eisler, M., "RPCSEC_GSS Version 2", RFC 5403, February 2009. [4] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[5] Williams, N., "On the Use of Channel Bindings to Secure [5] Haynes, T., "NFS Version 4 Minor Version 2", draft-ietf-
Channels", RFC 5056, November 2007. nfsv4-minorversion2-27 (Work In Progress), June 2014.
[6] Haynes, T., "NFS Version 4 Minor Version 2", [6] Williams, N., "On the Use of Channel Bindings to Secure
draft-ietf-nfsv4-minorversion2-27 (Work In Progress), Channels", RFC 5056, November 2007.
June 2014.
[7] Eisler, M., "XDR: External Data Representation Standard", [7] Eisler, M., "XDR: External Data Representation Standard",
RFC 4506, May 2006. RFC 4506, May 2006.
[8] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA [8] Eisler, M., "RPCSEC_GSS Version 2", RFC 5403, February
Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. 2009.
[9] Haynes, T., "Requirements for Labeled NFS", RFC 7204,
April 2014.
6.2. Informative References 6.2. Informative References
[9] "Section 46.6. Multi-Level Security (MLS) of Deployment Guide: [10] "Section 46.6. Multi-Level Security (MLS) of Deployment
Deployment, configuration and administration of Red Hat Guide: Deployment, configuration and administration of Red
Enterprise Linux 5, Edition 6", 2011. Hat Enterprise Linux 5, Edition 6", 2011.
[10] Smalley, S., "The Distributed Trusted Operating System (DTOS) [11] Smalley, S., "The Distributed Trusted Operating System
Home Page", (DTOS) Home Page", 2000,
<http://www.cs.utah.edu/flux/fluke/html/dtos/HTML/dtos.html>. <http://www.cs.utah.edu/flux/fluke/html/dtos/HTML/
dtos.html>.
[11] Carter, J., "Implementing SELinux Support for NFS", [12] Carter, J., "Implementing SELinux Support for NFS", 2005,
<http://www.nsa.gov/research/_files/selinux/papers/nfsv3.pdf>. <http://www.nsa.gov/research/_files/selinux/papers/
nfsv3.pdf>.
[12] Haynes, T., "Requirements for Labeled NFS", [13] Quigley, D. and J. Lu, "Registry Specification for MAC
draft-ietf-nfsv4-labreqs-05 (work in progress). Security Label Formats", draft-quigley-label-format-
registry (work in progress), 2011.
[13] Quigley, D. and J. Lu, "Registry Specification for MAC Security [14] Wilkinson, S. and B. Kaduk, "Integrating rxgk with AFS",
Label Formats", draft-quigley-label-format-registry (work in draft-wilkinson-afs3-rxgk-afs (work in progress), April
progress), 2011. 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.
Lars Eggert and Mike Eisler for their most helpful reviews. We thank Lars Eggert, Mike Eisler, Ben Kaduk, and Bruce Fields 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 RFCTBD10 with RFCxxxx where xxxx is the
RFC number of this document] RFC number of this document]
Authors' Addresses Authors' Addresses
William A. (Andy) Adamson William A. (Andy) Adamson
NetApp NetApp
3629 Wagner Ridge Ctt 3629 Wagner Ridge Ct
Ann Arbor, MI 48103 Ann Arbor, MI 48103
USA USA
Phone: +1 734 665 1204 Phone: +1 734 665 1204
Email: andros@netapp.com Email: andros@netapp.com
Nico Williams Nico Williams
cryptonector.com cryptonector.com
13115 Tamayo Dr 13115 Tamayo Dr
Austin, TX 78729 Austin, TX 78729
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