draft-ietf-nfsv4-rpcsec-gssv3-05.txt   draft-ietf-nfsv4-rpcsec-gssv3-06.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: April 20, 2014 Cryptonector Expires: April 20, 2014 Cryptonector
October 17, 2013 October 17, 2013
Remote Procedure Call (RPC) Security Version 3 Remote Procedure Call (RPC) Security Version 3
draft-ietf-nfsv4-rpcsec-gssv3-05.txt draft-ietf-nfsv4-rpcsec-gssv3-06.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 compound security protocol (RPCSEC_GSS). This protocol provides for compound
authentication of client hosts and users to server (constructed by authentication of client hosts and users to server (constructed by
generic composition), security label assertions for multi-level and generic composition), security label assertions for multi-level and
type enforcement, structured privilege assertions, and channel type enforcement, structured privilege assertions, and channel
bindings. bindings.
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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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Applications of RPCSEC_GSSv3 . . . . . . . . . . . . . . . 4 1.1. Applications of RPCSEC_GSSv3 . . . . . . . . . . . . . . . 4
2. The RPCSEC_GSSv3 protocol . . . . . . . . . . . . . . . . . . 5 2. The RPCSEC_GSSv3 Protocol . . . . . . . . . . . . . . . . . . 5
2.1. New auth_stat values . . . . . . . . . . . . . . . . . . . 9 2.1. New auth_stat Values . . . . . . . . . . . . . . . . . . . 9
2.2. RPC message credential and verifier . . . . . . . . . . . 10 2.2. RPC Message Credential and Verifier . . . . . . . . . . . 10
2.3. Control Messages . . . . . . . . . . . . . . . . . . . . . 10 2.3. Control Messages . . . . . . . . . . . . . . . . . . . . . 10
2.3.1. Create request . . . . . . . . . . . . . . . . . . . . 11 2.3.1. Create Request . . . . . . . . . . . . . . . . . . . . 11
2.3.2. Destruction request . . . . . . . . . . . . . . . . . 15 2.3.2. Destruction Request . . . . . . . . . . . . . . . . . 15
2.3.3. List request . . . . . . . . . . . . . . . . . . . . . 16 2.3.3. List Request . . . . . . . . . . . . . . . . . . . . . 15
2.3.4. Extensibility . . . . . . . . . . . . . . . . . . . . 16 2.3.4. Extensibility . . . . . . . . . . . . . . . . . . . . 16
2.4. Data Messages . . . . . . . . . . . . . . . . . . . . . . 17 2.4. Data Messages . . . . . . . . . . . . . . . . . . . . . . 16
3. Security Considerations . . . . . . . . . . . . . . . . . . . 17 3. Security Considerations . . . . . . . . . . . . . . . . . . . 17
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.1. Normative References . . . . . . . . . . . . . . . . . . . 19 5.1. Normative References . . . . . . . . . . . . . . . . . . . 18
5.2. Informative References . . . . . . . . . . . . . . . . . . 19 5.2. Informative References . . . . . . . . . . . . . . . . . . 19
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 20 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 19
Appendix B. RFC Editor Notes . . . . . . . . . . . . . . . . . . 20 Appendix B. RFC Editor Notes . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction 1. Introduction
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 [4] added support for channel bindings [5].
We find that GSS-API mechanisms are insufficient for communicating We find that GSS-API mechanisms are insufficient for communicating
certain aspects of a client's authority to a server. The GSS-API and certain aspects of a client's authority to a server. The GSS-API and
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assertion as well. This calls for compound authentication. assertion as well. This calls for compound authentication.
Because the design of RPCSEC_GSSv3 relies on either RPCSEC_GSS Because the design of RPCSEC_GSSv3 relies on either RPCSEC_GSS
version 1 (though version 2 can be used) to do the actual GSS-API version 1 (though version 2 can be used) to do the actual GSS-API
security context establishment, we add support for channel binding so security context establishment, we add support for channel binding so
that implementors who have implemented RPCSEC_GSS version 1 but not that implementors who have implemented RPCSEC_GSS version 1 but not
version 2 can provide a (simplified) channel binding implementation version 2 can provide a (simplified) channel binding implementation
using RPCSEC_GSSv3. using RPCSEC_GSSv3.
We therefore describe a new version of RPCSEC_GSS that allows for the We therefore describe a new version of RPCSEC_GSS that allows for the
following: following client-side assertions of authority:
o Client-side assertions of authority:
* Security labels for multi-level, type enforcement, and other o Security labels for multi-level, type enforcement, and other
labeled security models. See [10], [11], [12], [6] and [9]. labeled security models. See [10], [11], [12], [6] and [9].
* Application-specific structured privileges. For an example see o Application-specific structured privileges. For an example see
server-side copy [6]. server-side copy [6].
* Compound authentication of the client host and user to the o Compound authentication of the client host and user to the server
server done by binding two RPCSEC_GSS handles. done by binding two RPCSEC_GSS handles.
* 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 also add an option for enumerating active server-side privileges We add an option for enumerating server supported label format
and supported label format specifiers (LFS). The LFS and Label specifiers (LFS). The LFS and Label Format Registry are described in
Format Registry are described in detail in [13]. detail in [13].
RPCSEC_GSSv3 is patterned as follows: RPCSEC_GSSv3 is patterned as follows:
o A client uses an existing RPCSEC_GSSv1 (or RPCSEC_GSSv2) context o A client uses an existing RPCSEC_GSSv1 (or RPCSEC_GSSv2) context
handle to protect RPCSEC_GSSv3 exchanges (this will be termed the handle to protect RPCSEC_GSSv3 exchanges (this will be termed the
"parent" handle) "parent" handle)
o The server issues a "child" RPCSEC_GSSv3 handle, but the o The server issues a "child" RPCSEC_GSSv3 handle which uses the
underlying GSS-API security context for the parent handle is used underlying GSS-API security context of the parent handle in all
in all subsequent exchanges using the child handle. This works subsequent exchanges that uses the child handle.
because the RPCSEC_GSS handle is included in the integrity
protected RPCSEC_GSS auth/verifier header for all versions of
RPCSEC_GSS. The child context, however, has its own sequence
number space and window, distinct from that of the parent.
[[Comment.1: RFC22203 states that when data integrity is used, the o The child handle, however, has its own sequence number space
distinct from that of the parent.
[[Comment.1: I removed the "child has a window distinct from that of
the parent" because RFC2203 states: " In a successful response, the
seq_window field is set to the sequence window length supported by
the server for this context. This window specifies the maximum
number of client requests that may be outstanding for this context."
If we want a distinct window, we will need to add that to the
rpc_gss3_create_res so that the server can set it. I see no point -
just use the parent window. --AA]]
[[Comment.2: RFC2203 states that when data integrity is used, the
seq_num in the rpc_gss_data_t must be the same as in the credential. seq_num in the rpc_gss_data_t must be the same as in the credential.
This means that using data integrity with GSS3 context's can not This means that using data integrity with GSS3 context's can not
simply construct it using the parent context as the seq_num must be simply construct it using the parent context as the seq_num must be
from the GSS3 context. --AA]] from the GSS3 context. --AA]]
This means that RPCSEC_GSSv3 depends on RPCSEC_GSS versions 1 and/or This means that RPCSEC_GSSv3 depends on an existing parent
2 for actual GSS-API security context establishment. This keeps the RPCSEC_GSSv1 or RPCSEC_GSSv2 context for actual GSS-API security
specification of RPCSEC_GSSv3 simple by avoiding the need to context establishment. This keeps the specification of RPCSEC_GSSv3
duplicate the core functionality of RPCSEC_GSS version 1. simple by avoiding the need to duplicate the core functionality of
RPCSEC_GSS version 1. This also means that an RPCSEC_GSSv3 context
MUST be destroyed prior to it's parent context being destroyed.
[[Comment.3: Destruction of the parent context => first destroy child
handle. IOW fail the RPCSEC_GSS_DESTROY of parent with new
RPCSEC_GSS3_CONTEXT_EXISTS error code OR upon the destruction of the
parent context destroy any associated RPCSEC_GSSv3 contexts OR.....
--AA]]
1.1. Applications of RPCSEC_GSSv3 1.1. Applications of RPCSEC_GSSv3
The common uses of RPCSEC_GSSv3, particularly for NFSv4 [6], are The common uses of RPCSEC_GSSv3, particularly for NFSv4 [6], are
expected to be: expected to be:
a. labeled security: client-side process label assertion [+ a. labeled security: client-side process label assertion [+
privilege assertion] + compound client host & user privilege assertion] + compound client host & user
authentication; authentication;
b. compound client host & user authentication [+ critical structured b. inter-server server-side copy: compound client host & user
privilege assertions] used in inter-server server-side copy; authentication [+ critical structured privilege assertions]
Labeled NFS (see Section 8 of [6]) uses the subject label provided by Labeled NFS (see Section 8 of [6]) uses the subject label provided by
the client via the RPCSEC_GSSv3 layer to enforce MAC access to 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.
[[Comment.2: check that this language states what NFSv4.2 labeled NFS [[Comment.4: check that this language states what NFSv4.2 labeled NFS
problem we are really solving. (setting labels on the server) --AA]] problem we are really solving. (setting labels on the server) --AA]]
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 [6]), the user first secures access to both source
and destination files, and then uses RPCSEC_GSSv3 compound and destination files, and then uses RPCSEC_GSSv3 compound
authentication and structured privileges to authorize the destination authentication and structured privileges to authorize the destination
to copy the file from the source on behalf of the user. to copy the file from the source on behalf of the user.
2. The RPCSEC_GSSv3 protocol 2. The RPCSEC_GSSv3 Protocol
This document contains the External Data Representation (XDR) ([7]) This document contains the External Data Representation (XDR) ([7])
definitions for the RPCSEC_GSSv3 protocol. definitions for the RPCSEC_GSSv3 protocol.
The XDR description is provided in this document in a way that makes The XDR description is provided in this document in a way that makes
it simple for the reader to extract into ready to compile form. The it 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:
#!/bin/sh #!/bin/sh
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/// opaque handle<>; /// opaque handle<>;
/// }; /// };
/// ///
/// const RPCSEC_GSS_VERS_1 = 1; /// const RPCSEC_GSS_VERS_1 = 1;
/// const RPCSEC_GSS_VERS_2 = 2; /// const RPCSEC_GSS_VERS_2 = 2;
/// const RPCSEC_GSS_VERS_3 = 3; /* new */ /// const RPCSEC_GSS_VERS_3 = 3; /* new */
/// ///
/// union rpc_gss_cred_t switch (unsigned int rgc_version) { /// union rpc_gss_cred_t switch (unsigned int rgc_version) {
/// case RPCSEC_GSS_VERS_1: /// case RPCSEC_GSS_VERS_1:
/// case RPCSEC_GSS_VERS_2: /// case RPCSEC_GSS_VERS_2:
/// rpc_gss_cred_vers_1_t rgc_cred_v1; /// rpc_gss_cred_vers_1_t rgc_cred_v1;
/// case RPCSEC_GSS_VERS_3: /* new */ /// case RPCSEC_GSS_VERS_3: /* new */
/// rpc_gss_cred_vers_3_t rgc_cred_v3; /// rpc_gss_cred_vers_3_t rgc_cred_v3;
/// }; /// };
/// ///
/// const MAXSEQ = 0x80000000; /// const MAXSEQ = 0x80000000;
/// ///
/// struct rpc_gss3_extension {
/// int type;
/// bool critical;
/// opaque data<>;
/// };
///
/// struct rpc_gss3_gss_binding { /// struct rpc_gss3_gss_binding {
/// unsigned int vers; /// unsigned int vers;
/// opaque handle<>; /// opaque handle<>;
/// opaque nonce<>; /// opaque nonce<>;
/// opaque mic<>; /// opaque mic<>;
/// }; /// };
/// ///
/// typedef opaque rpc_gss3_chan_binding<>; /// typedef opaque rpc_gss3_chan_binding<>;
/// ///
/// struct rpc_gss3_lfs { /// struct rpc_gss3_lfs {
/// unsigned int lfs_id; /// unsigned int lfs_id;
/// unsigned int pi_id; /// unsigned int pi_id;
/// }; /// };
/// ///
/// struct rpc_gss3_label { /// struct rpc_gss3_label {
/// rpc_gss3_lfs lfs; /// rpc_gss3_lfs lfs;
/// opaque label<>; /// opaque label<>;
/// }; /// };
/// ///
/// typedef string rpc_gss3_list_name<>;
/// struct rpc_gss3_privs { /// struct rpc_gss3_privs {
/// rpc_gss3_list_name listname; /// string name; /* human readable */
/// opaque privilege<>; /// opaque privilege<>;
/// }; /// };
/// ///
/// enum rpc_gss3_assertion_type { /// enum rpc_gss3_assertion_type {
/// LABEL = 0, /// LABEL = 0,
/// PRIVS = 1 /// PRIVS = 1
/// }; /// };
/// ///
/// union rpc_gss3_assertion_u /// union rpc_gss3_assertion_u
/// switch (rpc_gss3_assertion_type atype) { /// switch (rpc_gss3_assertion_type atype) {
/// case LABEL: /// case LABEL:
/// rpc_gss3_label label; /// rpc_gss3_label label;
/// case PRIVILEGES: /// case PRIVS:
/// rpc_gss3_privs privs; /// rpc_gss3_privs privs;
/// default: /// default:
/// opaque ext<>; /// opaque ext<>;
/// }; /// };
/// ///
/// struct rpc_gss3_assertion { /// struct rpc_gss3_assertion {
/// bool critical; /// bool critical;
/// rpc_gss3_assertion_u assertion; /// rpc_gss3_assertion_u assertion;
/// }; /// };
/// ///
/// struct rpc_gss3_create_args { /// struct rpc_gss3_create_args {
/// rpc_gss3_gss_binding *compound_binding; /// rpc_gss3_gss_binding *compound_binding;
/// rpc_gss3_chan_binding *chan_binding_mic; /// rpc_gss3_chan_binding *chan_binding_mic;
/// rpc_gss3_assertion assertions<>; /// rpc_gss3_assertion assertions<>;
/// rpc_gss3_extension extensions<>;
/// }; /// };
/// ///
/// struct rpc_gss3_create_res { /// struct rpc_gss3_create_res {
/// opaque handle<>; /// opaque handle<>;
/// rpc_gss3_chan_binding *chan_binding_mic; /// rpc_gss3_chan_binding *chan_binding_mic;
/// rpc_gss3_assertion granted_assertions<>; /// rpc_gss3_assertion granted_assertions<>;
/// rpc_gss3_extension granted_extensions<>;
/// }; /// };
/// ///
/// enum rpc_gss3_list_item { /// enum rpc_gss3_list_item {
/// LABEL = 0, /// LABEL = 0,
/// PRIV = 1,
/// }; /// };
/// ///
/// struct rpc_gss3_list_args { /// struct rpc_gss3_list_args {
/// rpc_gss3_list_item list_what<>; /// rpc_gss3_list_item list_what<>;
/// }; /// };
/// ///
/// union rpc_gss3_list_item_u /// union rpc_gss3_list_item_u
/// switch (rpc_gss3_list_item itype) { /// switch (rpc_gss3_list_item itype) {
/// case LABEL: /// case LABEL:
/// rpc_gss3_lable labels<>; /// rpc_gss3_lable labels<>;
/// case PRIV:
/// rpc_gss3_list_name privs<>;
/// default: /// default:
/// opaque ext<>; /// opaque ext<>;
/// }; /// };
/// ///
/// typedef rpc_gss3_list_item_u rpc_gss3_list_res<>; /// typedef rpc_gss3_list_item_u rpc_gss3_list_res<>;
2.1. New auth_stat values 2.1. 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: enumerated type definition:
enum auth_stat { enum auth_stat {
... ...
/* /*
* RPCSEC_GSS errors * RPCSEC_GSSv3 errors
*/ */
RPCSEC_GSS3_COMPOUND_PROBEM = <>, RPCSEC_GSS3_COMPOUND_PROBEM = <>,
RPCSEC_GSS3_LABEL_PROBLEM = <>, RPCSEC_GSS3_LABEL_PROBLEM = <>,
RPCSEC_GSS3_UNKNOWN_ASSERTION = <> RPCSEC_GSS3_UNKNOWN_PRIVILEGE = <>
RPCSEC_GSS3_UNKNOWN_EXTENSION = <>
RPCSEC_GSS3_UNKNOWN_MESSAGE = <> RPCSEC_GSS3_UNKNOWN_MESSAGE = <>
}; };
[[Comment.3: fix above into YYY. All the entries are TBD... --NW]] [[Comment.5: fix above into YYY. All the entries are TBD... --NW]]
[[Comment.6: The compound authentication problems are: can't find the
handle plus handle version on the target, or the MIC of the nounce
does not match. Both of these errors already have auth_stat entries:
RPCSEC_GSS_CREDPROBLEM for the first and "reply status of
MSG_ACCEPTED, and an acceptance status of GARBAGE_ARGS." --AA]]
2.2. RPC message credential and verifier 2.2. RPC Message Credential and Verifier
The rpc_gss_cred_vers_3_t type is used in much the same way that The rpc_gss_cred_vers_3_t type is used in much the same way that
rpc_gss_cred_vers_1_t is used in RPCSEC_GSSv1, that is: as the arm of rpc_gss_cred_vers_1_t is used in RPCSEC_GSSv1, that is: as the arm of
the rpc_gss_cred_t discriminated union in the RPC message header the rpc_gss_cred_t discriminated union in the RPC message header
opaque_auth structure corresponding to version 3 (RPCSEC_GSS_VERS_3). opaque_auth structure corresponding to version 3 (RPCSEC_GSS_VERS_3).
It differs from rpc_gss_cred_vers_1_t in that: It differs from rpc_gss_cred_vers_1_t in that:
a. the values for gss_proc corresponding to control messages are a. the values for gss_proc corresponding to control messages are
different. different.
b. the handle field is the RPCSEC_GSSv3 (child) handle, except for b. the handle field is the RPCSEC_GSSv3 (child) handle, except for
the RPCSEC_GSS3_CREATE control message where it is set to the the RPCSEC_GSS3_CREATE and RPCSEC_GSS3_LIST control messages
parent context handle. where it is set to the parent context handle.
For all RPCSEC_GSSv3 data and control messages, the verifier field in For all RPCSEC_GSSv3 data and control messages, the verifier field in
the RPC message header is constructed in the RPCSEC_GSSv1 manner the RPC message header is constructed in the RPCSEC_GSSv1 manner
using the parent GSS-API security context. using the parent GSS-API security context.
2.3. Control Messages 2.3. Control Messages
There are three RPCSEC_GSSv3 control messages: RPCSEC_GSS3_CREATE, There are three RPCSEC_GSSv3 control messages: RPCSEC_GSS3_CREATE,
RPCSEC_GSS3_DESTROY, and RPCSEC_GSS3_LIST. RPCSEC_GSS3_DESTROY, and RPCSEC_GSS3_LIST.
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NULLPROC. NULLPROC.
As in RPCSEC_GSSv1, the RPCSEC_GSSv3 control messages may contain As in RPCSEC_GSSv1, the RPCSEC_GSSv3 control messages may contain
information following the verifier in the body of the NULLPROC information following the verifier in the body of the NULLPROC
procedure. procedure.
The client MUST use one of the following security services to protect The client MUST use one of the following security services to protect
any RPCSEC_GSSv3 control message: any RPCSEC_GSSv3 control message:
o rpc_gss_svc_channel_prot (see RPCSEC_GSSv2) o rpc_gss_svc_channel_prot (see RPCSEC_GSSv2)
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.
For RPCSEC_GSSv3 control messages the rpc_gss_cred_vers_3_t in the For RPCSEC_GSSv3 control messages the rpc_gss_cred_vers_3_t in the
RPC message opaque_auth structure is encoded as follows: RPC message opaque_auth structure is encoded as follows:
1. the union rpc_gss_cred_t version is set to 3 with the value being o the union rpc_gss_cred_t version is set to 3 with the value being
of type rpc_gss_cred_vers_3_t instead of rpc_gss_cred_vers_1_t. of type rpc_gss_cred_vers_3_t instead of rpc_gss_cred_vers_1_t.
2. the gss_proc is set to one of RPCSEC_GSS3_CREATE, o the gss_proc is set to one of RPCSEC_GSS3_CREATE,
RPCSEC_GSS3_DESTROY, or RPCSEC_GSS3_LIST. RPCSEC_GSS3_DESTROY, or RPCSEC_GSS3_LIST.
3. the seq_num is a valid sequence number for the context in the o the seq_num is a valid sequence number for the context in the
handle field. handle field.
4. the rpc_gss_service_t is one of rpc_gss_svc_integrity, o the rpc_gss_service_t is one of rpc_gss_svc_integrity,
rpc_gss_svc_privacy, or rpc_gss_svc_channel_prot. rpc_gss_svc_privacy, or rpc_gss_svc_channel_prot.
5. the rpc_gss_cred_vers_3_t handle field is either set to the o the rpc_gss_cred_vers_3_t handle field is either set to the parent
parent context handle for RPCSEC_GSS3_CREATE, or to the GSS3 context handle for RPCSEC_GSS3_CREATE and RPCSEC_GSS3_LIST, or to
child handle for RPCSEC_GSS3_LIST and RPCSEC_GSS3_DESTROY. the GSS3 child handle for RPCSEC_GSS3_DESTROY.
2.3.1. Create request 2.3.1. Create Request
As noted in the introduction, RPCSEC_GSSv3 relies on the RPCSEC_GSS As noted in the introduction, RPCSEC_GSSv3 relies on the RPCSEC_GSS
version 1 parent context (though version 2 can be used) secure version 1 parent context (though version 2 can be used) secure
connection to do the actual GSS-API GSS3 security context connection to do the actual GSS-API GSS3 security context
establishment. As such, the rpc_gss_cred_vers_3_t fields in the RPC establishment. As such, for the RPCSEC_GSS3_CREATE request, the
Call opaque_auth use the parent context handle and seq_num stream. rpc_gss_cred_vers_3_t fields in the RPC Call opaque_auth use the
parent context handle and seq_num stream.
The RPCSEC_GSS3_CREATE call message binds one or more items of The RPCSEC_GSS3_CREATE call message binds one or more items of
several kinds into a new RPCSEC_GSSv3 context handle: several kinds into a new RPCSEC_GSSv3 context handle:
o another RPCSEC_GSS (version 1, 2, or 3) context handle (compound o another RPCSEC_GSS (version 1, 2, or 3) context handle (compound
authentication) authentication)
o a channel binding o a channel binding
o authorization assertions (labels, privileges) o authorization assertions (labels, privileges)
o extensions (see Section 2.3.4 )
The reply to this message consists of either an error or an The reply to this message consists of either an error or an
rpc_gss3_create_res structure which includes a new RPCSEC_GSSv3 rpc_gss3_create_res structure which includes a new RPCSEC_GSSv3
handle, termed the "child" which is used for subsequent control and handle, termed the "child" which is used for subsequent control and
data messages. data messages.
Upon successful RPCSEC_GSS3_CREATE, both the client and the server Upon successful RPCSEC_GSS3_CREATE, both the client and the server
should associate the resultant GSSv3 child context handle with the should associate the resultant GSSv3 child context handle with the
parent context handle in their GSS context caches so as to be able to parent context handle in their GSS context caches so as to be able to
reference the parent context given the child context handle. reference the parent context given the child context handle.
[[Comment.4: Destruction of the parent context => first destroy child Server implementation and policy MAY result in labels, privileges,
handle. IOW fail the RPCSEC_GSS_DESTROY of parent with new and identities being mapped to concepts and values that are local to
RPCSEC_GSS3_CONTEXT_EXISTS error code: What about the lifetime of the the server. Server policies should take into account the identity of
GSS3 context. Is this meant to be long lived?? --AA]] the client and/or user as authenticated via the GSS-API.
Server policies should take into account the identity of the client
and/or user as authenticated via the GSS-API. Server implementation
and policy MAY result in labels, privileges, and identities being
mapped to concepts and values that are local to the server.
2.3.1.1. Compound authentication 2.3.1.1. Compound Authentication
RPCSEC_GSSv3 allows for compound authentication of client hosts and RPCSEC_GSSv3 allows for compound authentication of client hosts and
users to servers. As in non-compound authentication, there is a users to servers. As in non-compound authentication, there is a
parent handle used to protect the RPCSEC_GSS3_CREATE call message, parent handle used to protect the RPCSEC_GSS3_CREATE call message and
and a resultant RPCSEC_GSSv3 child handle. In addition to the parent a resultant RPCSEC_GSSv3 child handle. In addition to the parent
handle, the compound authentication create control message has a handle, the compound authentication create control message has a
handle referenced via the compound_binding field of the handle referenced via the compound_binding field of the
RPCSEC_GSS3_CREATE arguments structure (rpc_gss3_create_args) termed RPCSEC_GSS3_CREATE arguments structure (rpc_gss3_create_args) termed
the "inner" handle, as well as a nonce and a MIC of that nounce the "inner" handle, as well as a nonce and a MIC of that nounce
created using the GSS-API security context associated with the created using the GSS-API security context associated with the
"inner" handle. "inner" handle.
All uses of a child context handle that is bound to an inner context
MUST be treated as speaking for the initiator principal (as modified
by any assertions in the RPCSEC_GSS3_CREATE message) of the inner
context handle's GSS-API security context.
This feature is needed, for example, when a client wishes to use This feature is needed, for example, when a client wishes to use
authority assertions that the server may only grant if a user and a authority assertions that the server may only grant if a user and a
client are authenticated together to the server. Thus a server may client 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 a client acting alone an unprivileged user-space program), or to a client acting alone
(e.g. when a client is acting on behalf of a user) but may grant (e.g. when a client is acting on behalf of a user) but may grant
requested authority to a client acting on behalf of a user if the requested authority to a client acting on behalf of a user if the
server identifies the user and trusts the client. server identifies the user and trusts the client.
It is assumed that an unprivileged user-space program would not have It is assumed that an unprivileged user-space program would not have
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GSS-API security context that authenticates the client host, and for GSS-API security context that authenticates the client host, and for
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 compounds might inner authenticates client) MUST NOT be used. Other compounds might
eventually make sense. eventually make sense.
An RPCSEC_GSSv3 context handle that is bound to another RPCSEC_GSS An RPCSEC_GSSv3 context handle that is bound to another RPCSEC_GSS
context MUST be treated by servers as authenticating the GSS-API context MUST be treated by servers as authenticating the GSS-API
initiator principal authenticated by the inner context handle's GSS- initiator principal authenticated by the inner context handle's GSS-
API security context. This principal may be mapped to a server-side API security context. This principal may be mapped to a server-side
notion of user or principal as modified by any identity assertions by notion of user or principal.
the client in the same RPCSEC_GSS3_CREATE request that the server
accepts.
2.3.1.2. Channel binding 2.3.1.2. Channel Binding
RPCSEC_GSSv3 provides a different way to do channel binding than RPCSEC_GSSv3 provides a different way to do channel binding than
RPCSEC_GSSv2. Specifically: RPCSEC_GSSv2. 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
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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.
2.3.1.3. Label assertions 2.3.1.3. Label Assertions
RPCSEC_GSSv3 clients MAY assert a security label in some LSF by RPCSEC_GSSv3 clients MAY assert a security label in some LSF by
binding this assertion into an RPCSEC_GSSv3 context handle. This is binding this assertion into an RPCSEC_GSSv3 context handle. This is
done by including an assertion of type rpc_gss3_label in the done by including an assertion of type rpc_gss3_label in the
'assertions' field (discriminant: 'LABEL') of the RPCSEC_GSS3_CREATE 'assertions' field (discriminant: 'LABEL') of the RPCSEC_GSS3_CREATE
arguments to the desired LSF and label. arguments to the desired LSF and label.
Label encoding is specified to mirror the NFSv4 sec_label attribute Label encoding is specified to mirror the NFSv4 sec_label attribute
described in Section 12.2.2 of [6]. The label format specifier (LFS) 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 is an identifier used by the client to establish the syntactic format
of the security label and the semantic meaning of its components. of the security label and the semantic meaning of its components.
The policy identifier (PI) is an optional part of the definition of The policy identifier (PI) is an optional part of the definition of
an LFS which allows for clients and server to identify specific an LFS which allows for clients and server to identify specific
security policies. The opaque label field of rpc_gss3_label is security policies. The opaque label field of rpc_gss3_label is
dependent on the MAC model to interpret and enforce. dependent on the MAC model to interpret and enforce.
[[Comment.5: Check that this Label definition provides all the [[Comment.7: Check that this Label definition provides all the
required pieces to enable full mode when combined with NFSv4.2 LNFS. required pieces to enable full mode when combined with NFSv4.2 LNFS.
Specifically, how does the client find out and respond if a server Specifically, how does the client find out and respond if a server
has changed a label. --AA]] has changed a label. --AA]]
If a label itself requires privacy protection (i.e., that the user 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 can assert that label is a secret) then the client MUST use the
rpc_gss_svc_privacy protection service for the RPCSEC_GSS3_CREATE rpc_gss_svc_privacy protection service for the RPCSEC_GSS3_CREATE
request or, if the parent handle is bound to a secure channel that request or, if the parent handle is bound to a secure channel that
provides privacy protection, rpc_gss_svc_channel_prot. provides privacy protection, rpc_gss_svc_channel_prot.
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Servers that do not support labeling MUST ignore non-critical label Servers that do not support labeling MUST ignore non-critical label
assertions. Servers that do not support the requested LFS MUST assertions. Servers that do not support the requested LFS MUST
either ignore non-critical label assertions or map them to a suitable 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 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 not support the requested LFS MUST return an error if the label
request is critical. Servers that support labeling in the requested request is critical. Servers that support labeling in the requested
LFS MAY map the requested label to different label as a result of LFS MAY map the requested label to different label as a result of
server-side policy evaluation. server-side policy evaluation.
2.3.1.4. Structured privilege assertions 2.3.1.4. Structured Privilege Assertions
A structured privilege is an RPC application defined structure that A structured privilege is an RPC application defined structure that
is opaque, and is encoded in the rpc_gss3_privs privilege field. is opaque, and is encoded in the rpc_gss3_privs privilege field.
Encoding, server verification and any server policies for structured Encoding, server verification and any server policies for structured
privileges are described by the RPC application definition. The privileges are described by the RPC application definition.
listname field of rpc_gss3_privs is a description string used to list
the privilege.
A successful structured privilege assertion RPCSEC_GSS3_CREATE call A successful structured privilege assertion RPCSEC_GSS3_CREATE call
must return all accepted privileges in the rpc_gss3_privs must return all granted privileges in the rpc_gss3_privs
granted_assertions field. granted_assertions field.
Section 3.4.1.2. "Inter-Server Copy with RPCSEC_GSSv3" of [6] shows Section 3.4.1.2. "Inter-Server Copy with RPCSEC_GSSv3" of [6] shows
an example of structured privilege definition and use. an example of structured privilege definition and use.
2.3.2. Destruction request 2.3.2. Destruction Request
The RPCSEC_GSS3_DESTROY control message is the same as the The RPCSEC_GSS3_DESTROY control message is the same as the
RPCSEC_GSSv1 RPCSEC_GSS_DESTROY control message, but with the version RPCSEC_GSSv1 RPCSEC_GSS_DESTROY control message, but with the version
3 header. Specifically, the rpc_gss_cred_vers_3_t fields in the RPC 3 header. Specifically, the rpc_gss_cred_vers_3_t fields in the RPC
Call opaque_auth use the GSS3 context handle and seq_num stream. As Call opaque_auth use the GSS3 context handle and seq_num stream. As
with all RPCSEC_GSSv3 messages, the header checksum uses the parent with all RPCSEC_GSSv3 messages, the header checksum uses the parent
context, and needs to be valid. context, and needs to be valid.
The server sends a response as it would to a data request. The The server sends a response as it would to a data request. The
client and server must then destroy the context for the session. client and server must then destroy the context for the session.
2.3.3. List request 2.3.3. List Request
The RPCSEC_GSS3_LIST control message is similar to The RPCSEC_GSS3_LIST control message is similar to RPCSEC_GSS3_CREATE
RPCSEC_GSS3_DESTROY message. Specifically, the rpc_gss_cred_vers_3_t message. Specifically, the rpc_gss_cred_vers_3_t fields in the RPC
fields in the RPC Call opaque_auth use the GSS3 context handle and Call opaque_auth use the parent context handle and seq_num stream.
seq_num stream. As with all RPCSEC_GSSv3 messages, the header As with all RPCSEC_GSSv3 messages, the header checksum uses the
checksum uses the parent context, and needs to be valid. parent context, and needs to be valid.
The RPCSEC_GSS3_LIST control message consists of a single integer The RPCSEC_GSS3_LIST control message consists of a single integer
indicating what should be listed, and the reply consists of an error indicating what should be listed, and the reply consists of an error
or the requested list. The client may list LFSs or structured or the requested list. The client may query the server to list
privilege listnames. available LFSs.
The result is an opaque octet string containing a list of LFSs The result is an opaque octet string containing a list of LFSs
[encoding TBD] or a list of active structured privileges [encoding [encoding TBD].
TBD].
2.3.4. Extensibility 2.3.4. Extensibility
New fields may be added through the 'extensions' typed hole. All
such extensions have a 'critical' flag.
[[Comment.6: Should we keep the extensions types hole? I think
not... --AA]]
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
'rpc_gss3_assertion_u' union. Every assertion has a 'critical' flag 'rpc_gss3_assertion_u' union. Every assertion has a 'critical' flag
that can be used to indicate criticality. Other assertion types are that can be used to indicate criticality. Other assertion types are
described 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. New control message types may be added.
Servers receiving unknown critical client assertions or unknown Servers receiving unknown critical client assertions MUST return an
RPCSEC_GSS_v3 extensions MUST return an error. error.
There is no IANA or other registry for RPCSEC_GSSv3 extensions. All
extensions MUST be done by IETF Protocol Action.
2.4. Data Messages 2.4. Data Messages
RPCSEC_GSS3_DATA messages differ from from RPCSEC_GSSv1 data messages RPCSEC_GSS3_DATA messages differ from from RPCSEC_GSSv1 data messages
in that the version number used MUST be '3' instead of '1'. As noted in that the version number used MUST be '3' instead of '1'. As noted
in Section 2.2 the RPCSEC_GSSv3 context handle is used along with in Section 2.2 the RPCSEC_GSSv3 context handle is used along with
it's sequence number stream. it's sequence number stream.
For RPCSEC_GSSv3 data messages the rpc_gss_cred_vers_3_t in the RPC For RPCSEC_GSSv3 data messages the rpc_gss_cred_vers_3_t in the RPC
message opaque_auth structure is encoded as follows: message opaque_auth structure is encoded as follows:
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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 evaludated by the server in the context of whether
the client and/or user are authenticated, whether compound the client and/or user are authenticated, whether compound
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 (and RPCSEC_GSSv3 supports a notion of critical assertions but there's no
extensions), but there's no need for peers to tell each other what need for peers to tell each other what assertions were granted, or
assertions were granted, or what they were mapped to. 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-
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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.7: [Add text about interaction with GSS-SSV...] --NW]] [[Comment.8: [Add text about interaction with GSS-SSV...] --NW]]
[[Comment.8: I see no reason to use RPCSEC_GSSv3 contexts for NFSv4.x [[Comment.9: I see no reason to use RPCSEC_GSSv3 contexts for NFSv4.x
back channel. --AA]] back channel. --AA]]
[[Comment.9: Since GSS3 requires an RPCSEC_GSSv1 or v2 context handle [[Comment.10: Since GSS3 requires an RPCSEC_GSSv1 or v2 context
to establish a GSS3 context, SSV can not be used as this draft is handle to establish a GSS3 context, SSV can not be used as this draft
written.]] is written.]]
[[Comment.10: AFAICS the reason to use SSV is to avoid using a client [[Comment.11: AFAICS the reason to use SSV is to avoid using a client
machine credential which means compound authentication can not be machine credential which means compound authentication can not be
used. Since GSS3 requires an RPCSEC_GSSv1 or v2 context handle to used. Since GSS3 requires an RPCSEC_GSSv1 or v2 context handle to
establish a GSS3 context, SSV can not be used as the parent context establish a GSS3 context, SSV can not be used as the parent context
for GSSv3. --AA]] for GSSv3. --AA]]
4. IANA Considerations 4. IANA Considerations
This section uses terms that are defined in [8]. This section uses terms that are defined in [8].
There are no IANA considerations in this document. TBDs in this There are no IANA considerations in this document. TBDs in this
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