likely because that value is unrecognized by the underlying
mechanism.
1.2.5: Anonymity Support
In certain situations or environments, an application may wish to
authenticate a peer and/or protect communications using GSS-API per-
message services without revealing its own identity. For example,
consider an application which provides read access to a research
database, and which permits queries by arbitrary requestors. A
client of such a service might wish to authenticate the service, to
establish trust in the information received from it, but might not
wish to disclose its identity to the service for privacy reasons.
In ordinary GSS-API usage, a context initiator's identity is made
available to the context acceptor as part of the context
establishment process. To provide for anonymity support, a facility
(input anon_req_flag to GSS_Init_sec_context()) is provided through
which context initiators may request that their identity not be
provided to the context acceptor. Mechanisms are not required to
honor this request, but a caller will be informed (via returned
anon_state indicator from GSS_Init_sec_context()) whether or not the
request is honored. Note that authentication as the anonymous
principal does not necessarily imply that credentials are not
required in order to establish a context.
The following Object Identifier value is provided as a means to
identify anonymous names, and can be compared against in order to
determine, in a mechanism-independent fashion, whether a name refers
to an anonymous principal:
{1(iso), 3(org), 6(dod), 1(internet), 5(security), 6(nametypes),
3(gss-anonymous-name)}
The recommended symbolic name corresponding to this definition is
GSS_C_NT_ANONYMOUS.
Four possible combinations of anon_state and mutual_state are
possible, with the following results:
anon_state == FALSE, mutual_state == FALSE: initiator
authenticated to target.
anon_state == FALSE, mutual_state == TRUE: initiator authenticated
to target, target authenticated to initiator.
anon_state == TRUE, mutual_state == FALSE: initiator authenticated
as anonymous principal to target.
anon_state == TRUE, mutual_state == TRUE: initiator authenticated
as anonymous principal to target, target authenticated to
initiator.
1.2.6: Initialization
No initialization calls (i.e., calls which must be invoked prior to
invocation of other facilities in the interface) are defined in GSS-
API. As an implication of this fact, GSS-API implementations must
themselves be self-initializing.
1.2.7: Per-Message Protection During Context Establishment
A facility is defined in GSS-V2 to enable protection and buffering of
data messages for later transfer while a security context's
establishment is in GSS_S_CONTINUE_NEEDED status, to be used in cases
where the caller side already possesses the necessary session key to
enable this processing. Specifically, a new state Boolean, called
prot_ready_state, is added to the set of information returned by
GSS_Init_sec_context(), GSS_Accept_sec_context(), and
GSS_Inquire_context().
For context establishment calls, this state Boolean is valid and
interpretable when the associated major_status is either
GSS_S_CONTINUE_NEEDED, or GSS_S_COMPLETE. Callers of GSS-API (both
initiators and acceptors) can assume that per-message protection (via
GSS_Wrap(), GSS_Unwrap(), GSS_GetMIC() and GSS_VerifyMIC()) is
available and ready for use if either: prot_ready_state == TRUE, or
major_status == GSS_S_COMPLETE, though mutual authentication (if
requested) cannot be guaranteed until GSS_S_COMPLETE is returned.
This achieves full, transparent backward compatibility for GSS-API V1
callers, who need not even know of the existence of prot_ready_state,
and who will get the expected behavior from GSS_S_COMPLETE, but who
will not be able to use per-message protection before GSS_S_COMPLETE
is returned.
It is not a requirement that GSS-V2 mechanisms ever return TRUE
prot_ready_state before completion of context establishment (indeed,
some mechanisms will not evolve usable message protection keys,
especially at the context acceptor, before context establishment is
complete). It is expected but not required that GSS-V2 mechanisms
will return TRUE prot_ready_state upon completion of context
establishment if they support per-message protection at all (however
GSS-V2 applications should not assume that TRUE prot_ready_state will
always be returned together with the GSS_S_COMPLETE major_status,
since GSS-V2 implementations may continue to support GSS-V1 mechanism
code, which will never return TRUE prot_ready_state).
When prot_ready_state is returned TRUE, mechanisms shall also set
those context service indicator flags (deleg_state, mutual_state,
replay_det_state, sequence_state, anon_state, trans_state,
conf_avail, integ_avail) which represent facilities confirmed, at
that time, to be available on the context being established. In
situations where prot_ready_state is returned before GSS_S_COMPLETE,
it is possible that additional facilities may be confirmed and
subsequently indicated when GSS_S_COMPLETE is returned.
1.2.8: Implementation Robustness
This section recommends aspects of GSS-API implementation behavior in
the interests of overall robustness.
If a token is presented for processing on a GSS-API security context
and that token is determined to be invalid for that context, the
context's state should not be disrupted for purposes of processing
subsequent valid tokens.
Certain local conditions at a GSS-API implementation (e.g.,
unavailability of memory) may preclude, temporarily or permanently,
the successful processing of tokens on a GSS-API security context,
typically generating GSS_S_FAILURE major_status returns along with
locally-significant minor_status. For robust operation under such
conditions, the following recommendations are made:
Failing calls should free any memory they allocate, so that
callers may retry without causing further loss of resources.
Failure of an individual call on an established context should not
preclude subsequent calls from succeeding on the same context.
Whenever possible, it should be possible for
GSS_Delete_sec_context() calls to be successfully processed even
if other calls cannot succeed, thereby enabling context-related
resources to be released.
2: Interface Descriptions
This section describes the GSS-API's service interface, dividing the
set of calls offered into four groups. Credential management calls
are related to the acquisition and release of credentials by
principals. Context-level calls are related to the management of
security contexts between principals. Per-message calls are related
to the protection of individual messages on established security
contexts. Support calls provide ancillary functions useful to GSS-API
callers. Table 2 groups and summarizes the calls in tabular fashion.
Table 2: GSS-API Calls
CREDENTIAL MANAGEMENT
GSS_Acquire_cred acquire credentials for use
GSS_Release_cred release credentials after use
GSS_Inquire_cred display information about
credentials
GSS_Add_cred construct credentials incrementally
GSS_Inquire_cred_by_mech display per-mechanism credential
information
CONTEXT-LEVEL CALLS
GSS_Init_sec_context initiate outbound security context
GSS_Accept_sec_context accept inbound security context
GSS_Delete_sec_context flush context when no longer needed
GSS_Process_context_token process received control token on
context
GSS_Context_time indicate validity time remaining on
context
GSS_Inquire_context display information about context
GSS_Wrap_size_limit determine GSS_Wrap token size limit
GSS_Export_sec_context transfer context to other process
GSS_Import_sec_context import transferred context
PER-MESSAGE CALLS
GSS_GetMIC apply integrity check, receive as
token separate from message
GSS_VerifyMIC validate integrity check token
along with message
GSS_Wrap sign, optionally encrypt,
encapsulate
GSS_Unwrap decapsulate, decrypt if needed,
validate integrity check
SUPPORT CALLS
GSS_Display_status translate status codes to printable
form
GSS_Indicate_mechs indicate mech_types supported on
local system
GSS_Compare_name compare two names for equality
GSS_Display_name translate name to printable form
GSS_Import_name convert printable name to
normalized form
GSS_Release_name free storage of normalized-form
name
GSS_Release_buffer free storage of printable name
GSS_Release_OID free storage of OID object
GSS_Release_OID_set free storage of OID set object
GSS_Create_empty_OID_set create empty OID set
GSS_Add_OID_set_member add member to OID set
GSS_Test_OID_set_member test if OID is member of OID set
GSS_OID_to_str display OID as string
GSS_Str_to_OID construct OID from string
GSS_Inquire_names_for_mech indicate name types supported by
mechanism
GSS_Inquire_mechs_for_name indicates mechanisms supporting name
type
GSS_Canonicalize_name translate name to per-mechanism form
GSS_Export_name externalize per-mechanism name
GSS_Duplicate_name duplicate name object
2.1: Credential management calls
These GSS-API calls provide functions related to the management of
credentials. Their characterization with regard to whether or not
they may block pending exchanges with other network entities (e.g.,
directories or authentication servers) depends in part on OS-specific
(extra-GSS-API) issues, so is not specified in this document.
The GSS_Acquire_cred() call is defined within the GSS-API in support
of application portability, with a particular orientation towards
support of portable server applications. It is recognized that (for
certain systems and mechanisms) credentials for interactive users may
be managed differently from credentials for server processes; in such
environments, it is the GSS-API implementation's responsibility to
distinguish these cases and the procedures for making this
distinction are a local matter. The GSS_Release_cred() call provides
a means for callers to indicate to the GSS-API that use of a
credentials structure is no longer required. The GSS_Inquire_cred()
call allows callers to determine information about a credentials
structure. The GSS_Add_cred() call enables callers to append
elements to an existing credential structure, allowing iterative
construction of a multi-mechanism credential. The
GSS_Inquire_cred_by_mech() call enables callers to extract per-
mechanism information describing a credentials structure.
2.1.1: GSS_Acquire_cred call
Inputs:
o desired_name INTERNAL NAME, -NULL requests locally-determined
default
o lifetime_req INTEGER,-in seconds; 0 requests default
o desired_mechs SET OF OBJECT IDENTIFIER,-empty set requests
system-selected default
o cred_usage INTEGER -0=INITIATE-AND-ACCEPT, 1=INITIATE-ONLY,
2=ACCEPT-ONLY
Outputs:
o major_status INTEGER,
o minor_status INTEGER,
o output_cred_handle CREDENTIAL HANDLE,
o actual_mechs SET OF OBJECT IDENTIFIER,
o lifetime_rec INTEGER -in seconds, or reserved value for
INDEFINITE
Return major_status codes:
o GSS_S_COMPLETE indicates that requested credentials were
successfully established, for the duration indicated in
lifetime_rec, suitable for the usage requested in cred_usage,
for the set of mech_types indicated in actual_mechs, and that
those credentials can be referenced for subsequent use with
the handle returned in output_cred_handle.
o GSS_S_BAD_MECH indicates that a mech_type unsupported by the
GSS-API implementation type was requested, causing the
credential establishment operation to fail.
o GSS_S_BAD_NAMETYPE indicates that the provided desired_name is
uninterpretable or of a type unsupported by the applicable
underlying GSS-API mechanism(s), so no credentials could be
established for the accompanying desired_name.
o GSS_S_BAD_NAME indicates that the provided desired_name is
inconsistent in terms of internally-incorporated type specifier
information, so no credentials could be established for the
accompanying desired_name.
o GSS_S_FAILURE indicates that credential establishment failed
for reasons unspecified at the GSS-API level, including lack
of authorization to establish and use credentials associated
with the identity named in the input desired_name argument.
GSS_Acquire_cred() is used to acquire credentials so that a
principal can (as a function of the input cred_usage parameter)
initiate and/or accept security contexts under the identity
represented by the desired_name input argument. On successful
completion, the returned output_cred_handle result provides a handle
for subsequent references to the acquired credentials. Typically,
single-user client processes requesting that default credential
behavior be applied for context establishment purposes will have no
need to invoke this call.
A caller may provide the value NULL for desired_name, signifying a
request for credentials corresponding to a principal identity
selected by default for the caller. The procedures used by GSS-API
implementations to select the appropriate principal identity in
response to such a request are local matters. It is possible that
multiple pre-established credentials may exist for the same principal
identity (for example, as a result of multiple user login sessions)
when GSS_Acquire_cred() is called; the means used in such cases to
select a specific credential are local matters. The input
lifetime_req argument to GSS_Acquire_cred() may provide useful
information for local GSS-API implementations to employ in making
this disambiguation in a manner which will best satisfy a caller's
intent.
The lifetime_rec result indicates the length of time for which the
acquired credentials will be valid, as an offset from the present. A
mechanism may return a reserved value indicating INDEFINITE if no
constraints on credential lifetime are imposed. A caller of
GSS_Acquire_cred() can request a length of time for which acquired
credentials are to be valid (lifetime_req argument), beginning at the
present, or can request credentials with a default validity interval.
(Requests for postdated credentials are not supported within the
GSS-API.) Certain mechanisms and implementations may bind in
credential validity period specifiers at a point preliminary to
invocation of the GSS_Acquire_cred() call (e.g., in conjunction with
user login procedures). As a result, callers requesting non-default
values for lifetime_req must recognize that such requests cannot
always be honored and must be prepared to accommodate the use of
returned credentials with different lifetimes as indicated in
lifetime_rec.
The caller of GSS_Acquire_cred() can explicitly specify a set of
mech_types which are to be accommodated in the returned credentials
(desired_mechs argument), or can request credentials for a system-
defined default set of mech_types. Selection of the system-specified
default set is recommended in the interests of application
portability. The actual_mechs return value may be interrogated by the
caller to determine the set of mechanisms with which the returned
credentials may be used.
2.1.2: GSS_Release_cred call
Input:
o cred_handle CREDENTIAL HANDLE - NULL specifies that
the credential elements used when default credential behavior
is requested be released.
Outputs:
o major_status INTEGER,
o minor_status INTEGER
Return major_status codes:
o GSS_S_COMPLETE indicates that the credentials referenced by the
input cred_handle were released for purposes of subsequent
access by the caller. The effect on other processes which may
be authorized shared access to such credentials is a local
matter.
o GSS_S_NO_CRED indicates that no release operation was
performed, either because the input cred_handle was invalid or
because the caller lacks authorization to access the
referenced credentials.
o GSS_S_FAILURE indicates that the release operation failed for
reasons unspecified at the GSS-API level.
Provides a means for a caller to explicitly request that credentials
be released when their use is no longer required. Note that system-
specific credential management functions are also likely to exist,
for example to assure that credentials shared among processes are
properly deleted when all affected processes terminate, even if no
explicit release requests are issued by those processes. Given the
fact that multiple callers are not precluded from gaining authorized
access to the same credentials, invocation of GSS_Release_cred()
cannot be assumed to delete a particular set of credentials on a
system-wide basis.
2.1.3: GSS_Inquire_cred call
Input:
o cred_handle CREDENTIAL HANDLE -NULL specifies that the
credential elements used when default credential behavior is
requested are to be queried
Outputs:
o major_status INTEGER,
o minor_status INTEGER,
o cred_name INTERNAL NAME,
o lifetime_rec INTEGER -in seconds, or reserved value for
INDEFINITE
o cred_usage INTEGER, -0=INITIATE-AND-ACCEPT, 1=INITIATE-ONLY,
2=ACCEPT-ONLY
o mech_set SET OF OBJECT IDENTIFIER
Return major_status codes:
o GSS_S_COMPLETE indicates that the credentials referenced by the
input cred_handle argument were valid, and that the output
cred_name, lifetime_rec, and cred_usage values represent,
respectively, the credentials' associated principal name,
remaining lifetime, suitable usage modes, and supported
mechanism types.
o GSS_S_NO_CRED indicates that no information could be returned
about the referenced credentials, either because the input
cred_handle was invalid or because the caller lacks
authorization to access the referenced credentials.
o GSS_S_DEFECTIVE_CREDENTIAL indicates that the referenced
credentials are invalid.
o GSS_S_CREDENTIALS_EXPIRED indicates that the referenced
credentials have expired.
o GSS_S_FAILURE indicates that the operation failed for
reasons unspecified at the GSS-API level.
The GSS_Inquire_cred() call is defined primarily for the use of those
callers which request use of default credential behavior rather than
acquiring credentials explicitly with GSS_Acquire_cred(). It enables
callers to determine a credential structure's associated principal
name, remaining validity period, usability for security context
initiation and/or acceptance, and supported mechanisms.
For a multi-mechanism credential, the returned "lifetime" specifier
indicates the shortest lifetime of any of the mechanisms' elements in
the credential (for either context initiation or acceptance
purposes).
GSS_Inquire_cred() should indicate INITIATE-AND-ACCEPT for
"cred_usage" if both of the following conditions hold:
(1) there exists in the credential an element which allows context
initiation using some mechanism
(2) there exists in the credential an element which allows context
acceptance using some mechanism (allowably, but not necessarily,
one of the same mechanism(s) qualifying for (1)).
If condition (1) holds but not condition (2), GSS_Inquire_cred()
should indicate INITIATE-ONLY for "cred_usage". If condition (2)
holds but not condition (1), GSS_Inquire_cred() should indicate
ACCEPT-ONLY for "cred_usage".
Callers requiring finer disambiguation among available combinations
of lifetimes, usage modes, and mechanisms should call the
GSS_Inquire_cred_by_mech() routine, passing that routine one of the
mech OIDs returned by GSS_Inquire_cred().
2.1.4: GSS_Add_cred call
Inputs:
o input_cred_handle CREDENTIAL HANDLE - handle to credential
structure created with prior GSS_Acquire_cred() or
GSS_Add_cred() call, or NULL to append elements to the set
which are applied for the caller when default credential
behavior is specified.
o desired_name INTERNAL NAME - NULL requests locally-determined
default
o initiator_time_req INTEGER - in seconds; 0 requests default
o acceptor_time_req INTEGER - in seconds; 0 requests default
o desired_mech OBJECT IDENTIFIER
o cred_usage INTEGER - 0=INITIATE-AND-ACCEPT, 1=INITIATE-ONLY,
2=ACCEPT-ONLY
Outputs:
o major_status INTEGER,
o minor_status INTEGER,
o output_cred_handle CREDENTIAL HANDLE, - NULL to request that
credential elements be added "in place" to the credential
structure identified by input_cred_handle, non-NULL pointer
to request that a new credential structure and handle be created.
o actual_mechs SET OF OBJECT IDENTIFIER,
o initiator_time_rec INTEGER - in seconds, or reserved value for
INDEFINITE
o acceptor_time_rec INTEGER - in seconds, or reserved value for
INDEFINITE
o cred_usage INTEGER, -0=INITIATE-AND-ACCEPT, 1=INITIATE-ONLY,
2=ACCEPT-ONLY
o mech_set SET OF OBJECT IDENTIFIER -- full set of mechanisms
supported by resulting credential.
Return major_status codes:
o GSS_S_COMPLETE indicates that the credentials referenced by
the input_cred_handle argument were valid, and that the
resulting credential from GSS_Add_cred() is valid for the
durations indicated in initiator_time_rec and acceptor_time_rec,
suitable for the usage requested in cred_usage, and for the
mechanisms indicated in actual_mechs.
o GSS_S_DUPLICATE_ELEMENT indicates that the input desired_mech
specified a mechanism for which the referenced credential
already contained a credential element with overlapping
cred_usage and validity time specifiers.
o GSS_S_BAD_MECH indicates that the input desired_mech specified
a mechanism unsupported by the GSS-API implementation, causing
the GSS_Add_cred() operation to fail.
o GSS_S_BAD_NAMETYPE indicates that the provided desired_name
is uninterpretable or of a type unsupported by the applicable
underlying GSS-API mechanism(s), so the GSS_Add_cred() operation
could not be performed for that name.
o GSS_S_BAD_NAME indicates that the provided desired_name is
inconsistent in terms of internally-incorporated type specifier
information, so the GSS_Add_cred() operation could not be
performed for that name.
o GSS_S_NO_CRED indicates that the input_cred_handle referenced
invalid or inaccessible credentials.
o GSS_S_FAILURE indicates that the operation failed for
reasons unspecified at the GSS-API level, including lack of
authorization to establish or use credentials representing
the requested identity.
GSS_Add_cred() enables callers to construct credentials iteratively
by adding credential elements in successive operations, corresponding
to different mechanisms. This offers particular value in multi-
mechanism environments, as the major_status and minor_status values
returned on each iteration are individually visible and can therefore
be interpreted unambiguously on a per-mechanism basis.
The same input desired_name, or default reference, should be used on
all GSS_Acquire_cred() and GSS_Add_cred() calls corresponding to a
particular credential.
2.1.5: GSS_Inquire_cred_by_mech call
Inputs:
o cred_handle CREDENTIAL HANDLE -- NULL specifies that the
credential elements used when default credential behavior is
requested are to be queried
o mech_type OBJECT IDENTIFIER -- specific mechanism for
which credentials are being queried
Outputs:
o major_status INTEGER,
o minor_status INTEGER,
o cred_name INTERNAL NAME, -- guaranteed to be MN
o lifetime_rec_initiate INTEGER -- in seconds, or reserved value for
INDEFINITE
o lifetime_rec_accept INTEGER -- in seconds, or reserved value for
INDEFINITE
o cred_usage INTEGER, -0=INITIATE-AND-ACCEPT, 1=INITIATE-ONLY,
2=ACCEPT-ONLY
Return major_status codes:
o GSS_S_COMPLETE indicates that the credentials referenced by the
input cred_handle argument were valid, that the mechanism
indicated by the input mech_type was represented with elements
within those credentials, and that the output cred_name,
lifetime_rec_initiate, lifetime_rec_accept, and cred_usage values
represent, respectively, the credentials' associated principal
name, remaining lifetimes, and suitable usage modes.
o GSS_S_NO_CRED indicates that no information could be returned
about the referenced credentials, either because the input
cred_handle was invalid or because the caller lacks
authorization to access the referenced credentials.
o GSS_S_DEFECTIVE_CREDENTIAL indicates that the referenced
credentials are invalid.
o GSS_S_CREDENTIALS_EXPIRED indicates that the referenced
credentials have expired.
o GSS_S_BAD_MECH indicates that the referenced credentials do not
contain elements for the requested mechanism.
o GSS_S_FAILURE indicates that the operation failed for reasons
unspecified at the GSS-API level.
The GSS_Inquire_cred_by_mech() call enables callers in multi-
mechanism environments to acquire specific data about available
combinations of lifetimes, usage modes, and mechanisms within a
credential structure. The lifetime_rec_initiate result indicates the
available lifetime for context initiation purposes; the
lifetime_rec_accept result indicates the available lifetime for
context acceptance purposes.
2.2: Context-level calls
This group of calls is devoted to the establishment and management of
security contexts between peers. A context's initiator calls
GSS_Init_sec_context(), resulting in generation of a token which the
caller passes to the target. At the target, that token is passed to
GSS_Accept_sec_context(). Depending on the underlying mech_type and
specified options, additional token exchanges may be performed in the
course of context establishment; such exchanges are accommodated by
GSS_S_CONTINUE_NEEDED status returns from GSS_Init_sec_context() and
GSS_Accept_sec_context().
Either party to an established context may invoke
GSS_Delete_sec_context() to flush context information when a context
is no longer required. GSS_Process_context_token() is used to
process received tokens carrying context-level control information.
GSS_Context_time() allows a caller to determine the length of time
for which an established context will remain valid.
GSS_Inquire_context() returns status information describing context
characteristics. GSS_Wrap_size_limit() allows a caller to determine
the size of a token which will be generated by a GSS_Wrap()
operation. GSS_Export_sec_context() and GSS_Import_sec_context()
enable transfer of active contexts between processes on an end
system.
2.2.1: GSS_Init_sec_context call
Inputs:
o claimant_cred_handle CREDENTIAL HANDLE, -NULL specifies "use
default"
o input_context_handle CONTEXT HANDLE, -0 specifies "none assigned
yet"
o targ_name INTERNAL NAME,
o mech_type OBJECT IDENTIFIER, -NULL parameter specifies "use
default"
o deleg_req_flag BOOLEAN,
o mutual_req_flag BOOLEAN,
o replay_det_req_flag BOOLEAN,
o sequence_req_flag BOOLEAN,
o anon_req_flag BOOLEAN,
o lifetime_req INTEGER,-0 specifies default lifetime
o chan_bindings OCTET STRING,
o input_token OCTET STRING-NULL or token received from target
Outputs:
o major_status INTEGER,
o minor_status INTEGER,
o output_context_handle CONTEXT HANDLE,
o mech_type OBJECT IDENTIFIER, -actual mechanism always
indicated, never NULL
o output_token OCTET STRING, -NULL or token to pass to context
target
o deleg_state BOOLEAN,
o mutual_state BOOLEAN,
o replay_det_state BOOLEAN,
o sequence_state BOOLEAN,
o anon_state BOOLEAN,
o trans_state BOOLEAN,
o prot_ready_state BOOLEAN, -- see Section 1.2.7
o conf_avail BOOLEAN,
o integ_avail BOOLEAN,
o lifetime_rec INTEGER - in seconds, or reserved value for
INDEFINITE
This call may block pending network interactions for those mech_types
in which an authentication server or other network entity must be
consulted on behalf of a context initiator in order to generate an
output_token suitable for presentation to a specified target.
Return major_status codes:
o GSS_S_COMPLETE indicates that context-level information was
successfully initialized, and that the returned output_token
will provide sufficient information for the target to perform
per-message processing on the newly-established context.
o GSS_S_CONTINUE_NEEDED indicates that control information in the
returned output_token must be sent to the target, and that a
reply must be received and passed as the input_token argument
to a continuation call to GSS_Init_sec_context(), before
per-message processing can be performed in conjunction with
this context.
o GSS_S_DEFECTIVE_TOKEN indicates that consistency checks
performed on the input_token failed, preventing further
processing from being performed based on that token.
o GSS_S_DEFECTIVE_CREDENTIAL indicates that consistency checks
performed on the credential structure referenced by
claimant_cred_handle failed, preventing further processing from
being performed using that credential structure.
o GSS_S_BAD_SIG indicates that the received input_token
contains an incorrect integrity check, so context setup cannot
be accomplished.
o GSS_S_NO_CRED indicates that no context was established,
either because the input cred_handle was invalid, because the
referenced credentials are valid for context acceptor use
only, or because the caller lacks authorization to access the
referenced credentials.
o GSS_S_CREDENTIALS_EXPIRED indicates that the credentials
provided through the input claimant_cred_handle argument are no
longer valid, so context establishment cannot be completed.
o GSS_S_BAD_BINDINGS indicates that a mismatch between the
caller-provided chan_bindings and those extracted from the
input_token was detected, signifying a security-relevant
event and preventing context establishment. (This result will
be returned by GSS_Init_sec_context only for contexts where
mutual_state is TRUE.)
o GSS_S_OLD_TOKEN indicates that the input_token is too old to
be checked for integrity. This is a fatal error during context
establishment.
o GSS_S_DUPLICATE_TOKEN indicates that the input token has a
correct integrity check, but is a duplicate of a token already
processed. This is a fatal error during context establishment.
o GSS_S_NO_CONTEXT indicates that no valid context was recognized
for the input context_handle provided; this major status will
be returned only for successor calls following GSS_S_CONTINUE_
NEEDED status returns.
o GSS_S_BAD_NAMETYPE indicates that the provided targ_name is
of a type uninterpretable or unsupported by the applicable
underlying GSS-API mechanism(s), so context establishment
cannot be completed.
o GSS_S_BAD_NAME indicates that the provided targ_name is
inconsistent in terms of internally-incorporated type specifier
information, so context establishment cannot be accomplished.
o GSS_S_BAD_MECH indicates receipt of a context establishment token
or of a caller request specifying a mechanism unsupported by
the local system or with the caller's active credentials
o GSS_S_FAILURE indicates that context setup could not be
accomplished for reasons unspecified at the GSS-API level, and
that no interface-defined recovery action is available.
This routine is used by a context initiator, and ordinarily emits one
(or, for the case of a multi-step exchange, more than one)
output_token suitable for use by the target within the selected
mech_type's protocol. Using information in the credentials structure
referenced by claimant_cred_handle, GSS_Init_sec_context()
initializes the data structures required to establish a security
context with target targ_name. The targ_name may be any valid
INTERNAL NAME; it need not be an MN. The claimant_cred_handle must
correspond to the same valid credentials structure on the initial
call to GSS_Init_sec_context() and on any successor calls resulting
from GSS_S_CONTINUE_NEEDED status returns; different protocol
sequences modeled by the GSS_S_CONTINUE_NEEDED facility will require
access to credentials at different points in the context
establishment sequence.
The input_context_handle argument is 0, specifying "not yet
assigned", on the first GSS_Init_sec_context() call relating to a
given context. If successful (i.e., if accompanied by major_status
GSS_S_COMPLETE or GSS_S_CONTINUE_NEEDED), and only if successful, the
initial GSS_Init_sec_context() call returns a non-zero
output_context_handle for use in future references to this context.
Once a non-zero output_context_handle has been returned, GSS-API
callers should call GSS_Delete_sec_context() to release context-
related resources if errors occur in later phases of context
establishment, or when an established context is no longer required.
When continuation attempts to GSS_Init_sec_context() are needed to
perform context establishment, the previously-returned non-zero
handle value is entered into the input_context_handle argument and
will be echoed in the returned output_context_handle argument. On
such continuation attempts (and only on continuation attempts) the
input_token value is used, to provide the token returned from the
context's target.
The chan_bindings argument is used by the caller to provide
information binding the security context to security-related
characteristics (e.g., addresses, cryptographic keys) of the
underlying communications channel. See Section 1.1.6 of this document
for more discussion of this argument's usage.
The input_token argument contains a message received from the target,
and is significant only on a call to GSS_Init_sec_context() which
follows a previous return indicating GSS_S_CONTINUE_NEEDED
major_status.
It is the caller's responsibility to establish a communications path
to the target, and to transmit any returned output_token (independent
of the accompanying returned major_status value) to the target over
that path. The output_token can, however, be transmitted along with
the first application-provided input message to be processed by
GSS_GetMIC() or GSS_Wrap() in conjunction with a successfully-
established context.
The initiator may request various context-level functions through
input flags: the deleg_req_flag requests delegation of access rights,
the mutual_req_flag requests mutual authentication, the
replay_det_req_flag requests that replay detection features be
applied to messages transferred on the established context, and the
sequence_req_flag requests that sequencing be enforced. (See Section
1.2.3 for more information on replay detection and sequencing
features.) The anon_req_flag requests that the initiator's identity
not be transferred within tokens to be sent to the acceptor.
Not all of the optionally-requestable features will be available in
all underlying mech_types. The corresponding return state values
deleg_state, mutual_state, replay_det_state, and sequence_state
indicate, as a function of mech_type processing capabilities and
initiator-provided input flags, the set of features which will be
active on the context. The returned trans_state value indicates
whether the context is transferable to other processes through use of
GSS_Export_sec_context(). These state indicators' values are
undefined unless either the routine's major_status indicates
GSS_S_COMPLETE, or TRUE prot_ready_state is returned along with
GSS_S_CONTINUE_NEEDED major_status; for the latter case, it is
possible that additional features, not confirmed or indicated along
with TRUE prot_ready_state, will be confirmed and indicated when
GSS_S_COMPLETE is subsequently returned.
The returned anon_state and prot_ready_state values are significant
for both GSS_S_COMPLETE and GSS_S_CONTINUE_NEEDED major_status
returns from GSS_Init_sec_context(). When anon_state is returned
TRUE, this indicates that neither the current token nor its
predecessors delivers or has delivered the initiator's identity.
Callers wishing to perform context establishment only if anonymity
support is provided should transfer a returned token from
GSS_Init_sec_context() to the peer only if it is accompanied by a
TRUE anon_state indicator. When prot_ready_state is returned TRUE in
conjunction with GSS_S_CONTINUE_NEEDED major_status, this indicates
that per-message protection operations may be applied on the context:
see Section 1.2.7 for further discussion of this facility.
Failure to provide the precise set of features requested by the
caller does not cause context establishment to fail; it is the
caller's prerogative to delete the context if the feature set
provided is unsuitable for the caller's use.
The returned mech_type value indicates the specific mechanism
employed on the context, is valid only along with major_status
GSS_S_COMPLETE, and will never indicate the value for "default".
Note that, for the case of certain mechanisms which themselves
perform negotiation, the returned mech_type result may indicate
selection of a mechanism identified by an OID different than that
passed in the input mech_type argument.
The conf_avail return value indicates whether the context supports
per-message confidentiality services, and so informs the caller
whether or not a request for encryption through the conf_req_flag
input to GSS_Wrap() can be honored. In similar fashion, the
integ_avail return value indicates whether per-message integrity
services are available (through either GSS_GetMIC() or GSS_Wrap()) on
the established context. These state indicators' values are undefined
unless either the routine's major_status indicates GSS_S_COMPLETE, or
TRUE prot_ready_state is returned along with GSS_S_CONTINUE_NEEDED
major_status.
The lifetime_req input specifies a desired upper bound for the
lifetime of the context to be established, with a value of 0 used to
request a default lifetime. The lifetime_rec return value indicates
the length of time for which the context will be valid, expressed as
an offset from the present; depending on mechanism capabilities,
credential lifetimes, and local policy, it may not correspond to the
value requested in lifetime_req. If no constraints on context
lifetime are imposed, this may be indicated by returning a reserved
value representing INDEFINITE lifetime_req. The value of lifetime_rec
is undefined unless the routine's major_status indicates
GSS_S_COMPLETE.
If the mutual_state is TRUE, this fact will be reflected within the
output_token. A call to GSS_Accept_sec_context() at the target in
conjunction with such a context will return a token, to be processed
by a continuation call to GSS_Init_sec_context(), in order to
achieve mutual authentication.
2.2.2: GSS_Accept_sec_context call
Inputs:
o acceptor_cred_handle CREDENTIAL HANDLE, -- NULL specifies
"use default"
o input_context_handle CONTEXT HANDLE, -- 0 specifies
"not yet assigned"
o chan_bindings OCTET STRING,
o input_token OCTET STRING
Outputs:
o major_status INTEGER,
o minor_status INTEGER,
o src_name INTERNAL NAME, -- guaranteed to be MN
o mech_type OBJECT IDENTIFIER,
o output_context_handle CONTEXT HANDLE,
o deleg_state BOOLEAN,
o mutual_state BOOLEAN,
o replay_det_state BOOLEAN,
o sequence_state BOOLEAN,
o anon_state BOOLEAN,
o trans_state BOOLEAN,
o prot_ready_state BOOLEAN, -- see Section 1.2.7 for discussion
o conf_avail BOOLEAN,
o integ_avail BOOLEAN,
o lifetime_rec INTEGER, - in seconds, or reserved value for
INDEFINITE
o delegated_cred_handle CREDENTIAL HANDLE,
o output_token OCTET STRING -NULL or token to pass to context
initiator
This call may block pending network interactions for those mech_types
in which a directory service or other network entity must be
consulted on behalf of a context acceptor in order to validate a
received input_token.
Return major_status codes:
o GSS_S_COMPLETE indicates that context-level data structures
were successfully initialized, and that per-message processing
can now be performed in conjunction with this context.
o GSS_S_CONTINUE_NEEDED indicates that control information in the
returned output_token must be sent to the initiator, and that
a response must be received and passed as the input_token
argument to a continuation call to GSS_Accept_sec_context(),
before per-message processing can be performed in conjunction
with this context.
o GSS_S_DEFECTIVE_TOKEN indicates that consistency checks performed
on the input_token failed, preventing further processing from
being performed based on that token.
o GSS_S_DEFECTIVE_CREDENTIAL indicates that consistency checks
performed on the credential structure referenced by
acceptor_cred_handle failed, preventing further processing from
being performed using that credential structure.
o GSS_S_BAD_SIG indicates that the received input_token contains
an incorrect integrity check, so context setup cannot be
accomplished.
o GSS_S_DUPLICATE_TOKEN indicates that the integrity check on the
received input_token was correct, but that the input_token
was recognized as a duplicate of an input_token already
processed. No new context is established.
o GSS_S_OLD_TOKEN indicates that the integrity check on the received
input_token was correct, but that the input_token is too old
to be checked for duplication against previously-processed
input_tokens. No new context is established.
o GSS_S_NO_CRED indicates that no context was established, either
because the input cred_handle was invalid, because the
referenced credentials are valid for context initiator use
only, or because the caller lacks authorization to access the
referenced credentials.
o GSS_S_CREDENTIALS_EXPIRED indicates that the credentials provided
through the input acceptor_cred_handle argument are no
longer valid, so context establishment cannot be completed.
o GSS_S_BAD_BINDINGS indicates that a mismatch between the
caller-provided chan_bindings and those extracted from the
input_token was detected, signifying a security-relevant
event and preventing context establishment.
o GSS_S_NO_CONTEXT indicates that no valid context was recognized
for the input context_handle provided; this major status will
be returned only for successor calls following GSS_S_CONTINUE_
NEEDED status returns.
o GSS_S_BAD_MECH indicates receipt of a context establishment token
specifying a mechanism unsupported by the local system or with
the caller's active credentials.
o GSS_S_FAILURE indicates that context setup could not be
accomplished for reasons unspecified at the GSS-API level, and
that no interface-defined recovery action is available.
The GSS_Accept_sec_context() routine is used by a context target.
Using information in the credentials structure referenced by the
input acceptor_cred_handle, it verifies the incoming input_token and
(following the successful completion of a context establishment
sequence) returns the authenticated src_name and the mech_type used.
The returned src_name is guaranteed to be an MN, processed by the
mechanism under which the context was established. The
acceptor_cred_handle must correspond to the same valid credentials
structure on the initial call to GSS_Accept_sec_context() and on any
successor calls resulting from GSS_S_CONTINUE_NEEDED status returns;
different protocol sequences modeled by the GSS_S_CONTINUE_NEEDED
mechanism will require access to credentials at different points in
the context establishment sequence.
The input_context_handle argument is 0, specifying "not yet
assigned", on the first GSS_Accept_sec_context() call relating to a
given context. If successful (i.e., if accompanied by major_status
GSS_S_COMPLETE or GSS_S_CONTINUE_NEEDED), and only if successful, the
initial GSS_Accept_sec_context() call returns a non-zero
output_context_handle for use in future references to this context.
Once a non-zero output_context_handle has been returned, GSS-API
callers should call GSS_Delete_sec_context() to release context-
related resources if errors occur in later phases of context
establishment, or when an established context is no longer required.
The chan_bindings argument is used by the caller to provide
information binding the security context to security-related
characteristics (e.g., addresses, cryptographic keys) of the
underlying communications channel. See Section 1.1.6 of this document
for more discussion of this argument's usage.
The returned state results (deleg_state, mutual_state,
replay_det_state, sequence_state, anon_state, trans_state, and
prot_ready_state) reflect the same information as described for
GSS_Init_sec_context(), and their values are significant under the
same return state conditions.
The conf_avail return value indicates whether the context supports
per-message confidentiality services, and so informs the caller
whether or not a request for encryption through the conf_req_flag
input to GSS_Wrap() can be honored. In similar fashion, the
integ_avail return value indicates whether per-message integrity
services are available (through either GSS_GetMIC() or GSS_Wrap())
on the established context. These values are significant under the
same return state conditions as described under
GSS_Init_sec_context().
The lifetime_rec return value is significant only in conjunction with
GSS_S_COMPLETE major_status, and indicates the length of time for
which the context will be valid, expressed as an offset from the
present.
The mech_type return value indicates the specific mechanism employed
on the context, is valid only along with major_status GSS_S_COMPLETE,
and will never indicate the value for "default".
The delegated_cred_handle result is significant only when deleg_state
is TRUE, and provides a means for the target to reference the
delegated credentials. The output_token result, when non-NULL,
provides a context-level token to be returned to the context
initiator to continue a multi-step context establishment sequence. As
noted with GSS_Init_sec_context(), any returned token should be
transferred to the context's peer (in this case, the context
initiator), independent of the value of the accompanying returned
major_status.
Note: A target must be able to distinguish a context-level
input_token, which is passed to GSS_Accept_sec_context(), from the
per-message data elements passed to GSS_VerifyMIC() or GSS_Unwrap().
These data elements may arrive in a single application message, and
GSS_Accept_sec_context() must be performed before per-message
processing can be performed successfully.
2.2.3: GSS_Delete_sec_context call
Input:
o context_handle CONTEXT HANDLE
Outputs:
o major_status INTEGER,
o minor_status INTEGER,
o output_context_token OCTET STRING
Return major_status codes:
o GSS_S_COMPLETE indicates that the context was recognized, and that
relevant context-specific information was flushed. If the caller
provides a non-null buffer to receive an output_context_token, and
the mechanism returns a non-NULL token into that buffer, the
returned output_context_token is ready for transfer to the
context's peer.
o GSS_S_NO_CONTEXT indicates that no valid context was recognized
for the input context_handle provided, so no deletion was
performed.
o GSS_S_FAILURE indicates that the context is recognized, but
that the GSS_Delete_sec_context() operation could not be
performed for reasons unspecified at the GSS-API level.
This call may block pending network interactions for mech_types in
which active notification must be made to a central server when a
security context is to be deleted.
This call can be made by either peer in a security context, to flush
context-specific information. If a non-null output_context_token
parameter is provided by the caller, an output_context_token may be