One document matched: draft-ietf-cat-gssv2-cbind-00.txt
Internet draft J.Wray
IETF Common Authentication Technology WG Digital Equipment Corporation
<draft-ietf-cat-gssv2-cbind-00.txt> March 1995
Generic Security Service API Version 2 : C-bindings
1. STATUS OF THIS MEMO
This document is an Internet Draft. Internet Drafts are working
documents of the Internet Engineering Task Force (IETF), its Areas,
and its Working Groups. Note that other groups may also distribute
working documents as Internet Drafts. Internet Drafts are draft
documents valid for a maximum of six months. Internet Drafts may be
updated, replaced, or obsoleted by other documents at any time. It
is not appropriate to use Internet Drafts as reference material or to
cite them other than as a "working draft" or "work in progress."
Please check the I-D abstract listing contained in each Internet
Draft directory to learn the current status of this or any other
Internet Draft.
Comments on this document should be sent to "cat-ietf@MIT.EDU", the
IETF Common Authentication Technology WG discussion list.
2. ABSTRACT
This draft document specifies C language bindings for Version 2 of
the Generic Security Service Application Program Interface (GSS-API),
which is described at a language-independent conceptual level in
other drafts.
The Generic Security Service Application Programming Interface
provides security services to its callers, and is intended for
implementation atop a variety of underlying cryptographic mechanisms.
Typically, GSS-API callers will be application protocols into which
security enhancements are integrated through invocation of services
provided by the GSS-API. The GSS-API allows a caller application to
authenticate a principal identity associated with a peer application,
to delegate rights to a peer, and to apply security services such as
confidentiality and integrity on a per-message basis.
3. INTRODUCTION
The Generic Security Service Application Programming Interface
[GSSAPI] provides security services to calling applications. It
allows a communicating application to authenticate the user
associated with another application, to delegate rights to another
application, and to apply security services such as confidentiality
and integrity on a per-message basis.
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There are four stages to using the GSS-API:
(a) The application acquires a set of credentials with which it may
prove its identity to other processes. The application's
credentials vouch for its global identity, which may or may not
be related to any local username under which it may be running.
(b) A pair of communicating applications establish a joint security
context using their credentials. The security context is a
pair of GSS-API data structures that contain shared state
information, which is required in order that per-message
security services may be provided. Examples of state that
might be shared between applications as part of a security
context are cryptographic keys, and message sequence numbers.
As part of the establishment of a security context, the context
initiator is authenticated to the responder, and may require
that the responder is authenticated in turn. The initiator may
optionally give the responder the right to initiate further
security contexts, acting as an agent or delegate of the
initiator. This transfer of rights is termed delegation, and
is achieved by creating a set of credentials, similar to those
used by the initiating application, but which may be used by
the responder.
To establish and maintain the shared information that makes up
the security context, certain GSS-API calls will return a token
data structure, which is a cryptographically protected opaque
data type. The caller of such a GSS-API routine is responsible
for transferring the token to the peer application,
encapsulated if necessary in an application-application
protocol. On receipt of such a token, the peer application
should pass it to a corresponding GSS-API routine which will
decode the token and extract the information, updating the
security context state information accordingly.
(c) Per-message services are invoked to apply either:
(i) integrity and data origin authentication, or
(ii) confidentiality, integrity and data origin authentication
to application data, which are treated by GSS-API as arbitrary
octet-strings. An application transmitting a message that it
wishes to protect will call the appropriate GSS-API routine
(gss_get_mic or gss_wrap) to apply protection, specifying the
appropriate security context, and send the resulting token to
the receiving application. The receiver will pass the received
token (and, in the case of data protected by gss_get_mic, the
accompanying message-data) to the corresponding decoding
routine (gss_verify_mic or gss_unwrap) to remove the protection
and validate the data.
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(d) At the completion of a communications session (which may extend
across several transport connections), each application calls a
GSS-API routine to delete the security context. Multiple
contexts may also be used (either successively or
simultaneously) within a single communications association, at
the option of the applications.
4. GSS-API ROUTINES
This section lists the routines that make up the GSS-API, and offers
a brief description of the purpose of each routine. Detailed
descriptions of each routine are listed in alphabetical order in
section 7.
Table 4-1 GSS-API Credential-management Routines
ROUTINE SECTION FUNCTION
gss_acquire_cred 7.2 Assume a global identity;
Obtain a GSS-API credential
handle for pre-existing
credentials.
gss_inquire_cred 7.15 Obtain information about
a credential.
gss_release_cred 7.18 Discard a credential handle.
Table 4-2 GSS-API Context-level Routines
ROUTINE SECTION FUNCTION
gss_init_sec_context 7.13 Initiate a security context
with a peer application
gss_accept_sec_context 7.1 Accept a security context
initiated by a peer
application
gss_delete_sec_context 7.5 Discard a security context
gss_process_context_token 7.16 Process a token on a security
context from a peer
application
gss_context_time 7.4 Determine for how long a
context will remain valid
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gss_inquire_context 7.14 Obtain information about a
security context
gss_wrap_size_limit 7.24 Determine token-size limit for
gss_wrap on a context
Table 4-3 GSS-API Per-message Routines
ROUTINE SECTION FUNCTION
gss_get_mic 7.9 Calculate a cryptographic
Message Integrity Code (MIC)
for a message; integrity service
gss_verify_mic 7.22 Check a MIC against a message;
verify integrity of a received
message
gss_wrap 7.23 Attach a MIC to a message, and
optionally encrypt the message
content; confidentiality service
gss_unwrap 7.21 Verify a message with attached
MIC, and decrypt message
content if necessary.
Table 4-4 GSS-API Support Routines
ROUTINE SECTION FUNCTION
SUPPORT ROUTINES
gss_display_status 7.7 Convert a GSS-API status code
to text
gss_indicate_mechs 7.12 Determine available underlying
authentication mechanisms
gss_import_name 7.10 Convert a textual name to
internal-form
gss_display_name 7.6 Convert internal-form name
to text
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gss_compare_name 7.3 Compare two internal-form names
gss_release_name 7.19 Discard an internal-form name
gss_release_oid_set 7.20 Discard a set of object
identifiers
gss_release_buffer 7.17 Discard a buffer
gss_import_name_object 7.11 Create an internal-form name
from a mechanism-specific
name object
gss_export_name_object 7.8 Create a mechanism-specific
name object from an
internal-form name
Individual GSS-API implementations may augment these routines by
providing additional mechanism-specific routines if required
functionality is not available from the generic forms. Applications
are encouraged to use the generic routines wherever possible on
portability grounds.
5. DATA TYPES AND CALLING CONVENTIONS
The following conventions are used by the GSS-API C-language
bindings:
5.1. Integer types
GSS-API uses the following integer data type:
OM_uint32 32-bit unsigned integer
Where guaranteed minimum bit-count is important, this portable data
type is used by the GSS-API routine definitions. Individual GSS-API
implementations will include appropriate typedef definitions to map
this type onto a built-in data type. If the platform supports the
X/Open xom.h header file, the OM_uint32 definition contained therein
should be used; the GSS-API header file in Appendix A contains logic
that will detect the prior inclusion of xom.h, and will not attempt
to re-declare OM_uint32. If the X/Open header file is not available
on the platform, the GSS-API implementation should use the smallest
natural unsigned integer type that provides at least 32 bits of
precision.
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5.2. String and similar data
Many of the GSS-API routines take arguments and return values that
describe contiguous multiple-byte data. All such data is passed
between the GSS-API and the caller using the gss_buffer_t data type.
This data type is a pointer to a buffer descriptor, which consists of
a length field that contains the total number of bytes in the datum,
and a value field which contains a pointer to the actual datum:
typedef struct gss_buffer_desc_struct {
size_t length;
void *value;
} gss_buffer_desc, *gss_buffer_t;
Storage for data passed to the application by a GSS-API routine using
the gss_buffer_t conventions is allocated by the GSS-API routine.
The application may free this storage by invoking the
gss_release_buffer routine. Allocation of the gss_buffer_desc object
is always the responsibility of the application; unused
gss_buffer_desc objects may be initialized to the value
GSS_C_EMPTY_BUFFER.
5.2.1. Opaque data types
Certain multiple-word data items are considered opaque data types at
the GSS-API, because their internal structure has no significance
either to the GSS-API or to the caller. Examples of such opaque data
types are the input_token parameter to gss_init_sec_context (which is
opaque to the caller), and the input_message parameter to gss_wrap
(which is opaque to the GSS-API). Opaque data is passed between the
GSS-API and the application using the gss_buffer_t datatype.
5.2.2. Character strings
Certain multiple-word data items may be regarded as simple ISO
Latin-1 character strings. An example of this is the
input_name_buffer parameter to gss_import_name. Some GSS-API
routines also return character strings. Character strings are passed
between the application and the GSS-API using the gss_buffer_t
datatype.
The length field of a gss_buffer_desc object should only count valid
printable characters within the value. In particular, no trailing
NULL character should be included in the length count.
5.3. Object Identifiers
Certain GSS-API procedures take parameters of the type gss_OID, or
Object identifier. This is a type containing ISO-defined tree-
structured values, and is used by the GSS-API caller to select an
underlying security mechanism. A value of type gss_OID has the
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following structure:
typedef struct gss_OID_desc_struct {
OM_uint32 length;
void *elements;
} gss_OID_desc, *gss_OID;
The elements field of this structure points to the first byte of an
octet string containing the ASN.1 BER encoding of the value of the
gss_OID. The length field contains the number of bytes in this
value. For example, the gss_OID value corresponding to {iso(1)
identified-organization(3) icd-ecma(12) member-company(2) dec(1011)
cryptoAlgorithms(7) DASS(5)}, meaning the DASS X.509 authentication
mechanism, has a length field of 7 and an elements field pointing to
seven octets containing the following octal values:
53,14,2,207,163,7,5. GSS-API implementations should provide constant
gss_OID values to allow callers to request any supported mechanism,
although applications are encouraged on portability grounds to accept
the default mechanism. gss_OID values should also be provided to
allow applications to specify particular name types (see section
5.9). Applications should treat gss_OID_desc values returned by
GSS-API routines as read-only. In particular, the application should
not attempt to deallocate them. The gss_OID_desc datatype is
equivalent to the X/Open OM_object_identifier datatype[XOM].
5.4. Object Identifier Sets
Certain GSS-API procedures take parameters of the type gss_OID_set.
This type represents one or more object identifiers (section 5.3). A
gss_OID_set object has the following structure:
typedef struct gss_OID_set_desc_struct {
size_t count;
gss_OID elements;
} gss_OID_set_desc, *gss_OID_set;
The count field contains the number of OIDs within the set. The
elements field is a pointer to an array of gss_OID_desc objects, each
of which describes a single OID. gss_OID_set values are used to name
the available mechanisms supported by the GSS-API, to request the use
of specific mechanisms, and to indicate which mechanisms a given
credential supports. Storage associated with gss_OID_set values
returned to the application by the GSS-API may be deallocated by the
gss_release_oid_set routine.
5.5. Credentials
A credential handle is a caller-opaque atomic datum that identifies a
GSS-API credential data structure. It is represented by the caller-
opaque type gss_cred_id_t, which should be implemented as a pointer
or arithmetic type. If a pointer implementation is chosen, care must
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be taken to ensure that two gss_cred_id_t values may be compared with
the == operator.
Credentials describe a principal, and give their holder the ability
to act as that principal. The GSS-API does not make the actual
credentials available to applications; instead the credential handle
is used to identify a particular credential, held internally by GSS-
API or the underlying mechanism.
The gss_init_sec_context and gss_accept_sec_context routines allow
the value GSS_C_NO_CREDENTIAL to be specified as their credential
handle parameter. This special credential-handle indicates a desire
by the application to act as a default principal. While individual
GSSAPI implementations are free to determine such default behavior as
appropriate to the mechanism, the following default behavior by these
routines is recommended for portability:
(a) gss_init_sec_context
(i) If there is only a single principal capable of initiating
security contexts that the application is authorized to
act on behalf of, then that principal shall be used,
otherwise
(ii) If the platform maintains a concept of a default
network-identity, and if the application is authorized to
act on behalf of that identity for the purpose if
initiating security contects, then the principal
corresponding to that identity shall be used, otherwise
(iii) If the platform maintains a concept of a default local
identity, and provides a means to map local identities
into network-identities, and if the application is
authorized to act on behalf of the network-identity image
of the default local identity for the purpose of
initiating security contexts, then the principal
corresponding to that identity shall be used, otherwise
(iv) A user-configurable default identity should be used.
(b) gss_accept_sec_context
(i) If there is only a single authorized principal identity
capable of accepting security contexts, then that
principal shall be used, otherwise
(ii) If the mechanism can determine the identity of the target
principal by examining the context-establishment token,
and if the accepting application is authorized to act as
that principal for the purpose of accepting security
contexts, then that principal identity shall be used,
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otherwise
(iii) If the mechanism supports context acceptance by any
principal, and mutual authentication was not requested,
any principal that the application is authorized to
accept security contexts under may be used, otherwise
(iv) A user-configurable default identity shall be used.
The purpose of the above rules is to allow security contexts to be
established by both initiator and acceptor using the default behavior
wherever possible. Applications requesting default behavior are
likely to be more portable across mechanisms and platforms than ones
that use gss_acquire_cred to request a specific identity.
5.6. Contexts
The gss_ctx_id_t data type contains a caller-opaque atomic value that
identifies one end of a GSS-API security context. It should be
implemented as a pointer or arithmetic type. If a pointer type is
chosen, care should be taken to ensure that two gss_ctx_id_t values
may be compared with the == operator.
The security context holds state information about each end of a peer
communication, including cryptographic state information.
5.7. Authentication tokens
A token is a caller-opaque type that GSS-API uses to maintain
synchronization between the context data structures at each end of a
GSS-API security context. The token is a cryptographically protected
byte-string, generated by the underlying mechanism at one end of a
GSS-API security context for use by the peer mechanism at the other
end. Encapsulation (if required) and transfer of the token are the
responsibility of the peer applications. A token is passed between
the GSS-API and the application using the gss_buffer_t conventions.
5.8. Status values
One or more status codes are returned by each GSS-API routine. Two
distinct sorts of status codes are returned. These are termed GSS
status codes and Mechanism status codes.
5.8.1. GSS status codes
GSS-API routines return GSS status codes as their OM_uint32 function
value. These codes indicate errors that are independent of the
underlying mechanism(s) used to provide the security service. The
errors that can be indicated via a GSS status code are either generic
API routine errors (errors that are defined in the GSS-API
specification) or calling errors (errors that are specific to these
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language bindings).
A GSS status code can indicate a single fatal generic API error from
the routine and a single calling error. In addition, supplementary
status information may be indicated via the setting of bits in the
supplementary info field of a GSS status code.
These errors are encoded into the 32-bit GSS status code as follows:
MSB LSB
|------------------------------------------------------------|
| Calling Error | Routine Error | Supplementary Info |
|------------------------------------------------------------|
Bit 31 24 23 16 15 0
Hence if a GSS-API routine returns a GSS status code whose upper 16
bits contain a non-zero value, the call failed. If the calling error
field is non-zero, the invoking application's call of the routine was
erroneous. Calling errors are defined in table 5-1. If the routine
error field is non-zero, the routine failed for one of the routine-
specific reasons listed below in table 5-2. Whether or not the upper
16 bits indicate a failure or a success, the routine may indicate
additional information by setting bits in the supplementary info
field of the status code. The meaning of individual bits is listed
below in table 5-3.
Table 5-1 Calling Errors
Name Value in Meaning
Field
GSS_S_CALL_INACCESSIBLE_READ 1 A required input
parameter could
not be read.
GSS_S_CALL_INACCESSIBLE_WRITE 2 A required output
parameter could
not be written.
GSS_S_CALL_BAD_STRUCTURE 3 A parameter was
malformed
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Table 5-2 Routine Errors
Name Value in Meaning
Field
GSS_S_BAD_MECH 1 An unsupported mechanism was
requested
GSS_S_BAD_NAME 2 An invalid name was supplied
GSS_S_BAD_NAMETYPE 3 A supplied name was of an
unsupported type
GSS_S_BAD_BINDINGS 4 Incorrect channel bindings
were supplied
GSS_S_BAD_STATUS 5 An invalid status code was
supplied
GSS_S_BAD_SIG 6 A token had an invalid
signature or MIC
GSS_S_NO_CRED 7 No credentials were supplied
GSS_S_NO_CONTEXT 8 No context has been
established
GSS_S_DEFECTIVE_TOKEN 9 A token was invalid
GSS_S_DEFECTIVE_CREDENTIAL 10 A credential was invalid
GSS_S_CREDENTIALS_EXPIRED 11 The referenced credentials
have expired
GSS_S_CONTEXT_EXPIRED 12 The context has expired
GSS_S_FAILURE 13 Miscellaneous failure
(see text)
GSS_S_BAD_QOP 14 The quality-of-protection
requested could not be
provide
Table 5-3 Supplementary Status Bits
Name Bit Number Meaning
GSS_S_CONTINUE_NEEDED 0 (LSB) The routine must be called
again to complete its function.
See routine documentation for
detailed description.
GSS_S_DUPLICATE_TOKEN 1 The token was a duplicate of
an earlier token
GSS_S_OLD_TOKEN 2 The token's validity period
has expired
GSS_S_UNSEQ_TOKEN 3 A later token has already been
processed
GSS_S_GAP_TOKEN 4 An expected per-message token
was not received
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The routine documentation also uses the name GSS_S_COMPLETE, which is
a zero value, to indicate an absence of any API errors or
supplementary information bits.
All GSS_S_xxx symbols equate to complete OM_uint32 status codes,
rather than to bitfield values. For example, the actual value of the
symbol GSS_S_BAD_NAMETYPE (value 3 in the routine error field) is
3 << 16.
The macros GSS_CALLING_ERROR(), GSS_ROUTINE_ERROR() and
GSS_SUPPLEMENTARY_INFO() are provided, each of which takes a GSS
status code and removes all but the relevant field. For example, the
value obtained by applying GSS_ROUTINE_ERROR to a status code removes
the calling errors and supplementary info fields, leaving only the
routine errors field. The values delivered by these macros may be
directly compared with a GSS_S_xxx symbol of the appropriate type.
The macro GSS_ERROR() is also provided, which when applied to a GSS
status code returns a non-zero value if the status code indicated a
calling or routine error, and a zero value otherwise. All macros
defined by GSS-API evaluate their argument(s) exactly once.
A GSS-API implementation may choose to signal calling errors in a
platform-specific manner instead of, or in addition to the routine
value; routine errors and supplementary info should be returned via
routine status values only.
5.8.2. Mechanism-specific status codes
GSS-API routines return a minor_status parameter, which is used to
indicate specialized errors from the underlying security mechanism.
This parameter may contain a single mechanism-specific error,
indicated by a OM_uint32 value.
The minor_status parameter will always be set by a GSS-API routine,
even if it returns a calling error or one of the generic API errors
indicated above as fatal, although most other output parameters may
remain unset in such cases. However, output parameters that are
expected to return pointers to storage allocated by a routine must
always set set by the routine, even in the event of an error,
although in such cases the GSS-API routine may elect to set the
returned parameter value to NULL to indicate that no storage was
actually allocated. Any length field associated with such pointers
(as in a gss_buffer_desc structure) should also be set to zero in
such cases.
The GSS status code GSS_S_FAILURE is used to indicate that the
underlying mechanism detected an error for which no specific GSS
status code is defined. The mechanism status code will provide more
details about the error.
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5.9. Names
A name is used to identify a person or entity. GSS-API authenticates
the relationship between a name and the entity claiming the name.
Three distinct representations are defined for names:
(a) A printable form, for presentation to a user
(b) An internal form, for presentation at the API
(c) Optional mechanism-specific forms.
The syntax of a printable name is defined by the GSS-API
implementation, and may be dependent on local system configuration,
or on individual user preference. The internal form provides a
canonical representation of the name that is independent of
configuration. The mechanism-specific forms are provided to simplify
porting of existing mechanism-specific applications to the GSS-API.
Any application that uses mechanism-specific name-forms is inherently
non-portable to other mechanisms, and may not be portable to other
implementations of the same mechanism.
A given GSS-API implementation may support names drawn from multiple
namespaces. In such an implementation, the internal form of the name
must include fields that identify the namespace from which the name
is drawn. The namespace from which a printable name is drawn is
specified by an accompanying object identifier.
Routines (gss_import_name and gss_display_name) are provided to
convert names between their printable representations and the
internal gss_name_t type. gss_import_name may support multiple
syntaxes for each supported namespace, allowing users the freedom to
choose a preferred name representation. gss_display_name should use
an implementation-chosen preferred syntax for each supported name-
type.
Comparison of internal-form names is accomplished via the
gss_compare_names routine. This removes the need for the application
program to understand the syntaxes of the various printable names
that a given GSS-API implementation may support.
The gss_name_t datatype should be implemented as a pointer type. To
allow the compiler to aid the application programmer by performing
type-checking, the use of (void *) is discouraged. A pointer to an
implementation-defined type is the preferred choice.
Storage is allocated by routines that return gss_name_t values. A
procedure, gss_release_name, is provided to free storage associated
with a name.
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5.10. Channel Bindings
GSS-API supports the use of user-specified tags to identify a given
context to the peer application. These tags are used to identify the
particular communications channel that carries the context. Channel
bindings are communicated to the GSS-API using the following
structure:
typedef struct gss_channel_bindings_struct {
OM_uint32 initiator_addrtype;
gss_buffer_desc initiator_address;
OM_uint32 acceptor_addrtype;
gss_buffer_desc acceptor_address;
gss_buffer_desc application_data;
} *gss_channel_bindings_t;
The initiator_addrtype and acceptor_addrtype fields denote the type
of addresses contained in the initiator_address and acceptor_address
buffers. The address type should be one of the following:
GSS_C_AF_UNSPEC Unspecified address type
GSS_C_AF_LOCAL Host-local address type
GSS_C_AF_INET DARPA Internet address type
GSS_C_AF_IMPLINK ARPAnet IMP address type (eg IP)
GSS_C_AF_PUP pup protocols (eg BSP) address type
GSS_C_AF_CHAOS MIT CHAOS protocol address type
GSS_C_AF_NS XEROX NS address type
GSS_C_AF_NBS nbs address type
GSS_C_AF_ECMA ECMA address type
GSS_C_AF_DATAKIT datakit protocols address type
GSS_C_AF_CCITT CCITT protocols (eg X.25)
GSS_C_AF_SNA IBM SNA address type
GSS_C_AF_DECnet DECnet address type
GSS_C_AF_DLI Direct data link interface address type
GSS_C_AF_LAT LAT address type
GSS_C_AF_HYLINK NSC Hyperchannel address type
GSS_C_AF_APPLETALK AppleTalk address type
GSS_C_AF_BSC BISYNC 2780/3780 address type
GSS_C_AF_DSS Distributed system services address type
GSS_C_AF_OSI OSI TP4 address type
GSS_C_AF_X25 X25
GSS_C_AF_NULLADDR No address specified
Note that these symbols name address families rather than specific
addressing formats. For address families that contain several
alternative address forms, the initiator_address and acceptor_address
fields must contain sufficient information to determine which address
form is used. When not otherwise specified, addresses should be
specified in network byte-order.
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Conceptually, the GSS-API concatenates the initiator_addrtype,
initiator_address, acceptor_addrtype, acceptor_address and
application_data to form an octet string. The mechanism signs this
octet string, and binds the signature to the context establishment
token emitted by gss_init_sec_context. The same bindings are
presented by the context acceptor to gss_accept_sec_context, and a
signature is calculated in the same way. The calculated signature is
compared with that found in the token, and if the signatures differ,
gss_accept_sec_context will return a GSS_S_BAD_BINDINGS error, and
the context will not be established. Some mechanisms may include the
actual channel binding data in the token (rather than just a
signature); applications should therefore not use confidential data
as channel-binding components. Individual mechanisms may impose
additional constraints on addresses and address types that may appear
in channel bindings. For example, a mechanism may verify that the
initiator_address field of the channel bindings presented to
gss_init_sec_context contains the correct network address of the host
system. Therefore, portable applications should ensure that they
provide either correct information for the address fields, or should
omit addressing information, and specify GSS_C_AF_NULLADDR as the
address-types.
5.11. Optional parameters
Various parameters are described as optional. This means that they
follow a convention whereby a default value may be requested. The
following conventions are used for omitted parameters. These
conventions apply only to those parameters that are explicitly
documented as optional.
5.11.1. gss_buffer_t types
Specify GSS_C_NO_BUFFER as a value. For an input parameter this
signifies that default behavior is requested, while for an output
parameter it indicates that the information that would be returned
via the parameter is not required by the application.
5.11.2. Integer types (input)
Individual parameter documentation lists values to be used to
indicate default actions.
5.11.3. Integer types (output)
Specify NULL as the value for the pointer.
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5.11.4. Pointer types
Specify NULL as the value.
5.11.5. Object IDs
Specify GSS_C_NO_OID as the value.
5.11.6. Object ID Sets
Specify GSS_C_NO_OID_SET as the value.
5.11.7. Channel Bindings
Specify GSS_C_NO_CHANNEL_BINDINGS to indicate that channel bindings
are not to be used.
6. ADDITIONAL CONTROLS
This section discusses the optional services that a context initiator
may request of the GSS-API at context establishment. All these
services are requested by setting flags in the req_flags input
parameter to gss_init_sec_context.
The optional services currently defined are:
Delegation - The (usually temporary) transfer of rights from initiator
to acceptor, enabling the acceptor to authenticate itself as an
agent of the initiator.
Mutual Authentication - In addition to the initiator authenticating its
identity to the context acceptor, the context acceptor should
also authenticate itself to the initiator.
Replay detection - In addition to providing message integrity services,
gss_get_mic and gss_wrap should include message numbering
information to enable gss_verify_mic and gss_unwrap to detect
if a message has been duplicated.
Out-of-sequence detection - In addition to providing message integrity
services, gss_get_mic and gss_wrap should include message
sequencing information to enable gss_verify_mic and gss_unwrap
to detect if a message has been received out of sequence.
Anonymous authentication - The establishment of the security context
should not reveal the initiator's identity to the context
acceptor.
Any currently undefined bits within such flag arguments should be
ignored by GSS-API implementations when presented by an application,
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and should be set to zero when returned to the application by the
GSS-API implementation.
Some mechanisms may not support all optional services, and some
mechanisms may only support some services in conjunction with others.
Both gss_init_sec_context and gss_accept_sec_context inform the
applications which services will be available from the context when
the establishment phase is complete, via the ret_flags output
parameter. In general, if the security mechanism is capable of
providing a requested service, it should do so, even if additional
services must be enabled in order to provide the requested service.
If the mechanism is incapable of providing a requested service, it
should proceed without the service, leaving the application to abort
the context establishment process if it considers the requested
service to be mandatory.
6.1. Delegation
The GSS-API allows delegation to be controlled by the initiating
application via a boolean parameter to gss_init_sec_context(), the
routine that establishes a security context. Some mechanisms do not
support delegation, and for such mechanisms attempts by an
application to enable delegation are ignored.
For many mechanisms that support delegation, a simple boolean does
not provide enough control. Examples of additional aspects of
delegation control that a mechanism might provide to an application
are duration of delegation, network addresses from which delegation
is valid, and constraints on the tasks performed by a delegate. Such
controls are presently outside the scope of the GSS-API. GSS-API
implementations supporting mechanisms offering additional controls
should provide extension routines that allow these controls to be
exercised (perhaps by modifying the initiator's GSS-API credential
prior to its use in establishing a context). However, the simple
delegation control provided by GSS-API should always be able to
over-ride other mechanism-specific delegation controls - If the
application instructs gss_init_sec_context() that delegation is not
desired, then the implementation must not permit delegation to occur.
This is an exception to the general rule that a mechanism may enable
services even if they are not requested - delegation may only be
provide at the explicit request of the application.
6.2. Mutual authentication
Usually, a context acceptor will require that a context initiator
authenticate itself so that the acceptor may make an access-control
decision prior to performing a service for the initator. In some
cases, the initiator may also request that the acceptor authenticate
itself. GSS-API allows the initiating application to request this
mutual authentication service by setting a flag when calling
gss_init_sec_context.
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The initiating application is informed as to whether or not mutual
authentication is being requested of the context acceptor. Note that
some mechanisms may not support mutual authentication, and other
mechanisms may always perform mutual authentication, whether or not
the initiating application requests it. In particular, mutual
authentication my be required by some mechanisms in order to support
replay or out-of-sequence message detection, and for such mechanisms
a request for either of these services will automatically enable
mutual authentication.
6.3. Replay and out-of-sequence detection
The GSS-API may provide detection of mis-ordered message once a
security context has been established. Protection may be applied to
messages by either application, by calling either gss_get_mic or
gss_wrap, and verified by the peer application by calling
gss_verify_mic or gss_unwrap.
gss_get_mic calculates a cryptographic checksum of an application
message, and returns that checksum in a token. The application
should pass both the token and the message to the peer application,
which presents them to gss_verify_mic.
gss_wrap calculates a cryptographic checksum of an application
message, and places both the checksum and the message in a token.
The application should pass the token to the peer application, which
presents it to gss_unwrap to extract the message.
Either pair of routines may be capable of detecting out-of-sequence
message delivery, or duplication of messages. Details of such mis-
ordered messages are indicated through supplementary status bits in
the major status code returned by gss_verify_mic or gss_unwrap. The
relevant supplementary bits are:
GSS_S_DUPLICATE_TOKEN - The token is a duplicate of one that has already
been received and processed. Contexts that do not claim to
provide replay detection may still set this bit if the
duplicate message is processed immediately after the original,
with no intervening messages.
GSS_S_OLD_TOKEN - The token is too old to determine whether or not it is
a duplicate. Contexts supporting out-of-sequence detection but
not replay detection should always set this bit if
GSS_S_UNSEQ_TOKEN is set; contexts that support replay
detection should only set this bit if the token is so old that
it cannot be checked for duplication.
GSS_S_UNSEQ_TOKEN - A later token has already been processed.
GSS_S_GAP_TOKEN - An earlier token has not yet been received.
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A mechanism need not maintain a list of all tokens that have been
processed in order to support these status codes. A typical
mechanism might retain information about only the most recent "N"
tokens processed, allowing it to distinguish duplicates and missing
tokens within the most recent "N" messages; the receipt of a token
older than the most recent "N" would result in a GSS_S_OLD_TOKEN
status.
6.4. Anonymous Authentication
In certain situations, an application may wish to initiate the
authentication process to authenticate a peer, without revealing its
own identity. For example, consider an application providing access
to a database containing medical information, and offering
unrestricted access to the service. A client of such a service might
wish to authenticate the service (in order to establish trust in any
information retrieved from it), but might not wish the service to be
able to obtain the client's identity (perhaps due to privacy concerns
about the specific inquiries, or perhaps simply to avoid being placed
on mailing-lists).
In normal use of the GSS-API, the initiator's identity is made
available to the acceptor as a result of the context establishment
process. However, context initiators may request that their identity
not be revealed to the context acceptor. Many mechanisms do not
support anonymous authentication, and for such mechanisms the request
will be refused. However, the application is always informed if a
requested service is unavailable, and has the option to abort context
establishment if anonymity is valued above the other security
services that would require a context to be established.
In addition to informing the application that a context is estalished
anonymously (via the ret_flags outputs from gss_init_sec_context and
gss_accept_sec_context), the optional src_name output from
gss_accept_sec_context and gss_inquire_context will, for such
contexts, return a reserved internal-form name, defined by the
implementation. When presented to gss_display_name, this reserved
internal-form name will result in a printable name that is
syntactically distinguishable from any valid principal name supported
by the implementation, associated with a name-type object identifier
with the value GSS_C_NAMETYPE_ANONYMOUS. This gss_OID value should
refer to a gss_OID_desc object containing the value {4, (void *)"}.
The printable form of an anonymous name should be chosen such that it
implies anonymity, since this name may appear in, for example, audit
logs. For example, the string "<anonymous>" might be a good choice,
if no valid printable names supported by the implementation can begin
with "<" and end with ">".
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6.5. Confidentiality
If a context supports the confidentiality service, gss_wrap may be
used to encrypt application messages. Messages are selectively
encrypted, under the control of the conf_req_flag input parameter to
gss_wrap.
Some mechanisms may specify that the confidentiality service is
optional, and that implementors of the mechanism need not provide it,
often because of legal restrictions on confidentiality protection.
For such mechanisms, it it possible that while the context
initiator's GSS-API implementation supports confidentiality, the
context acceptor's implementation may not. In this case, the status
return from gss_init_sec_context may indicate that the
confidentiality service is available, whereas in fact it is not,
since the acceptor will be unable to apply confidentility protection
to messages, or to process confidentiality-protected messages.
If context establishment requires the transmission of a token from
acceptor to initiator, the mechanism is encouraged to use this token
to indicate to the initiating GSS-API whether the acceptor supports
confidentiality, so that correct service information may be delivered
to the initiating application. For such a mechanism, the ret_flags
returned from the initial invocation of gss_init_sec_context should
indicate that confidentiality protection is available if the
initiating GSS-API implementation supports it, but the ret_flags
returned from the final invocation should indicate that the service
is unavailable if the acceptor does not provide confidentiality
support.
7. GSS-API routine descriptions
In addition to the explicit major status codes documented here, the
code GSS_S_FAILURE may be returned by any routine, indicating an
implementation-specific or mechanism-specific error condition,
further details of which are reported via the minor_status parameter.
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7.1. gss_accept_sec_context
OM_uint32 gss_accept_sec_context (
OM_uint32 * minor_status,
gss_ctx_id_t * context_handle,
gss_cred_id_t verifier_cred_handle,
gss_buffer_t input_token_buffer
gss_channel_bindings_t
input_chan_bindings,
gss_name_t * src_name,
gss_OID * mech_type,
gss_buffer_t output_token,
OM_uint32 * ret_flags,
OM_uint32 * time_rec,
gss_cred_id_t * delegated_cred_handle)
Purpose:
Allows a remotely initiated security context between the application
and a remote peer to be established. The routine may return a
output_token which should be transferred to the peer application,
where the peer application will present it to gss_init_sec_context.
If no token need be sent, gss_accept_sec_context will indicate this
by setting the length field of the output_token argument to zero. To
complete the context establishment, one or more reply tokens may be
required from the peer application; if so, gss_accept_sec_context
will return a status flag of GSS_S_CONTINUE_NEEDED, in which case it
should be called again when the reply token is received from the peer
application, passing the token to gss_accept_sec_context via the
input_token parameters.
The values returned via the src_name, time_rec, mech_type and
delegated_cred_handle parameters are not defined unless the routine
returns GSS_S_COMPLETE.
While the routine returns GSS_S_CONTINUE_NEEDED, the values returned
via the ret_flags argument indicate the services that the
implementation expects to be available from the established context.
Parameters:
context_handle gss_ctx_id_t, read/modify
context handle for new context. Supply
GSS_C_NO_CONTEXT for first call; use value
returned in subsequent calls.
verifier_cred_handle gss_cred_id_t, read
Credential handle claimed by context acceptor.
Specify GSS_C_NO_CREDENTIAL to accept the
context as a default principal. If
GSS_C_NO_CREDENTIAL is specified, but no
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default acceptor principal is defined,
GSS_S_NO_CRED will be returned.
input_token_buffer buffer, opaque, read
token obtained from remote application
input_chan_bindings channel bindings, read, optional
Application-specified bindings. Allows
application to securely bind channel
identification information to the security
context. If channel bindings are not
used, specify GSS_C_NO_CHANNEL_BINDINGS.
src_name gss_name_t, modify, optional
Authenticated name of context initiator.
After use, this name should be deallocated by
passing it to gss_release_name. If not required,
specify NULL.
mech_type Object ID, modify, optional
Security mechanism used. The returned
OID value will be a pointer into static
storage, and should be treated as read-only
by the caller. If not required, specify
NULL.
output_token buffer, opaque, modify
Token to be passed to peer application. If the
length field of the returned token buffer is 0,
then no token need be passed to the peer
application.
ret_flags bit-mask, modify, optional
Contains various independent flags, each of
which indicates that the context supports a
specific service option. If not needed,
specify NULL. Symbolic names are
provided for each flag, and the symbolic names
corresponding to the required flags
should be logically-ANDed with the ret_flags
value to test whether a given option is
supported by the context. The flags are:
GSS_C_DELEG_FLAG
True - Delegated credentials are available
via the delegated_cred_handle
parameter
False - No credentials were delegated
GSS_C_MUTUAL_FLAG
True - Remote peer asked for mutual
authentication
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False - Remote peer did not ask for mutual
authentication
GSS_C_REPLAY_FLAG
True - replay of protected messages
will be detected
False - replayed messages will not be
detected
GSS_C_SEQUENCE_FLAG
True - out-of-sequence protected
messages will be detected
False - out-of-sequence messages will not
be detected
GSS_C_CONF_FLAG
True - Confidentiality service may be invoked
by calling the gss_wrap routine
False - No confidentiality service (via
gss_wrap) available. gss_wrap will
provide message encapsulation,
data-origin authentication and
integrity services only.
GSS_C_INTEG_FLAG
True - Integrity service may be invoked by
calling either gss_get_mic or gss_wrap
routines.
False - Per-message integrity service
unavailable.
GSS_C_ANON_FLAG
True - The initiator does not wish to
be authenticated; the src_name
parameter (if requested) contains
an anonymous internal name.
False - The initiator has been
authenticated normally.
time_rec integer, modify, optional
number of seconds for which the context
will remain valid. Specify NULL if not required.
delegated_cred_handle
gss_cred_id_t, modify, optional
credential handle for credentials received from
context initiator. Only valid if deleg_flag in
ret_flags is true. If not needed, specify NULL.
minor_status integer, modify
Mechanism specific status code.
Function value:
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GSS status code:
GSS_S_COMPLETE Successful completion
GSS_S_CONTINUE_NEEDED Indicates that a token from the peer
application is required to complete the context,
and that gss_accept_sec_context must be called
again with that token.
GSS_S_DEFECTIVE_TOKEN Indicates that consistency checks performed on
the input_token failed.
GSS_S_DEFECTIVE_CREDENTIAL Indicates that consistency checks
performed on the credential failed.
GSS_S_NO_CRED The supplied credentials were not valid for context
acceptance, or the credential handle did not
reference any credentials.
GSS_S_CREDENTIALS_EXPIRED The referenced credentials have expired.
GSS_S_BAD_BINDINGS The input_token contains different channel
bindings to those specified via the
input_chan_bindings parameter.
GSS_S_NO_CONTEXT Indicates that the supplied context handle did not
refer to a valid context.
GSS_S_BAD_SIG The input_token contains an invalid signature.
GSS_S_OLD_TOKEN The input_token was too old. This is a fatal error
during context establishment.
GSS_S_DUPLICATE_TOKEN The input_token is valid, but is a duplicate of
a token already processed. This is a fatal error
during context establishment.
GSS_S_BAD_MECH The received token specified a mechanism that is
not supported by the implementation or the provided
credential.
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7.2. gss_acquire_cred
OM_uint32 gss_acquire_cred (
OM_uint32 * minor_status,
gss_name_t desired_name,
OM_uint32 time_req,
gss_OID_set desired_mechs,
gss_cred_usage_t cred_usage,
gss_cred_id_t * output_cred_handle,
gss_OID_set * actual_mechs,
OM_int32 * time_rec)
Purpose:
Allows an application to acquire a handle for a pre-existing
credential by name. GSS-API implementations must impose a local
access-control policy on callers of this routine to prevent
unauthorized callers from acquiring credentials to which they are not
entitled. This routine is not intended to provide a ``login to the
network'' function, as such a function would involve the creation of
new credentials rather than merely acquiring a handle to existing
credentials. Such functions, if required, should be defined in
implementation-specific extensions to the API.
This routine is expected to be used primarily by context acceptors,
since implementations are likely to provide mechanism-specific ways
of obtaining GSS-API initiator credentials from the system login
process. Some implementations may therefore not support the
acquisition of GSS_C_INITIATE or GSS_C_BOTH credentials via
gss_acquire_cred.
If credential acquisition is time-consuming for a mechanism, the
mechanism may chooses to delay the actual acquisition until the
credential is required (e.g. by gss_init_sec_context or
gss_accept_sec_context). Such mechanism-specific implementation
decisions should be invisible to the calling application; thus a call
of gss_inquire_cred immediately following the call of
gss_acquire_cred must return valid credential data, and may therefore
incur the overhead of a deferred credential acquisition.
Parameters:
desired_name gss_name_t, read
Name of principal whose credential
should be acquired
time_req integer, read
number of seconds that credentials
should remain valid
desired_mechs Set of Object IDs, read
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set of underlying security mechanisms that
may be used. GSS_C_NO_OID_SET may be used
to obtain an implementation-specific default.
cred_usage gss_cred_usage_t, read
GSS_C_BOTH - Credentials may be used
either to initiate or accept
security contexts.
GSS_C_INITIATE - Credentials will only be
used to initiate security
contexts.
GSS_C_ACCEPT - Credentials will only be used to
accept security contexts.
output_cred_handle gss_cred_id_t, modify
The returned credential handle.
actual_mechs Set of Object IDs, modify, optional
The set of mechanisms for which the
credential is valid. Specify NULL
if not required.
time_rec Integer, modify, optional
Actual number of seconds for which the
returned credentials will remain valid. If the
implementation does not support expiration of
credentials, the value GSS_C_INDEFINITE will
be returned. Specify NULL if not required
minor_status Integer, modify
Mechanism specific status code.
Function value:
GSS status code:
GSS_S_COMPLETE Successful completion
GSS_S_BAD_MECH Unavailable mechanism requested
GSS_S_BAD_NAMETYPE Type contained within desired_name parameter is
not supported
GSS_S_BAD_NAME Value supplied for desired_name parameter is ill-
formed.
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7.3. gss_compare_name
OM_uint32 gss_compare_name (
OM_uint32 * minor_status,
gss_name_t name1,
gss_name_t name2,
int * name_equal)
Purpose:
Allows an application to compare two internal-form names to determine
whether they refer to the same entity.
If either name presented to gss_compare_name denotes an anonymous
principal, the routines should indicate that the two names do not
refer to the same identity.
Parameters:
minor_status integer, modify
Mechanism specific status code.
name1 gss_name_t, read
internal-form name
name2 gss_name_t, read
internal-form name
name_equal boolean, modify
True - names refer to same entity
False - names refer to different entities
(strictly, the names are not known to
refer to the same identity).
Function value:
GSS status code:
GSS_S_COMPLETE Successful completion
GSS_S_BAD_NAMETYPE The type contained within either name1 or name2
was unrecognized, or the names were of incomparable
types.
GSS_S_BAD_NAME One or both of name1 or name2 was ill-formed
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7.4. gss_context_time
OM_uint32 gss_context_time (
OM_uint32 * minor_status,
gss_ctx_id_t context_handle,
OM_uint32 * time_rec)
Purpose:
Determines the number of seconds for which the specified context will
remain valid.
Parameters:
minor_status integer, modify
Implementation specific status code.
context_handle gss_ctx_id_t, read
Identifies the context to be interrogated.
time_rec integer, modify
Number of seconds that the context will remain
valid. If the context has already expired,
zero will be returned.
Function value:
GSS status code:
GSS_S_COMPLETE Successful completion
GSS_S_CONTEXT_EXPIRED The context has already expired
GSS_S_CREDENTIALS_EXPIRED The context is recognized, but associated
credentials have expired
GSS_S_NO_CONTEXT The context_handle parameter did not identify a
valid context
7.5. gss_delete_sec_context
OM_uint32 gss_delete_sec_context (
OM_uint32 * minor_status,
gss_ctx_id_t * context_handle,
gss_buffer_t output_token)
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Purpose:
Delete a security context. gss_delete_sec_context will delete the
local data structures associated with the specified security context,
and may generate an output_token, which when passed to the peer
gss_process_context_token will instruct it to do likewise. If no
token is required by the mechanism, the GSS-API should set the length
field of the output_token (if provided) to zero. No further security
services may be obtained using the context specified by
context_handle.
The output_token parameter is retained for compatibility with version
1 of the GSS-API. It is recommended that both peer applications
invoke gss_delete_sec_context passing the value GSS_C_NO_BUFFER for
the output_token parameter, indicating that no token is required, and
that gss_delete_sec_context should simply delete local context data
structures.
Parameters:
minor_status integer, modify
Mechanism specific status code.
context_handle gss_ctx_id_t, modify
context handle identifying context to delete.
output_token buffer, opaque, modify, optional
token to be sent to remote application to
instruct it to also delete the context. It
is recommended that applications specify
GSS_C_NO_BUFFER for this parameter, requesting
local deletion only.
Function value:
GSS status code:
GSS_S_COMPLETE Successful completion
GSS_S_NO_CONTEXT No valid context was supplied
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7.6. gss_display_name
OM_uint32 gss_display_name (
OM_uint32 * minor_status,
gss_name_t input_name,
gss_buffer_t output_name_buffer,
gss_OID * output_name_type)
Purpose:
Allows an application to obtain a textual representation of an opaque
internal-form name for display purposes. The syntax of a printable
name is defined by the GSS-API implementation.
If input_name denotes an anonymous principal, the implementation
should return the gss_OID value GSS_C_NAMETYPE_ANONYMOUS as the
output_name_type, and a textual name that is syntactically distinct
from all valid supported printable names in output_name_buffer.
Parameters:
minor_status integer, modify
Mechanism specific status code.
input_name gss_name_t, read
name to be displayed
output_name_buffer buffer, character-string, modify
buffer to receive textual name string
output_name_type Object ID, modify, optional
The type of the returned name. The returned
gss_OID will be a pointer into static storage,
and should be treated as read-only by the caller.
Specify NULL if not required.
Function value:
GSS status code:
GSS_S_COMPLETE Successful completion
GSS_S_BAD_NAMETYPE The type of input_name was not recognized
GSS_S_BAD_NAME input_name was ill-formed
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7.7. gss_display_status
OM_uint32 gss_display_status (
OM_uint32 * minor_status,
OM_uint32 status_value,
int status_type,
gss_OID mech_type,
OM_uint32 * message_context,
gss_buffer_t status_string)
Purpose:
Allows an application to obtain a textual representation of a GSS-API
status code, for display to the user or for logging purposes. Since
some status values may indicate multiple errors, applications may
need to call gss_display_status multiple times, each call generating
a single text string. The message_context parameter is used to
indicate which error message should be extracted from a given
status_value; message_context should be initialized to 0, and
gss_display_status will return a non-zero value if there are further
messages to extract.
Parameters:
minor_status integer, modify
Mechanism specific status code.
status_value integer, read
Status value to be converted
status_type integer, read
GSS_C_GSS_CODE - status_value is a GSS status
code
GSS_C_MECH_CODE - status_value is a mechanism
status code
mech_type Object ID, read, optional
Underlying mechanism (used to interpret a
minor status value) Supply GSS_C_NO_OID to
obtain the system default.
message_context integer, read/modify
Should be initialized to zero by caller
on first call. If further messages are
contained in the status_value parameter,
message_context will be non-zero on return,
and this value should be passed back to
subsequent calls, along with the same
status_value, status_type and mech_type
parameters.
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status_string buffer, character string, modify
textual interpretation of the status_value
Function value:
GSS status code:
GSS_S_COMPLETE Successful completion
GSS_S_BAD_MECH Indicates that translation in accordance with an
unsupported mechanism type was requested
GSS_S_BAD_STATUS The status value was not recognized, or the status
type was neither GSS_C_GSS_CODE nor
GSS_C_MECH_CODE.
7.8. gss_export_name_object
OM_uint32 gss_export_name_object (
OM_uint32 * minor_status,
gss_name_t input_name,
gss_OID desired_name_type,
void ** output_name)
Purpose:
Provided to simplify the porting of a mechanism-specific application
to the GSS-API. Allows a GSS-API internal name to be converted into
a mechanism-specific name object.
Applications invoking the gss_export_name_object routine are unlikely
to be portable to other mechanisms, and may not be portable to other
implementations of the same mechanism.
Parameters:
minor_status integer, modify
Mechanism specific status code
input_name gss_name_t, read
The GSS-API internal name to be converted
desired_name_type OID, read
The name-type corresponding to the desired
type of name object. The mechanism must
define an OID to identify its internal
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name objects.
output_name Pointer to any, modify
The mechanism-specific name object
corresponding to the provided input_name.
Function value:
GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_BAD_NAMETYPE The speicified nametype is unrecognized or
unsupported
GSS_S_BAD_NAME The provided name was either not a valid GSS-API
internal name, or it could not be converted to a
mechanism-specific name of the desired type.
7.9. gss_get_mic
OM_uint32 gss_get_mic (
OM_uint32 * minor_status,
gss_ctx_id_t context_handle,
gss_qop_t qop_req,
gss_buffer_t message_buffer,
gss_buffer_t msg_token)
Purpose:
Generates a cryptographic signature for the supplied message, and
places the signature in a token for transfer to the peer application.
The qop_req parameter allows a choice between several cryptographic
algorithms, if supported by the chosen mechanism.
Parameters:
minor_status integer, modify
Implementation specific status code.
context_handle gss_ctx_id_t, read
identifies the context on which the message
will be sent
qop_req gss_qop_t, read, optional
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Specifies requested quality of protection.
Callers are encouraged, on portability grounds,
to accept the default quality of protection
offered by the chosen mechanism, which may be
requested by specifying GSS_C_QOP_DEFAULT for
this parameter. If an unsupported protection
strength is requested, gss_get_mic will return a
major_status of GSS_S_BAD_QOP.
message_buffer buffer, opaque, read
message to be protected
msg_token buffer, opaque, modify
buffer to receive token
Function value:
GSS status code:
GSS_S_COMPLETE Successful completion
GSS_S_CONTEXT_EXPIRED The context has already expired
GSS_S_CREDENTIALS_EXPIRED The context is recognized, but associated
credentials have expired
GSS_S_NO_CONTEXT The context_handle parameter did not identify a
valid context
GSS_S_BAD_QOP The specified QOP is not supported by the
mechanism.
7.10. gss_import_name
OM_uint32 gss_import_name (
OM_uint32 * minor_status,
gss_buffer_t input_name_buffer,
gss_OID input_name_type,
gss_name_t * output_name)
Purpose:
Convert a printable name to internal form.
Parameters:
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minor_status integer, modify
Mechanism specific status code
input_name_buffer buffer, character-string, read
buffer containing printable name to convert
input_name_type Object ID, read, optional
Object Id specifying type of printable
name. Applications may specify either
GSS_C_NO_OID to use a local system-specific
printable syntax, or an OID registered by the
GSS-API implementation to name a particular
namespace.
output_name gss_name_t, modify
returned name in internal form
Function value:
GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_BAD_NAMETYPE The input_name_type was unrecognized
GSS_S_BAD_NAME The input_name parameter could not be interpreted
as a name of the specified type
7.11. gss_import_name_object
OM_uint32 gss_import_name_object (
OM_uint32 * minor_status,
void * input_name,
gss_OID input_name_type,
gss_name_t * output_name)
Purpose:
Provided to simplify the porting of a mechanism-specific application
to the GSS-API. Allows a mechanism-specific name object to be
converted into a GSS-API internal name.
Applications invoking the gss_import_name_object routine are unlikely
to be portable to other mechanisms, and may not be portable to other
implementations of the same mechanism.
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Parameters:
minor_status integer, modify
Mechanism specific status code
input_name Pointer to any, read
The mechanism-specific name object to
be imported
input_name_type OID, read
The name-type of the name object. The
mechanism must define an OID to identify
its internal name objects.
output_name gss_name_t, modify
The GSS-API internal name-form
corresponding to the provided input_name.
Function value:
GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_BAD_NAMETYPE The speicified nametype is unrecognized or
unsupported
GSS_S_BAD_NAME The provided name was not a valid object of the
stated name-type.
7.12. gss_indicate_mechs
OM_uint32 gss_indicate_mechs (
OM_uint32 * minor_status,
gss_OID_set * mech_set)
Purpose:
Allows an application to determine which underlying security
mechanisms are available.
Parameters:
minor_status integer, modify
Mechanism specific status code.
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mech_set set of Object IDs, modify
set of implementation-supported mechanisms.
The returned gss_OID_set value will be a
pointer into static storage, and should be
treated as read-only by the caller.
Function value:
GSS status code:
GSS_S_COMPLETE Successful completion
7.13. gss_init_sec_context
OM_uint32 gss_init_sec_context (
OM_uint32 * minor_status,
gss_cred_id_t claimant_cred_handle,
gss_ctx_id_t * context_handle,
gss_name_t target_name,
gss_OID mech_type,
OM_uint32 req_flags,
OM_uint32 time_req,
gss_channel_bindings_t
input_chan_bindings,
gss_buffer_t input_token
gss_OID * actual_mech_type,
gss_buffer_t output_token,
OM_uint32 * ret_flags,
OM_uint32 * time_rec )
Purpose:
Initiates the establishment of a security context between the
application and a remote peer. Initially, the input_token parameter
should be specified either as GSS_C_NO_BUFFER, or as a pointer to a
gss_buffer_desc object whose length field contains the value zero.
The routine may return a output_token which should be transferred to
the peer application, where the peer application will present it to
gss_accept_sec_context. If no token need be sent,
gss_init_sec_context will indicate this by setting the length field
of the output_token argument to zero. To complete the context
establishment, one or more reply tokens may be required from the peer
application; if so, gss_init_sec_context will return a status
containing the supplementary information bit GSS_S_CONTINUE_NEEDED.
In this case, gss_init_sec_context should be called again when the
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reply token is received from the peer application, passing the reply
token to gss_init_sec_context via the input_token parameters.
Whenever the routine returns a major status that includes the value
GSS_S_CONTINUE_NEEDED, the values returned via the actual_mech_type,
and time_rec parameters are not defined, and the value returned via
the ret_flags parameter should contain the value that the
implementation expects would be valid if context establishment were
to succeed. In particular, if the application has requested a
service such as delegation or anonymous authentication via the
req_flags argument, and such a service is unavailable from the
underlying mechanism, gss_init_sec_context should generate a token
that will not provide the service, and indicate via the ret_flags
argument that the service will not be supported. The application may
choose to abort the context establishment by calling
gss_delete_sec_context (if it cannot continue in the absence of the
service), or it may choose to transmit the token and continue context
establishment (if the service was merely desired but not mandatory).
Parameters:
minor_status integer, modify
Mechanism specific status code.
claimant_cred_handle gss_cred_id_t, read, optional
handle for credentials claimed. Supply
GSS_C_NO_CREDENTIAL to act as a default
initiator principal. If no default
initator is defined, the function will
return GSS_S_NO_CRED.
context_handle gss_ctx_id_t, read/modify
context handle for new context. Supply
GSS_C_NO_CONTEXT for first call; use value
returned by first call in continuation calls.
target_name gss_name_t, read
Name of target
mech_type OID, read, optional
Object ID of desired mechanism. Supply
GSS_C_NO_OID to obtain an implementation
specific default
req_flags bit-mask, read
Contains various independent flags, each of
which requests that the context support a
specific service option. Symbolic
names are provided for each flag, and the
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symbolic names corresponding to the required
flags should be logically-ORed
together to form the bit-mask value. The
flags are:
GSS_C_DELEG_FLAG
True - Delegate credentials to remote peer
False - Don't delegate
GSS_C_MUTUAL_FLAG
True - Request that remote peer
authenticate itself
False - Authenticate self to remote peer
only
GSS_C_REPLAY_FLAG
True - Enable replay detection for
messages protected with gss_wrap
or gss_get_mic
False - Don't attempt to detect
replayed messages
GSS_C_SEQUENCE_FLAG
True - Enable detection of out-of-sequence
protected messages
False - Don't attempt to detect
out-of-sequence messages
GSS_C_ANON_FLAG
True - Do not reveal the initiator's
identity to the acceptor.
False - Authenticate normally.
time_req integer, read, optional
Desired number of seconds for which context
should remain valid. Supply 0 to request a
default validity period.
input_chan_bindings channel bindings, read, optional
Application-specified bindings. Allows
application to securely bind channel
identification information to the security
context. Specify GSS_C_NO_CHANNEL_BINDINGS
if channel bindings are not used.
input_token buffer, opaque, read, optional (see text)
Token received from peer application.
Supply GSS_C_NO_BUFFER, or a pointer to
a buffer containing the value GSS_C_EMPTY_BUFFER
on initial call.
actual_mech_type OID, modify, optional
Actual mechanism used. Specify NULL if
not required.
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output_token buffer, opaque, modify
token to be sent to peer application. If
the length field of the returned buffer is
zero, no token need be sent to the peer
application.
ret_flags bit-mask, modify, optional
Contains various independent flags, each of which
indicates that the context supports a specific
service option. Specify NULL if not
required. Symbolic names are provided
for each flag, and the symbolic names
corresponding to the required flags should be
logically-ANDed with the ret_flags value to test
whether a given option is supported by the
context. The flags are:
GSS_C_DELEG_FLAG
True - Credentials were delegated to
the remote peer
False - No credentials were delegated
GSS_C_MUTUAL_FLAG
True - Remote peer has been asked to
authenticated itself
False - Remote peer has not been asked to
authenticate itself
GSS_C_REPLAY_FLAG
True - replay of protected messages
will be detected
False - replayed messages will not be
detected
GSS_C_SEQUENCE_FLAG
True - out-of-sequence protected
messages will be detected
False - out-of-sequence messages will
not be detected
GSS_C_CONF_FLAG
True - Confidentiality service may be
invoked by calling gss_wrap routine
False - No confidentiality service (via
gss_wrap) available. gss_wrap will
provide message encapsulation,
data-origin authentication and
integrity services only.
GSS_C_INTEG_FLAG
True - Integrity service may be invoked by
calling either gss_get_mic or gss_wrap
routines.
False - Per-message integrity service
unavailable.
GSS_C_ANON_FLAG
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True - The initiator's identity has not been
revealed, and will not be revealed if
any emitted token is passed to the
acceptor.
False - The initiator's identity has been or
will be authenticated normally.
time_rec integer, modify, optional
number of seconds for which the context
will remain valid. If the implementation does
not support credential expiration, the value
GSS_C_INDEFINITE will be returned. Specify
NULL if not required.
Function value:
GSS status code:
GSS_S_COMPLETE Successful completion
GSS_S_CONTINUE_NEEDED Indicates that a token from the peer
application is required to complete thecontext, and
that gss_init_sec_context must be called again with
that token.
GSS_S_DEFECTIVE_TOKEN Indicates that consistency checks performed on
the input_token failed
GSS_S_DEFECTIVE_CREDENTIAL Indicates that consistency checks
performed on the credential failed.
GSS_S_NO_CRED The supplied credentials were not valid for context
initiation, or the credential handle did not
reference any credentials.
GSS_S_CREDENTIALS_EXPIRED The referenced credentials have expired
GSS_S_BAD_BINDINGS The input_token contains different channel
bindings to those specified via the
input_chan_bindings parameter
GSS_S_BAD_SIG The input_token contains an invalid signature, or a
signature that could not be verified
GSS_S_OLD_TOKEN The input_token was too old. This is a fatal error
during context establishment
GSS_S_DUPLICATE_TOKEN The input_token is valid, but is a duplicate of
a token already processed. This is a fatal error
during context establishment.
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GSS_S_NO_CONTEXT Indicates that the supplied context handle did not
refer to a valid context
GSS_S_BAD_NAMETYPE The provided target_name parameter contained an
invalid or unsupported type of name
GSS_S_BAD_NAME The provided target_name parameter was ill-formed.
GSS_S_BAD_MECH The specified mechanism is not supported by the
provided credential, or is unrecognized by the
implementation.
7.14. gss_inquire_context
OM_uint32 gss_inquire_context (
OM_uint32 * minor_status,
gss_ctx_id_t context_handle,
gss_name_t * src_name,
gss_name_t * targ_name,
OM_uint32 * lifetime_rec,
gss_OID * mech_type,
OM_uint32 * ctx_flags,
int * locally_initiated,
int * open)
Purpose:
Obtains information about a security context. The caller must
already have obtained a handle that refers to the context, although
the context need not be fully established.
Parameters:
minor_status integer, modify
Mechanism specific status code
context_handle gss_ctx_id_t, read
A handle that refers to the security context.
src_name gss_name_t, modify, optional
The name of the context initiator.
If the context was established using anonymous
authentication, and if the application invoking
gss_inquire_context is the context acceptor,
an anonymous name will be returned.
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Specify NULL if not required.
targ_name gss_name_t, modify, optional
The name of the context acceptor.
Specify NULL if not required.
lifetime_rec Integer, modify, optional
The number of seconds for which the credential
will remain valid. If the credential has
expired, this parameter will be set to zero.
If the implementation does not support
credential expiration, the value
GSS_C_INDEFINITE will be returned. Specify
NULL if not required.
mech_type gss_OID, modify, optional
The security mechanism providing the
context.
Specify NULL if not required.
ctx_flags bit-mask, modify, optional
Contains various independent flags, each of
which indicates that the context supports
(or is expected to support, if ctx_open is
false) a specific service option. If not
needed, specify NULL. Symbolic names are
provided for each flag, and the symbolic names
corresponding to the required flags
should be logically-ANDed with the ret_flags
value to test whether a given option is
supported by the context. The flags are:
GSS_C_DELEG_FLAG
True - Credentials were delegated from
the initiator to the acceptor.
False - No credentials were delegated
GSS_C_MUTUAL_FLAG
True - The acceptor was authenticated
to the initiator
False - The acceptor did not authenticate
itself.
GSS_C_REPLAY_FLAG
True - replay of protected messages
will be detected
False - replayed messages will not be
detected
GSS_C_SEQUENCE_FLAG
True - out-of-sequence protected
messages will be detected
False - out-of-sequence messages will not
be detected
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GSS_C_CONF_FLAG
True - Confidentiality service may be invoked
by calling gss_wrap routine
False - No confidentiality service (via
gss_wrap) available. gss_wrap will
provide message encapsulation,
data-origin authentication and
integrity services only.
GSS_C_INTEG_FLAG
True - Integrity service may be invoked by
calling either gss_get_mic or gss_wrap
routines.
False - Per-message integrity service
unavailable.
GSS_C_ANON_FLAG
True - The initiator's identity will not
be revealed to the acceptor.
The src_name parameter (if
requested) contains an anonymous
internal name.
False - The initiator has been
authenticated normally.
locally_initiated Boolean, modify
True if the invoking application is the
context initiator.
Specify NULL if not required.
open Boolean, modify
True if the context is fully established;
false if a context-establishment token
is expected from the peer application.
Specify NULL if not required.
Function value:
GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_NO_CONTEXT The referenced context could not be accessed.
GSS_S_CONTEXT_EXPIRED The context has expired. If the lifetime_rec
parameter was requested, it will be set to 0.
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7.15. gss_inquire_cred
OM_uint32 gss_inquire_cred (
OM_uint32 * minor_status,
gss_cred_id_t cred_handle,
gss_name_t * name,
OM_uint32 * lifetime,
gss_cred_usage_t * cred_usage,
gss_OID_set * mechanisms )
Purpose:
Obtains information about a credential. The caller must already have
obtained a handle that refers to the credential.
Parameters:
minor_status integer, modify
Mechanism specific status code
cred_handle gss_cred_id_t, read
A handle that refers to the target credential.
Specify GSS_C_NO_CREDENTIAL to inquire about
the default initiator principal.
name gss_name_t, modify, optional
The name whose identity the credential asserts.
Specify NULL if not required.
lifetime Integer, modify, optional
The number of seconds for which the credential
will remain valid. If the credential has
expired, this parameter will be set to zero.
If the implementation does not support
credential expiration, the value
GSS_C_INDEFINITE will be returned. Specify
NULL if not required.
cred_usage gss_cred_usage_t, modify, optional
How the credential may be used. One of the
following:
GSS_C_INITIATE
GSS_C_ACCEPT
GSS_C_BOTH
Specify NULL if not required.
mechanisms gss_OID_set, modify, optional
Set of mechanisms supported by the credential.
Specify NULL if not required.
Function value:
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GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_NO_CRED The referenced credentials could not be accessed.
GSS_S_DEFECTIVE_CREDENTIAL The referenced credentials were invalid.
GSS_S_CREDENTIALS_EXPIRED The referenced credentials have expired.
If the lifetime parameter was not passed as NULL,
it will be set to 0.
7.16. gss_process_context_token
OM_uint32 gss_process_context_token (
OM_uint32 * minor_status,
gss_ctx_id_t context_handle,
gss_buffer_t token_buffer,
gss_buffer_t output_token)
Purpose:
Provides a way to pass a token to the security service. Usually,
tokens are associated either with context establishment (when they
would be passed to gss_init_sec_context or gss_accept_sec_context) or
with per-message security service (when they would be passed to
gss_verify_mic or gss_unwrap). Occasionally, tokens may be received
at other times, and gss_process_context_token allows such tokens to
be passed to the underlying security service for processing. At
present, such additional tokens may only be generated by
gss_delete_sec_context. GSS-API implementation may use this service
to implement deletion of the security context.
Parameters:
minor_status integer, modify
Implementation specific status code.
context_handle gss_ctx_id_t, read
context handle of context on which token is to
be processed
token_buffer buffer, opaque, read
token to process
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output_token buffer, opaque, modify
A token that the application should send
to the peer. If no token need be
sent, GSS-API will set the length field
to zero.
Function value:
GSS status code:
GSS_S_COMPLETE Successful completion
GSS_S_DEFECTIVE_TOKEN Indicates that consistency checks performed on
the token failed
GSS_S_NO_CONTEXT The context_handle did not refer to a valid context
7.17. gss_release_buffer
OM_uint32 gss_release_buffer (
OM_uint32 * minor_status,
gss_buffer_t buffer)
Purpose:
Free storage associated with a buffer format name. The storage must
have been allocated by a GSS-API routine. In addition to freeing the
associated storage, the routine will zero the length field in the
buffer parameter.
Parameters:
minor_status integer, modify
Mechanism specific status code
buffer buffer, modify
The storage associated with the buffer will be
deleted. The gss_buffer_desc object will not
be freed, but its length field will be zeroed.
Function value:
GSS status code
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GSS_S_COMPLETE Successful completion
7.18. gss_release_cred
OM_uint32 gss_release_cred (
OM_uint32 * minor_status,
gss_cred_id_t * cred_handle)
Purpose:
Informs GSS-API that the specified credential handle is no longer
required by the process. When all processes have released a
credential, it will be deleted.
Parameters:
cred_handle gss_cred_id_t, modify, optional
Buffer containing opaque credential
handle. If GSS_C_NO_CREDENTIAL is supplied,
the routine will complete successfully, but
will do nothing.
minor_status integer, modify
Mechanism specific status code.
Function value:
GSS status code:
GSS_S_COMPLETE Successful completion
GSS_S_NO_CRED Credentials could not be accessed.
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7.19. gss_release_name
OM_uint32 gss_release_name (
OM_uint32 * minor_status,
gss_name_t * name)
Purpose:
Free GSSAPI-allocated storage by associated with an internal form
name.
Parameters:
minor_status integer, modify
Mechanism specific status code
name gss_name_t, modify
The name to be deleted
Function value:
GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_BAD_NAME The name parameter did not contain a valid name
7.20. gss_release_oid_set
OM_uint32 gss_release_oid_set (
OM_uint32 * minor_status,
gss_OID_set * set)
Purpose:
Free storage associated with a gss_OID_set object. The storage must
have been allocated by a GSS-API routine.
Parameters:
minor_status integer, modify
Mechanism specific status code
set Set of Object IDs, modify
The storage associated with the gss_OID_set
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will be deleted.
Function value:
GSS status code
GSS_S_COMPLETE Successful completion
7.21. gss_unwrap
OM_uint32 gss_unwrap (
OM_uint32 * minor_status,
gss_ctx_id_t context_handle,
gss_buffer_t input_message_buffer,
gss_buffer_t output_message_buffer,
int * conf_state,
gss_qop_t * qop_state)
Purpose:
Converts a message previously protected by gss_wrap back to a usable
form, verifying the embedded signature. The conf_state parameter
indicates whether the message was encrypted; the qop_state parameter
indicates the strength of protection that was used to provide the
confidentiality and integrity services.
Parameters:
minor_status integer, modify
Mechanism specific status code.
context_handle gss_ctx_id_t, read
Identifies the context on which the message
arrived
input_message_buffer buffer, opaque, read
protected message
output_message_buffer buffer, opaque, modify
Buffer to receive unwrapped message
conf_state boolean, modify, optional
True - Confidentiality and integrity protection
were used
False - Inteegrity service only was used
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Specify NULL if not required
qop_state gss_qop_t, modify, optional
Quality of protection gained from signature
Specify NULL if not required
Function value:
GSS status code:
GSS_S_COMPLETE Successful completion
GSS_S_DEFECTIVE_TOKEN The token failed consistency checks
GSS_S_BAD_SIG The signature was incorrect
GSS_S_DUPLICATE_TOKEN The token was valid, and contained a correct
signature for the message, but it had already been
processed
GSS_S_OLD_TOKEN The token was valid, and contained a correct
signature for the message, but it is too old to
check for duplication.
GSS_S_UNSEQ_TOKEN The token was valid, and contained a correct
signature for the message, but has been verified
out of sequence; a later token has already been
received.
GSS_S_GAP_TOKEN The token was valid, and contained a correct
signature for the message, but has been verified
out of sequence; an earlier expected token has not
yet been received.
GSS_S_CONTEXT_EXPIRED The context has already expired
GSS_S_CREDENTIALS_EXPIRED The context is recognized, but associated
credentials have expired
GSS_S_NO_CONTEXT The context_handle parameter did not identify a
valid context
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7.22. gss_verify_mic
OM_uint32 gss_verify_mic (
OM_uint32 * minor_status,
gss_ctx_id_t context_handle,
gss_buffer_t message_buffer,
gss_buffer_t token_buffer,
gss_qop_t * qop_state)
Purpose:
Verifies that a cryptographic signature, contained in the token
parameter, fits the supplied message. The qop_state parameter allows
a message recipient to determine the strength of protection that was
applied to the message.
Parameters:
minor_status integer, modify
Mechanism specific status code.
context_handle gss_ctx_id_t, read
Identifies the context on which the message
arrived
message_buffer buffer, opaque, read
Message to be verified
token_buffer buffer, opaque, read
Token associated with message
qop_state gss_qop_t, modify, optionalo
quality of protection gained from signature
Specify NULL if not required
Function value:
GSS status code:
GSS_S_COMPLETE Successful completion
GSS_S_DEFECTIVE_TOKEN The token failed consistency checks
GSS_S_BAD_SIG The signature was incorrect
GSS_S_DUPLICATE_TOKEN The token was valid, and contained a correct
signature for the message, but it had already been
processed
GSS_S_OLD_TOKEN The token was valid, and contained a correct
signature for the message, but it is too old to
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check for duplication.
GSS_S_UNSEQ_TOKEN The token was valid, and contained a correct
signature for the message, but has been verified
out of sequence; a later token has already been
received.
GSS_S_GAP_TOKEN The token was valid, and contained a correct
signature for the message, but has been verified
out of sequence; an earlier expected token has not
yet been received.
GSS_S_CONTEXT_EXPIRED The context has already expired
GSS_S_CREDENTIALS_EXPIRED The context is recognized, but associated
credentials have expired
GSS_S_NO_CONTEXT The context_handle parameter did not identify a
valid context
7.23. gss_wrap
OM_uint32 gss_wrap (
OM_uint32 * minor_status,
gss_ctx_id_t context_handle,
int conf_req_flag,
gss_qop_t qop_req
gss_buffer_t input_message_buffer,
int * conf_state,
gss_buffer_t output_message_buffer)
Purpose:
Cryptographically signs and optionally encrypts the specified
input_message. The output_message contains both the signature and
the message. The qop_req parameter allows a choice between several
cryptographic algorithms, if supported by the chosen mechanism.
Parameters:
minor_status integer, modify
Mechanism specific status code.
context_handle gss_ctx_id_t, read
Identifies the context on which the message
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will be sent
conf_req_flag boolean, read
True - Both confidentiality and integrity
services are requested
False - Only integrity service is requested
qop_req gss_qop_t, read, optional
Specifies required quality of protection. A
mechanism-specific default may be requested by
setting qop_req to GSS_C_QOP_DEFAULT. If an
unsupported protection strength is requested,
gss_wrap will return a major_status of
GSS_S_BAD_QOP.
input_message_buffer buffer, opaque, read
Message to be protected
conf_state boolean, modify, optional
True - Confidentiality, data origin
authentication and integrity services
have been applied
False - Integrity and data origin services only
has been applied.
Specify NULL if not required
output_message_buffer buffer, opaque, modify
Buffer to receive protected message
Function value:
GSS status code:
GSS_S_COMPLETE Successful completion
GSS_S_CONTEXT_EXPIRED The context has already expired
GSS_S_CREDENTIALS_EXPIRED The context is recognized, but associated
credentials have expired
GSS_S_NO_CONTEXT The context_handle parameter did not identify a
valid context
GSS_S_BAD_QOP The specified QOP is not supported by the
mechanism.
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7.24. gss_wrap_size_limit
OM_uint32 gss_wrap_size_limit (
OM_uint32 * minor_status,
gss_ctx_id_t context_handle,
int conf_req_flag,
gss_qop_t qop_req,
OM_uint32 req_output_size,
OM_uint32 * max_input_size)
Purpose:
Allows an application to determine the maximum message size that, if
presented to gss_wrap with the same conf_req_flag and qop_req
parameters, will result in an output token containing no more than
req_output_size bytes.
This call is intended for use by applications that communicate over
protocols that impose a maximum message size. It enables the
application to fragment messages prior to applying protection.
Successful completion of this call does not guarantee that gss_wrap
will be able to protect a message of length max_input_bytes, since
this ability may depend on the availability of system resources at
the time that gss_wrap is called. However, if the implementation
itself imposes an upper limit on the length of messages that may be
processed by gss_wrap, the implementation should not return a value
via max_input_bytes that is greater than this length.
Parameters:
minor_status integer, modify
Mechanism specific status code
context_handle gss_ctx_id_t, read
A handle that refers to the security over
which the messages will be sent.
conf_req_flag Boolean, read
Indicates whether gss_wrap will be asked
to apply confidentiality protection in
addition to integrity protection. See
the routine description for gss_wrap
for more details.
qop_req gss_qop_t, read
Indicates the level of protection that
gss_wrap will be asked to provide. See
the routine description for gss_wrap for
more details.
req_output_size Integer, read
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The desired maximum size for tokens emitted
by gss_wrap.
max_input_size Integer, modify
The maximum input message size that may
be presented to gss_wrap in order to
guarantee that the emitted token shall
be no larger than req_output_size bytes.
Function value:
GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_NO_CONTEXT The referenced context could not be accessed.
GSS_S_CONTEXT_EXPIRED The context has expired.
GSS_S_BAD_QOP The specified QOP is not supported by the
mechanism.
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APPENDIX A. GSS-API C header file gssapi.h
C-language GSS-API implementations should include a copy of the
following header-file.
#ifndef GSSAPI_H_
#define GSSAPI_H_
/*
* First, include stddef.h to get size_t defined.
*/
#include <stddef.h>
/*
* If the platform supports the xom.h header file, it should be
* included here.
*/
#include <xom.h>
/*
* First, define the three platform-dependent pointer types.
*/
typedef <platform-specific> gss_ctx_id_t;
typedef <platform-specific> gss_cred_id_t;
typedef <platform-specific> gss_name_t;
/*
* The following type must be defined as the smallest natural
* unsigned integer supported by the platform that has at least
* 32 bits of precision.
*/
typedef <platform-specific> gss_uint32;
#ifdef OM_STRING
/*
* We have included the xom.h header file. Verify that OM_uint32
* is defined correctly.
*/
#if sizeof(gss_uint32) != sizeof(OM_uint32)
#error Incompatible definition of OM_uint32 from xom.h
#endif
typedef OM_object_identifier gss_OID_desc, *gss_OID;
#else
/*
* We can't use X/Open definitions, so roll our own.
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*/
typedef gss_uint32 OM_uint32;
typedef struct gss_OID_desc_struct {
OM_uint32 length;
void *elements;
} gss_OID_desc, *gss_OID;
#endif
typedef struct gss_OID_set_desc_struct {
size_t count;
gss_OID elements;
} gss_OID_set_desc, *gss_OID_set;
typedef struct gss_buffer_desc_struct {
size_t length;
void *value;
} gss_buffer_desc, *gss_buffer_t;
typedef struct gss_channel_bindings_struct {
OM_uint32 initiator_addrtype;
gss_buffer_desc initiator_address;
OM_uint32 acceptor_addrtype;
gss_buffer_desc acceptor_address;
gss_buffer_desc application_data;
} *gss_channel_bindings_t;
/*
* For now, define a QOP-type as an OM_uint32 (pending resolution
* of ongoing discussions).
*/
typedef OM_uint32 gss_qop_t;
typedef int gss_cred_usage_t;
/*
* Flag bits for context-level services.
*/
#define GSS_C_DELEG_FLAG 1
#define GSS_C_MUTUAL_FLAG 2
#define GSS_C_REPLAY_FLAG 4
#define GSS_C_SEQUENCE_FLAG 8
#define GSS_C_CONF_FLAG 16
#define GSS_C_INTEG_FLAG 32
#define GSS_C_ANON_FLAG 64
/*
* Credential usage options
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*/
#define GSS_C_BOTH 0
#define GSS_C_INITIATE 1
#define GSS_C_ACCEPT 2
/*
* Status code types for gss_display_status
*/
#define GSS_C_GSS_CODE 1
#define GSS_C_MECH_CODE 2
/*
* The constant definitions for channel-bindings address families
*/
#define GSS_C_AF_UNSPEC 0
#define GSS_C_AF_LOCAL 1
#define GSS_C_AF_INET 2
#define GSS_C_AF_IMPLINK 3
#define GSS_C_AF_PUP 4
#define GSS_C_AF_CHAOS 5
#define GSS_C_AF_NS 6
#define GSS_C_AF_NBS 7
#define GSS_C_AF_ECMA 8
#define GSS_C_AF_DATAKIT 9
#define GSS_C_AF_CCITT 10
#define GSS_C_AF_SNA 11
#define GSS_C_AF_DECnet 12
#define GSS_C_AF_DLI 13
#define GSS_C_AF_LAT 14
#define GSS_C_AF_HYLINK 15
#define GSS_C_AF_APPLETALK 16
#define GSS_C_AF_BSC 17
#define GSS_C_AF_DSS 18
#define GSS_C_AF_OSI 19
#define GSS_C_AF_X25 21
#define GSS_C_AF_NULLADDR 255
/*
* Various Null values
*/
#define GSS_C_NO_BUFFER ((gss_buffer_t) 0)
#define GSS_C_NO_OID ((gss_OID) 0)
#define GSS_C_NO_OID_SET ((gss_OID_set) 0)
#define GSS_C_NO_CONTEXT ((gss_ctx_id_t) 0)
#define GSS_C_NO_CREDENTIAL ((gss_cred_id_t) 0)
#define GSS_C_NO_CHANNEL_BINDINGS ((gss_channel_bindings_t) 0)
#define GSS_C_EMPTY_BUFFER {0, NULL}
/*
* Some alternate names for a couple of the above
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* values. These are defined for V1 compatibility.
*/
#define GSS_C_NULL_OID GSS_C_NO_OID
#define GSS_C_NULL_OID_SET GSS_C_NO_OID_SET
/*
* Define the default Quality of Protection for per-message
* services. Note that an implementation that offers multiple
* levels of QOP may either reserve a value (for example zero,
* as assumed here) to mean "default protection", or
* alternatively may simply equate GSS_C_QOP_DEFAULT to a specific
* explicit QOP value. However, a value of 0 should always be
* interpreted by a GSSAPI implementation as a request for the
* default protection level.
*/
#define GSS_C_QOP_DEFAULT 0
/*
* Expiration time of 2^32-1 seconds means infinite lifetime for a
* credential or security context
*/
#define GSS_C_INDEFINITE 0xfffffffful
/*
* The implementation must reserve static storage for a
* gss_OID_desc object containing the value
* {4, (void *)"}, and GSS_C_NAMETYPE_ANONYMOUS
* should be initialized to point to that gss_OID_desc.
*/
extern gss_OID GSS_C_NAMETYPE_ANONYMOUS;
/* Major status codes */
#define GSS_S_COMPLETE 0
/*
* Some "helper" definitions to make the status code macros obvious.
*/
#define GSS_C_CALLING_ERROR_OFFSET 24
#define GSS_C_ROUTINE_ERROR_OFFSET 16
#define GSS_C_SUPPLEMENTARY_OFFSET 0
#define GSS_C_CALLING_ERROR_MASK 0377ul
#define GSS_C_ROUTINE_ERROR_MASK 0377ul
#define GSS_C_SUPPLEMENTARY_MASK 0177777ul
/*
* The macros that test status codes for error conditions.
* Note that the GSS_ERROR() macro has changed slightly from
* the V1 GSSAPI so that it now evaluates its argument
* only once.
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*/
#define GSS_CALLING_ERROR(x) \
(x & (GSS_C_CALLING_ERROR_MASK << GSS_C_CALLING_ERROR_OFFSET))
#define GSS_ROUTINE_ERROR(x) \
(x & (GSS_C_ROUTINE_ERROR_MASK << GSS_C_ROUTINE_ERROR_OFFSET))
#define GSS_SUPPLEMENTARY_INFO(x) \
(x & (GSS_C_SUPPLEMENTARY_MASK << GSS_C_SUPPLEMENTARY_OFFSET))
#define GSS_ERROR(x) \
(x & ((GSS_C_CALLING_ERROR_MASK << GSS_C_CALLING_ERROR_OFFSET) | \
(GSS_C_ROUTINE_ERROR_MASK << GSS_C_ROUTINE_ERROR_OFFSET)))
/*
* Now the actual status code definitions
*/
/*
* Calling errors:
*/
#define GSS_S_CALL_INACCESSIBLE_READ \
(1ul << GSS_C_CALLING_ERROR_OFFSET)
#define GSS_S_CALL_INACCESSIBLE_WRITE \
(2ul << GSS_C_CALLING_ERROR_OFFSET)
#define GSS_S_CALL_BAD_STRUCTURE \
(3ul << GSS_C_CALLING_ERROR_OFFSET)
/*
* Routine errors:
*/
#define GSS_S_BAD_MECH (1ul << GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_BAD_NAME (2ul << GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_BAD_NAMETYPE (3ul << GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_BAD_BINDINGS (4ul << GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_BAD_STATUS (5ul << GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_BAD_SIG (6ul << GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_NO_CRED (7ul << GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_NO_CONTEXT (8ul << GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_DEFECTIVE_TOKEN (9ul << GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_DEFECTIVE_CREDENTIAL (10ul << GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_CREDENTIALS_EXPIRED (11ul << GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_CONTEXT_EXPIRED (12ul << GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_FAILURE (13ul << GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_BAD_QOP (14ul << GSS_C_ROUTINE_ERROR_OFFSET)
/*
* Supplementary info bits:
*/
#define GSS_S_CONTINUE_NEEDED (1ul << (GSS_C_SUPPLEMENTARY_OFFSET + 0))
#define GSS_S_DUPLICATE_TOKEN (1ul << (GSS_C_SUPPLEMENTARY_OFFSET + 1))
#define GSS_S_OLD_TOKEN (1ul << (GSS_C_SUPPLEMENTARY_OFFSET + 2))
#define GSS_S_UNSEQ_TOKEN (1ul << (GSS_C_SUPPLEMENTARY_OFFSET + 3))
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/*
* Finally, function prototypes for the GSS-API routines.
*/
OM_uint32 gss_acquire_cred
(OM_uint32*, /* minor_status */
gss_name_t, /* desired_name */
OM_uint32, /* time_req */
gss_OID_set, /* desired_mechs */
gss_cred_usage_t, /* cred_usage */
gss_cred_id_t*, /* output_cred_handle */
gss_OID_set*, /* actual_mechs */
OM_uint32* /* time_rec */
);
OM_uint32 gss_release_cred
(OM_uint32*, /* minor_status */
gss_cred_id_t* /* cred_handle */
);
OM_uint32 gss_init_sec_context
(OM_uint32*, /* minor_status */
gss_cred_id_t, /* claimant_cred_handle */
gss_ctx_id_t*, /* context_handle */
gss_name_t, /* target_name */
gss_OID, /* mech_type */
OM_uint32, /* req_flags */
OM_uint32, /* time_req */
gss_channel_bindings_t,
/* input_chan_bindings */
gss_buffer_t, /* input_token */
gss_OID*, /* actual_mech_type */
gss_buffer_t, /* output_token */
OM_uint32*, /* ret_flags */
OM_uint32* /* time_rec */
);
OM_uint32 gss_accept_sec_context
(OM_uint32*, /* minor_status */
gss_ctx_id_t*, /* context_handle */
gss_cred_id_t, /* verifier_cred_handle */
gss_buffer_t, /* input_token_buffer */
gss_channel_bindings_t,
/* input_chan_bindings */
gss_name_t*, /* src_name */
gss_OID*, /* mech_type */
gss_buffer_t, /* output_token */
OM_uint32*, /* ret_flags */
OM_uint32*, /* time_rec */
gss_cred_id_t* /* delegated_cred_handle */
);
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OM_uint32 gss_process_context_token
(OM_uint32*, /* minor_status */
gss_ctx_id_t, /* context_handle */
gss_buffer_t, /* token_buffer */
gss_buffer_t /* output_token */
);
OM_uint32 gss_delete_sec_context
(OM_uint32*, /* minor_status */
gss_ctx_id_t*, /* context_handle */
gss_buffer_t /* output_token */
);
OM_uint32 gss_context_time
(OM_uint32*, /* minor_status */
gss_ctx_id_t, /* context_handle */
OM_uint32* /* time_rec */
);
OM_uint32 gss_get_mic
(OM_uint32*, /* minor_status */
gss_ctx_id_t, /* context_handle */
gss_qop_t, /* qop_req */
gss_buffer_t, /* message_buffer */
gss_buffer_t /* message_token */
);
OM_uint32 gss_verify_mic
(OM_uint32*, /* minor_status */
gss_ctx_id_t, /* context_handle */
gss_buffer_t, /* message_buffer */
gss_buffer_t, /* token_buffer */
gss_qop_t* /* qop_state */
);
OM_uint32 gss_wrap
(OM_uint32*, /* minor_status */
gss_ctx_id_t, /* context_handle */
int, /* conf_req_flag */
gss_qop_t, /* qop_req */
gss_buffer_t, /* input_message_buffer */
int*, /* conf_state */
gss_buffer_t /* output_message_buffer */
);
OM_uint32 gss_unwrap
(OM_uint32*, /* minor_status */
gss_ctx_id_t, /* context_handle */
gss_buffer_t, /* input_message_buffer */
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gss_buffer_t, /* output_message_buffer */
int*, /* conf_state */
gss_qop_t* /* qop_state */
);
OM_uint32 gss_display_status
(OM_uint32*, /* minor_status */
OM_uint32, /* status_value */
int, /* status_type */
gss_OID, /* mech_type */
OM_uint32*, /* message_context */
gss_buffer_t /* status_string */
);
OM_uint32 gss_indicate_mechs
(OM_uint32*, /* minor_status */
gss_OID_set* /* mech_set */
);
OM_uint32 gss_compare_name
(OM_uint32*, /* minor_status */
gss_name_t, /* name1 */
gss_name_t, /* name2 */
int* /* name_equal */
);
OM_uint32 gss_display_name
(OM_uint32*, /* minor_status */
gss_name_t, /* input_name */
gss_buffer_t, /* output_name_buffer */
gss_OID* /* output_name_type */
);
OM_uint32 gss_import_name
(OM_uint32*, /* minor_status */
gss_buffer_t, /* input_name_buffer */
gss_OID, /* input_name_type */
gss_name_t* /* output_name */
);
OM_uint32 gss_release_name
(OM_uint32*, /* minor_status */
gss_name_t* /* input_name */
);
OM_uint32 gss_release_buffer
(OM_uint32*, /* minor_status */
gss_buffer_t /* buffer */
);
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OM_uint32 gss_release_oid_set
(OM_uint32*, /* minor_status */
gss_OID_set* /* set */
);
OM_uint32 gss_inquire_cred
(OM_uint32 *, /* minor_status */
gss_cred_id_t, /* cred_handle */
gss_name_t *, /* name */
OM_uint32 *, /* lifetime */
gss_cred_usage_t *, /* cred_usage */
gss_OID_set * /* mechanisms */
);
/*
* The following routines are obsolete variants of gss_get_mic,
* gss_wrap, gss_verify_mic and gss_unwrap. They should be
* provided by GSSAPI V2 implementations for backwards
* compatibility with V1 applications. Distinct entrypoints
* (as opposed to #defines) should be provided, to allow GSSAPI
* V1 applications to link against GSSAPI V2 implementations.
*/
OM_uint32 gss_sign
(OM_uint32*, /* minor_status */
gss_ctx_id_t, /* context_handle */
int, /* qop_req */
gss_buffer_t, /* message_buffer */
gss_buffer_t /* message_token */
);
OM_uint32 gss_verify
(OM_uint32*, /* minor_status */
gss_ctx_id_t, /* context_handle */
gss_buffer_t, /* message_buffer */
gss_buffer_t, /* token_buffer */
int* /* qop_state */
);
OM_uint32 gss_seal
(OM_uint32*, /* minor_status */
gss_ctx_id_t, /* context_handle */
int, /* conf_req_flag */
int, /* qop_req */
gss_buffer_t, /* input_message_buffer */
int*, /* conf_state */
gss_buffer_t /* output_message_buffer */
);
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OM_uint32 gss_unseal
(OM_uint32*, /* minor_status */
gss_ctx_id_t, /* context_handle */
gss_buffer_t, /* input_message_buffer */
gss_buffer_t, /* output_message_buffer */
int*, /* conf_state */
int* /* qop_state */
);
#endif /* GSSAPI_H_ */
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APPENDIX B. Routines for further discussion
The following convenience routines are presented for discussion.
They are not currently part of the GSS-API. They provide support
services for Object Identifiers and OID sets.
B.1. gss_create_empty_oid_set
OM_uint32 gss_create_empty_oid_set (
OM_uint32 * minor_status,
gss_OID_set * oid_set)
Purpose:
Create an object-identifier set containing no object identifiers, to
which members may be subsequently added using the
gss_add_oid_set_member routine. These routines are intended to be
used to construct sets of mechanism object identifiers, for input to
gss_acquire_cred.
Parameters:
minor_status integer, modify
Mechanism specific status code
oid_set Set of Object IDs, modify
The empty object identifier set.
The routine will allocate the
gss_OID_set_desc object.
Function value:
GSS status code
GSS_S_COMPLETE Successful completion
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B.2. gss_add_oid_set_member
OM_uint32 gss_add_oid_set_member (
OM_uint32 * minor_status,
gss_OID member_oid,
gss_OID_set * oid_set)
Purpose:
Add an Object Identifier to an Object Identifier set. This routine
is intended for use in conjunction with gss_create_empty_oid_set when
constructing a set of mechanism OIDs for input to gss_acquire_cred.
Parameters:
minor_status integer, modify
Mechanism specific status code
member_oid Object ID, read
The object identifier to copied into
the set.
oid_set Set of Object ID, modify
The set in which the objectidentifier
should be inserted.
Function value:
GSS status code
GSS_S_COMPLETE Successful completion
B.3. gss_test_oid_set_member
OM_uint32 gss_test_oid_set_member (
OM_uint32 * minor_status,
gss_OID member,
gss_OID_set set,
int * present)
Purpose:
Interrogate an Object Identifier set to determine whether a specified
Object Identifier is a member. This routine is intended to be used
with OID sets returned by gss_indicate_mechs, gss_acquire_cred, and
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gss_inquire_cred.
Parameters:
minor_status integer, modify
Mechanism specific status code
member Object ID, read
The object identifier whose presence
is to be tested.
set Set of Object ID, read
The Object Identifier set.
present Boolean, modify
True if the specified OID is a member
of the set, flase if not.
Function value:
GSS status code
GSS_S_COMPLETE Successful completion
B.4. gss_release_oid
OM_uint32 gss_release_oid (
OM_uint32 * minor_status,
gss_OID * oid)
Purpose:
Discard an OID. This routine is provided for completeness only.
While some of the GSS-API routines return OIDs, these routines are
currently documented as returning pointers to structures maintained
in static storage. gss_release_oid will recognise any of the GSS-
API's own OID values, and will silently ignore attempts to free these
OIDs; for other OIDs it will call the C free() routine for both the
OID data and the descriptor. This allows applications to freely mix
their own heap-allocated OID values with OIDs returned by GSS-API.
Parameters:
minor_status integer, modify
Mechanism specific status code
oid Object ID, modify
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The object identifier to be freed.
Function value:
GSS status code
GSS_S_COMPLETE Successful completion
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APPENDIX C. Additional constraints for application binary portability
The purpose of this C-bindings document is to encourage source-level
portability of applications across GSS-API implementations on
different platforms and atop different mechanisms. Additional goals
that have not been explicitly addressed by this document are link-
time and run-time portability.
Link-time portability provides the ability to compile an application
against one implementation of GSS-API, and then link it against a
different implementation on the same platform. It is a stricter
requirement than source-level portability.
Run-time portability differs from link-time portability only on those
platforms that implement dynamically loadable GSS-API
implementations, but do not offer load-time symbol resolution. On
such platforms, run-time portability is a stricter requirement than
link-time portability, and will typically include the precise
placement of the various GSS-API routines within library entrypoint
vectors.
Individual platforms will impose their own rules that must be
followed to achieve link-time (and run-time, if different)
portability. In order to ensure either form of binary portability,
an ABI specification must be written for GSS-API implementations on
that platform. However, it is recognised that there are some issues
that are likely to be common to all such ABI specifications. This
appendix is intended to be a repository for such common issues, and
contains some suggestions that individual ABI specifications may
choose to reference. Since machine architectures vary greatly, it
may not be possible or desirable to follow these suggestions on all
platforms.
C.1. Pointers
While ANSI-C provides a single pointer type for each declared type,
plus a single (void *) type, some platforms (notably those using
segmented memory architectures) augment this with various modified
pointer types (e.g. far pointers, near pointers). These language
bindings assume ANSI-C, and thus do not address such non-standard
implementations. GSS-API implementations for such platforms must
choose an appropriate memory model, and should use it consistently
throughout. For example, if a memory model is chosen that requires
the use of far pointers when passing routine parameters, then far
pointers should also be used within the structures defined by GSS-
API.
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C.2. Internal structure alignment
GSS-API defines several data-structures containing differently-sized
fields. An ABI specification should include a detailed description
of how the fields of such structures are aligned, and if there is any
internal padding in these data structures. The use of compiler
defaults for the platform is recommended.
C.3. Handle types
The C bindings specify that the gss_cred_id_t and gss_ctx_id_t types
should be implemented as either pointer or arithmetic types, and that
if pointer types are used, care should be taken to ensure that two
handles may be compared with the == operator. Note that ANSI-C does
not guarantee that two pointer values may be compared with the ==
operator unless either the two pointers point to members of a single
array, or at least one of the pointers contains a NULL value.
For binary portability the additional constraints are required. The
following is an attempt at defining platform-independent constraints.
(a) The size of the handle type must be the same as sizeof(void *),
using the appropriate memory model.
(b) The == operator for the chosen type must be a simple bit-wise
comparison. That is, for two in-memory handle objects h1 and
h2, the boolean value of the expression
(h1 == h2)
should always be the same as the boolean value of the
expression
(memcmp(&h1, &h2, sizeof(h1)) == 0)
(c) The actual use of the type (void *) for handle types is
discouraged, not for binary portability reasons, but since it
effectively disables much of the compile-time type-checking
that the compiler can otherwise perform, and is therefore not
"programmer-friendly". If a pointer implementation is desired,
and if the platform's implementation of pointers permits, the
handles should be implemented as pointers to distinct
implementation-defined types.
C.4. The gss_name_t type
The gss_name_t type, representing the internal name object, should be
implemented as a pointer type. The use of the (void *) type is
discouraged as it does not allow the compiler to perform strong
type-checking. However, the pointer type chosen should be of the
same size as the (void *) type. Provided this rule is obeyed, ABI
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specifications need not further constrain the implementation of
gss_name_t objects.
C.5. The int and size_t types
Some platforms may support differently sized implementations of the
"int" and "size_t" types, perhaps chosen through compiler switches,
and perhaps dependent on memory model. An ABI specification for such
a platform should include required implementations for these types.
It is recommended that the default implementation (for the chosen
memory model, if approriate) is chosen.
REFERENCES
[GSSAPI] J. Linn, "Generic Security Service Application Program
Interface, Version 2", Internet-Draft draft-ietf-cat-
gssv2-00, November 1994. (This Internet-Draft, like all
other Internet-Drafts, is not an archival document and is
subject to change or deletion. It is available at the
time of this writing by anonymous ftp from
ds.internic.net, directory internet-drafts. Would-be
readers should check for successor Internet-Draft
versions or Internet RFCs before relying on this
document.)
[XOM] OSI Object Management API Specification, Version 2.0 t",
X.400 API Association & X/Open Company Limited, August
24, 1990. Specification of datatypes and routines for
manipulating information objects.
AUTHOR'S ADDRESS
John Wray Internet email: Wray@tuxedo.enet.dec.com
Digital Equipment Corporation Telephone: +1-508-486-5210
550 King Street, LKG2-2/Z7
Littleton, MA 01460
USA
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