NAME

gss_acquire_cred — Obtain a GSS-API credential handle for pre-existing credentials

SYNOPSIS

#include <gssapi/gssapi.h>

OM_uint32
gss_acquire_cred(OM_uint32 *minor_status, const gss_name_t desired_name, OM_uint32 time_req, const 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);

DESCRIPTION

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.

If desired_name is GSS_C_NO_NAME, the call is interpreted as a request for a credential handle that will invoke default behavior when passed to gss_init_sec_context() (if cred_usage is GSS_C_INITIATE or GSS_C_BOTH) or gss_accept_sec_context() (if cred_usage is GSS_C_ACCEPT or GSS_C_BOTH ).

Mechanisms should honor the desired_mechs parameter, and return a credential that is suitable to use only with the requested mechanisms. An exception to this is the case where one underlying credential element can be shared by multiple mechanisms; in this case it is permissible for an implementation to indicate all mechanisms with which the credential element may be used. If desired_mechs is an empty set, behavior is undefined.

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() for any name other than GSS_C_NO_NAME, or a name produced by applying either gss_inquire_cred() to a valid credential, or gss_inquire_context() to an active context.

If credential acquisition is time-consuming for a mechanism, the mechanism may choose 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

Name of principal whose credential should be acquired.

time_req

Number of seconds that credentials should remain valid. Specify GSS_C_INDEFINITE to request that the credentials have the maximum permitted lifetime.

desired_mechs

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_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

The returned credential handle. Resources associated with this credential handle must be released by the application after use with a call to gss_release_cred().

actual_mechs

The set of mechanisms for which the credential is valid. Storage associated with the returned OID-set must be released by the application after use with a call to gss_release_oid_set(). Specify NULL if not required.

time_rec

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

Mechanism specific status code.

RETURN VALUES

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.
GSS_S_CREDENTIALS_EXPIRED: The credentials could not be acquired because they have expired.
GSS_S_NO_CRED: No credentials were found for the specified name.

STANDARDS

RFC 2743: Generic Security Service Application Program Interface Version 2, Update 1
RFC 2744: Generic Security Service API Version 2 : C-bindings

HISTORY

The gss_acquire_cred function first appeared in FreeBSD 7.0.

AUTHORS

John Wray, Iris Associates

COPYRIGHT

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