The gss_acquire_cred() function allows an application to acquire a handle for a pre-existing credential by name. This routine is not intended as a function to login to the network; a function for login to the network would involve creating new credentials rather than merely acquiring a handle to existing credentials.

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(3GSS) (if cred_usage is GSS_C_INITIATE or GSS_C_BOTH) or gss_accept_sec_context(3GSS) (if cred_usage is GSS_C_ACCEPT or GSS_C_BOTH).

Normally gss_acquire_cred() returns a credential that is valid only for the mechanisms requested by the desired_mechs argument. However, if multiple mechanisms can share a single credential element, the function returns all the mechanisms for which the credential is valid in the actual_mechs argument.

gss_acquire_cred() is intended to be used primarily by context acceptors, since the GSS-API routines obtain initiator credentials through the system login process. Accordingly, you may not acquire GSS_C_INITIATE or GSS_C_BOTH credentials by means of gss_acquire_cred() for any name other than GSS_C_NO_NAME. Alternatively, you may acquire GSS_C_INITIATE or GSS_C_BOTH credentials for a name produced when gss_inquire_cred(3GSS) is applied to a valid credential, or when gss_inquire_context(3GSS) is applied 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, for example, by gss_init_sec_context(3GSS) or by gss_accept_sec_context(3GSS). Such mechanism-specific implementations are, however, invisible to the calling application; thus a call of gss_inquire_cred(3GSS) immediately following the call of gss_acquire_cred() will return valid credential data and incur the overhead of a deferred credential acquisition.

The parameter descriptions for gss_acquire_cred() follow:

desired_name

The name of the principal for which a credential should be acquired.

time_req

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

desired_mechs

The set of underlying security mechanisms that may be used. GSS_C_NO_OID_SET may be used to obtain a default.

cred_usage

A flag that indicates how this credential should be used. If the flag is GSS_C_ACCEPT, then credentials will be used only to accept security credentials. GSS_C_INITIATE indicates that credentials will be used only to initiate security credentials. If the flag is GSS_C_BOTH, then credentials may be used either to initiate or 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(3GSS)

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(3GSS). Specify NULL if not required.

time_rec

Actual number of seconds for which the returned credentials will remain valid. Specify NULL if not required.

minor_status

Mechanism specific status code.

gss_acquire_cred() may return the following status codes:

GSS_S_COMPLETE

Successful completion.

GSS_S_BAD_MECH

An unavailable mechanism has been requested.

GSS_S_BAD_NAMETYPE

The type contained within the desired_name parameter is not supported.

GSS_S_BAD_NAME

The 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.

GSS_S_FAILURE

The underlying mechanism detected an error for which no specific GSS status code is defined. The mechanism-specific status code reported by means of the minor_status parameter details the error condition.

See attributes(5) for descriptions of the following attributes:

gss_accept_sec_context(3GSS), gss_init_sec_context(3GSS), gss_inquire_context(3GSS), gss_inquire_cred(3GSS), gss_release_cred(3GSS), gss_release_oid_set(3GSS), attributes(5)

GSS-API Programming Guide