Content-type: text/html Man page of gss_accept_sec_context


Section: Generic Security Services API Library Functions (3GSS)
Updated: 22 May 2006
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gss_accept_sec_context - accept a security context initiated by a peer application  


cc [ flag... ] file... -lgss [ library... ]
#include <gssapi/gssapi.h>

OM_uint32 gss_accept_sec_context(OM_uint32 *minor_status,
    gss_ctx_id_t *context_handle,
    const gss_cred_id_t acceptor_cred_handle,
    const gss_buffer_t input_token,
    const gss_channel_bindings_t input_chan_bindings,
    const 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);



The parameter descriptions for gss_accept_sec_context() follow:


The status code returned by the underlying mechanism.


The context handle to return to the initiator. This should be set to GSS_C_NO_CONTEXT before the loop begins.


The handle for the credentials acquired by the acceptor, typically through gss_acquire_cred(). It may be initialized to GSS_C_NO_CREDENTIAL to indicate a default credential to use. If no default credential is defined, the function returns GSS_C_NO_CRED.


Token received from the context initiative.


Optional application-specified bindings. Allows application to securely bind channel identification information to the security context. Set to GSS_C_NO_CHANNEL_BINDINGS if you do not want to use channel bindings.


The authenticated name of the context initiator. After use, this name should be deallocated by passing it to gss_release_name(). See gss_release_name(3GSS). If not required, specify NULL.


The security mechanism used. Set to NULL if it does not matter which mechanism is used.


The token to send to the acceptor. Initialize it to GSS_C_NO_BUFFER before the function is called (or its length field set to zero). If the length is zero, no token need be sent.


Contains various independent flags, each of which indicates that the context supports a specific service option. If not needed, specify NULL. Test the returned bit-mask ret_flags value against its symbolic name to determine if the given option is supported by the context. ret_flags may contain one of the following values:


If true, delegated credentials are available by means of the delegated_cred_handle parameter. If false, no credentials were delegated.


If true, a remote peer asked for mutual authentication. If false, no remote peer asked for mutual authentication.


If true, replay of protected messages will be detected. If false, replayed messages will not be detected.


If true, out of sequence protected messages will be detected. If false, they will not be detected.


If true, confidentiality service may be invoked by calling the gss_wrap() routine. If false, no confidentiality service is available by means of gss_wrap(). gss_wrap() will provide message encapsulation, data-origin authentication and integrity services only.


If true, integrity service may be invoked by calling either the gss_get_mic(3GSS) or the gss_wrap(3GSS) routine. If false, per-message integrity service is not available.


If true, the initiator does not wish to be authenticated. The src_name parameter, if requested, contains an anonymous internal name. If false, the initiator has been authenticated normally.


If true, the protection services specified by the states of GSS_C_CONF_FLAG and GSS_C_INTEG_FLAG are available if the accompanying major status return value is either GSS_S_COMPLETE or GSS_S_CONTINUE_NEEDED. If false, the protection services are available only if the accompanying major status return value is GSS_S_COMPLETE.


If true, the resultant security context may be transferred to other processes by means of a call to gss_export_sec_context(3GSS). If false, the security context cannot be transferred.


The number of sections for which the context will remain value Specify NULL if not required.


The credential value for credentials received from the context's initiator. It is valid only if the initiator has requested that the acceptor act as a proxy: that is, if the ret_flag argument resolves to GSS_C_DELEG_FLAG.



The gss_accept_sec_context() function allows a remotely initiated security context between the application and a remote peer to be established. The routine may return an output_token, which should be transferred to the peer application, where the peer application will present it to gss_init_sec_context(). See gss_init_sec_context(3GSS). 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() by means of the input_token parameters.

Portable applications should be constructed to use the token length and return status to determine whether to send or to wait for a token.

Whenever gss_accept_sec_context() returns a major status that includes the value GSS_S_CONTINUE_NEEDED, the context is not fully established, and the following restrictions apply to the output parameters:

o The value returned by means of the time_rec parameter is undefined.
o Unless the accompanying ret_flags parameter contains the bit GSS_C_PROT_READY_FLAG, which indicates that per-message services may be applied in advance of a successful completion status, the value returned by the mech_type parameter may be undefined until gss_accept_sec_context() returns a major status value of GSS_S_COMPLETE.

The values of the GSS_C_DELEG_FLAG, GSS_C_MUTUAL_FLAG, GSS_C_REPLAY_FLAG, GSS_C_SEQUENCE_FLAG, GSS_C_CONF_FLAG, GSS_C_INTEG_FLAG and GSS_C_ANON_FLAG bits returned by means of the ret_flags parameter are values that would be valid if context establishment were to succeed.

The values of the GSS_C_PROT_READY_FLAG and GSS_C_TRANS_FLAG bits within ret_flags indicate the actual state at the time gss_accept_sec_context() returns, whether or not the context is fully established. However, applications should not rely on this behavior, as GSS_C_PROT_READY_FLAG was not defined in Version 1 of the GSS-API. Instead, applications should be prepared to use per-message services after a successful context establishment, based upon the GSS_C_INTEG_FLAG and GSS_C_CONF_FLAG values.

All other bits within the ret_flags argument are set to zero.

While gss_accept_sec_context() returns GSS_S_CONTINUE_NEEDED, the values returned by means of the the ret_flags argument indicate the services available from the established context. If the initial call of gss_accept_sec_context() fails, no context object is created, and the value of the context_handle parameter is set to GSS_C_NO_CONTEXT. In the event of a failure on a subsequent call, the security context and the context_handle parameter are left untouched for the application to delete using gss_delete_sec_context(3GSS). During context establishment, the informational status bits GSS_S_OLD_TOKEN and GSS_S_DUPLICATE_TOKEN indicate fatal errors; GSS-API mechanisms always return them in association with a routine error of GSS_S_FAILURE. This pairing requirement did not exist in version 1 of the GSS-API specification, so applications that wish to run over version 1 implementations must special-case these codes.  


gss_accept_sec_context() may return the following status codes:


Successful completion.


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.


Consistency checks performed on the input_token failed.


Consistency checks performed on the credential failed.


The supplied credentials were not valid for context acceptance, or the credential handle did not reference any credentials.


The referenced credentials have expired.


The input_token contains different channel bindings than those specified by means of the input_chan_bindings parameter.


The supplied context handle did not refer to a valid context.


The input_token contains an invalid MIC.


The input_token was too old. This is a fatal error while establishing context.


The input_token is valid, but it is duplicate of a token already processed. This is a fatal error while establishing context.


The token received specified a mechanism that is not supported by the implementation or the provided credential.


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.



Example 1 Invoking gss_accept_sec_context() Within a Loop

A typical portable caller should always invoke gss_accept_sec_context() within a loop:

gss_ctx_id_t context_hdl = GSS_C_NO_CONTEXT;

do {
  maj_stat = gss_accept_sec_context(&min_stat,
  if (GSS_ERROR(maj_stat)) {
     report_error(maj_stat, min_stat);
  if (output_token->length != 0) {
     gss_release_buffer(&min_stat, output_token);
  if (GSS_ERROR(maj_stat)) {
     if (context_hdl != GSS_C_NO_CONTEXT)
} while (maj_stat & GSS_S_CONTINUE_NEEDED);

/* Check client_name authorization */

(void) gss_release_name(&min_stat, &client_name);

/* Use and/or store delegated credential */

(void) gss_release_cred(&min_stat, &deleg_cred);



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





gss_delete_sec_context(3GSS), gss_export_sec_context(3GSS), gss_get_mic(3GSS), gss_init_sec_context(3GSS), gss_release_cred(3GSS), gss_release_name(3GSS), gss_store_cred(3GSS), gss_wrap(3GSS), attributes(5)




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Time: 02:38:32 GMT, October 02, 2010