NAME
gss_accept_sec_context - API function
SYNOPSIS
#include <gss.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_buffer, const 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);
ARGUMENTS
OM_uint32 * minor_status
(Integer, modify) Mechanism specific status code.
gss_ctx_id_t * 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. Once
gss_accept_sec_context() has
returned a value via this parameter, resources have been
assigned
to the corresponding context, and must be freed by the
application after use with a call to
gss_delete_sec_context().
const gss_cred_id_t acceptor_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 default acceptor
principal is defined, GSS_S_NO_CRED will be returned.
const gss_buffer_t input_token_buffer
(buffer, opaque, read) Token obtained from
remote application.
const gss_channel_bindings_t 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.
gss_name_t * 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.
gss_OID * 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 (in
particular, it
does not need to be freed). If not required, specify
NULL.
gss_buffer_t 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.
If a
non- zero length field is returned, the associated
storage must
be freed after use by the application with a call to
gss_release_buffer().
OM_uint32 * 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. See below for the flags.
OM_uint32 * time_rec
(Integer, modify, optional) Number of seconds for which
the context will remain valid. Specify NULL if not
required.
gss_cred_id_t * 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, in
which case an explicit credential handle (i.e. not
GSS_C_NO_CREDENTIAL) will be returned; if deleg_flag is
false,
gss_accept_sec_context() will set this parameter to
GSS_C_NO_CREDENTIAL. If a credential handle is returned,
the
associated resources must be released by the application
after
use with a call to gss_release_cred(). Specify NULL if
not
required.
DESCRIPTION
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.
Portable applications should be constructed to use the token length and
return status to determine whether a token needs to be sent or waited
for. Thus 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 {
receive_token_from_peer(input_token);
maj_stat = gss_accept_sec_context(&min_stat,
&context_hdl,
cred_hdl,
input_token,
input_bindings,
&client_name,
&mech_type,
output_token,
&ret_flags,
&time_rec,
&deleg_cred);
if (GSS_ERROR(maj_stat)) {
report_error(maj_stat, min_stat);
};
if (output_token->length != 0) {
send_token_to_peer(output_token);
gss_release_buffer(&min_stat, output_token);
};
if (GSS_ERROR(maj_stat)) {
if (context_hdl != GSS_C_NO_CONTEXT)
gss_delete_sec_context(&min_stat,
&context_hdl,
GSS_C_NO_BUFFER);
break;
}; } while (maj_stat & GSS_S_CONTINUE_NEEDED);
---------------------------------------------------
Whenever the routine 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:
The value returned via the time_rec parameter is undefined Unless the
accompanying ret_flags parameter contains the bit
GSS_C_PROT_READY_FLAG, indicating that per-message services may be
applied in advance of a successful completion status, the value
returned via the mech_type parameter may be undefined until the routine
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 via
the ret_flags parameter should contain the values that the
implementation expects 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 should indicate the actual state at the time
gss_accept_sec_context returns, whether or not the context is fully
established.
Although this requires that GSS-API implementations set the
GSS_C_PROT_READY_FLAG in the final ret_flags returned to a caller (i.e.
when accompanied by a GSS_S_COMPLETE status code), applications should
not rely on this behavior as the 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,
according to the GSS_C_INTEG_FLAG and GSS_C_CONF_FLAG values.
All other bits within the ret_flags argument should be set to zero.
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.
If the initial call of gss_accept_sec_context() fails, the
implementation should not create a context object, and should leave the
value of the context_handle parameter set to GSS_C_NO_CONTEXT to
indicate this. In the event of a failure on a subsequent call, the
implementation is permitted to delete the "half-built" security context
(in which case it should set the context_handle parameter to
GSS_C_NO_CONTEXT), but the preferred behavior is to leave the security
context (and the context_handle parameter) untouched for the
application to delete (using gss_delete_sec_context).
During context establishment, the informational status bits
GSS_S_OLD_TOKEN and GSS_S_DUPLICATE_TOKEN indicate fatal errors, and
GSS-API mechanisms should always return them in association with a
routine error of GSS_S_FAILURE. This requirement for pairing 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.
The ‘ret_flags‘ values:
‘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. - 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.
‘GSS_C_PROT_READY_FLAG‘:: - True - Protection services (as specified by
the states of the 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. - False - Protection services (as specified
by the states of the GSS_C_CONF_FLAG and GSS_C_INTEG_FLAG) are
available only if the accompanying major status return value is
GSS_S_COMPLETE.
‘GSS_C_TRANS_FLAG‘:: - True - The resultant security context may be
transferred to other processes via a call to gss_export_sec_context().
- False - The security context is not transferable.
All other bits should be set to zero.
RETURN VALUE
‘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 MIC.
‘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.
REPORTING BUGS
Report bugs to <bug-gss@gnu.org>. GNU Generic Security Service home
page: http://www.gnu.org/software/gss/ General help using GNU software:
http://www.gnu.org/gethelp/
COPYRIGHT
Copyright © 2003-2010 Simon Josefsson.
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.
SEE ALSO
The full documentation for gss is maintained as a Texinfo manual. If
the info and gss programs are properly installed at your site, the
command
info gss
should give you access to the complete manual.