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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
* Copyright (c) 2006 Red Hat, Inc.
* Portions copyright (c) 2006, 2011 Massachusetts Institute of Technology
* All Rights Reserved.
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* the documentation and/or other materials provided with the
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* contributors may be used to endorse or promote products derived
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*
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/*
* Declarations for clpreauth plugin module implementors.
*
* The clpreauth interface has a single supported major version, which is
* 1. Major version 1 has a current minor version of 2. clpreauth modules
* should define a function named clpreauth_<modulename>_initvt, matching
* the signature:
*
* krb5_error_code
* clpreauth_modname_initvt(krb5_context context, int maj_ver,
* int min_ver, krb5_plugin_vtable vtable);
* The initvt function should:
*
* - Check that the supplied maj_ver number is supported by the module, or
* return KRB5_PLUGIN_VER_NOTSUPP if it is not.
*
* - Cast the vtable pointer as appropriate for the interface and maj_ver:
* maj_ver == 1: Cast to krb5_clpreauth_vtable
*
* - Initialize the methods of the vtable, stopping as appropriate for the
* supplied min_ver. Optional methods may be left uninitialized.
*
* Memory for the vtable is allocated by the caller, not by the module.
*/
#ifndef KRB5_CLPREAUTH_PLUGIN_H
#define KRB5_CLPREAUTH_PLUGIN_H
#include <krb5/krb5.h>
#include <krb5/plugin.h>
/* clpreauth mechanism property flags */
/* Provides a real answer which we can send back to the KDC. The client
* assumes that one real answer will be enough. */
#define PA_REAL 0x00000001
/* Doesn't provide a real answer, but must be given a chance to run before any
* REAL mechanism callbacks. */
#define PA_INFO 0x00000002
/* Abstract type for a client request information handle. */
typedef struct krb5_clpreauth_rock_st *krb5_clpreauth_rock;
/* Abstract types for module data and per-request module data. */
typedef struct krb5_clpreauth_moddata_st *krb5_clpreauth_moddata;
typedef struct krb5_clpreauth_modreq_st *krb5_clpreauth_modreq;
/* Before using a callback after version 1, modules must check the vers
* field of the callback structure. */
typedef struct krb5_clpreauth_callbacks_st {
int vers;
/*
* If an AS-REP has been received, return the enctype of the AS-REP
* encrypted part. Otherwise return the enctype chosen from etype-info, or
* the first requested enctype if no etype-info was received.
*/
krb5_enctype (*get_etype)(krb5_context context, krb5_clpreauth_rock rock);
/* Get a pointer to the FAST armor key, or NULL if the client is not using
* FAST. The returned pointer is an alias and should not be freed. */
krb5_keyblock *(*fast_armor)(krb5_context context,
krb5_clpreauth_rock rock);
/*
* Get a pointer to the client-supplied reply key, possibly invoking the
* prompter to ask for a password if this has not already been done. The
* returned pointer is an alias and should not be freed.
*/
krb5_error_code (*get_as_key)(krb5_context context,
krb5_clpreauth_rock rock,
krb5_keyblock **keyblock);
/* Replace the reply key to be used to decrypt the AS response. */
krb5_error_code (*set_as_key)(krb5_context context,
krb5_clpreauth_rock rock,
const krb5_keyblock *keyblock);
/* End of version 1 clpreauth callbacks. */
/*
* Get the current time for use in a preauth response. If
* allow_unauth_time is true and the library has been configured to allow
* it, the current time will be offset using unauthenticated timestamp
* information received from the KDC in the preauth-required error, if one
* has been received. Otherwise, the timestamp in a preauth-required error
* will only be used if it is protected by a FAST channel. Only set
* allow_unauth_time if using an unauthenticated time offset would not
* create a security issue.
*/
krb5_error_code (*get_preauth_time)(krb5_context context,
krb5_clpreauth_rock rock,
krb5_boolean allow_unauth_time,
krb5_timestamp *time_out,
krb5_int32 *usec_out);
/* Set a question to be answered by the responder and optionally provide
* a challenge. */
krb5_error_code (*ask_responder_question)(krb5_context context,
krb5_clpreauth_rock rock,
const char *question,
const char *challenge);
/* Get an answer from the responder, or NULL if the question was
* unanswered. */
const char *(*get_responder_answer)(krb5_context context,
krb5_clpreauth_rock rock,
const char *question);
/* Indicate interest in the AS key through the responder interface. */
void (*need_as_key)(krb5_context context, krb5_clpreauth_rock rock);
/*
* Get a configuration/state item from an input ccache, which may allow it
* to retrace the steps it took last time. The returned data string is an
* alias and should not be freed.
*/
const char *(*get_cc_config)(krb5_context context,
krb5_clpreauth_rock rock, const char *key);
/*
* Set a configuration/state item which will be recorded to an output
* ccache, if the calling application supplied one. Both key and data
* should be valid UTF-8 text.
*/
krb5_error_code (*set_cc_config)(krb5_context context,
krb5_clpreauth_rock rock,
const char *key, const char *data);
/* End of version 2 clpreauth callbacks (added in 1.11). */
/*
* Prevent further fallbacks to other preauth mechanisms if the KDC replies
* with an error. (The module itself can still respond to errors with its
* tryagain method, or continue after KDC_ERR_MORE_PREAUTH_DATA_REQUIRED
* errors with its process method.) A module should invoke this callback
* from the process method when it generates an authenticated request using
* credentials; often this will be the first or only client message
* generated by the mechanism.
*/
void (*disable_fallback)(krb5_context context, krb5_clpreauth_rock rock);
/* End of version 3 clpreauth callbacks (added in 1.17). */
} *krb5_clpreauth_callbacks;
/*
* Optional: per-plugin initialization/cleanup. The init function is called by
* libkrb5 when the plugin is loaded, and the fini function is called before
* the plugin is unloaded. These may be called multiple times in case the
* plugin is used in multiple contexts. The returned context lives the
* lifetime of the krb5_context.
*/
typedef krb5_error_code
(*krb5_clpreauth_init_fn)(krb5_context context,
krb5_clpreauth_moddata *moddata_out);
typedef void
(*krb5_clpreauth_fini_fn)(krb5_context context,
krb5_clpreauth_moddata moddata);
/*
* Optional (mandatory before MIT krb5 1.12): pa_type will be a member of the
* vtable's pa_type_list. Return PA_REAL if pa_type is a real
* preauthentication type or PA_INFO if it is an informational type. If this
* function is not defined in 1.12 or later, all pa_type values advertised by
* the module will be assumed to be real.
*/
typedef int
(*krb5_clpreauth_get_flags_fn)(krb5_context context, krb5_preauthtype pa_type);
/*
* Optional: per-request initialization/cleanup. The request_init function is
* called when beginning to process a get_init_creds request and the
* request_fini function is called when processing of the request is complete.
* This is optional. It may be called multiple times in the lifetime of a
* krb5_context.
*/
typedef void
(*krb5_clpreauth_request_init_fn)(krb5_context context,
krb5_clpreauth_moddata moddata,
krb5_clpreauth_modreq *modreq_out);
typedef void
(*krb5_clpreauth_request_fini_fn)(krb5_context context,
krb5_clpreauth_moddata moddata,
krb5_clpreauth_modreq modreq);
/*
* Optional: process server-supplied data in pa_data and set responder
* questions.
*
* encoded_previous_request may be NULL if there has been no previous request
* in the AS exchange.
*/
typedef krb5_error_code
(*krb5_clpreauth_prep_questions_fn)(krb5_context context,
krb5_clpreauth_moddata moddata,
krb5_clpreauth_modreq modreq,
krb5_get_init_creds_opt *opt,
krb5_clpreauth_callbacks cb,
krb5_clpreauth_rock rock,
krb5_kdc_req *request,
krb5_data *encoded_request_body,
krb5_data *encoded_previous_request,
krb5_pa_data *pa_data);
/*
* Mandatory: process server-supplied data in pa_data and return created data
* in pa_data_out. Also called after the AS-REP is received if the AS-REP
* includes preauthentication data of the associated type.
*
* as_key contains the client-supplied key if known, or an empty keyblock if
* not. If it is empty, the module may use gak_fct to fill it in.
*
* encoded_previous_request may be NULL if there has been no previous request
* in the AS exchange.
*/
typedef krb5_error_code
(*krb5_clpreauth_process_fn)(krb5_context context,
krb5_clpreauth_moddata moddata,
krb5_clpreauth_modreq modreq,
krb5_get_init_creds_opt *opt,
krb5_clpreauth_callbacks cb,
krb5_clpreauth_rock rock,
krb5_kdc_req *request,
krb5_data *encoded_request_body,
krb5_data *encoded_previous_request,
krb5_pa_data *pa_data,
krb5_prompter_fct prompter, void *prompter_data,
krb5_pa_data ***pa_data_out);
/*
* Optional: Attempt to use error and error_padata to try to recover from the
* given error. To work with both FAST and non-FAST errors, an implementation
* should generally consult error_padata rather than decoding error->e_data.
* For non-FAST errors, it contains the e_data decoded as either pa-data or
* typed-data.
*
* If this function is provided, and it returns 0 and stores data in
* pa_data_out, then the client library will retransmit the request.
*/
typedef krb5_error_code
(*krb5_clpreauth_tryagain_fn)(krb5_context context,
krb5_clpreauth_moddata moddata,
krb5_clpreauth_modreq modreq,
krb5_get_init_creds_opt *opt,
krb5_clpreauth_callbacks cb,
krb5_clpreauth_rock rock,
krb5_kdc_req *request,
krb5_data *encoded_request_body,
krb5_data *encoded_previous_request,
krb5_preauthtype pa_type,
krb5_error *error,
krb5_pa_data **error_padata,
krb5_prompter_fct prompter, void *prompter_data,
krb5_pa_data ***pa_data_out);
/*
* Optional: receive krb5_get_init_creds_opt information. The attr and value
* information supplied should be copied into moddata by the module if it
* wishes to reference it after returning from this call.
*/
typedef krb5_error_code
(*krb5_clpreauth_supply_gic_opts_fn)(krb5_context context,
krb5_clpreauth_moddata moddata,
krb5_get_init_creds_opt *opt,
const char *attr, const char *value);
typedef struct krb5_clpreauth_vtable_st {
/* Mandatory: name of module. */
char *name;
/* Mandatory: pointer to zero-terminated list of pa_types which this module
* can provide services for. */
krb5_preauthtype *pa_type_list;
/* Optional: pointer to zero-terminated list of enc_types which this module
* claims to add support for. */
krb5_enctype *enctype_list;
krb5_clpreauth_init_fn init;
krb5_clpreauth_fini_fn fini;
krb5_clpreauth_get_flags_fn flags;
krb5_clpreauth_request_init_fn request_init;
krb5_clpreauth_request_fini_fn request_fini;
krb5_clpreauth_process_fn process;
krb5_clpreauth_tryagain_fn tryagain;
krb5_clpreauth_supply_gic_opts_fn gic_opts;
/* Minor version 1 ends here. */
krb5_clpreauth_prep_questions_fn prep_questions;
/* Minor version 2 ends here. */
} *krb5_clpreauth_vtable;
/*
* This function allows a clpreauth plugin to obtain preauth options. The
* preauth_data returned from this function should be freed by calling
* krb5_get_init_creds_opt_free_pa().
*/
krb5_error_code KRB5_CALLCONV
krb5_get_init_creds_opt_get_pa(krb5_context context,
krb5_get_init_creds_opt *opt,
int *num_preauth_data,
krb5_gic_opt_pa_data **preauth_data);
/*
* This function frees the preauth_data that was returned by
* krb5_get_init_creds_opt_get_pa().
*/
void KRB5_CALLCONV
krb5_get_init_creds_opt_free_pa(krb5_context context,
int num_preauth_data,
krb5_gic_opt_pa_data *preauth_data);
#endif /* KRB5_CLPREAUTH_PLUGIN_H */
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