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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.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Red Hat, Inc., nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Declarations for preauth plugin module implementors.
*
* This header defines two preauth interfaces, clpreauth and kdcpreauth. A
* shared object can implement both interfaces or it can implement just one.
*
*
* The clpreauth interface has a single supported major version, which is
* 1. Major version 1 has a current minor version of 1. 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 kdcpreauth interface has a single supported major version, which is 1.
* Major version 1 has a current minor version of 1. kdcpreauth modules should
* define a function named kdcpreauth_<modulename>_initvt, matching the
* signature:
*
* krb5_error_code
* kdcpreauth_modname_initvt(krb5_context context, int maj_ver, int min_ver,
* krb5_plugin_vtable vtable);
*
* For both interfaces, 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:
* clpreauth, maj_ver == 1: Cast to krb5_clpreauth_vtable
* kdcpreauth, maj_ver == 1: Cast to krb5_kdcpreauth_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_PREAUTH_PLUGIN_H_INCLUDED
#define KRB5_PREAUTH_PLUGIN_H_INCLUDED
#include <krb5/krb5.h>
#include <krb5/plugin.h>
/*
* Preauth mechanism property flags, unified from previous definitions in the
* KDC and libkrb5 sources.
*/
/* Provides a real answer which we can send back to the KDC (client-only). 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 (client-only). */
#define PA_INFO 0x00000002
/*
* Causes the KDC to include this mechanism in a list of supported preauth
* types if the user's DB entry flags the user as requiring hardware-based
* preauthentication (KDC-only).
*/
#define PA_HARDWARE 0x00000004
/*
* Causes the KDC to include this mechanism in a list of supported preauth
* types if the user's DB entry flags the user as requiring preauthentication,
* and to fail preauthentication if we can't verify the client data. The
* flipside of PA_SUFFICIENT (KDC-only).
*/
#define PA_REQUIRED 0x00000008
/*
* Causes the KDC to include this mechanism in a list of supported preauth
* types if the user's DB entry flags the user as requiring preauthentication,
* and to mark preauthentication as successful if we can verify the client
* data. The flipside of PA_REQUIRED (KDC-only).
*/
#define PA_SUFFICIENT 0x00000010
/*
* Marks this preauthentication mechanism as one which changes the key which is
* used for encrypting the response to the client. Modules which have this
* flag have their server_return_fn called before modules which do not, and are
* passed over if a previously-called module has modified the encrypting key
* (KDC-only).
*/
#define PA_REPLACES_KEY 0x00000020
/*
* Not really a padata type, so don't include it in any list of preauth types
* which gets sent over the wire.
*/
#define PA_PSEUDO 0x00000080
/*
* For kdcpreauth mechanisms, indicates that e_data in non-FAST errors should
* be encoded as typed data instead of padata.
*/
#define PA_TYPED_E_DATA 0x00000100
/*
* clpreauth plugin interface definition.
*/
/* 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;
/*
* Get the enctype expected to be used to encrypt the encrypted portion of
* the AS_REP packet. When handling a PREAUTH_REQUIRED error, this
* typically comes from etype-info2. When handling an AS reply, it is
* initialized from the AS reply itself.
*/
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. */
} *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);
/*
* Mandatory: Return flags indicating if the module is a "real" or an "info"
* mechanism, and so on. This function is called for each entry in the
* client_pa_type_list.
*/
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);
/*
* 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_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);
/*
* kdcpreauth plugin interface definition.
*/
/* Abstract type for a KDC callback data handle. */
typedef struct krb5_kdcpreauth_rock_st *krb5_kdcpreauth_rock;
/* Abstract type for module data and per-request module data. */
typedef struct krb5_kdcpreauth_moddata_st *krb5_kdcpreauth_moddata;
typedef struct krb5_kdcpreauth_modreq_st *krb5_kdcpreauth_modreq;
/* The verto context structure type (typedef is in verto.h; we want to avoid a
* header dependency for the moment). */
struct verto_context;
/* Before using a callback after version 1, modules must check the vers
* field of the callback structure. */
typedef struct krb5_kdcpreauth_callbacks_st {
int vers;
krb5_deltat (*max_time_skew)(krb5_context context,
krb5_kdcpreauth_rock rock);
/*
* Get an array of krb5_keyblock structures containing the client keys
* matching the request enctypes, terminated by an entry with key type = 0.
* Returns ENOENT if no keys are available for the request enctypes. Free
* the resulting object with the free_keys callback.
*/
krb5_error_code (*client_keys)(krb5_context context,
krb5_kdcpreauth_rock rock,
krb5_keyblock **keys_out);
/* Free the result of client_keys. */
void (*free_keys)(krb5_context context, krb5_kdcpreauth_rock rock,
krb5_keyblock *keys);
/*
* Get the encoded request body, which is sometimes needed for checksums.
* For a FAST request this is the encoded inner request body. The returned
* pointer is an alias and should not be freed.
*/
krb5_data *(*request_body)(krb5_context context,
krb5_kdcpreauth_rock rock);
/* Get a pointer to the FAST armor key, or NULL if the request did not use
* FAST. The returned pointer is an alias and should not be freed. */
krb5_keyblock *(*fast_armor)(krb5_context context,
krb5_kdcpreauth_rock rock);
/* Retrieve a string attribute from the client DB entry, or NULL if no such
* attribute is set. Free the result with the free_string callback. */
krb5_error_code (*get_string)(krb5_context context,
krb5_kdcpreauth_rock rock, const char *key,
char **value_out);
/* Free the result of get_string. */
void (*free_string)(krb5_context context, krb5_kdcpreauth_rock rock,
char *string);
/* Get a pointer to the client DB entry (returned as a void pointer to
* avoid a dependency on a libkdb5 type). */
void *(*client_entry)(krb5_context context, krb5_kdcpreauth_rock rock);
/* Get a pointer to the verto context which should be used by an
* asynchronous edata or verify method. */
struct verto_ctx *(*event_context)(krb5_context context,
krb5_kdcpreauth_rock rock);
/* End of version 1 kdcpreauth callbacks. */
} *krb5_kdcpreauth_callbacks;
/* Optional: preauth plugin initialization function. */
typedef krb5_error_code
(*krb5_kdcpreauth_init_fn)(krb5_context context,
krb5_kdcpreauth_moddata *moddata_out,
const char **realmnames);
/* Optional: preauth plugin cleanup function. */
typedef void
(*krb5_kdcpreauth_fini_fn)(krb5_context context,
krb5_kdcpreauth_moddata moddata);
/*
* Optional: return the flags which the KDC should use for this module. This
* is a callback instead of a static value because the module may or may not
* wish to count itself as a hardware preauthentication module (in other words,
* the flags may be affected by the configuration, for example if a site
* administrator can force a particular preauthentication type to be supported
* using only hardware). This function is called for each entry entry in the
* server_pa_type_list.
*/
typedef int
(*krb5_kdcpreauth_flags_fn)(krb5_context context, krb5_preauthtype pa_type);
/*
* Responder for krb5_kdcpreauth_edata_fn. If invoked with a non-zero code, pa
* will be ignored and the padata type will not be included in the hint list.
* If invoked with a zero code and a null pa value, the padata type will be
* included in the list with an empty value. If invoked with a zero code and a
* non-null pa value, pa will be included in the hint list and will later be
* freed by the KDC.
*/
typedef void
(*krb5_kdcpreauth_edata_respond_fn)(void *arg, krb5_error_code code,
krb5_pa_data *pa);
/*
* Optional: provide pa_data to send to the client as part of the "you need to
* use preauthentication" error. The implementation must invoke the respond
* when complete, whether successful or not, either before returning or
* asynchronously using the verto context returned by cb->event_context().
*
* This function is not allowed to create a modreq object because we have no
* guarantee that the client will ever make a follow-up request, or that it
* will hit this KDC if it does.
*/
typedef void
(*krb5_kdcpreauth_edata_fn)(krb5_context context, krb5_kdc_req *request,
krb5_kdcpreauth_callbacks cb,
krb5_kdcpreauth_rock rock,
krb5_kdcpreauth_moddata moddata,
krb5_preauthtype pa_type,
krb5_kdcpreauth_edata_respond_fn respond,
void *arg);
/*
* Responder for krb5_kdcpreauth_verify_fn. Invoke with the arg parameter
* supplied to verify, the error code (0 for success), an optional module
* request state object to be consumed by return_fn or free_modreq_fn, optional
* e_data to be passed to the caller if code is nonzero, and optional
* authorization data to be included in the ticket. In non-FAST replies,
* e_data will be encoded as typed-data if the module sets the PA_TYPED_E_DATA
* flag, and as pa-data otherwise. e_data and authz_data will be freed by the
* KDC.
*/
typedef void
(*krb5_kdcpreauth_verify_respond_fn)(void *arg, krb5_error_code code,
krb5_kdcpreauth_modreq modreq,
krb5_pa_data **e_data,
krb5_authdata **authz_data);
/*
* Optional: verify preauthentication data sent by the client, setting the
* TKT_FLG_PRE_AUTH or TKT_FLG_HW_AUTH flag in the enc_tkt_reply's "flags"
* field as appropriate. The implementation must invoke the respond function
* when complete, whether successful or not, either before returning or
* asynchronously using the verto context returned by cb->event_context().
*/
typedef void
(*krb5_kdcpreauth_verify_fn)(krb5_context context,
krb5_data *req_pkt, krb5_kdc_req *request,
krb5_enc_tkt_part *enc_tkt_reply,
krb5_pa_data *data,
krb5_kdcpreauth_callbacks cb,
krb5_kdcpreauth_rock rock,
krb5_kdcpreauth_moddata moddata,
krb5_kdcpreauth_verify_respond_fn respond,
void *arg);
/*
* Optional: generate preauthentication response data to send to the client as
* part of the AS-REP. If it needs to override the key which is used to
* encrypt the response, it can do so.
*/
typedef krb5_error_code
(*krb5_kdcpreauth_return_fn)(krb5_context context,
krb5_pa_data *padata,
krb5_data *req_pkt,
krb5_kdc_req *request,
krb5_kdc_rep *reply,
krb5_keyblock *encrypting_key,
krb5_pa_data **send_pa_out,
krb5_kdcpreauth_callbacks cb,
krb5_kdcpreauth_rock rock,
krb5_kdcpreauth_moddata moddata,
krb5_kdcpreauth_modreq modreq);
/* Optional: free a per-request context. */
typedef void
(*krb5_kdcpreauth_free_modreq_fn)(krb5_context,
krb5_kdcpreauth_moddata moddata,
krb5_kdcpreauth_modreq modreq);
typedef struct krb5_kdcpreauth_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;
krb5_kdcpreauth_init_fn init;
krb5_kdcpreauth_fini_fn fini;
krb5_kdcpreauth_flags_fn flags;
krb5_kdcpreauth_edata_fn edata;
krb5_kdcpreauth_verify_fn verify;
krb5_kdcpreauth_return_fn return_padata;
krb5_kdcpreauth_free_modreq_fn free_modreq;
} *krb5_kdcpreauth_vtable;
#endif /* KRB5_PREAUTH_PLUGIN_H_INCLUDED */
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