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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
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* 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 kdcpreauth plugin module implementors.
*
* The kdcpreauth interface has a single supported major version, which is 1.
* Major version 1 has a current minor version of 3. 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);
*
* 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:
* 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_KDCPREAUTH_PLUGIN_H
#define KRB5_KDCPREAUTH_PLUGIN_H
#include <krb5/krb5.h>
#include <krb5/plugin.h>
/* kdcpreauth mechanism property flags */
/*
* 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.
*/
#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.
*/
#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.
*/
#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.
*/
#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
/*
* Indicates that e_data in non-FAST errors should be encoded as typed data
* instead of padata.
*/
#define PA_TYPED_E_DATA 0x00000100
/* 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_ctx;
/* 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. */
/* Return true if the client DB entry contains any keys matching the
* request enctypes. */
krb5_boolean (*have_client_keys)(krb5_context context,
krb5_kdcpreauth_rock rock);
/* End of version 2 kdcpreauth callbacks. */
/*
* Get the decrypted client long-term key chosen according to the request
* enctype list, or NULL if no matching key was found. The returned
* pointer is an alias and should not be freed. If invoked from
* return_padata, the result will be the same as the encrypting_key
* parameter if it is not NULL, and will therefore reflect the modified
* reply key if a return_padata handler has replaced the reply key.
*/
const krb5_keyblock *(*client_keyblock)(krb5_context context,
krb5_kdcpreauth_rock rock);
/* Assert an authentication indicator in the AS-REP authdata. Duplicate
* indicators will be ignored. */
krb5_error_code (*add_auth_indicator)(krb5_context context,
krb5_kdcpreauth_rock rock,
const char *indicator);
/*
* Read a data value for pa_type from the request cookie, placing it in
* *out. The value placed there is an alias and must not be freed.
* Returns true if a value for pa_type was retrieved, false if not.
*/
krb5_boolean (*get_cookie)(krb5_context context, krb5_kdcpreauth_rock rock,
krb5_preauthtype pa_type, krb5_data *out);
/*
* Set a data value for pa_type to be sent in a secure cookie in the next
* error response. If pa_type is already present, the value is ignored.
* If the preauth mechanism has different preauth types for requests and
* responses, use the request type. Secure cookies are encrypted in a key
* known only to the KDCs, but can be replayed within a short time window
* for requests using the same client principal.
*/
krb5_error_code (*set_cookie)(krb5_context context,
krb5_kdcpreauth_rock rock,
krb5_preauthtype pa_type,
const krb5_data *data);
/* End of version 3 kdcpreauth callbacks. */
/*
* Return true if princ matches the principal named in the request or the
* client principal (possibly canonicalized). If princ does not match,
* attempt a database lookup of princ with aliases allowed and compare the
* result to the client principal, returning true if it matches.
* Otherwise, return false.
*/
krb5_boolean (*match_client)(krb5_context context,
krb5_kdcpreauth_rock rock,
krb5_principal princ);
/*
* Get an alias to the client DB entry principal (possibly canonicalized).
*/
krb5_principal (*client_name)(krb5_context context,
krb5_kdcpreauth_rock rock);
/* End of version 4 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);
/* Optional: invoked after init_fn to provide the module with a pointer to the
* verto main loop. */
typedef krb5_error_code
(*krb5_kdcpreauth_loop_fn)(krb5_context context,
krb5_kdcpreauth_moddata moddata,
struct verto_ctx *ctx);
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;
/* Minor 1 ends here. */
krb5_kdcpreauth_loop_fn loop;
/* Minor 2 ends here. */
} *krb5_kdcpreauth_vtable;
#endif /* KRB5_KDCPREAUTH_PLUGIN_H */