xref: /freebsd/crypto/heimdal/lib/gssapi/krb5/accept_sec_context.c (revision b9f654b163bce26de79705e77b872427c9f2afa1)
1 /*
2  * Copyright (c) 1997 - 2006 Kungliga Tekniska Högskolan
3  * (Royal Institute of Technology, Stockholm, Sweden).
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  *
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  *
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * 3. Neither the name of the Institute nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #include "gsskrb5_locl.h"
35 
36 HEIMDAL_MUTEX gssapi_keytab_mutex = HEIMDAL_MUTEX_INITIALIZER;
37 krb5_keytab _gsskrb5_keytab;
38 
39 static krb5_error_code
40 validate_keytab(krb5_context context, const char *name, krb5_keytab *id)
41 {
42     krb5_error_code ret;
43 
44     ret = krb5_kt_resolve(context, name, id);
45     if (ret)
46 	return ret;
47 
48     ret = krb5_kt_have_content(context, *id);
49     if (ret) {
50 	krb5_kt_close(context, *id);
51 	*id = NULL;
52     }
53 
54     return ret;
55 }
56 
57 OM_uint32
58 _gsskrb5_register_acceptor_identity(OM_uint32 *min_stat, const char *identity)
59 {
60     krb5_context context;
61     krb5_error_code ret;
62 
63     *min_stat = 0;
64 
65     ret = _gsskrb5_init(&context);
66     if(ret)
67 	return GSS_S_FAILURE;
68 
69     HEIMDAL_MUTEX_lock(&gssapi_keytab_mutex);
70 
71     if(_gsskrb5_keytab != NULL) {
72 	krb5_kt_close(context, _gsskrb5_keytab);
73 	_gsskrb5_keytab = NULL;
74     }
75     if (identity == NULL) {
76 	ret = krb5_kt_default(context, &_gsskrb5_keytab);
77     } else {
78 	/*
79 	 * First check if we can the keytab as is and if it has content...
80 	 */
81 	ret = validate_keytab(context, identity, &_gsskrb5_keytab);
82 	/*
83 	 * if it doesn't, lets prepend FILE: and try again
84 	 */
85 	if (ret) {
86 	    char *p = NULL;
87 	    ret = asprintf(&p, "FILE:%s", identity);
88 	    if(ret < 0 || p == NULL) {
89 		HEIMDAL_MUTEX_unlock(&gssapi_keytab_mutex);
90 		return GSS_S_FAILURE;
91 	    }
92 	    ret = validate_keytab(context, p, &_gsskrb5_keytab);
93 	    free(p);
94 	}
95     }
96     HEIMDAL_MUTEX_unlock(&gssapi_keytab_mutex);
97     if(ret) {
98 	*min_stat = ret;
99 	return GSS_S_FAILURE;
100     }
101     return GSS_S_COMPLETE;
102 }
103 
104 void
105 _gsskrb5i_is_cfx(krb5_context context, gsskrb5_ctx ctx, int acceptor)
106 {
107     krb5_error_code ret;
108     krb5_keyblock *key;
109 
110     if (acceptor) {
111 	if (ctx->auth_context->local_subkey)
112 	    key = ctx->auth_context->local_subkey;
113 	else
114 	    key = ctx->auth_context->remote_subkey;
115     } else {
116 	if (ctx->auth_context->remote_subkey)
117 	    key = ctx->auth_context->remote_subkey;
118 	else
119 	    key = ctx->auth_context->local_subkey;
120     }
121     if (key == NULL)
122 	key = ctx->auth_context->keyblock;
123 
124     if (key == NULL)
125 	return;
126 
127     switch (key->keytype) {
128     case ETYPE_DES_CBC_CRC:
129     case ETYPE_DES_CBC_MD4:
130     case ETYPE_DES_CBC_MD5:
131     case ETYPE_DES3_CBC_MD5:
132     case ETYPE_OLD_DES3_CBC_SHA1:
133     case ETYPE_DES3_CBC_SHA1:
134     case ETYPE_ARCFOUR_HMAC_MD5:
135     case ETYPE_ARCFOUR_HMAC_MD5_56:
136 	break;
137     default :
138         ctx->more_flags |= IS_CFX;
139 
140 	if ((acceptor && ctx->auth_context->local_subkey) ||
141 	    (!acceptor && ctx->auth_context->remote_subkey))
142 	    ctx->more_flags |= ACCEPTOR_SUBKEY;
143 	break;
144     }
145     if (ctx->crypto)
146         krb5_crypto_destroy(context, ctx->crypto);
147     ret = krb5_crypto_init(context, key, 0, &ctx->crypto);
148 }
149 
150 
151 static OM_uint32
152 gsskrb5_accept_delegated_token
153 (OM_uint32 * minor_status,
154  gsskrb5_ctx ctx,
155  krb5_context context,
156  gss_cred_id_t * delegated_cred_handle
157     )
158 {
159     krb5_ccache ccache = NULL;
160     krb5_error_code kret;
161     int32_t ac_flags, ret = GSS_S_COMPLETE;
162 
163     *minor_status = 0;
164 
165     /* XXX Create a new delegated_cred_handle? */
166     if (delegated_cred_handle == NULL) {
167 	kret = krb5_cc_default (context, &ccache);
168     } else {
169 	*delegated_cred_handle = NULL;
170 	kret = krb5_cc_new_unique (context, krb5_cc_type_memory,
171 				   NULL, &ccache);
172     }
173     if (kret) {
174 	ctx->flags &= ~GSS_C_DELEG_FLAG;
175 	goto out;
176     }
177 
178     kret = krb5_cc_initialize(context, ccache, ctx->source);
179     if (kret) {
180 	ctx->flags &= ~GSS_C_DELEG_FLAG;
181 	goto out;
182     }
183 
184     krb5_auth_con_removeflags(context,
185 			      ctx->auth_context,
186 			      KRB5_AUTH_CONTEXT_DO_TIME,
187 			      &ac_flags);
188     kret = krb5_rd_cred2(context,
189 			 ctx->auth_context,
190 			 ccache,
191 			 &ctx->fwd_data);
192     krb5_auth_con_setflags(context,
193 			   ctx->auth_context,
194 			   ac_flags);
195     if (kret) {
196 	ctx->flags &= ~GSS_C_DELEG_FLAG;
197 	ret = GSS_S_FAILURE;
198 	*minor_status = kret;
199 	goto out;
200     }
201 
202     if (delegated_cred_handle) {
203 	gsskrb5_cred handle;
204 
205 	ret = _gsskrb5_krb5_import_cred(minor_status,
206 					ccache,
207 					NULL,
208 					NULL,
209 					delegated_cred_handle);
210 	if (ret != GSS_S_COMPLETE)
211 	    goto out;
212 
213 	handle = (gsskrb5_cred) *delegated_cred_handle;
214 
215 	handle->cred_flags |= GSS_CF_DESTROY_CRED_ON_RELEASE;
216 	krb5_cc_close(context, ccache);
217 	ccache = NULL;
218     }
219 
220 out:
221     if (ccache) {
222 	/* Don't destroy the default cred cache */
223 	if (delegated_cred_handle == NULL)
224 	    krb5_cc_close(context, ccache);
225 	else
226 	    krb5_cc_destroy(context, ccache);
227     }
228     return ret;
229 }
230 
231 static OM_uint32
232 gsskrb5_acceptor_ready(OM_uint32 * minor_status,
233 		       gsskrb5_ctx ctx,
234 		       krb5_context context,
235 		       gss_cred_id_t *delegated_cred_handle)
236 {
237     OM_uint32 ret;
238     int32_t seq_number;
239     int is_cfx = 0;
240 
241     krb5_auth_con_getremoteseqnumber (context,
242 				      ctx->auth_context,
243 				      &seq_number);
244 
245     _gsskrb5i_is_cfx(context, ctx, 1);
246     is_cfx = (ctx->more_flags & IS_CFX);
247 
248     ret = _gssapi_msg_order_create(minor_status,
249 				   &ctx->order,
250 				   _gssapi_msg_order_f(ctx->flags),
251 				   seq_number, 0, is_cfx);
252     if (ret)
253 	return ret;
254 
255     /*
256      * If requested, set local sequence num to remote sequence if this
257      * isn't a mutual authentication context
258      */
259     if (!(ctx->flags & GSS_C_MUTUAL_FLAG) && _gssapi_msg_order_f(ctx->flags)) {
260 	krb5_auth_con_setlocalseqnumber(context,
261 					ctx->auth_context,
262 					seq_number);
263     }
264 
265     /*
266      * We should handle the delegation ticket, in case it's there
267      */
268     if (ctx->fwd_data.length > 0 && (ctx->flags & GSS_C_DELEG_FLAG)) {
269 	ret = gsskrb5_accept_delegated_token(minor_status,
270 					     ctx,
271 					     context,
272 					     delegated_cred_handle);
273 	if (ret)
274 	    return ret;
275     } else {
276 	/* Well, looks like it wasn't there after all */
277 	ctx->flags &= ~GSS_C_DELEG_FLAG;
278     }
279 
280     ctx->state = ACCEPTOR_READY;
281     ctx->more_flags |= OPEN;
282 
283     return GSS_S_COMPLETE;
284 }
285 
286 static OM_uint32
287 send_error_token(OM_uint32 *minor_status,
288 		 krb5_context context,
289 		 krb5_error_code kret,
290 		 krb5_principal server,
291 		 krb5_data *indata,
292 		 gss_buffer_t output_token)
293 {
294     krb5_principal ap_req_server = NULL;
295     krb5_error_code ret;
296     krb5_data outbuf;
297     /* this e_data value encodes KERB_AP_ERR_TYPE_SKEW_RECOVERY which
298        tells windows to try again with the corrected timestamp. See
299        [MS-KILE] 2.2.1 KERB-ERROR-DATA */
300     krb5_data e_data = { 7, rk_UNCONST("\x30\x05\xa1\x03\x02\x01\x02") };
301 
302     /* build server from request if the acceptor had not selected one */
303     if (server == NULL) {
304 	AP_REQ ap_req;
305 
306 	ret = krb5_decode_ap_req(context, indata, &ap_req);
307 	if (ret) {
308 	    *minor_status = ret;
309 	    return GSS_S_FAILURE;
310 	}
311 	ret = _krb5_principalname2krb5_principal(context,
312 						  &ap_req_server,
313 						  ap_req.ticket.sname,
314 						  ap_req.ticket.realm);
315 	free_AP_REQ(&ap_req);
316 	if (ret) {
317 	    *minor_status = ret;
318 	    return GSS_S_FAILURE;
319 	}
320 	server = ap_req_server;
321     }
322 
323     ret = krb5_mk_error(context, kret, NULL, &e_data, NULL,
324 			server, NULL, NULL, &outbuf);
325     if (ap_req_server)
326 	krb5_free_principal(context, ap_req_server);
327     if (ret) {
328 	*minor_status = ret;
329 	return GSS_S_FAILURE;
330     }
331 
332     ret = _gsskrb5_encapsulate(minor_status,
333 			       &outbuf,
334 			       output_token,
335 			       "\x03\x00",
336 			       GSS_KRB5_MECHANISM);
337     krb5_data_free (&outbuf);
338     if (ret)
339 	return ret;
340 
341     *minor_status = 0;
342     return GSS_S_CONTINUE_NEEDED;
343 }
344 
345 
346 static OM_uint32
347 gsskrb5_acceptor_start(OM_uint32 * minor_status,
348 		       gsskrb5_ctx ctx,
349 		       krb5_context context,
350 		       const gss_cred_id_t acceptor_cred_handle,
351 		       const gss_buffer_t input_token_buffer,
352 		       const gss_channel_bindings_t input_chan_bindings,
353 		       gss_name_t * src_name,
354 		       gss_OID * mech_type,
355 		       gss_buffer_t output_token,
356 		       OM_uint32 * ret_flags,
357 		       OM_uint32 * time_rec,
358 		       gss_cred_id_t * delegated_cred_handle)
359 {
360     krb5_error_code kret;
361     OM_uint32 ret = GSS_S_COMPLETE;
362     krb5_data indata;
363     krb5_flags ap_options;
364     krb5_keytab keytab = NULL;
365     int is_cfx = 0;
366     const gsskrb5_cred acceptor_cred = (gsskrb5_cred)acceptor_cred_handle;
367 
368     /*
369      * We may, or may not, have an escapsulation.
370      */
371     ret = _gsskrb5_decapsulate (minor_status,
372 				input_token_buffer,
373 				&indata,
374 				"\x01\x00",
375 				GSS_KRB5_MECHANISM);
376 
377     if (ret) {
378 	/* Assume that there is no OID wrapping. */
379 	indata.length	= input_token_buffer->length;
380 	indata.data	= input_token_buffer->value;
381     }
382 
383     /*
384      * We need to get our keytab
385      */
386     if (acceptor_cred == NULL) {
387 	if (_gsskrb5_keytab != NULL)
388 	    keytab = _gsskrb5_keytab;
389     } else if (acceptor_cred->keytab != NULL) {
390 	keytab = acceptor_cred->keytab;
391     }
392 
393     /*
394      * We need to check the ticket and create the AP-REP packet
395      */
396 
397     {
398 	krb5_rd_req_in_ctx in = NULL;
399 	krb5_rd_req_out_ctx out = NULL;
400 	krb5_principal server = NULL;
401 
402 	if (acceptor_cred)
403 	    server = acceptor_cred->principal;
404 
405 	kret = krb5_rd_req_in_ctx_alloc(context, &in);
406 	if (kret == 0)
407 	    kret = krb5_rd_req_in_set_keytab(context, in, keytab);
408 	if (kret) {
409 	    if (in)
410 		krb5_rd_req_in_ctx_free(context, in);
411 	    *minor_status = kret;
412 	    return GSS_S_FAILURE;
413 	}
414 
415 	kret = krb5_rd_req_ctx(context,
416 			       &ctx->auth_context,
417 			       &indata,
418 			       server,
419 			       in, &out);
420 	krb5_rd_req_in_ctx_free(context, in);
421 	if (kret == KRB5KRB_AP_ERR_SKEW || kret == KRB5KRB_AP_ERR_TKT_NYV) {
422 	    /*
423 	     * No reply in non-MUTUAL mode, but we don't know that its
424 	     * non-MUTUAL mode yet, thats inside the 8003 checksum, so
425 	     * lets only send the error token on clock skew, that
426 	     * limit when send error token for non-MUTUAL.
427 	     */
428 	    return send_error_token(minor_status, context, kret,
429 				    server, &indata, output_token);
430 	} else if (kret) {
431 	    *minor_status = kret;
432 	    return GSS_S_FAILURE;
433 	}
434 
435 	/*
436 	 * we need to remember some data on the context_handle.
437 	 */
438 	kret = krb5_rd_req_out_get_ap_req_options(context, out,
439 						  &ap_options);
440 	if (kret == 0)
441 	    kret = krb5_rd_req_out_get_ticket(context, out,
442 					      &ctx->ticket);
443 	if (kret == 0)
444 	    kret = krb5_rd_req_out_get_keyblock(context, out,
445 						&ctx->service_keyblock);
446 	ctx->lifetime = ctx->ticket->ticket.endtime;
447 
448 	krb5_rd_req_out_ctx_free(context, out);
449 	if (kret) {
450 	    ret = GSS_S_FAILURE;
451 	    *minor_status = kret;
452 	    return ret;
453 	}
454     }
455 
456 
457     /*
458      * We need to copy the principal names to the context and the
459      * calling layer.
460      */
461     kret = krb5_copy_principal(context,
462 			       ctx->ticket->client,
463 			       &ctx->source);
464     if (kret) {
465 	ret = GSS_S_FAILURE;
466 	*minor_status = kret;
467     }
468 
469     kret = krb5_copy_principal(context,
470 			       ctx->ticket->server,
471 			       &ctx->target);
472     if (kret) {
473 	ret = GSS_S_FAILURE;
474 	*minor_status = kret;
475 	return ret;
476     }
477 
478     /*
479      * We need to setup some compat stuff, this assumes that
480      * context_handle->target is already set.
481      */
482     ret = _gss_DES3_get_mic_compat(minor_status, ctx, context);
483     if (ret)
484 	return ret;
485 
486     if (src_name != NULL) {
487 	kret = krb5_copy_principal (context,
488 				    ctx->ticket->client,
489 				    (gsskrb5_name*)src_name);
490 	if (kret) {
491 	    ret = GSS_S_FAILURE;
492 	    *minor_status = kret;
493 	    return ret;
494 	}
495     }
496 
497     /*
498      * We need to get the flags out of the 8003 checksum.
499      */
500 
501     {
502 	krb5_authenticator authenticator;
503 
504 	kret = krb5_auth_con_getauthenticator(context,
505 					      ctx->auth_context,
506 					      &authenticator);
507 	if(kret) {
508 	    ret = GSS_S_FAILURE;
509 	    *minor_status = kret;
510 	    return ret;
511 	}
512 
513 	if (authenticator->cksum == NULL) {
514 	    krb5_free_authenticator(context, &authenticator);
515 	    *minor_status = 0;
516 	    return GSS_S_BAD_BINDINGS;
517 	}
518 
519         if (authenticator->cksum->cksumtype == CKSUMTYPE_GSSAPI) {
520             ret = _gsskrb5_verify_8003_checksum(minor_status,
521 						input_chan_bindings,
522 						authenticator->cksum,
523 						&ctx->flags,
524 						&ctx->fwd_data);
525 
526 	    krb5_free_authenticator(context, &authenticator);
527 	    if (ret) {
528 		return ret;
529 	    }
530         } else {
531 	    krb5_crypto crypto;
532 
533 	    kret = krb5_crypto_init(context,
534 				    ctx->auth_context->keyblock,
535 				    0, &crypto);
536 	    if(kret) {
537 		krb5_free_authenticator(context, &authenticator);
538 
539 		ret = GSS_S_FAILURE;
540 		*minor_status = kret;
541 		return ret;
542 	    }
543 
544 	    /*
545 	     * Windows accepts Samba3's use of a kerberos, rather than
546 	     * GSSAPI checksum here
547 	     */
548 
549 	    kret = krb5_verify_checksum(context,
550 					crypto, KRB5_KU_AP_REQ_AUTH_CKSUM, NULL, 0,
551 					authenticator->cksum);
552 	    krb5_free_authenticator(context, &authenticator);
553 	    krb5_crypto_destroy(context, crypto);
554 
555 	    if(kret) {
556 		ret = GSS_S_BAD_SIG;
557 		*minor_status = kret;
558 		return ret;
559 	    }
560 
561 	    /*
562 	     * Samba style get some flags (but not DCE-STYLE), use
563 	     * ap_options to guess the mutual flag.
564 	     */
565  	    ctx->flags = GSS_C_REPLAY_FLAG | GSS_C_SEQUENCE_FLAG;
566 	    if (ap_options & AP_OPTS_MUTUAL_REQUIRED)
567 		ctx->flags |= GSS_C_MUTUAL_FLAG;
568         }
569     }
570 
571     if(ctx->flags & GSS_C_MUTUAL_FLAG) {
572 	krb5_data outbuf;
573 	int use_subkey = 0;
574 
575 	_gsskrb5i_is_cfx(context, ctx, 1);
576 	is_cfx = (ctx->more_flags & IS_CFX);
577 
578 	if (is_cfx || (ap_options & AP_OPTS_USE_SUBKEY)) {
579 	    use_subkey = 1;
580 	} else {
581 	    krb5_keyblock *rkey;
582 
583 	    /*
584 	     * If there is a initiator subkey, copy that to acceptor
585 	     * subkey to match Windows behavior
586 	     */
587 	    kret = krb5_auth_con_getremotesubkey(context,
588 						 ctx->auth_context,
589 						 &rkey);
590 	    if (kret == 0) {
591 		kret = krb5_auth_con_setlocalsubkey(context,
592 						    ctx->auth_context,
593 						    rkey);
594 		if (kret == 0)
595 		    use_subkey = 1;
596 		krb5_free_keyblock(context, rkey);
597 	    }
598 	}
599 	if (use_subkey) {
600 	    ctx->more_flags |= ACCEPTOR_SUBKEY;
601 	    krb5_auth_con_addflags(context, ctx->auth_context,
602 				   KRB5_AUTH_CONTEXT_USE_SUBKEY,
603 				   NULL);
604 	}
605 
606 	kret = krb5_mk_rep(context,
607 			   ctx->auth_context,
608 			   &outbuf);
609 	if (kret) {
610 	    *minor_status = kret;
611 	    return GSS_S_FAILURE;
612 	}
613 
614 	if (IS_DCE_STYLE(ctx)) {
615 	    output_token->length = outbuf.length;
616 	    output_token->value = outbuf.data;
617 	} else {
618 	    ret = _gsskrb5_encapsulate(minor_status,
619 				       &outbuf,
620 				       output_token,
621 				       "\x02\x00",
622 				       GSS_KRB5_MECHANISM);
623 	    krb5_data_free (&outbuf);
624 	    if (ret)
625 		return ret;
626 	}
627     }
628 
629     ctx->flags |= GSS_C_TRANS_FLAG;
630 
631     /* Remember the flags */
632 
633     ctx->lifetime = ctx->ticket->ticket.endtime;
634     ctx->more_flags |= OPEN;
635 
636     if (mech_type)
637 	*mech_type = GSS_KRB5_MECHANISM;
638 
639     if (time_rec) {
640 	ret = _gsskrb5_lifetime_left(minor_status,
641 				     context,
642 				     ctx->lifetime,
643 				     time_rec);
644 	if (ret) {
645 	    return ret;
646 	}
647     }
648 
649     /*
650      * When GSS_C_DCE_STYLE is in use, we need ask for a AP-REP from
651      * the client.
652      */
653     if (IS_DCE_STYLE(ctx)) {
654 	/*
655 	 * Return flags to caller, but we haven't processed
656 	 * delgations yet
657 	 */
658 	if (ret_flags)
659 	    *ret_flags = (ctx->flags & ~GSS_C_DELEG_FLAG);
660 
661 	ctx->state = ACCEPTOR_WAIT_FOR_DCESTYLE;
662 	return GSS_S_CONTINUE_NEEDED;
663     }
664 
665     ret = gsskrb5_acceptor_ready(minor_status, ctx, context,
666 				 delegated_cred_handle);
667 
668     if (ret_flags)
669 	*ret_flags = ctx->flags;
670 
671     return ret;
672 }
673 
674 static OM_uint32
675 acceptor_wait_for_dcestyle(OM_uint32 * minor_status,
676 			   gsskrb5_ctx ctx,
677 			   krb5_context context,
678 			   const gss_cred_id_t acceptor_cred_handle,
679 			   const gss_buffer_t input_token_buffer,
680 			   const gss_channel_bindings_t input_chan_bindings,
681 			   gss_name_t * src_name,
682 			   gss_OID * mech_type,
683 			   gss_buffer_t output_token,
684 			   OM_uint32 * ret_flags,
685 			   OM_uint32 * time_rec,
686 			   gss_cred_id_t * delegated_cred_handle)
687 {
688     OM_uint32 ret;
689     krb5_error_code kret;
690     krb5_data inbuf;
691     int32_t r_seq_number, l_seq_number;
692 
693     /*
694      * We know it's GSS_C_DCE_STYLE so we don't need to decapsulate the AP_REP
695      */
696 
697     inbuf.length = input_token_buffer->length;
698     inbuf.data = input_token_buffer->value;
699 
700     /*
701      * We need to remeber the old remote seq_number, then check if the
702      * client has replied with our local seq_number, and then reset
703      * the remote seq_number to the old value
704      */
705     {
706 	kret = krb5_auth_con_getlocalseqnumber(context,
707 					       ctx->auth_context,
708 					       &l_seq_number);
709 	if (kret) {
710 	    *minor_status = kret;
711 	    return GSS_S_FAILURE;
712 	}
713 
714 	kret = krb5_auth_con_getremoteseqnumber(context,
715 						ctx->auth_context,
716 						&r_seq_number);
717 	if (kret) {
718 	    *minor_status = kret;
719 	    return GSS_S_FAILURE;
720 	}
721 
722 	kret = krb5_auth_con_setremoteseqnumber(context,
723 						ctx->auth_context,
724 						l_seq_number);
725 	if (kret) {
726 	    *minor_status = kret;
727 	    return GSS_S_FAILURE;
728 	}
729     }
730 
731     /*
732      * We need to verify the AP_REP, but we need to flag that this is
733      * DCE_STYLE, so don't check the timestamps this time, but put the
734      * flag DO_TIME back afterward.
735     */
736     {
737 	krb5_ap_rep_enc_part *repl;
738 	int32_t auth_flags;
739 
740 	krb5_auth_con_removeflags(context,
741 				  ctx->auth_context,
742 				  KRB5_AUTH_CONTEXT_DO_TIME,
743 				  &auth_flags);
744 
745 	kret = krb5_rd_rep(context, ctx->auth_context, &inbuf, &repl);
746 	if (kret) {
747 	    *minor_status = kret;
748 	    return GSS_S_FAILURE;
749 	}
750 	krb5_free_ap_rep_enc_part(context, repl);
751 	krb5_auth_con_setflags(context, ctx->auth_context, auth_flags);
752     }
753 
754     /* We need to check the liftime */
755     {
756 	OM_uint32 lifetime_rec;
757 
758 	ret = _gsskrb5_lifetime_left(minor_status,
759 				     context,
760 				     ctx->lifetime,
761 				     &lifetime_rec);
762 	if (ret) {
763 	    return ret;
764 	}
765 	if (lifetime_rec == 0) {
766 	    return GSS_S_CONTEXT_EXPIRED;
767 	}
768 
769 	if (time_rec) *time_rec = lifetime_rec;
770     }
771 
772     /* We need to give the caller the flags which are in use */
773     if (ret_flags) *ret_flags = ctx->flags;
774 
775     if (src_name) {
776 	kret = krb5_copy_principal(context,
777 				   ctx->source,
778 				   (gsskrb5_name*)src_name);
779 	if (kret) {
780 	    *minor_status = kret;
781 	    return GSS_S_FAILURE;
782 	}
783     }
784 
785     /*
786      * After the krb5_rd_rep() the remote and local seq_number should
787      * be the same, because the client just replies the seq_number
788      * from our AP-REP in its AP-REP, but then the client uses the
789      * seq_number from its AP-REQ for GSS_wrap()
790      */
791     {
792 	int32_t tmp_r_seq_number, tmp_l_seq_number;
793 
794 	kret = krb5_auth_con_getremoteseqnumber(context,
795 						ctx->auth_context,
796 						&tmp_r_seq_number);
797 	if (kret) {
798 	    *minor_status = kret;
799 	    return GSS_S_FAILURE;
800 	}
801 
802 	kret = krb5_auth_con_getlocalseqnumber(context,
803 					       ctx->auth_context,
804 					       &tmp_l_seq_number);
805 	if (kret) {
806 
807 	    *minor_status = kret;
808 	    return GSS_S_FAILURE;
809 	}
810 
811 	/*
812 	 * Here we check if the client has responsed with our local seq_number,
813 	 */
814 	if (tmp_r_seq_number != tmp_l_seq_number) {
815 	    return GSS_S_UNSEQ_TOKEN;
816 	}
817     }
818 
819     /*
820      * We need to reset the remote seq_number, because the client will use,
821      * the old one for the GSS_wrap() calls
822      */
823     {
824 	kret = krb5_auth_con_setremoteseqnumber(context,
825 						ctx->auth_context,
826 						r_seq_number);
827 	if (kret) {
828 	    *minor_status = kret;
829 	    return GSS_S_FAILURE;
830 	}
831     }
832 
833     return gsskrb5_acceptor_ready(minor_status, ctx, context,
834 				  delegated_cred_handle);
835 }
836 
837 
838 OM_uint32 GSSAPI_CALLCONV
839 _gsskrb5_accept_sec_context(OM_uint32 * minor_status,
840 			    gss_ctx_id_t * context_handle,
841 			    const gss_cred_id_t acceptor_cred_handle,
842 			    const gss_buffer_t input_token_buffer,
843 			    const gss_channel_bindings_t input_chan_bindings,
844 			    gss_name_t * src_name,
845 			    gss_OID * mech_type,
846 			    gss_buffer_t output_token,
847 			    OM_uint32 * ret_flags,
848 			    OM_uint32 * time_rec,
849 			    gss_cred_id_t * delegated_cred_handle)
850 {
851     krb5_context context;
852     OM_uint32 ret;
853     gsskrb5_ctx ctx;
854 
855     GSSAPI_KRB5_INIT(&context);
856 
857     output_token->length = 0;
858     output_token->value = NULL;
859 
860     if (src_name != NULL)
861 	*src_name = NULL;
862     if (mech_type)
863 	*mech_type = GSS_KRB5_MECHANISM;
864 
865     if (*context_handle == GSS_C_NO_CONTEXT) {
866 	ret = _gsskrb5_create_ctx(minor_status,
867 				  context_handle,
868 				  context,
869 				  input_chan_bindings,
870 				  ACCEPTOR_START);
871 	if (ret)
872 	    return ret;
873     }
874 
875     ctx = (gsskrb5_ctx)*context_handle;
876 
877 
878     /*
879      * TODO: check the channel_bindings
880      * (above just sets them to krb5 layer)
881      */
882 
883     HEIMDAL_MUTEX_lock(&ctx->ctx_id_mutex);
884 
885     switch (ctx->state) {
886     case ACCEPTOR_START:
887 	ret = gsskrb5_acceptor_start(minor_status,
888 				     ctx,
889 				     context,
890 				     acceptor_cred_handle,
891 				     input_token_buffer,
892 				     input_chan_bindings,
893 				     src_name,
894 				     mech_type,
895 				     output_token,
896 				     ret_flags,
897 				     time_rec,
898 				     delegated_cred_handle);
899 	break;
900     case ACCEPTOR_WAIT_FOR_DCESTYLE:
901 	ret = acceptor_wait_for_dcestyle(minor_status,
902 					 ctx,
903 					 context,
904 					 acceptor_cred_handle,
905 					 input_token_buffer,
906 					 input_chan_bindings,
907 					 src_name,
908 					 mech_type,
909 					 output_token,
910 					 ret_flags,
911 					 time_rec,
912 					 delegated_cred_handle);
913 	break;
914     case ACCEPTOR_READY:
915 	/*
916 	 * If we get there, the caller have called
917 	 * gss_accept_sec_context() one time too many.
918 	 */
919 	ret =  GSS_S_BAD_STATUS;
920 	break;
921     default:
922 	/* TODO: is this correct here? --metze */
923 	ret =  GSS_S_BAD_STATUS;
924 	break;
925     }
926 
927     HEIMDAL_MUTEX_unlock(&ctx->ctx_id_mutex);
928 
929     if (GSS_ERROR(ret)) {
930 	OM_uint32 min2;
931 	_gsskrb5_delete_sec_context(&min2, context_handle, GSS_C_NO_BUFFER);
932     }
933 
934     return ret;
935 }
936