abfe90cf79124beadc25d6b527b4f282e4b6718b
[mech_eap.orig] / util_reauth.c
1 /*
2  * Copyright (c) 2010, JANET(UK)
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  *
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * 3. Neither the name of JANET(UK) nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
21  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32
33 #include "gssapiP_eap.h"
34
35 #include <dlfcn.h>
36
37 /*
38  * Fast reauthentication support for EAP GSS.
39  */
40
41 krb5_error_code
42 krb5_encrypt_tkt_part(krb5_context, const krb5_keyblock *, krb5_ticket *);
43
44 krb5_error_code
45 encode_krb5_ticket(const krb5_ticket *rep, krb5_data **code);
46
47 static OM_uint32
48 gssDisplayName(OM_uint32 *minor,
49                gss_name_t name,
50                gss_buffer_t buffer,
51                gss_OID *name_type);
52
53 static OM_uint32
54 gssImportName(OM_uint32 *minor,
55               gss_buffer_t buffer,
56               gss_OID name_type,
57               gss_name_t *name);
58
59 static krb5_error_code
60 getAcceptorKey(krb5_context krbContext,
61                gss_ctx_id_t ctx,
62                gss_cred_id_t cred,
63                krb5_principal *princ,
64                krb5_keyblock *key)
65 {
66     krb5_error_code code;
67     krb5_keytab keytab = NULL;
68     krb5_keytab_entry ktent = { 0 };
69     krb5_kt_cursor cursor = NULL;
70
71     *princ = NULL;
72     memset(key, 0, sizeof(*key));
73
74     code = krb5_kt_default(krbContext, &keytab);
75     if (code != 0)
76         goto cleanup;
77
78     if (cred != GSS_C_NO_CREDENTIAL && cred->name != GSS_C_NO_NAME) {
79         code = krb5_kt_get_entry(krbContext, keytab,
80                                  cred->name->krbPrincipal, 0,
81                                  ctx->encryptionType, &ktent);
82         if (code != 0)
83             goto cleanup;
84     } else {
85         /*
86          * It's not clear that looking encrypting the ticket in the
87          * requested EAP enctype provides any value.
88          */
89         code = krb5_kt_start_seq_get(krbContext, keytab, &cursor);
90         if (code != 0)
91             goto cleanup;
92
93         while ((code = krb5_kt_next_entry(krbContext, keytab,
94                                           &ktent, &cursor)) == 0) {
95             if (ktent.key.enctype == ctx->encryptionType)
96                 break;
97             else
98                 krb5_free_keytab_entry_contents(krbContext, &ktent);
99         }
100     }
101
102     if (code == 0) {
103         *princ = ktent.principal;
104         *key = ktent.key;
105     }
106
107 cleanup:
108     if (cred == GSS_C_NO_CREDENTIAL || cred->name == GSS_C_NO_NAME)
109         krb5_kt_end_seq_get(krbContext, keytab, &cursor);
110     krb5_kt_close(krbContext, keytab);
111
112     if (code != 0)
113         krb5_free_keytab_entry_contents(krbContext, &ktent);
114
115     return code;
116 }
117
118 static OM_uint32
119 freezeAttrContext(OM_uint32 *minor,
120                   gss_name_t initiatorName,
121                   krb5_const_principal acceptorPrinc,
122                   krb5_keyblock *session,
123                   krb5_authdata ***authdata)
124 {
125     OM_uint32 major, tmpMinor;
126     krb5_error_code code;
127     gss_buffer_desc attrBuf = GSS_C_EMPTY_BUFFER;
128     krb5_authdata *authData[2], authDatum = { 0 };
129     krb5_context krbContext;
130
131     GSSEAP_KRB_INIT(&krbContext);
132
133     major = gssEapExportAttrContext(minor, initiatorName, &attrBuf);
134     if (GSS_ERROR(major))
135         return major;
136
137     authDatum.ad_type = KRB5_AUTHDATA_RADIUS_AVP;
138     authDatum.length = attrBuf.length;
139     authDatum.contents = attrBuf.value;
140     authData[0] = &authDatum;
141     authData[1] = NULL;
142
143     code = krb5_make_authdata_kdc_issued(krbContext, session, acceptorPrinc,
144                                          authData, authdata);
145     if (code != 0) {
146         major = GSS_S_FAILURE;
147         *minor = code;
148     } else {
149         major = GSS_S_COMPLETE;
150     }
151
152     gss_release_buffer(&tmpMinor, &attrBuf);
153
154     return major;
155 }
156
157 /*
158  * Fabricate a ticket to ourselves given a GSS EAP context.
159  */
160 OM_uint32
161 gssEapMakeReauthCreds(OM_uint32 *minor,
162                       gss_ctx_id_t ctx,
163                       gss_cred_id_t cred,
164                       gss_buffer_t credBuf)
165 {
166     OM_uint32 major = GSS_S_COMPLETE;
167     krb5_error_code code;
168     krb5_context krbContext = NULL;
169     krb5_ticket ticket = { 0 };
170     krb5_keyblock session = { 0 }, acceptorKey = { 0 };
171     krb5_enc_tkt_part enc_part = { 0 };
172     krb5_data *ticketData = NULL, *credsData = NULL;
173     krb5_creds creds = { 0 };
174     krb5_auth_context authContext = NULL;
175
176     credBuf->length = 0;
177     credBuf->value = NULL;
178
179     GSSEAP_KRB_INIT(&krbContext);
180
181     code = getAcceptorKey(krbContext, ctx, cred,
182                           &ticket.server, &acceptorKey);
183     if (code == KRB5_KT_NOTFOUND) {
184         gss_buffer_desc emptyToken = { 0, "" };
185
186         /*
187          * If we can't produce the KRB-CRED message, we need to
188          * return an empty (not NULL) token to the caller so we
189          * don't change the number of authentication legs.
190          */
191         return duplicateBuffer(minor, &emptyToken, credBuf);
192     } else if (code != 0)
193         goto cleanup;
194
195     enc_part.flags = TKT_FLG_INITIAL;
196
197     /*
198      * Generate a random session key to place in the ticket and
199      * sign the "KDC-Issued" authorization data element.
200      */
201     code = krb5_c_make_random_key(krbContext, ctx->encryptionType,
202                                   &session);
203     if (code != 0)
204         goto cleanup;
205
206     enc_part.session = &session;
207     enc_part.client = ctx->initiatorName->krbPrincipal;
208     enc_part.times.authtime = time(NULL);
209     enc_part.times.starttime = enc_part.times.authtime;
210     enc_part.times.endtime = ctx->expiryTime
211                              ? ctx->expiryTime
212                              : KRB5_INT32_MAX;
213     enc_part.times.renew_till = 0;
214
215     major = freezeAttrContext(minor, ctx->initiatorName, ticket.server,
216                               &session, &enc_part.authorization_data);
217     if (GSS_ERROR(major))
218         goto cleanup;
219
220     ticket.enc_part2 = &enc_part;
221
222     code = krb5_encrypt_tkt_part(krbContext, &acceptorKey, &ticket);
223     if (code != 0)
224         goto cleanup;
225
226     code = encode_krb5_ticket(&ticket, &ticketData);
227     if (code != 0)
228         goto cleanup;
229
230     creds.client = enc_part.client;
231     creds.server = ticket.server;
232     creds.keyblock = session;
233     creds.times = enc_part.times;
234     creds.ticket_flags = enc_part.flags;
235     creds.ticket = *ticketData;
236     creds.authdata = enc_part.authorization_data;
237
238     code = krb5_auth_con_init(krbContext, &authContext);
239     if (code != 0)
240         goto cleanup;
241
242     code = krb5_auth_con_setflags(krbContext, authContext, 0);
243     if (code != 0)
244         goto cleanup;
245
246     code = krb5_auth_con_setsendsubkey(krbContext, authContext,
247                                        &ctx->rfc3961Key);
248     if (code != 0)
249         goto cleanup;
250
251     code = krb5_mk_1cred(krbContext, authContext, &creds, &credsData, NULL);
252     if (code != 0)
253         goto cleanup;
254
255     krbDataToGssBuffer(credsData, credBuf);
256
257 cleanup:
258     if (ticket.enc_part.ciphertext.data != NULL)
259         GSSEAP_FREE(ticket.enc_part.ciphertext.data);
260     krb5_free_keyblock_contents(krbContext, &session);
261     krb5_free_keyblock_contents(krbContext, &acceptorKey);
262     krb5_free_data(krbContext, ticketData);
263     krb5_auth_con_free(krbContext, authContext);
264     krb5_free_authdata(krbContext, enc_part.authorization_data);
265     if (credsData != NULL)
266         GSSEAP_FREE(credsData);
267
268     if (major == GSS_S_COMPLETE) {
269         *minor = code;
270         major = code != 0 ? GSS_S_FAILURE : GSS_S_COMPLETE;
271     }
272
273     return major;
274 }
275
276 static int
277 isTicketGrantingServiceP(krb5_context krbContext,
278                          krb5_const_principal principal)
279 {
280     if (krb5_princ_size(krbContext, principal) == 2 &&
281         krb5_princ_component(krbContext, principal, 0)->length == 6 &&
282         memcmp(krb5_princ_component(krbContext,
283                                     principal, 0)->data, "krbtgt", 6) == 0)
284         return TRUE;
285
286     return FALSE;
287 }
288
289 /*
290  * Store re-authentication (Kerberos) credentials in a credential handle.
291  */
292 OM_uint32
293 gssEapStoreReauthCreds(OM_uint32 *minor,
294                        gss_ctx_id_t ctx,
295                        gss_cred_id_t cred,
296                        gss_buffer_t credBuf)
297 {
298     OM_uint32 major = GSS_S_COMPLETE, code;
299     krb5_context krbContext = NULL;
300     krb5_auth_context authContext = NULL;
301     krb5_data credData = { 0 };
302     krb5_creds **creds = NULL;
303     krb5_principal canonPrinc;
304     int i;
305
306     if (credBuf->length == 0 || cred == GSS_C_NO_CREDENTIAL)
307         return GSS_S_COMPLETE;
308
309     GSSEAP_KRB_INIT(&krbContext);
310
311     code = krb5_auth_con_init(krbContext, &authContext);
312     if (code != 0)
313         goto cleanup;
314
315     code = krb5_auth_con_setflags(krbContext, authContext, 0);
316     if (code != 0)
317         goto cleanup;
318
319     code = krb5_auth_con_setrecvsubkey(krbContext, authContext,
320                                        &ctx->rfc3961Key);
321     if (code != 0)
322         goto cleanup;
323
324     gssBufferToKrbData(credBuf, &credData);
325
326     code = krb5_rd_cred(krbContext, authContext, &credData, &creds, NULL);
327     if (code != 0)
328         goto cleanup;
329
330     if (creds == NULL || creds[0] == NULL)
331         goto cleanup;
332
333     code = krb5_copy_principal(krbContext, creds[0]->client, &canonPrinc);
334     if (code != 0)
335         goto cleanup;
336
337     krb5_free_principal(krbContext, cred->name->krbPrincipal);
338     cred->name->krbPrincipal = canonPrinc;
339
340     cred->expiryTime = creds[0]->times.endtime;
341
342     code = krb5_cc_new_unique(krbContext, "MEMORY", NULL, &cred->krbCredCache);
343     if (code != 0)
344         goto cleanup;
345
346     code = krb5_cc_initialize(krbContext, cred->krbCredCache,
347                               creds[0]->client);
348     if (code != 0)
349         goto cleanup;
350
351     for (i = 0; creds[i] != NULL; i++) {
352         krb5_creds kcred = *(creds[i]);
353
354         /*
355          * Swap in the acceptor name the client asked for so
356          * get_credentials() works. We're making the assumption that
357          * any service tickets returned are for us. We'll need to
358          * reflect some more on whether that is a safe assumption.
359          */
360         if (!isTicketGrantingServiceP(krbContext, kcred.server))
361             kcred.server = ctx->acceptorName->krbPrincipal;
362
363         code = krb5_cc_store_cred(krbContext, cred->krbCredCache, &kcred);
364         if (code != 0)
365             goto cleanup;
366     }
367
368     /*
369      * To turn a credentials cache into a GSS credentials handle, we
370      * require the gss_krb5_import_cred() API (present in Heimdal, but
371      * not shipped in MIT yet).
372      */
373     major = gss_krb5_import_cred(minor, cred->krbCredCache, NULL, NULL,
374                                  &cred->krbCred);
375     if (GSS_ERROR(major))
376         goto cleanup;
377
378 cleanup:
379     *minor = code;
380
381     krb5_auth_con_free(krbContext, authContext);
382     if (creds != NULL) {
383         for (i = 0; creds[i] != NULL; i++)
384             krb5_free_creds(krbContext, creds[i]);
385     }
386     if (major == GSS_S_COMPLETE)
387         major = *minor ? GSS_S_FAILURE : GSS_S_COMPLETE;
388
389     return major;
390 }
391
392 static gss_buffer_desc radiusAvpKrbAttr = {
393     sizeof("urn:authdata-radius-avp") - 1, "urn:authdata-radius-avp"
394 };
395
396 /*
397  * Unfortunately extracting an AD-KDCIssued authorization data element
398  * is pretty implementation-dependent. It's not possible to verify the
399  * signature ourselves because the ticket session key is not exposed
400  * outside GSS. In an ideal world, all AD-KDCIssued elements would be
401  * verified by the Kerberos library and authentication would fail if
402  * verification failed. We're not quite there yet and as a result have
403  * to go through some hoops to get this to work. The alternative would
404  * be to sign the authorization data with our long-term key, but it
405  * seems a pity to compromise the design because of current implementation
406  * limitations.
407  *
408  * (Specifically, the hoops involve a libkrb5 authorisation data plugin
409  * that exposes the verified and serialised attribute context through
410  * the Kerberos GSS mechanism's naming extensions API.)
411  */
412 static OM_uint32
413 defrostAttrContext(OM_uint32 *minor,
414                    gss_name_t glueName,
415                    gss_name_t mechName)
416 {
417     OM_uint32 major, tmpMinor;
418     gss_buffer_desc authData = GSS_C_EMPTY_BUFFER;
419     gss_buffer_desc authDataDisplay = GSS_C_EMPTY_BUFFER;
420     int more = -1;
421     int authenticated, complete;
422
423     major = gssGetNameAttribute(minor, glueName, &radiusAvpKrbAttr,
424                                 &authenticated, &complete,
425                                 &authData, &authDataDisplay, &more);
426     if (major == GSS_S_COMPLETE) {
427         if (authenticated == 0)
428             major = GSS_S_BAD_NAME;
429         else
430             major = gssEapImportAttrContext(minor, &authData, mechName);
431     } else if (major == GSS_S_UNAVAILABLE) {
432         major = GSS_S_COMPLETE;
433     }
434
435     gss_release_buffer(&tmpMinor, &authData);
436     gss_release_buffer(&tmpMinor, &authDataDisplay);
437
438     return major;
439 }
440
441 /*
442  * Convert a mechanism glue to an EAP mechanism name by displaying and
443  * importing it. This also handles the RADIUS attributes.
444  */
445 OM_uint32
446 gssEapGlueToMechName(OM_uint32 *minor,
447                      gss_name_t glueName,
448                      gss_name_t *pMechName)
449 {
450     OM_uint32 major, tmpMinor;
451     gss_buffer_desc nameBuf = GSS_C_EMPTY_BUFFER;
452
453     *pMechName = GSS_C_NO_NAME;
454
455     major = gssDisplayName(minor, glueName, &nameBuf, NULL);
456     if (GSS_ERROR(major))
457         goto cleanup;
458
459     major = gssEapImportName(minor, &nameBuf, GSS_C_NT_USER_NAME,
460                              pMechName);
461     if (GSS_ERROR(major))
462         goto cleanup;
463
464     major = defrostAttrContext(minor, glueName, *pMechName);
465     if (GSS_ERROR(major))
466         goto cleanup;
467
468 cleanup:
469     if (GSS_ERROR(major)) {
470         gssReleaseName(&tmpMinor, pMechName);
471         *pMechName = GSS_C_NO_NAME;
472     }
473
474     gss_release_buffer(&tmpMinor, &nameBuf);
475
476     return major;
477 }
478
479 /*
480  * Convert an EAP mechanism name to a mechanism glue name by displaying
481  * and importing it.
482  */
483 OM_uint32
484 gssEapMechToGlueName(OM_uint32 *minor,
485                      gss_name_t mechName,
486                      gss_name_t *pGlueName)
487 {
488     OM_uint32 major, tmpMinor;
489     gss_buffer_desc nameBuf = GSS_C_EMPTY_BUFFER;
490
491     *pGlueName = GSS_C_NO_NAME;
492
493     major = gssEapDisplayName(minor, mechName, &nameBuf, NULL);
494     if (GSS_ERROR(major))
495         goto cleanup;
496
497     major = gssImportName(minor, &nameBuf, GSS_C_NT_USER_NAME,
498                           pGlueName);
499     if (GSS_ERROR(major))
500         goto cleanup;
501
502 cleanup:
503     gss_release_buffer(&tmpMinor, &nameBuf);
504
505     return major;
506 }
507
508 /*
509  * Suck out the analgous elements of a Kerberos GSS context into an EAP
510  * one so that the application doesn't know the difference.
511  */
512 OM_uint32
513 gssEapReauthComplete(OM_uint32 *minor,
514                     gss_ctx_id_t ctx,
515                     gss_cred_id_t cred,
516                     const gss_OID mech,
517                     OM_uint32 timeRec)
518 {
519     OM_uint32 major, tmpMinor;
520     gss_buffer_set_t keyData = GSS_C_NO_BUFFER_SET;
521
522     if (!oidEqual(mech, gss_mech_krb5)) {
523         major = GSS_S_BAD_MECH;
524         goto cleanup;
525     }
526
527     /* Get the raw subsession key and encryption type*/
528     major = gssInquireSecContextByOid(minor, ctx->kerberosCtx,
529                                       GSS_C_INQ_SSPI_SESSION_KEY, &keyData);
530     if (GSS_ERROR(major))
531         goto cleanup;
532
533     {
534         gss_OID_desc oid;
535         int suffix;
536
537         oid.length = keyData->elements[1].length;
538         oid.elements = keyData->elements[1].value;
539
540         /* GSS_KRB5_SESSION_KEY_ENCTYPE_OID */
541         major = decomposeOid(minor,
542                              "\x2a\x86\x48\x86\xf7\x12\x01\x02\x02\x04",
543                              10, &oid, &suffix);
544         if (GSS_ERROR(major))
545             goto cleanup;
546
547         ctx->encryptionType = suffix;
548     }
549
550     {
551         krb5_context krbContext = NULL;
552         krb5_keyblock key;
553
554         GSSEAP_KRB_INIT(&krbContext);
555
556         KRB_KEY_LENGTH(&key) = keyData->elements[0].length;
557         KRB_KEY_DATA(&key)   = keyData->elements[0].value;
558         KRB_KEY_TYPE(&key)   = ctx->encryptionType;
559
560         *minor = krb5_copy_keyblock_contents(krbContext,
561                                              &key, &ctx->rfc3961Key);
562         if (*minor != 0) {
563             major = GSS_S_FAILURE;
564             goto cleanup;
565         }
566     }
567
568     major = rfc3961ChecksumTypeForKey(minor, &ctx->rfc3961Key,
569                                       &ctx->checksumType);
570     if (GSS_ERROR(major))
571         goto cleanup;
572
573     if (timeRec != GSS_C_INDEFINITE)
574         ctx->expiryTime = time(NULL) + timeRec;
575
576     /* Initialize our sequence state */
577     major = sequenceInit(minor,
578                          &ctx->seqState, ctx->recvSeq,
579                          ((ctx->gssFlags & GSS_C_REPLAY_FLAG) != 0),
580                          ((ctx->gssFlags & GSS_C_SEQUENCE_FLAG) != 0),
581                          TRUE);
582     if (GSS_ERROR(major))
583         goto cleanup;
584
585     major = GSS_S_COMPLETE;
586
587 cleanup:
588     gss_release_buffer_set(&tmpMinor, &keyData);
589
590     return major;
591 }
592
593 /*
594  * The remainder of this file consists of wrappers so we can call into the
595  * mechanism glue without calling ourselves.
596  */
597 static OM_uint32
598 (*gssInitSecContextNext)(OM_uint32 *,
599                          gss_cred_id_t,
600                          gss_ctx_id_t *,
601                          gss_name_t,
602                          gss_OID,
603                          OM_uint32,
604                          OM_uint32,
605                          gss_channel_bindings_t,
606                          gss_buffer_t,
607                          gss_OID *,
608                          gss_buffer_t,
609                          OM_uint32 *,
610                          OM_uint32 *);
611
612 static OM_uint32
613 (*gssAcceptSecContextNext)(OM_uint32 *,
614                            gss_ctx_id_t *,
615                            gss_cred_id_t,
616                            gss_buffer_t,
617                            gss_channel_bindings_t,
618                            gss_name_t *,
619                            gss_OID *,
620                            gss_buffer_t,
621                            OM_uint32 *,
622                            OM_uint32 *,
623                            gss_cred_id_t *);
624
625 static OM_uint32
626 (*gssReleaseCredNext)(OM_uint32 *, gss_cred_id_t *);
627
628 static OM_uint32
629 (*gssReleaseNameNext)(OM_uint32 *, gss_name_t *);
630
631 static OM_uint32
632 (*gssInquireSecContextByOidNext)(OM_uint32 *,
633                                  const gss_ctx_id_t,
634                                  const gss_OID,
635                                  gss_buffer_set_t *);
636
637 static OM_uint32
638 (*gssDeleteSecContextNext)(OM_uint32 *,
639                           gss_ctx_id_t *,
640                           gss_buffer_t);
641
642 static OM_uint32
643 (*gssDisplayNameNext)(OM_uint32 *,
644                       gss_name_t,
645                       gss_buffer_t,
646                       gss_OID *);
647
648 static OM_uint32
649 (*gssImportNameNext)(OM_uint32 *,
650                      gss_buffer_t,
651                      gss_OID,
652                      gss_name_t *);
653
654 static OM_uint32
655 (*gssStoreCredNext)(OM_uint32 *,
656                     const gss_cred_id_t,
657                     gss_cred_usage_t,
658                     const gss_OID,
659                     OM_uint32,
660                     OM_uint32,
661                     gss_OID_set *,
662                     gss_cred_usage_t *);
663
664 static OM_uint32
665 (*gssGetNameAttributeNext)(OM_uint32 *,
666                           gss_name_t,
667                           gss_buffer_t,
668                           int *,
669                           int *,
670                           gss_buffer_t,
671                           gss_buffer_t,
672                           int *);
673
674 #define NEXT_SYMBOL(local, global)  ((local) = dlsym(RTLD_NEXT, (global)))
675
676 OM_uint32
677 gssEapReauthInitialize(OM_uint32 *minor)
678 {
679     NEXT_SYMBOL(gssInitSecContextNext,         "gss_init_sec_context");
680     NEXT_SYMBOL(gssAcceptSecContextNext,       "gss_accept_sec_context");
681     NEXT_SYMBOL(gssReleaseCredNext,            "gss_release_cred");
682     NEXT_SYMBOL(gssReleaseNameNext,            "gss_release_name");
683     NEXT_SYMBOL(gssInquireSecContextByOidNext, "gss_inquire_sec_context_by_oid");
684     NEXT_SYMBOL(gssDeleteSecContextNext,       "gss_delete_sec_context");
685     NEXT_SYMBOL(gssDisplayNameNext,            "gss_display_name");
686     NEXT_SYMBOL(gssImportNameNext,             "gss_import_name");
687     NEXT_SYMBOL(gssStoreCredNext,              "gss_store_cred");
688     NEXT_SYMBOL(gssGetNameAttributeNext,       "gss_get_name_attribute");
689
690     return GSS_S_COMPLETE;
691 }
692
693 OM_uint32
694 gssInitSecContext(OM_uint32 *minor,
695                   gss_cred_id_t cred,
696                   gss_ctx_id_t *context_handle,
697                   gss_name_t target_name,
698                   gss_OID mech_type,
699                   OM_uint32 req_flags,
700                   OM_uint32 time_req,
701                   gss_channel_bindings_t input_chan_bindings,
702                   gss_buffer_t input_token,
703                   gss_OID *actual_mech_type,
704                   gss_buffer_t output_token,
705                   OM_uint32 *ret_flags,
706                   OM_uint32 *time_rec)
707 {
708     if (gssInitSecContextNext == NULL)
709         return GSS_S_UNAVAILABLE;
710
711     return gssInitSecContextNext(minor, cred, context_handle,
712                                  target_name, mech_type, req_flags,
713                                  time_req, input_chan_bindings,
714                                  input_token, actual_mech_type,
715                                  output_token, ret_flags, time_rec);
716 }
717
718 OM_uint32
719 gssAcceptSecContext(OM_uint32 *minor,
720                     gss_ctx_id_t *context_handle,
721                     gss_cred_id_t cred,
722                     gss_buffer_t input_token,
723                     gss_channel_bindings_t input_chan_bindings,
724                     gss_name_t *src_name,
725                     gss_OID *mech_type,
726                     gss_buffer_t output_token,
727                     OM_uint32 *ret_flags,
728                     OM_uint32 *time_rec,
729                     gss_cred_id_t *delegated_cred_handle)
730 {
731     if (gssAcceptSecContextNext == NULL)
732         return GSS_S_UNAVAILABLE;
733
734     return gssAcceptSecContextNext(minor, context_handle, cred,
735                                    input_token, input_chan_bindings,
736                                    src_name, mech_type, output_token,
737                                    ret_flags, time_rec, delegated_cred_handle);
738 }
739
740 OM_uint32
741 gssReleaseCred(OM_uint32 *minor,
742                gss_cred_id_t *cred_handle)
743 {
744     if (gssReleaseCredNext == NULL)
745         return GSS_S_UNAVAILABLE;
746
747     return gssReleaseCredNext(minor, cred_handle);
748 }
749
750 OM_uint32
751 gssReleaseName(OM_uint32 *minor,
752                gss_name_t *name)
753 {
754     if (gssReleaseName == NULL)
755         return GSS_S_UNAVAILABLE;
756
757     return gssReleaseNameNext(minor, name);
758 }
759
760 OM_uint32
761 gssDeleteSecContext(OM_uint32 *minor,
762                     gss_ctx_id_t *context_handle,
763                     gss_buffer_t output_token)
764 {
765     if (gssDeleteSecContextNext == NULL)
766         return GSS_S_UNAVAILABLE;
767
768     return gssDeleteSecContextNext(minor, context_handle, output_token);
769 }
770
771 static OM_uint32
772 gssDisplayName(OM_uint32 *minor,
773                gss_name_t name,
774                gss_buffer_t buffer,
775                gss_OID *name_type)
776 {
777     if (gssDisplayNameNext == NULL)
778         return GSS_S_UNAVAILABLE;
779
780     return gssDisplayNameNext(minor, name, buffer, name_type);
781 }
782
783 static OM_uint32
784 gssImportName(OM_uint32 *minor,
785               gss_buffer_t buffer,
786               gss_OID name_type,
787               gss_name_t *name)
788 {
789     if (gssImportNameNext == NULL)
790         return GSS_S_UNAVAILABLE;
791
792     return gssImportNameNext(minor, buffer, name_type, name);
793 }
794
795 OM_uint32
796 gssInquireSecContextByOid(OM_uint32 *minor,
797                           const gss_ctx_id_t context_handle,
798                           const gss_OID desired_object,
799                           gss_buffer_set_t *data_set)
800 {
801     if (gssInquireSecContextByOidNext == NULL)
802         return GSS_S_UNAVAILABLE;
803
804     return gssInquireSecContextByOidNext(minor, context_handle,
805                                          desired_object, data_set);
806 }
807
808 OM_uint32
809 gssStoreCred(OM_uint32 *minor,
810              const gss_cred_id_t input_cred_handle,
811              gss_cred_usage_t input_usage,
812              const gss_OID desired_mech,
813              OM_uint32 overwrite_cred,
814              OM_uint32 default_cred,
815              gss_OID_set *elements_stored,
816              gss_cred_usage_t *cred_usage_stored)
817 {
818     if (gssStoreCredNext == NULL)
819         return GSS_S_UNAVAILABLE;
820
821     return gssStoreCredNext(minor, input_cred_handle, input_usage,
822                             desired_mech, overwrite_cred, default_cred,
823                             elements_stored, cred_usage_stored);
824 }
825
826 OM_uint32
827 gssGetNameAttribute(OM_uint32 *minor,
828                     gss_name_t name,
829                     gss_buffer_t attr,
830                     int *authenticated,
831                     int *complete,
832                     gss_buffer_t value,
833                     gss_buffer_t display_value,
834                     int *more)
835 {
836     if (gssGetNameAttributeNext == NULL)
837         return GSS_S_UNAVAILABLE;
838
839     return gssGetNameAttributeNext(minor, name, attr, authenticated, complete,
840                                    value, display_value, more);
841 }