openssh/gss-genr.c

   1 /*
   2  * Copyright (c) 2001,2002 Simon Wilkinson. All rights reserved. *
   3  * Redistribution and use in source and binary forms, with or without
   4  * modification, are permitted provided that the following conditions
   5  * are met:
   6  * 1. Redistributions of source code must retain the above copyright
   7  *    notice, this list of conditions and the following disclaimer.
   8  * 2. Redistributions in binary form must reproduce the above copyright
   9  *    notice, this list of conditions and the following disclaimer in the
  10  *    documentation and/or other materials provided with the distribution.
  11  *
  12  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
  13  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  14  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  15  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  16  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  17  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  18  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  19  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  20  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  21  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  22  */
  23
  24 #include "includes.h"
  25
  26 #ifdef GSSAPI
  27
  28 #include "ssh.h"
  29 #include "ssh2.h"
  30 #include "xmalloc.h"
  31 #include "buffer.h"
  32 #include "bufaux.h"
  33 #include "packet.h"
  34 #include "compat.h"
  35 #include <openssl/evp.h>
  36 #include "cipher.h"
  37 #include "kex.h"
  38 #include "log.h"
  39 #include "compat.h"
  40 #include "monitor_wrap.h"
  41
  42 #include <netdb.h>
  43
  44 #include "ssh-gss.h"
  45
  46 /* Assorted globals for tracking the clients identity once they've
  47  * authenticated */
  48
  49 gss_buffer_desc gssapi_client_name = {0,NULL}; /* Name of our client */
  50 gss_cred_id_t   gssapi_client_creds = GSS_C_NO_CREDENTIAL; /* Their credentials */
  51 enum ssh_gss_id gssapi_client_type = GSS_LAST_ENTRY;
  52
  53 unsigned char ssh1_key_digest[16]; /* used for ssh1 gssapi */
  54
  55 /* The mechanism name used in the list below is defined in the internet
  56  * draft as the Base 64 encoding of the MD5 hash of the ASN.1 DER encoding
  57  * of the underlying GSSAPI mechanism's OID.
  58  *
  59  * Also from the draft, before considering adding SPNEGO, bear in mind that
  60  * "mechanisms ... MUST NOT use SPNEGO as the underlying GSSAPI mechanism"
  61  */
  62
  63 /* These must be in the same order as ssh_gss_id, in ssh-gss.h */
  64
  65 ssh_gssapi_mech supported_mechs[]= {
  66 #ifdef KRB5
  67  /* Official OID - 1.2.850.113554.1.2.2 */
  68  {"Se3H81ismmOC3OE+FwYCiQ==","Kerberos",
  69         {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"}},
  70 #endif
  71 #ifdef GSI
  72  /* gssapi_ssleay 1.3.6.1.4.1.3536.1.1 */
  73  {"N3+k7/4wGxHyuP8Yxi4RhA==",
  74   "GSI",
  75   {9, "\x2B\x06\x01\x04\x01\x9B\x50\x01\x01"}
  76  },
  77 #endif /* GSI */
  78  {NULL,NULL,{0,0}}
  79 };
  80
  81 char gssprefix[]=KEX_GSS_SHA1;
  82
  83 /* Return a list of the gss-group1-sha1-x mechanisms supported by this
  84  * program.
  85  *
  86  * We only support the mechanisms that we've indicated in the list above,
  87  * but we check that they're supported by the GSSAPI mechanism on the
  88  * machine. We also check, before including them in the list, that
  89  * we have the necesary information in order to carry out the key exchange
  90  * (that is, that the user has credentials, the server's creds are accessible,
  91  * etc)
  92  *
  93  * The way that this is done is fairly nasty, as we do a lot of work that
  94  * is then thrown away. This should possibly be implemented with a cache
  95  * that stores the results (in an expanded Gssctxt structure), which are
  96  * then used by the first calls if that key exchange mechanism is chosen.
  97  */
  98
  99 char *
 100 ssh_gssapi_mechanisms(int server,char *host) {
 101         gss_OID_set     supported;
 102         OM_uint32       maj_status, min_status;
 103         Buffer          buf;
 104         int             i = 0;
 105         int             present;
 106         int             mech_count=0;
 107         char *          mechs;
 108         Gssctxt *       ctx = NULL;
 109
 110         if (datafellows & SSH_OLD_GSSAPI) return NULL;
 111
 112         gss_indicate_mechs(&min_status, &supported);
 113
 114         buffer_init(&buf);
 115
 116         do {
 117                 if ((maj_status=gss_test_oid_set_member(&min_status,
 118                                                         &supported_mechs[i].oid,
 119                                                         supported,
 120                                                         &present))) {
 121                         present=0;
 122                 }
 123                 if (present) {
 124                         if ((server &&
 125                              !GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctx,
 126                                                             &supported_mechs[i].oid))))
 127                             || (!server &&
 128                                 !GSS_ERROR(ssh_gssapi_client_ctx(&ctx,
 129                                                        &supported_mechs[i].oid,
 130                                                        host)))) {
 131                                 /* Append gss_group1_sha1_x to our list */
 132                                 if (++mech_count > 1) {
 133                                     buffer_append(&buf, ",", 1);
 134                                 }
 135                                 buffer_append(&buf, gssprefix,
 136                                               strlen(gssprefix));
 137                                 buffer_append(&buf,
 138                                               supported_mechs[i].enc_name,
 139                                               strlen(supported_mechs[i].enc_name));
 140                                 debug("GSSAPI mechanism %s (%s%s) supported",
 141                                       supported_mechs[i].name, gssprefix,
 142                                       supported_mechs[i].enc_name);
 143                         } else {
 144                             debug("no credentials for GSSAPI mechanism %s",
 145                                   supported_mechs[i].name);
 146                         }
 147                 } else {
 148                     debug("GSSAPI mechanism %s not supported",
 149                           supported_mechs[i].name);
 150                 }
 151         } while (supported_mechs[++i].name != NULL);
 152
 153         buffer_put_char(&buf,'\0');
 154
 155         mechs=xmalloc(buffer_len(&buf));
 156         buffer_get(&buf,mechs,buffer_len(&buf));
 157         buffer_free(&buf);
 158         if (strlen(mechs)==0)
 159            return(NULL);
 160         else
 161            return(mechs);
 162 }
 163
 164 void ssh_gssapi_supported_oids(gss_OID_set *oidset) {
 165         enum ssh_gss_id i =0;
 166         OM_uint32 maj_status,min_status;
 167         int present;
 168         gss_OID_set supported;
 169
 170         gss_create_empty_oid_set(&min_status,oidset);
 171         gss_indicate_mechs(&min_status, &supported);
 172
 173         while (supported_mechs[i].name!=NULL) {
 174                 if ((maj_status=gss_test_oid_set_member(&min_status,
 175                                                        &supported_mechs[i].oid,
 176                                                        supported,
 177                                                        &present))) {
 178                         present=0;
 179                 }
 180                 if (present) {
 181                         gss_add_oid_set_member(&min_status,
 182                                                &supported_mechs[i].oid,
 183                                                oidset);
 184                 }
 185                 i++;
 186         }
 187 }
 188
 189 /* Set the contexts OID from a data stream */
 190 void ssh_gssapi_set_oid_data(Gssctxt *ctx, void *data, size_t len) {
 191   if (ctx->oid != GSS_C_NO_OID) {
 192         xfree(ctx->oid->elements);
 193         xfree(ctx->oid);
 194   }
 195   ctx->oid=xmalloc(sizeof(gss_OID_desc));
 196   ctx->oid->length=len;
 197   ctx->oid->elements=xmalloc(len);
 198   memcpy(ctx->oid->elements,data,len);
 199 }
 200
 201 /* Set the contexts OID */
 202 void ssh_gssapi_set_oid(Gssctxt *ctx, gss_OID oid) {
 203   ssh_gssapi_set_oid_data(ctx,oid->elements,oid->length);
 204 }
 205
 206 /* Find out which GSS type (out of the list we define in ssh-gss.h) a
 207  * particular connection is using
 208  */
 209 enum ssh_gss_id ssh_gssapi_get_ctype(Gssctxt *ctxt) {
 210         enum ssh_gss_id i=0;
 211
 212         while(supported_mechs[i].name!=NULL) {
 213            if (supported_mechs[i].oid.length == ctxt->oid->length &&
 214                (memcmp(supported_mechs[i].oid.elements,
 215                        ctxt->oid->elements,ctxt->oid->length) == 0))
 216                return i;
 217            i++;
 218         }
 219         return(GSS_LAST_ENTRY);
 220 }
 221
 222 /* Set the GSS context's OID to the oid indicated by the given key exchange
 223  * name. */
 224 gss_OID ssh_gssapi_id_kex(Gssctxt *ctx, char *name) {
 225   enum ssh_gss_id i=0;
 226
 227   if (strncmp(name, gssprefix, strlen(gssprefix)-1) !=0) {
 228      return(NULL);
 229   }
 230
 231   name+=strlen(gssprefix); /* Move to the start of the MIME string */
 232
 233   while (supported_mechs[i].name!=NULL &&
 234          strcmp(name,supported_mechs[i].enc_name)!=0) {
 235         i++;
 236   }
 237
 238   if (supported_mechs[i].name==NULL)
 239      return (NULL);
 240
 241   if (ctx) ssh_gssapi_set_oid(ctx,&supported_mechs[i].oid);
 242
 243   debug("using GSSAPI mechanism %s (%s%s)", supported_mechs[i].name,
 244         gssprefix, supported_mechs[i].enc_name);
 245
 246   return &supported_mechs[i].oid;
 247 }
 248
 249
 250 /* All this effort to report an error ... */
 251 static void
 252 ssh_gssapi_error_ex(OM_uint32 major_status,OM_uint32 minor_status,
 253                     int send_packet) {
 254         OM_uint32 lmaj, lmin;
 255         gss_buffer_desc msg = {0,NULL};
 256         OM_uint32 ctx;
 257
 258         ctx = 0;
 259         /* The GSSAPI error */
 260         do {
 261                 lmaj = gss_display_status(&lmin, major_status,
 262                                           GSS_C_GSS_CODE,
 263                                           GSS_C_NULL_OID,
 264                                           &ctx, &msg);
 265                 if (lmaj == GSS_S_COMPLETE) {
 266                         debug((char *)msg.value);
 267                         if (send_packet) packet_send_debug((char *)msg.value);
 268                         (void) gss_release_buffer(&lmin, &msg);
 269                 }
 270         } while (ctx!=0);
 271
 272         /* The mechanism specific error */
 273         do {
 274                 lmaj = gss_display_status(&lmin, minor_status,
 275                                           GSS_C_MECH_CODE,
 276                                           GSS_C_NULL_OID,
 277                                           &ctx, &msg);
 278                 if (lmaj == GSS_S_COMPLETE) {
 279                         debug((char *)msg.value);
 280                         if (send_packet) packet_send_debug((char *)msg.value);
 281                         (void) gss_release_buffer(&lmin, &msg);
 282                 }
 283         } while (ctx!=0);
 284 }
 285
 286 void
 287 ssh_gssapi_error(OM_uint32 major_status,OM_uint32 minor_status) {
 288     ssh_gssapi_error_ex(major_status, minor_status, 0);
 289 }
 290
 291 void
 292 ssh_gssapi_send_error(OM_uint32 major_status,OM_uint32 minor_status) {
 293     ssh_gssapi_error_ex(major_status, minor_status, 1);
 294 }
 295
 296
 297
 298
 299 /* Initialise our GSSAPI context. We use this opaque structure to contain all
 300  * of the data which both the client and server need to persist across
 301  * {accept,init}_sec_context calls, so that when we do it from the userauth
 302  * stuff life is a little easier
 303  */
 304 void
 305 ssh_gssapi_build_ctx(Gssctxt **ctx)
 306 {
 307         *ctx=xmalloc(sizeof (Gssctxt));
 308         (*ctx)->context=GSS_C_NO_CONTEXT;
 309         (*ctx)->name=GSS_C_NO_NAME;
 310         (*ctx)->oid=GSS_C_NO_OID;
 311         (*ctx)->creds=GSS_C_NO_CREDENTIAL;
 312         (*ctx)->client=GSS_C_NO_NAME;
 313         (*ctx)->client_creds=GSS_C_NO_CREDENTIAL;
 314 }
 315
 316 /* Delete our context, providing it has been built correctly */
 317 void
 318 ssh_gssapi_delete_ctx(Gssctxt **ctx)
 319 {
 320         OM_uint32 ms;
 321
 322         /* Return if there's no context */
 323         if ((*ctx)==NULL)
 324                 return;
 325
 326 #if !defined(MECHGLUE) /* mechglue has some memory management issues */
 327         if ((*ctx)->context != GSS_C_NO_CONTEXT)
 328                 gss_delete_sec_context(&ms,&(*ctx)->context,GSS_C_NO_BUFFER);
 329         if ((*ctx)->name != GSS_C_NO_NAME)
 330                 gss_release_name(&ms,&(*ctx)->name);
 331         if ((*ctx)->oid != GSS_C_NO_OID) {
 332                 xfree((*ctx)->oid->elements);
 333                 xfree((*ctx)->oid);
 334                 (*ctx)->oid = GSS_C_NO_OID;
 335         }
 336         if ((*ctx)->creds != GSS_C_NO_CREDENTIAL)
 337                 gss_release_cred(&ms,&(*ctx)->creds);
 338         if ((*ctx)->client != GSS_C_NO_NAME)
 339                 gss_release_name(&ms,&(*ctx)->client);
 340         if ((*ctx)->client_creds != GSS_C_NO_CREDENTIAL)
 341                 gss_release_cred(&ms,&(*ctx)->client_creds);
 342 #endif
 343
 344         xfree(*ctx);
 345         *ctx=NULL;
 346 }
 347
 348 /* Wrapper to init_sec_context
 349  * Requires that the context contains:
 350  *      oid
 351  *      server name (from ssh_gssapi_import_name)
 352  */
 353 OM_uint32
 354 ssh_gssapi_init_ctx(Gssctxt *ctx, int deleg_creds, gss_buffer_desc *recv_tok,
 355                     gss_buffer_desc* send_tok, OM_uint32 *flags)
 356 {
 357         OM_uint32 maj_status, min_status;
 358         int deleg_flag = 0;
 359
 360         if (deleg_creds) {
 361                 deleg_flag=GSS_C_DELEG_FLAG;
 362                 debug("Delegating credentials");
 363         }
 364
 365         maj_status=gss_init_sec_context(&min_status,
 366                                         GSS_C_NO_CREDENTIAL, /* def. cred */
 367                                         &ctx->context,
 368                                         ctx->name,
 369                                         ctx->oid,
 370                                         GSS_C_MUTUAL_FLAG |
 371                                         GSS_C_INTEG_FLAG |
 372                                         deleg_flag,
 373                                         0, /* default lifetime */
 374                                         NULL, /* no channel bindings */
 375                                         recv_tok,
 376                                         NULL,
 377                                         send_tok,
 378                                         flags,
 379                                         NULL);
 380         ctx->status=maj_status;
 381         if (GSS_ERROR(maj_status)) {
 382                 ssh_gssapi_error(maj_status,min_status);
 383         }
 384         return(maj_status);
 385 }
 386
 387 /* Wrapper arround accept_sec_context
 388  * Requires that the context contains:
 389  *    oid
 390  *    credentials       (from ssh_gssapi_acquire_cred)
 391  */
 392 OM_uint32 ssh_gssapi_accept_ctx(Gssctxt *ctx,gss_buffer_desc *recv_tok,
 393                                 gss_buffer_desc *send_tok, OM_uint32 *flags)
 394 {
 395         OM_uint32 maj_status, min_status;
 396         gss_OID mech;
 397
 398         maj_status=gss_accept_sec_context(&min_status,
 399                                           &ctx->context,
 400                                           ctx->creds,
 401                                           recv_tok,
 402                                           GSS_C_NO_CHANNEL_BINDINGS,
 403                                           &ctx->client,
 404                                           &mech,
 405                                           send_tok,
 406                                           flags,
 407                                           NULL,
 408                                           &ctx->client_creds);
 409         if (GSS_ERROR(maj_status)) {
 410                 ssh_gssapi_send_error(maj_status,min_status);
 411         }
 412
 413         if (ctx->client_creds) {
 414                 debug("Received some client credentials");
 415         } else {
 416                 debug("Got no client credentials");
 417         }
 418
 419         /* FIXME: We should check that the me
 420          * the one that we asked for (in ctx->oid) */
 421
 422         ctx->status=maj_status;
 423
 424         /* Now, if we're complete and we have the right flags, then
 425          * we flag the user as also having been authenticated
 426          */
 427
 428         if (((flags==NULL) || ((*flags & GSS_C_MUTUAL_FLAG) &&
 429                                (*flags & GSS_C_INTEG_FLAG))) &&
 430             (maj_status == GSS_S_COMPLETE)) {
 431                 if (ssh_gssapi_getclient(ctx,&gssapi_client_type,
 432                                          &gssapi_client_name,
 433                                          &gssapi_client_creds))
 434                         fatal("Couldn't convert client name");
 435         }
 436
 437         return(maj_status);
 438 }
 439
 440 /* Create a service name for the given host */
 441 OM_uint32
 442 ssh_gssapi_import_name(Gssctxt *ctx, const char *host) {
 443         gss_buffer_desc gssbuf = {0,NULL};
 444         OM_uint32 maj_status, min_status;
 445         struct hostent *hostinfo = NULL;
 446         char *xhost, *addr;
 447
 448         /* Make a copy of the host name, in case it was returned by a
 449          * previous call to gethostbyname(). */
 450         xhost = xstrdup(host);
 451
 452         /* Make sure we have the FQDN. Some GSSAPI implementations don't do
 453          * this for us themselves */
 454         hostinfo = gethostbyname(xhost);
 455
 456         /* Use local hostname when coming in on loopback interface because
 457            we won't have 'localhost' credentials. */
 458         if (hostinfo &&
 459             hostinfo->h_addrtype == AF_INET) {
 460             struct in_addr addr;
 461             addr = *(struct in_addr *)(hostinfo->h_addr);
 462             if (ntohl(addr.s_addr) == INADDR_LOOPBACK) {
 463                 char buf[4096];
 464                 if (gethostname(buf, 4096) == 0) {
 465                     hostinfo = gethostbyname(buf);
 466                 }
 467             }
 468         }
 469
 470         /* Go to the resolver to get the official hostname for our target.
 471            WARNING: This makes us vulnerable to DNS spoofing. */
 472         if ((hostinfo == NULL) || (hostinfo->h_name == NULL)) {
 473                 debug("Unable to get FQDN for \"%s\"", xhost);
 474         } else {
 475                 addr = xmalloc(hostinfo->h_length);
 476                 memcpy(addr, hostinfo->h_addr, hostinfo->h_length);
 477                 hostinfo = gethostbyaddr(addr, hostinfo->h_length,
 478                                          hostinfo->h_addrtype);
 479                 xfree(addr);
 480                 if ((hostinfo == NULL) || (hostinfo->h_name == NULL)) {
 481                     debug("Unable to get FQDN for \"%s\"", xhost);
 482                 } else {
 483                     xfree(xhost);
 484                     xhost = xstrdup(hostinfo->h_name);
 485                 }
 486         }
 487
 488         gssbuf.length = sizeof("host@")+strlen(xhost);
 489
 490         gssbuf.value = xmalloc(gssbuf.length);
 491         if (gssbuf.value == NULL) {
 492                 xfree(xhost);
 493                 return(-1);
 494         }
 495         snprintf(gssbuf.value,gssbuf.length,"host@%s",xhost);
 496         if ((maj_status=gss_import_name(&min_status,
 497                                         &gssbuf,
 498                                         GSS_C_NT_HOSTBASED_SERVICE,
 499                                         &ctx->name))) {
 500                 ssh_gssapi_error(maj_status,min_status);
 501         }
 502
 503         xfree(xhost);
 504         xfree(gssbuf.value);
 505         return(maj_status);
 506 }
 507
 508 /* Acquire credentials for a server running on the current host.
 509  * Requires that the context structure contains a valid OID
 510  */
 511
 512 /* Returns a GSSAPI error code */
 513 OM_uint32
 514 ssh_gssapi_acquire_cred(Gssctxt *ctx) {
 515         OM_uint32 maj_status, min_status;
 516         char lname[MAXHOSTNAMELEN];
 517         gss_OID_set oidset;
 518
 519         gss_create_empty_oid_set(&min_status,&oidset);
 520         gss_add_oid_set_member(&min_status,ctx->oid,&oidset);
 521
 522         if (gethostname(lname, MAXHOSTNAMELEN)) {
 523                 return(-1);
 524         }
 525
 526         if ((maj_status=ssh_gssapi_import_name(ctx,lname))) {
 527                 return(maj_status);
 528         }
 529         if ((maj_status=gss_acquire_cred(&min_status,
 530                                     ctx->name,
 531                                     0,
 532                                     oidset,
 533                                     GSS_C_ACCEPT,
 534                                     &ctx->creds,
 535                                     NULL,
 536                                     NULL))) {
 537                 ssh_gssapi_error(maj_status,min_status);
 538         }
 539
 540         gss_release_oid_set(&min_status, &oidset);
 541         return(maj_status);
 542 }
 543
 544 /* Extract the client details from a given context. This can only reliably
 545  * be called once for a context */
 546
 547 OM_uint32
 548 ssh_gssapi_getclient(Gssctxt *ctx, enum ssh_gss_id *type,
 549                      gss_buffer_desc *name, gss_cred_id_t *creds) {
 550
 551         OM_uint32 maj_status,min_status;
 552
 553         *type=ssh_gssapi_get_ctype(ctx);
 554         if ((maj_status=gss_display_name(&min_status,ctx->client,name,NULL))) {
 555                 ssh_gssapi_error(maj_status,min_status);
 556         }
 557
 558         /* This is icky. There appears to be no way to copy this structure,
 559          * rather than the pointer to it, so we simply copy the pointer and
 560          * mark the originator as empty so we don't destroy it.
 561          */
 562         *creds=ctx->client_creds;
 563         ctx->client_creds=GSS_C_NO_CREDENTIAL;
 564         return(maj_status);
 565 }
 566
 567 OM_uint32
 568 ssh_gssapi_sign(Gssctxt *ctx, gss_buffer_desc *buffer, gss_buffer_desc *hash) {
 569         OM_uint32 maj_status,min_status;
 570
 571         /* ssh1 needs to exchange the hash of the keys */
 572         /* will us this hash to return it */
 573         if (!compat20) {
 574                 if ((maj_status=gss_wrap(&min_status,ctx->context,
 575                                         0,
 576                                         GSS_C_QOP_DEFAULT,
 577                                         buffer,
 578                                         NULL,
 579                                         hash)))
 580                         ssh_gssapi_error(maj_status,min_status);
 581         }
 582         else
 583
 584         if ((maj_status=gss_get_mic(&min_status,ctx->context,
 585                                     GSS_C_QOP_DEFAULT, buffer, hash))) {
 586                 ssh_gssapi_error(maj_status,min_status);
 587         }
 588
 589         return(maj_status);
 590 }
 591
 592 OM_uint32
 593 ssh_gssapi_server_ctx(Gssctxt **ctx,gss_OID oid) {
 594         if (*ctx) ssh_gssapi_delete_ctx(ctx);
 595         ssh_gssapi_build_ctx(ctx);
 596         ssh_gssapi_set_oid(*ctx,oid);
 597         return(ssh_gssapi_acquire_cred(*ctx));
 598 }
 599
 600 OM_uint32
 601 ssh_gssapi_client_ctx(Gssctxt **ctx,gss_OID oid, char *host) {
 602         gss_buffer_desc token = {0,NULL};
 603         OM_uint32 major,minor;
 604
 605         if (*ctx) ssh_gssapi_delete_ctx(ctx);
 606         ssh_gssapi_build_ctx(ctx);
 607         ssh_gssapi_set_oid(*ctx,oid);
 608         ssh_gssapi_import_name(*ctx,host);
 609         major=ssh_gssapi_init_ctx(*ctx, 0, GSS_C_NO_BUFFER, &token, NULL);
 610         gss_release_buffer(&minor,&token);
 611         return(major);
 612 }
 613
 614 #endif /* GSSAPI */