lib/krb5/rd_req.c

   1
   2 /*
   3  * Copyright (c) 1997 - 2007 Kungliga Tekniska Högskolan
   4  * (Royal Institute of Technology, Stockholm, Sweden).
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  *
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  *
  18  * 3. Neither the name of the Institute nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include "krb5_locl.h"
  36
  37 static krb5_error_code
  38 decrypt_tkt_enc_part (krb5_context context,
  39                       krb5_keyblock *key,
  40                       EncryptedData *enc_part,
  41                       EncTicketPart *decr_part)
  42 {
  43     krb5_error_code ret;
  44     krb5_data plain;
  45     size_t len;
  46     krb5_crypto crypto;
  47
  48     ret = krb5_crypto_init(context, key, 0, &crypto);
  49     if (ret)
  50         return ret;
  51     ret = krb5_decrypt_EncryptedData (context,
  52                                       crypto,
  53                                       KRB5_KU_TICKET,
  54                                       enc_part,
  55                                       &plain);
  56     krb5_crypto_destroy(context, crypto);
  57     if (ret)
  58         return ret;
  59
  60     ret = decode_EncTicketPart(plain.data, plain.length, decr_part, &len);
  61     if (ret)
  62         krb5_set_error_message(context, ret,
  63                                N_("Failed to decode encrypted "
  64                                   "ticket part", ""));
  65     krb5_data_free (&plain);
  66     return ret;
  67 }
  68
  69 static krb5_error_code
  70 decrypt_authenticator (krb5_context context,
  71                        EncryptionKey *key,
  72                        EncryptedData *enc_part,
  73                        Authenticator *authenticator,
  74                        krb5_key_usage usage)
  75 {
  76     krb5_error_code ret;
  77     krb5_data plain;
  78     size_t len;
  79     krb5_crypto crypto;
  80
  81     ret = krb5_crypto_init(context, key, 0, &crypto);
  82     if (ret)
  83         return ret;
  84     ret = krb5_decrypt_EncryptedData (context,
  85                                       crypto,
  86                                       usage /* KRB5_KU_AP_REQ_AUTH */,
  87                                       enc_part,
  88                                       &plain);
  89     /* for backwards compatibility, also try the old usage */
  90     if (ret && usage == KRB5_KU_TGS_REQ_AUTH)
  91         ret = krb5_decrypt_EncryptedData (context,
  92                                           crypto,
  93                                           KRB5_KU_AP_REQ_AUTH,
  94                                           enc_part,
  95                                           &plain);
  96     krb5_crypto_destroy(context, crypto);
  97     if (ret)
  98         return ret;
  99
 100     ret = decode_Authenticator(plain.data, plain.length,
 101                                authenticator, &len);
 102     krb5_data_free (&plain);
 103     return ret;
 104 }
 105
 106 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 107 krb5_decode_ap_req(krb5_context context,
 108                    const krb5_data *inbuf,
 109                    krb5_ap_req *ap_req)
 110 {
 111     krb5_error_code ret;
 112     size_t len;
 113     ret = decode_AP_REQ(inbuf->data, inbuf->length, ap_req, &len);
 114     if (ret)
 115         return ret;
 116     if (ap_req->pvno != 5){
 117         free_AP_REQ(ap_req);
 118         krb5_clear_error_message (context);
 119         return KRB5KRB_AP_ERR_BADVERSION;
 120     }
 121     if (ap_req->msg_type != krb_ap_req){
 122         free_AP_REQ(ap_req);
 123         krb5_clear_error_message (context);
 124         return KRB5KRB_AP_ERR_MSG_TYPE;
 125     }
 126     if (ap_req->ticket.tkt_vno != 5){
 127         free_AP_REQ(ap_req);
 128         krb5_clear_error_message (context);
 129         return KRB5KRB_AP_ERR_BADVERSION;
 130     }
 131     return 0;
 132 }
 133
 134 static krb5_error_code
 135 check_transited(krb5_context context, Ticket *ticket, EncTicketPart *enc)
 136 {
 137     char **realms;
 138     unsigned int num_realms, n;
 139     krb5_error_code ret;
 140
 141     /*
 142      * Windows 2000 and 2003 uses this inside their TGT so it's normaly
 143      * not seen by others, however, samba4 joined with a Windows AD as
 144      * a Domain Controller gets exposed to this.
 145      */
 146     if(enc->transited.tr_type == 0 && enc->transited.contents.length == 0)
 147         return 0;
 148
 149     if(enc->transited.tr_type != DOMAIN_X500_COMPRESS)
 150         return KRB5KDC_ERR_TRTYPE_NOSUPP;
 151
 152     if(enc->transited.contents.length == 0)
 153         return 0;
 154
 155     ret = krb5_domain_x500_decode(context, enc->transited.contents,
 156                                   &realms, &num_realms,
 157                                   enc->crealm,
 158                                   ticket->realm);
 159     if(ret)
 160         return ret;
 161     ret = krb5_check_transited(context, enc->crealm,
 162                                ticket->realm,
 163                                realms, num_realms, NULL);
 164     for (n = 0; n < num_realms; n++)
 165         free(realms[n]);
 166     free(realms);
 167     return ret;
 168 }
 169
 170 static krb5_error_code
 171 find_etypelist(krb5_context context,
 172                krb5_auth_context auth_context,
 173                EtypeList *etypes)
 174 {
 175     krb5_error_code ret;
 176     krb5_data data;
 177
 178     ret = _krb5_get_ad(context, auth_context->authenticator->authorization_data, NULL, KRB5_AUTHDATA_GSS_API_ETYPE_NEGOTIATION, &data);
 179     if (ret)
 180         return 0;
 181
 182     ret = decode_EtypeList(data.data, data.length, etypes, NULL);
 183     krb5_data_free(&data);
 184     if (ret)
 185         krb5_clear_error_message(context);
 186
 187     return ret;
 188 }
 189
 190 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 191 krb5_decrypt_ticket(krb5_context context,
 192                     Ticket *ticket,
 193                     krb5_keyblock *key,
 194                     EncTicketPart *out,
 195                     krb5_flags flags)
 196 {
 197     EncTicketPart t;
 198     krb5_error_code ret;
 199     ret = decrypt_tkt_enc_part (context, key, &ticket->enc_part, &t);
 200     if (ret)
 201         return ret;
 202
 203     {
 204         krb5_timestamp now;
 205         time_t start = t.authtime;
 206
 207         krb5_timeofday (context, &now);
 208         if(t.starttime)
 209             start = *t.starttime;
 210         if(start - now > context->max_skew
 211            || (t.flags.invalid
 212                && !(flags & KRB5_VERIFY_AP_REQ_IGNORE_INVALID))) {
 213             free_EncTicketPart(&t);
 214             krb5_clear_error_message (context);
 215             return KRB5KRB_AP_ERR_TKT_NYV;
 216         }
 217         if(now - t.endtime > context->max_skew) {
 218             free_EncTicketPart(&t);
 219             krb5_clear_error_message (context);
 220             return KRB5KRB_AP_ERR_TKT_EXPIRED;
 221         }
 222
 223         if(!t.flags.transited_policy_checked) {
 224             ret = check_transited(context, ticket, &t);
 225             if(ret) {
 226                 free_EncTicketPart(&t);
 227                 return ret;
 228             }
 229         }
 230     }
 231
 232     if(out)
 233         *out = t;
 234     else
 235         free_EncTicketPart(&t);
 236     return 0;
 237 }
 238
 239 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 240 krb5_verify_authenticator_checksum(krb5_context context,
 241                                    krb5_auth_context ac,
 242                                    void *data,
 243                                    size_t len)
 244 {
 245     krb5_error_code ret;
 246     krb5_keyblock *key = NULL;
 247     krb5_authenticator authenticator;
 248     krb5_crypto crypto;
 249
 250     ret = krb5_auth_con_getauthenticator(context, ac, &authenticator);
 251     if (ret)
 252         return ret;
 253     if (authenticator->cksum == NULL) {
 254         ret = -17;
 255         goto out;
 256     }
 257     ret = krb5_auth_con_getkey(context, ac, &key);
 258     if (ret)
 259         goto out;
 260     ret = krb5_crypto_init(context, key, 0, &crypto);
 261     if (ret)
 262         goto out;
 263     ret = krb5_verify_checksum(context, crypto,
 264                                KRB5_KU_AP_REQ_AUTH_CKSUM,
 265                                data, len, authenticator->cksum);
 266     krb5_crypto_destroy(context, crypto);
 267 out:
 268     krb5_free_authenticator(context, &authenticator);
 269     krb5_free_keyblock(context, key);
 270     return ret;
 271 }
 272
 273
 274 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 275 krb5_verify_ap_req(krb5_context context,
 276                    krb5_auth_context *auth_context,
 277                    krb5_ap_req *ap_req,
 278                    krb5_const_principal server,
 279                    krb5_keyblock *keyblock,
 280                    krb5_flags flags,
 281                    krb5_flags *ap_req_options,
 282                    krb5_ticket **ticket)
 283 {
 284     return krb5_verify_ap_req2 (context,
 285                                 auth_context,
 286                                 ap_req,
 287                                 server,
 288                                 keyblock,
 289                                 flags,
 290                                 ap_req_options,
 291                                 ticket,
 292                                 KRB5_KU_AP_REQ_AUTH);
 293 }
 294
 295 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 296 krb5_verify_ap_req2(krb5_context context,
 297                     krb5_auth_context *auth_context,
 298                     krb5_ap_req *ap_req,
 299                     krb5_const_principal server,
 300                     krb5_keyblock *keyblock,
 301                     krb5_flags flags,
 302                     krb5_flags *ap_req_options,
 303                     krb5_ticket **ticket,
 304                     krb5_key_usage usage)
 305 {
 306     krb5_ticket *t;
 307     krb5_auth_context ac;
 308     krb5_error_code ret;
 309     EtypeList etypes;
 310
 311     memset(&etypes, 0, sizeof(etypes));
 312
 313     if (ticket)
 314         *ticket = NULL;
 315
 316     if (auth_context && *auth_context) {
 317         ac = *auth_context;
 318     } else {
 319         ret = krb5_auth_con_init (context, &ac);
 320         if (ret)
 321             return ret;
 322     }
 323
 324     t = calloc(1, sizeof(*t));
 325     if (t == NULL) {
 326         ret = krb5_enomem(context);
 327         goto out;
 328     }
 329
 330     if (ap_req->ap_options.use_session_key && ac->keyblock){
 331         ret = krb5_decrypt_ticket(context, &ap_req->ticket,
 332                                   ac->keyblock,
 333                                   &t->ticket,
 334                                   flags);
 335         krb5_free_keyblock(context, ac->keyblock);
 336         ac->keyblock = NULL;
 337     }else
 338         ret = krb5_decrypt_ticket(context, &ap_req->ticket,
 339                                   keyblock,
 340                                   &t->ticket,
 341                                   flags);
 342
 343     if(ret)
 344         goto out;
 345
 346     ret = _krb5_principalname2krb5_principal(context,
 347                                              &t->server,
 348                                              ap_req->ticket.sname,
 349                                              ap_req->ticket.realm);
 350     if (ret) goto out;
 351     ret = _krb5_principalname2krb5_principal(context,
 352                                              &t->client,
 353                                              t->ticket.cname,
 354                                              t->ticket.crealm);
 355     if (ret) goto out;
 356
 357     ret = decrypt_authenticator (context,
 358                                  &t->ticket.key,
 359                                  &ap_req->authenticator,
 360                                  ac->authenticator,
 361                                  usage);
 362     if (ret)
 363         goto out;
 364
 365     {
 366         krb5_principal p1, p2;
 367         krb5_boolean res;
 368
 369         _krb5_principalname2krb5_principal(context,
 370                                            &p1,
 371                                            ac->authenticator->cname,
 372                                            ac->authenticator->crealm);
 373         _krb5_principalname2krb5_principal(context,
 374                                            &p2,
 375                                            t->ticket.cname,
 376                                            t->ticket.crealm);
 377         res = krb5_principal_compare (context, p1, p2);
 378         krb5_free_principal (context, p1);
 379         krb5_free_principal (context, p2);
 380         if (!res) {
 381             ret = KRB5KRB_AP_ERR_BADMATCH;
 382             krb5_clear_error_message (context);
 383             goto out;
 384         }
 385     }
 386
 387     /* check addresses */
 388
 389     if (t->ticket.caddr
 390         && ac->remote_address
 391         && !krb5_address_search (context,
 392                                  ac->remote_address,
 393                                  t->ticket.caddr)) {
 394         ret = KRB5KRB_AP_ERR_BADADDR;
 395         krb5_clear_error_message (context);
 396         goto out;
 397     }
 398
 399     /* check timestamp in authenticator */
 400     {
 401         krb5_timestamp now;
 402
 403         krb5_timeofday (context, &now);
 404
 405         if (labs(ac->authenticator->ctime - now) > context->max_skew) {
 406             ret = KRB5KRB_AP_ERR_SKEW;
 407             krb5_clear_error_message (context);
 408             goto out;
 409         }
 410     }
 411
 412     if (ac->authenticator->seq_number)
 413         krb5_auth_con_setremoteseqnumber(context, ac,
 414                                          *ac->authenticator->seq_number);
 415
 416     /* XXX - Xor sequence numbers */
 417
 418     if (ac->authenticator->subkey) {
 419         ret = krb5_auth_con_setremotesubkey(context, ac,
 420                                             ac->authenticator->subkey);
 421         if (ret)
 422             goto out;
 423     }
 424
 425     ret = find_etypelist(context, ac, &etypes);
 426     if (ret)
 427         goto out;
 428
 429     ac->keytype = ETYPE_NULL;
 430
 431     if (etypes.val) {
 432         size_t i;
 433
 434         for (i = 0; i < etypes.len; i++) {
 435             if (krb5_enctype_valid(context, etypes.val[i]) == 0) {
 436                 ac->keytype = etypes.val[i];
 437                 break;
 438             }
 439         }
 440     }
 441
 442     /* save key */
 443     ret = krb5_copy_keyblock(context, &t->ticket.key, &ac->keyblock);
 444     if (ret) goto out;
 445
 446     if (ap_req_options) {
 447         *ap_req_options = 0;
 448         if (ac->keytype != (krb5_enctype)ETYPE_NULL)
 449             *ap_req_options |= AP_OPTS_USE_SUBKEY;
 450         if (ap_req->ap_options.use_session_key)
 451             *ap_req_options |= AP_OPTS_USE_SESSION_KEY;
 452         if (ap_req->ap_options.mutual_required)
 453             *ap_req_options |= AP_OPTS_MUTUAL_REQUIRED;
 454     }
 455
 456     if(ticket)
 457         *ticket = t;
 458     else
 459         krb5_free_ticket (context, t);
 460     if (auth_context) {
 461         if (*auth_context == NULL)
 462             *auth_context = ac;
 463     } else
 464         krb5_auth_con_free (context, ac);
 465     free_EtypeList(&etypes);
 466     return 0;
 467  out:
 468     free_EtypeList(&etypes);
 469     if (t)
 470         krb5_free_ticket (context, t);
 471     if (auth_context == NULL || *auth_context == NULL)
 472         krb5_auth_con_free (context, ac);
 473     return ret;
 474 }
 475
 476 /*
 477  *
 478  */
 479
 480 struct krb5_rd_req_in_ctx_data {
 481     krb5_keytab keytab;
 482     krb5_keyblock *keyblock;
 483     krb5_boolean check_pac;
 484 };
 485
 486 struct krb5_rd_req_out_ctx_data {
 487     krb5_keyblock *keyblock;
 488     krb5_flags ap_req_options;
 489     krb5_ticket *ticket;
 490     krb5_principal server;
 491 };
 492
 493 /**
 494  * Allocate a krb5_rd_req_in_ctx as an input parameter to
 495  * krb5_rd_req_ctx(). The caller should free the context with
 496  * krb5_rd_req_in_ctx_free() when done with the context.
 497  *
 498  * @param context Keberos 5 context.
 499  * @param ctx in ctx to krb5_rd_req_ctx().
 500  *
 501  * @return Kerberos 5 error code, see krb5_get_error_message().
 502  *
 503  * @ingroup krb5_auth
 504  */
 505
 506 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 507 krb5_rd_req_in_ctx_alloc(krb5_context context, krb5_rd_req_in_ctx *ctx)
 508 {
 509     *ctx = calloc(1, sizeof(**ctx));
 510     if (*ctx == NULL)
 511         return krb5_enomem(context);
 512     (*ctx)->check_pac = (context->flags & KRB5_CTX_F_CHECK_PAC) ? 1 : 0;
 513     return 0;
 514 }
 515
 516 /**
 517  * Set the keytab that krb5_rd_req_ctx() will use.
 518  *
 519  * @param context Keberos 5 context.
 520  * @param in in ctx to krb5_rd_req_ctx().
 521  * @param keytab keytab that krb5_rd_req_ctx() will use, only copy the
 522  *        pointer, so the caller must free they keytab after
 523  *        krb5_rd_req_in_ctx_free() is called.
 524  *
 525  * @return Kerberos 5 error code, see krb5_get_error_message().
 526  *
 527  * @ingroup krb5_auth
 528  */
 529
 530 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 531 krb5_rd_req_in_set_keytab(krb5_context context,
 532                           krb5_rd_req_in_ctx in,
 533                           krb5_keytab keytab)
 534 {
 535     in->keytab = keytab;
 536     return 0;
 537 }
 538
 539 /**
 540  * Set if krb5_rq_red() is going to check the Windows PAC or not
 541  *
 542  * @param context Keberos 5 context.
 543  * @param in krb5_rd_req_in_ctx to check the option on.
 544  * @param flag flag to select if to check the pac (TRUE) or not (FALSE).
 545  *
 546  * @return Kerberos 5 error code, see krb5_get_error_message().
 547  *
 548  * @ingroup krb5_auth
 549  */
 550
 551 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 552 krb5_rd_req_in_set_pac_check(krb5_context context,
 553                              krb5_rd_req_in_ctx in,
 554                              krb5_boolean flag)
 555 {
 556     in->check_pac = flag;
 557     return 0;
 558 }
 559
 560
 561 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 562 krb5_rd_req_in_set_keyblock(krb5_context context,
 563                             krb5_rd_req_in_ctx in,
 564                             krb5_keyblock *keyblock)
 565 {
 566     in->keyblock = keyblock; /* XXX should make copy */
 567     return 0;
 568 }
 569
 570 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 571 krb5_rd_req_out_get_ap_req_options(krb5_context context,
 572                                    krb5_rd_req_out_ctx out,
 573                                    krb5_flags *ap_req_options)
 574 {
 575     *ap_req_options = out->ap_req_options;
 576     return 0;
 577 }
 578
 579 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 580 krb5_rd_req_out_get_ticket(krb5_context context,
 581                             krb5_rd_req_out_ctx out,
 582                             krb5_ticket **ticket)
 583 {
 584     return krb5_copy_ticket(context, out->ticket, ticket);
 585 }
 586
 587 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 588 krb5_rd_req_out_get_keyblock(krb5_context context,
 589                             krb5_rd_req_out_ctx out,
 590                             krb5_keyblock **keyblock)
 591 {
 592     return krb5_copy_keyblock(context, out->keyblock, keyblock);
 593 }
 594
 595 /**
 596  * Get the principal that was used in the request from the
 597  * client. Might not match whats in the ticket if krb5_rd_req_ctx()
 598  * searched in the keytab for a matching key.
 599  *
 600  * @param context a Kerberos 5 context.
 601  * @param out a krb5_rd_req_out_ctx from krb5_rd_req_ctx().
 602  * @param principal return principal, free with krb5_free_principal().
 603  *
 604  * @ingroup krb5_auth
 605  */
 606
 607 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 608 krb5_rd_req_out_get_server(krb5_context context,
 609                             krb5_rd_req_out_ctx out,
 610                             krb5_principal *principal)
 611 {
 612     return krb5_copy_principal(context, out->server, principal);
 613 }
 614
 615 KRB5_LIB_FUNCTION void KRB5_LIB_CALL
 616 krb5_rd_req_in_ctx_free(krb5_context context, krb5_rd_req_in_ctx ctx)
 617 {
 618     free(ctx);
 619 }
 620
 621 /**
 622  * Free the krb5_rd_req_out_ctx.
 623  *
 624  * @param context Keberos 5 context.
 625  * @param ctx krb5_rd_req_out_ctx context to free.
 626  *
 627  * @ingroup krb5_auth
 628  */
 629
 630 KRB5_LIB_FUNCTION void KRB5_LIB_CALL
 631 krb5_rd_req_out_ctx_free(krb5_context context, krb5_rd_req_out_ctx ctx)
 632 {
 633     if (ctx->ticket)
 634         krb5_free_ticket(context, ctx->ticket);
 635     if (ctx->keyblock)
 636         krb5_free_keyblock(context, ctx->keyblock);
 637     if (ctx->server)
 638         krb5_free_principal(context, ctx->server);
 639     free(ctx);
 640 }
 641
 642 /**
 643  * Process an AP_REQ message.
 644  *
 645  * @param context        Kerberos 5 context.
 646  * @param auth_context   authentication context of the peer.
 647  * @param inbuf          the AP_REQ message, obtained for example with krb5_read_message().
 648  * @param server         server principal.
 649  * @param keytab         server keytab.
 650  * @param ap_req_options set to the AP_REQ options. See the AP_OPTS_* defines.
 651  * @param ticket         on success, set to the authenticated client credentials.
 652  *                       Must be deallocated with krb5_free_ticket(). If not
 653  *                       interested, pass a NULL value.
 654  *
 655  * @return 0 to indicate success. Otherwise a Kerberos error code is
 656  *         returned, see krb5_get_error_message().
 657  */
 658 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 659 krb5_rd_req(krb5_context context,
 660             krb5_auth_context *auth_context,
 661             const krb5_data *inbuf,
 662             krb5_const_principal server,
 663             krb5_keytab keytab,
 664             krb5_flags *ap_req_options,
 665             krb5_ticket **ticket)
 666 {
 667     krb5_error_code ret;
 668     krb5_rd_req_in_ctx in;
 669     krb5_rd_req_out_ctx out;
 670
 671     ret = krb5_rd_req_in_ctx_alloc(context, &in);
 672     if (ret)
 673         return ret;
 674
 675     ret = krb5_rd_req_in_set_keytab(context, in, keytab);
 676     if (ret) {
 677         krb5_rd_req_in_ctx_free(context, in);
 678         return ret;
 679     }
 680
 681     ret = krb5_rd_req_ctx(context, auth_context, inbuf, server, in, &out);
 682     krb5_rd_req_in_ctx_free(context, in);
 683     if (ret)
 684         return ret;
 685
 686     if (ap_req_options)
 687         *ap_req_options = out->ap_req_options;
 688     if (ticket) {
 689         ret = krb5_copy_ticket(context, out->ticket, ticket);
 690         if (ret)
 691             goto out;
 692     }
 693
 694 out:
 695     krb5_rd_req_out_ctx_free(context, out);
 696     return ret;
 697 }
 698
 699 /*
 700  *
 701  */
 702
 703 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 704 krb5_rd_req_with_keyblock(krb5_context context,
 705                           krb5_auth_context *auth_context,
 706                           const krb5_data *inbuf,
 707                           krb5_const_principal server,
 708                           krb5_keyblock *keyblock,
 709                           krb5_flags *ap_req_options,
 710                           krb5_ticket **ticket)
 711 {
 712     krb5_error_code ret;
 713     krb5_rd_req_in_ctx in;
 714     krb5_rd_req_out_ctx out;
 715
 716     ret = krb5_rd_req_in_ctx_alloc(context, &in);
 717     if (ret)
 718         return ret;
 719
 720     ret = krb5_rd_req_in_set_keyblock(context, in, keyblock);
 721     if (ret) {
 722         krb5_rd_req_in_ctx_free(context, in);
 723         return ret;
 724     }
 725
 726     ret = krb5_rd_req_ctx(context, auth_context, inbuf, server, in, &out);
 727     krb5_rd_req_in_ctx_free(context, in);
 728     if (ret)
 729         return ret;
 730
 731     if (ap_req_options)
 732         *ap_req_options = out->ap_req_options;
 733     if (ticket) {
 734         ret = krb5_copy_ticket(context, out->ticket, ticket);
 735         if (ret)
 736             goto out;
 737     }
 738
 739 out:
 740     krb5_rd_req_out_ctx_free(context, out);
 741     return ret;
 742 }
 743
 744 /*
 745  *
 746  */
 747
 748 static krb5_error_code
 749 get_key_from_keytab(krb5_context context,
 750                     krb5_ap_req *ap_req,
 751                     krb5_const_principal server,
 752                     krb5_keytab keytab,
 753                     krb5_keyblock **out_key)
 754 {
 755     krb5_keytab_entry entry;
 756     krb5_error_code ret;
 757     int kvno;
 758     krb5_keytab real_keytab;
 759
 760     if(keytab == NULL)
 761         krb5_kt_default(context, &real_keytab);
 762     else
 763         real_keytab = keytab;
 764
 765     if (ap_req->ticket.enc_part.kvno)
 766         kvno = *ap_req->ticket.enc_part.kvno;
 767     else
 768         kvno = 0;
 769
 770     ret = krb5_kt_get_entry (context,
 771                              real_keytab,
 772                              server,
 773                              kvno,
 774                              ap_req->ticket.enc_part.etype,
 775                              &entry);
 776     if(ret)
 777         goto out;
 778     ret = krb5_copy_keyblock(context, &entry.keyblock, out_key);
 779     krb5_kt_free_entry (context, &entry);
 780 out:
 781     if(keytab == NULL)
 782         krb5_kt_close(context, real_keytab);
 783
 784     return ret;
 785 }
 786
 787 /**
 788  * The core server function that verify application authentication
 789  * requests from clients.
 790  *
 791  * @param context Keberos 5 context.
 792  * @param auth_context the authentication context, can be NULL, then
 793  *        default values for the authentication context will used.
 794  * @param inbuf the (AP-REQ) authentication buffer
 795  *
 796  * @param server the server to authenticate to. If NULL the function
 797  *        will try to find any available credential in the keytab
 798  *        that will verify the reply. The function will prefer the
 799  *        server specified in the AP-REQ, but if
 800  *        there is no mach, it will try all keytab entries for a
 801  *        match. This has serious performance issues for large keytabs.
 802  *
 803  * @param inctx control the behavior of the function, if NULL, the
 804  *        default behavior is used.
 805  * @param outctx the return outctx, free with krb5_rd_req_out_ctx_free().
 806  * @return Kerberos 5 error code, see krb5_get_error_message().
 807  *
 808  * @ingroup krb5_auth
 809  */
 810
 811 KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
 812 krb5_rd_req_ctx(krb5_context context,
 813                 krb5_auth_context *auth_context,
 814                 const krb5_data *inbuf,
 815                 krb5_const_principal server,
 816                 krb5_rd_req_in_ctx inctx,
 817                 krb5_rd_req_out_ctx *outctx)
 818 {
 819     krb5_error_code ret;
 820     krb5_ap_req ap_req;
 821     krb5_rd_req_out_ctx o = NULL;
 822     krb5_keytab id = NULL, keytab = NULL;
 823     krb5_principal service = NULL;
 824
 825     *outctx = NULL;
 826
 827     o = calloc(1, sizeof(*o));
 828     if (o == NULL)
 829         return krb5_enomem(context);
 830
 831     if (*auth_context == NULL) {
 832         ret = krb5_auth_con_init(context, auth_context);
 833         if (ret)
 834             goto out;
 835     }
 836
 837     ret = krb5_decode_ap_req(context, inbuf, &ap_req);
 838     if(ret)
 839         goto out;
 840
 841     /* Save the principal that was in the request */
 842     ret = _krb5_principalname2krb5_principal(context,
 843                                              &o->server,
 844                                              ap_req.ticket.sname,
 845                                              ap_req.ticket.realm);
 846     if (ret)
 847         goto out;
 848
 849     if (ap_req.ap_options.use_session_key &&
 850         (*auth_context)->keyblock == NULL) {
 851         ret = KRB5KRB_AP_ERR_NOKEY;
 852         krb5_set_error_message(context, ret,
 853                                N_("krb5_rd_req: user to user auth "
 854                                   "without session key given", ""));
 855         goto out;
 856     }
 857
 858     if (inctx && inctx->keytab)
 859         id = inctx->keytab;
 860
 861     if((*auth_context)->keyblock){
 862         ret = krb5_copy_keyblock(context,
 863                                  (*auth_context)->keyblock,
 864                                  &o->keyblock);
 865         if (ret)
 866             goto out;
 867     } else if(inctx && inctx->keyblock){
 868         ret = krb5_copy_keyblock(context,
 869                                  inctx->keyblock,
 870                                  &o->keyblock);
 871         if (ret)
 872             goto out;
 873     } else {
 874
 875         if(id == NULL) {
 876             krb5_kt_default(context, &keytab);
 877             id = keytab;
 878         }
 879         if (id == NULL)
 880             goto out;
 881
 882         if (server == NULL) {
 883             ret = _krb5_principalname2krb5_principal(context,
 884                                                      &service,
 885                                                      ap_req.ticket.sname,
 886                                                      ap_req.ticket.realm);
 887             if (ret)
 888                 goto out;
 889             server = service;
 890         }
 891
 892         ret = get_key_from_keytab(context,
 893                                   &ap_req,
 894                                   server,
 895                                   id,
 896                                   &o->keyblock);
 897         if (ret) {
 898             /* If caller specified a server, fail. */
 899             if (service == NULL && (context->flags & KRB5_CTX_F_RD_REQ_IGNORE) == 0)
 900                 goto out;
 901             /* Otherwise, fall back to iterating over the keytab. This
 902              * have serious performace issues for larger keytab.
 903              */
 904             o->keyblock = NULL;
 905         }
 906     }
 907
 908     if (o->keyblock) {
 909         /*
 910          * We got an exact keymatch, use that.
 911          */
 912
 913         ret = krb5_verify_ap_req2(context,
 914                                   auth_context,
 915                                   &ap_req,
 916                                   server,
 917                                   o->keyblock,
 918                                   0,
 919                                   &o->ap_req_options,
 920                                   &o->ticket,
 921                                   KRB5_KU_AP_REQ_AUTH);
 922
 923         if (ret)
 924             goto out;
 925
 926     } else {
 927         /*
 928          * Interate over keytab to find a key that can decrypt the request.
 929          */
 930
 931         krb5_keytab_entry entry;
 932         krb5_kt_cursor cursor;
 933         int done = 0, kvno = 0;
 934
 935         memset(&cursor, 0, sizeof(cursor));
 936
 937         if (ap_req.ticket.enc_part.kvno)
 938             kvno = *ap_req.ticket.enc_part.kvno;
 939
 940         ret = krb5_kt_start_seq_get(context, id, &cursor);
 941         if (ret)
 942             goto out;
 943
 944         done = 0;
 945         while (!done) {
 946             krb5_principal p;
 947
 948             ret = krb5_kt_next_entry(context, id, &entry, &cursor);
 949             if (ret) {
 950                 _krb5_kt_principal_not_found(context, ret, id, o->server,
 951                                              ap_req.ticket.enc_part.etype,
 952                                              kvno);
 953                 break;
 954             }
 955
 956             if (entry.keyblock.keytype != ap_req.ticket.enc_part.etype) {
 957                 krb5_kt_free_entry (context, &entry);
 958                 continue;
 959             }
 960
 961             ret = krb5_verify_ap_req2(context,
 962                                       auth_context,
 963                                       &ap_req,
 964                                       server,
 965                                       &entry.keyblock,
 966                                       0,
 967                                       &o->ap_req_options,
 968                                       &o->ticket,
 969                                       KRB5_KU_AP_REQ_AUTH);
 970             if (ret) {
 971                 krb5_kt_free_entry (context, &entry);
 972                 continue;
 973             }
 974
 975             /*
 976              * Found a match, save the keyblock for PAC processing,
 977              * and update the service principal in the ticket to match
 978              * whatever is in the keytab.
 979              */
 980
 981             ret = krb5_copy_keyblock(context,
 982                                      &entry.keyblock,
 983                                      &o->keyblock);
 984             if (ret) {
 985                 krb5_kt_free_entry (context, &entry);
 986                 break;
 987             }
 988
 989             ret = krb5_copy_principal(context, entry.principal, &p);
 990             if (ret) {
 991                 krb5_kt_free_entry (context, &entry);
 992                 break;
 993             }
 994             krb5_free_principal(context, o->ticket->server);
 995             o->ticket->server = p;
 996
 997             krb5_kt_free_entry (context, &entry);
 998
 999             done = 1;
1000         }
1001         krb5_kt_end_seq_get (context, id, &cursor);
1002         if (ret)
1003             goto out;
1004     }
1005
1006     /* If there is a PAC, verify its server signature */
1007     if (inctx == NULL || inctx->check_pac) {
1008         krb5_pac pac;
1009         krb5_data data;
1010
1011         ret = krb5_ticket_get_authorization_data_type(context,
1012                                                       o->ticket,
1013                                                       KRB5_AUTHDATA_WIN2K_PAC,
1014                                                       &data);
1015         if (ret == 0) {
1016             ret = krb5_pac_parse(context, data.data, data.length, &pac);
1017             krb5_data_free(&data);
1018             if (ret)
1019                 goto out;
1020
1021             ret = krb5_pac_verify(context,
1022                                   pac,
1023                                   o->ticket->ticket.authtime,
1024                                   o->ticket->client,
1025                                   o->keyblock,
1026                                   NULL);
1027             krb5_pac_free(context, pac);
1028             if (ret)
1029                 goto out;
1030         } else
1031           ret = 0;
1032     }
1033 out:
1034
1035     if (ret || outctx == NULL) {
1036         krb5_rd_req_out_ctx_free(context, o);
1037     } else
1038         *outctx = o;
1039
1040     free_AP_REQ(&ap_req);
1041
1042     if (service)
1043         krb5_free_principal(context, service);
1044
1045     if (keytab)
1046         krb5_kt_close(context, keytab);
1047
1048     return ret;
1049 }