lib/libtelnet/kerberos5.c

   1 /*      $NetBSD: kerberos5.c,v 1.16 2006/03/19 22:56:36 christos Exp $  */
   2
   3 /*-
   4  * Copyright (c) 1991, 1993
   5  *      The Regents of the University of California.  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  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  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  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 /*
  33  * Copyright (C) 1990 by the Massachusetts Institute of Technology
  34  *
  35  * Export of this software from the United States of America may
  36  * require a specific license from the United States Government.
  37  * It is the responsibility of any person or organization contemplating
  38  * export to obtain such a license before exporting.
  39  *
  40  * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
  41  * distribute this software and its documentation for any purpose and
  42  * without fee is hereby granted, provided that the above copyright
  43  * notice appear in all copies and that both that copyright notice and
  44  * this permission notice appear in supporting documentation, and that
  45  * the name of M.I.T. not be used in advertising or publicity pertaining
  46  * to distribution of the software without specific, written prior
  47  * permission.  M.I.T. makes no representations about the suitability of
  48  * this software for any purpose.  It is provided "as is" without express
  49  * or implied warranty.
  50  */
  51
  52 #ifdef  KRB5
  53 #include <arpa/telnet.h>
  54 #include <stdio.h>
  55 #include <stdlib.h>
  56 #include <string.h>
  57 #include <unistd.h>
  58 #include <netdb.h>
  59 #include <ctype.h>
  60 #include <pwd.h>
  61 #define Authenticator k5_Authenticator
  62 #include <krb5.h>
  63 #undef Authenticator
  64 /* #include <roken.h> */
  65
  66 #include "encrypt.h"
  67 #include "auth.h"
  68 #include "misc.h"
  69
  70 extern int net;
  71
  72 int forward_flags;      /* Flags get set in telnet/main.c on -f and -F */
  73 int got_forwarded_creds;/* Tell telnetd to pass -F or -f to login. */
  74
  75 int require_hwpreauth;
  76
  77 void kerberos5_forward(Authenticator *);
  78
  79 static unsigned char str_data[1024] = {IAC, SB, TELOPT_AUTHENTICATION, 0,
  80                                        AUTHTYPE_KERBEROS_V5,};
  81
  82 #define KRB_AUTH                0       /* Authentication data follows */
  83 #define KRB_REJECT              1       /* Rejected (reason might follow) */
  84 #define KRB_ACCEPT              2       /* Accepted */
  85 #define KRB_RESPONSE            3       /* Response for mutual auth. */
  86
  87 #define KRB_FORWARD             4       /* Forwarded credentials follow */
  88 #define KRB_FORWARD_ACCEPT      5       /* Forwarded credentials accepted */
  89 #define KRB_FORWARD_REJECT      6       /* Forwarded credentials rejected */
  90
  91 static krb5_data auth;
  92 static krb5_ticket *ticket;
  93
  94 krb5_context telnet_context;
  95 static krb5_auth_context auth_context;
  96
  97 static int
  98 Data(Authenticator *ap, int type, void *d, int c)
  99 {
 100         unsigned char *p = str_data + 4;
 101         unsigned char *cd = (unsigned char *) d;
 102
 103         if (c == -1)
 104                 c = strlen(cd);
 105
 106         if (auth_debug_mode) {
 107                 printf("%s:%d: [%d] (%d)",
 108                     str_data[3] == TELQUAL_IS ? ">>>IS" : ">>>REPLY",
 109                     str_data[3],
 110                     type, c);
 111                 printd(d, c);
 112                 printf("\r\n");
 113         }
 114         *p++ = ap->type;
 115         *p++ = ap->way;
 116         *p++ = type;
 117         while (c-- > 0) {
 118                 if ((*p++ = *cd++) == IAC)
 119                         *p++ = IAC;
 120         }
 121         *p++ = IAC;
 122         *p++ = SE;
 123         if (str_data[3] == TELQUAL_IS)
 124                 printsub('>', &str_data[2], p - &str_data[2]);
 125         return (telnet_net_write(str_data, p - str_data));
 126 }
 127
 128 int
 129 kerberos5_init(Authenticator *ap, int server)
 130 {
 131         krb5_error_code ret;
 132
 133         if (telnet_context == 0) {
 134                 ret = krb5_init_context(&telnet_context);
 135                 if (ret)
 136                         return 0;
 137         }
 138
 139         if (server) {
 140                 krb5_keytab kt;
 141                 krb5_kt_cursor cursor;
 142
 143                 ret = krb5_kt_default(telnet_context, &kt);
 144                 if (ret)
 145                         return 0;
 146
 147                 ret = krb5_kt_start_seq_get(telnet_context, kt, &cursor);
 148                 if (ret) {
 149                         krb5_kt_close(telnet_context, kt);
 150                         return 0;
 151                 }
 152                 krb5_kt_end_seq_get(telnet_context, kt, &cursor);
 153                 krb5_kt_close(telnet_context, kt);
 154
 155                 str_data[3] = TELQUAL_REPLY;
 156         } else
 157                 str_data[3] = TELQUAL_IS;
 158         return (1);
 159 }
 160
 161 int
 162 kerberos5_send(Authenticator *ap)
 163 {
 164         krb5_error_code ret;
 165         krb5_ccache ccache;
 166         int ap_opts;
 167         krb5_data cksum_data;
 168         char foo[2];
 169
 170         printf("[ Trying KERBEROS5 ... ]\r\n");
 171
 172         if (!UserNameRequested) {
 173                 if (auth_debug_mode) {
 174                         printf("Kerberos V5: no user name supplied\r\n");
 175                 }
 176                 return (0);
 177         }
 178         ret = krb5_cc_default(telnet_context, &ccache);
 179         if (ret) {
 180                 if (auth_debug_mode) {
 181                         printf(
 182                         "Kerberos V5: could not get default ccache: %s\r\n",
 183                             krb5_get_err_text(telnet_context, ret));
 184                 }
 185                 return (0);
 186         }
 187         if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL)
 188                 ap_opts = AP_OPTS_MUTUAL_REQUIRED;
 189         else
 190                 ap_opts = 0;
 191
 192         ap_opts |= AP_OPTS_USE_SUBKEY;
 193
 194         ret = krb5_auth_con_init(telnet_context, &auth_context);
 195         if (ret) {
 196                 if (auth_debug_mode) {
 197                         printf(
 198                         "Kerberos V5: krb5_auth_con_init failed: %s\r\n",
 199                             krb5_get_err_text(telnet_context, ret));
 200                 }
 201                 return (0);
 202         }
 203         ret = krb5_auth_con_setaddrs_from_fd(telnet_context,
 204             auth_context, &net);
 205         if (ret) {
 206                 if (auth_debug_mode) {
 207                         printf("Kerberos V5: "
 208                             "krb5_auth_con_setaddrs_from_fd failed: %s\r\n",
 209                             krb5_get_err_text(telnet_context, ret));
 210                 }
 211                 return (0);
 212         }
 213         krb5_auth_con_setkeytype(telnet_context, auth_context, KEYTYPE_DES);
 214
 215         foo[0] = ap->type;
 216         foo[1] = ap->way;
 217
 218         cksum_data.length = sizeof(foo);
 219         cksum_data.data = foo;
 220         ret = krb5_mk_req(telnet_context, &auth_context, ap_opts, "host",
 221             RemoteHostName, &cksum_data, ccache, &auth);
 222         if (ret) {
 223                 if (1 || auth_debug_mode) {
 224                         printf("Kerberos V5: mk_req failed (%s)\r\n",
 225                             krb5_get_err_text(telnet_context, ret));
 226                 }
 227                 return (0);
 228         }
 229
 230         if (!auth_sendname((unsigned char *) UserNameRequested,
 231                 strlen(UserNameRequested))) {
 232                 if (auth_debug_mode)
 233                         printf("Not enough room for user name\r\n");
 234                 return (0);
 235         }
 236         if (!Data(ap, KRB_AUTH, auth.data, auth.length)) {
 237                 if (auth_debug_mode)
 238                         printf("Not enough room for authentication data\r\n");
 239                 return (0);
 240         }
 241         if (auth_debug_mode) {
 242                 printf("Sent Kerberos V5 credentials to server\r\n");
 243         }
 244         return (1);
 245 }
 246
 247 void
 248 kerberos5_is(Authenticator * ap, unsigned char *data, int cnt)
 249 {
 250         krb5_error_code ret;
 251         krb5_data outbuf;
 252         krb5_keyblock *key_block;
 253         char *name;
 254         krb5_principal server;
 255         int zero = 0;
 256
 257         if (cnt-- < 1)
 258                 return;
 259         switch (*data++) {
 260         case KRB_AUTH:
 261                 auth.data = (char *) data;
 262                 auth.length = cnt;
 263
 264                 auth_context = NULL;
 265
 266                 ret = krb5_auth_con_init(telnet_context, &auth_context);
 267                 if (ret) {
 268                         Data(ap, KRB_REJECT, "krb5_auth_con_init failed", -1);
 269                         auth_finished(ap, AUTH_REJECT);
 270                         if (auth_debug_mode)
 271                                 printf("Kerberos V5: krb5_auth_con_init failed (%s)\r\n",
 272                                     krb5_get_err_text(telnet_context, ret));
 273                         return;
 274                 }
 275                 ret = krb5_auth_con_setaddrs_from_fd(telnet_context,
 276                     auth_context, &zero);
 277                 if (ret) {
 278                         Data(ap, KRB_REJECT, "krb5_auth_con_setaddrs_from_fd failed", -1);
 279                         auth_finished(ap, AUTH_REJECT);
 280                         if (auth_debug_mode)
 281                                 printf("Kerberos V5: "
 282                                     "krb5_auth_con_setaddrs_from_fd failed (%s)\r\n",
 283                                     krb5_get_err_text(telnet_context, ret));
 284                         return;
 285                 }
 286                 ret = krb5_sock_to_principal(telnet_context, 0, "host",
 287                     KRB5_NT_SRV_HST, &server);
 288                 if (ret) {
 289                         Data(ap, KRB_REJECT, "krb5_sock_to_principal failed", -1);
 290                         auth_finished(ap, AUTH_REJECT);
 291                         if (auth_debug_mode)
 292                                 printf("Kerberos V5: "
 293                                     "krb5_sock_to_principal failed (%s)\r\n",
 294                                     krb5_get_err_text(telnet_context, ret));
 295                         return;
 296                 }
 297                 ret = krb5_rd_req(telnet_context, &auth_context, &auth,
 298                     server, NULL, NULL, &ticket);
 299                 krb5_free_principal(telnet_context, server);
 300
 301                 if (ret) {
 302                         char *errbuf;
 303
 304                         asprintf(&errbuf,
 305                             "Read req failed: %s",
 306                             krb5_get_err_text(telnet_context, ret));
 307                         Data(ap, KRB_REJECT, errbuf, -1);
 308                         if (auth_debug_mode)
 309                                 printf("%s\r\n", errbuf);
 310                         free(errbuf);
 311                         return;
 312                 } {
 313                         char foo[2];
 314
 315                         foo[0] = ap->type;
 316                         foo[1] = ap->way;
 317
 318                         ret = krb5_verify_authenticator_checksum(telnet_context,
 319                             auth_context, foo, sizeof(foo));
 320
 321                         if (ret) {
 322                                 char *errbuf;
 323                                 asprintf(&errbuf, "Bad checksum: %s",
 324                                     krb5_get_err_text(telnet_context, ret));
 325                                 Data(ap, KRB_REJECT, errbuf, -1);
 326                                 if (auth_debug_mode)
 327                                         printf("%s\r\n", errbuf);
 328                                 free(errbuf);
 329                                 return;
 330                         }
 331                 }
 332                 ret = krb5_auth_con_getremotesubkey(telnet_context,
 333                     auth_context, &key_block);
 334
 335                 if (ret) {
 336                         Data(ap, KRB_REJECT, "krb5_auth_con_getremotesubkey failed", -1);
 337                         auth_finished(ap, AUTH_REJECT);
 338                         if (auth_debug_mode)
 339                                 printf("Kerberos V5: "
 340                                     "krb5_auth_con_getremotesubkey failed (%s)\r\n",
 341                                     krb5_get_err_text(telnet_context, ret));
 342                         return;
 343                 }
 344                 if (key_block == NULL) {
 345                         ret = krb5_auth_con_getkey(telnet_context,
 346                                                    auth_context,
 347                                                    &key_block);
 348                 }
 349                 if (ret) {
 350                         Data(ap, KRB_REJECT, "krb5_auth_con_getkey failed", -1);
 351                         auth_finished(ap, AUTH_REJECT);
 352                         if (auth_debug_mode)
 353                                 printf("Kerberos V5: "
 354                                        "krb5_auth_con_getkey failed (%s)\r\n",
 355                                        krb5_get_err_text(telnet_context, ret));
 356                         return;
 357                 }
 358                 if (key_block == NULL) {
 359                         Data(ap, KRB_REJECT, "no subkey received", -1);
 360                         auth_finished(ap, AUTH_REJECT);
 361                         if (auth_debug_mode)
 362                                 printf("Kerberos V5: "
 363                                        "krb5_auth_con_getremotesubkey returned NULL key\r\n");
 364                         return;
 365                 }
 366                 if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) {
 367                         ret = krb5_mk_rep(telnet_context,
 368                             auth_context, &outbuf);
 369                         if (ret) {
 370                                 Data(ap, KRB_REJECT,
 371                                     "krb5_mk_rep failed", -1);
 372                                 auth_finished(ap, AUTH_REJECT);
 373                                 if (auth_debug_mode)
 374                                         printf("Kerberos V5: "
 375                                             "krb5_mk_rep failed (%s)\r\n",
 376                                             krb5_get_err_text(telnet_context,
 377                                             ret));
 378                                 krb5_free_keyblock(telnet_context, key_block);
 379                                 return;
 380                         }
 381                         Data(ap, KRB_RESPONSE, outbuf.data, outbuf.length);
 382                 }
 383                 if (krb5_unparse_name(telnet_context, ticket->client, &name))
 384                         name = 0;
 385
 386                 if (UserNameRequested && krb5_kuserok(telnet_context,
 387                     ticket->client, UserNameRequested)) {
 388                         Data(ap, KRB_ACCEPT, name ? name : "", name ? -1 : 0);
 389                         if (auth_debug_mode) {
 390                                 printf("Kerberos5 identifies him as ``%s''\r\n",
 391                                     name ? name : "");
 392                         }
 393                         if (key_block->keytype == ETYPE_DES_CBC_MD5 ||
 394                             key_block->keytype == ETYPE_DES_CBC_MD4 ||
 395                             key_block->keytype == ETYPE_DES_CBC_CRC) {
 396                                 Session_Key skey;
 397
 398                                 skey.type = SK_DES;
 399                                 skey.length = 8;
 400                                 skey.data = key_block->keyvalue.data;
 401                                 encrypt_session_key(&skey, 0);
 402                         }
 403                 } else {
 404                         char *msg;
 405
 406                         asprintf(&msg, "user `%s' is not authorized to "
 407                             "login as `%s'",
 408                             name ? name : "<unknown>",
 409                             UserNameRequested ? UserNameRequested : "<nobody>");
 410                         if (msg == NULL)
 411                                 Data(ap, KRB_REJECT, NULL, 0);
 412                         else {
 413                                 Data(ap, KRB_REJECT, (void *) msg, -1);
 414                                 free(msg);
 415                         }
 416                         auth_finished(ap, AUTH_REJECT);
 417                         krb5_free_keyblock(telnet_context, key_block);
 418                         break;
 419                 }
 420                 auth_finished(ap, AUTH_USER);
 421                 krb5_free_keyblock(telnet_context, key_block);
 422                 break;
 423         case KRB_FORWARD:{
 424                         struct passwd pws, *pwd;
 425                         char pwbuf[1024];
 426                         char ccname[1024];      /* XXX */
 427                         krb5_data inbuf;
 428                         krb5_ccache ccache;
 429                         inbuf.data = (char *) data;
 430                         inbuf.length = cnt;
 431
 432                         if (getpwnam_r(UserNameRequested, &pws, pwbuf,
 433                             sizeof(pwbuf), &pwd) != 0 || pwd == NULL)
 434                                 break;
 435
 436                         snprintf(ccname, sizeof(ccname),
 437                             "FILE:/tmp/krb5cc_%u", pwd->pw_uid);
 438
 439                         ret = krb5_cc_resolve(telnet_context, ccname, &ccache);
 440                         if (ret) {
 441                                 if (auth_debug_mode)
 442                                         printf("Kerberos V5: could not get ccache: %s\r\n",
 443                                             krb5_get_err_text(telnet_context,
 444                                             ret));
 445                                 break;
 446                         }
 447                         ret = krb5_cc_initialize(telnet_context, ccache,
 448                             ticket->client);
 449                         if (ret) {
 450                                 if (auth_debug_mode)
 451                                         printf("Kerberos V5: could not init ccache: %s\r\n",
 452                                             krb5_get_err_text(telnet_context,
 453                                                 ret));
 454                                 break;
 455                         }
 456                         ret = krb5_rd_cred2(telnet_context, auth_context,
 457                             ccache, &inbuf);
 458                         if (ret) {
 459                                 char *errbuf;
 460
 461                                 asprintf(&errbuf,
 462                                     "Read forwarded creds failed: %s",
 463                                     krb5_get_err_text(telnet_context, ret));
 464                                 if (errbuf == NULL)
 465                                         Data(ap, KRB_FORWARD_REJECT, NULL, 0);
 466                                 else
 467                                         Data(ap, KRB_FORWARD_REJECT, errbuf, -1);
 468                                 if (auth_debug_mode)
 469                                         printf("Could not read forwarded credentials: %s\r\n",
 470                                             errbuf);
 471                                 free(errbuf);
 472                         } else
 473                                 Data(ap, KRB_FORWARD_ACCEPT, 0, 0);
 474                         chown(ccname + 5, pwd->pw_uid, -1);
 475                         if (auth_debug_mode)
 476                                 printf("Forwarded credentials obtained\r\n");
 477                         break;
 478                 }
 479         default:
 480                 if (auth_debug_mode)
 481                         printf("Unknown Kerberos option %d\r\n", data[-1]);
 482                 Data(ap, KRB_REJECT, 0, 0);
 483                 break;
 484         }
 485 }
 486
 487 void
 488 kerberos5_reply(Authenticator * ap, unsigned char *data, int cnt)
 489 {
 490         static int mutual_complete = 0;
 491
 492         if (cnt-- < 1)
 493                 return;
 494         switch (*data++) {
 495         case KRB_REJECT:
 496                 if (cnt > 0) {
 497                         printf("[ Kerberos V5 refuses authentication because %.*s ]\r\n",
 498                             cnt, data);
 499                 } else
 500                         printf("[ Kerberos V5 refuses authentication ]\r\n");
 501                 auth_send_retry();
 502                 return;
 503         case KRB_ACCEPT:{
 504                         krb5_error_code ret;
 505                         Session_Key skey;
 506                         krb5_keyblock *keyblock;
 507
 508                         if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL &&
 509                             !mutual_complete) {
 510                                 printf("[ Kerberos V5 accepted you, but didn't provide mutual authentication! ]\r\n");
 511                                 auth_send_retry();
 512                                 return;
 513                         }
 514                         if (cnt)
 515                                 printf("[ Kerberos V5 accepts you as ``%.*s'' ]\r\n", cnt, data);
 516                         else
 517                                 printf("[ Kerberos V5 accepts you ]\r\n");
 518
 519                         ret = krb5_auth_con_getlocalsubkey(telnet_context,
 520                             auth_context, &keyblock);
 521                         if (ret)
 522                                 ret = krb5_auth_con_getkey(telnet_context,
 523                                     auth_context, &keyblock);
 524                         if (ret) {
 525                                 printf("[ krb5_auth_con_getkey: %s ]\r\n",
 526                                     krb5_get_err_text(telnet_context, ret));
 527                                 auth_send_retry();
 528                                 return;
 529                         }
 530                         skey.type = SK_DES;
 531                         skey.length = 8;
 532                         skey.data = keyblock->keyvalue.data;
 533                         encrypt_session_key(&skey, 0);
 534                         krb5_free_keyblock(telnet_context, keyblock);
 535                         auth_finished(ap, AUTH_USER);
 536                         if (forward_flags & OPTS_FORWARD_CREDS)
 537                                 kerberos5_forward(ap);
 538                         break;
 539                 }
 540         case KRB_RESPONSE:
 541                 if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) {
 542                         /* the rest of the reply should contain a krb_ap_rep */
 543                         krb5_ap_rep_enc_part *reply;
 544                         krb5_data inbuf;
 545                         krb5_error_code ret;
 546
 547                         inbuf.length = cnt;
 548                         inbuf.data = (char *) data;
 549
 550                         ret = krb5_rd_rep(telnet_context,
 551                             auth_context, &inbuf, &reply);
 552                         if (ret) {
 553                                 printf("[ Mutual authentication failed: %s ]\r\n",
 554                                     krb5_get_err_text(telnet_context, ret));
 555                                 auth_send_retry();
 556                                 return;
 557                         }
 558                         krb5_free_ap_rep_enc_part(telnet_context, reply);
 559                         mutual_complete = 1;
 560                 }
 561                 return;
 562         case KRB_FORWARD_ACCEPT:
 563                 printf("[ Kerberos V5 accepted forwarded credentials ]\r\n");
 564                 return;
 565         case KRB_FORWARD_REJECT:
 566                 printf("[ Kerberos V5 refuses forwarded credentials because %.*s ]\r\n",
 567                     cnt, data);
 568                 return;
 569         default:
 570                 if (auth_debug_mode)
 571                         printf("Unknown Kerberos option %d\r\n", data[-1]);
 572                 return;
 573         }
 574 }
 575
 576 int
 577 kerberos5_status(Authenticator *ap, char *name, size_t l, int level)
 578 {
 579         if (level < AUTH_USER)
 580                 return (level);
 581
 582         if (UserNameRequested &&
 583             krb5_kuserok(telnet_context, ticket->client, UserNameRequested)) {
 584                 strlcpy(name, UserNameRequested, l);
 585                 return (AUTH_VALID);
 586         } else
 587                 return (AUTH_USER);
 588 }
 589 #define BUMP(buf, len)          while (*(buf)) {++(buf), --(len);}
 590 #define ADDC(buf, len, c)       if ((len) > 0) {*(buf)++ = (c); --(len);}
 591
 592 void
 593 kerberos5_printsub(unsigned char *data, int cnt, unsigned char *buf, int buflen)
 594 {
 595         int i;
 596
 597         buf[buflen - 1] = '\0'; /* make sure its NULL terminated */
 598         buflen -= 1;
 599
 600         switch (data[3]) {
 601         case KRB_REJECT:        /* Rejected (reason might follow) */
 602                 strlcpy((char *) buf, " REJECT ", buflen);
 603                 goto common;
 604
 605         case KRB_ACCEPT:        /* Accepted (name might follow) */
 606                 strlcpy((char *) buf, " ACCEPT ", buflen);
 607 common:
 608                 BUMP(buf, buflen);
 609                 if (cnt <= 4)
 610                         break;
 611                 ADDC(buf, buflen, '"');
 612                 for (i = 4; i < cnt; i++)
 613                         ADDC(buf, buflen, data[i]);
 614                 ADDC(buf, buflen, '"');
 615                 ADDC(buf, buflen, '\0');
 616                 break;
 617
 618
 619         case KRB_AUTH:          /* Authentication data follows */
 620                 strlcpy((char *) buf, " AUTH", buflen);
 621                 goto common2;
 622
 623         case KRB_RESPONSE:
 624                 strlcpy((char *) buf, " RESPONSE", buflen);
 625                 goto common2;
 626
 627         case KRB_FORWARD:       /* Forwarded credentials follow */
 628                 strlcpy((char *) buf, " FORWARD", buflen);
 629                 goto common2;
 630
 631         case KRB_FORWARD_ACCEPT:        /* Forwarded credentials accepted */
 632                 strlcpy((char *) buf, " FORWARD_ACCEPT", buflen);
 633                 goto common2;
 634
 635         case KRB_FORWARD_REJECT:        /* Forwarded credentials rejected */
 636                 /* (reason might follow) */
 637                 strlcpy((char *) buf, " FORWARD_REJECT", buflen);
 638                 goto common2;
 639
 640         default:
 641                 snprintf(buf, buflen, " %d (unknown)", data[3]);
 642 common2:
 643                 BUMP(buf, buflen);
 644                 for (i = 4; i < cnt; i++) {
 645                         snprintf(buf, buflen, " %d", data[i]);
 646                         BUMP(buf, buflen);
 647                 }
 648                 break;
 649         }
 650 }
 651
 652 void
 653 kerberos5_forward(Authenticator * ap)
 654 {
 655         krb5_error_code ret;
 656         krb5_ccache ccache;
 657         krb5_creds creds;
 658         krb5_kdc_flags flags;
 659         krb5_data out_data;
 660         krb5_principal principal;
 661
 662         ret = krb5_cc_default(telnet_context, &ccache);
 663         if (ret) {
 664                 if (auth_debug_mode)
 665                         printf("KerberosV5: could not get default ccache: %s\r\n",
 666                             krb5_get_err_text(telnet_context, ret));
 667                 return;
 668         }
 669         ret = krb5_cc_get_principal(telnet_context, ccache, &principal);
 670         if (ret) {
 671                 if (auth_debug_mode)
 672                         printf("KerberosV5: could not get principal: %s\r\n",
 673                             krb5_get_err_text(telnet_context, ret));
 674                 return;
 675         }
 676         memset(&creds, 0, sizeof(creds));
 677
 678         creds.client = principal;
 679
 680         ret = krb5_build_principal(telnet_context, &creds.server,
 681             strlen(principal->realm), principal->realm, "krbtgt",
 682             principal->realm, NULL);
 683
 684         if (ret) {
 685                 if (auth_debug_mode)
 686                         printf("KerberosV5: could not get principal: %s\r\n",
 687                             krb5_get_err_text(telnet_context, ret));
 688                 return;
 689         }
 690         creds.times.endtime = 0;
 691
 692         flags.i = 0;
 693         flags.b.forwarded = 1;
 694         if (forward_flags & OPTS_FORWARDABLE_CREDS)
 695                 flags.b.forwardable = 1;
 696
 697         ret = krb5_get_forwarded_creds(telnet_context, auth_context,
 698             ccache, flags.i, RemoteHostName, &creds, &out_data);
 699         if (ret) {
 700                 if (auth_debug_mode)
 701                         printf("Kerberos V5: error getting forwarded creds: %s\r\n",
 702                             krb5_get_err_text(telnet_context, ret));
 703                 return;
 704         }
 705         if (!Data(ap, KRB_FORWARD, out_data.data, out_data.length)) {
 706                 if (auth_debug_mode)
 707                         printf("Not enough room for authentication data\r\n");
 708         } else {
 709                 if (auth_debug_mode)
 710                         printf("Forwarded local Kerberos V5 credentials to server\r\n");
 711         }
 712 }
 713 #endif /* KRB5 */