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kerberos5.c revision 1.8
      1 /*	$NetBSD: kerberos5.c,v 1.8 2001/09/17 12:34:43 assar 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. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 /*
     37  * Copyright (C) 1990 by the Massachusetts Institute of Technology
     38  *
     39  * Export of this software from the United States of America may
     40  * require a specific license from the United States Government.
     41  * It is the responsibility of any person or organization contemplating
     42  * export to obtain such a license before exporting.
     43  *
     44  * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
     45  * distribute this software and its documentation for any purpose and
     46  * without fee is hereby granted, provided that the above copyright
     47  * notice appear in all copies and that both that copyright notice and
     48  * this permission notice appear in supporting documentation, and that
     49  * the name of M.I.T. not be used in advertising or publicity pertaining
     50  * to distribution of the software without specific, written prior
     51  * permission.  M.I.T. makes no representations about the suitability of
     52  * this software for any purpose.  It is provided "as is" without express
     53  * or implied warranty.
     54  */
     55 
     56 #ifdef	KRB5
     57 #include <arpa/telnet.h>
     58 #include <stdio.h>
     59 #include <stdlib.h>
     60 #include <string.h>
     61 #include <unistd.h>
     62 #include <netdb.h>
     63 #include <ctype.h>
     64 #include <pwd.h>
     65 #define Authenticator k5_Authenticator
     66 #include <krb5.h>
     67 #undef Authenticator
     68 /* #include <roken.h> */
     69 
     70 #include "encrypt.h"
     71 #include "auth.h"
     72 #include "misc.h"
     73 
     74 extern int net;
     75 
     76 int forward_flags;	/* Flags get set in telnet/main.c on -f and -F */
     77 int got_forwarded_creds;/* Tell telnetd to pass -F or -f to login. */
     78 
     79 int require_hwpreauth;
     80 
     81 void kerberos5_forward(Authenticator *);
     82 
     83 static unsigned char str_data[1024] = {IAC, SB, TELOPT_AUTHENTICATION, 0,
     84 				       AUTHTYPE_KERBEROS_V5,};
     85 
     86 #define	KRB_AUTH		0	/* Authentication data follows */
     87 #define	KRB_REJECT		1	/* Rejected (reason might follow) */
     88 #define	KRB_ACCEPT		2	/* Accepted */
     89 #define	KRB_RESPONSE		3	/* Response for mutual auth. */
     90 
     91 #define KRB_FORWARD     	4	/* Forwarded credentials follow */
     92 #define KRB_FORWARD_ACCEPT     	5	/* Forwarded credentials accepted */
     93 #define KRB_FORWARD_REJECT     	6	/* Forwarded credentials rejected */
     94 
     95 static krb5_data auth;
     96 static krb5_ticket *ticket;
     97 
     98 krb5_context telnet_context;
     99 static krb5_auth_context auth_context;
    100 
    101 static int
    102 Data(Authenticator *ap, int type, void *d, int c)
    103 {
    104 	unsigned char *p = str_data + 4;
    105 	unsigned char *cd = (unsigned char *) d;
    106 
    107 	if (c == -1)
    108 		c = strlen(cd);
    109 
    110 	if (auth_debug_mode) {
    111 		printf("%s:%d: [%d] (%d)",
    112 		    str_data[3] == TELQUAL_IS ? ">>>IS" : ">>>REPLY",
    113 		    str_data[3],
    114 		    type, c);
    115 		printd(d, c);
    116 		printf("\r\n");
    117 	}
    118 	*p++ = ap->type;
    119 	*p++ = ap->way;
    120 	*p++ = type;
    121 	while (c-- > 0) {
    122 		if ((*p++ = *cd++) == IAC)
    123 			*p++ = IAC;
    124 	}
    125 	*p++ = IAC;
    126 	*p++ = SE;
    127 	if (str_data[3] == TELQUAL_IS)
    128 		printsub('>', &str_data[2], p - &str_data[2]);
    129 	return (telnet_net_write(str_data, p - str_data));
    130 }
    131 
    132 int
    133 kerberos5_init(Authenticator *ap, int server)
    134 {
    135 	krb5_error_code ret;
    136 
    137 	if (telnet_context == 0) {
    138 		ret = krb5_init_context(&telnet_context);
    139 		if (ret)
    140 			return 0;
    141 	}
    142 
    143 	if (server) {
    144 		krb5_keytab kt;
    145 		krb5_kt_cursor cursor;
    146 
    147 		ret = krb5_kt_default(telnet_context, &kt);
    148 		if (ret)
    149 			return 0;
    150 
    151 		ret = krb5_kt_start_seq_get(telnet_context, kt, &cursor);
    152 		if (ret) {
    153 			krb5_kt_close(telnet_context, kt);
    154 			return 0;
    155 		}
    156 		krb5_kt_end_seq_get(telnet_context, kt, &cursor);
    157 		krb5_kt_close(telnet_context, kt);
    158 
    159 		str_data[3] = TELQUAL_REPLY;
    160 	} else
    161 		str_data[3] = TELQUAL_IS;
    162 	return (1);
    163 }
    164 
    165 int
    166 kerberos5_send(Authenticator *ap)
    167 {
    168 	krb5_error_code ret;
    169 	krb5_ccache ccache;
    170 	int ap_opts;
    171 	krb5_data cksum_data;
    172 	char foo[2];
    173 
    174 	printf("[ Trying KERBEROS5 ... ]\r\n");
    175 
    176 	if (!UserNameRequested) {
    177 		if (auth_debug_mode) {
    178 			printf("Kerberos V5: no user name supplied\r\n");
    179 		}
    180 		return (0);
    181 	}
    182 	ret = krb5_cc_default(telnet_context, &ccache);
    183 	if (ret) {
    184 		if (auth_debug_mode) {
    185 			printf(
    186 			"Kerberos V5: could not get default ccache: %s\r\n",
    187 			    krb5_get_err_text(telnet_context, ret));
    188 		}
    189 		return (0);
    190 	}
    191 	if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL)
    192 		ap_opts = AP_OPTS_MUTUAL_REQUIRED;
    193 	else
    194 		ap_opts = 0;
    195 
    196 	ret = krb5_auth_con_init(telnet_context, &auth_context);
    197 	if (ret) {
    198 		if (auth_debug_mode) {
    199 			printf(
    200 			"Kerberos V5: krb5_auth_con_init failed: %s\r\n",
    201 			    krb5_get_err_text(telnet_context, ret));
    202 		}
    203 		return (0);
    204 	}
    205 	ret = krb5_auth_con_setaddrs_from_fd(telnet_context,
    206 	    auth_context, &net);
    207 	if (ret) {
    208 		if (auth_debug_mode) {
    209 			printf("Kerberos V5: "
    210 			    "krb5_auth_con_setaddrs_from_fd failed: %s\r\n",
    211 			    krb5_get_err_text(telnet_context, ret));
    212 		}
    213 		return (0);
    214 	}
    215 	krb5_auth_con_setkeytype(telnet_context, auth_context, KEYTYPE_DES);
    216 
    217 	foo[0] = ap->type;
    218 	foo[1] = ap->way;
    219 
    220 	cksum_data.length = sizeof(foo);
    221 	cksum_data.data = foo;
    222 	ret = krb5_mk_req(telnet_context, &auth_context, ap_opts, "host",
    223 	    RemoteHostName, &cksum_data, ccache, &auth);
    224 	if (ret) {
    225 		if (1 || auth_debug_mode) {
    226 			printf("Kerberos V5: mk_req failed (%s)\r\n",
    227 			    krb5_get_err_text(telnet_context, ret));
    228 		}
    229 		return (0);
    230 	}
    231 
    232 	if (!auth_sendname((unsigned char *) UserNameRequested,
    233 		strlen(UserNameRequested))) {
    234 		if (auth_debug_mode)
    235 			printf("Not enough room for user name\r\n");
    236 		return (0);
    237 	}
    238 	if (!Data(ap, KRB_AUTH, auth.data, auth.length)) {
    239 		if (auth_debug_mode)
    240 			printf("Not enough room for authentication data\r\n");
    241 		return (0);
    242 	}
    243 	if (auth_debug_mode) {
    244 		printf("Sent Kerberos V5 credentials to server\r\n");
    245 	}
    246 	return (1);
    247 }
    248 
    249 void
    250 kerberos5_is(Authenticator * ap, unsigned char *data, int cnt)
    251 {
    252 	krb5_error_code ret;
    253 	krb5_data outbuf;
    254 	krb5_keyblock *key_block;
    255 	char *name;
    256 	krb5_principal server;
    257 	int zero = 0;
    258 
    259 	if (cnt-- < 1)
    260 		return;
    261 	switch (*data++) {
    262 	case KRB_AUTH:
    263 		auth.data = (char *) data;
    264 		auth.length = cnt;
    265 
    266 		auth_context = NULL;
    267 
    268 		ret = krb5_auth_con_init(telnet_context, &auth_context);
    269 		if (ret) {
    270 			Data(ap, KRB_REJECT, "krb5_auth_con_init failed", -1);
    271 			auth_finished(ap, AUTH_REJECT);
    272 			if (auth_debug_mode)
    273 				printf("Kerberos V5: krb5_auth_con_init failed (%s)\r\n",
    274 				    krb5_get_err_text(telnet_context, ret));
    275 			return;
    276 		}
    277 		ret = krb5_auth_con_setaddrs_from_fd(telnet_context,
    278 		    auth_context, &zero);
    279 		if (ret) {
    280 			Data(ap, KRB_REJECT, "krb5_auth_con_setaddrs_from_fd failed", -1);
    281 			auth_finished(ap, AUTH_REJECT);
    282 			if (auth_debug_mode)
    283 				printf("Kerberos V5: "
    284 				    "krb5_auth_con_setaddrs_from_fd failed (%s)\r\n",
    285 				    krb5_get_err_text(telnet_context, ret));
    286 			return;
    287 		}
    288 		ret = krb5_sock_to_principal(telnet_context, 0, "host",
    289 		    KRB5_NT_SRV_HST, &server);
    290 		if (ret) {
    291 			Data(ap, KRB_REJECT, "krb5_sock_to_principal failed", -1);
    292 			auth_finished(ap, AUTH_REJECT);
    293 			if (auth_debug_mode)
    294 				printf("Kerberos V5: "
    295 				    "krb5_sock_to_principal failed (%s)\r\n",
    296 				    krb5_get_err_text(telnet_context, ret));
    297 			return;
    298 		}
    299 		ret = krb5_rd_req(telnet_context, &auth_context, &auth,
    300 		    server, NULL, NULL, &ticket);
    301 		krb5_free_principal(telnet_context, server);
    302 
    303 		if (ret) {
    304 			char *errbuf;
    305 
    306 			asprintf(&errbuf,
    307 			    "Read req failed: %s",
    308 			    krb5_get_err_text(telnet_context, ret));
    309 			Data(ap, KRB_REJECT, errbuf, -1);
    310 			if (auth_debug_mode)
    311 				printf("%s\r\n", errbuf);
    312 			free(errbuf);
    313 			return;
    314 		} {
    315 			char foo[2];
    316 
    317 			foo[0] = ap->type;
    318 			foo[1] = ap->way;
    319 
    320 			ret = krb5_verify_authenticator_checksum(telnet_context,
    321 			    auth_context, foo, sizeof(foo));
    322 
    323 			if (ret) {
    324 				char *errbuf;
    325 				asprintf(&errbuf, "Bad checksum: %s",
    326 				    krb5_get_err_text(telnet_context, ret));
    327 				Data(ap, KRB_REJECT, errbuf, -1);
    328 				if (auth_debug_mode)
    329 					printf("%s\r\n", errbuf);
    330 				free(errbuf);
    331 				return;
    332 			}
    333 		}
    334 		ret = krb5_auth_con_getremotesubkey(telnet_context,
    335 		    auth_context, &key_block);
    336 
    337 		if (ret) {
    338 			Data(ap, KRB_REJECT, "krb5_auth_con_getremotesubkey failed", -1);
    339 			auth_finished(ap, AUTH_REJECT);
    340 			if (auth_debug_mode)
    341 				printf("Kerberos V5: "
    342 				    "krb5_auth_con_getremotesubkey failed (%s)\r\n",
    343 				    krb5_get_err_text(telnet_context, ret));
    344 			return;
    345 		}
    346 		if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) {
    347 			ret = krb5_mk_rep(telnet_context,
    348 			    auth_context, &outbuf);
    349 			if (ret) {
    350 				Data(ap, KRB_REJECT,
    351 				    "krb5_mk_rep failed", -1);
    352 				auth_finished(ap, AUTH_REJECT);
    353 				if (auth_debug_mode)
    354 					printf("Kerberos V5: "
    355 					    "krb5_mk_rep failed (%s)\r\n",
    356 					    krb5_get_err_text(telnet_context,
    357 					    ret));
    358 				return;
    359 			}
    360 			Data(ap, KRB_RESPONSE, outbuf.data, outbuf.length);
    361 		}
    362 		if (krb5_unparse_name(telnet_context, ticket->client, &name))
    363 			name = 0;
    364 
    365 		if (UserNameRequested && krb5_kuserok(telnet_context,
    366 		    ticket->client, UserNameRequested)) {
    367 			Data(ap, KRB_ACCEPT, name, name ? -1 : 0);
    368 			if (auth_debug_mode) {
    369 				printf("Kerberos5 identifies him as ``%s''\r\n",
    370 				    name ? name : "");
    371 			}
    372 			if (key_block->keytype == ETYPE_DES_CBC_MD5 ||
    373 			    key_block->keytype == ETYPE_DES_CBC_MD4 ||
    374 			    key_block->keytype == ETYPE_DES_CBC_CRC) {
    375 				Session_Key skey;
    376 
    377 				skey.type = SK_DES;
    378 				skey.length = 8;
    379 				skey.data = key_block->keyvalue.data;
    380 				encrypt_session_key(&skey, 0);
    381 			}
    382 		} else {
    383 			char *msg;
    384 
    385 			asprintf(&msg, "user `%s' is not authorized to "
    386 			    "login as `%s'",
    387 			    name ? name : "<unknown>",
    388 			    UserNameRequested ? UserNameRequested : "<nobody>");
    389 			if (msg == NULL)
    390 				Data(ap, KRB_REJECT, NULL, 0);
    391 			else {
    392 				Data(ap, KRB_REJECT, (void *) msg, -1);
    393 				free(msg);
    394 			}
    395 			auth_finished(ap, AUTH_REJECT);
    396 			krb5_free_keyblock_contents(telnet_context, key_block);
    397 			break;
    398 		}
    399 		auth_finished(ap, AUTH_USER);
    400 		krb5_free_keyblock_contents(telnet_context, key_block);
    401 
    402 		break;
    403 	case KRB_FORWARD:{
    404 			struct passwd *pwd;
    405 			char ccname[1024];	/* XXX */
    406 			krb5_data inbuf;
    407 			krb5_ccache ccache;
    408 			inbuf.data = (char *) data;
    409 			inbuf.length = cnt;
    410 
    411 			pwd = getpwnam(UserNameRequested);
    412 			if (pwd == NULL)
    413 				break;
    414 
    415 			snprintf(ccname, sizeof(ccname),
    416 			    "FILE:/tmp/krb5cc_%u", pwd->pw_uid);
    417 
    418 			ret = krb5_cc_resolve(telnet_context, ccname, &ccache);
    419 			if (ret) {
    420 				if (auth_debug_mode)
    421 					printf("Kerberos V5: could not get ccache: %s\r\n",
    422 					    krb5_get_err_text(telnet_context,
    423 					    ret));
    424 				break;
    425 			}
    426 			ret = krb5_cc_initialize(telnet_context, ccache,
    427 			    ticket->client);
    428 			if (ret) {
    429 				if (auth_debug_mode)
    430 					printf("Kerberos V5: could not init ccache: %s\r\n",
    431 					    krb5_get_err_text(telnet_context,
    432 					        ret));
    433 				break;
    434 			}
    435 			ret = krb5_rd_cred2(telnet_context, auth_context,
    436 			    ccache, &inbuf);
    437 			if (ret) {
    438 				char *errbuf;
    439 
    440 				asprintf(&errbuf,
    441 				    "Read forwarded creds failed: %s",
    442 				    krb5_get_err_text(telnet_context, ret));
    443 				if (errbuf == NULL)
    444 					Data(ap, KRB_FORWARD_REJECT, NULL, 0);
    445 				else
    446 					Data(ap, KRB_FORWARD_REJECT, errbuf, -1);
    447 				if (auth_debug_mode)
    448 					printf("Could not read forwarded credentials: %s\r\n",
    449 					    errbuf);
    450 				free(errbuf);
    451 			} else
    452 				Data(ap, KRB_FORWARD_ACCEPT, 0, 0);
    453 			chown(ccname + 5, pwd->pw_uid, -1);
    454 			if (auth_debug_mode)
    455 				printf("Forwarded credentials obtained\r\n");
    456 			break;
    457 		}
    458 	default:
    459 		if (auth_debug_mode)
    460 			printf("Unknown Kerberos option %d\r\n", data[-1]);
    461 		Data(ap, KRB_REJECT, 0, 0);
    462 		break;
    463 	}
    464 }
    465 
    466 void
    467 kerberos5_reply(Authenticator * ap, unsigned char *data, int cnt)
    468 {
    469 	static int mutual_complete = 0;
    470 
    471 	if (cnt-- < 1)
    472 		return;
    473 	switch (*data++) {
    474 	case KRB_REJECT:
    475 		if (cnt > 0) {
    476 			printf("[ Kerberos V5 refuses authentication because %.*s ]\r\n",
    477 			    cnt, data);
    478 		} else
    479 			printf("[ Kerberos V5 refuses authentication ]\r\n");
    480 		auth_send_retry();
    481 		return;
    482 	case KRB_ACCEPT:{
    483 			krb5_error_code ret;
    484 			Session_Key skey;
    485 			krb5_keyblock *keyblock;
    486 
    487 			if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL &&
    488 			    !mutual_complete) {
    489 				printf("[ Kerberos V5 accepted you, but didn't provide mutual authentication! ]\r\n");
    490 				auth_send_retry();
    491 				return;
    492 			}
    493 			if (cnt)
    494 				printf("[ Kerberos V5 accepts you as ``%.*s'' ]\r\n", cnt, data);
    495 			else
    496 				printf("[ Kerberos V5 accepts you ]\r\n");
    497 
    498 			ret = krb5_auth_con_getlocalsubkey(telnet_context,
    499 			    auth_context, &keyblock);
    500 			if (ret)
    501 				ret = krb5_auth_con_getkey(telnet_context,
    502 				    auth_context, &keyblock);
    503 			if (ret) {
    504 				printf("[ krb5_auth_con_getkey: %s ]\r\n",
    505 				    krb5_get_err_text(telnet_context, ret));
    506 				auth_send_retry();
    507 				return;
    508 			}
    509 			skey.type = SK_DES;
    510 			skey.length = 8;
    511 			skey.data = keyblock->keyvalue.data;
    512 			encrypt_session_key(&skey, 0);
    513 			krb5_free_keyblock_contents(telnet_context, keyblock);
    514 			auth_finished(ap, AUTH_USER);
    515 			if (forward_flags & OPTS_FORWARD_CREDS)
    516 				kerberos5_forward(ap);
    517 			break;
    518 		}
    519 	case KRB_RESPONSE:
    520 		if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) {
    521 			/* the rest of the reply should contain a krb_ap_rep */
    522 			krb5_ap_rep_enc_part *reply;
    523 			krb5_data inbuf;
    524 			krb5_error_code ret;
    525 
    526 			inbuf.length = cnt;
    527 			inbuf.data = (char *) data;
    528 
    529 			ret = krb5_rd_rep(telnet_context,
    530 			    auth_context, &inbuf, &reply);
    531 			if (ret) {
    532 				printf("[ Mutual authentication failed: %s ]\r\n",
    533 				    krb5_get_err_text(telnet_context, ret));
    534 				auth_send_retry();
    535 				return;
    536 			}
    537 			krb5_free_ap_rep_enc_part(telnet_context, reply);
    538 			mutual_complete = 1;
    539 		}
    540 		return;
    541 	case KRB_FORWARD_ACCEPT:
    542 		printf("[ Kerberos V5 accepted forwarded credentials ]\r\n");
    543 		return;
    544 	case KRB_FORWARD_REJECT:
    545 		printf("[ Kerberos V5 refuses forwarded credentials because %.*s ]\r\n",
    546 		    cnt, data);
    547 		return;
    548 	default:
    549 		if (auth_debug_mode)
    550 			printf("Unknown Kerberos option %d\r\n", data[-1]);
    551 		return;
    552 	}
    553 }
    554 
    555 int
    556 kerberos5_status(Authenticator *ap, char *name, int level)
    557 {
    558 	if (level < AUTH_USER)
    559 		return (level);
    560 
    561 	if (UserNameRequested &&
    562 	    krb5_kuserok(telnet_context, ticket->client, UserNameRequested)) {
    563 		strcpy(name, UserNameRequested);
    564 		return (AUTH_VALID);
    565 	} else
    566 		return (AUTH_USER);
    567 }
    568 #define	BUMP(buf, len)		while (*(buf)) {++(buf), --(len);}
    569 #define	ADDC(buf, len, c)	if ((len) > 0) {*(buf)++ = (c); --(len);}
    570 
    571 void
    572 kerberos5_printsub(unsigned char *data, int cnt, unsigned char *buf, int buflen)
    573 {
    574 	int i;
    575 
    576 	buf[buflen - 1] = '\0';	/* make sure its NULL terminated */
    577 	buflen -= 1;
    578 
    579 	switch (data[3]) {
    580 	case KRB_REJECT:	/* Rejected (reason might follow) */
    581 		strlcpy((char *) buf, " REJECT ", buflen);
    582 		goto common;
    583 
    584 	case KRB_ACCEPT:	/* Accepted (name might follow) */
    585 		strlcpy((char *) buf, " ACCEPT ", buflen);
    586 common:
    587 		BUMP(buf, buflen);
    588 		if (cnt <= 4)
    589 			break;
    590 		ADDC(buf, buflen, '"');
    591 		for (i = 4; i < cnt; i++)
    592 			ADDC(buf, buflen, data[i]);
    593 		ADDC(buf, buflen, '"');
    594 		ADDC(buf, buflen, '\0');
    595 		break;
    596 
    597 
    598 	case KRB_AUTH:		/* Authentication data follows */
    599 		strlcpy((char *) buf, " AUTH", buflen);
    600 		goto common2;
    601 
    602 	case KRB_RESPONSE:
    603 		strlcpy((char *) buf, " RESPONSE", buflen);
    604 		goto common2;
    605 
    606 	case KRB_FORWARD:	/* Forwarded credentials follow */
    607 		strlcpy((char *) buf, " FORWARD", buflen);
    608 		goto common2;
    609 
    610 	case KRB_FORWARD_ACCEPT:	/* Forwarded credentials accepted */
    611 		strlcpy((char *) buf, " FORWARD_ACCEPT", buflen);
    612 		goto common2;
    613 
    614 	case KRB_FORWARD_REJECT:	/* Forwarded credentials rejected */
    615 		/* (reason might follow) */
    616 		strlcpy((char *) buf, " FORWARD_REJECT", buflen);
    617 		goto common2;
    618 
    619 	default:
    620 		snprintf(buf, buflen, " %d (unknown)", data[3]);
    621 common2:
    622 		BUMP(buf, buflen);
    623 		for (i = 4; i < cnt; i++) {
    624 			snprintf(buf, buflen, " %d", data[i]);
    625 			BUMP(buf, buflen);
    626 		}
    627 		break;
    628 	}
    629 }
    630 
    631 void
    632 kerberos5_forward(Authenticator * ap)
    633 {
    634 	krb5_error_code ret;
    635 	krb5_ccache ccache;
    636 	krb5_creds creds;
    637 	krb5_kdc_flags flags;
    638 	krb5_data out_data;
    639 	krb5_principal principal;
    640 
    641 	ret = krb5_cc_default(telnet_context, &ccache);
    642 	if (ret) {
    643 		if (auth_debug_mode)
    644 			printf("KerberosV5: could not get default ccache: %s\r\n",
    645 			    krb5_get_err_text(telnet_context, ret));
    646 		return;
    647 	}
    648 	ret = krb5_cc_get_principal(telnet_context, ccache, &principal);
    649 	if (ret) {
    650 		if (auth_debug_mode)
    651 			printf("KerberosV5: could not get principal: %s\r\n",
    652 			    krb5_get_err_text(telnet_context, ret));
    653 		return;
    654 	}
    655 	memset(&creds, 0, sizeof(creds));
    656 
    657 	creds.client = principal;
    658 
    659 	ret = krb5_build_principal(telnet_context, &creds.server,
    660 	    strlen(principal->realm), principal->realm, "krbtgt",
    661 	    principal->realm, NULL);
    662 
    663 	if (ret) {
    664 		if (auth_debug_mode)
    665 			printf("KerberosV5: could not get principal: %s\r\n",
    666 			    krb5_get_err_text(telnet_context, ret));
    667 		return;
    668 	}
    669 	creds.times.endtime = 0;
    670 
    671 	flags.i = 0;
    672 	flags.b.forwarded = 1;
    673 	if (forward_flags & OPTS_FORWARDABLE_CREDS)
    674 		flags.b.forwardable = 1;
    675 
    676 	ret = krb5_get_forwarded_creds(telnet_context, auth_context,
    677 	    ccache, flags.i, RemoteHostName, &creds, &out_data);
    678 	if (ret) {
    679 		if (auth_debug_mode)
    680 			printf("Kerberos V5: error getting forwarded creds: %s\r\n",
    681 			    krb5_get_err_text(telnet_context, ret));
    682 		return;
    683 	}
    684 	if (!Data(ap, KRB_FORWARD, out_data.data, out_data.length)) {
    685 		if (auth_debug_mode)
    686 			printf("Not enough room for authentication data\r\n");
    687 	} else {
    688 		if (auth_debug_mode)
    689 			printf("Forwarded local Kerberos V5 credentials to server\r\n");
    690 	}
    691 }
    692 #endif /* KRB5 */
    693