1 /*-
2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 #include <sys/cdefs.h>
31
32 __FBSDID("$FreeBSD$");
33
34 #ifndef lint
35 static const char sccsid[] = "@(#)kerberos.c 8.3 (Berkeley) 5/30/95";
36 #endif /* not lint */
37
38 /*
39 * Copyright (C) 1990 by the Massachusetts Institute of Technology
40 *
41 * Export of this software from the United States of America is assumed
42 * to require a specific license from the United States Government.
43 * It is the responsibility of any person or organization contemplating
44 * export to obtain such a license before exporting.
45 *
46 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
47 * distribute this software and its documentation for any purpose and
48 * without fee is hereby granted, provided that the above copyright
49 * notice appear in all copies and that both that copyright notice and
50 * this permission notice appear in supporting documentation, and that
51 * the name of M.I.T. not be used in advertising or publicity pertaining
52 * to distribution of the software without specific, written prior
53 * permission. M.I.T. makes no representations about the suitability of
54 * this software for any purpose. It is provided "as is" without express
55 * or implied warranty.
56 */
57
58 #ifdef KRB4
59 #include <sys/types.h>
60 #include <arpa/telnet.h>
61 #include <openssl/des.h> /* BSD wont include this in krb.h, so we do it here */
62 #include <krb.h>
63 #include <stdio.h>
64 #include <stdlib.h>
65 #include <string.h>
66
67 #include "encrypt.h"
68 #include "auth.h"
69 #include "misc.h"
70
71 int kerberos4_cksum(unsigned char *, int);
72 int kuserok(AUTH_DAT *, char *);
73
74 extern int auth_debug_mode;
75
76 static unsigned char str_data[1024] = { IAC, SB, TELOPT_AUTHENTICATION, 0,
77 AUTHTYPE_KERBEROS_V4, };
78
79 #define KRB_AUTH 0 /* Authentication data follows */
80 #define KRB_REJECT 1 /* Rejected (reason might follow) */
81 #define KRB_ACCEPT 2 /* Accepted */
82 #define KRB_CHALLENGE 3 /* Challenge for mutual auth. */
83 #define KRB_RESPONSE 4 /* Response for mutual auth. */
84
85 static KTEXT_ST auth;
86 static char name[ANAME_SZ];
87 static AUTH_DAT adat = { 0, "", "", "", 0, {}, 0, 0, 0, { 0, "", 0 } };
88 #ifdef ENCRYPTION
89 static Block session_key = { 0 };
90 static DES_key_schedule sched;
91 static Block challenge = { 0 };
92 #endif /* ENCRYPTION */
93
94 static char krb_service_name[] = "rcmd";
95 static char empty[] = "";
96
97 static int
Data(Authenticator * ap,int type,const unsigned char * d,int c)98 Data(Authenticator *ap, int type, const unsigned char *d, int c)
99 {
100 unsigned char *p = str_data + 4;
101 const unsigned char *cd = 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(net_write(str_data, p - str_data));
126 }
127
128 int
kerberos4_init(Authenticator * ap __unused,int server)129 kerberos4_init(Authenticator *ap __unused, int server)
130 {
131 FILE *fp;
132
133 if (server) {
134 str_data[3] = TELQUAL_REPLY;
135 if ((fp = fopen(KEYFILE, "r")) == NULL)
136 return(0);
137 fclose(fp);
138 } else {
139 str_data[3] = TELQUAL_IS;
140 }
141 return(1);
142 }
143
144 char dst_realm_buf[REALM_SZ], *dest_realm = NULL;
145 int dst_realm_sz = REALM_SZ;
146
147 int
kerberos4_send(Authenticator * ap)148 kerberos4_send(Authenticator *ap)
149 {
150 KTEXT_ST lauth;
151 char instance[INST_SZ];
152 char *realm;
153 CREDENTIALS cred;
154 int r;
155
156 printf("[ Trying KERBEROS4 ... ]\n");
157 if (!UserNameRequested) {
158 if (auth_debug_mode) {
159 printf("Kerberos V4: no user name supplied\r\n");
160 }
161 return(0);
162 }
163
164 memset(instance, 0, sizeof(instance));
165
166 if ((realm = krb_get_phost(RemoteHostName)))
167 strncpy(instance, realm, sizeof(instance));
168
169 instance[sizeof(instance)-1] = '\0';
170
171 realm = dest_realm ? dest_realm : krb_realmofhost(RemoteHostName);
172
173 if (!realm) {
174 printf("Kerberos V4: no realm for %s\r\n", RemoteHostName);
175 return(0);
176 }
177 if ((r = krb_mk_req(&lauth, krb_service_name, instance, realm, 0L))) {
178 printf("mk_req failed: %s\r\n", krb_err_txt[r]);
179 return(0);
180 }
181 if ((r = krb_get_cred(krb_service_name, instance, realm, &cred))) {
182 printf("get_cred failed: %s\r\n", krb_err_txt[r]);
183 return(0);
184 }
185 if (!auth_sendname(UserNameRequested, strlen(UserNameRequested))) {
186 if (auth_debug_mode)
187 printf("Not enough room for user name\r\n");
188 return(0);
189 }
190 if (auth_debug_mode)
191 printf("Sent %d bytes of authentication data\r\n", lauth.length);
192 if (!Data(ap, KRB_AUTH, (void *)lauth.dat, lauth.length)) {
193 if (auth_debug_mode)
194 printf("Not enough room for authentication data\r\n");
195 return(0);
196 }
197 #ifdef ENCRYPTION
198 /*
199 * If we are doing mutual authentication, get set up to send
200 * the challenge, and verify it when the response comes back.
201 */
202 if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) {
203 register int i;
204
205 DES_key_sched(&cred.session, sched);
206 DES_random_key(&session_key);
207 DES_ecb_encrypt(&session_key, &session_key, sched, 0);
208 DES_ecb_encrypt(&session_key, &challenge, sched, 0);
209 /*
210 * Increment the challenge by 1, and encrypt it for
211 * later comparison.
212 */
213 for (i = 7; i >= 0; --i) {
214 register int x;
215 x = (unsigned int)challenge[i] + 1;
216 challenge[i] = x; /* ignore overflow */
217 if (x < 256) /* if no overflow, all done */
218 break;
219 }
220 DES_ecb_encrypt(&challenge, &challenge, sched, 1);
221 }
222 #endif /* ENCRYPTION */
223
224 if (auth_debug_mode) {
225 printf("CK: %d:", kerberos4_cksum(lauth.dat, lauth.length));
226 printd(lauth.dat, lauth.length);
227 printf("\r\n");
228 printf("Sent Kerberos V4 credentials to server\r\n");
229 }
230 return(1);
231 }
232
233 void
kerberos4_is(Authenticator * ap,unsigned char * data,int cnt)234 kerberos4_is(Authenticator *ap, unsigned char *data, int cnt)
235 {
236 #ifdef ENCRYPTION
237 Session_Key skey;
238 Block datablock;
239 #endif /* ENCRYPTION */
240 char realm[REALM_SZ];
241 char instance[INST_SZ];
242 int r;
243
244 if (cnt-- < 1)
245 return;
246 switch (*data++) {
247 case KRB_AUTH:
248 if (krb_get_lrealm(realm, 1) != KSUCCESS) {
249 Data(ap, KRB_REJECT, "No local V4 Realm.", -1);
250 auth_finished(ap, AUTH_REJECT);
251 if (auth_debug_mode)
252 printf("No local realm\r\n");
253 return;
254 }
255 memmove((void *)auth.dat, (void *)data, auth.length = cnt);
256 if (auth_debug_mode) {
257 printf("Got %d bytes of authentication data\r\n", cnt);
258 printf("CK: %d:", kerberos4_cksum(auth.dat, auth.length));
259 printd(auth.dat, auth.length);
260 printf("\r\n");
261 }
262 instance[0] = '*'; instance[1] = 0;
263 if ((r = krb_rd_req(&auth, krb_service_name,
264 instance, 0, &adat, empty))) {
265 if (auth_debug_mode)
266 printf("Kerberos failed him as %s\r\n", name);
267 Data(ap, KRB_REJECT, krb_err_txt[r], -1);
268 auth_finished(ap, AUTH_REJECT);
269 return;
270 }
271 #ifdef ENCRYPTION
272 memmove((void *)session_key, (void *)adat.session, sizeof(Block));
273 #endif /* ENCRYPTION */
274 krb_kntoln(&adat, name);
275
276 if (UserNameRequested && !kuserok(&adat, UserNameRequested))
277 Data(ap, KRB_ACCEPT, NULL, 0);
278 else
279 Data(ap, KRB_REJECT, "user is not authorized", -1);
280 auth_finished(ap, AUTH_USER);
281 break;
282
283 case KRB_CHALLENGE:
284 #ifndef ENCRYPTION
285 Data(ap, KRB_RESPONSE, NULL, 0);
286 #else /* ENCRYPTION */
287 if (!VALIDKEY(session_key)) {
288 /*
289 * We don't have a valid session key, so just
290 * send back a response with an empty session
291 * key.
292 */
293 Data(ap, KRB_RESPONSE, NULL, 0);
294 break;
295 }
296
297 DES_key_sched(&session_key, sched);
298 memmove((void *)datablock, (void *)data, sizeof(Block));
299 /*
300 * Take the received encrypted challenge, and encrypt
301 * it again to get a unique session_key for the
302 * ENCRYPT option.
303 */
304 DES_ecb_encrypt(&datablock, &session_key, sched, 1);
305 skey.type = SK_DES;
306 skey.length = 8;
307 skey.data = session_key;
308 encrypt_session_key(&skey, 1);
309 /*
310 * Now decrypt the received encrypted challenge,
311 * increment by one, re-encrypt it and send it back.
312 */
313 DES_ecb_encrypt(&datablock, &challenge, sched, 0);
314 for (r = 7; r >= 0; r--) {
315 register int t;
316 t = (unsigned int)challenge[r] + 1;
317 challenge[r] = t; /* ignore overflow */
318 if (t < 256) /* if no overflow, all done */
319 break;
320 }
321 DES_ecb_encrypt(&challenge, &challenge, sched, 1);
322 Data(ap, KRB_RESPONSE, challenge, sizeof(challenge));
323 #endif /* ENCRYPTION */
324 break;
325
326 default:
327 if (auth_debug_mode)
328 printf("Unknown Kerberos option %d\r\n", data[-1]);
329 Data(ap, KRB_REJECT, NULL, 0);
330 break;
331 }
332 }
333
334 void
kerberos4_reply(Authenticator * ap,unsigned char * data,int cnt)335 kerberos4_reply(Authenticator *ap, unsigned char *data, int cnt)
336 {
337 #ifdef ENCRYPTION
338 Session_Key skey;
339 #endif /* ENCRYPTION */
340
341 if (cnt-- < 1)
342 return;
343 switch (*data++) {
344 case KRB_REJECT:
345 if (cnt > 0) {
346 printf("[ Kerberos V4 refuses authentication because %.*s ]\r\n",
347 cnt, data);
348 } else
349 printf("[ Kerberos V4 refuses authentication ]\r\n");
350 auth_send_retry();
351 return;
352 case KRB_ACCEPT:
353 printf("[ Kerberos V4 accepts you ]\n");
354 if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) {
355 /*
356 * Send over the encrypted challenge.
357 */
358 #ifndef ENCRYPTION
359 Data(ap, KRB_CHALLENGE, NULL, 0);
360 #else /* ENCRYPTION */
361 Data(ap, KRB_CHALLENGE, session_key,
362 sizeof(session_key));
363 DES_ecb_encrypt(&session_key, &session_key, sched, 1);
364 skey.type = SK_DES;
365 skey.length = 8;
366 skey.data = session_key;
367 encrypt_session_key(&skey, 0);
368 #endif /* ENCRYPTION */
369 return;
370 }
371 auth_finished(ap, AUTH_USER);
372 return;
373 case KRB_RESPONSE:
374 #ifdef ENCRYPTION
375 /*
376 * Verify that the response to the challenge is correct.
377 */
378 if ((cnt != sizeof(Block)) ||
379 (0 != memcmp((void *)data, (void *)challenge,
380 sizeof(challenge))))
381 {
382 #endif /* ENCRYPTION */
383 printf("[ Kerberos V4 challenge failed!!! ]\r\n");
384 auth_send_retry();
385 return;
386 #ifdef ENCRYPTION
387 }
388 printf("[ Kerberos V4 challenge successful ]\r\n");
389 auth_finished(ap, AUTH_USER);
390 #endif /* ENCRYPTION */
391 break;
392 default:
393 if (auth_debug_mode)
394 printf("Unknown Kerberos option %d\r\n", data[-1]);
395 return;
396 }
397 }
398
399 int
kerberos4_status(Authenticator * ap __unused,char * nam,int level)400 kerberos4_status(Authenticator *ap __unused, char *nam, int level)
401 {
402 if (level < AUTH_USER)
403 return(level);
404
405 if (UserNameRequested && !kuserok(&adat, UserNameRequested)) {
406 strcpy(nam, UserNameRequested);
407 return(AUTH_VALID);
408 } else
409 return(AUTH_USER);
410 }
411
412 #define BUMP(buf, len) while (*(buf)) {++(buf), --(len);}
413 #define ADDC(buf, len, c) if ((len) > 0) {*(buf)++ = (c); --(len);}
414
415 void
kerberos4_printsub(unsigned char * data,int cnt,unsigned char * buf,int buflen)416 kerberos4_printsub(unsigned char *data, int cnt, unsigned char *buf, int buflen)
417 {
418 char lbuf[32];
419 register int i;
420
421 buf[buflen-1] = '\0'; /* make sure its NULL terminated */
422 buflen -= 1;
423
424 switch(data[3]) {
425 case KRB_REJECT: /* Rejected (reason might follow) */
426 strncpy((char *)buf, " REJECT ", buflen);
427 goto common;
428
429 case KRB_ACCEPT: /* Accepted (name might follow) */
430 strncpy((char *)buf, " ACCEPT ", buflen);
431 common:
432 BUMP(buf, buflen);
433 if (cnt <= 4)
434 break;
435 ADDC(buf, buflen, '"');
436 for (i = 4; i < cnt; i++)
437 ADDC(buf, buflen, data[i]);
438 ADDC(buf, buflen, '"');
439 ADDC(buf, buflen, '\0');
440 break;
441
442 case KRB_AUTH: /* Authentication data follows */
443 strncpy((char *)buf, " AUTH", buflen);
444 goto common2;
445
446 case KRB_CHALLENGE:
447 strncpy((char *)buf, " CHALLENGE", buflen);
448 goto common2;
449
450 case KRB_RESPONSE:
451 strncpy((char *)buf, " RESPONSE", buflen);
452 goto common2;
453
454 default:
455 sprintf(lbuf, " %d (unknown)", data[3]);
456 strncpy((char *)buf, lbuf, buflen);
457 common2:
458 BUMP(buf, buflen);
459 for (i = 4; i < cnt; i++) {
460 sprintf(lbuf, " %d", data[i]);
461 strncpy((char *)buf, lbuf, buflen);
462 BUMP(buf, buflen);
463 }
464 break;
465 }
466 }
467
468 int
kerberos4_cksum(unsigned char * d,int n)469 kerberos4_cksum(unsigned char *d, int n)
470 {
471 int ck = 0;
472
473 /*
474 * A comment is probably needed here for those not
475 * well versed in the "C" language. Yes, this is
476 * supposed to be a "switch" with the body of the
477 * "switch" being a "while" statement. The whole
478 * purpose of the switch is to allow us to jump into
479 * the middle of the while() loop, and then not have
480 * to do any more switch()s.
481 *
482 * Some compilers will spit out a warning message
483 * about the loop not being entered at the top.
484 */
485 switch (n&03)
486 while (n > 0) {
487 case 0:
488 ck ^= (int)*d++ << 24;
489 --n;
490 case 3:
491 ck ^= (int)*d++ << 16;
492 --n;
493 case 2:
494 ck ^= (int)*d++ << 8;
495 --n;
496 case 1:
497 ck ^= (int)*d++;
498 --n;
499 }
500 return(ck);
501 }
502 #endif
503