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 #ifndef lint
31 static const char sccsid[] = "@(#)kerberos.c 8.3 (Berkeley) 5/30/95";
32 #endif /* not lint */
33
34 /*
35 * Copyright (C) 1990 by the Massachusetts Institute of Technology
36 *
37 * Export of this software from the United States of America is assumed
38 * to require a specific license from the United States Government.
39 * It is the responsibility of any person or organization contemplating
40 * export to obtain such a license before exporting.
41 *
42 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
43 * distribute this software and its documentation for any purpose and
44 * without fee is hereby granted, provided that the above copyright
45 * notice appear in all copies and that both that copyright notice and
46 * this permission notice appear in supporting documentation, and that
47 * the name of M.I.T. not be used in advertising or publicity pertaining
48 * to distribution of the software without specific, written prior
49 * permission. M.I.T. makes no representations about the suitability of
50 * this software for any purpose. It is provided "as is" without express
51 * or implied warranty.
52 */
53
54 #ifdef KRB4
55 #include <sys/types.h>
56 #include <arpa/telnet.h>
57 #include <openssl/des.h> /* BSD wont include this in krb.h, so we do it here */
58 #include <krb.h>
59 #include <stdio.h>
60 #include <stdlib.h>
61 #include <string.h>
62
63 #include "encrypt.h"
64 #include "auth.h"
65 #include "misc.h"
66
67 int kerberos4_cksum(unsigned char *, int);
68 int kuserok(AUTH_DAT *, char *);
69
70 extern int auth_debug_mode;
71
72 static unsigned char str_data[1024] = { IAC, SB, TELOPT_AUTHENTICATION, 0,
73 AUTHTYPE_KERBEROS_V4, };
74
75 #define KRB_AUTH 0 /* Authentication data follows */
76 #define KRB_REJECT 1 /* Rejected (reason might follow) */
77 #define KRB_ACCEPT 2 /* Accepted */
78 #define KRB_CHALLENGE 3 /* Challenge for mutual auth. */
79 #define KRB_RESPONSE 4 /* Response for mutual auth. */
80
81 static KTEXT_ST auth;
82 static char name[ANAME_SZ];
83 static AUTH_DAT adat = { 0, "", "", "", 0, {}, 0, 0, 0, { 0, "", 0 } };
84 #ifdef ENCRYPTION
85 static Block session_key = { 0 };
86 static DES_key_schedule sched;
87 static Block challenge = { 0 };
88 #endif /* ENCRYPTION */
89
90 static char krb_service_name[] = "rcmd";
91 static char empty[] = "";
92
93 static int
Data(Authenticator * ap,int type,const unsigned char * d,int c)94 Data(Authenticator *ap, int type, const unsigned char *d, int c)
95 {
96 unsigned char *p = str_data + 4;
97 const unsigned char *cd = d;
98
99 if (c == -1)
100 c = strlen(cd);
101
102 if (auth_debug_mode) {
103 printf("%s:%d: [%d] (%d)",
104 str_data[3] == TELQUAL_IS ? ">>>IS" : ">>>REPLY",
105 str_data[3],
106 type, c);
107 printd(d, c);
108 printf("\r\n");
109 }
110 *p++ = ap->type;
111 *p++ = ap->way;
112 *p++ = type;
113 while (c-- > 0) {
114 if ((*p++ = *cd++) == IAC)
115 *p++ = IAC;
116 }
117 *p++ = IAC;
118 *p++ = SE;
119 if (str_data[3] == TELQUAL_IS)
120 printsub('>', &str_data[2], p - (&str_data[2]));
121 return(net_write(str_data, p - str_data));
122 }
123
124 int
kerberos4_init(Authenticator * ap __unused,int server)125 kerberos4_init(Authenticator *ap __unused, int server)
126 {
127 FILE *fp;
128
129 if (server) {
130 str_data[3] = TELQUAL_REPLY;
131 if ((fp = fopen(KEYFILE, "r")) == NULL)
132 return(0);
133 fclose(fp);
134 } else {
135 str_data[3] = TELQUAL_IS;
136 }
137 return(1);
138 }
139
140 char dst_realm_buf[REALM_SZ], *dest_realm = NULL;
141 int dst_realm_sz = REALM_SZ;
142
143 int
kerberos4_send(Authenticator * ap)144 kerberos4_send(Authenticator *ap)
145 {
146 KTEXT_ST lauth;
147 char instance[INST_SZ];
148 char *realm;
149 CREDENTIALS cred;
150 int r;
151
152 printf("[ Trying KERBEROS4 ... ]\n");
153 if (!UserNameRequested) {
154 if (auth_debug_mode) {
155 printf("Kerberos V4: no user name supplied\r\n");
156 }
157 return(0);
158 }
159
160 memset(instance, 0, sizeof(instance));
161
162 if ((realm = krb_get_phost(RemoteHostName)))
163 strncpy(instance, realm, sizeof(instance));
164
165 instance[sizeof(instance)-1] = '\0';
166
167 realm = dest_realm ? dest_realm : krb_realmofhost(RemoteHostName);
168
169 if (!realm) {
170 printf("Kerberos V4: no realm for %s\r\n", RemoteHostName);
171 return(0);
172 }
173 if ((r = krb_mk_req(&lauth, krb_service_name, instance, realm, 0L))) {
174 printf("mk_req failed: %s\r\n", krb_err_txt[r]);
175 return(0);
176 }
177 if ((r = krb_get_cred(krb_service_name, instance, realm, &cred))) {
178 printf("get_cred failed: %s\r\n", krb_err_txt[r]);
179 return(0);
180 }
181 if (!auth_sendname(UserNameRequested, strlen(UserNameRequested))) {
182 if (auth_debug_mode)
183 printf("Not enough room for user name\r\n");
184 return(0);
185 }
186 if (auth_debug_mode)
187 printf("Sent %d bytes of authentication data\r\n", lauth.length);
188 if (!Data(ap, KRB_AUTH, (void *)lauth.dat, lauth.length)) {
189 if (auth_debug_mode)
190 printf("Not enough room for authentication data\r\n");
191 return(0);
192 }
193 #ifdef ENCRYPTION
194 /*
195 * If we are doing mutual authentication, get set up to send
196 * the challenge, and verify it when the response comes back.
197 */
198 if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) {
199 register int i;
200
201 DES_key_sched(&cred.session, sched);
202 DES_random_key(&session_key);
203 DES_ecb_encrypt(&session_key, &session_key, sched, 0);
204 DES_ecb_encrypt(&session_key, &challenge, sched, 0);
205 /*
206 * Increment the challenge by 1, and encrypt it for
207 * later comparison.
208 */
209 for (i = 7; i >= 0; --i) {
210 register int x;
211 x = (unsigned int)challenge[i] + 1;
212 challenge[i] = x; /* ignore overflow */
213 if (x < 256) /* if no overflow, all done */
214 break;
215 }
216 DES_ecb_encrypt(&challenge, &challenge, sched, 1);
217 }
218 #endif /* ENCRYPTION */
219
220 if (auth_debug_mode) {
221 printf("CK: %d:", kerberos4_cksum(lauth.dat, lauth.length));
222 printd(lauth.dat, lauth.length);
223 printf("\r\n");
224 printf("Sent Kerberos V4 credentials to server\r\n");
225 }
226 return(1);
227 }
228
229 void
kerberos4_is(Authenticator * ap,unsigned char * data,int cnt)230 kerberos4_is(Authenticator *ap, unsigned char *data, int cnt)
231 {
232 #ifdef ENCRYPTION
233 Session_Key skey;
234 Block datablock;
235 #endif /* ENCRYPTION */
236 char realm[REALM_SZ];
237 char instance[INST_SZ];
238 int r;
239
240 if (cnt-- < 1)
241 return;
242 switch (*data++) {
243 case KRB_AUTH:
244 if (krb_get_lrealm(realm, 1) != KSUCCESS) {
245 Data(ap, KRB_REJECT, "No local V4 Realm.", -1);
246 auth_finished(ap, AUTH_REJECT);
247 if (auth_debug_mode)
248 printf("No local realm\r\n");
249 return;
250 }
251 memmove((void *)auth.dat, (void *)data, auth.length = cnt);
252 if (auth_debug_mode) {
253 printf("Got %d bytes of authentication data\r\n", cnt);
254 printf("CK: %d:", kerberos4_cksum(auth.dat, auth.length));
255 printd(auth.dat, auth.length);
256 printf("\r\n");
257 }
258 instance[0] = '*'; instance[1] = 0;
259 if ((r = krb_rd_req(&auth, krb_service_name,
260 instance, 0, &adat, empty))) {
261 if (auth_debug_mode)
262 printf("Kerberos failed him as %s\r\n", name);
263 Data(ap, KRB_REJECT, krb_err_txt[r], -1);
264 auth_finished(ap, AUTH_REJECT);
265 return;
266 }
267 #ifdef ENCRYPTION
268 memmove((void *)session_key, (void *)adat.session, sizeof(Block));
269 #endif /* ENCRYPTION */
270 krb_kntoln(&adat, name);
271
272 if (UserNameRequested && !kuserok(&adat, UserNameRequested))
273 Data(ap, KRB_ACCEPT, NULL, 0);
274 else
275 Data(ap, KRB_REJECT, "user is not authorized", -1);
276 auth_finished(ap, AUTH_USER);
277 break;
278
279 case KRB_CHALLENGE:
280 #ifndef ENCRYPTION
281 Data(ap, KRB_RESPONSE, NULL, 0);
282 #else /* ENCRYPTION */
283 if (!VALIDKEY(session_key)) {
284 /*
285 * We don't have a valid session key, so just
286 * send back a response with an empty session
287 * key.
288 */
289 Data(ap, KRB_RESPONSE, NULL, 0);
290 break;
291 }
292
293 DES_key_sched(&session_key, sched);
294 memmove((void *)datablock, (void *)data, sizeof(Block));
295 /*
296 * Take the received encrypted challenge, and encrypt
297 * it again to get a unique session_key for the
298 * ENCRYPT option.
299 */
300 DES_ecb_encrypt(&datablock, &session_key, sched, 1);
301 skey.type = SK_DES;
302 skey.length = 8;
303 skey.data = session_key;
304 encrypt_session_key(&skey, 1);
305 /*
306 * Now decrypt the received encrypted challenge,
307 * increment by one, re-encrypt it and send it back.
308 */
309 DES_ecb_encrypt(&datablock, &challenge, sched, 0);
310 for (r = 7; r >= 0; r--) {
311 register int t;
312 t = (unsigned int)challenge[r] + 1;
313 challenge[r] = t; /* ignore overflow */
314 if (t < 256) /* if no overflow, all done */
315 break;
316 }
317 DES_ecb_encrypt(&challenge, &challenge, sched, 1);
318 Data(ap, KRB_RESPONSE, challenge, sizeof(challenge));
319 #endif /* ENCRYPTION */
320 break;
321
322 default:
323 if (auth_debug_mode)
324 printf("Unknown Kerberos option %d\r\n", data[-1]);
325 Data(ap, KRB_REJECT, NULL, 0);
326 break;
327 }
328 }
329
330 void
kerberos4_reply(Authenticator * ap,unsigned char * data,int cnt)331 kerberos4_reply(Authenticator *ap, unsigned char *data, int cnt)
332 {
333 #ifdef ENCRYPTION
334 Session_Key skey;
335 #endif /* ENCRYPTION */
336
337 if (cnt-- < 1)
338 return;
339 switch (*data++) {
340 case KRB_REJECT:
341 if (cnt > 0) {
342 printf("[ Kerberos V4 refuses authentication because %.*s ]\r\n",
343 cnt, data);
344 } else
345 printf("[ Kerberos V4 refuses authentication ]\r\n");
346 auth_send_retry();
347 return;
348 case KRB_ACCEPT:
349 printf("[ Kerberos V4 accepts you ]\n");
350 if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) {
351 /*
352 * Send over the encrypted challenge.
353 */
354 #ifndef ENCRYPTION
355 Data(ap, KRB_CHALLENGE, NULL, 0);
356 #else /* ENCRYPTION */
357 Data(ap, KRB_CHALLENGE, session_key,
358 sizeof(session_key));
359 DES_ecb_encrypt(&session_key, &session_key, sched, 1);
360 skey.type = SK_DES;
361 skey.length = 8;
362 skey.data = session_key;
363 encrypt_session_key(&skey, 0);
364 #endif /* ENCRYPTION */
365 return;
366 }
367 auth_finished(ap, AUTH_USER);
368 return;
369 case KRB_RESPONSE:
370 #ifdef ENCRYPTION
371 /*
372 * Verify that the response to the challenge is correct.
373 */
374 if ((cnt != sizeof(Block)) ||
375 (0 != memcmp((void *)data, (void *)challenge,
376 sizeof(challenge))))
377 {
378 #endif /* ENCRYPTION */
379 printf("[ Kerberos V4 challenge failed!!! ]\r\n");
380 auth_send_retry();
381 return;
382 #ifdef ENCRYPTION
383 }
384 printf("[ Kerberos V4 challenge successful ]\r\n");
385 auth_finished(ap, AUTH_USER);
386 #endif /* ENCRYPTION */
387 break;
388 default:
389 if (auth_debug_mode)
390 printf("Unknown Kerberos option %d\r\n", data[-1]);
391 return;
392 }
393 }
394
395 int
kerberos4_status(Authenticator * ap __unused,char * nam,int level)396 kerberos4_status(Authenticator *ap __unused, char *nam, int level)
397 {
398 if (level < AUTH_USER)
399 return(level);
400
401 if (UserNameRequested && !kuserok(&adat, UserNameRequested)) {
402 strcpy(nam, UserNameRequested);
403 return(AUTH_VALID);
404 } else
405 return(AUTH_USER);
406 }
407
408 #define BUMP(buf, len) while (*(buf)) {++(buf), --(len);}
409 #define ADDC(buf, len, c) if ((len) > 0) {*(buf)++ = (c); --(len);}
410
411 void
kerberos4_printsub(unsigned char * data,int cnt,unsigned char * buf,int buflen)412 kerberos4_printsub(unsigned char *data, int cnt, unsigned char *buf, int buflen)
413 {
414 char lbuf[32];
415 register int i;
416
417 buf[buflen-1] = '\0'; /* make sure its NULL terminated */
418 buflen -= 1;
419
420 switch(data[3]) {
421 case KRB_REJECT: /* Rejected (reason might follow) */
422 strncpy((char *)buf, " REJECT ", buflen);
423 goto common;
424
425 case KRB_ACCEPT: /* Accepted (name might follow) */
426 strncpy((char *)buf, " ACCEPT ", buflen);
427 common:
428 BUMP(buf, buflen);
429 if (cnt <= 4)
430 break;
431 ADDC(buf, buflen, '"');
432 for (i = 4; i < cnt; i++)
433 ADDC(buf, buflen, data[i]);
434 ADDC(buf, buflen, '"');
435 ADDC(buf, buflen, '\0');
436 break;
437
438 case KRB_AUTH: /* Authentication data follows */
439 strncpy((char *)buf, " AUTH", buflen);
440 goto common2;
441
442 case KRB_CHALLENGE:
443 strncpy((char *)buf, " CHALLENGE", buflen);
444 goto common2;
445
446 case KRB_RESPONSE:
447 strncpy((char *)buf, " RESPONSE", buflen);
448 goto common2;
449
450 default:
451 sprintf(lbuf, " %d (unknown)", data[3]);
452 strncpy((char *)buf, lbuf, buflen);
453 common2:
454 BUMP(buf, buflen);
455 for (i = 4; i < cnt; i++) {
456 sprintf(lbuf, " %d", data[i]);
457 strncpy((char *)buf, lbuf, buflen);
458 BUMP(buf, buflen);
459 }
460 break;
461 }
462 }
463
464 int
kerberos4_cksum(unsigned char * d,int n)465 kerberos4_cksum(unsigned char *d, int n)
466 {
467 int ck = 0;
468
469 /*
470 * A comment is probably needed here for those not
471 * well versed in the "C" language. Yes, this is
472 * supposed to be a "switch" with the body of the
473 * "switch" being a "while" statement. The whole
474 * purpose of the switch is to allow us to jump into
475 * the middle of the while() loop, and then not have
476 * to do any more switch()s.
477 *
478 * Some compilers will spit out a warning message
479 * about the loop not being entered at the top.
480 */
481 switch (n&03)
482 while (n > 0) {
483 case 0:
484 ck ^= (int)*d++ << 24;
485 --n;
486 case 3:
487 ck ^= (int)*d++ << 16;
488 --n;
489 case 2:
490 ck ^= (int)*d++ << 8;
491 --n;
492 case 1:
493 ck ^= (int)*d++;
494 --n;
495 }
496 return(ck);
497 }
498 #endif
499