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 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 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 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 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 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 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 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 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