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 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 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 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 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 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 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 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 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