sra.c revision 1.2
1 /*- 2 * Copyright (c) 1991, 1993 3 * Dave Safford. 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 31 #include <sys/cdefs.h> 32 #ifdef notdef 33 __FBSDID("$FreeBSD: src/contrib/telnet/libtelnet/sra.c,v 1.16 2002/05/06 09:48:02 markm Exp $"); 34 #else 35 __RCSID("$NetBSD: sra.c,v 1.2 2005/04/09 22:43:51 christos Exp $"); 36 #endif 37 38 #ifdef SRA 39 #ifdef ENCRYPTION 40 #include <sys/types.h> 41 #include <arpa/telnet.h> 42 #include <pwd.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <string.h> 46 #include <syslog.h> 47 #include <ttyent.h> 48 49 #ifndef NOPAM 50 #include <security/pam_appl.h> 51 #else 52 #include <unistd.h> 53 #endif 54 55 #include "auth.h" 56 #include "misc.h" 57 #include "encrypt.h" 58 #include "pk.h" 59 60 char pka[HEXKEYBYTES+1], ska[HEXKEYBYTES+1], pkb[HEXKEYBYTES+1]; 61 char *user, *pass, *xuser, *xpass; 62 DesData ck; 63 IdeaData ik; 64 65 extern int auth_debug_mode; 66 extern char line[]; 67 68 static int sra_valid = 0; 69 static int passwd_sent = 0; 70 71 static unsigned char str_data[1024] = { IAC, SB, TELOPT_AUTHENTICATION, 0, 72 AUTHTYPE_SRA, }; 73 74 #define SRA_KEY 0 75 #define SRA_USER 1 76 #define SRA_CONTINUE 2 77 #define SRA_PASS 3 78 #define SRA_ACCEPT 4 79 #define SRA_REJECT 5 80 81 static int check_user(char *, char *); 82 83 /* support routine to send out authentication message */ 84 static int 85 Data(Authenticator *ap, int type, void *d, int c) 86 { 87 unsigned char *p = str_data + 4; 88 unsigned char *cd = (unsigned char *)d; 89 90 if (c == -1) 91 c = strlen((char *)cd); 92 93 if (auth_debug_mode) { 94 printf("%s:%d: [%d] (%d)", 95 str_data[3] == TELQUAL_IS ? ">>>IS" : ">>>REPLY", 96 str_data[3], 97 type, c); 98 printd(d, c); 99 printf("\r\n"); 100 } 101 *p++ = ap->type; 102 *p++ = ap->way; 103 *p++ = type; 104 while (c-- > 0) { 105 if ((*p++ = *cd++) == IAC) 106 *p++ = IAC; 107 } 108 *p++ = IAC; 109 *p++ = SE; 110 if (str_data[3] == TELQUAL_IS) 111 printsub('>', &str_data[2], p - (&str_data[2])); 112 return(telnet_net_write(str_data, p - str_data)); 113 } 114 115 int 116 sra_init(Authenticator *ap __unused, int server) 117 { 118 if (server) 119 str_data[3] = TELQUAL_REPLY; 120 else 121 str_data[3] = TELQUAL_IS; 122 123 user = (char *)malloc(256); 124 xuser = (char *)malloc(513); 125 pass = (char *)malloc(256); 126 xpass = (char *)malloc(513); 127 128 if (user == NULL || xuser == NULL || pass == NULL || xpass == 129 NULL) 130 return 0; /* malloc failed */ 131 132 passwd_sent = 0; 133 134 genkeys(pka,ska); 135 return(1); 136 } 137 138 /* client received a go-ahead for sra */ 139 int 140 sra_send(Authenticator *ap) 141 { 142 /* send PKA */ 143 144 if (auth_debug_mode) 145 printf("Sent PKA to server.\r\n" ); 146 printf("Trying SRA secure login:\r\n"); 147 if (!Data(ap, SRA_KEY, (void *)pka, HEXKEYBYTES)) { 148 if (auth_debug_mode) 149 printf("Not enough room for authentication data\r\n"); 150 return(0); 151 } 152 153 return(1); 154 } 155 156 /* server received an IS -- could be SRA KEY, USER, or PASS */ 157 void 158 sra_is(Authenticator *ap, unsigned char *data, int cnt) 159 { 160 int valid; 161 Session_Key skey; 162 163 if (cnt-- < 1) 164 goto bad; 165 switch (*data++) { 166 167 case SRA_KEY: 168 if (cnt < HEXKEYBYTES) { 169 Data(ap, SRA_REJECT, (void *)0, 0); 170 auth_finished(ap, AUTH_USER); 171 if (auth_debug_mode) { 172 printf("SRA user rejected for bad PKB\r\n"); 173 } 174 return; 175 } 176 if (auth_debug_mode) 177 printf("Sent pka\r\n"); 178 if (!Data(ap, SRA_KEY, (void *)pka, HEXKEYBYTES)) { 179 if (auth_debug_mode) 180 printf("Not enough room\r\n"); 181 return; 182 } 183 memcpy(pkb,data,HEXKEYBYTES); 184 pkb[HEXKEYBYTES] = '\0'; 185 common_key(ska,pkb,&ik,&ck); 186 return; 187 188 case SRA_USER: 189 /* decode KAB(u) */ 190 if (cnt > 512) /* Attempted buffer overflow */ 191 break; 192 memcpy(xuser,data,cnt); 193 xuser[cnt] = '\0'; 194 pk_decode(xuser,user,&ck); 195 auth_encrypt_user(user); 196 Data(ap, SRA_CONTINUE, (void *)0, 0); 197 198 return; 199 200 case SRA_PASS: 201 if (cnt > 512) /* Attempted buffer overflow */ 202 break; 203 /* decode KAB(P) */ 204 memcpy(xpass,data,cnt); 205 xpass[cnt] = '\0'; 206 pk_decode(xpass,pass,&ck); 207 208 /* check user's password */ 209 valid = check_user(user,pass); 210 211 if(valid) { 212 Data(ap, SRA_ACCEPT, (void *)0, 0); 213 skey.data = ck; 214 skey.type = SK_DES; 215 skey.length = 8; 216 encrypt_session_key(&skey, 1); 217 218 sra_valid = 1; 219 auth_finished(ap, AUTH_VALID); 220 if (auth_debug_mode) { 221 printf("SRA user accepted\r\n"); 222 } 223 } 224 else { 225 Data(ap, SRA_CONTINUE, (void *)0, 0); 226 /* 227 Data(ap, SRA_REJECT, (void *)0, 0); 228 sra_valid = 0; 229 auth_finished(ap, AUTH_REJECT); 230 */ 231 if (auth_debug_mode) { 232 printf("SRA user failed\r\n"); 233 } 234 } 235 return; 236 237 default: 238 if (auth_debug_mode) 239 printf("Unknown SRA option %d\r\n", data[-1]); 240 } 241 bad: 242 Data(ap, SRA_REJECT, 0, 0); 243 sra_valid = 0; 244 auth_finished(ap, AUTH_REJECT); 245 } 246 247 /* client received REPLY -- could be SRA KEY, CONTINUE, ACCEPT, or REJECT */ 248 void 249 sra_reply(Authenticator *ap, unsigned char *data, int cnt) 250 { 251 char uprompt[256],tuser[256]; 252 Session_Key skey; 253 size_t i; 254 255 if (cnt-- < 1) 256 return; 257 switch (*data++) { 258 259 case SRA_KEY: 260 /* calculate common key */ 261 if (cnt < HEXKEYBYTES) { 262 if (auth_debug_mode) { 263 printf("SRA user rejected for bad PKB\r\n"); 264 } 265 return; 266 } 267 memcpy(pkb,data,HEXKEYBYTES); 268 pkb[HEXKEYBYTES] = '\0'; 269 270 common_key(ska,pkb,&ik,&ck); 271 272 enc_user: 273 274 /* encode user */ 275 memset(tuser,0,sizeof(tuser)); 276 sprintf(uprompt,"User (%s): ",UserNameRequested); 277 telnet_gets(uprompt,tuser,255,1); 278 if (tuser[0] == '\n' || tuser[0] == '\r' ) 279 strcpy(user,UserNameRequested); 280 else { 281 /* telnet_gets leaves the newline on */ 282 for(i=0;i<sizeof(tuser);i++) { 283 if (tuser[i] == '\n') { 284 tuser[i] = '\0'; 285 break; 286 } 287 } 288 strcpy(user,tuser); 289 } 290 pk_encode(user,xuser,&ck); 291 292 /* send it off */ 293 if (auth_debug_mode) 294 printf("Sent KAB(U)\r\n"); 295 if (!Data(ap, SRA_USER, (void *)xuser, strlen(xuser))) { 296 if (auth_debug_mode) 297 printf("Not enough room\r\n"); 298 return; 299 } 300 break; 301 302 case SRA_CONTINUE: 303 if (passwd_sent) { 304 passwd_sent = 0; 305 printf("[ SRA login failed ]\r\n"); 306 goto enc_user; 307 } 308 /* encode password */ 309 memset(pass,0,sizeof(pass)); 310 telnet_gets("Password: ",pass,255,0); 311 pk_encode(pass,xpass,&ck); 312 /* send it off */ 313 if (auth_debug_mode) 314 printf("Sent KAB(P)\r\n"); 315 if (!Data(ap, SRA_PASS, (void *)xpass, strlen(xpass))) { 316 if (auth_debug_mode) 317 printf("Not enough room\r\n"); 318 return; 319 } 320 passwd_sent = 1; 321 break; 322 323 case SRA_REJECT: 324 printf("[ SRA refuses authentication ]\r\n"); 325 printf("Trying plaintext login:\r\n"); 326 auth_finished(0,AUTH_REJECT); 327 return; 328 329 case SRA_ACCEPT: 330 printf("[ SRA accepts you ]\r\n"); 331 skey.data = ck; 332 skey.type = SK_DES; 333 skey.length = 8; 334 encrypt_session_key(&skey, 0); 335 336 auth_finished(ap, AUTH_VALID); 337 return; 338 default: 339 if (auth_debug_mode) 340 printf("Unknown SRA option %d\r\n", data[-1]); 341 return; 342 } 343 } 344 345 int 346 sra_status(Authenticator *ap __unused, char *name, size_t len, int level) 347 { 348 if (level < AUTH_USER) 349 return(level); 350 if (UserNameRequested && sra_valid) { 351 strlcpy(name, UserNameRequested, len); 352 return(AUTH_VALID); 353 } else 354 return(AUTH_USER); 355 } 356 357 #define BUMP(buf, len) while (*(buf)) {++(buf), --(len);} 358 #define ADDC(buf, len, c) if ((len) > 0) {*(buf)++ = (c); --(len);} 359 360 void 361 sra_printsub(unsigned char *data, int cnt, unsigned char *buf, int buflen) 362 { 363 char lbuf[32]; 364 int i; 365 366 buf[buflen-1] = '\0'; /* make sure its NULL terminated */ 367 buflen -= 1; 368 369 switch(data[3]) { 370 371 case SRA_CONTINUE: 372 strncpy((char *)buf, " CONTINUE ", buflen); 373 goto common; 374 375 case SRA_REJECT: /* Rejected (reason might follow) */ 376 strncpy((char *)buf, " REJECT ", buflen); 377 goto common; 378 379 case SRA_ACCEPT: /* Accepted (name might follow) */ 380 strncpy((char *)buf, " ACCEPT ", buflen); 381 382 common: 383 BUMP(buf, buflen); 384 if (cnt <= 4) 385 break; 386 ADDC(buf, buflen, '"'); 387 for (i = 4; i < cnt; i++) 388 ADDC(buf, buflen, data[i]); 389 ADDC(buf, buflen, '"'); 390 ADDC(buf, buflen, '\0'); 391 break; 392 393 case SRA_KEY: /* Authentication data follows */ 394 strncpy((char *)buf, " KEY ", buflen); 395 goto common2; 396 397 case SRA_USER: 398 strncpy((char *)buf, " USER ", buflen); 399 goto common2; 400 401 case SRA_PASS: 402 strncpy((char *)buf, " PASS ", buflen); 403 goto common2; 404 405 default: 406 sprintf(lbuf, " %d (unknown)", data[3]); 407 strncpy((char *)buf, lbuf, buflen); 408 common2: 409 BUMP(buf, buflen); 410 for (i = 4; i < cnt; i++) { 411 sprintf(lbuf, " %d", data[i]); 412 strncpy((char *)buf, lbuf, buflen); 413 BUMP(buf, buflen); 414 } 415 break; 416 } 417 } 418 419 static int 420 isroot(const char *usr) 421 { 422 struct passwd pws, *pwd; 423 char pwbuf[1024]; 424 425 if (getpwnam_r(usr, &pws, pwbuf, sizeof(pwbuf), &pwd) != 0) 426 return 0; 427 return (!pwd->pw_uid); 428 } 429 430 static int 431 rootterm(char *ttyn) 432 { 433 struct ttyent *t; 434 435 return ((t = getttynam(ttyn)) && t->ty_status & TTY_SECURE); 436 } 437 438 #ifdef NOPAM 439 static int 440 check_user(char *name, char *cred) 441 { 442 char *cp; 443 char *xpasswd, *salt; 444 445 if (isroot(name) && !rootterm(line)) 446 { 447 crypt("AA","*"); /* Waste some time to simulate success */ 448 return(0); 449 } 450 451 if (pw = sgetpwnam(name)) { 452 if (pw->pw_shell == NULL) { 453 pw = (struct passwd *) NULL; 454 return(0); 455 } 456 457 salt = pw->pw_passwd; 458 xpasswd = crypt(cred, salt); 459 /* The strcmp does not catch null passwords! */ 460 if (pw == NULL || *pw->pw_passwd == '\0' || 461 strcmp(xpasswd, pw->pw_passwd)) { 462 pw = (struct passwd *) NULL; 463 return(0); 464 } 465 return(1); 466 } 467 return(0); 468 } 469 #else 470 471 /* 472 * The following is stolen from ftpd, which stole it from the imap-uw 473 * PAM module and login.c. It is needed because we can't really 474 * "converse" with the user, having already gone to the trouble of 475 * getting their username and password through an encrypted channel. 476 */ 477 478 #define COPY_STRING(s) (s ? strdup(s):NULL) 479 480 struct cred_t { 481 const char *uname; 482 const char *pass; 483 }; 484 typedef struct cred_t cred_t; 485 486 static int 487 auth_conv(int num_msg, const struct pam_message **msg, struct pam_response **resp, void *appdata) 488 { 489 int i; 490 cred_t *cred = (cred_t *) appdata; 491 struct pam_response *reply = 492 malloc(sizeof(struct pam_response) * num_msg); 493 494 if (reply == NULL) 495 return PAM_BUF_ERR; 496 497 for (i = 0; i < num_msg; i++) { 498 switch (msg[i]->msg_style) { 499 case PAM_PROMPT_ECHO_ON: /* assume want user name */ 500 reply[i].resp_retcode = PAM_SUCCESS; 501 reply[i].resp = COPY_STRING(cred->uname); 502 /* PAM frees resp. */ 503 break; 504 case PAM_PROMPT_ECHO_OFF: /* assume want password */ 505 reply[i].resp_retcode = PAM_SUCCESS; 506 reply[i].resp = COPY_STRING(cred->pass); 507 /* PAM frees resp. */ 508 break; 509 case PAM_TEXT_INFO: 510 case PAM_ERROR_MSG: 511 reply[i].resp_retcode = PAM_SUCCESS; 512 reply[i].resp = NULL; 513 break; 514 default: /* unknown message style */ 515 free(reply); 516 return PAM_CONV_ERR; 517 } 518 } 519 520 *resp = reply; 521 return PAM_SUCCESS; 522 } 523 524 /* 525 * The PAM version as a side effect may put a new username in *name. 526 */ 527 static int 528 check_user(char *name, char *cred) 529 { 530 pam_handle_t *pamh = NULL; 531 const void *item; 532 int rval; 533 int e; 534 cred_t auth_cred = { name, cred }; 535 struct pam_conv conv = { &auth_conv, &auth_cred }; 536 537 e = pam_start("telnetd", name, &conv, &pamh); 538 if (e != PAM_SUCCESS) { 539 syslog(LOG_ERR, "pam_start: %s", pam_strerror(pamh, e)); 540 return 0; 541 } 542 543 #if 0 /* Where can we find this value? */ 544 e = pam_set_item(pamh, PAM_RHOST, remotehost); 545 if (e != PAM_SUCCESS) { 546 syslog(LOG_ERR, "pam_set_item(PAM_RHOST): %s", 547 pam_strerror(pamh, e)); 548 return 0; 549 } 550 #endif 551 552 e = pam_authenticate(pamh, 0); 553 switch (e) { 554 case PAM_SUCCESS: 555 /* 556 * With PAM we support the concept of a "template" 557 * user. The user enters a login name which is 558 * authenticated by PAM, usually via a remote service 559 * such as RADIUS or TACACS+. If authentication 560 * succeeds, a different but related "template" name 561 * is used for setting the credentials, shell, and 562 * home directory. The name the user enters need only 563 * exist on the remote authentication server, but the 564 * template name must be present in the local password 565 * database. 566 * 567 * This is supported by two various mechanisms in the 568 * individual modules. However, from the application's 569 * point of view, the template user is always passed 570 * back as a changed value of the PAM_USER item. 571 */ 572 if ((e = pam_get_item(pamh, PAM_USER, &item)) == 573 PAM_SUCCESS) { 574 strcpy(name, item); 575 } else 576 syslog(LOG_ERR, "Couldn't get PAM_USER: %s", 577 pam_strerror(pamh, e)); 578 if (isroot(name) && !rootterm(line)) 579 rval = 0; 580 else 581 rval = 1; 582 break; 583 584 case PAM_AUTH_ERR: 585 case PAM_USER_UNKNOWN: 586 case PAM_MAXTRIES: 587 rval = 0; 588 break; 589 590 default: 591 syslog(LOG_ERR, "auth_pam: %s", pam_strerror(pamh, e)); 592 rval = 0; 593 break; 594 } 595 596 if ((e = pam_end(pamh, e)) != PAM_SUCCESS) { 597 syslog(LOG_ERR, "pam_end: %s", pam_strerror(pamh, e)); 598 rval = 0; 599 } 600 return rval; 601 } 602 603 #endif 604 605 #endif /* ENCRYPTION */ 606 #endif /* SRA */ 607
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