1 /* 2 * Copyright (c) 1983, 1988 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms are permitted 6 * provided that the above copyright notice and this paragraph are 7 * duplicated in all such forms and that any documentation, 8 * advertising materials, and other materials related to such 9 * distribution and use acknowledge that the software was developed 10 * by the University of California, Berkeley. The name of the 11 * University may not be used to endorse or promote products derived 12 * from this software without specific prior written permission. 13 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 15 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. 16 */ 17 18 #ifndef lint 19 char copyright[] = 20 "@(#) Copyright (c) 1983, 1988 The Regents of the University of California.\n\ 21 All rights reserved.\n"; 22 #endif /* not lint */ 23 24 #ifndef lint 25 static char sccsid[] = "@(#)rlogind.c 5.27 (Berkeley) 01/25/89"; 26 #endif /* not lint */ 27 28 /* 29 * remote login server: 30 * \0 31 * remuser\0 32 * locuser\0 33 * terminal_type/speed\0 34 * data 35 */ 36 37 #include <stdio.h> 38 #include <sys/types.h> 39 #include <sys/stat.h> 40 #include <sys/socket.h> 41 #include <sys/wait.h> 42 #include <sys/file.h> 43 #include <sys/param.h> 44 45 #include <netinet/in.h> 46 47 #include <errno.h> 48 #include <pwd.h> 49 #include <signal.h> 50 #include <sys/ioctl.h> 51 #include <sys/termios.h> 52 #include <stdio.h> 53 #include <netdb.h> 54 #include <syslog.h> 55 #include <strings.h> 56 57 #ifndef TIOCPKT_WINDOW 58 #define TIOCPKT_WINDOW 0x80 59 #endif 60 61 #ifdef KERBEROS 62 #include <kerberos/krb.h> 63 #define SECURE_MESSAGE "This rlogin session is using DES encryption for all transmissions.\r\n" 64 65 AUTH_DAT *kdata; 66 KTEXT ticket; 67 u_char auth_buf[sizeof(AUTH_DAT)]; 68 u_char tick_buf[sizeof(KTEXT_ST)]; 69 Key_schedule schedule; 70 int encrypt, retval, use_kerberos = 0, vacuous = 0; 71 int do_krb_login(); 72 73 #define OLD_RCMD 0x00 74 #define KERB_RCMD 0x00 75 #define KERB_RCMD_MUTUAL 0x03 76 77 #define ARGSTR "lnkv" 78 #else 79 #define ARGSTR "ln" 80 #endif /* KERBEROS */ 81 82 char *env[2]; 83 #define NMAX 30 84 char lusername[NMAX+1], rusername[NMAX+1]; 85 static char term[64] = "TERM="; 86 #define ENVSIZE (sizeof("TERM=")-1) /* skip null for concatenation */ 87 int keepalive = 1; 88 89 #define SUPERUSER(pwd) ((pwd)->pw_uid == 0) 90 91 extern int errno; 92 int reapchild(); 93 struct passwd *getpwnam(), *pwd; 94 char *malloc(); 95 96 main(argc, argv) 97 int argc; 98 char **argv; 99 { 100 extern int opterr, optind, _check_rhosts_file; 101 int ch; 102 int on = 1, fromlen; 103 struct sockaddr_in from; 104 105 openlog("rlogind", LOG_PID | LOG_CONS, LOG_AUTH); 106 107 opterr = 0; 108 while ((ch = getopt(argc, argv, ARGSTR)) != EOF) 109 switch (ch) { 110 case 'l': 111 _check_rhosts_file = 0; 112 break; 113 case 'n': 114 keepalive = 0; 115 break; 116 #ifdef KERBEROS 117 case 'k': 118 use_kerberos = 1; 119 break; 120 case 'v': 121 vacuous = 1; 122 break; 123 #endif 124 case '?': 125 default: 126 usage(); 127 break; 128 } 129 argc -= optind; 130 argv += optind; 131 132 #ifdef KERBEROS 133 if (use_kerberos && vacuous) { 134 usage(); 135 fatal("only one of -k and -v allowed\n"); 136 } 137 #endif 138 fromlen = sizeof (from); 139 if (getpeername(0, &from, &fromlen) < 0) { 140 syslog(LOG_ERR,"Can't get peer name of remote host: %m"); 141 fatalperror("Can't get peer name of remote host"); 142 } 143 if (keepalive && 144 setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof (on)) < 0) 145 syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m"); 146 doit(0, &from); 147 } 148 149 int child; 150 int cleanup(); 151 int netf; 152 char *line; 153 extern char *inet_ntoa(); 154 155 struct winsize win = { 0, 0, 0, 0 }; 156 157 158 doit(f, fromp) 159 int f; 160 struct sockaddr_in *fromp; 161 { 162 int i, p, t, pid, on = 1; 163 int authenticated = 0, hostok = 0; 164 register struct hostent *hp; 165 char remotehost[2 * MAXHOSTNAMELEN + 1]; 166 struct hostent hostent; 167 char c; 168 169 alarm(60); 170 read(f, &c, 1); 171 172 #ifdef KERBEROS 173 /* 174 * XXX 1st char tells us which client we're talking to 175 */ 176 switch (c) { 177 178 case OLD_RCMD: /* OLD_RCMD is same as KERB_RCMD */ 179 if (vacuous) 180 fatal(f, "Remote host requires Kerberos authentication"); 181 break; 182 183 case KERB_RCMD_MUTUAL: 184 encrypt = 1; 185 break; 186 187 default: 188 fatal(f, "Remote protocol error"); 189 } 190 #else 191 if (c != 0) 192 exit(1); 193 #endif 194 195 alarm(0); 196 fromp->sin_port = ntohs((u_short)fromp->sin_port); 197 hp = gethostbyaddr(&fromp->sin_addr, sizeof (struct in_addr), 198 fromp->sin_family); 199 if (hp == 0) { 200 /* 201 * Only the name is used below. 202 */ 203 hp = &hostent; 204 hp->h_name = inet_ntoa(fromp->sin_addr); 205 } else if (local_domain(hp->h_name)) { 206 /* 207 * If name returned by gethostbyaddr is in our domain, 208 * attempt to verify that we haven't been fooled by someone 209 * in a remote net; look up the name and check that this 210 * address corresponds to the name. 211 */ 212 strncpy(remotehost, hp->h_name, sizeof(remotehost) - 1); 213 remotehost[sizeof(remotehost) - 1] = 0; 214 hp = gethostbyname(remotehost); 215 if (hp) 216 for (; hp->h_addr_list[0]; hp->h_addr_list++) { 217 if (!bcmp(hp->h_addr_list[0], (caddr_t)&fromp->sin_addr, 218 sizeof(fromp->sin_addr))) { 219 hostok++; 220 break; 221 } 222 } 223 } 224 225 #ifdef KERBEROS 226 if (use_kerberos) { 227 retval = do_krb_login(hp->h_name, fromp, encrypt); 228 write(f, &c, 1); 229 if (retval == 0) 230 authenticated++; 231 else if (retval > 0) 232 fatal(f, krb_err_txt[retval]); 233 } else 234 #endif 235 if (fromp->sin_family != AF_INET || 236 fromp->sin_port >= IPPORT_RESERVED || 237 fromp->sin_port < IPPORT_RESERVED/2) { 238 syslog(LOG_NOTICE, "Connection from %s on illegal port", 239 inet_ntoa(fromp->sin_addr)); 240 fatal(f, "Permission denied"); 241 } 242 write(f, "", 1); 243 244 if (do_rlogin(hp->h_name) == 0) { 245 if (hostok) 246 authenticated++; 247 else 248 write(f, "rlogind: Host address mismatch.\r\n", 249 sizeof("rlogind: Host address mismatch.\r\n") - 1); 250 } 251 252 for (c = 'p'; c <= 's'; c++) { 253 struct stat stb; 254 line = "/dev/ptyXX"; 255 line[strlen("/dev/pty")] = c; 256 line[strlen("/dev/ptyp")] = '0'; 257 if (stat(line, &stb) < 0) 258 break; 259 for (i = 0; i < 16; i++) { 260 line[sizeof("/dev/ptyp") - 1] = "0123456789abcdef"[i]; 261 p = open(line, O_RDWR); 262 if (p > 0) 263 goto gotpty; 264 } 265 } 266 fatal(f, "Out of ptys"); 267 /*NOTREACHED*/ 268 gotpty: 269 (void) ioctl(p, TIOCSWINSZ, &win); 270 netf = f; 271 line[strlen("/dev/")] = 't'; 272 t = open(line, O_RDWR); 273 if (t < 0) 274 fatalperror(f, line); 275 if (fchmod(t, 0)) 276 fatalperror(f, line); 277 (void)signal(SIGHUP, SIG_IGN); 278 vhangup(); 279 (void)signal(SIGHUP, SIG_DFL); 280 t = open(line, O_RDWR); 281 if (t < 0) 282 fatalperror(f, line); 283 setup_term(t); 284 #ifdef DEBUG 285 { 286 int tt = open("/dev/tty", O_RDWR); 287 if (tt > 0) { 288 (void)ioctl(tt, TIOCNOTTY, 0); 289 (void)close(tt); 290 } 291 } 292 #endif 293 pid = fork(); 294 if (pid < 0) 295 fatalperror(f, ""); 296 if (pid == 0) { 297 if (setsid() < 0) 298 fatalperror(f, "setsid"); 299 if (ioctl(t, TIOCSCTTY, 0) < 0) 300 fatalperror(f, "ioctl(sctty)"); 301 close(f), close(p); 302 dup2(t, 0), dup2(t, 1), dup2(t, 2); 303 close(t); 304 if (authenticated) 305 execl("/bin/login", "login", "-p", 306 "-h", hp->h_name, "-f", lusername, 0); 307 else 308 execl("/bin/login", "login", "-p", 309 "-h", hp->h_name, lusername, 0); 310 fatalperror(2, "/bin/login"); 311 /*NOTREACHED*/ 312 } 313 close(t); 314 315 #ifdef KERBEROS 316 /* 317 * If encrypted, don't turn on NBIO or the des read/write 318 * routines will croak. 319 */ 320 321 if (encrypt) 322 (void) des_write(f, SECURE_MESSAGE, sizeof(SECURE_MESSAGE)); 323 else 324 #endif 325 ioctl(f, FIONBIO, &on); 326 ioctl(p, FIONBIO, &on); 327 ioctl(p, TIOCPKT, &on); 328 signal(SIGTSTP, SIG_IGN); 329 signal(SIGCHLD, cleanup); 330 setpgrp(0, 0); 331 protocol(f, p); 332 signal(SIGCHLD, SIG_IGN); 333 cleanup(); 334 } 335 336 char magic[2] = { 0377, 0377 }; 337 char oobdata[] = {TIOCPKT_WINDOW}; 338 339 /* 340 * Handle a "control" request (signaled by magic being present) 341 * in the data stream. For now, we are only willing to handle 342 * window size changes. 343 */ 344 control(pty, cp, n) 345 int pty; 346 char *cp; 347 int n; 348 { 349 struct winsize w; 350 351 if (n < 4+sizeof (w) || cp[2] != 's' || cp[3] != 's') 352 return (0); 353 oobdata[0] &= ~TIOCPKT_WINDOW; /* we know he heard */ 354 bcopy(cp+4, (char *)&w, sizeof(w)); 355 w.ws_row = ntohs(w.ws_row); 356 w.ws_col = ntohs(w.ws_col); 357 w.ws_xpixel = ntohs(w.ws_xpixel); 358 w.ws_ypixel = ntohs(w.ws_ypixel); 359 (void)ioctl(pty, TIOCSWINSZ, &w); 360 return (4+sizeof (w)); 361 } 362 363 /* 364 * rlogin "protocol" machine. 365 */ 366 protocol(f, p) 367 int f, p; 368 { 369 char pibuf[1024], fibuf[1024], *pbp, *fbp; 370 register pcc = 0, fcc = 0; 371 int cc, nfd, pmask, fmask; 372 char cntl; 373 374 /* 375 * Must ignore SIGTTOU, otherwise we'll stop 376 * when we try and set slave pty's window shape 377 * (our controlling tty is the master pty). 378 */ 379 (void) signal(SIGTTOU, SIG_IGN); 380 send(f, oobdata, 1, MSG_OOB); /* indicate new rlogin */ 381 if (f > p) 382 nfd = f + 1; 383 else 384 nfd = p + 1; 385 fmask = 1 << f; 386 pmask = 1 << p; 387 for (;;) { 388 int ibits, obits, ebits; 389 390 ibits = 0; 391 obits = 0; 392 if (fcc) 393 obits |= pmask; 394 else 395 ibits |= fmask; 396 if (pcc >= 0) 397 if (pcc) 398 obits |= fmask; 399 else 400 ibits |= pmask; 401 ebits = pmask; 402 if (select(nfd, &ibits, obits ? &obits : (int *)NULL, 403 &ebits, 0) < 0) { 404 if (errno == EINTR) 405 continue; 406 fatalperror(f, "select"); 407 } 408 if (ibits == 0 && obits == 0 && ebits == 0) { 409 /* shouldn't happen... */ 410 sleep(5); 411 continue; 412 } 413 #define pkcontrol(c) ((c)&(TIOCPKT_FLUSHWRITE|TIOCPKT_NOSTOP|TIOCPKT_DOSTOP)) 414 if (ebits & pmask) { 415 cc = read(p, &cntl, 1); 416 if (cc == 1 && pkcontrol(cntl)) { 417 cntl |= oobdata[0]; 418 send(f, &cntl, 1, MSG_OOB); 419 if (cntl & TIOCPKT_FLUSHWRITE) { 420 pcc = 0; 421 ibits &= ~pmask; 422 } 423 } 424 } 425 if (ibits & fmask) { 426 #ifdef KERBEROS 427 if (encrypt) 428 fcc = des_read(f, fibuf, sizeof(fibuf)); 429 else 430 #endif 431 fcc = read(f, fibuf, sizeof(fibuf)); 432 if (fcc < 0 && errno == EWOULDBLOCK) 433 fcc = 0; 434 else { 435 register char *cp; 436 int left, n; 437 438 if (fcc <= 0) 439 break; 440 fbp = fibuf; 441 442 top: 443 for (cp = fibuf; cp < fibuf+fcc-1; cp++) 444 if (cp[0] == magic[0] && 445 cp[1] == magic[1]) { 446 left = fcc - (cp-fibuf); 447 n = control(p, cp, left); 448 if (n) { 449 left -= n; 450 if (left > 0) 451 bcopy(cp+n, cp, left); 452 fcc -= n; 453 goto top; /* n^2 */ 454 } 455 } 456 obits |= pmask; /* try write */ 457 } 458 } 459 460 if ((obits & pmask) && fcc > 0) { 461 cc = write(p, fbp, fcc); 462 if (cc > 0) { 463 fcc -= cc; 464 fbp += cc; 465 } 466 } 467 468 if (ibits & pmask) { 469 pcc = read(p, pibuf, sizeof (pibuf)); 470 pbp = pibuf; 471 if (pcc < 0 && errno == EWOULDBLOCK) 472 pcc = 0; 473 else if (pcc <= 0) 474 break; 475 else if (pibuf[0] == 0) { 476 pbp++, pcc--; 477 #ifdef KERBEROS 478 if (!encrypt) 479 #endif 480 obits |= fmask; /* try a write */ 481 } else { 482 if (pkcontrol(pibuf[0])) { 483 pibuf[0] |= oobdata[0]; 484 send(f, &pibuf[0], 1, MSG_OOB); 485 } 486 pcc = 0; 487 } 488 } 489 if ((obits & fmask) && pcc > 0) { 490 #ifdef KERBEROS 491 if (encrypt) 492 cc = des_write(f, pbp, pcc); 493 else 494 #endif 495 cc = write(f, pbp, pcc); 496 if (cc < 0 && errno == EWOULDBLOCK) { 497 /* also shouldn't happen */ 498 sleep(5); 499 continue; 500 } 501 if (cc > 0) { 502 pcc -= cc; 503 pbp += cc; 504 } 505 } 506 } 507 } 508 509 cleanup() 510 { 511 char *p; 512 513 p = line + sizeof("/dev/") - 1; 514 if (logout(p)) 515 logwtmp(p, "", ""); 516 (void)chmod(line, 0666); 517 (void)chown(line, 0, 0); 518 *p = 'p'; 519 (void)chmod(line, 0666); 520 (void)chown(line, 0, 0); 521 shutdown(netf, 2); 522 exit(1); 523 } 524 525 fatal(f, msg) 526 int f; 527 char *msg; 528 { 529 char buf[BUFSIZ]; 530 531 buf[0] = '\01'; /* error indicator */ 532 (void) sprintf(buf + 1, "rlogind: %s.\r\n", msg); 533 (void) write(f, buf, strlen(buf)); 534 exit(1); 535 } 536 537 fatalperror(f, msg) 538 int f; 539 char *msg; 540 { 541 char buf[BUFSIZ]; 542 extern int sys_nerr; 543 extern char *sys_errlist[]; 544 545 if ((unsigned)errno < sys_nerr) 546 (void) sprintf(buf, "%s: %s", msg, sys_errlist[errno]); 547 else 548 (void) sprintf(buf, "%s: Error %d", msg, errno); 549 fatal(f, buf); 550 } 551 552 do_rlogin(host) 553 char *host; 554 { 555 556 getstr(rusername, sizeof(rusername), "remuser too long"); 557 getstr(lusername, sizeof(lusername), "locuser too long"); 558 getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type too long"); 559 560 if (getuid()) 561 return(-1); 562 pwd = getpwnam(lusername); 563 if (pwd == NULL) 564 return(-1); 565 return(ruserok(host, SUPERUSER(pwd), rusername, lusername)); 566 } 567 568 569 getstr(buf, cnt, errmsg) 570 char *buf; 571 int cnt; 572 char *errmsg; 573 { 574 char c; 575 576 do { 577 if (read(0, &c, 1) != 1) 578 exit(1); 579 if (--cnt < 0) 580 fatal(1, errmsg); 581 *buf++ = c; 582 } while (c != 0); 583 } 584 585 extern char **environ; 586 587 setup_term(fd) 588 int fd; 589 { 590 struct termios tt; 591 register char *cp = index(term+ENVSIZE, '/'); 592 char *speed; 593 594 tcgetattr(fd, &tt); 595 if (cp) { 596 *cp++ = '\0'; 597 speed = cp; 598 cp = index(speed, '/'); 599 if (cp) 600 *cp++ = '\0'; 601 cfsetspeed(&tt, atoi(speed)); 602 } 603 tt.c_iflag = BRKINT|ICRNL|IXON|ISTRIP|IEXTEN|IMAXBEL; 604 tt.c_oflag = OPOST|ONLCR|OXTABS; 605 tt.c_lflag = ISIG|ICANON|ECHO; 606 tcsetattr(fd, TCSADFLUSH, &tt); 607 608 env[0] = term; 609 env[1] = 0; 610 environ = env; 611 } 612 613 #ifdef KERBEROS 614 #define VERSION_SIZE 9 615 616 /* 617 * Do the remote kerberos login to the named host with the 618 * given inet address 619 * 620 * Return 0 on valid authorization 621 * Return -1 on valid authentication, no authorization 622 * Return >0 for error conditions 623 */ 624 do_krb_login(host, dest, encrypt) 625 char *host; 626 struct sockaddr_in *dest; 627 int encrypt; 628 { 629 int rc; 630 char instance[INST_SZ], version[VERSION_SIZE]; 631 long authopts = 0L; /* !mutual */ 632 struct sockaddr_in faddr; 633 634 if (getuid()) 635 return(KFAILURE); 636 637 kdata = (AUTH_DAT *) auth_buf; 638 ticket = (KTEXT) tick_buf; 639 strcpy(instance, "*"); 640 641 if (encrypt) { 642 rc = sizeof(faddr); 643 if (getsockname(0, &faddr, &rc)) 644 return(-1); 645 authopts = KOPT_DO_MUTUAL; 646 rc = krb_recvauth( 647 authopts, 0, 648 ticket, "rcmd", 649 instance, dest, &faddr, 650 kdata, "", schedule, version); 651 des_set_key(kdata->session, schedule); 652 653 } else { 654 rc = krb_recvauth( 655 authopts, 0, 656 ticket, "rcmd", 657 instance, dest, (struct sockaddr_in *) 0, 658 kdata, "", (bit_64 *) 0, version); 659 } 660 661 if (rc != KSUCCESS) 662 return(rc); 663 664 if ((rc = krb_kntoln(kdata, rusername)) != KSUCCESS) 665 return(rc); 666 667 getstr(lusername, sizeof(lusername), "locuser"); 668 /* get the "cmd" in the rcmd protocol */ 669 getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type"); 670 671 pwd = getpwnam(lusername); 672 if (pwd == NULL) 673 return(-1); 674 675 /* returns nonzero for no access */ 676 /* return(ruserok(host, SUPERUSER(pwd), rusername, lusername)); */ 677 if (kuserok(kdata,lusername) != 0) 678 return(-1); 679 680 return(0); 681 682 } 683 684 #endif /* KERBEROS */ 685 686 usage() 687 { 688 #ifdef KERBEROS 689 syslog(LOG_ERR, "usage: rlogind [-k | -v] [-l] [-n]"); 690 #else 691 syslog(LOG_ERR, "usage: rlogind [-l] [-n]"); 692 #endif 693 } 694 695 /* 696 * Check whether host h is in our local domain, 697 * as determined by the part of the name following 698 * the first '.' in its name and in ours. 699 * If either name is unqualified (contains no '.'), 700 * assume that the host is local, as it will be 701 * interpreted as such. 702 */ 703 local_domain(h) 704 char *h; 705 { 706 char localhost[MAXHOSTNAMELEN]; 707 char *p1, *p2 = index(h, '.'); 708 709 (void) gethostname(localhost, sizeof(localhost)); 710 p1 = index(localhost, '.'); 711 if (p1 == NULL || p2 == NULL || !strcasecmp(p1, p2)) 712 return(1); 713 return(0); 714 } 715