rshd.c revision 67001
1/*- 2 * Copyright (c) 1988, 1989, 1992, 1993, 1994 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. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34#ifndef lint 35static const char copyright[] = 36"@(#) Copyright (c) 1988, 1989, 1992, 1993, 1994\n\ 37 The Regents of the University of California. All rights reserved.\n"; 38#endif /* not lint */ 39 40#ifndef lint 41#if 0 42static const char sccsid[] = "@(#)rshd.c 8.2 (Berkeley) 4/6/94"; 43#endif 44static const char rcsid[] = 45 "$FreeBSD: head/libexec/rshd/rshd.c 67001 2000-10-12 07:18:20Z ru $"; 46#endif /* not lint */ 47 48/* 49 * remote shell server: 50 * [port]\0 51 * remuser\0 52 * locuser\0 53 * command\0 54 * data 55 */ 56#include <sys/param.h> 57#include <sys/ioctl.h> 58#include <sys/time.h> 59#include <sys/socket.h> 60 61#include <netinet/in_systm.h> 62#include <netinet/in.h> 63#include <netinet/ip.h> 64#include <netinet/tcp.h> 65#include <arpa/inet.h> 66#include <netdb.h> 67 68#include <errno.h> 69#include <fcntl.h> 70#include <libutil.h> 71#include <paths.h> 72#include <pwd.h> 73#include <signal.h> 74#include <stdio.h> 75#include <stdlib.h> 76#include <string.h> 77#include <syslog.h> 78#include <unistd.h> 79#ifdef LOGIN_CAP 80#include <login_cap.h> 81#endif 82 83/* wrapper for KAME-special getnameinfo() */ 84#ifndef NI_WITHSCOPEID 85#define NI_WITHSCOPEID 0 86#endif 87 88int keepalive = 1; 89int log_success; /* If TRUE, log all successful accesses */ 90int sent_null; 91int no_delay; 92#ifdef CRYPT 93int doencrypt = 0; 94#endif 95 96union sockunion { 97 struct sockinet { 98 u_char si_len; 99 u_char si_family; 100 u_short si_port; 101 } su_si; 102 struct sockaddr_in su_sin; 103 struct sockaddr_in6 su_sin6; 104}; 105#define su_len su_si.si_len 106#define su_family su_si.si_family 107#define su_port su_si.si_port 108 109void doit __P((union sockunion *)); 110void error __P((const char *, ...)); 111void getstr __P((char *, int, char *)); 112int local_domain __P((char *)); 113char *topdomain __P((char *)); 114void usage __P((void)); 115 116 117#define OPTIONS "alnDL" 118 119int 120main(argc, argv) 121 int argc; 122 char *argv[]; 123{ 124 extern int __check_rhosts_file; 125 struct linger linger; 126 int ch, on = 1, fromlen; 127 struct sockaddr_storage from; 128 129 openlog("rshd", LOG_PID | LOG_ODELAY, LOG_DAEMON); 130 131 opterr = 0; 132 while ((ch = getopt(argc, argv, OPTIONS)) != -1) 133 switch (ch) { 134 case 'a': 135 /* ignored for compatability */ 136 break; 137 case 'l': 138 __check_rhosts_file = 0; 139 break; 140 case 'n': 141 keepalive = 0; 142 break; 143#ifdef CRYPT 144 case 'x': 145 doencrypt = 1; 146 break; 147#endif 148 case 'D': 149 no_delay = 1; 150 break; 151 case 'L': 152 log_success = 1; 153 break; 154 case '?': 155 default: 156 usage(); 157 break; 158 } 159 160 argc -= optind; 161 argv += optind; 162 163#ifdef CRYPT 164 if (doencrypt) { 165 syslog(LOG_ERR, "-k is required for -x"); 166 exit(2); 167 } 168#endif 169 170 fromlen = sizeof (from); 171 if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) { 172 syslog(LOG_ERR, "getpeername: %m"); 173 exit(1); 174 } 175 if (keepalive && 176 setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, (char *)&on, 177 sizeof(on)) < 0) 178 syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m"); 179 linger.l_onoff = 1; 180 linger.l_linger = 60; /* XXX */ 181 if (setsockopt(0, SOL_SOCKET, SO_LINGER, (char *)&linger, 182 sizeof (linger)) < 0) 183 syslog(LOG_WARNING, "setsockopt (SO_LINGER): %m"); 184 if (no_delay && 185 setsockopt(0, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) < 0) 186 syslog(LOG_WARNING, "setsockopt (TCP_NODELAY): %m"); 187 doit((union sockunion *)&from); 188 /* NOTREACHED */ 189 return(0); 190} 191 192char username[20] = "USER="; 193char homedir[64] = "HOME="; 194char shell[64] = "SHELL="; 195char path[100] = "PATH="; 196char *envinit[] = 197 {homedir, shell, path, username, 0}; 198char **environ; 199 200void 201doit(fromp) 202 union sockunion *fromp; 203{ 204 extern char *__rcmd_errstr; /* syslog hook from libc/net/rcmd.c. */ 205 struct passwd *pwd; 206 u_short port; 207 fd_set ready, readfrom; 208 int cc, nfd, pv[2], pid, s; 209 int one = 1; 210 char *errorstr; 211 char *cp, sig, buf[BUFSIZ]; 212 char cmdbuf[NCARGS+1], locuser[16], remuser[16]; 213 char fromhost[2 * MAXHOSTNAMELEN + 1]; 214 char numericname[INET6_ADDRSTRLEN]; 215 int af = fromp->su_family, err; 216#ifdef CRYPT 217 int rc; 218 int pv1[2], pv2[2]; 219#endif 220#ifdef LOGIN_CAP 221 login_cap_t *lc; 222#endif 223 224 (void) signal(SIGINT, SIG_DFL); 225 (void) signal(SIGQUIT, SIG_DFL); 226 (void) signal(SIGTERM, SIG_DFL); 227 fromp->su_port = ntohs((u_short)fromp->su_port); 228 if (af != AF_INET 229#ifdef INET6 230 && af != AF_INET6 231#endif 232 ) { 233 syslog(LOG_ERR, "malformed \"from\" address (af %d)\n", af); 234 exit(1); 235 } 236 err = getnameinfo((struct sockaddr *)fromp, fromp->su_len, numericname, 237 sizeof(numericname), NULL, 0, 238 NI_NUMERICHOST|NI_WITHSCOPEID); 239 /* XXX: do 'err' check */ 240#ifdef IP_OPTIONS 241 if (af == AF_INET) { 242 u_char optbuf[BUFSIZ/3]; 243 int optsize = sizeof(optbuf), ipproto, i; 244 struct protoent *ip; 245 246 if ((ip = getprotobyname("ip")) != NULL) 247 ipproto = ip->p_proto; 248 else 249 ipproto = IPPROTO_IP; 250 if (!getsockopt(0, ipproto, IP_OPTIONS, (char *)optbuf, &optsize) && 251 optsize != 0) { 252 for (i = 0; i < optsize; ) { 253 u_char c = optbuf[i]; 254 if (c == IPOPT_LSRR || c == IPOPT_SSRR) { 255 syslog(LOG_NOTICE, 256 "connection refused from %s with IP option %s", 257 numericname, 258 c == IPOPT_LSRR ? "LSRR" : "SSRR"); 259 exit(1); 260 } 261 if (c == IPOPT_EOL) 262 break; 263 i += (c == IPOPT_NOP) ? 1 : optbuf[i+1]; 264 } 265 } 266 } 267#endif 268 269 if (fromp->su_port >= IPPORT_RESERVED || 270 fromp->su_port < IPPORT_RESERVED/2) { 271 syslog(LOG_NOTICE|LOG_AUTH, 272 "connection from %s on illegal port %u", 273 numericname, 274 fromp->su_port); 275 exit(1); 276 } 277 278 (void) alarm(60); 279 port = 0; 280 s = 0; /* not set or used if port == 0 */ 281 for (;;) { 282 char c; 283 if ((cc = read(STDIN_FILENO, &c, 1)) != 1) { 284 if (cc < 0) 285 syslog(LOG_NOTICE, "read: %m"); 286 shutdown(0, 1+1); 287 exit(1); 288 } 289 if (c == 0) 290 break; 291 port = port * 10 + c - '0'; 292 } 293 294 (void) alarm(0); 295 if (port != 0) { 296 int lport = IPPORT_RESERVED - 1; 297 s = rresvport_af(&lport, af); 298 if (s < 0) { 299 syslog(LOG_ERR, "can't get stderr port: %m"); 300 exit(1); 301 } 302 if (port >= IPPORT_RESERVED || 303 port < IPPORT_RESERVED/2) { 304 syslog(LOG_NOTICE|LOG_AUTH, 305 "2nd socket from %s on unreserved port %u", 306 numericname, 307 port); 308 exit(1); 309 } 310 fromp->su_port = htons(port); 311 if (connect(s, (struct sockaddr *)fromp, fromp->su_len) < 0) { 312 syslog(LOG_INFO, "connect second port %d: %m", port); 313 exit(1); 314 } 315 } 316 317 errorstr = NULL; 318 realhostname_sa(fromhost, sizeof(fromhost) - 1, 319 (struct sockaddr *)fromp, 320 fromp->su_len); 321 fromhost[sizeof(fromhost) - 1] = '\0'; 322 323#ifdef CRYPT 324 if (doencrypt && af == AF_INET) { 325 struct sockaddr_in local_addr; 326 rc = sizeof(local_addr); 327 if (getsockname(0, (struct sockaddr *)&local_addr, 328 &rc) < 0) { 329 syslog(LOG_ERR, "getsockname: %m"); 330 error("rlogind: getsockname: %m"); 331 exit(1); 332 } 333 authopts = KOPT_DO_MUTUAL; 334 rc = krb_recvauth(authopts, 0, ticket, 335 "rcmd", instance, &fromaddr, 336 &local_addr, kdata, "", schedule, 337 version); 338 des_set_key(&kdata->session, schedule); 339 } 340#endif 341 getstr(remuser, sizeof(remuser), "remuser"); 342 343 getstr(locuser, sizeof(locuser), "locuser"); 344 getstr(cmdbuf, sizeof(cmdbuf), "command"); 345 setpwent(); 346 pwd = getpwnam(locuser); 347 if (pwd == NULL) { 348 syslog(LOG_INFO|LOG_AUTH, 349 "%s@%s as %s: unknown login. cmd='%.80s'", 350 remuser, fromhost, locuser, cmdbuf); 351 if (errorstr == NULL) 352 errorstr = "Login incorrect.\n"; 353 goto fail; 354 } 355#ifdef LOGIN_CAP 356 lc = login_getpwclass(pwd); 357#endif 358 if (chdir(pwd->pw_dir) < 0) { 359#ifdef LOGIN_CAP 360 if (chdir("/") < 0 || 361 login_getcapbool(lc, "requirehome", !!pwd->pw_uid)) { 362 syslog(LOG_INFO|LOG_AUTH, 363 "%s@%s as %s: no home directory. cmd='%.80s'", 364 remuser, fromhost, locuser, cmdbuf); 365 error("No remote home directory.\n"); 366 exit(0); 367 } 368#else 369 (void) chdir("/"); 370#ifdef notdef 371 syslog(LOG_INFO|LOG_AUTH, 372 "%s@%s as %s: no home directory. cmd='%.80s'", 373 remuser, fromhost, locuser, cmdbuf); 374 error("No remote directory.\n"); 375 exit(1); 376#endif 377#endif 378 pwd->pw_dir = "/"; 379 } 380 381 382 if (errorstr || 383 (pwd->pw_expire && time(NULL) >= pwd->pw_expire) || 384 iruserok_sa(fromp, fromp->su_len, pwd->pw_uid == 0, 385 remuser, locuser) < 0) { 386 if (__rcmd_errstr) 387 syslog(LOG_INFO|LOG_AUTH, 388 "%s@%s as %s: permission denied (%s). cmd='%.80s'", 389 remuser, fromhost, locuser, __rcmd_errstr, 390 cmdbuf); 391 else 392 syslog(LOG_INFO|LOG_AUTH, 393 "%s@%s as %s: permission denied. cmd='%.80s'", 394 remuser, fromhost, locuser, cmdbuf); 395fail: 396 if (errorstr == NULL) 397 errorstr = "Login incorrect.\n"; 398 error(errorstr, fromhost); 399 exit(1); 400 } 401 402 if (pwd->pw_uid && !access(_PATH_NOLOGIN, F_OK)) { 403 error("Logins currently disabled.\n"); 404 exit(1); 405 } 406#ifdef LOGIN_CAP 407 if (lc != NULL && fromp->su_family == AF_INET) { /*XXX*/ 408 char remote_ip[MAXHOSTNAMELEN]; 409 410 strncpy(remote_ip, numericname, 411 sizeof(remote_ip) - 1); 412 remote_ip[sizeof(remote_ip) - 1] = 0; 413 if (!auth_hostok(lc, fromhost, remote_ip)) { 414 syslog(LOG_INFO|LOG_AUTH, 415 "%s@%s as %s: permission denied (%s). cmd='%.80s'", 416 remuser, fromhost, locuser, __rcmd_errstr, 417 cmdbuf); 418 error("Login incorrect.\n"); 419 exit(1); 420 } 421 if (!auth_timeok(lc, time(NULL))) { 422 error("Logins not available right now\n"); 423 exit(1); 424 } 425 } 426#endif /* !LOGIN_CAP */ 427#if BSD > 43 428 /* before fork, while we're session leader */ 429 if (setlogin(pwd->pw_name) < 0) 430 syslog(LOG_ERR, "setlogin() failed: %m"); 431#endif 432 433 (void) write(STDERR_FILENO, "\0", 1); 434 sent_null = 1; 435 436 if (port) { 437 if (pipe(pv) < 0) { 438 error("Can't make pipe.\n"); 439 exit(1); 440 } 441#ifdef CRYPT 442 if (doencrypt) { 443 if (pipe(pv1) < 0) { 444 error("Can't make 2nd pipe.\n"); 445 exit(1); 446 } 447 if (pipe(pv2) < 0) { 448 error("Can't make 3rd pipe.\n"); 449 exit(1); 450 } 451 } 452#endif 453 pid = fork(); 454 if (pid == -1) { 455 error("Can't fork; try again.\n"); 456 exit(1); 457 } 458 if (pid) { 459#ifdef CRYPT 460 if (doencrypt) { 461 static char msg[] = SECURE_MESSAGE; 462 (void) close(pv1[1]); 463 (void) close(pv2[1]); 464 des_enc_write(s, msg, sizeof(msg) - 1, 465 schedule, &kdata->session); 466 467 } else 468#endif 469 { 470 (void) close(0); 471 (void) close(1); 472 } 473 (void) close(2); 474 (void) close(pv[1]); 475 476 FD_ZERO(&readfrom); 477 FD_SET(s, &readfrom); 478 FD_SET(pv[0], &readfrom); 479 if (pv[0] > s) 480 nfd = pv[0]; 481 else 482 nfd = s; 483#ifdef CRYPT 484 if (doencrypt) { 485 FD_ZERO(&writeto); 486 FD_SET(pv2[0], &writeto); 487 FD_SET(pv1[0], &readfrom); 488 489 nfd = MAX(nfd, pv2[0]); 490 nfd = MAX(nfd, pv1[0]); 491 } else 492#endif 493 ioctl(pv[0], FIONBIO, (char *)&one); 494 495 /* should set s nbio! */ 496 nfd++; 497 do { 498 ready = readfrom; 499#ifdef CRYPT 500 if (doencrypt) { 501 wready = writeto; 502 if (select(nfd, &ready, 503 &wready, (fd_set *) 0, 504 (struct timeval *) 0) < 0) 505 break; 506 } else 507#endif 508 if (select(nfd, &ready, (fd_set *)0, 509 (fd_set *)0, (struct timeval *)0) < 0) 510 break; 511 if (FD_ISSET(s, &ready)) { 512 int ret; 513#ifdef CRYPT 514 if (doencrypt) 515 ret = des_enc_read(s, &sig, 1, 516 schedule, &kdata->session); 517 else 518#endif 519 ret = read(s, &sig, 1); 520 if (ret <= 0) 521 FD_CLR(s, &readfrom); 522 else 523 killpg(pid, sig); 524 } 525 if (FD_ISSET(pv[0], &ready)) { 526 errno = 0; 527 cc = read(pv[0], buf, sizeof(buf)); 528 if (cc <= 0) { 529 shutdown(s, 1+1); 530 FD_CLR(pv[0], &readfrom); 531 } else { 532#ifdef CRYPT 533 if (doencrypt) 534 (void) 535 des_enc_write(s, buf, cc, 536 schedule, &kdata->session); 537 else 538#endif 539 (void) 540 write(s, buf, cc); 541 } 542 } 543#ifdef CRYPT 544 if (doencrypt && FD_ISSET(pv1[0], &ready)) { 545 errno = 0; 546 cc = read(pv1[0], buf, sizeof(buf)); 547 if (cc <= 0) { 548 shutdown(pv1[0], 1+1); 549 FD_CLR(pv1[0], &readfrom); 550 } else 551 (void) des_enc_write(STDOUT_FILENO, 552 buf, cc, 553 schedule, &kdata->session); 554 } 555 556 if (doencrypt && FD_ISSET(pv2[0], &wready)) { 557 errno = 0; 558 cc = des_enc_read(STDIN_FILENO, 559 buf, sizeof(buf), 560 schedule, &kdata->session); 561 if (cc <= 0) { 562 shutdown(pv2[0], 1+1); 563 FD_CLR(pv2[0], &writeto); 564 } else 565 (void) write(pv2[0], buf, cc); 566 } 567#endif 568 569 } while (FD_ISSET(s, &readfrom) || 570#ifdef CRYPT 571 (doencrypt && FD_ISSET(pv1[0], &readfrom)) || 572#endif 573 FD_ISSET(pv[0], &readfrom)); 574 exit(0); 575 } 576 setpgrp(0, getpid()); 577 (void) close(s); 578 (void) close(pv[0]); 579#ifdef CRYPT 580 if (doencrypt) { 581 close(pv1[0]); close(pv2[0]); 582 dup2(pv1[1], 1); 583 dup2(pv2[1], 0); 584 close(pv1[1]); 585 close(pv2[1]); 586 } 587#endif 588 dup2(pv[1], 2); 589 close(pv[1]); 590 } 591 if (*pwd->pw_shell == '\0') 592 pwd->pw_shell = _PATH_BSHELL; 593 environ = envinit; 594 strncat(homedir, pwd->pw_dir, sizeof(homedir)-6); 595 strcat(path, _PATH_DEFPATH); 596 strncat(shell, pwd->pw_shell, sizeof(shell)-7); 597 strncat(username, pwd->pw_name, sizeof(username)-6); 598 cp = strrchr(pwd->pw_shell, '/'); 599 if (cp) 600 cp++; 601 else 602 cp = pwd->pw_shell; 603#ifdef LOGIN_CAP 604 if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETALL) != 0) { 605 syslog(LOG_ERR, "setusercontext: %m"); 606 exit(1); 607 } 608 login_close(lc); 609#else 610 (void) setgid((gid_t)pwd->pw_gid); 611 initgroups(pwd->pw_name, pwd->pw_gid); 612 (void) setuid((uid_t)pwd->pw_uid); 613#endif 614 endpwent(); 615 if (log_success || pwd->pw_uid == 0) { 616 syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: cmd='%.80s'", 617 remuser, fromhost, locuser, cmdbuf); 618 } 619 execl(pwd->pw_shell, cp, "-c", cmdbuf, 0); 620 perror(pwd->pw_shell); 621 exit(1); 622} 623 624/* 625 * Report error to client. Note: can't be used until second socket has 626 * connected to client, or older clients will hang waiting for that 627 * connection first. 628 */ 629#if __STDC__ 630#include <stdarg.h> 631#else 632#include <varargs.h> 633#endif 634 635void 636#if __STDC__ 637error(const char *fmt, ...) 638#else 639error(fmt, va_alist) 640 char *fmt; 641 va_dcl 642#endif 643{ 644 va_list ap; 645 int len; 646 char *bp, buf[BUFSIZ]; 647#if __STDC__ 648 va_start(ap, fmt); 649#else 650 va_start(ap); 651#endif 652 bp = buf; 653 if (sent_null == 0) { 654 *bp++ = 1; 655 len = 1; 656 } else 657 len = 0; 658 (void)vsnprintf(bp, sizeof(buf) - 1, fmt, ap); 659 (void)write(STDERR_FILENO, buf, len + strlen(bp)); 660} 661 662void 663getstr(buf, cnt, err) 664 char *buf, *err; 665 int cnt; 666{ 667 char c; 668 669 do { 670 if (read(STDIN_FILENO, &c, 1) != 1) 671 exit(1); 672 *buf++ = c; 673 if (--cnt == 0) { 674 error("%s too long\n", err); 675 exit(1); 676 } 677 } while (c != 0); 678} 679 680/* 681 * Check whether host h is in our local domain, 682 * defined as sharing the last two components of the domain part, 683 * or the entire domain part if the local domain has only one component. 684 * If either name is unqualified (contains no '.'), 685 * assume that the host is local, as it will be 686 * interpreted as such. 687 */ 688int 689local_domain(h) 690 char *h; 691{ 692 char localhost[MAXHOSTNAMELEN]; 693 char *p1, *p2; 694 695 localhost[0] = 0; 696 (void) gethostname(localhost, sizeof(localhost) - 1); 697 localhost[sizeof(localhost) - 1] = '\0'; 698 p1 = topdomain(localhost); 699 p2 = topdomain(h); 700 if (p1 == NULL || p2 == NULL || !strcasecmp(p1, p2)) 701 return (1); 702 return (0); 703} 704 705char * 706topdomain(h) 707 char *h; 708{ 709 char *p, *maybe = NULL; 710 int dots = 0; 711 712 for (p = h + strlen(h); p >= h; p--) { 713 if (*p == '.') { 714 if (++dots == 2) 715 return (p); 716 maybe = p; 717 } 718 } 719 return (maybe); 720} 721 722void 723usage() 724{ 725 726 syslog(LOG_ERR, "usage: rshd [-%s]", OPTIONS); 727 exit(2); 728} 729