1 /* 2 * Copyright (c) 1995, 1996, 1998 Theo de Raadt. All rights reserved. 3 * Copyright (c) 1983, 1993, 1994 4 * The Regents of the University of California. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <sys/param.h> 32 #include <sys/socket.h> 33 #include <sys/stat.h> 34 35 #include <netinet/in.h> 36 #include <arpa/inet.h> 37 38 #include <signal.h> 39 #include <fcntl.h> 40 #include <netdb.h> 41 #include <unistd.h> 42 #include <pwd.h> 43 #include <errno.h> 44 #include <stdio.h> 45 #include <ctype.h> 46 #include <string.h> 47 #include <syslog.h> 48 #include <stdlib.h> 49 #include <netgroup.h> 50 51 int __ivaliduser(FILE *, in_addr_t, const char *, const char *); 52 int __ivaliduser_sa(FILE *, struct sockaddr *, socklen_t, 53 const char *, const char *); 54 static int __icheckhost(struct sockaddr *, socklen_t, const char *); 55 static char *__gethostloop(struct sockaddr *, socklen_t); 56 57 int 58 rcmd(char **ahost, int rport, const char *locuser, const char *remuser, 59 const char *cmd, int *fd2p) 60 { 61 return rcmd_af(ahost, rport, locuser, remuser, cmd, fd2p, AF_INET); 62 } 63 64 int 65 rcmd_af(char **ahost, int porta, const char *locuser, const char *remuser, 66 const char *cmd, int *fd2p, int af) 67 { 68 static char hbuf[MAXHOSTNAMELEN]; 69 char pbuf[NI_MAXSERV]; 70 struct addrinfo hints, *res, *r; 71 int error; 72 struct sockaddr_storage from; 73 fd_set *readsp = NULL; 74 sigset_t oldmask, mask; 75 pid_t pid; 76 int s, lport, timo; 77 char c, *p; 78 int refused; 79 in_port_t rport = porta; 80 81 /* call rcmdsh() with specified remote shell if appropriate. */ 82 if (!issetugid() && (p = getenv("RSH")) && *p) { 83 struct servent *sp = getservbyname("shell", "tcp"); 84 85 if (sp && sp->s_port == rport) 86 return (rcmdsh(ahost, rport, locuser, remuser, 87 cmd, p)); 88 } 89 90 /* use rsh(1) if non-root and remote port is shell. */ 91 if (geteuid()) { 92 struct servent *sp = getservbyname("shell", "tcp"); 93 94 if (sp && sp->s_port == rport) 95 return (rcmdsh(ahost, rport, locuser, remuser, 96 cmd, NULL)); 97 } 98 99 pid = getpid(); 100 snprintf(pbuf, sizeof(pbuf), "%u", ntohs(rport)); 101 memset(&hints, 0, sizeof(hints)); 102 hints.ai_family = af; 103 hints.ai_socktype = SOCK_STREAM; 104 hints.ai_flags = AI_CANONNAME; 105 error = getaddrinfo(*ahost, pbuf, &hints, &res); 106 if (error) { 107 #if 0 108 warnx("%s: %s", *ahost, gai_strerror(error)); 109 #endif 110 return (-1); 111 } 112 if (res->ai_canonname) { 113 strlcpy(hbuf, res->ai_canonname, sizeof(hbuf)); 114 *ahost = hbuf; 115 } else 116 ; /*XXX*/ 117 118 r = res; 119 refused = 0; 120 sigemptyset(&mask); 121 sigaddset(&mask, SIGURG); 122 sigprocmask(SIG_BLOCK, &mask, &oldmask); 123 for (timo = 1, lport = IPPORT_RESERVED - 1;;) { 124 s = rresvport_af(&lport, r->ai_family); 125 if (s < 0) { 126 if (errno == EAGAIN) 127 (void)fprintf(stderr, 128 "rcmd: socket: All ports in use\n"); 129 else 130 (void)fprintf(stderr, "rcmd: socket: %s\n", 131 strerror(errno)); 132 if (r->ai_next) { 133 r = r->ai_next; 134 continue; 135 } else { 136 sigprocmask(SIG_SETMASK, &oldmask, NULL); 137 freeaddrinfo(res); 138 return (-1); 139 } 140 } 141 fcntl(s, F_SETOWN, pid); 142 if (connect(s, r->ai_addr, r->ai_addrlen) >= 0) 143 break; 144 (void)close(s); 145 if (errno == EADDRINUSE) { 146 lport--; 147 continue; 148 } 149 if (errno == ECONNREFUSED) 150 refused++; 151 if (r->ai_next) { 152 int oerrno = errno; 153 char hbuf[NI_MAXHOST]; 154 const int niflags = NI_NUMERICHOST; 155 156 hbuf[0] = '\0'; 157 if (getnameinfo(r->ai_addr, r->ai_addrlen, 158 hbuf, sizeof(hbuf), NULL, 0, niflags) != 0) 159 strlcpy(hbuf, "(invalid)", sizeof hbuf); 160 (void)fprintf(stderr, "connect to address %s: ", hbuf); 161 errno = oerrno; 162 perror(0); 163 r = r->ai_next; 164 hbuf[0] = '\0'; 165 if (getnameinfo(r->ai_addr, r->ai_addrlen, 166 hbuf, sizeof(hbuf), NULL, 0, niflags) != 0) 167 strlcpy(hbuf, "(invalid)", sizeof hbuf); 168 (void)fprintf(stderr, "Trying %s...\n", hbuf); 169 continue; 170 } 171 if (refused && timo <= 16) { 172 (void)sleep(timo); 173 timo *= 2; 174 r = res; 175 refused = 0; 176 continue; 177 } 178 (void)fprintf(stderr, "%s: %s\n", res->ai_canonname, 179 strerror(errno)); 180 sigprocmask(SIG_SETMASK, &oldmask, NULL); 181 freeaddrinfo(res); 182 return (-1); 183 } 184 /* given "af" can be PF_UNSPEC, we need the real af for "s" */ 185 af = r->ai_family; 186 freeaddrinfo(res); 187 #if 0 188 /* 189 * try to rresvport() to the same port. This will make rresvport() 190 * fail it's first bind, resulting in it choosing a random port. 191 */ 192 lport--; 193 #endif 194 if (fd2p == 0) { 195 write(s, "", 1); 196 lport = 0; 197 } else { 198 char num[8]; 199 int s2 = rresvport_af(&lport, af), s3; 200 socklen_t len = sizeof(from); 201 int fdssize = howmany(MAX(s, s2)+1, NFDBITS) * sizeof(fd_mask); 202 203 if (s2 < 0) 204 goto bad; 205 readsp = (fd_set *)malloc(fdssize); 206 if (readsp == NULL) { 207 close(s2); 208 goto bad; 209 } 210 listen(s2, 1); 211 (void)snprintf(num, sizeof(num), "%d", lport); 212 if (write(s, num, strlen(num)+1) != strlen(num)+1) { 213 (void)fprintf(stderr, 214 "rcmd: write (setting up stderr): %s\n", 215 strerror(errno)); 216 (void)close(s2); 217 goto bad; 218 } 219 again: 220 bzero(readsp, fdssize); 221 FD_SET(s, readsp); 222 FD_SET(s2, readsp); 223 errno = 0; 224 if (select(MAX(s, s2) + 1, readsp, 0, 0, 0) < 1 || 225 !FD_ISSET(s2, readsp)) { 226 if (errno != 0) 227 (void)fprintf(stderr, 228 "rcmd: select (setting up stderr): %s\n", 229 strerror(errno)); 230 else 231 (void)fprintf(stderr, 232 "select: protocol failure in circuit setup\n"); 233 (void)close(s2); 234 goto bad; 235 } 236 s3 = accept(s2, (struct sockaddr *)&from, &len); 237 if (s3 < 0) { 238 (void)fprintf(stderr, 239 "rcmd: accept: %s\n", strerror(errno)); 240 lport = 0; 241 close(s2); 242 goto bad; 243 } 244 245 /* 246 * XXX careful for ftp bounce attacks. If discovered, shut them 247 * down and check for the real auxiliary channel to connect. 248 */ 249 switch (from.ss_family) { 250 case AF_INET: 251 case AF_INET6: 252 if (getnameinfo((struct sockaddr *)&from, len, 253 NULL, 0, num, sizeof(num), NI_NUMERICSERV) == 0 && 254 atoi(num) != 20) { 255 break; 256 } 257 close(s3); 258 goto again; 259 default: 260 break; 261 } 262 (void)close(s2); 263 264 *fd2p = s3; 265 switch (from.ss_family) { 266 case AF_INET: 267 case AF_INET6: 268 if (getnameinfo((struct sockaddr *)&from, len, 269 NULL, 0, num, sizeof(num), NI_NUMERICSERV) != 0 || 270 (atoi(num) >= IPPORT_RESERVED || 271 atoi(num) < IPPORT_RESERVED / 2)) { 272 (void)fprintf(stderr, 273 "socket: protocol failure in circuit setup.\n"); 274 goto bad2; 275 } 276 break; 277 default: 278 break; 279 } 280 } 281 (void)write(s, locuser, strlen(locuser)+1); 282 (void)write(s, remuser, strlen(remuser)+1); 283 (void)write(s, cmd, strlen(cmd)+1); 284 if (read(s, &c, 1) != 1) { 285 (void)fprintf(stderr, 286 "rcmd: %s: %s\n", *ahost, strerror(errno)); 287 goto bad2; 288 } 289 if (c != 0) { 290 while (read(s, &c, 1) == 1) { 291 (void)write(STDERR_FILENO, &c, 1); 292 if (c == '\n') 293 break; 294 } 295 goto bad2; 296 } 297 sigprocmask(SIG_SETMASK, &oldmask, NULL); 298 free(readsp); 299 return (s); 300 bad2: 301 if (lport) 302 (void)close(*fd2p); 303 bad: 304 if (readsp) 305 free(readsp); 306 (void)close(s); 307 sigprocmask(SIG_SETMASK, &oldmask, NULL); 308 return (-1); 309 } 310 311 int __check_rhosts_file = 1; 312 char *__rcmd_errstr; 313 314 int 315 ruserok(const char *rhost, int superuser, const char *ruser, const char *luser) 316 { 317 struct addrinfo hints, *res, *r; 318 int error; 319 320 memset(&hints, 0, sizeof(hints)); 321 hints.ai_family = PF_UNSPEC; 322 hints.ai_socktype = SOCK_DGRAM; /*dummy*/ 323 error = getaddrinfo(rhost, "0", &hints, &res); 324 if (error) 325 return (-1); 326 327 for (r = res; r; r = r->ai_next) { 328 if (iruserok_sa(r->ai_addr, r->ai_addrlen, superuser, ruser, 329 luser) == 0) { 330 freeaddrinfo(res); 331 return (0); 332 } 333 } 334 freeaddrinfo(res); 335 return (-1); 336 } 337 338 /* 339 * New .rhosts strategy: We are passed an ip address. We spin through 340 * hosts.equiv and .rhosts looking for a match. When the .rhosts only 341 * has ip addresses, we don't have to trust a nameserver. When it 342 * contains hostnames, we spin through the list of addresses the nameserver 343 * gives us and look for a match. 344 * 345 * Returns 0 if ok, -1 if not ok. 346 */ 347 int 348 iruserok(u_int32_t raddr, int superuser, const char *ruser, const char *luser) 349 { 350 struct sockaddr_in sin; 351 352 memset(&sin, 0, sizeof(sin)); 353 sin.sin_family = AF_INET; 354 sin.sin_len = sizeof(struct sockaddr_in); 355 memcpy(&sin.sin_addr, &raddr, sizeof(sin.sin_addr)); 356 return iruserok_sa(&sin, sizeof(struct sockaddr_in), superuser, ruser, 357 luser); 358 } 359 360 int 361 iruserok_sa(const void *raddr, int rlen, int superuser, const char *ruser, 362 const char *luser) 363 { 364 struct sockaddr *sa; 365 char *cp; 366 struct stat sbuf; 367 struct passwd *pwd; 368 FILE *hostf; 369 uid_t uid; 370 int first; 371 char pbuf[MAXPATHLEN]; 372 373 sa = (struct sockaddr *)raddr; 374 first = 1; 375 hostf = superuser ? NULL : fopen(_PATH_HEQUIV, "r"); 376 again: 377 if (hostf) { 378 if (__ivaliduser_sa(hostf, sa, rlen, luser, ruser) == 0) { 379 (void)fclose(hostf); 380 return (0); 381 } 382 (void)fclose(hostf); 383 } 384 if (first == 1 && (__check_rhosts_file || superuser)) { 385 first = 0; 386 if ((pwd = getpwnam(luser)) == NULL) 387 return (-1); 388 snprintf(pbuf, sizeof pbuf, "%s/.rhosts", pwd->pw_dir); 389 390 /* 391 * Change effective uid while opening .rhosts. If root and 392 * reading an NFS mounted file system, can't read files that 393 * are protected read/write owner only. 394 */ 395 uid = geteuid(); 396 (void)seteuid(pwd->pw_uid); 397 hostf = fopen(pbuf, "r"); 398 (void)seteuid(uid); 399 400 if (hostf == NULL) 401 return (-1); 402 /* 403 * If not a regular file, or is owned by someone other than 404 * user or root or if writeable by anyone but the owner, quit. 405 */ 406 cp = NULL; 407 if (lstat(pbuf, &sbuf) < 0) 408 cp = ".rhosts lstat failed"; 409 else if (!S_ISREG(sbuf.st_mode)) 410 cp = ".rhosts not regular file"; 411 else if (fstat(fileno(hostf), &sbuf) < 0) 412 cp = ".rhosts fstat failed"; 413 else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid) 414 cp = "bad .rhosts owner"; 415 else if (sbuf.st_mode & (S_IWGRP|S_IWOTH)) 416 cp = ".rhosts writable by other than owner"; 417 /* If there were any problems, quit. */ 418 if (cp) { 419 __rcmd_errstr = cp; 420 (void)fclose(hostf); 421 return (-1); 422 } 423 goto again; 424 } 425 return (-1); 426 } 427 428 /* 429 * XXX 430 * Don't make static, used by lpd(8). 431 * 432 * Returns 0 if ok, -1 if not ok. 433 */ 434 int 435 __ivaliduser(FILE *hostf, in_addr_t raddrl, const char *luser, 436 const char *ruser) 437 { 438 struct sockaddr_in sin; 439 440 memset(&sin, 0, sizeof(sin)); 441 sin.sin_family = AF_INET; 442 sin.sin_len = sizeof(struct sockaddr_in); 443 memcpy(&sin.sin_addr, &raddrl, sizeof(sin.sin_addr)); 444 return __ivaliduser_sa(hostf, (struct sockaddr *)&sin, sin.sin_len, 445 luser, ruser); 446 } 447 448 int 449 __ivaliduser_sa(FILE *hostf, struct sockaddr *raddr, socklen_t salen, 450 const char *luser, const char *ruser) 451 { 452 char *user, *p; 453 char *buf; 454 const char *auser, *ahost; 455 int hostok, userok; 456 char *rhost = (char *)-1; 457 char domain[MAXHOSTNAMELEN]; 458 size_t buflen; 459 460 getdomainname(domain, sizeof(domain)); 461 462 while ((buf = fgetln(hostf, &buflen))) { 463 p = buf; 464 if (*p == '#') 465 continue; 466 while (p < buf + buflen && *p != '\n' && *p != ' ' && *p != '\t') { 467 if (!isprint(*p)) 468 goto bail; 469 *p = isupper(*p) ? tolower(*p) : *p; 470 p++; 471 } 472 if (p >= buf + buflen) 473 continue; 474 if (*p == ' ' || *p == '\t') { 475 *p++ = '\0'; 476 while (p < buf + buflen && (*p == ' ' || *p == '\t')) 477 p++; 478 if (p >= buf + buflen) 479 continue; 480 user = p; 481 while (p < buf + buflen && *p != '\n' && *p != ' ' && 482 *p != '\t') { 483 if (!isprint(*p)) 484 goto bail; 485 p++; 486 } 487 } else 488 user = p; 489 *p = '\0'; 490 491 if (p == buf) 492 continue; 493 494 auser = *user ? user : luser; 495 ahost = buf; 496 497 if (strlen(ahost) >= MAXHOSTNAMELEN) 498 continue; 499 500 /* 501 * innetgr() must lookup a hostname (we do not attempt 502 * to change the semantics so that netgroups may have 503 * #.#.#.# addresses in the list.) 504 */ 505 if (ahost[0] == '+') 506 switch (ahost[1]) { 507 case '\0': 508 hostok = 1; 509 break; 510 case '@': 511 if (rhost == (char *)-1) 512 rhost = __gethostloop(raddr, salen); 513 hostok = 0; 514 if (rhost) 515 hostok = innetgr(&ahost[2], rhost, 516 NULL, domain); 517 break; 518 default: 519 hostok = __icheckhost(raddr, salen, &ahost[1]); 520 break; 521 } 522 else if (ahost[0] == '-') 523 switch (ahost[1]) { 524 case '\0': 525 hostok = -1; 526 break; 527 case '@': 528 if (rhost == (char *)-1) 529 rhost = __gethostloop(raddr, salen); 530 hostok = 0; 531 if (rhost) 532 hostok = -innetgr(&ahost[2], rhost, 533 NULL, domain); 534 break; 535 default: 536 hostok = -__icheckhost(raddr, salen, &ahost[1]); 537 break; 538 } 539 else 540 hostok = __icheckhost(raddr, salen, ahost); 541 542 543 if (auser[0] == '+') 544 switch (auser[1]) { 545 case '\0': 546 userok = 1; 547 break; 548 case '@': 549 userok = innetgr(&auser[2], NULL, ruser, 550 domain); 551 break; 552 default: 553 userok = strcmp(ruser, &auser[1]) ? 0 : 1; 554 break; 555 } 556 else if (auser[0] == '-') 557 switch (auser[1]) { 558 case '\0': 559 userok = -1; 560 break; 561 case '@': 562 userok = -innetgr(&auser[2], NULL, ruser, 563 domain); 564 break; 565 default: 566 userok = strcmp(ruser, &auser[1]) ? 0 : -1; 567 break; 568 } 569 else 570 userok = strcmp(ruser, auser) ? 0 : 1; 571 572 /* Check if one component did not match */ 573 if (hostok == 0 || userok == 0) 574 continue; 575 576 /* Check if we got a forbidden pair */ 577 if (userok <= -1 || hostok <= -1) 578 return (-1); 579 580 /* Check if we got a valid pair */ 581 if (hostok >= 1 && userok >= 1) 582 return (0); 583 } 584 bail: 585 return (-1); 586 } 587 588 /* 589 * Returns "true" if match, 0 if no match. If we do not find any 590 * semblance of an A->PTR->A loop, allow a simple #.#.#.# match to work. 591 */ 592 static int 593 __icheckhost(struct sockaddr *raddr, socklen_t salen, const char *lhost) 594 { 595 struct addrinfo hints, *res, *r; 596 char h1[NI_MAXHOST], h2[NI_MAXHOST]; 597 int error; 598 const int niflags = NI_NUMERICHOST; 599 600 h1[0] = '\0'; 601 if (getnameinfo(raddr, salen, h1, sizeof(h1), NULL, 0, 602 niflags) != 0) 603 return (0); 604 605 /* Resolve laddr into sockaddr */ 606 memset(&hints, 0, sizeof(hints)); 607 hints.ai_family = raddr->sa_family; 608 hints.ai_socktype = SOCK_DGRAM; /*dummy*/ 609 res = NULL; 610 error = getaddrinfo(lhost, "0", &hints, &res); 611 if (error) 612 return (0); 613 614 /* 615 * Try string comparisons between raddr and laddr. 616 */ 617 for (r = res; r; r = r->ai_next) { 618 h2[0] = '\0'; 619 if (getnameinfo(r->ai_addr, r->ai_addrlen, h2, sizeof(h2), 620 NULL, 0, niflags) != 0) 621 continue; 622 if (strcmp(h1, h2) == 0) { 623 freeaddrinfo(res); 624 return (1); 625 } 626 } 627 628 /* No match. */ 629 freeaddrinfo(res); 630 return (0); 631 } 632 633 /* 634 * Return the hostname associated with the supplied address. 635 * Do a reverse lookup as well for security. If a loop cannot 636 * be found, pack the result of inet_ntoa() into the string. 637 */ 638 static char * 639 __gethostloop(struct sockaddr *raddr, socklen_t salen) 640 { 641 static char remotehost[NI_MAXHOST]; 642 char h1[NI_MAXHOST], h2[NI_MAXHOST]; 643 struct addrinfo hints, *res, *r; 644 int error; 645 const int niflags = NI_NUMERICHOST; 646 647 h1[0] = remotehost[0] = '\0'; 648 if (getnameinfo(raddr, salen, remotehost, sizeof(remotehost), 649 NULL, 0, NI_NAMEREQD) != 0) 650 return (NULL); 651 if (getnameinfo(raddr, salen, h1, sizeof(h1), NULL, 0, 652 niflags) != 0) 653 return (NULL); 654 655 /* 656 * Look up the name and check that the supplied 657 * address is in the list 658 */ 659 memset(&hints, 0, sizeof(hints)); 660 hints.ai_family = raddr->sa_family; 661 hints.ai_socktype = SOCK_DGRAM; /*dummy*/ 662 hints.ai_flags = AI_CANONNAME; 663 res = NULL; 664 error = getaddrinfo(remotehost, "0", &hints, &res); 665 if (error) 666 return (NULL); 667 668 for (r = res; r; r = r->ai_next) { 669 h2[0] = '\0'; 670 if (getnameinfo(r->ai_addr, r->ai_addrlen, h2, sizeof(h2), 671 NULL, 0, niflags) != 0) 672 continue; 673 if (strcmp(h1, h2) == 0) { 674 freeaddrinfo(res); 675 return (remotehost); 676 } 677 } 678 679 /* 680 * either the DNS adminstrator has made a configuration 681 * mistake, or someone has attempted to spoof us 682 */ 683 syslog(LOG_NOTICE, "rcmd: address %s not listed for host %s", 684 h1, res->ai_canonname ? res->ai_canonname : remotehost); 685 freeaddrinfo(res); 686 return (NULL); 687 } 688