1 /* 2 * Copyright (c) 1995, 1996 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. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by the University of 17 * California, Berkeley and its contributors. 18 * This product includes software developed by Theo de Raadt. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #if defined(LIBC_SCCS) && !defined(lint) 37 static char *rcsid = "$OpenBSD: rcmd.c,v 1.26 1997/07/09 01:08:47 millert Exp $"; 38 #endif /* LIBC_SCCS and not lint */ 39 40 #include <sys/param.h> 41 #include <sys/socket.h> 42 #include <sys/stat.h> 43 44 #include <netinet/in.h> 45 #include <arpa/inet.h> 46 47 #include <signal.h> 48 #include <fcntl.h> 49 #include <netdb.h> 50 #include <unistd.h> 51 #include <pwd.h> 52 #include <errno.h> 53 #include <stdio.h> 54 #include <ctype.h> 55 #include <string.h> 56 #include <syslog.h> 57 #include <stdlib.h> 58 #include <netgroup.h> 59 60 int __ivaliduser __P((FILE *, in_addr_t, const char *, const char *)); 61 static int __icheckhost __P((u_int32_t, const char *)); 62 static char *__gethostloop __P((u_int32_t)); 63 64 int 65 rcmd(ahost, rport, locuser, remuser, cmd, fd2p) 66 char **ahost; 67 in_port_t rport; 68 const char *locuser, *remuser, *cmd; 69 int *fd2p; 70 { 71 struct hostent *hp; 72 struct sockaddr_in sin, from; 73 fd_set *readsp = NULL; 74 int oldmask; 75 pid_t pid; 76 int s, lport, timo; 77 char c, *p; 78 79 /* call rcmdsh() with specified remote shell if appropriate. */ 80 if (!issetugid() && (p = getenv("RSH"))) { 81 struct servent *sp = getservbyname("shell", "tcp"); 82 83 if (sp && sp->s_port == rport) 84 return (rcmdsh(ahost, rport, locuser, remuser, 85 cmd, p)); 86 } 87 88 /* use rsh(1) if non-root and remote port is shell. */ 89 if (geteuid()) { 90 struct servent *sp = getservbyname("shell", "tcp"); 91 92 if (sp && sp->s_port == rport) 93 return (rcmdsh(ahost, rport, locuser, remuser, 94 cmd, NULL)); 95 } 96 97 pid = getpid(); 98 hp = gethostbyname(*ahost); 99 if (hp == NULL) { 100 herror(*ahost); 101 return (-1); 102 } 103 *ahost = hp->h_name; 104 105 oldmask = sigblock(sigmask(SIGURG)); 106 for (timo = 1, lport = IPPORT_RESERVED - 1;;) { 107 s = rresvport(&lport); 108 if (s < 0) { 109 if (errno == EAGAIN) 110 (void)fprintf(stderr, 111 "rcmd: socket: All ports in use\n"); 112 else 113 (void)fprintf(stderr, "rcmd: socket: %s\n", 114 strerror(errno)); 115 sigsetmask(oldmask); 116 return (-1); 117 } 118 fcntl(s, F_SETOWN, pid); 119 bzero(&sin, sizeof sin); 120 sin.sin_len = sizeof(struct sockaddr_in); 121 sin.sin_family = hp->h_addrtype; 122 sin.sin_port = rport; 123 bcopy(hp->h_addr_list[0], &sin.sin_addr, hp->h_length); 124 if (connect(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0) 125 break; 126 (void)close(s); 127 if (errno == EADDRINUSE) { 128 lport--; 129 continue; 130 } 131 if (errno == ECONNREFUSED && timo <= 16) { 132 (void)sleep(timo); 133 timo *= 2; 134 continue; 135 } 136 if (hp->h_addr_list[1] != NULL) { 137 int oerrno = errno; 138 139 (void)fprintf(stderr, "connect to address %s: ", 140 inet_ntoa(sin.sin_addr)); 141 errno = oerrno; 142 perror(0); 143 hp->h_addr_list++; 144 bcopy(hp->h_addr_list[0], &sin.sin_addr, hp->h_length); 145 (void)fprintf(stderr, "Trying %s...\n", 146 inet_ntoa(sin.sin_addr)); 147 continue; 148 } 149 (void)fprintf(stderr, "%s: %s\n", hp->h_name, strerror(errno)); 150 sigsetmask(oldmask); 151 return (-1); 152 } 153 #if 0 154 /* 155 * try to rresvport() to the same port. This will make rresvport() 156 * fail it's first bind, resulting in it choosing a random port. 157 */ 158 lport--; 159 #endif 160 if (fd2p == 0) { 161 write(s, "", 1); 162 lport = 0; 163 } else { 164 char num[8]; 165 int s2 = rresvport(&lport), s3; 166 int len = sizeof(from); 167 int fdssize = howmany(MAX(s, s2)+1, NFDBITS) * sizeof(fd_mask); 168 169 if (s2 < 0) 170 goto bad; 171 readsp = (fd_set *)malloc(fdssize); 172 if (readsp == NULL) 173 goto bad; 174 listen(s2, 1); 175 (void)snprintf(num, sizeof(num), "%d", lport); 176 if (write(s, num, strlen(num)+1) != strlen(num)+1) { 177 (void)fprintf(stderr, 178 "rcmd: write (setting up stderr): %s\n", 179 strerror(errno)); 180 (void)close(s2); 181 goto bad; 182 } 183 again: 184 bzero(readsp, fdssize); 185 FD_SET(s, readsp); 186 FD_SET(s2, readsp); 187 errno = 0; 188 if (select(MAX(s, s2) + 1, readsp, 0, 0, 0) < 1 || 189 !FD_ISSET(s2, readsp)) { 190 if (errno != 0) 191 (void)fprintf(stderr, 192 "rcmd: select (setting up stderr): %s\n", 193 strerror(errno)); 194 else 195 (void)fprintf(stderr, 196 "select: protocol failure in circuit setup\n"); 197 (void)close(s2); 198 goto bad; 199 } 200 s3 = accept(s2, (struct sockaddr *)&from, &len); 201 /* 202 * XXX careful for ftp bounce attacks. If discovered, shut them 203 * down and check for the real auxiliary channel to connect. 204 */ 205 if (from.sin_family == AF_INET && from.sin_port == htons(20)) { 206 close(s3); 207 goto again; 208 } 209 (void)close(s2); 210 if (s3 < 0) { 211 (void)fprintf(stderr, 212 "rcmd: accept: %s\n", strerror(errno)); 213 lport = 0; 214 goto bad; 215 } 216 *fd2p = s3; 217 from.sin_port = ntohs(from.sin_port); 218 if (from.sin_family != AF_INET || 219 from.sin_port >= IPPORT_RESERVED || 220 from.sin_port < IPPORT_RESERVED / 2) { 221 (void)fprintf(stderr, 222 "socket: protocol failure in circuit setup.\n"); 223 goto bad2; 224 } 225 } 226 (void)write(s, locuser, strlen(locuser)+1); 227 (void)write(s, remuser, strlen(remuser)+1); 228 (void)write(s, cmd, strlen(cmd)+1); 229 if (read(s, &c, 1) != 1) { 230 (void)fprintf(stderr, 231 "rcmd: %s: %s\n", *ahost, strerror(errno)); 232 goto bad2; 233 } 234 if (c != 0) { 235 while (read(s, &c, 1) == 1) { 236 (void)write(STDERR_FILENO, &c, 1); 237 if (c == '\n') 238 break; 239 } 240 goto bad2; 241 } 242 sigsetmask(oldmask); 243 free(readsp); 244 return (s); 245 bad2: 246 if (lport) 247 (void)close(*fd2p); 248 bad: 249 if (readsp) 250 free(readsp); 251 (void)close(s); 252 sigsetmask(oldmask); 253 return (-1); 254 } 255 256 int 257 rresvport(alport) 258 int *alport; 259 { 260 struct sockaddr_in sin; 261 int s; 262 263 bzero(&sin, sizeof sin); 264 sin.sin_len = sizeof(struct sockaddr_in); 265 sin.sin_family = AF_INET; 266 sin.sin_addr.s_addr = INADDR_ANY; 267 s = socket(AF_INET, SOCK_STREAM, 0); 268 if (s < 0) 269 return (-1); 270 sin.sin_port = htons((in_port_t)*alport); 271 if (*alport < IPPORT_RESERVED - 1) { 272 if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0) 273 return (s); 274 if (errno != EADDRINUSE) { 275 (void)close(s); 276 return (-1); 277 } 278 } 279 sin.sin_port = 0; 280 if (bindresvport(s, &sin) == -1) { 281 (void)close(s); 282 return (-1); 283 } 284 *alport = (int)ntohs(sin.sin_port); 285 return (s); 286 } 287 288 int __check_rhosts_file = 1; 289 char *__rcmd_errstr; 290 291 int 292 ruserok(rhost, superuser, ruser, luser) 293 const char *rhost, *ruser, *luser; 294 int superuser; 295 { 296 struct hostent *hp; 297 char **ap; 298 int i; 299 #define MAXADDRS 35 300 u_int32_t addrs[MAXADDRS + 1]; 301 302 if ((hp = gethostbyname(rhost)) == NULL) 303 return (-1); 304 for (i = 0, ap = hp->h_addr_list; *ap && i < MAXADDRS; ++ap, ++i) 305 bcopy(*ap, &addrs[i], sizeof(addrs[i])); 306 addrs[i] = 0; 307 308 for (i = 0; i < MAXADDRS && addrs[i]; i++) 309 if (iruserok((in_addr_t)addrs[i], superuser, ruser, luser) == 0) 310 return (0); 311 return (-1); 312 } 313 314 /* 315 * New .rhosts strategy: We are passed an ip address. We spin through 316 * hosts.equiv and .rhosts looking for a match. When the .rhosts only 317 * has ip addresses, we don't have to trust a nameserver. When it 318 * contains hostnames, we spin through the list of addresses the nameserver 319 * gives us and look for a match. 320 * 321 * Returns 0 if ok, -1 if not ok. 322 */ 323 int 324 iruserok(raddr, superuser, ruser, luser) 325 u_int32_t raddr; 326 int superuser; 327 const char *ruser, *luser; 328 { 329 register char *cp; 330 struct stat sbuf; 331 struct passwd *pwd; 332 FILE *hostf; 333 uid_t uid; 334 int first; 335 char pbuf[MAXPATHLEN]; 336 337 first = 1; 338 hostf = superuser ? NULL : fopen(_PATH_HEQUIV, "r"); 339 again: 340 if (hostf) { 341 if (__ivaliduser(hostf, raddr, luser, ruser) == 0) { 342 (void)fclose(hostf); 343 return (0); 344 } 345 (void)fclose(hostf); 346 } 347 if (first == 1 && (__check_rhosts_file || superuser)) { 348 first = 0; 349 if ((pwd = getpwnam(luser)) == NULL) 350 return (-1); 351 (void)strcpy(pbuf, pwd->pw_dir); 352 (void)strcat(pbuf, "/.rhosts"); 353 354 /* 355 * Change effective uid while opening .rhosts. If root and 356 * reading an NFS mounted file system, can't read files that 357 * are protected read/write owner only. 358 */ 359 uid = geteuid(); 360 (void)seteuid(pwd->pw_uid); 361 hostf = fopen(pbuf, "r"); 362 (void)seteuid(uid); 363 364 if (hostf == NULL) 365 return (-1); 366 /* 367 * If not a regular file, or is owned by someone other than 368 * user or root or if writeable by anyone but the owner, quit. 369 */ 370 cp = NULL; 371 if (lstat(pbuf, &sbuf) < 0) 372 cp = ".rhosts lstat failed"; 373 else if (!S_ISREG(sbuf.st_mode)) 374 cp = ".rhosts not regular file"; 375 else if (fstat(fileno(hostf), &sbuf) < 0) 376 cp = ".rhosts fstat failed"; 377 else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid) 378 cp = "bad .rhosts owner"; 379 else if (sbuf.st_mode & (S_IWGRP|S_IWOTH)) 380 cp = ".rhosts writeable by other than owner"; 381 /* If there were any problems, quit. */ 382 if (cp) { 383 __rcmd_errstr = cp; 384 (void)fclose(hostf); 385 return (-1); 386 } 387 goto again; 388 } 389 return (-1); 390 } 391 392 /* 393 * XXX 394 * Don't make static, used by lpd(8). 395 * 396 * Returns 0 if ok, -1 if not ok. 397 */ 398 int 399 __ivaliduser(hostf, raddrl, luser, ruser) 400 FILE *hostf; 401 in_addr_t raddrl; 402 const char *luser, *ruser; 403 { 404 register char *user, *p; 405 int ch; 406 char buf[MAXHOSTNAMELEN + 128]; /* host + login */ 407 const char *auser, *ahost; 408 int hostok, userok; 409 char *rhost = (char *)-1; 410 char domain[MAXHOSTNAMELEN]; 411 u_int32_t raddr = (u_int32_t)raddrl; 412 413 getdomainname(domain, sizeof(domain)); 414 415 while (fgets(buf, sizeof(buf), hostf)) { 416 p = buf; 417 /* Skip lines that are too long. */ 418 if (strchr(p, '\n') == NULL) { 419 while ((ch = getc(hostf)) != '\n' && ch != EOF) 420 ; 421 continue; 422 } 423 if (*p == '#') 424 continue; 425 while (*p != '\n' && *p != ' ' && *p != '\t' && *p != '\0') { 426 if (!isprint(*p)) 427 goto bail; 428 *p = isupper(*p) ? tolower(*p) : *p; 429 p++; 430 } 431 if (*p == ' ' || *p == '\t') { 432 *p++ = '\0'; 433 while (*p == ' ' || *p == '\t') 434 p++; 435 user = p; 436 while (*p != '\n' && *p != ' ' && 437 *p != '\t' && *p != '\0') 438 p++; 439 } else 440 user = p; 441 *p = '\0'; 442 443 if (p == buf) 444 continue; 445 446 auser = *user ? user : luser; 447 ahost = buf; 448 449 /* 450 * innetgr() must lookup a hostname (we do not attempt 451 * to change the semantics so that netgroups may have 452 * #.#.#.# addresses in the list.) 453 */ 454 if (ahost[0] == '+') 455 switch (ahost[1]) { 456 case '\0': 457 hostok = 1; 458 break; 459 case '@': 460 if (rhost == (char *)-1) 461 rhost = __gethostloop(raddr); 462 hostok = 0; 463 if (rhost) 464 hostok = innetgr(&ahost[2], rhost, 465 NULL, domain); 466 break; 467 default: 468 hostok = __icheckhost(raddr, &ahost[1]); 469 break; 470 } 471 else if (ahost[0] == '-') 472 switch (ahost[1]) { 473 case '\0': 474 hostok = -1; 475 break; 476 case '@': 477 if (rhost == (char *)-1) 478 rhost = __gethostloop(raddr); 479 hostok = 0; 480 if (rhost) 481 hostok = -innetgr(&ahost[2], rhost, 482 NULL, domain); 483 break; 484 default: 485 hostok = -__icheckhost(raddr, &ahost[1]); 486 break; 487 } 488 else 489 hostok = __icheckhost(raddr, ahost); 490 491 492 if (auser[0] == '+') 493 switch (auser[1]) { 494 case '\0': 495 userok = 1; 496 break; 497 case '@': 498 userok = innetgr(&auser[2], NULL, ruser, 499 domain); 500 break; 501 default: 502 userok = strcmp(ruser, &auser[1]) ? 0 : 1; 503 break; 504 } 505 else if (auser[0] == '-') 506 switch (auser[1]) { 507 case '\0': 508 userok = -1; 509 break; 510 case '@': 511 userok = -innetgr(&auser[2], NULL, ruser, 512 domain); 513 break; 514 default: 515 userok = strcmp(ruser, &auser[1]) ? 0 : -1; 516 break; 517 } 518 else 519 userok = strcmp(ruser, auser) ? 0 : 1; 520 521 /* Check if one component did not match */ 522 if (hostok == 0 || userok == 0) 523 continue; 524 525 /* Check if we got a forbidden pair */ 526 if (userok <= -1 || hostok <= -1) 527 return (-1); 528 529 /* Check if we got a valid pair */ 530 if (hostok >= 1 && userok >= 1) 531 return (0); 532 } 533 bail: 534 return (-1); 535 } 536 537 /* 538 * Returns "true" if match, 0 if no match. If we do not find any 539 * semblance of an A->PTR->A loop, allow a simple #.#.#.# match to work. 540 */ 541 static int 542 __icheckhost(raddr, lhost) 543 u_int32_t raddr; 544 const char *lhost; 545 { 546 register struct hostent *hp; 547 register char **pp; 548 struct in_addr in; 549 550 hp = gethostbyname(lhost); 551 if (hp != NULL) { 552 /* Spin through ip addresses. */ 553 for (pp = hp->h_addr_list; *pp; ++pp) 554 if (!bcmp(&raddr, *pp, sizeof(raddr))) 555 return (1); 556 } 557 558 in.s_addr = raddr; 559 if (strcmp(lhost, inet_ntoa(in)) == 0) 560 return (1); 561 return (0); 562 } 563 564 /* 565 * Return the hostname associated with the supplied address. 566 * Do a reverse lookup as well for security. If a loop cannot 567 * be found, pack the result of inet_ntoa() into the string. 568 */ 569 static char * 570 __gethostloop(raddr) 571 u_int32_t raddr; 572 { 573 static char remotehost[MAXHOSTNAMELEN]; 574 struct hostent *hp; 575 struct in_addr in; 576 577 hp = gethostbyaddr((char *) &raddr, sizeof(raddr), AF_INET); 578 if (hp == NULL) 579 return (NULL); 580 581 /* 582 * Look up the name and check that the supplied 583 * address is in the list 584 */ 585 strncpy(remotehost, hp->h_name, sizeof(remotehost) - 1); 586 remotehost[sizeof(remotehost) - 1] = '\0'; 587 hp = gethostbyname(remotehost); 588 if (hp == NULL) 589 return (NULL); 590 591 for (; hp->h_addr_list[0] != NULL; hp->h_addr_list++) 592 if (!bcmp(hp->h_addr_list[0], (caddr_t)&raddr, sizeof(raddr))) 593 return (remotehost); 594 595 /* 596 * either the DNS adminstrator has made a configuration 597 * mistake, or someone has attempted to spoof us 598 */ 599 in.s_addr = raddr; 600 syslog(LOG_NOTICE, "rcmd: address %s not listed for host %s", 601 inet_ntoa(in), hp->h_name); 602 return (NULL); 603 } 604