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 1.25 1997/07/06 07:55:58 deraadt 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 59 int __ivaliduser __P((FILE *, in_addr_t, const char *, const char *)); 60 static int __icheckhost __P((u_int32_t, const char *)); 61 static char *__gethostloop __P((u_int32_t)); 62 63 int 64 rcmd(ahost, rport, locuser, remuser, cmd, fd2p) 65 char **ahost; 66 in_port_t rport; 67 const char *locuser, *remuser, *cmd; 68 int *fd2p; 69 { 70 struct hostent *hp; 71 struct sockaddr_in sin, from; 72 fd_set *readsp = NULL; 73 int oldmask; 74 pid_t pid; 75 int s, lport, timo; 76 char c, *p; 77 78 /* call rcmdsh() with specified remote shell if appropriate. */ 79 if (!issetugid() && (p = getenv("RSH"))) { 80 struct servent *sp = getservbyname("shell", "tcp"); 81 82 if (sp && sp->s_port == rport) 83 return (rcmdsh(ahost, rport, locuser, remuser, 84 cmd, p)); 85 } 86 87 /* use rsh(1) if non-root and remote port is shell. */ 88 if (geteuid()) { 89 struct servent *sp = getservbyname("shell", "tcp"); 90 91 if (sp && sp->s_port == rport) 92 return (rcmdsh(ahost, rport, locuser, remuser, 93 cmd, NULL)); 94 } 95 96 pid = getpid(); 97 hp = gethostbyname(*ahost); 98 if (hp == NULL) { 99 herror(*ahost); 100 return (-1); 101 } 102 *ahost = hp->h_name; 103 104 oldmask = sigblock(sigmask(SIGURG)); 105 for (timo = 1, lport = IPPORT_RESERVED - 1;;) { 106 s = rresvport(&lport); 107 if (s < 0) { 108 if (errno == EAGAIN) 109 (void)fprintf(stderr, 110 "rcmd: socket: All ports in use\n"); 111 else 112 (void)fprintf(stderr, "rcmd: socket: %s\n", 113 strerror(errno)); 114 sigsetmask(oldmask); 115 return (-1); 116 } 117 fcntl(s, F_SETOWN, pid); 118 bzero(&sin, sizeof sin); 119 sin.sin_len = sizeof(struct sockaddr_in); 120 sin.sin_family = hp->h_addrtype; 121 sin.sin_port = rport; 122 bcopy(hp->h_addr_list[0], &sin.sin_addr, hp->h_length); 123 if (connect(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0) 124 break; 125 (void)close(s); 126 if (errno == EADDRINUSE) { 127 lport--; 128 continue; 129 } 130 if (errno == ECONNREFUSED && timo <= 16) { 131 (void)sleep(timo); 132 timo *= 2; 133 continue; 134 } 135 if (hp->h_addr_list[1] != NULL) { 136 int oerrno = errno; 137 138 (void)fprintf(stderr, "connect to address %s: ", 139 inet_ntoa(sin.sin_addr)); 140 errno = oerrno; 141 perror(0); 142 hp->h_addr_list++; 143 bcopy(hp->h_addr_list[0], &sin.sin_addr, hp->h_length); 144 (void)fprintf(stderr, "Trying %s...\n", 145 inet_ntoa(sin.sin_addr)); 146 continue; 147 } 148 (void)fprintf(stderr, "%s: %s\n", hp->h_name, strerror(errno)); 149 sigsetmask(oldmask); 150 return (-1); 151 } 152 #if 0 153 /* 154 * try to rresvport() to the same port. This will make rresvport() 155 * fail it's first bind, resulting in it choosing a random port. 156 */ 157 lport--; 158 #endif 159 if (fd2p == 0) { 160 write(s, "", 1); 161 lport = 0; 162 } else { 163 char num[8]; 164 int s2 = rresvport(&lport), s3; 165 int len = sizeof(from); 166 int fdssize = howmany(MAX(s, s2)+1, NFDBITS) * sizeof(fd_mask); 167 168 if (s2 < 0) 169 goto bad; 170 readsp = (fd_set *)malloc(fdssize); 171 if (readsp == NULL) 172 goto bad; 173 listen(s2, 1); 174 (void)snprintf(num, sizeof(num), "%d", lport); 175 if (write(s, num, strlen(num)+1) != strlen(num)+1) { 176 (void)fprintf(stderr, 177 "rcmd: write (setting up stderr): %s\n", 178 strerror(errno)); 179 (void)close(s2); 180 goto bad; 181 } 182 again: 183 bzero(readsp, fdssize); 184 FD_SET(s, readsp); 185 FD_SET(s2, readsp); 186 errno = 0; 187 if (select(MAX(s, s2) + 1, readsp, 0, 0, 0) < 1 || 188 !FD_ISSET(s2, readsp)) { 189 if (errno != 0) 190 (void)fprintf(stderr, 191 "rcmd: select (setting up stderr): %s\n", 192 strerror(errno)); 193 else 194 (void)fprintf(stderr, 195 "select: protocol failure in circuit setup\n"); 196 (void)close(s2); 197 goto bad; 198 } 199 s3 = accept(s2, (struct sockaddr *)&from, &len); 200 /* 201 * XXX careful for ftp bounce attacks. If discovered, shut them 202 * down and check for the real auxiliary channel to connect. 203 */ 204 if (from.sin_family == AF_INET && from.sin_port == htons(20)) { 205 close(s3); 206 goto again; 207 } 208 (void)close(s2); 209 if (s3 < 0) { 210 (void)fprintf(stderr, 211 "rcmd: accept: %s\n", strerror(errno)); 212 lport = 0; 213 goto bad; 214 } 215 *fd2p = s3; 216 from.sin_port = ntohs(from.sin_port); 217 if (from.sin_family != AF_INET || 218 from.sin_port >= IPPORT_RESERVED || 219 from.sin_port < IPPORT_RESERVED / 2) { 220 (void)fprintf(stderr, 221 "socket: protocol failure in circuit setup.\n"); 222 goto bad2; 223 } 224 } 225 (void)write(s, locuser, strlen(locuser)+1); 226 (void)write(s, remuser, strlen(remuser)+1); 227 (void)write(s, cmd, strlen(cmd)+1); 228 if (read(s, &c, 1) != 1) { 229 (void)fprintf(stderr, 230 "rcmd: %s: %s\n", *ahost, strerror(errno)); 231 goto bad2; 232 } 233 if (c != 0) { 234 while (read(s, &c, 1) == 1) { 235 (void)write(STDERR_FILENO, &c, 1); 236 if (c == '\n') 237 break; 238 } 239 goto bad2; 240 } 241 sigsetmask(oldmask); 242 free(readsp); 243 return (s); 244 bad2: 245 if (lport) 246 (void)close(*fd2p); 247 bad: 248 if (readsp) 249 free(readsp); 250 (void)close(s); 251 sigsetmask(oldmask); 252 return (-1); 253 } 254 255 int 256 rresvport(alport) 257 int *alport; 258 { 259 struct sockaddr_in sin; 260 int s; 261 262 bzero(&sin, sizeof sin); 263 sin.sin_len = sizeof(struct sockaddr_in); 264 sin.sin_family = AF_INET; 265 sin.sin_addr.s_addr = INADDR_ANY; 266 s = socket(AF_INET, SOCK_STREAM, 0); 267 if (s < 0) 268 return (-1); 269 sin.sin_port = htons((in_port_t)*alport); 270 if (*alport < IPPORT_RESERVED - 1) { 271 if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0) 272 return (s); 273 if (errno != EADDRINUSE) { 274 (void)close(s); 275 return (-1); 276 } 277 } 278 sin.sin_port = 0; 279 if (bindresvport(s, &sin) == -1) { 280 (void)close(s); 281 return (-1); 282 } 283 *alport = (int)ntohs(sin.sin_port); 284 return (s); 285 } 286 287 int __check_rhosts_file = 1; 288 char *__rcmd_errstr; 289 290 int 291 ruserok(rhost, superuser, ruser, luser) 292 const char *rhost, *ruser, *luser; 293 int superuser; 294 { 295 struct hostent *hp; 296 char **ap; 297 int i; 298 #define MAXADDRS 35 299 u_int32_t addrs[MAXADDRS + 1]; 300 301 if ((hp = gethostbyname(rhost)) == NULL) 302 return (-1); 303 for (i = 0, ap = hp->h_addr_list; *ap && i < MAXADDRS; ++ap, ++i) 304 bcopy(*ap, &addrs[i], sizeof(addrs[i])); 305 addrs[i] = 0; 306 307 for (i = 0; i < MAXADDRS && addrs[i]; i++) 308 if (iruserok((in_addr_t)addrs[i], superuser, ruser, luser) == 0) 309 return (0); 310 return (-1); 311 } 312 313 /* 314 * New .rhosts strategy: We are passed an ip address. We spin through 315 * hosts.equiv and .rhosts looking for a match. When the .rhosts only 316 * has ip addresses, we don't have to trust a nameserver. When it 317 * contains hostnames, we spin through the list of addresses the nameserver 318 * gives us and look for a match. 319 * 320 * Returns 0 if ok, -1 if not ok. 321 */ 322 int 323 iruserok(raddr, superuser, ruser, luser) 324 u_int32_t raddr; 325 int superuser; 326 const char *ruser, *luser; 327 { 328 register char *cp; 329 struct stat sbuf; 330 struct passwd *pwd; 331 FILE *hostf; 332 uid_t uid; 333 int first; 334 char pbuf[MAXPATHLEN]; 335 336 first = 1; 337 hostf = superuser ? NULL : fopen(_PATH_HEQUIV, "r"); 338 again: 339 if (hostf) { 340 if (__ivaliduser(hostf, raddr, luser, ruser) == 0) { 341 (void)fclose(hostf); 342 return (0); 343 } 344 (void)fclose(hostf); 345 } 346 if (first == 1 && (__check_rhosts_file || superuser)) { 347 first = 0; 348 if ((pwd = getpwnam(luser)) == NULL) 349 return (-1); 350 (void)strcpy(pbuf, pwd->pw_dir); 351 (void)strcat(pbuf, "/.rhosts"); 352 353 /* 354 * Change effective uid while opening .rhosts. If root and 355 * reading an NFS mounted file system, can't read files that 356 * are protected read/write owner only. 357 */ 358 uid = geteuid(); 359 (void)seteuid(pwd->pw_uid); 360 hostf = fopen(pbuf, "r"); 361 (void)seteuid(uid); 362 363 if (hostf == NULL) 364 return (-1); 365 /* 366 * If not a regular file, or is owned by someone other than 367 * user or root or if writeable by anyone but the owner, quit. 368 */ 369 cp = NULL; 370 if (lstat(pbuf, &sbuf) < 0) 371 cp = ".rhosts lstat failed"; 372 else if (!S_ISREG(sbuf.st_mode)) 373 cp = ".rhosts not regular file"; 374 else if (fstat(fileno(hostf), &sbuf) < 0) 375 cp = ".rhosts fstat failed"; 376 else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid) 377 cp = "bad .rhosts owner"; 378 else if (sbuf.st_mode & (S_IWGRP|S_IWOTH)) 379 cp = ".rhosts writeable by other than owner"; 380 /* If there were any problems, quit. */ 381 if (cp) { 382 __rcmd_errstr = cp; 383 (void)fclose(hostf); 384 return (-1); 385 } 386 goto again; 387 } 388 return (-1); 389 } 390 391 /* 392 * XXX 393 * Don't make static, used by lpd(8). 394 * 395 * Returns 0 if ok, -1 if not ok. 396 */ 397 int 398 __ivaliduser(hostf, raddrl, luser, ruser) 399 FILE *hostf; 400 in_addr_t raddrl; 401 const char *luser, *ruser; 402 { 403 register char *user, *p; 404 int ch; 405 char buf[MAXHOSTNAMELEN + 128]; /* host + login */ 406 const char *auser, *ahost; 407 int hostok, userok; 408 char *rhost = (char *)-1; 409 char domain[MAXHOSTNAMELEN]; 410 u_int32_t raddr = (u_int32_t)raddrl; 411 412 getdomainname(domain, sizeof(domain)); 413 414 while (fgets(buf, sizeof(buf), hostf)) { 415 p = buf; 416 /* Skip lines that are too long. */ 417 if (strchr(p, '\n') == NULL) { 418 while ((ch = getc(hostf)) != '\n' && ch != EOF) 419 ; 420 continue; 421 } 422 if (*p == '#') 423 continue; 424 while (*p != '\n' && *p != ' ' && *p != '\t' && *p != '\0') { 425 if (!isprint(*p)) 426 goto bail; 427 *p = isupper(*p) ? tolower(*p) : *p; 428 p++; 429 } 430 if (*p == ' ' || *p == '\t') { 431 *p++ = '\0'; 432 while (*p == ' ' || *p == '\t') 433 p++; 434 user = p; 435 while (*p != '\n' && *p != ' ' && 436 *p != '\t' && *p != '\0') 437 p++; 438 } else 439 user = p; 440 *p = '\0'; 441 442 if (p == buf) 443 continue; 444 445 auser = *user ? user : luser; 446 ahost = buf; 447 448 /* 449 * innetgr() must lookup a hostname (we do not attempt 450 * to change the semantics so that netgroups may have 451 * #.#.#.# addresses in the list.) 452 */ 453 if (ahost[0] == '+') 454 switch (ahost[1]) { 455 case '\0': 456 hostok = 1; 457 break; 458 case '@': 459 if (rhost == (char *)-1) 460 rhost = __gethostloop(raddr); 461 hostok = 0; 462 if (rhost) 463 hostok = innetgr(&ahost[2], rhost, 464 NULL, domain); 465 break; 466 default: 467 hostok = __icheckhost(raddr, &ahost[1]); 468 break; 469 } 470 else if (ahost[0] == '-') 471 switch (ahost[1]) { 472 case '\0': 473 hostok = -1; 474 break; 475 case '@': 476 if (rhost == (char *)-1) 477 rhost = __gethostloop(raddr); 478 hostok = 0; 479 if (rhost) 480 hostok = -innetgr(&ahost[2], rhost, 481 NULL, domain); 482 break; 483 default: 484 hostok = -__icheckhost(raddr, &ahost[1]); 485 break; 486 } 487 else 488 hostok = __icheckhost(raddr, ahost); 489 490 491 if (auser[0] == '+') 492 switch (auser[1]) { 493 case '\0': 494 userok = 1; 495 break; 496 case '@': 497 userok = innetgr(&auser[2], NULL, ruser, 498 domain); 499 break; 500 default: 501 userok = strcmp(ruser, &auser[1]) ? 0 : 1; 502 break; 503 } 504 else if (auser[0] == '-') 505 switch (auser[1]) { 506 case '\0': 507 userok = -1; 508 break; 509 case '@': 510 userok = -innetgr(&auser[2], NULL, ruser, 511 domain); 512 break; 513 default: 514 userok = strcmp(ruser, &auser[1]) ? 0 : -1; 515 break; 516 } 517 else 518 userok = strcmp(ruser, auser) ? 0 : 1; 519 520 /* Check if one component did not match */ 521 if (hostok == 0 || userok == 0) 522 continue; 523 524 /* Check if we got a forbidden pair */ 525 if (userok <= -1 || hostok <= -1) 526 return (-1); 527 528 /* Check if we got a valid pair */ 529 if (hostok >= 1 && userok >= 1) 530 return (0); 531 } 532 bail: 533 return (-1); 534 } 535 536 /* 537 * Returns "true" if match, 0 if no match. If we do not find any 538 * semblance of an A->PTR->A loop, allow a simple #.#.#.# match to work. 539 */ 540 static int 541 __icheckhost(raddr, lhost) 542 u_int32_t raddr; 543 const char *lhost; 544 { 545 register struct hostent *hp; 546 register char **pp; 547 struct in_addr in; 548 549 hp = gethostbyname(lhost); 550 if (hp != NULL) { 551 /* Spin through ip addresses. */ 552 for (pp = hp->h_addr_list; *pp; ++pp) 553 if (!bcmp(&raddr, *pp, sizeof(raddr))) 554 return (1); 555 } 556 557 in.s_addr = raddr; 558 if (strcmp(lhost, inet_ntoa(in)) == 0) 559 return (1); 560 return (0); 561 } 562 563 /* 564 * Return the hostname associated with the supplied address. 565 * Do a reverse lookup as well for security. If a loop cannot 566 * be found, pack the result of inet_ntoa() into the string. 567 */ 568 static char * 569 __gethostloop(raddr) 570 u_int32_t raddr; 571 { 572 static char remotehost[MAXHOSTNAMELEN]; 573 struct hostent *hp; 574 struct in_addr in; 575 576 hp = gethostbyaddr((char *) &raddr, sizeof(raddr), AF_INET); 577 if (hp == NULL) 578 return (NULL); 579 580 /* 581 * Look up the name and check that the supplied 582 * address is in the list 583 */ 584 strncpy(remotehost, hp->h_name, sizeof(remotehost) - 1); 585 remotehost[sizeof(remotehost) - 1] = '\0'; 586 hp = gethostbyname(remotehost); 587 if (hp == NULL) 588 return (NULL); 589 590 for (; hp->h_addr_list[0] != NULL; hp->h_addr_list++) 591 if (!bcmp(hp->h_addr_list[0], (caddr_t)&raddr, sizeof(raddr))) 592 return (remotehost); 593 594 /* 595 * either the DNS adminstrator has made a configuration 596 * mistake, or someone has attempted to spoof us 597 */ 598 in.s_addr = raddr; 599 syslog(LOG_NOTICE, "rcmd: address %s not listed for host %s", 600 inet_ntoa(in), hp->h_name); 601 return (NULL); 602 } 603