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 1.17 1996/09/03 10:53:37 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 *, u_long, 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 u_short rport; 67 const char *locuser, *remuser, *cmd; 68 int *fd2p; 69 { 70 struct hostent *hp; 71 struct sockaddr_in sin, from; 72 fd_set reads; 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 ((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); 166 167 if (s2 < 0) 168 goto bad; 169 listen(s2, 1); 170 (void)snprintf(num, sizeof(num), "%d", lport); 171 if (write(s, num, strlen(num)+1) != strlen(num)+1) { 172 (void)fprintf(stderr, 173 "rcmd: write (setting up stderr): %s\n", 174 strerror(errno)); 175 (void)close(s2); 176 goto bad; 177 } 178 again: 179 FD_ZERO(&reads); 180 FD_SET(s, &reads); 181 FD_SET(s2, &reads); 182 errno = 0; 183 if (select(MAX(s, s2) + 1, &reads, 0, 0, 0) < 1 || 184 !FD_ISSET(s2, &reads)) { 185 if (errno != 0) 186 (void)fprintf(stderr, 187 "rcmd: select (setting up stderr): %s\n", 188 strerror(errno)); 189 else 190 (void)fprintf(stderr, 191 "select: protocol failure in circuit setup\n"); 192 (void)close(s2); 193 goto bad; 194 } 195 s3 = accept(s2, (struct sockaddr *)&from, &len); 196 /* 197 * XXX careful for ftp bounce attacks. If discovered, shut them 198 * down and check for the real auxiliary channel to connect. 199 */ 200 if (from.sin_family == AF_INET && from.sin_port == htons(20)) { 201 close(s3); 202 goto again; 203 } 204 (void)close(s2); 205 if (s3 < 0) { 206 (void)fprintf(stderr, 207 "rcmd: accept: %s\n", strerror(errno)); 208 lport = 0; 209 goto bad; 210 } 211 *fd2p = s3; 212 from.sin_port = ntohs(from.sin_port); 213 if (from.sin_family != AF_INET || 214 from.sin_port >= IPPORT_RESERVED || 215 from.sin_port < IPPORT_RESERVED / 2) { 216 (void)fprintf(stderr, 217 "socket: protocol failure in circuit setup.\n"); 218 goto bad2; 219 } 220 } 221 (void)write(s, locuser, strlen(locuser)+1); 222 (void)write(s, remuser, strlen(remuser)+1); 223 (void)write(s, cmd, strlen(cmd)+1); 224 if (read(s, &c, 1) != 1) { 225 (void)fprintf(stderr, 226 "rcmd: %s: %s\n", *ahost, strerror(errno)); 227 goto bad2; 228 } 229 if (c != 0) { 230 while (read(s, &c, 1) == 1) { 231 (void)write(STDERR_FILENO, &c, 1); 232 if (c == '\n') 233 break; 234 } 235 goto bad2; 236 } 237 sigsetmask(oldmask); 238 return (s); 239 bad2: 240 if (lport) 241 (void)close(*fd2p); 242 bad: 243 (void)close(s); 244 sigsetmask(oldmask); 245 return (-1); 246 } 247 248 int 249 rresvport(alport) 250 int *alport; 251 { 252 struct sockaddr_in sin; 253 int s; 254 255 bzero(&sin, sizeof sin); 256 sin.sin_len = sizeof(struct sockaddr_in); 257 sin.sin_family = AF_INET; 258 sin.sin_addr.s_addr = INADDR_ANY; 259 s = socket(AF_INET, SOCK_STREAM, 0); 260 if (s < 0) 261 return (-1); 262 sin.sin_port = htons((u_short)*alport); 263 if (*alport != IPPORT_RESERVED - 1) { 264 if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0) 265 return (s); 266 if (errno != EADDRINUSE) { 267 (void)close(s); 268 return (-1); 269 } 270 } 271 sin.sin_port = 0; 272 if (bindresvport(s, &sin) == -1) { 273 (void)close(s); 274 return (-1); 275 } 276 *alport = (int)ntohs(sin.sin_port); 277 return (s); 278 } 279 280 int __check_rhosts_file = 1; 281 char *__rcmd_errstr; 282 283 int 284 ruserok(rhost, superuser, ruser, luser) 285 const char *rhost, *ruser, *luser; 286 int superuser; 287 { 288 struct hostent *hp; 289 char **ap; 290 int i; 291 #define MAXADDRS 35 292 u_int32_t addrs[MAXADDRS + 1]; 293 294 if ((hp = gethostbyname(rhost)) == NULL) 295 return (-1); 296 for (i = 0, ap = hp->h_addr_list; *ap && i < MAXADDRS; ++ap, ++i) 297 bcopy(*ap, &addrs[i], sizeof(addrs[i])); 298 addrs[i] = 0; 299 300 for (i = 0; i < MAXADDRS && addrs[i]; i++) 301 if (iruserok((u_long)addrs[i], superuser, ruser, luser) == 0) 302 return (0); 303 return (-1); 304 } 305 306 /* 307 * New .rhosts strategy: We are passed an ip address. We spin through 308 * hosts.equiv and .rhosts looking for a match. When the .rhosts only 309 * has ip addresses, we don't have to trust a nameserver. When it 310 * contains hostnames, we spin through the list of addresses the nameserver 311 * gives us and look for a match. 312 * 313 * Returns 0 if ok, -1 if not ok. 314 */ 315 int 316 iruserok(raddr, superuser, ruser, luser) 317 u_int32_t raddr; 318 int superuser; 319 const char *ruser, *luser; 320 { 321 register char *cp; 322 struct stat sbuf; 323 struct passwd *pwd; 324 FILE *hostf; 325 uid_t uid; 326 int first; 327 char pbuf[MAXPATHLEN]; 328 329 first = 1; 330 hostf = superuser ? NULL : fopen(_PATH_HEQUIV, "r"); 331 again: 332 if (hostf) { 333 if (__ivaliduser(hostf, raddr, luser, ruser) == 0) { 334 (void)fclose(hostf); 335 return (0); 336 } 337 (void)fclose(hostf); 338 } 339 if (first == 1 && (__check_rhosts_file || superuser)) { 340 first = 0; 341 if ((pwd = getpwnam(luser)) == NULL) 342 return (-1); 343 (void)strcpy(pbuf, pwd->pw_dir); 344 (void)strcat(pbuf, "/.rhosts"); 345 346 /* 347 * Change effective uid while opening .rhosts. If root and 348 * reading an NFS mounted file system, can't read files that 349 * are protected read/write owner only. 350 */ 351 uid = geteuid(); 352 (void)seteuid(pwd->pw_uid); 353 hostf = fopen(pbuf, "r"); 354 (void)seteuid(uid); 355 356 if (hostf == NULL) 357 return (-1); 358 /* 359 * If not a regular file, or is owned by someone other than 360 * user or root or if writeable by anyone but the owner, quit. 361 */ 362 cp = NULL; 363 if (lstat(pbuf, &sbuf) < 0) 364 cp = ".rhosts lstat failed"; 365 else if (!S_ISREG(sbuf.st_mode)) 366 cp = ".rhosts not regular file"; 367 else if (fstat(fileno(hostf), &sbuf) < 0) 368 cp = ".rhosts fstat failed"; 369 else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid) 370 cp = "bad .rhosts owner"; 371 else if (sbuf.st_mode & (S_IWGRP|S_IWOTH)) 372 cp = ".rhosts writeable by other than owner"; 373 /* If there were any problems, quit. */ 374 if (cp) { 375 __rcmd_errstr = cp; 376 (void)fclose(hostf); 377 return (-1); 378 } 379 goto again; 380 } 381 return (-1); 382 } 383 384 /* 385 * XXX 386 * Don't make static, used by lpd(8). 387 * 388 * Returns 0 if ok, -1 if not ok. 389 */ 390 int 391 __ivaliduser(hostf, raddrl, luser, ruser) 392 FILE *hostf; 393 u_long raddrl; 394 const char *luser, *ruser; 395 { 396 register char *user, *p; 397 int ch; 398 char buf[MAXHOSTNAMELEN + 128]; /* host + login */ 399 const char *auser, *ahost; 400 int hostok, userok; 401 char *rhost = (char *)-1; 402 char domain[MAXHOSTNAMELEN]; 403 u_int32_t raddr = (u_int32_t)raddrl; 404 405 getdomainname(domain, sizeof(domain)); 406 407 while (fgets(buf, sizeof(buf), hostf)) { 408 p = buf; 409 /* Skip lines that are too long. */ 410 if (strchr(p, '\n') == NULL) { 411 while ((ch = getc(hostf)) != '\n' && ch != EOF) 412 ; 413 continue; 414 } 415 if (*p == '#') 416 continue; 417 while (*p != '\n' && *p != ' ' && *p != '\t' && *p != '\0') { 418 *p = isupper(*p) ? tolower(*p) : *p; 419 p++; 420 } 421 if (*p == ' ' || *p == '\t') { 422 *p++ = '\0'; 423 while (*p == ' ' || *p == '\t') 424 p++; 425 user = p; 426 while (*p != '\n' && *p != ' ' && 427 *p != '\t' && *p != '\0') 428 p++; 429 } else 430 user = p; 431 *p = '\0'; 432 433 if (p == buf) 434 continue; 435 436 auser = *user ? user : luser; 437 ahost = buf; 438 439 /* 440 * innetgr() must lookup a hostname (we do not attempt 441 * to change the semantics so that netgroups may have 442 * #.#.#.# addresses in the list.) 443 */ 444 if (ahost[0] == '+') 445 switch (ahost[1]) { 446 case '\0': 447 hostok = 1; 448 break; 449 case '@': 450 if (rhost == (char *)-1) 451 rhost = __gethostloop(raddr); 452 hostok = 0; 453 if (rhost) 454 hostok = innetgr(&ahost[2], rhost, 455 NULL, domain); 456 break; 457 default: 458 hostok = __icheckhost(raddr, &ahost[1]); 459 break; 460 } 461 else if (ahost[0] == '-') 462 switch (ahost[1]) { 463 case '\0': 464 hostok = -1; 465 break; 466 case '@': 467 if (rhost == (char *)-1) 468 rhost = __gethostloop(raddr); 469 hostok = 0; 470 if (rhost) 471 hostok = -innetgr(&ahost[2], rhost, 472 NULL, domain); 473 break; 474 default: 475 hostok = -__icheckhost(raddr, &ahost[1]); 476 break; 477 } 478 else 479 hostok = __icheckhost(raddr, ahost); 480 481 482 if (auser[0] == '+') 483 switch (auser[1]) { 484 case '\0': 485 userok = 1; 486 break; 487 case '@': 488 userok = innetgr(&auser[2], NULL, ruser, 489 domain); 490 break; 491 default: 492 userok = strcmp(ruser, &auser[1]) ? 0 : 1; 493 break; 494 } 495 else if (auser[0] == '-') 496 switch (auser[1]) { 497 case '\0': 498 userok = -1; 499 break; 500 case '@': 501 userok = -innetgr(&auser[2], NULL, ruser, 502 domain); 503 break; 504 default: 505 userok = strcmp(ruser, &auser[1]) ? 0 : -1; 506 break; 507 } 508 else 509 userok = strcmp(ruser, auser) ? 0 : 1; 510 511 /* Check if one component did not match */ 512 if (hostok == 0 || userok == 0) 513 continue; 514 515 /* Check if we got a forbidden pair */ 516 if (userok <= -1 || hostok <= -1) 517 return (-1); 518 519 /* Check if we got a valid pair */ 520 if (hostok >= 1 && userok >= 1) 521 return (0); 522 } 523 return (-1); 524 } 525 526 /* 527 * Returns "true" if match, 0 if no match. If we do not find any 528 * semblance of an A->PTR->A loop, allow a simple #.#.#.# match to work. 529 */ 530 static int 531 __icheckhost(raddr, lhost) 532 u_int32_t raddr; 533 const char *lhost; 534 { 535 register struct hostent *hp; 536 register char **pp; 537 struct in_addr in; 538 539 hp = gethostbyname(lhost); 540 if (hp != NULL) { 541 /* Spin through ip addresses. */ 542 for (pp = hp->h_addr_list; *pp; ++pp) 543 if (!bcmp(&raddr, *pp, sizeof(raddr))) 544 return (1); 545 } 546 547 in.s_addr = raddr; 548 if (strcmp(lhost, inet_ntoa(in)) == 0) 549 return (1); 550 return (0); 551 } 552 553 /* 554 * Return the hostname associated with the supplied address. 555 * Do a reverse lookup as well for security. If a loop cannot 556 * be found, pack the result of inet_ntoa() into the string. 557 */ 558 static char * 559 __gethostloop(raddr) 560 u_int32_t raddr; 561 { 562 static char remotehost[MAXHOSTNAMELEN]; 563 struct hostent *hp; 564 struct in_addr in; 565 566 hp = gethostbyaddr((char *) &raddr, sizeof(raddr), AF_INET); 567 if (hp == NULL) 568 return (NULL); 569 570 /* 571 * Look up the name and check that the supplied 572 * address is in the list 573 */ 574 strncpy(remotehost, hp->h_name, sizeof(remotehost) - 1); 575 remotehost[sizeof(remotehost) - 1] = '\0'; 576 hp = gethostbyname(remotehost); 577 if (hp == NULL) 578 return (NULL); 579 580 for (; hp->h_addr_list[0] != NULL; hp->h_addr_list++) 581 if (!bcmp(hp->h_addr_list[0], (caddr_t)&raddr, sizeof(raddr))) 582 return (remotehost); 583 584 /* 585 * either the DNS adminstrator has made a configuration 586 * mistake, or someone has attempted to spoof us 587 */ 588 in.s_addr = raddr; 589 syslog(LOG_NOTICE, "rcmd: address %s not listed for host %s", 590 inet_ntoa(in), hp->h_name); 591 return (NULL); 592 } 593