1 /* 2 * Copyright (c) 1983, 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 #if defined(LIBC_SCCS) && !defined(lint) 35 static char *rcsid = "$OpenBSD: rcmd.c,v 1.14 1996/08/31 17:56:52 deraadt Exp $"; 36 #endif /* LIBC_SCCS and not lint */ 37 38 #include <sys/param.h> 39 #include <sys/socket.h> 40 #include <sys/stat.h> 41 42 #include <netinet/in.h> 43 #include <arpa/inet.h> 44 45 #include <signal.h> 46 #include <fcntl.h> 47 #include <netdb.h> 48 #include <unistd.h> 49 #include <pwd.h> 50 #include <errno.h> 51 #include <stdio.h> 52 #include <ctype.h> 53 #include <string.h> 54 #include <syslog.h> 55 56 int __ivaliduser __P((FILE *, u_long, const char *, const char *)); 57 static int __icheckhost __P((u_int32_t, const char *)); 58 static char *__gethostloop __P((u_int32_t)); 59 60 int 61 rcmd(ahost, rport, locuser, remuser, cmd, fd2p) 62 char **ahost; 63 u_short rport; 64 const char *locuser, *remuser, *cmd; 65 int *fd2p; 66 { 67 struct hostent *hp; 68 struct sockaddr_in sin, from; 69 fd_set reads; 70 int oldmask; 71 pid_t pid; 72 int s, lport, timo; 73 char c; 74 75 /* use rsh(1) if non-root and remote port is shell. */ 76 if (geteuid()) { 77 struct servent *sp = getservbyname("shell", "tcp"); 78 79 if (sp && sp->s_port == rport) 80 return (rcmdsh(ahost, rport, locuser, remuser, 81 cmd, NULL)); 82 } 83 84 pid = getpid(); 85 hp = gethostbyname(*ahost); 86 if (hp == NULL) { 87 herror(*ahost); 88 return (-1); 89 } 90 *ahost = hp->h_name; 91 92 oldmask = sigblock(sigmask(SIGURG)); 93 for (timo = 1, lport = IPPORT_RESERVED - 1;;) { 94 s = rresvport(&lport); 95 if (s < 0) { 96 if (errno == EAGAIN) 97 (void)fprintf(stderr, 98 "rcmd: socket: All ports in use\n"); 99 else 100 (void)fprintf(stderr, "rcmd: socket: %s\n", 101 strerror(errno)); 102 sigsetmask(oldmask); 103 return (-1); 104 } 105 fcntl(s, F_SETOWN, pid); 106 bzero(&sin, sizeof sin); 107 sin.sin_len = sizeof(struct sockaddr_in); 108 sin.sin_family = hp->h_addrtype; 109 sin.sin_port = rport; 110 bcopy(hp->h_addr_list[0], &sin.sin_addr, hp->h_length); 111 if (connect(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0) 112 break; 113 (void)close(s); 114 if (errno == EADDRINUSE) { 115 lport--; 116 continue; 117 } 118 if (errno == ECONNREFUSED && timo <= 16) { 119 (void)sleep(timo); 120 timo *= 2; 121 continue; 122 } 123 if (hp->h_addr_list[1] != NULL) { 124 int oerrno = errno; 125 126 (void)fprintf(stderr, "connect to address %s: ", 127 inet_ntoa(sin.sin_addr)); 128 errno = oerrno; 129 perror(0); 130 hp->h_addr_list++; 131 bcopy(hp->h_addr_list[0], &sin.sin_addr, hp->h_length); 132 (void)fprintf(stderr, "Trying %s...\n", 133 inet_ntoa(sin.sin_addr)); 134 continue; 135 } 136 (void)fprintf(stderr, "%s: %s\n", hp->h_name, strerror(errno)); 137 sigsetmask(oldmask); 138 return (-1); 139 } 140 #if 0 141 /* 142 * try to rresvport() to the same port. This will make rresvport() 143 * fail it's first bind, resulting in it choosing a random port. 144 */ 145 lport--; 146 #endif 147 if (fd2p == 0) { 148 write(s, "", 1); 149 lport = 0; 150 } else { 151 char num[8]; 152 int s2 = rresvport(&lport), s3; 153 int len = sizeof(from); 154 155 if (s2 < 0) 156 goto bad; 157 listen(s2, 1); 158 (void)snprintf(num, sizeof(num), "%d", lport); 159 if (write(s, num, strlen(num)+1) != strlen(num)+1) { 160 (void)fprintf(stderr, 161 "rcmd: write (setting up stderr): %s\n", 162 strerror(errno)); 163 (void)close(s2); 164 goto bad; 165 } 166 again: 167 FD_ZERO(&reads); 168 FD_SET(s, &reads); 169 FD_SET(s2, &reads); 170 errno = 0; 171 if (select(MAX(s, s2) + 1, &reads, 0, 0, 0) < 1 || 172 !FD_ISSET(s2, &reads)) { 173 if (errno != 0) 174 (void)fprintf(stderr, 175 "rcmd: select (setting up stderr): %s\n", 176 strerror(errno)); 177 else 178 (void)fprintf(stderr, 179 "select: protocol failure in circuit setup\n"); 180 (void)close(s2); 181 goto bad; 182 } 183 s3 = accept(s2, (struct sockaddr *)&from, &len); 184 /* 185 * XXX careful for ftp bounce attacks. If discovered, shut them 186 * down and check for the real auxiliary channel to connect. 187 */ 188 if (from.sin_family == AF_INET && from.sin_port == htons(20)) { 189 close(s3); 190 goto again; 191 } 192 (void)close(s2); 193 if (s3 < 0) { 194 (void)fprintf(stderr, 195 "rcmd: accept: %s\n", strerror(errno)); 196 lport = 0; 197 goto bad; 198 } 199 *fd2p = s3; 200 from.sin_port = ntohs(from.sin_port); 201 if (from.sin_family != AF_INET || 202 from.sin_port >= IPPORT_RESERVED || 203 from.sin_port < IPPORT_RESERVED / 2) { 204 (void)fprintf(stderr, 205 "socket: protocol failure in circuit setup.\n"); 206 goto bad2; 207 } 208 } 209 (void)write(s, locuser, strlen(locuser)+1); 210 (void)write(s, remuser, strlen(remuser)+1); 211 (void)write(s, cmd, strlen(cmd)+1); 212 if (read(s, &c, 1) != 1) { 213 (void)fprintf(stderr, 214 "rcmd: %s: %s\n", *ahost, strerror(errno)); 215 goto bad2; 216 } 217 if (c != 0) { 218 while (read(s, &c, 1) == 1) { 219 (void)write(STDERR_FILENO, &c, 1); 220 if (c == '\n') 221 break; 222 } 223 goto bad2; 224 } 225 sigsetmask(oldmask); 226 return (s); 227 bad2: 228 if (lport) 229 (void)close(*fd2p); 230 bad: 231 (void)close(s); 232 sigsetmask(oldmask); 233 return (-1); 234 } 235 236 int 237 rresvport(alport) 238 int *alport; 239 { 240 struct sockaddr_in sin; 241 int s; 242 243 bzero(&sin, sizeof sin); 244 sin.sin_len = sizeof(struct sockaddr_in); 245 sin.sin_family = AF_INET; 246 sin.sin_addr.s_addr = INADDR_ANY; 247 s = socket(AF_INET, SOCK_STREAM, 0); 248 if (s < 0) 249 return (-1); 250 sin.sin_port = htons((u_short)*alport); 251 if (*alport != IPPORT_RESERVED - 1) { 252 if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0) 253 return (s); 254 if (errno != EADDRINUSE) { 255 (void)close(s); 256 return (-1); 257 } 258 } 259 sin.sin_port = 0; 260 if (bindresvport(s, &sin) == -1) { 261 (void)close(s); 262 return (-1); 263 } 264 *alport = (int)ntohs(sin.sin_port); 265 return (s); 266 } 267 268 int __check_rhosts_file = 1; 269 char *__rcmd_errstr; 270 271 int 272 ruserok(rhost, superuser, ruser, luser) 273 const char *rhost, *ruser, *luser; 274 int superuser; 275 { 276 struct hostent *hp; 277 char **ap; 278 int i; 279 #define MAXADDRS 35 280 u_int32_t addrs[MAXADDRS + 1]; 281 282 if ((hp = gethostbyname(rhost)) == NULL) 283 return (-1); 284 for (i = 0, ap = hp->h_addr_list; *ap && i < MAXADDRS; ++ap, ++i) 285 bcopy(*ap, &addrs[i], sizeof(addrs[i])); 286 addrs[i] = 0; 287 288 for (i = 0; i < MAXADDRS && addrs[i]; i++) 289 if (iruserok((u_long)addrs[i], superuser, ruser, luser) == 0) 290 return (0); 291 return (-1); 292 } 293 294 /* 295 * New .rhosts strategy: We are passed an ip address. We spin through 296 * hosts.equiv and .rhosts looking for a match. When the .rhosts only 297 * has ip addresses, we don't have to trust a nameserver. When it 298 * contains hostnames, we spin through the list of addresses the nameserver 299 * gives us and look for a match. 300 * 301 * Returns 0 if ok, -1 if not ok. 302 */ 303 int 304 iruserok(raddr, superuser, ruser, luser) 305 u_int32_t raddr; 306 int superuser; 307 const char *ruser, *luser; 308 { 309 register char *cp; 310 struct stat sbuf; 311 struct passwd *pwd; 312 FILE *hostf; 313 uid_t uid; 314 int first; 315 char pbuf[MAXPATHLEN]; 316 317 first = 1; 318 hostf = superuser ? NULL : fopen(_PATH_HEQUIV, "r"); 319 again: 320 if (hostf) { 321 if (__ivaliduser(hostf, raddr, luser, ruser) == 0) { 322 (void)fclose(hostf); 323 return (0); 324 } 325 (void)fclose(hostf); 326 } 327 if (first == 1 && (__check_rhosts_file || superuser)) { 328 first = 0; 329 if ((pwd = getpwnam(luser)) == NULL) 330 return (-1); 331 (void)strcpy(pbuf, pwd->pw_dir); 332 (void)strcat(pbuf, "/.rhosts"); 333 334 /* 335 * Change effective uid while opening .rhosts. If root and 336 * reading an NFS mounted file system, can't read files that 337 * are protected read/write owner only. 338 */ 339 uid = geteuid(); 340 (void)seteuid(pwd->pw_uid); 341 hostf = fopen(pbuf, "r"); 342 (void)seteuid(uid); 343 344 if (hostf == NULL) 345 return (-1); 346 /* 347 * If not a regular file, or is owned by someone other than 348 * user or root or if writeable by anyone but the owner, quit. 349 */ 350 cp = NULL; 351 if (lstat(pbuf, &sbuf) < 0) 352 cp = ".rhosts lstat failed"; 353 else if (!S_ISREG(sbuf.st_mode)) 354 cp = ".rhosts not regular file"; 355 else if (fstat(fileno(hostf), &sbuf) < 0) 356 cp = ".rhosts fstat failed"; 357 else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid) 358 cp = "bad .rhosts owner"; 359 else if (sbuf.st_mode & (S_IWGRP|S_IWOTH)) 360 cp = ".rhosts writeable by other than owner"; 361 /* If there were any problems, quit. */ 362 if (cp) { 363 __rcmd_errstr = cp; 364 (void)fclose(hostf); 365 return (-1); 366 } 367 goto again; 368 } 369 return (-1); 370 } 371 372 /* 373 * XXX 374 * Don't make static, used by lpd(8). 375 * 376 * Returns 0 if ok, -1 if not ok. 377 */ 378 int 379 __ivaliduser(hostf, raddrl, luser, ruser) 380 FILE *hostf; 381 u_long raddrl; 382 const char *luser, *ruser; 383 { 384 register char *user, *p; 385 int ch; 386 char buf[MAXHOSTNAMELEN + 128]; /* host + login */ 387 const char *auser, *ahost; 388 int hostok, userok; 389 char *rhost = (char *)-1; 390 char domain[MAXHOSTNAMELEN]; 391 u_int32_t raddr = (u_int32_t)raddrl; 392 393 getdomainname(domain, sizeof(domain)); 394 395 while (fgets(buf, sizeof(buf), hostf)) { 396 p = buf; 397 /* Skip lines that are too long. */ 398 if (strchr(p, '\n') == NULL) { 399 while ((ch = getc(hostf)) != '\n' && ch != EOF) 400 ; 401 continue; 402 } 403 if (*p == '#') 404 continue; 405 while (*p != '\n' && *p != ' ' && *p != '\t' && *p != '\0') { 406 *p = isupper(*p) ? tolower(*p) : *p; 407 p++; 408 } 409 if (*p == ' ' || *p == '\t') { 410 *p++ = '\0'; 411 while (*p == ' ' || *p == '\t') 412 p++; 413 user = p; 414 while (*p != '\n' && *p != ' ' && 415 *p != '\t' && *p != '\0') 416 p++; 417 } else 418 user = p; 419 *p = '\0'; 420 421 if (p == buf) 422 continue; 423 424 auser = *user ? user : luser; 425 ahost = buf; 426 427 /* 428 * innetgr() must lookup a hostname (we do not attempt 429 * to change the semantics so that netgroups may have 430 * #.#.#.# addresses in the list.) 431 */ 432 if (ahost[0] == '+') 433 switch (ahost[1]) { 434 case '\0': 435 hostok = 1; 436 break; 437 case '@': 438 if (rhost == (char *)-1) 439 rhost = __gethostloop(raddr); 440 hostok = 0; 441 if (rhost) 442 hostok = innetgr(&ahost[2], rhost, 443 NULL, domain); 444 break; 445 default: 446 hostok = __icheckhost(raddr, &ahost[1]); 447 break; 448 } 449 else if (ahost[0] == '-') 450 switch (ahost[1]) { 451 case '\0': 452 hostok = -1; 453 break; 454 case '@': 455 if (rhost == (char *)-1) 456 rhost = __gethostloop(raddr); 457 hostok = 0; 458 if (rhost) 459 hostok = -innetgr(&ahost[2], rhost, 460 NULL, domain); 461 break; 462 default: 463 hostok = -__icheckhost(raddr, &ahost[1]); 464 break; 465 } 466 else 467 hostok = __icheckhost(raddr, ahost); 468 469 470 if (auser[0] == '+') 471 switch (auser[1]) { 472 case '\0': 473 userok = 1; 474 break; 475 case '@': 476 userok = innetgr(&auser[2], NULL, ruser, 477 domain); 478 break; 479 default: 480 userok = strcmp(ruser, &auser[1]) ? 0 : 1; 481 break; 482 } 483 else if (auser[0] == '-') 484 switch (auser[1]) { 485 case '\0': 486 userok = -1; 487 break; 488 case '@': 489 userok = -innetgr(&auser[2], NULL, ruser, 490 domain); 491 break; 492 default: 493 userok = strcmp(ruser, &auser[1]) ? 0 : -1; 494 break; 495 } 496 else 497 userok = strcmp(ruser, auser) ? 0 : 1; 498 499 /* Check if one component did not match */ 500 if (hostok == 0 || userok == 0) 501 continue; 502 503 /* Check if we got a forbidden pair */ 504 if (userok <= -1 || hostok <= -1) 505 return (-1); 506 507 /* Check if we got a valid pair */ 508 if (hostok >= 1 && userok >= 1) 509 return (0); 510 } 511 return (-1); 512 } 513 514 /* 515 * Returns "true" if match, 0 if no match. If we do not find any 516 * semblance of an A->PTR->A loop, allow a simple #.#.#.# match to work. 517 */ 518 static int 519 __icheckhost(raddr, lhost) 520 u_int32_t raddr; 521 const char *lhost; 522 { 523 register struct hostent *hp; 524 register char **pp; 525 struct in_addr in; 526 527 hp = gethostbyname(lhost); 528 if (hp != NULL) { 529 /* Spin through ip addresses. */ 530 for (pp = hp->h_addr_list; *pp; ++pp) 531 if (!bcmp(&raddr, *pp, sizeof(raddr))) 532 return (1); 533 } 534 535 in.s_addr = raddr; 536 if (strcmp(lhost, inet_ntoa(in)) == 0) 537 return (1); 538 return (0); 539 } 540 541 /* 542 * Return the hostname associated with the supplied address. 543 * Do a reverse lookup as well for security. If a loop cannot 544 * be found, pack the result of inet_ntoa() into the string. 545 */ 546 static char * 547 __gethostloop(raddr) 548 u_int32_t raddr; 549 { 550 static char remotehost[MAXHOSTNAMELEN]; 551 struct hostent *hp; 552 struct in_addr in; 553 554 hp = gethostbyaddr((char *) &raddr, sizeof(raddr), AF_INET); 555 if (hp == NULL) 556 return (NULL); 557 558 /* 559 * Look up the name and check that the supplied 560 * address is in the list 561 */ 562 strncpy(remotehost, hp->h_name, sizeof(remotehost) - 1); 563 remotehost[sizeof(remotehost) - 1] = '\0'; 564 hp = gethostbyname(remotehost); 565 if (hp == NULL) 566 return (NULL); 567 568 for (; hp->h_addr_list[0] != NULL; hp->h_addr_list++) 569 if (!bcmp(hp->h_addr_list[0], (caddr_t)&raddr, sizeof(raddr))) 570 return (remotehost); 571 572 /* 573 * either the DNS adminstrator has made a configuration 574 * mistake, or someone has attempted to spoof us 575 */ 576 in.s_addr = raddr; 577 syslog(LOG_NOTICE, "rcmd: address %s not listed for host %s", 578 inet_ntoa(in), hp->h_name); 579 return (NULL); 580 } 581