1 /* $NetBSD: rcmd.c,v 1.12 1995/06/03 22:33:34 mycroft Exp $ */ 2 3 /* 4 * Copyright (c) 1983, 1993, 1994 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 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 #if 0 38 static char sccsid[] = "@(#)rcmd.c 8.3 (Berkeley) 3/26/94"; 39 #else 40 static char *rcsid = "$NetBSD: rcmd.c,v 1.12 1995/06/03 22:33:34 mycroft Exp $"; 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include <sys/param.h> 45 #include <sys/socket.h> 46 #include <sys/stat.h> 47 48 #include <netinet/in.h> 49 #include <arpa/inet.h> 50 51 #include <signal.h> 52 #include <fcntl.h> 53 #include <netdb.h> 54 #include <unistd.h> 55 #include <pwd.h> 56 #include <errno.h> 57 #include <stdio.h> 58 #include <ctype.h> 59 #include <string.h> 60 #include <syslog.h> 61 62 int __ivaliduser __P((FILE *, u_long, const char *, const char *)); 63 static int __icheckhost __P((u_int32_t, const char *)); 64 static char *__gethostloop __P((u_int32_t)); 65 66 int 67 rcmd(ahost, rport, locuser, remuser, cmd, fd2p) 68 char **ahost; 69 u_short rport; 70 const char *locuser, *remuser, *cmd; 71 int *fd2p; 72 { 73 struct hostent *hp; 74 struct sockaddr_in sin, from; 75 fd_set reads; 76 int oldmask; 77 pid_t pid; 78 int s, lport, timo; 79 char c; 80 81 pid = getpid(); 82 hp = gethostbyname(*ahost); 83 if (hp == NULL) { 84 herror(*ahost); 85 return (-1); 86 } 87 *ahost = hp->h_name; 88 oldmask = sigblock(sigmask(SIGURG)); 89 for (timo = 1, lport = IPPORT_RESERVED - 1;;) { 90 s = rresvport(&lport); 91 if (s < 0) { 92 if (errno == EAGAIN) 93 (void)fprintf(stderr, 94 "rcmd: socket: All ports in use\n"); 95 else 96 (void)fprintf(stderr, "rcmd: socket: %s\n", 97 strerror(errno)); 98 sigsetmask(oldmask); 99 return (-1); 100 } 101 fcntl(s, F_SETOWN, pid); 102 bzero(&sin, sizeof sin); 103 sin.sin_len = sizeof(struct sockaddr_in); 104 sin.sin_family = hp->h_addrtype; 105 sin.sin_port = rport; 106 bcopy(hp->h_addr_list[0], &sin.sin_addr, hp->h_length); 107 if (connect(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0) 108 break; 109 (void)close(s); 110 if (errno == EADDRINUSE) { 111 lport--; 112 continue; 113 } 114 if (errno == ECONNREFUSED && timo <= 16) { 115 (void)sleep(timo); 116 timo *= 2; 117 continue; 118 } 119 if (hp->h_addr_list[1] != NULL) { 120 int oerrno = errno; 121 122 (void)fprintf(stderr, "connect to address %s: ", 123 inet_ntoa(sin.sin_addr)); 124 errno = oerrno; 125 perror(0); 126 hp->h_addr_list++; 127 bcopy(hp->h_addr_list[0], &sin.sin_addr, hp->h_length); 128 (void)fprintf(stderr, "Trying %s...\n", 129 inet_ntoa(sin.sin_addr)); 130 continue; 131 } 132 (void)fprintf(stderr, "%s: %s\n", hp->h_name, strerror(errno)); 133 sigsetmask(oldmask); 134 return (-1); 135 } 136 lport--; 137 if (fd2p == 0) { 138 write(s, "", 1); 139 lport = 0; 140 } else { 141 char num[8]; 142 int s2 = rresvport(&lport), s3; 143 int len = sizeof(from); 144 145 if (s2 < 0) 146 goto bad; 147 listen(s2, 1); 148 (void)snprintf(num, sizeof(num), "%d", lport); 149 if (write(s, num, strlen(num)+1) != strlen(num)+1) { 150 (void)fprintf(stderr, 151 "rcmd: write (setting up stderr): %s\n", 152 strerror(errno)); 153 (void)close(s2); 154 goto bad; 155 } 156 again: 157 FD_ZERO(&reads); 158 FD_SET(s, &reads); 159 FD_SET(s2, &reads); 160 errno = 0; 161 if (select(MAX(s, s2) + 1, &reads, 0, 0, 0) < 1 || 162 !FD_ISSET(s2, &reads)) { 163 if (errno != 0) 164 (void)fprintf(stderr, 165 "rcmd: select (setting up stderr): %s\n", 166 strerror(errno)); 167 else 168 (void)fprintf(stderr, 169 "select: protocol failure in circuit setup\n"); 170 (void)close(s2); 171 goto bad; 172 } 173 s3 = accept(s2, (struct sockaddr *)&from, &len); 174 /* 175 * XXX careful for ftp bounce attacks. If discovered, shut them 176 * down and check for the real auxiliary channel to connect. 177 */ 178 if (from.sin_family == AF_INET && from.sin_port == htons(20)) { 179 close(s3); 180 goto again; 181 } 182 (void)close(s2); 183 if (s3 < 0) { 184 (void)fprintf(stderr, 185 "rcmd: accept: %s\n", strerror(errno)); 186 lport = 0; 187 goto bad; 188 } 189 *fd2p = s3; 190 from.sin_port = ntohs(from.sin_port); 191 if (from.sin_family != AF_INET || 192 from.sin_port >= IPPORT_RESERVED || 193 from.sin_port < IPPORT_RESERVED / 2) { 194 (void)fprintf(stderr, 195 "socket: protocol failure in circuit setup.\n"); 196 goto bad2; 197 } 198 } 199 (void)write(s, locuser, strlen(locuser)+1); 200 (void)write(s, remuser, strlen(remuser)+1); 201 (void)write(s, cmd, strlen(cmd)+1); 202 if (read(s, &c, 1) != 1) { 203 (void)fprintf(stderr, 204 "rcmd: %s: %s\n", *ahost, strerror(errno)); 205 goto bad2; 206 } 207 if (c != 0) { 208 while (read(s, &c, 1) == 1) { 209 (void)write(STDERR_FILENO, &c, 1); 210 if (c == '\n') 211 break; 212 } 213 goto bad2; 214 } 215 sigsetmask(oldmask); 216 return (s); 217 bad2: 218 if (lport) 219 (void)close(*fd2p); 220 bad: 221 (void)close(s); 222 sigsetmask(oldmask); 223 return (-1); 224 } 225 226 int 227 rresvport(alport) 228 int *alport; 229 { 230 struct sockaddr_in sin; 231 int s; 232 233 bzero(&sin, sizeof sin); 234 sin.sin_len = sizeof(struct sockaddr_in); 235 sin.sin_family = AF_INET; 236 sin.sin_addr.s_addr = INADDR_ANY; 237 s = socket(AF_INET, SOCK_STREAM, 0); 238 if (s < 0) 239 return (-1); 240 sin.sin_port = htons((u_short)*alport); 241 if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0) 242 return (s); 243 if (errno != EADDRINUSE) { 244 (void)close(s); 245 return (-1); 246 } 247 sin.sin_port = 0; 248 if (bindresvport(s, &sin) == -1) { 249 (void)close(s); 250 return (-1); 251 } 252 *alport = (int)ntohs(sin.sin_port); 253 return (s); 254 } 255 256 int __check_rhosts_file = 1; 257 char *__rcmd_errstr; 258 259 int 260 ruserok(rhost, superuser, ruser, luser) 261 const char *rhost, *ruser, *luser; 262 int superuser; 263 { 264 struct hostent *hp; 265 char **ap; 266 int i; 267 #define MAXADDRS 35 268 u_int32_t addrs[MAXADDRS + 1]; 269 270 if ((hp = gethostbyname(rhost)) == NULL) 271 return (-1); 272 for (i = 0, ap = hp->h_addr_list; *ap && i < MAXADDRS; ++ap, ++i) 273 bcopy(*ap, &addrs[i], sizeof(addrs[i])); 274 addrs[i] = 0; 275 276 for (i = 0; i < MAXADDRS && addrs[i]; i++) 277 if (iruserok((u_long)addrs[i], superuser, ruser, luser) == 0) 278 return (0); 279 return (-1); 280 } 281 282 /* 283 * New .rhosts strategy: We are passed an ip address. We spin through 284 * hosts.equiv and .rhosts looking for a match. When the .rhosts only 285 * has ip addresses, we don't have to trust a nameserver. When it 286 * contains hostnames, we spin through the list of addresses the nameserver 287 * gives us and look for a match. 288 * 289 * Returns 0 if ok, -1 if not ok. 290 */ 291 int 292 iruserok(raddr, superuser, ruser, luser) 293 u_int32_t raddr; 294 int superuser; 295 const char *ruser, *luser; 296 { 297 register char *cp; 298 struct stat sbuf; 299 struct passwd *pwd; 300 FILE *hostf; 301 uid_t uid; 302 int first; 303 char pbuf[MAXPATHLEN]; 304 305 first = 1; 306 hostf = superuser ? NULL : fopen(_PATH_HEQUIV, "r"); 307 again: 308 if (hostf) { 309 if (__ivaliduser(hostf, raddr, luser, ruser) == 0) { 310 (void)fclose(hostf); 311 return (0); 312 } 313 (void)fclose(hostf); 314 } 315 if (first == 1 && (__check_rhosts_file || superuser)) { 316 first = 0; 317 if ((pwd = getpwnam(luser)) == NULL) 318 return (-1); 319 (void)strcpy(pbuf, pwd->pw_dir); 320 (void)strcat(pbuf, "/.rhosts"); 321 322 /* 323 * Change effective uid while opening .rhosts. If root and 324 * reading an NFS mounted file system, can't read files that 325 * are protected read/write owner only. 326 */ 327 uid = geteuid(); 328 (void)seteuid(pwd->pw_uid); 329 hostf = fopen(pbuf, "r"); 330 (void)seteuid(uid); 331 332 if (hostf == NULL) 333 return (-1); 334 /* 335 * If not a regular file, or is owned by someone other than 336 * user or root or if writeable by anyone but the owner, quit. 337 */ 338 cp = NULL; 339 if (lstat(pbuf, &sbuf) < 0) 340 cp = ".rhosts lstat failed"; 341 else if (!S_ISREG(sbuf.st_mode)) 342 cp = ".rhosts not regular file"; 343 else if (fstat(fileno(hostf), &sbuf) < 0) 344 cp = ".rhosts fstat failed"; 345 else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid) 346 cp = "bad .rhosts owner"; 347 else if (sbuf.st_mode & (S_IWGRP|S_IWOTH)) 348 cp = ".rhosts writeable by other than owner"; 349 /* If there were any problems, quit. */ 350 if (cp) { 351 __rcmd_errstr = cp; 352 (void)fclose(hostf); 353 return (-1); 354 } 355 goto again; 356 } 357 return (-1); 358 } 359 360 /* 361 * XXX 362 * Don't make static, used by lpd(8). 363 * 364 * Returns 0 if ok, -1 if not ok. 365 */ 366 int 367 __ivaliduser(hostf, raddrl, luser, ruser) 368 FILE *hostf; 369 u_long raddrl; 370 const char *luser, *ruser; 371 { 372 register char *user, *p; 373 int ch; 374 char buf[MAXHOSTNAMELEN + 128]; /* host + login */ 375 const char *auser, *ahost; 376 int hostok, userok; 377 char *rhost = (char *)-1; 378 char domain[MAXHOSTNAMELEN]; 379 u_int32_t raddr = (u_int32_t)raddrl; 380 381 getdomainname(domain, sizeof(domain)); 382 383 while (fgets(buf, sizeof(buf), hostf)) { 384 p = buf; 385 /* Skip lines that are too long. */ 386 if (strchr(p, '\n') == NULL) { 387 while ((ch = getc(hostf)) != '\n' && ch != EOF) 388 ; 389 continue; 390 } 391 if (*p == '#') 392 continue; 393 while (*p != '\n' && *p != ' ' && *p != '\t' && *p != '\0') { 394 *p = isupper(*p) ? tolower(*p) : *p; 395 p++; 396 } 397 if (*p == ' ' || *p == '\t') { 398 *p++ = '\0'; 399 while (*p == ' ' || *p == '\t') 400 p++; 401 user = p; 402 while (*p != '\n' && *p != ' ' && 403 *p != '\t' && *p != '\0') 404 p++; 405 } else 406 user = p; 407 *p = '\0'; 408 409 if (p == buf) 410 continue; 411 412 auser = *user ? user : luser; 413 ahost = buf; 414 415 /* 416 * innetgr() must lookup a hostname (we do not attempt 417 * to change the semantics so that netgroups may have 418 * #.#.#.# addresses in the list.) 419 */ 420 if (ahost[0] == '+') 421 switch (ahost[1]) { 422 case '\0': 423 hostok = 1; 424 break; 425 case '@': 426 if (rhost == (char *)-1) 427 rhost = __gethostloop(raddr); 428 hostok = 0; 429 if (rhost) 430 hostok = innetgr(&ahost[2], rhost, 431 NULL, domain); 432 break; 433 default: 434 hostok = __icheckhost(raddr, &ahost[1]); 435 break; 436 } 437 else if (ahost[0] == '-') 438 switch (ahost[1]) { 439 case '\0': 440 hostok = -1; 441 break; 442 case '@': 443 if (rhost == (char *)-1) 444 rhost = __gethostloop(raddr); 445 hostok = 0; 446 if (rhost) 447 hostok = -innetgr(&ahost[2], rhost, 448 NULL, domain); 449 break; 450 default: 451 hostok = -__icheckhost(raddr, &ahost[1]); 452 break; 453 } 454 else 455 hostok = __icheckhost(raddr, ahost); 456 457 458 if (auser[0] == '+') 459 switch (auser[1]) { 460 case '\0': 461 userok = 1; 462 break; 463 case '@': 464 userok = innetgr(&auser[2], NULL, ruser, 465 domain); 466 break; 467 default: 468 userok = strcmp(ruser, &auser[1]) ? 0 : 1; 469 break; 470 } 471 else if (auser[0] == '-') 472 switch (auser[1]) { 473 case '\0': 474 userok = -1; 475 break; 476 case '@': 477 userok = -innetgr(&auser[2], NULL, ruser, 478 domain); 479 break; 480 default: 481 userok = strcmp(ruser, &auser[1]) ? 0 : -1; 482 break; 483 } 484 else 485 userok = strcmp(ruser, auser) ? 0 : 1; 486 487 /* Check if one component did not match */ 488 if (hostok == 0 || userok == 0) 489 continue; 490 491 /* Check if we got a forbidden pair */ 492 if (userok <= -1 || hostok <= -1) 493 return (-1); 494 495 /* Check if we got a valid pair */ 496 if (hostok >= 1 && userok >= 1) 497 return (0); 498 } 499 return (-1); 500 } 501 502 /* 503 * Returns "true" if match, 0 if no match. If we do not find any 504 * semblance of an A->PTR->A loop, allow a simple #.#.#.# match to work. 505 */ 506 static int 507 __icheckhost(raddr, lhost) 508 u_int32_t raddr; 509 const char *lhost; 510 { 511 register struct hostent *hp; 512 register char **pp; 513 struct in_addr in; 514 515 hp = gethostbyname(lhost); 516 if (hp != NULL) { 517 /* Spin through ip addresses. */ 518 for (pp = hp->h_addr_list; *pp; ++pp) 519 if (!bcmp(&raddr, *pp, sizeof(raddr))) 520 return (1); 521 } 522 523 in.s_addr = raddr; 524 if (strcmp(lhost, inet_ntoa(in)) == 0) 525 return (1); 526 return (0); 527 } 528 529 /* 530 * Return the hostname associated with the supplied address. 531 * Do a reverse lookup as well for security. If a loop cannot 532 * be found, pack the result of inet_ntoa() into the string. 533 */ 534 static char * 535 __gethostloop(raddr) 536 u_int32_t raddr; 537 { 538 static char remotehost[MAXHOSTNAMELEN]; 539 struct hostent *hp; 540 struct in_addr in; 541 542 hp = gethostbyaddr((char *) &raddr, sizeof(raddr), AF_INET); 543 if (hp == NULL) 544 return (NULL); 545 546 /* 547 * Look up the name and check that the supplied 548 * address is in the list 549 */ 550 strncpy(remotehost, hp->h_name, sizeof(remotehost) - 1); 551 remotehost[sizeof(remotehost) - 1] = '\0'; 552 hp = gethostbyname(remotehost); 553 if (hp == NULL) 554 return (NULL); 555 556 for (; hp->h_addr_list[0] != NULL; hp->h_addr_list++) 557 if (!bcmp(hp->h_addr_list[0], (caddr_t)&raddr, sizeof(raddr))) 558 return (remotehost); 559 560 /* 561 * either the DNS adminstrator has made a configuration 562 * mistake, or someone has attempted to spoof us 563 */ 564 in.s_addr = raddr; 565 syslog(LOG_NOTICE, "rcmd: address %s not listed for host %s", 566 inet_ntoa(in), hp->h_name); 567 return (NULL); 568 } 569