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