util.subproj/rcmd.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
   7  * Reserved.  This file contains Original Code and/or Modifications of
   8  * Original Code as defined in and that are subject to the Apple Public
   9  * Source License Version 1.1 (the "License").  You may not use this file
  10  * except in compliance with the License.  Please obtain a copy of the
  11  * License at http://www.apple.com/publicsource and read it before using
  12  * this file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT.  Please see the
  19  * License for the specific language governing rights and limitations
  20  * under the License.
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24 /*
  25  * Copyright (c) 1995, 1996, 1998 Theo de Raadt.  All rights reserved.
  26  * Copyright (c) 1983, 1993, 1994
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by the University of
  40  *      California, Berkeley and its contributors.
  41  *      This product includes software developed by Theo de Raadt.
  42  * 4. Neither the name of the University nor the names of its contributors
  43  *    may be used to endorse or promote products derived from this software
  44  *    without specific prior written permission.
  45  *
  46  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  47  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  48  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  49  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  50  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  51  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  52  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  53  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  54  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  55  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  56  * SUCH DAMAGE.
  57  */
  58
  59 #if defined(LIBC_SCCS) && !defined(lint)
  60 static char *rcsid = "$OpenBSD: rcmd.c,v 1.30 1998/02/12 02:21:19 deraadt Exp $";
  61 #endif /* LIBC_SCCS and not lint */
  62
  63 #include <sys/param.h>
  64 #include <sys/socket.h>
  65 #include <sys/stat.h>
  66
  67 #include <netinet/in.h>
  68 #include <arpa/inet.h>
  69 #include <netinfo/ni_util.h>
  70
  71 #include <signal.h>
  72 #include <fcntl.h>
  73 #include <netdb.h>
  74 #include <unistd.h>
  75 #include <pwd.h>
  76 #include <errno.h>
  77 #include <stdio.h>
  78 #include <ctype.h>
  79 #include <string.h>
  80 #include <syslog.h>
  81 #include <stdlib.h>
  82
  83 typedef u_int32_t       in_addr_t;      /* base type for internet address */
  84 typedef u_int16_t       in_port_t;      /* IP port type */
  85
  86 extern int bindresvport(int sd, struct sockaddr_in *sin);
  87 extern int getdomainname(char *val, size_t len);
  88 extern int rcmdsh(char **ahost, int rport, const char *locuser, const char *remuser, const char *cmd, char *rshprog);
  89
  90 int     __ivaliduser __P((FILE *, in_addr_t, const char *, const char *));
  91 static int __icheckhost __P((u_int32_t, const char *));
  92 static char *__gethostloop __P((u_int32_t));
  93
  94 int
  95 rcmd(ahost, rport, locuser, remuser, cmd, fd2p)
  96         char **ahost;
  97         in_port_t rport;
  98         const char *locuser, *remuser, *cmd;
  99         int *fd2p;
 100 {
 101         struct hostent *hp;
 102         struct sockaddr_in sin, from;
 103         fd_set *readsp = NULL;
 104         int oldmask;
 105         pid_t pid;
 106         int s, lport, timo;
 107         char c, *p;
 108
 109         /* call rcmdsh() with specified remote shell if appropriate. */
 110         if ((getuid() == geteuid()) && (p = getenv("RSH"))) {
 111                 struct servent *sp = getservbyname("shell", "tcp");
 112
 113                 if (sp && sp->s_port == rport)
 114                         return (rcmdsh(ahost, rport, locuser, remuser,
 115                             cmd, p));
 116         }
 117
 118         /* use rsh(1) if non-root and remote port is shell. */
 119         if (geteuid()) {
 120                 struct servent *sp = getservbyname("shell", "tcp");
 121
 122                 if (sp && sp->s_port == rport)
 123                         return (rcmdsh(ahost, rport, locuser, remuser,
 124                             cmd, NULL));
 125         }
 126
 127         pid = getpid();
 128         hp = gethostbyname(*ahost);
 129         if (hp == NULL) {
 130                 herror(*ahost);
 131                 return (-1);
 132         }
 133         *ahost = hp->h_name;
 134
 135         oldmask = sigblock(sigmask(SIGURG));
 136         for (timo = 1, lport = IPPORT_RESERVED - 1;;) {
 137                 s = rresvport(&lport);
 138                 if (s < 0) {
 139                         if (errno == EAGAIN)
 140                                 (void)fprintf(stderr,
 141                                     "rcmd: socket: All ports in use\n");
 142                         else
 143                                 (void)fprintf(stderr, "rcmd: socket: %s\n",
 144                                     strerror(errno));
 145                         sigsetmask(oldmask);
 146                         return (-1);
 147                 }
 148                 fcntl(s, F_SETOWN, pid);
 149                 bzero(&sin, sizeof sin);
 150                 sin.sin_len = sizeof(struct sockaddr_in);
 151                 sin.sin_family = hp->h_addrtype;
 152                 sin.sin_port = rport;
 153                 bcopy(hp->h_addr_list[0], &sin.sin_addr, hp->h_length);
 154                 if (connect(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
 155                         break;
 156                 (void)close(s);
 157                 if (errno == EADDRINUSE) {
 158                         lport--;
 159                         continue;
 160                 }
 161                 if (errno == ECONNREFUSED && timo <= 16) {
 162                         (void)sleep(timo);
 163                         timo *= 2;
 164                         continue;
 165                 }
 166                 if (hp->h_addr_list[1] != NULL) {
 167                         int oerrno = errno;
 168
 169                         (void)fprintf(stderr, "connect to address %s: ",
 170                             inet_ntoa(sin.sin_addr));
 171                         errno = oerrno;
 172                         perror(0);
 173                         hp->h_addr_list++;
 174                         bcopy(hp->h_addr_list[0], &sin.sin_addr, hp->h_length);
 175                         (void)fprintf(stderr, "Trying %s...\n",
 176                             inet_ntoa(sin.sin_addr));
 177                         continue;
 178                 }
 179                 (void)fprintf(stderr, "%s: %s\n", hp->h_name, strerror(errno));
 180                 sigsetmask(oldmask);
 181                 return (-1);
 182         }
 183 #if 0
 184         /*
 185          * try to rresvport() to the same port. This will make rresvport()
 186          * fail it's first bind, resulting in it choosing a random port.
 187          */
 188         lport--;
 189 #endif
 190         if (fd2p == 0) {
 191                 write(s, "", 1);
 192                 lport = 0;
 193         } else {
 194                 char num[8];
 195                 int s2 = rresvport(&lport), s3;
 196                 int len = sizeof(from);
 197                 int fdssize = howmany(MAX(s, s2)+1, NFDBITS) * sizeof(fd_mask);
 198
 199                 if (s2 < 0)
 200                         goto bad;
 201                 readsp = (fd_set *)malloc(fdssize);
 202                 if (readsp == NULL)
 203                         goto bad;
 204                 listen(s2, 1);
 205                 (void)snprintf(num, sizeof(num), "%d", lport);
 206                 if (write(s, num, strlen(num)+1) != strlen(num)+1) {
 207                         (void)fprintf(stderr,
 208                             "rcmd: write (setting up stderr): %s\n",
 209                             strerror(errno));
 210                         (void)close(s2);
 211                         goto bad;
 212                 }
 213 again:
 214                 bzero(readsp, fdssize);
 215                 FD_SET(s, readsp);
 216                 FD_SET(s2, readsp);
 217                 errno = 0;
 218                 if (select(MAX(s, s2) + 1, readsp, 0, 0, 0) < 1 ||
 219                     !FD_ISSET(s2, readsp)) {
 220                         if (errno != 0)
 221                                 (void)fprintf(stderr,
 222                                     "rcmd: select (setting up stderr): %s\n",
 223                                     strerror(errno));
 224                         else
 225                                 (void)fprintf(stderr,
 226                                 "select: protocol failure in circuit setup\n");
 227                         (void)close(s2);
 228                         goto bad;
 229                 }
 230                 s3 = accept(s2, (struct sockaddr *)&from, &len);
 231                 /*
 232                  * XXX careful for ftp bounce attacks. If discovered, shut them
 233                  * down and check for the real auxiliary channel to connect.
 234                  */
 235                 if (from.sin_family == AF_INET && from.sin_port == htons(20)) {
 236                         close(s3);
 237                         goto again;
 238                 }
 239                 (void)close(s2);
 240                 if (s3 < 0) {
 241                         (void)fprintf(stderr,
 242                             "rcmd: accept: %s\n", strerror(errno));
 243                         lport = 0;
 244                         goto bad;
 245                 }
 246                 *fd2p = s3;
 247                 from.sin_port = ntohs(from.sin_port);
 248                 if (from.sin_family != AF_INET ||
 249                     from.sin_port >= IPPORT_RESERVED ||
 250                     from.sin_port < IPPORT_RESERVED / 2) {
 251                         (void)fprintf(stderr,
 252                             "socket: protocol failure in circuit setup.\n");
 253                         goto bad2;
 254                 }
 255         }
 256         (void)write(s, locuser, strlen(locuser)+1);
 257         (void)write(s, remuser, strlen(remuser)+1);
 258         (void)write(s, cmd, strlen(cmd)+1);
 259         if (read(s, &c, 1) != 1) {
 260                 (void)fprintf(stderr,
 261                     "rcmd: %s: %s\n", *ahost, strerror(errno));
 262                 goto bad2;
 263         }
 264         if (c != 0) {
 265                 while (read(s, &c, 1) == 1) {
 266                         (void)write(STDERR_FILENO, &c, 1);
 267                         if (c == '\n')
 268                                 break;
 269                 }
 270                 goto bad2;
 271         }
 272         sigsetmask(oldmask);
 273         free(readsp);
 274         return (s);
 275 bad2:
 276         if (lport)
 277                 (void)close(*fd2p);
 278 bad:
 279         if (readsp)
 280                 free(readsp);
 281         (void)close(s);
 282         sigsetmask(oldmask);
 283         return (-1);
 284 }
 285
 286 int
 287 rresvport(alport)
 288         int *alport;
 289 {
 290         struct sockaddr_in sin;
 291         int s;
 292
 293         bzero(&sin, sizeof sin);
 294         sin.sin_len = sizeof(struct sockaddr_in);
 295         sin.sin_family = AF_INET;
 296         sin.sin_addr.s_addr = INADDR_ANY;
 297         s = socket(AF_INET, SOCK_STREAM, 0);
 298         if (s < 0)
 299                 return (-1);
 300         sin.sin_port = htons((in_port_t)*alport);
 301         if (*alport < IPPORT_RESERVED - 1) {
 302                 if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
 303                         return (s);
 304                 if (errno != EADDRINUSE) {
 305                         (void)close(s);
 306                         return (-1);
 307                 }
 308         }
 309         sin.sin_port = 0;
 310         if (bindresvport(s, &sin) == -1) {
 311                 (void)close(s);
 312                 return (-1);
 313         }
 314         *alport = (int)ntohs(sin.sin_port);
 315         return (s);
 316 }
 317
 318 int     __check_rhosts_file = 1;
 319 char    *__rcmd_errstr;
 320
 321 int
 322 ruserok(rhost, superuser, ruser, luser)
 323         const char *rhost, *ruser, *luser;
 324         int superuser;
 325 {
 326         struct hostent *hp;
 327         char **ap;
 328         int i;
 329 #define MAXADDRS        35
 330         u_int32_t addrs[MAXADDRS + 1];
 331
 332         if ((hp = gethostbyname(rhost)) == NULL)
 333                 return (-1);
 334         for (i = 0, ap = hp->h_addr_list; *ap && i < MAXADDRS; ++ap, ++i)
 335                 bcopy(*ap, &addrs[i], sizeof(addrs[i]));
 336         addrs[i] = 0;
 337
 338         for (i = 0; i < MAXADDRS && addrs[i]; i++)
 339                 if (iruserok((in_addr_t)addrs[i], superuser, ruser, luser) == 0)
 340                         return (0);
 341         return (-1);
 342 }
 343
 344 /*
 345  * New .rhosts strategy: We are passed an ip address. We spin through
 346  * hosts.equiv and .rhosts looking for a match. When the .rhosts only
 347  * has ip addresses, we don't have to trust a nameserver.  When it
 348  * contains hostnames, we spin through the list of addresses the nameserver
 349  * gives us and look for a match.
 350  *
 351  * Returns 0 if ok, -1 if not ok.
 352  */
 353 int
 354 iruserok(raddr, superuser, ruser, luser)
 355         unsigned long raddr;
 356         int superuser;
 357         const char *ruser, *luser;
 358 {
 359         register char *cp;
 360         struct stat sbuf;
 361         struct passwd *pwd;
 362         FILE *hostf;
 363         uid_t uid;
 364         int first;
 365         char pbuf[MAXPATHLEN];
 366
 367         first = 1;
 368         hostf = superuser ? NULL : fopen(_PATH_HEQUIV, "r");
 369 again:
 370         if (hostf) {
 371                 if (__ivaliduser(hostf, raddr, luser, ruser) == 0) {
 372                         (void)fclose(hostf);
 373                         return (0);
 374                 }
 375                 (void)fclose(hostf);
 376         }
 377         if (first == 1 && (__check_rhosts_file || superuser)) {
 378                 first = 0;
 379                 if ((pwd = getpwnam(luser)) == NULL)
 380                         return (-1);
 381                 (void)strcpy(pbuf, pwd->pw_dir);
 382                 (void)strcat(pbuf, "/.rhosts");
 383
 384                 /*
 385                  * Change effective uid while opening .rhosts.  If root and
 386                  * reading an NFS mounted file system, can't read files that
 387                  * are protected read/write owner only.
 388                  */
 389                 uid = geteuid();
 390                 (void)seteuid(pwd->pw_uid);
 391                 hostf = fopen(pbuf, "r");
 392                 (void)seteuid(uid);
 393
 394                 if (hostf == NULL)
 395                         return (-1);
 396                 /*
 397                  * If not a regular file, or is owned by someone other than
 398                  * user or root or if writeable by anyone but the owner, quit.
 399                  */
 400                 cp = NULL;
 401                 if (lstat(pbuf, &sbuf) < 0)
 402                         cp = ".rhosts lstat failed";
 403                 else if (!S_ISREG(sbuf.st_mode))
 404                         cp = ".rhosts not regular file";
 405                 else if (fstat(fileno(hostf), &sbuf) < 0)
 406                         cp = ".rhosts fstat failed";
 407                 else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid)
 408                         cp = "bad .rhosts owner";
 409                 else if (sbuf.st_mode & (S_IWGRP|S_IWOTH))
 410                         cp = ".rhosts writeable by other than owner";
 411                 /* If there were any problems, quit. */
 412                 if (cp) {
 413                         __rcmd_errstr = cp;
 414                         (void)fclose(hostf);
 415                         return (-1);
 416                 }
 417                 goto again;
 418         }
 419         return (-1);
 420 }
 421
 422 /*
 423  * XXX
 424  * Don't make static, used by lpd(8).
 425  *
 426  * Returns 0 if ok, -1 if not ok.
 427  */
 428 int
 429 __ivaliduser(hostf, raddrl, luser, ruser)
 430         FILE *hostf;
 431         in_addr_t raddrl;
 432         const char *luser, *ruser;
 433 {
 434         register char *user, *p;
 435         char *buf;
 436         const char *auser, *ahost;
 437         int hostok, userok;
 438         char *rhost = (char *)-1;
 439         char domain[MAXHOSTNAMELEN];
 440         u_int32_t raddr = (u_int32_t)raddrl;
 441         size_t buflen;
 442
 443         getdomainname(domain, sizeof(domain));
 444
 445         while ((buf = fgetln(hostf, &buflen))) {
 446                 p = buf;
 447                 if (*p == '#')
 448                         continue;
 449                 while (*p != '\n' && *p != ' ' && *p != '\t' && p < buf + buflen) {
 450                         if (!isprint(*p))
 451                                 goto bail;
 452                         *p = isupper(*p) ? tolower(*p) : *p;
 453                         p++;
 454                 }
 455                 if (p >= buf + buflen)
 456                         continue;
 457                 if (*p == ' ' || *p == '\t') {
 458                         *p++ = '\0';
 459                         while (*p == ' ' || *p == '\t' && p < buf + buflen)
 460                                 p++;
 461                         if (p >= buf + buflen)
 462                                 continue;
 463                         user = p;
 464                         while (*p != '\n' && *p != ' ' &&
 465                             *p != '\t' && p < buf + buflen) {
 466                                 if (!isprint(*p))
 467                                         goto bail;
 468                                 p++;
 469                         }
 470                 } else
 471                         user = p;
 472                 *p = '\0';
 473
 474                 if (p == buf)
 475                         continue;
 476
 477                 auser = *user ? user : luser;
 478                 ahost = buf;
 479
 480                 if (strlen(ahost) >= MAXHOSTNAMELEN)
 481                         continue;
 482
 483                 /*
 484                  * innetgr() must lookup a hostname (we do not attempt
 485                  * to change the semantics so that netgroups may have
 486                  * #.#.#.# addresses in the list.)
 487                  */
 488                 if (ahost[0] == '+')
 489                         switch (ahost[1]) {
 490                         case '\0':
 491                                 hostok = 1;
 492                                 break;
 493                         case '@':
 494                                 if (rhost == (char *)-1)
 495                                         rhost = __gethostloop(raddr);
 496                                 hostok = 0;
 497                                 if (rhost)
 498                                         hostok = innetgr(&ahost[2], rhost,
 499                                             NULL, domain);
 500                                 break;
 501                         default:
 502                                 hostok = __icheckhost(raddr, &ahost[1]);
 503                                 break;
 504                         }
 505                 else if (ahost[0] == '-')
 506                         switch (ahost[1]) {
 507                         case '\0':
 508                                 hostok = -1;
 509                                 break;
 510                         case '@':
 511                                 if (rhost == (char *)-1)
 512                                         rhost = __gethostloop(raddr);
 513                                 hostok = 0;
 514                                 if (rhost)
 515                                         hostok = -innetgr(&ahost[2], rhost,
 516                                             NULL, domain);
 517                                 break;
 518                         default:
 519                                 hostok = -__icheckhost(raddr, &ahost[1]);
 520                                 break;
 521                         }
 522                 else
 523                         hostok = __icheckhost(raddr, ahost);
 524
 525
 526                 if (auser[0] == '+')
 527                         switch (auser[1]) {
 528                         case '\0':
 529                                 userok = 1;
 530                                 break;
 531                         case '@':
 532                                 userok = innetgr(&auser[2], NULL, ruser,
 533                                     domain);
 534                                 break;
 535                         default:
 536                                 userok = strcmp(ruser, &auser[1]) ? 0 : 1;
 537                                 break;
 538                         }
 539                 else if (auser[0] == '-')
 540                         switch (auser[1]) {
 541                         case '\0':
 542                                 userok = -1;
 543                                 break;
 544                         case '@':
 545                                 userok = -innetgr(&auser[2], NULL, ruser,
 546                                     domain);
 547                                 break;
 548                         default:
 549                                 userok = strcmp(ruser, &auser[1]) ? 0 : -1;
 550                                 break;
 551                         }
 552                 else
 553                         userok = strcmp(ruser, auser) ? 0 : 1;
 554
 555                 /* Check if one component did not match */
 556                 if (hostok == 0 || userok == 0)
 557                         continue;
 558
 559                 /* Check if we got a forbidden pair */
 560                 if (userok <= -1 || hostok <= -1)
 561                         return (-1);
 562
 563                 /* Check if we got a valid pair */
 564                 if (hostok >= 1 && userok >= 1)
 565                         return (0);
 566         }
 567 bail:
 568         return (-1);
 569 }
 570
 571 /*
 572  * Returns "true" if match, 0 if no match.  If we do not find any
 573  * semblance of an A->PTR->A loop, allow a simple #.#.#.# match to work.
 574  */
 575 static int
 576 __icheckhost(raddr, lhost)
 577         u_int32_t raddr;
 578         const char *lhost;
 579 {
 580         register struct hostent *hp;
 581         register char **pp;
 582         struct in_addr in;
 583
 584         hp = gethostbyname(lhost);
 585         if (hp != NULL) {
 586                 /* Spin through ip addresses. */
 587                 for (pp = hp->h_addr_list; *pp; ++pp)
 588                         if (!bcmp(&raddr, *pp, sizeof(raddr)))
 589                                 return (1);
 590         }
 591
 592         in.s_addr = raddr;
 593         if (strcmp(lhost, inet_ntoa(in)) == 0)
 594                 return (1);
 595         return (0);
 596 }
 597
 598 /*
 599  * Return the hostname associated with the supplied address.
 600  * Do a reverse lookup as well for security. If a loop cannot
 601  * be found, pack the result of inet_ntoa() into the string.
 602  */
 603 static char *
 604 __gethostloop(raddr)
 605         u_int32_t raddr;
 606 {
 607         static char remotehost[MAXHOSTNAMELEN];
 608         struct hostent *hp;
 609         struct in_addr in;
 610
 611         hp = gethostbyaddr((char *) &raddr, sizeof(raddr), AF_INET);
 612         if (hp == NULL)
 613                 return (NULL);
 614
 615         /*
 616          * Look up the name and check that the supplied
 617          * address is in the list
 618          */
 619         strncpy(remotehost, hp->h_name, sizeof(remotehost) - 1);
 620         remotehost[sizeof(remotehost) - 1] = '\0';
 621         hp = gethostbyname(remotehost);
 622         if (hp == NULL)
 623                 return (NULL);
 624
 625         for (; hp->h_addr_list[0] != NULL; hp->h_addr_list++)
 626                 if (!bcmp(hp->h_addr_list[0], (caddr_t)&raddr, sizeof(raddr)))
 627                         return (remotehost);
 628
 629         /*
 630          * either the DNS adminstrator has made a configuration
 631          * mistake, or someone has attempted to spoof us
 632          */
 633         in.s_addr = raddr;
 634         syslog(LOG_NOTICE, "rcmd: address %s not listed for host %s",
 635             inet_ntoa(in), hp->h_name);
 636         return (NULL);
 637 }