inet/rcmd.c

   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 sccsid[] = "@(#)rcmd.c      8.3 (Berkeley) 3/26/94";
  36 #endif /* LIBC_SCCS and not lint */
  37
  38 #include <sys/param.h>
  39 #include <sys/poll.h>
  40 #include <sys/socket.h>
  41 #include <sys/stat.h>
  42
  43 #include <netinet/in.h>
  44 #include <arpa/inet.h>
  45
  46 #include <alloca.h>
  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
  57
  58 int __ivaliduser __P ((FILE *, u_int32_t, const char *, const char *));
  59 static int __ivaliduser2 __P ((FILE *, u_int32_t, const char *, const char *,
  60                                const char *));
  61
  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 hostbuf, *hp;
  71         size_t hstbuflen;
  72         char *tmphstbuf;
  73         struct sockaddr_in sin, from;
  74         struct pollfd pfd[2];
  75         int32_t oldmask;
  76         pid_t pid;
  77         int s, lport, timo;
  78         char c;
  79         int herr;
  80
  81         pid = __getpid();
  82
  83         hstbuflen = 1024;
  84         tmphstbuf = __alloca (hstbuflen);
  85         while (__gethostbyname_r (*ahost, &hostbuf, tmphstbuf, hstbuflen,
  86                                   &hp, &herr) < 0)
  87           if (herr != NETDB_INTERNAL || errno != ERANGE)
  88             {
  89               __set_h_errno (herr);
  90               herror(*ahost);
  91               return -1;
  92             }
  93           else
  94             {
  95               /* Enlarge the buffer.  */
  96               hstbuflen *= 2;
  97               tmphstbuf = __alloca (hstbuflen);
  98             }
  99
 100         pfd[0].events = POLLIN;
 101         pfd[1].events = POLLIN;
 102
 103         *ahost = hp->h_name;
 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: %m\n");
 113                         __sigsetmask(oldmask);
 114                         return -1;
 115                 }
 116                 __fcntl(s, F_SETOWN, pid);
 117                 sin.sin_family = hp->h_addrtype;
 118                 bcopy(hp->h_addr_list[0], &sin.sin_addr,
 119                       MIN (sizeof (sin.sin_addr), hp->h_length));
 120                 sin.sin_port = rport;
 121                 if (__connect(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
 122                         break;
 123                 (void)__close(s);
 124                 if (errno == EADDRINUSE) {
 125                         lport--;
 126                         continue;
 127                 }
 128                 if (errno == ECONNREFUSED && timo <= 16) {
 129                         (void)__sleep(timo);
 130                         timo *= 2;
 131                         continue;
 132                 }
 133                 if (hp->h_addr_list[1] != NULL) {
 134                         int oerrno = errno;
 135
 136                         (void)fprintf(stderr, _("connect to address %s: "),
 137                             inet_ntoa(sin.sin_addr));
 138                         __set_errno (oerrno);
 139                         perror(0);
 140                         hp->h_addr_list++;
 141                         bcopy(hp->h_addr_list[0], &sin.sin_addr,
 142                               MIN (sizeof (sin.sin_addr), hp->h_length));
 143                         (void)fprintf(stderr, _("Trying %s...\n"),
 144                             inet_ntoa(sin.sin_addr));
 145                         continue;
 146                 }
 147                 (void)fprintf(stderr, "%s: %m\n", hp->h_name);
 148                 __sigsetmask(oldmask);
 149                 return -1;
 150         }
 151         lport--;
 152         if (fd2p == 0) {
 153                 __write(s, "", 1);
 154                 lport = 0;
 155         } else {
 156                 char num[8];
 157                 int s2 = rresvport(&lport), s3;
 158                 size_t len = sizeof(from);
 159
 160                 if (s2 < 0)
 161                         goto bad;
 162                 listen(s2, 1);
 163                 (void)__snprintf(num, sizeof(num), "%d", lport);
 164                 if (__write(s, num, strlen(num)+1) != strlen(num)+1) {
 165                         (void)fprintf(stderr,
 166                             _("rcmd: write (setting up stderr): %m\n"));
 167                         (void)__close(s2);
 168                         goto bad;
 169                 }
 170                 pfd[0].fd = s;
 171                 pfd[1].fd = s2;
 172                 __set_errno (0);
 173                 if (__poll (pfd, 2, -1) < 1 || (pfd[1].revents & POLLIN) == 0){
 174                         if (errno != 0)
 175                                 (void)fprintf(stderr,
 176                                   _("rcmd: poll (setting up stderr): %m\n"));
 177                         else
 178                                 (void)fprintf(stderr,
 179                              _("poll: protocol failure in circuit setup\n"));
 180                         (void)__close(s2);
 181                         goto bad;
 182                 }
 183                 s3 = accept(s2, (struct sockaddr *)&from, &len);
 184                 (void)__close(s2);
 185                 if (s3 < 0) {
 186                         (void)fprintf(stderr,
 187                             "rcmd: accept: %m\n");
 188                         lport = 0;
 189                         goto bad;
 190                 }
 191                 *fd2p = s3;
 192                 from.sin_port = ntohs((u_short)from.sin_port);
 193                 if (from.sin_family != AF_INET ||
 194                     from.sin_port >= IPPORT_RESERVED ||
 195                     from.sin_port < IPPORT_RESERVED / 2) {
 196                         (void)fprintf(stderr,
 197                             _("socket: protocol failure in circuit setup\n"));
 198                         goto bad2;
 199                 }
 200         }
 201         (void)__write(s, locuser, strlen(locuser)+1);
 202         (void)__write(s, remuser, strlen(remuser)+1);
 203         (void)__write(s, cmd, strlen(cmd)+1);
 204         if (__read(s, &c, 1) != 1) {
 205                 (void)fprintf(stderr,
 206                     "rcmd: %s: %m\n", *ahost);
 207                 goto bad2;
 208         }
 209         if (c != 0) {
 210                 while (__read(s, &c, 1) == 1) {
 211                         (void)__write(STDERR_FILENO, &c, 1);
 212                         if (c == '\n')
 213                                 break;
 214                 }
 215                 goto bad2;
 216         }
 217         __sigsetmask(oldmask);
 218         return s;
 219 bad2:
 220         if (lport)
 221                 (void)__close(*fd2p);
 222 bad:
 223         (void)__close(s);
 224         __sigsetmask(oldmask);
 225         return -1;
 226 }
 227
 228 int
 229 rresvport(alport)
 230         int *alport;
 231 {
 232         struct sockaddr_in sin;
 233         int s;
 234
 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         for (;;) {
 241                 sin.sin_port = htons((u_short)*alport);
 242                 if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
 243                         return s;
 244                 if (errno != EADDRINUSE) {
 245                         (void)__close(s);
 246                         return -1;
 247                 }
 248                 (*alport)--;
 249                 if (*alport == IPPORT_RESERVED/2) {
 250                         (void)__close(s);
 251                         __set_errno (EAGAIN);           /* close */
 252                         return -1;
 253                 }
 254         }
 255 }
 256
 257 int     __check_rhosts_file = 1;
 258 char    *__rcmd_errstr;
 259
 260 int
 261 ruserok(rhost, superuser, ruser, luser)
 262         const char *rhost, *ruser, *luser;
 263         int superuser;
 264 {
 265         struct hostent hostbuf, *hp;
 266         size_t buflen;
 267         char *buffer;
 268         u_int32_t addr;
 269         char **ap;
 270         int herr;
 271
 272         buflen = 1024;
 273         buffer = __alloca (buflen);
 274
 275         while (__gethostbyname_r (rhost, &hostbuf, buffer, buflen, &hp, &herr)
 276                < 0)
 277           if (herr != NETDB_INTERNAL || errno != ERANGE)
 278             return -1;
 279           else
 280             {
 281               /* Enlarge the buffer.  */
 282               buflen *= 2;
 283               buffer = __alloca (buflen);
 284             }
 285
 286         for (ap = hp->h_addr_list; *ap; ++ap) {
 287                 bcopy(*ap, &addr, sizeof(addr));
 288                 if (iruserok(addr, superuser, ruser, luser, rhost) == 0)
 289                         return 0;
 290         }
 291         return -1;
 292 }
 293
 294 /* Extremely paranoid file open function. */
 295 static FILE *
 296 iruserfopen (char *file, uid_t okuser)
 297 {
 298   struct stat st;
 299   char *cp = NULL;
 300   FILE *res = NULL;
 301
 302   /* If not a regular file, if owned by someone other than user or
 303      root, if writeable by anyone but the owner, or if hardlinked
 304      anywhere, quit.  */
 305   cp = NULL;
 306   if (__lxstat (_STAT_VER, file, &st))
 307     cp = _("lstat failed");
 308   else if (!S_ISREG (st.st_mode))
 309     cp = _("not regular file");
 310   else
 311     {
 312       res = fopen (file, "r");
 313       if (!res)
 314         cp = _("cannot open");
 315       else if (__fxstat (_STAT_VER, fileno (res), &st) < 0)
 316         cp = _("fstat failed");
 317       else if (st.st_uid && st.st_uid != okuser)
 318         cp = _("bad owner");
 319       else if (st.st_mode & (S_IWGRP|S_IWOTH))
 320         cp = _("writeable by other than owner");
 321       else if (st.st_nlink > 1)
 322         cp = _("hard linked somewhere");
 323     }
 324
 325   /* If there were any problems, quit.  */
 326   if (cp != NULL)
 327     {
 328       __rcmd_errstr = cp;
 329       if (res)
 330         fclose (res);
 331       return NULL;
 332     }
 333
 334   return res;
 335 }
 336
 337 /*
 338  * New .rhosts strategy: We are passed an ip address. We spin through
 339  * hosts.equiv and .rhosts looking for a match. When the .rhosts only
 340  * has ip addresses, we don't have to trust a nameserver.  When it
 341  * contains hostnames, we spin through the list of addresses the nameserver
 342  * gives us and look for a match.
 343  *
 344  * Returns 0 if ok, -1 if not ok.
 345  */
 346 static int
 347 iruserok2 (raddr, superuser, ruser, luser, rhost)
 348      u_int32_t raddr;
 349      int superuser;
 350      const char *ruser, *luser, *rhost;
 351 {
 352   FILE *hostf = NULL;
 353   int isbad;
 354
 355   if (!superuser)
 356     hostf = iruserfopen (_PATH_HEQUIV, 0);
 357
 358   if (hostf)
 359     {
 360       isbad = __ivaliduser2 (hostf, raddr, luser, ruser, rhost);
 361       fclose (hostf);
 362
 363       if (!isbad)
 364         return 0;
 365     }
 366
 367   if (__check_rhosts_file || superuser)
 368     {
 369       char *pbuf;
 370       struct passwd pwdbuf, *pwd;
 371       size_t dirlen;
 372       size_t buflen = __sysconf (_SC_GETPW_R_SIZE_MAX);
 373       char *buffer = __alloca (buflen);
 374       uid_t uid;
 375
 376       if (__getpwnam_r (luser, &pwdbuf, buffer, buflen, &pwd))
 377         return -1;
 378
 379       dirlen = strlen (pwd->pw_dir);
 380       pbuf = alloca (dirlen + sizeof "/.rhosts");
 381       __mempcpy (__mempcpy (pbuf, pwd->pw_dir, dirlen),
 382                  "/.rhosts", sizeof "/.rhosts");
 383
 384        /* Change effective uid while reading .rhosts.  If root and
 385           reading an NFS mounted file system, can't read files that
 386           are protected read/write owner only.  */
 387        uid = __geteuid ();
 388        seteuid (pwd->pw_uid);
 389        hostf = iruserfopen (pbuf, pwd->pw_uid);
 390
 391        if (hostf != NULL)
 392          {
 393            isbad = __ivaliduser2 (hostf, raddr, luser, ruser, rhost);
 394            fclose (hostf);
 395          }
 396
 397        seteuid (uid);
 398        return isbad;
 399     }
 400   return -1;
 401 }
 402
 403 /* This is the exported version.  */
 404 int
 405 iruserok (raddr, superuser, ruser, luser)
 406      u_int32_t raddr;
 407      int superuser;
 408      const char *ruser, *luser;
 409 {
 410   return iruserok2 (raddr, superuser, ruser, luser, "-");
 411 }
 412
 413 /*
 414  * XXX
 415  * Don't make static, used by lpd(8).
 416  *
 417  * This function is not used anymore. It is only present because lpd(8)
 418  * calls it (!?!). We simply call __invaliduser2() with an illegal rhost
 419  * argument. This means that netgroups won't work in .rhost/hosts.equiv
 420  * files. If you want lpd to work with netgroups, fix lpd to use ruserok()
 421  * or PAM.
 422  * Returns 0 if ok, -1 if not ok.
 423  */
 424 int
 425 __ivaliduser(hostf, raddr, luser, ruser)
 426         FILE *hostf;
 427         u_int32_t raddr;
 428         const char *luser, *ruser;
 429 {
 430         return __ivaliduser2(hostf, raddr, luser, ruser, "-");
 431 }
 432
 433
 434 /* Returns 1 on positive match, 0 on no match, -1 on negative match.  */
 435 static int
 436 internal_function
 437 __icheckhost (raddr, lhost, rhost)
 438         u_int32_t raddr;
 439         char *lhost;
 440         const char *rhost;
 441 {
 442         struct hostent hostbuf, *hp;
 443         size_t buflen;
 444         char *buffer;
 445         int herr;
 446         int save_errno;
 447         u_int32_t laddr;
 448         int negate=1;    /* Multiply return with this to get -1 instead of 1 */
 449         char **pp, *user;
 450
 451         /* Check nis netgroup.  */
 452         if (strncmp ("+@", lhost, 2) == 0)
 453                 return innetgr (&lhost[2], rhost, NULL, NULL);
 454
 455         if (strncmp ("-@", lhost, 2) == 0)
 456                 return -innetgr (&lhost[2], rhost, NULL, NULL);
 457
 458         /* -host */
 459         if (strncmp ("-", lhost,1) == 0) {
 460                 negate = -1;
 461                 lhost++;
 462         } else if (strcmp ("+",lhost) == 0) {
 463                 return 1;                    /* asking for trouble, but ok.. */
 464         }
 465
 466         /* Try for raw ip address first. */
 467         if (isdigit (*lhost) && (long) (laddr = inet_addr (lhost)) != -1)
 468                 return negate * (! (raddr ^ laddr));
 469
 470         /* Better be a hostname. */
 471         buflen = 1024;
 472         buffer = __alloca (buflen);
 473         save_errno = errno;
 474         while (__gethostbyname_r (lhost, &hostbuf, buffer, buflen, &hp, &herr)
 475                < 0)
 476                 if (herr != NETDB_INTERNAL || errno != ERANGE)
 477                         return (0);
 478                 else {
 479                         /* Enlarge the buffer.  */
 480                         buflen *= 2;
 481                         buffer = __alloca (buflen);
 482                         __set_errno (0);
 483                 }
 484         __set_errno (save_errno);
 485         if (hp == NULL)
 486                 return 0;
 487
 488         /* Spin through ip addresses. */
 489         for (pp = hp->h_addr_list; *pp; ++pp)
 490                 if (!memcmp (&raddr, *pp, sizeof (u_int32_t)))
 491                         return negate;
 492
 493         /* No match. */
 494         return (0);
 495 }
 496
 497 /* Returns 1 on positive match, 0 on no match, -1 on negative match.  */
 498 static int
 499 internal_function
 500 __icheckuser (luser, ruser)
 501         const char *luser, *ruser;
 502 {
 503     /*
 504       luser is user entry from .rhosts/hosts.equiv file
 505       ruser is user id on remote host
 506       */
 507     char *user;
 508
 509     /* [-+]@netgroup */
 510     if (strncmp ("+@", luser, 2) == 0)
 511         return innetgr (&luser[2], NULL, ruser, NULL);
 512
 513     if (strncmp ("-@", luser,2) == 0)
 514         return -innetgr (&luser[2], NULL, ruser, NULL);
 515
 516     /* -user */
 517     if (strncmp ("-", luser, 1) == 0)
 518         return -(strcmp (&luser[1], ruser) == 0);
 519
 520     /* + */
 521     if (strcmp ("+", luser) == 0)
 522         return 1;
 523
 524     /* simple string match */
 525     return strcmp (ruser, luser) == 0;
 526 }
 527
 528 /*
 529  * Returns 1 for blank lines (or only comment lines) and 0 otherwise
 530  */
 531 static int
 532 __isempty(p)
 533         char *p;
 534 {
 535     while (*p && isspace (*p)) {
 536         ++p;
 537     }
 538
 539     return (*p == '\0' || *p == '#') ? 1 : 0 ;
 540 }
 541
 542 /*
 543  * Returns 0 if positive match, -1 if _not_ ok.
 544  */
 545 static int
 546 __ivaliduser2(hostf, raddr, luser, ruser, rhost)
 547         FILE *hostf;
 548         u_int32_t raddr;
 549         const char *luser, *ruser, *rhost;
 550 {
 551     register const char *user;
 552     register char *p;
 553     int hcheck, ucheck;
 554     char *buf = NULL;
 555     size_t bufsize = 0;
 556
 557     while (__getline (&buf, &bufsize, hostf) > 0) {
 558         buf[bufsize - 1] = '\0'; /* Make sure it's terminated.  */
 559         p = buf;
 560
 561         /* Skip empty or comment lines */
 562         if (__isempty (p)) {
 563             continue;
 564         }
 565
 566         /* Skip lines that are too long. */
 567         if (strchr (p, '\n') == NULL) {
 568             int ch = getc (hostf);
 569
 570             while (ch != '\n' && ch != EOF)
 571                 ch = getc (hostf);
 572             continue;
 573         }
 574
 575         for (;*p && !isspace(*p); ++p) {
 576             *p = tolower (*p);
 577         }
 578
 579         /* Next we want to find the permitted name for the remote user.  */
 580         if (*p == ' ' || *p == '\t') {
 581             /* <nul> terminate hostname and skip spaces */
 582             for (*p++='\0'; *p && isspace (*p); ++p);
 583
 584             user = p;                   /* this is the user's name */
 585             while (*p && !isspace (*p))
 586                 ++p;                    /* find end of user's name */
 587         } else
 588             user = p;
 589
 590         *p = '\0';              /* <nul> terminate username (+host?) */
 591
 592         /* buf -> host(?) ; user -> username(?) */
 593
 594         /* First check host part */
 595         hcheck = __icheckhost (raddr, buf, rhost);
 596
 597         if (hcheck < 0)
 598             return -1;
 599
 600         if (hcheck) {
 601             /* Then check user part */
 602             if (! (*user))
 603                 user = luser;
 604
 605             ucheck = __icheckuser (user, ruser);
 606
 607             /* Positive 'host user' match? */
 608             if (ucheck > 0)
 609                 return 0;
 610
 611             /* Negative 'host -user' match? */
 612             if (ucheck < 0)
 613                 return -1;
 614
 615             /* Neither, go on looking for match */
 616         }
 617     }
 618
 619     return -1;
 620 }