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  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #if defined(LIBC_SCCS) && !defined(lint)
  31 static char sccsid[] = "@(#)rcmd.c      8.3 (Berkeley) 3/26/94";
  32 #endif /* LIBC_SCCS and not lint */
  33
  34 #include <sys/param.h>
  35 #include <sys/poll.h>
  36 #include <sys/socket.h>
  37 #include <sys/stat.h>
  38
  39 #include <netinet/in.h>
  40 #include <arpa/inet.h>
  41
  42 #include <alloca.h>
  43 #include <signal.h>
  44 #include <fcntl.h>
  45 #include <netdb.h>
  46 #include <unistd.h>
  47 #include <pwd.h>
  48 #include <errno.h>
  49 #include <stdio.h>
  50 #include <ctype.h>
  51 #include <string.h>
  52 #include <libintl.h>
  53 #include <stdlib.h>
  54
  55
  56 int __ivaliduser __P ((FILE *, u_int32_t, const char *, const char *));
  57 static int __ivaliduser2 __P ((FILE *, u_int32_t, const char *, const char *,
  58                                const char *));
  59 static int iruserok2 (u_int32_t raddr, int superuser, const char *ruser,
  60                       const char *luser, const char *rhost);
  61 int iruserok (u_int32_t raddr, int superuser, const char *ruser,
  62               const char *luser);
  63
  64
  65 int
  66 rcmd(ahost, rport, locuser, remuser, cmd, fd2p)
  67         char **ahost;
  68         u_short rport;
  69         const char *locuser, *remuser, *cmd;
  70         int *fd2p;
  71 {
  72         struct hostent hostbuf, *hp;
  73         size_t hstbuflen;
  74         char *tmphstbuf;
  75         struct sockaddr_in sin, from;
  76         struct pollfd pfd[2];
  77         int32_t oldmask;
  78         pid_t pid;
  79         int s, lport, timo;
  80         char c;
  81         int herr;
  82
  83         pid = __getpid();
  84
  85         hstbuflen = 1024;
  86         tmphstbuf = __alloca (hstbuflen);
  87         while (__gethostbyname_r (*ahost, &hostbuf, tmphstbuf, hstbuflen,
  88                                   &hp, &herr) != 0
  89                || hp == NULL)
  90           if (herr != NETDB_INTERNAL || errno != ERANGE)
  91             {
  92               __set_h_errno (herr);
  93               herror(*ahost);
  94               return -1;
  95             }
  96           else
  97             {
  98               /* Enlarge the buffer.  */
  99               hstbuflen *= 2;
 100               tmphstbuf = __alloca (hstbuflen);
 101             }
 102
 103         pfd[0].events = POLLIN;
 104         pfd[1].events = POLLIN;
 105
 106         *ahost = hp->h_name;
 107         oldmask = __sigblock(sigmask(SIGURG));
 108         for (timo = 1, lport = IPPORT_RESERVED - 1;;) {
 109                 s = rresvport(&lport);
 110                 if (s < 0) {
 111                         if (errno == EAGAIN)
 112                                 (void)fprintf(stderr,
 113                                     _("rcmd: socket: All ports in use\n"));
 114                         else
 115                                 (void)fprintf(stderr, "rcmd: socket: %m\n");
 116                         __sigsetmask(oldmask);
 117                         return -1;
 118                 }
 119                 __fcntl(s, F_SETOWN, pid);
 120                 sin.sin_family = hp->h_addrtype;
 121                 bcopy(hp->h_addr_list[0], &sin.sin_addr,
 122                       MIN (sizeof (sin.sin_addr), hp->h_length));
 123                 sin.sin_port = rport;
 124                 if (__connect(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
 125                         break;
 126                 (void)__close(s);
 127                 if (errno == EADDRINUSE) {
 128                         lport--;
 129                         continue;
 130                 }
 131                 if (errno == ECONNREFUSED && timo <= 16) {
 132                         (void)__sleep(timo);
 133                         timo *= 2;
 134                         continue;
 135                 }
 136                 if (hp->h_addr_list[1] != NULL) {
 137                         int oerrno = errno;
 138
 139                         (void)fprintf(stderr, _("connect to address %s: "),
 140                             inet_ntoa(sin.sin_addr));
 141                         __set_errno (oerrno);
 142                         perror(0);
 143                         hp->h_addr_list++;
 144                         bcopy(hp->h_addr_list[0], &sin.sin_addr,
 145                               MIN (sizeof (sin.sin_addr), hp->h_length));
 146                         (void)fprintf(stderr, _("Trying %s...\n"),
 147                             inet_ntoa(sin.sin_addr));
 148                         continue;
 149                 }
 150                 (void)fprintf(stderr, "%s: %m\n", hp->h_name);
 151                 __sigsetmask(oldmask);
 152                 return -1;
 153         }
 154         lport--;
 155         if (fd2p == 0) {
 156                 __write(s, "", 1);
 157                 lport = 0;
 158         } else {
 159                 char num[8];
 160                 int s2 = rresvport(&lport), s3;
 161                 size_t len = sizeof(from);
 162
 163                 if (s2 < 0)
 164                         goto bad;
 165                 listen(s2, 1);
 166                 (void)__snprintf(num, sizeof(num), "%d", lport);
 167                 if (__write(s, num, strlen(num)+1) != strlen(num)+1) {
 168                         (void)fprintf(stderr,
 169                             _("rcmd: write (setting up stderr): %m\n"));
 170                         (void)__close(s2);
 171                         goto bad;
 172                 }
 173                 pfd[0].fd = s;
 174                 pfd[1].fd = s2;
 175                 __set_errno (0);
 176                 if (__poll (pfd, 2, -1) < 1 || (pfd[1].revents & POLLIN) == 0){
 177                         if (errno != 0)
 178                                 (void)fprintf(stderr,
 179                                   _("rcmd: poll (setting up stderr): %m\n"));
 180                         else
 181                                 (void)fprintf(stderr,
 182                              _("poll: protocol failure in circuit setup\n"));
 183                         (void)__close(s2);
 184                         goto bad;
 185                 }
 186                 s3 = accept(s2, (struct sockaddr *)&from, &len);
 187                 (void)__close(s2);
 188                 if (s3 < 0) {
 189                         (void)fprintf(stderr,
 190                             "rcmd: accept: %m\n");
 191                         lport = 0;
 192                         goto bad;
 193                 }
 194                 *fd2p = s3;
 195                 from.sin_port = ntohs((u_short)from.sin_port);
 196                 if (from.sin_family != AF_INET ||
 197                     from.sin_port >= IPPORT_RESERVED ||
 198                     from.sin_port < IPPORT_RESERVED / 2) {
 199                         (void)fprintf(stderr,
 200                             _("socket: protocol failure in circuit setup\n"));
 201                         goto bad2;
 202                 }
 203         }
 204         (void)__write(s, locuser, strlen(locuser)+1);
 205         (void)__write(s, remuser, strlen(remuser)+1);
 206         (void)__write(s, cmd, strlen(cmd)+1);
 207         if (__read(s, &c, 1) != 1) {
 208                 (void)fprintf(stderr,
 209                     "rcmd: %s: %m\n", *ahost);
 210                 goto bad2;
 211         }
 212         if (c != 0) {
 213                 while (__read(s, &c, 1) == 1) {
 214                         (void)__write(STDERR_FILENO, &c, 1);
 215                         if (c == '\n')
 216                                 break;
 217                 }
 218                 goto bad2;
 219         }
 220         __sigsetmask(oldmask);
 221         return s;
 222 bad2:
 223         if (lport)
 224                 (void)__close(*fd2p);
 225 bad:
 226         (void)__close(s);
 227         __sigsetmask(oldmask);
 228         return -1;
 229 }
 230
 231 int
 232 rresvport(alport)
 233         int *alport;
 234 {
 235         struct sockaddr_in sin;
 236         int s;
 237
 238         sin.sin_family = AF_INET;
 239         sin.sin_addr.s_addr = INADDR_ANY;
 240         s = __socket(AF_INET, SOCK_STREAM, 0);
 241         if (s < 0)
 242                 return -1;
 243         for (;;) {
 244                 sin.sin_port = htons((u_short)*alport);
 245                 if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
 246                         return s;
 247                 if (errno != EADDRINUSE) {
 248                         (void)__close(s);
 249                         return -1;
 250                 }
 251                 (*alport)--;
 252                 if (*alport == IPPORT_RESERVED/2) {
 253                         (void)__close(s);
 254                         __set_errno (EAGAIN);           /* close */
 255                         return -1;
 256                 }
 257         }
 258 }
 259
 260 int     __check_rhosts_file = 1;
 261 char    *__rcmd_errstr;
 262
 263 int
 264 ruserok(rhost, superuser, ruser, luser)
 265         const char *rhost, *ruser, *luser;
 266         int superuser;
 267 {
 268         struct hostent hostbuf, *hp;
 269         size_t buflen;
 270         char *buffer;
 271         u_int32_t addr;
 272         char **ap;
 273         int herr;
 274
 275         buflen = 1024;
 276         buffer = __alloca (buflen);
 277
 278         while (__gethostbyname_r (rhost, &hostbuf, buffer, buflen, &hp, &herr)
 279                != 0
 280                || hp == NULL)
 281           if (herr != NETDB_INTERNAL || errno != ERANGE)
 282             return -1;
 283           else
 284             {
 285               /* Enlarge the buffer.  */
 286               buflen *= 2;
 287               buffer = __alloca (buflen);
 288             }
 289
 290         for (ap = hp->h_addr_list; *ap; ++ap) {
 291                 bcopy(*ap, &addr, sizeof(addr));
 292                 if (iruserok2(addr, superuser, ruser, luser, rhost) == 0)
 293                         return 0;
 294         }
 295         return -1;
 296 }
 297
 298 /* Extremely paranoid file open function. */
 299 static FILE *
 300 iruserfopen (char *file, uid_t okuser)
 301 {
 302   struct stat st;
 303   char *cp = NULL;
 304   FILE *res = NULL;
 305
 306   /* If not a regular file, if owned by someone other than user or
 307      root, if writeable by anyone but the owner, or if hardlinked
 308      anywhere, quit.  */
 309   cp = NULL;
 310   if (__lxstat (_STAT_VER, file, &st))
 311     cp = _("lstat failed");
 312   else if (!S_ISREG (st.st_mode))
 313     cp = _("not regular file");
 314   else
 315     {
 316       res = fopen (file, "r");
 317       if (!res)
 318         cp = _("cannot open");
 319       else if (__fxstat (_STAT_VER, fileno (res), &st) < 0)
 320         cp = _("fstat failed");
 321       else if (st.st_uid && st.st_uid != okuser)
 322         cp = _("bad owner");
 323       else if (st.st_mode & (S_IWGRP|S_IWOTH))
 324         cp = _("writeable by other than owner");
 325       else if (st.st_nlink > 1)
 326         cp = _("hard linked somewhere");
 327     }
 328
 329   /* If there were any problems, quit.  */
 330   if (cp != NULL)
 331     {
 332       __rcmd_errstr = cp;
 333       if (res)
 334         fclose (res);
 335       return NULL;
 336     }
 337
 338   return res;
 339 }
 340
 341 /*
 342  * New .rhosts strategy: We are passed an ip address. We spin through
 343  * hosts.equiv and .rhosts looking for a match. When the .rhosts only
 344  * has ip addresses, we don't have to trust a nameserver.  When it
 345  * contains hostnames, we spin through the list of addresses the nameserver
 346  * gives us and look for a match.
 347  *
 348  * Returns 0 if ok, -1 if not ok.
 349  */
 350 static int
 351 iruserok2 (raddr, superuser, ruser, luser, rhost)
 352      u_int32_t raddr;
 353      int superuser;
 354      const char *ruser, *luser, *rhost;
 355 {
 356   FILE *hostf = NULL;
 357   int isbad = -1;
 358
 359   if (!superuser)
 360     hostf = iruserfopen (_PATH_HEQUIV, 0);
 361
 362   if (hostf)
 363     {
 364       isbad = __ivaliduser2 (hostf, raddr, luser, ruser, rhost);
 365       fclose (hostf);
 366
 367       if (!isbad)
 368         return 0;
 369     }
 370
 371   if (__check_rhosts_file || superuser)
 372     {
 373       char *pbuf;
 374       struct passwd pwdbuf, *pwd;
 375       size_t dirlen;
 376       size_t buflen = __sysconf (_SC_GETPW_R_SIZE_MAX);
 377       char *buffer = __alloca (buflen);
 378       uid_t uid;
 379
 380       if (__getpwnam_r (luser, &pwdbuf, buffer, buflen, &pwd) != 0
 381           || pwd == NULL)
 382         return -1;
 383
 384       dirlen = strlen (pwd->pw_dir);
 385       pbuf = alloca (dirlen + sizeof "/.rhosts");
 386       __mempcpy (__mempcpy (pbuf, pwd->pw_dir, dirlen),
 387                  "/.rhosts", sizeof "/.rhosts");
 388
 389        /* Change effective uid while reading .rhosts.  If root and
 390           reading an NFS mounted file system, can't read files that
 391           are protected read/write owner only.  */
 392        uid = __geteuid ();
 393        seteuid (pwd->pw_uid);
 394        hostf = iruserfopen (pbuf, pwd->pw_uid);
 395
 396        if (hostf != NULL)
 397          {
 398            isbad = __ivaliduser2 (hostf, raddr, luser, ruser, rhost);
 399            fclose (hostf);
 400          }
 401
 402        seteuid (uid);
 403        return isbad;
 404     }
 405   return -1;
 406 }
 407
 408 /* This is the exported version.  */
 409 int
 410 iruserok (raddr, superuser, ruser, luser)
 411      u_int32_t raddr;
 412      int superuser;
 413      const char *ruser, *luser;
 414 {
 415   return iruserok2 (raddr, superuser, ruser, luser, "-");
 416 }
 417
 418 /*
 419  * XXX
 420  * Don't make static, used by lpd(8).
 421  *
 422  * This function is not used anymore. It is only present because lpd(8)
 423  * calls it (!?!). We simply call __invaliduser2() with an illegal rhost
 424  * argument. This means that netgroups won't work in .rhost/hosts.equiv
 425  * files. If you want lpd to work with netgroups, fix lpd to use ruserok()
 426  * or PAM.
 427  * Returns 0 if ok, -1 if not ok.
 428  */
 429 int
 430 __ivaliduser(hostf, raddr, luser, ruser)
 431         FILE *hostf;
 432         u_int32_t raddr;
 433         const char *luser, *ruser;
 434 {
 435         return __ivaliduser2(hostf, raddr, luser, ruser, "-");
 436 }
 437
 438
 439 /* Returns 1 on positive match, 0 on no match, -1 on negative match.  */
 440 static int
 441 internal_function
 442 __icheckhost (raddr, lhost, rhost)
 443         u_int32_t raddr;
 444         char *lhost;
 445         const char *rhost;
 446 {
 447         struct hostent hostbuf, *hp;
 448         size_t buflen;
 449         char *buffer;
 450         int herr;
 451         int save_errno;
 452         u_int32_t laddr;
 453         int negate=1;    /* Multiply return with this to get -1 instead of 1 */
 454         char **pp, *user;
 455
 456         /* Check nis netgroup.  */
 457         if (strncmp ("+@", lhost, 2) == 0)
 458                 return innetgr (&lhost[2], rhost, NULL, NULL);
 459
 460         if (strncmp ("-@", lhost, 2) == 0)
 461                 return -innetgr (&lhost[2], rhost, NULL, NULL);
 462
 463         /* -host */
 464         if (strncmp ("-", lhost,1) == 0) {
 465                 negate = -1;
 466                 lhost++;
 467         } else if (strcmp ("+",lhost) == 0) {
 468                 return 1;                    /* asking for trouble, but ok.. */
 469         }
 470
 471         /* Try for raw ip address first. */
 472         if (isdigit (*lhost) && (long) (laddr = inet_addr (lhost)) != -1)
 473                 return negate * (! (raddr ^ laddr));
 474
 475         /* Better be a hostname. */
 476         buflen = 1024;
 477         buffer = __alloca (buflen);
 478         save_errno = errno;
 479         while (__gethostbyname_r (lhost, &hostbuf, buffer, buflen, &hp, &herr)
 480                != 0)
 481                 if (herr != NETDB_INTERNAL || errno != ERANGE)
 482                         return (0);
 483                 else {
 484                         /* Enlarge the buffer.  */
 485                         buflen *= 2;
 486                         buffer = __alloca (buflen);
 487                         __set_errno (0);
 488                 }
 489         __set_errno (save_errno);
 490         if (hp == NULL)
 491                 return 0;
 492
 493         /* Spin through ip addresses. */
 494         for (pp = hp->h_addr_list; *pp; ++pp)
 495                 if (!memcmp (&raddr, *pp, sizeof (u_int32_t)))
 496                         return negate;
 497
 498         /* No match. */
 499         return (0);
 500 }
 501
 502 /* Returns 1 on positive match, 0 on no match, -1 on negative match.  */
 503 static int
 504 internal_function
 505 __icheckuser (luser, ruser)
 506         const char *luser, *ruser;
 507 {
 508     /*
 509       luser is user entry from .rhosts/hosts.equiv file
 510       ruser is user id on remote host
 511       */
 512     char *user;
 513
 514     /* [-+]@netgroup */
 515     if (strncmp ("+@", luser, 2) == 0)
 516         return innetgr (&luser[2], NULL, ruser, NULL);
 517
 518     if (strncmp ("-@", luser,2) == 0)
 519         return -innetgr (&luser[2], NULL, ruser, NULL);
 520
 521     /* -user */
 522     if (strncmp ("-", luser, 1) == 0)
 523         return -(strcmp (&luser[1], ruser) == 0);
 524
 525     /* + */
 526     if (strcmp ("+", luser) == 0)
 527         return 1;
 528
 529     /* simple string match */
 530     return strcmp (ruser, luser) == 0;
 531 }
 532
 533 /*
 534  * Returns 1 for blank lines (or only comment lines) and 0 otherwise
 535  */
 536 static int
 537 __isempty(p)
 538         char *p;
 539 {
 540     while (*p && isspace (*p)) {
 541         ++p;
 542     }
 543
 544     return (*p == '\0' || *p == '#') ? 1 : 0 ;
 545 }
 546
 547 /*
 548  * Returns 0 if positive match, -1 if _not_ ok.
 549  */
 550 static int
 551 __ivaliduser2(hostf, raddr, luser, ruser, rhost)
 552         FILE *hostf;
 553         u_int32_t raddr;
 554         const char *luser, *ruser, *rhost;
 555 {
 556     register const char *user;
 557     register char *p;
 558     int hcheck, ucheck;
 559     char *buf = NULL;
 560     size_t bufsize = 0;
 561     int retval = -1;
 562
 563     while (__getline (&buf, &bufsize, hostf) > 0) {
 564         buf[bufsize - 1] = '\0'; /* Make sure it's terminated.  */
 565         p = buf;
 566
 567         /* Skip empty or comment lines */
 568         if (__isempty (p)) {
 569             continue;
 570         }
 571
 572         /* Skip lines that are too long. */
 573         if (strchr (p, '\n') == NULL) {
 574             int ch = getc_unlocked (hostf);
 575
 576             while (ch != '\n' && ch != EOF)
 577                 ch = getc_unlocked (hostf);
 578             continue;
 579         }
 580
 581         for (;*p && !isspace(*p); ++p) {
 582             *p = _tolower (*p);
 583         }
 584
 585         /* Next we want to find the permitted name for the remote user.  */
 586         if (*p == ' ' || *p == '\t') {
 587             /* <nul> terminate hostname and skip spaces */
 588             for (*p++='\0'; *p && isspace (*p); ++p);
 589
 590             user = p;                   /* this is the user's name */
 591             while (*p && !isspace (*p))
 592                 ++p;                    /* find end of user's name */
 593         } else
 594             user = p;
 595
 596         *p = '\0';              /* <nul> terminate username (+host?) */
 597
 598         /* buf -> host(?) ; user -> username(?) */
 599
 600         /* First check host part */
 601         hcheck = __icheckhost (raddr, buf, rhost);
 602
 603         if (hcheck < 0)
 604             break;
 605
 606         if (hcheck) {
 607             /* Then check user part */
 608             if (! (*user))
 609                 user = luser;
 610
 611             ucheck = __icheckuser (user, ruser);
 612
 613             /* Positive 'host user' match? */
 614             if (ucheck > 0) {
 615                 retval = 0;
 616                 break;
 617             }
 618
 619             /* Negative 'host -user' match? */
 620             if (ucheck < 0)
 621                 break;
 622
 623             /* Neither, go on looking for match */
 624         }
 625     }
 626
 627     if (buf != NULL)
 628       free (buf);
 629
 630     return retval;
 631 }