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
  54
  55 int __ivaliduser __P ((FILE *, u_int32_t, const char *, const char *));
  56 static int __ivaliduser2 __P ((FILE *, u_int32_t, const char *, const char *,
  57                                const char *));
  58
  59
  60 int
  61 rcmd(ahost, rport, locuser, remuser, cmd, fd2p)
  62         char **ahost;
  63         u_short rport;
  64         const char *locuser, *remuser, *cmd;
  65         int *fd2p;
  66 {
  67         struct hostent hostbuf, *hp;
  68         size_t hstbuflen;
  69         char *tmphstbuf;
  70         struct sockaddr_in sin, from;
  71         struct pollfd pfd[2];
  72         int32_t oldmask;
  73         pid_t pid;
  74         int s, lport, timo;
  75         char c;
  76         int herr;
  77
  78         pid = __getpid();
  79
  80         hstbuflen = 1024;
  81         tmphstbuf = __alloca (hstbuflen);
  82         while (__gethostbyname_r (*ahost, &hostbuf, tmphstbuf, hstbuflen,
  83                                   &hp, &herr) != 0
  84                || hp == NULL)
  85           if (herr != NETDB_INTERNAL || errno != ERANGE)
  86             {
  87               __set_h_errno (herr);
  88               herror(*ahost);
  89               return -1;
  90             }
  91           else
  92             {
  93               /* Enlarge the buffer.  */
  94               hstbuflen *= 2;
  95               tmphstbuf = __alloca (hstbuflen);
  96             }
  97
  98         pfd[0].events = POLLIN;
  99         pfd[1].events = POLLIN;
 100
 101         *ahost = hp->h_name;
 102         oldmask = __sigblock(sigmask(SIGURG));
 103         for (timo = 1, lport = IPPORT_RESERVED - 1;;) {
 104                 s = rresvport(&lport);
 105                 if (s < 0) {
 106                         if (errno == EAGAIN)
 107                                 (void)fprintf(stderr,
 108                                     _("rcmd: socket: All ports in use\n"));
 109                         else
 110                                 (void)fprintf(stderr, "rcmd: socket: %m\n");
 111                         __sigsetmask(oldmask);
 112                         return -1;
 113                 }
 114                 __fcntl(s, F_SETOWN, pid);
 115                 sin.sin_family = hp->h_addrtype;
 116                 bcopy(hp->h_addr_list[0], &sin.sin_addr,
 117                       MIN (sizeof (sin.sin_addr), hp->h_length));
 118                 sin.sin_port = rport;
 119                 if (__connect(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
 120                         break;
 121                 (void)__close(s);
 122                 if (errno == EADDRINUSE) {
 123                         lport--;
 124                         continue;
 125                 }
 126                 if (errno == ECONNREFUSED && timo <= 16) {
 127                         (void)__sleep(timo);
 128                         timo *= 2;
 129                         continue;
 130                 }
 131                 if (hp->h_addr_list[1] != NULL) {
 132                         int oerrno = errno;
 133
 134                         (void)fprintf(stderr, _("connect to address %s: "),
 135                             inet_ntoa(sin.sin_addr));
 136                         __set_errno (oerrno);
 137                         perror(0);
 138                         hp->h_addr_list++;
 139                         bcopy(hp->h_addr_list[0], &sin.sin_addr,
 140                               MIN (sizeof (sin.sin_addr), hp->h_length));
 141                         (void)fprintf(stderr, _("Trying %s...\n"),
 142                             inet_ntoa(sin.sin_addr));
 143                         continue;
 144                 }
 145                 (void)fprintf(stderr, "%s: %m\n", hp->h_name);
 146                 __sigsetmask(oldmask);
 147                 return -1;
 148         }
 149         lport--;
 150         if (fd2p == 0) {
 151                 __write(s, "", 1);
 152                 lport = 0;
 153         } else {
 154                 char num[8];
 155                 int s2 = rresvport(&lport), s3;
 156                 size_t len = sizeof(from);
 157
 158                 if (s2 < 0)
 159                         goto bad;
 160                 listen(s2, 1);
 161                 (void)__snprintf(num, sizeof(num), "%d", lport);
 162                 if (__write(s, num, strlen(num)+1) != strlen(num)+1) {
 163                         (void)fprintf(stderr,
 164                             _("rcmd: write (setting up stderr): %m\n"));
 165                         (void)__close(s2);
 166                         goto bad;
 167                 }
 168                 pfd[0].fd = s;
 169                 pfd[1].fd = s2;
 170                 __set_errno (0);
 171                 if (__poll (pfd, 2, -1) < 1 || (pfd[1].revents & POLLIN) == 0){
 172                         if (errno != 0)
 173                                 (void)fprintf(stderr,
 174                                   _("rcmd: poll (setting up stderr): %m\n"));
 175                         else
 176                                 (void)fprintf(stderr,
 177                              _("poll: protocol failure in circuit setup\n"));
 178                         (void)__close(s2);
 179                         goto bad;
 180                 }
 181                 s3 = accept(s2, (struct sockaddr *)&from, &len);
 182                 (void)__close(s2);
 183                 if (s3 < 0) {
 184                         (void)fprintf(stderr,
 185                             "rcmd: accept: %m\n");
 186                         lport = 0;
 187                         goto bad;
 188                 }
 189                 *fd2p = s3;
 190                 from.sin_port = ntohs((u_short)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: %m\n", *ahost);
 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         sin.sin_family = AF_INET;
 234         sin.sin_addr.s_addr = INADDR_ANY;
 235         s = __socket(AF_INET, SOCK_STREAM, 0);
 236         if (s < 0)
 237                 return -1;
 238         for (;;) {
 239                 sin.sin_port = htons((u_short)*alport);
 240                 if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) >= 0)
 241                         return s;
 242                 if (errno != EADDRINUSE) {
 243                         (void)__close(s);
 244                         return -1;
 245                 }
 246                 (*alport)--;
 247                 if (*alport == IPPORT_RESERVED/2) {
 248                         (void)__close(s);
 249                         __set_errno (EAGAIN);           /* close */
 250                         return -1;
 251                 }
 252         }
 253 }
 254
 255 int     __check_rhosts_file = 1;
 256 char    *__rcmd_errstr;
 257
 258 int
 259 ruserok(rhost, superuser, ruser, luser)
 260         const char *rhost, *ruser, *luser;
 261         int superuser;
 262 {
 263         struct hostent hostbuf, *hp;
 264         size_t buflen;
 265         char *buffer;
 266         u_int32_t addr;
 267         char **ap;
 268         int herr;
 269
 270         buflen = 1024;
 271         buffer = __alloca (buflen);
 272
 273         while (__gethostbyname_r (rhost, &hostbuf, buffer, buflen, &hp, &herr)
 274                != 0
 275                || hp == NULL)
 276           if (herr != NETDB_INTERNAL || errno != ERANGE)
 277             return -1;
 278           else
 279             {
 280               /* Enlarge the buffer.  */
 281               buflen *= 2;
 282               buffer = __alloca (buflen);
 283             }
 284
 285         for (ap = hp->h_addr_list; *ap; ++ap) {
 286                 bcopy(*ap, &addr, sizeof(addr));
 287                 if (iruserok(addr, superuser, ruser, luser, rhost) == 0)
 288                         return 0;
 289         }
 290         return -1;
 291 }
 292
 293 /* Extremely paranoid file open function. */
 294 static FILE *
 295 iruserfopen (char *file, uid_t okuser)
 296 {
 297   struct stat st;
 298   char *cp = NULL;
 299   FILE *res = NULL;
 300
 301   /* If not a regular file, if owned by someone other than user or
 302      root, if writeable by anyone but the owner, or if hardlinked
 303      anywhere, quit.  */
 304   cp = NULL;
 305   if (__lxstat (_STAT_VER, file, &st))
 306     cp = _("lstat failed");
 307   else if (!S_ISREG (st.st_mode))
 308     cp = _("not regular file");
 309   else
 310     {
 311       res = fopen (file, "r");
 312       if (!res)
 313         cp = _("cannot open");
 314       else if (__fxstat (_STAT_VER, fileno (res), &st) < 0)
 315         cp = _("fstat failed");
 316       else if (st.st_uid && st.st_uid != okuser)
 317         cp = _("bad owner");
 318       else if (st.st_mode & (S_IWGRP|S_IWOTH))
 319         cp = _("writeable by other than owner");
 320       else if (st.st_nlink > 1)
 321         cp = _("hard linked somewhere");
 322     }
 323
 324   /* If there were any problems, quit.  */
 325   if (cp != NULL)
 326     {
 327       __rcmd_errstr = cp;
 328       if (res)
 329         fclose (res);
 330       return NULL;
 331     }
 332
 333   return res;
 334 }
 335
 336 /*
 337  * New .rhosts strategy: We are passed an ip address. We spin through
 338  * hosts.equiv and .rhosts looking for a match. When the .rhosts only
 339  * has ip addresses, we don't have to trust a nameserver.  When it
 340  * contains hostnames, we spin through the list of addresses the nameserver
 341  * gives us and look for a match.
 342  *
 343  * Returns 0 if ok, -1 if not ok.
 344  */
 345 static int
 346 iruserok2 (raddr, superuser, ruser, luser, rhost)
 347      u_int32_t raddr;
 348      int superuser;
 349      const char *ruser, *luser, *rhost;
 350 {
 351   FILE *hostf = NULL;
 352   int isbad = -1;
 353
 354   if (!superuser)
 355     hostf = iruserfopen (_PATH_HEQUIV, 0);
 356
 357   if (hostf)
 358     {
 359       isbad = __ivaliduser2 (hostf, raddr, luser, ruser, rhost);
 360       fclose (hostf);
 361
 362       if (!isbad)
 363         return 0;
 364     }
 365
 366   if (__check_rhosts_file || superuser)
 367     {
 368       char *pbuf;
 369       struct passwd pwdbuf, *pwd;
 370       size_t dirlen;
 371       size_t buflen = __sysconf (_SC_GETPW_R_SIZE_MAX);
 372       char *buffer = __alloca (buflen);
 373       uid_t uid;
 374
 375       if (__getpwnam_r (luser, &pwdbuf, buffer, buflen, &pwd) != 0
 376           || pwd == NULL)
 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     int retval = -1;
 557
 558     while (__getline (&buf, &bufsize, hostf) > 0) {
 559         buf[bufsize - 1] = '\0'; /* Make sure it's terminated.  */
 560         p = buf;
 561
 562         /* Skip empty or comment lines */
 563         if (__isempty (p)) {
 564             continue;
 565         }
 566
 567         /* Skip lines that are too long. */
 568         if (strchr (p, '\n') == NULL) {
 569             int ch = getc_unlocked (hostf);
 570
 571             while (ch != '\n' && ch != EOF)
 572                 ch = getc_unlocked (hostf);
 573             continue;
 574         }
 575
 576         for (;*p && !isspace(*p); ++p) {
 577             *p = _tolower (*p);
 578         }
 579
 580         /* Next we want to find the permitted name for the remote user.  */
 581         if (*p == ' ' || *p == '\t') {
 582             /* <nul> terminate hostname and skip spaces */
 583             for (*p++='\0'; *p && isspace (*p); ++p);
 584
 585             user = p;                   /* this is the user's name */
 586             while (*p && !isspace (*p))
 587                 ++p;                    /* find end of user's name */
 588         } else
 589             user = p;
 590
 591         *p = '\0';              /* <nul> terminate username (+host?) */
 592
 593         /* buf -> host(?) ; user -> username(?) */
 594
 595         /* First check host part */
 596         hcheck = __icheckhost (raddr, buf, rhost);
 597
 598         if (hcheck < 0)
 599             break;
 600
 601         if (hcheck) {
 602             /* Then check user part */
 603             if (! (*user))
 604                 user = luser;
 605
 606             ucheck = __icheckuser (user, ruser);
 607
 608             /* Positive 'host user' match? */
 609             if (ucheck > 0) {
 610                 retval = 0;
 611                 break;
 612             }
 613
 614             /* Negative 'host -user' match? */
 615             if (ucheck < 0)
 616                 break;
 617
 618             /* Neither, go on looking for match */
 619         }
 620     }
 621
 622     if (buf != NULL)
 623       free (buf);
 624
 625     return retval;
 626 }