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 __icheckhost __P((u_int32_t, char *)) internal_function;
  60
  61 int
  62 rcmd(ahost, rport, locuser, remuser, cmd, fd2p)
  63         char **ahost;
  64         u_short rport;
  65         const char *locuser, *remuser, *cmd;
  66         int *fd2p;
  67 {
  68         struct hostent hostbuf, *hp;
  69         size_t hstbuflen;
  70         char *tmphstbuf;
  71         struct sockaddr_in sin, from;
  72         struct pollfd pfd[2];
  73         int32_t oldmask;
  74         pid_t pid;
  75         int s, lport, timo;
  76         char c;
  77         int herr;
  78
  79         pid = getpid();
  80
  81         hstbuflen = 1024;
  82         tmphstbuf = __alloca (hstbuflen);
  83         while (__gethostbyname_r (*ahost, &hostbuf, tmphstbuf, hstbuflen,
  84                                   &hp, &herr) < 0)
  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           if (herr != NETDB_INTERNAL || errno != ERANGE)
 276             return -1;
 277           else
 278             {
 279               /* Enlarge the buffer.  */
 280               buflen *= 2;
 281               buffer = __alloca (buflen);
 282             }
 283
 284         for (ap = hp->h_addr_list; *ap; ++ap) {
 285                 bcopy(*ap, &addr, sizeof(addr));
 286                 if (iruserok(addr, superuser, ruser, luser) == 0)
 287                         return 0;
 288         }
 289         return -1;
 290 }
 291
 292 /* Extremely paranoid file open function. */
 293 static FILE *
 294 iruserfopen (char *file, uid_t okuser)
 295 {
 296   struct stat st;
 297   char *cp = NULL;
 298   FILE *res = NULL;
 299
 300   /* If not a regular file, if owned by someone other than user or
 301      root, if writeable by anyone but the owner, or if hardlinked
 302      anywhere, quit.  */
 303   cp = NULL;
 304   if (__lxstat (_STAT_VER, file, &st))
 305     cp = _("lstat failed");
 306   else if (!S_ISREG (st.st_mode))
 307     cp = _("not regular file");
 308   else
 309     {
 310       res = fopen (file, "r");
 311       if (!res)
 312         cp = _("cannot open");
 313       else if (__fxstat (_STAT_VER, fileno (res), &st) < 0)
 314         cp = _("fstat failed");
 315       else if (st.st_uid && st.st_uid != okuser)
 316         cp = _("bad owner");
 317       else if (st.st_mode & (S_IWGRP|S_IWOTH))
 318         cp = _("writeable by other than owner");
 319       else if (st.st_nlink > 1)
 320         cp = _("hard linked somewhere");
 321     }
 322
 323   /* If there were any problems, quit.  */
 324   if (cp != NULL)
 325     {
 326       __rcmd_errstr = cp;
 327       if (res)
 328         fclose (res);
 329       return NULL;
 330     }
 331
 332   return res;
 333 }
 334
 335 /*
 336  * New .rhosts strategy: We are passed an ip address. We spin through
 337  * hosts.equiv and .rhosts looking for a match. When the .rhosts only
 338  * has ip addresses, we don't have to trust a nameserver.  When it
 339  * contains hostnames, we spin through the list of addresses the nameserver
 340  * gives us and look for a match.
 341  *
 342  * Returns 0 if ok, -1 if not ok.
 343  */
 344 int
 345 iruserok (raddr, superuser, ruser, luser)
 346      u_int32_t raddr;
 347      int superuser;
 348      const char *ruser, *luser;
 349 {
 350   FILE *hostf = NULL;
 351   int isbad;
 352
 353   if (!superuser)
 354     hostf = iruserfopen (_PATH_HEQUIV, 0);
 355
 356   if (hostf)
 357     {
 358       isbad = __ivaliduser (hostf, raddr, luser, ruser);
 359       fclose (hostf);
 360
 361       if (!isbad)
 362         return 0;
 363     }
 364
 365   if (__check_rhosts_file || superuser)
 366     {
 367       char *pbuf;
 368       struct passwd pwdbuf, *pwd;
 369       size_t dirlen;
 370       size_t buflen = __sysconf (_SC_GETPW_R_SIZE_MAX);
 371       char *buffer = __alloca (buflen);
 372       uid_t uid;
 373
 374       if (__getpwnam_r (luser, &pwdbuf, buffer, buflen, &pwd))
 375         return -1;
 376
 377       dirlen = strlen (pwd->pw_dir);
 378       pbuf = alloca (dirlen + sizeof "/.rhosts");
 379       __mempcpy (__mempcpy (pbuf, pwd->pw_dir, dirlen),
 380                  "/.rhosts", sizeof "/.rhosts");
 381
 382        /* Change effective uid while reading .rhosts.  If root and
 383           reading an NFS mounted file system, can't read files that
 384           are protected read/write owner only.  */
 385        uid = geteuid ();
 386        seteuid (pwd->pw_uid);
 387        hostf = iruserfopen (pbuf, pwd->pw_uid);
 388
 389        if (hostf != NULL)
 390          {
 391            isbad = __ivaliduser (hostf, raddr, luser, ruser);
 392            fclose (hostf);
 393          }
 394
 395        seteuid (uid);
 396        return isbad;
 397     }
 398   return -1;
 399 }
 400
 401 /*
 402  * XXX
 403  * Don't make static, used by lpd(8).
 404  *
 405  * Returns 0 if ok, -1 if not ok.
 406  */
 407 int
 408 __ivaliduser(hostf, raddr, luser, ruser)
 409         FILE *hostf;
 410         u_int32_t raddr;
 411         const char *luser, *ruser;
 412 {
 413         register char *user, *p;
 414         int ch;
 415         char *buf = NULL;
 416         size_t bufsize = 0;
 417         ssize_t nread;
 418
 419         while ((nread = __getline (&buf, &bufsize, hostf)) > 0) {
 420                 buf[bufsize - 1] = '\0'; /* Make sure it's terminated.  */
 421                 p = buf;
 422                 while (*p != '\n' && *p != ' ' && *p != '\t' && *p != '\0') {
 423                         *p = isupper(*p) ? tolower(*p) : *p;
 424                         p++;
 425                 }
 426                 if (*p == ' ' || *p == '\t') {
 427                         *p++ = '\0';
 428                         while (*p == ' ' || *p == '\t')
 429                                 p++;
 430                         user = p;
 431                         while (*p != '\n' && *p != ' ' &&
 432                             *p != '\t' && *p != '\0')
 433                                 p++;
 434                 } else
 435                         user = p;
 436                 *p = '\0';
 437                 if (__icheckhost(raddr, buf) &&
 438                     strcmp(ruser, *user ? user : luser) == 0) {
 439                         free (buf);
 440                         return 0;
 441                 }
 442         }
 443         if (buf != NULL)
 444                 free (buf);
 445         return -1;
 446 }
 447
 448 /*
 449  * Returns "true" if match, 0 if no match.
 450  */
 451 static int
 452 internal_function
 453 __icheckhost(raddr, lhost)
 454         u_int32_t raddr;
 455         register char *lhost;
 456 {
 457         struct hostent hostbuf, *hp;
 458         size_t buflen;
 459         char *buffer;
 460         register u_int32_t laddr;
 461         register char **pp;
 462         int herr;
 463
 464         /* Try for raw ip address first. */
 465         if (isdigit(*lhost) && (int32_t)(laddr = inet_addr(lhost)) != -1)
 466                 return raddr == laddr;
 467
 468         /* Better be a hostname. */
 469         buflen = 1024;
 470         buffer = __alloca (buflen);
 471         while (__gethostbyname_r (lhost, &hostbuf, buffer, buflen, &hp, &herr)
 472                < 0)
 473           if (herr != NETDB_INTERNAL || errno != ERANGE)
 474             return 0;
 475           else
 476             {
 477               /* Enlarge the buffer.  */
 478               buflen *= 2;
 479               buffer = __alloca (buflen);
 480             }
 481
 482         /* Spin through ip addresses. */
 483         for (pp = hp->h_addr_list; *pp; ++pp)
 484                 if (!bcmp(&raddr, *pp, sizeof(u_int32_t)))
 485                         return 1;
 486
 487         /* No match. */
 488         return 0;
 489 }