usr.bin/rsh/rsh.c

   1 /*      $NetBSD: rsh.c,v 1.38 2014/11/26 23:44:21 enami Exp $   */
   2
   3 /*-
   4  * Copyright (c) 1983, 1990, 1993, 1994
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #ifndef lint
  34 __COPYRIGHT("@(#) Copyright (c) 1983, 1990, 1993, 1994\
  35  The Regents of the University of California.  All rights reserved.");
  36 #endif /* not lint */
  37
  38 #ifndef lint
  39 #if 0
  40 static char sccsid[] = "@(#)rsh.c       8.4 (Berkeley) 4/29/95";
  41 #else
  42 __RCSID("$NetBSD: rsh.c,v 1.38 2014/11/26 23:44:21 enami Exp $");
  43 #endif
  44 #endif /* not lint */
  45
  46 #include <sys/types.h>
  47 #include <sys/socket.h>
  48 #include <sys/ioctl.h>
  49 #include <sys/file.h>
  50 #include <poll.h>
  51
  52 #include <netinet/in.h>
  53 #include <netinet/tcp.h>
  54 #include <netdb.h>
  55
  56 #include <err.h>
  57 #include <errno.h>
  58 #include <limits.h>
  59 #include <pwd.h>
  60 #include <signal.h>
  61 #include <stdarg.h>
  62 #include <stdio.h>
  63 #include <stdlib.h>
  64 #include <string.h>
  65 #include <unistd.h>
  66
  67 #include "pathnames.h"
  68 #include "getport.h"
  69
  70
  71 /*
  72  * rsh - remote shell
  73  */
  74 int     remerr;
  75
  76 static int sigs[] = { SIGINT, SIGTERM, SIGQUIT };
  77
  78 static char   *copyargs(char **);
  79 static void     sendsig(int);
  80 static int      checkfd(struct pollfd *, int);
  81 static void     talk(int, sigset_t *, pid_t, int);
  82 __dead static void      usage(void);
  83 #ifdef IN_RCMD
  84 int      orcmd(char **, int, const char *,
  85     const char *, const char *, int *);
  86 int      orcmd_af(char **, int, const char *,
  87     const char *, const char *, int *, int);
  88 static int      relay_signal;
  89 #endif
  90
  91 int
  92 main(int argc, char **argv)
  93 {
  94         struct passwd *pw;
  95         struct servent *sp;
  96         sigset_t oset, nset;
  97         struct protoent *proto;
  98
  99 #ifdef IN_RCMD
 100         char    *locuser = 0, *loop, *relay;
 101 #endif /* IN_RCMD */
 102         int argoff, asrsh, ch, dflag, nflag, one, rem;
 103         size_t i;
 104         int family = AF_UNSPEC;
 105         pid_t pid;
 106         uid_t uid;
 107         char *args, *host, *p, *user, *name;
 108
 109         argoff = asrsh = dflag = nflag = 0;
 110         one = 1;
 111         host = user = NULL;
 112         sp = NULL;
 113
 114 #ifndef IN_RCMD
 115         /*
 116          * If called as something other than "rsh" use it as the host name,
 117          * only for rsh.
 118          */
 119         if (strcmp(getprogname(), "rsh") == 0)
 120                 asrsh = 1;
 121         else {
 122                 host = strdup(getprogname());
 123                 if (host == NULL)
 124                         err(1, NULL);
 125         }
 126 #endif /* IN_RCMD */
 127
 128         /* handle "rsh host flags" */
 129         if (!host && argc > 2 && argv[1][0] != '-') {
 130                 host = argv[1];
 131                 argoff = 1;
 132         }
 133
 134 #ifdef IN_RCMD
 135         if ((relay = getenv("RCMD_RELAY_SIGNAL")) && strcmp(relay, "YES") == 0)
 136                 relay_signal = 1;
 137         if ((loop = getenv("RCMD_LOOP")) && strcmp(loop, "YES") == 0)
 138                 warnx("rcmd appears to be looping!");
 139
 140         setenv("RCMD_LOOP", "YES", 1);
 141
 142 #  define       OPTIONS "468KLdel:np:u:w"
 143
 144 #else /* IN_RCMD */
 145
 146 #  define       OPTIONS "468KLdel:np:w"
 147
 148 #endif /* IN_RCMD */
 149
 150         if (!(pw = getpwuid(uid = getuid())))
 151                 errx(1, "unknown user id");
 152
 153         if ((name = strdup(pw->pw_name)) == NULL)
 154                 err(1, "malloc");
 155         while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
 156                 switch (ch) {
 157                 case '4':
 158                         family = AF_INET;
 159                         break;
 160                 case '6':
 161                         family = AF_INET6;
 162                         break;
 163                 case 'K':
 164                         break;
 165                 case 'L':       /* -8Lew are ignored to allow rlogin aliases */
 166                 case 'e':
 167                 case 'w':
 168                 case '8':
 169                         break;
 170                 case 'd':
 171                         dflag = 1;
 172                         break;
 173                 case 'l':
 174                         user = optarg;
 175                         break;
 176                 case 'n':
 177                         nflag = 1;
 178                         break;
 179                 case 'p':
 180                         sp = getport(optarg, "tcp");
 181                         break;
 182 #ifdef IN_RCMD
 183                 case 'u':
 184                         if (getuid() != 0 && optarg && name &&
 185                             strcmp(name, optarg) != 0)
 186                                 errx(1,"only super user can use the -u option");
 187                         locuser = optarg;
 188                         break;
 189 #endif /* IN_RCMD */
 190                 case '?':
 191                 default:
 192                         usage();
 193                 }
 194         optind += argoff;
 195
 196         /* if haven't gotten a host yet, do so */
 197         if (!host && !(host = argv[optind++]))
 198                 usage();
 199
 200         /* if no further arguments, must have been called as rlogin. */
 201         if (!argv[optind]) {
 202 #ifdef IN_RCMD
 203                 usage();
 204 #else
 205                 if (asrsh)
 206                         *argv = __UNCONST("rlogin");
 207                 setuid(uid);
 208                 execv(_PATH_RLOGIN, argv);
 209                 err(1, "can't exec %s", _PATH_RLOGIN);
 210 #endif
 211         }
 212
 213         argc -= optind;
 214         argv += optind;
 215
 216         /* Accept user1@host format, though "-l user2" overrides user1 */
 217         p = strchr(host, '@');
 218         if (p) {
 219                 *p = '\0';
 220                 if (!user && p > host)
 221                         user = host;
 222                 host = p + 1;
 223                 if (*host == '\0')
 224                         usage();
 225         }
 226         if (!user)
 227                 user = name;
 228
 229
 230         args = copyargs(argv);
 231
 232         if (sp == NULL)
 233                 sp = getservbyname("shell", "tcp");
 234         if (sp == NULL)
 235                 errx(1, "shell/tcp: unknown service");
 236
 237
 238 #ifdef IN_RCMD
 239         rem = orcmd_af(&host, sp->s_port, locuser ? locuser :
 240 #else
 241         rem = rcmd_af(&host, sp->s_port,
 242 #endif
 243             name, user, args, &remerr, family);
 244         (void)free(name);
 245
 246         if (rem < 0)
 247                 exit(1);
 248
 249         if (remerr < 0)
 250                 errx(1, "can't establish stderr");
 251         if (dflag) {
 252                 if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
 253                     sizeof(one)) < 0)
 254                         warn("setsockopt remote");
 255                 if (setsockopt(remerr, SOL_SOCKET, SO_DEBUG, &one,
 256                     sizeof(one)) < 0)
 257                         warn("setsockopt stderr");
 258         }
 259         proto = getprotobyname("tcp");
 260         setsockopt(rem, proto->p_proto, TCP_NODELAY, &one, sizeof(one));
 261         setsockopt(remerr, proto->p_proto, TCP_NODELAY, &one, sizeof(one));
 262
 263
 264         (void)setuid(uid);
 265
 266         (void)sigemptyset(&nset);
 267         for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++)
 268                 (void)sigaddset(&nset, sigs[i]);
 269
 270         (void)sigprocmask(SIG_BLOCK, &nset, &oset);
 271
 272 #ifdef IN_RCMD
 273         if (!relay_signal)
 274 #endif
 275                 for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++) {
 276                         struct sigaction sa;
 277
 278                         if (sa.sa_handler != SIG_IGN) {
 279                                 sa.sa_handler = sendsig;
 280                                 (void)sigaction(sigs[i], &sa, NULL);
 281                         }
 282                 }
 283
 284         if (!nflag) {
 285                 pid = fork();
 286                 if (pid < 0)
 287                         err(1, "fork");
 288         }
 289         else
 290                 pid = -1;
 291
 292         (void)ioctl(remerr, FIONBIO, &one);
 293         (void)ioctl(rem, FIONBIO, &one);
 294
 295         talk(nflag, &oset, pid, rem);
 296
 297         if (!nflag)
 298                 (void)kill(pid, SIGKILL);
 299         exit(0);
 300 }
 301
 302 static int
 303 checkfd(struct pollfd *fdp, int outfd)
 304 {
 305         int nr, nw;
 306         char buf[BUFSIZ];
 307
 308         if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
 309                 return -1;
 310
 311         if ((fdp->revents & POLLIN) == 0)
 312                 return 0;
 313
 314         errno = 0;
 315         nr = read(fdp->fd, buf, sizeof buf);
 316
 317         if (nr <= 0) {
 318                 if (errno != EAGAIN)
 319                         return -1;
 320                 else
 321                         return 0;
 322         }
 323         else {
 324                 char *bc = buf;
 325                 while (nr) {
 326                         if ((nw = write(outfd, bc, nr)) <= 0)
 327                                 return -1;
 328                         nr -= nw;
 329                         bc += nw;
 330                 }
 331                 return 0;
 332         }
 333 }
 334
 335 static void
 336 talk(int nflag, sigset_t *oset, __pid_t pid, int rem)
 337 {
 338         int nr, nw, nfds;
 339         struct pollfd fds[3], *fdp = &fds[0];
 340         char *bp, buf[BUFSIZ];
 341
 342         if (!nflag && pid == 0) {
 343                 (void)close(remerr);
 344
 345                 fdp->events = POLLOUT|POLLNVAL|POLLERR|POLLHUP;
 346                 fdp->fd = rem;
 347                 nr = 0;
 348                 bp = buf;
 349
 350                 for (;;) {
 351                         errno = 0;
 352
 353                         if (nr == 0) {
 354                                 if ((nr = read(0, buf, sizeof buf)) == 0)
 355                                         goto done;
 356                                 if (nr == -1) {
 357                                         if (errno == EIO)
 358                                                 goto done;
 359                                         if (errno == EINTR) {
 360                                                 nr = 0;
 361                                                 continue;
 362                                         }
 363                                         err(1, "read");
 364                                 }
 365                                 bp = buf;
 366                         }
 367
 368 rewrite:                if (poll(fdp, 1, INFTIM) == -1) {
 369                                 if (errno != EINTR)
 370                                         err(1, "poll");
 371                                 goto rewrite;
 372                         }
 373
 374                         if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
 375                                 err(1, "poll");
 376
 377                         if ((fdp->revents & POLLOUT) == 0)
 378                                 goto rewrite;
 379
 380                         nw = write(rem, bp, nr);
 381
 382                         if (nw < 0) {
 383                                 if (errno == EAGAIN)
 384                                         continue;
 385                                 err(1, "write");
 386                         }
 387                         bp += nw;
 388                         nr -= nw;
 389                 }
 390 done:
 391                 (void)shutdown(rem, 1);
 392                 exit(0);
 393         }
 394
 395         fdp = &fds[1];
 396         nfds = 2;
 397         fds[0].events = 0;
 398 #ifdef IN_RCMD
 399         if (relay_signal) {
 400                 fdp = &fds[0];
 401                 nfds = 3;
 402                 fds[0].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
 403                 fds[0].fd = 2;
 404         } else
 405 #endif
 406                 (void)sigprocmask(SIG_SETMASK, oset, NULL);
 407         fds[1].events = fds[2].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
 408         fds[1].fd = remerr;
 409         fds[2].fd = rem;
 410         do {
 411                 if (poll(fdp, nfds, INFTIM) == -1) {
 412                         if (errno != EINTR)
 413                                 err(1, "poll");
 414                         continue;
 415                 }
 416                 if ((fds[1].events != 0 && checkfd(&fds[1], 2) == -1)
 417 #ifdef IN_RCMD
 418                     || (fds[0].events != 0 && checkfd(&fds[0], remerr) == -1)
 419 #endif
 420                     ) {
 421                         nfds--;
 422                         fds[1].events = 0;
 423 #ifdef IN_RCMD
 424                         if (relay_signal) {
 425                                 nfds--;
 426                                 fds[0].events = 0;
 427                         }
 428 #endif
 429                         fdp = &fds[2];
 430                 }
 431                 if (fds[2].events != 0 && checkfd(&fds[2], 1) == -1) {
 432                         nfds--;
 433                         fds[2].events = 0;
 434                 }
 435         }
 436         while (nfds);
 437 }
 438
 439 static void
 440 sendsig(int sig)
 441 {
 442         char signo;
 443
 444         signo = sig;
 445         (void)write(remerr, &signo, 1);
 446 }
 447
 448 static char *
 449 copyargs(char **argv)
 450 {
 451         int cc;
 452         char **ap, *args, *p, *ep;
 453
 454         cc = 0;
 455         for (ap = argv; *ap; ++ap)
 456                 cc += strlen(*ap) + 1;
 457         if (!(args = malloc((u_int)cc)))
 458                 err(1, "malloc");
 459         ep = args + cc;
 460         for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
 461                 (void)strlcpy(p, *ap, ep - p);
 462                 p += strlen(p);
 463                 if (ap[1])
 464                         *p++ = ' ';
 465         }
 466         *p = '\0';
 467         return (args);
 468 }
 469
 470 static void
 471 usage(void)
 472 {
 473
 474         (void)fprintf(stderr,
 475             "usage: %s [-46dn] [-l login] [-p port]%s [login@]host command\n",
 476             getprogname(),
 477 #ifdef IN_RCMD
 478             " [-u locuser]"
 479 #else
 480             ""
 481 #endif
 482             );
 483         exit(1);
 484 }