usr.bin/rsh/rsh.c

   1 /*      $NetBSD: rsh.c,v 1.30 2008/07/21 14:19:25 lukem 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 1.30 2008/07/21 14:19:25 lukem 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 char   *copyargs(char **);
  79 void    sendsig(int);
  80 int     checkfd(struct pollfd *, int);
  81 void    talk(int, sigset_t *, pid_t, int);
  82 void    usage(void);
  83 int     main(int, char **);
  84 #ifdef IN_RCMD
  85 int      orcmd(char **, int, const char *,
  86     const char *, const char *, int *);
  87 int      orcmd_af(char **, int, const char *,
  88     const char *, const char *, int *, int);
  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;
 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 ((loop = getenv("RCMD_LOOP")) && strcmp(loop, "YES") == 0)
 136                 warnx("rcmd appears to be looping!");
 137
 138         putenv("RCMD_LOOP=YES");
 139
 140 #  define       OPTIONS "468KLdel:np:u:w"
 141
 142 #else /* IN_RCMD */
 143
 144 #  define       OPTIONS "468KLdel:np:w"
 145
 146 #endif /* IN_RCMD */
 147
 148         if (!(pw = getpwuid(uid = getuid())))
 149                 errx(1, "unknown user id");
 150
 151         if ((name = strdup(pw->pw_name)) == NULL)
 152                 err(1, "malloc");
 153         while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
 154                 switch(ch) {
 155                 case '4':
 156                         family = AF_INET;
 157                         break;
 158                 case '6':
 159                         family = AF_INET6;
 160                         break;
 161                 case 'K':
 162                         break;
 163                 case 'L':       /* -8Lew are ignored to allow rlogin aliases */
 164                 case 'e':
 165                 case 'w':
 166                 case '8':
 167                         break;
 168                 case 'd':
 169                         dflag = 1;
 170                         break;
 171                 case 'l':
 172                         user = optarg;
 173                         break;
 174                 case 'n':
 175                         nflag = 1;
 176                         break;
 177                 case 'p':
 178                         sp = getport(optarg, "tcp");
 179                         break;
 180 #ifdef IN_RCMD
 181                 case 'u':
 182                         if (getuid() != 0 && optarg && name &&
 183                             strcmp(name, optarg) != 0)
 184                                 errx(1,"only super user can use the -u option");
 185                         locuser = optarg;
 186                         break;
 187 #endif /* IN_RCMD */
 188                 case '?':
 189                 default:
 190                         usage();
 191                 }
 192         optind += argoff;
 193
 194         /* if haven't gotten a host yet, do so */
 195         if (!host && !(host = argv[optind++]))
 196                 usage();
 197
 198         /* if no further arguments, must have been called as rlogin. */
 199         if (!argv[optind]) {
 200 #ifdef IN_RCMD
 201                 usage();
 202 #else
 203                 if (asrsh)
 204                         *argv = __UNCONST("rlogin");
 205                 execv(_PATH_RLOGIN, argv);
 206                 err(1, "can't exec %s", _PATH_RLOGIN);
 207 #endif
 208         }
 209
 210         argc -= optind;
 211         argv += optind;
 212
 213         /* Accept user1@host format, though "-l user2" overrides user1 */
 214         p = strchr(host, '@');
 215         if (p) {
 216                 *p = '\0';
 217                 if (!user && p > host)
 218                         user = host;
 219                 host = p + 1;
 220                 if (*host == '\0')
 221                         usage();
 222         }
 223         if (!user)
 224                 user = name;
 225
 226
 227         args = copyargs(argv);
 228
 229         if (sp == NULL)
 230                 sp = getservbyname("shell", "tcp");
 231         if (sp == NULL)
 232                 errx(1, "shell/tcp: unknown service");
 233
 234
 235 #ifdef IN_RCMD
 236         rem = orcmd_af(&host, sp->s_port, locuser ? locuser :
 237 #else
 238         rem = rcmd_af(&host, sp->s_port,
 239 #endif
 240             name, user, args, &remerr, family);
 241         (void)free(name);
 242
 243         if (rem < 0)
 244                 exit(1);
 245
 246         if (remerr < 0)
 247                 errx(1, "can't establish stderr");
 248         if (dflag) {
 249                 if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
 250                     sizeof(one)) < 0)
 251                         warn("setsockopt remote");
 252                 if (setsockopt(remerr, SOL_SOCKET, SO_DEBUG, &one,
 253                     sizeof(one)) < 0)
 254                         warn("setsockopt stderr");
 255         }
 256         proto = getprotobyname("tcp");
 257         setsockopt(rem, proto->p_proto, TCP_NODELAY, &one, sizeof(one));
 258         setsockopt(remerr, proto->p_proto, TCP_NODELAY, &one, sizeof(one));
 259
 260
 261         (void)setuid(uid);
 262
 263         (void)sigemptyset(&nset);
 264         for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++)
 265                 (void)sigaddset(&nset, sigs[i]);
 266
 267         (void)sigprocmask(SIG_BLOCK, &nset, &oset);
 268
 269         for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++) {
 270                 struct sigaction sa;
 271
 272                 if (sa.sa_handler != SIG_IGN) {
 273                         sa.sa_handler = sendsig;
 274                         (void)sigaction(sigs[i], &sa, NULL);
 275                 }
 276         }
 277
 278         if (!nflag) {
 279                 pid = fork();
 280                 if (pid < 0)
 281                         err(1, "fork");
 282         }
 283         else
 284                 pid = -1;
 285
 286 #if defined(KERBEROS) && defined(CRYPT)
 287         if (!doencrypt)
 288 #endif
 289         {
 290                 (void)ioctl(remerr, FIONBIO, &one);
 291                 (void)ioctl(rem, FIONBIO, &one);
 292         }
 293
 294         talk(nflag, &oset, pid, rem);
 295
 296         if (!nflag)
 297                 (void)kill(pid, SIGKILL);
 298         exit(0);
 299 }
 300
 301 int
 302 checkfd(struct pollfd *fdp, int outfd)
 303 {
 304         int nr, nw;
 305         char buf[BUFSIZ];
 306
 307         if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
 308                 return -1;
 309
 310         if ((fdp->revents & POLLIN) == 0)
 311                 return 0;
 312
 313         errno = 0;
 314 #if defined(KERBEROS) && defined(CRYPT)
 315         if (doencrypt)
 316                 nr = des_read(fdp->fd, buf, sizeof buf);
 317         else
 318 #endif
 319                 nr = read(fdp->fd, buf, sizeof buf);
 320
 321         if (nr <= 0) {
 322                 if (errno != EAGAIN)
 323                         return -1;
 324                 else
 325                         return 0;
 326         }
 327         else {
 328                 char *bc = buf;
 329                 while (nr) {
 330                         if ((nw = write(outfd, bc, nr)) <= 0)
 331                                 return -1;
 332                         nr -= nw;
 333                         bc += nw;
 334                 }
 335                 return 0;
 336         }
 337 }
 338
 339 void
 340 talk(int nflag, sigset_t *oset, __pid_t pid, int rem)
 341 {
 342         int nr, nw, nfds;
 343         struct pollfd fds[2], *fdp = &fds[0];
 344         char *bp, buf[BUFSIZ];
 345
 346         if (!nflag && pid == 0) {
 347                 (void)close(remerr);
 348
 349                 fdp->events = POLLOUT|POLLNVAL|POLLERR|POLLHUP;
 350                 fdp->fd = rem;
 351                 nr = 0;
 352                 bp = buf;
 353
 354                 for (;;) {
 355                         errno = 0;
 356
 357                         if (nr == 0) {
 358                                 if ((nr = read(0, buf, sizeof buf)) == 0)
 359                                         goto done;
 360                                 if (nr == -1) {
 361                                         if (errno == EIO)
 362                                                 goto done;
 363                                         if (errno == EINTR) {
 364                                                 nr = 0;
 365                                                 continue;
 366                                         }
 367                                         err(1, "read");
 368                                 }
 369                                 bp = buf;
 370                         }
 371
 372 rewrite:                if (poll(fdp, 1, INFTIM) == -1) {
 373                                 if (errno != EINTR)
 374                                         err(1, "poll");
 375                                 goto rewrite;
 376                         }
 377
 378                         if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
 379                                 err(1, "poll");
 380
 381                         if ((fdp->revents & POLLOUT) == 0)
 382                                 goto rewrite;
 383
 384 #if defined(KERBEROS) && defined(CRYPT)
 385                         if (doencrypt)
 386                                 nw = des_write(rem, bp, nr);
 387                         else
 388 #endif
 389                                 nw = write(rem, bp, nr);
 390
 391                         if (nw < 0) {
 392                                 if (errno == EAGAIN)
 393                                         continue;
 394                                 err(1, "write");
 395                         }
 396                         bp += nw;
 397                         nr -= nw;
 398                 }
 399 done:
 400                 (void)shutdown(rem, 1);
 401                 exit(0);
 402         }
 403
 404         (void)sigprocmask(SIG_SETMASK, oset, NULL);
 405         fds[0].events = fds[1].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
 406         fds[0].fd = remerr;
 407         fds[1].fd = rem;
 408         fdp = &fds[0];
 409         nfds = 2;
 410         do {
 411                 if (poll(fdp, nfds, INFTIM) == -1) {
 412                         if (errno != EINTR)
 413                                 err(1, "poll");
 414                         continue;
 415                 }
 416                 if (fds[0].events != 0 && checkfd(&fds[0], 2) == -1) {
 417                         nfds--;
 418                         fds[0].events = 0;
 419                         fdp = &fds[1];
 420                 }
 421                 if (fds[1].events != 0 && checkfd(&fds[1], 1) == -1) {
 422                         nfds--;
 423                         fds[1].events = 0;
 424                 }
 425         }
 426         while (nfds);
 427 }
 428
 429 void
 430 sendsig(int sig)
 431 {
 432         char signo;
 433
 434         signo = sig;
 435                 (void)write(remerr, &signo, 1);
 436 }
 437
 438
 439 char *
 440 copyargs(char **argv)
 441 {
 442         int cc;
 443         char **ap, *args, *p, *ep;
 444
 445         cc = 0;
 446         for (ap = argv; *ap; ++ap)
 447                 cc += strlen(*ap) + 1;
 448         if (!(args = malloc((u_int)cc)))
 449                 err(1, "malloc");
 450         ep = args + cc;
 451         for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
 452                 (void)strlcpy(p, *ap, ep - p);
 453                 p += strlen(p);
 454                 if (ap[1])
 455                         *p++ = ' ';
 456         }
 457         *p = '\0';
 458         return (args);
 459 }
 460
 461 void
 462 usage(void)
 463 {
 464
 465         (void)fprintf(stderr,
 466             "usage: %s [-46dn] [-l login] [-p port]%s [login@]host command\n",
 467             getprogname(),
 468 #ifdef IN_RCMD
 469             " [-u locuser]"
 470 #else
 471             ""
 472 #endif
 473             );
 474         exit(1);
 475 }