usr.bin/rsh/rsh.c

   1 /*-
   2  * Copyright (c) 1983, 1990, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  * Copyright (c) 2002 Networks Associates Technology, Inc.
   5  * All rights reserved.
   6  *
   7  * Portions of this software were developed for the FreeBSD Project by
   8  * ThinkSec AS and NAI Labs, the Security Research Division of Network
   9  * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
  10  * ("CBOSS"), as part of the DARPA CHATS research program.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. All advertising materials mentioning features or use of this software
  21  *    must display the following acknowledgement:
  22  *      This product includes software developed by the University of
  23  *      California, Berkeley and its contributors.
  24  * 4. Neither the name of the University nor the names of its contributors
  25  *    may be used to endorse or promote products derived from this software
  26  *    without specific prior written permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  38  * SUCH DAMAGE.
  39  *
  40  * @(#)rsh.c    8.3 (Berkeley) 4/6/94
  41  * $FreeBSD: src/usr.bin/rsh/rsh.c,v 1.35 2005/05/21 09:55:07 ru Exp $
  42  * $DragonFly: src/usr.bin/rsh/rsh.c,v 1.7 2007/05/18 17:05:12 dillon Exp $
  43  */
  44
  45 #include <sys/param.h>
  46 #include <sys/signal.h>
  47 #include <sys/socket.h>
  48 #include <sys/ioctl.h>
  49 #include <sys/file.h>
  50 #include <sys/time.h>
  51
  52 #include <netinet/in.h>
  53 #include <netdb.h>
  54
  55 #include <err.h>
  56 #include <errno.h>
  57 #include <libutil.h>
  58 #include <paths.h>
  59 #include <pwd.h>
  60 #include <signal.h>
  61 #include <stdio.h>
  62 #include <stdlib.h>
  63 #include <string.h>
  64 #include <unistd.h>
  65
  66 /*
  67  * rsh - remote shell
  68  */
  69 int     rfd2;
  70
  71 int family = PF_UNSPEC;
  72 char rlogin[] = "rlogin";
  73
  74 void    connect_timeout(int);
  75 char   *copyargs(char * const *);
  76 void    sendsig(int);
  77 void    talk(int, long, pid_t, int, int);
  78 void    usage(void);
  79
  80 int
  81 main(int argc, char **argv)
  82 {
  83         struct passwd const *pw;
  84         struct servent const *sp;
  85         long omask;
  86         int argoff, asrsh, ch, dflag, nflag, one, rem;
  87         pid_t pid = 0;
  88         uid_t uid;
  89         char *args, *host, *p, *user;
  90         int timeout = 0;
  91
  92         argoff = asrsh = dflag = nflag = 0;
  93         one = 1;
  94         host = user = NULL;
  95
  96         /* if called as something other than "rsh", use it as the host name */
  97         if ((p = strrchr(argv[0], '/')))
  98                 ++p;
  99         else
 100                 p = argv[0];
 101         if (strcmp(p, "rsh"))
 102                 host = p;
 103         else
 104                 asrsh = 1;
 105
 106         /* handle "rsh host flags" */
 107         if (!host && argc > 2 && argv[1][0] != '-') {
 108                 host = argv[1];
 109                 argoff = 1;
 110         }
 111
 112 #define OPTIONS "468Lde:l:nt:w"
 113         while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
 114                 switch(ch) {
 115                 case '4':
 116                         family = PF_INET;
 117                         break;
 118
 119                 case '6':
 120                         family = PF_INET6;
 121                         break;
 122
 123                 case 'L':       /* -8Lew are ignored to allow rlogin aliases */
 124                 case 'e':
 125                 case 'w':
 126                 case '8':
 127                         break;
 128                 case 'd':
 129                         dflag = 1;
 130                         break;
 131                 case 'l':
 132                         user = optarg;
 133                         break;
 134                 case 'n':
 135                         nflag = 1;
 136                         break;
 137                 case 't':
 138                         timeout = atoi(optarg);
 139                         break;
 140                 case '?':
 141                 default:
 142                         usage();
 143                 }
 144         optind += argoff;
 145
 146         /* if haven't gotten a host yet, do so */
 147         if (!host && !(host = argv[optind++]))
 148                 usage();
 149
 150         /* if no further arguments, must have been called as rlogin. */
 151         if (!argv[optind]) {
 152                 if (asrsh)
 153                         *argv = rlogin;
 154                 execv(_PATH_RLOGIN, argv);
 155                 err(1, "can't exec %s", _PATH_RLOGIN);
 156         }
 157
 158         argc -= optind;
 159         argv += optind;
 160
 161         if (!(pw = getpwuid(uid = getuid())))
 162                 errx(1, "unknown user id");
 163         if (!user)
 164                 user = pw->pw_name;
 165
 166         args = copyargs(argv);
 167
 168         sp = NULL;
 169         if (sp == NULL)
 170                 sp = getservbyname("shell", "tcp");
 171         if (sp == NULL)
 172                 errx(1, "shell/tcp: unknown service");
 173
 174         if (timeout) {
 175                 signal(SIGALRM, connect_timeout);
 176                 alarm(timeout);
 177         }
 178         rem = rcmd_af(&host, sp->s_port, pw->pw_name, user, args, &rfd2,
 179                       family);
 180         if (timeout) {
 181                 signal(SIGALRM, SIG_DFL);
 182                 alarm(0);
 183         }
 184
 185         if (rem < 0)
 186                 exit(1);
 187
 188         if (rfd2 < 0)
 189                 errx(1, "can't establish stderr");
 190         if (dflag) {
 191                 if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
 192                     sizeof(one)) < 0)
 193                         warn("setsockopt");
 194                 if (setsockopt(rfd2, SOL_SOCKET, SO_DEBUG, &one,
 195                     sizeof(one)) < 0)
 196                         warn("setsockopt");
 197         }
 198
 199         setuid(uid);
 200         omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGTERM));
 201         if (signal(SIGINT, SIG_IGN) != SIG_IGN)
 202                 signal(SIGINT, sendsig);
 203         if (signal(SIGQUIT, SIG_IGN) != SIG_IGN)
 204                 signal(SIGQUIT, sendsig);
 205         if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
 206                 signal(SIGTERM, sendsig);
 207
 208         if (!nflag) {
 209                 pid = fork();
 210                 if (pid < 0)
 211                         err(1, "fork");
 212         }
 213         else
 214                 shutdown(rem, SHUT_WR);
 215
 216         ioctl(rfd2, FIONBIO, &one);
 217         ioctl(rem, FIONBIO, &one);
 218
 219         talk(nflag, omask, pid, rem, timeout);
 220
 221         if (!nflag)
 222                 kill(pid, SIGKILL);
 223         exit(0);
 224 }
 225
 226 void
 227 talk(int nflag, long omask, pid_t pid, int rem, int timeout)
 228 {
 229         int cc, wc;
 230         fd_set readfrom, ready, rembits;
 231         char buf[BUFSIZ];
 232         const char *bp;
 233         struct timeval tvtimeout;
 234         int nfds, srval;
 235
 236         if (!nflag && pid == 0) {
 237                 close(rfd2);
 238
 239 reread:         errno = 0;
 240                 if ((cc = read(STDIN_FILENO, buf, sizeof(buf))) <= 0)
 241                         goto done;
 242                 bp = buf;
 243
 244 rewrite:
 245                 if (rem >= FD_SETSIZE)
 246                         errx(1, "descriptor too big");
 247                 FD_ZERO(&rembits);
 248                 FD_SET(rem, &rembits);
 249                 nfds = rem + 1;
 250                 if (select(nfds, 0, &rembits, 0, 0) < 0) {
 251                         if (errno != EINTR)
 252                                 err(1, "select");
 253                         goto rewrite;
 254                 }
 255                 if (!FD_ISSET(rem, &rembits))
 256                         goto rewrite;
 257                 wc = write(rem, bp, cc);
 258                 if (wc < 0) {
 259                         if (errno == EWOULDBLOCK)
 260                                 goto rewrite;
 261                         goto done;
 262                 }
 263                 bp += wc;
 264                 cc -= wc;
 265                 if (cc == 0)
 266                         goto reread;
 267                 goto rewrite;
 268 done:
 269                 shutdown(rem, SHUT_WR);
 270                 exit(0);
 271         }
 272
 273         tvtimeout.tv_sec = timeout;
 274         tvtimeout.tv_usec = 0;
 275
 276         sigsetmask(omask);
 277         if (rfd2 >= FD_SETSIZE || rem >= FD_SETSIZE)
 278                 errx(1, "descriptor too big");
 279         FD_ZERO(&readfrom);
 280         FD_SET(rfd2, &readfrom);
 281         FD_SET(rem, &readfrom);
 282         nfds = MAX(rfd2+1, rem+1);
 283         do {
 284                 ready = readfrom;
 285                 if (timeout) {
 286                         srval = select(nfds, &ready, 0, 0, &tvtimeout);
 287                 } else {
 288                         srval = select(nfds, &ready, 0, 0, 0);
 289                 }
 290
 291                 if (srval < 0) {
 292                         if (errno != EINTR)
 293                                 err(1, "select");
 294                         continue;
 295                 }
 296                 if (srval == 0)
 297                         errx(1, "timeout reached (%d seconds)", timeout);
 298                 if (FD_ISSET(rfd2, &ready)) {
 299                         errno = 0;
 300                         cc = read(rfd2, buf, sizeof(buf));
 301                         if (cc <= 0) {
 302                                 if (errno != EWOULDBLOCK)
 303                                         FD_CLR(rfd2, &readfrom);
 304                         } else
 305                                 write(STDERR_FILENO, buf, cc);
 306                 }
 307                 if (FD_ISSET(rem, &ready)) {
 308                         errno = 0;
 309                         cc = read(rem, buf, sizeof(buf));
 310                         if (cc <= 0) {
 311                                 if (errno != EWOULDBLOCK)
 312                                         FD_CLR(rem, &readfrom);
 313                         } else
 314                                 write(STDOUT_FILENO, buf, cc);
 315                 }
 316         } while (FD_ISSET(rfd2, &readfrom) || FD_ISSET(rem, &readfrom));
 317 }
 318
 319 void
 320 connect_timeout(int sig __unused)
 321 {
 322         char message[] = "timeout reached before connection completed.\n";
 323
 324         write(STDERR_FILENO, message, sizeof(message) - 1);
 325         _exit(1);
 326 }
 327
 328 void
 329 sendsig(int sig)
 330 {
 331         char signo;
 332
 333         signo = sig;
 334         write(rfd2, &signo, 1);
 335 }
 336
 337 char *
 338 copyargs(char * const *argv)
 339 {
 340         int cc;
 341         char *args, *p;
 342         char * const *ap;
 343
 344         cc = 0;
 345         for (ap = argv; *ap; ++ap)
 346                 cc += strlen(*ap) + 1;
 347         if (!(args = malloc((u_int)cc)))
 348                 err(1, NULL);
 349         for (p = args, ap = argv; *ap; ++ap) {
 350                 strcpy(p, *ap);
 351                 for (p = strcpy(p, *ap); *p; ++p);
 352                 if (ap[1])
 353                         *p++ = ' ';
 354         }
 355         return (args);
 356 }
 357
 358 void
 359 usage(void)
 360 {
 361
 362         fprintf(stderr,
 363             "usage: rsh [-46dn] [-l username] [-t timeout] host [command]\n");
 364         exit(1);
 365 }