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