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  *
   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  * @(#) Copyright (c) 1983, 1990, 1993, 1994 The Regents of the University of California.  All rights reserved.
  34  * @(#)rsh.c    8.3 (Berkeley) 4/6/94
  35  * $FreeBSD: src/usr.bin/rsh/rsh.c,v 1.21.2.4 2002/09/17 15:34:41 nectar Exp $
  36  * $DragonFly: src/usr.bin/rsh/rsh.c,v 1.6 2005/01/01 23:00:15 cpressey Exp $
  37  */
  38
  39 #include <sys/param.h>
  40 #include <sys/signal.h>
  41 #include <sys/socket.h>
  42 #include <sys/ioctl.h>
  43 #include <sys/file.h>
  44 #include <sys/time.h>
  45
  46 #include <netinet/in.h>
  47 #include <netdb.h>
  48
  49 #include <err.h>
  50 #include <errno.h>
  51 #include <libutil.h>
  52 #include <pwd.h>
  53 #include <signal.h>
  54 #include <stdio.h>
  55 #include <stdlib.h>
  56 #include <string.h>
  57 #include <unistd.h>
  58
  59 #include "pathnames.h"
  60
  61 #ifdef KERBEROS
  62 #include <openssl/des.h>
  63 #include <krb.h>
  64 #include "krb.h"
  65
  66 CREDENTIALS cred;
  67 Key_schedule schedule;
  68 int use_kerberos = 1, doencrypt;
  69 char dst_realm_buf[REALM_SZ], *dest_realm;
  70 extern char *krb_realmofhost();
  71 #endif
  72
  73 /*
  74  * rsh - remote shell
  75  */
  76 int     rfd2;
  77
  78 int family = PF_UNSPEC;
  79
  80 void    connect_timeout(int);
  81 char   *copyargs(char **);
  82 void    sendsig(int);
  83 void    talk(int, long, pid_t, int, int);
  84 void    usage(void);
  85
  86 static char rlogin[] = "rlogin";
  87
  88 int
  89 main(int argc, char **argv)
  90 {
  91         struct passwd *pw;
  92         struct servent *sp;
  93         long omask;
  94         int argoff, asrsh, ch, dflag, nflag, one, rem;
  95         pid_t pid = 0;
  96         uid_t uid;
  97         char *args, *host, *p, *user;
  98         int timeout = 0;
  99 #ifdef KERBEROS
 100         char *k;
 101 #endif
 102
 103         argoff = asrsh = dflag = nflag = 0;
 104         one = 1;
 105         host = user = NULL;
 106
 107         /* if called as something other than "rsh", use it as the host name */
 108         if ((p = strrchr(argv[0], '/')))
 109                 ++p;
 110         else
 111                 p = argv[0];
 112         if (strcmp(p, "rsh"))
 113                 host = p;
 114         else
 115                 asrsh = 1;
 116
 117         /* handle "rsh host flags" */
 118         if (!host && argc > 2 && argv[1][0] != '-') {
 119                 host = argv[1];
 120                 argoff = 1;
 121         }
 122
 123 #ifdef KERBEROS
 124 #ifdef CRYPT
 125 #define OPTIONS "468KLde:k:l:nt:wx"
 126 #else
 127 #define OPTIONS "468KLde:k:l:nt:w"
 128 #endif
 129 #else
 130 #define OPTIONS "468KLde:l:nt:w"
 131 #endif
 132         while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
 133                 switch(ch) {
 134                 case '4':
 135                         family = PF_INET;
 136                         break;
 137
 138                 case '6':
 139                         family = PF_INET6;
 140                         break;
 141
 142                 case 'K':
 143 #ifdef KERBEROS
 144                         use_kerberos = 0;
 145 #endif
 146                         break;
 147                 case 'L':       /* -8Lew are ignored to allow rlogin aliases */
 148                 case 'e':
 149                 case 'w':
 150                 case '8':
 151                         break;
 152                 case 'd':
 153                         dflag = 1;
 154                         break;
 155                 case 'l':
 156                         user = optarg;
 157                         break;
 158 #ifdef KERBEROS
 159                 case 'k':
 160                         dest_realm = dst_realm_buf;
 161                         strncpy(dest_realm, optarg, REALM_SZ);
 162                         break;
 163 #endif
 164                 case 'n':
 165                         nflag = 1;
 166                         break;
 167 #ifdef KERBEROS
 168 #ifdef CRYPT
 169                 case 'x':
 170                         doencrypt = 1;
 171                         break;
 172 #endif
 173 #endif
 174                 case 't':
 175                         timeout = atoi(optarg);
 176                         break;
 177                 case '?':
 178                 default:
 179                         usage();
 180                 }
 181         optind += argoff;
 182
 183         /* if haven't gotten a host yet, do so */
 184         if (!host && !(host = argv[optind++]))
 185                 usage();
 186
 187         /* if no further arguments, must have been called as rlogin. */
 188         if (!argv[optind]) {
 189                 if (asrsh)
 190                         *argv = rlogin;
 191                 execv(_PATH_RLOGIN, argv);
 192                 err(1, "can't exec %s", _PATH_RLOGIN);
 193         }
 194
 195         argc -= optind;
 196         argv += optind;
 197
 198         if (!(pw = getpwuid(uid = getuid())))
 199                 errx(1, "unknown user id");
 200         if (!user)
 201                 user = pw->pw_name;
 202
 203 #ifdef KERBEROS
 204 #ifdef CRYPT
 205         /* -x turns off -n */
 206         if (doencrypt)
 207                 nflag = 0;
 208 #endif
 209 #endif
 210
 211         args = copyargs(argv);
 212
 213         sp = NULL;
 214 #ifdef KERBEROS
 215         k = auth_getval("auth_list");
 216         if (k && !strstr(k, "kerberos"))
 217             use_kerberos = 0;
 218         if (use_kerberos) {
 219                 sp = getservbyname((doencrypt ? "ekshell" : "kshell"), "tcp");
 220                 if (sp == NULL) {
 221                         use_kerberos = 0;
 222                         warnx(
 223         "warning, using standard rsh: can't get entry for %s/tcp service",
 224                             doencrypt ? "ekshell" : "kshell");
 225                 }
 226         }
 227 #endif
 228         if (sp == NULL)
 229                 sp = getservbyname("shell", "tcp");
 230         if (sp == NULL)
 231                 errx(1, "shell/tcp: unknown service");
 232
 233 #ifdef KERBEROS
 234 try_connect:
 235         if (use_kerberos) {
 236                 struct hostent *hp;
 237
 238                 /* fully qualify hostname (needed for krb_realmofhost) */
 239                 hp = gethostbyname(host);
 240                 if (hp != NULL && !(host = strdup(hp->h_name)))
 241                         err(1, NULL);
 242
 243                 rem = KSUCCESS;
 244                 errno = 0;
 245                 if (dest_realm == NULL)
 246                         dest_realm = krb_realmofhost(host);
 247
 248 #ifdef CRYPT
 249                 if (doencrypt) {
 250                         rem = krcmd_mutual(&host, sp->s_port, user, args,
 251                             &rfd2, dest_realm, &cred, schedule);
 252                         des_set_key(&cred.session, schedule);
 253                 } else
 254 #endif
 255                         rem = krcmd(&host, sp->s_port, user, args, &rfd2,
 256                             dest_realm);
 257                 if (rem < 0) {
 258                         use_kerberos = 0;
 259                         sp = getservbyname("shell", "tcp");
 260                         if (sp == NULL)
 261                                 errx(1, "shell/tcp: unknown service");
 262                         if (errno == ECONNREFUSED)
 263                                 warnx(
 264                 "warning, using standard rsh: remote host doesn't support Kerberos");
 265                         if (errno == ENOENT)
 266                                 warnx(
 267                 "warning, using standard rsh: can't provide Kerberos auth data");
 268                         goto try_connect;
 269                 }
 270         } else {
 271                 if (doencrypt)
 272                         errx(1, "the -x flag requires Kerberos authentication");
 273                 rem = rcmd_af(&host, sp->s_port, pw->pw_name, user, args,
 274                               &rfd2, family);
 275         }
 276 #else
 277         if (timeout) {
 278                 signal(SIGALRM, connect_timeout);
 279                 alarm(timeout);
 280         }
 281         rem = rcmd_af(&host, sp->s_port, pw->pw_name, user, args, &rfd2,
 282                       family);
 283         if (timeout) {
 284                 signal(SIGALRM, SIG_DFL);
 285                 alarm(0);
 286         }
 287 #endif
 288
 289         if (rem < 0)
 290                 exit(1);
 291
 292         if (rfd2 < 0)
 293                 errx(1, "can't establish stderr");
 294         if (dflag) {
 295                 if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
 296                     sizeof(one)) < 0)
 297                         warn("setsockopt");
 298                 if (setsockopt(rfd2, SOL_SOCKET, SO_DEBUG, &one,
 299                     sizeof(one)) < 0)
 300                         warn("setsockopt");
 301         }
 302
 303         setuid(uid);
 304         omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGTERM));
 305         if (signal(SIGINT, SIG_IGN) != SIG_IGN)
 306                 signal(SIGINT, sendsig);
 307         if (signal(SIGQUIT, SIG_IGN) != SIG_IGN)
 308                 signal(SIGQUIT, sendsig);
 309         if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
 310                 signal(SIGTERM, sendsig);
 311
 312         if (!nflag) {
 313                 pid = fork();
 314                 if (pid < 0)
 315                         err(1, "fork");
 316         }
 317         else
 318                 shutdown(rem, 1);
 319
 320 #ifdef KERBEROS
 321 #ifdef CRYPT
 322         if (!doencrypt)
 323 #endif
 324 #endif
 325         {
 326                 ioctl(rfd2, FIONBIO, &one);
 327                 ioctl(rem, FIONBIO, &one);
 328         }
 329
 330         talk(nflag, omask, pid, rem, timeout);
 331
 332         if (!nflag)
 333                 kill(pid, SIGKILL);
 334         exit(0);
 335 }
 336
 337 void
 338 talk(int nflag, long omask, pid_t pid, int rem, int timeout)
 339 {
 340         int cc, wc;
 341         fd_set readfrom, ready, rembits;
 342         char *bp, buf[BUFSIZ];
 343         struct timeval tvtimeout;
 344         int nfds, srval;
 345
 346         if (!nflag && pid == 0) {
 347                 close(rfd2);
 348
 349 reread:         errno = 0;
 350                 if ((cc = read(STDIN_FILENO, buf, sizeof(buf))) <= 0)
 351                         goto done;
 352                 bp = buf;
 353
 354 rewrite:
 355                 if (rem >= FD_SETSIZE)
 356                         errx(1, "descriptor too big");
 357                 FD_ZERO(&rembits);
 358                 FD_SET(rem, &rembits);
 359                 nfds = rem + 1;
 360                 if (select(nfds, 0, &rembits, 0, 0) < 0) {
 361                         if (errno != EINTR)
 362                                 err(1, "select");
 363                         goto rewrite;
 364                 }
 365                 if (!FD_ISSET(rem, &rembits))
 366                         goto rewrite;
 367 #ifdef KERBEROS
 368 #ifdef CRYPT
 369                 if (doencrypt)
 370                         wc = des_enc_write(rem, bp, cc, schedule, &cred.session);
 371                 else
 372 #endif
 373 #endif
 374                         wc = write(rem, bp, cc);
 375                 if (wc < 0) {
 376                         if (errno == EWOULDBLOCK)
 377                                 goto rewrite;
 378                         goto done;
 379                 }
 380                 bp += wc;
 381                 cc -= wc;
 382                 if (cc == 0)
 383                         goto reread;
 384                 goto rewrite;
 385 done:
 386                 shutdown(rem, 1);
 387                 exit(0);
 388         }
 389
 390         tvtimeout.tv_sec = timeout;
 391         tvtimeout.tv_usec = 0;
 392
 393         sigsetmask(omask);
 394         if (rfd2 >= FD_SETSIZE || rem >= FD_SETSIZE)
 395                 errx(1, "descriptor too big");
 396         FD_ZERO(&readfrom);
 397         FD_SET(rfd2, &readfrom);
 398         FD_SET(rem, &readfrom);
 399         nfds = MAX(rfd2+1, rem+1);
 400         do {
 401                 ready = readfrom;
 402                 if (timeout) {
 403                         srval = select(nfds, &ready, 0, 0, &tvtimeout);
 404                 } else {
 405                         srval = select(nfds, &ready, 0, 0, 0);
 406                 }
 407
 408                 if (srval < 0) {
 409                         if (errno != EINTR)
 410                                 err(1, "select");
 411                         continue;
 412                 }
 413                 if (srval == 0)
 414                         errx(1, "timeout reached (%d seconds)", timeout);
 415                 if (FD_ISSET(rfd2, &ready)) {
 416                         errno = 0;
 417 #ifdef KERBEROS
 418 #ifdef CRYPT
 419                         if (doencrypt)
 420                                 cc = des_enc_read(rfd2, buf, sizeof(buf), schedule, &cred.session);
 421                         else
 422 #endif
 423 #endif
 424                                 cc = read(rfd2, buf, sizeof(buf));
 425                         if (cc <= 0) {
 426                                 if (errno != EWOULDBLOCK)
 427                                         FD_CLR(rfd2, &readfrom);
 428                         } else
 429                                 write(STDERR_FILENO, buf, cc);
 430                 }
 431                 if (FD_ISSET(rem, &ready)) {
 432                         errno = 0;
 433 #ifdef KERBEROS
 434 #ifdef CRYPT
 435                         if (doencrypt)
 436                                 cc = des_enc_read(rem, buf, sizeof(buf), schedule, &cred.session);
 437                         else
 438 #endif
 439 #endif
 440                                 cc = read(rem, buf, sizeof(buf));
 441                         if (cc <= 0) {
 442                                 if (errno != EWOULDBLOCK)
 443                                         FD_CLR(rem, &readfrom);
 444                         } else
 445                                 write(STDOUT_FILENO, buf, cc);
 446                 }
 447         } while (FD_ISSET(rfd2, &readfrom) || FD_ISSET(rem, &readfrom));
 448 }
 449
 450 void
 451 connect_timeout(__unused int sig)
 452 {
 453         char message[] = "timeout reached before connection completed.\n";
 454
 455         write(STDERR_FILENO, message, sizeof(message) - 1);
 456         _exit(1);
 457 }
 458
 459 void
 460 sendsig(int sig)
 461 {
 462         char signo;
 463
 464         signo = sig;
 465 #ifdef KERBEROS
 466 #ifdef CRYPT
 467         if (doencrypt)
 468                 des_enc_write(rfd2, &signo, 1, schedule, &cred.session);
 469         else
 470 #endif
 471 #endif
 472                 write(rfd2, &signo, 1);
 473 }
 474
 475 char *
 476 copyargs(char **argv)
 477 {
 478         int cc;
 479         char **ap, *args, *p;
 480
 481         cc = 0;
 482         for (ap = argv; *ap; ++ap)
 483                 cc += strlen(*ap) + 1;
 484         if (!(args = malloc((u_int)cc)))
 485                 err(1, NULL);
 486         for (p = args, ap = argv; *ap; ++ap) {
 487                 strcpy(p, *ap);
 488                 for (p = strcpy(p, *ap); *p; ++p);
 489                 if (ap[1])
 490                         *p++ = ' ';
 491         }
 492         return (args);
 493 }
 494
 495 void
 496 usage(void)
 497 {
 498
 499         fprintf(stderr,
 500             "usage: rsh [-46] [-ndK%s]%s[-l login] [-t timeout] host [command]\n",
 501 #ifdef KERBEROS
 502 #ifdef CRYPT
 503             "x", " [-k realm] ");
 504 #else
 505             "", " [-k realm] ");
 506 #endif
 507 #else
 508             "", " ");
 509 #endif
 510         exit(1);
 511 }
 512