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rsh.c revision 1.8 
      1 /*	$NetBSD: rsh.c,v 1.8 1997/06/02 11:57:23 mrg 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. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #ifndef lint
     37 static char copyright[] =
     38 "@(#) Copyright (c) 1983, 1990, 1993, 1994\n\
     39 	The Regents of the University of California.  All rights reserved.\n";
     40 #endif /* not lint */
     41 
     42 #ifndef lint
     43 /*static char sccsid[] = "from: @(#)rsh.c	8.4 (Berkeley) 4/29/95";*/
     44 static char rcsid[] = "$NetBSD: rsh.c,v 1.8 1997/06/02 11:57:23 mrg Exp $";
     45 #endif /* not lint */
     46 
     47 #include <sys/types.h>
     48 #include <sys/socket.h>
     49 #include <sys/ioctl.h>
     50 #include <sys/file.h>
     51 #include <poll.h>
     52 
     53 #include <netinet/in.h>
     54 #include <netdb.h>
     55 
     56 #include <err.h>
     57 #include <errno.h>
     58 #include <pwd.h>
     59 #include <signal.h>
     60 #include <stdio.h>
     61 #include <stdlib.h>
     62 #include <string.h>
     63 #include <unistd.h>
     64 #include <varargs.h>
     65 
     66 #include "pathnames.h"
     67 
     68 #ifdef KERBEROS
     69 #include <kerberosIV/des.h>
     70 #include <kerberosIV/krb.h>
     71 
     72 CREDENTIALS cred;
     73 Key_schedule schedule;
     74 int use_kerberos = 1, doencrypt;
     75 char dst_realm_buf[REALM_SZ], *dest_realm;
     76 extern char *krb_realmofhost();
     77 #endif
     78 
     79 /*
     80  * rsh - remote shell
     81  */
     82 extern	char *__progname;		/* XXX */
     83 int	rfd2;
     84 
     85 char   *copyargs __P((char **));
     86 void	sendsig __P((int));
     87 void	talk __P((int, long, pid_t, int));
     88 void	usage __P((void));
     89 void	warning __P(());
     90 
     91 int
     92 main(argc, argv)
     93 	int argc;
     94 	char **argv;
     95 {
     96 	struct passwd *pw;
     97 	struct servent *sp;
     98 	long omask;
     99 #ifdef IN_RCMD
    100 	char	*locuser = 0, *loop;
    101 #endif /* IN_RCMD */
    102 	int argoff, asrsh, ch, dflag, nflag, one, rem;
    103 	pid_t pid;
    104 	uid_t uid;
    105 	char *args, *host, *p, *user;
    106 
    107 	argoff = asrsh = dflag = nflag = 0;
    108 	one = 1;
    109 	host = user = NULL;
    110 
    111 #ifndef IN_RCMD
    112 	/*
    113 	 * If called as something other than "rsh" use it as the host name,
    114 	 * only for rsh.
    115 	 */
    116 	p = __progname;
    117 	if (strcmp(p, "rsh") == 0)
    118 		asrsh = 1;
    119 	else
    120 		host = p;
    121 #endif /* IN_RCMD */
    122 
    123 	/* handle "rsh host flags" */
    124 	if (!host && argc > 2 && argv[1][0] != '-') {
    125 		host = argv[1];
    126 		argoff = 1;
    127 	}
    128 
    129 #ifdef IN_RCMD
    130 	if ((loop = getenv("RCMD_LOOP")) && strcmp(loop, "YES") == 0)
    131 		warnx("rcmd appears to be looping!");
    132 
    133 	putenv("RCMD_LOOP=YES");
    134 
    135 # ifdef KERBEROS
    136 #  ifdef CRYPT
    137 #   define	OPTIONS	"8KLdek:l:nu:wx"
    138 #  else
    139 #   define	OPTIONS	"8KLdek:l:nu:w"
    140 #  endif
    141 # else
    142 #  define	OPTIONS	"8KLdel:nu:w"
    143 # endif
    144 
    145 #else /* IN_RCMD */
    146 
    147 # ifdef KERBEROS
    148 #  ifdef CRYPT
    149 #   define	OPTIONS	"8KLdek:l:nwx"
    150 #  else
    151 #   define	OPTIONS	"8KLdek:l:nw"
    152 #  endif
    153 # else
    154 #  define	OPTIONS	"8KLdel:nw"
    155 # endif
    156 
    157 #endif /* IN_RCMD */
    158 
    159 	if (!(pw = getpwuid(uid = getuid())))
    160 		errx(1, "unknown user id");
    161 
    162 	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != EOF)
    163 		switch(ch) {
    164 		case 'K':
    165 #ifdef KERBEROS
    166 			use_kerberos = 0;
    167 #endif
    168 			break;
    169 		case 'L':	/* -8Lew are ignored to allow rlogin aliases */
    170 		case 'e':
    171 		case 'w':
    172 		case '8':
    173 			break;
    174 		case 'd':
    175 			dflag = 1;
    176 			break;
    177 		case 'l':
    178 			user = optarg;
    179 			break;
    180 #ifdef KERBEROS
    181 		case 'k':
    182 			dest_realm = dst_realm_buf;
    183 			strncpy(dest_realm, optarg, REALM_SZ);
    184 			break;
    185 #endif
    186 		case 'n':
    187 			nflag = 1;
    188 			break;
    189 #ifdef IN_RCMD
    190 		case 'u':
    191 			if (getuid() != 0 && optarg && pw->pw_name &&
    192 			    strcmp(pw->pw_name, optarg) != 0)
    193 				errx(1,"only super user can use the -u option");
    194 			locuser = optarg;
    195 			break;
    196 #endif /* IN_RCMD */
    197 #ifdef KERBEROS
    198 #ifdef CRYPT
    199 		case 'x':
    200 			doencrypt = 1;
    201 			des_set_key(cred.session, schedule);
    202 			break;
    203 #endif
    204 #endif
    205 		case '?':
    206 		default:
    207 			usage();
    208 		}
    209 	optind += argoff;
    210 
    211 	/* if haven't gotten a host yet, do so */
    212 	if (!host && !(host = argv[optind++]))
    213 		usage();
    214 
    215 	/* if no further arguments, must have been called as rlogin. */
    216 	if (!argv[optind]) {
    217 #ifdef IN_RCMD
    218 		usage();
    219 #else
    220 		if (asrsh)
    221 			*argv = "rlogin";
    222 		execv(_PATH_RLOGIN, argv);
    223 		err(1, "can't exec %s", _PATH_RLOGIN);
    224 #endif
    225 	}
    226 
    227 	argc -= optind;
    228 	argv += optind;
    229 
    230 	/* Accept user1@host format, though "-l user2" overrides user1 */
    231 	p = strchr(host, '@');
    232 	if (p) {
    233 		*p = '\0';
    234 		if (!user && p > host)
    235 			user = host;
    236 		host = p + 1;
    237 		if (*host == '\0')
    238 			usage();
    239 	}
    240 	if (!user)
    241 		user = pw->pw_name;
    242 
    243 #ifdef KERBEROS
    244 #ifdef CRYPT
    245 	/* -x turns off -n */
    246 	if (doencrypt)
    247 		nflag = 0;
    248 #endif
    249 #endif
    250 
    251 	args = copyargs(argv);
    252 
    253 	sp = NULL;
    254 #ifdef KERBEROS
    255 	if (use_kerberos) {
    256 		sp = getservbyname((doencrypt ? "ekshell" : "kshell"), "tcp");
    257 		if (sp == NULL) {
    258 			use_kerberos = 0;
    259 			warning("can't get entry for %s/tcp service",
    260 			    doencrypt ? "ekshell" : "kshell");
    261 		}
    262 	}
    263 #endif
    264 	if (sp == NULL)
    265 		sp = getservbyname("shell", "tcp");
    266 	if (sp == NULL)
    267 		errx(1, "shell/tcp: unknown service");
    268 
    269 #ifdef KERBEROS
    270 try_connect:
    271 	if (use_kerberos) {
    272 #if 1
    273 		struct hostent *hp;
    274 
    275 		/* fully qualify hostname (needed for krb_realmofhost) */
    276 		hp = gethostbyname(host);
    277 		if (hp != NULL && !(host = strdup(hp->h_name)))
    278 			err(1, NULL);
    279 #endif
    280 
    281 		rem = KSUCCESS;
    282 		errno = 0;
    283 		if (dest_realm == NULL)
    284 			dest_realm = krb_realmofhost(host);
    285 
    286 #ifdef CRYPT
    287 		if (doencrypt)
    288 			rem = krcmd_mutual(&host, sp->s_port, user, args,
    289 			    &rfd2, dest_realm, &cred, schedule);
    290 		else
    291 #endif
    292 			rem = krcmd(&host, sp->s_port, user, args, &rfd2,
    293 			    dest_realm);
    294 		if (rem < 0) {
    295 			use_kerberos = 0;
    296 			sp = getservbyname("shell", "tcp");
    297 			if (sp == NULL)
    298 				errx(1, "shell/tcp: unknown service");
    299 			if (errno == ECONNREFUSED)
    300 				warning("remote host doesn't support Kerberos");
    301 			if (errno == ENOENT)
    302 				warning("can't provide Kerberos auth data");
    303 			goto try_connect;
    304 		}
    305 	} else {
    306 		if (doencrypt)
    307 			errx(1, "the -x flag requires Kerberos authentication.");
    308 #ifdef IN_RCMD
    309 		rem = orcmd(&host, sp->s_port, locuser ? locuser :
    310 #else
    311 		rem = rcmd(&host, sp->s_port,
    312 #endif
    313 		    pw->pw_name,
    314 		    user, args, &rfd2);
    315 	}
    316 #else /* KERBEROS */
    317 
    318 #ifdef IN_RCMD
    319 	rem = orcmd(&host, sp->s_port, locuser ? locuser :
    320 #else
    321 	rem = rcmd(&host, sp->s_port,
    322 #endif
    323 	    pw->pw_name, user,
    324 	    args, &rfd2);
    325 #endif /* KERBEROS */
    326 
    327 	if (rem < 0)
    328 		exit(1);
    329 
    330 	if (rfd2 < 0)
    331 		errx(1, "can't establish stderr");
    332 	if (dflag) {
    333 		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
    334 		    sizeof(one)) < 0)
    335 			warn("setsockopt remote");
    336 		if (setsockopt(rfd2, SOL_SOCKET, SO_DEBUG, &one,
    337 		    sizeof(one)) < 0)
    338 			warn("setsockopt stderr");
    339 	}
    340 
    341 	(void)setuid(uid);
    342 	omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGTERM));
    343 	if (signal(SIGINT, SIG_IGN) != SIG_IGN)
    344 		(void)signal(SIGINT, sendsig);
    345 	if (signal(SIGQUIT, SIG_IGN) != SIG_IGN)
    346 		(void)signal(SIGQUIT, sendsig);
    347 	if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
    348 		(void)signal(SIGTERM, sendsig);
    349 
    350 	if (!nflag) {
    351 		pid = fork();
    352 		if (pid < 0)
    353 			err(1, "fork");
    354 	}
    355 
    356 #ifdef KERBEROS
    357 #ifdef CRYPT
    358 	if (!doencrypt)
    359 #endif
    360 #endif
    361 	{
    362 		(void)ioctl(rfd2, FIONBIO, &one);
    363 		(void)ioctl(rem, FIONBIO, &one);
    364 	}
    365 
    366 	talk(nflag, omask, pid, rem);
    367 
    368 	if (!nflag)
    369 		(void)kill(pid, SIGKILL);
    370 	exit(0);
    371 }
    372 
    373 void
    374 talk(nflag, omask, pid, rem)
    375 	int nflag;
    376 	long omask;
    377 	pid_t pid;
    378 	int rem;
    379 {
    380 	int cc, wc, nfds;
    381 	struct pollfd fds[2], *fdp = &fds[0];
    382 	char *bp, buf[BUFSIZ];
    383 
    384 	if (!nflag && pid == 0) {
    385 		(void)close(rfd2);
    386 
    387 reread:		errno = 0;
    388 		if ((cc = read(0, buf, sizeof buf)) <= 0)
    389 			goto done;
    390 		bp = buf;
    391 
    392 rewrite:	fdp->events = POLLOUT;
    393 		fdp->fd = rem;
    394 		if (poll(fdp, 1, 0) < 0) {
    395 			if (errno != EINTR)
    396 				err(1, "poll");
    397 			goto rewrite;
    398 		}
    399 		if ((fdp->revents & POLLOUT) == 0)
    400 			goto rewrite;
    401 #ifdef KERBEROS
    402 #ifdef CRYPT
    403 		if (doencrypt)
    404 			wc = des_write(rem, bp, cc);
    405 		else
    406 #endif
    407 #endif
    408 			wc = write(rem, bp, cc);
    409 		if (wc < 0) {
    410 			if (errno == EWOULDBLOCK)
    411 				goto rewrite;
    412 			goto done;
    413 		}
    414 		bp += wc;
    415 		cc -= wc;
    416 		if (cc == 0)
    417 			goto reread;
    418 		goto rewrite;
    419 done:
    420 		(void)shutdown(rem, 1);
    421 		exit(0);
    422 	}
    423 
    424 	(void)sigsetmask(omask);
    425 	fds[0].events = fds[1].events = POLLIN;
    426 	fds[0].fd = rfd2;
    427 	fds[1].fd = rem;
    428 	fdp = &fds[0];
    429 	nfds = 2;
    430 	do {
    431 		if (poll(fdp, nfds, 0) < 0) {
    432 			if (errno != EINTR)
    433 				err(1, "poll");
    434 			continue;
    435 		}
    436 		if (fds[0].events == POLLIN && (fds[0].revents & POLLIN)) {
    437 			errno = 0;
    438 #ifdef KERBEROS
    439 #ifdef CRYPT
    440 			if (doencrypt)
    441 				cc = des_read(rfd2, buf, sizeof buf);
    442 			else
    443 #endif
    444 #endif
    445 				cc = read(rfd2, buf, sizeof buf);
    446 			if (cc <= 0) {
    447 				if (errno != EWOULDBLOCK) {
    448 					nfds--;
    449 					fds[0].events = 0;
    450 					fdp = &fds[1];
    451 				}
    452 			} else
    453 				(void)write(2, buf, cc);
    454 		}
    455 		if (fds[1].events == POLLIN && (fds[1].revents & POLLIN)) {
    456 			errno = 0;
    457 #ifdef KERBEROS
    458 #ifdef CRYPT
    459 			if (doencrypt)
    460 				cc = des_read(rem, buf, sizeof buf);
    461 			else
    462 #endif
    463 #endif
    464 				cc = read(rem, buf, sizeof buf);
    465 			if (cc <= 0) {
    466 				if (errno != EWOULDBLOCK) {
    467 					nfds--;
    468 					fds[1].events = 0;
    469 				}
    470 			} else
    471 				(void)write(1, buf, cc);
    472 		}
    473 	} while (nfds);
    474 }
    475 
    476 void
    477 sendsig(sig)
    478 	int sig;
    479 {
    480 	char signo;
    481 
    482 	signo = sig;
    483 #ifdef KERBEROS
    484 #ifdef CRYPT
    485 	if (doencrypt)
    486 		(void)des_write(rfd2, &signo, 1);
    487 	else
    488 #endif
    489 #endif
    490 		(void)write(rfd2, &signo, 1);
    491 }
    492 
    493 #ifdef KERBEROS
    494 /* VARARGS */
    495 void
    496 warning(va_alist)
    497 va_dcl
    498 {
    499 	va_list ap;
    500 	char *fmt;
    501 
    502 	(void)fprintf(stderr, "rsh: warning, using standard rsh: ");
    503 	va_start(ap);
    504 	fmt = va_arg(ap, char *);
    505 	vfprintf(stderr, fmt, ap);
    506 	va_end(ap);
    507 	(void)fprintf(stderr, ".\n");
    508 }
    509 #endif
    510 
    511 char *
    512 copyargs(argv)
    513 	char **argv;
    514 {
    515 	int cc;
    516 	char **ap, *args, *p;
    517 
    518 	cc = 0;
    519 	for (ap = argv; *ap; ++ap)
    520 		cc += strlen(*ap) + 1;
    521 	if (!(args = malloc((u_int)cc)))
    522 		errx(1, "%s", strerror(ENOMEM));
    523 	for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
    524 		(void)strcpy(p, *ap);
    525 		p += strlen(p);
    526 		if (ap[1])
    527 			*p++ = ' ';
    528 	}
    529 	*p = '\0';
    530 	return (args);
    531 }
    532 
    533 void
    534 usage()
    535 {
    536 
    537 	(void)fprintf(stderr,
    538 	    "usage: %s [-nd%s]%s[-l login]%s [login@]host %s\n", __progname,
    539 #ifdef KERBEROS
    540 #ifdef CRYPT
    541 	    "x", " [-k realm] ",
    542 #else
    543 	    "", " [-k realm] ",
    544 #endif
    545 #else
    546 	    "", " ",
    547 #endif
    548 #ifdef IN_RCMD
    549 	    " [-u locuser]", "command"
    550 #else
    551 	    "", "[command]"
    552 #endif
    553 	    );
    554 	exit(1);
    555 }
    556