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rsh.c revision 1.12 
      1 /*	$NetBSD: rsh.c,v 1.12 1997/07/20 20:44:23 christos 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 #include <sys/cdefs.h>
     37 #ifndef lint
     38 __COPYRIGHT("@(#) 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 #if 0
     44 static char sccsid[] = "@(#)rsh.c	8.4 (Berkeley) 4/29/95";
     45 #else
     46 __RCSID("$NetBSD: rsh.c,v 1.12 1997/07/20 20:44:23 christos Exp $");
     47 #endif
     48 #endif /* not lint */
     49 
     50 #include <sys/types.h>
     51 #include <sys/socket.h>
     52 #include <sys/ioctl.h>
     53 #include <sys/file.h>
     54 #include <poll.h>
     55 
     56 #include <netinet/in.h>
     57 #include <netdb.h>
     58 
     59 #include <err.h>
     60 #include <errno.h>
     61 #include <pwd.h>
     62 #include <signal.h>
     63 #include <stdio.h>
     64 #include <stdlib.h>
     65 #include <string.h>
     66 #include <unistd.h>
     67 #ifdef __STDC__
     68 #include <stdarg.h>
     69 #else
     70 #include <varargs.h>
     71 #endif
     72 
     73 #include "pathnames.h"
     74 
     75 #ifdef KERBEROS
     76 #include <kerberosIV/des.h>
     77 #include <kerberosIV/krb.h>
     78 
     79 CREDENTIALS cred;
     80 Key_schedule schedule;
     81 int use_kerberos = 1, doencrypt;
     82 char dst_realm_buf[REALM_SZ], *dest_realm;
     83 
     84 void	warning __P((const char *, ...));
     85 #endif
     86 
     87 /*
     88  * rsh - remote shell
     89  */
     90 extern	char *__progname;		/* XXX */
     91 int	remerr;
     92 
     93 static int sigs[] = { SIGINT, SIGTERM, SIGQUIT };
     94 
     95 char   *copyargs __P((char **));
     96 void	sendsig __P((int));
     97 int	checkfd __P((struct pollfd *, int));
     98 void	talk __P((int, sigset_t *, pid_t, int));
     99 void	usage __P((void));
    100 int	main __P((int, char **));
    101 #ifdef IN_RCMD
    102 int	 orcmd __P((char **, int, const char *,
    103     const char *, const char *, int *));
    104 #endif
    105 
    106 int
    107 main(argc, argv)
    108 	int argc;
    109 	char **argv;
    110 {
    111 	struct passwd *pw;
    112 	struct servent *sp;
    113 	sigset_t oset, nset;
    114 
    115 #ifdef IN_RCMD
    116 	char	*locuser = 0, *loop;
    117 #endif /* IN_RCMD */
    118 	int argoff, asrsh, ch, dflag, nflag, one, rem, i;
    119 	pid_t pid;
    120 	uid_t uid;
    121 	char *args, *host, *p, *user, *name;
    122 
    123 	argoff = asrsh = dflag = nflag = 0;
    124 	one = 1;
    125 	host = user = NULL;
    126 
    127 #ifndef IN_RCMD
    128 	/*
    129 	 * If called as something other than "rsh" use it as the host name,
    130 	 * only for rsh.
    131 	 */
    132 	p = __progname;
    133 	if (strcmp(p, "rsh") == 0)
    134 		asrsh = 1;
    135 	else
    136 		host = p;
    137 #endif /* IN_RCMD */
    138 
    139 	/* handle "rsh host flags" */
    140 	if (!host && argc > 2 && argv[1][0] != '-') {
    141 		host = argv[1];
    142 		argoff = 1;
    143 	}
    144 
    145 #ifdef IN_RCMD
    146 	if ((loop = getenv("RCMD_LOOP")) && strcmp(loop, "YES") == 0)
    147 		warnx("rcmd appears to be looping!");
    148 
    149 	putenv("RCMD_LOOP=YES");
    150 
    151 # ifdef KERBEROS
    152 #  ifdef CRYPT
    153 #   define	OPTIONS	"8KLdek:l:nu:wx"
    154 #  else
    155 #   define	OPTIONS	"8KLdek:l:nu:w"
    156 #  endif
    157 # else
    158 #  define	OPTIONS	"8KLdel:nu:w"
    159 # endif
    160 
    161 #else /* IN_RCMD */
    162 
    163 # ifdef KERBEROS
    164 #  ifdef CRYPT
    165 #   define	OPTIONS	"8KLdek:l:nwx"
    166 #  else
    167 #   define	OPTIONS	"8KLdek:l:nw"
    168 #  endif
    169 # else
    170 #  define	OPTIONS	"8KLdel:nw"
    171 # endif
    172 
    173 #endif /* IN_RCMD */
    174 
    175 	if (!(pw = getpwuid(uid = getuid())))
    176 		errx(1, "unknown user id");
    177 
    178 	if ((name = strdup(pw->pw_name)) == NULL)
    179 		err(1, "malloc");
    180 	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
    181 		switch(ch) {
    182 		case 'K':
    183 #ifdef KERBEROS
    184 			use_kerberos = 0;
    185 #endif
    186 			break;
    187 		case 'L':	/* -8Lew are ignored to allow rlogin aliases */
    188 		case 'e':
    189 		case 'w':
    190 		case '8':
    191 			break;
    192 		case 'd':
    193 			dflag = 1;
    194 			break;
    195 		case 'l':
    196 			user = optarg;
    197 			break;
    198 #ifdef KERBEROS
    199 		case 'k':
    200 			dest_realm = dst_realm_buf;
    201 			strncpy(dest_realm, optarg, REALM_SZ);
    202 			break;
    203 #endif
    204 		case 'n':
    205 			nflag = 1;
    206 			break;
    207 #ifdef IN_RCMD
    208 		case 'u':
    209 			if (getuid() != 0 && optarg && name &&
    210 			    strcmp(name, optarg) != 0)
    211 				errx(1,"only super user can use the -u option");
    212 			locuser = optarg;
    213 			break;
    214 #endif /* IN_RCMD */
    215 #ifdef KERBEROS
    216 #ifdef CRYPT
    217 		case 'x':
    218 			doencrypt = 1;
    219 			des_set_key((des_cblock *) cred.session, schedule);
    220 			break;
    221 #endif
    222 #endif
    223 		case '?':
    224 		default:
    225 			usage();
    226 		}
    227 	optind += argoff;
    228 
    229 	/* if haven't gotten a host yet, do so */
    230 	if (!host && !(host = argv[optind++]))
    231 		usage();
    232 
    233 	/* if no further arguments, must have been called as rlogin. */
    234 	if (!argv[optind]) {
    235 #ifdef IN_RCMD
    236 		usage();
    237 #else
    238 		if (asrsh)
    239 			*argv = "rlogin";
    240 		execv(_PATH_RLOGIN, argv);
    241 		err(1, "can't exec %s", _PATH_RLOGIN);
    242 #endif
    243 	}
    244 
    245 	argc -= optind;
    246 	argv += optind;
    247 
    248 	/* Accept user1@host format, though "-l user2" overrides user1 */
    249 	p = strchr(host, '@');
    250 	if (p) {
    251 		*p = '\0';
    252 		if (!user && p > host)
    253 			user = host;
    254 		host = p + 1;
    255 		if (*host == '\0')
    256 			usage();
    257 	}
    258 	if (!user)
    259 		user = name;
    260 
    261 #ifdef KERBEROS
    262 #ifdef CRYPT
    263 	/* -x turns off -n */
    264 	if (doencrypt)
    265 		nflag = 0;
    266 #endif
    267 #endif
    268 
    269 	args = copyargs(argv);
    270 
    271 	sp = NULL;
    272 #ifdef KERBEROS
    273 	if (use_kerberos) {
    274 		sp = getservbyname((doencrypt ? "ekshell" : "kshell"), "tcp");
    275 		if (sp == NULL) {
    276 			use_kerberos = 0;
    277 			warning("can't get entry for %s/tcp service",
    278 			    doencrypt ? "ekshell" : "kshell");
    279 		}
    280 	}
    281 #endif
    282 	if (sp == NULL)
    283 		sp = getservbyname("shell", "tcp");
    284 	if (sp == NULL)
    285 		errx(1, "shell/tcp: unknown service");
    286 
    287 #ifdef KERBEROS
    288 try_connect:
    289 	if (use_kerberos) {
    290 #if 1
    291 		struct hostent *hp;
    292 
    293 		/* fully qualify hostname (needed for krb_realmofhost) */
    294 		hp = gethostbyname(host);
    295 		if (hp != NULL && !(host = strdup(hp->h_name)))
    296 			err(1, "strdup");
    297 #endif
    298 
    299 		rem = KSUCCESS;
    300 		errno = 0;
    301 		if (dest_realm == NULL)
    302 			dest_realm = krb_realmofhost(host);
    303 
    304 #ifdef CRYPT
    305 		if (doencrypt)
    306 			rem = krcmd_mutual(&host, sp->s_port, user, args,
    307 			    &remerr, dest_realm, &cred, schedule);
    308 		else
    309 #endif
    310 			rem = krcmd(&host, sp->s_port, user, args, &remerr,
    311 			    dest_realm);
    312 		if (rem < 0) {
    313 			use_kerberos = 0;
    314 			sp = getservbyname("shell", "tcp");
    315 			if (sp == NULL)
    316 				errx(1, "shell/tcp: unknown service");
    317 			if (errno == ECONNREFUSED)
    318 				warning("remote host doesn't support Kerberos");
    319 			if (errno == ENOENT)
    320 				warning("can't provide Kerberos auth data");
    321 			goto try_connect;
    322 		}
    323 	} else {
    324 		if (doencrypt)
    325 			errx(1, "the -x flag requires Kerberos authentication.");
    326 #ifdef IN_RCMD
    327 		rem = orcmd(&host, sp->s_port, locuser ? locuser :
    328 #else
    329 		rem = rcmd(&host, sp->s_port,
    330 #endif
    331 		    name,
    332 		    user, args, &remerr);
    333 	}
    334 #else /* KERBEROS */
    335 
    336 #ifdef IN_RCMD
    337 	rem = orcmd(&host, sp->s_port, locuser ? locuser :
    338 #else
    339 	rem = rcmd(&host, sp->s_port,
    340 #endif
    341 	    name, user, args, &remerr);
    342 #endif /* KERBEROS */
    343 	(void)free(name);
    344 
    345 	if (rem < 0)
    346 		exit(1);
    347 
    348 	if (remerr < 0)
    349 		errx(1, "can't establish stderr");
    350 	if (dflag) {
    351 		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
    352 		    sizeof(one)) < 0)
    353 			warn("setsockopt remote");
    354 		if (setsockopt(remerr, SOL_SOCKET, SO_DEBUG, &one,
    355 		    sizeof(one)) < 0)
    356 			warn("setsockopt stderr");
    357 	}
    358 
    359 	(void) setuid(uid);
    360 
    361 	(void) sigemptyset(&nset);
    362 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++)
    363 		(void) sigaddset(&nset, sigs[i]);
    364 
    365 	(void) sigprocmask(SIG_BLOCK, &nset, &oset);
    366 
    367 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++) {
    368 		struct sigaction sa;
    369 
    370 		if (sa.sa_handler != SIG_IGN) {
    371 			sa.sa_handler = sendsig;
    372 			(void) sigaction(sigs[i], &sa, NULL);
    373 		}
    374 	}
    375 
    376 	if (!nflag) {
    377 		pid = fork();
    378 		if (pid < 0)
    379 			err(1, "fork");
    380 	}
    381 	else
    382 		pid = -1;
    383 
    384 #if defined(KERBEROS) && defined(CRYPT)
    385 	if (!doencrypt)
    386 #endif
    387 	{
    388 		(void)ioctl(remerr, FIONBIO, &one);
    389 		(void)ioctl(rem, FIONBIO, &one);
    390 	}
    391 
    392 	talk(nflag, &oset, pid, rem);
    393 
    394 	if (!nflag)
    395 		(void)kill(pid, SIGKILL);
    396 	exit(0);
    397 }
    398 
    399 int
    400 checkfd(fdp, outfd)
    401 	struct pollfd *fdp;
    402 	int outfd;
    403 {
    404 	int nr, nw;
    405 	char buf[BUFSIZ];
    406 
    407 	if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    408 		return -1;
    409 
    410 	if ((fdp->revents & POLLIN) == 0)
    411 		return 0;
    412 
    413 	errno = 0;
    414 #if defined(KERBEROS) && defined(CRYPT)
    415 	if (doencrypt)
    416 		nr = des_read(fdp->fd, buf, sizeof buf);
    417 	else
    418 #endif
    419 		nr = read(fdp->fd, buf, sizeof buf);
    420 
    421 	if (nr <= 0) {
    422 		if (errno != EAGAIN)
    423 			return -1;
    424 		else
    425 			return 0;
    426 	}
    427 	else {
    428 		char *bc = buf;
    429 		while (nr) {
    430 			if ((nw = write(outfd, bc, nr)) <= 0)
    431 				return -1;
    432 			nr -= nw;
    433 			bc += nw;
    434 		}
    435 		return 0;
    436 	}
    437 }
    438 
    439 void
    440 talk(nflag, oset, pid, rem)
    441 	int nflag;
    442 	sigset_t *oset;
    443 	pid_t pid;
    444 	int rem;
    445 {
    446 	int nr, nw, nfds;
    447 	struct pollfd fds[2], *fdp = &fds[0];
    448 	char *bp, buf[BUFSIZ];
    449 
    450 
    451 	if (!nflag && pid == 0) {
    452 		(void)close(remerr);
    453 
    454 		fdp->events = POLLOUT|POLLNVAL|POLLERR|POLLHUP;
    455 		fdp->fd = rem;
    456 		nr = 0;
    457 		bp = buf;
    458 
    459 		for (;;) {
    460 			errno = 0;
    461 
    462 			if (nr == 0) {
    463 				if ((nr = read(0, buf, sizeof buf)) == 0)
    464 					goto done;
    465 				if (nr == -1) {
    466 					if (errno == EIO)
    467 						goto done;
    468 					if (errno == EINTR)
    469 						continue;
    470 					err(1, "read");
    471 				}
    472 				bp = buf;
    473 			}
    474 
    475 rewrite:		if (poll(fdp, 1, INFTIM) == -1) {
    476 				if (errno != EINTR)
    477 					err(1, "poll");
    478 				goto rewrite;
    479 			}
    480 
    481 			if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    482 				err(1, "poll");
    483 
    484 			if ((fdp->revents & POLLOUT) == 0)
    485 				goto rewrite;
    486 
    487 #if defined(KERBEROS) && defined(CRYPT)
    488 			if (doencrypt)
    489 				nw = des_write(rem, bp, nr);
    490 			else
    491 #endif
    492 				nw = write(rem, bp, nr);
    493 
    494 			if (nw < 0) {
    495 				if (errno == EAGAIN)
    496 					continue;
    497 				err(1, "write");
    498 			}
    499 			bp += nw;
    500 			nr -= nw;
    501 		}
    502 done:
    503 		(void)shutdown(rem, 1);
    504 		exit(0);
    505 	}
    506 
    507 	(void) sigprocmask(SIG_SETMASK, oset, NULL);
    508 	fds[0].events = fds[1].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
    509 	fds[0].fd = remerr;
    510 	fds[1].fd = rem;
    511 	fdp = &fds[0];
    512 	nfds = 2;
    513 	do {
    514 		if (poll(fdp, nfds, INFTIM) == -1) {
    515 			if (errno != EINTR)
    516 				err(1, "poll");
    517 			continue;
    518 		}
    519 		if (fds[0].events != 0 && checkfd(&fds[0], 2) == -1) {
    520 			nfds--;
    521 			fds[0].events = 0;
    522 			fdp = &fds[1];
    523 		}
    524 		if (fds[1].events != 0 && checkfd(&fds[1], 1) == -1) {
    525 			nfds--;
    526 			fds[1].events = 0;
    527 		}
    528 	}
    529 	while (nfds);
    530 }
    531 
    532 void
    533 sendsig(sig)
    534 	int sig;
    535 {
    536 	char signo;
    537 
    538 	signo = sig;
    539 #ifdef KERBEROS
    540 #ifdef CRYPT
    541 	if (doencrypt)
    542 		(void)des_write(remerr, &signo, 1);
    543 	else
    544 #endif
    545 #endif
    546 		(void)write(remerr, &signo, 1);
    547 }
    548 
    549 #ifdef KERBEROS
    550 /* VARARGS */
    551 void
    552 #ifdef __STDC__
    553 warning(const char *fmt, ...)
    554 #else
    555 warning(va_alist)
    556 	va_dcl
    557 #endif
    558 {
    559 	va_list ap;
    560 #ifndef __STDC__
    561 	const char *fmt;
    562 
    563 	va_start(ap);
    564 	fmt = va_arg(ap, const char *);
    565 #else
    566 	va_start(ap, fmt);
    567 #endif
    568 
    569 	(void) fprintf(stderr, "%s: warning, using standard rsh: ", __progname);
    570 	(void) vfprintf(stderr, fmt, ap);
    571 	va_end(ap);
    572 	(void) fprintf(stderr, ".\n");
    573 }
    574 #endif
    575 
    576 char *
    577 copyargs(argv)
    578 	char **argv;
    579 {
    580 	int cc;
    581 	char **ap, *args, *p;
    582 
    583 	cc = 0;
    584 	for (ap = argv; *ap; ++ap)
    585 		cc += strlen(*ap) + 1;
    586 	if (!(args = malloc((u_int)cc)))
    587 		err(1, "malloc");
    588 	for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
    589 		(void)strcpy(p, *ap);
    590 		p += strlen(p);
    591 		if (ap[1])
    592 			*p++ = ' ';
    593 	}
    594 	*p = '\0';
    595 	return (args);
    596 }
    597 
    598 void
    599 usage()
    600 {
    601 
    602 	(void)fprintf(stderr,
    603 	    "usage: %s [-nd%s]%s[-l login]%s [login@]host %s\n", __progname,
    604 #ifdef KERBEROS
    605 #ifdef CRYPT
    606 	    "x", " [-k realm] ",
    607 #else
    608 	    "", " [-k realm] ",
    609 #endif
    610 #else
    611 	    "", " ",
    612 #endif
    613 #ifdef IN_RCMD
    614 	    " [-u locuser]", "command"
    615 #else
    616 	    "", "[command]"
    617 #endif
    618 	    );
    619 	exit(1);
    620 }
    621