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rsh.c revision 1.10 
      1 /*	$NetBSD: rsh.c,v 1.10 1997/06/16 20:54:16 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 #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 1.10 1997/06/16 20:54:16 christos 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 #ifdef __STDC__
     65 #include <stdarg.h>
     66 #else
     67 #include <varargs.h>
     68 #endif
     69 
     70 #include "pathnames.h"
     71 
     72 #ifdef KERBEROS
     73 #include <kerberosIV/des.h>
     74 #include <kerberosIV/krb.h>
     75 
     76 CREDENTIALS cred;
     77 Key_schedule schedule;
     78 int use_kerberos = 1, doencrypt;
     79 char dst_realm_buf[REALM_SZ], *dest_realm;
     80 
     81 void	warning __P((const char *, ...));
     82 #endif
     83 
     84 /*
     85  * rsh - remote shell
     86  */
     87 extern	char *__progname;		/* XXX */
     88 int	remerr;
     89 
     90 static int sigs[] = { SIGINT, SIGTERM, SIGQUIT };
     91 
     92 char   *copyargs __P((char **));
     93 void	sendsig __P((int));
     94 int	checkfd __P((struct pollfd *, int));
     95 void	talk __P((int, sigset_t *, pid_t, int));
     96 void	usage __P((void));
     97 int	main __P((int, char **));
     98 
     99 int
    100 main(argc, argv)
    101 	int argc;
    102 	char **argv;
    103 {
    104 	struct passwd *pw;
    105 	struct servent *sp;
    106 	sigset_t oset, nset;
    107 
    108 #ifdef IN_RCMD
    109 	char	*locuser = 0, *loop;
    110 #endif /* IN_RCMD */
    111 	int argoff, asrsh, ch, dflag, nflag, one, rem, i;
    112 	pid_t pid;
    113 	uid_t uid;
    114 	char *args, *host, *p, *user, *name;
    115 
    116 	argoff = asrsh = dflag = nflag = 0;
    117 	one = 1;
    118 	host = user = NULL;
    119 
    120 #ifndef IN_RCMD
    121 	/*
    122 	 * If called as something other than "rsh" use it as the host name,
    123 	 * only for rsh.
    124 	 */
    125 	p = __progname;
    126 	if (strcmp(p, "rsh") == 0)
    127 		asrsh = 1;
    128 	else
    129 		host = p;
    130 #endif /* IN_RCMD */
    131 
    132 	/* handle "rsh host flags" */
    133 	if (!host && argc > 2 && argv[1][0] != '-') {
    134 		host = argv[1];
    135 		argoff = 1;
    136 	}
    137 
    138 #ifdef IN_RCMD
    139 	if ((loop = getenv("RCMD_LOOP")) && strcmp(loop, "YES") == 0)
    140 		warnx("rcmd appears to be looping!");
    141 
    142 	putenv("RCMD_LOOP=YES");
    143 
    144 # ifdef KERBEROS
    145 #  ifdef CRYPT
    146 #   define	OPTIONS	"8KLdek:l:nu:wx"
    147 #  else
    148 #   define	OPTIONS	"8KLdek:l:nu:w"
    149 #  endif
    150 # else
    151 #  define	OPTIONS	"8KLdel:nu:w"
    152 # endif
    153 
    154 #else /* IN_RCMD */
    155 
    156 # ifdef KERBEROS
    157 #  ifdef CRYPT
    158 #   define	OPTIONS	"8KLdek:l:nwx"
    159 #  else
    160 #   define	OPTIONS	"8KLdek:l:nw"
    161 #  endif
    162 # else
    163 #  define	OPTIONS	"8KLdel:nw"
    164 # endif
    165 
    166 #endif /* IN_RCMD */
    167 
    168 	if (!(pw = getpwuid(uid = getuid())))
    169 		errx(1, "unknown user id");
    170 
    171 	if ((name = strdup(pw->pw_name)) == NULL)
    172 		err(1, "malloc");
    173 	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
    174 		switch(ch) {
    175 		case 'K':
    176 #ifdef KERBEROS
    177 			use_kerberos = 0;
    178 #endif
    179 			break;
    180 		case 'L':	/* -8Lew are ignored to allow rlogin aliases */
    181 		case 'e':
    182 		case 'w':
    183 		case '8':
    184 			break;
    185 		case 'd':
    186 			dflag = 1;
    187 			break;
    188 		case 'l':
    189 			user = optarg;
    190 			break;
    191 #ifdef KERBEROS
    192 		case 'k':
    193 			dest_realm = dst_realm_buf;
    194 			strncpy(dest_realm, optarg, REALM_SZ);
    195 			break;
    196 #endif
    197 		case 'n':
    198 			nflag = 1;
    199 			break;
    200 #ifdef IN_RCMD
    201 		case 'u':
    202 			if (getuid() != 0 && optarg && name &&
    203 			    strcmp(name, optarg) != 0)
    204 				errx(1,"only super user can use the -u option");
    205 			locuser = optarg;
    206 			break;
    207 #endif /* IN_RCMD */
    208 #ifdef KERBEROS
    209 #ifdef CRYPT
    210 		case 'x':
    211 			doencrypt = 1;
    212 			des_set_key((des_cblock *) cred.session, schedule);
    213 			break;
    214 #endif
    215 #endif
    216 		case '?':
    217 		default:
    218 			usage();
    219 		}
    220 	optind += argoff;
    221 
    222 	/* if haven't gotten a host yet, do so */
    223 	if (!host && !(host = argv[optind++]))
    224 		usage();
    225 
    226 	/* if no further arguments, must have been called as rlogin. */
    227 	if (!argv[optind]) {
    228 #ifdef IN_RCMD
    229 		usage();
    230 #else
    231 		if (asrsh)
    232 			*argv = "rlogin";
    233 		execv(_PATH_RLOGIN, argv);
    234 		err(1, "can't exec %s", _PATH_RLOGIN);
    235 #endif
    236 	}
    237 
    238 	argc -= optind;
    239 	argv += optind;
    240 
    241 	/* Accept user1@host format, though "-l user2" overrides user1 */
    242 	p = strchr(host, '@');
    243 	if (p) {
    244 		*p = '\0';
    245 		if (!user && p > host)
    246 			user = host;
    247 		host = p + 1;
    248 		if (*host == '\0')
    249 			usage();
    250 	}
    251 	if (!user)
    252 		user = name;
    253 
    254 #ifdef KERBEROS
    255 #ifdef CRYPT
    256 	/* -x turns off -n */
    257 	if (doencrypt)
    258 		nflag = 0;
    259 #endif
    260 #endif
    261 
    262 	args = copyargs(argv);
    263 
    264 	sp = NULL;
    265 #ifdef KERBEROS
    266 	if (use_kerberos) {
    267 		sp = getservbyname((doencrypt ? "ekshell" : "kshell"), "tcp");
    268 		if (sp == NULL) {
    269 			use_kerberos = 0;
    270 			warning("can't get entry for %s/tcp service",
    271 			    doencrypt ? "ekshell" : "kshell");
    272 		}
    273 	}
    274 #endif
    275 	if (sp == NULL)
    276 		sp = getservbyname("shell", "tcp");
    277 	if (sp == NULL)
    278 		errx(1, "shell/tcp: unknown service");
    279 
    280 #ifdef KERBEROS
    281 try_connect:
    282 	if (use_kerberos) {
    283 #if 1
    284 		struct hostent *hp;
    285 
    286 		/* fully qualify hostname (needed for krb_realmofhost) */
    287 		hp = gethostbyname(host);
    288 		if (hp != NULL && !(host = strdup(hp->h_name)))
    289 			err(1, "strdup");
    290 #endif
    291 
    292 		rem = KSUCCESS;
    293 		errno = 0;
    294 		if (dest_realm == NULL)
    295 			dest_realm = krb_realmofhost(host);
    296 
    297 #ifdef CRYPT
    298 		if (doencrypt)
    299 			rem = krcmd_mutual(&host, sp->s_port, user, args,
    300 			    &remerr, dest_realm, &cred, schedule);
    301 		else
    302 #endif
    303 			rem = krcmd(&host, sp->s_port, user, args, &remerr,
    304 			    dest_realm);
    305 		if (rem < 0) {
    306 			use_kerberos = 0;
    307 			sp = getservbyname("shell", "tcp");
    308 			if (sp == NULL)
    309 				errx(1, "shell/tcp: unknown service");
    310 			if (errno == ECONNREFUSED)
    311 				warning("remote host doesn't support Kerberos");
    312 			if (errno == ENOENT)
    313 				warning("can't provide Kerberos auth data");
    314 			goto try_connect;
    315 		}
    316 	} else {
    317 		if (doencrypt)
    318 			errx(1, "the -x flag requires Kerberos authentication.");
    319 #ifdef IN_RCMD
    320 		rem = orcmd(&host, sp->s_port, locuser ? locuser :
    321 #else
    322 		rem = rcmd(&host, sp->s_port,
    323 #endif
    324 		    name,
    325 		    user, args, &remerr);
    326 	}
    327 #else /* KERBEROS */
    328 
    329 #ifdef IN_RCMD
    330 	rem = orcmd(&host, sp->s_port, locuser ? locuser :
    331 #else
    332 	rem = rcmd(&host, sp->s_port,
    333 #endif
    334 	    name, user, args, &remerr);
    335 #endif /* KERBEROS */
    336 	(void)free(name);
    337 
    338 	if (rem < 0)
    339 		exit(1);
    340 
    341 	if (remerr < 0)
    342 		errx(1, "can't establish stderr");
    343 	if (dflag) {
    344 		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
    345 		    sizeof(one)) < 0)
    346 			warn("setsockopt remote");
    347 		if (setsockopt(remerr, SOL_SOCKET, SO_DEBUG, &one,
    348 		    sizeof(one)) < 0)
    349 			warn("setsockopt stderr");
    350 	}
    351 
    352 	(void) setuid(uid);
    353 
    354 	(void) sigemptyset(&nset);
    355 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++)
    356 		(void) sigaddset(&nset, sigs[i]);
    357 
    358 	(void) sigprocmask(SIG_BLOCK, &nset, &oset);
    359 
    360 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++) {
    361 		struct sigaction sa;
    362 
    363 		if (sa.sa_handler != SIG_IGN) {
    364 			sa.sa_handler = sendsig;
    365 			(void) sigaction(sigs[i], &sa, NULL);
    366 		}
    367 	}
    368 
    369 	if (!nflag) {
    370 		pid = fork();
    371 		if (pid < 0)
    372 			err(1, "fork");
    373 	}
    374 	else
    375 		pid = -1;
    376 
    377 #if defined(KERBEROS) && defined(CRYPT)
    378 	if (!doencrypt)
    379 #endif
    380 	{
    381 		(void)ioctl(remerr, FIONBIO, &one);
    382 		(void)ioctl(rem, FIONBIO, &one);
    383 	}
    384 
    385 	talk(nflag, &oset, pid, rem);
    386 
    387 	if (!nflag)
    388 		(void)kill(pid, SIGKILL);
    389 	exit(0);
    390 }
    391 
    392 int
    393 checkfd(fdp, outfd)
    394 	struct pollfd *fdp;
    395 	int outfd;
    396 {
    397 	int nr, nw;
    398 	char buf[BUFSIZ];
    399 
    400 	if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    401 		return -1;
    402 
    403 	if ((fdp->revents & POLLIN) == 0)
    404 		return 0;
    405 
    406 	errno = 0;
    407 #if defined(KERBEROS) && defined(CRYPT)
    408 	if (doencrypt)
    409 		nr = des_read(fdp->fd, buf, sizeof buf);
    410 	else
    411 #endif
    412 		nr = read(fdp->fd, buf, sizeof buf);
    413 
    414 	if (nr <= 0) {
    415 		if (errno != EAGAIN)
    416 			return -1;
    417 		else
    418 			return 0;
    419 	}
    420 	else {
    421 		char *bc = buf;
    422 		while (nr) {
    423 			if ((nw = write(outfd, bc, nr)) <= 0)
    424 				return -1;
    425 			nr -= nw;
    426 			bc += nw;
    427 		}
    428 		return 0;
    429 	}
    430 }
    431 
    432 void
    433 talk(nflag, oset, pid, rem)
    434 	int nflag;
    435 	sigset_t *oset;
    436 	pid_t pid;
    437 	int rem;
    438 {
    439 	int nr, nw, nfds;
    440 	struct pollfd fds[2], *fdp = &fds[0];
    441 	char *bp, buf[BUFSIZ];
    442 
    443 
    444 	if (!nflag && pid == 0) {
    445 		(void)close(remerr);
    446 
    447 		fdp->events = POLLOUT|POLLNVAL|POLLERR|POLLHUP;
    448 		fdp->fd = rem;
    449 		nr = 0;
    450 		bp = buf;
    451 
    452 		for (;;) {
    453 			errno = 0;
    454 
    455 			if (nr == 0) {
    456 				if ((nr = read(0, buf, sizeof buf)) == 0)
    457 					goto done;
    458 				if (nr == -1) {
    459 					if (errno == EIO)
    460 						goto done;
    461 					if (errno == EINTR)
    462 						continue;
    463 					err(1, "read");
    464 				}
    465 				bp = buf;
    466 			}
    467 
    468 rewrite:		if (poll(fdp, 1, INFTIM) == -1) {
    469 				if (errno != EINTR)
    470 					err(1, "poll");
    471 				goto rewrite;
    472 			}
    473 
    474 			if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    475 				err(1, "poll");
    476 
    477 			if ((fdp->revents & POLLOUT) == 0)
    478 				goto rewrite;
    479 
    480 #if defined(KERBEROS) && defined(CRYPT)
    481 			if (doencrypt)
    482 				nw = des_write(rem, bp, nr);
    483 			else
    484 #endif
    485 				nw = write(rem, bp, nr);
    486 
    487 			if (nw < 0) {
    488 				if (errno == EAGAIN)
    489 					continue;
    490 				err(1, "write");
    491 			}
    492 			bp += nw;
    493 			nr -= nw;
    494 		}
    495 done:
    496 		(void)shutdown(rem, 1);
    497 		exit(0);
    498 	}
    499 
    500 	(void) sigprocmask(SIG_SETMASK, oset, NULL);
    501 	fds[0].events = fds[1].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
    502 	fds[0].fd = remerr;
    503 	fds[1].fd = rem;
    504 	fdp = &fds[0];
    505 	nfds = 2;
    506 	do {
    507 		if (poll(fdp, nfds, INFTIM) == -1) {
    508 			if (errno != EINTR)
    509 				err(1, "poll");
    510 			continue;
    511 		}
    512 		if (fds[0].events != 0 && checkfd(&fds[0], 2) == -1) {
    513 			nfds--;
    514 			fds[0].events = 0;
    515 			fdp = &fds[1];
    516 		}
    517 		if (fds[1].events != 0 && checkfd(&fds[1], 1) == -1) {
    518 			nfds--;
    519 			fds[1].events = 0;
    520 		}
    521 	}
    522 	while (nfds);
    523 }
    524 
    525 void
    526 sendsig(sig)
    527 	int sig;
    528 {
    529 	char signo;
    530 
    531 	signo = sig;
    532 #ifdef KERBEROS
    533 #ifdef CRYPT
    534 	if (doencrypt)
    535 		(void)des_write(remerr, &signo, 1);
    536 	else
    537 #endif
    538 #endif
    539 		(void)write(remerr, &signo, 1);
    540 }
    541 
    542 #ifdef KERBEROS
    543 /* VARARGS */
    544 void
    545 #ifdef __STDC__
    546 warning(const char *fmt, ...)
    547 #else
    548 warning(va_alist)
    549 	va_dcl
    550 #endif
    551 {
    552 	va_list ap;
    553 #ifndef __STDC__
    554 	const char *fmt;
    555 
    556 	va_start(ap);
    557 	fmt = va_arg(ap, const char *);
    558 #else
    559 	va_start(ap, fmt);
    560 #endif
    561 
    562 	(void) fprintf(stderr, "%s: warning, using standard rsh: ", __progname);
    563 	(void) vfprintf(stderr, fmt, ap);
    564 	va_end(ap);
    565 	(void) fprintf(stderr, ".\n");
    566 }
    567 #endif
    568 
    569 char *
    570 copyargs(argv)
    571 	char **argv;
    572 {
    573 	int cc;
    574 	char **ap, *args, *p;
    575 
    576 	cc = 0;
    577 	for (ap = argv; *ap; ++ap)
    578 		cc += strlen(*ap) + 1;
    579 	if (!(args = malloc((u_int)cc)))
    580 		err(1, "malloc");
    581 	for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
    582 		(void)strcpy(p, *ap);
    583 		p += strlen(p);
    584 		if (ap[1])
    585 			*p++ = ' ';
    586 	}
    587 	*p = '\0';
    588 	return (args);
    589 }
    590 
    591 void
    592 usage()
    593 {
    594 
    595 	(void)fprintf(stderr,
    596 	    "usage: %s [-nd%s]%s[-l login]%s [login@]host %s\n", __progname,
    597 #ifdef KERBEROS
    598 #ifdef CRYPT
    599 	    "x", " [-k realm] ",
    600 #else
    601 	    "", " [-k realm] ",
    602 #endif
    603 #else
    604 	    "", " ",
    605 #endif
    606 #ifdef IN_RCMD
    607 	    " [-u locuser]", "command"
    608 #else
    609 	    "", "[command]"
    610 #endif
    611 	    );
    612 	exit(1);
    613 }
    614