Home | History | Annotate | Line # | Download | only in rsh
rsh.c revision 1.11 
      1 /*	$NetBSD: rsh.c,v 1.11 1997/07/06 19:31:29 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 1.11 1997/07/06 19:31:29 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 
    102 int
    103 main(argc, argv)
    104 	int argc;
    105 	char **argv;
    106 {
    107 	struct passwd *pw;
    108 	struct servent *sp;
    109 	sigset_t oset, nset;
    110 
    111 #ifdef IN_RCMD
    112 	char	*locuser = 0, *loop;
    113 #endif /* IN_RCMD */
    114 	int argoff, asrsh, ch, dflag, nflag, one, rem, i;
    115 	pid_t pid;
    116 	uid_t uid;
    117 	char *args, *host, *p, *user, *name;
    118 
    119 	argoff = asrsh = dflag = nflag = 0;
    120 	one = 1;
    121 	host = user = NULL;
    122 
    123 #ifndef IN_RCMD
    124 	/*
    125 	 * If called as something other than "rsh" use it as the host name,
    126 	 * only for rsh.
    127 	 */
    128 	p = __progname;
    129 	if (strcmp(p, "rsh") == 0)
    130 		asrsh = 1;
    131 	else
    132 		host = p;
    133 #endif /* IN_RCMD */
    134 
    135 	/* handle "rsh host flags" */
    136 	if (!host && argc > 2 && argv[1][0] != '-') {
    137 		host = argv[1];
    138 		argoff = 1;
    139 	}
    140 
    141 #ifdef IN_RCMD
    142 	if ((loop = getenv("RCMD_LOOP")) && strcmp(loop, "YES") == 0)
    143 		warnx("rcmd appears to be looping!");
    144 
    145 	putenv("RCMD_LOOP=YES");
    146 
    147 # ifdef KERBEROS
    148 #  ifdef CRYPT
    149 #   define	OPTIONS	"8KLdek:l:nu:wx"
    150 #  else
    151 #   define	OPTIONS	"8KLdek:l:nu:w"
    152 #  endif
    153 # else
    154 #  define	OPTIONS	"8KLdel:nu:w"
    155 # endif
    156 
    157 #else /* IN_RCMD */
    158 
    159 # ifdef KERBEROS
    160 #  ifdef CRYPT
    161 #   define	OPTIONS	"8KLdek:l:nwx"
    162 #  else
    163 #   define	OPTIONS	"8KLdek:l:nw"
    164 #  endif
    165 # else
    166 #  define	OPTIONS	"8KLdel:nw"
    167 # endif
    168 
    169 #endif /* IN_RCMD */
    170 
    171 	if (!(pw = getpwuid(uid = getuid())))
    172 		errx(1, "unknown user id");
    173 
    174 	if ((name = strdup(pw->pw_name)) == NULL)
    175 		err(1, "malloc");
    176 	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
    177 		switch(ch) {
    178 		case 'K':
    179 #ifdef KERBEROS
    180 			use_kerberos = 0;
    181 #endif
    182 			break;
    183 		case 'L':	/* -8Lew are ignored to allow rlogin aliases */
    184 		case 'e':
    185 		case 'w':
    186 		case '8':
    187 			break;
    188 		case 'd':
    189 			dflag = 1;
    190 			break;
    191 		case 'l':
    192 			user = optarg;
    193 			break;
    194 #ifdef KERBEROS
    195 		case 'k':
    196 			dest_realm = dst_realm_buf;
    197 			strncpy(dest_realm, optarg, REALM_SZ);
    198 			break;
    199 #endif
    200 		case 'n':
    201 			nflag = 1;
    202 			break;
    203 #ifdef IN_RCMD
    204 		case 'u':
    205 			if (getuid() != 0 && optarg && name &&
    206 			    strcmp(name, optarg) != 0)
    207 				errx(1,"only super user can use the -u option");
    208 			locuser = optarg;
    209 			break;
    210 #endif /* IN_RCMD */
    211 #ifdef KERBEROS
    212 #ifdef CRYPT
    213 		case 'x':
    214 			doencrypt = 1;
    215 			des_set_key((des_cblock *) cred.session, schedule);
    216 			break;
    217 #endif
    218 #endif
    219 		case '?':
    220 		default:
    221 			usage();
    222 		}
    223 	optind += argoff;
    224 
    225 	/* if haven't gotten a host yet, do so */
    226 	if (!host && !(host = argv[optind++]))
    227 		usage();
    228 
    229 	/* if no further arguments, must have been called as rlogin. */
    230 	if (!argv[optind]) {
    231 #ifdef IN_RCMD
    232 		usage();
    233 #else
    234 		if (asrsh)
    235 			*argv = "rlogin";
    236 		execv(_PATH_RLOGIN, argv);
    237 		err(1, "can't exec %s", _PATH_RLOGIN);
    238 #endif
    239 	}
    240 
    241 	argc -= optind;
    242 	argv += optind;
    243 
    244 	/* Accept user1@host format, though "-l user2" overrides user1 */
    245 	p = strchr(host, '@');
    246 	if (p) {
    247 		*p = '\0';
    248 		if (!user && p > host)
    249 			user = host;
    250 		host = p + 1;
    251 		if (*host == '\0')
    252 			usage();
    253 	}
    254 	if (!user)
    255 		user = name;
    256 
    257 #ifdef KERBEROS
    258 #ifdef CRYPT
    259 	/* -x turns off -n */
    260 	if (doencrypt)
    261 		nflag = 0;
    262 #endif
    263 #endif
    264 
    265 	args = copyargs(argv);
    266 
    267 	sp = NULL;
    268 #ifdef KERBEROS
    269 	if (use_kerberos) {
    270 		sp = getservbyname((doencrypt ? "ekshell" : "kshell"), "tcp");
    271 		if (sp == NULL) {
    272 			use_kerberos = 0;
    273 			warning("can't get entry for %s/tcp service",
    274 			    doencrypt ? "ekshell" : "kshell");
    275 		}
    276 	}
    277 #endif
    278 	if (sp == NULL)
    279 		sp = getservbyname("shell", "tcp");
    280 	if (sp == NULL)
    281 		errx(1, "shell/tcp: unknown service");
    282 
    283 #ifdef KERBEROS
    284 try_connect:
    285 	if (use_kerberos) {
    286 #if 1
    287 		struct hostent *hp;
    288 
    289 		/* fully qualify hostname (needed for krb_realmofhost) */
    290 		hp = gethostbyname(host);
    291 		if (hp != NULL && !(host = strdup(hp->h_name)))
    292 			err(1, "strdup");
    293 #endif
    294 
    295 		rem = KSUCCESS;
    296 		errno = 0;
    297 		if (dest_realm == NULL)
    298 			dest_realm = krb_realmofhost(host);
    299 
    300 #ifdef CRYPT
    301 		if (doencrypt)
    302 			rem = krcmd_mutual(&host, sp->s_port, user, args,
    303 			    &remerr, dest_realm, &cred, schedule);
    304 		else
    305 #endif
    306 			rem = krcmd(&host, sp->s_port, user, args, &remerr,
    307 			    dest_realm);
    308 		if (rem < 0) {
    309 			use_kerberos = 0;
    310 			sp = getservbyname("shell", "tcp");
    311 			if (sp == NULL)
    312 				errx(1, "shell/tcp: unknown service");
    313 			if (errno == ECONNREFUSED)
    314 				warning("remote host doesn't support Kerberos");
    315 			if (errno == ENOENT)
    316 				warning("can't provide Kerberos auth data");
    317 			goto try_connect;
    318 		}
    319 	} else {
    320 		if (doencrypt)
    321 			errx(1, "the -x flag requires Kerberos authentication.");
    322 #ifdef IN_RCMD
    323 		rem = orcmd(&host, sp->s_port, locuser ? locuser :
    324 #else
    325 		rem = rcmd(&host, sp->s_port,
    326 #endif
    327 		    name,
    328 		    user, args, &remerr);
    329 	}
    330 #else /* KERBEROS */
    331 
    332 #ifdef IN_RCMD
    333 	rem = orcmd(&host, sp->s_port, locuser ? locuser :
    334 #else
    335 	rem = rcmd(&host, sp->s_port,
    336 #endif
    337 	    name, user, args, &remerr);
    338 #endif /* KERBEROS */
    339 	(void)free(name);
    340 
    341 	if (rem < 0)
    342 		exit(1);
    343 
    344 	if (remerr < 0)
    345 		errx(1, "can't establish stderr");
    346 	if (dflag) {
    347 		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
    348 		    sizeof(one)) < 0)
    349 			warn("setsockopt remote");
    350 		if (setsockopt(remerr, SOL_SOCKET, SO_DEBUG, &one,
    351 		    sizeof(one)) < 0)
    352 			warn("setsockopt stderr");
    353 	}
    354 
    355 	(void) setuid(uid);
    356 
    357 	(void) sigemptyset(&nset);
    358 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++)
    359 		(void) sigaddset(&nset, sigs[i]);
    360 
    361 	(void) sigprocmask(SIG_BLOCK, &nset, &oset);
    362 
    363 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++) {
    364 		struct sigaction sa;
    365 
    366 		if (sa.sa_handler != SIG_IGN) {
    367 			sa.sa_handler = sendsig;
    368 			(void) sigaction(sigs[i], &sa, NULL);
    369 		}
    370 	}
    371 
    372 	if (!nflag) {
    373 		pid = fork();
    374 		if (pid < 0)
    375 			err(1, "fork");
    376 	}
    377 	else
    378 		pid = -1;
    379 
    380 #if defined(KERBEROS) && defined(CRYPT)
    381 	if (!doencrypt)
    382 #endif
    383 	{
    384 		(void)ioctl(remerr, FIONBIO, &one);
    385 		(void)ioctl(rem, FIONBIO, &one);
    386 	}
    387 
    388 	talk(nflag, &oset, pid, rem);
    389 
    390 	if (!nflag)
    391 		(void)kill(pid, SIGKILL);
    392 	exit(0);
    393 }
    394 
    395 int
    396 checkfd(fdp, outfd)
    397 	struct pollfd *fdp;
    398 	int outfd;
    399 {
    400 	int nr, nw;
    401 	char buf[BUFSIZ];
    402 
    403 	if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    404 		return -1;
    405 
    406 	if ((fdp->revents & POLLIN) == 0)
    407 		return 0;
    408 
    409 	errno = 0;
    410 #if defined(KERBEROS) && defined(CRYPT)
    411 	if (doencrypt)
    412 		nr = des_read(fdp->fd, buf, sizeof buf);
    413 	else
    414 #endif
    415 		nr = read(fdp->fd, buf, sizeof buf);
    416 
    417 	if (nr <= 0) {
    418 		if (errno != EAGAIN)
    419 			return -1;
    420 		else
    421 			return 0;
    422 	}
    423 	else {
    424 		char *bc = buf;
    425 		while (nr) {
    426 			if ((nw = write(outfd, bc, nr)) <= 0)
    427 				return -1;
    428 			nr -= nw;
    429 			bc += nw;
    430 		}
    431 		return 0;
    432 	}
    433 }
    434 
    435 void
    436 talk(nflag, oset, pid, rem)
    437 	int nflag;
    438 	sigset_t *oset;
    439 	pid_t pid;
    440 	int rem;
    441 {
    442 	int nr, nw, nfds;
    443 	struct pollfd fds[2], *fdp = &fds[0];
    444 	char *bp, buf[BUFSIZ];
    445 
    446 
    447 	if (!nflag && pid == 0) {
    448 		(void)close(remerr);
    449 
    450 		fdp->events = POLLOUT|POLLNVAL|POLLERR|POLLHUP;
    451 		fdp->fd = rem;
    452 		nr = 0;
    453 		bp = buf;
    454 
    455 		for (;;) {
    456 			errno = 0;
    457 
    458 			if (nr == 0) {
    459 				if ((nr = read(0, buf, sizeof buf)) == 0)
    460 					goto done;
    461 				if (nr == -1) {
    462 					if (errno == EIO)
    463 						goto done;
    464 					if (errno == EINTR)
    465 						continue;
    466 					err(1, "read");
    467 				}
    468 				bp = buf;
    469 			}
    470 
    471 rewrite:		if (poll(fdp, 1, INFTIM) == -1) {
    472 				if (errno != EINTR)
    473 					err(1, "poll");
    474 				goto rewrite;
    475 			}
    476 
    477 			if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    478 				err(1, "poll");
    479 
    480 			if ((fdp->revents & POLLOUT) == 0)
    481 				goto rewrite;
    482 
    483 #if defined(KERBEROS) && defined(CRYPT)
    484 			if (doencrypt)
    485 				nw = des_write(rem, bp, nr);
    486 			else
    487 #endif
    488 				nw = write(rem, bp, nr);
    489 
    490 			if (nw < 0) {
    491 				if (errno == EAGAIN)
    492 					continue;
    493 				err(1, "write");
    494 			}
    495 			bp += nw;
    496 			nr -= nw;
    497 		}
    498 done:
    499 		(void)shutdown(rem, 1);
    500 		exit(0);
    501 	}
    502 
    503 	(void) sigprocmask(SIG_SETMASK, oset, NULL);
    504 	fds[0].events = fds[1].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
    505 	fds[0].fd = remerr;
    506 	fds[1].fd = rem;
    507 	fdp = &fds[0];
    508 	nfds = 2;
    509 	do {
    510 		if (poll(fdp, nfds, INFTIM) == -1) {
    511 			if (errno != EINTR)
    512 				err(1, "poll");
    513 			continue;
    514 		}
    515 		if (fds[0].events != 0 && checkfd(&fds[0], 2) == -1) {
    516 			nfds--;
    517 			fds[0].events = 0;
    518 			fdp = &fds[1];
    519 		}
    520 		if (fds[1].events != 0 && checkfd(&fds[1], 1) == -1) {
    521 			nfds--;
    522 			fds[1].events = 0;
    523 		}
    524 	}
    525 	while (nfds);
    526 }
    527 
    528 void
    529 sendsig(sig)
    530 	int sig;
    531 {
    532 	char signo;
    533 
    534 	signo = sig;
    535 #ifdef KERBEROS
    536 #ifdef CRYPT
    537 	if (doencrypt)
    538 		(void)des_write(remerr, &signo, 1);
    539 	else
    540 #endif
    541 #endif
    542 		(void)write(remerr, &signo, 1);
    543 }
    544 
    545 #ifdef KERBEROS
    546 /* VARARGS */
    547 void
    548 #ifdef __STDC__
    549 warning(const char *fmt, ...)
    550 #else
    551 warning(va_alist)
    552 	va_dcl
    553 #endif
    554 {
    555 	va_list ap;
    556 #ifndef __STDC__
    557 	const char *fmt;
    558 
    559 	va_start(ap);
    560 	fmt = va_arg(ap, const char *);
    561 #else
    562 	va_start(ap, fmt);
    563 #endif
    564 
    565 	(void) fprintf(stderr, "%s: warning, using standard rsh: ", __progname);
    566 	(void) vfprintf(stderr, fmt, ap);
    567 	va_end(ap);
    568 	(void) fprintf(stderr, ".\n");
    569 }
    570 #endif
    571 
    572 char *
    573 copyargs(argv)
    574 	char **argv;
    575 {
    576 	int cc;
    577 	char **ap, *args, *p;
    578 
    579 	cc = 0;
    580 	for (ap = argv; *ap; ++ap)
    581 		cc += strlen(*ap) + 1;
    582 	if (!(args = malloc((u_int)cc)))
    583 		err(1, "malloc");
    584 	for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
    585 		(void)strcpy(p, *ap);
    586 		p += strlen(p);
    587 		if (ap[1])
    588 			*p++ = ' ';
    589 	}
    590 	*p = '\0';
    591 	return (args);
    592 }
    593 
    594 void
    595 usage()
    596 {
    597 
    598 	(void)fprintf(stderr,
    599 	    "usage: %s [-nd%s]%s[-l login]%s [login@]host %s\n", __progname,
    600 #ifdef KERBEROS
    601 #ifdef CRYPT
    602 	    "x", " [-k realm] ",
    603 #else
    604 	    "", " [-k realm] ",
    605 #endif
    606 #else
    607 	    "", " ",
    608 #endif
    609 #ifdef IN_RCMD
    610 	    " [-u locuser]", "command"
    611 #else
    612 	    "", "[command]"
    613 #endif
    614 	    );
    615 	exit(1);
    616 }
    617