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rsh.c revision 1.13 
      1 /*	$NetBSD: rsh.c,v 1.13 2000/01/31 14:19:34 itojun 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 1.13 2000/01/31 14:19:34 itojun 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 int	 orcmd_af __P((char **, int, const char *,
    105     const char *, const char *, int *, int));
    106 #endif
    107 
    108 int
    109 main(argc, argv)
    110 	int argc;
    111 	char **argv;
    112 {
    113 	struct passwd *pw;
    114 	struct servent *sp;
    115 	sigset_t oset, nset;
    116 
    117 #ifdef IN_RCMD
    118 	char	*locuser = 0, *loop;
    119 #endif /* IN_RCMD */
    120 	int argoff, asrsh, ch, dflag, nflag, one, rem, i;
    121 	pid_t pid;
    122 	uid_t uid;
    123 	char *args, *host, *p, *user, *name;
    124 
    125 	argoff = asrsh = dflag = nflag = 0;
    126 	one = 1;
    127 	host = user = NULL;
    128 
    129 #ifndef IN_RCMD
    130 	/*
    131 	 * If called as something other than "rsh" use it as the host name,
    132 	 * only for rsh.
    133 	 */
    134 	p = __progname;
    135 	if (strcmp(p, "rsh") == 0)
    136 		asrsh = 1;
    137 	else
    138 		host = p;
    139 #endif /* IN_RCMD */
    140 
    141 	/* handle "rsh host flags" */
    142 	if (!host && argc > 2 && argv[1][0] != '-') {
    143 		host = argv[1];
    144 		argoff = 1;
    145 	}
    146 
    147 #ifdef IN_RCMD
    148 	if ((loop = getenv("RCMD_LOOP")) && strcmp(loop, "YES") == 0)
    149 		warnx("rcmd appears to be looping!");
    150 
    151 	putenv("RCMD_LOOP=YES");
    152 
    153 # ifdef KERBEROS
    154 #  ifdef CRYPT
    155 #   define	OPTIONS	"8KLdek:l:nu:wx"
    156 #  else
    157 #   define	OPTIONS	"8KLdek:l:nu:w"
    158 #  endif
    159 # else
    160 #  define	OPTIONS	"8KLdel:nu:w"
    161 # endif
    162 
    163 #else /* IN_RCMD */
    164 
    165 # ifdef KERBEROS
    166 #  ifdef CRYPT
    167 #   define	OPTIONS	"8KLdek:l:nwx"
    168 #  else
    169 #   define	OPTIONS	"8KLdek:l:nw"
    170 #  endif
    171 # else
    172 #  define	OPTIONS	"8KLdel:nw"
    173 # endif
    174 
    175 #endif /* IN_RCMD */
    176 
    177 	if (!(pw = getpwuid(uid = getuid())))
    178 		errx(1, "unknown user id");
    179 
    180 	if ((name = strdup(pw->pw_name)) == NULL)
    181 		err(1, "malloc");
    182 	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
    183 		switch(ch) {
    184 		case 'K':
    185 #ifdef KERBEROS
    186 			use_kerberos = 0;
    187 #endif
    188 			break;
    189 		case 'L':	/* -8Lew are ignored to allow rlogin aliases */
    190 		case 'e':
    191 		case 'w':
    192 		case '8':
    193 			break;
    194 		case 'd':
    195 			dflag = 1;
    196 			break;
    197 		case 'l':
    198 			user = optarg;
    199 			break;
    200 #ifdef KERBEROS
    201 		case 'k':
    202 			dest_realm = dst_realm_buf;
    203 			strncpy(dest_realm, optarg, REALM_SZ);
    204 			break;
    205 #endif
    206 		case 'n':
    207 			nflag = 1;
    208 			break;
    209 #ifdef IN_RCMD
    210 		case 'u':
    211 			if (getuid() != 0 && optarg && name &&
    212 			    strcmp(name, optarg) != 0)
    213 				errx(1,"only super user can use the -u option");
    214 			locuser = optarg;
    215 			break;
    216 #endif /* IN_RCMD */
    217 #ifdef KERBEROS
    218 #ifdef CRYPT
    219 		case 'x':
    220 			doencrypt = 1;
    221 			des_set_key((des_cblock *) cred.session, schedule);
    222 			break;
    223 #endif
    224 #endif
    225 		case '?':
    226 		default:
    227 			usage();
    228 		}
    229 	optind += argoff;
    230 
    231 	/* if haven't gotten a host yet, do so */
    232 	if (!host && !(host = argv[optind++]))
    233 		usage();
    234 
    235 	/* if no further arguments, must have been called as rlogin. */
    236 	if (!argv[optind]) {
    237 #ifdef IN_RCMD
    238 		usage();
    239 #else
    240 		if (asrsh)
    241 			*argv = "rlogin";
    242 		execv(_PATH_RLOGIN, argv);
    243 		err(1, "can't exec %s", _PATH_RLOGIN);
    244 #endif
    245 	}
    246 
    247 	argc -= optind;
    248 	argv += optind;
    249 
    250 	/* Accept user1@host format, though "-l user2" overrides user1 */
    251 	p = strchr(host, '@');
    252 	if (p) {
    253 		*p = '\0';
    254 		if (!user && p > host)
    255 			user = host;
    256 		host = p + 1;
    257 		if (*host == '\0')
    258 			usage();
    259 	}
    260 	if (!user)
    261 		user = name;
    262 
    263 #ifdef KERBEROS
    264 #ifdef CRYPT
    265 	/* -x turns off -n */
    266 	if (doencrypt)
    267 		nflag = 0;
    268 #endif
    269 #endif
    270 
    271 	args = copyargs(argv);
    272 
    273 	sp = NULL;
    274 #ifdef KERBEROS
    275 	if (use_kerberos) {
    276 		sp = getservbyname((doencrypt ? "ekshell" : "kshell"), "tcp");
    277 		if (sp == NULL) {
    278 			use_kerberos = 0;
    279 			warning("can't get entry for %s/tcp service",
    280 			    doencrypt ? "ekshell" : "kshell");
    281 		}
    282 	}
    283 #endif
    284 	if (sp == NULL)
    285 		sp = getservbyname("shell", "tcp");
    286 	if (sp == NULL)
    287 		errx(1, "shell/tcp: unknown service");
    288 
    289 #ifdef KERBEROS
    290 try_connect:
    291 	if (use_kerberos) {
    292 #if 1
    293 		struct hostent *hp;
    294 
    295 		/* fully qualify hostname (needed for krb_realmofhost) */
    296 		hp = gethostbyname(host);
    297 		if (hp != NULL && !(host = strdup(hp->h_name)))
    298 			err(1, "strdup");
    299 #endif
    300 
    301 		rem = KSUCCESS;
    302 		errno = 0;
    303 		if (dest_realm == NULL)
    304 			dest_realm = krb_realmofhost(host);
    305 
    306 #ifdef CRYPT
    307 		if (doencrypt)
    308 			rem = krcmd_mutual(&host, sp->s_port, user, args,
    309 			    &remerr, dest_realm, &cred, schedule);
    310 		else
    311 #endif
    312 			rem = krcmd(&host, sp->s_port, user, args, &remerr,
    313 			    dest_realm);
    314 		if (rem < 0) {
    315 			use_kerberos = 0;
    316 			sp = getservbyname("shell", "tcp");
    317 			if (sp == NULL)
    318 				errx(1, "shell/tcp: unknown service");
    319 			if (errno == ECONNREFUSED)
    320 				warning("remote host doesn't support Kerberos");
    321 			if (errno == ENOENT)
    322 				warning("can't provide Kerberos auth data");
    323 			goto try_connect;
    324 		}
    325 	} else {
    326 		if (doencrypt)
    327 			errx(1, "the -x flag requires Kerberos authentication.");
    328 #ifdef IN_RCMD
    329 		rem = orcmd_af(&host, sp->s_port, locuser ? locuser :
    330 #else
    331 		rem = rcmd_af(&host, sp->s_port,
    332 #endif
    333 		    name,
    334 		    user, args, &remerr, PF_UNSPEC);
    335 	}
    336 #else /* KERBEROS */
    337 
    338 #ifdef IN_RCMD
    339 	rem = orcmd_af(&host, sp->s_port, locuser ? locuser :
    340 #else
    341 	rem = rcmd_af(&host, sp->s_port,
    342 #endif
    343 	    name, user, args, &remerr, PF_UNSPEC);
    344 #endif /* KERBEROS */
    345 	(void)free(name);
    346 
    347 	if (rem < 0)
    348 		exit(1);
    349 
    350 	if (remerr < 0)
    351 		errx(1, "can't establish stderr");
    352 	if (dflag) {
    353 		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
    354 		    sizeof(one)) < 0)
    355 			warn("setsockopt remote");
    356 		if (setsockopt(remerr, SOL_SOCKET, SO_DEBUG, &one,
    357 		    sizeof(one)) < 0)
    358 			warn("setsockopt stderr");
    359 	}
    360 
    361 	(void) setuid(uid);
    362 
    363 	(void) sigemptyset(&nset);
    364 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++)
    365 		(void) sigaddset(&nset, sigs[i]);
    366 
    367 	(void) sigprocmask(SIG_BLOCK, &nset, &oset);
    368 
    369 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++) {
    370 		struct sigaction sa;
    371 
    372 		if (sa.sa_handler != SIG_IGN) {
    373 			sa.sa_handler = sendsig;
    374 			(void) sigaction(sigs[i], &sa, NULL);
    375 		}
    376 	}
    377 
    378 	if (!nflag) {
    379 		pid = fork();
    380 		if (pid < 0)
    381 			err(1, "fork");
    382 	}
    383 	else
    384 		pid = -1;
    385 
    386 #if defined(KERBEROS) && defined(CRYPT)
    387 	if (!doencrypt)
    388 #endif
    389 	{
    390 		(void)ioctl(remerr, FIONBIO, &one);
    391 		(void)ioctl(rem, FIONBIO, &one);
    392 	}
    393 
    394 	talk(nflag, &oset, pid, rem);
    395 
    396 	if (!nflag)
    397 		(void)kill(pid, SIGKILL);
    398 	exit(0);
    399 }
    400 
    401 int
    402 checkfd(fdp, outfd)
    403 	struct pollfd *fdp;
    404 	int outfd;
    405 {
    406 	int nr, nw;
    407 	char buf[BUFSIZ];
    408 
    409 	if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    410 		return -1;
    411 
    412 	if ((fdp->revents & POLLIN) == 0)
    413 		return 0;
    414 
    415 	errno = 0;
    416 #if defined(KERBEROS) && defined(CRYPT)
    417 	if (doencrypt)
    418 		nr = des_read(fdp->fd, buf, sizeof buf);
    419 	else
    420 #endif
    421 		nr = read(fdp->fd, buf, sizeof buf);
    422 
    423 	if (nr <= 0) {
    424 		if (errno != EAGAIN)
    425 			return -1;
    426 		else
    427 			return 0;
    428 	}
    429 	else {
    430 		char *bc = buf;
    431 		while (nr) {
    432 			if ((nw = write(outfd, bc, nr)) <= 0)
    433 				return -1;
    434 			nr -= nw;
    435 			bc += nw;
    436 		}
    437 		return 0;
    438 	}
    439 }
    440 
    441 void
    442 talk(nflag, oset, pid, rem)
    443 	int nflag;
    444 	sigset_t *oset;
    445 	pid_t pid;
    446 	int rem;
    447 {
    448 	int nr, nw, nfds;
    449 	struct pollfd fds[2], *fdp = &fds[0];
    450 	char *bp, buf[BUFSIZ];
    451 
    452 
    453 	if (!nflag && pid == 0) {
    454 		(void)close(remerr);
    455 
    456 		fdp->events = POLLOUT|POLLNVAL|POLLERR|POLLHUP;
    457 		fdp->fd = rem;
    458 		nr = 0;
    459 		bp = buf;
    460 
    461 		for (;;) {
    462 			errno = 0;
    463 
    464 			if (nr == 0) {
    465 				if ((nr = read(0, buf, sizeof buf)) == 0)
    466 					goto done;
    467 				if (nr == -1) {
    468 					if (errno == EIO)
    469 						goto done;
    470 					if (errno == EINTR)
    471 						continue;
    472 					err(1, "read");
    473 				}
    474 				bp = buf;
    475 			}
    476 
    477 rewrite:		if (poll(fdp, 1, INFTIM) == -1) {
    478 				if (errno != EINTR)
    479 					err(1, "poll");
    480 				goto rewrite;
    481 			}
    482 
    483 			if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    484 				err(1, "poll");
    485 
    486 			if ((fdp->revents & POLLOUT) == 0)
    487 				goto rewrite;
    488 
    489 #if defined(KERBEROS) && defined(CRYPT)
    490 			if (doencrypt)
    491 				nw = des_write(rem, bp, nr);
    492 			else
    493 #endif
    494 				nw = write(rem, bp, nr);
    495 
    496 			if (nw < 0) {
    497 				if (errno == EAGAIN)
    498 					continue;
    499 				err(1, "write");
    500 			}
    501 			bp += nw;
    502 			nr -= nw;
    503 		}
    504 done:
    505 		(void)shutdown(rem, 1);
    506 		exit(0);
    507 	}
    508 
    509 	(void) sigprocmask(SIG_SETMASK, oset, NULL);
    510 	fds[0].events = fds[1].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
    511 	fds[0].fd = remerr;
    512 	fds[1].fd = rem;
    513 	fdp = &fds[0];
    514 	nfds = 2;
    515 	do {
    516 		if (poll(fdp, nfds, INFTIM) == -1) {
    517 			if (errno != EINTR)
    518 				err(1, "poll");
    519 			continue;
    520 		}
    521 		if (fds[0].events != 0 && checkfd(&fds[0], 2) == -1) {
    522 			nfds--;
    523 			fds[0].events = 0;
    524 			fdp = &fds[1];
    525 		}
    526 		if (fds[1].events != 0 && checkfd(&fds[1], 1) == -1) {
    527 			nfds--;
    528 			fds[1].events = 0;
    529 		}
    530 	}
    531 	while (nfds);
    532 }
    533 
    534 void
    535 sendsig(sig)
    536 	int sig;
    537 {
    538 	char signo;
    539 
    540 	signo = sig;
    541 #ifdef KERBEROS
    542 #ifdef CRYPT
    543 	if (doencrypt)
    544 		(void)des_write(remerr, &signo, 1);
    545 	else
    546 #endif
    547 #endif
    548 		(void)write(remerr, &signo, 1);
    549 }
    550 
    551 #ifdef KERBEROS
    552 /* VARARGS */
    553 void
    554 #ifdef __STDC__
    555 warning(const char *fmt, ...)
    556 #else
    557 warning(va_alist)
    558 	va_dcl
    559 #endif
    560 {
    561 	va_list ap;
    562 #ifndef __STDC__
    563 	const char *fmt;
    564 
    565 	va_start(ap);
    566 	fmt = va_arg(ap, const char *);
    567 #else
    568 	va_start(ap, fmt);
    569 #endif
    570 
    571 	(void) fprintf(stderr, "%s: warning, using standard rsh: ", __progname);
    572 	(void) vfprintf(stderr, fmt, ap);
    573 	va_end(ap);
    574 	(void) fprintf(stderr, ".\n");
    575 }
    576 #endif
    577 
    578 char *
    579 copyargs(argv)
    580 	char **argv;
    581 {
    582 	int cc;
    583 	char **ap, *args, *p;
    584 
    585 	cc = 0;
    586 	for (ap = argv; *ap; ++ap)
    587 		cc += strlen(*ap) + 1;
    588 	if (!(args = malloc((u_int)cc)))
    589 		err(1, "malloc");
    590 	for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
    591 		(void)strcpy(p, *ap);
    592 		p += strlen(p);
    593 		if (ap[1])
    594 			*p++ = ' ';
    595 	}
    596 	*p = '\0';
    597 	return (args);
    598 }
    599 
    600 void
    601 usage()
    602 {
    603 
    604 	(void)fprintf(stderr,
    605 	    "usage: %s [-nd%s]%s[-l login]%s [login@]host %s\n", __progname,
    606 #ifdef KERBEROS
    607 #ifdef CRYPT
    608 	    "x", " [-k realm] ",
    609 #else
    610 	    "", " [-k realm] ",
    611 #endif
    612 #else
    613 	    "", " ",
    614 #endif
    615 #ifdef IN_RCMD
    616 	    " [-u locuser]", "command"
    617 #else
    618 	    "", "[command]"
    619 #endif
    620 	    );
    621 	exit(1);
    622 }
    623