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rsh.c revision 1.16 
      1 /*	$NetBSD: rsh.c,v 1.16 2002/11/16 13:47:34 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 1.16 2002/11/16 13:47:34 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 <stdarg.h>
     64 #include <stdio.h>
     65 #include <stdlib.h>
     66 #include <string.h>
     67 #include <unistd.h>
     68 
     69 #include "pathnames.h"
     70 
     71 #ifdef KERBEROS
     72 #include <kerberosIV/des.h>
     73 #include <kerberosIV/krb.h>
     74 
     75 CREDENTIALS cred;
     76 Key_schedule schedule;
     77 int use_kerberos = 1, doencrypt;
     78 char dst_realm_buf[REALM_SZ], *dest_realm;
     79 
     80 void	warning(const char *, ...);
     81 #endif
     82 
     83 /*
     84  * rsh - remote shell
     85  */
     86 int	remerr;
     87 
     88 static int sigs[] = { SIGINT, SIGTERM, SIGQUIT };
     89 
     90 char   *copyargs(char **);
     91 void	sendsig(int);
     92 int	checkfd(struct pollfd *, int);
     93 void	talk(int, sigset_t *, pid_t, int);
     94 void	usage(void);
     95 int	main(int, char **);
     96 #ifdef IN_RCMD
     97 int	 orcmd(char **, int, const char *,
     98     const char *, const char *, int *);
     99 int	 orcmd_af(char **, int, const char *,
    100     const char *, const char *, int *, int);
    101 #endif
    102 
    103 int
    104 main(int argc, char **argv)
    105 {
    106 	struct passwd *pw;
    107 	struct servent *sp;
    108 	sigset_t oset, nset;
    109 
    110 #ifdef IN_RCMD
    111 	char	*locuser = 0, *loop;
    112 #endif /* IN_RCMD */
    113 	int argoff, asrsh, ch, dflag, nflag, one, rem, i;
    114 	pid_t pid;
    115 	uid_t uid;
    116 	char *args, *host, *p, *user, *name;
    117 
    118 	argoff = asrsh = dflag = nflag = 0;
    119 	one = 1;
    120 	host = user = NULL;
    121 
    122 #ifndef IN_RCMD
    123 	/*
    124 	 * If called as something other than "rsh" use it as the host name,
    125 	 * only for rsh.
    126 	 */
    127 	if (strcmp(getprogname(), "rsh") == 0)
    128 		asrsh = 1;
    129 	else {
    130 		host = strdup(getprogname());
    131 		if (host == NULL)
    132 			err(1, NULL);
    133 	}
    134 #endif /* IN_RCMD */
    135 
    136 	/* handle "rsh host flags" */
    137 	if (!host && argc > 2 && argv[1][0] != '-') {
    138 		host = argv[1];
    139 		argoff = 1;
    140 	}
    141 
    142 #ifdef IN_RCMD
    143 	if ((loop = getenv("RCMD_LOOP")) && strcmp(loop, "YES") == 0)
    144 		warnx("rcmd appears to be looping!");
    145 
    146 	putenv("RCMD_LOOP=YES");
    147 
    148 # ifdef KERBEROS
    149 #  ifdef CRYPT
    150 #   define	OPTIONS	"8KLdek:l:nu:wx"
    151 #  else
    152 #   define	OPTIONS	"8KLdek:l:nu:w"
    153 #  endif
    154 # else
    155 #  define	OPTIONS	"8KLdel:nu:w"
    156 # endif
    157 
    158 #else /* IN_RCMD */
    159 
    160 # ifdef KERBEROS
    161 #  ifdef CRYPT
    162 #   define	OPTIONS	"8KLdek:l:nwx"
    163 #  else
    164 #   define	OPTIONS	"8KLdek:l:nw"
    165 #  endif
    166 # else
    167 #  define	OPTIONS	"8KLdel:nw"
    168 # endif
    169 
    170 #endif /* IN_RCMD */
    171 
    172 	if (!(pw = getpwuid(uid = getuid())))
    173 		errx(1, "unknown user id");
    174 
    175 	if ((name = strdup(pw->pw_name)) == NULL)
    176 		err(1, "malloc");
    177 	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
    178 		switch(ch) {
    179 		case 'K':
    180 #ifdef KERBEROS
    181 			use_kerberos = 0;
    182 #endif
    183 			break;
    184 		case 'L':	/* -8Lew are ignored to allow rlogin aliases */
    185 		case 'e':
    186 		case 'w':
    187 		case '8':
    188 			break;
    189 		case 'd':
    190 			dflag = 1;
    191 			break;
    192 		case 'l':
    193 			user = optarg;
    194 			break;
    195 #ifdef KERBEROS
    196 		case 'k':
    197 			strlcpy(dest_realm_buf, optarg, sizeof(dest_realm_buf));
    198 			dest_realm = dst_realm_buf;
    199 			break;
    200 #endif
    201 		case 'n':
    202 			nflag = 1;
    203 			break;
    204 #ifdef IN_RCMD
    205 		case 'u':
    206 			if (getuid() != 0 && optarg && name &&
    207 			    strcmp(name, optarg) != 0)
    208 				errx(1,"only super user can use the -u option");
    209 			locuser = optarg;
    210 			break;
    211 #endif /* IN_RCMD */
    212 #ifdef KERBEROS
    213 #ifdef CRYPT
    214 		case 'x':
    215 			doencrypt = 1;
    216 			des_set_key((des_cblock *) cred.session, schedule);
    217 			break;
    218 #endif
    219 #endif
    220 		case '?':
    221 		default:
    222 			usage();
    223 		}
    224 	optind += argoff;
    225 
    226 	/* if haven't gotten a host yet, do so */
    227 	if (!host && !(host = argv[optind++]))
    228 		usage();
    229 
    230 	/* if no further arguments, must have been called as rlogin. */
    231 	if (!argv[optind]) {
    232 #ifdef IN_RCMD
    233 		usage();
    234 #else
    235 		if (asrsh)
    236 			*argv = "rlogin";
    237 		execv(_PATH_RLOGIN, argv);
    238 		err(1, "can't exec %s", _PATH_RLOGIN);
    239 #endif
    240 	}
    241 
    242 	argc -= optind;
    243 	argv += optind;
    244 
    245 	/* Accept user1@host format, though "-l user2" overrides user1 */
    246 	p = strchr(host, '@');
    247 	if (p) {
    248 		*p = '\0';
    249 		if (!user && p > host)
    250 			user = host;
    251 		host = p + 1;
    252 		if (*host == '\0')
    253 			usage();
    254 	}
    255 	if (!user)
    256 		user = name;
    257 
    258 #ifdef KERBEROS
    259 #ifdef CRYPT
    260 	/* -x turns off -n */
    261 	if (doencrypt)
    262 		nflag = 0;
    263 #endif
    264 #endif
    265 
    266 	args = copyargs(argv);
    267 
    268 	sp = NULL;
    269 #ifdef KERBEROS
    270 	if (use_kerberos) {
    271 		sp = getservbyname((doencrypt ? "ekshell" : "kshell"), "tcp");
    272 		if (sp == NULL) {
    273 			use_kerberos = 0;
    274 			warning("can't get entry for %s/tcp service",
    275 			    doencrypt ? "ekshell" : "kshell");
    276 		}
    277 	}
    278 #endif
    279 	if (sp == NULL)
    280 		sp = getservbyname("shell", "tcp");
    281 	if (sp == NULL)
    282 		errx(1, "shell/tcp: unknown service");
    283 
    284 #ifdef KERBEROS
    285 try_connect:
    286 	if (use_kerberos) {
    287 #if 1
    288 		struct hostent *hp;
    289 
    290 		/* fully qualify hostname (needed for krb_realmofhost) */
    291 		hp = gethostbyname(host);
    292 		if (hp != NULL && !(host = strdup(hp->h_name)))
    293 			err(1, "strdup");
    294 #endif
    295 
    296 		rem = KSUCCESS;
    297 		errno = 0;
    298 		if (dest_realm == NULL)
    299 			dest_realm = krb_realmofhost(host);
    300 
    301 #ifdef CRYPT
    302 		if (doencrypt)
    303 			rem = krcmd_mutual(&host, sp->s_port, user, args,
    304 			    &remerr, dest_realm, &cred, schedule);
    305 		else
    306 #endif
    307 			rem = krcmd(&host, sp->s_port, user, args, &remerr,
    308 			    dest_realm);
    309 		if (rem < 0) {
    310 			use_kerberos = 0;
    311 			sp = getservbyname("shell", "tcp");
    312 			if (sp == NULL)
    313 				errx(1, "shell/tcp: unknown service");
    314 			if (errno == ECONNREFUSED)
    315 				warning("remote host doesn't support Kerberos");
    316 			if (errno == ENOENT)
    317 				warning("can't provide Kerberos auth data");
    318 			goto try_connect;
    319 		}
    320 	} else {
    321 		if (doencrypt)
    322 			errx(1, "the -x flag requires Kerberos authentication.");
    323 #ifdef IN_RCMD
    324 		rem = orcmd_af(&host, sp->s_port, locuser ? locuser :
    325 #else
    326 		rem = rcmd_af(&host, sp->s_port,
    327 #endif
    328 		    name,
    329 		    user, args, &remerr, PF_UNSPEC);
    330 	}
    331 #else /* KERBEROS */
    332 
    333 #ifdef IN_RCMD
    334 	rem = orcmd_af(&host, sp->s_port, locuser ? locuser :
    335 #else
    336 	rem = rcmd_af(&host, sp->s_port,
    337 #endif
    338 	    name, user, args, &remerr, PF_UNSPEC);
    339 #endif /* KERBEROS */
    340 	(void)free(name);
    341 
    342 	if (rem < 0)
    343 		exit(1);
    344 
    345 	if (remerr < 0)
    346 		errx(1, "can't establish stderr");
    347 	if (dflag) {
    348 		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
    349 		    sizeof(one)) < 0)
    350 			warn("setsockopt remote");
    351 		if (setsockopt(remerr, SOL_SOCKET, SO_DEBUG, &one,
    352 		    sizeof(one)) < 0)
    353 			warn("setsockopt stderr");
    354 	}
    355 
    356 	(void) setuid(uid);
    357 
    358 	(void) sigemptyset(&nset);
    359 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++)
    360 		(void) sigaddset(&nset, sigs[i]);
    361 
    362 	(void) sigprocmask(SIG_BLOCK, &nset, &oset);
    363 
    364 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++) {
    365 		struct sigaction sa;
    366 
    367 		if (sa.sa_handler != SIG_IGN) {
    368 			sa.sa_handler = sendsig;
    369 			(void) sigaction(sigs[i], &sa, NULL);
    370 		}
    371 	}
    372 
    373 	if (!nflag) {
    374 		pid = fork();
    375 		if (pid < 0)
    376 			err(1, "fork");
    377 	}
    378 	else
    379 		pid = -1;
    380 
    381 #if defined(KERBEROS) && defined(CRYPT)
    382 	if (!doencrypt)
    383 #endif
    384 	{
    385 		(void)ioctl(remerr, FIONBIO, &one);
    386 		(void)ioctl(rem, FIONBIO, &one);
    387 	}
    388 
    389 	talk(nflag, &oset, pid, rem);
    390 
    391 	if (!nflag)
    392 		(void)kill(pid, SIGKILL);
    393 	exit(0);
    394 }
    395 
    396 int
    397 checkfd(struct pollfd *fdp, int outfd)
    398 {
    399 	int nr, nw;
    400 	char buf[BUFSIZ];
    401 
    402 	if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    403 		return -1;
    404 
    405 	if ((fdp->revents & POLLIN) == 0)
    406 		return 0;
    407 
    408 	errno = 0;
    409 #if defined(KERBEROS) && defined(CRYPT)
    410 	if (doencrypt)
    411 		nr = des_read(fdp->fd, buf, sizeof buf);
    412 	else
    413 #endif
    414 		nr = read(fdp->fd, buf, sizeof buf);
    415 
    416 	if (nr <= 0) {
    417 		if (errno != EAGAIN)
    418 			return -1;
    419 		else
    420 			return 0;
    421 	}
    422 	else {
    423 		char *bc = buf;
    424 		while (nr) {
    425 			if ((nw = write(outfd, bc, nr)) <= 0)
    426 				return -1;
    427 			nr -= nw;
    428 			bc += nw;
    429 		}
    430 		return 0;
    431 	}
    432 }
    433 
    434 void
    435 talk(int nflag, sigset_t *oset, __pid_t pid, int rem)
    436 {
    437 	int nr, nw, nfds;
    438 	struct pollfd fds[2], *fdp = &fds[0];
    439 	char *bp, buf[BUFSIZ];
    440 
    441 
    442 	if (!nflag && pid == 0) {
    443 		(void)close(remerr);
    444 
    445 		fdp->events = POLLOUT|POLLNVAL|POLLERR|POLLHUP;
    446 		fdp->fd = rem;
    447 		nr = 0;
    448 		bp = buf;
    449 
    450 		for (;;) {
    451 			errno = 0;
    452 
    453 			if (nr == 0) {
    454 				if ((nr = read(0, buf, sizeof buf)) == 0)
    455 					goto done;
    456 				if (nr == -1) {
    457 					if (errno == EIO)
    458 						goto done;
    459 					if (errno == EINTR)
    460 						continue;
    461 					err(1, "read");
    462 				}
    463 				bp = buf;
    464 			}
    465 
    466 rewrite:		if (poll(fdp, 1, INFTIM) == -1) {
    467 				if (errno != EINTR)
    468 					err(1, "poll");
    469 				goto rewrite;
    470 			}
    471 
    472 			if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    473 				err(1, "poll");
    474 
    475 			if ((fdp->revents & POLLOUT) == 0)
    476 				goto rewrite;
    477 
    478 #if defined(KERBEROS) && defined(CRYPT)
    479 			if (doencrypt)
    480 				nw = des_write(rem, bp, nr);
    481 			else
    482 #endif
    483 				nw = write(rem, bp, nr);
    484 
    485 			if (nw < 0) {
    486 				if (errno == EAGAIN)
    487 					continue;
    488 				err(1, "write");
    489 			}
    490 			bp += nw;
    491 			nr -= nw;
    492 		}
    493 done:
    494 		(void)shutdown(rem, 1);
    495 		exit(0);
    496 	}
    497 
    498 	(void) sigprocmask(SIG_SETMASK, oset, NULL);
    499 	fds[0].events = fds[1].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
    500 	fds[0].fd = remerr;
    501 	fds[1].fd = rem;
    502 	fdp = &fds[0];
    503 	nfds = 2;
    504 	do {
    505 		if (poll(fdp, nfds, INFTIM) == -1) {
    506 			if (errno != EINTR)
    507 				err(1, "poll");
    508 			continue;
    509 		}
    510 		if (fds[0].events != 0 && checkfd(&fds[0], 2) == -1) {
    511 			nfds--;
    512 			fds[0].events = 0;
    513 			fdp = &fds[1];
    514 		}
    515 		if (fds[1].events != 0 && checkfd(&fds[1], 1) == -1) {
    516 			nfds--;
    517 			fds[1].events = 0;
    518 		}
    519 	}
    520 	while (nfds);
    521 }
    522 
    523 void
    524 sendsig(int sig)
    525 {
    526 	char signo;
    527 
    528 	signo = sig;
    529 #ifdef KERBEROS
    530 #ifdef CRYPT
    531 	if (doencrypt)
    532 		(void)des_write(remerr, &signo, 1);
    533 	else
    534 #endif
    535 #endif
    536 		(void)write(remerr, &signo, 1);
    537 }
    538 
    539 #ifdef KERBEROS
    540 /* VARARGS */
    541 void
    542 warning(const char *fmt, ...)
    543 {
    544 	va_list ap;
    545 
    546 	va_start(ap, fmt);
    547 	(void) fprintf(stderr, "%s: warning, using standard rsh: ",
    548 	    getprogname());
    549 	(void) vfprintf(stderr, fmt, ap);
    550 	va_end(ap);
    551 	(void) fprintf(stderr, ".\n");
    552 }
    553 #endif
    554 
    555 char *
    556 copyargs(char **argv)
    557 {
    558 	int cc;
    559 	char **ap, *args, *p;
    560 
    561 	cc = 0;
    562 	for (ap = argv; *ap; ++ap)
    563 		cc += strlen(*ap) + 1;
    564 	if (!(args = malloc((u_int)cc)))
    565 		err(1, "malloc");
    566 	for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
    567 		(void)strcpy(p, *ap);
    568 		p += strlen(p);
    569 		if (ap[1])
    570 			*p++ = ' ';
    571 	}
    572 	*p = '\0';
    573 	return (args);
    574 }
    575 
    576 void
    577 usage(void)
    578 {
    579 
    580 	(void)fprintf(stderr,
    581 	    "usage: %s [-nd%s]%s[-l login]%s [login@]host %s\n", getprogname(),
    582 #ifdef KERBEROS
    583 #ifdef CRYPT
    584 	    "x", " [-k realm] ",
    585 #else
    586 	    "", " [-k realm] ",
    587 #endif
    588 #else
    589 	    "", " ",
    590 #endif
    591 #ifdef IN_RCMD
    592 	    " [-u locuser]", "command"
    593 #else
    594 	    "", "[command]"
    595 #endif
    596 	    );
    597 	exit(1);
    598 }
    599