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rsh.c revision 1.23 
      1 /*	$NetBSD: rsh.c,v 1.23 2004/10/16 02:03:54 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. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #ifndef lint
     34 __COPYRIGHT("@(#) Copyright (c) 1983, 1990, 1993, 1994\n\
     35 	The Regents of the University of California.  All rights reserved.\n");
     36 #endif /* not lint */
     37 
     38 #ifndef lint
     39 #if 0
     40 static char sccsid[] = "@(#)rsh.c	8.4 (Berkeley) 4/29/95";
     41 #else
     42 __RCSID("$NetBSD: rsh.c,v 1.23 2004/10/16 02:03:54 christos Exp $");
     43 #endif
     44 #endif /* not lint */
     45 
     46 #include <sys/types.h>
     47 #include <sys/socket.h>
     48 #include <sys/ioctl.h>
     49 #include <sys/file.h>
     50 #include <poll.h>
     51 
     52 #include <netinet/in.h>
     53 #include <netinet/tcp.h>
     54 #include <netdb.h>
     55 
     56 #include <err.h>
     57 #include <errno.h>
     58 #include <limits.h>
     59 #include <pwd.h>
     60 #include <signal.h>
     61 #include <stdarg.h>
     62 #include <stdio.h>
     63 #include <stdlib.h>
     64 #include <string.h>
     65 #include <unistd.h>
     66 
     67 #include "pathnames.h"
     68 #include "getport.h"
     69 
     70 #ifdef KERBEROS
     71 #include <des.h>
     72 #include <kerberosIV/krb.h>
     73 
     74 CREDENTIALS cred;
     75 Key_schedule schedule;
     76 int use_kerberos = 1, doencrypt;
     77 char dst_realm_buf[REALM_SZ], *dest_realm;
     78 
     79 void	warning(const char *, ...);
     80 #endif
     81 
     82 /*
     83  * rsh - remote shell
     84  */
     85 int	remerr;
     86 
     87 static int sigs[] = { SIGINT, SIGTERM, SIGQUIT };
     88 
     89 char   *copyargs(char **);
     90 void	sendsig(int);
     91 int	checkfd(struct pollfd *, int);
     92 void	talk(int, sigset_t *, pid_t, int);
     93 void	usage(void);
     94 int	main(int, char **);
     95 #ifdef IN_RCMD
     96 int	 orcmd(char **, int, const char *,
     97     const char *, const char *, int *);
     98 int	 orcmd_af(char **, int, const char *,
     99     const char *, const char *, int *, int);
    100 #endif
    101 
    102 int
    103 main(int argc, char **argv)
    104 {
    105 	struct passwd *pw;
    106 	struct servent *sp;
    107 	sigset_t oset, nset;
    108 	struct protoent *proto;
    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 	char *service = NULL;
    118 
    119 	argoff = asrsh = dflag = nflag = 0;
    120 	one = 1;
    121 	host = user = NULL;
    122 	sp = NULL;
    123 
    124 #ifndef IN_RCMD
    125 	/*
    126 	 * If called as something other than "rsh" use it as the host name,
    127 	 * only for rsh.
    128 	 */
    129 	if (strcmp(getprogname(), "rsh") == 0)
    130 		asrsh = 1;
    131 	else {
    132 		host = strdup(getprogname());
    133 		if (host == NULL)
    134 			err(1, NULL);
    135 	}
    136 #endif /* IN_RCMD */
    137 
    138 	/* handle "rsh host flags" */
    139 	if (!host && argc > 2 && argv[1][0] != '-') {
    140 		host = argv[1];
    141 		argoff = 1;
    142 	}
    143 
    144 #ifdef IN_RCMD
    145 	if ((loop = getenv("RCMD_LOOP")) && strcmp(loop, "YES") == 0)
    146 		warnx("rcmd appears to be looping!");
    147 
    148 	putenv("RCMD_LOOP=YES");
    149 
    150 # ifdef KERBEROS
    151 #  ifdef CRYPT
    152 #   define	OPTIONS	"8KLdek:l:np:u:wx"
    153 #  else
    154 #   define	OPTIONS	"8KLdek:l:np:u:w"
    155 #  endif
    156 # else
    157 #  define	OPTIONS	"8KLdel:np:u:w"
    158 # endif
    159 
    160 #else /* IN_RCMD */
    161 
    162 # ifdef KERBEROS
    163 #  ifdef CRYPT
    164 #   define	OPTIONS	"8KLdek:l:np:wx"
    165 #  else
    166 #   define	OPTIONS	"8KLdek:l:np:w"
    167 #  endif
    168 # else
    169 #  define	OPTIONS	"8KLdel:np:w"
    170 # endif
    171 
    172 #endif /* IN_RCMD */
    173 
    174 	if (!(pw = getpwuid(uid = getuid())))
    175 		errx(1, "unknown user id");
    176 
    177 	if ((name = strdup(pw->pw_name)) == NULL)
    178 		err(1, "malloc");
    179 	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
    180 		switch(ch) {
    181 		case 'K':
    182 #ifdef KERBEROS
    183 			use_kerberos = 0;
    184 #endif
    185 			break;
    186 		case 'L':	/* -8Lew are ignored to allow rlogin aliases */
    187 		case 'e':
    188 		case 'w':
    189 		case '8':
    190 			break;
    191 		case 'd':
    192 			dflag = 1;
    193 			break;
    194 		case 'l':
    195 			user = optarg;
    196 			break;
    197 #ifdef KERBEROS
    198 		case 'k':
    199 			strlcpy(dest_realm_buf, optarg, sizeof(dest_realm_buf));
    200 			dest_realm = dst_realm_buf;
    201 			break;
    202 #endif
    203 		case 'n':
    204 			nflag = 1;
    205 			break;
    206 		case 'p':
    207 			sp = getport(optarg, "tcp");
    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 = __UNCONST("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 #ifdef KERBEROS
    274 	if (use_kerberos) {
    275 		if (sp == NULL) {
    276 			sp = getservbyname((doencrypt ? "ekshell" : "kshell"), "tcp");
    277 		}
    278 		if (sp == NULL) {
    279 			use_kerberos = 0;
    280 			warning("can't get entry for %s/tcp service",
    281 			    doencrypt ? "ekshell" : "kshell");
    282 		}
    283 	}
    284 #endif
    285 	if (sp == NULL)
    286 		sp = getservbyname("shell", "tcp");
    287 	if (sp == NULL)
    288 		errx(1, "shell/tcp: unknown service");
    289 
    290 #ifdef KERBEROS
    291 try_connect:
    292 	if (use_kerberos) {
    293 #if 1
    294 		struct hostent *hp;
    295 
    296 		/* fully qualify hostname (needed for krb_realmofhost) */
    297 		hp = gethostbyname(host);
    298 		if (hp != NULL && !(host = strdup(hp->h_name)))
    299 			err(1, "strdup");
    300 #endif
    301 
    302 		rem = KSUCCESS;
    303 		errno = 0;
    304 		if (dest_realm == NULL)
    305 			dest_realm = krb_realmofhost(host);
    306 
    307 #ifdef CRYPT
    308 		if (doencrypt)
    309 			rem = krcmd_mutual(&host, sp->s_port, user, args,
    310 			    &remerr, dest_realm, &cred, schedule);
    311 		else
    312 #endif
    313 			rem = krcmd(&host, sp->s_port, user, args, &remerr,
    314 			    dest_realm);
    315 		if (rem < 0) {
    316 			use_kerberos = 0;
    317 			sp = getservbyname("shell", "tcp");
    318 			if (sp == NULL)
    319 				errx(1, "shell/tcp: unknown service");
    320 			if (errno == ECONNREFUSED)
    321 				warning("remote host doesn't support Kerberos");
    322 			if (errno == ENOENT)
    323 				warning("can't provide Kerberos auth data");
    324 			goto try_connect;
    325 		}
    326 	} else {
    327 		if (doencrypt)
    328 			errx(1, "the -x flag requires Kerberos authentication.");
    329 #ifdef IN_RCMD
    330 		rem = orcmd_af(&host, sp->s_port, locuser ? locuser :
    331 #else
    332 		rem = rcmd_af(&host, sp->s_port,
    333 #endif
    334 		    name,
    335 		    user, args, &remerr, PF_UNSPEC);
    336 	}
    337 #else /* KERBEROS */
    338 
    339 #ifdef IN_RCMD
    340 	rem = orcmd_af(&host, sp->s_port, locuser ? locuser :
    341 #else
    342 	rem = rcmd_af(&host, sp->s_port,
    343 #endif
    344 	    name, user, args, &remerr, PF_UNSPEC);
    345 #endif /* KERBEROS */
    346 	(void)free(name);
    347 
    348 	if (rem < 0)
    349 		exit(1);
    350 
    351 	if (remerr < 0)
    352 		errx(1, "can't establish stderr");
    353 	if (dflag) {
    354 		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
    355 		    sizeof(one)) < 0)
    356 			warn("setsockopt remote");
    357 		if (setsockopt(remerr, SOL_SOCKET, SO_DEBUG, &one,
    358 		    sizeof(one)) < 0)
    359 			warn("setsockopt stderr");
    360 	}
    361 	proto = getprotobyname("tcp");
    362 	setsockopt(rem, proto->p_proto, TCP_NODELAY, &one, sizeof(one));
    363 	setsockopt(remerr, proto->p_proto, TCP_NODELAY, &one, sizeof(one));
    364 
    365 
    366 	(void) setuid(uid);
    367 
    368 	(void) sigemptyset(&nset);
    369 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++)
    370 		(void) sigaddset(&nset, sigs[i]);
    371 
    372 	(void) sigprocmask(SIG_BLOCK, &nset, &oset);
    373 
    374 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++) {
    375 		struct sigaction sa;
    376 
    377 		if (sa.sa_handler != SIG_IGN) {
    378 			sa.sa_handler = sendsig;
    379 			(void) sigaction(sigs[i], &sa, NULL);
    380 		}
    381 	}
    382 
    383 	if (!nflag) {
    384 		pid = fork();
    385 		if (pid < 0)
    386 			err(1, "fork");
    387 	}
    388 	else
    389 		pid = -1;
    390 
    391 #if defined(KERBEROS) && defined(CRYPT)
    392 	if (!doencrypt)
    393 #endif
    394 	{
    395 		(void)ioctl(remerr, FIONBIO, &one);
    396 		(void)ioctl(rem, FIONBIO, &one);
    397 	}
    398 
    399 	talk(nflag, &oset, pid, rem);
    400 
    401 	if (!nflag)
    402 		(void)kill(pid, SIGKILL);
    403 	exit(0);
    404 }
    405 
    406 int
    407 checkfd(struct pollfd *fdp, int outfd)
    408 {
    409 	int nr, nw;
    410 	char buf[BUFSIZ];
    411 
    412 	if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    413 		return -1;
    414 
    415 	if ((fdp->revents & POLLIN) == 0)
    416 		return 0;
    417 
    418 	errno = 0;
    419 #if defined(KERBEROS) && defined(CRYPT)
    420 	if (doencrypt)
    421 		nr = des_read(fdp->fd, buf, sizeof buf);
    422 	else
    423 #endif
    424 		nr = read(fdp->fd, buf, sizeof buf);
    425 
    426 	if (nr <= 0) {
    427 		if (errno != EAGAIN)
    428 			return -1;
    429 		else
    430 			return 0;
    431 	}
    432 	else {
    433 		char *bc = buf;
    434 		while (nr) {
    435 			if ((nw = write(outfd, bc, nr)) <= 0)
    436 				return -1;
    437 			nr -= nw;
    438 			bc += nw;
    439 		}
    440 		return 0;
    441 	}
    442 }
    443 
    444 void
    445 talk(int nflag, sigset_t *oset, __pid_t pid, int rem)
    446 {
    447 	int nr, nw, nfds;
    448 	struct pollfd fds[2], *fdp = &fds[0];
    449 	char *bp, buf[BUFSIZ];
    450 
    451 
    452 	if (!nflag && pid == 0) {
    453 		(void)close(remerr);
    454 
    455 		fdp->events = POLLOUT|POLLNVAL|POLLERR|POLLHUP;
    456 		fdp->fd = rem;
    457 		nr = 0;
    458 		bp = buf;
    459 
    460 		for (;;) {
    461 			errno = 0;
    462 
    463 			if (nr == 0) {
    464 				if ((nr = read(0, buf, sizeof buf)) == 0)
    465 					goto done;
    466 				if (nr == -1) {
    467 					if (errno == EIO)
    468 						goto done;
    469 					if (errno == EINTR)
    470 						continue;
    471 					err(1, "read");
    472 				}
    473 				bp = buf;
    474 			}
    475 
    476 rewrite:		if (poll(fdp, 1, INFTIM) == -1) {
    477 				if (errno != EINTR)
    478 					err(1, "poll");
    479 				goto rewrite;
    480 			}
    481 
    482 			if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    483 				err(1, "poll");
    484 
    485 			if ((fdp->revents & POLLOUT) == 0)
    486 				goto rewrite;
    487 
    488 #if defined(KERBEROS) && defined(CRYPT)
    489 			if (doencrypt)
    490 				nw = des_write(rem, bp, nr);
    491 			else
    492 #endif
    493 				nw = write(rem, bp, nr);
    494 
    495 			if (nw < 0) {
    496 				if (errno == EAGAIN)
    497 					continue;
    498 				err(1, "write");
    499 			}
    500 			bp += nw;
    501 			nr -= nw;
    502 		}
    503 done:
    504 		(void)shutdown(rem, 1);
    505 		exit(0);
    506 	}
    507 
    508 	(void) sigprocmask(SIG_SETMASK, oset, NULL);
    509 	fds[0].events = fds[1].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
    510 	fds[0].fd = remerr;
    511 	fds[1].fd = rem;
    512 	fdp = &fds[0];
    513 	nfds = 2;
    514 	do {
    515 		if (poll(fdp, nfds, INFTIM) == -1) {
    516 			if (errno != EINTR)
    517 				err(1, "poll");
    518 			continue;
    519 		}
    520 		if (fds[0].events != 0 && checkfd(&fds[0], 2) == -1) {
    521 			nfds--;
    522 			fds[0].events = 0;
    523 			fdp = &fds[1];
    524 		}
    525 		if (fds[1].events != 0 && checkfd(&fds[1], 1) == -1) {
    526 			nfds--;
    527 			fds[1].events = 0;
    528 		}
    529 	}
    530 	while (nfds);
    531 }
    532 
    533 void
    534 sendsig(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 warning(const char *fmt, ...)
    553 {
    554 	va_list ap;
    555 
    556 	va_start(ap, fmt);
    557 	(void) fprintf(stderr, "%s: warning, using standard rsh: ",
    558 	    getprogname());
    559 	(void) vfprintf(stderr, fmt, ap);
    560 	va_end(ap);
    561 	(void) fprintf(stderr, ".\n");
    562 }
    563 #endif
    564 
    565 char *
    566 copyargs(char **argv)
    567 {
    568 	int cc;
    569 	char **ap, *args, *p, *ep;
    570 
    571 	cc = 0;
    572 	for (ap = argv; *ap; ++ap)
    573 		cc += strlen(*ap) + 1;
    574 	if (!(args = malloc((u_int)cc)))
    575 		err(1, "malloc");
    576 	ep = args + cc;
    577 	for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
    578 		(void)strlcpy(p, *ap, ep - p);
    579 		p += strlen(p);
    580 		if (ap[1])
    581 			*p++ = ' ';
    582 	}
    583 	*p = '\0';
    584 	return (args);
    585 }
    586 
    587 void
    588 usage(void)
    589 {
    590 
    591 	(void)fprintf(stderr,
    592 	    "usage: %s [-nd%s]%s[-l login] [-p port]%s [login@]host %s\n", getprogname(),
    593 #ifdef KERBEROS
    594 #ifdef CRYPT
    595 	    "x", " [-k realm] ",
    596 #else
    597 	    "", " [-k realm] ",
    598 #endif
    599 #else
    600 	    "", " ",
    601 #endif
    602 #ifdef IN_RCMD
    603 	    " [-u locuser]", "command"
    604 #else
    605 	    "", "[command]"
    606 #endif
    607 	    );
    608 	exit(1);
    609 }
    610