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rsh.c revision 1.22 
      1 /*	$NetBSD: rsh.c,v 1.22 2003/08/07 11:15:43 agc 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 1.22 2003/08/07 11:15:43 agc 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 <pwd.h>
     59 #include <signal.h>
     60 #include <stdarg.h>
     61 #include <stdio.h>
     62 #include <stdlib.h>
     63 #include <string.h>
     64 #include <unistd.h>
     65 
     66 #include "pathnames.h"
     67 
     68 #ifdef KERBEROS
     69 #include <des.h>
     70 #include <kerberosIV/krb.h>
     71 
     72 CREDENTIALS cred;
     73 Key_schedule schedule;
     74 int use_kerberos = 1, doencrypt;
     75 char dst_realm_buf[REALM_SZ], *dest_realm;
     76 
     77 void	warning(const char *, ...);
     78 #endif
     79 
     80 /*
     81  * rsh - remote shell
     82  */
     83 int	remerr;
     84 
     85 static int sigs[] = { SIGINT, SIGTERM, SIGQUIT };
     86 
     87 char   *copyargs(char **);
     88 void	sendsig(int);
     89 int	checkfd(struct pollfd *, int);
     90 void	talk(int, sigset_t *, pid_t, int);
     91 void	usage(void);
     92 int	main(int, char **);
     93 #ifdef IN_RCMD
     94 int	 orcmd(char **, int, const char *,
     95     const char *, const char *, int *);
     96 int	 orcmd_af(char **, int, const char *,
     97     const char *, const char *, int *, int);
     98 #endif
     99 
    100 int
    101 main(int argc, char **argv)
    102 {
    103 	struct passwd *pw;
    104 	struct servent *sp;
    105 	sigset_t oset, nset;
    106 	struct protoent *proto;
    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 	char *service=NULL;
    116 
    117 	argoff = asrsh = dflag = nflag = 0;
    118 	one = 1;
    119 	host = user = NULL;
    120 	sp = 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:np:u:wx"
    151 #  else
    152 #   define	OPTIONS	"8KLdek:l:np:u:w"
    153 #  endif
    154 # else
    155 #  define	OPTIONS	"8KLdel:np:u:w"
    156 # endif
    157 
    158 #else /* IN_RCMD */
    159 
    160 # ifdef KERBEROS
    161 #  ifdef CRYPT
    162 #   define	OPTIONS	"8KLdek:l:np:wx"
    163 #  else
    164 #   define	OPTIONS	"8KLdek:l:np:w"
    165 #  endif
    166 # else
    167 #  define	OPTIONS	"8KLdel:np:w"
    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 		case 'p':
    205 			service = optarg;
    206 			sp = getservbyname(service, "tcp");
    207 			if (sp == NULL) {	/* number given, no name */
    208 				sp = malloc(sizeof(*sp));
    209 				memset(sp, 0, sizeof(*sp));
    210 				sp->s_name = service;
    211 				sp->s_proto = "tcp";
    212 				sp->s_port = atoi(service);
    213 				if (sp->s_port <= 0 || sp->s_port > IPPORT_ANONMAX)
    214 					errx(1,"port must be between 1 and %d", IPPORT_ANONMAX);
    215 			}
    216 			break;
    217 #ifdef IN_RCMD
    218 		case 'u':
    219 			if (getuid() != 0 && optarg && name &&
    220 			    strcmp(name, optarg) != 0)
    221 				errx(1,"only super user can use the -u option");
    222 			locuser = optarg;
    223 			break;
    224 #endif /* IN_RCMD */
    225 #ifdef KERBEROS
    226 #ifdef CRYPT
    227 		case 'x':
    228 			doencrypt = 1;
    229 			des_set_key((des_cblock *) cred.session, schedule);
    230 			break;
    231 #endif
    232 #endif
    233 		case '?':
    234 		default:
    235 			usage();
    236 		}
    237 	optind += argoff;
    238 
    239 	/* if haven't gotten a host yet, do so */
    240 	if (!host && !(host = argv[optind++]))
    241 		usage();
    242 
    243 	/* if no further arguments, must have been called as rlogin. */
    244 	if (!argv[optind]) {
    245 #ifdef IN_RCMD
    246 		usage();
    247 #else
    248 		if (asrsh)
    249 			*argv = "rlogin";
    250 		execv(_PATH_RLOGIN, argv);
    251 		err(1, "can't exec %s", _PATH_RLOGIN);
    252 #endif
    253 	}
    254 
    255 	argc -= optind;
    256 	argv += optind;
    257 
    258 	/* Accept user1@host format, though "-l user2" overrides user1 */
    259 	p = strchr(host, '@');
    260 	if (p) {
    261 		*p = '\0';
    262 		if (!user && p > host)
    263 			user = host;
    264 		host = p + 1;
    265 		if (*host == '\0')
    266 			usage();
    267 	}
    268 	if (!user)
    269 		user = name;
    270 
    271 #ifdef KERBEROS
    272 #ifdef CRYPT
    273 	/* -x turns off -n */
    274 	if (doencrypt)
    275 		nflag = 0;
    276 #endif
    277 #endif
    278 
    279 	args = copyargs(argv);
    280 
    281 #ifdef KERBEROS
    282 	if (use_kerberos) {
    283 		if (sp == NULL) {
    284 			sp = getservbyname((doencrypt ? "ekshell" : "kshell"), "tcp");
    285 		}
    286 		if (sp == NULL) {
    287 			use_kerberos = 0;
    288 			warning("can't get entry for %s/tcp service",
    289 			    doencrypt ? "ekshell" : "kshell");
    290 		}
    291 	}
    292 #endif
    293 	if (sp == NULL)
    294 		sp = getservbyname("shell", "tcp");
    295 	if (sp == NULL)
    296 		errx(1, "shell/tcp: unknown service");
    297 
    298 #ifdef KERBEROS
    299 try_connect:
    300 	if (use_kerberos) {
    301 #if 1
    302 		struct hostent *hp;
    303 
    304 		/* fully qualify hostname (needed for krb_realmofhost) */
    305 		hp = gethostbyname(host);
    306 		if (hp != NULL && !(host = strdup(hp->h_name)))
    307 			err(1, "strdup");
    308 #endif
    309 
    310 		rem = KSUCCESS;
    311 		errno = 0;
    312 		if (dest_realm == NULL)
    313 			dest_realm = krb_realmofhost(host);
    314 
    315 #ifdef CRYPT
    316 		if (doencrypt)
    317 			rem = krcmd_mutual(&host, sp->s_port, user, args,
    318 			    &remerr, dest_realm, &cred, schedule);
    319 		else
    320 #endif
    321 			rem = krcmd(&host, sp->s_port, user, args, &remerr,
    322 			    dest_realm);
    323 		if (rem < 0) {
    324 			use_kerberos = 0;
    325 			sp = getservbyname("shell", "tcp");
    326 			if (sp == NULL)
    327 				errx(1, "shell/tcp: unknown service");
    328 			if (errno == ECONNREFUSED)
    329 				warning("remote host doesn't support Kerberos");
    330 			if (errno == ENOENT)
    331 				warning("can't provide Kerberos auth data");
    332 			goto try_connect;
    333 		}
    334 	} else {
    335 		if (doencrypt)
    336 			errx(1, "the -x flag requires Kerberos authentication.");
    337 #ifdef IN_RCMD
    338 		rem = orcmd_af(&host, sp->s_port, locuser ? locuser :
    339 #else
    340 		rem = rcmd_af(&host, sp->s_port,
    341 #endif
    342 		    name,
    343 		    user, args, &remerr, PF_UNSPEC);
    344 	}
    345 #else /* KERBEROS */
    346 
    347 #ifdef IN_RCMD
    348 	rem = orcmd_af(&host, sp->s_port, locuser ? locuser :
    349 #else
    350 	rem = rcmd_af(&host, sp->s_port,
    351 #endif
    352 	    name, user, args, &remerr, PF_UNSPEC);
    353 #endif /* KERBEROS */
    354 	(void)free(name);
    355 
    356 	if (rem < 0)
    357 		exit(1);
    358 
    359 	if (remerr < 0)
    360 		errx(1, "can't establish stderr");
    361 	if (dflag) {
    362 		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
    363 		    sizeof(one)) < 0)
    364 			warn("setsockopt remote");
    365 		if (setsockopt(remerr, SOL_SOCKET, SO_DEBUG, &one,
    366 		    sizeof(one)) < 0)
    367 			warn("setsockopt stderr");
    368 	}
    369 	proto = getprotobyname("tcp");
    370 	setsockopt(rem, proto->p_proto, TCP_NODELAY, &one, sizeof(one));
    371 	setsockopt(remerr, proto->p_proto, TCP_NODELAY, &one, sizeof(one));
    372 
    373 
    374 	(void) setuid(uid);
    375 
    376 	(void) sigemptyset(&nset);
    377 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++)
    378 		(void) sigaddset(&nset, sigs[i]);
    379 
    380 	(void) sigprocmask(SIG_BLOCK, &nset, &oset);
    381 
    382 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++) {
    383 		struct sigaction sa;
    384 
    385 		if (sa.sa_handler != SIG_IGN) {
    386 			sa.sa_handler = sendsig;
    387 			(void) sigaction(sigs[i], &sa, NULL);
    388 		}
    389 	}
    390 
    391 	if (!nflag) {
    392 		pid = fork();
    393 		if (pid < 0)
    394 			err(1, "fork");
    395 	}
    396 	else
    397 		pid = -1;
    398 
    399 #if defined(KERBEROS) && defined(CRYPT)
    400 	if (!doencrypt)
    401 #endif
    402 	{
    403 		(void)ioctl(remerr, FIONBIO, &one);
    404 		(void)ioctl(rem, FIONBIO, &one);
    405 	}
    406 
    407 	talk(nflag, &oset, pid, rem);
    408 
    409 	if (!nflag)
    410 		(void)kill(pid, SIGKILL);
    411 	exit(0);
    412 }
    413 
    414 int
    415 checkfd(struct pollfd *fdp, int outfd)
    416 {
    417 	int nr, nw;
    418 	char buf[BUFSIZ];
    419 
    420 	if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    421 		return -1;
    422 
    423 	if ((fdp->revents & POLLIN) == 0)
    424 		return 0;
    425 
    426 	errno = 0;
    427 #if defined(KERBEROS) && defined(CRYPT)
    428 	if (doencrypt)
    429 		nr = des_read(fdp->fd, buf, sizeof buf);
    430 	else
    431 #endif
    432 		nr = read(fdp->fd, buf, sizeof buf);
    433 
    434 	if (nr <= 0) {
    435 		if (errno != EAGAIN)
    436 			return -1;
    437 		else
    438 			return 0;
    439 	}
    440 	else {
    441 		char *bc = buf;
    442 		while (nr) {
    443 			if ((nw = write(outfd, bc, nr)) <= 0)
    444 				return -1;
    445 			nr -= nw;
    446 			bc += nw;
    447 		}
    448 		return 0;
    449 	}
    450 }
    451 
    452 void
    453 talk(int nflag, sigset_t *oset, __pid_t pid, int rem)
    454 {
    455 	int nr, nw, nfds;
    456 	struct pollfd fds[2], *fdp = &fds[0];
    457 	char *bp, buf[BUFSIZ];
    458 
    459 
    460 	if (!nflag && pid == 0) {
    461 		(void)close(remerr);
    462 
    463 		fdp->events = POLLOUT|POLLNVAL|POLLERR|POLLHUP;
    464 		fdp->fd = rem;
    465 		nr = 0;
    466 		bp = buf;
    467 
    468 		for (;;) {
    469 			errno = 0;
    470 
    471 			if (nr == 0) {
    472 				if ((nr = read(0, buf, sizeof buf)) == 0)
    473 					goto done;
    474 				if (nr == -1) {
    475 					if (errno == EIO)
    476 						goto done;
    477 					if (errno == EINTR)
    478 						continue;
    479 					err(1, "read");
    480 				}
    481 				bp = buf;
    482 			}
    483 
    484 rewrite:		if (poll(fdp, 1, INFTIM) == -1) {
    485 				if (errno != EINTR)
    486 					err(1, "poll");
    487 				goto rewrite;
    488 			}
    489 
    490 			if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    491 				err(1, "poll");
    492 
    493 			if ((fdp->revents & POLLOUT) == 0)
    494 				goto rewrite;
    495 
    496 #if defined(KERBEROS) && defined(CRYPT)
    497 			if (doencrypt)
    498 				nw = des_write(rem, bp, nr);
    499 			else
    500 #endif
    501 				nw = write(rem, bp, nr);
    502 
    503 			if (nw < 0) {
    504 				if (errno == EAGAIN)
    505 					continue;
    506 				err(1, "write");
    507 			}
    508 			bp += nw;
    509 			nr -= nw;
    510 		}
    511 done:
    512 		(void)shutdown(rem, 1);
    513 		exit(0);
    514 	}
    515 
    516 	(void) sigprocmask(SIG_SETMASK, oset, NULL);
    517 	fds[0].events = fds[1].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
    518 	fds[0].fd = remerr;
    519 	fds[1].fd = rem;
    520 	fdp = &fds[0];
    521 	nfds = 2;
    522 	do {
    523 		if (poll(fdp, nfds, INFTIM) == -1) {
    524 			if (errno != EINTR)
    525 				err(1, "poll");
    526 			continue;
    527 		}
    528 		if (fds[0].events != 0 && checkfd(&fds[0], 2) == -1) {
    529 			nfds--;
    530 			fds[0].events = 0;
    531 			fdp = &fds[1];
    532 		}
    533 		if (fds[1].events != 0 && checkfd(&fds[1], 1) == -1) {
    534 			nfds--;
    535 			fds[1].events = 0;
    536 		}
    537 	}
    538 	while (nfds);
    539 }
    540 
    541 void
    542 sendsig(int sig)
    543 {
    544 	char signo;
    545 
    546 	signo = sig;
    547 #ifdef KERBEROS
    548 #ifdef CRYPT
    549 	if (doencrypt)
    550 		(void)des_write(remerr, &signo, 1);
    551 	else
    552 #endif
    553 #endif
    554 		(void)write(remerr, &signo, 1);
    555 }
    556 
    557 #ifdef KERBEROS
    558 /* VARARGS */
    559 void
    560 warning(const char *fmt, ...)
    561 {
    562 	va_list ap;
    563 
    564 	va_start(ap, fmt);
    565 	(void) fprintf(stderr, "%s: warning, using standard rsh: ",
    566 	    getprogname());
    567 	(void) vfprintf(stderr, fmt, ap);
    568 	va_end(ap);
    569 	(void) fprintf(stderr, ".\n");
    570 }
    571 #endif
    572 
    573 char *
    574 copyargs(char **argv)
    575 {
    576 	int cc;
    577 	char **ap, *args, *p, *ep;
    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 	ep = args + cc;
    585 	for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
    586 		(void)strlcpy(p, *ap, ep - p);
    587 		p += strlen(p);
    588 		if (ap[1])
    589 			*p++ = ' ';
    590 	}
    591 	*p = '\0';
    592 	return (args);
    593 }
    594 
    595 void
    596 usage(void)
    597 {
    598 
    599 	(void)fprintf(stderr,
    600 	    "usage: %s [-nd%s]%s[-l login] [-p port]%s [login@]host %s\n", getprogname(),
    601 #ifdef KERBEROS
    602 #ifdef CRYPT
    603 	    "x", " [-k realm] ",
    604 #else
    605 	    "", " [-k realm] ",
    606 #endif
    607 #else
    608 	    "", " ",
    609 #endif
    610 #ifdef IN_RCMD
    611 	    " [-u locuser]", "command"
    612 #else
    613 	    "", "[command]"
    614 #endif
    615 	    );
    616 	exit(1);
    617 }
    618