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rsh.c revision 1.29 
      1 /*	$NetBSD: rsh.c,v 1.29 2006/03/23 23:49:07 wiz 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 1.29 2006/03/23 23:49:07 wiz 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 
     71 /*
     72  * rsh - remote shell
     73  */
     74 int	remerr;
     75 
     76 static int sigs[] = { SIGINT, SIGTERM, SIGQUIT };
     77 
     78 char   *copyargs(char **);
     79 void	sendsig(int);
     80 int	checkfd(struct pollfd *, int);
     81 void	talk(int, sigset_t *, pid_t, int);
     82 void	usage(void);
     83 int	main(int, char **);
     84 #ifdef IN_RCMD
     85 int	 orcmd(char **, int, const char *,
     86     const char *, const char *, int *);
     87 int	 orcmd_af(char **, int, const char *,
     88     const char *, const char *, int *, int);
     89 #endif
     90 
     91 int
     92 main(int argc, char **argv)
     93 {
     94 	struct passwd *pw;
     95 	struct servent *sp;
     96 	sigset_t oset, nset;
     97 	struct protoent *proto;
     98 
     99 #ifdef IN_RCMD
    100 	char	*locuser = 0, *loop;
    101 #endif /* IN_RCMD */
    102 	int argoff, asrsh, ch, dflag, nflag, one, rem, i;
    103 	int family = AF_UNSPEC;
    104 	pid_t pid;
    105 	uid_t uid;
    106 	char *args, *host, *p, *user, *name;
    107 
    108 	argoff = asrsh = dflag = nflag = 0;
    109 	one = 1;
    110 	host = user = NULL;
    111 	sp = NULL;
    112 
    113 #ifndef IN_RCMD
    114 	/*
    115 	 * If called as something other than "rsh" use it as the host name,
    116 	 * only for rsh.
    117 	 */
    118 	if (strcmp(getprogname(), "rsh") == 0)
    119 		asrsh = 1;
    120 	else {
    121 		host = strdup(getprogname());
    122 		if (host == NULL)
    123 			err(1, NULL);
    124 	}
    125 #endif /* IN_RCMD */
    126 
    127 	/* handle "rsh host flags" */
    128 	if (!host && argc > 2 && argv[1][0] != '-') {
    129 		host = argv[1];
    130 		argoff = 1;
    131 	}
    132 
    133 #ifdef IN_RCMD
    134 	if ((loop = getenv("RCMD_LOOP")) && strcmp(loop, "YES") == 0)
    135 		warnx("rcmd appears to be looping!");
    136 
    137 	putenv("RCMD_LOOP=YES");
    138 
    139 #  define	OPTIONS	"468KLdel:np:u:w"
    140 
    141 #else /* IN_RCMD */
    142 
    143 #  define	OPTIONS	"468KLdel:np:w"
    144 
    145 #endif /* IN_RCMD */
    146 
    147 	if (!(pw = getpwuid(uid = getuid())))
    148 		errx(1, "unknown user id");
    149 
    150 	if ((name = strdup(pw->pw_name)) == NULL)
    151 		err(1, "malloc");
    152 	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
    153 		switch(ch) {
    154 		case '4':
    155 			family = AF_INET;
    156 			break;
    157 		case '6':
    158 			family = AF_INET6;
    159 			break;
    160 		case 'K':
    161 			break;
    162 		case 'L':	/* -8Lew are ignored to allow rlogin aliases */
    163 		case 'e':
    164 		case 'w':
    165 		case '8':
    166 			break;
    167 		case 'd':
    168 			dflag = 1;
    169 			break;
    170 		case 'l':
    171 			user = optarg;
    172 			break;
    173 		case 'n':
    174 			nflag = 1;
    175 			break;
    176 		case 'p':
    177 			sp = getport(optarg, "tcp");
    178 			break;
    179 #ifdef IN_RCMD
    180 		case 'u':
    181 			if (getuid() != 0 && optarg && name &&
    182 			    strcmp(name, optarg) != 0)
    183 				errx(1,"only super user can use the -u option");
    184 			locuser = optarg;
    185 			break;
    186 #endif /* IN_RCMD */
    187 		case '?':
    188 		default:
    189 			usage();
    190 		}
    191 	optind += argoff;
    192 
    193 	/* if haven't gotten a host yet, do so */
    194 	if (!host && !(host = argv[optind++]))
    195 		usage();
    196 
    197 	/* if no further arguments, must have been called as rlogin. */
    198 	if (!argv[optind]) {
    199 #ifdef IN_RCMD
    200 		usage();
    201 #else
    202 		if (asrsh)
    203 			*argv = __UNCONST("rlogin");
    204 		execv(_PATH_RLOGIN, argv);
    205 		err(1, "can't exec %s", _PATH_RLOGIN);
    206 #endif
    207 	}
    208 
    209 	argc -= optind;
    210 	argv += optind;
    211 
    212 	/* Accept user1@host format, though "-l user2" overrides user1 */
    213 	p = strchr(host, '@');
    214 	if (p) {
    215 		*p = '\0';
    216 		if (!user && p > host)
    217 			user = host;
    218 		host = p + 1;
    219 		if (*host == '\0')
    220 			usage();
    221 	}
    222 	if (!user)
    223 		user = name;
    224 
    225 
    226 	args = copyargs(argv);
    227 
    228 	if (sp == NULL)
    229 		sp = getservbyname("shell", "tcp");
    230 	if (sp == NULL)
    231 		errx(1, "shell/tcp: unknown service");
    232 
    233 
    234 #ifdef IN_RCMD
    235 	rem = orcmd_af(&host, sp->s_port, locuser ? locuser :
    236 #else
    237 	rem = rcmd_af(&host, sp->s_port,
    238 #endif
    239 	    name, user, args, &remerr, family);
    240 	(void)free(name);
    241 
    242 	if (rem < 0)
    243 		exit(1);
    244 
    245 	if (remerr < 0)
    246 		errx(1, "can't establish stderr");
    247 	if (dflag) {
    248 		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
    249 		    sizeof(one)) < 0)
    250 			warn("setsockopt remote");
    251 		if (setsockopt(remerr, SOL_SOCKET, SO_DEBUG, &one,
    252 		    sizeof(one)) < 0)
    253 			warn("setsockopt stderr");
    254 	}
    255 	proto = getprotobyname("tcp");
    256 	setsockopt(rem, proto->p_proto, TCP_NODELAY, &one, sizeof(one));
    257 	setsockopt(remerr, proto->p_proto, TCP_NODELAY, &one, sizeof(one));
    258 
    259 
    260 	(void)setuid(uid);
    261 
    262 	(void)sigemptyset(&nset);
    263 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++)
    264 		(void)sigaddset(&nset, sigs[i]);
    265 
    266 	(void)sigprocmask(SIG_BLOCK, &nset, &oset);
    267 
    268 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++) {
    269 		struct sigaction sa;
    270 
    271 		if (sa.sa_handler != SIG_IGN) {
    272 			sa.sa_handler = sendsig;
    273 			(void)sigaction(sigs[i], &sa, NULL);
    274 		}
    275 	}
    276 
    277 	if (!nflag) {
    278 		pid = fork();
    279 		if (pid < 0)
    280 			err(1, "fork");
    281 	}
    282 	else
    283 		pid = -1;
    284 
    285 #if defined(KERBEROS) && defined(CRYPT)
    286 	if (!doencrypt)
    287 #endif
    288 	{
    289 		(void)ioctl(remerr, FIONBIO, &one);
    290 		(void)ioctl(rem, FIONBIO, &one);
    291 	}
    292 
    293 	talk(nflag, &oset, pid, rem);
    294 
    295 	if (!nflag)
    296 		(void)kill(pid, SIGKILL);
    297 	exit(0);
    298 }
    299 
    300 int
    301 checkfd(struct pollfd *fdp, int outfd)
    302 {
    303 	int nr, nw;
    304 	char buf[BUFSIZ];
    305 
    306 	if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    307 		return -1;
    308 
    309 	if ((fdp->revents & POLLIN) == 0)
    310 		return 0;
    311 
    312 	errno = 0;
    313 #if defined(KERBEROS) && defined(CRYPT)
    314 	if (doencrypt)
    315 		nr = des_read(fdp->fd, buf, sizeof buf);
    316 	else
    317 #endif
    318 		nr = read(fdp->fd, buf, sizeof buf);
    319 
    320 	if (nr <= 0) {
    321 		if (errno != EAGAIN)
    322 			return -1;
    323 		else
    324 			return 0;
    325 	}
    326 	else {
    327 		char *bc = buf;
    328 		while (nr) {
    329 			if ((nw = write(outfd, bc, nr)) <= 0)
    330 				return -1;
    331 			nr -= nw;
    332 			bc += nw;
    333 		}
    334 		return 0;
    335 	}
    336 }
    337 
    338 void
    339 talk(int nflag, sigset_t *oset, __pid_t pid, int rem)
    340 {
    341 	int nr, nw, nfds;
    342 	struct pollfd fds[2], *fdp = &fds[0];
    343 	char *bp, buf[BUFSIZ];
    344 
    345 	if (!nflag && pid == 0) {
    346 		(void)close(remerr);
    347 
    348 		fdp->events = POLLOUT|POLLNVAL|POLLERR|POLLHUP;
    349 		fdp->fd = rem;
    350 		nr = 0;
    351 		bp = buf;
    352 
    353 		for (;;) {
    354 			errno = 0;
    355 
    356 			if (nr == 0) {
    357 				if ((nr = read(0, buf, sizeof buf)) == 0)
    358 					goto done;
    359 				if (nr == -1) {
    360 					if (errno == EIO)
    361 						goto done;
    362 					if (errno == EINTR) {
    363 						nr = 0;
    364 						continue;
    365 					}
    366 					err(1, "read");
    367 				}
    368 				bp = buf;
    369 			}
    370 
    371 rewrite:		if (poll(fdp, 1, INFTIM) == -1) {
    372 				if (errno != EINTR)
    373 					err(1, "poll");
    374 				goto rewrite;
    375 			}
    376 
    377 			if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    378 				err(1, "poll");
    379 
    380 			if ((fdp->revents & POLLOUT) == 0)
    381 				goto rewrite;
    382 
    383 #if defined(KERBEROS) && defined(CRYPT)
    384 			if (doencrypt)
    385 				nw = des_write(rem, bp, nr);
    386 			else
    387 #endif
    388 				nw = write(rem, bp, nr);
    389 
    390 			if (nw < 0) {
    391 				if (errno == EAGAIN)
    392 					continue;
    393 				err(1, "write");
    394 			}
    395 			bp += nw;
    396 			nr -= nw;
    397 		}
    398 done:
    399 		(void)shutdown(rem, 1);
    400 		exit(0);
    401 	}
    402 
    403 	(void)sigprocmask(SIG_SETMASK, oset, NULL);
    404 	fds[0].events = fds[1].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
    405 	fds[0].fd = remerr;
    406 	fds[1].fd = rem;
    407 	fdp = &fds[0];
    408 	nfds = 2;
    409 	do {
    410 		if (poll(fdp, nfds, INFTIM) == -1) {
    411 			if (errno != EINTR)
    412 				err(1, "poll");
    413 			continue;
    414 		}
    415 		if (fds[0].events != 0 && checkfd(&fds[0], 2) == -1) {
    416 			nfds--;
    417 			fds[0].events = 0;
    418 			fdp = &fds[1];
    419 		}
    420 		if (fds[1].events != 0 && checkfd(&fds[1], 1) == -1) {
    421 			nfds--;
    422 			fds[1].events = 0;
    423 		}
    424 	}
    425 	while (nfds);
    426 }
    427 
    428 void
    429 sendsig(int sig)
    430 {
    431 	char signo;
    432 
    433 	signo = sig;
    434 		(void)write(remerr, &signo, 1);
    435 }
    436 
    437 
    438 char *
    439 copyargs(char **argv)
    440 {
    441 	int cc;
    442 	char **ap, *args, *p, *ep;
    443 
    444 	cc = 0;
    445 	for (ap = argv; *ap; ++ap)
    446 		cc += strlen(*ap) + 1;
    447 	if (!(args = malloc((u_int)cc)))
    448 		err(1, "malloc");
    449 	ep = args + cc;
    450 	for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
    451 		(void)strlcpy(p, *ap, ep - p);
    452 		p += strlen(p);
    453 		if (ap[1])
    454 			*p++ = ' ';
    455 	}
    456 	*p = '\0';
    457 	return (args);
    458 }
    459 
    460 void
    461 usage(void)
    462 {
    463 
    464 	(void)fprintf(stderr,
    465 	    "usage: %s [-46dn] [-l login] [-p port]%s [login@]host command\n",
    466 	    getprogname(),
    467 #ifdef IN_RCMD
    468 	    " [-u locuser]"
    469 #else
    470 	    ""
    471 #endif
    472 	    );
    473 	exit(1);
    474 }
    475