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rsh.c revision 1.32 
      1 /*	$NetBSD: rsh.c,v 1.32 2010/10/02 09:24:16 gson 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\
     35  The Regents of the University of California.  All rights reserved.");
     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 1.32 2010/10/02 09:24:16 gson 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;
    103 	size_t i;
    104 	int family = AF_UNSPEC;
    105 	pid_t pid;
    106 	uid_t uid;
    107 	char *args, *host, *p, *user, *name;
    108 
    109 	argoff = asrsh = dflag = nflag = 0;
    110 	one = 1;
    111 	host = user = NULL;
    112 	sp = NULL;
    113 
    114 #ifndef IN_RCMD
    115 	/*
    116 	 * If called as something other than "rsh" use it as the host name,
    117 	 * only for rsh.
    118 	 */
    119 	if (strcmp(getprogname(), "rsh") == 0)
    120 		asrsh = 1;
    121 	else {
    122 		host = strdup(getprogname());
    123 		if (host == NULL)
    124 			err(1, NULL);
    125 	}
    126 #endif /* IN_RCMD */
    127 
    128 	/* handle "rsh host flags" */
    129 	if (!host && argc > 2 && argv[1][0] != '-') {
    130 		host = argv[1];
    131 		argoff = 1;
    132 	}
    133 
    134 #ifdef IN_RCMD
    135 	if ((loop = getenv("RCMD_LOOP")) && strcmp(loop, "YES") == 0)
    136 		warnx("rcmd appears to be looping!");
    137 
    138 	setenv("RCMD_LOOP", "YES", 1);
    139 
    140 #  define	OPTIONS	"468KLdel:np:u:w"
    141 
    142 #else /* IN_RCMD */
    143 
    144 #  define	OPTIONS	"468KLdel:np:w"
    145 
    146 #endif /* IN_RCMD */
    147 
    148 	if (!(pw = getpwuid(uid = getuid())))
    149 		errx(1, "unknown user id");
    150 
    151 	if ((name = strdup(pw->pw_name)) == NULL)
    152 		err(1, "malloc");
    153 	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
    154 		switch(ch) {
    155 		case '4':
    156 			family = AF_INET;
    157 			break;
    158 		case '6':
    159 			family = AF_INET6;
    160 			break;
    161 		case 'K':
    162 			break;
    163 		case 'L':	/* -8Lew are ignored to allow rlogin aliases */
    164 		case 'e':
    165 		case 'w':
    166 		case '8':
    167 			break;
    168 		case 'd':
    169 			dflag = 1;
    170 			break;
    171 		case 'l':
    172 			user = optarg;
    173 			break;
    174 		case 'n':
    175 			nflag = 1;
    176 			break;
    177 		case 'p':
    178 			sp = getport(optarg, "tcp");
    179 			break;
    180 #ifdef IN_RCMD
    181 		case 'u':
    182 			if (getuid() != 0 && optarg && name &&
    183 			    strcmp(name, optarg) != 0)
    184 				errx(1,"only super user can use the -u option");
    185 			locuser = optarg;
    186 			break;
    187 #endif /* IN_RCMD */
    188 		case '?':
    189 		default:
    190 			usage();
    191 		}
    192 	optind += argoff;
    193 
    194 	/* if haven't gotten a host yet, do so */
    195 	if (!host && !(host = argv[optind++]))
    196 		usage();
    197 
    198 	/* if no further arguments, must have been called as rlogin. */
    199 	if (!argv[optind]) {
    200 #ifdef IN_RCMD
    201 		usage();
    202 #else
    203 		if (asrsh)
    204 			*argv = __UNCONST("rlogin");
    205 		execv(_PATH_RLOGIN, argv);
    206 		err(1, "can't exec %s", _PATH_RLOGIN);
    207 #endif
    208 	}
    209 
    210 	argc -= optind;
    211 	argv += optind;
    212 
    213 	/* Accept user1@host format, though "-l user2" overrides user1 */
    214 	p = strchr(host, '@');
    215 	if (p) {
    216 		*p = '\0';
    217 		if (!user && p > host)
    218 			user = host;
    219 		host = p + 1;
    220 		if (*host == '\0')
    221 			usage();
    222 	}
    223 	if (!user)
    224 		user = name;
    225 
    226 
    227 	args = copyargs(argv);
    228 
    229 	if (sp == NULL)
    230 		sp = getservbyname("shell", "tcp");
    231 	if (sp == NULL)
    232 		errx(1, "shell/tcp: unknown service");
    233 
    234 
    235 #ifdef IN_RCMD
    236 	rem = orcmd_af(&host, sp->s_port, locuser ? locuser :
    237 #else
    238 	rem = rcmd_af(&host, sp->s_port,
    239 #endif
    240 	    name, user, args, &remerr, family);
    241 	(void)free(name);
    242 
    243 	if (rem < 0)
    244 		exit(1);
    245 
    246 	if (remerr < 0)
    247 		errx(1, "can't establish stderr");
    248 	if (dflag) {
    249 		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
    250 		    sizeof(one)) < 0)
    251 			warn("setsockopt remote");
    252 		if (setsockopt(remerr, SOL_SOCKET, SO_DEBUG, &one,
    253 		    sizeof(one)) < 0)
    254 			warn("setsockopt stderr");
    255 	}
    256 	proto = getprotobyname("tcp");
    257 	setsockopt(rem, proto->p_proto, TCP_NODELAY, &one, sizeof(one));
    258 	setsockopt(remerr, proto->p_proto, TCP_NODELAY, &one, sizeof(one));
    259 
    260 
    261 	(void)setuid(uid);
    262 
    263 	(void)sigemptyset(&nset);
    264 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++)
    265 		(void)sigaddset(&nset, sigs[i]);
    266 
    267 	(void)sigprocmask(SIG_BLOCK, &nset, &oset);
    268 
    269 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++) {
    270 		struct sigaction sa;
    271 
    272 		if (sa.sa_handler != SIG_IGN) {
    273 			sa.sa_handler = sendsig;
    274 			(void)sigaction(sigs[i], &sa, NULL);
    275 		}
    276 	}
    277 
    278 	if (!nflag) {
    279 		pid = fork();
    280 		if (pid < 0)
    281 			err(1, "fork");
    282 	}
    283 	else
    284 		pid = -1;
    285 
    286 #if defined(KERBEROS) && defined(CRYPT)
    287 	if (!doencrypt)
    288 #endif
    289 	{
    290 		(void)ioctl(remerr, FIONBIO, &one);
    291 		(void)ioctl(rem, FIONBIO, &one);
    292 	}
    293 
    294 	talk(nflag, &oset, pid, rem);
    295 
    296 	if (!nflag)
    297 		(void)kill(pid, SIGKILL);
    298 	exit(0);
    299 }
    300 
    301 int
    302 checkfd(struct pollfd *fdp, int outfd)
    303 {
    304 	int nr, nw;
    305 	char buf[BUFSIZ];
    306 
    307 	if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    308 		return -1;
    309 
    310 	if ((fdp->revents & POLLIN) == 0)
    311 		return 0;
    312 
    313 	errno = 0;
    314 #if defined(KERBEROS) && defined(CRYPT)
    315 	if (doencrypt)
    316 		nr = des_read(fdp->fd, buf, sizeof buf);
    317 	else
    318 #endif
    319 		nr = read(fdp->fd, buf, sizeof buf);
    320 
    321 	if (nr <= 0) {
    322 		if (errno != EAGAIN)
    323 			return -1;
    324 		else
    325 			return 0;
    326 	}
    327 	else {
    328 		char *bc = buf;
    329 		while (nr) {
    330 			if ((nw = write(outfd, bc, nr)) <= 0)
    331 				return -1;
    332 			nr -= nw;
    333 			bc += nw;
    334 		}
    335 		return 0;
    336 	}
    337 }
    338 
    339 void
    340 talk(int nflag, sigset_t *oset, __pid_t pid, int rem)
    341 {
    342 	int nr, nw, nfds;
    343 	struct pollfd fds[2], *fdp = &fds[0];
    344 	char *bp, buf[BUFSIZ];
    345 
    346 	if (!nflag && pid == 0) {
    347 		(void)close(remerr);
    348 
    349 		fdp->events = POLLOUT|POLLNVAL|POLLERR|POLLHUP;
    350 		fdp->fd = rem;
    351 		nr = 0;
    352 		bp = buf;
    353 
    354 		for (;;) {
    355 			errno = 0;
    356 
    357 			if (nr == 0) {
    358 				if ((nr = read(0, buf, sizeof buf)) == 0)
    359 					goto done;
    360 				if (nr == -1) {
    361 					if (errno == EIO)
    362 						goto done;
    363 					if (errno == EINTR) {
    364 						nr = 0;
    365 						continue;
    366 					}
    367 					err(1, "read");
    368 				}
    369 				bp = buf;
    370 			}
    371 
    372 rewrite:		if (poll(fdp, 1, INFTIM) == -1) {
    373 				if (errno != EINTR)
    374 					err(1, "poll");
    375 				goto rewrite;
    376 			}
    377 
    378 			if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
    379 				err(1, "poll");
    380 
    381 			if ((fdp->revents & POLLOUT) == 0)
    382 				goto rewrite;
    383 
    384 #if defined(KERBEROS) && defined(CRYPT)
    385 			if (doencrypt)
    386 				nw = des_write(rem, bp, nr);
    387 			else
    388 #endif
    389 				nw = write(rem, bp, nr);
    390 
    391 			if (nw < 0) {
    392 				if (errno == EAGAIN)
    393 					continue;
    394 				err(1, "write");
    395 			}
    396 			bp += nw;
    397 			nr -= nw;
    398 		}
    399 done:
    400 		(void)shutdown(rem, 1);
    401 		exit(0);
    402 	}
    403 
    404 	(void)sigprocmask(SIG_SETMASK, oset, NULL);
    405 	fds[0].events = fds[1].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
    406 	fds[0].fd = remerr;
    407 	fds[1].fd = rem;
    408 	fdp = &fds[0];
    409 	nfds = 2;
    410 	do {
    411 		if (poll(fdp, nfds, INFTIM) == -1) {
    412 			if (errno != EINTR)
    413 				err(1, "poll");
    414 			continue;
    415 		}
    416 		if (fds[0].events != 0 && checkfd(&fds[0], 2) == -1) {
    417 			nfds--;
    418 			fds[0].events = 0;
    419 			fdp = &fds[1];
    420 		}
    421 		if (fds[1].events != 0 && checkfd(&fds[1], 1) == -1) {
    422 			nfds--;
    423 			fds[1].events = 0;
    424 		}
    425 	}
    426 	while (nfds);
    427 }
    428 
    429 void
    430 sendsig(int sig)
    431 {
    432 	char signo;
    433 
    434 	signo = sig;
    435 		(void)write(remerr, &signo, 1);
    436 }
    437 
    438 
    439 char *
    440 copyargs(char **argv)
    441 {
    442 	int cc;
    443 	char **ap, *args, *p, *ep;
    444 
    445 	cc = 0;
    446 	for (ap = argv; *ap; ++ap)
    447 		cc += strlen(*ap) + 1;
    448 	if (!(args = malloc((u_int)cc)))
    449 		err(1, "malloc");
    450 	ep = args + cc;
    451 	for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
    452 		(void)strlcpy(p, *ap, ep - p);
    453 		p += strlen(p);
    454 		if (ap[1])
    455 			*p++ = ' ';
    456 	}
    457 	*p = '\0';
    458 	return (args);
    459 }
    460 
    461 void
    462 usage(void)
    463 {
    464 
    465 	(void)fprintf(stderr,
    466 	    "usage: %s [-46dn] [-l login] [-p port]%s [login@]host command\n",
    467 	    getprogname(),
    468 #ifdef IN_RCMD
    469 	    " [-u locuser]"
    470 #else
    471 	    ""
    472 #endif
    473 	    );
    474 	exit(1);
    475 }
    476