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rsh.c revision 1.7 
      1 /*	$NetBSD: rsh.c,v 1.7 1997/05/26 14:29:36 mrg 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 #ifndef lint
     37 static char copyright[] =
     38 "@(#) 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 /*static char sccsid[] = "from: @(#)rsh.c	8.4 (Berkeley) 4/29/95";*/
     44 static char rcsid[] = "$NetBSD: rsh.c,v 1.7 1997/05/26 14:29:36 mrg Exp $";
     45 #endif /* not lint */
     46 
     47 #include <sys/types.h>
     48 #include <sys/socket.h>
     49 #include <sys/ioctl.h>
     50 #include <sys/file.h>
     51 #include <poll.h>
     52 
     53 #include <netinet/in.h>
     54 #include <netdb.h>
     55 
     56 #include <err.h>
     57 #include <errno.h>
     58 #include <pwd.h>
     59 #include <signal.h>
     60 #include <stdio.h>
     61 #include <stdlib.h>
     62 #include <string.h>
     63 #include <unistd.h>
     64 #include <varargs.h>
     65 
     66 #include "pathnames.h"
     67 
     68 #ifdef KERBEROS
     69 #include <kerberosIV/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 extern char *krb_realmofhost();
     77 #endif
     78 
     79 /*
     80  * rsh - remote shell
     81  */
     82 extern	char *__progname;		/* XXX */
     83 int	rfd2;
     84 
     85 char   *copyargs __P((char **));
     86 void	sendsig __P((int));
     87 void	talk __P((int, long, pid_t, int));
     88 void	usage __P((void));
     89 void	warning __P(());
     90 
     91 int
     92 main(argc, argv)
     93 	int argc;
     94 	char **argv;
     95 {
     96 	struct passwd *pw;
     97 	struct servent *sp;
     98 	long omask;
     99 #ifdef IN_RCMD
    100 	char	*locuser = 0, *loop;
    101 #endif /* IN_RCMD */
    102 	int argoff, asrsh, ch, dflag, nflag, one, rem;
    103 	pid_t pid;
    104 	uid_t uid;
    105 	char *args, *host, *p, *user;
    106 
    107 	argoff = asrsh = dflag = nflag = 0;
    108 	one = 1;
    109 	host = user = NULL;
    110 
    111 	/*
    112 	 * If called as something other than "rsh" or "rcmd", use it as the
    113 	 * host name
    114 	 */
    115 	p = __progname;
    116 	if (strcmp(p, "rsh") == 0
    117 #ifdef IN_RCMD
    118 	    || strcmp(p, "rcmd") == 0
    119 #endif /* IN_RCMD */
    120 	    )
    121 		asrsh = 1;
    122 	else
    123 		host = p;
    124 
    125 	/* handle "rsh host flags" */
    126 	if (!host && argc > 2 && argv[1][0] != '-') {
    127 		host = argv[1];
    128 		argoff = 1;
    129 	}
    130 
    131 #ifdef IN_RCMD
    132 
    133 	if ((loop = getenv("RCMD_LOOP")) && strcmp(loop, "YES") == 0)
    134 		warnx("rcmd appears to be looping!");
    135 
    136 	putenv("RCMD_LOOP=YES");
    137 
    138 # ifdef KERBEROS
    139 #  ifdef CRYPT
    140 #   define	OPTIONS	"8KLdek:l:nu:wx"
    141 #  else
    142 #   define	OPTIONS	"8KLdek:l:nu:w"
    143 #  endif
    144 # else
    145 #  define	OPTIONS	"8KLdel:nu:w"
    146 # endif
    147 
    148 #else /* IN_RCMD */
    149 
    150 # ifdef KERBEROS
    151 #  ifdef CRYPT
    152 #   define	OPTIONS	"8KLdek:l:nwx"
    153 #  else
    154 #   define	OPTIONS	"8KLdek:l:nw"
    155 #  endif
    156 # else
    157 #  define	OPTIONS	"8KLdel:nw"
    158 # endif
    159 
    160 #endif /* IN_RCMD */
    161 
    162 	if (!(pw = getpwuid(uid = getuid())))
    163 		errx(1, "unknown user id");
    164 
    165 	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != EOF)
    166 		switch(ch) {
    167 		case 'K':
    168 #ifdef KERBEROS
    169 			use_kerberos = 0;
    170 #endif
    171 			break;
    172 		case 'L':	/* -8Lew are ignored to allow rlogin aliases */
    173 		case 'e':
    174 		case 'w':
    175 		case '8':
    176 			break;
    177 		case 'd':
    178 			dflag = 1;
    179 			break;
    180 		case 'l':
    181 			user = optarg;
    182 			break;
    183 #ifdef KERBEROS
    184 		case 'k':
    185 			dest_realm = dst_realm_buf;
    186 			strncpy(dest_realm, optarg, REALM_SZ);
    187 			break;
    188 #endif
    189 		case 'n':
    190 			nflag = 1;
    191 			break;
    192 #ifdef IN_RCMD
    193 		case 'u':
    194 			if (getuid() != 0 && optarg && pw->pw_name &&
    195 			    strcmp(pw->pw_name, optarg) != 0)
    196 				errx(1,"only super user can use the -u option");
    197 			locuser = optarg;
    198 			break;
    199 #endif /* IN_RCMD */
    200 #ifdef KERBEROS
    201 #ifdef CRYPT
    202 		case 'x':
    203 			doencrypt = 1;
    204 			des_set_key(cred.session, schedule);
    205 			break;
    206 #endif
    207 #endif
    208 		case '?':
    209 		default:
    210 			usage();
    211 		}
    212 	optind += argoff;
    213 
    214 	/* if haven't gotten a host yet, do so */
    215 	if (!host && !(host = argv[optind++]))
    216 		usage();
    217 
    218 	/* if no further arguments, must have been called as rlogin. */
    219 	if (!argv[optind]) {
    220 #ifdef IN_RCMD
    221 		usage();
    222 #else
    223 		if (asrsh)
    224 			*argv = "rlogin";
    225 		execv(_PATH_RLOGIN, argv);
    226 		err(1, "can't exec %s", _PATH_RLOGIN);
    227 #endif
    228 	}
    229 
    230 	argc -= optind;
    231 	argv += optind;
    232 
    233 	/* Accept user1@host format, though "-l user2" overrides user1 */
    234 	p = strchr(host, '@');
    235 	if (p) {
    236 		*p = '\0';
    237 		if (!user && p > host)
    238 			user = host;
    239 		host = p + 1;
    240 		if (*host == '\0')
    241 			usage();
    242 	}
    243 	if (!user)
    244 		user = pw->pw_name;
    245 
    246 #ifdef KERBEROS
    247 #ifdef CRYPT
    248 	/* -x turns off -n */
    249 	if (doencrypt)
    250 		nflag = 0;
    251 #endif
    252 #endif
    253 
    254 	args = copyargs(argv);
    255 
    256 	sp = NULL;
    257 #ifdef KERBEROS
    258 	if (use_kerberos) {
    259 		sp = getservbyname((doencrypt ? "ekshell" : "kshell"), "tcp");
    260 		if (sp == NULL) {
    261 			use_kerberos = 0;
    262 			warning("can't get entry for %s/tcp service",
    263 			    doencrypt ? "ekshell" : "kshell");
    264 		}
    265 	}
    266 #endif
    267 	if (sp == NULL)
    268 		sp = getservbyname("shell", "tcp");
    269 	if (sp == NULL)
    270 		errx(1, "shell/tcp: unknown service");
    271 
    272 #ifdef KERBEROS
    273 try_connect:
    274 	if (use_kerberos) {
    275 #if 1
    276 		struct hostent *hp;
    277 
    278 		/* fully qualify hostname (needed for krb_realmofhost) */
    279 		hp = gethostbyname(host);
    280 		if (hp != NULL && !(host = strdup(hp->h_name)))
    281 			err(1, NULL);
    282 #endif
    283 
    284 		rem = KSUCCESS;
    285 		errno = 0;
    286 		if (dest_realm == NULL)
    287 			dest_realm = krb_realmofhost(host);
    288 
    289 #ifdef CRYPT
    290 		if (doencrypt)
    291 			rem = krcmd_mutual(&host, sp->s_port, user, args,
    292 			    &rfd2, dest_realm, &cred, schedule);
    293 		else
    294 #endif
    295 			rem = krcmd(&host, sp->s_port, user, args, &rfd2,
    296 			    dest_realm);
    297 		if (rem < 0) {
    298 			use_kerberos = 0;
    299 			sp = getservbyname("shell", "tcp");
    300 			if (sp == NULL)
    301 				errx(1, "shell/tcp: unknown service");
    302 			if (errno == ECONNREFUSED)
    303 				warning("remote host doesn't support Kerberos");
    304 			if (errno == ENOENT)
    305 				warning("can't provide Kerberos auth data");
    306 			goto try_connect;
    307 		}
    308 	} else {
    309 		if (doencrypt)
    310 			errx(1, "the -x flag requires Kerberos authentication.");
    311 #ifdef IN_RCMD
    312 		rem = orcmd(&host, sp->s_port, locuser ? locuser :
    313 #else
    314 		rem = rcmd(&host, sp->s_port,
    315 #endif
    316 		    pw->pw_name,
    317 		    user, args, &rfd2);
    318 	}
    319 #else /* KERBEROS */
    320 
    321 #ifdef IN_RCMD
    322 	rem = orcmd(&host, sp->s_port, locuser ? locuser :
    323 #else
    324 	rem = rcmd(&host, sp->s_port,
    325 #endif
    326 	    pw->pw_name, user,
    327 	    args, &rfd2);
    328 #endif /* KERBEROS */
    329 
    330 	if (rem < 0)
    331 		exit(1);
    332 
    333 	if (rfd2 < 0)
    334 		errx(1, "can't establish stderr");
    335 	if (dflag) {
    336 		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
    337 		    sizeof(one)) < 0)
    338 			warn("setsockopt remote");
    339 		if (setsockopt(rfd2, SOL_SOCKET, SO_DEBUG, &one,
    340 		    sizeof(one)) < 0)
    341 			warn("setsockopt stderr");
    342 	}
    343 
    344 	(void)setuid(uid);
    345 	omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGTERM));
    346 	if (signal(SIGINT, SIG_IGN) != SIG_IGN)
    347 		(void)signal(SIGINT, sendsig);
    348 	if (signal(SIGQUIT, SIG_IGN) != SIG_IGN)
    349 		(void)signal(SIGQUIT, sendsig);
    350 	if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
    351 		(void)signal(SIGTERM, sendsig);
    352 
    353 	if (!nflag) {
    354 		pid = fork();
    355 		if (pid < 0)
    356 			err(1, "fork");
    357 	}
    358 
    359 #ifdef KERBEROS
    360 #ifdef CRYPT
    361 	if (!doencrypt)
    362 #endif
    363 #endif
    364 	{
    365 		(void)ioctl(rfd2, FIONBIO, &one);
    366 		(void)ioctl(rem, FIONBIO, &one);
    367 	}
    368 
    369 	talk(nflag, omask, pid, rem);
    370 
    371 	if (!nflag)
    372 		(void)kill(pid, SIGKILL);
    373 	exit(0);
    374 }
    375 
    376 void
    377 talk(nflag, omask, pid, rem)
    378 	int nflag;
    379 	long omask;
    380 	pid_t pid;
    381 	int rem;
    382 {
    383 	int cc, wc, nfds;
    384 	struct pollfd fds[2], *fdp = &fds[0];
    385 	char *bp, buf[BUFSIZ];
    386 
    387 	if (!nflag && pid == 0) {
    388 		(void)close(rfd2);
    389 
    390 reread:		errno = 0;
    391 		if ((cc = read(0, buf, sizeof buf)) <= 0)
    392 			goto done;
    393 		bp = buf;
    394 
    395 rewrite:	fdp->events = POLLOUT;
    396 		fdp->fd = rem;
    397 		if (poll(fdp, 1, 0) < 0) {
    398 			if (errno != EINTR)
    399 				err(1, "poll");
    400 			goto rewrite;
    401 		}
    402 		if ((fdp->revents & POLLOUT) == 0)
    403 			goto rewrite;
    404 #ifdef KERBEROS
    405 #ifdef CRYPT
    406 		if (doencrypt)
    407 			wc = des_write(rem, bp, cc);
    408 		else
    409 #endif
    410 #endif
    411 			wc = write(rem, bp, cc);
    412 		if (wc < 0) {
    413 			if (errno == EWOULDBLOCK)
    414 				goto rewrite;
    415 			goto done;
    416 		}
    417 		bp += wc;
    418 		cc -= wc;
    419 		if (cc == 0)
    420 			goto reread;
    421 		goto rewrite;
    422 done:
    423 		(void)shutdown(rem, 1);
    424 		exit(0);
    425 	}
    426 
    427 	(void)sigsetmask(omask);
    428 	fds[0].events = fds[1].events = POLLIN;
    429 	fds[0].fd = rfd2;
    430 	fds[1].fd = rem;
    431 	fdp = &fds[0];
    432 	nfds = 2;
    433 	do {
    434 		if (poll(fdp, nfds, 0) < 0) {
    435 			if (errno != EINTR)
    436 				err(1, "poll");
    437 			continue;
    438 		}
    439 		if (fds[0].events == POLLIN && (fds[0].revents & POLLIN)) {
    440 			errno = 0;
    441 #ifdef KERBEROS
    442 #ifdef CRYPT
    443 			if (doencrypt)
    444 				cc = des_read(rfd2, buf, sizeof buf);
    445 			else
    446 #endif
    447 #endif
    448 				cc = read(rfd2, buf, sizeof buf);
    449 			if (cc <= 0) {
    450 				if (errno != EWOULDBLOCK) {
    451 					nfds--;
    452 					fds[0].events = 0;
    453 					fdp = &fds[1];
    454 				}
    455 			} else
    456 				(void)write(2, buf, cc);
    457 		}
    458 		if (fds[1].events == POLLIN && (fds[1].revents & POLLIN)) {
    459 			errno = 0;
    460 #ifdef KERBEROS
    461 #ifdef CRYPT
    462 			if (doencrypt)
    463 				cc = des_read(rem, buf, sizeof buf);
    464 			else
    465 #endif
    466 #endif
    467 				cc = read(rem, buf, sizeof buf);
    468 			if (cc <= 0) {
    469 				if (errno != EWOULDBLOCK) {
    470 					nfds--;
    471 					fds[1].events = 0;
    472 				}
    473 			} else
    474 				(void)write(1, buf, cc);
    475 		}
    476 	} while (nfds);
    477 }
    478 
    479 void
    480 sendsig(sig)
    481 	int sig;
    482 {
    483 	char signo;
    484 
    485 	signo = sig;
    486 #ifdef KERBEROS
    487 #ifdef CRYPT
    488 	if (doencrypt)
    489 		(void)des_write(rfd2, &signo, 1);
    490 	else
    491 #endif
    492 #endif
    493 		(void)write(rfd2, &signo, 1);
    494 }
    495 
    496 #ifdef KERBEROS
    497 /* VARARGS */
    498 void
    499 warning(va_alist)
    500 va_dcl
    501 {
    502 	va_list ap;
    503 	char *fmt;
    504 
    505 	(void)fprintf(stderr, "rsh: warning, using standard rsh: ");
    506 	va_start(ap);
    507 	fmt = va_arg(ap, char *);
    508 	vfprintf(stderr, fmt, ap);
    509 	va_end(ap);
    510 	(void)fprintf(stderr, ".\n");
    511 }
    512 #endif
    513 
    514 char *
    515 copyargs(argv)
    516 	char **argv;
    517 {
    518 	int cc;
    519 	char **ap, *args, *p;
    520 
    521 	cc = 0;
    522 	for (ap = argv; *ap; ++ap)
    523 		cc += strlen(*ap) + 1;
    524 	if (!(args = malloc((u_int)cc)))
    525 		errx(1, "%s", strerror(ENOMEM));
    526 	for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
    527 		strcat(p, *ap);
    528 		p += strlen(p);
    529 		if (ap[1])
    530 			*p++ = ' ';
    531 	}
    532 	*p = '\0';
    533 	return (args);
    534 }
    535 
    536 void
    537 usage()
    538 {
    539 
    540 	(void)fprintf(stderr,
    541 	    "usage: %s [-nd%s]%s[-l login]%s [login@]host %s\n", __progname,
    542 #ifdef KERBEROS
    543 #ifdef CRYPT
    544 	    "x", " [-k realm] ",
    545 #else
    546 	    "", " [-k realm] ",
    547 #endif
    548 #else
    549 	    "", " ",
    550 #endif
    551 #ifdef IN_RCMD
    552 	    " [-u locuser]", "command"
    553 #else
    554 	    "", "[command]"
    555 #endif
    556 	    );
    557 	exit(1);
    558 }
    559