xref: /netbsd/usr.bin/rsh/rsh.c (revision bf9ec67e) 
1 /*	$NetBSD: rsh.c,v 1.14 2001/02/19 23:03:51 cgd 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 #include <sys/cdefs.h>
37 #ifndef lint
38 __COPYRIGHT("@(#) 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 #if 0
44 static char sccsid[] = "@(#)rsh.c	8.4 (Berkeley) 4/29/95";
45 #else
46 __RCSID("$NetBSD: rsh.c,v 1.14 2001/02/19 23:03:51 cgd Exp $");
47 #endif
48 #endif /* not lint */
49 
50 #include <sys/types.h>
51 #include <sys/socket.h>
52 #include <sys/ioctl.h>
53 #include <sys/file.h>
54 #include <poll.h>
55 
56 #include <netinet/in.h>
57 #include <netdb.h>
58 
59 #include <err.h>
60 #include <errno.h>
61 #include <pwd.h>
62 #include <signal.h>
63 #include <stdio.h>
64 #include <stdlib.h>
65 #include <string.h>
66 #include <unistd.h>
67 #ifdef __STDC__
68 #include <stdarg.h>
69 #else
70 #include <varargs.h>
71 #endif
72 
73 #include "pathnames.h"
74 
75 #ifdef KERBEROS
76 #include <kerberosIV/des.h>
77 #include <kerberosIV/krb.h>
78 
79 CREDENTIALS cred;
80 Key_schedule schedule;
81 int use_kerberos = 1, doencrypt;
82 char dst_realm_buf[REALM_SZ], *dest_realm;
83 
84 void	warning __P((const char *, ...));
85 #endif
86 
87 /*
88  * rsh - remote shell
89  */
90 int	remerr;
91 
92 static int sigs[] = { SIGINT, SIGTERM, SIGQUIT };
93 
94 char   *copyargs __P((char **));
95 void	sendsig __P((int));
96 int	checkfd __P((struct pollfd *, int));
97 void	talk __P((int, sigset_t *, pid_t, int));
98 void	usage __P((void));
99 int	main __P((int, char **));
100 #ifdef IN_RCMD
101 int	 orcmd __P((char **, int, const char *,
102     const char *, const char *, int *));
103 int	 orcmd_af __P((char **, int, const char *,
104     const char *, const char *, int *, int));
105 #endif
106 
107 int
108 main(argc, argv)
109 	int argc;
110 	char **argv;
111 {
112 	struct passwd *pw;
113 	struct servent *sp;
114 	sigset_t oset, nset;
115 
116 #ifdef IN_RCMD
117 	char	*locuser = 0, *loop;
118 #endif /* IN_RCMD */
119 	int argoff, asrsh, ch, dflag, nflag, one, rem, i;
120 	pid_t pid;
121 	uid_t uid;
122 	char *args, *host, *p, *user, *name;
123 
124 	argoff = asrsh = dflag = nflag = 0;
125 	one = 1;
126 	host = user = NULL;
127 
128 #ifndef IN_RCMD
129 	/*
130 	 * If called as something other than "rsh" use it as the host name,
131 	 * only for rsh.
132 	 */
133 	if (strcmp(getprogname(), "rsh") == 0)
134 		asrsh = 1;
135 	else {
136 		host = strdup(getprogname());
137 		if (host == NULL)
138 			err(1, NULL);
139 	}
140 #endif /* IN_RCMD */
141 
142 	/* handle "rsh host flags" */
143 	if (!host && argc > 2 && argv[1][0] != '-') {
144 		host = argv[1];
145 		argoff = 1;
146 	}
147 
148 #ifdef IN_RCMD
149 	if ((loop = getenv("RCMD_LOOP")) && strcmp(loop, "YES") == 0)
150 		warnx("rcmd appears to be looping!");
151 
152 	putenv("RCMD_LOOP=YES");
153 
154 # ifdef KERBEROS
155 #  ifdef CRYPT
156 #   define	OPTIONS	"8KLdek:l:nu:wx"
157 #  else
158 #   define	OPTIONS	"8KLdek:l:nu:w"
159 #  endif
160 # else
161 #  define	OPTIONS	"8KLdel:nu:w"
162 # endif
163 
164 #else /* IN_RCMD */
165 
166 # ifdef KERBEROS
167 #  ifdef CRYPT
168 #   define	OPTIONS	"8KLdek:l:nwx"
169 #  else
170 #   define	OPTIONS	"8KLdek:l:nw"
171 #  endif
172 # else
173 #  define	OPTIONS	"8KLdel:nw"
174 # endif
175 
176 #endif /* IN_RCMD */
177 
178 	if (!(pw = getpwuid(uid = getuid())))
179 		errx(1, "unknown user id");
180 
181 	if ((name = strdup(pw->pw_name)) == NULL)
182 		err(1, "malloc");
183 	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
184 		switch(ch) {
185 		case 'K':
186 #ifdef KERBEROS
187 			use_kerberos = 0;
188 #endif
189 			break;
190 		case 'L':	/* -8Lew are ignored to allow rlogin aliases */
191 		case 'e':
192 		case 'w':
193 		case '8':
194 			break;
195 		case 'd':
196 			dflag = 1;
197 			break;
198 		case 'l':
199 			user = optarg;
200 			break;
201 #ifdef KERBEROS
202 		case 'k':
203 			dest_realm = dst_realm_buf;
204 			strncpy(dest_realm, optarg, REALM_SZ);
205 			break;
206 #endif
207 		case 'n':
208 			nflag = 1;
209 			break;
210 #ifdef IN_RCMD
211 		case 'u':
212 			if (getuid() != 0 && optarg && name &&
213 			    strcmp(name, optarg) != 0)
214 				errx(1,"only super user can use the -u option");
215 			locuser = optarg;
216 			break;
217 #endif /* IN_RCMD */
218 #ifdef KERBEROS
219 #ifdef CRYPT
220 		case 'x':
221 			doencrypt = 1;
222 			des_set_key((des_cblock *) cred.session, schedule);
223 			break;
224 #endif
225 #endif
226 		case '?':
227 		default:
228 			usage();
229 		}
230 	optind += argoff;
231 
232 	/* if haven't gotten a host yet, do so */
233 	if (!host && !(host = argv[optind++]))
234 		usage();
235 
236 	/* if no further arguments, must have been called as rlogin. */
237 	if (!argv[optind]) {
238 #ifdef IN_RCMD
239 		usage();
240 #else
241 		if (asrsh)
242 			*argv = "rlogin";
243 		execv(_PATH_RLOGIN, argv);
244 		err(1, "can't exec %s", _PATH_RLOGIN);
245 #endif
246 	}
247 
248 	argc -= optind;
249 	argv += optind;
250 
251 	/* Accept user1@host format, though "-l user2" overrides user1 */
252 	p = strchr(host, '@');
253 	if (p) {
254 		*p = '\0';
255 		if (!user && p > host)
256 			user = host;
257 		host = p + 1;
258 		if (*host == '\0')
259 			usage();
260 	}
261 	if (!user)
262 		user = name;
263 
264 #ifdef KERBEROS
265 #ifdef CRYPT
266 	/* -x turns off -n */
267 	if (doencrypt)
268 		nflag = 0;
269 #endif
270 #endif
271 
272 	args = copyargs(argv);
273 
274 	sp = NULL;
275 #ifdef KERBEROS
276 	if (use_kerberos) {
277 		sp = getservbyname((doencrypt ? "ekshell" : "kshell"), "tcp");
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 
362 	(void) setuid(uid);
363 
364 	(void) sigemptyset(&nset);
365 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++)
366 		(void) sigaddset(&nset, sigs[i]);
367 
368 	(void) sigprocmask(SIG_BLOCK, &nset, &oset);
369 
370 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++) {
371 		struct sigaction sa;
372 
373 		if (sa.sa_handler != SIG_IGN) {
374 			sa.sa_handler = sendsig;
375 			(void) sigaction(sigs[i], &sa, NULL);
376 		}
377 	}
378 
379 	if (!nflag) {
380 		pid = fork();
381 		if (pid < 0)
382 			err(1, "fork");
383 	}
384 	else
385 		pid = -1;
386 
387 #if defined(KERBEROS) && defined(CRYPT)
388 	if (!doencrypt)
389 #endif
390 	{
391 		(void)ioctl(remerr, FIONBIO, &one);
392 		(void)ioctl(rem, FIONBIO, &one);
393 	}
394 
395 	talk(nflag, &oset, pid, rem);
396 
397 	if (!nflag)
398 		(void)kill(pid, SIGKILL);
399 	exit(0);
400 }
401 
402 int
403 checkfd(fdp, outfd)
404 	struct pollfd *fdp;
405 	int outfd;
406 {
407 	int nr, nw;
408 	char buf[BUFSIZ];
409 
410 	if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
411 		return -1;
412 
413 	if ((fdp->revents & POLLIN) == 0)
414 		return 0;
415 
416 	errno = 0;
417 #if defined(KERBEROS) && defined(CRYPT)
418 	if (doencrypt)
419 		nr = des_read(fdp->fd, buf, sizeof buf);
420 	else
421 #endif
422 		nr = read(fdp->fd, buf, sizeof buf);
423 
424 	if (nr <= 0) {
425 		if (errno != EAGAIN)
426 			return -1;
427 		else
428 			return 0;
429 	}
430 	else {
431 		char *bc = buf;
432 		while (nr) {
433 			if ((nw = write(outfd, bc, nr)) <= 0)
434 				return -1;
435 			nr -= nw;
436 			bc += nw;
437 		}
438 		return 0;
439 	}
440 }
441 
442 void
443 talk(nflag, oset, pid, rem)
444 	int nflag;
445 	sigset_t *oset;
446 	pid_t pid;
447 	int rem;
448 {
449 	int nr, nw, nfds;
450 	struct pollfd fds[2], *fdp = &fds[0];
451 	char *bp, buf[BUFSIZ];
452 
453 
454 	if (!nflag && pid == 0) {
455 		(void)close(remerr);
456 
457 		fdp->events = POLLOUT|POLLNVAL|POLLERR|POLLHUP;
458 		fdp->fd = rem;
459 		nr = 0;
460 		bp = buf;
461 
462 		for (;;) {
463 			errno = 0;
464 
465 			if (nr == 0) {
466 				if ((nr = read(0, buf, sizeof buf)) == 0)
467 					goto done;
468 				if (nr == -1) {
469 					if (errno == EIO)
470 						goto done;
471 					if (errno == EINTR)
472 						continue;
473 					err(1, "read");
474 				}
475 				bp = buf;
476 			}
477 
478 rewrite:		if (poll(fdp, 1, INFTIM) == -1) {
479 				if (errno != EINTR)
480 					err(1, "poll");
481 				goto rewrite;
482 			}
483 
484 			if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
485 				err(1, "poll");
486 
487 			if ((fdp->revents & POLLOUT) == 0)
488 				goto rewrite;
489 
490 #if defined(KERBEROS) && defined(CRYPT)
491 			if (doencrypt)
492 				nw = des_write(rem, bp, nr);
493 			else
494 #endif
495 				nw = write(rem, bp, nr);
496 
497 			if (nw < 0) {
498 				if (errno == EAGAIN)
499 					continue;
500 				err(1, "write");
501 			}
502 			bp += nw;
503 			nr -= nw;
504 		}
505 done:
506 		(void)shutdown(rem, 1);
507 		exit(0);
508 	}
509 
510 	(void) sigprocmask(SIG_SETMASK, oset, NULL);
511 	fds[0].events = fds[1].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
512 	fds[0].fd = remerr;
513 	fds[1].fd = rem;
514 	fdp = &fds[0];
515 	nfds = 2;
516 	do {
517 		if (poll(fdp, nfds, INFTIM) == -1) {
518 			if (errno != EINTR)
519 				err(1, "poll");
520 			continue;
521 		}
522 		if (fds[0].events != 0 && checkfd(&fds[0], 2) == -1) {
523 			nfds--;
524 			fds[0].events = 0;
525 			fdp = &fds[1];
526 		}
527 		if (fds[1].events != 0 && checkfd(&fds[1], 1) == -1) {
528 			nfds--;
529 			fds[1].events = 0;
530 		}
531 	}
532 	while (nfds);
533 }
534 
535 void
536 sendsig(sig)
537 	int sig;
538 {
539 	char signo;
540 
541 	signo = sig;
542 #ifdef KERBEROS
543 #ifdef CRYPT
544 	if (doencrypt)
545 		(void)des_write(remerr, &signo, 1);
546 	else
547 #endif
548 #endif
549 		(void)write(remerr, &signo, 1);
550 }
551 
552 #ifdef KERBEROS
553 /* VARARGS */
554 void
555 #ifdef __STDC__
556 warning(const char *fmt, ...)
557 #else
558 warning(va_alist)
559 	va_dcl
560 #endif
561 {
562 	va_list ap;
563 #ifndef __STDC__
564 	const char *fmt;
565 
566 	va_start(ap);
567 	fmt = va_arg(ap, const char *);
568 #else
569 	va_start(ap, fmt);
570 #endif
571 
572 	(void) fprintf(stderr, "%s: warning, using standard rsh: ",
573 	    getprogname());
574 	(void) vfprintf(stderr, fmt, ap);
575 	va_end(ap);
576 	(void) fprintf(stderr, ".\n");
577 }
578 #endif
579 
580 char *
581 copyargs(argv)
582 	char **argv;
583 {
584 	int cc;
585 	char **ap, *args, *p;
586 
587 	cc = 0;
588 	for (ap = argv; *ap; ++ap)
589 		cc += strlen(*ap) + 1;
590 	if (!(args = malloc((u_int)cc)))
591 		err(1, "malloc");
592 	for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
593 		(void)strcpy(p, *ap);
594 		p += strlen(p);
595 		if (ap[1])
596 			*p++ = ' ';
597 	}
598 	*p = '\0';
599 	return (args);
600 }
601 
602 void
603 usage()
604 {
605 
606 	(void)fprintf(stderr,
607 	    "usage: %s [-nd%s]%s[-l login]%s [login@]host %s\n", getprogname(),
608 #ifdef KERBEROS
609 #ifdef CRYPT
610 	    "x", " [-k realm] ",
611 #else
612 	    "", " [-k realm] ",
613 #endif
614 #else
615 	    "", " ",
616 #endif
617 #ifdef IN_RCMD
618 	    " [-u locuser]", "command"
619 #else
620 	    "", "[command]"
621 #endif
622 	    );
623 	exit(1);
624 }
625