xref: /netbsd/usr.bin/rsh/rsh.c (revision c4a72b64) 
1 /*	$NetBSD: rsh.c,v 1.16 2002/11/16 13:47:34 itojun 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 1.16 2002/11/16 13:47:34 itojun 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 <stdarg.h>
64 #include <stdio.h>
65 #include <stdlib.h>
66 #include <string.h>
67 #include <unistd.h>
68 
69 #include "pathnames.h"
70 
71 #ifdef KERBEROS
72 #include <kerberosIV/des.h>
73 #include <kerberosIV/krb.h>
74 
75 CREDENTIALS cred;
76 Key_schedule schedule;
77 int use_kerberos = 1, doencrypt;
78 char dst_realm_buf[REALM_SZ], *dest_realm;
79 
80 void	warning(const char *, ...);
81 #endif
82 
83 /*
84  * rsh - remote shell
85  */
86 int	remerr;
87 
88 static int sigs[] = { SIGINT, SIGTERM, SIGQUIT };
89 
90 char   *copyargs(char **);
91 void	sendsig(int);
92 int	checkfd(struct pollfd *, int);
93 void	talk(int, sigset_t *, pid_t, int);
94 void	usage(void);
95 int	main(int, char **);
96 #ifdef IN_RCMD
97 int	 orcmd(char **, int, const char *,
98     const char *, const char *, int *);
99 int	 orcmd_af(char **, int, const char *,
100     const char *, const char *, int *, int);
101 #endif
102 
103 int
104 main(int argc, char **argv)
105 {
106 	struct passwd *pw;
107 	struct servent *sp;
108 	sigset_t oset, nset;
109 
110 #ifdef IN_RCMD
111 	char	*locuser = 0, *loop;
112 #endif /* IN_RCMD */
113 	int argoff, asrsh, ch, dflag, nflag, one, rem, i;
114 	pid_t pid;
115 	uid_t uid;
116 	char *args, *host, *p, *user, *name;
117 
118 	argoff = asrsh = dflag = nflag = 0;
119 	one = 1;
120 	host = user = 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:nu:wx"
151 #  else
152 #   define	OPTIONS	"8KLdek:l:nu:w"
153 #  endif
154 # else
155 #  define	OPTIONS	"8KLdel:nu:w"
156 # endif
157 
158 #else /* IN_RCMD */
159 
160 # ifdef KERBEROS
161 #  ifdef CRYPT
162 #   define	OPTIONS	"8KLdek:l:nwx"
163 #  else
164 #   define	OPTIONS	"8KLdek:l:nw"
165 #  endif
166 # else
167 #  define	OPTIONS	"8KLdel:nw"
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 #ifdef IN_RCMD
205 		case 'u':
206 			if (getuid() != 0 && optarg && name &&
207 			    strcmp(name, optarg) != 0)
208 				errx(1,"only super user can use the -u option");
209 			locuser = optarg;
210 			break;
211 #endif /* IN_RCMD */
212 #ifdef KERBEROS
213 #ifdef CRYPT
214 		case 'x':
215 			doencrypt = 1;
216 			des_set_key((des_cblock *) cred.session, schedule);
217 			break;
218 #endif
219 #endif
220 		case '?':
221 		default:
222 			usage();
223 		}
224 	optind += argoff;
225 
226 	/* if haven't gotten a host yet, do so */
227 	if (!host && !(host = argv[optind++]))
228 		usage();
229 
230 	/* if no further arguments, must have been called as rlogin. */
231 	if (!argv[optind]) {
232 #ifdef IN_RCMD
233 		usage();
234 #else
235 		if (asrsh)
236 			*argv = "rlogin";
237 		execv(_PATH_RLOGIN, argv);
238 		err(1, "can't exec %s", _PATH_RLOGIN);
239 #endif
240 	}
241 
242 	argc -= optind;
243 	argv += optind;
244 
245 	/* Accept user1@host format, though "-l user2" overrides user1 */
246 	p = strchr(host, '@');
247 	if (p) {
248 		*p = '\0';
249 		if (!user && p > host)
250 			user = host;
251 		host = p + 1;
252 		if (*host == '\0')
253 			usage();
254 	}
255 	if (!user)
256 		user = name;
257 
258 #ifdef KERBEROS
259 #ifdef CRYPT
260 	/* -x turns off -n */
261 	if (doencrypt)
262 		nflag = 0;
263 #endif
264 #endif
265 
266 	args = copyargs(argv);
267 
268 	sp = NULL;
269 #ifdef KERBEROS
270 	if (use_kerberos) {
271 		sp = getservbyname((doencrypt ? "ekshell" : "kshell"), "tcp");
272 		if (sp == NULL) {
273 			use_kerberos = 0;
274 			warning("can't get entry for %s/tcp service",
275 			    doencrypt ? "ekshell" : "kshell");
276 		}
277 	}
278 #endif
279 	if (sp == NULL)
280 		sp = getservbyname("shell", "tcp");
281 	if (sp == NULL)
282 		errx(1, "shell/tcp: unknown service");
283 
284 #ifdef KERBEROS
285 try_connect:
286 	if (use_kerberos) {
287 #if 1
288 		struct hostent *hp;
289 
290 		/* fully qualify hostname (needed for krb_realmofhost) */
291 		hp = gethostbyname(host);
292 		if (hp != NULL && !(host = strdup(hp->h_name)))
293 			err(1, "strdup");
294 #endif
295 
296 		rem = KSUCCESS;
297 		errno = 0;
298 		if (dest_realm == NULL)
299 			dest_realm = krb_realmofhost(host);
300 
301 #ifdef CRYPT
302 		if (doencrypt)
303 			rem = krcmd_mutual(&host, sp->s_port, user, args,
304 			    &remerr, dest_realm, &cred, schedule);
305 		else
306 #endif
307 			rem = krcmd(&host, sp->s_port, user, args, &remerr,
308 			    dest_realm);
309 		if (rem < 0) {
310 			use_kerberos = 0;
311 			sp = getservbyname("shell", "tcp");
312 			if (sp == NULL)
313 				errx(1, "shell/tcp: unknown service");
314 			if (errno == ECONNREFUSED)
315 				warning("remote host doesn't support Kerberos");
316 			if (errno == ENOENT)
317 				warning("can't provide Kerberos auth data");
318 			goto try_connect;
319 		}
320 	} else {
321 		if (doencrypt)
322 			errx(1, "the -x flag requires Kerberos authentication.");
323 #ifdef IN_RCMD
324 		rem = orcmd_af(&host, sp->s_port, locuser ? locuser :
325 #else
326 		rem = rcmd_af(&host, sp->s_port,
327 #endif
328 		    name,
329 		    user, args, &remerr, PF_UNSPEC);
330 	}
331 #else /* KERBEROS */
332 
333 #ifdef IN_RCMD
334 	rem = orcmd_af(&host, sp->s_port, locuser ? locuser :
335 #else
336 	rem = rcmd_af(&host, sp->s_port,
337 #endif
338 	    name, user, args, &remerr, PF_UNSPEC);
339 #endif /* KERBEROS */
340 	(void)free(name);
341 
342 	if (rem < 0)
343 		exit(1);
344 
345 	if (remerr < 0)
346 		errx(1, "can't establish stderr");
347 	if (dflag) {
348 		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
349 		    sizeof(one)) < 0)
350 			warn("setsockopt remote");
351 		if (setsockopt(remerr, SOL_SOCKET, SO_DEBUG, &one,
352 		    sizeof(one)) < 0)
353 			warn("setsockopt stderr");
354 	}
355 
356 	(void) setuid(uid);
357 
358 	(void) sigemptyset(&nset);
359 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++)
360 		(void) sigaddset(&nset, sigs[i]);
361 
362 	(void) sigprocmask(SIG_BLOCK, &nset, &oset);
363 
364 	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++) {
365 		struct sigaction sa;
366 
367 		if (sa.sa_handler != SIG_IGN) {
368 			sa.sa_handler = sendsig;
369 			(void) sigaction(sigs[i], &sa, NULL);
370 		}
371 	}
372 
373 	if (!nflag) {
374 		pid = fork();
375 		if (pid < 0)
376 			err(1, "fork");
377 	}
378 	else
379 		pid = -1;
380 
381 #if defined(KERBEROS) && defined(CRYPT)
382 	if (!doencrypt)
383 #endif
384 	{
385 		(void)ioctl(remerr, FIONBIO, &one);
386 		(void)ioctl(rem, FIONBIO, &one);
387 	}
388 
389 	talk(nflag, &oset, pid, rem);
390 
391 	if (!nflag)
392 		(void)kill(pid, SIGKILL);
393 	exit(0);
394 }
395 
396 int
397 checkfd(struct pollfd *fdp, int outfd)
398 {
399 	int nr, nw;
400 	char buf[BUFSIZ];
401 
402 	if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
403 		return -1;
404 
405 	if ((fdp->revents & POLLIN) == 0)
406 		return 0;
407 
408 	errno = 0;
409 #if defined(KERBEROS) && defined(CRYPT)
410 	if (doencrypt)
411 		nr = des_read(fdp->fd, buf, sizeof buf);
412 	else
413 #endif
414 		nr = read(fdp->fd, buf, sizeof buf);
415 
416 	if (nr <= 0) {
417 		if (errno != EAGAIN)
418 			return -1;
419 		else
420 			return 0;
421 	}
422 	else {
423 		char *bc = buf;
424 		while (nr) {
425 			if ((nw = write(outfd, bc, nr)) <= 0)
426 				return -1;
427 			nr -= nw;
428 			bc += nw;
429 		}
430 		return 0;
431 	}
432 }
433 
434 void
435 talk(int nflag, sigset_t *oset, __pid_t pid, int rem)
436 {
437 	int nr, nw, nfds;
438 	struct pollfd fds[2], *fdp = &fds[0];
439 	char *bp, buf[BUFSIZ];
440 
441 
442 	if (!nflag && pid == 0) {
443 		(void)close(remerr);
444 
445 		fdp->events = POLLOUT|POLLNVAL|POLLERR|POLLHUP;
446 		fdp->fd = rem;
447 		nr = 0;
448 		bp = buf;
449 
450 		for (;;) {
451 			errno = 0;
452 
453 			if (nr == 0) {
454 				if ((nr = read(0, buf, sizeof buf)) == 0)
455 					goto done;
456 				if (nr == -1) {
457 					if (errno == EIO)
458 						goto done;
459 					if (errno == EINTR)
460 						continue;
461 					err(1, "read");
462 				}
463 				bp = buf;
464 			}
465 
466 rewrite:		if (poll(fdp, 1, INFTIM) == -1) {
467 				if (errno != EINTR)
468 					err(1, "poll");
469 				goto rewrite;
470 			}
471 
472 			if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
473 				err(1, "poll");
474 
475 			if ((fdp->revents & POLLOUT) == 0)
476 				goto rewrite;
477 
478 #if defined(KERBEROS) && defined(CRYPT)
479 			if (doencrypt)
480 				nw = des_write(rem, bp, nr);
481 			else
482 #endif
483 				nw = write(rem, bp, nr);
484 
485 			if (nw < 0) {
486 				if (errno == EAGAIN)
487 					continue;
488 				err(1, "write");
489 			}
490 			bp += nw;
491 			nr -= nw;
492 		}
493 done:
494 		(void)shutdown(rem, 1);
495 		exit(0);
496 	}
497 
498 	(void) sigprocmask(SIG_SETMASK, oset, NULL);
499 	fds[0].events = fds[1].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
500 	fds[0].fd = remerr;
501 	fds[1].fd = rem;
502 	fdp = &fds[0];
503 	nfds = 2;
504 	do {
505 		if (poll(fdp, nfds, INFTIM) == -1) {
506 			if (errno != EINTR)
507 				err(1, "poll");
508 			continue;
509 		}
510 		if (fds[0].events != 0 && checkfd(&fds[0], 2) == -1) {
511 			nfds--;
512 			fds[0].events = 0;
513 			fdp = &fds[1];
514 		}
515 		if (fds[1].events != 0 && checkfd(&fds[1], 1) == -1) {
516 			nfds--;
517 			fds[1].events = 0;
518 		}
519 	}
520 	while (nfds);
521 }
522 
523 void
524 sendsig(int sig)
525 {
526 	char signo;
527 
528 	signo = sig;
529 #ifdef KERBEROS
530 #ifdef CRYPT
531 	if (doencrypt)
532 		(void)des_write(remerr, &signo, 1);
533 	else
534 #endif
535 #endif
536 		(void)write(remerr, &signo, 1);
537 }
538 
539 #ifdef KERBEROS
540 /* VARARGS */
541 void
542 warning(const char *fmt, ...)
543 {
544 	va_list ap;
545 
546 	va_start(ap, fmt);
547 	(void) fprintf(stderr, "%s: warning, using standard rsh: ",
548 	    getprogname());
549 	(void) vfprintf(stderr, fmt, ap);
550 	va_end(ap);
551 	(void) fprintf(stderr, ".\n");
552 }
553 #endif
554 
555 char *
556 copyargs(char **argv)
557 {
558 	int cc;
559 	char **ap, *args, *p;
560 
561 	cc = 0;
562 	for (ap = argv; *ap; ++ap)
563 		cc += strlen(*ap) + 1;
564 	if (!(args = malloc((u_int)cc)))
565 		err(1, "malloc");
566 	for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
567 		(void)strcpy(p, *ap);
568 		p += strlen(p);
569 		if (ap[1])
570 			*p++ = ' ';
571 	}
572 	*p = '\0';
573 	return (args);
574 }
575 
576 void
577 usage(void)
578 {
579 
580 	(void)fprintf(stderr,
581 	    "usage: %s [-nd%s]%s[-l login]%s [login@]host %s\n", getprogname(),
582 #ifdef KERBEROS
583 #ifdef CRYPT
584 	    "x", " [-k realm] ",
585 #else
586 	    "", " [-k realm] ",
587 #endif
588 #else
589 	    "", " ",
590 #endif
591 #ifdef IN_RCMD
592 	    " [-u locuser]", "command"
593 #else
594 	    "", "[command]"
595 #endif
596 	    );
597 	exit(1);
598 }
599