rsh.c revision 27954 
1/*-
2 * Copyright (c) 1983, 1990, 1993, 1994
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#ifndef lint
35static const char copyright[] =
36"@(#) Copyright (c) 1983, 1990, 1993, 1994\n\
37	The Regents of the University of California.  All rights reserved.\n";
38#endif /* not lint */
39
40#ifndef lint
41#if 0
42static char sccsid[] = "From: @(#)rsh.c	8.3 (Berkeley) 4/6/94";
43#endif
44static char rcsid[] =
45	"$Id: rsh.c,v 1.11 1997/03/29 04:31:59 imp Exp $";
46#endif /* not lint */
47
48#include <sys/types.h>
49#include <sys/signal.h>
50#include <sys/socket.h>
51#include <sys/ioctl.h>
52#include <sys/file.h>
53#include <sys/time.h>
54
55#include <netinet/in.h>
56#include <netdb.h>
57
58#include <err.h>
59#include <errno.h>
60#include <pwd.h>
61#include <signal.h>
62#include <stdio.h>
63#include <stdlib.h>
64#include <string.h>
65#include <unistd.h>
66#include <varargs.h>
67
68#include "pathnames.h"
69
70#ifdef KERBEROS
71#include <des.h>
72#include <kerberosIV/krb.h>
73
74CREDENTIALS cred;
75Key_schedule schedule;
76int use_kerberos = 1, doencrypt;
77char dst_realm_buf[REALM_SZ], *dest_realm;
78extern char *krb_realmofhost();
79#endif
80
81/*
82 * rsh - remote shell
83 */
84int	rfd2;
85
86char   *copyargs __P((char **));
87void	sendsig __P((int));
88void	talk __P((int, long, pid_t, int, int));
89void	usage __P((void));
90
91int
92main(argc, argv)
93	int argc;
94	char **argv;
95{
96	struct passwd *pw;
97	struct servent *sp;
98	long omask;
99	int argoff, asrsh, ch, dflag, nflag, one, rem;
100	pid_t pid;
101	uid_t uid;
102	char *args, *host, *p, *user;
103	int timeout = 0;
104
105	argoff = asrsh = dflag = nflag = 0;
106	one = 1;
107	host = user = NULL;
108
109	/* if called as something other than "rsh", use it as the host name */
110	if (p = strrchr(argv[0], '/'))
111		++p;
112	else
113		p = argv[0];
114	if (strcmp(p, "rsh"))
115		host = p;
116	else
117		asrsh = 1;
118
119	/* handle "rsh host flags" */
120	if (!host && argc > 2 && argv[1][0] != '-') {
121		host = argv[1];
122		argoff = 1;
123	}
124
125#ifdef KERBEROS
126#ifdef CRYPT
127#define	OPTIONS	"8KLde:k:l:nt:wx"
128#else
129#define	OPTIONS	"8KLde:k:l:nt:w"
130#endif
131#else
132#define	OPTIONS	"8KLde:l:nt:w"
133#endif
134	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
135		switch(ch) {
136		case 'K':
137#ifdef KERBEROS
138			use_kerberos = 0;
139#endif
140			break;
141		case 'L':	/* -8Lew are ignored to allow rlogin aliases */
142		case 'e':
143		case 'w':
144		case '8':
145			break;
146		case 'd':
147			dflag = 1;
148			break;
149		case 'l':
150			user = optarg;
151			break;
152#ifdef KERBEROS
153		case 'k':
154			dest_realm = dst_realm_buf;
155			strncpy(dest_realm, optarg, REALM_SZ);
156			break;
157#endif
158		case 'n':
159			nflag = 1;
160			break;
161#ifdef KERBEROS
162#ifdef CRYPT
163		case 'x':
164			doencrypt = 1;
165			break;
166#endif
167#endif
168		case 't':
169			timeout = atoi(optarg);
170			break;
171		case '?':
172		default:
173			usage();
174		}
175	optind += argoff;
176
177	/* if haven't gotten a host yet, do so */
178	if (!host && !(host = argv[optind++]))
179		usage();
180
181	/* if no further arguments, must have been called as rlogin. */
182	if (!argv[optind]) {
183		if (asrsh)
184			*argv = "rlogin";
185		execv(_PATH_RLOGIN, argv);
186		err(1, "can't exec %s", _PATH_RLOGIN);
187	}
188
189	argc -= optind;
190	argv += optind;
191
192	if (!(pw = getpwuid(uid = getuid())))
193		errx(1, "unknown user id");
194	if (!user)
195		user = pw->pw_name;
196
197#ifdef KERBEROS
198#ifdef CRYPT
199	/* -x turns off -n */
200	if (doencrypt)
201		nflag = 0;
202#endif
203#endif
204
205	args = copyargs(argv);
206
207	sp = NULL;
208#ifdef KERBEROS
209	if (use_kerberos) {
210		sp = getservbyname((doencrypt ? "ekshell" : "kshell"), "tcp");
211		if (sp == NULL) {
212			use_kerberos = 0;
213			warnx(
214	"warning, using standard rsh: can't get entry for %s/tcp service",
215			    doencrypt ? "ekshell" : "kshell");
216		}
217	}
218#endif
219	if (sp == NULL)
220		sp = getservbyname("shell", "tcp");
221	if (sp == NULL)
222		errx(1, "shell/tcp: unknown service");
223
224#ifdef KERBEROS
225try_connect:
226	if (use_kerberos) {
227		struct hostent *hp;
228
229		/* fully qualify hostname (needed for krb_realmofhost) */
230		hp = gethostbyname(host);
231		if (hp != NULL && !(host = strdup(hp->h_name)))
232			err(1, NULL);
233
234		rem = KSUCCESS;
235		errno = 0;
236		if (dest_realm == NULL)
237			dest_realm = krb_realmofhost(host);
238
239#ifdef CRYPT
240		if (doencrypt) {
241			rem = krcmd_mutual(&host, sp->s_port, user, args,
242			    &rfd2, dest_realm, &cred, schedule);
243			des_set_key_krb(&cred.session, schedule);
244		} else
245#endif
246			rem = krcmd(&host, sp->s_port, user, args, &rfd2,
247			    dest_realm);
248		if (rem < 0) {
249			use_kerberos = 0;
250			sp = getservbyname("shell", "tcp");
251			if (sp == NULL)
252				errx(1, "shell/tcp: unknown service");
253			if (errno == ECONNREFUSED)
254				warnx(
255		"warning, using standard rsh: remote host doesn't support Kerberos");
256			if (errno == ENOENT)
257				warnx(
258		"warning, using standard rsh: can't provide Kerberos auth data");
259			goto try_connect;
260		}
261	} else {
262		if (doencrypt)
263			errx(1, "the -x flag requires Kerberos authentication");
264		rem = rcmd(&host, sp->s_port, pw->pw_name, user, args, &rfd2);
265	}
266#else
267	rem = rcmd(&host, sp->s_port, pw->pw_name, user, args, &rfd2);
268#endif
269
270	if (rem < 0)
271		exit(1);
272
273	if (rfd2 < 0)
274		errx(1, "can't establish stderr");
275	if (dflag) {
276		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
277		    sizeof(one)) < 0)
278			warn("setsockopt");
279		if (setsockopt(rfd2, SOL_SOCKET, SO_DEBUG, &one,
280		    sizeof(one)) < 0)
281			warn("setsockopt");
282	}
283
284	(void)setuid(uid);
285	omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGTERM));
286	if (signal(SIGINT, SIG_IGN) != SIG_IGN)
287		(void)signal(SIGINT, sendsig);
288	if (signal(SIGQUIT, SIG_IGN) != SIG_IGN)
289		(void)signal(SIGQUIT, sendsig);
290	if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
291		(void)signal(SIGTERM, sendsig);
292
293	if (!nflag) {
294		pid = fork();
295		if (pid < 0)
296			err(1, "fork");
297	}
298
299#ifdef KERBEROS
300#ifdef CRYPT
301	if (!doencrypt)
302#endif
303#endif
304	{
305		(void)ioctl(rfd2, FIONBIO, &one);
306		(void)ioctl(rem, FIONBIO, &one);
307	}
308
309	talk(nflag, omask, pid, rem, timeout);
310
311	if (!nflag)
312		(void)kill(pid, SIGKILL);
313	exit(0);
314}
315
316void
317talk(nflag, omask, pid, rem, timeout)
318	int nflag;
319	long omask;
320	pid_t pid;
321	int rem;
322{
323	int cc, wc;
324	fd_set readfrom, ready, rembits;
325	char *bp, buf[BUFSIZ];
326	struct timeval tvtimeout;
327	int srval;
328
329	if (!nflag && pid == 0) {
330		(void)close(rfd2);
331
332reread:		errno = 0;
333		if ((cc = read(0, buf, sizeof buf)) <= 0)
334			goto done;
335		bp = buf;
336
337rewrite:
338		FD_ZERO(&rembits);
339		FD_SET(rem, &rembits);
340		if (select(16, 0, &rembits, 0, 0) < 0) {
341			if (errno != EINTR)
342				err(1, "select");
343			goto rewrite;
344		}
345		if (!FD_ISSET(rem, &rembits))
346			goto rewrite;
347#ifdef KERBEROS
348#ifdef CRYPT
349		if (doencrypt)
350			wc = des_write(rem, bp, cc);
351		else
352#endif
353#endif
354			wc = write(rem, bp, cc);
355		if (wc < 0) {
356			if (errno == EWOULDBLOCK)
357				goto rewrite;
358			goto done;
359		}
360		bp += wc;
361		cc -= wc;
362		if (cc == 0)
363			goto reread;
364		goto rewrite;
365done:
366		(void)shutdown(rem, 1);
367		exit(0);
368	}
369
370	tvtimeout.tv_sec = timeout;
371	tvtimeout.tv_usec = 0;
372
373	(void)sigsetmask(omask);
374	FD_ZERO(&readfrom);
375	FD_SET(rfd2, &readfrom);
376	FD_SET(rem, &readfrom);
377	do {
378		ready = readfrom;
379		if (timeout) {
380			srval = select(16, &ready, 0, 0, &tvtimeout);
381		} else {
382			srval = select(16, &ready, 0, 0, 0);
383		}
384
385		if (srval < 0) {
386			if (errno != EINTR)
387				err(1, "select");
388			continue;
389		}
390		if (srval == 0)
391			errx(1, "timeout reached (%d seconds)\n", timeout);
392		if (FD_ISSET(rfd2, &ready)) {
393			errno = 0;
394#ifdef KERBEROS
395#ifdef CRYPT
396			if (doencrypt)
397				cc = des_read(rfd2, buf, sizeof buf);
398			else
399#endif
400#endif
401				cc = read(rfd2, buf, sizeof buf);
402			if (cc <= 0) {
403				if (errno != EWOULDBLOCK)
404					FD_CLR(rfd2, &readfrom);
405			} else
406				(void)write(2, buf, cc);
407		}
408		if (FD_ISSET(rem, &ready)) {
409			errno = 0;
410#ifdef KERBEROS
411#ifdef CRYPT
412			if (doencrypt)
413				cc = des_read(rem, buf, sizeof buf);
414			else
415#endif
416#endif
417				cc = read(rem, buf, sizeof buf);
418			if (cc <= 0) {
419				if (errno != EWOULDBLOCK)
420					FD_CLR(rem, &readfrom);
421			} else
422				(void)write(1, buf, cc);
423		}
424	} while (FD_ISSET(rfd2, &readfrom) || FD_ISSET(rem, &readfrom));
425}
426
427void
428sendsig(sig)
429	int sig;
430{
431	char signo;
432
433	signo = sig;
434#ifdef KERBEROS
435#ifdef CRYPT
436	if (doencrypt)
437		(void)des_write(rfd2, &signo, 1);
438	else
439#endif
440#endif
441		(void)write(rfd2, &signo, 1);
442}
443
444char *
445copyargs(argv)
446	char **argv;
447{
448	int cc;
449	char **ap, *args, *p;
450
451	cc = 0;
452	for (ap = argv; *ap; ++ap)
453		cc += strlen(*ap) + 1;
454	if (!(args = malloc((u_int)cc)))
455		err(1, NULL);
456	for (p = args, ap = argv; *ap; ++ap) {
457		(void)strcpy(p, *ap);
458		for (p = strcpy(p, *ap); *p; ++p);
459		if (ap[1])
460			*p++ = ' ';
461	}
462	return (args);
463}
464
465void
466usage()
467{
468
469	(void)fprintf(stderr,
470	    "usage: rsh [-nd%s]%s[-l login] [-t timeout] host [command]\n",
471#ifdef KERBEROS
472#ifdef CRYPT
473	    "x", " [-k realm] ");
474#else
475	    "", " [-k realm] ");
476#endif
477#else
478	    "", " ");
479#endif
480	exit(1);
481}
482
483