rsh.c revision 1591 
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 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
41static char sccsid[] = "@(#)rsh.c	8.3 (Berkeley) 4/6/94";
42#endif /* not lint */
43
44/*
45 * $Source: mit/rsh/RCS/rsh.c,v $
46 * $Header: mit/rsh/RCS/rsh.c,v 5.1 89/07/31 19:28:59 kfall Exp Locker: kfall $
47 */
48
49#include <sys/types.h>
50#include <sys/signal.h>
51#include <sys/socket.h>
52#include <sys/ioctl.h>
53#include <sys/file.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 <kerberosIV/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));
89void	usage __P((void));
90void	warning __P(());
91
92int
93main(argc, argv)
94	int argc;
95	char **argv;
96{
97	struct passwd *pw;
98	struct servent *sp;
99	long omask;
100	int argoff, asrsh, ch, dflag, nflag, one, rem;
101	pid_t pid;
102	uid_t uid;
103	char *args, *host, *p, *user;
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	"8KLdek:l:nwx"
128#else
129#define	OPTIONS	"8KLdek:l:nw"
130#endif
131#else
132#define	OPTIONS	"8KLdel:nw"
133#endif
134	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != EOF)
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			des_set_key(cred.session, schedule);
166			break;
167#endif
168#endif
169		case '?':
170		default:
171			usage();
172		}
173	optind += argoff;
174
175	/* if haven't gotten a host yet, do so */
176	if (!host && !(host = argv[optind++]))
177		usage();
178
179	/* if no further arguments, must have been called as rlogin. */
180	if (!argv[optind]) {
181		if (asrsh)
182			*argv = "rlogin";
183		execv(_PATH_RLOGIN, argv);
184		err(1, "can't exec %s", _PATH_RLOGIN);
185	}
186
187	argc -= optind;
188	argv += optind;
189
190	if (!(pw = getpwuid(uid = getuid())))
191		errx(1, "unknown user id");
192	if (!user)
193		user = pw->pw_name;
194
195#ifdef KERBEROS
196#ifdef CRYPT
197	/* -x turns off -n */
198	if (doencrypt)
199		nflag = 0;
200#endif
201#endif
202
203	args = copyargs(argv);
204
205	sp = NULL;
206#ifdef KERBEROS
207	if (use_kerberos) {
208		sp = getservbyname((doencrypt ? "ekshell" : "kshell"), "tcp");
209		if (sp == NULL) {
210			use_kerberos = 0;
211			warning("can't get entry for %s/tcp service",
212			    doencrypt ? "ekshell" : "kshell");
213		}
214	}
215#endif
216	if (sp == NULL)
217		sp = getservbyname("shell", "tcp");
218	if (sp == NULL)
219		errx(1, "shell/tcp: unknown service");
220
221#ifdef KERBEROS
222try_connect:
223	if (use_kerberos) {
224		struct hostent *hp;
225
226		/* fully qualify hostname (needed for krb_realmofhost) */
227		hp = gethostbyname(host);
228		if (hp != NULL && !(host = strdup(hp->h_name)))
229			err(1, NULL);
230
231		rem = KSUCCESS;
232		errno = 0;
233		if (dest_realm == NULL)
234			dest_realm = krb_realmofhost(host);
235
236#ifdef CRYPT
237		if (doencrypt)
238			rem = krcmd_mutual(&host, sp->s_port, user, args,
239			    &rfd2, dest_realm, &cred, schedule);
240		else
241#endif
242			rem = krcmd(&host, sp->s_port, user, args, &rfd2,
243			    dest_realm);
244		if (rem < 0) {
245			use_kerberos = 0;
246			sp = getservbyname("shell", "tcp");
247			if (sp == NULL)
248				errx(1, "shell/tcp: unknown service");
249			if (errno == ECONNREFUSED)
250				warning("remote host doesn't support Kerberos");
251			if (errno == ENOENT)
252				warning("can't provide Kerberos auth data");
253			goto try_connect;
254		}
255	} else {
256		if (doencrypt)
257			errx(1, "the -x flag requires Kerberos authentication");
258		rem = rcmd(&host, sp->s_port, pw->pw_name, user, args, &rfd2);
259	}
260#else
261	rem = rcmd(&host, sp->s_port, pw->pw_name, user, args, &rfd2);
262#endif
263
264	if (rem < 0)
265		exit(1);
266
267	if (rfd2 < 0)
268		errx(1, "can't establish stderr");
269	if (dflag) {
270		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
271		    sizeof(one)) < 0)
272			warn("setsockopt");
273		if (setsockopt(rfd2, SOL_SOCKET, SO_DEBUG, &one,
274		    sizeof(one)) < 0)
275			warn("setsockopt");
276	}
277
278	(void)setuid(uid);
279	omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGTERM));
280	if (signal(SIGINT, SIG_IGN) != SIG_IGN)
281		(void)signal(SIGINT, sendsig);
282	if (signal(SIGQUIT, SIG_IGN) != SIG_IGN)
283		(void)signal(SIGQUIT, sendsig);
284	if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
285		(void)signal(SIGTERM, sendsig);
286
287	if (!nflag) {
288		pid = fork();
289		if (pid < 0)
290			err(1, "fork");
291	}
292
293#ifdef KERBEROS
294#ifdef CRYPT
295	if (!doencrypt)
296#endif
297#endif
298	{
299		(void)ioctl(rfd2, FIONBIO, &one);
300		(void)ioctl(rem, FIONBIO, &one);
301	}
302
303	talk(nflag, omask, pid, rem);
304
305	if (!nflag)
306		(void)kill(pid, SIGKILL);
307	exit(0);
308}
309
310void
311talk(nflag, omask, pid, rem)
312	int nflag;
313	long omask;
314	pid_t pid;
315	int rem;
316{
317	int cc, wc;
318	fd_set readfrom, ready, rembits;
319	char *bp, buf[BUFSIZ];
320
321	if (!nflag && pid == 0) {
322		(void)close(rfd2);
323
324reread:		errno = 0;
325		if ((cc = read(0, buf, sizeof buf)) <= 0)
326			goto done;
327		bp = buf;
328
329rewrite:
330		FD_ZERO(&rembits);
331		FD_SET(rem, &rembits);
332		if (select(16, 0, &rembits, 0, 0) < 0) {
333			if (errno != EINTR)
334				err(1, "select");
335			goto rewrite;
336		}
337		if (!FD_ISSET(rem, &rembits))
338			goto rewrite;
339#ifdef KERBEROS
340#ifdef CRYPT
341		if (doencrypt)
342			wc = des_write(rem, bp, cc);
343		else
344#endif
345#endif
346			wc = write(rem, bp, cc);
347		if (wc < 0) {
348			if (errno == EWOULDBLOCK)
349				goto rewrite;
350			goto done;
351		}
352		bp += wc;
353		cc -= wc;
354		if (cc == 0)
355			goto reread;
356		goto rewrite;
357done:
358		(void)shutdown(rem, 1);
359		exit(0);
360	}
361
362	(void)sigsetmask(omask);
363	FD_ZERO(&readfrom);
364	FD_SET(rfd2, &readfrom);
365	FD_SET(rem, &readfrom);
366	do {
367		ready = readfrom;
368		if (select(16, &ready, 0, 0, 0) < 0) {
369			if (errno != EINTR)
370				err(1, "select");
371			continue;
372		}
373		if (FD_ISSET(rfd2, &ready)) {
374			errno = 0;
375#ifdef KERBEROS
376#ifdef CRYPT
377			if (doencrypt)
378				cc = des_read(rfd2, buf, sizeof buf);
379			else
380#endif
381#endif
382				cc = read(rfd2, buf, sizeof buf);
383			if (cc <= 0) {
384				if (errno != EWOULDBLOCK)
385					FD_CLR(rfd2, &readfrom);
386			} else
387				(void)write(2, buf, cc);
388		}
389		if (FD_ISSET(rem, &ready)) {
390			errno = 0;
391#ifdef KERBEROS
392#ifdef CRYPT
393			if (doencrypt)
394				cc = des_read(rem, buf, sizeof buf);
395			else
396#endif
397#endif
398				cc = read(rem, buf, sizeof buf);
399			if (cc <= 0) {
400				if (errno != EWOULDBLOCK)
401					FD_CLR(rem, &readfrom);
402			} else
403				(void)write(1, buf, cc);
404		}
405	} while (FD_ISSET(rfd2, &readfrom) || FD_ISSET(rem, &readfrom));
406}
407
408void
409sendsig(sig)
410	int sig;
411{
412	char signo;
413
414	signo = sig;
415#ifdef KERBEROS
416#ifdef CRYPT
417	if (doencrypt)
418		(void)des_write(rfd2, &signo, 1);
419	else
420#endif
421#endif
422		(void)write(rfd2, &signo, 1);
423}
424
425#ifdef KERBEROS
426/* VARARGS */
427void
428warning(va_alist)
429va_dcl
430{
431	va_list ap;
432	char *fmt;
433
434	(void)fprintf(stderr, "rsh: warning, using standard rsh: ");
435	va_start(ap);
436	fmt = va_arg(ap, char *);
437	vfprintf(stderr, fmt, ap);
438	va_end(ap);
439	(void)fprintf(stderr, ".\n");
440}
441#endif
442
443char *
444copyargs(argv)
445	char **argv;
446{
447	int cc;
448	char **ap, *args, *p;
449
450	cc = 0;
451	for (ap = argv; *ap; ++ap)
452		cc += strlen(*ap) + 1;
453	if (!(args = malloc((u_int)cc)))
454		err(1, NULL);
455	for (p = args, ap = argv; *ap; ++ap) {
456		(void)strcpy(p, *ap);
457		for (p = strcpy(p, *ap); *p; ++p);
458		if (ap[1])
459			*p++ = ' ';
460	}
461	return (args);
462}
463
464void
465usage()
466{
467
468	(void)fprintf(stderr,
469	    "usage: rsh [-nd%s]%s[-l login] host [command]\n",
470#ifdef KERBEROS
471#ifdef CRYPT
472	    "x", " [-k realm] ");
473#else
474	    "", " [-k realm] ");
475#endif
476#else
477	    "", " ");
478#endif
479	exit(1);
480}
481