rsh.c revision 325474 
1/*-
2 * Copyright (c) 1983, 1990, 1993, 1994
3 *	The Regents of the University of California.  All rights reserved.
4 * Copyright (c) 2002 Networks Associates Technology, Inc.
5 * All rights reserved.
6 *
7 * Portions of this software were developed for the FreeBSD Project by
8 * ThinkSec AS and NAI Labs, the Security Research Division of Network
9 * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
10 * ("CBOSS"), as part of the DARPA CHATS research program.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 *    notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 *    notice, this list of conditions and the following disclaimer in the
19 *    documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 *    must display the following acknowledgement:
22 *	This product includes software developed by the University of
23 *	California, Berkeley and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 *    may be used to endorse or promote products derived from this software
26 *    without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * SUCH DAMAGE.
39 */
40
41#ifndef lint
42static const char copyright[] =
43"@(#) Copyright (c) 1983, 1990, 1993, 1994\n\
44	The Regents of the University of California.  All rights reserved.\n";
45#endif /* not lint */
46
47#if 0
48#ifndef lint
49static const char sccsid[] = "From: @(#)rsh.c	8.3 (Berkeley) 4/6/94";
50#endif /* not lint */
51#endif
52
53#include <sys/cdefs.h>
54__FBSDID("$FreeBSD: stable/10/usr.bin/rsh/rsh.c 325474 2017-11-06 12:45:51Z eugen $");
55
56#include <sys/param.h>
57#include <sys/signal.h>
58#include <sys/socket.h>
59#include <sys/ioctl.h>
60#include <sys/file.h>
61#include <sys/time.h>
62
63#include <netinet/in.h>
64#include <netdb.h>
65
66#include <err.h>
67#include <errno.h>
68#include <libutil.h>
69#include <paths.h>
70#include <pwd.h>
71#include <signal.h>
72#include <stdio.h>
73#include <stdlib.h>
74#include <string.h>
75#include <unistd.h>
76
77/*
78 * rsh - remote shell
79 */
80int	rfd2;
81
82int family = PF_UNSPEC;
83char rlogin[] = "rlogin";
84
85void	connect_timeout(int);
86char   *copyargs(char * const *);
87void	sendsig(int);
88void	talk(int, int, long, pid_t, int, int);
89void	usage(void);
90
91int
92main(int argc, char *argv[])
93{
94	struct passwd const *pw;
95	struct servent const *sp;
96	long omask;
97	int argoff, asrsh, ch, dflag, nflag, Nflag, one, rem;
98	pid_t pid = 0;
99	uid_t uid;
100	char *args, *host, *p, *user;
101	int timeout = 0;
102
103	argoff = asrsh = dflag = nflag = Nflag = 0;
104	one = 1;
105	host = user = NULL;
106
107	/* if called as something other than "rsh", use it as the host name */
108	if ((p = strrchr(argv[0], '/')))
109		++p;
110	else
111		p = argv[0];
112	if (strcmp(p, "rsh"))
113		host = p;
114	else
115		asrsh = 1;
116
117	/* handle "rsh host flags" */
118	if (!host && argc > 2 && argv[1][0] != '-') {
119		host = argv[1];
120		argoff = 1;
121	}
122
123#define	OPTIONS	"468LNde:l:nt:w"
124	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
125		switch(ch) {
126		case '4':
127			family = PF_INET;
128			break;
129
130		case '6':
131			family = PF_INET6;
132			break;
133
134		case 'N':
135			Nflag = 1;
136			nflag = 0;
137			break;
138		case 'L':	/* -8Lew are ignored to allow rlogin aliases */
139		case 'e':
140		case 'w':
141		case '8':
142			break;
143		case 'd':
144			dflag = 1;
145			break;
146		case 'l':
147			user = optarg;
148			break;
149		case 'n':
150			nflag = 1;
151			Nflag = 0;
152			break;
153		case 't':
154			timeout = atoi(optarg);
155			break;
156		case '?':
157		default:
158			usage();
159		}
160	optind += argoff;
161
162	/* if haven't gotten a host yet, do so */
163	if (!host && !(host = argv[optind++]))
164		usage();
165
166	/* if no further arguments, must have been called as rlogin. */
167	if (!argv[optind]) {
168		if (asrsh)
169			*argv = rlogin;
170		execv(_PATH_RLOGIN, argv);
171		err(1, "can't exec %s", _PATH_RLOGIN);
172	}
173
174	argc -= optind;
175	argv += optind;
176
177	if (!(pw = getpwuid(uid = getuid())))
178		errx(1, "unknown user id");
179	if (!user)
180		user = pw->pw_name;
181
182	args = copyargs(argv);
183
184	sp = NULL;
185	if (sp == NULL)
186		sp = getservbyname("shell", "tcp");
187	if (sp == NULL)
188		errx(1, "shell/tcp: unknown service");
189
190	if (timeout) {
191		signal(SIGALRM, connect_timeout);
192		alarm(timeout);
193	}
194	rem = rcmd_af(&host, sp->s_port, pw->pw_name, user, args, &rfd2,
195		      family);
196	if (timeout) {
197		signal(SIGALRM, SIG_DFL);
198		alarm(0);
199	}
200
201	if (rem < 0)
202		exit(1);
203
204	if (rfd2 < 0)
205		errx(1, "can't establish stderr");
206	if (dflag) {
207		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
208		    sizeof(one)) < 0)
209			warn("setsockopt");
210		if (setsockopt(rfd2, SOL_SOCKET, SO_DEBUG, &one,
211		    sizeof(one)) < 0)
212			warn("setsockopt");
213	}
214
215	(void)setuid(uid);
216	omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGTERM));
217	if (signal(SIGINT, SIG_IGN) != SIG_IGN)
218		(void)signal(SIGINT, sendsig);
219	if (signal(SIGQUIT, SIG_IGN) != SIG_IGN)
220		(void)signal(SIGQUIT, sendsig);
221	if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
222		(void)signal(SIGTERM, sendsig);
223
224	if (!nflag) {
225		pid = fork();
226		if (pid < 0)
227			err(1, "fork");
228	}
229	else
230		(void)shutdown(rem, SHUT_WR);
231
232	(void)ioctl(rfd2, FIONBIO, &one);
233	(void)ioctl(rem, FIONBIO, &one);
234
235	talk(nflag, Nflag, omask, pid, rem, timeout);
236
237	if (!nflag)
238		(void)kill(pid, SIGKILL);
239	exit(0);
240}
241
242void
243talk(int nflag, int Nflag, long omask, pid_t pid, int rem, int timeout)
244{
245	int cc, wc;
246	fd_set readfrom, ready, rembits;
247	char buf[BUFSIZ];
248	const char *bp;
249	struct timeval tvtimeout;
250	int nfds, srval;
251
252	if (!nflag && pid == 0) {
253		(void)close(rfd2);
254
255reread:		errno = 0;
256		if ((cc = read(0, buf, sizeof buf)) <= 0)
257			goto done;
258		bp = buf;
259
260rewrite:
261		if (rem >= FD_SETSIZE)
262			errx(1, "descriptor too big");
263		FD_ZERO(&rembits);
264		FD_SET(rem, &rembits);
265		nfds = rem + 1;
266		if (select(nfds, 0, &rembits, 0, 0) < 0) {
267			if (errno != EINTR)
268				err(1, "select");
269			goto rewrite;
270		}
271		if (!FD_ISSET(rem, &rembits))
272			goto rewrite;
273		wc = write(rem, bp, cc);
274		if (wc < 0) {
275			if (errno == EWOULDBLOCK)
276				goto rewrite;
277			goto done;
278		}
279		bp += wc;
280		cc -= wc;
281		if (cc == 0)
282			goto reread;
283		goto rewrite;
284done:		if (!Nflag)
285			(void)shutdown(rem, SHUT_WR);
286		exit(0);
287	}
288
289	tvtimeout.tv_sec = timeout;
290	tvtimeout.tv_usec = 0;
291
292	(void)sigsetmask(omask);
293	if (rfd2 >= FD_SETSIZE || rem >= FD_SETSIZE)
294		errx(1, "descriptor too big");
295	FD_ZERO(&readfrom);
296	FD_SET(rfd2, &readfrom);
297	FD_SET(rem, &readfrom);
298	nfds = MAX(rfd2+1, rem+1);
299	do {
300		ready = readfrom;
301		if (timeout) {
302			srval = select(nfds, &ready, 0, 0, &tvtimeout);
303		} else {
304			srval = select(nfds, &ready, 0, 0, 0);
305		}
306
307		if (srval < 0) {
308			if (errno != EINTR)
309				err(1, "select");
310			continue;
311		}
312		if (srval == 0)
313			errx(1, "timeout reached (%d seconds)", timeout);
314		if (FD_ISSET(rfd2, &ready)) {
315			errno = 0;
316			cc = read(rfd2, buf, sizeof buf);
317			if (cc <= 0) {
318				if (errno != EWOULDBLOCK)
319					FD_CLR(rfd2, &readfrom);
320			} else
321				(void)write(STDERR_FILENO, buf, cc);
322		}
323		if (FD_ISSET(rem, &ready)) {
324			errno = 0;
325			cc = read(rem, buf, sizeof buf);
326			if (cc <= 0) {
327				if (errno != EWOULDBLOCK)
328					FD_CLR(rem, &readfrom);
329			} else
330				(void)write(STDOUT_FILENO, buf, cc);
331		}
332	} while (FD_ISSET(rfd2, &readfrom) || FD_ISSET(rem, &readfrom));
333}
334
335void
336connect_timeout(int sig __unused)
337{
338	char message[] = "timeout reached before connection completed.\n";
339
340	write(STDERR_FILENO, message, sizeof(message) - 1);
341	_exit(1);
342}
343
344void
345sendsig(int sig)
346{
347	char signo;
348
349	signo = sig;
350	(void)write(rfd2, &signo, 1);
351}
352
353char *
354copyargs(char * const *argv)
355{
356	int cc;
357	char *args, *p;
358	char * const *ap;
359
360	cc = 0;
361	for (ap = argv; *ap; ++ap)
362		cc += strlen(*ap) + 1;
363	if (!(args = malloc((u_int)cc)))
364		err(1, NULL);
365	for (p = args, ap = argv; *ap; ++ap) {
366		(void)strcpy(p, *ap);
367		for (p = strcpy(p, *ap); *p; ++p);
368		if (ap[1])
369			*p++ = ' ';
370	}
371	return (args);
372}
373
374void
375usage(void)
376{
377
378	(void)fprintf(stderr,
379	    "usage: rsh [-46Ndn] [-l username] [-t timeout] host [command]\n");
380	exit(1);
381}
382