rsh.c revision 105269 
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#ifndef lint
48static const char sccsid[] = "From: @(#)rsh.c	8.3 (Berkeley) 4/6/94";
49#endif /* not lint */
50
51#include <sys/cdefs.h>
52__FBSDID("$FreeBSD: head/usr.bin/rsh/rsh.c 105269 2002-10-16 16:10:46Z markm $");
53
54#include <sys/param.h>
55#include <sys/signal.h>
56#include <sys/socket.h>
57#include <sys/ioctl.h>
58#include <sys/file.h>
59#include <sys/time.h>
60
61#include <netinet/in.h>
62#include <netdb.h>
63
64#include <err.h>
65#include <errno.h>
66#include <libutil.h>
67#include <paths.h>
68#include <pwd.h>
69#include <signal.h>
70#include <stdio.h>
71#include <stdlib.h>
72#include <string.h>
73#include <unistd.h>
74#include <err.h>
75
76/*
77 * rsh - remote shell
78 */
79int	rfd2;
80
81int family = PF_UNSPEC;
82char rlogin[] = "rlogin";
83
84void	connect_timeout(int);
85char   *copyargs(char * const *);
86void	sendsig(int);
87void	talk(int, long, pid_t, int, int);
88void	usage(void);
89
90int
91main(int argc, char *argv[])
92{
93	struct passwd const *pw;
94	struct servent const *sp;
95	long omask;
96	int argoff, asrsh, ch, dflag, nflag, one, rem;
97	pid_t pid = 0;
98	uid_t uid;
99	char *args, *host, *p, *user;
100	int timeout = 0;
101
102	argoff = asrsh = dflag = nflag = 0;
103	one = 1;
104	host = user = NULL;
105
106	/* if called as something other than "rsh", use it as the host name */
107	if ((p = strrchr(argv[0], '/')))
108		++p;
109	else
110		p = argv[0];
111	if (strcmp(p, "rsh"))
112		host = p;
113	else
114		asrsh = 1;
115
116	/* handle "rsh host flags" */
117	if (!host && argc > 2 && argv[1][0] != '-') {
118		host = argv[1];
119		argoff = 1;
120	}
121
122#define	OPTIONS	"468KLde:l:nt:w"
123	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
124		switch(ch) {
125		case '4':
126			family = PF_INET;
127			break;
128
129		case '6':
130			family = PF_INET6;
131			break;
132
133		case 'L':	/* -8Lew are ignored to allow rlogin aliases */
134		case 'e':
135		case 'w':
136		case '8':
137			break;
138		case 'd':
139			dflag = 1;
140			break;
141		case 'l':
142			user = optarg;
143			break;
144		case 'n':
145			nflag = 1;
146			break;
147		case 't':
148			timeout = atoi(optarg);
149			break;
150		case '?':
151		default:
152			usage();
153		}
154	optind += argoff;
155
156	/* if haven't gotten a host yet, do so */
157	if (!host && !(host = argv[optind++]))
158		usage();
159
160	/* if no further arguments, must have been called as rlogin. */
161	if (!argv[optind]) {
162		if (asrsh)
163			*argv = rlogin;
164		execv(_PATH_RLOGIN, argv);
165		err(1, "can't exec %s", _PATH_RLOGIN);
166	}
167
168	argc -= optind;
169	argv += optind;
170
171	if (!(pw = getpwuid(uid = getuid())))
172		errx(1, "unknown user id");
173	if (!user)
174		user = pw->pw_name;
175
176	args = copyargs(argv);
177
178	sp = NULL;
179	if (sp == NULL)
180		sp = getservbyname("shell", "tcp");
181	if (sp == NULL)
182		errx(1, "shell/tcp: unknown service");
183
184	if (timeout) {
185		signal(SIGALRM, connect_timeout);
186		alarm(timeout);
187	}
188	rem = rcmd_af(&host, sp->s_port, pw->pw_name, user, args, &rfd2,
189		      family);
190	if (timeout) {
191		signal(SIGALRM, SIG_DFL);
192		alarm(0);
193	}
194
195	if (rem < 0)
196		exit(1);
197
198	if (rfd2 < 0)
199		errx(1, "can't establish stderr");
200	if (dflag) {
201		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
202		    sizeof(one)) < 0)
203			warn("setsockopt");
204		if (setsockopt(rfd2, SOL_SOCKET, SO_DEBUG, &one,
205		    sizeof(one)) < 0)
206			warn("setsockopt");
207	}
208
209	(void)setuid(uid);
210	omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGTERM));
211	if (signal(SIGINT, SIG_IGN) != SIG_IGN)
212		(void)signal(SIGINT, sendsig);
213	if (signal(SIGQUIT, SIG_IGN) != SIG_IGN)
214		(void)signal(SIGQUIT, sendsig);
215	if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
216		(void)signal(SIGTERM, sendsig);
217
218	if (!nflag) {
219		pid = fork();
220		if (pid < 0)
221			err(1, "fork");
222	}
223	else
224		(void)shutdown(rem, 1);
225
226	(void)ioctl(rfd2, FIONBIO, &one);
227	(void)ioctl(rem, FIONBIO, &one);
228
229	talk(nflag, omask, pid, rem, timeout);
230
231	if (!nflag)
232		(void)kill(pid, SIGKILL);
233	exit(0);
234}
235
236void
237talk(int nflag, long omask, pid_t pid, int rem, int timeout)
238{
239	int cc, wc;
240	fd_set readfrom, ready, rembits;
241	char buf[BUFSIZ];
242	const char *bp;
243	struct timeval tvtimeout;
244	int nfds, srval;
245
246	if (!nflag && pid == 0) {
247		(void)close(rfd2);
248
249reread:		errno = 0;
250		if ((cc = read(0, buf, sizeof buf)) <= 0)
251			goto done;
252		bp = buf;
253
254rewrite:
255		if (rem >= FD_SETSIZE)
256			errx(1, "descriptor too big");
257		FD_ZERO(&rembits);
258		FD_SET(rem, &rembits);
259		nfds = rem + 1;
260		if (select(nfds, 0, &rembits, 0, 0) < 0) {
261			if (errno != EINTR)
262				err(1, "select");
263			goto rewrite;
264		}
265		if (!FD_ISSET(rem, &rembits))
266			goto rewrite;
267		wc = write(rem, bp, cc);
268		if (wc < 0) {
269			if (errno == EWOULDBLOCK)
270				goto rewrite;
271			goto done;
272		}
273		bp += wc;
274		cc -= wc;
275		if (cc == 0)
276			goto reread;
277		goto rewrite;
278done:
279		(void)shutdown(rem, 1);
280		exit(0);
281	}
282
283	tvtimeout.tv_sec = timeout;
284	tvtimeout.tv_usec = 0;
285
286	(void)sigsetmask(omask);
287	if (rfd2 >= FD_SETSIZE || rem >= FD_SETSIZE)
288		errx(1, "descriptor too big");
289	FD_ZERO(&readfrom);
290	FD_SET(rfd2, &readfrom);
291	FD_SET(rem, &readfrom);
292	nfds = MAX(rfd2+1, rem+1);
293	do {
294		ready = readfrom;
295		if (timeout) {
296			srval = select(nfds, &ready, 0, 0, &tvtimeout);
297		} else {
298			srval = select(nfds, &ready, 0, 0, 0);
299		}
300
301		if (srval < 0) {
302			if (errno != EINTR)
303				err(1, "select");
304			continue;
305		}
306		if (srval == 0)
307			errx(1, "timeout reached (%d seconds)\n", timeout);
308		if (FD_ISSET(rfd2, &ready)) {
309			errno = 0;
310			cc = read(rfd2, buf, sizeof buf);
311			if (cc <= 0) {
312				if (errno != EWOULDBLOCK)
313					FD_CLR(rfd2, &readfrom);
314			} else
315				(void)write(STDERR_FILENO, buf, cc);
316		}
317		if (FD_ISSET(rem, &ready)) {
318			errno = 0;
319			cc = read(rem, buf, sizeof buf);
320			if (cc <= 0) {
321				if (errno != EWOULDBLOCK)
322					FD_CLR(rem, &readfrom);
323			} else
324				(void)write(STDOUT_FILENO, buf, cc);
325		}
326	} while (FD_ISSET(rfd2, &readfrom) || FD_ISSET(rem, &readfrom));
327}
328
329void
330connect_timeout(int sig)
331{
332	char message[] = "timeout reached before connection completed.\n";
333
334	write(STDERR_FILENO, message, sizeof(message) - 1);
335	_exit(1);
336}
337
338void
339sendsig(int sig)
340{
341	char signo;
342
343	signo = sig;
344	(void)write(rfd2, &signo, 1);
345}
346
347char *
348copyargs(char * const *argv)
349{
350	int cc;
351	char *args, *p;
352	char * const *ap;
353
354	cc = 0;
355	for (ap = argv; *ap; ++ap)
356		cc += strlen(*ap) + 1;
357	if (!(args = malloc((u_int)cc)))
358		err(1, NULL);
359	for (p = args, ap = argv; *ap; ++ap) {
360		(void)strcpy(p, *ap);
361		for (p = strcpy(p, *ap); *p; ++p);
362		if (ap[1])
363			*p++ = ' ';
364	}
365	return (args);
366}
367
368void
369usage(void)
370{
371
372	(void)fprintf(stderr,
373	    "usage: rsh [-46] [-nd] [-l login] [-t timeout] host [command]\n");
374	exit(1);
375}
376