1/*	$NetBSD: rsh.c,v 1.39 2021/04/13 06:25:49 mrg 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. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33#ifndef lint
34__COPYRIGHT("@(#) Copyright (c) 1983, 1990, 1993, 1994\
35 The Regents of the University of California.  All rights reserved.");
36#endif /* not lint */
37
38#ifndef lint
39#if 0
40static char sccsid[] = "@(#)rsh.c	8.4 (Berkeley) 4/29/95";
41#else
42__RCSID("$NetBSD: rsh.c,v 1.39 2021/04/13 06:25:49 mrg Exp $");
43#endif
44#endif /* not lint */
45
46#include <sys/types.h>
47#include <sys/socket.h>
48#include <sys/ioctl.h>
49#include <sys/file.h>
50#include <poll.h>
51
52#include <netinet/in.h>
53#include <netinet/tcp.h>
54#include <netdb.h>
55
56#include <err.h>
57#include <errno.h>
58#include <limits.h>
59#include <pwd.h>
60#include <signal.h>
61#include <stdarg.h>
62#include <stdio.h>
63#include <stdlib.h>
64#include <string.h>
65#include <unistd.h>
66
67#include "pathnames.h"
68#include "getport.h"
69
70
71/*
72 * rsh - remote shell
73 */
74int	remerr;
75
76static int sigs[] = { SIGINT, SIGTERM, SIGQUIT };
77
78static char   *copyargs(char **);
79static void	sendsig(int);
80static int	checkfd(struct pollfd *, int);
81static void	talk(int, sigset_t *, pid_t, int);
82__dead static void	usage(void);
83#ifdef IN_RCMD
84int	 orcmd(char **, int, const char *,
85    const char *, const char *, int *);
86int	 orcmd_af(char **, int, const char *,
87    const char *, const char *, int *, int);
88static int	relay_signal;
89#endif
90
91int
92main(int argc, char **argv)
93{
94	struct passwd *pw;
95	struct servent *sp;
96	sigset_t oset, nset;
97	struct protoent *proto;
98
99#ifdef IN_RCMD
100	char	*locuser = 0, *loop, *relay;
101#endif /* IN_RCMD */
102	int argoff, asrsh, ch, dflag, nflag, one, rem;
103	size_t i;
104	int family = AF_UNSPEC;
105	pid_t pid;
106	uid_t uid;
107	char *args, *host, *p, *user, *name;
108
109	argoff = asrsh = dflag = nflag = 0;
110	one = 1;
111	host = user = NULL;
112	sp = NULL;
113
114#ifndef IN_RCMD
115	/*
116	 * If called as something other than "rsh" use it as the host name,
117	 * only for rsh.
118	 */
119	if (strcmp(getprogname(), "rsh") == 0)
120		asrsh = 1;
121	else {
122		host = strdup(getprogname());
123		if (host == NULL)
124			err(1, NULL);
125	}
126#endif /* IN_RCMD */
127
128	/* handle "rsh host flags" */
129	if (!host && argc > 2 && argv[1][0] != '-') {
130		host = argv[1];
131		argoff = 1;
132	}
133
134#ifdef IN_RCMD
135	if ((relay = getenv("RCMD_RELAY_SIGNAL")) && strcmp(relay, "YES") == 0)
136		relay_signal = 1;
137	if ((loop = getenv("RCMD_LOOP")) && strcmp(loop, "YES") == 0)
138		warnx("rcmd appears to be looping!");
139
140	setenv("RCMD_LOOP", "YES", 1);
141
142#  define	OPTIONS	"468KLdel:np:u:w"
143
144#else /* IN_RCMD */
145
146#  define	OPTIONS	"468KLdel:np:w"
147
148#endif /* IN_RCMD */
149
150	if (!(pw = getpwuid(uid = getuid())))
151		errx(1, "unknown user id");
152
153	if ((name = strdup(pw->pw_name)) == NULL)
154		err(1, "malloc");
155	while ((ch = getopt(argc - argoff, argv + argoff, OPTIONS)) != -1)
156		switch (ch) {
157		case '4':
158			family = AF_INET;
159			break;
160		case '6':
161			family = AF_INET6;
162			break;
163		case 'K':
164			break;
165		case 'L':	/* -8Lew are ignored to allow rlogin aliases */
166		case 'e':
167		case 'w':
168		case '8':
169			break;
170		case 'd':
171			dflag = 1;
172			break;
173		case 'l':
174			user = optarg;
175			break;
176		case 'n':
177			nflag = 1;
178			break;
179		case 'p':
180			sp = getport(optarg, "tcp");
181			break;
182#ifdef IN_RCMD
183		case 'u':
184			if (getuid() != 0 && optarg && name &&
185			    strcmp(name, optarg) != 0)
186				errx(1,"only super user can use the -u option");
187			locuser = optarg;
188			break;
189#endif /* IN_RCMD */
190		case '?':
191		default:
192			usage();
193		}
194	optind += argoff;
195
196	/* if haven't gotten a host yet, do so */
197	if (!host && !(host = argv[optind++]))
198		usage();
199
200	/* if no further arguments, must have been called as rlogin. */
201	if (!argv[optind]) {
202#ifdef IN_RCMD
203		usage();
204#else
205		if (asrsh)
206			*argv = __UNCONST("rlogin");
207		setuid(uid);
208		execv(_PATH_RLOGIN, argv);
209		err(1, "can't exec %s", _PATH_RLOGIN);
210#endif
211	}
212
213	argc -= optind;
214	argv += optind;
215
216	/* Accept user1@host format, though "-l user2" overrides user1 */
217	p = strchr(host, '@');
218	if (p) {
219		*p = '\0';
220		if (!user && p > host)
221			user = host;
222		host = p + 1;
223		if (*host == '\0')
224			usage();
225	}
226	if (!user)
227		user = name;
228
229
230	args = copyargs(argv);
231
232	if (sp == NULL)
233		sp = getservbyname("shell", "tcp");
234	if (sp == NULL)
235		errx(1, "shell/tcp: unknown service");
236
237
238#ifdef IN_RCMD
239	rem = orcmd_af(&host, sp->s_port, locuser ? locuser :
240#else
241	rem = rcmd_af(&host, sp->s_port,
242#endif
243	    name, user, args, &remerr, family);
244	(void)free(name);
245
246	if (rem < 0)
247		exit(1);
248
249	if (remerr < 0)
250		errx(1, "can't establish stderr");
251	if (dflag) {
252		if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one,
253		    sizeof(one)) < 0)
254			warn("setsockopt remote");
255		if (setsockopt(remerr, SOL_SOCKET, SO_DEBUG, &one,
256		    sizeof(one)) < 0)
257			warn("setsockopt stderr");
258	}
259	proto = getprotobyname("tcp");
260	setsockopt(rem, proto->p_proto, TCP_NODELAY, &one, sizeof(one));
261	setsockopt(remerr, proto->p_proto, TCP_NODELAY, &one, sizeof(one));
262
263
264	(void)setuid(uid);
265
266	(void)sigemptyset(&nset);
267	for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++)
268		(void)sigaddset(&nset, sigs[i]);
269
270	(void)sigprocmask(SIG_BLOCK, &nset, &oset);
271
272#ifdef IN_RCMD
273	if (!relay_signal)
274#endif
275		for (i = 0; i < sizeof(sigs) / sizeof(sigs[0]); i++) {
276			struct sigaction sa;
277
278			if (sa.sa_handler != SIG_IGN) {
279				sa.sa_handler = sendsig;
280				(void)sigaction(sigs[i], &sa, NULL);
281			}
282		}
283
284	if (!nflag) {
285		pid = fork();
286		if (pid < 0)
287			err(1, "fork");
288	}
289	else
290		pid = -1;
291
292	(void)ioctl(remerr, FIONBIO, &one);
293	(void)ioctl(rem, FIONBIO, &one);
294
295	talk(nflag, &oset, pid, rem);
296
297	if (!nflag)
298		(void)kill(pid, SIGKILL);
299	exit(0);
300}
301
302static int
303checkfd(struct pollfd *fdp, int outfd)
304{
305	int nr, nw;
306	char buf[BUFSIZ];
307
308	if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
309		return -1;
310
311	if ((fdp->revents & POLLIN) == 0)
312		return 0;
313
314	errno = 0;
315	nr = read(fdp->fd, buf, sizeof buf);
316
317	if (nr <= 0) {
318		if (errno != EAGAIN)
319			return -1;
320		else
321			return 0;
322	}
323	else {
324		char *bc = buf;
325		while (nr) {
326			if ((nw = write(outfd, bc, nr)) <= 0)
327				return -1;
328			nr -= nw;
329			bc += nw;
330		}
331		return 0;
332	}
333}
334
335static void
336talk(int nflag, sigset_t *oset, __pid_t pid, int rem)
337{
338	int nr, nw, nfds;
339	struct pollfd fds[3], *fdp = &fds[0];
340	char *bp, buf[BUFSIZ];
341
342	if (!nflag && pid == 0) {
343		(void)close(remerr);
344
345		fdp->events = POLLOUT|POLLNVAL|POLLERR|POLLHUP;
346		fdp->fd = rem;
347		nr = 0;
348		bp = buf;
349
350		for (;;) {
351			errno = 0;
352
353			if (nr == 0) {
354				if ((nr = read(0, buf, sizeof buf)) == 0)
355					goto done;
356				if (nr == -1) {
357					if (errno == EIO)
358						goto done;
359					if (errno == EINTR) {
360						nr = 0;
361						continue;
362					}
363					err(1, "read");
364				}
365				bp = buf;
366			}
367
368rewrite:		if (poll(fdp, 1, INFTIM) == -1) {
369				if (errno != EINTR)
370					err(1, "poll");
371				goto rewrite;
372			}
373
374			if (fdp->revents & (POLLNVAL|POLLERR|POLLHUP))
375				err(1, "poll");
376
377			if ((fdp->revents & POLLOUT) == 0)
378				goto rewrite;
379
380			nw = write(rem, bp, nr);
381
382			if (nw < 0) {
383				if (errno == EAGAIN)
384					continue;
385				err(1, "write");
386			}
387			bp += nw;
388			nr -= nw;
389		}
390done:
391		(void)shutdown(rem, 1);
392		exit(0);
393	}
394
395	fdp = &fds[1];
396	nfds = 2;
397	fds[0].events = 0;
398#ifdef IN_RCMD
399	if (relay_signal) {
400		fdp = &fds[0];
401		nfds = 3;
402		fds[0].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
403		fds[0].fd = 2;
404	} else
405#endif
406		(void)sigprocmask(SIG_SETMASK, oset, NULL);
407	fds[1].events = fds[2].events = POLLIN|POLLNVAL|POLLERR|POLLHUP;
408	fds[1].fd = remerr;
409	fds[2].fd = rem;
410	do {
411		if (poll(fdp, nfds, INFTIM) == -1) {
412			if (errno != EINTR)
413				err(1, "poll");
414			continue;
415		}
416		if ((fds[1].events != 0 && checkfd(&fds[1], 2) == -1)
417#ifdef IN_RCMD
418		    || (fds[0].events != 0 && checkfd(&fds[0], remerr) == -1)
419#endif
420		    ) {
421			nfds--;
422			fds[1].events = 0;
423#ifdef IN_RCMD
424			if (relay_signal) {
425				nfds--;
426				fds[0].events = 0;
427			}
428#endif
429			fdp = &fds[2];
430		}
431		if (fds[2].events != 0 && checkfd(&fds[2], 1) == -1) {
432			nfds--;
433			fds[2].events = 0;
434		}
435	}
436	while (nfds);
437}
438
439static void
440sendsig(int sig)
441{
442	char signo;
443
444	signo = sig;
445	(void)write(remerr, &signo, 1);
446}
447
448static char *
449copyargs(char **argv)
450{
451	int cc;
452	char **ap, *args, *p, *ep;
453
454	cc = 0;
455	for (ap = argv; *ap; ++ap)
456		cc += strlen(*ap) + 1;
457	if (cc == 0)
458		usage();
459	if (!(args = malloc((u_int)cc)))
460		err(1, "malloc");
461	ep = args + cc;
462	for (p = args, *p = '\0', ap = argv; *ap; ++ap) {
463		(void)strlcpy(p, *ap, ep - p);
464		p += strlen(p);
465		if (ap[1])
466			*p++ = ' ';
467	}
468	*p = '\0';
469	return (args);
470}
471
472static void
473usage(void)
474{
475
476	(void)fprintf(stderr,
477	    "usage: %s [-46dn] [-l login] [-p port]%s [login@]host command\n",
478	    getprogname(),
479#ifdef IN_RCMD
480	    " [-u locuser]"
481#else
482	    ""
483#endif
484	    );
485	exit(1);
486}
487