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
40 static 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 */
74 int remerr;
75
76 static int sigs[] = { SIGINT, SIGTERM, SIGQUIT };
77
78 static char *copyargs(char **);
79 static void sendsig(int);
80 static int checkfd(struct pollfd *, int);
81 static void talk(int, sigset_t *, pid_t, int);
82 __dead static void usage(void);
83 #ifdef IN_RCMD
84 int orcmd(char **, int, const char *,
85 const char *, const char *, int *);
86 int orcmd_af(char **, int, const char *,
87 const char *, const char *, int *, int);
88 static int relay_signal;
89 #endif
90
91 int
main(int argc,char ** argv)92 main(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
302 static int
checkfd(struct pollfd * fdp,int outfd)303 checkfd(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
335 static void
talk(int nflag,sigset_t * oset,__pid_t pid,int rem)336 talk(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
368 rewrite: 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 }
390 done:
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
439 static void
sendsig(int sig)440 sendsig(int sig)
441 {
442 char signo;
443
444 signo = sig;
445 (void)write(remerr, &signo, 1);
446 }
447
448 static char *
copyargs(char ** argv)449 copyargs(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
472 static void
usage(void)473 usage(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