rlogind.c revision 80381 
1/*-
2 * Copyright (c) 1983, 1988, 1989, 1993
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 const char copyright[] =
36"@(#) Copyright (c) 1983, 1988, 1989, 1993\n\
37	The Regents of the University of California.  All rights reserved.\n";
38#endif /* not lint */
39
40#ifndef lint
41#if 0
42static const char sccsid[] = "@(#)rlogind.c	8.1 (Berkeley) 6/4/93";
43#endif
44static const char rcsid[] =
45  "$FreeBSD: head/libexec/rlogind/rlogind.c 80381 2001-07-26 11:02:39Z sheldonh $";
46#endif /* not lint */
47
48/*
49 * remote login server:
50 *	\0
51 *	remuser\0
52 *	locuser\0
53 *	terminal_type/speed\0
54 *	data
55 */
56
57#define	FD_SETSIZE	16		/* don't need many bits for select */
58#include <sys/types.h>
59#include <sys/param.h>
60#include <sys/stat.h>
61#include <sys/ioctl.h>
62#include <signal.h>
63#include <termios.h>
64
65#include <sys/socket.h>
66#include <netinet/in.h>
67#include <netinet/in_systm.h>
68#include <netinet/ip.h>
69#include <netinet/tcp.h>
70#include <arpa/inet.h>
71#include <netdb.h>
72
73#include <errno.h>
74#include <libutil.h>
75#include <pwd.h>
76#include <syslog.h>
77#include <stdio.h>
78#include <stdlib.h>
79#include <string.h>
80#include <unistd.h>
81#include "pathnames.h"
82
83
84#ifndef TIOCPKT_WINDOW
85#define TIOCPKT_WINDOW 0x80
86#endif
87
88#define		ARGSTR			"Dalnx"
89
90/* wrapper for KAME-special getnameinfo() */
91#ifndef NI_WITHSCOPEID
92#define	NI_WITHSCOPEID	0
93#endif
94
95char	*env[2];
96#define	NMAX 30
97char	lusername[NMAX+1], rusername[NMAX+1];
98static	char term[64] = "TERM=";
99#define	ENVSIZE	(sizeof("TERM=")-1)	/* skip null for concatenation */
100int	keepalive = 1;
101int	check_all = 0;
102int	no_delay;
103
104struct	passwd *pwd;
105
106union sockunion {
107	struct sockinet {
108		u_char si_len;
109		u_char si_family;
110		u_short si_port;
111	} su_si;
112	struct sockaddr_in  su_sin;
113	struct sockaddr_in6 su_sin6;
114};
115#define su_len		su_si.si_len
116#define su_family	su_si.si_family
117#define su_port		su_si.si_port
118
119void	doit __P((int, union sockunion *));
120int	control __P((int, char *, int));
121void	protocol __P((int, int));
122void	cleanup __P((int));
123void	fatal __P((int, char *, int));
124int	do_rlogin __P((union sockunion *));
125void	getstr __P((char *, int, char *));
126void	setup_term __P((int));
127int	do_krb_login __P((struct sockaddr_in *));
128void	usage __P((void));
129
130
131int
132main(argc, argv)
133	int argc;
134	char *argv[];
135{
136	extern int __check_rhosts_file;
137	union sockunion from;
138	int ch, fromlen, on;
139
140	openlog("rlogind", LOG_PID | LOG_CONS, LOG_AUTH);
141
142	opterr = 0;
143	while ((ch = getopt(argc, argv, ARGSTR)) != -1)
144		switch (ch) {
145		case 'D':
146			no_delay = 1;
147			break;
148		case 'a':
149			check_all = 1;
150			break;
151		case 'l':
152			__check_rhosts_file = 0;
153			break;
154		case 'n':
155			keepalive = 0;
156			break;
157#ifdef CRYPT
158		case 'x':
159			doencrypt = 1;
160			break;
161#endif
162		case '?':
163		default:
164			usage();
165			break;
166		}
167	argc -= optind;
168	argv += optind;
169
170	fromlen = sizeof (from);
171	if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
172		syslog(LOG_ERR,"Can't get peer name of remote host: %m");
173		fatal(STDERR_FILENO, "Can't get peer name of remote host", 1);
174	}
175	on = 1;
176	if (keepalive &&
177	    setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof (on)) < 0)
178		syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
179	if (no_delay &&
180	    setsockopt(0, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) < 0)
181		syslog(LOG_WARNING, "setsockopt (TCP_NODELAY): %m");
182        if (from.su_family == AF_INET)
183      {
184	on = IPTOS_LOWDELAY;
185	if (setsockopt(0, IPPROTO_IP, IP_TOS, (char *)&on, sizeof(int)) < 0)
186		syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
187      }
188
189	doit(0, &from);
190	return 0;
191}
192
193int	child;
194int	netf;
195char	line[MAXPATHLEN];
196int	confirmed;
197
198struct winsize win = { 0, 0, 0, 0 };
199
200
201void
202doit(f, fromp)
203	int f;
204	union sockunion *fromp;
205{
206	int master, pid, on = 1;
207	int authenticated = 0;
208	char hostname[2 * MAXHOSTNAMELEN + 1];
209	char nameinfo[2 * INET6_ADDRSTRLEN + 1];
210	char c;
211
212	alarm(60);
213	read(f, &c, 1);
214
215	if (c != 0)
216		exit(1);
217
218	alarm(0);
219
220	realhostname_sa(hostname, sizeof(hostname) - 1,
221			    (struct sockaddr *)fromp, fromp->su_len);
222	/* error check ? */
223	fromp->su_port = ntohs((u_short)fromp->su_port);
224	hostname[sizeof(hostname) - 1] = '\0';
225
226	{
227		if ((fromp->su_family != AF_INET
228#ifdef INET6
229		  && fromp->su_family != AF_INET6
230#endif
231		     ) ||
232		    fromp->su_port >= IPPORT_RESERVED ||
233		    fromp->su_port < IPPORT_RESERVED/2) {
234			getnameinfo((struct sockaddr *)fromp,
235				    fromp->su_len,
236				    nameinfo, sizeof(nameinfo), NULL, 0,
237				    NI_NUMERICHOST|NI_WITHSCOPEID);
238			/* error check ? */
239			syslog(LOG_NOTICE, "Connection from %s on illegal port",
240			       nameinfo);
241			fatal(f, "Permission denied", 0);
242		}
243#ifdef IP_OPTIONS
244		if (fromp->su_family == AF_INET)
245              {
246		u_char optbuf[BUFSIZ/3];
247		int optsize = sizeof(optbuf), ipproto, i;
248		struct protoent *ip;
249
250		if ((ip = getprotobyname("ip")) != NULL)
251			ipproto = ip->p_proto;
252		else
253			ipproto = IPPROTO_IP;
254		if (getsockopt(0, ipproto, IP_OPTIONS, (char *)optbuf,
255		    &optsize) == 0 && optsize != 0) {
256			for (i = 0; i < optsize; ) {
257				u_char c = optbuf[i];
258				if (c == IPOPT_LSRR || c == IPOPT_SSRR) {
259					syslog(LOG_NOTICE,
260						"Connection refused from %s with IP option %s",
261						inet_ntoa(fromp->su_sin.sin_addr),
262						c == IPOPT_LSRR ? "LSRR" : "SSRR");
263					exit(1);
264				}
265				if (c == IPOPT_EOL)
266					break;
267				i += (c == IPOPT_NOP) ? 1 : optbuf[i+1];
268			}
269		}
270	      }
271#endif
272		if (do_rlogin(fromp) == 0)
273			authenticated++;
274	}
275	if (confirmed == 0) {
276		write(f, "", 1);
277		confirmed = 1;		/* we sent the null! */
278	}
279#ifdef	CRYPT
280	if (doencrypt)
281		(void) des_enc_write(f,
282				     SECURE_MESSAGE,
283				     strlen(SECURE_MESSAGE),
284				     schedule, &kdata->session);
285#endif
286	netf = f;
287
288	pid = forkpty(&master, line, NULL, &win);
289	if (pid < 0) {
290		if (errno == ENOENT)
291			fatal(f, "Out of ptys", 0);
292		else
293			fatal(f, "Forkpty", 1);
294	}
295	if (pid == 0) {
296		if (f > 2)	/* f should always be 0, but... */
297			(void) close(f);
298		setup_term(0);
299		 if (*lusername=='-') {
300			syslog(LOG_ERR, "tried to pass user \"%s\" to login",
301			       lusername);
302			fatal(STDERR_FILENO, "invalid user", 0);
303		}
304		if (authenticated) {
305			execl(_PATH_LOGIN, "login", "-p",
306			    "-h", hostname, "-f", lusername, (char *)NULL);
307		} else
308			execl(_PATH_LOGIN, "login", "-p",
309			    "-h", hostname, lusername, (char *)NULL);
310		fatal(STDERR_FILENO, _PATH_LOGIN, 1);
311		/*NOTREACHED*/
312	}
313#ifdef	CRYPT
314	/*
315	 * If encrypted, don't turn on NBIO or the des read/write
316	 * routines will croak.
317	 */
318
319	if (!doencrypt)
320#endif
321		ioctl(f, FIONBIO, &on);
322	ioctl(master, FIONBIO, &on);
323	ioctl(master, TIOCPKT, &on);
324	signal(SIGCHLD, cleanup);
325	protocol(f, master);
326	signal(SIGCHLD, SIG_IGN);
327	cleanup(0);
328}
329
330char	magic[2] = { 0377, 0377 };
331char	oobdata[] = {TIOCPKT_WINDOW};
332
333/*
334 * Handle a "control" request (signaled by magic being present)
335 * in the data stream.  For now, we are only willing to handle
336 * window size changes.
337 */
338int
339control(pty, cp, n)
340	int pty;
341	char *cp;
342	int n;
343{
344	struct winsize w;
345
346	if (n < 4+sizeof (w) || cp[2] != 's' || cp[3] != 's')
347		return (0);
348	oobdata[0] &= ~TIOCPKT_WINDOW;	/* we know he heard */
349	bcopy(cp+4, (char *)&w, sizeof(w));
350	w.ws_row = ntohs(w.ws_row);
351	w.ws_col = ntohs(w.ws_col);
352	w.ws_xpixel = ntohs(w.ws_xpixel);
353	w.ws_ypixel = ntohs(w.ws_ypixel);
354	(void)ioctl(pty, TIOCSWINSZ, &w);
355	return (4+sizeof (w));
356}
357
358/*
359 * rlogin "protocol" machine.
360 */
361void
362protocol(f, p)
363	register int f, p;
364{
365	char pibuf[1024+1], fibuf[1024], *pbp = NULL, *fbp = NULL;
366	int pcc = 0, fcc = 0;
367	int cc, nfd, n;
368	char cntl;
369
370	/*
371	 * Must ignore SIGTTOU, otherwise we'll stop
372	 * when we try and set slave pty's window shape
373	 * (our controlling tty is the master pty).
374	 */
375	(void) signal(SIGTTOU, SIG_IGN);
376	send(f, oobdata, 1, MSG_OOB);	/* indicate new rlogin */
377	if (f > p)
378		nfd = f + 1;
379	else
380		nfd = p + 1;
381	if (nfd > FD_SETSIZE) {
382		syslog(LOG_ERR, "select mask too small, increase FD_SETSIZE");
383		fatal(f, "internal error (select mask too small)", 0);
384	}
385	for (;;) {
386		fd_set ibits, obits, ebits, *omask;
387
388		FD_ZERO(&ebits);
389		FD_ZERO(&ibits);
390		FD_ZERO(&obits);
391		omask = (fd_set *)NULL;
392		if (fcc) {
393			FD_SET(p, &obits);
394			omask = &obits;
395		} else
396			FD_SET(f, &ibits);
397		if (pcc >= 0) {
398			if (pcc) {
399				FD_SET(f, &obits);
400				omask = &obits;
401			} else
402				FD_SET(p, &ibits);
403		}
404		FD_SET(p, &ebits);
405		if ((n = select(nfd, &ibits, omask, &ebits, 0)) < 0) {
406			if (errno == EINTR)
407				continue;
408			fatal(f, "select", 1);
409		}
410		if (n == 0) {
411			/* shouldn't happen... */
412			sleep(5);
413			continue;
414		}
415#define	pkcontrol(c)	((c)&(TIOCPKT_FLUSHWRITE|TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))
416		if (FD_ISSET(p, &ebits)) {
417			cc = read(p, &cntl, 1);
418			if (cc == 1 && pkcontrol(cntl)) {
419				cntl |= oobdata[0];
420				send(f, &cntl, 1, MSG_OOB);
421				if (cntl & TIOCPKT_FLUSHWRITE) {
422					pcc = 0;
423					FD_CLR(p, &ibits);
424				}
425			}
426		}
427		if (FD_ISSET(f, &ibits)) {
428#ifdef	CRYPT
429			if (doencrypt)
430				fcc = des_enc_read(f, fibuf, sizeof(fibuf),
431					schedule, &kdata->session);
432			else
433#endif
434				fcc = read(f, fibuf, sizeof(fibuf));
435			if (fcc < 0 && errno == EWOULDBLOCK)
436				fcc = 0;
437			else {
438				register char *cp;
439				int left, n;
440
441				if (fcc <= 0)
442					break;
443				fbp = fibuf;
444
445			top:
446				for (cp = fibuf; cp < fibuf+fcc-1; cp++)
447					if (cp[0] == magic[0] &&
448					    cp[1] == magic[1]) {
449						left = fcc - (cp-fibuf);
450						n = control(p, cp, left);
451						if (n) {
452							left -= n;
453							if (left > 0)
454								bcopy(cp+n, cp, left);
455							fcc -= n;
456							goto top; /* n^2 */
457						}
458					}
459				FD_SET(p, &obits);		/* try write */
460			}
461		}
462
463		if (FD_ISSET(p, &obits) && fcc > 0) {
464			cc = write(p, fbp, fcc);
465			if (cc > 0) {
466				fcc -= cc;
467				fbp += cc;
468			}
469		}
470
471		if (FD_ISSET(p, &ibits)) {
472			pcc = read(p, pibuf, sizeof (pibuf));
473			pbp = pibuf;
474			if (pcc < 0 && errno == EWOULDBLOCK)
475				pcc = 0;
476			else if (pcc <= 0)
477				break;
478			else if (pibuf[0] == 0) {
479				pbp++, pcc--;
480#ifdef	CRYPT
481				if (!doencrypt)
482#endif
483					FD_SET(f, &obits);	/* try write */
484			} else {
485				if (pkcontrol(pibuf[0])) {
486					pibuf[0] |= oobdata[0];
487					send(f, &pibuf[0], 1, MSG_OOB);
488				}
489				pcc = 0;
490			}
491		}
492		if ((FD_ISSET(f, &obits)) && pcc > 0) {
493#ifdef	CRYPT
494			if (doencrypt)
495				cc = des_enc_write(f, pbp, pcc,
496					schedule, &kdata->session);
497			else
498#endif
499				cc = write(f, pbp, pcc);
500			if (cc < 0 && errno == EWOULDBLOCK) {
501				/*
502				 * This happens when we try write after read
503				 * from p, but some old kernels balk at large
504				 * writes even when select returns true.
505				 */
506				if (!FD_ISSET(p, &ibits))
507					sleep(5);
508				continue;
509			}
510			if (cc > 0) {
511				pcc -= cc;
512				pbp += cc;
513			}
514		}
515	}
516}
517
518void
519cleanup(signo)
520	int signo;
521{
522	char *p;
523
524	p = line + sizeof(_PATH_DEV) - 1;
525	if (logout(p))
526		logwtmp(p, "", "");
527	(void)chflags(line, 0);
528	(void)chmod(line, 0666);
529	(void)chown(line, 0, 0);
530	*p = 'p';
531	(void)chflags(line, 0);
532	(void)chmod(line, 0666);
533	(void)chown(line, 0, 0);
534	shutdown(netf, 2);
535	exit(1);
536}
537
538void
539fatal(f, msg, syserr)
540	int f;
541	char *msg;
542	int syserr;
543{
544	int len;
545	char buf[BUFSIZ], *bp = buf;
546
547	/*
548	 * Prepend binary one to message if we haven't sent
549	 * the magic null as confirmation.
550	 */
551	if (!confirmed)
552		*bp++ = '\01';		/* error indicator */
553	if (syserr)
554		len = snprintf(bp, sizeof(buf), "rlogind: %s: %s.\r\n",
555		    msg, strerror(errno));
556	else
557		len = snprintf(bp, sizeof(buf), "rlogind: %s.\r\n", msg);
558	(void) write(f, buf, bp + len - buf);
559	exit(1);
560}
561
562int
563do_rlogin(dest)
564	union sockunion *dest;
565{
566
567	getstr(rusername, sizeof(rusername), "remuser too long");
568	getstr(lusername, sizeof(lusername), "locuser too long");
569	getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type too long");
570
571	pwd = getpwnam(lusername);
572	if (pwd == NULL)
573		return (-1);
574	/* XXX why don't we syslog() failure? */
575
576	return (iruserok_sa(dest, dest->su_len, pwd->pw_uid == 0, rusername,
577			    lusername));
578}
579
580void
581getstr(buf, cnt, errmsg)
582	char *buf;
583	int cnt;
584	char *errmsg;
585{
586	char c;
587
588	do {
589		if (read(STDIN_FILENO, &c, 1) != 1)
590			exit(1);
591		if (--cnt < 0)
592			fatal(STDOUT_FILENO, errmsg, 0);
593		*buf++ = c;
594	} while (c != 0);
595}
596
597extern	char **environ;
598
599void
600setup_term(fd)
601	int fd;
602{
603	register char *cp = index(term+ENVSIZE, '/');
604	char *speed;
605	struct termios tt;
606
607#ifndef notyet
608	tcgetattr(fd, &tt);
609	if (cp) {
610		*cp++ = '\0';
611		speed = cp;
612		cp = index(speed, '/');
613		if (cp)
614			*cp++ = '\0';
615		cfsetspeed(&tt, atoi(speed));
616	}
617
618	tt.c_iflag = TTYDEF_IFLAG;
619	tt.c_oflag = TTYDEF_OFLAG;
620	tt.c_lflag = TTYDEF_LFLAG;
621	tcsetattr(fd, TCSAFLUSH, &tt);
622#else
623	if (cp) {
624		*cp++ = '\0';
625		speed = cp;
626		cp = index(speed, '/');
627		if (cp)
628			*cp++ = '\0';
629		tcgetattr(fd, &tt);
630		cfsetspeed(&tt, atoi(speed));
631		tcsetattr(fd, TCSAFLUSH, &tt);
632	}
633#endif
634
635	env[0] = term;
636	env[1] = 0;
637	environ = env;
638}
639
640void
641usage()
642{
643	syslog(LOG_ERR, "usage: rlogind [-" ARGSTR "]");
644}
645