rlogind.c revision 90377 
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 90377 2002-02-07 23:57:01Z imp $";
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(int, union sockunion *);
120int	control(int, char *, int);
121void	protocol(int, int);
122void	cleanup(int);
123void	fatal(int, char *, int);
124int	do_rlogin(union sockunion *);
125void	getstr(char *, int, char *);
126void	setup_term(int);
127int	do_krb_login(struct sockaddr_in *);
128void	usage(void);
129
130
131int
132main(int argc, char *argv[])
133{
134	extern int __check_rhosts_file;
135	union sockunion from;
136	int ch, fromlen, on;
137
138	openlog("rlogind", LOG_PID | LOG_CONS, LOG_AUTH);
139
140	opterr = 0;
141	while ((ch = getopt(argc, argv, ARGSTR)) != -1)
142		switch (ch) {
143		case 'D':
144			no_delay = 1;
145			break;
146		case 'a':
147			check_all = 1;
148			break;
149		case 'l':
150			__check_rhosts_file = 0;
151			break;
152		case 'n':
153			keepalive = 0;
154			break;
155#ifdef CRYPT
156		case 'x':
157			doencrypt = 1;
158			break;
159#endif
160		case '?':
161		default:
162			usage();
163			break;
164		}
165	argc -= optind;
166	argv += optind;
167
168	fromlen = sizeof (from);
169	if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
170		syslog(LOG_ERR,"Can't get peer name of remote host: %m");
171		fatal(STDERR_FILENO, "Can't get peer name of remote host", 1);
172	}
173	on = 1;
174	if (keepalive &&
175	    setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof (on)) < 0)
176		syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
177	if (no_delay &&
178	    setsockopt(0, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) < 0)
179		syslog(LOG_WARNING, "setsockopt (TCP_NODELAY): %m");
180        if (from.su_family == AF_INET)
181      {
182	on = IPTOS_LOWDELAY;
183	if (setsockopt(0, IPPROTO_IP, IP_TOS, (char *)&on, sizeof(int)) < 0)
184		syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
185      }
186
187	doit(0, &from);
188	return 0;
189}
190
191int	child;
192int	netf;
193char	line[MAXPATHLEN];
194int	confirmed;
195
196struct winsize win = { 0, 0, 0, 0 };
197
198
199void
200doit(int f, union sockunion *fromp)
201{
202	int master, pid, on = 1;
203	int authenticated = 0;
204	char hostname[2 * MAXHOSTNAMELEN + 1];
205	char nameinfo[2 * INET6_ADDRSTRLEN + 1];
206	char c;
207
208	alarm(60);
209	read(f, &c, 1);
210
211	if (c != 0)
212		exit(1);
213
214	alarm(0);
215
216	realhostname_sa(hostname, sizeof(hostname) - 1,
217			    (struct sockaddr *)fromp, fromp->su_len);
218	/* error check ? */
219	fromp->su_port = ntohs((u_short)fromp->su_port);
220	hostname[sizeof(hostname) - 1] = '\0';
221
222	{
223		if ((fromp->su_family != AF_INET
224#ifdef INET6
225		  && fromp->su_family != AF_INET6
226#endif
227		     ) ||
228		    fromp->su_port >= IPPORT_RESERVED ||
229		    fromp->su_port < IPPORT_RESERVED/2) {
230			getnameinfo((struct sockaddr *)fromp,
231				    fromp->su_len,
232				    nameinfo, sizeof(nameinfo), NULL, 0,
233				    NI_NUMERICHOST|NI_WITHSCOPEID);
234			/* error check ? */
235			syslog(LOG_NOTICE, "Connection from %s on illegal port",
236			       nameinfo);
237			fatal(f, "Permission denied", 0);
238		}
239#ifdef IP_OPTIONS
240		if (fromp->su_family == AF_INET)
241              {
242		u_char optbuf[BUFSIZ/3];
243		int optsize = sizeof(optbuf), ipproto, i;
244		struct protoent *ip;
245
246		if ((ip = getprotobyname("ip")) != NULL)
247			ipproto = ip->p_proto;
248		else
249			ipproto = IPPROTO_IP;
250		if (getsockopt(0, ipproto, IP_OPTIONS, (char *)optbuf,
251		    &optsize) == 0 && optsize != 0) {
252			for (i = 0; i < optsize; ) {
253				u_char c = optbuf[i];
254				if (c == IPOPT_LSRR || c == IPOPT_SSRR) {
255					syslog(LOG_NOTICE,
256						"Connection refused from %s with IP option %s",
257						inet_ntoa(fromp->su_sin.sin_addr),
258						c == IPOPT_LSRR ? "LSRR" : "SSRR");
259					exit(1);
260				}
261				if (c == IPOPT_EOL)
262					break;
263				i += (c == IPOPT_NOP) ? 1 : optbuf[i+1];
264			}
265		}
266	      }
267#endif
268		if (do_rlogin(fromp) == 0)
269			authenticated++;
270	}
271	if (confirmed == 0) {
272		write(f, "", 1);
273		confirmed = 1;		/* we sent the null! */
274	}
275#ifdef	CRYPT
276	if (doencrypt)
277		(void) des_enc_write(f,
278				     SECURE_MESSAGE,
279				     strlen(SECURE_MESSAGE),
280				     schedule, &kdata->session);
281#endif
282	netf = f;
283
284	pid = forkpty(&master, line, NULL, &win);
285	if (pid < 0) {
286		if (errno == ENOENT)
287			fatal(f, "Out of ptys", 0);
288		else
289			fatal(f, "Forkpty", 1);
290	}
291	if (pid == 0) {
292		if (f > 2)	/* f should always be 0, but... */
293			(void) close(f);
294		setup_term(0);
295		 if (*lusername=='-') {
296			syslog(LOG_ERR, "tried to pass user \"%s\" to login",
297			       lusername);
298			fatal(STDERR_FILENO, "invalid user", 0);
299		}
300		if (authenticated) {
301			execl(_PATH_LOGIN, "login", "-p",
302			    "-h", hostname, "-f", lusername, (char *)NULL);
303		} else
304			execl(_PATH_LOGIN, "login", "-p",
305			    "-h", hostname, lusername, (char *)NULL);
306		fatal(STDERR_FILENO, _PATH_LOGIN, 1);
307		/*NOTREACHED*/
308	}
309#ifdef	CRYPT
310	/*
311	 * If encrypted, don't turn on NBIO or the des read/write
312	 * routines will croak.
313	 */
314
315	if (!doencrypt)
316#endif
317		ioctl(f, FIONBIO, &on);
318	ioctl(master, FIONBIO, &on);
319	ioctl(master, TIOCPKT, &on);
320	signal(SIGCHLD, cleanup);
321	protocol(f, master);
322	signal(SIGCHLD, SIG_IGN);
323	cleanup(0);
324}
325
326char	magic[2] = { 0377, 0377 };
327char	oobdata[] = {TIOCPKT_WINDOW};
328
329/*
330 * Handle a "control" request (signaled by magic being present)
331 * in the data stream.  For now, we are only willing to handle
332 * window size changes.
333 */
334int
335control(int pty, char *cp, int n)
336{
337	struct winsize w;
338
339	if (n < 4+sizeof (w) || cp[2] != 's' || cp[3] != 's')
340		return (0);
341	oobdata[0] &= ~TIOCPKT_WINDOW;	/* we know he heard */
342	bcopy(cp+4, (char *)&w, sizeof(w));
343	w.ws_row = ntohs(w.ws_row);
344	w.ws_col = ntohs(w.ws_col);
345	w.ws_xpixel = ntohs(w.ws_xpixel);
346	w.ws_ypixel = ntohs(w.ws_ypixel);
347	(void)ioctl(pty, TIOCSWINSZ, &w);
348	return (4+sizeof (w));
349}
350
351/*
352 * rlogin "protocol" machine.
353 */
354void
355protocol(int f, int p)
356{
357	char pibuf[1024+1], fibuf[1024], *pbp = NULL, *fbp = NULL;
358	int pcc = 0, fcc = 0;
359	int cc, nfd, n;
360	char cntl;
361
362	/*
363	 * Must ignore SIGTTOU, otherwise we'll stop
364	 * when we try and set slave pty's window shape
365	 * (our controlling tty is the master pty).
366	 */
367	(void) signal(SIGTTOU, SIG_IGN);
368	send(f, oobdata, 1, MSG_OOB);	/* indicate new rlogin */
369	if (f > p)
370		nfd = f + 1;
371	else
372		nfd = p + 1;
373	if (nfd > FD_SETSIZE) {
374		syslog(LOG_ERR, "select mask too small, increase FD_SETSIZE");
375		fatal(f, "internal error (select mask too small)", 0);
376	}
377	for (;;) {
378		fd_set ibits, obits, ebits, *omask;
379
380		FD_ZERO(&ebits);
381		FD_ZERO(&ibits);
382		FD_ZERO(&obits);
383		omask = (fd_set *)NULL;
384		if (fcc) {
385			FD_SET(p, &obits);
386			omask = &obits;
387		} else
388			FD_SET(f, &ibits);
389		if (pcc >= 0) {
390			if (pcc) {
391				FD_SET(f, &obits);
392				omask = &obits;
393			} else
394				FD_SET(p, &ibits);
395		}
396		FD_SET(p, &ebits);
397		if ((n = select(nfd, &ibits, omask, &ebits, 0)) < 0) {
398			if (errno == EINTR)
399				continue;
400			fatal(f, "select", 1);
401		}
402		if (n == 0) {
403			/* shouldn't happen... */
404			sleep(5);
405			continue;
406		}
407#define	pkcontrol(c)	((c)&(TIOCPKT_FLUSHWRITE|TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))
408		if (FD_ISSET(p, &ebits)) {
409			cc = read(p, &cntl, 1);
410			if (cc == 1 && pkcontrol(cntl)) {
411				cntl |= oobdata[0];
412				send(f, &cntl, 1, MSG_OOB);
413				if (cntl & TIOCPKT_FLUSHWRITE) {
414					pcc = 0;
415					FD_CLR(p, &ibits);
416				}
417			}
418		}
419		if (FD_ISSET(f, &ibits)) {
420#ifdef	CRYPT
421			if (doencrypt)
422				fcc = des_enc_read(f, fibuf, sizeof(fibuf),
423					schedule, &kdata->session);
424			else
425#endif
426				fcc = read(f, fibuf, sizeof(fibuf));
427			if (fcc < 0 && errno == EWOULDBLOCK)
428				fcc = 0;
429			else {
430				char *cp;
431				int left, n;
432
433				if (fcc <= 0)
434					break;
435				fbp = fibuf;
436
437			top:
438				for (cp = fibuf; cp < fibuf+fcc-1; cp++)
439					if (cp[0] == magic[0] &&
440					    cp[1] == magic[1]) {
441						left = fcc - (cp-fibuf);
442						n = control(p, cp, left);
443						if (n) {
444							left -= n;
445							if (left > 0)
446								bcopy(cp+n, cp, left);
447							fcc -= n;
448							goto top; /* n^2 */
449						}
450					}
451				FD_SET(p, &obits);		/* try write */
452			}
453		}
454
455		if (FD_ISSET(p, &obits) && fcc > 0) {
456			cc = write(p, fbp, fcc);
457			if (cc > 0) {
458				fcc -= cc;
459				fbp += cc;
460			}
461		}
462
463		if (FD_ISSET(p, &ibits)) {
464			pcc = read(p, pibuf, sizeof (pibuf));
465			pbp = pibuf;
466			if (pcc < 0 && errno == EWOULDBLOCK)
467				pcc = 0;
468			else if (pcc <= 0)
469				break;
470			else if (pibuf[0] == 0) {
471				pbp++, pcc--;
472#ifdef	CRYPT
473				if (!doencrypt)
474#endif
475					FD_SET(f, &obits);	/* try write */
476			} else {
477				if (pkcontrol(pibuf[0])) {
478					pibuf[0] |= oobdata[0];
479					send(f, &pibuf[0], 1, MSG_OOB);
480				}
481				pcc = 0;
482			}
483		}
484		if ((FD_ISSET(f, &obits)) && pcc > 0) {
485#ifdef	CRYPT
486			if (doencrypt)
487				cc = des_enc_write(f, pbp, pcc,
488					schedule, &kdata->session);
489			else
490#endif
491				cc = write(f, pbp, pcc);
492			if (cc < 0 && errno == EWOULDBLOCK) {
493				/*
494				 * This happens when we try write after read
495				 * from p, but some old kernels balk at large
496				 * writes even when select returns true.
497				 */
498				if (!FD_ISSET(p, &ibits))
499					sleep(5);
500				continue;
501			}
502			if (cc > 0) {
503				pcc -= cc;
504				pbp += cc;
505			}
506		}
507	}
508}
509
510void
511cleanup(int signo)
512{
513	char *p;
514
515	p = line + sizeof(_PATH_DEV) - 1;
516	if (logout(p))
517		logwtmp(p, "", "");
518	(void)chflags(line, 0);
519	(void)chmod(line, 0666);
520	(void)chown(line, 0, 0);
521	*p = 'p';
522	(void)chflags(line, 0);
523	(void)chmod(line, 0666);
524	(void)chown(line, 0, 0);
525	shutdown(netf, 2);
526	exit(1);
527}
528
529void
530fatal(int f, char *msg, int syserr)
531{
532	int len;
533	char buf[BUFSIZ], *bp = buf;
534
535	/*
536	 * Prepend binary one to message if we haven't sent
537	 * the magic null as confirmation.
538	 */
539	if (!confirmed)
540		*bp++ = '\01';		/* error indicator */
541	if (syserr)
542		len = snprintf(bp, sizeof(buf), "rlogind: %s: %s.\r\n",
543		    msg, strerror(errno));
544	else
545		len = snprintf(bp, sizeof(buf), "rlogind: %s.\r\n", msg);
546	if (len < 0)
547		len = 0;
548	(void) write(f, buf, bp + len - buf);
549	exit(1);
550}
551
552int
553do_rlogin(union sockunion *dest)
554{
555
556	getstr(rusername, sizeof(rusername), "remuser too long");
557	getstr(lusername, sizeof(lusername), "locuser too long");
558	getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type too long");
559
560	pwd = getpwnam(lusername);
561	if (pwd == NULL)
562		return (-1);
563	/* XXX why don't we syslog() failure? */
564
565	return (iruserok_sa(dest, dest->su_len, pwd->pw_uid == 0, rusername,
566			    lusername));
567}
568
569void
570getstr(char *buf, int cnt, char *errmsg)
571{
572	char c;
573
574	do {
575		if (read(STDIN_FILENO, &c, 1) != 1)
576			exit(1);
577		if (--cnt < 0)
578			fatal(STDOUT_FILENO, errmsg, 0);
579		*buf++ = c;
580	} while (c != 0);
581}
582
583extern	char **environ;
584
585void
586setup_term(int fd)
587{
588	char *cp = index(term+ENVSIZE, '/');
589	char *speed;
590	struct termios tt;
591
592#ifndef notyet
593	tcgetattr(fd, &tt);
594	if (cp) {
595		*cp++ = '\0';
596		speed = cp;
597		cp = index(speed, '/');
598		if (cp)
599			*cp++ = '\0';
600		cfsetspeed(&tt, atoi(speed));
601	}
602
603	tt.c_iflag = TTYDEF_IFLAG;
604	tt.c_oflag = TTYDEF_OFLAG;
605	tt.c_lflag = TTYDEF_LFLAG;
606	tcsetattr(fd, TCSAFLUSH, &tt);
607#else
608	if (cp) {
609		*cp++ = '\0';
610		speed = cp;
611		cp = index(speed, '/');
612		if (cp)
613			*cp++ = '\0';
614		tcgetattr(fd, &tt);
615		cfsetspeed(&tt, atoi(speed));
616		tcsetattr(fd, TCSAFLUSH, &tt);
617	}
618#endif
619
620	env[0] = term;
621	env[1] = 0;
622	environ = env;
623}
624
625void
626usage(void)
627{
628	syslog(LOG_ERR, "usage: rlogind [-" ARGSTR "]");
629}
630