rlogind.c revision 1592 
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 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
41static char sccsid[] = "@(#)rlogind.c	8.1 (Berkeley) 6/4/93";
42#endif /* not lint */
43
44/*
45 * remote login server:
46 *	\0
47 *	remuser\0
48 *	locuser\0
49 *	terminal_type/speed\0
50 *	data
51 */
52
53#define	FD_SETSIZE	16		/* don't need many bits for select */
54#include <sys/param.h>
55#include <sys/stat.h>
56#include <sys/ioctl.h>
57#include <signal.h>
58#include <termios.h>
59
60#include <sys/socket.h>
61#include <netinet/in.h>
62#include <netinet/in_systm.h>
63#include <netinet/ip.h>
64#include <arpa/inet.h>
65#include <netdb.h>
66
67#include <pwd.h>
68#include <syslog.h>
69#include <errno.h>
70#include <stdio.h>
71#include <unistd.h>
72#include <stdlib.h>
73#include <string.h>
74#include "pathnames.h"
75
76#ifndef TIOCPKT_WINDOW
77#define TIOCPKT_WINDOW 0x80
78#endif
79
80#ifdef	KERBEROS
81#include <kerberosIV/des.h>
82#include <kerberosIV/krb.h>
83#define	SECURE_MESSAGE "This rlogin session is using DES encryption for all transmissions.\r\n"
84
85AUTH_DAT	*kdata;
86KTEXT		ticket;
87u_char		auth_buf[sizeof(AUTH_DAT)];
88u_char		tick_buf[sizeof(KTEXT_ST)];
89Key_schedule	schedule;
90int		doencrypt, retval, use_kerberos, vacuous;
91
92#define		ARGSTR			"alnkvx"
93#else
94#define		ARGSTR			"aln"
95#endif	/* KERBEROS */
96
97char	*env[2];
98#define	NMAX 30
99char	lusername[NMAX+1], rusername[NMAX+1];
100static	char term[64] = "TERM=";
101#define	ENVSIZE	(sizeof("TERM=")-1)	/* skip null for concatenation */
102int	keepalive = 1;
103int	check_all = 0;
104
105struct	passwd *pwd;
106
107void	doit __P((int, struct sockaddr_in *));
108int	control __P((int, char *, int));
109void	protocol __P((int, int));
110void	cleanup __P((int));
111void	fatal __P((int, char *, int));
112int	do_rlogin __P((struct sockaddr_in *));
113void	getstr __P((char *, int, char *));
114void	setup_term __P((int));
115int	do_krb_login __P((struct sockaddr_in *));
116void	usage __P((void));
117int	local_domain __P((char *));
118char	*topdomain __P((char *));
119
120int
121main(argc, argv)
122	int argc;
123	char *argv[];
124{
125	extern int __check_rhosts_file;
126	struct sockaddr_in from;
127	int ch, fromlen, on;
128
129	openlog("rlogind", LOG_PID | LOG_CONS, LOG_AUTH);
130
131	opterr = 0;
132	while ((ch = getopt(argc, argv, ARGSTR)) != EOF)
133		switch (ch) {
134		case 'a':
135			check_all = 1;
136			break;
137		case 'l':
138			__check_rhosts_file = 0;
139			break;
140		case 'n':
141			keepalive = 0;
142			break;
143#ifdef KERBEROS
144		case 'k':
145			use_kerberos = 1;
146			break;
147		case 'v':
148			vacuous = 1;
149			break;
150#ifdef CRYPT
151		case 'x':
152			doencrypt = 1;
153			break;
154#endif
155#endif
156		case '?':
157		default:
158			usage();
159			break;
160		}
161	argc -= optind;
162	argv += optind;
163
164#ifdef	KERBEROS
165	if (use_kerberos && vacuous) {
166		usage();
167		fatal(STDERR_FILENO, "only one of -k and -v allowed", 0);
168	}
169#endif
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	on = IPTOS_LOWDELAY;
180	if (setsockopt(0, IPPROTO_IP, IP_TOS, (char *)&on, sizeof(int)) < 0)
181		syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
182	doit(0, &from);
183}
184
185int	child;
186int	netf;
187char	line[MAXPATHLEN];
188int	confirmed;
189
190struct winsize win = { 0, 0, 0, 0 };
191
192
193void
194doit(f, fromp)
195	int f;
196	struct sockaddr_in *fromp;
197{
198	int master, pid, on = 1;
199	int authenticated = 0;
200	register struct hostent *hp;
201	char hostname[2 * MAXHOSTNAMELEN + 1];
202	char c;
203
204	alarm(60);
205	read(f, &c, 1);
206
207	if (c != 0)
208		exit(1);
209#ifdef	KERBEROS
210	if (vacuous)
211		fatal(f, "Remote host requires Kerberos authentication", 0);
212#endif
213
214	alarm(0);
215	fromp->sin_port = ntohs((u_short)fromp->sin_port);
216	hp = gethostbyaddr((char *)&fromp->sin_addr, sizeof(struct in_addr),
217	    fromp->sin_family);
218	if (hp)
219		(void)strcpy(hostname, hp->h_name);
220	else
221		(void)strcpy(hostname, inet_ntoa(fromp->sin_addr));
222
223#ifdef	KERBEROS
224	if (use_kerberos) {
225		retval = do_krb_login(fromp);
226		if (retval == 0)
227			authenticated++;
228		else if (retval > 0)
229			fatal(f, krb_err_txt[retval], 0);
230		write(f, &c, 1);
231		confirmed = 1;		/* we sent the null! */
232	} else
233#endif
234	{
235		if (fromp->sin_family != AF_INET ||
236		    fromp->sin_port >= IPPORT_RESERVED ||
237		    fromp->sin_port < IPPORT_RESERVED/2) {
238			syslog(LOG_NOTICE, "Connection from %s on illegal port",
239				inet_ntoa(fromp->sin_addr));
240			fatal(f, "Permission denied", 0);
241		}
242#ifdef IP_OPTIONS
243		{
244		u_char optbuf[BUFSIZ/3], *cp;
245		char lbuf[BUFSIZ], *lp;
246		int optsize = sizeof(optbuf), ipproto;
247		struct protoent *ip;
248
249		if ((ip = getprotobyname("ip")) != NULL)
250			ipproto = ip->p_proto;
251		else
252			ipproto = IPPROTO_IP;
253		if (getsockopt(0, ipproto, IP_OPTIONS, (char *)optbuf,
254		    &optsize) == 0 && optsize != 0) {
255			lp = lbuf;
256			for (cp = optbuf; optsize > 0; cp++, optsize--, lp += 3)
257				sprintf(lp, " %2.2x", *cp);
258			syslog(LOG_NOTICE,
259			    "Connection received using IP options (ignored):%s",
260			    lbuf);
261			if (setsockopt(0, ipproto, IP_OPTIONS,
262			    (char *)NULL, optsize) != 0) {
263				syslog(LOG_ERR,
264				    "setsockopt IP_OPTIONS NULL: %m");
265				exit(1);
266			}
267		}
268		}
269#endif
270		if (do_rlogin(fromp) == 0)
271			authenticated++;
272	}
273	if (confirmed == 0) {
274		write(f, "", 1);
275		confirmed = 1;		/* we sent the null! */
276	}
277#ifdef	KERBEROS
278#ifdef	CRYPT
279	if (doencrypt)
280		(void) des_write(f, SECURE_MESSAGE, sizeof(SECURE_MESSAGE) - 1);
281#endif
282#endif
283	netf = f;
284
285	pid = forkpty(&master, line, NULL, &win);
286	if (pid < 0) {
287		if (errno == ENOENT)
288			fatal(f, "Out of ptys", 0);
289		else
290			fatal(f, "Forkpty", 1);
291	}
292	if (pid == 0) {
293		if (f > 2)	/* f should always be 0, but... */
294			(void) close(f);
295		setup_term(0);
296		if (authenticated) {
297#ifdef	KERBEROS
298			if (use_kerberos && (pwd->pw_uid == 0))
299				syslog(LOG_INFO|LOG_AUTH,
300				    "ROOT Kerberos login from %s.%s@%s on %s\n",
301				    kdata->pname, kdata->pinst, kdata->prealm,
302				    hostname);
303#endif
304
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#ifdef	KERBEROS
315	/*
316	 * If encrypted, don't turn on NBIO or the des read/write
317	 * routines will croak.
318	 */
319
320	if (!doencrypt)
321#endif
322#endif
323		ioctl(f, FIONBIO, &on);
324	ioctl(master, FIONBIO, &on);
325	ioctl(master, TIOCPKT, &on);
326	signal(SIGCHLD, cleanup);
327	protocol(f, master);
328	signal(SIGCHLD, SIG_IGN);
329	cleanup(0);
330}
331
332char	magic[2] = { 0377, 0377 };
333char	oobdata[] = {TIOCPKT_WINDOW};
334
335/*
336 * Handle a "control" request (signaled by magic being present)
337 * in the data stream.  For now, we are only willing to handle
338 * window size changes.
339 */
340int
341control(pty, cp, n)
342	int pty;
343	char *cp;
344	int n;
345{
346	struct winsize w;
347
348	if (n < 4+sizeof (w) || cp[2] != 's' || cp[3] != 's')
349		return (0);
350	oobdata[0] &= ~TIOCPKT_WINDOW;	/* we know he heard */
351	bcopy(cp+4, (char *)&w, sizeof(w));
352	w.ws_row = ntohs(w.ws_row);
353	w.ws_col = ntohs(w.ws_col);
354	w.ws_xpixel = ntohs(w.ws_xpixel);
355	w.ws_ypixel = ntohs(w.ws_ypixel);
356	(void)ioctl(pty, TIOCSWINSZ, &w);
357	return (4+sizeof (w));
358}
359
360/*
361 * rlogin "protocol" machine.
362 */
363void
364protocol(f, p)
365	register int f, p;
366{
367	char pibuf[1024+1], fibuf[1024], *pbp, *fbp;
368	register pcc = 0, fcc = 0;
369	int cc, nfd, n;
370	char cntl;
371
372	/*
373	 * Must ignore SIGTTOU, otherwise we'll stop
374	 * when we try and set slave pty's window shape
375	 * (our controlling tty is the master pty).
376	 */
377	(void) signal(SIGTTOU, SIG_IGN);
378	send(f, oobdata, 1, MSG_OOB);	/* indicate new rlogin */
379	if (f > p)
380		nfd = f + 1;
381	else
382		nfd = p + 1;
383	if (nfd > FD_SETSIZE) {
384		syslog(LOG_ERR, "select mask too small, increase FD_SETSIZE");
385		fatal(f, "internal error (select mask too small)", 0);
386	}
387	for (;;) {
388		fd_set ibits, obits, ebits, *omask;
389
390		FD_ZERO(&ebits);
391		FD_ZERO(&ibits);
392		FD_ZERO(&obits);
393		omask = (fd_set *)NULL;
394		if (fcc) {
395			FD_SET(p, &obits);
396			omask = &obits;
397		} else
398			FD_SET(f, &ibits);
399		if (pcc >= 0)
400			if (pcc) {
401				FD_SET(f, &obits);
402				omask = &obits;
403			} else
404				FD_SET(p, &ibits);
405		FD_SET(p, &ebits);
406		if ((n = select(nfd, &ibits, omask, &ebits, 0)) < 0) {
407			if (errno == EINTR)
408				continue;
409			fatal(f, "select", 1);
410		}
411		if (n == 0) {
412			/* shouldn't happen... */
413			sleep(5);
414			continue;
415		}
416#define	pkcontrol(c)	((c)&(TIOCPKT_FLUSHWRITE|TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))
417		if (FD_ISSET(p, &ebits)) {
418			cc = read(p, &cntl, 1);
419			if (cc == 1 && pkcontrol(cntl)) {
420				cntl |= oobdata[0];
421				send(f, &cntl, 1, MSG_OOB);
422				if (cntl & TIOCPKT_FLUSHWRITE) {
423					pcc = 0;
424					FD_CLR(p, &ibits);
425				}
426			}
427		}
428		if (FD_ISSET(f, &ibits)) {
429#ifdef	CRYPT
430#ifdef	KERBEROS
431			if (doencrypt)
432				fcc = des_read(f, fibuf, sizeof(fibuf));
433			else
434#endif
435#endif
436				fcc = read(f, fibuf, sizeof(fibuf));
437			if (fcc < 0 && errno == EWOULDBLOCK)
438				fcc = 0;
439			else {
440				register char *cp;
441				int left, n;
442
443				if (fcc <= 0)
444					break;
445				fbp = fibuf;
446
447			top:
448				for (cp = fibuf; cp < fibuf+fcc-1; cp++)
449					if (cp[0] == magic[0] &&
450					    cp[1] == magic[1]) {
451						left = fcc - (cp-fibuf);
452						n = control(p, cp, left);
453						if (n) {
454							left -= n;
455							if (left > 0)
456								bcopy(cp+n, cp, left);
457							fcc -= n;
458							goto top; /* n^2 */
459						}
460					}
461				FD_SET(p, &obits);		/* try write */
462			}
463		}
464
465		if (FD_ISSET(p, &obits) && fcc > 0) {
466			cc = write(p, fbp, fcc);
467			if (cc > 0) {
468				fcc -= cc;
469				fbp += cc;
470			}
471		}
472
473		if (FD_ISSET(p, &ibits)) {
474			pcc = read(p, pibuf, sizeof (pibuf));
475			pbp = pibuf;
476			if (pcc < 0 && errno == EWOULDBLOCK)
477				pcc = 0;
478			else if (pcc <= 0)
479				break;
480			else if (pibuf[0] == 0) {
481				pbp++, pcc--;
482#ifdef	CRYPT
483#ifdef	KERBEROS
484				if (!doencrypt)
485#endif
486#endif
487					FD_SET(f, &obits);	/* try write */
488			} else {
489				if (pkcontrol(pibuf[0])) {
490					pibuf[0] |= oobdata[0];
491					send(f, &pibuf[0], 1, MSG_OOB);
492				}
493				pcc = 0;
494			}
495		}
496		if ((FD_ISSET(f, &obits)) && pcc > 0) {
497#ifdef	CRYPT
498#ifdef	KERBEROS
499			if (doencrypt)
500				cc = des_write(f, pbp, pcc);
501			else
502#endif
503#endif
504				cc = write(f, pbp, pcc);
505			if (cc < 0 && errno == EWOULDBLOCK) {
506				/*
507				 * This happens when we try write after read
508				 * from p, but some old kernels balk at large
509				 * writes even when select returns true.
510				 */
511				if (!FD_ISSET(p, &ibits))
512					sleep(5);
513				continue;
514			}
515			if (cc > 0) {
516				pcc -= cc;
517				pbp += cc;
518			}
519		}
520	}
521}
522
523void
524cleanup(signo)
525	int signo;
526{
527	char *p;
528
529	p = line + sizeof(_PATH_DEV) - 1;
530	if (logout(p))
531		logwtmp(p, "", "");
532	(void)chmod(line, 0666);
533	(void)chown(line, 0, 0);
534	*p = 'p';
535	(void)chmod(line, 0666);
536	(void)chown(line, 0, 0);
537	shutdown(netf, 2);
538	exit(1);
539}
540
541void
542fatal(f, msg, syserr)
543	int f;
544	char *msg;
545	int syserr;
546{
547	int len;
548	char buf[BUFSIZ], *bp = buf;
549
550	/*
551	 * Prepend binary one to message if we haven't sent
552	 * the magic null as confirmation.
553	 */
554	if (!confirmed)
555		*bp++ = '\01';		/* error indicator */
556	if (syserr)
557		len = sprintf(bp, "rlogind: %s: %s.\r\n",
558		    msg, strerror(errno));
559	else
560		len = sprintf(bp, "rlogind: %s.\r\n", msg);
561	(void) write(f, buf, bp + len - buf);
562	exit(1);
563}
564
565int
566do_rlogin(dest)
567	struct sockaddr_in *dest;
568{
569	getstr(rusername, sizeof(rusername), "remuser too long");
570	getstr(lusername, sizeof(lusername), "locuser too long");
571	getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type too long");
572
573	pwd = getpwnam(lusername);
574	if (pwd == NULL)
575		return (-1);
576	if (pwd->pw_uid == 0)
577		return (-1);
578	/* XXX why don't we syslog() failure? */
579	return (iruserok(dest->sin_addr.s_addr, 0, rusername, lusername));
580}
581
582void
583getstr(buf, cnt, errmsg)
584	char *buf;
585	int cnt;
586	char *errmsg;
587{
588	char c;
589
590	do {
591		if (read(0, &c, 1) != 1)
592			exit(1);
593		if (--cnt < 0)
594			fatal(STDOUT_FILENO, errmsg, 0);
595		*buf++ = c;
596	} while (c != 0);
597}
598
599extern	char **environ;
600
601void
602setup_term(fd)
603	int fd;
604{
605	register char *cp = index(term+ENVSIZE, '/');
606	char *speed;
607	struct termios tt;
608
609#ifndef notyet
610	tcgetattr(fd, &tt);
611	if (cp) {
612		*cp++ = '\0';
613		speed = cp;
614		cp = index(speed, '/');
615		if (cp)
616			*cp++ = '\0';
617		cfsetspeed(&tt, atoi(speed));
618	}
619
620	tt.c_iflag = TTYDEF_IFLAG;
621	tt.c_oflag = TTYDEF_OFLAG;
622	tt.c_lflag = TTYDEF_LFLAG;
623	tcsetattr(fd, TCSAFLUSH, &tt);
624#else
625	if (cp) {
626		*cp++ = '\0';
627		speed = cp;
628		cp = index(speed, '/');
629		if (cp)
630			*cp++ = '\0';
631		tcgetattr(fd, &tt);
632		cfsetspeed(&tt, atoi(speed));
633		tcsetattr(fd, TCSAFLUSH, &tt);
634	}
635#endif
636
637	env[0] = term;
638	env[1] = 0;
639	environ = env;
640}
641
642#ifdef	KERBEROS
643#define	VERSION_SIZE	9
644
645/*
646 * Do the remote kerberos login to the named host with the
647 * given inet address
648 *
649 * Return 0 on valid authorization
650 * Return -1 on valid authentication, no authorization
651 * Return >0 for error conditions
652 */
653int
654do_krb_login(dest)
655	struct sockaddr_in *dest;
656{
657	int rc;
658	char instance[INST_SZ], version[VERSION_SIZE];
659	long authopts = 0L;	/* !mutual */
660	struct sockaddr_in faddr;
661
662	kdata = (AUTH_DAT *) auth_buf;
663	ticket = (KTEXT) tick_buf;
664
665	instance[0] = '*';
666	instance[1] = '\0';
667
668#ifdef	CRYPT
669	if (doencrypt) {
670		rc = sizeof(faddr);
671		if (getsockname(0, (struct sockaddr *)&faddr, &rc))
672			return (-1);
673		authopts = KOPT_DO_MUTUAL;
674		rc = krb_recvauth(
675			authopts, 0,
676			ticket, "rcmd",
677			instance, dest, &faddr,
678			kdata, "", schedule, version);
679		 des_set_key(kdata->session, schedule);
680
681	} else
682#endif
683		rc = krb_recvauth(
684			authopts, 0,
685			ticket, "rcmd",
686			instance, dest, (struct sockaddr_in *) 0,
687			kdata, "", (bit_64 *) 0, version);
688
689	if (rc != KSUCCESS)
690		return (rc);
691
692	getstr(lusername, sizeof(lusername), "locuser");
693	/* get the "cmd" in the rcmd protocol */
694	getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type");
695
696	pwd = getpwnam(lusername);
697	if (pwd == NULL)
698		return (-1);
699
700	/* returns nonzero for no access */
701	if (kuserok(kdata, lusername) != 0)
702		return (-1);
703
704	return (0);
705
706}
707#endif /* KERBEROS */
708
709void
710usage()
711{
712#ifdef KERBEROS
713	syslog(LOG_ERR, "usage: rlogind [-aln] [-k | -v]");
714#else
715	syslog(LOG_ERR, "usage: rlogind [-aln]");
716#endif
717}
718
719/*
720 * Check whether host h is in our local domain,
721 * defined as sharing the last two components of the domain part,
722 * or the entire domain part if the local domain has only one component.
723 * If either name is unqualified (contains no '.'),
724 * assume that the host is local, as it will be
725 * interpreted as such.
726 */
727int
728local_domain(h)
729	char *h;
730{
731	char localhost[MAXHOSTNAMELEN];
732	char *p1, *p2;
733
734	localhost[0] = 0;
735	(void) gethostname(localhost, sizeof(localhost));
736	p1 = topdomain(localhost);
737	p2 = topdomain(h);
738	if (p1 == NULL || p2 == NULL || !strcasecmp(p1, p2))
739		return (1);
740	return (0);
741}
742
743char *
744topdomain(h)
745	char *h;
746{
747	register char *p;
748	char *maybe = NULL;
749	int dots = 0;
750
751	for (p = h + strlen(h); p >= h; p--) {
752		if (*p == '.') {
753			if (++dots == 2)
754				return (p);
755			maybe = p;
756		}
757	}
758	return (maybe);
759}
760