rlogind.c revision 141588 
1/*-
2 * Copyright (c) 1983, 1988, 1989, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 * Copyright (c) 2002 Networks Associates Technology, Inc.
5 * All rights reserved.
6 *
7 * Portions of this software were developed for the FreeBSD Project by
8 * ThinkSec AS and NAI Labs, the Security Research Division of Network
9 * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
10 * ("CBOSS"), as part of the DARPA CHATS research program.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 *    notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 *    notice, this list of conditions and the following disclaimer in the
19 *    documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 *    must display the following acknowledgement:
22 *	This product includes software developed by the University of
23 *	California, Berkeley and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 *    may be used to endorse or promote products derived from this software
26 *    without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * SUCH DAMAGE.
39 */
40
41#if 0
42#ifndef lint
43static const char copyright[] =
44"@(#) Copyright (c) 1983, 1988, 1989, 1993\n\
45	The Regents of the University of California.  All rights reserved.\n";
46#endif /* not lint */
47
48#ifndef lint
49static const char sccsid[] = "@(#)rlogind.c	8.1 (Berkeley) 6/4/93";
50#endif /* not lint */
51#endif
52#include <sys/cdefs.h>
53__FBSDID("$FreeBSD: head/libexec/rlogind/rlogind.c 141588 2005-02-09 20:23:36Z ru $");
54
55/*
56 * remote login server:
57 *	\0
58 *	remuser\0
59 *	locuser\0
60 *	terminal_type/speed\0
61 *	data
62 */
63
64#define	FD_SETSIZE	16		/* don't need many bits for select */
65#include <sys/types.h>
66#include <sys/param.h>
67#include <sys/stat.h>
68#include <sys/ioctl.h>
69#include <signal.h>
70#include <termios.h>
71
72#include <sys/socket.h>
73#include <netinet/in.h>
74#include <netinet/in_systm.h>
75#include <netinet/ip.h>
76#include <netinet/tcp.h>
77#include <arpa/inet.h>
78#include <netdb.h>
79
80#include <errno.h>
81#include <libutil.h>
82#include <paths.h>
83#include <pwd.h>
84#include <syslog.h>
85#include <stdio.h>
86#include <stdlib.h>
87#include <string.h>
88#include <unistd.h>
89
90
91#ifndef TIOCPKT_WINDOW
92#define TIOCPKT_WINDOW 0x80
93#endif
94
95#define		ARGSTR			"Daln"
96
97/* wrapper for KAME-special getnameinfo() */
98#ifndef NI_WITHSCOPEID
99#define	NI_WITHSCOPEID	0
100#endif
101
102char	*env[2];
103#define	NMAX 30
104char	lusername[NMAX+1], rusername[NMAX+1];
105static	char term[64] = "TERM=";
106#define	ENVSIZE	(sizeof("TERM=")-1)	/* skip null for concatenation */
107int	keepalive = 1;
108int	check_all = 0;
109int	no_delay;
110
111struct	passwd *pwd;
112
113union sockunion {
114	struct sockinet {
115		u_char si_len;
116		u_char si_family;
117		u_short si_port;
118	} su_si;
119	struct sockaddr_in  su_sin;
120	struct sockaddr_in6 su_sin6;
121};
122#define su_len		su_si.si_len
123#define su_family	su_si.si_family
124#define su_port		su_si.si_port
125
126void	doit(int, union sockunion *);
127int	control(int, char *, int);
128void	protocol(int, int);
129void	cleanup(int);
130void	fatal(int, char *, int);
131int	do_rlogin(union sockunion *);
132void	getstr(char *, int, char *);
133void	setup_term(int);
134int	do_krb_login(struct sockaddr_in *);
135void	usage(void);
136
137
138int
139main(int argc, char *argv[])
140{
141	extern int __check_rhosts_file;
142	union sockunion from;
143	int ch, fromlen, on;
144
145	openlog("rlogind", LOG_PID | LOG_CONS, LOG_AUTH);
146
147	opterr = 0;
148	while ((ch = getopt(argc, argv, ARGSTR)) != -1)
149		switch (ch) {
150		case 'D':
151			no_delay = 1;
152			break;
153		case 'a':
154			check_all = 1;
155			break;
156		case 'l':
157			__check_rhosts_file = 0;
158			break;
159		case 'n':
160			keepalive = 0;
161			break;
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(int f, union sockunion *fromp)
203{
204	int master, pid, on = 1;
205	int authenticated = 0;
206	char hostname[2 * MAXHOSTNAMELEN + 1];
207	char nameinfo[2 * INET6_ADDRSTRLEN + 1];
208	char c;
209
210	alarm(60);
211	read(f, &c, 1);
212
213	if (c != 0)
214		exit(1);
215
216	alarm(0);
217
218	realhostname_sa(hostname, sizeof(hostname) - 1,
219			    (struct sockaddr *)fromp, fromp->su_len);
220	/* error check ? */
221	fromp->su_port = ntohs((u_short)fromp->su_port);
222	hostname[sizeof(hostname) - 1] = '\0';
223
224	{
225		if ((fromp->su_family != AF_INET
226#ifdef INET6
227		  && fromp->su_family != AF_INET6
228#endif
229		     ) ||
230		    fromp->su_port >= IPPORT_RESERVED ||
231		    fromp->su_port < IPPORT_RESERVED/2) {
232			getnameinfo((struct sockaddr *)fromp,
233				    fromp->su_len,
234				    nameinfo, sizeof(nameinfo), NULL, 0,
235				    NI_NUMERICHOST|NI_WITHSCOPEID);
236			/* error check ? */
237			syslog(LOG_NOTICE, "Connection from %s on illegal port",
238			       nameinfo);
239			fatal(f, "Permission denied", 0);
240		}
241#ifdef IP_OPTIONS
242		if (fromp->su_family == AF_INET)
243	      {
244		u_char optbuf[BUFSIZ/3];
245		int optsize = sizeof(optbuf), ipproto, i;
246		struct protoent *ip;
247
248		if ((ip = getprotobyname("ip")) != NULL)
249			ipproto = ip->p_proto;
250		else
251			ipproto = IPPROTO_IP;
252		if (getsockopt(0, ipproto, IP_OPTIONS, (char *)optbuf,
253		    &optsize) == 0 && optsize != 0) {
254			for (i = 0; i < optsize; ) {
255				u_char c = optbuf[i];
256				if (c == IPOPT_LSRR || c == IPOPT_SSRR) {
257					syslog(LOG_NOTICE,
258						"Connection refused from %s with IP option %s",
259						inet_ntoa(fromp->su_sin.sin_addr),
260						c == IPOPT_LSRR ? "LSRR" : "SSRR");
261					exit(1);
262				}
263				if (c == IPOPT_EOL)
264					break;
265				i += (c == IPOPT_NOP) ? 1 : optbuf[i+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	netf = f;
278
279	pid = forkpty(&master, line, NULL, &win);
280	if (pid < 0) {
281		if (errno == ENOENT)
282			fatal(f, "Out of ptys", 0);
283		else
284			fatal(f, "Forkpty", 1);
285	}
286	if (pid == 0) {
287		if (f > 2)	/* f should always be 0, but... */
288			(void) close(f);
289		setup_term(0);
290		 if (*lusername=='-') {
291			syslog(LOG_ERR, "tried to pass user \"%s\" to login",
292			       lusername);
293			fatal(STDERR_FILENO, "invalid user", 0);
294		}
295		if (authenticated) {
296			execl(_PATH_LOGIN, "login", "-p",
297			    "-h", hostname, "-f", lusername, (char *)NULL);
298		} else
299			execl(_PATH_LOGIN, "login", "-p",
300			    "-h", hostname, lusername, (char *)NULL);
301		fatal(STDERR_FILENO, _PATH_LOGIN, 1);
302		/*NOTREACHED*/
303	}
304	ioctl(f, FIONBIO, &on);
305	ioctl(master, FIONBIO, &on);
306	ioctl(master, TIOCPKT, &on);
307	signal(SIGCHLD, cleanup);
308	protocol(f, master);
309	signal(SIGCHLD, SIG_IGN);
310	cleanup(0);
311}
312
313char	magic[2] = { 0377, 0377 };
314char	oobdata[] = {TIOCPKT_WINDOW};
315
316/*
317 * Handle a "control" request (signaled by magic being present)
318 * in the data stream.  For now, we are only willing to handle
319 * window size changes.
320 */
321int
322control(int pty, char *cp, int n)
323{
324	struct winsize w;
325
326	if (n < 4 + (int)sizeof(w) || cp[2] != 's' || cp[3] != 's')
327		return (0);
328	oobdata[0] &= ~TIOCPKT_WINDOW;	/* we know he heard */
329	bcopy(cp+4, (char *)&w, sizeof(w));
330	w.ws_row = ntohs(w.ws_row);
331	w.ws_col = ntohs(w.ws_col);
332	w.ws_xpixel = ntohs(w.ws_xpixel);
333	w.ws_ypixel = ntohs(w.ws_ypixel);
334	(void)ioctl(pty, TIOCSWINSZ, &w);
335	return (4+sizeof (w));
336}
337
338/*
339 * rlogin "protocol" machine.
340 */
341void
342protocol(int f, int p)
343{
344	char pibuf[1024+1], fibuf[1024], *pbp = NULL, *fbp = NULL;
345	int pcc = 0, fcc = 0;
346	int cc, nfd, n;
347	char cntl;
348
349	/*
350	 * Must ignore SIGTTOU, otherwise we'll stop
351	 * when we try and set slave pty's window shape
352	 * (our controlling tty is the master pty).
353	 */
354	(void) signal(SIGTTOU, SIG_IGN);
355	send(f, oobdata, 1, MSG_OOB);	/* indicate new rlogin */
356	if (f > p)
357		nfd = f + 1;
358	else
359		nfd = p + 1;
360	if (nfd > FD_SETSIZE) {
361		syslog(LOG_ERR, "select mask too small, increase FD_SETSIZE");
362		fatal(f, "internal error (select mask too small)", 0);
363	}
364	for (;;) {
365		fd_set ibits, obits, ebits, *omask;
366
367		FD_ZERO(&ebits);
368		FD_ZERO(&ibits);
369		FD_ZERO(&obits);
370		omask = (fd_set *)NULL;
371		if (fcc) {
372			FD_SET(p, &obits);
373			omask = &obits;
374		} else
375			FD_SET(f, &ibits);
376		if (pcc >= 0) {
377			if (pcc) {
378				FD_SET(f, &obits);
379				omask = &obits;
380			} else
381				FD_SET(p, &ibits);
382		}
383		FD_SET(p, &ebits);
384		if ((n = select(nfd, &ibits, omask, &ebits, 0)) < 0) {
385			if (errno == EINTR)
386				continue;
387			fatal(f, "select", 1);
388		}
389		if (n == 0) {
390			/* shouldn't happen... */
391			sleep(5);
392			continue;
393		}
394#define	pkcontrol(c)	((c)&(TIOCPKT_FLUSHWRITE|TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))
395		if (FD_ISSET(p, &ebits)) {
396			cc = read(p, &cntl, 1);
397			if (cc == 1 && pkcontrol(cntl)) {
398				cntl |= oobdata[0];
399				send(f, &cntl, 1, MSG_OOB);
400				if (cntl & TIOCPKT_FLUSHWRITE) {
401					pcc = 0;
402					FD_CLR(p, &ibits);
403				}
404			}
405		}
406		if (FD_ISSET(f, &ibits)) {
407			fcc = read(f, fibuf, sizeof(fibuf));
408			if (fcc < 0 && errno == EWOULDBLOCK)
409				fcc = 0;
410			else {
411				char *cp;
412				int left, n;
413
414				if (fcc <= 0)
415					break;
416				fbp = fibuf;
417
418			top:
419				for (cp = fibuf; cp < fibuf+fcc-1; cp++)
420					if (cp[0] == magic[0] &&
421					    cp[1] == magic[1]) {
422						left = fcc - (cp-fibuf);
423						n = control(p, cp, left);
424						if (n) {
425							left -= n;
426							if (left > 0)
427								bcopy(cp+n, cp, left);
428							fcc -= n;
429							goto top; /* n^2 */
430						}
431					}
432				FD_SET(p, &obits);		/* try write */
433			}
434		}
435
436		if (FD_ISSET(p, &obits) && fcc > 0) {
437			cc = write(p, fbp, fcc);
438			if (cc > 0) {
439				fcc -= cc;
440				fbp += cc;
441			}
442		}
443
444		if (FD_ISSET(p, &ibits)) {
445			pcc = read(p, pibuf, sizeof (pibuf));
446			pbp = pibuf;
447			if (pcc < 0 && errno == EWOULDBLOCK)
448				pcc = 0;
449			else if (pcc <= 0)
450				break;
451			else if (pibuf[0] == 0) {
452				pbp++, pcc--;
453				FD_SET(f, &obits);	/* try write */
454			} else {
455				if (pkcontrol(pibuf[0])) {
456					pibuf[0] |= oobdata[0];
457					send(f, &pibuf[0], 1, MSG_OOB);
458				}
459				pcc = 0;
460			}
461		}
462		if ((FD_ISSET(f, &obits)) && pcc > 0) {
463			cc = write(f, pbp, pcc);
464			if (cc < 0 && errno == EWOULDBLOCK) {
465				/*
466				 * This happens when we try write after read
467				 * from p, but some old kernels balk at large
468				 * writes even when select returns true.
469				 */
470				if (!FD_ISSET(p, &ibits))
471					sleep(5);
472				continue;
473			}
474			if (cc > 0) {
475				pcc -= cc;
476				pbp += cc;
477			}
478		}
479	}
480}
481
482void
483cleanup(int signo)
484{
485	char *p;
486
487	p = line + sizeof(_PATH_DEV) - 1;
488	if (logout(p))
489		logwtmp(p, "", "");
490	(void)chflags(line, 0);
491	(void)chmod(line, 0666);
492	(void)chown(line, 0, 0);
493	*p = 'p';
494	(void)chflags(line, 0);
495	(void)chmod(line, 0666);
496	(void)chown(line, 0, 0);
497	shutdown(netf, 2);
498	exit(1);
499}
500
501void
502fatal(int f, char *msg, int syserr)
503{
504	int len;
505	char buf[BUFSIZ], *bp = buf;
506
507	/*
508	 * Prepend binary one to message if we haven't sent
509	 * the magic null as confirmation.
510	 */
511	if (!confirmed)
512		*bp++ = '\01';		/* error indicator */
513	if (syserr)
514		len = snprintf(bp, sizeof(buf), "rlogind: %s: %s.\r\n",
515		    msg, strerror(errno));
516	else
517		len = snprintf(bp, sizeof(buf), "rlogind: %s.\r\n", msg);
518	if (len < 0)
519		len = 0;
520	(void) write(f, buf, bp + len - buf);
521	exit(1);
522}
523
524int
525do_rlogin(union sockunion *dest)
526{
527
528	getstr(rusername, sizeof(rusername), "remuser too long");
529	getstr(lusername, sizeof(lusername), "locuser too long");
530	getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type too long");
531
532	pwd = getpwnam(lusername);
533	if (pwd == NULL)
534		return (-1);
535	/* XXX why don't we syslog() failure? */
536
537	return (iruserok_sa(dest, dest->su_len, pwd->pw_uid == 0, rusername,
538			    lusername));
539}
540
541void
542getstr(char *buf, int cnt, char *errmsg)
543{
544	char c;
545
546	do {
547		if (read(STDIN_FILENO, &c, 1) != 1)
548			exit(1);
549		if (--cnt < 0)
550			fatal(STDOUT_FILENO, errmsg, 0);
551		*buf++ = c;
552	} while (c != 0);
553}
554
555extern	char **environ;
556
557void
558setup_term(int fd)
559{
560	char *cp = index(term+ENVSIZE, '/');
561	char *speed;
562	struct termios tt;
563
564#ifndef notyet
565	tcgetattr(fd, &tt);
566	if (cp) {
567		*cp++ = '\0';
568		speed = cp;
569		cp = index(speed, '/');
570		if (cp)
571			*cp++ = '\0';
572		cfsetspeed(&tt, atoi(speed));
573	}
574
575	tt.c_iflag = TTYDEF_IFLAG;
576	tt.c_oflag = TTYDEF_OFLAG;
577	tt.c_lflag = TTYDEF_LFLAG;
578	tcsetattr(fd, TCSAFLUSH, &tt);
579#else
580	if (cp) {
581		*cp++ = '\0';
582		speed = cp;
583		cp = index(speed, '/');
584		if (cp)
585			*cp++ = '\0';
586		tcgetattr(fd, &tt);
587		cfsetspeed(&tt, atoi(speed));
588		tcsetattr(fd, TCSAFLUSH, &tt);
589	}
590#endif
591
592	env[0] = term;
593	env[1] = 0;
594	environ = env;
595}
596
597void
598usage(void)
599{
600	syslog(LOG_ERR, "usage: rlogind [-" ARGSTR "]");
601}
602