rlogind.c revision 262435 
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. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#if 0
38#ifndef lint
39static const char copyright[] =
40"@(#) Copyright (c) 1983, 1988, 1989, 1993\n\
41	The Regents of the University of California.  All rights reserved.\n";
42#endif /* not lint */
43
44#ifndef lint
45static const char sccsid[] = "@(#)rlogind.c	8.1 (Berkeley) 6/4/93";
46#endif /* not lint */
47#endif
48#include <sys/cdefs.h>
49__FBSDID("$FreeBSD: stable/10/libexec/rlogind/rlogind.c 262435 2014-02-24 08:21:49Z brueffer $");
50
51/*
52 * remote login server:
53 *	\0
54 *	remuser\0
55 *	locuser\0
56 *	terminal_type/speed\0
57 *	data
58 */
59
60#define	FD_SETSIZE	16		/* don't need many bits for select */
61#include <sys/types.h>
62#include <sys/param.h>
63#include <sys/stat.h>
64#include <sys/ioctl.h>
65#include <signal.h>
66#include <termios.h>
67
68#include <sys/socket.h>
69#include <netinet/in.h>
70#include <netinet/in_systm.h>
71#include <netinet/ip.h>
72#include <netinet/tcp.h>
73#include <arpa/inet.h>
74#include <netdb.h>
75
76#include <errno.h>
77#include <libutil.h>
78#include <paths.h>
79#include <pwd.h>
80#include <syslog.h>
81#include <stdio.h>
82#include <stdlib.h>
83#include <string.h>
84#include <unistd.h>
85
86
87#ifndef TIOCPKT_WINDOW
88#define TIOCPKT_WINDOW 0x80
89#endif
90
91#define		ARGSTR			"Daln"
92
93char	*env[2];
94#define	NMAX 30
95char	lusername[NMAX+1], rusername[NMAX+1];
96static	char term[64] = "TERM=";
97#define	ENVSIZE	(sizeof("TERM=")-1)	/* skip null for concatenation */
98int	keepalive = 1;
99int	check_all = 0;
100int	no_delay;
101
102struct	passwd *pwd;
103
104union sockunion {
105	struct sockinet {
106		u_char si_len;
107		u_char si_family;
108		u_short si_port;
109	} su_si;
110	struct sockaddr_in  su_sin;
111	struct sockaddr_in6 su_sin6;
112};
113#define su_len		su_si.si_len
114#define su_family	su_si.si_family
115#define su_port		su_si.si_port
116
117void	doit(int, union sockunion *);
118int	control(int, char *, int);
119void	protocol(int, int);
120void	cleanup(int);
121void	fatal(int, char *, int);
122int	do_rlogin(union sockunion *);
123void	getstr(char *, int, char *);
124void	setup_term(int);
125int	do_krb_login(struct sockaddr_in *);
126void	usage(void);
127
128
129int
130main(int argc, char *argv[])
131{
132	extern int __check_rhosts_file;
133	union sockunion from;
134	socklen_t fromlen;
135	int ch, on;
136
137	openlog("rlogind", LOG_PID | LOG_CONS, LOG_AUTH);
138
139	opterr = 0;
140	while ((ch = getopt(argc, argv, ARGSTR)) != -1)
141		switch (ch) {
142		case 'D':
143			no_delay = 1;
144			break;
145		case 'a':
146			check_all = 1;
147			break;
148		case 'l':
149			__check_rhosts_file = 0;
150			break;
151		case 'n':
152			keepalive = 0;
153			break;
154		case '?':
155		default:
156			usage();
157			break;
158		}
159	argc -= optind;
160	argv += optind;
161
162	fromlen = sizeof (from);
163	if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {
164		syslog(LOG_ERR,"Can't get peer name of remote host: %m");
165		fatal(STDERR_FILENO, "Can't get peer name of remote host", 1);
166	}
167	on = 1;
168	if (keepalive &&
169	    setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof (on)) < 0)
170		syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
171	if (no_delay &&
172	    setsockopt(0, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) < 0)
173		syslog(LOG_WARNING, "setsockopt (TCP_NODELAY): %m");
174	if (from.su_family == AF_INET)
175      {
176	on = IPTOS_LOWDELAY;
177	if (setsockopt(0, IPPROTO_IP, IP_TOS, (char *)&on, sizeof(int)) < 0)
178		syslog(LOG_WARNING, "setsockopt (IP_TOS): %m");
179      }
180
181	doit(0, &from);
182	return 0;
183}
184
185int	child;
186int	netf;
187char	line[MAXPATHLEN];
188int	confirmed;
189
190struct winsize win = { 0, 0, 0, 0 };
191
192
193void
194doit(int f, union sockunion *fromp)
195{
196	int master, pid, on = 1;
197	int authenticated = 0;
198	char hostname[2 * MAXHOSTNAMELEN + 1];
199	char nameinfo[2 * INET6_ADDRSTRLEN + 1];
200	char c;
201
202	alarm(60);
203	read(f, &c, 1);
204
205	if (c != 0)
206		exit(1);
207
208	alarm(0);
209
210	realhostname_sa(hostname, sizeof(hostname) - 1,
211			    (struct sockaddr *)fromp, fromp->su_len);
212	/* error check ? */
213	fromp->su_port = ntohs((u_short)fromp->su_port);
214	hostname[sizeof(hostname) - 1] = '\0';
215
216	{
217		if ((fromp->su_family != AF_INET
218#ifdef INET6
219		  && fromp->su_family != AF_INET6
220#endif
221		     ) ||
222		    fromp->su_port >= IPPORT_RESERVED ||
223		    fromp->su_port < IPPORT_RESERVED/2) {
224			getnameinfo((struct sockaddr *)fromp,
225				    fromp->su_len,
226				    nameinfo, sizeof(nameinfo), NULL, 0,
227				    NI_NUMERICHOST);
228			/* error check ? */
229			syslog(LOG_NOTICE, "Connection from %s on illegal port",
230			       nameinfo);
231			fatal(f, "Permission denied", 0);
232		}
233#ifdef IP_OPTIONS
234		if (fromp->su_family == AF_INET)
235	      {
236		u_char optbuf[BUFSIZ/3];
237		socklen_t optsize = sizeof(optbuf);
238		int ipproto, i;
239		struct protoent *ip;
240
241		if ((ip = getprotobyname("ip")) != NULL)
242			ipproto = ip->p_proto;
243		else
244			ipproto = IPPROTO_IP;
245		if (getsockopt(0, ipproto, IP_OPTIONS, (char *)optbuf,
246		    &optsize) == 0 && optsize != 0) {
247			for (i = 0; i < optsize; ) {
248				u_char c = optbuf[i];
249				if (c == IPOPT_LSRR || c == IPOPT_SSRR) {
250					syslog(LOG_NOTICE,
251						"Connection refused from %s with IP option %s",
252						inet_ntoa(fromp->su_sin.sin_addr),
253						c == IPOPT_LSRR ? "LSRR" : "SSRR");
254					exit(1);
255				}
256				if (c == IPOPT_EOL)
257					break;
258				i += (c == IPOPT_NOP) ? 1 : optbuf[i+1];
259			}
260		}
261	      }
262#endif
263		if (do_rlogin(fromp) == 0)
264			authenticated++;
265	}
266	if (confirmed == 0) {
267		write(f, "", 1);
268		confirmed = 1;		/* we sent the null! */
269	}
270	netf = f;
271
272	pid = forkpty(&master, line, NULL, &win);
273	if (pid < 0) {
274		if (errno == ENOENT)
275			fatal(f, "Out of ptys", 0);
276		else
277			fatal(f, "Forkpty", 1);
278	}
279	if (pid == 0) {
280		if (f > 2)	/* f should always be 0, but... */
281			(void) close(f);
282		setup_term(0);
283		 if (*lusername=='-') {
284			syslog(LOG_ERR, "tried to pass user \"%s\" to login",
285			       lusername);
286			fatal(STDERR_FILENO, "invalid user", 0);
287		}
288		if (authenticated) {
289			execl(_PATH_LOGIN, "login", "-p",
290			    "-h", hostname, "-f", lusername, (char *)NULL);
291		} else
292			execl(_PATH_LOGIN, "login", "-p",
293			    "-h", hostname, lusername, (char *)NULL);
294		fatal(STDERR_FILENO, _PATH_LOGIN, 1);
295		/*NOTREACHED*/
296	}
297	ioctl(f, FIONBIO, &on);
298	ioctl(master, FIONBIO, &on);
299	ioctl(master, TIOCPKT, &on);
300	signal(SIGCHLD, cleanup);
301	protocol(f, master);
302	signal(SIGCHLD, SIG_IGN);
303	cleanup(0);
304}
305
306char	magic[2] = { 0377, 0377 };
307char	oobdata[] = {TIOCPKT_WINDOW};
308
309/*
310 * Handle a "control" request (signaled by magic being present)
311 * in the data stream.  For now, we are only willing to handle
312 * window size changes.
313 */
314int
315control(int pty, char *cp, int n)
316{
317	struct winsize w;
318
319	if (n < 4 + (int)sizeof(w) || cp[2] != 's' || cp[3] != 's')
320		return (0);
321	oobdata[0] &= ~TIOCPKT_WINDOW;	/* we know he heard */
322	bcopy(cp+4, (char *)&w, sizeof(w));
323	w.ws_row = ntohs(w.ws_row);
324	w.ws_col = ntohs(w.ws_col);
325	w.ws_xpixel = ntohs(w.ws_xpixel);
326	w.ws_ypixel = ntohs(w.ws_ypixel);
327	(void)ioctl(pty, TIOCSWINSZ, &w);
328	return (4+sizeof (w));
329}
330
331/*
332 * rlogin "protocol" machine.
333 */
334void
335protocol(int f, int p)
336{
337	char pibuf[1024+1], fibuf[1024], *pbp = NULL, *fbp = NULL;
338	int pcc = 0, fcc = 0;
339	int cc, nfd, n;
340	char cntl;
341
342	/*
343	 * Must ignore SIGTTOU, otherwise we'll stop
344	 * when we try and set slave pty's window shape
345	 * (our controlling tty is the master pty).
346	 */
347	(void) signal(SIGTTOU, SIG_IGN);
348	send(f, oobdata, 1, MSG_OOB);	/* indicate new rlogin */
349	if (f > p)
350		nfd = f + 1;
351	else
352		nfd = p + 1;
353	if (nfd > FD_SETSIZE) {
354		syslog(LOG_ERR, "select mask too small, increase FD_SETSIZE");
355		fatal(f, "internal error (select mask too small)", 0);
356	}
357	for (;;) {
358		fd_set ibits, obits, ebits, *omask;
359
360		FD_ZERO(&ebits);
361		FD_ZERO(&ibits);
362		FD_ZERO(&obits);
363		omask = (fd_set *)NULL;
364		if (fcc) {
365			FD_SET(p, &obits);
366			omask = &obits;
367		} else
368			FD_SET(f, &ibits);
369		if (pcc >= 0) {
370			if (pcc) {
371				FD_SET(f, &obits);
372				omask = &obits;
373			} else
374				FD_SET(p, &ibits);
375		}
376		FD_SET(p, &ebits);
377		if ((n = select(nfd, &ibits, omask, &ebits, 0)) < 0) {
378			if (errno == EINTR)
379				continue;
380			fatal(f, "select", 1);
381		}
382		if (n == 0) {
383			/* shouldn't happen... */
384			sleep(5);
385			continue;
386		}
387#define	pkcontrol(c)	((c)&(TIOCPKT_FLUSHWRITE|TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))
388		if (FD_ISSET(p, &ebits)) {
389			cc = read(p, &cntl, 1);
390			if (cc == 1 && pkcontrol(cntl)) {
391				cntl |= oobdata[0];
392				send(f, &cntl, 1, MSG_OOB);
393				if (cntl & TIOCPKT_FLUSHWRITE) {
394					pcc = 0;
395					FD_CLR(p, &ibits);
396				}
397			}
398		}
399		if (FD_ISSET(f, &ibits)) {
400			fcc = read(f, fibuf, sizeof(fibuf));
401			if (fcc < 0 && errno == EWOULDBLOCK)
402				fcc = 0;
403			else {
404				char *cp;
405				int left, n;
406
407				if (fcc <= 0)
408					break;
409				fbp = fibuf;
410
411			top:
412				for (cp = fibuf; cp < fibuf+fcc-1; cp++)
413					if (cp[0] == magic[0] &&
414					    cp[1] == magic[1]) {
415						left = fcc - (cp-fibuf);
416						n = control(p, cp, left);
417						if (n) {
418							left -= n;
419							if (left > 0)
420								bcopy(cp+n, cp, left);
421							fcc -= n;
422							goto top; /* n^2 */
423						}
424					}
425				FD_SET(p, &obits);		/* try write */
426			}
427		}
428
429		if (FD_ISSET(p, &obits) && fcc > 0) {
430			cc = write(p, fbp, fcc);
431			if (cc > 0) {
432				fcc -= cc;
433				fbp += cc;
434			}
435		}
436
437		if (FD_ISSET(p, &ibits)) {
438			pcc = read(p, pibuf, sizeof (pibuf));
439			pbp = pibuf;
440			if (pcc < 0 && errno == EWOULDBLOCK)
441				pcc = 0;
442			else if (pcc <= 0)
443				break;
444			else if (pibuf[0] == 0) {
445				pbp++, pcc--;
446				FD_SET(f, &obits);	/* try write */
447			} else {
448				if (pkcontrol(pibuf[0])) {
449					pibuf[0] |= oobdata[0];
450					send(f, &pibuf[0], 1, MSG_OOB);
451				}
452				pcc = 0;
453			}
454		}
455		if ((FD_ISSET(f, &obits)) && pcc > 0) {
456			cc = write(f, pbp, pcc);
457			if (cc < 0 && errno == EWOULDBLOCK) {
458				/*
459				 * This happens when we try write after read
460				 * from p, but some old kernels balk at large
461				 * writes even when select returns true.
462				 */
463				if (!FD_ISSET(p, &ibits))
464					sleep(5);
465				continue;
466			}
467			if (cc > 0) {
468				pcc -= cc;
469				pbp += cc;
470			}
471		}
472	}
473}
474
475void
476cleanup(int signo __unused)
477{
478
479	shutdown(netf, SHUT_RDWR);
480	exit(1);
481}
482
483void
484fatal(int f, char *msg, int syserr)
485{
486	int len;
487	char buf[BUFSIZ], *bp = buf;
488
489	/*
490	 * Prepend binary one to message if we haven't sent
491	 * the magic null as confirmation.
492	 */
493	if (!confirmed)
494		*bp++ = '\01';		/* error indicator */
495	if (syserr)
496		len = snprintf(bp, sizeof(buf), "rlogind: %s: %s.\r\n",
497		    msg, strerror(errno));
498	else
499		len = snprintf(bp, sizeof(buf), "rlogind: %s.\r\n", msg);
500	if (len < 0)
501		len = 0;
502	(void) write(f, buf, bp + len - buf);
503	exit(1);
504}
505
506int
507do_rlogin(union sockunion *dest)
508{
509
510	getstr(rusername, sizeof(rusername), "remuser too long");
511	getstr(lusername, sizeof(lusername), "locuser too long");
512	getstr(term+ENVSIZE, sizeof(term)-ENVSIZE, "Terminal type too long");
513
514	pwd = getpwnam(lusername);
515	if (pwd == NULL)
516		return (-1);
517	/* XXX why don't we syslog() failure? */
518
519	return (iruserok_sa(dest, dest->su_len, pwd->pw_uid == 0, rusername,
520			    lusername));
521}
522
523void
524getstr(char *buf, int cnt, char *errmsg)
525{
526	char c;
527
528	do {
529		if (read(STDIN_FILENO, &c, 1) != 1)
530			exit(1);
531		if (--cnt < 0)
532			fatal(STDOUT_FILENO, errmsg, 0);
533		*buf++ = c;
534	} while (c != 0);
535}
536
537extern	char **environ;
538
539void
540setup_term(int fd)
541{
542	char *cp;
543	char *speed;
544	struct termios tt, def;
545
546	cp = strchr(term + ENVSIZE, '/');
547#ifndef notyet
548	tcgetattr(fd, &tt);
549	if (cp) {
550		*cp++ = '\0';
551		speed = cp;
552		cp = strchr(speed, '/');
553		if (cp)
554			*cp++ = '\0';
555		cfsetspeed(&tt, atoi(speed));
556	}
557
558	cfmakesane(&def);
559	tt.c_iflag = def.c_iflag;
560	tt.c_oflag = def.c_oflag;
561	tt.c_lflag = def.c_lflag;
562	tcsetattr(fd, TCSAFLUSH, &tt);
563#else
564	if (cp) {
565		*cp++ = '\0';
566		speed = cp;
567		cp = strchr(speed, '/');
568		if (cp)
569			*cp++ = '\0';
570		tcgetattr(fd, &tt);
571		cfsetspeed(&tt, atoi(speed));
572		tcsetattr(fd, TCSAFLUSH, &tt);
573	}
574#endif
575
576	env[0] = term;
577	env[1] = 0;
578	environ = env;
579}
580
581void
582usage(void)
583{
584	syslog(LOG_ERR, "usage: rlogind [-" ARGSTR "]");
585}
586