1/*
2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 *                    All rights reserved
5 * Allocating a pseudo-terminal, and making it the controlling tty.
6 *
7 * As far as I am concerned, the code I have written for this software
8 * can be used freely for any purpose.  Any derived versions of this
9 * software must be clearly marked as such, and if the derived work is
10 * incompatible with the protocol description in the RFC file, it must be
11 * called by a name other than "ssh" or "Secure Shell".
12 */
13
14#include "includes.h"
15RCSID("$OpenBSD: sshpty.c,v 1.7 2002/06/24 17:57:20 deraadt Exp $");
16
17#pragma ident	"%Z%%M%	%I%	%E% SMI"
18
19#ifdef HAVE_UTIL_H
20# include <util.h>
21#endif /* HAVE_UTIL_H */
22
23#include "sshpty.h"
24#include "log.h"
25#include "misc.h"
26
27/* Pty allocated with _getpty gets broken if we do I_PUSH:es to it. */
28#if defined(HAVE__GETPTY) || defined(HAVE_OPENPTY)
29#undef HAVE_DEV_PTMX
30#endif
31
32#ifdef HAVE_PTY_H
33# include <pty.h>
34#endif
35#if defined(HAVE_DEV_PTMX) && defined(HAVE_SYS_STROPTS_H)
36# include <sys/stropts.h>
37#endif
38
39#ifndef O_NOCTTY
40#define O_NOCTTY 0
41#endif
42
43/*
44 * Allocates and opens a pty.  Returns 0 if no pty could be allocated, or
45 * nonzero if a pty was successfully allocated.  On success, open file
46 * descriptors for the pty and tty sides and the name of the tty side are
47 * returned (the buffer must be able to hold at least 64 characters).
48 */
49
50int
51pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, int namebuflen)
52{
53#if defined(HAVE_OPENPTY) || defined(BSD4_4)
54	/* openpty(3) exists in OSF/1 and some other os'es */
55	char *name;
56	int i;
57
58	i = openpty(ptyfd, ttyfd, NULL, NULL, NULL);
59	if (i < 0) {
60		error("openpty: %.100s", strerror(errno));
61		return 0;
62	}
63	name = ttyname(*ttyfd);
64	if (!name)
65		fatal("openpty returns device for which ttyname fails.");
66
67	strlcpy(namebuf, name, namebuflen);	/* possible truncation */
68	return 1;
69#else /* HAVE_OPENPTY */
70#ifdef HAVE__GETPTY
71	/*
72	 * _getpty(3) exists in SGI Irix 4.x, 5.x & 6.x -- it generates more
73	 * pty's automagically when needed
74	 */
75	char *slave;
76
77	slave = _getpty(ptyfd, O_RDWR, 0622, 0);
78	if (slave == NULL) {
79		error("_getpty: %.100s", strerror(errno));
80		return 0;
81	}
82	strlcpy(namebuf, slave, namebuflen);
83	/* Open the slave side. */
84	*ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
85	if (*ttyfd < 0) {
86		error("%.200s: %.100s", namebuf, strerror(errno));
87		close(*ptyfd);
88		return 0;
89	}
90	return 1;
91#else /* HAVE__GETPTY */
92#if defined(HAVE_DEV_PTMX)
93	/*
94	 * This code is used e.g. on Solaris 2.x.  (Note that Solaris 2.3
95	 * also has bsd-style ptys, but they simply do not work.)
96	 */
97	int ptm;
98	char *pts;
99	mysig_t old_signal;
100
101	ptm = open("/dev/ptmx", O_RDWR | O_NOCTTY);
102	if (ptm < 0) {
103		error("/dev/ptmx: %.100s", strerror(errno));
104		return 0;
105	}
106	old_signal = mysignal(SIGCHLD, SIG_DFL);
107	if (grantpt(ptm) < 0) {
108		error("grantpt: %.100s", strerror(errno));
109		return 0;
110	}
111	mysignal(SIGCHLD, old_signal);
112	if (unlockpt(ptm) < 0) {
113		error("unlockpt: %.100s", strerror(errno));
114		return 0;
115	}
116	pts = ptsname(ptm);
117	if (pts == NULL)
118		error("Slave pty side name could not be obtained.");
119	strlcpy(namebuf, pts, namebuflen);
120	*ptyfd = ptm;
121
122	/* Open the slave side. */
123	*ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
124	if (*ttyfd < 0) {
125		error("%.100s: %.100s", namebuf, strerror(errno));
126		close(*ptyfd);
127		return 0;
128	}
129#ifndef HAVE_CYGWIN
130	/*
131	 * Push the appropriate streams modules, as described in Solaris pts(7).
132	 * HP-UX pts(7) doesn't have ttcompat module.
133	 */
134	if (ioctl(*ttyfd, I_PUSH, "ptem") < 0)
135		error("ioctl I_PUSH ptem: %.100s", strerror(errno));
136	if (ioctl(*ttyfd, I_PUSH, "ldterm") < 0)
137		error("ioctl I_PUSH ldterm: %.100s", strerror(errno));
138#ifndef __hpux
139	if (ioctl(*ttyfd, I_PUSH, "ttcompat") < 0)
140		error("ioctl I_PUSH ttcompat: %.100s", strerror(errno));
141#endif
142#endif
143	return 1;
144#else /* HAVE_DEV_PTMX */
145#ifdef HAVE_DEV_PTS_AND_PTC
146	/* AIX-style pty code. */
147	const char *name;
148
149	*ptyfd = open("/dev/ptc", O_RDWR | O_NOCTTY);
150	if (*ptyfd < 0) {
151		error("Could not open /dev/ptc: %.100s", strerror(errno));
152		return 0;
153	}
154	name = ttyname(*ptyfd);
155	if (!name)
156		fatal("Open of /dev/ptc returns device for which ttyname fails.");
157	strlcpy(namebuf, name, namebuflen);
158	*ttyfd = open(name, O_RDWR | O_NOCTTY);
159	if (*ttyfd < 0) {
160		error("Could not open pty slave side %.100s: %.100s",
161		    name, strerror(errno));
162		close(*ptyfd);
163		return 0;
164	}
165	return 1;
166#else /* HAVE_DEV_PTS_AND_PTC */
167#ifdef _UNICOS
168	char buf[64];
169	int i;
170	int highpty;
171
172#ifdef _SC_CRAY_NPTY
173	highpty = sysconf(_SC_CRAY_NPTY);
174	if (highpty == -1)
175		highpty = 128;
176#else
177	highpty = 128;
178#endif
179
180	for (i = 0; i < highpty; i++) {
181		snprintf(buf, sizeof(buf), "/dev/pty/%03d", i);
182		*ptyfd = open(buf, O_RDWR|O_NOCTTY);
183		if (*ptyfd < 0)
184			continue;
185		snprintf(namebuf, namebuflen, "/dev/ttyp%03d", i);
186		/* Open the slave side. */
187		*ttyfd = open(namebuf, O_RDWR|O_NOCTTY);
188		if (*ttyfd < 0) {
189			error("%.100s: %.100s", namebuf, strerror(errno));
190			close(*ptyfd);
191			return 0;
192		}
193		return 1;
194	}
195	return 0;
196#else
197	/* BSD-style pty code. */
198	char buf[64];
199	int i;
200	const char *ptymajors = "pqrstuvwxyzabcdefghijklmnoABCDEFGHIJKLMNOPQRSTUVWXYZ";
201	const char *ptyminors = "0123456789abcdef";
202	int num_minors = strlen(ptyminors);
203	int num_ptys = strlen(ptymajors) * num_minors;
204	struct termios tio;
205
206	for (i = 0; i < num_ptys; i++) {
207		snprintf(buf, sizeof buf, "/dev/pty%c%c", ptymajors[i / num_minors],
208			 ptyminors[i % num_minors]);
209		snprintf(namebuf, namebuflen, "/dev/tty%c%c",
210		    ptymajors[i / num_minors], ptyminors[i % num_minors]);
211
212		*ptyfd = open(buf, O_RDWR | O_NOCTTY);
213		if (*ptyfd < 0) {
214			/* Try SCO style naming */
215			snprintf(buf, sizeof buf, "/dev/ptyp%d", i);
216			snprintf(namebuf, namebuflen, "/dev/ttyp%d", i);
217			*ptyfd = open(buf, O_RDWR | O_NOCTTY);
218			if (*ptyfd < 0)
219				continue;
220		}
221
222		/* Open the slave side. */
223		*ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
224		if (*ttyfd < 0) {
225			error("%.100s: %.100s", namebuf, strerror(errno));
226			close(*ptyfd);
227			return 0;
228		}
229		/* set tty modes to a sane state for broken clients */
230		if (tcgetattr(*ptyfd, &tio) < 0)
231			log("Getting tty modes for pty failed: %.100s", strerror(errno));
232		else {
233			tio.c_lflag |= (ECHO | ISIG | ICANON);
234			tio.c_oflag |= (OPOST | ONLCR);
235			tio.c_iflag |= ICRNL;
236
237			/* Set the new modes for the terminal. */
238			if (tcsetattr(*ptyfd, TCSANOW, &tio) < 0)
239				log("Setting tty modes for pty failed: %.100s", strerror(errno));
240		}
241
242		return 1;
243	}
244	return 0;
245#endif /* CRAY */
246#endif /* HAVE_DEV_PTS_AND_PTC */
247#endif /* HAVE_DEV_PTMX */
248#endif /* HAVE__GETPTY */
249#endif /* HAVE_OPENPTY */
250}
251
252/* Releases the tty.  Its ownership is returned to root, and permissions to 0666. */
253
254void
255pty_release(const char *ttyname)
256{
257	if (chown(ttyname, (uid_t) 0, (gid_t) 0) < 0)
258		error("chown %.100s 0 0 failed: %.100s", ttyname, strerror(errno));
259	if (chmod(ttyname, (mode_t) 0666) < 0)
260		error("chmod %.100s 0666 failed: %.100s", ttyname, strerror(errno));
261}
262
263/* Makes the tty the processes controlling tty and sets it to sane modes. */
264
265void
266pty_make_controlling_tty(int *ttyfd, const char *ttyname)
267{
268	int fd;
269#ifdef USE_VHANGUP
270	void *old;
271#endif /* USE_VHANGUP */
272
273#ifdef _UNICOS
274	if (setsid() < 0)
275		error("setsid: %.100s", strerror(errno));
276
277	fd = open(ttyname, O_RDWR|O_NOCTTY);
278	if (fd != -1) {
279		mysignal(SIGHUP, SIG_IGN);
280		ioctl(fd, TCVHUP, (char *)NULL);
281		mysignal(SIGHUP, SIG_DFL);
282		setpgid(0, 0);
283		close(fd);
284	} else {
285		error("Failed to disconnect from controlling tty.");
286	}
287
288	debug("Setting controlling tty using TCSETCTTY.");
289	ioctl(*ttyfd, TCSETCTTY, NULL);
290	fd = open("/dev/tty", O_RDWR);
291	if (fd < 0)
292		error("%.100s: %.100s", ttyname, strerror(errno));
293	close(*ttyfd);
294	*ttyfd = fd;
295#else /* _UNICOS */
296
297	/* First disconnect from the old controlling tty. */
298#ifdef TIOCNOTTY
299	fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
300	if (fd >= 0) {
301		(void) ioctl(fd, TIOCNOTTY, NULL);
302		close(fd);
303	}
304#endif /* TIOCNOTTY */
305	if (setsid() < 0)
306		error("setsid: %.100s", strerror(errno));
307
308	/*
309	 * Verify that we are successfully disconnected from the controlling
310	 * tty.
311	 */
312	fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
313	if (fd >= 0) {
314		error("Failed to disconnect from controlling tty.");
315		close(fd);
316	}
317	/* Make it our controlling tty. */
318#ifdef TIOCSCTTY
319	debug("Setting controlling tty using TIOCSCTTY.");
320	if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0)
321		error("ioctl(TIOCSCTTY): %.100s", strerror(errno));
322#endif /* TIOCSCTTY */
323#ifdef HAVE_NEWS4
324	if (setpgrp(0,0) < 0)
325		error("SETPGRP %s",strerror(errno));
326#endif /* HAVE_NEWS4 */
327#ifdef USE_VHANGUP
328	old = mysignal(SIGHUP, SIG_IGN);
329	vhangup();
330	mysignal(SIGHUP, old);
331#endif /* USE_VHANGUP */
332	fd = open(ttyname, O_RDWR);
333	if (fd < 0) {
334		error("%.100s: %.100s", ttyname, strerror(errno));
335	} else {
336#ifdef USE_VHANGUP
337		close(*ttyfd);
338		*ttyfd = fd;
339#else /* USE_VHANGUP */
340		close(fd);
341#endif /* USE_VHANGUP */
342	}
343	/* Verify that we now have a controlling tty. */
344	fd = open(_PATH_TTY, O_WRONLY);
345	if (fd < 0)
346		error("open /dev/tty failed - could not set controlling tty: %.100s",
347		    strerror(errno));
348	else
349		close(fd);
350#endif /* _UNICOS */
351}
352
353/* Changes the window size associated with the pty. */
354
355void
356pty_change_window_size(int ptyfd, int row, int col,
357	int xpixel, int ypixel)
358{
359	struct winsize w;
360
361	w.ws_row = row;
362	w.ws_col = col;
363	w.ws_xpixel = xpixel;
364	w.ws_ypixel = ypixel;
365	(void) ioctl(ptyfd, TIOCSWINSZ, &w);
366}
367
368void
369pty_setowner(struct passwd *pw, const char *ttyname)
370{
371	struct group *grp;
372	gid_t gid;
373	mode_t mode;
374	struct stat st;
375
376	/* Determine the group to make the owner of the tty. */
377	grp = getgrnam("tty");
378	if (grp) {
379		gid = grp->gr_gid;
380		mode = S_IRUSR | S_IWUSR | S_IWGRP;
381	} else {
382		gid = pw->pw_gid;
383		mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH;
384	}
385
386	/*
387	 * Change owner and mode of the tty as required.
388	 * Warn but continue if filesystem is read-only and the uids match/
389	 * tty is owned by root.
390	 */
391	if (stat(ttyname, &st))
392		fatal("stat(%.100s) failed: %.100s", ttyname,
393		    strerror(errno));
394
395	if (st.st_uid != pw->pw_uid || st.st_gid != gid) {
396		if (chown(ttyname, pw->pw_uid, gid) < 0) {
397			if (errno == EROFS &&
398			    (st.st_uid == pw->pw_uid || st.st_uid == 0))
399				error("chown(%.100s, %u, %u) failed: %.100s",
400				    ttyname, (u_int)pw->pw_uid, (u_int)gid,
401				    strerror(errno));
402			else
403				fatal("chown(%.100s, %u, %u) failed: %.100s",
404				    ttyname, (u_int)pw->pw_uid, (u_int)gid,
405				    strerror(errno));
406		}
407	}
408
409	if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) {
410		if (chmod(ttyname, mode) < 0) {
411			if (errno == EROFS &&
412			    (st.st_mode & (S_IRGRP | S_IROTH)) == 0)
413				error("chmod(%.100s, 0%o) failed: %.100s",
414				    ttyname, (int)mode, strerror(errno));
415			else
416				fatal("chmod(%.100s, 0%o) failed: %.100s",
417				    ttyname, (int)mode, strerror(errno));
418		}
419	}
420}
421