[gssapi-openssh.git] / openssh / sshpty.c

/* $OpenBSD: sshpty.c,v 1.28 2007/09/11 23:49:09 stevesk Exp $ */
/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * Allocating a pseudo-terminal, and making it the controlling tty.
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 */

#include "includes.h"

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <signal.h>

#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#ifdef HAVE_PATHS_H
# include <paths.h>
#endif
#include <pwd.h>
#include <stdarg.h>
#include <string.h>
#include <termios.h>
#ifdef HAVE_UTIL_H
# include <util.h>
#endif
#include <unistd.h>

#include "sshpty.h"
#include "log.h"
#include "misc.h"

#ifdef HAVE_PTY_H
# include <pty.h>
#endif

#ifndef O_NOCTTY
#define O_NOCTTY 0
#endif

#ifdef __APPLE__
# include <AvailabilityMacros.h>
# if (MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5)
#  define __APPLE_PRIVPTY__
# endif
#endif

/*
 * Allocates and opens a pty.  Returns 0 if no pty could be allocated, or
 * nonzero if a pty was successfully allocated.  On success, open file
 * descriptors for the pty and tty sides and the name of the tty side are
 * returned (the buffer must be able to hold at least 64 characters).
 */

int
pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, size_t namebuflen)
{
	/* openpty(3) exists in OSF/1 and some other os'es */
	char *name;
	int i;

	i = openpty(ptyfd, ttyfd, NULL, NULL, NULL);
	if (i < 0) {
		error("openpty: %.100s", strerror(errno));
		return 0;
	}
	name = ttyname(*ttyfd);
	if (!name)
		fatal("openpty returns device for which ttyname fails.");

	strlcpy(namebuf, name, namebuflen);	/* possible truncation */
	return 1;
}

/* Releases the tty.  Its ownership is returned to root, and permissions to 0666. */

void
pty_release(const char *tty)
{
#ifndef __APPLE_PRIVPTY__
	if (chown(tty, (uid_t) 0, (gid_t) 0) < 0)
		error("chown %.100s 0 0 failed: %.100s", tty, strerror(errno));
	if (chmod(tty, (mode_t) 0666) < 0)
		error("chmod %.100s 0666 failed: %.100s", tty, strerror(errno));
#endif /* __APPLE_PRIVPTY__ */
}

/* Makes the tty the process's controlling tty and sets it to sane modes. */

void
pty_make_controlling_tty(int *ttyfd, const char *tty)
{
	int fd;
#ifdef USE_VHANGUP
	void *old;
#endif /* USE_VHANGUP */

#ifdef _UNICOS
	if (setsid() < 0)
		error("setsid: %.100s", strerror(errno));

	fd = open(tty, O_RDWR|O_NOCTTY);
	if (fd != -1) {
		signal(SIGHUP, SIG_IGN);
		ioctl(fd, TCVHUP, (char *)NULL);
		signal(SIGHUP, SIG_DFL);
		setpgid(0, 0);
		close(fd);
	} else {
		error("Failed to disconnect from controlling tty.");
	}

	debug("Setting controlling tty using TCSETCTTY.");
	ioctl(*ttyfd, TCSETCTTY, NULL);
	fd = open("/dev/tty", O_RDWR);
	if (fd < 0)
		error("%.100s: %.100s", tty, strerror(errno));
	close(*ttyfd);
	*ttyfd = fd;
#else /* _UNICOS */

	/* First disconnect from the old controlling tty. */
#ifdef TIOCNOTTY
	fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
	if (fd >= 0) {
		(void) ioctl(fd, TIOCNOTTY, NULL);
		close(fd);
	}
#endif /* TIOCNOTTY */
	if (setsid() < 0)
		error("setsid: %.100s", strerror(errno));

	/*
	 * Verify that we are successfully disconnected from the controlling
	 * tty.
	 */
	fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
	if (fd >= 0) {
		error("Failed to disconnect from controlling tty.");
		close(fd);
	}
	/* Make it our controlling tty. */
#ifdef TIOCSCTTY
	debug("Setting controlling tty using TIOCSCTTY.");
	if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0)
		error("ioctl(TIOCSCTTY): %.100s", strerror(errno));
#endif /* TIOCSCTTY */
#ifdef NEED_SETPGRP
	if (setpgrp(0,0) < 0)
		error("SETPGRP %s",strerror(errno));
#endif /* NEED_SETPGRP */
#ifdef USE_VHANGUP
	old = signal(SIGHUP, SIG_IGN);
	vhangup();
	signal(SIGHUP, old);
#endif /* USE_VHANGUP */
	fd = open(tty, O_RDWR);
	if (fd < 0) {
		error("%.100s: %.100s", tty, strerror(errno));
	} else {
#ifdef USE_VHANGUP
		close(*ttyfd);
		*ttyfd = fd;
#else /* USE_VHANGUP */
		close(fd);
#endif /* USE_VHANGUP */
	}
	/* Verify that we now have a controlling tty. */
	fd = open(_PATH_TTY, O_WRONLY);
	if (fd < 0)
		error("open /dev/tty failed - could not set controlling tty: %.100s",
		    strerror(errno));
	else
		close(fd);
#endif /* _UNICOS */
}

/* Changes the window size associated with the pty. */

void
pty_change_window_size(int ptyfd, u_int row, u_int col,
	u_int xpixel, u_int ypixel)
{
	struct winsize w;

	/* may truncate u_int -> u_short */
	w.ws_row = row;
	w.ws_col = col;
	w.ws_xpixel = xpixel;
	w.ws_ypixel = ypixel;
	(void) ioctl(ptyfd, TIOCSWINSZ, &w);
}

void
pty_setowner(struct passwd *pw, const char *tty)
{
	struct group *grp;
	gid_t gid;
	mode_t mode;
	struct stat st;

	/* Determine the group to make the owner of the tty. */
	grp = getgrnam("tty");
	if (grp) {
		gid = grp->gr_gid;
		mode = S_IRUSR | S_IWUSR | S_IWGRP;
	} else {
		gid = pw->pw_gid;
		mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH;
	}

	/*
	 * Change owner and mode of the tty as required.
	 * Warn but continue if filesystem is read-only and the uids match/
	 * tty is owned by root.
	 */
	if (stat(tty, &st))
		fatal("stat(%.100s) failed: %.100s", tty,
		    strerror(errno));

#ifdef WITH_SELINUX
	ssh_selinux_setup_pty(pw->pw_name, tty);
#endif

	if (st.st_uid != pw->pw_uid || st.st_gid != gid) {
		if (chown(tty, pw->pw_uid, gid) < 0) {
			if (errno == EROFS &&
			    (st.st_uid == pw->pw_uid || st.st_uid == 0))
				debug("chown(%.100s, %u, %u) failed: %.100s",
				    tty, (u_int)pw->pw_uid, (u_int)gid,
				    strerror(errno));
			else
				fatal("chown(%.100s, %u, %u) failed: %.100s",
				    tty, (u_int)pw->pw_uid, (u_int)gid,
				    strerror(errno));
		}
	}

	if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) {
		if (chmod(tty, mode) < 0) {
			if (errno == EROFS &&
			    (st.st_mode & (S_IRGRP | S_IROTH)) == 0)
				debug("chmod(%.100s, 0%o) failed: %.100s",
				    tty, (u_int)mode, strerror(errno));
			else
				fatal("chmod(%.100s, 0%o) failed: %.100s",
				    tty, (u_int)mode, strerror(errno));
		}
	}
}
Commit	Line	Data
47686178	1	/* $OpenBSD: sshpty.c,v 1.28 2007/09/11 23:49:09 stevesk Exp $ */
3c0ef626	2	/*
	3	* Author: Tatu Ylonen <ylo@cs.hut.fi>
	4	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	5	* All rights reserved
	6	* Allocating a pseudo-terminal, and making it the controlling tty.
	7	*
	8	* As far as I am concerned, the code I have written for this software
	9	* can be used freely for any purpose. Any derived versions of this
	10	* software must be clearly marked as such, and if the derived work is
	11	* incompatible with the protocol description in the RFC file, it must be
	12	* called by a name other than "ssh" or "Secure Shell".
	13	*/
	14
	15	#include "includes.h"
3c0ef626	16
9108f8d9	17	#include <sys/types.h>
	18	#include <sys/ioctl.h>
	19	#include <sys/stat.h>
	20	#include <signal.h>
	21
	22	#include <errno.h>
	23	#include <fcntl.h>
	24	#include <grp.h>
	25	#ifdef HAVE_PATHS_H
	26	# include <paths.h>
	27	#endif
	28	#include <pwd.h>
	29	#include <stdarg.h>
	30	#include <string.h>
	31	#include <termios.h>
3c0ef626	32	#ifdef HAVE_UTIL_H
3c0ef626	33	# include <util.h>
9108f8d9	34	#endif
9108f8d9	35	#include <unistd.h>
3c0ef626	36
	37	#include "sshpty.h"
	38	#include "log.h"
	39	#include "misc.h"
	40
3c0ef626	41	#ifdef HAVE_PTY_H
	42	# include <pty.h>
	43	#endif
3c0ef626	44
	45	#ifndef O_NOCTTY
	46	#define O_NOCTTY 0
	47	#endif
	48
91d9cdd3	49	#ifdef __APPLE__
	50	# include <AvailabilityMacros.h>
	51	# if (MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5)
	52	# define __APPLE_PRIVPTY__
	53	# endif
	54	#endif
	55
3c0ef626	56	/*
	57	* Allocates and opens a pty. Returns 0 if no pty could be allocated, or
	58	* nonzero if a pty was successfully allocated. On success, open file
	59	* descriptors for the pty and tty sides and the name of the tty side are
	60	* returned (the buffer must be able to hold at least 64 characters).
	61	*/
	62
	63	int
9108f8d9	64	pty_allocate(int ptyfd, int ttyfd, char *namebuf, size_t namebuflen)
3c0ef626	65	{
3c0ef626	66	/* openpty(3) exists in OSF/1 and some other os'es */
	67	char *name;
	68	int i;
	69
	70	i = openpty(ptyfd, ttyfd, NULL, NULL, NULL);
	71	if (i < 0) {
	72	error("openpty: %.100s", strerror(errno));
	73	return 0;
	74	}
	75	name = ttyname(*ttyfd);
	76	if (!name)
	77	fatal("openpty returns device for which ttyname fails.");
	78
	79	strlcpy(namebuf, name, namebuflen); /* possible truncation */
	80	return 1;
3c0ef626	81	}
	82
	83	/* Releases the tty. Its ownership is returned to root, and permissions to 0666. */
	84
	85	void
c9f39d2c	86	pty_release(const char *tty)
3c0ef626	87	{
91d9cdd3	88	#ifndef __APPLE_PRIVPTY__
c9f39d2c	89	if (chown(tty, (uid_t) 0, (gid_t) 0) < 0)
	90	error("chown %.100s 0 0 failed: %.100s", tty, strerror(errno));
	91	if (chmod(tty, (mode_t) 0666) < 0)
	92	error("chmod %.100s 0666 failed: %.100s", tty, strerror(errno));
91d9cdd3	93	#endif /* __APPLE_PRIVPTY__ */
3c0ef626	94	}
3c0ef626	95
0fff78ff	96	/* Makes the tty the process's controlling tty and sets it to sane modes. */
3c0ef626	97
3c0ef626	98	void
c9f39d2c	99	pty_make_controlling_tty(int ttyfd, const char tty)
3c0ef626	100	{
	101	int fd;
	102	#ifdef USE_VHANGUP
	103	void *old;
	104	#endif /* USE_VHANGUP */
	105
41b2f314	106	#ifdef _UNICOS
3c0ef626	107	if (setsid() < 0)
	108	error("setsid: %.100s", strerror(errno));
	109
c9f39d2c	110	fd = open(tty, O_RDWR\|O_NOCTTY);
3c0ef626	111	if (fd != -1) {
0fff78ff	112	signal(SIGHUP, SIG_IGN);
3c0ef626	113	ioctl(fd, TCVHUP, (char *)NULL);
0fff78ff	114	signal(SIGHUP, SIG_DFL);
3c0ef626	115	setpgid(0, 0);
	116	close(fd);
	117	} else {
	118	error("Failed to disconnect from controlling tty.");
	119	}
	120
	121	debug("Setting controlling tty using TCSETCTTY.");
	122	ioctl(*ttyfd, TCSETCTTY, NULL);
	123	fd = open("/dev/tty", O_RDWR);
	124	if (fd < 0)
c9f39d2c	125	error("%.100s: %.100s", tty, strerror(errno));
3c0ef626	126	close(*ttyfd);
f5799ae1	127	*ttyfd = fd;
41b2f314	128	#else /* _UNICOS */
3c0ef626	129
	130	/* First disconnect from the old controlling tty. */
	131	#ifdef TIOCNOTTY
	132	fd = open(_PATH_TTY, O_RDWR \| O_NOCTTY);
	133	if (fd >= 0) {
	134	(void) ioctl(fd, TIOCNOTTY, NULL);
	135	close(fd);
	136	}
	137	#endif /* TIOCNOTTY */
	138	if (setsid() < 0)
	139	error("setsid: %.100s", strerror(errno));
	140
	141	/*
	142	* Verify that we are successfully disconnected from the controlling
	143	* tty.
	144	*/
	145	fd = open(_PATH_TTY, O_RDWR \| O_NOCTTY);
	146	if (fd >= 0) {
	147	error("Failed to disconnect from controlling tty.");
	148	close(fd);
	149	}
	150	/* Make it our controlling tty. */
	151	#ifdef TIOCSCTTY
	152	debug("Setting controlling tty using TIOCSCTTY.");
	153	if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0)
	154	error("ioctl(TIOCSCTTY): %.100s", strerror(errno));
	155	#endif /* TIOCSCTTY */
665a873d	156	#ifdef NEED_SETPGRP
3c0ef626	157	if (setpgrp(0,0) < 0)
3c0ef626	158	error("SETPGRP %s",strerror(errno));
665a873d	159	#endif /* NEED_SETPGRP */
3c0ef626	160	#ifdef USE_VHANGUP
0fff78ff	161	old = signal(SIGHUP, SIG_IGN);
3c0ef626	162	vhangup();
0fff78ff	163	signal(SIGHUP, old);
3c0ef626	164	#endif /* USE_VHANGUP */
c9f39d2c	165	fd = open(tty, O_RDWR);
3c0ef626	166	if (fd < 0) {
c9f39d2c	167	error("%.100s: %.100s", tty, strerror(errno));
3c0ef626	168	} else {
	169	#ifdef USE_VHANGUP
	170	close(*ttyfd);
	171	*ttyfd = fd;
	172	#else /* USE_VHANGUP */
	173	close(fd);
	174	#endif /* USE_VHANGUP */
	175	}
	176	/* Verify that we now have a controlling tty. */
	177	fd = open(_PATH_TTY, O_WRONLY);
	178	if (fd < 0)
	179	error("open /dev/tty failed - could not set controlling tty: %.100s",
e9a17296	180	strerror(errno));
cdd66111	181	else
3c0ef626	182	close(fd);
41b2f314	183	#endif /* _UNICOS */
3c0ef626	184	}
	185
	186	/* Changes the window size associated with the pty. */
	187
	188	void
9108f8d9	189	pty_change_window_size(int ptyfd, u_int row, u_int col,
9108f8d9	190	u_int xpixel, u_int ypixel)
3c0ef626	191	{
3c0ef626	192	struct winsize w;
680cee3b	193
9108f8d9	194	/* may truncate u_int -> u_short */
3c0ef626	195	w.ws_row = row;
	196	w.ws_col = col;
	197	w.ws_xpixel = xpixel;
	198	w.ws_ypixel = ypixel;
	199	(void) ioctl(ptyfd, TIOCSWINSZ, &w);
	200	}
	201
	202	void
c9f39d2c	203	pty_setowner(struct passwd pw, const char tty)
3c0ef626	204	{
	205	struct group *grp;
	206	gid_t gid;
	207	mode_t mode;
	208	struct stat st;
	209
	210	/* Determine the group to make the owner of the tty. */
	211	grp = getgrnam("tty");
	212	if (grp) {
	213	gid = grp->gr_gid;
	214	mode = S_IRUSR \| S_IWUSR \| S_IWGRP;
	215	} else {
	216	gid = pw->pw_gid;
	217	mode = S_IRUSR \| S_IWUSR \| S_IWGRP \| S_IWOTH;
	218	}
	219
	220	/*
	221	* Change owner and mode of the tty as required.
	222	* Warn but continue if filesystem is read-only and the uids match/
	223	* tty is owned by root.
	224	*/
c9f39d2c	225	if (stat(tty, &st))
c9f39d2c	226	fatal("stat(%.100s) failed: %.100s", tty,
3c0ef626	227	strerror(errno));
3c0ef626	228
9108f8d9	229	#ifdef WITH_SELINUX
	230	ssh_selinux_setup_pty(pw->pw_name, tty);
	231	#endif
	232
3c0ef626	233	if (st.st_uid != pw->pw_uid \|\| st.st_gid != gid) {
c9f39d2c	234	if (chown(tty, pw->pw_uid, gid) < 0) {
e9a17296	235	if (errno == EROFS &&
680cee3b	236	(st.st_uid == pw->pw_uid \|\| st.st_uid == 0))
6a9b3198	237	debug("chown(%.100s, %u, %u) failed: %.100s",
c9f39d2c	238	tty, (u_int)pw->pw_uid, (u_int)gid,
e9a17296	239	strerror(errno));
3c0ef626	240	else
680cee3b	241	fatal("chown(%.100s, %u, %u) failed: %.100s",
c9f39d2c	242	tty, (u_int)pw->pw_uid, (u_int)gid,
e9a17296	243	strerror(errno));
3c0ef626	244	}
	245	}
	246
	247	if ((st.st_mode & (S_IRWXU\|S_IRWXG\|S_IRWXO)) != mode) {
c9f39d2c	248	if (chmod(tty, mode) < 0) {
3c0ef626	249	if (errno == EROFS &&
3c0ef626	250	(st.st_mode & (S_IRGRP \| S_IROTH)) == 0)
6a9b3198	251	debug("chmod(%.100s, 0%o) failed: %.100s",
c9f39d2c	252	tty, (u_int)mode, strerror(errno));
3c0ef626	253	else
3c0ef626	254	fatal("chmod(%.100s, 0%o) failed: %.100s",
c9f39d2c	255	tty, (u_int)mode, strerror(errno));
3c0ef626	256	}
	257	}
	258	}