sshpty.c - third_party/openssh-portable - Git at Google

 /* $OpenBSD: sshpty.c,v 1.31 2016/11/29 03:54:50 dtucker 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)
 {
 #if !defined(__APPLE_PRIVPTY__) && !defined(HAVE_OPENPTY)
 	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__ && !HAVE_OPENPTY */
 }

 /* 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 _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 */
 	fd = open(tty, O_RDWR);
 	if (fd < 0)
 		error("%.100s: %.100s", tty, strerror(errno));
 	else
 		close(fd);

 	/* 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");
 	gid = (grp != NULL) ? grp->gr_gid : pw->pw_gid;
 	mode = (grp != NULL) ? 0620 : 0600;

 	/*
 	 * 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));
 		}
 	}
 }

 /* Disconnect from the controlling tty. */
 void
 disconnect_controlling_tty(void)
 {
 #ifdef TIOCNOTTY
 	int fd;

 	if ((fd = open(_PATH_TTY, O_RDWR | O_NOCTTY)) >= 0) {
 		(void) ioctl(fd, TIOCNOTTY, NULL);
 		close(fd);
 	}
 #endif /* TIOCNOTTY */
 }
	/* $OpenBSD: sshpty.c,v 1.31 2016/11/29 03:54:50 dtucker 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)
	{
	#if !defined(__APPLE_PRIVPTY__) && !defined(HAVE_OPENPTY)
	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__ && !HAVE_OPENPTY */
	}

	/* 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 _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 */
	fd = open(tty, O_RDWR);
	if (fd < 0)
	error("%.100s: %.100s", tty, strerror(errno));
	else
	close(fd);

	/* 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");
	gid = (grp != NULL) ? grp->gr_gid : pw->pw_gid;
	mode = (grp != NULL) ? 0620 : 0600;

	/*
	* 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));
	}
	}
	}

	/* Disconnect from the controlling tty. */
	void
	disconnect_controlling_tty(void)
	{
	#ifdef TIOCNOTTY
	int fd;

	if ((fd = open(_PATH_TTY, O_RDWR \| O_NOCTTY)) >= 0) {
	(void) ioctl(fd, TIOCNOTTY, NULL);
	close(fd);
	}
	#endif /* TIOCNOTTY */
	}