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/*
* Dropbear - a SSH2 server
*
* Copied from OpenSSH-3.5p1 source, modified by Matt Johnston 2003
*
* 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".
*/
/*RCSID("OpenBSD: sshpty.c,v 1.7 2002/06/24 17:57:20 deraadt Exp ");*/
#include "includes.h"
#include "dbutil.h"
#include "errno.h"
#include "sshpty.h"
/* Pty allocated with _getpty gets broken if we do I_PUSH:es to it. */
#if defined(HAVE__GETPTY) || defined(HAVE_OPENPTY)
#undef HAVE_DEV_PTMX
#endif
#ifdef HAVE_PTY_H
# include <pty.h>
#endif
#if defined(USE_DEV_PTMX) && defined(HAVE_STROPTS_H)
# include <stropts.h>
#endif
#ifndef O_NOCTTY
#define O_NOCTTY 0
#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, int namebuflen)
{
#if defined(HAVE_OPENPTY)
/* exists in recent (4.4) BSDs and OSF/1 */
char *name;
int i;
i = openpty(ptyfd, ttyfd, NULL, NULL, NULL);
if (i < 0) {
dropbear_log(LOG_WARNING,
"pty_allocate: openpty: %.100s", strerror(errno));
return 0;
}
name = ttyname(*ttyfd);
if (!name) {
dropbear_exit("ttyname fails for openpty device");
}
strlcpy(namebuf, name, namebuflen); /* possible truncation */
return 1;
#else /* HAVE_OPENPTY */
#ifdef HAVE__GETPTY
/*
* _getpty(3) exists in SGI Irix 4.x, 5.x & 6.x -- it generates more
* pty's automagically when needed
*/
char *slave;
slave = _getpty(ptyfd, O_RDWR, 0622, 0);
if (slave == NULL) {
dropbear_log(LOG_WARNING,
"pty_allocate: _getpty: %.100s", strerror(errno));
return 0;
}
strlcpy(namebuf, slave, namebuflen);
/* Open the slave side. */
*ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
if (*ttyfd < 0) {
dropbear_log(LOG_WARNING,
"pty_allocate error: ttyftd open error");
close(*ptyfd);
return 0;
}
return 1;
#else /* HAVE__GETPTY */
#if defined(USE_DEV_PTMX)
/*
* This code is used e.g. on Solaris 2.x. (Note that Solaris 2.3
* also has bsd-style ptys, but they simply do not work.)
*
* Linux systems may have the /dev/ptmx device, but this code won't work.
*/
int ptm;
char *pts;
ptm = open("/dev/ptmx", O_RDWR | O_NOCTTY);
if (ptm < 0) {
dropbear_log(LOG_WARNING,
"pty_allocate: /dev/ptmx: %.100s", strerror(errno));
return 0;
}
if (grantpt(ptm) < 0) {
dropbear_log(LOG_WARNING,
"grantpt: %.100s", strerror(errno));
return 0;
}
if (unlockpt(ptm) < 0) {
dropbear_log(LOG_WARNING,
"unlockpt: %.100s", strerror(errno));
return 0;
}
pts = ptsname(ptm);
if (pts == NULL) {
dropbear_log(LOG_WARNING,
"Slave pty side name could not be obtained.");
}
strlcpy(namebuf, pts, namebuflen);
*ptyfd = ptm;
/* Open the slave side. */
*ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
if (*ttyfd < 0) {
dropbear_log(LOG_ERR,
"error opening pts %.100s: %.100s", namebuf, strerror(errno));
close(*ptyfd);
return 0;
}
#ifndef HAVE_CYGWIN
/*
* Push the appropriate streams modules, as described in Solaris pts(7).
* HP-UX pts(7) doesn't have ttcompat module.
*/
if (ioctl(*ttyfd, I_PUSH, "ptem") < 0) {
dropbear_log(LOG_WARNING,
"ioctl I_PUSH ptem: %.100s", strerror(errno));
}
if (ioctl(*ttyfd, I_PUSH, "ldterm") < 0) {
dropbear_log(LOG_WARNING,
"ioctl I_PUSH ldterm: %.100s", strerror(errno));
}
#ifndef __hpux
if (ioctl(*ttyfd, I_PUSH, "ttcompat") < 0) {
dropbear_log(LOG_WARNING,
"ioctl I_PUSH ttcompat: %.100s", strerror(errno));
}
#endif
#endif
return 1;
#else /* USE_DEV_PTMX */
#ifdef HAVE_DEV_PTS_AND_PTC
/* AIX-style pty code. */
const char *name;
*ptyfd = open("/dev/ptc", O_RDWR | O_NOCTTY);
if (*ptyfd < 0) {
dropbear_log(LOG_ERR,
"Could not open /dev/ptc: %.100s", strerror(errno));
return 0;
}
name = ttyname(*ptyfd);
if (!name) {
dropbear_exit("ttyname fails for /dev/ptc device");
}
strlcpy(namebuf, name, namebuflen);
*ttyfd = open(name, O_RDWR | O_NOCTTY);
if (*ttyfd < 0) {
dropbear_log(LOG_ERR,
"Could not open pty slave side %.100s: %.100s",
name, strerror(errno));
close(*ptyfd);
return 0;
}
return 1;
#else /* HAVE_DEV_PTS_AND_PTC */
/* BSD-style pty code. */
char buf[64];
int i;
const char *ptymajors = "pqrstuvwxyzabcdefghijklmnoABCDEFGHIJKLMNOPQRSTUVWXYZ";
const char *ptyminors = "0123456789abcdef";
int num_minors = strlen(ptyminors);
int num_ptys = strlen(ptymajors) * num_minors;
struct termios tio;
for (i = 0; i < num_ptys; i++) {
snprintf(buf, sizeof buf, "/dev/pty%c%c", ptymajors[i / num_minors],
ptyminors[i % num_minors]);
snprintf(namebuf, namebuflen, "/dev/tty%c%c",
ptymajors[i / num_minors], ptyminors[i % num_minors]);
*ptyfd = open(buf, O_RDWR | O_NOCTTY);
if (*ptyfd < 0) {
/* Try SCO style naming */
snprintf(buf, sizeof buf, "/dev/ptyp%d", i);
snprintf(namebuf, namebuflen, "/dev/ttyp%d", i);
*ptyfd = open(buf, O_RDWR | O_NOCTTY);
if (*ptyfd < 0) {
continue;
}
}
/* Open the slave side. */
*ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
if (*ttyfd < 0) {
dropbear_log(LOG_ERR,
"pty_allocate: %.100s: %.100s", namebuf, strerror(errno));
close(*ptyfd);
return 0;
}
/* set tty modes to a sane state for broken clients */
if (tcgetattr(*ptyfd, &tio) < 0) {
dropbear_log(LOG_WARNING,
"ptyallocate: tty modes failed: %.100s", strerror(errno));
} else {
tio.c_lflag |= (ECHO | ISIG | ICANON);
tio.c_oflag |= (OPOST | ONLCR);
tio.c_iflag |= ICRNL;
/* Set the new modes for the terminal. */
if (tcsetattr(*ptyfd, TCSANOW, &tio) < 0) {
dropbear_log(LOG_WARNING,
"Setting tty modes for pty failed: %.100s",
strerror(errno));
}
}
return 1;
}
dropbear_log(LOG_WARNING, "Failed to open any /dev/pty?? devices");
return 0;
#endif /* HAVE_DEV_PTS_AND_PTC */
#endif /* USE_DEV_PTMX */
#endif /* HAVE__GETPTY */
#endif /* HAVE_OPENPTY */
}
/* Releases the tty. Its ownership is returned to root, and permissions to 0666. */
void
pty_release(const char *tty_name)
{
if (chown(tty_name, (uid_t) 0, (gid_t) 0) < 0
&& (errno != ENOENT)) {
dropbear_log(LOG_ERR,
"chown %.100s 0 0 failed: %.100s", tty_name, strerror(errno));
}
if (chmod(tty_name, (mode_t) 0666) < 0
&& (errno != ENOENT)) {
dropbear_log(LOG_ERR,
"chmod %.100s 0666 failed: %.100s", tty_name, strerror(errno));
}
}
/* Makes the tty the processes controlling tty and sets it to sane modes. */
void
pty_make_controlling_tty(int *ttyfd, const char *tty_name)
{
int fd;
#ifdef USE_VHANGUP
void *old;
#endif /* USE_VHANGUP */
/* Solaris has a problem with TIOCNOTTY for a bg process, so
* we disable the signal which would STOP the process - matt */
signal(SIGTTOU, SIG_IGN);
/* 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) {
dropbear_log(LOG_ERR,
"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) {
dropbear_log(LOG_ERR,
"Failed to disconnect from controlling tty.\n");
close(fd);
}
/* Make it our controlling tty. */
#ifdef TIOCSCTTY
if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0) {
dropbear_log(LOG_ERR,
"ioctl(TIOCSCTTY): %.100s", strerror(errno));
}
#endif /* TIOCSCTTY */
#ifdef HAVE_NEWS4
if (setpgrp(0,0) < 0) {
dropbear_log(LOG_ERR,
error("SETPGRP %s",strerror(errno)));
}
#endif /* HAVE_NEWS4 */
#ifdef USE_VHANGUP
old = mysignal(SIGHUP, SIG_IGN);
vhangup();
mysignal(SIGHUP, old);
#endif /* USE_VHANGUP */
fd = open(tty_name, O_RDWR);
if (fd < 0) {
dropbear_log(LOG_ERR,
"%.100s: %.100s", tty_name, 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) {
dropbear_log(LOG_ERR,
"open /dev/tty failed - could not set controlling tty: %.100s",
strerror(errno));
} else {
close(fd);
}
}
/* Changes the window size associated with the pty. */
void
pty_change_window_size(int ptyfd, int row, int col,
int xpixel, int ypixel)
{
struct winsize w;
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_name)
{
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_name, &st)) {
dropbear_exit("pty_setowner: stat(%.101s) failed: %.100s",
tty_name, strerror(errno));
}
if (st.st_uid != pw->pw_uid || st.st_gid != gid) {
if (chown(tty_name, pw->pw_uid, gid) < 0) {
if (errno == EROFS &&
(st.st_uid == pw->pw_uid || st.st_uid == 0)) {
dropbear_log(LOG_ERR,
"chown(%.100s, %u, %u) failed: %.100s",
tty_name, (unsigned int)pw->pw_uid, (unsigned int)gid,
strerror(errno));
} else {
dropbear_exit("chown(%.100s, %u, %u) failed: %.100s",
tty_name, (unsigned int)pw->pw_uid, (unsigned int)gid,
strerror(errno));
}
}
}
if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) {
if (chmod(tty_name, mode) < 0) {
if (errno == EROFS &&
(st.st_mode & (S_IRGRP | S_IROTH)) == 0) {
dropbear_log(LOG_ERR,
"chmod(%.100s, 0%o) failed: %.100s",
tty_name, mode, strerror(errno));
} else {
dropbear_exit("chmod(%.100s, 0%o) failed: %.100s",
tty_name, mode, strerror(errno));
}
}
}
}
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