/*

 * 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;

  }

#if !defined(HAVE_CYGWIN) && defined(I_PUSH)

  /*

   * 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));

  }

  /* Allow either "tty" gid or user's own gid. On Linux with openpty()

   * this varies depending on the devpts mount options */

  if (st.st_uid != pw->pw_uid || !(st.st_gid == gid || st.st_gid == pw->pw_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));

      }

    }

  }

}