rxvt-unicode/src/ptytty.C

// This file is part of libptytty. Do not make local modifications.
// http://software.schmorp.de/pkg/libptytty

/*----------------------------------------------------------------------*
 * File:        ptytty.C
 *----------------------------------------------------------------------*
 *
 * All portions of code are copyright by their respective author/s.
 * Copyright (c) 1999-2001 Geoff Wing <gcw@pobox.com>
 * Copyright (c) 2004-2006 Marc Lehmann <pcg@goof.com>
 * Copyright (c) 2006      Emanuele Giaquinta <e.giaquinta@glauco.it>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *---------------------------------------------------------------------*/

#include "../config.h"

#include "ptytty.h"

#include <cstdlib>
#include <cstring>
#include <csignal>

#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <fcntl.h>

#ifdef HAVE_SYS_IOCTL_H
# include <sys/ioctl.h>
#endif
#if defined(HAVE_DEV_PTMX) && defined(HAVE_SYS_STROPTS_H)
# include <sys/stropts.h>      /* for I_PUSH */
#endif
#ifdef HAVE_ISASTREAM
# include <stropts.h>
#endif
#if defined(HAVE_PTY_H)
# include <pty.h>
#elif defined(HAVE_LIBUTIL_H)
# include <libutil.h>
#elif defined(HAVE_UTIL_H)
# include <util.h>
#endif
#ifdef TTY_GID_SUPPORT
#include <grp.h>
#endif

#include <cstdio>

/////////////////////////////////////////////////////////////////////////////

/* ------------------------------------------------------------------------- *
 *                  GET PSEUDO TELETYPE - MASTER AND SLAVE                   *
 * ------------------------------------------------------------------------- */
/*
 * Returns pty file descriptor, or -1 on failure 
 * If successful, ttydev is set to the name of the slave device.
 * fd_tty _may_ also be set to an open fd to the slave device
 */
#if defined(UNIX98_PTY)
static int
get_pty (int *fd_tty, char **ttydev)
{
  int pfd;

# if defined(HAVE_GETPT)
  pfd = getpt();
# elif defined(HAVE_POSIX_OPENPT)
  pfd = posix_openpt (O_RDWR);
# else
  pfd = open (CLONE_DEVICE, O_RDWR | O_NOCTTY, 0);
# endif
  if (pfd >= 0)
    {
      if (grantpt (pfd) == 0    /* change slave permissions */
          && unlockpt (pfd) == 0)
        {       /* slave now unlocked */
          *ttydev = strdup (ptsname (pfd));     /* get slave's name */
          return pfd;
        }

      close (pfd);
    }

  return -1;
}
#elif defined(HAVE_OPENPTY)
static int
get_pty (int *fd_tty, char **ttydev)
{
  int pfd;
  int res;
  char tty_name[32];
  
  res = openpty (&pfd, fd_tty, tty_name, NULL, NULL);
  if (res != -1)
    {
      *ttydev = strdup (tty_name);
      return pfd;
    }

  return -1;
}
#elif defined(HAVE__GETPTY)
static int
get_pty (int *fd_tty, char **ttydev)
{
  int pfd;

  *ttydev = _getpty (&pfd, O_RDWR | O_NONBLOCK | O_NOCTTY, 0622, 0);
  if (*ttydev != NULL)
    return pfd;

  return -1;
}
#elif defined(HAVE_DEV_PTC)
static int
get_pty (int *fd_tty, char **ttydev)
{
  int pfd;

  if ((pfd = open ("/dev/ptc", O_RDWR | O_NOCTTY, 0)) >= 0)
    {
      *ttydev = strdup (ttyname (pfd));
      return pfd;
    }

  return -1;
}
#elif defined(HAVE_DEV_CLONE)
static int
get_pty (int *fd_tty, char **ttydev)
{
  int pfd;

  if ((pfd = open ("/dev/ptym/clone", O_RDWR | O_NOCTTY, 0)) >= 0)
    {
      *ttydev = strdup (ptsname (pfd));
      return pfd;
    }

  return -1;
}
#else
/* Based on the code in openssh/openbsd-compat/bsd-openpty.c */
static int
get_pty (int *fd_tty, char **ttydev)
{
  int pfd;
  int i;
  char pty_name[32];
  char tty_name[32];
  const char *majors = "pqrstuvwxyzabcde";
  const char *minors = "0123456789abcdef";
  for (i = 0; i < 256; i++)
    {
      snprintf(pty_name, 32, "/dev/pty%c%c", majors[i / 16], minors[i % 16]);
      snprintf(tty_name, 32, "/dev/tty%c%c", majors[i / 16], minors[i % 16]);
      if ((pfd = open (pty_name, O_RDWR | O_NOCTTY, 0)) == -1)
        {
          snprintf(pty_name, 32, "/dev/ptyp%d", i);
          snprintf(tty_name, 32, "/dev/ttyp%d", i);
          if ((pfd = open (pty_name, O_RDWR | O_NOCTTY, 0)) == -1)
            continue;
        }
      if (access (tty_name, R_OK | W_OK) == 0)
        {
          *ttydev = strdup (tty_name);
          return pfd;
        }

      close (pfd);
    }
}
#endif

/*----------------------------------------------------------------------*/
/*
 * Returns tty file descriptor, or -1 on failure 
 */
static int
get_tty (char *ttydev)
{
  return open (ttydev, O_RDWR | O_NOCTTY, 0);
}

/*----------------------------------------------------------------------*/
/*
 * Make our tty a controlling tty so that /dev/tty points to us
 */
static int
control_tty (int fd_tty)
{
  setsid ();

#if defined(HAVE_DEV_PTMX) && defined(I_PUSH)
  /*
   * Push STREAMS modules:
   *    ptem: pseudo-terminal hardware emulation module.
   *    ldterm: standard terminal line discipline.
   *    ttcompat: V7, 4BSD and XENIX STREAMS compatibility module.
   *
   * After we push the STREAMS modules, the first open () on the slave side
   * (i.e. the next section between the dashes giving us "tty opened OK")
   * should make the "ptem" (or "ldterm" depending upon either which OS
   * version or which set of manual pages you have) module give us a
   * controlling terminal.  We must already have close ()d the master side
   * fd in this child process before we push STREAMS modules on because the
   * documentation is really unclear about whether it is any close () on
   * the master side or the last close () - i.e. a proper STREAMS dismantling
   * close () - on the master side which causes a hang up to be sent
   * through - Geoff Wing
   */
# ifdef HAVE_ISASTREAM
  if (isastream (fd_tty) == 1)
# endif
    {
      ioctl (fd_tty, I_PUSH, "ptem");
      ioctl (fd_tty, I_PUSH, "ldterm");
      ioctl (fd_tty, I_PUSH, "ttcompat");
    }
#endif

  ioctl (fd_tty, TIOCSCTTY, NULL);

  int fd = open ("/dev/tty", O_WRONLY);
  if (fd < 0)
    return -1; /* fatal */

  close (fd);

  return 0;
}

void
ptytty::close_tty ()
{
  if (tty < 0)
    return;

  close (tty);
  tty = -1;
}

bool
ptytty::make_controlling_tty ()
{
  return control_tty (tty) >= 0;
}

void
ptytty::set_utf8_mode (bool on)
{
#ifdef IUTF8
  if (pty < 0)
    return;

  struct termios tio;

  if (tcgetattr (pty, &tio) != -1)
    {
      tcflag_t new_cflag = tio.c_iflag;

      if (on)
        new_cflag |= IUTF8;
      else
        new_cflag &= ~IUTF8;

      if (new_cflag != tio.c_iflag)
        {
          tio.c_iflag = new_cflag;
          tcsetattr (pty, TCSANOW, &tio);
        }
    }
#endif
}

static struct ttyconf {
  gid_t gid;
  mode_t mode;

  ttyconf ()
    {
#ifdef TTY_GID_SUPPORT
      struct group *gr = getgrnam ("tty");

      if (gr)
        {           /* change group ownership of tty to "tty" */
          mode = S_IRUSR | S_IWUSR | S_IWGRP;
          gid = gr->gr_gid;
        }
      else
#endif                          /* TTY_GID_SUPPORT */
        {
          mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH;
          gid = 0;
        }
    }
} ttyconf;

ptytty_unix::ptytty_unix ()
{
  name = 0;
#if UTMP_SUPPORT
  cmd_pid = 0;
#endif
}

ptytty_unix::~ptytty_unix ()
{
#if UTMP_SUPPORT
  logout ();
#endif
  put ();
}

void
ptytty_unix::put ()
{
  chmod (name, RESTORE_TTY_MODE);
  chown (name, 0, ttyconf.gid);

  close_tty ();

  if (pty >= 0)
    close (pty);

  free (name);

  pty = tty = -1;
  name = 0;
}

bool
ptytty_unix::get ()
{
  /* get master (pty) */
  if ((pty = get_pty (&tty, &name)) < 0)
    return false;

  fcntl (pty, F_SETFL, O_NONBLOCK);

  /* get slave (tty) */
  if (tty < 0)
    {
#ifndef NO_SETOWNER_TTYDEV
      chown (name, getuid (), ttyconf.gid);      /* fail silently */
      chmod (name, ttyconf.mode);
# ifdef HAVE_REVOKE
      revoke (name);
# endif
#endif

      if ((tty = get_tty (name)) < 0)
        {
          put ();
          return false;
        }
    }

  return true;
}

/////////////////////////////////////////////////////////////////////////////
// helper/proxy support

#if PTYTTY_HELPER

static int sock_fd = -1, lock_fd = -1;
static int helper_pid, owner_pid;

struct command
{
  enum { get, login, destroy } type;

  ptytty *id;

  bool login_shell;
  int cmd_pid;
  char hostname[512]; // arbitrary, but should be plenty
};

struct ptytty_proxy : ptytty
{
  ptytty *id;

  ptytty_proxy ()
  : id(0)
  {
  }

  ~ptytty_proxy ();

  bool get ();
  void login (int cmd_pid, bool login_shell, const char *hostname);
};

#if PTYTTY_REENTRANT
# define NEED_TOKEN do { char ch; read  (lock_fd, &ch, 1); } while (0)
# define GIVE_TOKEN do { char ch; write (lock_fd, &ch, 1); } while (0)
#else
# define NEED_TOKEN (void)0
# define GIVE_TOKEN (void)0
#endif

bool
ptytty_proxy::get ()
{
  NEED_TOKEN;

  command cmd;

  cmd.type = command::get;

  write (sock_fd, &cmd, sizeof (cmd));

  if (read (sock_fd, &id, sizeof (id)) != sizeof (id))
    ptytty_fatal ("protocol error while creating pty using helper process, aborting.\n");

  if (!id)
    {
      GIVE_TOKEN;
      return false;
    }

  if ((pty = recv_fd (sock_fd)) < 0
      || (tty = recv_fd (sock_fd)) < 0)
    ptytty_fatal ("protocol error while reading pty/tty fds from helper process, aborting.\n");

  GIVE_TOKEN;
  return true;
}

void
ptytty_proxy::login (int cmd_pid, bool login_shell, const char *hostname)
{
  NEED_TOKEN;

  command cmd;

  cmd.type = command::login;
  cmd.id = id;
  cmd.cmd_pid = cmd_pid;
  cmd.login_shell = login_shell;
  strncpy (cmd.hostname, hostname, sizeof (cmd.hostname));

  write (sock_fd, &cmd, sizeof (cmd));

  GIVE_TOKEN;
}

ptytty_proxy::~ptytty_proxy ()
{
  if (id)
    {
      NEED_TOKEN;

      command cmd;

      cmd.type = command::destroy;
      cmd.id = id;

      write (sock_fd, &cmd, sizeof (cmd));

      GIVE_TOKEN;
    }
}

static
void serve ()
{
  command cmd;
  vector<ptytty *> ptys;

  for (;;)
    {
      GIVE_TOKEN;

      if (read (sock_fd, &cmd, sizeof (command)) != sizeof (command))
        break;

      if (cmd.type == command::get)
        {
          // -> id ptyfd ttyfd
          cmd.id = new ptytty_unix;

          if (cmd.id->get ())
            {
              write (sock_fd, &cmd.id, sizeof (cmd.id));
              ptys.push_back (cmd.id);

              ptytty::send_fd (sock_fd, cmd.id->pty);
              ptytty::send_fd (sock_fd, cmd.id->tty);
            }
          else
            {
              delete cmd.id;
              cmd.id = 0;
              write (sock_fd, &cmd.id, sizeof (cmd.id));
            }
        }
      else if (cmd.type == command::login)
        {
#if UTMP_SUPPORT
          if (find (ptys.begin (), ptys.end (), cmd.id) != ptys.end ())
            {
              cmd.hostname[sizeof (cmd.hostname) - 1] = 0;
              cmd.id->login (cmd.cmd_pid, cmd.login_shell, cmd.hostname);
            }
#endif
        }
      else if (cmd.type == command::destroy)
        {
          vector<ptytty *>::iterator pty = find (ptys.begin (), ptys.end (), cmd.id);

          if (pty != ptys.end ())
            {
              delete *pty;
              ptys.erase (pty);
            }
        }
      else
        break;

      NEED_TOKEN;
    }

  // destroy all ptys
  for (vector<ptytty *>::iterator i = ptys.end (); i-- > ptys.begin (); )
    delete *i;
}

void
ptytty::use_helper ()
{
#ifndef PTYTTY_NO_PID_CHECK
  int pid = getpid ();
#endif

  if (sock_fd >= 0
#ifndef PTYTTY_NO_PID_CHECK
      && pid == owner_pid
#endif
      )
    return;

#ifndef PTYTTY_NO_PID_CHECK
  owner_pid = pid;
#endif

  int sv[2];

  if (socketpair (AF_UNIX, SOCK_STREAM, 0, sv))
    ptytty_fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n");

#ifdef PTYTTY_REENTRANT
  int lv[2];

  if (socketpair (AF_UNIX, SOCK_STREAM, 0, lv))
    ptytty_fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n");
#endif

  helper_pid = fork ();

  if (helper_pid < 0)
    ptytty_fatal ("could not create pty/sessiondb helper process, aborting.\n");

  if (helper_pid)
    {
      // client, process
      sock_fd = sv[0];
      close (sv[1]);
      fcntl (sock_fd, F_SETFD, FD_CLOEXEC);
#ifdef PTYTTY_REENTRANT
      lock_fd = lv[0];
      close (lv[1]);
      fcntl (lock_fd, F_SETFD, FD_CLOEXEC);
#endif
    }
  else
    {
      // server, pty-helper
      sock_fd = sv[1];
#ifdef PTYTTY_REENTRANT
      lock_fd = lv[1];
#endif

      chdir ("/");

      signal (SIGHUP,  SIG_IGN);
      signal (SIGTERM, SIG_IGN);
      signal (SIGINT,  SIG_IGN);
      signal (SIGPIPE, SIG_IGN);

      for (int fd = 0; fd < 1023; fd++)
        if (fd != sock_fd && fd != lock_fd)
          close (fd);

      serve ();
      _exit (EXIT_SUCCESS);
    }
}

#endif

ptytty *
ptytty::create ()
{
#if PTYTTY_HELPER
  if (helper_pid
# ifndef PTYTTY_NO_PID_CHECK
      && getpid () == owner_pid
# endif
      )
    // use helper process
    return new ptytty_proxy;
  else
#endif
    return new ptytty_unix;
}

void
ptytty::init ()
{
  uid_t uid = getuid ();
  gid_t gid = getgid ();
      
  // before doing anything else, check for setuid/setgid operation,
  // start the helper process and drop privileges
  if (uid != geteuid ()
      || gid != getegid ())
    {
#if PTYTTY_HELPER
      use_helper ();
#else
      ptytty_warn ("running setuid/setgid without pty helper compiled in, continuing unprivileged.\n");
#endif

      drop_privileges ();
    }
}

void
ptytty::drop_privileges ()
{
  uid_t uid = getuid ();
  gid_t gid = getgid ();

  // drop privileges
#if HAVE_SETRESUID
  setresgid (gid, gid, gid);
  setresuid (uid, uid, uid);
#elif HAVE_SETREUID
  setregid (gid, gid);
  setreuid (uid, uid);
#elif HAVE_SETUID
  setgid (gid);
  setuid (uid);
#endif

  if (uid != geteuid ()
      || gid != getegid ())
    ptytty_fatal ("unable to drop privileges, aborting.\n");
}

/////////////////////////////////////////////////////////////////////////////
// C API

#ifndef PTYTTY_NO_C_API

typedef void *PTYTTY;

#define DEFINE_METHOD(retval, name, args1, args2) \
extern "C" retval ptytty_ ## name args1           \
{ return ((struct ptytty *)ptytty)->name args2; }

DEFINE_METHOD(int,pty,(PTYTTY ptytty),)
DEFINE_METHOD(int,tty,(PTYTTY ptytty),)
DEFINE_METHOD(int,get,(PTYTTY ptytty),())
DEFINE_METHOD(void,login,(PTYTTY ptytty, int cmd_pid, bool login_shell, const char *hostname),(cmd_pid,login_shell,hostname))

DEFINE_METHOD(void,close_tty,(PTYTTY ptytty),())
DEFINE_METHOD(int,make_controlling_tty,(PTYTTY ptytty),())
DEFINE_METHOD(void,set_utf8_mode,(PTYTTY ptytty, int on),(on))

#define DEFINE_STATIC(retval, name, args) \
extern "C" retval ptytty_ ## name args           \
{ return ptytty::name args; }

DEFINE_STATIC(void,drop_privileges,())
DEFINE_STATIC(void,use_helper,())
DEFINE_STATIC(void,init,())

DEFINE_STATIC(PTYTTY ,create,())

void ptytty_delete (PTYTTY ptytty)
{
  delete (struct ptytty *)ptytty;
}

// send_fd, recv_fd not exposed

#endif
Revision:	1.60
Committed:	Mon Jan 23 12:37:59 2006 UTC (18 years, 4 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.59:	+12 -10 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.55	// This file is part of libptytty. Do not make local modifications.
2			// http://software.schmorp.de/pkg/libptytty
3
4			/----------------------------------------------------------------------
5	pcg	1.11	* File: ptytty.C
6	pcg	1.1	----------------------------------------------------------------------
7			*
8			* All portions of code are copyright by their respective author/s.
9			* Copyright (c) 1999-2001 Geoff Wing <gcw@pobox.com>
10	root	1.30	* Copyright (c) 2004-2006 Marc Lehmann <pcg@goof.com>
11	root	1.58	* Copyright (c) 2006 Emanuele Giaquinta <e.giaquinta@glauco.it>
12	pcg	1.1	*
13			* This program is free software; you can redistribute it and/or modify
14			* it under the terms of the GNU General Public License as published by
15			* the Free Software Foundation; either version 2 of the License, or
16			* (at your option) any later version.
17			*
18			* This program is distributed in the hope that it will be useful,
19			* but WITHOUT ANY WARRANTY; without even the implied warranty of
20			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21			* GNU General Public License for more details.
22			*
23			* You should have received a copy of the GNU General Public License
24			* along with this program; if not, write to the Free Software
25			* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
26			---------------------------------------------------------------------/
27
28	root	1.55	#include "../config.h"
29	root	1.54
30			#include "ptytty.h"
31	pcg	1.1
32	root	1.40	#include <cstdlib>
33			#include <cstring>
34	root	1.59	#include <csignal>
35	root	1.40
36			#include <sys/types.h>
37			#include <sys/socket.h>
38			#include <unistd.h>
39			#include <fcntl.h>
40	root	1.31
41	pcg	1.1	#ifdef HAVE_SYS_IOCTL_H
42			# include <sys/ioctl.h>
43			#endif
44	ayin	1.53	#if defined(HAVE_DEV_PTMX) && defined(HAVE_SYS_STROPTS_H)
45	pcg	1.1	# include <sys/stropts.h> /* for I_PUSH */
46			#endif
47	pcg	1.10	#ifdef HAVE_ISASTREAM
48			# include <stropts.h>
49			#endif
50	root	1.31	#if defined(HAVE_PTY_H)
51	root	1.22	# include <pty.h>
52	root	1.31	#elif defined(HAVE_LIBUTIL_H)
53	root	1.16	# include <libutil.h>
54	root	1.31	#elif defined(HAVE_UTIL_H)
55	root	1.17	# include <util.h>
56	pcg	1.1	#endif
57	ayin	1.53	#ifdef TTY_GID_SUPPORT
58			#include <grp.h>
59			#endif
60	pcg	1.1
61	root	1.16	#include <cstdio>
62
63	root	1.36	/////////////////////////////////////////////////////////////////////////////
64
65	pcg	1.1	/* ------------------------------------------------------------------------- *
66			* GET PSEUDO TELETYPE - MASTER AND SLAVE *
67			* ------------------------------------------------------------------------- */
68			/*
69			* Returns pty file descriptor, or -1 on failure
70			* If successful, ttydev is set to the name of the slave device.
71			* fd_tty _may_ also be set to an open fd to the slave device
72			*/
73	ayin	1.53	#if defined(UNIX98_PTY)
74			static int
75			get_pty (int fd_tty, char *ttydev)
76	pcg	1.1	{
77	pcg	1.4	int pfd;
78	pcg	1.1
79	ayin	1.53	# if defined(HAVE_GETPT)
80	ayin	1.44	pfd = getpt();
81	ayin	1.53	# elif defined(HAVE_POSIX_OPENPT)
82	ayin	1.44	pfd = posix_openpt (O_RDWR);
83			# else
84	ayin	1.53	pfd = open (CLONE_DEVICE, O_RDWR \| O_NOCTTY, 0);
85	ayin	1.44	# endif
86			if (pfd >= 0)
87			{
88			if (grantpt (pfd) == 0 /* change slave permissions */
89			&& unlockpt (pfd) == 0)
90			{ /* slave now unlocked */
91			ttydev = strdup (ptsname (pfd)); / get slave's name */
92			return pfd;
93			}
94	root	1.45
95	ayin	1.44	close (pfd);
96			}
97	root	1.45
98	ayin	1.44	return -1;
99			}
100	ayin	1.53	#elif defined(HAVE_OPENPTY)
101			static int
102			get_pty (int fd_tty, char *ttydev)
103	ayin	1.44	{
104			int pfd;
105			int res;
106	ayin	1.51	char tty_name[32];
107	ayin	1.44
108			res = openpty (&pfd, fd_tty, tty_name, NULL, NULL);
109	root	1.27	if (res != -1)
110	pcg	1.4	{
111	pcg	1.6	*ttydev = strdup (tty_name);
112	pcg	1.4	return pfd;
113	pcg	1.1	}
114	root	1.45
115	ayin	1.44	return -1;
116			}
117	ayin	1.53	#elif defined(HAVE__GETPTY)
118			static int
119			get_pty (int fd_tty, char *ttydev)
120	ayin	1.44	{
121			int pfd;
122
123	pcg	1.6	*ttydev = _getpty (&pfd, O_RDWR \| O_NONBLOCK \| O_NOCTTY, 0622, 0);
124	pcg	1.4	if (*ttydev != NULL)
125			return pfd;
126	root	1.45
127	ayin	1.44	return -1;
128			}
129	ayin	1.53	#elif defined(HAVE_DEV_PTC)
130			static int
131			get_pty (int fd_tty, char *ttydev)
132	ayin	1.44	{
133			int pfd;
134	pcg	1.4
135	pcg	1.6	if ((pfd = open ("/dev/ptc", O_RDWR \| O_NOCTTY, 0)) >= 0)
136	pcg	1.4	{
137	root	1.16	*ttydev = strdup (ttyname (pfd));
138	pcg	1.4	return pfd;
139	pcg	1.1	}
140	root	1.45
141	ayin	1.44	return -1;
142			}
143	ayin	1.53	#elif defined(HAVE_DEV_CLONE)
144			static int
145			get_pty (int fd_tty, char *ttydev)
146	ayin	1.44	{
147			int pfd;
148
149	pcg	1.6	if ((pfd = open ("/dev/ptym/clone", O_RDWR \| O_NOCTTY, 0)) >= 0)
150	pcg	1.4	{
151	root	1.16	*ttydev = strdup (ptsname (pfd));
152	pcg	1.4	return pfd;
153	pcg	1.1	}
154	root	1.45
155	ayin	1.44	return -1;
156			}
157	ayin	1.53	#else
158			/* Based on the code in openssh/openbsd-compat/bsd-openpty.c */
159			static int
160			get_pty (int fd_tty, char *ttydev)
161	ayin	1.44	{
162	root	1.45	int pfd;
163	ayin	1.53	int i;
164			char pty_name[32];
165			char tty_name[32];
166			const char *majors = "pqrstuvwxyzabcde";
167			const char *minors = "0123456789abcdef";
168			for (i = 0; i < 256; i++)
169			{
170			snprintf(pty_name, 32, "/dev/pty%c%c", majors[i / 16], minors[i % 16]);
171			snprintf(tty_name, 32, "/dev/tty%c%c", majors[i / 16], minors[i % 16]);
172			if ((pfd = open (pty_name, O_RDWR \| O_NOCTTY, 0)) == -1)
173	root	1.45	{
174	ayin	1.53	snprintf(pty_name, 32, "/dev/ptyp%d", i);
175			snprintf(tty_name, 32, "/dev/ttyp%d", i);
176			if ((pfd = open (pty_name, O_RDWR \| O_NOCTTY, 0)) == -1)
177			continue;
178	root	1.45	}
179	ayin	1.53	if (access (tty_name, R_OK \| W_OK) == 0)
180	root	1.45	{
181	ayin	1.53	*ttydev = strdup (tty_name);
182			return pfd;
183			}
184	root	1.45
185	ayin	1.53	close (pfd);
186	root	1.45	}
187	ayin	1.44	}
188	pcg	1.1	#endif
189	root	1.45
190	pcg	1.1	/----------------------------------------------------------------------/
191			/*
192			* Returns tty file descriptor, or -1 on failure
193			*/
194	root	1.16	static int
195			get_tty (char *ttydev)
196	pcg	1.1	{
197	pcg	1.4	return open (ttydev, O_RDWR \| O_NOCTTY, 0);
198	pcg	1.1	}
199
200			/----------------------------------------------------------------------/
201			/*
202			* Make our tty a controlling tty so that /dev/tty points to us
203			*/
204	root	1.16	static int
205	root	1.36	control_tty (int fd_tty)
206	pcg	1.1	{
207	pcg	1.4	setsid ();
208	root	1.16
209	ayin	1.53	#if defined(HAVE_DEV_PTMX) && defined(I_PUSH)
210	pcg	1.4	/*
211			* Push STREAMS modules:
212			* ptem: pseudo-terminal hardware emulation module.
213			* ldterm: standard terminal line discipline.
214			* ttcompat: V7, 4BSD and XENIX STREAMS compatibility module.
215			*
216	pcg	1.6	* After we push the STREAMS modules, the first open () on the slave side
217	pcg	1.4	* (i.e. the next section between the dashes giving us "tty opened OK")
218			* should make the "ptem" (or "ldterm" depending upon either which OS
219			* version or which set of manual pages you have) module give us a
220	pcg	1.6	* controlling terminal. We must already have close ()d the master side
221	pcg	1.4	* fd in this child process before we push STREAMS modules on because the
222	pcg	1.6	* documentation is really unclear about whether it is any close () on
223			* the master side or the last close () - i.e. a proper STREAMS dismantling
224			* close () - on the master side which causes a hang up to be sent
225	pcg	1.4	* through - Geoff Wing
226			*/
227	root	1.47	# ifdef HAVE_ISASTREAM
228	pcg	1.4	if (isastream (fd_tty) == 1)
229	root	1.47	# endif
230	pcg	1.1	{
231	pcg	1.4	ioctl (fd_tty, I_PUSH, "ptem");
232			ioctl (fd_tty, I_PUSH, "ldterm");
233			ioctl (fd_tty, I_PUSH, "ttcompat");
234	pcg	1.1	}
235	root	1.47	#endif
236	root	1.45
237			ioctl (fd_tty, TIOCSCTTY, NULL);
238
239			int fd = open ("/dev/tty", O_WRONLY);
240	pcg	1.4	if (fd < 0)
241	root	1.56	return -1; /* fatal */
242	root	1.45
243	pcg	1.4	close (fd);
244
245			return 0;
246	pcg	1.1	}
247	root	1.16
248	root	1.36	void
249	root	1.54	ptytty::close_tty ()
250	root	1.36	{
251			if (tty < 0)
252			return;
253
254			close (tty);
255			tty = -1;
256			}
257
258			bool
259	root	1.54	ptytty::make_controlling_tty ()
260	root	1.36	{
261			return control_tty (tty) >= 0;
262			}
263
264			void
265	root	1.54	ptytty::set_utf8_mode (bool on)
266	root	1.36	{
267			#ifdef IUTF8
268			if (pty < 0)
269			return;
270
271			struct termios tio;
272
273			if (tcgetattr (pty, &tio) != -1)
274			{
275			tcflag_t new_cflag = tio.c_iflag;
276
277			if (on)
278			new_cflag \|= IUTF8;
279			else
280			new_cflag &= ~IUTF8;
281
282			if (new_cflag != tio.c_iflag)
283			{
284			tio.c_iflag = new_cflag;
285			tcsetattr (pty, TCSANOW, &tio);
286			}
287			}
288			#endif
289			}
290
291	root	1.16	static struct ttyconf {
292			gid_t gid;
293			mode_t mode;
294
295			ttyconf ()
296			{
297			#ifdef TTY_GID_SUPPORT
298			struct group *gr = getgrnam ("tty");
299
300			if (gr)
301			{ /* change group ownership of tty to "tty" */
302			mode = S_IRUSR \| S_IWUSR \| S_IWGRP;
303			gid = gr->gr_gid;
304			}
305			else
306			#endif /* TTY_GID_SUPPORT */
307			{
308			mode = S_IRUSR \| S_IWUSR \| S_IWGRP \| S_IWOTH;
309	ayin	1.48	gid = 0;
310	root	1.16	}
311			}
312			} ttyconf;
313
314	root	1.54	ptytty_unix::ptytty_unix ()
315	root	1.16	{
316			name = 0;
317	root	1.35	#if UTMP_SUPPORT
318			cmd_pid = 0;
319			#endif
320	root	1.16	}
321
322	root	1.54	ptytty_unix::~ptytty_unix ()
323	root	1.16	{
324	root	1.43	#if UTMP_SUPPORT
325	root	1.35	logout ();
326	root	1.43	#endif
327	root	1.16	put ();
328			}
329
330			void
331	root	1.54	ptytty_unix::put ()
332	root	1.16	{
333	ayin	1.49	chmod (name, RESTORE_TTY_MODE);
334			chown (name, 0, ttyconf.gid);
335	root	1.16
336			close_tty ();
337	root	1.50
338			if (pty >= 0)
339			close (pty);
340
341	root	1.16	free (name);
342
343			pty = tty = -1;
344			name = 0;
345			}
346
347			bool
348	root	1.54	ptytty_unix::get ()
349	root	1.16	{
350			/* get master (pty) */
351			if ((pty = get_pty (&tty, &name)) < 0)
352			return false;
353
354			fcntl (pty, F_SETFL, O_NONBLOCK);
355
356			/* get slave (tty) */
357			if (tty < 0)
358			{
359			#ifndef NO_SETOWNER_TTYDEV
360	ayin	1.49	chown (name, getuid (), ttyconf.gid); /* fail silently */
361			chmod (name, ttyconf.mode);
362			# ifdef HAVE_REVOKE
363			revoke (name);
364			# endif
365	root	1.16	#endif
366
367			if ((tty = get_tty (name)) < 0)
368			{
369			put ();
370			return false;
371			}
372			}
373
374			return true;
375			}
376
377	root	1.59	/////////////////////////////////////////////////////////////////////////////
378			// helper/proxy support
379
380	root	1.40	#if PTYTTY_HELPER
381
382	root	1.59	static int sock_fd = -1, lock_fd = -1;
383	root	1.56	static int helper_pid, owner_pid;
384	root	1.40
385			struct command
386			{
387			enum { get, login, destroy } type;
388
389	root	1.54	ptytty *id;
390	root	1.40
391			bool login_shell;
392			int cmd_pid;
393			char hostname[512]; // arbitrary, but should be plenty
394			};
395
396	root	1.54	struct ptytty_proxy : ptytty
397	root	1.40	{
398	root	1.54	ptytty *id;
399	root	1.40
400	root	1.54	ptytty_proxy ()
401			: id(0)
402			{
403			}
404
405			~ptytty_proxy ();
406	root	1.40
407			bool get ();
408			void login (int cmd_pid, bool login_shell, const char *hostname);
409			};
410
411	root	1.59	#if PTYTTY_REENTRANT
412			# define NEED_TOKEN do { char ch; read (lock_fd, &ch, 1); } while (0)
413			# define GIVE_TOKEN do { char ch; write (lock_fd, &ch, 1); } while (0)
414			#else
415			# define NEED_TOKEN (void)0
416			# define GIVE_TOKEN (void)0
417			#endif
418
419	root	1.40	bool
420	root	1.54	ptytty_proxy::get ()
421	root	1.40	{
422	root	1.59	NEED_TOKEN;
423
424	root	1.40	command cmd;
425
426			cmd.type = command::get;
427
428			write (sock_fd, &cmd, sizeof (cmd));
429
430			if (read (sock_fd, &id, sizeof (id)) != sizeof (id))
431	root	1.56	ptytty_fatal ("protocol error while creating pty using helper process, aborting.\n");
432	root	1.40
433			if (!id)
434	root	1.59	{
435			GIVE_TOKEN;
436			return false;
437			}
438	root	1.40
439	root	1.56	if ((pty = recv_fd (sock_fd)) < 0
440			\|\| (tty = recv_fd (sock_fd)) < 0)
441			ptytty_fatal ("protocol error while reading pty/tty fds from helper process, aborting.\n");
442	root	1.40
443	root	1.59	GIVE_TOKEN;
444	root	1.40	return true;
445			}
446
447			void
448	root	1.54	ptytty_proxy::login (int cmd_pid, bool login_shell, const char *hostname)
449	root	1.40	{
450	root	1.59	NEED_TOKEN;
451
452	root	1.40	command cmd;
453
454			cmd.type = command::login;
455			cmd.id = id;
456			cmd.cmd_pid = cmd_pid;
457			cmd.login_shell = login_shell;
458			strncpy (cmd.hostname, hostname, sizeof (cmd.hostname));
459
460			write (sock_fd, &cmd, sizeof (cmd));
461	root	1.59
462			GIVE_TOKEN;
463	root	1.40	}
464
465	root	1.54	ptytty_proxy::~ptytty_proxy ()
466	root	1.40	{
467	root	1.54	if (id)
468			{
469	root	1.59	NEED_TOKEN;
470
471	root	1.54	command cmd;
472	root	1.40
473	root	1.54	cmd.type = command::destroy;
474			cmd.id = id;
475	root	1.40
476	root	1.54	write (sock_fd, &cmd, sizeof (cmd));
477	root	1.59
478			GIVE_TOKEN;
479	root	1.54	}
480	root	1.40	}
481
482			static
483			void serve ()
484			{
485			command cmd;
486	root	1.54	vector<ptytty *> ptys;
487	root	1.40
488	root	1.59	for (;;)
489	root	1.40	{
490	root	1.59	GIVE_TOKEN;
491
492			if (read (sock_fd, &cmd, sizeof (command)) != sizeof (command))
493			break;
494
495	root	1.40	if (cmd.type == command::get)
496			{
497			// -> id ptyfd ttyfd
498	root	1.54	cmd.id = new ptytty_unix;
499	root	1.40
500			if (cmd.id->get ())
501			{
502			write (sock_fd, &cmd.id, sizeof (cmd.id));
503			ptys.push_back (cmd.id);
504
505	root	1.56	ptytty::send_fd (sock_fd, cmd.id->pty);
506			ptytty::send_fd (sock_fd, cmd.id->tty);
507	root	1.40	}
508			else
509			{
510			delete cmd.id;
511			cmd.id = 0;
512			write (sock_fd, &cmd.id, sizeof (cmd.id));
513			}
514			}
515			else if (cmd.type == command::login)
516			{
517	root	1.43	#if UTMP_SUPPORT
518	root	1.59	if (find (ptys.begin (), ptys.end (), cmd.id) != ptys.end ())
519	root	1.40	{
520			cmd.hostname[sizeof (cmd.hostname) - 1] = 0;
521			cmd.id->login (cmd.cmd_pid, cmd.login_shell, cmd.hostname);
522			}
523	root	1.43	#endif
524	root	1.40	}
525			else if (cmd.type == command::destroy)
526			{
527	root	1.56	vector<ptytty *>::iterator pty = find (ptys.begin (), ptys.end (), cmd.id);
528	root	1.40
529	root	1.56	if (pty != ptys.end ())
530	root	1.40	{
531	root	1.42	delete *pty;
532	root	1.40	ptys.erase (pty);
533			}
534			}
535			else
536			break;
537	root	1.59
538			NEED_TOKEN;
539	root	1.40	}
540
541			// destroy all ptys
542	root	1.56	for (vector<ptytty *>::iterator i = ptys.end (); i-- > ptys.begin (); )
543	root	1.40	delete *i;
544			}
545
546	root	1.56	void
547			ptytty::use_helper ()
548	root	1.40	{
549	root	1.59	#ifndef PTYTTY_NO_PID_CHECK
550	root	1.56	int pid = getpid ();
551	root	1.59	#endif
552	root	1.56
553	root	1.59	if (sock_fd >= 0
554			#ifndef PTYTTY_NO_PID_CHECK
555			&& pid == owner_pid
556			#endif
557			)
558	root	1.56	return;
559
560	root	1.59	#ifndef PTYTTY_NO_PID_CHECK
561	root	1.56	owner_pid = pid;
562	root	1.59	#endif
563	root	1.56
564	root	1.40	int sv[2];
565
566			if (socketpair (AF_UNIX, SOCK_STREAM, 0, sv))
567	root	1.56	ptytty_fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n");
568	root	1.40
569	root	1.59	#ifdef PTYTTY_REENTRANT
570			int lv[2];
571
572			if (socketpair (AF_UNIX, SOCK_STREAM, 0, lv))
573			ptytty_fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n");
574			#endif
575
576	root	1.56	helper_pid = fork ();
577	root	1.40
578	root	1.56	if (helper_pid < 0)
579			ptytty_fatal ("could not create pty/sessiondb helper process, aborting.\n");
580	root	1.40
581	root	1.56	if (helper_pid)
582	root	1.40	{
583	root	1.54	// client, process
584	root	1.40	sock_fd = sv[0];
585			close (sv[1]);
586			fcntl (sock_fd, F_SETFD, FD_CLOEXEC);
587	root	1.59	#ifdef PTYTTY_REENTRANT
588			lock_fd = lv[0];
589			close (lv[1]);
590			fcntl (lock_fd, F_SETFD, FD_CLOEXEC);
591			#endif
592	root	1.40	}
593			else
594			{
595			// server, pty-helper
596			sock_fd = sv[1];
597	root	1.59	#ifdef PTYTTY_REENTRANT
598			lock_fd = lv[1];
599			#endif
600	root	1.40
601	root	1.56	chdir ("/");
602
603	root	1.59	signal (SIGHUP, SIG_IGN);
604			signal (SIGTERM, SIG_IGN);
605			signal (SIGINT, SIG_IGN);
606			signal (SIGPIPE, SIG_IGN);
607
608	root	1.41	for (int fd = 0; fd < 1023; fd++)
609	root	1.59	if (fd != sock_fd && fd != lock_fd)
610	root	1.41	close (fd);
611	root	1.40
612			serve ();
613			_exit (EXIT_SUCCESS);
614			}
615			}
616	root	1.50
617	root	1.40	#endif
618
619	root	1.54	ptytty *
620	root	1.56	ptytty::create ()
621	root	1.39	{
622	root	1.40	#if PTYTTY_HELPER
623	root	1.59	if (helper_pid
624			# ifndef PTYTTY_NO_PID_CHECK
625			&& getpid () == owner_pid
626			# endif
627			)
628	root	1.41	// use helper process
629	root	1.54	return new ptytty_proxy;
630	root	1.40	else
631			#endif
632	root	1.54	return new ptytty_unix;
633	root	1.39	}
634
635	root	1.56	void
636			ptytty::init ()
637			{
638			uid_t uid = getuid ();
639			gid_t gid = getgid ();
640
641			// before doing anything else, check for setuid/setgid operation,
642			// start the helper process and drop privileges
643			if (uid != geteuid ()
644			\|\| gid != getegid ())
645			{
646			#if PTYTTY_HELPER
647			use_helper ();
648			#else
649			ptytty_warn ("running setuid/setgid without pty helper compiled in, continuing unprivileged.\n");
650			#endif
651
652			drop_privileges ();
653			}
654			}
655
656			void
657			ptytty::drop_privileges ()
658			{
659			uid_t uid = getuid ();
660			gid_t gid = getgid ();
661
662			// drop privileges
663			#if HAVE_SETRESUID
664			setresgid (gid, gid, gid);
665			setresuid (uid, uid, uid);
666			#elif HAVE_SETREUID
667			setregid (gid, gid);
668			setreuid (uid, uid);
669			#elif HAVE_SETUID
670			setgid (gid);
671			setuid (uid);
672			#endif
673
674			if (uid != geteuid ()
675			\|\| gid != getegid ())
676			ptytty_fatal ("unable to drop privileges, aborting.\n");
677			}
678	root	1.16
679	root	1.59	/////////////////////////////////////////////////////////////////////////////
680			// C API
681
682			#ifndef PTYTTY_NO_C_API
683
684	root	1.60	typedef void *PTYTTY;
685
686	root	1.59	#define DEFINE_METHOD(retval, name, args1, args2) \
687			extern "C" retval ptytty_ ## name args1 \
688			{ return ((struct ptytty *)ptytty)->name args2; }
689
690	root	1.60	DEFINE_METHOD(int,pty,(PTYTTY ptytty),)
691			DEFINE_METHOD(int,tty,(PTYTTY ptytty),)
692			DEFINE_METHOD(int,get,(PTYTTY ptytty),())
693			DEFINE_METHOD(void,login,(PTYTTY ptytty, int cmd_pid, bool login_shell, const char *hostname),(cmd_pid,login_shell,hostname))
694
695			DEFINE_METHOD(void,close_tty,(PTYTTY ptytty),())
696			DEFINE_METHOD(int,make_controlling_tty,(PTYTTY ptytty),())
697			DEFINE_METHOD(void,set_utf8_mode,(PTYTTY ptytty, int on),(on))
698	root	1.59
699			#define DEFINE_STATIC(retval, name, args) \
700			extern "C" retval ptytty_ ## name args \
701			{ return ptytty::name args; }
702
703			DEFINE_STATIC(void,drop_privileges,())
704			DEFINE_STATIC(void,use_helper,())
705			DEFINE_STATIC(void,init,())
706
707	root	1.60	DEFINE_STATIC(PTYTTY ,create,())
708	root	1.59
709	root	1.60	void ptytty_delete (PTYTTY ptytty)
710	root	1.59	{
711			delete (struct ptytty *)ptytty;
712			}
713
714			// send_fd, recv_fd not exposed
715
716			#endif