libptytty/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 <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;
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);
};

bool
ptytty_proxy::get ()
{
  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)
    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");

  return true;
}

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

ptytty_proxy::~ptytty_proxy ()
{
  if (id)
    {
      command cmd;

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

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

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

  while (read (sock_fd, &cmd, sizeof (command)) == sizeof (command))
    {
      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;
    }

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

void
ptytty::use_helper ()
{
  int pid = getpid ();

  if (sock_fd >= 0 && pid == owner_pid)
    return;

  owner_pid = pid;

  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");

  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);
    }
  else
    {
      // server, pty-helper
      sock_fd = sv[1];

      chdir ("/");

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

      serve ();
      _exit (EXIT_SUCCESS);
    }
}

#endif

ptytty *
ptytty::create ()
{
#if PTYTTY_HELPER
  if (helper_pid && getpid () == owner_pid)
    // 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 NO_C_API

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

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

DEFINE_METHOD(void,close_tty,(void *ptytty),())
DEFINE_METHOD(int,make_controlling_tty,(void *ptytty),())
DEFINE_METHOD(void,set_utf8_mode,(void *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(void *,create,())

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

// send_fd, recv_fd not exposed

#endif
Revision:	1.16
Committed:	Mon Jan 23 11:22:34 2006 UTC (20 years, 7 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.15:	+4 -2 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.8	// This file is part of libptytty. Do not make local modifications.
2			// http://software.schmorp.de/pkg/libptytty
3
4			/----------------------------------------------------------------------
5	root	1.1	* File: ptytty.C
6			----------------------------------------------------------------------
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	1.2	* Copyright (c) 2004-2006 Marc Lehmann <pcg@goof.com>
11	root	1.12	* Copyright (c) 2006 Emanuele Giaquinta <e.giaquinta@glauco.it>
12	root	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	1.8	#include "../config.h"
29	root	1.1
30	root	1.3	#include "ptytty.h"
31
32	root	1.2	#include <cstdlib>
33			#include <cstring>
34
35			#include <sys/types.h>
36			#include <sys/socket.h>
37			#include <unistd.h>
38			#include <fcntl.h>
39
40	root	1.1	#ifdef HAVE_SYS_IOCTL_H
41			# include <sys/ioctl.h>
42			#endif
43	root	1.2	#if defined(HAVE_DEV_PTMX) && defined(HAVE_SYS_STROPTS_H)
44	root	1.1	# include <sys/stropts.h> /* for I_PUSH */
45			#endif
46			#ifdef HAVE_ISASTREAM
47			# include <stropts.h>
48			#endif
49	root	1.2	#if defined(HAVE_PTY_H)
50	root	1.1	# include <pty.h>
51	root	1.2	#elif defined(HAVE_LIBUTIL_H)
52	root	1.1	# include <libutil.h>
53	root	1.2	#elif defined(HAVE_UTIL_H)
54	root	1.1	# include <util.h>
55			#endif
56	root	1.2	#ifdef TTY_GID_SUPPORT
57			#include <grp.h>
58			#endif
59	root	1.1
60			#include <cstdio>
61	root	1.2
62			/////////////////////////////////////////////////////////////////////////////
63	root	1.1
64			/* ------------------------------------------------------------------------- *
65			* GET PSEUDO TELETYPE - MASTER AND SLAVE *
66			* ------------------------------------------------------------------------- */
67			/*
68			* Returns pty file descriptor, or -1 on failure
69			* If successful, ttydev is set to the name of the slave device.
70			* fd_tty _may_ also be set to an open fd to the slave device
71			*/
72	root	1.2	#if defined(UNIX98_PTY)
73	root	1.1	static int
74			get_pty (int fd_tty, char *ttydev)
75			{
76			int pfd;
77
78	root	1.2	# if defined(HAVE_GETPT)
79			pfd = getpt();
80			# elif defined(HAVE_POSIX_OPENPT)
81			pfd = posix_openpt (O_RDWR);
82			# else
83			pfd = open (CLONE_DEVICE, O_RDWR \| O_NOCTTY, 0);
84			# endif
85			if (pfd >= 0)
86			{
87			if (grantpt (pfd) == 0 /* change slave permissions */
88			&& unlockpt (pfd) == 0)
89			{ /* slave now unlocked */
90			ttydev = strdup (ptsname (pfd)); / get slave's name */
91			return pfd;
92			}
93	root	1.1
94	root	1.2	close (pfd);
95			}
96
97			return -1;
98			}
99			#elif defined(HAVE_OPENPTY)
100			static int
101			get_pty (int fd_tty, char *ttydev)
102			{
103			int pfd;
104			int res;
105			char tty_name[32];
106
107			res = openpty (&pfd, fd_tty, tty_name, NULL, NULL);
108			if (res != -1)
109	root	1.1	{
110			*ttydev = strdup (tty_name);
111			return pfd;
112			}
113
114	root	1.2	return -1;
115			}
116			#elif defined(HAVE__GETPTY)
117			static int
118			get_pty (int fd_tty, char *ttydev)
119			{
120			int pfd;
121
122	root	1.1	*ttydev = _getpty (&pfd, O_RDWR \| O_NONBLOCK \| O_NOCTTY, 0622, 0);
123			if (*ttydev != NULL)
124			return pfd;
125
126	root	1.2	return -1;
127			}
128			#elif defined(HAVE_DEV_PTC)
129			static int
130			get_pty (int fd_tty, char *ttydev)
131			{
132			int pfd;
133	root	1.1
134			if ((pfd = open ("/dev/ptc", O_RDWR \| O_NOCTTY, 0)) >= 0)
135			{
136			*ttydev = strdup (ttyname (pfd));
137			return pfd;
138			}
139
140	root	1.2	return -1;
141			}
142			#elif defined(HAVE_DEV_CLONE)
143			static int
144			get_pty (int fd_tty, char *ttydev)
145			{
146			int pfd;
147
148	root	1.1	if ((pfd = open ("/dev/ptym/clone", O_RDWR \| O_NOCTTY, 0)) >= 0)
149			{
150			*ttydev = strdup (ptsname (pfd));
151			return pfd;
152			}
153
154	root	1.2	return -1;
155			}
156			#else
157			/* Based on the code in openssh/openbsd-compat/bsd-openpty.c */
158			static int
159			get_pty (int fd_tty, char *ttydev)
160			{
161			int pfd;
162			int i;
163			char pty_name[32];
164			char tty_name[32];
165			const char *majors = "pqrstuvwxyzabcde";
166			const char *minors = "0123456789abcdef";
167			for (i = 0; i < 256; i++)
168			{
169			snprintf(pty_name, 32, "/dev/pty%c%c", majors[i / 16], minors[i % 16]);
170			snprintf(tty_name, 32, "/dev/tty%c%c", majors[i / 16], minors[i % 16]);
171			if ((pfd = open (pty_name, O_RDWR \| O_NOCTTY, 0)) == -1)
172			{
173			snprintf(pty_name, 32, "/dev/ptyp%d", i);
174			snprintf(tty_name, 32, "/dev/ttyp%d", i);
175			if ((pfd = open (pty_name, O_RDWR \| O_NOCTTY, 0)) == -1)
176			continue;
177			}
178			if (access (tty_name, R_OK \| W_OK) == 0)
179			{
180			*ttydev = strdup (tty_name);
181			return pfd;
182			}
183	root	1.1
184	root	1.2	close (pfd);
185			}
186			}
187	root	1.1	#endif
188
189			/----------------------------------------------------------------------/
190			/*
191			* Returns tty file descriptor, or -1 on failure
192			*/
193			static int
194			get_tty (char *ttydev)
195			{
196			return open (ttydev, O_RDWR \| O_NOCTTY, 0);
197			}
198
199			/----------------------------------------------------------------------/
200			/*
201			* Make our tty a controlling tty so that /dev/tty points to us
202			*/
203			static int
204	root	1.2	control_tty (int fd_tty)
205	root	1.1	{
206			setsid ();
207
208	root	1.2	#if defined(HAVE_DEV_PTMX) && defined(I_PUSH)
209	root	1.1	/*
210			* Push STREAMS modules:
211			* ptem: pseudo-terminal hardware emulation module.
212			* ldterm: standard terminal line discipline.
213			* ttcompat: V7, 4BSD and XENIX STREAMS compatibility module.
214			*
215			* After we push the STREAMS modules, the first open () on the slave side
216			* (i.e. the next section between the dashes giving us "tty opened OK")
217			* should make the "ptem" (or "ldterm" depending upon either which OS
218			* version or which set of manual pages you have) module give us a
219			* controlling terminal. We must already have close ()d the master side
220			* fd in this child process before we push STREAMS modules on because the
221			* documentation is really unclear about whether it is any close () on
222			* the master side or the last close () - i.e. a proper STREAMS dismantling
223			* close () - on the master side which causes a hang up to be sent
224			* through - Geoff Wing
225			*/
226			# ifdef HAVE_ISASTREAM
227			if (isastream (fd_tty) == 1)
228			# endif
229			{
230			ioctl (fd_tty, I_PUSH, "ptem");
231			ioctl (fd_tty, I_PUSH, "ldterm");
232			ioctl (fd_tty, I_PUSH, "ttcompat");
233			}
234			#endif
235	root	1.2
236			ioctl (fd_tty, TIOCSCTTY, NULL);
237
238			int fd = open ("/dev/tty", O_WRONLY);
239	root	1.1	if (fd < 0)
240	root	1.10	return -1; /* fatal */
241	root	1.2
242	root	1.1	close (fd);
243
244			return 0;
245			}
246
247	root	1.2	void
248	root	1.4	ptytty::close_tty ()
249	root	1.2	{
250			if (tty < 0)
251			return;
252
253			close (tty);
254			tty = -1;
255			}
256
257			bool
258	root	1.4	ptytty::make_controlling_tty ()
259	root	1.2	{
260			return control_tty (tty) >= 0;
261			}
262
263			void
264	root	1.4	ptytty::set_utf8_mode (bool on)
265	root	1.2	{
266			#ifdef IUTF8
267			if (pty < 0)
268			return;
269
270			struct termios tio;
271
272			if (tcgetattr (pty, &tio) != -1)
273			{
274			tcflag_t new_cflag = tio.c_iflag;
275
276			if (on)
277			new_cflag \|= IUTF8;
278			else
279			new_cflag &= ~IUTF8;
280
281			if (new_cflag != tio.c_iflag)
282			{
283			tio.c_iflag = new_cflag;
284			tcsetattr (pty, TCSANOW, &tio);
285			}
286			}
287			#endif
288			}
289
290	root	1.1	static struct ttyconf {
291			gid_t gid;
292			mode_t mode;
293
294			ttyconf ()
295			{
296			#ifdef TTY_GID_SUPPORT
297			struct group *gr = getgrnam ("tty");
298
299			if (gr)
300			{ /* change group ownership of tty to "tty" */
301			mode = S_IRUSR \| S_IWUSR \| S_IWGRP;
302			gid = gr->gr_gid;
303			}
304			else
305			#endif /* TTY_GID_SUPPORT */
306			{
307			mode = S_IRUSR \| S_IWUSR \| S_IWGRP \| S_IWOTH;
308	root	1.2	gid = 0;
309	root	1.1	}
310			}
311			} ttyconf;
312
313	root	1.4	ptytty_unix::ptytty_unix ()
314	root	1.1	{
315			name = 0;
316	root	1.2	#if UTMP_SUPPORT
317			cmd_pid = 0;
318	root	1.1	#endif
319			}
320
321	root	1.4	ptytty_unix::~ptytty_unix ()
322	root	1.1	{
323	root	1.2	#if UTMP_SUPPORT
324			logout ();
325			#endif
326	root	1.1	put ();
327			}
328
329			void
330	root	1.4	ptytty_unix::put ()
331	root	1.2	{
332			chmod (name, RESTORE_TTY_MODE);
333			chown (name, 0, ttyconf.gid);
334	root	1.1
335	root	1.2	close_tty ();
336	root	1.1
337	root	1.2	if (pty >= 0)
338			close (pty);
339	root	1.1
340			free (name);
341
342			pty = tty = -1;
343			name = 0;
344			}
345
346			bool
347	root	1.4	ptytty_unix::get ()
348	root	1.1	{
349			/* get master (pty) */
350			if ((pty = get_pty (&tty, &name)) < 0)
351			return false;
352
353			fcntl (pty, F_SETFL, O_NONBLOCK);
354
355			/* get slave (tty) */
356			if (tty < 0)
357			{
358			#ifndef NO_SETOWNER_TTYDEV
359	root	1.2	chown (name, getuid (), ttyconf.gid); /* fail silently */
360			chmod (name, ttyconf.mode);
361			# ifdef HAVE_REVOKE
362			revoke (name);
363			# endif
364	root	1.1	#endif
365
366			if ((tty = get_tty (name)) < 0)
367			{
368			put ();
369			return false;
370			}
371			}
372
373			return true;
374			}
375
376	root	1.14	/////////////////////////////////////////////////////////////////////////////
377			// helper/proxy support
378
379	root	1.2	#if PTYTTY_HELPER
380
381	root	1.9	static int sock_fd = -1;
382			static int helper_pid, owner_pid;
383	root	1.2
384			struct command
385			{
386			enum { get, login, destroy } type;
387
388	root	1.4	ptytty *id;
389	root	1.2
390			bool login_shell;
391			int cmd_pid;
392			char hostname[512]; // arbitrary, but should be plenty
393			};
394
395	root	1.6	struct ptytty_proxy : ptytty
396	root	1.2	{
397	root	1.4	ptytty *id;
398	root	1.2
399	root	1.7	ptytty_proxy ()
400	root	1.6	: id(0)
401			{
402			}
403
404	root	1.4	~ptytty_proxy ();
405	root	1.2
406			bool get ();
407			void login (int cmd_pid, bool login_shell, const char *hostname);
408			};
409
410			bool
411	root	1.4	ptytty_proxy::get ()
412	root	1.2	{
413			command cmd;
414
415			cmd.type = command::get;
416
417			write (sock_fd, &cmd, sizeof (cmd));
418
419			if (read (sock_fd, &id, sizeof (id)) != sizeof (id))
420	root	1.10	ptytty_fatal ("protocol error while creating pty using helper process, aborting.\n");
421	root	1.2
422			if (!id)
423			return false;
424
425	root	1.9	if ((pty = recv_fd (sock_fd)) < 0
426			\|\| (tty = recv_fd (sock_fd)) < 0)
427	root	1.10	ptytty_fatal ("protocol error while reading pty/tty fds from helper process, aborting.\n");
428	root	1.2
429			return true;
430			}
431
432	root	1.1	void
433	root	1.4	ptytty_proxy::login (int cmd_pid, bool login_shell, const char *hostname)
434	root	1.2	{
435			command cmd;
436
437			cmd.type = command::login;
438			cmd.id = id;
439			cmd.cmd_pid = cmd_pid;
440			cmd.login_shell = login_shell;
441			strncpy (cmd.hostname, hostname, sizeof (cmd.hostname));
442
443			write (sock_fd, &cmd, sizeof (cmd));
444			}
445
446	root	1.4	ptytty_proxy::~ptytty_proxy ()
447	root	1.2	{
448	root	1.6	if (id)
449			{
450			command cmd;
451	root	1.2
452	root	1.6	cmd.type = command::destroy;
453			cmd.id = id;
454	root	1.2
455	root	1.6	write (sock_fd, &cmd, sizeof (cmd));
456			}
457	root	1.2	}
458
459			static
460			void serve ()
461	root	1.1	{
462	root	1.2	command cmd;
463	root	1.4	vector<ptytty *> ptys;
464	root	1.2
465			while (read (sock_fd, &cmd, sizeof (command)) == sizeof (command))
466	root	1.1	{
467	root	1.2	if (cmd.type == command::get)
468			{
469			// -> id ptyfd ttyfd
470	root	1.4	cmd.id = new ptytty_unix;
471	root	1.1
472	root	1.2	if (cmd.id->get ())
473			{
474			write (sock_fd, &cmd.id, sizeof (cmd.id));
475			ptys.push_back (cmd.id);
476	root	1.1
477	root	1.9	ptytty::send_fd (sock_fd, cmd.id->pty);
478			ptytty::send_fd (sock_fd, cmd.id->tty);
479	root	1.2	}
480	root	1.1	else
481	root	1.2	{
482			delete cmd.id;
483			cmd.id = 0;
484			write (sock_fd, &cmd.id, sizeof (cmd.id));
485			}
486			}
487			else if (cmd.type == command::login)
488			{
489			#if UTMP_SUPPORT
490	root	1.13	if (find (ptys.begin (), ptys.end (), cmd.id) != ptys.end ())
491	root	1.2	{
492			cmd.hostname[sizeof (cmd.hostname) - 1] = 0;
493			cmd.id->login (cmd.cmd_pid, cmd.login_shell, cmd.hostname);
494			}
495			#endif
496			}
497			else if (cmd.type == command::destroy)
498			{
499	root	1.9	vector<ptytty *>::iterator pty = find (ptys.begin (), ptys.end (), cmd.id);
500	root	1.1
501	root	1.9	if (pty != ptys.end ())
502	root	1.1	{
503	root	1.2	delete *pty;
504			ptys.erase (pty);
505	root	1.1	}
506			}
507	root	1.2	else
508			break;
509	root	1.1	}
510	root	1.2
511			// destroy all ptys
512	root	1.9	for (vector<ptytty *>::iterator i = ptys.end (); i-- > ptys.begin (); )
513	root	1.2	delete *i;
514			}
515
516	root	1.9	void
517			ptytty::use_helper ()
518	root	1.2	{
519	root	1.9	int pid = getpid ();
520
521			if (sock_fd >= 0 && pid == owner_pid)
522			return;
523
524			owner_pid = pid;
525
526	root	1.2	int sv[2];
527
528			if (socketpair (AF_UNIX, SOCK_STREAM, 0, sv))
529	root	1.10	ptytty_fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n");
530	root	1.2
531	root	1.9	helper_pid = fork ();
532	root	1.2
533	root	1.9	if (helper_pid < 0)
534	root	1.10	ptytty_fatal ("could not create pty/sessiondb helper process, aborting.\n");
535	root	1.2
536	root	1.9	if (helper_pid)
537	root	1.2	{
538	root	1.5	// client, process
539	root	1.2	sock_fd = sv[0];
540			close (sv[1]);
541			fcntl (sock_fd, F_SETFD, FD_CLOEXEC);
542			}
543			else
544			{
545			// server, pty-helper
546			sock_fd = sv[1];
547
548	root	1.9	chdir ("/");
549
550	root	1.2	for (int fd = 0; fd < 1023; fd++)
551			if (fd != sock_fd)
552			close (fd);
553
554			serve ();
555			_exit (EXIT_SUCCESS);
556			}
557			}
558
559			#endif
560
561	root	1.4	ptytty *
562	root	1.9	ptytty::create ()
563	root	1.2	{
564			#if PTYTTY_HELPER
565	root	1.9	if (helper_pid && getpid () == owner_pid)
566	root	1.2	// use helper process
567	root	1.4	return new ptytty_proxy;
568	root	1.2	else
569	root	1.1	#endif
570	root	1.4	return new ptytty_unix;
571	root	1.1	}
572
573	root	1.10	void
574			ptytty::init ()
575			{
576			uid_t uid = getuid ();
577			gid_t gid = getgid ();
578
579			// before doing anything else, check for setuid/setgid operation,
580			// start the helper process and drop privileges
581			if (uid != geteuid ()
582			\|\| gid != getegid ())
583			{
584			#if PTYTTY_HELPER
585			use_helper ();
586			#else
587			ptytty_warn ("running setuid/setgid without pty helper compiled in, continuing unprivileged.\n");
588			#endif
589
590			drop_privileges ();
591			}
592			}
593
594			void
595			ptytty::drop_privileges ()
596			{
597			uid_t uid = getuid ();
598			gid_t gid = getgid ();
599
600			// drop privileges
601			#if HAVE_SETRESUID
602			setresgid (gid, gid, gid);
603			setresuid (uid, uid, uid);
604			#elif HAVE_SETREUID
605			setregid (gid, gid);
606			setreuid (uid, uid);
607			#elif HAVE_SETUID
608			setgid (gid);
609			setuid (uid);
610			#endif
611
612			if (uid != geteuid ()
613			\|\| gid != getegid ())
614			ptytty_fatal ("unable to drop privileges, aborting.\n");
615			}
616	root	1.1
617	root	1.14	/////////////////////////////////////////////////////////////////////////////
618			// C API
619
620	root	1.15	#ifndef NO_C_API
621
622	root	1.14	#define DEFINE_METHOD(retval, name, args1, args2) \
623			extern "C" retval ptytty_ ## name args1 \
624			{ return ((struct ptytty *)ptytty)->name args2; }
625
626			DEFINE_METHOD(int,pty,(void *ptytty),)
627			DEFINE_METHOD(int,tty,(void *ptytty),)
628			DEFINE_METHOD(int,get,(void *ptytty),())
629			DEFINE_METHOD(void,login,(void ptytty, int cmd_pid, bool login_shell, const char hostname),(cmd_pid,login_shell,hostname))
630
631			DEFINE_METHOD(void,close_tty,(void *ptytty),())
632			DEFINE_METHOD(int,make_controlling_tty,(void *ptytty),())
633			DEFINE_METHOD(void,set_utf8_mode,(void *ptytty, int on),(on))
634
635			#define DEFINE_STATIC(retval, name, args) \
636			extern "C" retval ptytty_ ## name args \
637			{ return ptytty::name args; }
638
639	root	1.16	DEFINE_STATIC(void,drop_privileges,())
640			DEFINE_STATIC(void,use_helper,())
641
642	root	1.14	DEFINE_STATIC(void,init,())
643			DEFINE_STATIC(void *,create,())
644
645			void ptytty_delete (void *ptytty)
646			{
647			delete (struct ptytty *)ptytty;
648			}
649
650	root	1.16	// send_fd, recv_fd not exposed
651	root	1.14
652	root	1.15	#endif