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>
 *
 * 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;
}

#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))
            {
              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");
}

Revision:	1.10
Committed:	Sun Jan 22 04:05:19 2006 UTC (18 years, 5 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.9:	+48 -5 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	1.1	*
12			* This program is free software; you can redistribute it and/or modify
13			* it under the terms of the GNU General Public License as published by
14			* the Free Software Foundation; either version 2 of the License, or
15			* (at your option) any later version.
16			*
17			* This program is distributed in the hope that it will be useful,
18			* but WITHOUT ANY WARRANTY; without even the implied warranty of
19			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20			* GNU General Public License for more details.
21			*
22			* You should have received a copy of the GNU General Public License
23			* along with this program; if not, write to the Free Software
24			* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
25			---------------------------------------------------------------------/
26
27	root	1.8	#include "../config.h"
28	root	1.1
29	root	1.3	#include "ptytty.h"
30
31	root	1.2	#include <cstdlib>
32			#include <cstring>
33
34			#include <sys/types.h>
35			#include <sys/socket.h>
36			#include <unistd.h>
37			#include <fcntl.h>
38
39	root	1.1	#ifdef HAVE_SYS_IOCTL_H
40			# include <sys/ioctl.h>
41			#endif
42	root	1.2	#if defined(HAVE_DEV_PTMX) && defined(HAVE_SYS_STROPTS_H)
43	root	1.1	# include <sys/stropts.h> /* for I_PUSH */
44			#endif
45			#ifdef HAVE_ISASTREAM
46			# include <stropts.h>
47			#endif
48	root	1.2	#if defined(HAVE_PTY_H)
49	root	1.1	# include <pty.h>
50	root	1.2	#elif defined(HAVE_LIBUTIL_H)
51	root	1.1	# include <libutil.h>
52	root	1.2	#elif defined(HAVE_UTIL_H)
53	root	1.1	# include <util.h>
54			#endif
55	root	1.2	#ifdef TTY_GID_SUPPORT
56			#include <grp.h>
57			#endif
58	root	1.1
59			#include <cstdio>
60	root	1.2
61			/////////////////////////////////////////////////////////////////////////////
62	root	1.1
63			/* ------------------------------------------------------------------------- *
64			* GET PSEUDO TELETYPE - MASTER AND SLAVE *
65			* ------------------------------------------------------------------------- */
66			/*
67			* Returns pty file descriptor, or -1 on failure
68			* If successful, ttydev is set to the name of the slave device.
69			* fd_tty _may_ also be set to an open fd to the slave device
70			*/
71	root	1.2	#if defined(UNIX98_PTY)
72	root	1.1	static int
73			get_pty (int fd_tty, char *ttydev)
74			{
75			int pfd;
76
77	root	1.2	# if defined(HAVE_GETPT)
78			pfd = getpt();
79			# elif defined(HAVE_POSIX_OPENPT)
80			pfd = posix_openpt (O_RDWR);
81			# else
82			pfd = open (CLONE_DEVICE, O_RDWR \| O_NOCTTY, 0);
83			# endif
84			if (pfd >= 0)
85			{
86			if (grantpt (pfd) == 0 /* change slave permissions */
87			&& unlockpt (pfd) == 0)
88			{ /* slave now unlocked */
89			ttydev = strdup (ptsname (pfd)); / get slave's name */
90			return pfd;
91			}
92	root	1.1
93	root	1.2	close (pfd);
94			}
95
96			return -1;
97			}
98			#elif defined(HAVE_OPENPTY)
99			static int
100			get_pty (int fd_tty, char *ttydev)
101			{
102			int pfd;
103			int res;
104			char tty_name[32];
105
106			res = openpty (&pfd, fd_tty, tty_name, NULL, NULL);
107			if (res != -1)
108	root	1.1	{
109			*ttydev = strdup (tty_name);
110			return pfd;
111			}
112
113	root	1.2	return -1;
114			}
115			#elif defined(HAVE__GETPTY)
116			static int
117			get_pty (int fd_tty, char *ttydev)
118			{
119			int pfd;
120
121	root	1.1	*ttydev = _getpty (&pfd, O_RDWR \| O_NONBLOCK \| O_NOCTTY, 0622, 0);
122			if (*ttydev != NULL)
123			return pfd;
124
125	root	1.2	return -1;
126			}
127			#elif defined(HAVE_DEV_PTC)
128			static int
129			get_pty (int fd_tty, char *ttydev)
130			{
131			int pfd;
132	root	1.1
133			if ((pfd = open ("/dev/ptc", O_RDWR \| O_NOCTTY, 0)) >= 0)
134			{
135			*ttydev = strdup (ttyname (pfd));
136			return pfd;
137			}
138
139	root	1.2	return -1;
140			}
141			#elif defined(HAVE_DEV_CLONE)
142			static int
143			get_pty (int fd_tty, char *ttydev)
144			{
145			int pfd;
146
147	root	1.1	if ((pfd = open ("/dev/ptym/clone", O_RDWR \| O_NOCTTY, 0)) >= 0)
148			{
149			*ttydev = strdup (ptsname (pfd));
150			return pfd;
151			}
152
153	root	1.2	return -1;
154			}
155			#else
156			/* Based on the code in openssh/openbsd-compat/bsd-openpty.c */
157			static int
158			get_pty (int fd_tty, char *ttydev)
159			{
160			int pfd;
161			int i;
162			char pty_name[32];
163			char tty_name[32];
164			const char *majors = "pqrstuvwxyzabcde";
165			const char *minors = "0123456789abcdef";
166			for (i = 0; i < 256; i++)
167			{
168			snprintf(pty_name, 32, "/dev/pty%c%c", majors[i / 16], minors[i % 16]);
169			snprintf(tty_name, 32, "/dev/tty%c%c", majors[i / 16], minors[i % 16]);
170			if ((pfd = open (pty_name, O_RDWR \| O_NOCTTY, 0)) == -1)
171			{
172			snprintf(pty_name, 32, "/dev/ptyp%d", i);
173			snprintf(tty_name, 32, "/dev/ttyp%d", i);
174			if ((pfd = open (pty_name, O_RDWR \| O_NOCTTY, 0)) == -1)
175			continue;
176			}
177			if (access (tty_name, R_OK \| W_OK) == 0)
178			{
179			*ttydev = strdup (tty_name);
180			return pfd;
181			}
182	root	1.1
183	root	1.2	close (pfd);
184			}
185			}
186	root	1.1	#endif
187
188			/----------------------------------------------------------------------/
189			/*
190			* Returns tty file descriptor, or -1 on failure
191			*/
192			static int
193			get_tty (char *ttydev)
194			{
195			return open (ttydev, O_RDWR \| O_NOCTTY, 0);
196			}
197
198			/----------------------------------------------------------------------/
199			/*
200			* Make our tty a controlling tty so that /dev/tty points to us
201			*/
202			static int
203	root	1.2	control_tty (int fd_tty)
204	root	1.1	{
205			setsid ();
206
207	root	1.2	#if defined(HAVE_DEV_PTMX) && defined(I_PUSH)
208	root	1.1	/*
209			* Push STREAMS modules:
210			* ptem: pseudo-terminal hardware emulation module.
211			* ldterm: standard terminal line discipline.
212			* ttcompat: V7, 4BSD and XENIX STREAMS compatibility module.
213			*
214			* After we push the STREAMS modules, the first open () on the slave side
215			* (i.e. the next section between the dashes giving us "tty opened OK")
216			* should make the "ptem" (or "ldterm" depending upon either which OS
217			* version or which set of manual pages you have) module give us a
218			* controlling terminal. We must already have close ()d the master side
219			* fd in this child process before we push STREAMS modules on because the
220			* documentation is really unclear about whether it is any close () on
221			* the master side or the last close () - i.e. a proper STREAMS dismantling
222			* close () - on the master side which causes a hang up to be sent
223			* through - Geoff Wing
224			*/
225			# ifdef HAVE_ISASTREAM
226			if (isastream (fd_tty) == 1)
227			# endif
228			{
229			ioctl (fd_tty, I_PUSH, "ptem");
230			ioctl (fd_tty, I_PUSH, "ldterm");
231			ioctl (fd_tty, I_PUSH, "ttcompat");
232			}
233			#endif
234	root	1.2
235			ioctl (fd_tty, TIOCSCTTY, NULL);
236
237			int fd = open ("/dev/tty", O_WRONLY);
238	root	1.1	if (fd < 0)
239	root	1.10	return -1; /* fatal */
240	root	1.2
241	root	1.1	close (fd);
242
243			return 0;
244			}
245
246	root	1.2	void
247	root	1.4	ptytty::close_tty ()
248	root	1.2	{
249			if (tty < 0)
250			return;
251
252			close (tty);
253			tty = -1;
254			}
255
256			bool
257	root	1.4	ptytty::make_controlling_tty ()
258	root	1.2	{
259			return control_tty (tty) >= 0;
260			}
261
262			void
263	root	1.4	ptytty::set_utf8_mode (bool on)
264	root	1.2	{
265			#ifdef IUTF8
266			if (pty < 0)
267			return;
268
269			struct termios tio;
270
271			if (tcgetattr (pty, &tio) != -1)
272			{
273			tcflag_t new_cflag = tio.c_iflag;
274
275			if (on)
276			new_cflag \|= IUTF8;
277			else
278			new_cflag &= ~IUTF8;
279
280			if (new_cflag != tio.c_iflag)
281			{
282			tio.c_iflag = new_cflag;
283			tcsetattr (pty, TCSANOW, &tio);
284			}
285			}
286			#endif
287			}
288
289	root	1.1	static struct ttyconf {
290			gid_t gid;
291			mode_t mode;
292
293			ttyconf ()
294			{
295			#ifdef TTY_GID_SUPPORT
296			struct group *gr = getgrnam ("tty");
297
298			if (gr)
299			{ /* change group ownership of tty to "tty" */
300			mode = S_IRUSR \| S_IWUSR \| S_IWGRP;
301			gid = gr->gr_gid;
302			}
303			else
304			#endif /* TTY_GID_SUPPORT */
305			{
306			mode = S_IRUSR \| S_IWUSR \| S_IWGRP \| S_IWOTH;
307	root	1.2	gid = 0;
308	root	1.1	}
309			}
310			} ttyconf;
311
312	root	1.4	ptytty_unix::ptytty_unix ()
313	root	1.1	{
314			name = 0;
315	root	1.2	#if UTMP_SUPPORT
316			cmd_pid = 0;
317	root	1.1	#endif
318			}
319
320	root	1.4	ptytty_unix::~ptytty_unix ()
321	root	1.1	{
322	root	1.2	#if UTMP_SUPPORT
323			logout ();
324			#endif
325	root	1.1	put ();
326			}
327
328			void
329	root	1.4	ptytty_unix::put ()
330	root	1.2	{
331			chmod (name, RESTORE_TTY_MODE);
332			chown (name, 0, ttyconf.gid);
333	root	1.1
334	root	1.2	close_tty ();
335	root	1.1
336	root	1.2	if (pty >= 0)
337			close (pty);
338	root	1.1
339			free (name);
340
341			pty = tty = -1;
342			name = 0;
343			}
344
345			bool
346	root	1.4	ptytty_unix::get ()
347	root	1.1	{
348			/* get master (pty) */
349			if ((pty = get_pty (&tty, &name)) < 0)
350			return false;
351
352			fcntl (pty, F_SETFL, O_NONBLOCK);
353
354			/* get slave (tty) */
355			if (tty < 0)
356			{
357			#ifndef NO_SETOWNER_TTYDEV
358	root	1.2	chown (name, getuid (), ttyconf.gid); /* fail silently */
359			chmod (name, ttyconf.mode);
360			# ifdef HAVE_REVOKE
361			revoke (name);
362			# endif
363	root	1.1	#endif
364
365			if ((tty = get_tty (name)) < 0)
366			{
367			put ();
368			return false;
369			}
370			}
371
372			return true;
373			}
374
375	root	1.2	#if PTYTTY_HELPER
376
377	root	1.9	static int sock_fd = -1;
378			static int helper_pid, owner_pid;
379	root	1.2
380			struct command
381			{
382			enum { get, login, destroy } type;
383
384	root	1.4	ptytty *id;
385	root	1.2
386			bool login_shell;
387			int cmd_pid;
388			char hostname[512]; // arbitrary, but should be plenty
389			};
390
391	root	1.6	struct ptytty_proxy : ptytty
392	root	1.2	{
393	root	1.4	ptytty *id;
394	root	1.2
395	root	1.7	ptytty_proxy ()
396	root	1.6	: id(0)
397			{
398			}
399
400	root	1.4	~ptytty_proxy ();
401	root	1.2
402			bool get ();
403			void login (int cmd_pid, bool login_shell, const char *hostname);
404			};
405
406			bool
407	root	1.4	ptytty_proxy::get ()
408	root	1.2	{
409			command cmd;
410
411			cmd.type = command::get;
412
413			write (sock_fd, &cmd, sizeof (cmd));
414
415			if (read (sock_fd, &id, sizeof (id)) != sizeof (id))
416	root	1.10	ptytty_fatal ("protocol error while creating pty using helper process, aborting.\n");
417	root	1.2
418			if (!id)
419			return false;
420
421	root	1.9	if ((pty = recv_fd (sock_fd)) < 0
422			\|\| (tty = recv_fd (sock_fd)) < 0)
423	root	1.10	ptytty_fatal ("protocol error while reading pty/tty fds from helper process, aborting.\n");
424	root	1.2
425			return true;
426			}
427
428	root	1.1	void
429	root	1.4	ptytty_proxy::login (int cmd_pid, bool login_shell, const char *hostname)
430	root	1.2	{
431			command cmd;
432
433			cmd.type = command::login;
434			cmd.id = id;
435			cmd.cmd_pid = cmd_pid;
436			cmd.login_shell = login_shell;
437			strncpy (cmd.hostname, hostname, sizeof (cmd.hostname));
438
439			write (sock_fd, &cmd, sizeof (cmd));
440			}
441
442	root	1.4	ptytty_proxy::~ptytty_proxy ()
443	root	1.2	{
444	root	1.6	if (id)
445			{
446			command cmd;
447	root	1.2
448	root	1.6	cmd.type = command::destroy;
449			cmd.id = id;
450	root	1.2
451	root	1.6	write (sock_fd, &cmd, sizeof (cmd));
452			}
453	root	1.2	}
454
455			static
456			void serve ()
457	root	1.1	{
458	root	1.2	command cmd;
459	root	1.4	vector<ptytty *> ptys;
460	root	1.2
461			while (read (sock_fd, &cmd, sizeof (command)) == sizeof (command))
462	root	1.1	{
463	root	1.2	if (cmd.type == command::get)
464			{
465			// -> id ptyfd ttyfd
466	root	1.4	cmd.id = new ptytty_unix;
467	root	1.1
468	root	1.2	if (cmd.id->get ())
469			{
470			write (sock_fd, &cmd.id, sizeof (cmd.id));
471			ptys.push_back (cmd.id);
472	root	1.1
473	root	1.9	ptytty::send_fd (sock_fd, cmd.id->pty);
474			ptytty::send_fd (sock_fd, cmd.id->tty);
475	root	1.2	}
476	root	1.1	else
477	root	1.2	{
478			delete cmd.id;
479			cmd.id = 0;
480			write (sock_fd, &cmd.id, sizeof (cmd.id));
481			}
482			}
483			else if (cmd.type == command::login)
484			{
485			#if UTMP_SUPPORT
486			if (find (ptys.begin (), ptys.end (), cmd.id))
487			{
488			cmd.hostname[sizeof (cmd.hostname) - 1] = 0;
489			cmd.id->login (cmd.cmd_pid, cmd.login_shell, cmd.hostname);
490			}
491			#endif
492			}
493			else if (cmd.type == command::destroy)
494			{
495	root	1.9	vector<ptytty *>::iterator pty = find (ptys.begin (), ptys.end (), cmd.id);
496	root	1.1
497	root	1.9	if (pty != ptys.end ())
498	root	1.1	{
499	root	1.2	delete *pty;
500			ptys.erase (pty);
501	root	1.1	}
502			}
503	root	1.2	else
504			break;
505	root	1.1	}
506	root	1.2
507			// destroy all ptys
508	root	1.9	for (vector<ptytty *>::iterator i = ptys.end (); i-- > ptys.begin (); )
509	root	1.2	delete *i;
510			}
511
512	root	1.9	void
513			ptytty::use_helper ()
514	root	1.2	{
515	root	1.9	int pid = getpid ();
516
517			if (sock_fd >= 0 && pid == owner_pid)
518			return;
519
520			owner_pid = pid;
521
522	root	1.2	int sv[2];
523
524			if (socketpair (AF_UNIX, SOCK_STREAM, 0, sv))
525	root	1.10	ptytty_fatal ("could not create socket to communicate with pty/sessiondb helper, aborting.\n");
526	root	1.2
527	root	1.9	helper_pid = fork ();
528	root	1.2
529	root	1.9	if (helper_pid < 0)
530	root	1.10	ptytty_fatal ("could not create pty/sessiondb helper process, aborting.\n");
531	root	1.2
532	root	1.9	if (helper_pid)
533	root	1.2	{
534	root	1.5	// client, process
535	root	1.2	sock_fd = sv[0];
536			close (sv[1]);
537			fcntl (sock_fd, F_SETFD, FD_CLOEXEC);
538			}
539			else
540			{
541			// server, pty-helper
542			sock_fd = sv[1];
543
544	root	1.9	chdir ("/");
545
546	root	1.2	for (int fd = 0; fd < 1023; fd++)
547			if (fd != sock_fd)
548			close (fd);
549
550			serve ();
551			_exit (EXIT_SUCCESS);
552			}
553			}
554
555			#endif
556
557	root	1.4	ptytty *
558	root	1.9	ptytty::create ()
559	root	1.2	{
560			#if PTYTTY_HELPER
561	root	1.9	if (helper_pid && getpid () == owner_pid)
562	root	1.2	// use helper process
563	root	1.4	return new ptytty_proxy;
564	root	1.2	else
565	root	1.1	#endif
566	root	1.4	return new ptytty_unix;
567	root	1.1	}
568
569	root	1.10	void
570			ptytty::init ()
571			{
572			uid_t uid = getuid ();
573			gid_t gid = getgid ();
574
575			// before doing anything else, check for setuid/setgid operation,
576			// start the helper process and drop privileges
577			if (uid != geteuid ()
578			\|\| gid != getegid ())
579			{
580			#if PTYTTY_HELPER
581			use_helper ();
582			#else
583			ptytty_warn ("running setuid/setgid without pty helper compiled in, continuing unprivileged.\n");
584			#endif
585
586			drop_privileges ();
587			}
588			}
589
590			void
591			ptytty::drop_privileges ()
592			{
593			uid_t uid = getuid ();
594			gid_t gid = getgid ();
595
596			// drop privileges
597			#if HAVE_SETRESUID
598			setresgid (gid, gid, gid);
599			setresuid (uid, uid, uid);
600			#elif HAVE_SETREUID
601			setregid (gid, gid);
602			setreuid (uid, uid);
603			#elif HAVE_SETUID
604			setgid (gid);
605			setuid (uid);
606			#endif
607
608			if (uid != geteuid ()
609			\|\| gid != getegid ())
610			ptytty_fatal ("unable to drop privileges, aborting.\n");
611			}
612	root	1.1