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/* Copyright (C) 1998 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by C. Scott Ananian <cananian@alumni.princeton.edu>, 1998.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
/* pt_chmod.c ... securely implement grantpt in user-land. */
#include <sys/stat.h>
#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <stdio.h>
#include <grp.h>
#include "pty-internal.h"
#define Str(x) _Str(x)
#define _Str(x) #x
void
usage (void)
{
fprintf (stderr, _("usage: pt_chown FD>&%s\n"
"This program is used internally by grantpt(3).\n"),
Str (PTY_FD));
exit (0);
}
void
bad_installation (void)
{
fputs (_("pt_chown: installation problem: "
"This program needs to be setuid root.\n"), stderr);
exit (FAIL_EXEC);
}
int
main (int argc, char **argv)
{
struct group *grp;
struct stat s;
char *pty;
gid_t gid;
uid_t uid;
if (argc != 1)
usage ();
if (geteuid () != 0)
bad_installation ();
grp = getgrnam (TTY_GROUP);
gid = grp ? grp->gr_gid : getgid ();
uid = getuid ();
/* Check that fd is a valid pty master -- call ptsname(). */
pty = ptsname (PTY_FD);
if (pty == NULL)
return errno == EBADF ? FAIL_EBADF : FAIL_EINVAL;
close (PTY_FD);
/* Check that target file is a character device. */
if (stat (pty, &s))
return FAIL_EINVAL; /* This should only fail if pty doesn't exist. */
if (!S_ISCHR (s.st_mode))
return FAIL_EINVAL;
if (chmod (pty, 0620))
return FAIL_EACCES; /* XXX: Probably not true. */
if (chown (pty, uid, gid))
return FAIL_EACCES;
return 0;
}
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