89 lines
2.3 KiB
C
89 lines
2.3 KiB
C
/* Copyright (C) 1998 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by C. Scott Ananian <cananian@alumni.princeton.edu>, 1998.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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/* pt_chmod.c ... securely implement grantpt in user-land. */
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <errno.h>
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#include <stdio.h>
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#include <grp.h>
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#include "pty-internal.h"
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#define Str(x) _Str(x)
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#define _Str(x) #x
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void
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usage (void)
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{
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fprintf (stderr, _("usage: pt_chown FD>&%s\n"
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"This program is used internally by grantpt(3).\n"),
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Str (PTY_FD));
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exit (0);
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}
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void
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bad_installation (void)
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{
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fputs (_("pt_chown: installation problem: "
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"This program needs to be setuid root.\n"), stderr);
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exit (FAIL_EXEC);
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}
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int
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main (int argc, char **argv)
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{
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struct group *grp;
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struct stat s;
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char *pty;
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gid_t gid;
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uid_t uid;
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if (argc != 1)
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usage ();
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if (geteuid () != 0)
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bad_installation ();
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grp = getgrnam (TTY_GROUP);
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gid = grp ? grp->gr_gid : getgid ();
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uid = getuid ();
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/* Check that fd is a valid pty master -- call ptsname(). */
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pty = ptsname (PTY_FD);
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if (pty == NULL)
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return errno == EBADF ? FAIL_EBADF : FAIL_EINVAL;
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close (PTY_FD);
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/* Check that target file is a character device. */
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if (stat (pty, &s))
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return FAIL_EINVAL; /* This should only fail if pty doesn't exist. */
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if (!S_ISCHR (s.st_mode))
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return FAIL_EINVAL;
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if (chmod (pty, 0620))
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return FAIL_EACCES; /* XXX: Probably not true. */
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if (chown (pty, uid, gid))
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return FAIL_EACCES;
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return 0;
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}
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