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/*
* Copyright (c) 2002 The FreeBSD Project, Inc.
* All rights reserved.
*
* This software includes code contributed to the FreeBSD Project
* by Ryan Younce of North Carolina State University.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the FreeBSD Project nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE FREEBSD PROJECT AND CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE FREEBSD PROJECT OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#ifndef lint
__FBSDID("$FreeBSD$");
#endif /* not lint */
#include <sys/stat.h>
#include <grp.h>
#include <stdlib.h>
#include <sysexits.h>
#include <unistd.h>
/*
* pt_chown
* Utility support routine for grantpt(3).
*
* According to IEEE Std 1003.1-2001, grantpt(3) changes ownership and
* permission bits of a slave pseudo-terminal device associated with a
* master.
*
* Since doing this if we are not the owner of the slave (which would
* rarely happen) cannot be done by conventional methods, grantpt(3)
* has to rely on this support program, which is setuid root, to change
* the slave's owner, group, and permission mode attributes. It's
* a rather undesirable approach, but Digital Unix and Solaris also seem
* to rely on this approach to pull this off.
*
* This program hangs around long enough to do just these things upon
* its standard input (which is set up by grantpt(3) to be the master's
* descriptor, the one passed to it). The rationale behind this
* approach not allowing somebody to modify ownership of another active
* pseudo terminal is:
*
* 1) This program only operates on its standard input. If STDIN_FILENO
* is not open or is not a pseudo-terminal master, no action is
* taken and the program exits (ptsname() is called for a non-NULL
* return).
* 2) Only one active file description for a pseudo-terminal master
* can exist at a time (attempting to open an active PTY returns with
* EIO - I/O Error). Thus, if the pseudo-terminal is already in
* use by somebody else, it could not have been opened to begin
* with, and thus this program would be useless in such situations.
*/
int
main(int argc, char *argv[])
{
int retcode;
char *slave;
gid_t gid;
struct group *grp;
retcode = EX_OK;
if ((slave = ptsname(STDIN_FILENO)) == NULL)
retcode = EX_USAGE;
else {
gid = (grp = getgrnam("tty")) ? grp->gr_gid : -1;
if (chown(slave, getuid(), gid) == 0 &&
chmod(slave, S_IRUSR | S_IWUSR | S_IWGRP) == 0)
retcode = 0;
else
retcode = EX_NOPERM;
}
/*
* grantpt(3) checks the retcode for being either zero or
* nonzero. Any nonzero return results in errno being set
* to EACCES.
*/
exit(retcode);
}
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