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d3951ad162
to Solaris, it is in /usr/libexec) to perform the handing over of tty nodes to the user being granted the pty. Submitted by: Ryan Younce <ryany@pobox.com> Reviewed by: security-officer@, standards@, mike@
104 lines
3.9 KiB
C
104 lines
3.9 KiB
C
/*
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* Copyright (c) 2002 The FreeBSD Project, Inc.
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* All rights reserved.
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*
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* This software includes code contributed to the FreeBSD Project
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* by Ryan Younce of North Carolina State University.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the FreeBSD Project nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE FREEBSD PROJECT AND CONTRIBUTORS ``AS IS''
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE FREEBSD PROJECT OR ITS CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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__FBSDID("$FreeBSD$");
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#endif /* not lint */
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#include <sys/stat.h>
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#include <grp.h>
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#include <stdlib.h>
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#include <sysexits.h>
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#include <unistd.h>
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/*
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* pt_chown
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* Utility support routine for grantpt(3).
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*
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* According to IEEE Std 1003.1-2001, grantpt(3) changes ownership and
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* permission bits of a slave pseudo-terminal device associated with a
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* master.
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*
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* Since doing this if we are not the owner of the slave (which would
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* rarely happen) cannot be done by conventional methods, grantpt(3)
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* has to rely on this support program, which is setuid root, to change
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* the slave's owner, group, and permission mode attributes. It's
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* a rather undesirable approach, but Digital Unix and Solaris also seem
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* to rely on this approach to pull this off.
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*
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* This program hangs around long enough to do just these things upon
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* its standard input (which is set up by grantpt(3) to be the master's
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* descriptor, the one passed to it). The rationale behind this
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* approach not allowing somebody to modify ownership of another active
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* pseudo terminal is:
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*
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* 1) This program only operates on its standard input. If STDIN_FILENO
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* is not open or is not a pseudo-terminal master, no action is
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* taken and the program exits (ptsname() is called for a non-NULL
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* return).
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* 2) Only one active file description for a pseudo-terminal master
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* can exist at a time (attempting to open an active PTY returns with
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* EIO - I/O Error). Thus, if the pseudo-terminal is already in
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* use by somebody else, it could not have been opened to begin
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* with, and thus this program would be useless in such situations.
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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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int retcode;
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char *slave;
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gid_t gid;
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struct group *grp;
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retcode = EX_OK;
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if ((slave = ptsname(STDIN_FILENO)) == NULL)
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retcode = EX_USAGE;
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else {
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gid = (grp = getgrnam("tty")) ? grp->gr_gid : -1;
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if (chown(slave, getuid(), gid) == 0 &&
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chmod(slave, S_IRUSR | S_IWUSR | S_IWGRP) == 0)
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retcode = 0;
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else
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retcode = EX_NOPERM;
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}
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/*
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* grantpt(3) checks the retcode for being either zero or
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* nonzero. Any nonzero return results in errno being set
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* to EACCES.
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*/
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exit(retcode);
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}
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