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/*-
* Copyright (c) 2006 nCircle Network Security, Inc.
* All rights reserved.
*
* This software was developed by Robert N. M. Watson for the TrustedBSD
* Project under contract to nCircle Network Security, Inc.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR, NCIRCLE NETWORK SECURITY,
* INC., OR 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.
*
* $FreeBSD$
*/
/*
* Confirm that privilege is required in the cases using chown():
*
* - If the process euid does not match the file uid.
*
* - If the target uid is different than the current uid.
*
* - If the target gid changes and we the process is not a member of the new
* group.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include "main.h"
const gid_t gidset[] = {GID_WHEEL, GID_OWNER};
void
priv_vfs_chown(void)
{
char fpath[1024];
int error;
assert_root();
/*
* Before beginning, set up group set for process. Place in wheel
* and owner groups; don't put in other group so that when we chown
* to the other group, it's as a non-member.
*/
if (setgroups(2, gidset) < 0)
err(-1, "setgroups(2, {%d, %d})", GID_WHEEL, GID_OWNER);
/*
* In the first pass, confirm that all works as desired with
* privilege.
*
* Check that chown when non-owner works fine. Do a no-op change to
* avoid other permission checks. Note that we can't request
* (-1, -1) and get an access control check, we have to request
* specific uid/gid that are not the same.
*/
setup_file(fpath, UID_OWNER, GID_OWNER, 0600);
if (chown(fpath, -1, GID_OWNER) < 0) {
warn("chown(%s, -1, %d) as root", fpath, GID_OWNER);
goto out;
}
(void)unlink(fpath);
/*
* Check that chown changing uid works with privilege.
*/
setup_file(fpath, UID_OWNER, GID_OWNER, 0600);
if (chown(fpath, UID_OTHER, -1) < 0) {
warn("chown(%s, %d, -1) as root", fpath, UID_OTHER);
goto out;
}
(void)unlink(fpath);
/*
* Check that can change the file group to one we are not a member of
* when running with privilege.
*/
setup_file(fpath, UID_OWNER, GID_OWNER, 0600);
if (chown(fpath, -1, GID_OTHER) < 0) {
warn("chown(%s, -1, %d) as root", fpath, GID_OTHER);
goto out;
}
(void)unlink(fpath);
/*
* Now, the same again, but without privilege.
*
* Confirm that we can't chown a file we don't own, even as a no-op.
*/
setup_file(fpath, UID_OWNER, GID_OWNER, 0600);
set_euid(UID_OTHER);
error = chown(fpath, -1, GID_OWNER);
if (error == 0) {
warnx("chown(%s, -1, %d) succeeded as !root, non-owner",
fpath, GID_OWNER);
goto out;
}
if (errno != EPERM) {
warn("chown(%s, -1, %d) wrong errno %d as !root, non-owner",
fpath, GID_OWNER, errno);
goto out;
}
set_euid(UID_ROOT);
(void)unlink(fpath);
/*
* Check that we can't change the uid of the file without privilege,
* even though we own the file.
*/
setup_file(fpath, UID_OWNER, GID_OWNER, 0600);
set_euid(UID_OWNER);
error = chown(fpath, UID_OTHER, -1);
if (error == 0) {
warnx("chown(%s, %d, -1) succeeded as !root", fpath,
UID_OTHER);
goto out;
}
if (errno != EPERM) {
warn("chown(%s, %d, -1) wrong errno %d as !root", fpath,
UID_OTHER, errno);
goto out;
}
set_euid(UID_ROOT);
(void)unlink(fpath);
/*
* Check that can't change the file group to one we are not a member
* of when running without privilege.
*/
setup_file(fpath, UID_OWNER, GID_OWNER, 0600);
set_euid(UID_OWNER);
error = chown(fpath, -1, GID_OTHER);
if (error == 0) {
warn("chown(%s, -1, %d) succeeded as !root", fpath, GID_OTHER);
goto out;
}
if (errno != EPERM) {
warn("chown(%s, -1, %d) wrong errno %d as !root", fpath,
errno, GID_OTHER);
goto out;
}
set_euid(UID_ROOT);
(void)unlink(fpath);
out:
(void)seteuid(UID_ROOT);
(void)unlink(fpath);
}
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