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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.
*
* $FreeBSD$
*/
/*
* There are three cases in which the file system will clear the setuid or
* setgid bits on a file when running as !root:
*
* - When the file is chown()'d and either of the uid or the gid is changed.
*
* - The file is written to succeesfully.
*
* - An extended attribute of the file is written to successfully.
*
* Test each case first as root (that flags aren't cleared), and then as
* !root, to check they are cleared.
*/
#include <sys/types.h>
#include <sys/extattr.h>
#include <sys/stat.h>
#include <err.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "main.h"
static const gid_t gidset[] = {GID_WHEEL, GID_OWNER, GID_OTHER};
/*
* Confirm that the setuid bit is set on a file. Don't return on failure.
*/
static void
confirm_setuid(char *fpathp, char *test_case)
{
struct stat sb;
if (stat(fpathp, &sb) < 0) {
warn("%s stat(%s)", test_case, fpathp);
(void)seteuid(UID_ROOT);
(void)unlink(fpathp);
exit(-1);
}
if (!(sb.st_mode & S_ISUID)) {
warnx("case %s stat(%s) not setuid", test_case, fpathp);
(void)seteuid(UID_ROOT);
(void)unlink(fpathp);
exit(-1);
}
}
/*
* Confirm that the setuid bit is not set on a file. Don't return on failure.
*/
static void
confirm_notsetuid(char *fpathp, char *test_case)
{
struct stat sb;
if (stat(fpathp, &sb) < 0) {
warn("%s stat(%s)", test_case, fpathp);
(void)seteuid(UID_ROOT);
(void)unlink(fpathp);
exit(-1);
}
if (sb.st_mode & S_ISUID) {
warnx("case %s stat(%s) is setuid", test_case, fpathp);
(void)seteuid(UID_ROOT);
(void)unlink(fpathp);
exit(-1);
}
}
#define EA_NAMESPACE EXTATTR_NAMESPACE_USER
#define EA_NAME "clearsugid"
#define EA_DATA "test"
#define EA_SIZE (strlen(EA_DATA))
void
priv_vfs_clearsugid(void)
{
char ch, fpath[1024];
int fd;
assert_root();
/*
* Before starting on work, set up group IDs so that the process can
* change the group ID of the file without privilege, in order to see
* the effects. That way privilege is only required to maintain the
* setuid bit. For the chown() test, we change only the group id, as
* that can be done with or without privilege.
*/
if (setgroups(3, gidset) < 0)
err(-1, "setgroups(2, {%d, %d})", GID_WHEEL, GID_OWNER);
/*
* chown() with privilege.
*/
setup_file(fpath, UID_ROOT, GID_WHEEL, 0600 | S_ISUID);
if (chown(fpath, -1, GID_OTHER) < 0)
warn("chown(%s, -1, %d) as root", fpath, GID_OTHER);
confirm_setuid(fpath, "chown as root");
(void)unlink(fpath);
/*
* write() with privilege.
*/
setup_file(fpath, UID_ROOT, GID_WHEEL, 0600 | S_ISUID);
fd = open(fpath, O_RDWR);
if (fd < 0) {
warn("open(%s) as root", fpath);
goto out;
}
ch = 0;
if (write(fd, &ch, sizeof(ch)) < 0) {
warn("write(%s) as root", fpath);
goto out;
}
close(fd);
confirm_setuid(fpath, "write as root");
(void)unlink(fpath);
/*
* extwrite() with privilege.
*/
setup_file(fpath, UID_ROOT, GID_WHEEL, 0600 | S_ISUID);
if (extattr_set_file(fpath, EA_NAMESPACE, EA_NAME, EA_DATA, EA_SIZE)
< 0) {
warn("extattr_set_file(%s, user, %s, %s, %d) as root",
fpath, EA_NAME, EA_DATA, EA_SIZE);
goto out;
}
confirm_setuid(fpath, "extwrite as root");
(void)unlink(fpath);
/*
* chown() without privilege.
*/
setup_file(fpath, UID_OWNER, GID_OWNER, 0600 | S_ISUID);
set_euid(UID_OWNER);
if (chown(fpath, -1, GID_OTHER) < 0)
warn("chown(%s, -1, %d) as !root", fpath, GID_OTHER);
set_euid(UID_ROOT);
confirm_notsetuid(fpath, "chown as !root");
(void)unlink(fpath);
/*
* write() without privilege.
*/
setup_file(fpath, UID_OWNER, GID_OWNER, 0600 | S_ISUID);
set_euid(UID_OWNER);
fd = open(fpath, O_RDWR);
if (fd < 0) {
warn("open(%s) as !root", fpath);
goto out;
}
ch = 0;
if (write(fd, &ch, sizeof(ch)) < 0) {
warn("write(%s) as !root", fpath);
goto out;
}
close(fd);
set_euid(UID_ROOT);
confirm_notsetuid(fpath, "write as !root");
(void)unlink(fpath);
/*
* extwrite() without privilege.
*/
setup_file(fpath, UID_OWNER, GID_OWNER, 0600 | S_ISUID);
set_euid(UID_OWNER);
if (extattr_set_file(fpath, EA_NAMESPACE, EA_NAME, EA_DATA, EA_SIZE)
< 0) {
warn("extattr_set_file(%s, user, %s, %s, %d) as !root",
fpath, EA_NAME, EA_DATA, EA_SIZE);
goto out;
}
set_euid(UID_ROOT);
confirm_notsetuid(fpath, "extwrite as !root");
(void)unlink(fpath);
out:
(void)seteuid(UID_ROOT);
(void)unlink(fpath);
}
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