xref: /freebsd/tools/regression/priv/priv_vfs_clearsugid.c (revision b3e7694832e81d7a904a10f525f8797b753bf0d3)

/*-
 * Copyright (c) 2006 nCircle Network Security, Inc.
 * Copyright (c) 2007 Robert N. M. Watson
 * 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.
 */

/*
 * There are three cases in which the file system will clear the setuid or
 * setgid bits on a file when running unprivileged:
 *
 * - When the file is chown()'d and either of the uid or the gid is changed.
 *   (currently, only changing the file gid applies, as privilege is required
 *   to change the uid).
 *
 * - The file is written to successfully.
 *
 * - An extended attribute of the file is written to successfully.
 *
 * In each case, check that the flags are cleared if unprivileged, and that
 * they aren't cleared if privileged.
 *
 * We can't use expect() as we're looking for side-effects rather than
 * success/failure of the system call.
 */

#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 char fpath[1024];
static int fpath_initialized;

/*
 * If running as root, check that SUID is still set; otherwise, check that it
 * is not.
 */
static void
confirm_sugid(char *test_case, int asroot, int injail)
{
	struct stat sb;

	if (stat(fpath, &sb) < 0) {
		warn("%s stat(%s)", test_case, fpath);
		return;
	}
	if (asroot) {
		if (!(sb.st_mode & S_ISUID))
			warnx("%s(root, %s): !SUID", test_case, injail ?
			    "jail" : "!jail");
	} else {
		if (sb.st_mode & S_ISUID)
			warnx("%s(!root, %s): SUID", test_case, injail ?
			    "jail" : "!jail");
	}
}

int
priv_vfs_clearsugid_setup(int asroot, int injail, struct test *test)
{

	setup_file("priv_vfs_clearsugid_setup: fpath", fpath, UID_OWNER,
	    GID_OTHER, 0600 | S_ISUID);
	fpath_initialized = 1;
	return (0);
}

void
priv_vfs_clearsugid_chgrp(int asroot, int injail, struct test *test)
{

	if (chown(fpath, -1, asroot ? GID_WHEEL : GID_OWNER) < 0)
		err(-1, "priv_vfs_clearsugid_chgrp(%s, %s): chrgrp",
		    asroot ? "root" : "!root", injail ? "jail" : "!jail");
	confirm_sugid("priv_vfs_clearsugid_chgrp", asroot, injail);
}

#define	EA_NAMESPACE	EXTATTR_NAMESPACE_USER
#define	EA_NAME		"clearsugid"
#define	EA_DATA		"test"
#define	EA_SIZE		(strlen(EA_DATA))

void
priv_vfs_clearsugid_extattr(int asroot, int injail, struct test *test)
{

	if (extattr_set_file(fpath, EA_NAMESPACE, EA_NAME, EA_DATA, EA_SIZE)
	    < 0)
		err(-1,
		    "priv_vfs_clearsugid_extattr(%s, %s): extattr_set_file",
		    asroot ? "root" : "!root", injail ? "jail" : "!jail");
	confirm_sugid("priv_vfs_clearsugid_extattr", asroot, injail);
}

void
priv_vfs_clearsugid_write(int asroot, int injail, struct test *test)
{
	int fd;

	fd = open(fpath, O_RDWR);
	if (fd < 0)
		err(-1, "priv_vfs_clearsugid_write(%s, %s): open",
		    asroot ? "root" : "!root", injail ? "jail" : "!jail");
	if (write(fd, EA_DATA, EA_SIZE) < 0)
		err(-1, "priv_vfs_clearsugid_write(%s, %s): write",
		    asroot ? "root" : "!root", injail ? "jail" : "!jail");
	(void)close(fd);
	confirm_sugid("priv_vfs_clearsugid_write", asroot, injail);
}

void
priv_vfs_clearsugid_cleanup(int asroot, int injail, struct test *test)
{

	if (fpath_initialized) {
		(void)unlink(fpath);
		fpath_initialized = 0;
	}
}