xref: /freebsd/sys/security/mac_ntpd/mac_ntpd.c (revision db33c6f3ae9d1231087710068ee4ea5398aacca7)

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2018 Ian Lepore <ian@FreeBSD.org>
 *
 * 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 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.
 */

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/priv.h>
#include <sys/sysctl.h>
#include <sys/ucred.h>

#include <security/mac/mac_policy.h>

static SYSCTL_NODE(_security_mac, OID_AUTO, ntpd,
    CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "mac_ntpd policy controls");

static int ntpd_enabled = 1;
SYSCTL_INT(_security_mac_ntpd, OID_AUTO, enabled, CTLFLAG_RWTUN,
    &ntpd_enabled, 0, "Enable mac_ntpd policy");

static int ntpd_uid = 123;
SYSCTL_INT(_security_mac_ntpd, OID_AUTO, uid, CTLFLAG_RWTUN,
    &ntpd_uid, 0, "User id for ntpd user");

static int
ntpd_priv_grant(struct ucred *cred, int priv)
{

	if (ntpd_enabled && cred->cr_uid == ntpd_uid) {
		switch (priv) {
		case PRIV_ADJTIME:
		case PRIV_CLOCK_SETTIME:
		case PRIV_NTP_ADJTIME:
		case PRIV_NETINET_RESERVEDPORT:
		case PRIV_NETINET_REUSEPORT:
			return (0);
		default:
			break;
		}
	}
	return (EPERM);
}

static struct mac_policy_ops ntpd_ops =
{
	.mpo_priv_grant = ntpd_priv_grant,
};

MAC_POLICY_SET(&ntpd_ops, mac_ntpd, "MAC/ntpd",
    MPC_LOADTIME_FLAG_UNLOADOK, NULL);