NetBSD/sys/secmodel/bsd44/secmodel_bsd44_securelevel.c

/* $NetBSD: secmodel_bsd44_securelevel.c,v 1.10 2006/11/04 09:30:00 elad Exp $ */
/*-
 * Copyright (c) 2006 Elad Efrat <elad@NetBSD.org>
 * All rights reserved.
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Elad Efrat.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
 */

/*
 * This file contains kauth(9) listeners needed to implement the traditional
 * NetBSD securelevel. 
 *
 * The securelevel is a system-global indication on what operations are
 * allowed or not. It affects all users, including root.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: secmodel_bsd44_securelevel.c,v 1.10 2006/11/04 09:30:00 elad Exp $");

#ifdef _KERNEL_OPT
#include "opt_insecure.h"
#endif /* _KERNEL_OPT */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/kauth.h>

#include <sys/conf.h>
#include <sys/mount.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>

#include <miscfs/specfs/specdev.h>

#include <secmodel/bsd44/securelevel.h>

/*
 * XXX after we remove all securelevel references from the kernel,
 * XXX this goes static.
 */
int securelevel;

/*
 * sysctl helper routine for securelevel. ensures that the value
 * only rises unless the caller has pid 1 (assumed to be init).
 */
int
secmodel_bsd44_sysctl_securelevel(SYSCTLFN_ARGS)
{       
	int newsecurelevel, error;
	struct sysctlnode node;

	newsecurelevel = securelevel;
	node = *rnode;
	node.sysctl_data = &newsecurelevel;
	error = sysctl_lookup(SYSCTLFN_CALL(&node));
	if (error || newp == NULL)
		return (error);
        
	if (newsecurelevel < securelevel && l && l->l_proc->p_pid != 1)
		return (EPERM);
	securelevel = newsecurelevel;

	return (error);
}

void
secmodel_bsd44_securelevel_init(void)
{
#ifdef INSECURE
	securelevel = -1;
#else
	securelevel = 0;
#endif /* INSECURE */
}

SYSCTL_SETUP(sysctl_secmodel_bsd44_securelevel_setup,
    "sysctl secmodel bsd44 securelevel setup")
{
	/*
	 * For compatibility, we create a kern.securelevel variable.
	 */
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT,
		       CTLTYPE_NODE, "kern", NULL,
		       NULL, 0, NULL, 0,
		       CTL_KERN, CTL_EOL);

	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "securelevel",
		       SYSCTL_DESCR("System security level"),
		       secmodel_bsd44_sysctl_securelevel, 0, &securelevel, 0,
		       CTL_KERN, KERN_SECURELVL, CTL_EOL);
}

void
secmodel_bsd44_securelevel_start(void)
{
	kauth_listen_scope(KAUTH_SCOPE_SYSTEM,
	    secmodel_bsd44_securelevel_system_cb, NULL);
	kauth_listen_scope(KAUTH_SCOPE_PROCESS,
	    secmodel_bsd44_securelevel_process_cb, NULL);
	kauth_listen_scope(KAUTH_SCOPE_NETWORK,
	    secmodel_bsd44_securelevel_network_cb, NULL);
	kauth_listen_scope(KAUTH_SCOPE_MACHDEP,
	    secmodel_bsd44_securelevel_machdep_cb, NULL);
	kauth_listen_scope(KAUTH_SCOPE_DEVICE,
	    secmodel_bsd44_securelevel_device_cb, NULL);
}

/*
 * kauth(9) listener
 *
 * Security model: Traditional NetBSD
 * Scope: System
 * Responsibility: Securelevel
 */
int
secmodel_bsd44_securelevel_system_cb(kauth_cred_t cred __unused,
    kauth_action_t action, void *cookie __unused, void *arg0, void *arg1,
    void *arg2, void *arg3)
{
	int result;
	enum kauth_system_req req;

	result = KAUTH_RESULT_DENY;
	req = (enum kauth_system_req)arg0;

	switch (action) {
	case KAUTH_SYSTEM_TIME:
		switch (req) {
		case KAUTH_REQ_SYSTEM_TIME_BACKWARDS:
			if (securelevel < 2)
				result = KAUTH_RESULT_ALLOW;
			break;

		case KAUTH_REQ_SYSTEM_TIME_RTCOFFSET:
			if (securelevel < 1)
				result = KAUTH_RESULT_ALLOW;
			break;

		default:
			result = KAUTH_RESULT_DEFER;
			break;
		}
		break;

	case KAUTH_SYSTEM_LKM:
		if (securelevel < 1)
			result = KAUTH_RESULT_ALLOW;
		break;

	case KAUTH_SYSTEM_SYSCTL:
		switch (req) {
		case KAUTH_REQ_SYSTEM_SYSCTL_ADD:
		case KAUTH_REQ_SYSTEM_SYSCTL_DELETE:
		case KAUTH_REQ_SYSTEM_SYSCTL_DESC:
			if (securelevel < 1)
				result = KAUTH_RESULT_ALLOW;
			break;

		default:
			result = KAUTH_RESULT_DEFER;
			break;
		}
		break;

	case KAUTH_SYSTEM_SETIDCORE:
		if (securelevel < 1)
			result = KAUTH_RESULT_ALLOW;
		break;

	case KAUTH_SYSTEM_DEBUG:
		switch (req) {
		case KAUTH_REQ_SYSTEM_DEBUG_IPKDB:
			if (securelevel < 1)
				result = KAUTH_RESULT_ALLOW;
			break;

		default:
			result = KAUTH_RESULT_DEFER;
			break;
		}
		break;

	default:
		result = KAUTH_RESULT_DEFER;
		break;
	}

	return (result);
}

/*
 * kauth(9) listener
 *
 * Security model: Traditional NetBSD
 * Scope: Process
 * Responsibility: Securelevel
 */
int
secmodel_bsd44_securelevel_process_cb(kauth_cred_t cred __unused,
    kauth_action_t action, void *cookie __unused, void *arg0 __unused,
    void *arg1 __unused, void *arg2 __unused, void *arg3 __unused)
{
	int result;

	result = KAUTH_RESULT_DENY;

	switch (action) {
	case KAUTH_PROCESS_CORENAME:
		if (securelevel < 2)
			result = KAUTH_RESULT_ALLOW;
		break;

	default:
		result = KAUTH_RESULT_DEFER;
		break;
	}

	return (result);
}

/*
 * kauth(9) listener
 *
 * Security model: Traditional NetBSD
 * Scope: Network
 * Responsibility: Securelevel
 */
int
secmodel_bsd44_securelevel_network_cb(kauth_cred_t cred __unused,
    kauth_action_t action, void *cookie __unused, void *arg0 __unused,
    void *arg1 __unused, void *arg2 __unused, void *arg3 __unused)
{
	int result;
	enum kauth_network_req req;

	result = KAUTH_RESULT_DENY;
	req = (enum kauth_network_req)arg0;

	switch (action) {
	case KAUTH_NETWORK_FIREWALL:
		switch (req) {
		case KAUTH_REQ_NETWORK_FIREWALL_FW:
		case KAUTH_REQ_NETWORK_FIREWALL_NAT:
			if (securelevel < 2)
				result = KAUTH_RESULT_ALLOW;
			break;

		default:
			result = KAUTH_RESULT_DEFER;
			break;
		}
		break;

	case KAUTH_NETWORK_FORWSRCRT:
		if (securelevel < 1)
			result = KAUTH_RESULT_ALLOW;
		break;

	default:
		result = KAUTH_RESULT_DEFER;
		break;
	}

	return (result);
}

/*              
 * kauth(9) listener
 *
 * Security model: Traditional NetBSD
 * Scope: Machdep
 * Responsibility: Securelevel
 */
int
secmodel_bsd44_securelevel_machdep_cb(kauth_cred_t cred __unused,
    kauth_action_t action, void *cookie __unused, void *arg0 __unused,
    void *arg1 __unused, void *arg2 __unused, void *arg3 __unused)
{
        int result;
	enum kauth_machdep_req req;

        result = KAUTH_RESULT_DENY;
	req = (enum kauth_machdep_req)arg0;

        switch (action) {
	case KAUTH_MACHDEP_X86:
		switch (req) {
		case KAUTH_REQ_MACHDEP_X86_IOPL:
		case KAUTH_REQ_MACHDEP_X86_IOPERM:
			if (securelevel < 2)
				result = KAUTH_RESULT_ALLOW;
			break;
		default:
			result = KAUTH_RESULT_DEFER;
			break;
		}

		break;

	default:
		result = KAUTH_RESULT_DEFER;
		break;
	}

	return (result);
}

/*
 * kauth(9) listener
 *
 * Security model: Traditional NetBSD
 * Scope: Device 
 * Responsibility: Securelevel
 */
int
secmodel_bsd44_securelevel_device_cb(kauth_cred_t cred __unused,
    kauth_action_t action, void *cookie __unused, void *arg0,
    void *arg1, void *arg2 __unused, void *arg3 __unused)
{
	int result;
	enum kauth_device_req req;

	result = KAUTH_RESULT_DENY;
	req = (enum kauth_device_req)arg0;

	switch (action) {
	case KAUTH_DEVICE_RAWIO_SPEC: {
		struct vnode *vp;
		dev_t dev;

		vp = arg1;

		if (vp == NULL) {
			result = KAUTH_RESULT_ALLOW;
			break;
		}

		dev = vp->v_un.vu_specinfo->si_rdev;

		/* Handle /dev/mem and /dev/kmem. */
		if ((vp->v_type == VCHR) && iskmemdev(dev)) {
			switch (req) {
			case KAUTH_REQ_DEVICE_RAWIO_SPEC_READ:
				result = KAUTH_RESULT_ALLOW;
				break;

			case KAUTH_REQ_DEVICE_RAWIO_SPEC_WRITE:
			case KAUTH_REQ_DEVICE_RAWIO_SPEC_RW:
				if (securelevel < 1)
					result = KAUTH_RESULT_ALLOW;
				break;

			default:
				result = KAUTH_RESULT_DEFER;
				break;
			}

			break;
		}

		switch (req) {
		case KAUTH_REQ_DEVICE_RAWIO_SPEC_READ:
			result = KAUTH_RESULT_ALLOW;
			break;

		case KAUTH_REQ_DEVICE_RAWIO_SPEC_WRITE:
		case KAUTH_REQ_DEVICE_RAWIO_SPEC_RW:
			switch (vp->v_type) {
			case VCHR: {
				const struct cdevsw *cdev;

				cdev = cdevsw_lookup(dev);
				if ((cdev == NULL) ||
				    (cdev->d_type != D_DISK)) {
					result = KAUTH_RESULT_ALLOW;
					break;
				}

				break;
				}
			case VBLK: {
				const struct bdevsw *bdev;

				bdev = bdevsw_lookup(dev);
				if ((bdev == NULL) ||
				    (bdev->d_type != D_DISK)) {
					result = KAUTH_RESULT_ALLOW;
					break;
				}

				break;
				}
			default:
				result = KAUTH_RESULT_DEFER;
				break;
			}

			if (vfs_mountedon(vp) && (securelevel > 0))
				break;

			if (securelevel < 2)
				result = KAUTH_RESULT_ALLOW;

			break;

		default:
			result = KAUTH_RESULT_DEFER;
			break;
		}

		break;
		}

	case KAUTH_DEVICE_RAWIO_PASSTHRU:
		if (securelevel < 1)
			result = KAUTH_RESULT_ALLOW;

		break;

	default:
		result = KAUTH_RESULT_DEFER;
		break;
	}

	return (result);
}