/* $NetBSD: secmodel_keylock.c,v 1.12 2021/12/07 21:45:31 andvar Exp $ */
/*-
 * Copyright (c) 2009 Marc Balmer <marc@msys.ch>
 * 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. 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 an experimental
 * keylock based security scheme.
 *
 * The position of the keylock is a system-global indication on what
 * operations are allowed or not. It affects all users, including root.
 *
 * Rules:
 *
 * - If the number of possible keylock positions is 0, assume there is no
 *   keylock present, do not disallow any action, i.e. do nothing
 *
 * - If the number of possible keylock positions is greater than 0, but the
 *   current lock position is 0, assume tampering with the lock and forbid
 *   all actions.
 *
 * - If the lock is in the lowest position, assume the system is locked and
 *   forbid most actions.
 *
 * - If the lock is in the highest position, assume the system to be open and
 *   forbid nothing.
 *
 * - If the security.models.keylock.order sysctl is set to a value != 0,
 *   reverse this order.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: secmodel_keylock.c,v 1.12 2021/12/07 21:45:31 andvar Exp $");

#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 <dev/keylock.h>

#include <miscfs/specfs/specdev.h>

#include <secmodel/secmodel.h>
#include <secmodel/keylock/keylock.h>

static kauth_listener_t l_system, l_process, l_network, l_machdep, l_device;

static secmodel_t keylock_sm;

SYSCTL_SETUP(sysctl_security_keylock_setup,
    "sysctl security keylock setup")
{
        const struct sysctlnode *rnode;

        sysctl_createv(clog, 0, NULL, &rnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "models", NULL,
                       NULL, 0, NULL, 0,
                       CTL_SECURITY, CTL_CREATE, CTL_EOL);

        sysctl_createv(clog, 0, &rnode, &rnode,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "keylock",
                       SYSCTL_DESCR("Keylock security model"),
                       NULL, 0, NULL, 0,
                       CTL_CREATE, CTL_EOL);

        sysctl_createv(clog, 0, &rnode, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_STRING, "name", NULL,
                       NULL, 0, __UNCONST("Keylock"), 0,
                       CTL_CREATE, CTL_EOL);
}

void
secmodel_keylock_init(void)
{
        int error = secmodel_register(&keylock_sm,
            "org.netbsd.secmodel.keylock",
            "NetBSD Security Model: Keylock", NULL, NULL, NULL);
        if (error != 0)
                printf("secmodel_keylock_init: secmodel_register "
                    "returned %d\n", error);
}

void
secmodel_keylock_start(void)
{
        l_system = kauth_listen_scope(KAUTH_SCOPE_SYSTEM,
            secmodel_keylock_system_cb, NULL);
        l_process = kauth_listen_scope(KAUTH_SCOPE_PROCESS,
            secmodel_keylock_process_cb, NULL);
        l_network = kauth_listen_scope(KAUTH_SCOPE_NETWORK,
            secmodel_keylock_network_cb, NULL);
        l_machdep = kauth_listen_scope(KAUTH_SCOPE_MACHDEP,
            secmodel_keylock_machdep_cb, NULL);
        l_device = kauth_listen_scope(KAUTH_SCOPE_DEVICE,
            secmodel_keylock_device_cb, NULL);
}

void
secmodel_keylock_stop(void)
{
        int error;

        kauth_unlisten_scope(l_system);
        kauth_unlisten_scope(l_process);
        kauth_unlisten_scope(l_network);
        kauth_unlisten_scope(l_machdep);
        kauth_unlisten_scope(l_device);

        error = secmodel_deregister(keylock_sm);
        if (error != 0)
                printf("secmodel_keylock_stop: secmodel_deregister "
                    "returned %d\n", error);
}

/*
 * kauth(9) listener
 *
 * Security model: Multi-position keylock
 * Scope: System
 * Responsibility: Keylock
 */
int
secmodel_keylock_system_cb(kauth_cred_t cred,
    kauth_action_t action, void *cookie, void *arg0, void *arg1,
    void *arg2, void *arg3)
{
        int result;
        enum kauth_system_req req;
        int kstate;

        kstate = keylock_state();
        if (kstate == KEYLOCK_ABSENT)
                return KAUTH_RESULT_DEFER;
        else if (kstate == KEYLOCK_TAMPER)
                return KAUTH_RESULT_DENY;

        result = KAUTH_RESULT_DEFER;
        req = (enum kauth_system_req)(uintptr_t)arg0;

        switch (action) {
        case KAUTH_SYSTEM_CHSYSFLAGS:
                if (kstate == KEYLOCK_CLOSE)
                        result = KAUTH_RESULT_DENY;
                break;

        case KAUTH_SYSTEM_TIME:
                switch (req) {
                case KAUTH_REQ_SYSTEM_TIME_RTCOFFSET:
                        if (kstate == KEYLOCK_CLOSE)
                                result = KAUTH_RESULT_DENY;
                        break;

                case KAUTH_REQ_SYSTEM_TIME_SYSTEM: {
                        struct timespec *ts = arg1;
                        struct timespec *delta = arg2;

                        if (keylock_position() > 1 && time_wraps(ts, delta))
                                result = KAUTH_RESULT_DENY;
                        break;
                }
                default:
                        break;
                }
                break;

        case KAUTH_SYSTEM_MODULE:
                if (kstate == KEYLOCK_CLOSE)
                        result = KAUTH_RESULT_DENY;
                break;

        case KAUTH_SYSTEM_MOUNT:
                switch (req) {
                case KAUTH_REQ_SYSTEM_MOUNT_NEW:
                        if (kstate == KEYLOCK_CLOSE)
                                result = KAUTH_RESULT_DENY;

                        break;

                case KAUTH_REQ_SYSTEM_MOUNT_UPDATE:
                        if (kstate == KEYLOCK_CLOSE) {
                                struct mount *mp = arg1;
                                u_long flags = (u_long)arg2;

                                /*
                                 * Can only degrade from read/write to
                                 * read-only.
                                 */
                                if (flags != (mp->mnt_flag | MNT_RDONLY |
                                    MNT_RELOAD | MNT_FORCE | MNT_UPDATE))
                                        result = KAUTH_RESULT_DENY;
                        }
                        break;
                default:
                        break;
                }

                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 (kstate == KEYLOCK_CLOSE)
                                result = KAUTH_RESULT_DENY;
                        break;
                default:
                        break;
                }
                break;

        case KAUTH_SYSTEM_SETIDCORE:
                if (kstate == KEYLOCK_CLOSE)
                        result = KAUTH_RESULT_DENY;
                break;

        case KAUTH_SYSTEM_DEBUG:
                break;
        }

        return result;
}

/*
 * kauth(9) listener
 *
 * Security model: Multi-position keylock
 * Scope: Process
 * Responsibility: Keylock
 */
int
secmodel_keylock_process_cb(kauth_cred_t cred,
    kauth_action_t action, void *cookie, void *arg0,
    void *arg1, void *arg2, void *arg3)
{
        struct proc *p;
        int result, kstate;

        kstate = keylock_state();
        if (kstate == KEYLOCK_ABSENT)
                return KAUTH_RESULT_DEFER;
        else if (kstate == KEYLOCK_TAMPER)
                return KAUTH_RESULT_DENY;

        result = KAUTH_RESULT_DEFER;
        p = arg0;

        switch (action) {
        case KAUTH_PROCESS_PROCFS: {
                enum kauth_process_req req;

                req = (enum kauth_process_req)(uintptr_t)arg2;
                switch (req) {
                case KAUTH_REQ_PROCESS_PROCFS_READ:
                        break;

                case KAUTH_REQ_PROCESS_PROCFS_RW:
                case KAUTH_REQ_PROCESS_PROCFS_WRITE:
                        if ((p == initproc) && (kstate != KEYLOCK_OPEN))
                                result = KAUTH_RESULT_DENY;

                        break;
                default:
                        break;
                }

                break;
                }

        case KAUTH_PROCESS_PTRACE:
                if ((p == initproc) && (kstate != KEYLOCK_OPEN))
                        result = KAUTH_RESULT_DENY;

                break;

        case KAUTH_PROCESS_CORENAME:
                if (kstate == KEYLOCK_CLOSE)
                        result = KAUTH_RESULT_DENY;
                break;
        }
        return result;
}

/*
 * kauth(9) listener
 *
 * Security model: Multi-position keylock
 * Scope: Network
 * Responsibility: Keylock
 */
int
secmodel_keylock_network_cb(kauth_cred_t cred,
    kauth_action_t action, void *cookie, void *arg0,
    void *arg1, void *arg2, void *arg3)
{
        int result, kstate;
        enum kauth_network_req req;

        kstate = keylock_state();
        if (kstate == KEYLOCK_ABSENT)
                return KAUTH_RESULT_DEFER;
        else if (kstate == KEYLOCK_TAMPER)
                return KAUTH_RESULT_DENY;

        result = KAUTH_RESULT_DEFER;
        req = (enum kauth_network_req)(uintptr_t)arg0;

        switch (action) {
        case KAUTH_NETWORK_FIREWALL:
                switch (req) {
                case KAUTH_REQ_NETWORK_FIREWALL_FW:
                case KAUTH_REQ_NETWORK_FIREWALL_NAT:
                        if (kstate == KEYLOCK_CLOSE)
                                result = KAUTH_RESULT_DENY;
                        break;

                default:
                        break;
                }
                break;

        case KAUTH_NETWORK_FORWSRCRT:
                if (kstate != KEYLOCK_OPEN)
                        result = KAUTH_RESULT_DENY;
                break;
        }

        return result;
}

/*              
 * kauth(9) listener
 *
 * Security model: Multi-position keylock
 * Scope: Machdep
 * Responsibility: Keylock
 */
int
secmodel_keylock_machdep_cb(kauth_cred_t cred,
    kauth_action_t action, void *cookie, void *arg0,
    void *arg1, void *arg2, void *arg3)
{
        int result, kstate;

        kstate = keylock_state();
        if (kstate == KEYLOCK_ABSENT)
                return KAUTH_RESULT_DEFER;
        else if (kstate == KEYLOCK_TAMPER)
                return KAUTH_RESULT_DENY;

        result = KAUTH_RESULT_DEFER;

        switch (action) {
        case KAUTH_MACHDEP_IOPERM_SET:
        case KAUTH_MACHDEP_IOPL:
                if (kstate != KEYLOCK_OPEN)
                        result = KAUTH_RESULT_DENY;
                break;

        case KAUTH_MACHDEP_UNMANAGEDMEM:
                if (kstate != KEYLOCK_OPEN)
                        result = KAUTH_RESULT_DENY;
                break;
        }

        return result;
}

/*
 * kauth(9) listener
 *
 * Security model: Multi-position keylock
 * Scope: Device 
 * Responsibility: Keylock
 */
int
secmodel_keylock_device_cb(kauth_cred_t cred,
    kauth_action_t action, void *cookie, void *arg0,
    void *arg1, void *arg2, void *arg3)
{
        int result, kstate, error;

        kstate = keylock_state();
        if (kstate == KEYLOCK_ABSENT)
                return KAUTH_RESULT_DEFER;
        else if (kstate == KEYLOCK_TAMPER)
                return KAUTH_RESULT_DENY;

        result = KAUTH_RESULT_DEFER;

        switch (action) {
        case KAUTH_DEVICE_RAWIO_SPEC: {
                struct vnode *vp;
                enum kauth_device_req req;

                req = (enum kauth_device_req)(uintptr_t)arg0;
                vp = arg1;

                KASSERT(vp != NULL);

                /* Handle /dev/mem and /dev/kmem. */
                if (iskmemvp(vp)) {
                        switch (req) {
                        case KAUTH_REQ_DEVICE_RAWIO_SPEC_READ:
                                break;

                        case KAUTH_REQ_DEVICE_RAWIO_SPEC_WRITE:
                        case KAUTH_REQ_DEVICE_RAWIO_SPEC_RW:
                                if (kstate != KEYLOCK_OPEN)
                                        result = KAUTH_RESULT_DENY;
                                break;
                        default:
                                break;
                        }
                        break;
                }

                switch (req) {
                case KAUTH_REQ_DEVICE_RAWIO_SPEC_READ:
                        break;

                case KAUTH_REQ_DEVICE_RAWIO_SPEC_WRITE:
                case KAUTH_REQ_DEVICE_RAWIO_SPEC_RW:
                        error = rawdev_mounted(vp, NULL);

                        if (error == EINVAL)
                                break;

                        if (error && (kstate != KEYLOCK_OPEN))
                                break;

                        if (kstate == KEYLOCK_CLOSE)
                                result = KAUTH_RESULT_DENY;

                        break;
                default:
                        break;
                }
                break;
                }

        case KAUTH_DEVICE_RAWIO_PASSTHRU:
                if (kstate != KEYLOCK_OPEN) {
                        u_long bits;

                        bits = (u_long)arg0;

                        KASSERT(bits != 0);
                        KASSERT((bits & ~KAUTH_REQ_DEVICE_RAWIO_PASSTHRU_ALL)
                            == 0);

                        if (bits & ~KAUTH_REQ_DEVICE_RAWIO_PASSTHRU_READCONF)
                                result = KAUTH_RESULT_DENY;
                }
                break;

        case KAUTH_DEVICE_GPIO_PINSET:
                if (kstate != KEYLOCK_OPEN)
                        result = KAUTH_RESULT_DENY;
                break;
        default:
                break;
        }
        return result;
}