xnu-7195.60.75.tar.gz

[apple/xnu.git] / security / mac_base.c

/*
 * Copyright (c) 2007-2020 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*-
 * Copyright (c) 1999, 2000, 2001, 2002 Robert N. M. Watson
 * Copyright (c) 2001 Ilmar S. Habibulin
 * Copyright (c) 2001, 2002, 2003, 2004 Networks Associates Technology, Inc.
 * Copyright (c) 2005-2006 SPARTA, Inc.
 *
 * This software was developed by Robert Watson and Ilmar Habibulin for the
 * TrustedBSD Project.
 *
 * This software was developed for the FreeBSD Project in part by Network
 * Associates Laboratories, the Security Research Division of Network
 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
 * as part of the DARPA CHATS research program.
 *
 * 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.
 *
 */

/*-
 * Framework for extensible kernel access control.  This file contains
 * Kernel and userland interface to the framework, policy registration
 * and composition.  Per-object interfaces, controls, and labeling may be
 * found in src/sys/mac/.  Sample policies may be found in src/sys/mac*.
 */

#include <stdarg.h>
#include <string.h>
#include <security/mac_internal.h>
#include <security/mac_mach_internal.h>
#include <sys/param.h>
#include <sys/vnode.h>
#include <sys/vnode_internal.h>
#include <sys/vfs_context.h>
#include <sys/namei.h>
#include <bsd/bsm/audit.h>
#include <bsd/security/audit/audit.h>
#include <bsd/security/audit/audit_private.h>
#include <sys/file.h>
#include <sys/file_internal.h>
#include <sys/filedesc.h>
#include <sys/proc.h>
#include <sys/proc_internal.h>
#include <sys/kauth.h>
#include <sys/sysproto.h>

#include <mach/exception_types.h>
#include <mach/vm_types.h>
#include <mach/vm_prot.h>

#include <kern/kalloc.h>
#include <kern/sched_prim.h>
#include <kern/task.h>

#if CONFIG_MACF
#include <security/mac.h>
#include <security/mac_policy.h>
#include <security/mac_framework.h>
#include <security/mac_internal.h>
#include <security/mac_mach_internal.h>
#endif

#include <libkern/section_keywords.h>

/*
 * define MB_DEBUG to display run-time debugging information
 * #define MB_DEBUG 1
 */

#ifdef MB_DEBUG
#define DPRINTF(x)      printf x
#else
#define MB_DEBUG
#define DPRINTF(x)
#endif

#if CONFIG_MACF
SYSCTL_NODE(, OID_AUTO, security, CTLFLAG_RW | CTLFLAG_LOCKED, 0,
    "Security Controls");
SYSCTL_NODE(_security, OID_AUTO, mac, CTLFLAG_RW | CTLFLAG_LOCKED, 0,
    "TrustedBSD MAC policy controls");

/*
 * Declare that the kernel provides MAC support, version 1.  This permits
 * modules to refuse to be loaded if the necessary support isn't present,
 * even if it's pre-boot.
 */
#if 0
MODULE_VERSION(kernel_mac_support, 1);
#endif

#if MAC_MAX_SLOTS > 32
#error "MAC_MAX_SLOTS too large"
#endif

static unsigned int mac_max_slots = MAC_MAX_SLOTS;
static unsigned int mac_slot_offsets_free = (1 << MAC_MAX_SLOTS) - 1;
SYSCTL_UINT(_security_mac, OID_AUTO, max_slots, CTLFLAG_RD | CTLFLAG_LOCKED,
    &mac_max_slots, 0, "");

/*
 * Has the kernel started generating labeled objects yet?  All read/write
 * access to this variable is serialized during the boot process.  Following
 * the end of serialization, we don't update this flag; no locking.
 */
int     mac_late = 0;

/*
 * Flag to indicate whether or not we should allocate label storage for
 * new vnodes.  Since most dynamic policies we currently work with don't
 * rely on vnode labeling, try to avoid paying the cost of mtag allocation
 * unless specifically notified of interest.  One result of this is
 * that if a dynamically loaded policy requests vnode labels, it must
 * be able to deal with a NULL label being returned on any vnodes that
 * were already in flight when the policy was loaded.  Since the policy
 * already has to deal with uninitialized labels, this probably won't
 * be a problem.
 */
#if CONFIG_MACF_LAZY_VNODE_LABELS
unsigned int    mac_label_vnodes = 1;
#else
unsigned int    mac_label_vnodes = 0;
#endif /* CONFIG_MACF_LAZY_VNODE_LABELS */
SYSCTL_UINT(_security_mac, OID_AUTO, labelvnodes, SECURITY_MAC_CTLFLAGS
#if CONFIG_MACF_LAZY_VNODE_LABELS
    | CTLFLAG_RD
#endif
    , &mac_label_vnodes, 0, "Label all vnodes");

unsigned int mac_vnode_label_count = 0;
SYSCTL_UINT(_security_mac, OID_AUTO, vnode_label_count, SECURITY_MAC_CTLFLAGS | CTLFLAG_RD,
    &mac_vnode_label_count, 0, "Count of vnode labels");

unsigned int mac_device_enforce = 1;
SYSCTL_UINT(_security_mac, OID_AUTO, device_enforce, SECURITY_MAC_CTLFLAGS,
    &mac_device_enforce, 0, "Enforce MAC policy on device operations");

unsigned int    mac_pipe_enforce = 1;
SYSCTL_UINT(_security_mac, OID_AUTO, pipe_enforce, SECURITY_MAC_CTLFLAGS,
    &mac_pipe_enforce, 0, "Enforce MAC policy on pipe operations");

unsigned int    mac_posixsem_enforce = 1;
SYSCTL_UINT(_security_mac, OID_AUTO, posixsem_enforce, SECURITY_MAC_CTLFLAGS,
    &mac_posixsem_enforce, 0, "Enforce MAC policy on POSIX semaphores");

unsigned int mac_posixshm_enforce = 1;
SYSCTL_UINT(_security_mac, OID_AUTO, posixshm_enforce, SECURITY_MAC_CTLFLAGS,
    &mac_posixshm_enforce, 0, "Enforce MAC policy on Posix Shared Memory");

unsigned int    mac_proc_enforce = 1;
SYSCTL_UINT(_security_mac, OID_AUTO, proc_enforce, SECURITY_MAC_CTLFLAGS,
    &mac_proc_enforce, 0, "Enforce MAC policy on process operations");

unsigned int mac_socket_enforce = 1;
SYSCTL_UINT(_security_mac, OID_AUTO, socket_enforce, SECURITY_MAC_CTLFLAGS,
    &mac_socket_enforce, 0, "Enforce MAC policy on socket operations");

unsigned int    mac_system_enforce = 1;
SYSCTL_UINT(_security_mac, OID_AUTO, system_enforce, SECURITY_MAC_CTLFLAGS,
    &mac_system_enforce, 0, "Enforce MAC policy on system-wide interfaces");

unsigned int    mac_sysvmsg_enforce = 1;
SYSCTL_UINT(_security_mac, OID_AUTO, sysvmsg_enforce, SECURITY_MAC_CTLFLAGS,
    &mac_sysvmsg_enforce, 0, "Enforce MAC policy on System V IPC message queues");

unsigned int    mac_sysvsem_enforce = 1;
SYSCTL_UINT(_security_mac, OID_AUTO, sysvsem_enforce, SECURITY_MAC_CTLFLAGS,
    &mac_sysvsem_enforce, 0, "Enforce MAC policy on System V IPC semaphores");

unsigned int    mac_sysvshm_enforce = 1;
SYSCTL_INT(_security_mac, OID_AUTO, sysvshm_enforce, SECURITY_MAC_CTLFLAGS,
    &mac_sysvshm_enforce, 0, "Enforce MAC policy on System V Shared Memory");

unsigned int    mac_vm_enforce = 1;
SYSCTL_INT(_security_mac, OID_AUTO, vm_enforce, SECURITY_MAC_CTLFLAGS,
    &mac_vm_enforce, 0, "Enforce MAC policy on VM operations");

unsigned int    mac_vnode_enforce = 1;
SYSCTL_UINT(_security_mac, OID_AUTO, vnode_enforce, SECURITY_MAC_CTLFLAGS,
    &mac_vnode_enforce, 0, "Enforce MAC policy on vnode operations");

/*
 * mac_policy_list holds the list of policy modules.  Modules with a
 * handle lower than staticmax are considered "static" and cannot be
 * unloaded.  Such policies can be invoked without holding the busy count.
 *
 * Modules with a handle at or above the staticmax high water mark
 * are considered to be "dynamic" policies.  A busy count is maintained
 * for the list, stored in mac_policy_busy.  The busy count is protected
 * by mac_policy_mtx; the list may be modified only while the busy
 * count is 0, requiring that the lock be held to prevent new references
 * to the list from being acquired.  For almost all operations,
 * incrementing the busy count is sufficient to guarantee consistency,
 * as the list cannot be modified while the busy count is elevated.
 * For a few special operations involving a change to the list of
 * active policies, the mtx itself must be held.
 */
static lck_mtx_t *mac_policy_mtx;

/*
 * Policy list array allocation chunk size. Each entry holds a pointer.
 */
#define MAC_POLICY_LIST_CHUNKSIZE 8

static int mac_policy_busy;

#if !XNU_TARGET_OS_OSX
SECURITY_READ_ONLY_LATE(mac_policy_list_t) mac_policy_list;
SECURITY_READ_ONLY_LATE(static struct mac_policy_list_element) mac_policy_static_entries[MAC_POLICY_LIST_CHUNKSIZE];
#else
mac_policy_list_t mac_policy_list;
#endif

/*
 * mac_label_element_list holds the master list of label namespaces for
 * all the policies. When a policy is loaded, each of it's label namespace
 * elements is added to the master list if not already present. When a
 * policy is unloaded, the namespace elements are removed if no other
 * policy is interested in that namespace element.
 */
struct mac_label_element_list_t mac_label_element_list;
struct mac_label_element_list_t mac_static_label_element_list;

static __inline void
mac_policy_grab_exclusive(void)
{
        lck_mtx_lock(mac_policy_mtx);
        while (mac_policy_busy != 0) {
                lck_mtx_sleep(mac_policy_mtx, LCK_SLEEP_UNLOCK,
                    (event_t)&mac_policy_busy, THREAD_UNINT);
                lck_mtx_lock(mac_policy_mtx);
        }
}

static __inline void
mac_policy_release_exclusive(void)
{
        KASSERT(mac_policy_busy == 0,
            ("mac_policy_release_exclusive(): not exclusive"));
        lck_mtx_unlock(mac_policy_mtx);
        thread_wakeup((event_t) &mac_policy_busy);
}

void
mac_policy_list_busy(void)
{
        lck_mtx_lock(mac_policy_mtx);
        mac_policy_busy++;
        lck_mtx_unlock(mac_policy_mtx);
}

int
mac_policy_list_conditional_busy(void)
{
        int ret;

        if (mac_policy_list.numloaded <= mac_policy_list.staticmax) {
                return 0;
        }

        lck_mtx_lock(mac_policy_mtx);
        if (mac_policy_list.numloaded > mac_policy_list.staticmax) {
                mac_policy_busy++;
                ret = 1;
        } else {
                ret = 0;
        }
        lck_mtx_unlock(mac_policy_mtx);
        return ret;
}

void
mac_policy_list_unbusy(void)
{
        lck_mtx_lock(mac_policy_mtx);
        mac_policy_busy--;
        KASSERT(mac_policy_busy >= 0, ("MAC_POLICY_LIST_LOCK"));
        if (mac_policy_busy == 0) {
                thread_wakeup(&mac_policy_busy);
        }
        lck_mtx_unlock(mac_policy_mtx);
}

/*
 * Early pre-malloc MAC initialization, including appropriate SMP locks.
 */
void
mac_policy_init(void)
{
        lck_grp_attr_t *mac_lck_grp_attr;
        lck_attr_t *mac_lck_attr;
        lck_grp_t *mac_lck_grp;

        mac_policy_list.numloaded = 0;
        mac_policy_list.max = MAC_POLICY_LIST_CHUNKSIZE;
        mac_policy_list.maxindex = 0;
        mac_policy_list.staticmax = 0;
        mac_policy_list.freehint = 0;
        mac_policy_list.chunks = 1;

#if !XNU_TARGET_OS_OSX
        mac_policy_list.entries = mac_policy_static_entries;
#else
        mac_policy_list.entries = kalloc_flags(
                sizeof(struct mac_policy_list_element) * MAC_POLICY_LIST_CHUNKSIZE,
                Z_WAITOK | Z_ZERO);
#endif

        LIST_INIT(&mac_label_element_list);
        LIST_INIT(&mac_static_label_element_list);

        mac_lck_grp_attr = lck_grp_attr_alloc_init();
        mac_lck_grp = lck_grp_alloc_init("MAC lock", mac_lck_grp_attr);
        mac_lck_attr = lck_attr_alloc_init();
        lck_attr_setdefault(mac_lck_attr);
        mac_policy_mtx = lck_mtx_alloc_init(mac_lck_grp, mac_lck_attr);
        lck_attr_free(mac_lck_attr);
        lck_grp_attr_free(mac_lck_grp_attr);
        lck_grp_free(mac_lck_grp);
}

/* Function pointer set up for loading security extensions.
 * It is set to an actual function after OSlibkernInit()
 * has been called, and is set back to 0 by OSKextRemoveKextBootstrap()
 * after bsd_init().
 */
void (*load_security_extensions_function)(void) = 0;

/*
 * Init after early Mach startup, but before BSD
 */
void
mac_policy_initmach(void)
{
        /*
         * For the purposes of modules that want to know if they were
         * loaded "early", set the mac_late flag once we've processed
         * modules either linked into the kernel, or loaded before the
         * kernel startup.
         */

        if (load_security_extensions_function) {
                load_security_extensions_function();
        }
        mac_late = 1;
}

/*
 * BSD startup.
 */
void
mac_policy_initbsd(void)
{
        struct mac_policy_conf *mpc;
        u_int i;

        printf("MAC Framework successfully initialized\n");

        /* Call bsd init functions of already loaded policies */

        /*
         * Using the exclusive lock means no other framework entry
         * points can proceed while initializations are running.
         * This may not be necessary.
         */
        mac_policy_grab_exclusive();

        for (i = 0; i <= mac_policy_list.maxindex; i++) {
                mpc = mac_get_mpc(i);
                if ((mpc != NULL) && (mpc->mpc_ops->mpo_policy_initbsd != NULL)) {
                        (*(mpc->mpc_ops->mpo_policy_initbsd))(mpc);
                }
        }

        mac_policy_release_exclusive();
}

/*
 * After a policy has been loaded, add the label namespaces managed by the
 * policy to either the static or non-static label namespace list.
 * A namespace is added to the the list only if it is not already on one of
 * the lists.
 */
void
mac_policy_addto_labellist(mac_policy_handle_t handle, int static_entry)
{
        struct mac_label_listener **new_mlls;
        struct mac_label_element *mle, **new_mles;
        struct mac_label_element_list_t *list;
        struct mac_policy_conf *mpc;
        const char *name, *name2;
        u_int idx, mle_free, mll_free;

        mpc = mac_get_mpc(handle);

        if (mpc->mpc_labelnames == NULL) {
                return;
        }

        if (mpc->mpc_labelname_count == 0) {
                return;
        }

        if (static_entry) {
                list = &mac_static_label_element_list;
        } else {
                list = &mac_label_element_list;
        }

        /*
         * Before we grab the policy list lock, allocate enough memory
         * to contain the potential new elements so we don't have to
         * give up the lock, or allocate with the lock held.
         */
        MALLOC(new_mles, struct mac_label_element **,
            sizeof(struct mac_label_element *) *
            mpc->mpc_labelname_count, M_MACTEMP, M_WAITOK | M_ZERO);
        for (idx = 0; idx < mpc->mpc_labelname_count; idx++) {
                MALLOC(new_mles[idx], struct mac_label_element *,
                    sizeof(struct mac_label_element),
                    M_MACTEMP, M_WAITOK);
        }
        mle_free = 0;
        MALLOC(new_mlls, struct mac_label_listener **,
            sizeof(struct mac_label_listener *) *
            mpc->mpc_labelname_count, M_MACTEMP, M_WAITOK);
        for (idx = 0; idx < mpc->mpc_labelname_count; idx++) {
                MALLOC(new_mlls[idx], struct mac_label_listener *,
                    sizeof(struct mac_label_listener), M_MACTEMP, M_WAITOK);
        }
        mll_free = 0;

        if (mac_late) {
                mac_policy_grab_exclusive();
        }
        for (idx = 0; idx < mpc->mpc_labelname_count; idx++) {
                if (*(name = mpc->mpc_labelnames[idx]) == '?') {
                        name++;
                }
                /*
                 * Check both label element lists and add to the
                 * appropriate list only if not already on a list.
                 */
                LIST_FOREACH(mle, &mac_static_label_element_list, mle_list) {
                        if (*(name2 = mle->mle_name) == '?') {
                                name2++;
                        }
                        if (strcmp(name, name2) == 0) {
                                break;
                        }
                }
                if (mle == NULL) {
                        LIST_FOREACH(mle, &mac_label_element_list, mle_list) {
                                if (*(name2 = mle->mle_name) == '?') {
                                        name2++;
                                }
                                if (strcmp(name, name2) == 0) {
                                        break;
                                }
                        }
                }
                if (mle == NULL) {
                        mle = new_mles[mle_free];
                        strlcpy(mle->mle_name, mpc->mpc_labelnames[idx],
                            MAC_MAX_LABEL_ELEMENT_NAME);
                        LIST_INIT(&mle->mle_listeners);
                        LIST_INSERT_HEAD(list, mle, mle_list);
                        mle_free++;
                }
                /* Add policy handler as a listener. */
                new_mlls[mll_free]->mll_handle = handle;
                LIST_INSERT_HEAD(&mle->mle_listeners, new_mlls[mll_free],
                    mll_list);
                mll_free++;
        }
        if (mac_late) {
                mac_policy_release_exclusive();
        }

        /* Free up any unused label elements and listeners */
        for (idx = mle_free; idx < mpc->mpc_labelname_count; idx++) {
                FREE(new_mles[idx], M_MACTEMP);
        }
        FREE(new_mles, M_MACTEMP);
        for (idx = mll_free; idx < mpc->mpc_labelname_count; idx++) {
                FREE(new_mlls[idx], M_MACTEMP);
        }
        FREE(new_mlls, M_MACTEMP);
}

/*
 * After a policy has been unloaded, remove the label namespaces that the
 * the policy manages from the non-static list of namespaces.
 * The removal only takes place when no other policy is interested in the
 * namespace.
 *
 * Must be called with the policy exclusive lock held.
 */
void
mac_policy_removefrom_labellist(mac_policy_handle_t handle)
{
        struct mac_label_listener *mll;
        struct mac_label_element *mle;
        struct mac_policy_conf *mpc;

        mpc = mac_get_mpc(handle);

        if (mpc->mpc_labelnames == NULL) {
                return;
        }

        if (mpc->mpc_labelname_count == 0) {
                return;
        }

        /*
         * Unregister policy as being interested in any label
         * namespaces.  If no other policy is listening, remove
         * that label element from the list.  Note that we only
         * have to worry about the non-static list.
         */
        LIST_FOREACH(mle, &mac_label_element_list, mle_list) {
                LIST_FOREACH(mll, &mle->mle_listeners, mll_list) {
                        if (mll->mll_handle == handle) {
                                LIST_REMOVE(mll, mll_list);
                                FREE(mll, M_MACTEMP);
                                if (LIST_EMPTY(&mle->mle_listeners)) {
                                        LIST_REMOVE(mle, mle_list);
                                        FREE(mle, M_MACTEMP);
                                }
                                return;
                        }
                }
        }
}

/*
 * After the policy list has changed, walk the list to update any global
 * flags.
 */
static void
mac_policy_updateflags(void)
{
}

static __inline void
mac_policy_fixup_mmd_list(struct mac_module_data *new)
{
        struct mac_module_data *old;
        struct mac_module_data_element *ele, *aele;
        struct mac_module_data_list *arr, *dict;
        unsigned int i, j, k;

        old = new->base_addr;
        DPRINTF(("fixup_mmd: old %p new %p\n", old, new));
        for (i = 0; i < new->count; i++) {
                ele = &(new->data[i]);
                DPRINTF(("fixup_mmd: ele %p\n", ele));
                DPRINTF(("   key %p value %p\n", ele->key, ele->value));
                mmd_fixup_ele(old, new, ele); /* Fix up key/value ptrs.       */
                DPRINTF(("   key %p value %p\n", ele->key, ele->value));
                if (ele->value_type == MAC_DATA_TYPE_ARRAY) {
                        arr = (struct mac_module_data_list *)ele->value;
                        DPRINTF(("fixup_mmd: array @%p\n", arr));
                        for (j = 0; j < arr->count; j++) {
                                aele = &(arr->list[j]);
                                DPRINTF(("fixup_mmd: aele %p\n", aele));
                                DPRINTF(("   key %p value %p\n", aele->key, aele->value));
                                mmd_fixup_ele(old, new, aele);
                                DPRINTF(("   key %p value %p\n", aele->key, aele->value));
                                if (arr->type == MAC_DATA_TYPE_DICT) {
                                        dict = (struct mac_module_data_list *)aele->value;
                                        DPRINTF(("fixup_mmd: dict @%p\n", dict));
                                        for (k = 0; k < dict->count; k++) {
                                                mmd_fixup_ele(old, new,
                                                    &(dict->list[k]));
                                        }
                                }
                        }
                }
        }
        new->base_addr = new;
}

int
mac_policy_register(struct mac_policy_conf *mpc, mac_policy_handle_t *handlep,
    void *xd)
{
#if XNU_TARGET_OS_OSX
        struct mac_policy_list_element *tmac_policy_list_element;
#endif
        int error, slot, static_entry = 0;
        u_int i;

        /*
         * Some preliminary checks to make sure the policy's conf structure
         * contains the required fields.
         */
        if (mpc->mpc_name == NULL) {
                panic("policy's name is not set\n");
        }

        if (mpc->mpc_fullname == NULL) {
                panic("policy's full name is not set\n");
        }

        if (mpc->mpc_labelname_count > MAC_MAX_MANAGED_NAMESPACES) {
                panic("policy's managed label namespaces exceeds maximum\n");
        }

        if (mpc->mpc_ops == NULL) {
                panic("policy's OPs field is NULL\n");
        }

        error = 0;

        if (mac_late) {
                if (mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_NOTLATE) {
                        printf("Module %s does not support late loading.\n",
                            mpc->mpc_name);
                        return EPERM;
                }
                mac_policy_grab_exclusive();
        }

        if (mac_policy_list.numloaded >= mac_policy_list.max) {
#if XNU_TARGET_OS_OSX
                /* allocate new policy list array, zero new chunk */
                tmac_policy_list_element =
                    kalloc((sizeof(struct mac_policy_list_element) *
                    MAC_POLICY_LIST_CHUNKSIZE) * (mac_policy_list.chunks + 1));
                bzero(&tmac_policy_list_element[mac_policy_list.max],
                    sizeof(struct mac_policy_list_element) *
                    MAC_POLICY_LIST_CHUNKSIZE);

                /* copy old entries into new list */
                memcpy(tmac_policy_list_element, mac_policy_list.entries,
                    sizeof(struct mac_policy_list_element) *
                    MAC_POLICY_LIST_CHUNKSIZE * mac_policy_list.chunks);

                /* free old array */
                kfree(mac_policy_list.entries,
                    sizeof(struct mac_policy_list_element) *
                    MAC_POLICY_LIST_CHUNKSIZE * mac_policy_list.chunks);

                mac_policy_list.entries = tmac_policy_list_element;

                /* Update maximums, etc */
                mac_policy_list.max += MAC_POLICY_LIST_CHUNKSIZE;
                mac_policy_list.chunks++;
#else
                printf("out of space in mac_policy_list.\n");
                return ENOMEM;
#endif /* XNU_TARGET_OS_OSX */
        }

        /* Check for policy with same name already loaded */
        for (i = 0; i <= mac_policy_list.maxindex; i++) {
                if (mac_policy_list.entries[i].mpc == NULL) {
                        continue;
                }

                if (strcmp(mac_policy_list.entries[i].mpc->mpc_name,
                    mpc->mpc_name) == 0) {
                        error = EEXIST;
                        goto out;
                }
        }

        if (mpc->mpc_field_off != NULL) {
                slot = ffs(mac_slot_offsets_free);
                if (slot == 0) {
                        error = ENOMEM;
                        goto out;
                }
                slot--;
                mac_slot_offsets_free &= ~(1 << slot);
                *mpc->mpc_field_off = slot;
        }
        mpc->mpc_runtime_flags |= MPC_RUNTIME_FLAG_REGISTERED;

        if (xd) {
                struct mac_module_data *mmd = xd; /* module data from plist */

                /* Make a copy of the data. */
                mpc->mpc_data = (void *)kalloc(mmd->size);
                if (mpc->mpc_data != NULL) {
                        memcpy(mpc->mpc_data, mmd, mmd->size);

                        /* Fix up pointers after copy. */
                        mac_policy_fixup_mmd_list(mpc->mpc_data);
                }
        }

        /* Find the first free handle in the list (using our hint). */
        for (i = mac_policy_list.freehint; i < mac_policy_list.max; i++) {
                if (mac_policy_list.entries[i].mpc == NULL) {
                        *handlep = i;
                        mac_policy_list.freehint = ++i;
                        break;
                }
        }

        /*
         * If we are loading a MAC module before the framework has
         * finished initializing or the module is not unloadable and
         * we can place its handle adjacent to the last static entry,
         * bump the static policy high water mark.
         * Static policies can get by with weaker locking requirements.
         */
        if (!mac_late ||
            ((mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_UNLOADOK) == 0 &&
            *handlep == mac_policy_list.staticmax)) {
                static_entry = 1;
                mac_policy_list.staticmax++;
        }

        mac_policy_list.entries[*handlep].mpc = mpc;

        /* Update counters, etc */
        if (*handlep > mac_policy_list.maxindex) {
                mac_policy_list.maxindex = *handlep;
        }
        mac_policy_list.numloaded++;

        /* Per-policy initialization. */
        printf("calling mpo_policy_init for %s\n", mpc->mpc_name);
        if (mpc->mpc_ops->mpo_policy_init != NULL) {
                (*(mpc->mpc_ops->mpo_policy_init))(mpc);
        }

        if (mac_late && mpc->mpc_ops->mpo_policy_initbsd != NULL) {
                printf("calling mpo_policy_initbsd for %s\n", mpc->mpc_name);
                (*(mpc->mpc_ops->mpo_policy_initbsd))(mpc);
        }

        mac_policy_updateflags();

        if (mac_late) {
                mac_policy_release_exclusive();
        }

        mac_policy_addto_labellist(*handlep, static_entry);

        printf("Security policy loaded: %s (%s)\n", mpc->mpc_fullname,
            mpc->mpc_name);

        return 0;

out:
        if (mac_late) {
                mac_policy_release_exclusive();
        }

        return error;
}

int
mac_policy_unregister(mac_policy_handle_t handle)
{
        struct mac_policy_conf *mpc;

        /*
         * If we fail the load, we may get a request to unload.  Check
         * to see if we did the run-time registration, and if not,
         * silently succeed.
         */
        mac_policy_grab_exclusive();
        mpc = mac_get_mpc(handle);
        if ((mpc->mpc_runtime_flags & MPC_RUNTIME_FLAG_REGISTERED) == 0) {
                mac_policy_release_exclusive();
                return 0;
        }

#if 0
        /*
         * Don't allow unloading modules with private data.
         */
        if (mpc->mpc_field_off != NULL) {
                MAC_POLICY_LIST_UNLOCK();
                return EBUSY;
        }
#endif
        /*
         * Only allow the unload to proceed if the module is unloadable
         * by its own definition.
         */
        if ((mpc->mpc_loadtime_flags & MPC_LOADTIME_FLAG_UNLOADOK) == 0) {
                mac_policy_release_exclusive();
                return EBUSY;
        }

        mac_policy_removefrom_labellist(handle);

        mac_get_mpc(handle) = NULL;
        if (handle < mac_policy_list.freehint &&
            handle >= mac_policy_list.staticmax) {
                mac_policy_list.freehint = handle;
        }

        if (handle == mac_policy_list.maxindex) {
                mac_policy_list.maxindex--;
        }

        mac_policy_list.numloaded--;
        if (mpc->mpc_field_off != NULL) {
                mac_slot_offsets_free |= (1 << *mpc->mpc_field_off);
        }

        if (mpc->mpc_ops->mpo_policy_destroy != NULL) {
                (*(mpc->mpc_ops->mpo_policy_destroy))(mpc);
        }

        mpc->mpc_runtime_flags &= ~MPC_RUNTIME_FLAG_REGISTERED;
        mac_policy_updateflags();

        mac_policy_release_exclusive();

        if (mpc->mpc_data) {
                struct mac_module_data *mmd = mpc->mpc_data;
                kfree(mmd, mmd->size);
                mpc->mpc_data = NULL;
        }

        printf("Security policy unload: %s (%s)\n", mpc->mpc_fullname,
            mpc->mpc_name);

        return 0;
}

/*
 * Define an error value precedence, and given two arguments, selects the
 * value with the higher precedence.
 */
int
mac_error_select(int error1, int error2)
{
        /* Certain decision-making errors take top priority. */
        if (error1 == EDEADLK || error2 == EDEADLK) {
                return EDEADLK;
        }

        /* Invalid arguments should be reported where possible. */
        if (error1 == EINVAL || error2 == EINVAL) {
                return EINVAL;
        }

        /* Precedence goes to "visibility", with both process and file. */
        if (error1 == ESRCH || error2 == ESRCH) {
                return ESRCH;
        }

        if (error1 == ENOENT || error2 == ENOENT) {
                return ENOENT;
        }

        /* Precedence goes to DAC/MAC protections. */
        if (error1 == EACCES || error2 == EACCES) {
                return EACCES;
        }

        /* Precedence goes to privilege. */
        if (error1 == EPERM || error2 == EPERM) {
                return EPERM;
        }

        /* Precedence goes to error over success; otherwise, arbitrary. */
        if (error1 != 0) {
                return error1;
        }
        return error2;
}

void
mac_label_init(struct label *label)
{
        bzero(label, sizeof(*label));
        label->l_flags = MAC_FLAG_INITIALIZED;
}

void
mac_label_destroy(struct label *label)
{
        KASSERT(label->l_flags & MAC_FLAG_INITIALIZED,
            ("destroying uninitialized label"));

        bzero(label, sizeof(*label));
        /* implicit: label->l_flags &= ~MAC_FLAG_INITIALIZED; */
}

int
mac_check_structmac_consistent(struct user_mac *mac)
{
        if (mac->m_buflen > MAC_MAX_LABEL_BUF_LEN || mac->m_buflen == 0) {
                return EINVAL;
        }

        return 0;
}

/*
 * Get the external forms of labels from all policies, for a single
 * label namespace or "*" for all namespaces.  Returns ENOENT if no policy
 * is registered for the namespace, unless the namespace begins with a '?'.
 */
static int
mac_label_externalize(size_t mpo_externalize_off, struct label *label,
    const char *element, struct sbuf *sb)
{
        struct mac_policy_conf *mpc;
        struct mac_label_listener *mll;
        struct mac_label_element *mle;
        struct mac_label_element_list_t *element_list;
        const char *name;
        int (*mpo_externalize)(struct label *, char *, struct sbuf *);
        int all_labels = 0, ignorenotfound = 0, error = 0, busy = FALSE;
        int sb_pos;
        unsigned int count = 0;

        if (element[0] == '?') {
                element++;
                ignorenotfound = 1;
        } else if (element[0] == '*' && element[1] == '\0') {
                all_labels = 1;
        }

        element_list = &mac_static_label_element_list;
element_loop:
        LIST_FOREACH(mle, element_list, mle_list) {
                name = mle->mle_name;
                if (all_labels) {
                        if (*name == '?') {
                                continue;
                        }
                } else {
                        if (*name == '?') {
                                name++;
                        }
                        if (strcmp(name, element) != 0) {
                                continue;
                        }
                }
                LIST_FOREACH(mll, &mle->mle_listeners, mll_list) {
                        mpc = mac_policy_list.entries[mll->mll_handle].mpc;
                        if (mpc == NULL) {
                                continue;
                        }
                        mpo_externalize = *(const typeof(mpo_externalize) *)
                            ((const char *)mpc->mpc_ops + mpo_externalize_off);
                        if (mpo_externalize == NULL) {
                                continue;
                        }
                        sb_pos = sbuf_len(sb);
                        error = sbuf_printf(sb, "%s/", name);
                        if (error) {
                                goto done;
                        }
                        error = mpo_externalize(label, mle->mle_name, sb);
                        if (error) {
                                if (error != ENOENT) {
                                        goto done;
                                }
                                /*
                                 * If a policy doesn't have a label to
                                 * externalize it returns ENOENT.  This
                                 * may occur for policies that support
                                 * multiple label elements for some
                                 * (but not all) object types.
                                 */
                                sbuf_setpos(sb, sb_pos);
                                error = 0;
                                continue;
                        }
                        error = sbuf_putc(sb, ',');
                        if (error) {
                                goto done;
                        }
                        count++;
                }
        }
        /* If there are dynamic policies present, check their elements too. */
        if (!busy && mac_policy_list_conditional_busy() == 1) {
                element_list = &mac_label_element_list;
                busy = TRUE;
                goto element_loop;
        }
done:
        if (busy) {
                mac_policy_list_unbusy();
        }
        if (!error && count == 0) {
                if (!all_labels && !ignorenotfound) {
                        error = ENOENT; /* XXX: ENOLABEL? */
                }
        }
        return error;
}

/*
 * Get the external forms of labels from all policies, for all label
 * namespaces contained in a list.
 *
 * XXX This may be leaking an sbuf.
 */
int
mac_externalize(size_t mpo_externalize_off, struct label *label,
    const char *elementlist, char *outbuf, size_t outbuflen)
{
        char *element;
        char *scratch_base;
        char *scratch;
        struct sbuf sb;
        int error = 0, len;

        /* allocate a scratch buffer the size of the string */
        MALLOC(scratch_base, char *, strlen(elementlist) + 1, M_MACTEMP, M_WAITOK);
        if (scratch_base == NULL) {
                error = ENOMEM;
                goto out;
        }

        /* copy the elementlist to the scratch buffer */
        strlcpy(scratch_base, elementlist, strlen(elementlist) + 1);

        /*
         * set up a temporary pointer that can be used to iterate the
         * scratch buffer without losing the allocation address
         */
        scratch = scratch_base;

        /*
         * initialize an sbuf mapping over the output buffer (or newly-allocated internal buffer, if
         * outbuf is NULL), up to sbuf's limit of INT_MAX.
         */
        if (outbuflen > INT_MAX) {
                outbuflen = INT_MAX;
        }
        if (sbuf_new(&sb, outbuf, (int)outbuflen, SBUF_FIXEDLEN) == NULL) {
                /* could not allocate interior buffer */
                error = ENOMEM;
                goto out;
        }
        /* iterate the scratch buffer; NOTE: buffer contents modified! */
        while ((element = strsep(&scratch, ",")) != NULL) {
                error = mac_label_externalize(mpo_externalize_off, label,
                    element, &sb);
                if (error) {
                        break;
                }
        }
        if ((len = sbuf_len(&sb)) > 0) {
                sbuf_setpos(&sb, len - 1);      /* trim trailing comma */
        }
        sbuf_finish(&sb);

out:
        if (scratch_base != NULL) {
                FREE(scratch_base, M_MACTEMP);
        }

        return error;
}

/*
 * Have all policies set the internal form of a label, for a single
 * label namespace.
 */
static int
mac_label_internalize(size_t mpo_internalize_off, struct label *label,
    char *element_name, char *element_data)
{
        struct mac_policy_conf *mpc;
        struct mac_label_listener *mll;
        struct mac_label_element *mle;
        struct mac_label_element_list_t *element_list;
        int (*mpo_internalize)(struct label *, char *, char *);
        int error = 0, busy = FALSE;
        unsigned int count = 0;
        const char *name;

        element_list = &mac_static_label_element_list;
element_loop:
        LIST_FOREACH(mle, element_list, mle_list) {
                if (*(name = mle->mle_name) == '?') {
                        name++;
                }
                if (strcmp(element_name, name) != 0) {
                        continue;
                }
                LIST_FOREACH(mll, &mle->mle_listeners, mll_list) {
                        mpc = mac_policy_list.entries[mll->mll_handle].mpc;
                        if (mpc == NULL) {
                                continue;
                        }
                        mpo_internalize = *(const typeof(mpo_internalize) *)
                            ((const char *)mpc->mpc_ops + mpo_internalize_off);
                        if (mpo_internalize == NULL) {
                                continue;
                        }
                        error = mpo_internalize(label, element_name,
                            element_data);
                        if (error) {
                                goto done;
                        }
                        count++;
                }
        }
        /* If there are dynamic policies present, check their elements too. */
        if (!busy && mac_policy_list_conditional_busy() == 1) {
                element_list = &mac_label_element_list;
                busy = TRUE;
                goto element_loop;
        }
done:
        if (busy) {
                mac_policy_list_unbusy();
        }
        if (!error && count == 0) {
                error = ENOPOLICY;
        }
        return error;
}

int
mac_internalize(size_t mpo_internalize_off, struct label *label,
    char *textlabels)
{
        char *element_name, *element_data;
        int error = 0;

        while (!error && (element_name = strsep(&textlabels, ",")) != NULL) {
                element_data = strchr(element_name, '/');
                if (element_data == NULL) {
                        error = EINVAL;
                        break;
                }
                *element_data++ = '\0';
                error = mac_label_internalize(mpo_internalize_off, label,
                    element_name, element_data);
        }
        return error;
}

/* system calls */

int
__mac_get_pid(struct proc *p, struct __mac_get_pid_args *uap, int *ret __unused)
{
        char *elements, *buffer;
        struct user_mac mac;
        struct proc *tproc;
        struct ucred *tcred;
        int error;
        size_t ulen;

        AUDIT_ARG(pid, uap->pid);
        if (IS_64BIT_PROCESS(p)) {
                struct user64_mac mac64;
                error = copyin(uap->mac_p, &mac64, sizeof(mac64));
                mac.m_buflen = mac64.m_buflen;
                mac.m_string = mac64.m_string;
        } else {
                struct user32_mac mac32;
                error = copyin(uap->mac_p, &mac32, sizeof(mac32));
                mac.m_buflen = mac32.m_buflen;
                mac.m_string = mac32.m_string;
        }
        if (error) {
                return error;
        }

        error = mac_check_structmac_consistent(&mac);
        if (error) {
                return error;
        }

        tproc = proc_find(uap->pid);
        if (tproc == NULL) {
                return ESRCH;
        }
        tcred = kauth_cred_proc_ref(tproc);
        proc_rele(tproc);

        MALLOC(elements, char *, mac.m_buflen, M_MACTEMP, M_WAITOK);
        error = copyinstr(mac.m_string, elements, mac.m_buflen, &ulen);
        if (error) {
                FREE(elements, M_MACTEMP);
                kauth_cred_unref(&tcred);
                return error;
        }
        AUDIT_ARG(mac_string, elements);

        MALLOC(buffer, char *, mac.m_buflen, M_MACTEMP, M_WAITOK | M_ZERO);
        error = mac_cred_label_externalize(tcred->cr_label, elements,
            buffer, mac.m_buflen, M_WAITOK);
        if (error == 0) {
                error = copyout(buffer, mac.m_string, strlen(buffer) + 1);
        }

        FREE(buffer, M_MACTEMP);
        FREE(elements, M_MACTEMP);
        kauth_cred_unref(&tcred);
        return error;
}

int
__mac_get_proc(proc_t p, struct __mac_get_proc_args *uap, int *ret __unused)
{
        char *elements, *buffer;
        struct user_mac mac;
        kauth_cred_t cr;
        int error;
        size_t ulen;

        if (IS_64BIT_PROCESS(p)) {
                struct user64_mac mac64;
                error = copyin(uap->mac_p, &mac64, sizeof(mac64));
                mac.m_buflen = mac64.m_buflen;
                mac.m_string = mac64.m_string;
        } else {
                struct user32_mac mac32;
                error = copyin(uap->mac_p, &mac32, sizeof(mac32));
                mac.m_buflen = mac32.m_buflen;
                mac.m_string = mac32.m_string;
        }
        if (error) {
                return error;
        }

        error = mac_check_structmac_consistent(&mac);
        if (error) {
                return error;
        }

        MALLOC(elements, char *, mac.m_buflen, M_MACTEMP, M_WAITOK);
        error = copyinstr(mac.m_string, elements, mac.m_buflen, &ulen);
        if (error) {
                FREE(elements, M_MACTEMP);
                return error;
        }
        AUDIT_ARG(mac_string, elements);

        cr = kauth_cred_proc_ref(p);

        MALLOC(buffer, char *, mac.m_buflen, M_MACTEMP, M_WAITOK | M_ZERO);
        error = mac_cred_label_externalize(cr->cr_label,
            elements, buffer, mac.m_buflen, M_WAITOK);
        if (error == 0) {
                error = copyout(buffer, mac.m_string, strlen(buffer) + 1);
        }

        FREE(buffer, M_MACTEMP);
        FREE(elements, M_MACTEMP);
        kauth_cred_unref(&cr);
        return error;
}

int
__mac_set_proc(proc_t p, struct __mac_set_proc_args *uap, int *ret __unused)
{
        struct label *intlabel;
        struct user_mac mac;
        char *buffer;
        int error;
        size_t ulen;

        if (IS_64BIT_PROCESS(p)) {
                struct user64_mac mac64;
                error = copyin(uap->mac_p, &mac64, sizeof(mac64));
                mac.m_buflen = mac64.m_buflen;
                mac.m_string = mac64.m_string;
        } else {
                struct user32_mac mac32;
                error = copyin(uap->mac_p, &mac32, sizeof(mac32));
                mac.m_buflen = mac32.m_buflen;
                mac.m_string = mac32.m_string;
        }
        if (error) {
                return error;
        }

        error = mac_check_structmac_consistent(&mac);
        if (error) {
                return error;
        }

        MALLOC(buffer, char *, mac.m_buflen, M_MACTEMP, M_WAITOK);
        error = copyinstr(mac.m_string, buffer, mac.m_buflen, &ulen);
        if (error) {
                FREE(buffer, M_MACTEMP);
                return error;
        }
        AUDIT_ARG(mac_string, buffer);

        intlabel = mac_cred_label_alloc();
        error = mac_cred_label_internalize(intlabel, buffer);
        FREE(buffer, M_MACTEMP);
        if (error) {
                goto out;
        }

        error = mac_cred_check_label_update(kauth_cred_get(), intlabel);
        if (error) {
                goto out;
        }

        error = kauth_proc_label_update(p, intlabel);
        if (error) {
                goto out;
        }

out:
        mac_cred_label_free(intlabel);
        return error;
}

int
__mac_get_fd(proc_t p, struct __mac_get_fd_args *uap, int *ret __unused)
{
        struct fileproc *fp;
        struct vnode *vp;
        struct user_mac mac;
        char *elements, *buffer;
        int error;
        size_t ulen;
        kauth_cred_t my_cred;
        struct label *intlabel;

        AUDIT_ARG(fd, uap->fd);

        if (IS_64BIT_PROCESS(p)) {
                struct user64_mac mac64;
                error = copyin(uap->mac_p, &mac64, sizeof(mac64));
                mac.m_buflen = mac64.m_buflen;
                mac.m_string = mac64.m_string;
        } else {
                struct user32_mac mac32;
                error = copyin(uap->mac_p, &mac32, sizeof(mac32));
                mac.m_buflen = mac32.m_buflen;
                mac.m_string = mac32.m_string;
        }

        if (error) {
                return error;
        }

        error = mac_check_structmac_consistent(&mac);
        if (error) {
                return error;
        }

        MALLOC(elements, char *, mac.m_buflen, M_MACTEMP, M_WAITOK);
        error = copyinstr(mac.m_string, elements, mac.m_buflen, &ulen);
        if (error) {
                FREE(elements, M_MACTEMP);
                return error;
        }
        AUDIT_ARG(mac_string, elements);

        MALLOC(buffer, char *, mac.m_buflen, M_MACTEMP, M_WAITOK);
        error = fp_lookup(p, uap->fd, &fp, 0);
        if (error) {
                FREE(buffer, M_MACTEMP);
                FREE(elements, M_MACTEMP);
                return error;
        }

        my_cred = kauth_cred_proc_ref(p);
        error = mac_file_check_get(my_cred, fp->fp_glob, elements, mac.m_buflen);
        kauth_cred_unref(&my_cred);
        if (error) {
                fp_drop(p, uap->fd, fp, 0);
                FREE(buffer, M_MACTEMP);
                FREE(elements, M_MACTEMP);
                return error;
        }

        switch (FILEGLOB_DTYPE(fp->fp_glob)) {
        case DTYPE_VNODE:
                intlabel = mac_vnode_label_alloc();
                if (intlabel == NULL) {
                        error = ENOMEM;
                        break;
                }
                vp = (struct vnode *)fp->fp_glob->fg_data;
                error = vnode_getwithref(vp);
                if (error == 0) {
                        mac_vnode_label_copy(vp->v_label, intlabel);
                        error = mac_vnode_label_externalize(intlabel,
                            elements, buffer,
                            mac.m_buflen, M_WAITOK);
                        vnode_put(vp);
                }
                mac_vnode_label_free(intlabel);
                break;
        case DTYPE_SOCKET:
        case DTYPE_PSXSHM:
        case DTYPE_PSXSEM:
        case DTYPE_PIPE:
        case DTYPE_KQUEUE:
        case DTYPE_FSEVENTS:
        case DTYPE_ATALK:
        case DTYPE_NETPOLICY:
        default:
                error = ENOSYS;           // only sockets/vnodes so far
                break;
        }
        fp_drop(p, uap->fd, fp, 0);

        if (error == 0) {
                error = copyout(buffer, mac.m_string, strlen(buffer) + 1);
        }

        FREE(buffer, M_MACTEMP);
        FREE(elements, M_MACTEMP);
        return error;
}

static int
mac_get_filelink(proc_t p, user_addr_t mac_p, user_addr_t path_p, int follow)
{
        struct vnode *vp;
        vfs_context_t ctx;
        char *elements, *buffer;
        struct nameidata nd;
        struct label *intlabel;
        struct user_mac mac;
        int error;
        size_t ulen;

        if (IS_64BIT_PROCESS(p)) {
                struct user64_mac mac64;
                error = copyin(mac_p, &mac64, sizeof(mac64));
                mac.m_buflen = mac64.m_buflen;
                mac.m_string = mac64.m_string;
        } else {
                struct user32_mac mac32;
                error = copyin(mac_p, &mac32, sizeof(mac32));
                mac.m_buflen = mac32.m_buflen;
                mac.m_string = mac32.m_string;
        }

        if (error) {
                return error;
        }

        error = mac_check_structmac_consistent(&mac);
        if (error) {
                return error;
        }

        MALLOC(elements, char *, mac.m_buflen, M_MACTEMP, M_WAITOK);
        MALLOC(buffer, char *, mac.m_buflen, M_MACTEMP, M_WAITOK | M_ZERO);

        error = copyinstr(mac.m_string, elements, mac.m_buflen, &ulen);
        if (error) {
                FREE(buffer, M_MACTEMP);
                FREE(elements, M_MACTEMP);
                return error;
        }
        AUDIT_ARG(mac_string, elements);

        ctx = vfs_context_current();

        NDINIT(&nd, LOOKUP, OP_LOOKUP,
            LOCKLEAF | (follow ? FOLLOW : NOFOLLOW) | AUDITVNPATH1,
            UIO_USERSPACE, path_p, ctx);
        error = namei(&nd);
        if (error) {
                FREE(buffer, M_MACTEMP);
                FREE(elements, M_MACTEMP);
                return error;
        }
        vp = nd.ni_vp;

        nameidone(&nd);

        intlabel = mac_vnode_label_alloc();
        mac_vnode_label_copy(vp->v_label, intlabel);
        error = mac_vnode_label_externalize(intlabel, elements, buffer,
            mac.m_buflen, M_WAITOK);
        mac_vnode_label_free(intlabel);
        if (error == 0) {
                error = copyout(buffer, mac.m_string, strlen(buffer) + 1);
        }

        vnode_put(vp);

        FREE(buffer, M_MACTEMP);
        FREE(elements, M_MACTEMP);

        return error;
}

int
__mac_get_file(proc_t p, struct __mac_get_file_args *uap,
    int *ret __unused)
{
        return mac_get_filelink(p, uap->mac_p, uap->path_p, 1);
}

int
__mac_get_link(proc_t p, struct __mac_get_link_args *uap,
    int *ret __unused)
{
        return mac_get_filelink(p, uap->mac_p, uap->path_p, 0);
}

int
__mac_set_fd(proc_t p, struct __mac_set_fd_args *uap, int *ret __unused)
{
        struct fileproc *fp;
        struct user_mac mac;
        struct vfs_context *ctx = vfs_context_current();
        int error;
        size_t ulen;
        char *buffer;
        struct label *intlabel;
        struct vnode *vp;

        AUDIT_ARG(fd, uap->fd);

        if (IS_64BIT_PROCESS(p)) {
                struct user64_mac mac64;
                error = copyin(uap->mac_p, &mac64, sizeof(mac64));
                mac.m_buflen = mac64.m_buflen;
                mac.m_string = mac64.m_string;
        } else {
                struct user32_mac mac32;
                error = copyin(uap->mac_p, &mac32, sizeof(mac32));
                mac.m_buflen = mac32.m_buflen;
                mac.m_string = mac32.m_string;
        }
        if (error) {
                return error;
        }

        error = mac_check_structmac_consistent(&mac);
        if (error) {
                return error;
        }

        MALLOC(buffer, char *, mac.m_buflen, M_MACTEMP, M_WAITOK);
        error = copyinstr(mac.m_string, buffer, mac.m_buflen, &ulen);
        if (error) {
                FREE(buffer, M_MACTEMP);
                return error;
        }
        AUDIT_ARG(mac_string, buffer);

        error = fp_lookup(p, uap->fd, &fp, 0);
        if (error) {
                FREE(buffer, M_MACTEMP);
                return error;
        }


        error = mac_file_check_set(vfs_context_ucred(ctx), fp->fp_glob, buffer, mac.m_buflen);
        if (error) {
                fp_drop(p, uap->fd, fp, 0);
                FREE(buffer, M_MACTEMP);
                return error;
        }

        switch (FILEGLOB_DTYPE(fp->fp_glob)) {
        case DTYPE_VNODE:
                if (mac_label_vnodes == 0) {
                        error = ENOSYS;
                        break;
                }

                intlabel = mac_vnode_label_alloc();

                error = mac_vnode_label_internalize(intlabel, buffer);
                if (error) {
                        mac_vnode_label_free(intlabel);
                        break;
                }


                vp = (struct vnode *)fp->fp_glob->fg_data;

                error = vnode_getwithref(vp);
                if (error == 0) {
                        error = vn_setlabel(vp, intlabel, ctx);
                        vnode_put(vp);
                }
                mac_vnode_label_free(intlabel);
                break;

        case DTYPE_SOCKET:
        case DTYPE_PSXSHM:
        case DTYPE_PSXSEM:
        case DTYPE_PIPE:
        case DTYPE_KQUEUE:
        case DTYPE_FSEVENTS:
        case DTYPE_ATALK:
        case DTYPE_NETPOLICY:
        default:
                error = ENOSYS;          // only sockets/vnodes so far
                break;
        }

        fp_drop(p, uap->fd, fp, 0);
        FREE(buffer, M_MACTEMP);
        return error;
}

static int
mac_set_filelink(proc_t p, user_addr_t mac_p, user_addr_t path_p,
    int follow)
{
        struct vnode *vp;
        struct vfs_context *ctx = vfs_context_current();
        struct label *intlabel;
        struct nameidata nd;
        struct user_mac mac;
        char *buffer;
        int error;
        size_t ulen;

        if (mac_label_vnodes == 0) {
                return ENOSYS;
        }

        if (IS_64BIT_PROCESS(p)) {
                struct user64_mac mac64;
                error = copyin(mac_p, &mac64, sizeof(mac64));
                mac.m_buflen = mac64.m_buflen;
                mac.m_string = mac64.m_string;
        } else {
                struct user32_mac mac32;
                error = copyin(mac_p, &mac32, sizeof(mac32));
                mac.m_buflen = mac32.m_buflen;
                mac.m_string = mac32.m_string;
        }
        if (error) {
                return error;
        }

        error = mac_check_structmac_consistent(&mac);
        if (error) {
                printf("mac_set_file: failed structure consistency check\n");
                return error;
        }

        MALLOC(buffer, char *, mac.m_buflen, M_MACTEMP, M_WAITOK);
        error = copyinstr(mac.m_string, buffer, mac.m_buflen, &ulen);
        if (error) {
                FREE(buffer, M_MACTEMP);
                return error;
        }
        AUDIT_ARG(mac_string, buffer);

        intlabel = mac_vnode_label_alloc();
        error = mac_vnode_label_internalize(intlabel, buffer);
        FREE(buffer, M_MACTEMP);
        if (error) {
                mac_vnode_label_free(intlabel);
                return error;
        }

        NDINIT(&nd, LOOKUP, OP_LOOKUP,
            LOCKLEAF | (follow ? FOLLOW : NOFOLLOW) | AUDITVNPATH1,
            UIO_USERSPACE, path_p, ctx);
        error = namei(&nd);
        if (error) {
                mac_vnode_label_free(intlabel);
                return error;
        }
        vp = nd.ni_vp;

        nameidone(&nd);

        error = vn_setlabel(vp, intlabel, ctx);
        vnode_put(vp);
        mac_vnode_label_free(intlabel);

        return error;
}

int
__mac_set_file(proc_t p, struct __mac_set_file_args *uap,
    int *ret __unused)
{
        return mac_set_filelink(p, uap->mac_p, uap->path_p, 1);
}

int
__mac_set_link(proc_t p, struct __mac_set_link_args *uap,
    int *ret __unused)
{
        return mac_set_filelink(p, uap->mac_p, uap->path_p, 0);
}

/*
 * __mac_syscall: Perform a MAC policy system call
 *
 * Parameters:    p                       Process calling this routine
 *                uap                     User argument descriptor (see below)
 *                retv                    (Unused)
 *
 * Indirect:      uap->policy             Name of target MAC policy
 *                uap->call               MAC policy-specific system call to perform
 *                uap->arg                MAC policy-specific system call arguments
 *
 * Returns:        0                      Success
 *                !0                      Not success
 *
 */
int
__mac_syscall(proc_t p, struct __mac_syscall_args *uap, int *retv __unused)
{
        struct mac_policy_conf *mpc;
        char target[MAC_MAX_POLICY_NAME];
        int error;
        u_int i;
        size_t ulen;

        error = copyinstr(uap->policy, target, sizeof(target), &ulen);
        if (error) {
                return error;
        }
        AUDIT_ARG(value32, uap->call);
        AUDIT_ARG(mac_string, target);

        error = ENOPOLICY;

        for (i = 0; i < mac_policy_list.staticmax; i++) {
                mpc = mac_policy_list.entries[i].mpc;
                if (mpc == NULL) {
                        continue;
                }

                if (strcmp(mpc->mpc_name, target) == 0 &&
                    mpc->mpc_ops->mpo_policy_syscall != NULL) {
                        error = mpc->mpc_ops->mpo_policy_syscall(p,
                            uap->call, uap->arg);
                        goto done;
                }
        }
        if (mac_policy_list_conditional_busy() != 0) {
                for (; i <= mac_policy_list.maxindex; i++) {
                        mpc = mac_policy_list.entries[i].mpc;
                        if (mpc == NULL) {
                                continue;
                        }

                        if (strcmp(mpc->mpc_name, target) == 0 &&
                            mpc->mpc_ops->mpo_policy_syscall != NULL) {
                                error = mpc->mpc_ops->mpo_policy_syscall(p,
                                    uap->call, uap->arg);
                                break;
                        }
                }
                mac_policy_list_unbusy();
        }

done:
        return error;
}

int
mac_mount_label_get(struct mount *mp, user_addr_t mac_p)
{
        char *elements, *buffer;
        struct label *label;
        struct user_mac mac;
        int error;
        size_t ulen;

        if (IS_64BIT_PROCESS(current_proc())) {
                struct user64_mac mac64;
                error = copyin(mac_p, &mac64, sizeof(mac64));
                mac.m_buflen = mac64.m_buflen;
                mac.m_string = mac64.m_string;
        } else {
                struct user32_mac mac32;
                error = copyin(mac_p, &mac32, sizeof(mac32));
                mac.m_buflen = mac32.m_buflen;
                mac.m_string = mac32.m_string;
        }
        if (error) {
                return error;
        }

        error = mac_check_structmac_consistent(&mac);
        if (error) {
                return error;
        }

        MALLOC(elements, char *, mac.m_buflen, M_MACTEMP, M_WAITOK);
        error = copyinstr(mac.m_string, elements, mac.m_buflen, &ulen);
        if (error) {
                FREE(elements, M_MACTEMP);
                return error;
        }
        AUDIT_ARG(mac_string, elements);

        label = mp->mnt_mntlabel;
        MALLOC(buffer, char *, mac.m_buflen, M_MACTEMP, M_WAITOK | M_ZERO);
        error = mac_mount_label_externalize(label, elements, buffer,
            mac.m_buflen);
        FREE(elements, M_MACTEMP);

        if (error == 0) {
                error = copyout(buffer, mac.m_string, strlen(buffer) + 1);
        }
        FREE(buffer, M_MACTEMP);

        return error;
}

/*
 * __mac_get_mount: Get mount point label information for a given pathname
 *
 * Parameters:    p                        (ignored)
 *                uap                      User argument descriptor (see below)
 *                ret                      (ignored)
 *
 * Indirect:      uap->path                Pathname
 *                uap->mac_p               MAC info
 *
 * Returns:        0                       Success
 *                !0                       Not success
 */
int
__mac_get_mount(proc_t p __unused, struct __mac_get_mount_args *uap,
    int *ret __unused)
{
        struct nameidata nd;
        struct vfs_context *ctx = vfs_context_current();
        struct mount *mp;
        int error;

        NDINIT(&nd, LOOKUP, OP_LOOKUP, FOLLOW | AUDITVNPATH1,
            UIO_USERSPACE, uap->path, ctx);
        error = namei(&nd);
        if (error) {
                return error;
        }
        mp = nd.ni_vp->v_mount;
        mount_ref(mp, 0);
        vnode_put(nd.ni_vp);
        nameidone(&nd);

        error = mac_mount_label_get(mp, uap->mac_p);
        mount_drop(mp, 0);
        return error;
}

/*
 * mac_schedule_userret()
 *
 * Schedule a callback to the mpo_thread_userret hook. The mpo_thread_userret
 * hook is called just before the thread exit from the kernel in ast_taken().
 *
 * Returns:      0              Success
 *              !0              Not successful
 */
int
mac_schedule_userret(void)
{
        act_set_astmacf(current_thread());
        return 0;
}

/*
 * mac_do_machexc()
 *
 * Do a Mach exception.  This should only be done in the mpo_thread_userret
 * callback.
 *
 * params:      code            exception code
 *              subcode         exception subcode
 *              flags           flags:
 *                              MAC_DOEXCF_TRACED  Only do exception if being
 *                                                 ptrace()'ed.
 *
 *
 * Returns:      0              Success
 *              !0              Not successful
 */
int
mac_do_machexc(int64_t code, int64_t subcode, uint32_t flags)
{
        mach_exception_data_type_t  codes[EXCEPTION_CODE_MAX];
        proc_t p = current_proc();

        /* Only allow execption codes in MACF's reserved range. */
        if ((code < EXC_MACF_MIN) || (code > EXC_MACF_MAX)) {
                return 1;
        }

        if (flags & MAC_DOEXCF_TRACED &&
            !(p->p_lflag & P_LTRACED && (p->p_lflag & P_LPPWAIT) == 0)) {
                return 0;
        }


        /* Send the Mach exception */
        codes[0] = (mach_exception_data_type_t)code;
        codes[1] = (mach_exception_data_type_t)subcode;

        return bsd_exception(EXC_SOFTWARE, codes, 2) != KERN_SUCCESS;
}

#else /* MAC */

void (*load_security_extensions_function)(void) = 0;

struct sysctl_oid_list sysctl__security_mac_children;

int
mac_policy_register(struct mac_policy_conf *mpc __unused,
    mac_policy_handle_t *handlep __unused, void *xd __unused)
{
        return 0;
}

int
mac_policy_unregister(mac_policy_handle_t handle __unused)
{
        return 0;
}

int
mac_audit_text(char *text __unused, mac_policy_handle_t handle __unused)
{
        return 0;
}

int
mac_vnop_setxattr(struct vnode *vp __unused, const char *name __unused, char *buf __unused, size_t len __unused)
{
        return ENOENT;
}

int
mac_vnop_getxattr(struct vnode *vp __unused, const char *name __unused,
    char *buf __unused, size_t len __unused, size_t *attrlen __unused)
{
        return ENOENT;
}

int
mac_vnop_removexattr(struct vnode *vp __unused, const char *name __unused)
{
        return ENOENT;
}

int
mac_file_setxattr(struct fileglob *fg __unused, const char *name __unused, char *buf __unused, size_t len __unused)
{
        return ENOENT;
}

int
mac_file_getxattr(struct fileglob *fg __unused, const char *name __unused,
    char *buf __unused, size_t len __unused, size_t *attrlen __unused)
{
        return ENOENT;
}

int
mac_file_removexattr(struct fileglob *fg __unused, const char *name __unused)
{
        return ENOENT;
}

intptr_t
mac_label_get(struct label *l __unused, int slot __unused)
{
        return 0;
}

void
mac_label_set(struct label *l __unused, int slot __unused, intptr_t v __unused)
{
        return;
}

int mac_iokit_check_hid_control(kauth_cred_t cred __unused);
int
mac_iokit_check_hid_control(kauth_cred_t cred __unused)
{
        return 0;
}

int mac_mount_check_snapshot_mount(vfs_context_t ctx, struct vnode *rvp, struct vnode *vp, struct componentname *cnp,
    const char *name, const char *vfc_name);
int
mac_mount_check_snapshot_mount(vfs_context_t ctx __unused, struct vnode *rvp __unused, struct vnode *vp __unused,
    struct componentname *cnp __unused, const char *name __unused, const char *vfc_name __unused)
{
        return 0;
}

int mac_vnode_check_trigger_resolve(vfs_context_t ctx __unused, struct vnode *dvp __unused, struct componentname *cnp __unused);
int
mac_vnode_check_trigger_resolve(vfs_context_t ctx __unused, struct vnode *dvp __unused, struct componentname *cnp __unused)
{
        return 0;
}

#endif /* !MAC */