[apple/xnu.git] / osfmk / ipc / ipc_object.c

/*
 * Copyright (c) 2000-2007 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,
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 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 */
/*
 * Mach Operating System
 * Copyright (c) 1991,1990,1989 Carnegie Mellon University
 * All Rights Reserved.
 *
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 * NOTICE: This file was modified by McAfee Research in 2004 to introduce
 * support for mandatory and extensible security protections.  This notice
 * is included in support of clause 2.2 (b) of the Apple Public License,
 * Version 2.0.
 * Copyright (c) 2005-2006 SPARTA, Inc.
 */
/*
 */
/*
 *      File:   ipc/ipc_object.c
 *      Author: Rich Draves
 *      Date:   1989
 *
 *      Functions to manipulate IPC objects.
 */

#include <mach/mach_types.h>
#include <mach/boolean.h>
#include <mach/kern_return.h>
#include <mach/port.h>
#include <mach/message.h>

#include <kern/kern_types.h>
#include <kern/misc_protos.h>
#include <kern/ipc_kobject.h>

#include <ipc/ipc_types.h>
#include <ipc/ipc_importance.h>
#include <ipc/port.h>
#include <ipc/ipc_space.h>
#include <ipc/ipc_entry.h>
#include <ipc/ipc_object.h>
#include <ipc/ipc_hash.h>
#include <ipc/ipc_right.h>
#include <ipc/ipc_notify.h>
#include <ipc/ipc_port.h>
#include <ipc/ipc_pset.h>

#include <security/mac_mach_internal.h>

zone_t ipc_object_zones[IOT_NUMBER];

/*
 *      Routine:        ipc_object_reference
 *      Purpose:
 *              Take a reference to an object.
 */

void
ipc_object_reference(
        ipc_object_t    object)
{
        io_reference(object);
}

/*
 *      Routine:        ipc_object_release
 *      Purpose:
 *              Release a reference to an object.
 */

void
ipc_object_release(
        ipc_object_t    object)
{
        io_release(object);
}

/*
 *      Routine:        ipc_object_translate
 *      Purpose:
 *              Look up an object in a space.
 *      Conditions:
 *              Nothing locked before.  If successful, the object
 *              is returned locked.  The caller doesn't get a ref.
 *      Returns:
 *              KERN_SUCCESS            Object returned locked.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       The name doesn't denote a right
 *              KERN_INVALID_RIGHT      Name doesn't denote the correct right
 */
kern_return_t
ipc_object_translate(
        ipc_space_t             space,
        mach_port_name_t        name,
        mach_port_right_t       right,
        ipc_object_t            *objectp)
{
        ipc_entry_t entry;
        ipc_object_t object;
        kern_return_t kr;

        kr = ipc_right_lookup_read(space, name, &entry);
        if (kr != KERN_SUCCESS) {
                return kr;
        }
        /* space is read-locked and active */

        if ((entry->ie_bits & MACH_PORT_TYPE(right)) == MACH_PORT_TYPE_NONE) {
                is_read_unlock(space);
                return KERN_INVALID_RIGHT;
        }

        object = entry->ie_object;
        assert(object != IO_NULL);

        io_lock(object);
        is_read_unlock(space);

        *objectp = object;
        return KERN_SUCCESS;
}

/*
 *      Routine:        ipc_object_translate_two
 *      Purpose:
 *              Look up two objects in a space.
 *      Conditions:
 *              Nothing locked before.  If successful, the objects
 *              are returned locked.  The caller doesn't get a ref.
 *      Returns:
 *              KERN_SUCCESS            Objects returned locked.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       A name doesn't denote a right.
 *              KERN_INVALID_RIGHT      A name doesn't denote the correct right.
 */

kern_return_t
ipc_object_translate_two(
        ipc_space_t             space,
        mach_port_name_t        name1,
        mach_port_right_t       right1,
        ipc_object_t            *objectp1,
        mach_port_name_t        name2,
        mach_port_right_t       right2,
        ipc_object_t            *objectp2)
{
        ipc_entry_t entry1;
        ipc_entry_t entry2;
        ipc_object_t object;
        kern_return_t kr;

        kr = ipc_right_lookup_two_read(space, name1, &entry1, name2, &entry2);
        if (kr != KERN_SUCCESS) {
                return kr;
        }
        /* space is read-locked and active */

        if ((entry1->ie_bits & MACH_PORT_TYPE(right1)) == MACH_PORT_TYPE_NONE) {
                is_read_unlock(space);
                mach_port_guard_exception(name1, 0, 0, kGUARD_EXC_INVALID_RIGHT);
                return KERN_INVALID_RIGHT;
        }

        if ((entry2->ie_bits & MACH_PORT_TYPE(right2)) == MACH_PORT_TYPE_NONE) {
                is_read_unlock(space);
                mach_port_guard_exception(name2, 0, 0, kGUARD_EXC_INVALID_RIGHT);
                return KERN_INVALID_RIGHT;
        }

        object = entry1->ie_object;
        assert(object != IO_NULL);
        io_lock(object);
        *objectp1 = object;

        object = entry2->ie_object;
        assert(object != IO_NULL);
        io_lock(object);
        *objectp2 = object;

        is_read_unlock(space);
        return KERN_SUCCESS;
}

/*
 *      Routine:        ipc_object_alloc_dead
 *      Purpose:
 *              Allocate a dead-name entry.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            The dead name is allocated.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_NO_SPACE           No room for an entry in the space.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 */

kern_return_t
ipc_object_alloc_dead(
        ipc_space_t             space,
        mach_port_name_t        *namep)
{
        ipc_entry_t entry;
        kern_return_t kr;

        kr = ipc_entry_alloc(space, namep, &entry);
        if (kr != KERN_SUCCESS) {
                return kr;
        }
        /* space is write-locked */

        /* null object, MACH_PORT_TYPE_DEAD_NAME, 1 uref */

        assert(entry->ie_object == IO_NULL);
        entry->ie_bits |= MACH_PORT_TYPE_DEAD_NAME | 1;
        ipc_entry_modified(space, *namep, entry);
        is_write_unlock(space);
        return KERN_SUCCESS;
}

/*
 *      Routine:        ipc_object_alloc_dead_name
 *      Purpose:
 *              Allocate a dead-name entry, with a specific name.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            The dead name is allocated.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_NAME_EXISTS        The name already denotes a right.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 */

kern_return_t
ipc_object_alloc_dead_name(
        ipc_space_t             space,
        mach_port_name_t        name)
{
        ipc_entry_t entry;
        kern_return_t kr;

        kr = ipc_entry_alloc_name(space, name, &entry);
        if (kr != KERN_SUCCESS) {
                return kr;
        }
        /* space is write-locked */

        if (ipc_right_inuse(space, name, entry)) {
                return KERN_NAME_EXISTS;
        }

        /* null object, MACH_PORT_TYPE_DEAD_NAME, 1 uref */

        assert(entry->ie_object == IO_NULL);
        entry->ie_bits |= MACH_PORT_TYPE_DEAD_NAME | 1;
        ipc_entry_modified(space, name, entry);
        is_write_unlock(space);
        return KERN_SUCCESS;
}

/*
 *      Routine:        ipc_object_alloc
 *      Purpose:
 *              Allocate an object.
 *      Conditions:
 *              Nothing locked.  If successful, the object is returned locked.
 *              The space is write locked on successful return.
 *              The caller doesn't get a reference for the object.
 *      Returns:
 *              KERN_SUCCESS            The object is allocated.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_NO_SPACE           No room for an entry in the space.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 */

kern_return_t
ipc_object_alloc(
        ipc_space_t             space,
        ipc_object_type_t       otype,
        mach_port_type_t        type,
        mach_port_urefs_t       urefs,
        mach_port_name_t        *namep,
        ipc_object_t            *objectp)
{
        ipc_object_t object;
        ipc_entry_t entry;
        kern_return_t kr;

        assert(otype < IOT_NUMBER);
        assert((type & MACH_PORT_TYPE_ALL_RIGHTS) == type);
        assert(type != MACH_PORT_TYPE_NONE);
        assert(urefs <= MACH_PORT_UREFS_MAX);

        object = io_alloc(otype);
        if (object == IO_NULL) {
                return KERN_RESOURCE_SHORTAGE;
        }

        if (otype == IOT_PORT) {
                ipc_port_t port = (ipc_port_t)object;

                bzero((char *)port, sizeof(*port));
        } else if (otype == IOT_PORT_SET) {
                ipc_pset_t pset = (ipc_pset_t)object;

                bzero((char *)pset, sizeof(*pset));
        }

        io_lock_init(object);
        *namep = CAST_MACH_PORT_TO_NAME(object);
        kr = ipc_entry_alloc(space, namep, &entry);
        if (kr != KERN_SUCCESS) {
                io_free(otype, object);
                return kr;
        }
        /* space is write-locked */

        entry->ie_bits |= type | urefs;
        entry->ie_object = object;
        ipc_entry_modified(space, *namep, entry);

        io_lock(object);

        object->io_references = 1; /* for entry, not caller */
        object->io_bits = io_makebits(TRUE, otype, 0);

        *objectp = object;
        return KERN_SUCCESS;
}

/*
 *      Routine:        ipc_object_alloc_name
 *      Purpose:
 *              Allocate an object, with a specific name.
 *      Conditions:
 *              Nothing locked.  If successful, the object is returned locked.
 *              The caller doesn't get a reference for the object.
 *      Returns:
 *              KERN_SUCCESS            The object is allocated.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_NAME_EXISTS        The name already denotes a right.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 */

kern_return_t
ipc_object_alloc_name(
        ipc_space_t             space,
        ipc_object_type_t       otype,
        mach_port_type_t        type,
        mach_port_urefs_t       urefs,
        mach_port_name_t        name,
        ipc_object_t            *objectp)
{
        ipc_object_t object;
        ipc_entry_t entry;
        kern_return_t kr;

        assert(otype < IOT_NUMBER);
        assert((type & MACH_PORT_TYPE_ALL_RIGHTS) == type);
        assert(type != MACH_PORT_TYPE_NONE);
        assert(urefs <= MACH_PORT_UREFS_MAX);

        object = io_alloc(otype);
        if (object == IO_NULL) {
                return KERN_RESOURCE_SHORTAGE;
        }

        if (otype == IOT_PORT) {
                ipc_port_t port = (ipc_port_t)object;

                bzero((char *)port, sizeof(*port));
        } else if (otype == IOT_PORT_SET) {
                ipc_pset_t pset = (ipc_pset_t)object;

                bzero((char *)pset, sizeof(*pset));
        }

        io_lock_init(object);
        kr = ipc_entry_alloc_name(space, name, &entry);
        if (kr != KERN_SUCCESS) {
                io_free(otype, object);
                return kr;
        }
        /* space is write-locked */

        if (ipc_right_inuse(space, name, entry)) {
                io_free(otype, object);
                return KERN_NAME_EXISTS;
        }

        entry->ie_bits |= type | urefs;
        entry->ie_object = object;
        ipc_entry_modified(space, name, entry);

        io_lock(object);
        is_write_unlock(space);

        object->io_references = 1; /* for entry, not caller */
        object->io_bits = io_makebits(TRUE, otype, 0);

        *objectp = object;
        return KERN_SUCCESS;
}

/*
 *      Routine:        ipc_object_copyin_type
 *      Purpose:
 *              Convert a send type name to a received type name.
 */

mach_msg_type_name_t
ipc_object_copyin_type(
        mach_msg_type_name_t    msgt_name)
{
        switch (msgt_name) {
        case MACH_MSG_TYPE_MOVE_RECEIVE:
                return MACH_MSG_TYPE_PORT_RECEIVE;

        case MACH_MSG_TYPE_MOVE_SEND_ONCE:
        case MACH_MSG_TYPE_MAKE_SEND_ONCE:
                return MACH_MSG_TYPE_PORT_SEND_ONCE;

        case MACH_MSG_TYPE_MOVE_SEND:
        case MACH_MSG_TYPE_MAKE_SEND:
        case MACH_MSG_TYPE_COPY_SEND:
                return MACH_MSG_TYPE_PORT_SEND;

        case MACH_MSG_TYPE_DISPOSE_RECEIVE:
        case MACH_MSG_TYPE_DISPOSE_SEND:
        case MACH_MSG_TYPE_DISPOSE_SEND_ONCE:
        /* fall thru */
        default:
                return MACH_MSG_TYPE_PORT_NONE;
        }
}

/*
 *      Routine:        ipc_object_copyin
 *      Purpose:
 *              Copyin a capability from a space.
 *              If successful, the caller gets a ref
 *              for the resulting object, unless it is IO_DEAD.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Acquired an object, possibly IO_DEAD.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       Name doesn't exist in space.
 *              KERN_INVALID_RIGHT      Name doesn't denote correct right.
 */

kern_return_t
ipc_object_copyin(
        ipc_space_t             space,
        mach_port_name_t        name,
        mach_msg_type_name_t    msgt_name,
        ipc_object_t            *objectp)
{
        ipc_entry_t entry;
        ipc_port_t soright;
        ipc_port_t release_port;
        kern_return_t kr;
        int assertcnt = 0;

        /*
         *      Could first try a read lock when doing
         *      MACH_MSG_TYPE_COPY_SEND, MACH_MSG_TYPE_MAKE_SEND,
         *      and MACH_MSG_TYPE_MAKE_SEND_ONCE.
         */

        kr = ipc_right_lookup_write(space, name, &entry);
        if (kr != KERN_SUCCESS) {
                return kr;
        }
        /* space is write-locked and active */

        release_port = IP_NULL;
        kr = ipc_right_copyin(space, name, entry,
            msgt_name, IPC_RIGHT_COPYIN_FLAGS_DEADOK,
            objectp, &soright,
            &release_port,
            &assertcnt);
        if (IE_BITS_TYPE(entry->ie_bits) == MACH_PORT_TYPE_NONE) {
                ipc_entry_dealloc(space, name, entry);
        }
        is_write_unlock(space);

#if IMPORTANCE_INHERITANCE
        if (0 < assertcnt && ipc_importance_task_is_any_receiver_type(current_task()->task_imp_base)) {
                ipc_importance_task_drop_internal_assertion(current_task()->task_imp_base, assertcnt);
        }
#endif /* IMPORTANCE_INHERITANCE */

        if (release_port != IP_NULL) {
                ip_release(release_port);
        }

        if ((kr == KERN_SUCCESS) && (soright != IP_NULL)) {
                ipc_notify_port_deleted(soright, name);
        }

        return kr;
}

/*
 *      Routine:        ipc_object_copyin_from_kernel
 *      Purpose:
 *              Copyin a naked capability from the kernel.
 *
 *              MACH_MSG_TYPE_MOVE_RECEIVE
 *                      The receiver must be ipc_space_kernel
 *                      or the receive right must already be in limbo.
 *                      Consumes the naked receive right.
 *              MACH_MSG_TYPE_COPY_SEND
 *                      A naked send right must be supplied.
 *                      The port gains a reference, and a send right
 *                      if the port is still active.
 *              MACH_MSG_TYPE_MAKE_SEND
 *                      The receiver must be ipc_space_kernel.
 *                      The port gains a reference and a send right.
 *              MACH_MSG_TYPE_MOVE_SEND
 *                      Consumes a naked send right.
 *              MACH_MSG_TYPE_MAKE_SEND_ONCE
 *                      The port gains a reference and a send-once right.
 *                      Receiver also be the caller of device subsystem,
 *                      so no assertion.
 *              MACH_MSG_TYPE_MOVE_SEND_ONCE
 *                      Consumes a naked send-once right.
 *      Conditions:
 *              Nothing locked.
 */

void
ipc_object_copyin_from_kernel(
        ipc_object_t            object,
        mach_msg_type_name_t    msgt_name)
{
        assert(IO_VALID(object));

        switch (msgt_name) {
        case MACH_MSG_TYPE_MOVE_RECEIVE: {
                ipc_port_t port = (ipc_port_t) object;

                ip_lock(port);
                imq_lock(&port->ip_messages);
                assert(ip_active(port));
                if (port->ip_destination != IP_NULL) {
                        assert(port->ip_receiver == ipc_space_kernel);

                        /* relevant part of ipc_port_clear_receiver */
                        ipc_port_set_mscount(port, 0);

                        port->ip_receiver_name = MACH_PORT_NULL;
                        port->ip_destination = IP_NULL;
                }
                imq_unlock(&port->ip_messages);
                ip_unlock(port);
                break;
        }

        case MACH_MSG_TYPE_COPY_SEND: {
                ipc_port_t port = (ipc_port_t) object;

                ip_lock(port);
                if (ip_active(port)) {
                        assert(port->ip_srights > 0);
                        port->ip_srights++;
                }
                ip_reference(port);
                ip_unlock(port);
                break;
        }

        case MACH_MSG_TYPE_MAKE_SEND: {
                ipc_port_t port = (ipc_port_t) object;

                ip_lock(port);
                if (ip_active(port)) {
                        assert(port->ip_receiver_name != MACH_PORT_NULL);
                        assert((port->ip_receiver == ipc_space_kernel) ||
                            (port->ip_receiver->is_node_id != HOST_LOCAL_NODE));
                        port->ip_mscount++;
                }

                port->ip_srights++;
                ip_reference(port);
                ip_unlock(port);
                break;
        }

        case MACH_MSG_TYPE_MOVE_SEND: {
                /* move naked send right into the message */
                assert(((ipc_port_t)object)->ip_srights);
                break;
        }

        case MACH_MSG_TYPE_MAKE_SEND_ONCE: {
                ipc_port_t port = (ipc_port_t) object;

                ip_lock(port);
                if (ip_active(port)) {
                        assert(port->ip_receiver_name != MACH_PORT_NULL);
                }
                port->ip_sorights++;
                ip_reference(port);
                ip_unlock(port);
                break;
        }

        case MACH_MSG_TYPE_MOVE_SEND_ONCE: {
                /* move naked send-once right into the message */
                assert(((ipc_port_t)object)->ip_sorights);
                break;
        }

        default:
                panic("ipc_object_copyin_from_kernel: strange rights");
        }
}

/*
 *      Routine:        ipc_object_destroy
 *      Purpose:
 *              Destroys a naked capability.
 *              Consumes a ref for the object.
 *
 *              A receive right should be in limbo or in transit.
 *      Conditions:
 *              Nothing locked.
 */

void
ipc_object_destroy(
        ipc_object_t            object,
        mach_msg_type_name_t    msgt_name)
{
        assert(IO_VALID(object));
        assert(io_otype(object) == IOT_PORT);

        switch (msgt_name) {
        case MACH_MSG_TYPE_PORT_SEND:
                ipc_port_release_send((ipc_port_t) object);
                break;

        case MACH_MSG_TYPE_PORT_SEND_ONCE:
                ipc_notify_send_once((ipc_port_t) object);
                break;

        case MACH_MSG_TYPE_PORT_RECEIVE:
                ipc_port_release_receive((ipc_port_t) object);
                break;

        default:
                panic("ipc_object_destroy: strange rights");
        }
}

/*
 *      Routine:        ipc_object_destroy_dest
 *      Purpose:
 *              Destroys a naked capability for the destination of
 *              of a message. Consumes a ref for the object.
 *
 *      Conditions:
 *              Nothing locked.
 */

void
ipc_object_destroy_dest(
        ipc_object_t            object,
        mach_msg_type_name_t    msgt_name)
{
        assert(IO_VALID(object));
        assert(io_otype(object) == IOT_PORT);

        switch (msgt_name) {
        case MACH_MSG_TYPE_PORT_SEND:
                ipc_port_release_send((ipc_port_t) object);
                break;

        case MACH_MSG_TYPE_PORT_SEND_ONCE:
                if (io_active(object) &&
                    !ip_full_kernel((ipc_port_t) object)) {
                        ipc_notify_send_once((ipc_port_t) object);
                } else {
                        ipc_port_release_sonce((ipc_port_t) object);
                }
                break;

        default:
                panic("ipc_object_destroy_dest: strange rights");
        }
}

/*
 *      Routine:        ipc_object_copyout
 *      Purpose:
 *              Copyout a capability, placing it into a space.
 *              If successful, consumes a ref for the object.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Copied out object, consumed ref.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_CAPABILITY The object is dead.
 *              KERN_NO_SPACE           No room in space for another right.
 *              KERN_RESOURCE_SHORTAGE  No memory available.
 *              KERN_UREFS_OVERFLOW     Urefs limit exceeded
 *                      and overflow wasn't specified.
 */

kern_return_t
ipc_object_copyout(
        ipc_space_t             space,
        ipc_object_t            object,
        mach_msg_type_name_t    msgt_name,
        boolean_t               overflow,
        mach_port_name_t        *namep)
{
        struct knote *kn = current_thread()->ith_knote;
        mach_port_name_t name;
        ipc_entry_t entry;
        kern_return_t kr;

        assert(IO_VALID(object));
        assert(io_otype(object) == IOT_PORT);

        if (ITH_KNOTE_VALID(kn, msgt_name)) {
                filt_machport_turnstile_prepare_lazily(kn,
                    msgt_name, (ipc_port_t)object);
        }

        is_write_lock(space);

        for (;;) {
                if (!is_active(space)) {
                        is_write_unlock(space);
                        return KERN_INVALID_TASK;
                }

                if ((msgt_name != MACH_MSG_TYPE_PORT_SEND_ONCE) &&
                    ipc_right_reverse(space, object, &name, &entry)) {
                        /* object is locked and active */

                        assert(entry->ie_bits & MACH_PORT_TYPE_SEND_RECEIVE);
                        break;
                }

                name = CAST_MACH_PORT_TO_NAME(object);
                kr = ipc_entry_get(space, &name, &entry);
                if (kr != KERN_SUCCESS) {
                        /* unlocks/locks space, so must start again */

                        kr = ipc_entry_grow_table(space, ITS_SIZE_NONE);
                        if (kr != KERN_SUCCESS) {
                                return kr; /* space is unlocked */
                        }
                        continue;
                }

                assert(IE_BITS_TYPE(entry->ie_bits) == MACH_PORT_TYPE_NONE);
                assert(entry->ie_object == IO_NULL);

                io_lock(object);
                if (!io_active(object)) {
                        io_unlock(object);
                        ipc_entry_dealloc(space, name, entry);
                        is_write_unlock(space);
                        return KERN_INVALID_CAPABILITY;
                }

                entry->ie_object = object;
                break;
        }

        /* space is write-locked and active, object is locked and active */

        kr = ipc_right_copyout(space, name, entry,
            msgt_name, overflow, object);

        /* object is unlocked */
        is_write_unlock(space);

        if (kr == KERN_SUCCESS) {
                *namep = name;
        }
        return kr;
}

/*
 *      Routine:        ipc_object_copyout_name
 *      Purpose:
 *              Copyout a capability, placing it into a space.
 *              The specified name is used for the capability.
 *              If successful, consumes a ref for the object.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Copied out object, consumed ref.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_CAPABILITY The object is dead.
 *              KERN_RESOURCE_SHORTAGE  No memory available.
 *              KERN_UREFS_OVERFLOW     Urefs limit exceeded
 *                      and overflow wasn't specified.
 *              KERN_RIGHT_EXISTS       Space has rights under another name.
 *              KERN_NAME_EXISTS        Name is already used.
 */

kern_return_t
ipc_object_copyout_name(
        ipc_space_t             space,
        ipc_object_t            object,
        mach_msg_type_name_t    msgt_name,
        boolean_t               overflow,
        mach_port_name_t        name)
{
        mach_port_name_t oname;
        ipc_entry_t oentry;
        ipc_entry_t entry;
        kern_return_t kr;
        struct knote *kn = current_thread()->ith_knote;

#if IMPORTANCE_INHERITANCE
        int assertcnt = 0;
        ipc_importance_task_t task_imp = IIT_NULL;
#endif /* IMPORTANCE_INHERITANCE */

        assert(IO_VALID(object));
        assert(io_otype(object) == IOT_PORT);

        if (ITH_KNOTE_VALID(kn, msgt_name)) {
                filt_machport_turnstile_prepare_lazily(kn,
                    msgt_name, (ipc_port_t)object);
        }

        kr = ipc_entry_alloc_name(space, name, &entry);
        if (kr != KERN_SUCCESS) {
                return kr;
        }
        /* space is write-locked and active */

        if ((msgt_name != MACH_MSG_TYPE_PORT_SEND_ONCE) &&
            ipc_right_reverse(space, object, &oname, &oentry)) {
                /* object is locked and active */

                if (name != oname) {
                        io_unlock(object);

                        if (IE_BITS_TYPE(entry->ie_bits) == MACH_PORT_TYPE_NONE) {
                                ipc_entry_dealloc(space, name, entry);
                        }

                        is_write_unlock(space);
                        return KERN_RIGHT_EXISTS;
                }

                assert(entry == oentry);
                assert(entry->ie_bits & MACH_PORT_TYPE_SEND_RECEIVE);
        } else {
                if (ipc_right_inuse(space, name, entry)) {
                        return KERN_NAME_EXISTS;
                }

                assert(IE_BITS_TYPE(entry->ie_bits) == MACH_PORT_TYPE_NONE);
                assert(entry->ie_object == IO_NULL);

                io_lock(object);
                if (!io_active(object)) {
                        io_unlock(object);
                        ipc_entry_dealloc(space, name, entry);
                        is_write_unlock(space);
                        return KERN_INVALID_CAPABILITY;
                }

                entry->ie_object = object;
        }

        /* space is write-locked and active, object is locked and active */

#if IMPORTANCE_INHERITANCE
        /*
         * We are slamming a receive right into the space, without
         * first having been enqueued on a port destined there.  So,
         * we have to arrange to boost the task appropriately if this
         * port has assertions (and the task wants them).
         */
        if (msgt_name == MACH_MSG_TYPE_PORT_RECEIVE) {
                ipc_port_t port = (ipc_port_t)object;

                if (space->is_task != TASK_NULL) {
                        task_imp = space->is_task->task_imp_base;
                        if (ipc_importance_task_is_any_receiver_type(task_imp)) {
                                assertcnt = port->ip_impcount;
                                ipc_importance_task_reference(task_imp);
                        } else {
                                task_imp = IIT_NULL;
                        }
                }

                /* take port out of limbo */
                assert(port->ip_tempowner != 0);
                port->ip_tempowner = 0;
        }

#endif /* IMPORTANCE_INHERITANCE */

        kr = ipc_right_copyout(space, name, entry,
            msgt_name, overflow, object);

        /* object is unlocked */
        is_write_unlock(space);

#if IMPORTANCE_INHERITANCE
        /*
         * Add the assertions to the task that we captured before
         */
        if (task_imp != IIT_NULL) {
                ipc_importance_task_hold_internal_assertion(task_imp, assertcnt);
                ipc_importance_task_release(task_imp);
        }
#endif /* IMPORTANCE_INHERITANCE */

        return kr;
}

/*
 *      Routine:        ipc_object_copyout_dest
 *      Purpose:
 *              Translates/consumes the destination right of a message.
 *              This is unlike normal copyout because the right is consumed
 *              in a funny way instead of being given to the receiving space.
 *              The receiver gets his name for the port, if he has receive
 *              rights, otherwise MACH_PORT_NULL.
 *      Conditions:
 *              The object is locked and active.  Nothing else locked.
 *              The object is unlocked and loses a reference.
 */

void
ipc_object_copyout_dest(
        ipc_space_t             space,
        ipc_object_t            object,
        mach_msg_type_name_t    msgt_name,
        mach_port_name_t        *namep)
{
        mach_port_name_t name;

        assert(IO_VALID(object));
        assert(io_active(object));

        io_release(object);

        /*
         *      If the space is the receiver/owner of the object,
         *      then we quietly consume the right and return
         *      the space's name for the object.  Otherwise
         *      we destroy the right and return MACH_PORT_NULL.
         */

        switch (msgt_name) {
        case MACH_MSG_TYPE_PORT_SEND: {
                ipc_port_t port = (ipc_port_t) object;
                ipc_port_t nsrequest = IP_NULL;
                mach_port_mscount_t mscount;

                if (port->ip_receiver == space) {
                        name = port->ip_receiver_name;
                } else {
                        name = MACH_PORT_NULL;
                }

                assert(port->ip_srights > 0);
                if (--port->ip_srights == 0 &&
                    port->ip_nsrequest != IP_NULL) {
                        nsrequest = port->ip_nsrequest;
                        port->ip_nsrequest = IP_NULL;
                        mscount = port->ip_mscount;
                        ip_unlock(port);
                        ipc_notify_no_senders(nsrequest, mscount);
                } else {
                        ip_unlock(port);
                }
                break;
        }

        case MACH_MSG_TYPE_PORT_SEND_ONCE: {
                ipc_port_t port = (ipc_port_t) object;

                assert(port->ip_sorights > 0);

                if (port->ip_receiver == space) {
                        /* quietly consume the send-once right */

                        port->ip_sorights--;
                        name = port->ip_receiver_name;
                        ip_unlock(port);
                } else {
                        /*
                         *      A very bizarre case.  The message
                         *      was received, but before this copyout
                         *      happened the space lost receive rights.
                         *      We can't quietly consume the soright
                         *      out from underneath some other task,
                         *      so generate a send-once notification.
                         */

                        ip_reference(port); /* restore ref */
                        ip_unlock(port);

                        ipc_notify_send_once(port);
                        name = MACH_PORT_NULL;
                }

                break;
        }

        default:
                panic("ipc_object_copyout_dest: strange rights");
                name = MACH_PORT_DEAD;
        }

        *namep = name;
}

/*
 *      Routine:        ipc_object_rename
 *      Purpose:
 *              Rename an entry in a space.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Renamed the entry.
 *              KERN_INVALID_TASK       The space was dead.
 *              KERN_INVALID_NAME       oname didn't denote an entry.
 *              KERN_NAME_EXISTS        nname already denoted an entry.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate new entry.
 */

kern_return_t
ipc_object_rename(
        ipc_space_t             space,
        mach_port_name_t        oname,
        mach_port_name_t        nname)
{
        ipc_entry_t oentry, nentry;
        kern_return_t kr;

        kr = ipc_entry_alloc_name(space, nname, &nentry);
        if (kr != KERN_SUCCESS) {
                return kr;
        }

        /* space is write-locked and active */

        if (ipc_right_inuse(space, nname, nentry)) {
                /* space is unlocked */
                return KERN_NAME_EXISTS;
        }

        /* don't let ipc_entry_lookup see the uninitialized new entry */

        if ((oname == nname) ||
            ((oentry = ipc_entry_lookup(space, oname)) == IE_NULL)) {
                ipc_entry_dealloc(space, nname, nentry);
                is_write_unlock(space);
                return KERN_INVALID_NAME;
        }

        kr = ipc_right_rename(space, oname, oentry, nname, nentry);
        /* space is unlocked */
        return kr;
}

/*
 *      Check whether the object is a port if so, free it.  But
 *      keep track of that fact.
 */
void
io_free(
        unsigned int    otype,
        ipc_object_t    object)
{
        ipc_port_t      port;

        if (otype == IOT_PORT) {
                port = (ipc_port_t) object;
                ipc_port_finalize(port);
        }
        io_lock_destroy(object);
        zfree(ipc_object_zones[otype], object);
}