xnu-3248.40.184.tar.gz

[apple/xnu.git] / osfmk / kern / ipc_tt.c

/*
 * Copyright (c) 2000-2010 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@
 */
/*
 * @OSF_COPYRIGHT@
 */
/* 
 * Mach Operating System
 * Copyright (c) 1991,1990,1989,1988,1987 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.
 */
/*
 */

/*
 * File:        ipc_tt.c
 * Purpose:
 *      Task and thread related IPC functions.
 */

#include <mach/mach_types.h>
#include <mach/boolean.h>
#include <mach/kern_return.h>
#include <mach/mach_param.h>
#include <mach/task_special_ports.h>
#include <mach/thread_special_ports.h>
#include <mach/thread_status.h>
#include <mach/exception_types.h>
#include <mach/memory_object_types.h>
#include <mach/mach_traps.h>
#include <mach/task_server.h>
#include <mach/thread_act_server.h>
#include <mach/mach_host_server.h>
#include <mach/host_priv_server.h>
#include <mach/vm_map_server.h>

#include <kern/kern_types.h>
#include <kern/host.h>
#include <kern/ipc_kobject.h>
#include <kern/ipc_tt.h>
#include <kern/kalloc.h>
#include <kern/thread.h>
#include <kern/misc_protos.h>

#include <vm/vm_map.h>
#include <vm/vm_pageout.h>
#include <vm/vm_protos.h>

#include <security/mac_mach_internal.h>

/* forward declarations */
task_t convert_port_to_locked_task(ipc_port_t port);


/*
 *      Routine:        ipc_task_init
 *      Purpose:
 *              Initialize a task's IPC state.
 *
 *              If non-null, some state will be inherited from the parent.
 *              The parent must be appropriately initialized.
 *      Conditions:
 *              Nothing locked.
 */

void
ipc_task_init(
        task_t          task,
        task_t          parent)
{
        ipc_space_t space;
        ipc_port_t kport;
        ipc_port_t nport;
        kern_return_t kr;
        int i;


        kr = ipc_space_create(&ipc_table_entries[0], &space);
        if (kr != KERN_SUCCESS)
                panic("ipc_task_init");

        space->is_task = task;

        kport = ipc_port_alloc_kernel();
        if (kport == IP_NULL)
                panic("ipc_task_init");

        nport = ipc_port_alloc_kernel();
        if (nport == IP_NULL)
                panic("ipc_task_init");

        itk_lock_init(task);
        task->itk_self = kport;
        task->itk_nself = nport;
        task->itk_resume = IP_NULL; /* Lazily allocated on-demand */
        task->itk_sself = ipc_port_make_send(kport);
        task->itk_debug_control = IP_NULL;
        task->itk_space = space;

        if (parent == TASK_NULL) {
                ipc_port_t port;

                for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                        task->exc_actions[i].port = IP_NULL;
                }/* for */
                
                kr = host_get_host_port(host_priv_self(), &port);
                assert(kr == KERN_SUCCESS);
                task->itk_host = port;

                task->itk_bootstrap = IP_NULL;
                task->itk_seatbelt = IP_NULL;
                task->itk_gssd = IP_NULL;
                task->itk_task_access = IP_NULL;

                for (i = 0; i < TASK_PORT_REGISTER_MAX; i++)
                        task->itk_registered[i] = IP_NULL;
        } else {
                itk_lock(parent);
                assert(parent->itk_self != IP_NULL);

                /* inherit registered ports */

                for (i = 0; i < TASK_PORT_REGISTER_MAX; i++)
                        task->itk_registered[i] =
                                ipc_port_copy_send(parent->itk_registered[i]);

                /* inherit exception and bootstrap ports */

                for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                    task->exc_actions[i].port =
                                ipc_port_copy_send(parent->exc_actions[i].port);
                    task->exc_actions[i].flavor =
                                parent->exc_actions[i].flavor;
                    task->exc_actions[i].behavior = 
                                parent->exc_actions[i].behavior;
                    task->exc_actions[i].privileged =
                                parent->exc_actions[i].privileged;
                }/* for */
                task->itk_host =
                        ipc_port_copy_send(parent->itk_host);

                task->itk_bootstrap =
                        ipc_port_copy_send(parent->itk_bootstrap);

                task->itk_seatbelt =
                        ipc_port_copy_send(parent->itk_seatbelt);

                task->itk_gssd =
                        ipc_port_copy_send(parent->itk_gssd);

                task->itk_task_access =
                        ipc_port_copy_send(parent->itk_task_access);

                itk_unlock(parent);
        }
}

/*
 *      Routine:        ipc_task_enable
 *      Purpose:
 *              Enable a task for IPC access.
 *      Conditions:
 *              Nothing locked.
 */

void
ipc_task_enable(
        task_t          task)
{
        ipc_port_t kport;
        ipc_port_t nport;

        itk_lock(task);
        kport = task->itk_self;
        if (kport != IP_NULL)
                ipc_kobject_set(kport, (ipc_kobject_t) task, IKOT_TASK);
        nport = task->itk_nself;
        if (nport != IP_NULL)
                ipc_kobject_set(nport, (ipc_kobject_t) task, IKOT_TASK_NAME);
        itk_unlock(task);
}

/*
 *      Routine:        ipc_task_disable
 *      Purpose:
 *              Disable IPC access to a task.
 *      Conditions:
 *              Nothing locked.
 */

void
ipc_task_disable(
        task_t          task)
{
        ipc_port_t kport;
        ipc_port_t nport;
        ipc_port_t rport;

        itk_lock(task);
        kport = task->itk_self;
        if (kport != IP_NULL)
                ipc_kobject_set(kport, IKO_NULL, IKOT_NONE);
        nport = task->itk_nself;
        if (nport != IP_NULL)
                ipc_kobject_set(nport, IKO_NULL, IKOT_NONE);

        rport = task->itk_resume;
        if (rport != IP_NULL) {
                /*
                 * From this point onwards this task is no longer accepting
                 * resumptions.
                 *
                 * There are still outstanding suspensions on this task,
                 * even as it is being torn down. Disconnect the task
                 * from the rport, thereby "orphaning" the rport. The rport 
                 * itself will go away only when the last suspension holder
                 * destroys his SO right to it -- when he either
                 * exits, or tries to actually use that last SO right to
                 * resume this (now non-existent) task.
                 */
                ipc_kobject_set(rport, IKO_NULL, IKOT_NONE);
        }
        itk_unlock(task);
}

/*
 *      Routine:        ipc_task_terminate
 *      Purpose:
 *              Clean up and destroy a task's IPC state.
 *      Conditions:
 *              Nothing locked.  The task must be suspended.
 *              (Or the current thread must be in the task.)
 */

void
ipc_task_terminate(
        task_t          task)
{
        ipc_port_t kport;
        ipc_port_t nport;
        ipc_port_t rport;       
        int i;

        itk_lock(task);
        kport = task->itk_self;

        if (kport == IP_NULL) {
                /* the task is already terminated (can this happen?) */
                itk_unlock(task);
                return;
        }
        task->itk_self = IP_NULL;

        nport = task->itk_nself;
        assert(nport != IP_NULL);
        task->itk_nself = IP_NULL;

        rport = task->itk_resume;
        task->itk_resume = IP_NULL;

        itk_unlock(task);

        /* release the naked send rights */

        if (IP_VALID(task->itk_sself))
                ipc_port_release_send(task->itk_sself);

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                if (IP_VALID(task->exc_actions[i].port)) {
                        ipc_port_release_send(task->exc_actions[i].port);
                }
        }

        if (IP_VALID(task->itk_host))
                ipc_port_release_send(task->itk_host);

        if (IP_VALID(task->itk_bootstrap))
                ipc_port_release_send(task->itk_bootstrap);

        if (IP_VALID(task->itk_seatbelt))
                ipc_port_release_send(task->itk_seatbelt);
        
        if (IP_VALID(task->itk_gssd))
                ipc_port_release_send(task->itk_gssd);

        if (IP_VALID(task->itk_task_access))
                ipc_port_release_send(task->itk_task_access);

        if (IP_VALID(task->itk_debug_control))
                ipc_port_release_send(task->itk_debug_control);

        for (i = 0; i < TASK_PORT_REGISTER_MAX; i++)
                if (IP_VALID(task->itk_registered[i]))
                        ipc_port_release_send(task->itk_registered[i]);

        /* destroy the kernel ports */
        ipc_port_dealloc_kernel(kport);
        ipc_port_dealloc_kernel(nport);
        if (rport != IP_NULL)
                ipc_port_dealloc_kernel(rport); 

        itk_lock_destroy(task);
}

/*
 *      Routine:        ipc_task_reset
 *      Purpose:
 *              Reset a task's IPC state to protect it when
 *              it enters an elevated security context. The
 *              task name port can remain the same - since
 *              it represents no specific privilege.
 *      Conditions:
 *              Nothing locked.  The task must be suspended.
 *              (Or the current thread must be in the task.)
 */

void
ipc_task_reset(
        task_t          task)
{
        ipc_port_t old_kport, new_kport;
        ipc_port_t old_sself;
        ipc_port_t old_exc_actions[EXC_TYPES_COUNT];
        int i;

        new_kport = ipc_port_alloc_kernel();
        if (new_kport == IP_NULL)
                panic("ipc_task_reset");

        itk_lock(task);

        old_kport = task->itk_self;

        if (old_kport == IP_NULL) {
                /* the task is already terminated (can this happen?) */
                itk_unlock(task);
                ipc_port_dealloc_kernel(new_kport);
                return;
        }

        task->itk_self = new_kport;
        old_sself = task->itk_sself;
        task->itk_sself = ipc_port_make_send(new_kport);
        ipc_kobject_set(old_kport, IKO_NULL, IKOT_NONE);
        ipc_kobject_set(new_kport, (ipc_kobject_t) task, IKOT_TASK);

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                old_exc_actions[i] = IP_NULL;

                if (i == EXC_CORPSE_NOTIFY && task_corpse_pending_report(task)) {
                        continue;
                }

                if (!task->exc_actions[i].privileged) {
                        old_exc_actions[i] = task->exc_actions[i].port;
                        task->exc_actions[i].port = IP_NULL;
                }
        }/* for */
        
        if (IP_VALID(task->itk_debug_control)) {
                ipc_port_release_send(task->itk_debug_control);
        }
        task->itk_debug_control = IP_NULL;
        
        itk_unlock(task);

        /* release the naked send rights */

        if (IP_VALID(old_sself))
                ipc_port_release_send(old_sself);

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                if (IP_VALID(old_exc_actions[i])) {
                        ipc_port_release_send(old_exc_actions[i]);
                }
        }/* for */

        /* destroy the kernel port */
        ipc_port_dealloc_kernel(old_kport);
}

/*
 *      Routine:        ipc_thread_init
 *      Purpose:
 *              Initialize a thread's IPC state.
 *      Conditions:
 *              Nothing locked.
 */

void
ipc_thread_init(
        thread_t        thread)
{
        ipc_port_t      kport;

        kport = ipc_port_alloc_kernel();
        if (kport == IP_NULL)
                panic("ipc_thread_init");

        thread->ith_self = kport;
        thread->ith_sself = ipc_port_make_send(kport);
        thread->exc_actions = NULL;

        ipc_kobject_set(kport, (ipc_kobject_t)thread, IKOT_THREAD);

#if IMPORTANCE_INHERITANCE
        thread->ith_assertions = 0;
#endif

        ipc_kmsg_queue_init(&thread->ith_messages);

        thread->ith_rpc_reply = IP_NULL;
}

void
ipc_thread_init_exc_actions(
        thread_t        thread)
{
        assert(thread->exc_actions == NULL);

        thread->exc_actions = kalloc(sizeof(struct exception_action) * EXC_TYPES_COUNT);
        bzero(thread->exc_actions, sizeof(struct exception_action) * EXC_TYPES_COUNT);
}

void
ipc_thread_destroy_exc_actions(
        thread_t        thread)
{
        if (thread->exc_actions != NULL) {
                kfree(thread->exc_actions, 
                      sizeof(struct exception_action) * EXC_TYPES_COUNT);
                thread->exc_actions = NULL;
        }
}

void
ipc_thread_disable(
        thread_t        thread)
{
        ipc_port_t      kport = thread->ith_self;

        if (kport != IP_NULL)
                ipc_kobject_set(kport, IKO_NULL, IKOT_NONE);
}

/*
 *      Routine:        ipc_thread_terminate
 *      Purpose:
 *              Clean up and destroy a thread's IPC state.
 *      Conditions:
 *              Nothing locked.
 */

void
ipc_thread_terminate(
        thread_t        thread)
{
        ipc_port_t      kport = thread->ith_self;

        if (kport != IP_NULL) {
                int                     i;

                if (IP_VALID(thread->ith_sself))
                        ipc_port_release_send(thread->ith_sself);

                thread->ith_sself = thread->ith_self = IP_NULL;

                if (thread->exc_actions != NULL) {
                        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; ++i) {
                                if (IP_VALID(thread->exc_actions[i].port))
                                        ipc_port_release_send(thread->exc_actions[i].port);
                        }
                        ipc_thread_destroy_exc_actions(thread);
                }

                ipc_port_dealloc_kernel(kport);
        }

#if IMPORTANCE_INHERITANCE
        assert(thread->ith_assertions == 0);
#endif

        assert(ipc_kmsg_queue_empty(&thread->ith_messages));

        if (thread->ith_rpc_reply != IP_NULL)
                ipc_port_dealloc_reply(thread->ith_rpc_reply);

        thread->ith_rpc_reply = IP_NULL;
}

/*
 *      Routine:        ipc_thread_reset
 *      Purpose:
 *              Reset the IPC state for a given Mach thread when
 *              its task enters an elevated security context.
 *              Both the thread port and its exception ports have
 *              to be reset.  Its RPC reply port cannot have any
 *              rights outstanding, so it should be fine.
 *      Conditions:
 *              Nothing locked.
 */

void
ipc_thread_reset(
        thread_t        thread)
{
        ipc_port_t old_kport, new_kport;
        ipc_port_t old_sself;
        ipc_port_t old_exc_actions[EXC_TYPES_COUNT];
        boolean_t  has_old_exc_actions = FALSE; 
        int                i;

        new_kport = ipc_port_alloc_kernel();
        if (new_kport == IP_NULL)
                panic("ipc_task_reset");

        thread_mtx_lock(thread);

        old_kport = thread->ith_self;

        if (old_kport == IP_NULL && thread->inspection == FALSE) {
                /* the  is already terminated (can this happen?) */
                thread_mtx_unlock(thread);
                ipc_port_dealloc_kernel(new_kport);
                return;
        }

        thread->ith_self = new_kport;
        old_sself = thread->ith_sself;
        thread->ith_sself = ipc_port_make_send(new_kport);
        if (old_kport != IP_NULL) {
                ipc_kobject_set(old_kport, IKO_NULL, IKOT_NONE);
        }
        ipc_kobject_set(new_kport, (ipc_kobject_t) thread, IKOT_THREAD);

        /*
         * Only ports that were set by root-owned processes
         * (privileged ports) should survive 
         */
        if (thread->exc_actions != NULL) {
                has_old_exc_actions = TRUE;
                for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                        if (thread->exc_actions[i].privileged) {
                                old_exc_actions[i] = IP_NULL;
                        } else {
                                old_exc_actions[i] = thread->exc_actions[i].port;
                                thread->exc_actions[i].port = IP_NULL;          
                        }
                }
        }

        thread_mtx_unlock(thread);

        /* release the naked send rights */

        if (IP_VALID(old_sself))
                ipc_port_release_send(old_sself);

        if (has_old_exc_actions) {
                for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                        ipc_port_release_send(old_exc_actions[i]);
                }
        }

        /* destroy the kernel port */
        if (old_kport != IP_NULL) {
                ipc_port_dealloc_kernel(old_kport);
        }
}

/*
 *      Routine:        retrieve_task_self_fast
 *      Purpose:
 *              Optimized version of retrieve_task_self,
 *              that only works for the current task.
 *
 *              Return a send right (possibly null/dead)
 *              for the task's user-visible self port.
 *      Conditions:
 *              Nothing locked.
 */

ipc_port_t
retrieve_task_self_fast(
        register task_t         task)
{
        register ipc_port_t port;

        assert(task == current_task());

        itk_lock(task);
        assert(task->itk_self != IP_NULL);

        if ((port = task->itk_sself) == task->itk_self) {
                /* no interposing */

                ip_lock(port);
                assert(ip_active(port));
                ip_reference(port);
                port->ip_srights++;
                ip_unlock(port);
        } else
                port = ipc_port_copy_send(port);
        itk_unlock(task);

        return port;
}

/*
 *      Routine:        retrieve_thread_self_fast
 *      Purpose:
 *              Return a send right (possibly null/dead)
 *              for the thread's user-visible self port.
 *
 *              Only works for the current thread.
 *
 *      Conditions:
 *              Nothing locked.
 */

ipc_port_t
retrieve_thread_self_fast(
        thread_t                thread)
{
        register ipc_port_t port;

        assert(thread == current_thread());

        thread_mtx_lock(thread);

        assert(thread->ith_self != IP_NULL);

        if ((port = thread->ith_sself) == thread->ith_self) {
                /* no interposing */

                ip_lock(port);
                assert(ip_active(port));
                ip_reference(port);
                port->ip_srights++;
                ip_unlock(port);
        }
        else
                port = ipc_port_copy_send(port);

        thread_mtx_unlock(thread);

        return port;
}

/*
 *      Routine:        task_self_trap [mach trap]
 *      Purpose:
 *              Give the caller send rights for his own task port.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              MACH_PORT_NULL if there are any resource failures
 *              or other errors.
 */

mach_port_name_t
task_self_trap(
        __unused struct task_self_trap_args *args)
{
        task_t task = current_task();
        ipc_port_t sright;
        mach_port_name_t name;

        sright = retrieve_task_self_fast(task);
        name = ipc_port_copyout_send(sright, task->itk_space);
        return name;
}

/*
 *      Routine:        thread_self_trap [mach trap]
 *      Purpose:
 *              Give the caller send rights for his own thread port.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              MACH_PORT_NULL if there are any resource failures
 *              or other errors.
 */

mach_port_name_t
thread_self_trap(
        __unused struct thread_self_trap_args *args)
{
        thread_t  thread = current_thread();
        task_t task = thread->task;
        ipc_port_t sright;
        mach_port_name_t name;

        sright = retrieve_thread_self_fast(thread);
        name = ipc_port_copyout_send(sright, task->itk_space);
        return name;

}

/*
 *      Routine:        mach_reply_port [mach trap]
 *      Purpose:
 *              Allocate a port for the caller.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              MACH_PORT_NULL if there are any resource failures
 *              or other errors.
 */

mach_port_name_t
mach_reply_port(
        __unused struct mach_reply_port_args *args)
{
        ipc_port_t port;
        mach_port_name_t name;
        kern_return_t kr;

        kr = ipc_port_alloc(current_task()->itk_space, &name, &port);
        if (kr == KERN_SUCCESS)
                ip_unlock(port);
        else
                name = MACH_PORT_NULL;
        return name;
}

/*
 *      Routine:        thread_get_special_port [kernel call]
 *      Purpose:
 *              Clones a send right for one of the thread's
 *              special ports.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Extracted a send right.
 *              KERN_INVALID_ARGUMENT   The thread is null.
 *              KERN_FAILURE            The thread is dead.
 *              KERN_INVALID_ARGUMENT   Invalid special port.
 */

kern_return_t
thread_get_special_port(
        thread_t                thread,
        int                             which,
        ipc_port_t              *portp)
{
        kern_return_t   result = KERN_SUCCESS;
        ipc_port_t              *whichp;

        if (thread == THREAD_NULL)
                return (KERN_INVALID_ARGUMENT);

        switch (which) {

        case THREAD_KERNEL_PORT:
                whichp = &thread->ith_sself;
                break;

        default:
                return (KERN_INVALID_ARGUMENT);
        }

        thread_mtx_lock(thread);

        if (thread->active)
                *portp = ipc_port_copy_send(*whichp);
        else
                result = KERN_FAILURE;

        thread_mtx_unlock(thread);

        return (result);
}

/*
 *      Routine:        thread_set_special_port [kernel call]
 *      Purpose:
 *              Changes one of the thread's special ports,
 *              setting it to the supplied send right.
 *      Conditions:
 *              Nothing locked.  If successful, consumes
 *              the supplied send right.
 *      Returns:
 *              KERN_SUCCESS            Changed the special port.
 *              KERN_INVALID_ARGUMENT   The thread is null.
 *              KERN_FAILURE            The thread is dead.
 *              KERN_INVALID_ARGUMENT   Invalid special port.
 */

kern_return_t
thread_set_special_port(
        thread_t                thread,
        int                     which,
        ipc_port_t      port)
{
        kern_return_t   result = KERN_SUCCESS;
        ipc_port_t              *whichp, old = IP_NULL;

        if (thread == THREAD_NULL)
                return (KERN_INVALID_ARGUMENT);

        switch (which) {

        case THREAD_KERNEL_PORT:
                whichp = &thread->ith_sself;
                break;

        default:
                return (KERN_INVALID_ARGUMENT);
        }

        thread_mtx_lock(thread);

        if (thread->active) {
                old = *whichp;
                *whichp = port;
        }
        else
                result = KERN_FAILURE;

        thread_mtx_unlock(thread);

        if (IP_VALID(old))
                ipc_port_release_send(old);

        return (result);
}

/*
 *      Routine:        task_get_special_port [kernel call]
 *      Purpose:
 *              Clones a send right for one of the task's
 *              special ports.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Extracted a send right.
 *              KERN_INVALID_ARGUMENT   The task is null.
 *              KERN_FAILURE            The task/space is dead.
 *              KERN_INVALID_ARGUMENT   Invalid special port.
 */

kern_return_t
task_get_special_port(
        task_t          task,
        int             which,
        ipc_port_t      *portp)
{
        ipc_port_t port;

        if (task == TASK_NULL)
                return KERN_INVALID_ARGUMENT;

        itk_lock(task);
        if (task->itk_self == IP_NULL) {
                itk_unlock(task);
                return KERN_FAILURE;
        }

        switch (which) {
            case TASK_KERNEL_PORT:
                port = ipc_port_copy_send(task->itk_sself);
                break;

            case TASK_NAME_PORT:
                port = ipc_port_make_send(task->itk_nself);
                break;

            case TASK_HOST_PORT:
                port = ipc_port_copy_send(task->itk_host);
                break;

            case TASK_BOOTSTRAP_PORT:
                port = ipc_port_copy_send(task->itk_bootstrap);
                break;

            case TASK_SEATBELT_PORT:
                port = ipc_port_copy_send(task->itk_seatbelt);
                break;

            case TASK_ACCESS_PORT:
                port = ipc_port_copy_send(task->itk_task_access);
                break;

                case TASK_DEBUG_CONTROL_PORT:
                port = ipc_port_copy_send(task->itk_debug_control);
                break;

            default:
               itk_unlock(task);
                return KERN_INVALID_ARGUMENT;
        }
        itk_unlock(task);

        *portp = port;
        return KERN_SUCCESS;
}

/*
 *      Routine:        task_set_special_port [kernel call]
 *      Purpose:
 *              Changes one of the task's special ports,
 *              setting it to the supplied send right.
 *      Conditions:
 *              Nothing locked.  If successful, consumes
 *              the supplied send right.
 *      Returns:
 *              KERN_SUCCESS            Changed the special port.
 *              KERN_INVALID_ARGUMENT   The task is null.
 *              KERN_FAILURE            The task/space is dead.
 *              KERN_INVALID_ARGUMENT   Invalid special port.
 *              KERN_NO_ACCESS          Attempted overwrite of seatbelt port.
 */

kern_return_t
task_set_special_port(
        task_t          task,
        int             which,
        ipc_port_t      port)
{
        ipc_port_t *whichp;
        ipc_port_t old;

        if (task == TASK_NULL)
                return KERN_INVALID_ARGUMENT;

        switch (which) {
            case TASK_KERNEL_PORT:
                whichp = &task->itk_sself;
                break;

            case TASK_HOST_PORT:
                whichp = &task->itk_host;
                break;

            case TASK_BOOTSTRAP_PORT:
                whichp = &task->itk_bootstrap;
                break;

            case TASK_SEATBELT_PORT:
                whichp = &task->itk_seatbelt;
                break;

            case TASK_ACCESS_PORT:
                whichp = &task->itk_task_access;
                break;
                
            case TASK_DEBUG_CONTROL_PORT: 
                whichp = &task->itk_debug_control;
                break;


            default:
                return KERN_INVALID_ARGUMENT;
        }/* switch */

        itk_lock(task);
        if (task->itk_self == IP_NULL) {
                itk_unlock(task);
                return KERN_FAILURE;
        }

        /* do not allow overwrite of seatbelt or task access ports */
        if ((TASK_SEATBELT_PORT == which  || TASK_ACCESS_PORT == which) 
                && IP_VALID(*whichp)) {
                        itk_unlock(task);
                        return KERN_NO_ACCESS;
        }

        old = *whichp;
        *whichp = port;
        itk_unlock(task);

        if (IP_VALID(old))
                ipc_port_release_send(old);
        return KERN_SUCCESS;
}


/*
 *      Routine:        mach_ports_register [kernel call]
 *      Purpose:
 *              Stash a handful of port send rights in the task.
 *              Child tasks will inherit these rights, but they
 *              must use mach_ports_lookup to acquire them.
 *
 *              The rights are supplied in a (wired) kalloc'd segment.
 *              Rights which aren't supplied are assumed to be null.
 *      Conditions:
 *              Nothing locked.  If successful, consumes
 *              the supplied rights and memory.
 *      Returns:
 *              KERN_SUCCESS            Stashed the port rights.
 *              KERN_INVALID_ARGUMENT   The task is null.
 *              KERN_INVALID_ARGUMENT   The task is dead.
 *              KERN_INVALID_ARGUMENT   The memory param is null.
 *              KERN_INVALID_ARGUMENT   Too many port rights supplied.
 */

kern_return_t
mach_ports_register(
        task_t                  task,
        mach_port_array_t       memory,
        mach_msg_type_number_t  portsCnt)
{
        ipc_port_t ports[TASK_PORT_REGISTER_MAX];
        unsigned int i;

        if ((task == TASK_NULL) ||
            (portsCnt > TASK_PORT_REGISTER_MAX) ||
            (portsCnt && memory == NULL))
                return KERN_INVALID_ARGUMENT;

        /*
         *      Pad the port rights with nulls.
         */

        for (i = 0; i < portsCnt; i++)
                ports[i] = memory[i];
        for (; i < TASK_PORT_REGISTER_MAX; i++)
                ports[i] = IP_NULL;

        itk_lock(task);
        if (task->itk_self == IP_NULL) {
                itk_unlock(task);
                return KERN_INVALID_ARGUMENT;
        }

        /*
         *      Replace the old send rights with the new.
         *      Release the old rights after unlocking.
         */

        for (i = 0; i < TASK_PORT_REGISTER_MAX; i++) {
                ipc_port_t old;

                old = task->itk_registered[i];
                task->itk_registered[i] = ports[i];
                ports[i] = old;
        }

        itk_unlock(task);

        for (i = 0; i < TASK_PORT_REGISTER_MAX; i++)
                if (IP_VALID(ports[i]))
                        ipc_port_release_send(ports[i]);

        /*
         *      Now that the operation is known to be successful,
         *      we can free the memory.
         */

        if (portsCnt != 0)
                kfree(memory,
                      (vm_size_t) (portsCnt * sizeof(mach_port_t)));

        return KERN_SUCCESS;
}

/*
 *      Routine:        mach_ports_lookup [kernel call]
 *      Purpose:
 *              Retrieves (clones) the stashed port send rights.
 *      Conditions:
 *              Nothing locked.  If successful, the caller gets
 *              rights and memory.
 *      Returns:
 *              KERN_SUCCESS            Retrieved the send rights.
 *              KERN_INVALID_ARGUMENT   The task is null.
 *              KERN_INVALID_ARGUMENT   The task is dead.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 */

kern_return_t
mach_ports_lookup(
        task_t                  task,
        mach_port_array_t       *portsp,
        mach_msg_type_number_t  *portsCnt)
{
        void  *memory;
        vm_size_t size;
        ipc_port_t *ports;
        int i;

        if (task == TASK_NULL)
                return KERN_INVALID_ARGUMENT;

        size = (vm_size_t) (TASK_PORT_REGISTER_MAX * sizeof(ipc_port_t));

        memory = kalloc(size);
        if (memory == 0)
                return KERN_RESOURCE_SHORTAGE;

        itk_lock(task);
        if (task->itk_self == IP_NULL) {
                itk_unlock(task);

                kfree(memory, size);
                return KERN_INVALID_ARGUMENT;
        }

        ports = (ipc_port_t *) memory;

        /*
         *      Clone port rights.  Because kalloc'd memory
         *      is wired, we won't fault while holding the task lock.
         */

        for (i = 0; i < TASK_PORT_REGISTER_MAX; i++)
                ports[i] = ipc_port_copy_send(task->itk_registered[i]);

        itk_unlock(task);

        *portsp = (mach_port_array_t) ports;
        *portsCnt = TASK_PORT_REGISTER_MAX;
        return KERN_SUCCESS;
}

/*
 *      Routine: convert_port_to_locked_task
 *      Purpose:
 *              Internal helper routine to convert from a port to a locked
 *              task.  Used by several routines that try to convert from a
 *              task port to a reference on some task related object.
 *      Conditions:
 *              Nothing locked, blocking OK.
 */
task_t
convert_port_to_locked_task(ipc_port_t port)
{
        int try_failed_count = 0;

        while (IP_VALID(port)) {
                task_t task;

                ip_lock(port);
                if (!ip_active(port) || (ip_kotype(port) != IKOT_TASK)) {
                        ip_unlock(port);
                        return TASK_NULL;
                }
                task = (task_t) port->ip_kobject;
                assert(task != TASK_NULL);

                /*
                 * Normal lock ordering puts task_lock() before ip_lock().
                 * Attempt out-of-order locking here.
                 */
                if (task_lock_try(task)) {
                        ip_unlock(port);
                        return(task);
                }
                try_failed_count++;

                ip_unlock(port);
                mutex_pause(try_failed_count);
        }
        return TASK_NULL;
}

/*
 *      Routine:        convert_port_to_task
 *      Purpose:
 *              Convert from a port to a task.
 *              Doesn't consume the port ref; produces a task ref,
 *              which may be null.
 *      Conditions:
 *              Nothing locked.
 */
task_t
convert_port_to_task(
        ipc_port_t              port)
{
        task_t          task = TASK_NULL;

        if (IP_VALID(port)) {
                ip_lock(port);

                if (    ip_active(port)                                 &&
                                ip_kotype(port) == IKOT_TASK            ) {
                        task = (task_t)port->ip_kobject;
                        assert(task != TASK_NULL);

                        task_reference_internal(task);
                }

                ip_unlock(port);
        }

        return (task);
}

/*
 *      Routine:        convert_port_to_task_name
 *      Purpose:
 *              Convert from a port to a task name.
 *              Doesn't consume the port ref; produces a task name ref,
 *              which may be null.
 *      Conditions:
 *              Nothing locked.
 */
task_name_t
convert_port_to_task_name(
        ipc_port_t              port)
{
        task_name_t             task = TASK_NULL;

        if (IP_VALID(port)) {
                ip_lock(port);

                if (    ip_active(port)                                 &&
                                (ip_kotype(port) == IKOT_TASK   ||
                                 ip_kotype(port) == IKOT_TASK_NAME)) {
                        task = (task_name_t)port->ip_kobject;
                        assert(task != TASK_NAME_NULL);

                        task_reference_internal(task);
                }

                ip_unlock(port);
        }

        return (task);
}

/*
 *      Routine:        convert_port_to_task_suspension_token
 *      Purpose:
 *              Convert from a port to a task suspension token.
 *              Doesn't consume the port ref; produces a suspension token ref,
 *              which may be null.
 *      Conditions:
 *              Nothing locked.
 */
task_suspension_token_t
convert_port_to_task_suspension_token(
        ipc_port_t              port)
{
        task_suspension_token_t         task = TASK_NULL;

        if (IP_VALID(port)) {
                ip_lock(port);

                if (    ip_active(port)                                 &&
                                ip_kotype(port) == IKOT_TASK_RESUME) {
                        task = (task_suspension_token_t)port->ip_kobject;
                        assert(task != TASK_NULL);

                        task_reference_internal(task);
                }

                ip_unlock(port);
        }

        return (task);
}

/*
 *      Routine:        convert_port_to_space
 *      Purpose:
 *              Convert from a port to a space.
 *              Doesn't consume the port ref; produces a space ref,
 *              which may be null.
 *      Conditions:
 *              Nothing locked.
 */
ipc_space_t
convert_port_to_space(
        ipc_port_t      port)
{
        ipc_space_t space;
        task_t task;

        task = convert_port_to_locked_task(port);

        if (task == TASK_NULL)
                return IPC_SPACE_NULL;

        if (!task->active) {
                task_unlock(task);
                return IPC_SPACE_NULL;
        }
                
        space = task->itk_space;
        is_reference(space);
        task_unlock(task);
        return (space);
}

/*
 *      Routine:        convert_port_to_map
 *      Purpose:
 *              Convert from a port to a map.
 *              Doesn't consume the port ref; produces a map ref,
 *              which may be null.
 *      Conditions:
 *              Nothing locked.
 */

vm_map_t
convert_port_to_map(
        ipc_port_t      port)
{
        task_t task;
        vm_map_t map;

        task = convert_port_to_locked_task(port);
                
        if (task == TASK_NULL)
                return VM_MAP_NULL;

        if (!task->active) {
                task_unlock(task);
                return VM_MAP_NULL;
        }
                
        map = task->map;
        vm_map_reference_swap(map);
        task_unlock(task);
        return map;
}


/*
 *      Routine:        convert_port_to_thread
 *      Purpose:
 *              Convert from a port to a thread.
 *              Doesn't consume the port ref; produces an thread ref,
 *              which may be null.
 *      Conditions:
 *              Nothing locked.
 */

thread_t
convert_port_to_thread(
        ipc_port_t              port)
{
        thread_t        thread = THREAD_NULL;

        if (IP_VALID(port)) {
                ip_lock(port);

                if (    ip_active(port)                                 &&
                                ip_kotype(port) == IKOT_THREAD          ) {
                        thread = (thread_t)port->ip_kobject;
                        assert(thread != THREAD_NULL);

                        thread_reference_internal(thread);
                }

                ip_unlock(port);
        }

        return (thread);
}

/*
 *      Routine:        port_name_to_thread
 *      Purpose:
 *              Convert from a port name to an thread reference
 *              A name of MACH_PORT_NULL is valid for the null thread.
 *      Conditions:
 *              Nothing locked.
 *
 *      TODO: Could this be faster if it were ipc_port_translate_send based, like thread_switch?
 *            We could avoid extra lock/unlock and extra ref operations on the port.
 */
thread_t
port_name_to_thread(
        mach_port_name_t        name)
{
        thread_t        thread = THREAD_NULL;
        ipc_port_t      kport;

        if (MACH_PORT_VALID(name)) {
                if (ipc_object_copyin(current_space(), name,
                                               MACH_MSG_TYPE_COPY_SEND,
                                                          (ipc_object_t *)&kport) != KERN_SUCCESS)
                        return (THREAD_NULL);

                thread = convert_port_to_thread(kport);
                
                if (IP_VALID(kport))
                        ipc_port_release_send(kport);
        }

        return (thread);
}

task_t
port_name_to_task(
        mach_port_name_t name)
{
        ipc_port_t kern_port;
        kern_return_t kr;
        task_t task = TASK_NULL;

        if (MACH_PORT_VALID(name)) {
                kr = ipc_object_copyin(current_space(), name,
                                       MACH_MSG_TYPE_COPY_SEND,
                                       (ipc_object_t *) &kern_port);
                if (kr != KERN_SUCCESS)
                        return TASK_NULL;

                task = convert_port_to_task(kern_port);

                if (IP_VALID(kern_port))
                        ipc_port_release_send(kern_port);
        }
        return task;
}

/*
 *      Routine:        convert_task_to_port
 *      Purpose:
 *              Convert from a task to a port.
 *              Consumes a task ref; produces a naked send right
 *              which may be invalid.  
 *      Conditions:
 *              Nothing locked.
 */

ipc_port_t
convert_task_to_port(
        task_t          task)
{
        ipc_port_t port;

        itk_lock(task);
        if (task->itk_self != IP_NULL)
                port = ipc_port_make_send(task->itk_self);
        else
                port = IP_NULL;
        itk_unlock(task);

        task_deallocate(task);
        return port;
}

/*
 *      Routine:        convert_task_suspend_token_to_port
 *      Purpose:
 *              Convert from a task suspension token to a port.
 *              Consumes a task suspension token ref; produces a naked send-once right
 *              which may be invalid.  
 *      Conditions:
 *              Nothing locked.
 */
ipc_port_t
convert_task_suspension_token_to_port(
        task_suspension_token_t         task)
{
        ipc_port_t port;

        task_lock(task);
        if (task->active) {
                if (task->itk_resume == IP_NULL) {
                        task->itk_resume = ipc_port_alloc_kernel();
                        if (!IP_VALID(task->itk_resume)) {
                                panic("failed to create resume port");
                        }

                        ipc_kobject_set(task->itk_resume, (ipc_kobject_t) task, IKOT_TASK_RESUME);
                }

                /*
                 * Create a send-once right for each instance of a direct user-called
                 * task_suspend2 call. Each time one of these send-once rights is abandoned,
                 * the notification handler will resume the target task.
                 */
                port = ipc_port_make_sonce(task->itk_resume);
                assert(IP_VALID(port));
        } else {
                port = IP_NULL;
        }

        task_unlock(task);
        task_suspension_token_deallocate(task);

        return port;
}


/*
 *      Routine:        convert_task_name_to_port
 *      Purpose:
 *              Convert from a task name ref to a port.
 *              Consumes a task name ref; produces a naked send right
 *              which may be invalid.  
 *      Conditions:
 *              Nothing locked.
 */

ipc_port_t
convert_task_name_to_port(
        task_name_t             task_name)
{
        ipc_port_t port;

        itk_lock(task_name);
        if (task_name->itk_nself != IP_NULL)
                port = ipc_port_make_send(task_name->itk_nself);
        else
                port = IP_NULL;
        itk_unlock(task_name);

        task_name_deallocate(task_name);
        return port;
}

/*
 *      Routine:        convert_thread_to_port
 *      Purpose:
 *              Convert from a thread to a port.
 *              Consumes an thread ref; produces a naked send right
 *              which may be invalid.
 *      Conditions:
 *              Nothing locked.
 */

ipc_port_t
convert_thread_to_port(
        thread_t                thread)
{
        ipc_port_t              port;

        thread_mtx_lock(thread);

        if (thread->ith_self != IP_NULL)
                port = ipc_port_make_send(thread->ith_self);
        else
                port = IP_NULL;

        thread_mtx_unlock(thread);

        thread_deallocate(thread);

        return (port);
}

/*
 *      Routine:        space_deallocate
 *      Purpose:
 *              Deallocate a space ref produced by convert_port_to_space.
 *      Conditions:
 *              Nothing locked.
 */

void
space_deallocate(
        ipc_space_t     space)
{
        if (space != IS_NULL)
                is_release(space);
}

/*
 *      Routine:        thread/task_set_exception_ports [kernel call]
 *      Purpose:
 *                      Sets the thread/task exception port, flavor and
 *                      behavior for the exception types specified by the mask.
 *                      There will be one send right per exception per valid
 *                      port.
 *      Conditions:
 *              Nothing locked.  If successful, consumes
 *              the supplied send right.
 *      Returns:
 *              KERN_SUCCESS            Changed the special port.
 *              KERN_INVALID_ARGUMENT   The thread is null,
 *                                      Illegal mask bit set.
 *                                      Illegal exception behavior
 *              KERN_FAILURE            The thread is dead.
 */

kern_return_t
thread_set_exception_ports(
        thread_t                                thread,
        exception_mask_t                exception_mask,
        ipc_port_t                              new_port,
        exception_behavior_t    new_behavior,
        thread_state_flavor_t   new_flavor)
{
        ipc_port_t              old_port[EXC_TYPES_COUNT];
        boolean_t privileged = current_task()->sec_token.val[0] == 0;
        register int    i;

        if (thread == THREAD_NULL)
                return (KERN_INVALID_ARGUMENT);

        if (exception_mask & ~EXC_MASK_VALID)
                return (KERN_INVALID_ARGUMENT);

        if (IP_VALID(new_port)) {
                switch (new_behavior & ~MACH_EXCEPTION_CODES) {

                case EXCEPTION_DEFAULT:
                case EXCEPTION_STATE:
                case EXCEPTION_STATE_IDENTITY:
                        break;

                default:
                        return (KERN_INVALID_ARGUMENT);
                }
        }

        /* 
         * Check the validity of the thread_state_flavor by calling the
         * VALID_THREAD_STATE_FLAVOR architecture dependent macro defined in
         * osfmk/mach/ARCHITECTURE/thread_status.h
         */
        if (new_flavor != 0 && !VALID_THREAD_STATE_FLAVOR(new_flavor))
                return (KERN_INVALID_ARGUMENT);

        thread_mtx_lock(thread);

        if (!thread->active) {
                thread_mtx_unlock(thread);

                return (KERN_FAILURE);
        }

        if (thread->exc_actions == NULL) {
                ipc_thread_init_exc_actions(thread);
        }
        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; ++i) {
                if (exception_mask & (1 << i)) {
                        old_port[i] = thread->exc_actions[i].port;
                        thread->exc_actions[i].port = ipc_port_copy_send(new_port);
                        thread->exc_actions[i].behavior = new_behavior;
                        thread->exc_actions[i].flavor = new_flavor;
                        thread->exc_actions[i].privileged = privileged;
                }
                else
                        old_port[i] = IP_NULL;
        }

        thread_mtx_unlock(thread);

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; ++i)
                if (IP_VALID(old_port[i]))
                        ipc_port_release_send(old_port[i]);

        if (IP_VALID(new_port))          /* consume send right */
                ipc_port_release_send(new_port);

        return (KERN_SUCCESS);
}

kern_return_t
task_set_exception_ports(
        task_t                                  task,
        exception_mask_t                exception_mask,
        ipc_port_t                              new_port,
        exception_behavior_t    new_behavior,
        thread_state_flavor_t   new_flavor)
{
        ipc_port_t              old_port[EXC_TYPES_COUNT];
        boolean_t privileged = current_task()->sec_token.val[0] == 0;
        register int    i;

        if (task == TASK_NULL)
                return (KERN_INVALID_ARGUMENT);

        if (exception_mask & ~EXC_MASK_VALID)
                return (KERN_INVALID_ARGUMENT);

        if (IP_VALID(new_port)) {
                switch (new_behavior & ~MACH_EXCEPTION_CODES) {

                case EXCEPTION_DEFAULT:
                case EXCEPTION_STATE:
                case EXCEPTION_STATE_IDENTITY:
                        break;

                default:
                        return (KERN_INVALID_ARGUMENT);
                }
        }

        /*
         * Check the validity of the thread_state_flavor by calling the
         * VALID_THREAD_STATE_FLAVOR architecture dependent macro defined in
         * osfmk/mach/ARCHITECTURE/thread_status.h
         */
        if (new_flavor != 0 && !VALID_THREAD_STATE_FLAVOR(new_flavor))
                return (KERN_INVALID_ARGUMENT);

        itk_lock(task);

        if (task->itk_self == IP_NULL) {
                itk_unlock(task);

                return (KERN_FAILURE);
        }

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; ++i) {
                if (exception_mask & (1 << i)) {
                        old_port[i] = task->exc_actions[i].port;
                        task->exc_actions[i].port =
                                ipc_port_copy_send(new_port);
                        task->exc_actions[i].behavior = new_behavior;
                        task->exc_actions[i].flavor = new_flavor;
                        task->exc_actions[i].privileged = privileged;
                }
                else
                        old_port[i] = IP_NULL;
        }

        itk_unlock(task);

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; ++i)
                if (IP_VALID(old_port[i]))
                        ipc_port_release_send(old_port[i]);

        if (IP_VALID(new_port))          /* consume send right */
                ipc_port_release_send(new_port);

        return (KERN_SUCCESS);
}

/*
 *      Routine:        thread/task_swap_exception_ports [kernel call]
 *      Purpose:
 *                      Sets the thread/task exception port, flavor and
 *                      behavior for the exception types specified by the
 *                      mask.
 *
 *                      The old ports, behavior and flavors are returned
 *                      Count specifies the array sizes on input and
 *                      the number of returned ports etc. on output.  The
 *                      arrays must be large enough to hold all the returned
 *                      data, MIG returnes an error otherwise.  The masks
 *                      array specifies the corresponding exception type(s).
 *
 *      Conditions:
 *              Nothing locked.  If successful, consumes
 *              the supplied send right.
 *
 *              Returns upto [in} CountCnt elements.
 *      Returns:
 *              KERN_SUCCESS            Changed the special port.
 *              KERN_INVALID_ARGUMENT   The thread is null,
 *                                      Illegal mask bit set.
 *                                      Illegal exception behavior
 *              KERN_FAILURE            The thread is dead.
 */

kern_return_t
thread_swap_exception_ports(
        thread_t                                        thread,
        exception_mask_t                        exception_mask,
        ipc_port_t                                      new_port,
        exception_behavior_t            new_behavior,
        thread_state_flavor_t           new_flavor,
        exception_mask_array_t          masks,
        mach_msg_type_number_t          *CountCnt,
        exception_port_array_t          ports,
        exception_behavior_array_t      behaviors,
        thread_state_flavor_array_t     flavors)
{
        ipc_port_t              old_port[EXC_TYPES_COUNT];
        boolean_t privileged = current_task()->sec_token.val[0] == 0;
        unsigned int    i, j, count;

        if (thread == THREAD_NULL)
                return (KERN_INVALID_ARGUMENT);

        if (exception_mask & ~EXC_MASK_VALID)
                return (KERN_INVALID_ARGUMENT);

        if (IP_VALID(new_port)) {
                switch (new_behavior & ~MACH_EXCEPTION_CODES) {

                case EXCEPTION_DEFAULT:
                case EXCEPTION_STATE:
                case EXCEPTION_STATE_IDENTITY:
                        break;

                default:
                        return (KERN_INVALID_ARGUMENT);
                }
        }

        if (new_flavor != 0 && !VALID_THREAD_STATE_FLAVOR(new_flavor))
                return (KERN_INVALID_ARGUMENT);

        thread_mtx_lock(thread);

        if (!thread->active) {
                thread_mtx_unlock(thread);

                return (KERN_FAILURE);
        }

        if (thread->exc_actions == NULL) {
                ipc_thread_init_exc_actions(thread);
        }

        assert(EXC_TYPES_COUNT > FIRST_EXCEPTION);
        for (count = 0, i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT && count < *CountCnt; ++i) {
                if (exception_mask & (1 << i)) {
                        for (j = 0; j < count; ++j) {
                                /*
                                 * search for an identical entry, if found
                                 * set corresponding mask for this exception.
                                 */
                                if (    thread->exc_actions[i].port == ports[j]                         &&
                                                thread->exc_actions[i].behavior == behaviors[j]         &&
                                                thread->exc_actions[i].flavor == flavors[j]                     ) {
                                        masks[j] |= (1 << i);
                                        break;
                                }
                        }

                        if (j == count) {
                                masks[j] = (1 << i);
                                ports[j] = ipc_port_copy_send(thread->exc_actions[i].port);

                                behaviors[j] = thread->exc_actions[i].behavior;
                                flavors[j] = thread->exc_actions[i].flavor;
                                ++count;
                        }

                        old_port[i] = thread->exc_actions[i].port;
                        thread->exc_actions[i].port = ipc_port_copy_send(new_port);
                        thread->exc_actions[i].behavior = new_behavior;
                        thread->exc_actions[i].flavor = new_flavor;
                        thread->exc_actions[i].privileged = privileged;
                }
                else
                        old_port[i] = IP_NULL;
        }

        thread_mtx_unlock(thread);

        while (--i >= FIRST_EXCEPTION) {
                if (IP_VALID(old_port[i]))
                        ipc_port_release_send(old_port[i]);
        }

        if (IP_VALID(new_port))          /* consume send right */
                ipc_port_release_send(new_port);

        *CountCnt = count;

        return (KERN_SUCCESS);
}

kern_return_t
task_swap_exception_ports(
        task_t                                          task,
        exception_mask_t                        exception_mask,
        ipc_port_t                                      new_port,
        exception_behavior_t            new_behavior,
        thread_state_flavor_t           new_flavor,
        exception_mask_array_t          masks,
        mach_msg_type_number_t          *CountCnt,
        exception_port_array_t          ports,
        exception_behavior_array_t      behaviors,
        thread_state_flavor_array_t     flavors)
{
        ipc_port_t              old_port[EXC_TYPES_COUNT];
        boolean_t privileged = current_task()->sec_token.val[0] == 0;
        unsigned int    i, j, count;

        if (task == TASK_NULL)
                return (KERN_INVALID_ARGUMENT);

        if (exception_mask & ~EXC_MASK_VALID)
                return (KERN_INVALID_ARGUMENT);

        if (IP_VALID(new_port)) {
                switch (new_behavior & ~MACH_EXCEPTION_CODES) {

                case EXCEPTION_DEFAULT:
                case EXCEPTION_STATE:
                case EXCEPTION_STATE_IDENTITY:
                        break;

                default:
                        return (KERN_INVALID_ARGUMENT);
                }
        }

        if (new_flavor != 0 && !VALID_THREAD_STATE_FLAVOR(new_flavor))
                return (KERN_INVALID_ARGUMENT);

        itk_lock(task);

        if (task->itk_self == IP_NULL) {
                itk_unlock(task);

                return (KERN_FAILURE);
        }

        assert(EXC_TYPES_COUNT > FIRST_EXCEPTION);
        for (count = 0, i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT && count < *CountCnt; ++i) {
                if (exception_mask & (1 << i)) {
                        for (j = 0; j < count; j++) {
                                /*
                                 * search for an identical entry, if found
                                 * set corresponding mask for this exception.
                                 */
                                if (    task->exc_actions[i].port == ports[j]                   &&
                                                task->exc_actions[i].behavior == behaviors[j]   &&
                                                task->exc_actions[i].flavor == flavors[j]               ) {
                                        masks[j] |= (1 << i);
                                        break;
                                }
                        }

                        if (j == count) {
                                masks[j] = (1 << i);
                                ports[j] = ipc_port_copy_send(task->exc_actions[i].port);
                                behaviors[j] = task->exc_actions[i].behavior;
                                flavors[j] = task->exc_actions[i].flavor;
                                ++count;
                        }

                        old_port[i] = task->exc_actions[i].port;

                        task->exc_actions[i].port =     ipc_port_copy_send(new_port);
                        task->exc_actions[i].behavior = new_behavior;
                        task->exc_actions[i].flavor = new_flavor;
                        task->exc_actions[i].privileged = privileged;
                }
                else
                        old_port[i] = IP_NULL;
        }

        itk_unlock(task);

        while (--i >= FIRST_EXCEPTION) {
                if (IP_VALID(old_port[i]))
                        ipc_port_release_send(old_port[i]);
        }

        if (IP_VALID(new_port))          /* consume send right */
                ipc_port_release_send(new_port);

        *CountCnt = count;

        return (KERN_SUCCESS);
}

/*
 *      Routine:        thread/task_get_exception_ports [kernel call]
 *      Purpose:
 *              Clones a send right for each of the thread/task's exception
 *              ports specified in the mask and returns the behaviour
 *              and flavor of said port.
 *
 *              Returns upto [in} CountCnt elements.
 *
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Extracted a send right.
 *              KERN_INVALID_ARGUMENT   The thread is null,
 *                                      Invalid special port,
 *                                      Illegal mask bit set.
 *              KERN_FAILURE            The thread is dead.
 */

kern_return_t
thread_get_exception_ports(
        thread_t                                        thread,
        exception_mask_t                        exception_mask,
        exception_mask_array_t          masks,
        mach_msg_type_number_t          *CountCnt,
        exception_port_array_t          ports,
        exception_behavior_array_t      behaviors,
        thread_state_flavor_array_t     flavors)
{
        unsigned int    i, j, count;

        if (thread == THREAD_NULL)
                return (KERN_INVALID_ARGUMENT);

        if (exception_mask & ~EXC_MASK_VALID)
                return (KERN_INVALID_ARGUMENT);

        thread_mtx_lock(thread);

        if (!thread->active) {
                thread_mtx_unlock(thread);

                return (KERN_FAILURE);
        }

        count = 0;

        if (thread->exc_actions == NULL) {
                goto done;
        }

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; ++i) {
                if (exception_mask & (1 << i)) {
                        for (j = 0; j < count; ++j) {
                                /*
                                 * search for an identical entry, if found
                                 * set corresponding mask for this exception.
                                 */
                                if (    thread->exc_actions[i].port == ports[j]                 &&
                                                thread->exc_actions[i].behavior ==behaviors[j]  &&
                                                thread->exc_actions[i].flavor == flavors[j]             ) {
                                        masks[j] |= (1 << i);
                                        break;
                                }
                        }

                        if (j == count) {
                                masks[j] = (1 << i);
                                ports[j] = ipc_port_copy_send(thread->exc_actions[i].port);
                                behaviors[j] = thread->exc_actions[i].behavior;
                                flavors[j] = thread->exc_actions[i].flavor;
                                ++count;
                                if (count >= *CountCnt)
                                        break;
                        }
                }
        }

done:
        thread_mtx_unlock(thread);

        *CountCnt = count;

        return (KERN_SUCCESS);
}

kern_return_t
task_get_exception_ports(
        task_t                                          task,
        exception_mask_t                        exception_mask,
        exception_mask_array_t          masks,
        mach_msg_type_number_t          *CountCnt,
        exception_port_array_t          ports,
        exception_behavior_array_t      behaviors,
        thread_state_flavor_array_t     flavors)
{
        unsigned int    i, j, count;

        if (task == TASK_NULL)
                return (KERN_INVALID_ARGUMENT);

        if (exception_mask & ~EXC_MASK_VALID)
                return (KERN_INVALID_ARGUMENT);

        itk_lock(task);

        if (task->itk_self == IP_NULL) {
                itk_unlock(task);

                return (KERN_FAILURE);
        }

        count = 0;

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; ++i) {
                if (exception_mask & (1 << i)) {
                        for (j = 0; j < count; ++j) {
                                /*
                                 * search for an identical entry, if found
                                 * set corresponding mask for this exception.
                                 */
                                if (    task->exc_actions[i].port == ports[j]                   &&
                                                task->exc_actions[i].behavior == behaviors[j]   &&
                                                task->exc_actions[i].flavor == flavors[j]               ) {
                                        masks[j] |= (1 << i);
                                        break;
                                }
                        }

                        if (j == count) {
                                masks[j] = (1 << i);
                                ports[j] = ipc_port_copy_send(task->exc_actions[i].port);
                                behaviors[j] = task->exc_actions[i].behavior;
                                flavors[j] = task->exc_actions[i].flavor;
                                ++count;
                                if (count > *CountCnt)
                                        break;
                        }
                }
        }

        itk_unlock(task);

        *CountCnt = count;

        return (KERN_SUCCESS);
}