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

/*
 * Copyright (c) 2000-2016 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 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 SPARTA, Inc.
 */
/*
 */
/*
 *      File:   kern/ipc_kobject.c
 *      Author: Rich Draves
 *      Date:   1989
 *
 *      Functions for letting a port represent a kernel object.
 */

#include <mach_debug.h>
#include <mach_ipc_test.h>
#include <mach/mig.h>
#include <mach/port.h>
#include <mach/kern_return.h>
#include <mach/message.h>
#include <mach/mig_errors.h>
#include <mach/notify.h>
#include <mach/ndr.h>
#include <mach/vm_param.h>

#include <mach/mach_vm_server.h>
#include <mach/mach_port_server.h>
#include <mach/mach_host_server.h>
#include <mach/host_priv_server.h>
#include <mach/host_security_server.h>
#include <mach/clock_server.h>
#include <mach/clock_priv_server.h>
#include <mach/lock_set_server.h>
#include <mach/memory_entry_server.h>
#include <mach/memory_object_control_server.h>
#include <mach/memory_object_default_server.h>
#include <mach/processor_server.h>
#include <mach/processor_set_server.h>
#include <mach/task_server.h>
#include <mach/mach_voucher_server.h>
#include <mach/mach_voucher_attr_control_server.h>
#ifdef VM32_SUPPORT
#include <mach/vm32_map_server.h>
#endif
#include <mach/thread_act_server.h>
#include <mach/restartable_server.h>

#include <mach/exc_server.h>
#include <mach/mach_exc_server.h>

#include <device/device_types.h>
#include <device/device_server.h>

#include <UserNotification/UNDReplyServer.h>

#if     CONFIG_ARCADE
#include <mach/arcade_register_server.h>
#endif

#if     CONFIG_AUDIT
#include <kern/audit_sessionport.h>
#endif

#if     MACH_MACHINE_ROUTINES
#include <machine/machine_routines.h>
#endif  /* MACH_MACHINE_ROUTINES */
#if     XK_PROXY
#include <uk_xkern/xk_uproxy_server.h>
#endif  /* XK_PROXY */

#include <kern/ipc_tt.h>
#include <kern/ipc_mig.h>
#include <kern/ipc_misc.h>
#include <kern/ipc_kobject.h>
#include <kern/host_notify.h>
#include <kern/mk_timer.h>
#include <kern/misc_protos.h>

#if CONFIG_ARCADE
#include <kern/arcade.h>
#endif /* CONFIG_ARCADE */

#include <ipc/ipc_kmsg.h>
#include <ipc/ipc_port.h>
#include <ipc/ipc_voucher.h>
#include <kern/sync_sema.h>
#include <kern/counters.h>
#include <kern/work_interval.h>

#include <vm/vm_protos.h>

#include <security/mac_mach_internal.h>

extern char *proc_name_address(void *p);
extern int proc_pid(void *p);

/*
 *      Routine:        ipc_kobject_notify
 *      Purpose:
 *              Deliver notifications to kobjects that care about them.
 */
boolean_t
ipc_kobject_notify(
        mach_msg_header_t *request_header,
        mach_msg_header_t *reply_header);

typedef struct {
        mach_msg_id_t num;
        mig_routine_t routine;
        int size;
#if     MACH_COUNTERS
        mach_counter_t callcount;
#endif
} mig_hash_t;

#define MAX_MIG_ENTRIES 1031
#define MIG_HASH(x) (x)

#ifndef max
#define max(a, b)        (((a) > (b)) ? (a) : (b))
#endif /* max */

static mig_hash_t mig_buckets[MAX_MIG_ENTRIES];
static int mig_table_max_displ;
static mach_msg_size_t mig_reply_size = sizeof(mig_reply_error_t);



const struct mig_subsystem *mig_e[] = {
        (const struct mig_subsystem *)&mach_vm_subsystem,
        (const struct mig_subsystem *)&mach_port_subsystem,
        (const struct mig_subsystem *)&mach_host_subsystem,
        (const struct mig_subsystem *)&host_priv_subsystem,
        (const struct mig_subsystem *)&host_security_subsystem,
        (const struct mig_subsystem *)&clock_subsystem,
        (const struct mig_subsystem *)&clock_priv_subsystem,
        (const struct mig_subsystem *)&processor_subsystem,
        (const struct mig_subsystem *)&processor_set_subsystem,
        (const struct mig_subsystem *)&is_iokit_subsystem,
        (const struct mig_subsystem *)&lock_set_subsystem,
        (const struct mig_subsystem *)&task_subsystem,
        (const struct mig_subsystem *)&thread_act_subsystem,
#ifdef VM32_SUPPORT
        (const struct mig_subsystem *)&vm32_map_subsystem,
#endif
        (const struct mig_subsystem *)&UNDReply_subsystem,
        (const struct mig_subsystem *)&mach_voucher_subsystem,
        (const struct mig_subsystem *)&mach_voucher_attr_control_subsystem,
        (const struct mig_subsystem *)&memory_entry_subsystem,
        (const struct mig_subsystem *)&task_restartable_subsystem,

#if     XK_PROXY
        (const struct mig_subsystem *)&do_uproxy_xk_uproxy_subsystem,
#endif /* XK_PROXY */
#if     MACH_MACHINE_ROUTINES
        (const struct mig_subsystem *)&MACHINE_SUBSYSTEM,
#endif  /* MACH_MACHINE_ROUTINES */
#if     MCMSG && iPSC860
        (const struct mig_subsystem *)&mcmsg_info_subsystem,
#endif  /* MCMSG && iPSC860 */
        (const struct mig_subsystem *)&catch_exc_subsystem,
        (const struct mig_subsystem *)&catch_mach_exc_subsystem,
#if CONFIG_ARCADE
        (const struct mig_subsystem *)&arcade_register_subsystem,
#endif
};

void
mig_init(void)
{
        unsigned int i, n = sizeof(mig_e) / sizeof(const struct mig_subsystem *);
        int howmany;
        mach_msg_id_t j, pos, nentry, range;

        for (i = 0; i < n; i++) {
                range = mig_e[i]->end - mig_e[i]->start;
                if (!mig_e[i]->start || range < 0) {
                        panic("the msgh_ids in mig_e[] aren't valid!");
                }

                for (j = 0; j < range; j++) {
                        if (mig_e[i]->routine[j].stub_routine) {
                                /* Only put real entries in the table */
                                nentry = j + mig_e[i]->start;
                                for (pos = MIG_HASH(nentry) % MAX_MIG_ENTRIES, howmany = 1;
                                    mig_buckets[pos].num;
                                    pos++, pos = pos % MAX_MIG_ENTRIES, howmany++) {
                                        if (mig_buckets[pos].num == nentry) {
                                                printf("message id = %d\n", nentry);
                                                panic("multiple entries with the same msgh_id");
                                        }
                                        if (howmany == MAX_MIG_ENTRIES) {
                                                panic("the mig dispatch table is too small");
                                        }
                                }

                                mig_buckets[pos].num = nentry;
                                mig_buckets[pos].routine = mig_e[i]->routine[j].stub_routine;
                                if (mig_e[i]->routine[j].max_reply_msg) {
                                        mig_buckets[pos].size = mig_e[i]->routine[j].max_reply_msg;
                                } else {
                                        mig_buckets[pos].size = mig_e[i]->maxsize;
                                }

                                mig_table_max_displ = max(howmany, mig_table_max_displ);
                        }
                }
        }
        printf("mig_table_max_displ = %d\n", mig_table_max_displ);
}


/*
 *      Routine:        ipc_kobject_server
 *      Purpose:
 *              Handle a message sent to the kernel.
 *              Generates a reply message.
 *              Version for Untyped IPC.
 *      Conditions:
 *              Nothing locked.
 */

ipc_kmsg_t
ipc_kobject_server(
        ipc_kmsg_t      request,
        mach_msg_option_t __unused option)
{
        mach_msg_size_t reply_size;
        ipc_kmsg_t reply;
        kern_return_t kr;
        ipc_port_t  replyp = IPC_PORT_NULL;
        mach_msg_format_0_trailer_t *trailer;
        mig_hash_t *ptr;
        task_t task = TASK_NULL;
        uint32_t exec_token;
        boolean_t exec_token_changed = FALSE;
        int request_msgh_id = request->ikm_header->msgh_id;
        natural_t ikot;
        ipc_port_t port;

        reply = NULL;
        port = request->ikm_header->msgh_remote_port;
        if (IP_VALID(port)) {
                ikot = ip_kotype(port);
        } else {
                ikot = IKOT_UNKNOWN;
        }
        if (ikot == IKOT_UEXT_OBJECT) {
                kr = uext_server(request, &reply);
                if ((MIG_NO_REPLY == kr) || (KERN_SUCCESS == kr)) {
                        ipc_kmsg_trace_send(request, option);
                        goto msgdone;
                }
        }
        /*
         * Find corresponding mig_hash entry if any
         */
        {
                unsigned int i = (unsigned int)MIG_HASH(request_msgh_id);
                int max_iter = mig_table_max_displ;

                do {
                        ptr = &mig_buckets[i++ % MAX_MIG_ENTRIES];
                } while (request_msgh_id != ptr->num && ptr->num && --max_iter);

                if (!ptr->routine || request_msgh_id != ptr->num) {
                        ptr = (mig_hash_t *)0;
                        reply_size = mig_reply_size;
                } else {
                        reply_size = ptr->size;
#if     MACH_COUNTERS
                        ptr->callcount++;
#endif
                }
        }

        /* round up for trailer size */
        reply_size += MAX_TRAILER_SIZE;
        reply = ipc_kmsg_alloc(reply_size);

        if (reply == IKM_NULL) {
                printf("ipc_kobject_server: dropping request\n");
                ipc_kmsg_trace_send(request, option);
                ipc_kmsg_destroy(request);
                return IKM_NULL;
        }

        /*
         * Initialize reply message.
         */
        {
#define InP     ((mach_msg_header_t *) request->ikm_header)
#define OutP    ((mig_reply_error_t *) reply->ikm_header)

                /*
                 * MIG should really assure no data leakage -
                 * but until it does, pessimistically zero the
                 * whole reply buffer.
                 */
                bzero((void *)OutP, reply_size);

                OutP->NDR = NDR_record;
                OutP->Head.msgh_size = sizeof(mig_reply_error_t);

                OutP->Head.msgh_bits =
                    MACH_MSGH_BITS_SET(MACH_MSGH_BITS_LOCAL(InP->msgh_bits), 0, 0, 0);
                OutP->Head.msgh_remote_port = InP->msgh_local_port;
                OutP->Head.msgh_local_port = MACH_PORT_NULL;
                OutP->Head.msgh_voucher_port = MACH_PORT_NULL;
                OutP->Head.msgh_id = InP->msgh_id + 100;

#undef  InP
#undef  OutP
        }

        /*
         * Find the routine to call, and call it
         * to perform the kernel function
         */
        ipc_kmsg_trace_send(request, option);
        {
                if (ptr) {
                        /*
                         * Check if the port is a task port, if its a task port then
                         * snapshot the task exec token before the mig routine call.
                         */
                        if (ikot == IKOT_TASK) {
                                task = convert_port_to_task_with_exec_token(port, &exec_token);
                        }

                        (*ptr->routine)(request->ikm_header, reply->ikm_header);

                        /* Check if the exec token changed during the mig routine */
                        if (task != TASK_NULL) {
                                if (exec_token != task->exec_token) {
                                        exec_token_changed = TRUE;
                                }
                                task_deallocate(task);
                        }

                        kernel_task->messages_received++;
                } else {
                        if (!ipc_kobject_notify(request->ikm_header, reply->ikm_header)) {
#if DEVELOPMENT || DEBUG
                                printf("ipc_kobject_server: bogus kernel message, id=%d\n",
                                    request->ikm_header->msgh_id);
#endif  /* DEVELOPMENT || DEBUG */
                                _MIG_MSGID_INVALID(request->ikm_header->msgh_id);

                                ((mig_reply_error_t *) reply->ikm_header)->RetCode
                                        = MIG_BAD_ID;
                        } else {
                                kernel_task->messages_received++;
                        }
                }
                kernel_task->messages_sent++;
        }

        if (!(reply->ikm_header->msgh_bits & MACH_MSGH_BITS_COMPLEX) &&
            ((mig_reply_error_t *) reply->ikm_header)->RetCode != KERN_SUCCESS) {
                kr = ((mig_reply_error_t *) reply->ikm_header)->RetCode;
        } else {
                kr = KERN_SUCCESS;
        }

msgdone:
        /*
         *      Destroy destination. The following code differs from
         *      ipc_object_destroy in that we release the send-once
         *      right instead of generating a send-once notification
         *      (which would bring us here again, creating a loop).
         *      It also differs in that we only expect send or
         *      send-once rights, never receive rights.
         *
         *      We set msgh_remote_port to IP_NULL so that the kmsg
         *      destroy routines don't try to destroy the port twice.
         */
        switch (MACH_MSGH_BITS_REMOTE(request->ikm_header->msgh_bits)) {
        case MACH_MSG_TYPE_PORT_SEND:
                ipc_port_release_send(request->ikm_header->msgh_remote_port);
                request->ikm_header->msgh_remote_port = IP_NULL;
                break;

        case MACH_MSG_TYPE_PORT_SEND_ONCE:
                ipc_port_release_sonce(request->ikm_header->msgh_remote_port);
                request->ikm_header->msgh_remote_port = IP_NULL;
                break;

        default:
                panic("ipc_kobject_server: strange destination rights");
        }

        /*
         *      Destroy voucher.  The kernel MIG servers never take ownership
         *      of vouchers sent in messages.  Swallow any such rights here.
         */
        if (IP_VALID(request->ikm_voucher)) {
                assert(MACH_MSG_TYPE_PORT_SEND ==
                    MACH_MSGH_BITS_VOUCHER(request->ikm_header->msgh_bits));
                ipc_port_release_send(request->ikm_voucher);
                request->ikm_voucher = IP_NULL;
        }

        if ((kr == KERN_SUCCESS) || (kr == MIG_NO_REPLY)) {
                /*
                 *      The server function is responsible for the contents
                 *      of the message.  The reply port right is moved
                 *      to the reply message, and we have deallocated
                 *      the destination port right, so we just need
                 *      to free the kmsg.
                 */
                ipc_kmsg_free(request);
        } else {
                /*
                 *      The message contents of the request are intact.
                 *      Destroy everthing except the reply port right,
                 *      which is needed in the reply message.
                 */
                request->ikm_header->msgh_local_port = MACH_PORT_NULL;
                ipc_kmsg_destroy(request);
        }

        if (kr == MIG_NO_REPLY) {
                /*
                 *      The server function will send a reply message
                 *      using the reply port right, which it has saved.
                 */

                if (reply) {
                        ipc_kmsg_free(reply);
                }
                return IKM_NULL;
        }

        if (reply) {
                replyp = reply->ikm_header->msgh_remote_port;
        }

        if (!IP_VALID(replyp)) {
                /*
                 *      Can't queue the reply message if the destination
                 *      (the reply port) isn't valid.
                 */

                ipc_kmsg_destroy(reply);

                return IKM_NULL;
        } else if (replyp->ip_receiver == ipc_space_kernel) {
                /*
                 * Don't send replies to kobject kernel ports
                 */
#if DEVELOPMENT || DEBUG
                printf("%s: refusing to send reply to kobject %d port (id:%d)\n",
                    __func__, ip_kotype(replyp), request_msgh_id);
#endif  /* DEVELOPMENT || DEBUG */
                ipc_kmsg_destroy(reply);
                return IKM_NULL;
        }

        /* Fail the MIG call if the task exec token changed during the call */
        if (kr == KERN_SUCCESS && exec_token_changed) {
                /*
                 *      Create a new reply msg with error and destroy the old reply msg.
                 */
                ipc_kmsg_t new_reply = ipc_kmsg_alloc(reply_size);

                if (new_reply == IKM_NULL) {
                        printf("ipc_kobject_server: dropping request\n");
                        ipc_kmsg_destroy(reply);
                        return IKM_NULL;
                }
                /*
                 *      Initialize the new reply message.
                 */
                {
#define OutP_new        ((mig_reply_error_t *) new_reply->ikm_header)
#define OutP_old        ((mig_reply_error_t *) reply->ikm_header)

                        bzero((void *)OutP_new, reply_size);

                        OutP_new->NDR = OutP_old->NDR;
                        OutP_new->Head.msgh_size = sizeof(mig_reply_error_t);
                        OutP_new->Head.msgh_bits = OutP_old->Head.msgh_bits & ~MACH_MSGH_BITS_COMPLEX;
                        OutP_new->Head.msgh_remote_port = OutP_old->Head.msgh_remote_port;
                        OutP_new->Head.msgh_local_port = MACH_PORT_NULL;
                        OutP_new->Head.msgh_voucher_port = MACH_PORT_NULL;
                        OutP_new->Head.msgh_id = OutP_old->Head.msgh_id;

                        /* Set the error as KERN_INVALID_TASK */
                        OutP_new->RetCode = KERN_INVALID_TASK;

#undef  OutP_new
#undef  OutP_old
                }

                /*
                 *      Destroy everything in reply except the reply port right,
                 *      which is needed in the new reply message.
                 */
                reply->ikm_header->msgh_remote_port = MACH_PORT_NULL;
                ipc_kmsg_destroy(reply);

                reply = new_reply;
        }

        trailer = (mach_msg_format_0_trailer_t *)
            ((vm_offset_t)reply->ikm_header + (int)reply->ikm_header->msgh_size);

        trailer->msgh_sender = KERNEL_SECURITY_TOKEN;
        trailer->msgh_trailer_type = MACH_MSG_TRAILER_FORMAT_0;
        trailer->msgh_trailer_size = MACH_MSG_TRAILER_MINIMUM_SIZE;

        return reply;
}

/*
 *      Routine:        ipc_kobject_set
 *      Purpose:
 *              Make a port represent a kernel object of the given type.
 *              The caller is responsible for handling refs for the
 *              kernel object, if necessary.
 *      Conditions:
 *              Nothing locked.  The port must be active if setting
 *              a kobject linkage.  Clearing a linkage is OK on an
 *              inactive port.
 */
void
ipc_kobject_set(
        ipc_port_t                      port,
        ipc_kobject_t           kobject,
        ipc_kobject_type_t      type)
{
        ip_lock(port);
        ipc_kobject_set_atomically(port, kobject, type);
        ip_unlock(port);
}

void
ipc_kobject_set_atomically(
        ipc_port_t                      port,
        ipc_kobject_t           kobject,
        ipc_kobject_type_t      type)
{
        assert(type == IKOT_NONE || ip_active(port));
#if     MACH_ASSERT
        port->ip_spares[2] = (port->ip_object.io_bits & IO_BITS_KOTYPE);
#endif  /* MACH_ASSERT */
        port->ip_object.io_bits = (port->ip_object.io_bits & ~IO_BITS_KOTYPE) | type;
        port->ip_kobject = kobject;
        if (type != IKOT_NONE) {
                /* Once set, this bit can never be unset */
                port->ip_object.io_bits |= IO_BITS_KOBJECT;
        }
}

/*
 *      Routine:        ipc_kobject_alloc_port
 *      Purpose:
 *              Allocate a kobject port in the kernel space of the specified type.
 *
 *              This function never fails.
 *
 *      Conditions:
 *              No locks held (memory is allocated)
 */
ipc_port_t
ipc_kobject_alloc_port(
        ipc_kobject_t           kobject,
        ipc_kobject_type_t      type,
        ipc_kobject_alloc_options_t     options)
{
        ipc_port_init_flags_t flags;
        ipc_space_t space;
        ipc_port_t port;

        if (options & IPC_KOBJECT_ALLOC_IN_TRANSIT) {
                /* kobject port intended to be copied out to user-space */
                flags = IPC_PORT_INIT_MESSAGE_QUEUE;
                space = IS_NULL;
        } else {
                /* true kernel-bound kobject port */
                flags = IPC_PORT_INIT_NONE;
                space = ipc_space_kernel;
        }
        port = ipc_port_alloc_special(space, flags);
        if (port == IP_NULL) {
                panic("ipc_kobject_alloc_port(): failed to allocate port");
        }

        ipc_kobject_set_atomically(port, kobject, type);

        if (options & IPC_KOBJECT_ALLOC_MAKE_SEND) {
                ipc_port_make_send_locked(port);
        }

        if (options & IPC_KOBJECT_ALLOC_IN_TRANSIT) {
                /* reset the port like it has been copied in circularity checked */
                if (options & IPC_KOBJECT_ALLOC_NSREQUEST) {
                        panic("ipc_kobject_alloc_port(): invalid option for user-space port");
                }
                port->ip_mscount = 0;
                assert(port->ip_tempowner == 0);
                assert(port->ip_receiver == IS_NULL);
                port->ip_receiver = IS_NULL;
                port->ip_receiver_name = MACH_PORT_NULL;
        } else {
                if (options & IPC_KOBJECT_ALLOC_NSREQUEST) {
                        ipc_port_make_sonce_locked(port);
                        port->ip_nsrequest = port;
                }
        }
        if (options & IPC_KOBJECT_ALLOC_IMMOVABLE_SEND) {
                port->ip_immovable_send = 1;
        }
        if (options & IPC_KOBJECT_ALLOC_NO_GRANT) {
                port->ip_no_grant = 1;
        }

        return port;
}

/*
 *      Routine:        ipc_kobject_make_send_lazy_alloc_port
 *      Purpose:
 *              Make a send once for a kobject port.
 *
 *              A location owning this port is passed in port_store.
 *              If no port exists, a port is made lazily.
 *
 *              A send right is made for the port, and if this is the first one
 *              (possibly not for the first time), then the no-more-senders
 *              notification is rearmed.
 *
 *              When a notification is armed, the kobject must donate
 *              one of its references to the port. It is expected
 *              the no-more-senders notification will consume this reference.
 *
 *      Returns:
 *              TRUE if a notification was armed
 *              FALSE else
 *
 *      Conditions:
 *              Nothing is locked, memory can be allocated.
 *              The caller must be able to donate a kobject reference to the port.
 */
boolean_t
ipc_kobject_make_send_lazy_alloc_port(
        ipc_port_t              *port_store,
        ipc_kobject_t           kobject,
        ipc_kobject_type_t      type)
{
        ipc_port_t port, previous;
        boolean_t rc = FALSE;

        port = os_atomic_load(port_store, dependency);

        if (!IP_VALID(port)) {
                port = ipc_kobject_alloc_port(kobject, type,
                    IPC_KOBJECT_ALLOC_MAKE_SEND | IPC_KOBJECT_ALLOC_NSREQUEST);
                if (os_atomic_cmpxchgv(port_store, IP_NULL, port, &previous, release)) {
                        return TRUE;
                }

                // undo what ipc_kobject_alloc_port() did above
                port->ip_nsrequest = IP_NULL;
                port->ip_mscount = 0;
                port->ip_sorights = 0;
                port->ip_srights = 0;
                ip_release(port);
                ip_release(port);
                ipc_port_dealloc_kernel(port);

                port = previous;
        }

        ip_lock(port);
        ipc_port_make_send_locked(port);
        if (port->ip_srights == 1) {
                ipc_port_make_sonce_locked(port);
                assert(port->ip_nsrequest == IP_NULL);
                port->ip_nsrequest = port;
                rc = TRUE;
        }
        ip_unlock(port);

        return rc;
}

/*
 *      Routine:        ipc_kobject_destroy
 *      Purpose:
 *              Release any kernel object resources associated
 *              with the port, which is being destroyed.
 *
 *              This should only be needed when resources are
 *              associated with a user's port.  In the normal case,
 *              when the kernel is the receiver, the code calling
 *              ipc_port_dealloc_kernel should clean up the resources.
 *      Conditions:
 *              The port is not locked, but it is dead.
 */

void
ipc_kobject_destroy(
        ipc_port_t              port)
{
        switch (ip_kotype(port)) {
        case IKOT_TIMER:
                mk_timer_port_destroy(port);
                break;

        case IKOT_NAMED_ENTRY:
                mach_destroy_memory_entry(port);
                break;

        case IKOT_HOST_NOTIFY:
                host_notify_port_destroy(port);
                break;

        default:
                break;
        }
}


boolean_t
ipc_kobject_notify(
        mach_msg_header_t *request_header,
        mach_msg_header_t *reply_header)
{
        mach_msg_max_trailer_t * trailer;
        ipc_port_t port = request_header->msgh_remote_port;

        ((mig_reply_error_t *) reply_header)->RetCode = MIG_NO_REPLY;

        trailer = (mach_msg_max_trailer_t *)
            ((vm_offset_t)request_header + request_header->msgh_size);

        /*
         * The kobject notification is privileged and can change the
         * refcount on kernel-internal objects - make sure
         * that the message wasn't faked!
         */
        if (0 != bcmp(&trailer->msgh_audit, &KERNEL_AUDIT_TOKEN,
            sizeof(trailer->msgh_audit))) {
                return FALSE;
        }
        if (0 != bcmp(&trailer->msgh_sender, &KERNEL_SECURITY_TOKEN,
            sizeof(trailer->msgh_sender))) {
                return FALSE;
        }

        switch (request_header->msgh_id) {
        case MACH_NOTIFY_NO_SENDERS:
                switch (ip_kotype(port)) {
                case IKOT_VOUCHER:
                        ipc_voucher_notify(request_header);
                        return TRUE;

                case IKOT_VOUCHER_ATTR_CONTROL:
                        ipc_voucher_attr_control_notify(request_header);
                        return TRUE;

                case IKOT_SEMAPHORE:
                        semaphore_notify(request_header);
                        return TRUE;

                case IKOT_TASK:
                        task_port_notify(request_header);
                        return TRUE;

                case IKOT_NAMED_ENTRY:
                        ip_lock(port);

                        /*
                         * Bring the sequence number and mscount in
                         * line with ipc_port_destroy assertion.
                         */
                        port->ip_mscount = 0;
                        port->ip_messages.imq_seqno = 0;
                        ipc_port_destroy(port);         /* releases lock */
                        return TRUE;

                case IKOT_UPL:
                        upl_no_senders(
                                request_header->msgh_remote_port,
                                (mach_port_mscount_t)
                                ((mach_no_senders_notification_t *)
                                request_header)->not_count);
                        reply_header->msgh_remote_port = MACH_PORT_NULL;
                        return TRUE;

#if     CONFIG_AUDIT
                case IKOT_AU_SESSIONPORT:
                        audit_session_nosenders(request_header);
                        return TRUE;
#endif
                case IKOT_FILEPORT:
                        fileport_notify(request_header);
                        return TRUE;

                case IKOT_WORK_INTERVAL:
                        work_interval_port_notify(request_header);
                        return TRUE;
                }
                break;

        case MACH_NOTIFY_PORT_DELETED:
        case MACH_NOTIFY_PORT_DESTROYED:
        case MACH_NOTIFY_SEND_ONCE:
        case MACH_NOTIFY_DEAD_NAME:
                break;

        default:
                return FALSE;
        }
        switch (ip_kotype(port)) {
#ifdef IOKIT
        case IKOT_IOKIT_OBJECT:
        case IKOT_IOKIT_CONNECT:
        case IKOT_IOKIT_IDENT:
        case IKOT_UEXT_OBJECT:
        {
                return iokit_notify(request_header);
        }
#endif
        case IKOT_TASK_RESUME:
        {
                return task_suspension_notify(request_header);
        }

        default:
                return FALSE;
        }
}