osfmk/ipc/mach_msg.c

   1 /*
   2  * Copyright (c) 2000-2007 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  * @OSF_COPYRIGHT@
  30  */
  31 /*
  32  * Mach Operating System
  33  * Copyright (c) 1991,1990,1989 Carnegie Mellon University
  34  * All Rights Reserved.
  35  *
  36  * Permission to use, copy, modify and distribute this software and its
  37  * documentation is hereby granted, provided that both the copyright
  38  * notice and this permission notice appear in all copies of the
  39  * software, derivative works or modified versions, and any portions
  40  * thereof, and that both notices appear in supporting documentation.
  41  *
  42  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  43  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  44  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  45  *
  46  * Carnegie Mellon requests users of this software to return to
  47  *
  48  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  49  *  School of Computer Science
  50  *  Carnegie Mellon University
  51  *  Pittsburgh PA 15213-3890
  52  *
  53  * any improvements or extensions that they make and grant Carnegie Mellon
  54  * the rights to redistribute these changes.
  55  */
  56 /*
  57  * NOTICE: This file was modified by McAfee Research in 2004 to introduce
  58  * support for mandatory and extensible security protections.  This notice
  59  * is included in support of clause 2.2 (b) of the Apple Public License,
  60  * Version 2.0.
  61  * Copyright (c) 2005 SPARTA, Inc.
  62  */
  63 /*
  64  */
  65 /*
  66  *      File:   ipc/mach_msg.c
  67  *      Author: Rich Draves
  68  *      Date:   1989
  69  *
  70  *      Exported message traps.  See mach/message.h.
  71  */
  72
  73 #include <mach/mach_types.h>
  74 #include <mach/kern_return.h>
  75 #include <mach/port.h>
  76 #include <mach/message.h>
  77 #include <mach/mig_errors.h>
  78 #include <mach/mach_traps.h>
  79
  80 #include <kern/kern_types.h>
  81 #include <kern/assert.h>
  82 #include <kern/counters.h>
  83 #include <kern/cpu_number.h>
  84 #include <kern/ipc_kobject.h>
  85 #include <kern/ipc_mig.h>
  86 #include <kern/task.h>
  87 #include <kern/thread.h>
  88 #include <kern/sched_prim.h>
  89 #include <kern/exception.h>
  90 #include <kern/misc_protos.h>
  91 #include <kern/kalloc.h>
  92 #include <kern/processor.h>
  93 #include <kern/syscall_subr.h>
  94
  95 #include <vm/vm_map.h>
  96
  97 #include <ipc/ipc_types.h>
  98 #include <ipc/ipc_kmsg.h>
  99 #include <ipc/ipc_mqueue.h>
 100 #include <ipc/ipc_object.h>
 101 #include <ipc/ipc_notify.h>
 102 #include <ipc/ipc_port.h>
 103 #include <ipc/ipc_pset.h>
 104 #include <ipc/ipc_space.h>
 105 #include <ipc/ipc_entry.h>
 106 #include <ipc/ipc_importance.h>
 107 #include <ipc/ipc_voucher.h>
 108
 109 #include <machine/machine_routines.h>
 110 #include <security/mac_mach_internal.h>
 111
 112 #include <sys/kdebug.h>
 113
 114 #ifndef offsetof
 115 #define offsetof(type, member)  ((size_t)(&((type *)0)->member))
 116 #endif /* offsetof */
 117
 118 /*
 119  * Forward declarations - kernel internal routines
 120  */
 121
 122 mach_msg_return_t mach_msg_send(
 123         mach_msg_header_t       *msg,
 124         mach_msg_option_t       option,
 125         mach_msg_size_t         send_size,
 126         mach_msg_timeout_t      send_timeout,
 127         mach_port_name_t        notify);
 128
 129 mach_msg_return_t mach_msg_receive(
 130         mach_msg_header_t       *msg,
 131         mach_msg_option_t       option,
 132         mach_msg_size_t         rcv_size,
 133         mach_port_name_t        rcv_name,
 134         mach_msg_timeout_t      rcv_timeout,
 135         void                    (*continuation)(mach_msg_return_t),
 136         mach_msg_size_t         slist_size);
 137
 138
 139 mach_msg_return_t msg_receive_error(
 140         ipc_kmsg_t              kmsg,
 141         mach_vm_address_t       msg_addr,
 142         mach_msg_option_t       option,
 143         mach_port_seqno_t       seqno,
 144         ipc_space_t             space);
 145
 146 security_token_t KERNEL_SECURITY_TOKEN = KERNEL_SECURITY_TOKEN_VALUE;
 147 audit_token_t KERNEL_AUDIT_TOKEN = KERNEL_AUDIT_TOKEN_VALUE;
 148
 149 mach_msg_format_0_trailer_t trailer_template = {
 150         /* mach_msg_trailer_type_t */ MACH_MSG_TRAILER_FORMAT_0,
 151         /* mach_msg_trailer_size_t */ MACH_MSG_TRAILER_MINIMUM_SIZE,
 152         /* mach_port_seqno_t */       0,
 153         /* security_token_t */        KERNEL_SECURITY_TOKEN_VALUE
 154 };
 155
 156 /*
 157  *      Routine:        mach_msg_send [Kernel Internal]
 158  *      Purpose:
 159  *              Routine for kernel-task threads to send a message.
 160  *
 161  *              Unlike mach_msg_send_from_kernel(), this routine
 162  *              looks port names up in the kernel's port namespace
 163  *              and copies in the kernel virtual memory (instead
 164  *              of taking a vm_map_copy_t pointer for OOL descriptors).
 165  *      Conditions:
 166  *              Nothing locked.
 167  *      Returns:
 168  *              MACH_MSG_SUCCESS        Sent the message.
 169  *              MACH_SEND_MSG_TOO_SMALL Message smaller than a header.
 170  *              MACH_SEND_NO_BUFFER     Couldn't allocate buffer.
 171  *              MACH_SEND_INVALID_DATA  Couldn't copy message data.
 172  *              MACH_SEND_INVALID_HEADER
 173  *                      Illegal value in the message header bits.
 174  *              MACH_SEND_INVALID_DEST  The space is dead.
 175  *              MACH_SEND_INVALID_NOTIFY        Bad notify port.
 176  *              MACH_SEND_INVALID_DEST  Can't copyin destination port.
 177  *              MACH_SEND_INVALID_REPLY Can't copyin reply port.
 178  *              MACH_SEND_TIMED_OUT     Timeout expired without delivery.
 179  *              MACH_SEND_INTERRUPTED   Delivery interrupted.
 180  */
 181
 182 mach_msg_return_t
 183 mach_msg_send(
 184         mach_msg_header_t       *msg,
 185         mach_msg_option_t       option,
 186         mach_msg_size_t         send_size,
 187         mach_msg_timeout_t      send_timeout,
 188         __unused mach_port_name_t       notify)
 189 {
 190         ipc_space_t space = current_space();
 191         vm_map_t map = current_map();
 192         ipc_kmsg_t kmsg;
 193         mach_msg_return_t mr;
 194         mach_msg_size_t msg_and_trailer_size;
 195         mach_msg_max_trailer_t  *trailer;
 196
 197         if ((send_size < sizeof(mach_msg_header_t)) || (send_size & 3))
 198                 return MACH_SEND_MSG_TOO_SMALL;
 199
 200         if (send_size > MACH_MSG_SIZE_MAX - MAX_TRAILER_SIZE)
 201                 return MACH_SEND_TOO_LARGE;
 202
 203         msg_and_trailer_size = send_size + MAX_TRAILER_SIZE;
 204
 205         kmsg = ipc_kmsg_alloc(msg_and_trailer_size);
 206
 207         if (kmsg == IKM_NULL)
 208                 return MACH_SEND_NO_BUFFER;
 209
 210         (void) memcpy((void *) kmsg->ikm_header, (const void *) msg, send_size);
 211
 212         kmsg->ikm_header->msgh_size = send_size;
 213
 214         /*
 215          * reserve for the trailer the largest space (MAX_TRAILER_SIZE)
 216          * However, the internal size field of the trailer (msgh_trailer_size)
 217          * is initialized to the minimum (sizeof(mach_msg_trailer_t)), to optimize
 218          * the cases where no implicit data is requested.
 219          */
 220         trailer = (mach_msg_max_trailer_t *) ((vm_offset_t)kmsg->ikm_header + send_size);
 221         trailer->msgh_sender = current_thread()->task->sec_token;
 222         trailer->msgh_audit = current_thread()->task->audit_token;
 223         trailer->msgh_trailer_type = MACH_MSG_TRAILER_FORMAT_0;
 224         trailer->msgh_trailer_size = MACH_MSG_TRAILER_MINIMUM_SIZE;
 225
 226         mr = ipc_kmsg_copyin(kmsg, space, map, &option);
 227
 228         if (mr != MACH_MSG_SUCCESS) {
 229                 ipc_kmsg_free(kmsg);
 230                 return mr;
 231         }
 232
 233         mr = ipc_kmsg_send(kmsg, option, send_timeout);
 234
 235         if (mr != MACH_MSG_SUCCESS) {
 236             mr |= ipc_kmsg_copyout_pseudo(kmsg, space, map, MACH_MSG_BODY_NULL);
 237             (void) memcpy((void *) msg, (const void *) kmsg->ikm_header,
 238                           kmsg->ikm_header->msgh_size);
 239             ipc_kmsg_free(kmsg);
 240         }
 241
 242         return mr;
 243 }
 244
 245 /*
 246  * message header as seen at user-space
 247  * (for MACH_RCV_LARGE/IDENTITY updating)
 248  */
 249 typedef struct
 250 {
 251   mach_msg_bits_t       msgh_bits;
 252   mach_msg_size_t       msgh_size;
 253   mach_port_name_t      msgh_remote_port;
 254   mach_port_name_t      msgh_local_port;
 255   mach_msg_size_t       msgh_reserved;
 256   mach_msg_id_t         msgh_id;
 257 } mach_msg_user_header_t;
 258
 259 /*
 260  *      Routine:        mach_msg_receive_results
 261  *      Purpose:
 262  *              Receive a message.
 263  *      Conditions:
 264  *              Nothing locked.
 265  *      Returns:
 266  *              MACH_MSG_SUCCESS        Received a message.
 267  *              MACH_RCV_INVALID_NAME   The name doesn't denote a right,
 268  *                      or the denoted right is not receive or port set.
 269  *              MACH_RCV_IN_SET         Receive right is a member of a set.
 270  *              MACH_RCV_TOO_LARGE      Message wouldn't fit into buffer.
 271  *              MACH_RCV_TIMED_OUT      Timeout expired without a message.
 272  *              MACH_RCV_INTERRUPTED    Reception interrupted.
 273  *              MACH_RCV_PORT_DIED      Port/set died while receiving.
 274  *              MACH_RCV_PORT_CHANGED   Port moved into set while receiving.
 275  *              MACH_RCV_INVALID_DATA   Couldn't copy to user buffer.
 276  *              MACH_RCV_INVALID_NOTIFY Bad notify port.
 277  *              MACH_RCV_HEADER_ERROR
 278  */
 279
 280 mach_msg_return_t
 281 mach_msg_receive_results(void)
 282 {
 283         thread_t          self = current_thread();
 284         ipc_space_t       space = current_space();
 285         vm_map_t          map = current_map();
 286
 287         ipc_object_t      object = self->ith_object;
 288         mach_msg_return_t mr = self->ith_state;
 289         mach_vm_address_t msg_addr = self->ith_msg_addr;
 290         mach_msg_option_t option = self->ith_option;
 291         ipc_kmsg_t        kmsg = self->ith_kmsg;
 292         mach_port_seqno_t seqno = self->ith_seqno;
 293         mach_msg_trailer_size_t trailer_size;
 294
 295         io_release(object);
 296
 297         if (mr != MACH_MSG_SUCCESS) {
 298
 299           if (mr == MACH_RCV_TOO_LARGE ) {
 300             if (option & MACH_RCV_LARGE) {
 301               /*
 302                * We need to inform the user-level code that it needs more
 303                * space.  The value for how much space was returned in the
 304                * msize save area instead of the message (which was left on
 305                * the queue).
 306                */
 307               if (option & MACH_RCV_LARGE_IDENTITY) {
 308                       if (copyout((char *) &self->ith_receiver_name,
 309                                   msg_addr + offsetof(mach_msg_user_header_t, msgh_local_port),
 310                                   sizeof(mach_port_name_t)))
 311                               mr = MACH_RCV_INVALID_DATA;
 312               }
 313               if (copyout((char *) &self->ith_msize,
 314                           msg_addr + offsetof(mach_msg_user_header_t, msgh_size),
 315                           sizeof(mach_msg_size_t)))
 316                 mr = MACH_RCV_INVALID_DATA;
 317             } else {
 318
 319                 /* discard importance in message */
 320                 ipc_importance_clean(kmsg);
 321
 322                 if (msg_receive_error(kmsg, msg_addr, option, seqno, space)
 323                     == MACH_RCV_INVALID_DATA)
 324                     mr = MACH_RCV_INVALID_DATA;
 325             }
 326           }
 327           return mr;
 328         }
 329
 330 #if IMPORTANCE_INHERITANCE
 331
 332         /* adopt/transform any importance attributes carried in the message */
 333         ipc_importance_receive(kmsg, option);
 334
 335 #endif  /* IMPORTANCE_INHERITANCE */
 336
 337         /* auto redeem the voucher in the message */
 338         ipc_voucher_receive_postprocessing(kmsg, option);
 339
 340         trailer_size = ipc_kmsg_add_trailer(kmsg, space, option, self, seqno, FALSE,
 341                         kmsg->ikm_header->msgh_remote_port->ip_context);
 342         mr = ipc_kmsg_copyout(kmsg, space, map, MACH_MSG_BODY_NULL, option);
 343
 344         if (mr != MACH_MSG_SUCCESS) {
 345                 /* already received importance, so have to undo that here */
 346                 ipc_importance_unreceive(kmsg, option);
 347
 348                 if ((mr &~ MACH_MSG_MASK) == MACH_RCV_BODY_ERROR) {
 349                         if (ipc_kmsg_put(msg_addr, kmsg, kmsg->ikm_header->msgh_size +
 350                            trailer_size) == MACH_RCV_INVALID_DATA)
 351                                 mr = MACH_RCV_INVALID_DATA;
 352                 }
 353                 else {
 354                         if (msg_receive_error(kmsg, msg_addr, option, seqno, space)
 355                                                 == MACH_RCV_INVALID_DATA)
 356                                 mr = MACH_RCV_INVALID_DATA;
 357                 }
 358         } else {
 359                 mr = ipc_kmsg_put(msg_addr,
 360                                   kmsg,
 361                                   kmsg->ikm_header->msgh_size +
 362                                   trailer_size);
 363         }
 364
 365         return mr;
 366 }
 367
 368 /*
 369  *      Routine:        mach_msg_receive [Kernel Internal]
 370  *      Purpose:
 371  *              Routine for kernel-task threads to actively receive a message.
 372  *
 373  *              Unlike being dispatched to by ipc_kobject_server() or the
 374  *              reply part of mach_msg_rpc_from_kernel(), this routine
 375  *              looks up the receive port name in the kernel's port
 376  *              namespace and copies out received port rights to that namespace
 377  *              as well.  Out-of-line memory is copied out the kernel's
 378  *              address space (rather than just providing the vm_map_copy_t).
 379  *      Conditions:
 380  *              Nothing locked.
 381  *      Returns:
 382  *              MACH_MSG_SUCCESS        Received a message.
 383  *              See <mach/message.h> for list of MACH_RCV_XXX errors.
 384  */
 385 mach_msg_return_t
 386 mach_msg_receive(
 387         mach_msg_header_t       *msg,
 388         mach_msg_option_t       option,
 389         mach_msg_size_t         rcv_size,
 390         mach_port_name_t        rcv_name,
 391         mach_msg_timeout_t      rcv_timeout,
 392         void                    (*continuation)(mach_msg_return_t),
 393         __unused mach_msg_size_t slist_size)
 394 {
 395         thread_t self = current_thread();
 396         ipc_space_t space = current_space();
 397         ipc_object_t object;
 398         ipc_mqueue_t mqueue;
 399         mach_msg_return_t mr;
 400
 401         mr = ipc_mqueue_copyin(space, rcv_name, &mqueue, &object);
 402         if (mr != MACH_MSG_SUCCESS) {
 403                 return mr;
 404         }
 405         /* hold ref for object */
 406
 407         self->ith_msg_addr = CAST_DOWN(mach_vm_address_t, msg);
 408         self->ith_object = object;
 409         self->ith_msize = rcv_size;
 410         self->ith_option = option;
 411         self->ith_continuation = continuation;
 412
 413         ipc_mqueue_receive(mqueue, option, rcv_size, rcv_timeout, THREAD_ABORTSAFE);
 414         if ((option & MACH_RCV_TIMEOUT) && rcv_timeout == 0)
 415                 thread_poll_yield(self);
 416         return mach_msg_receive_results();
 417 }
 418
 419 void
 420 mach_msg_receive_continue(void)
 421 {
 422         thread_t self = current_thread();
 423
 424         (*self->ith_continuation)(mach_msg_receive_results());
 425 }
 426
 427
 428 /*
 429  *      Routine:        mach_msg_overwrite_trap [mach trap]
 430  *      Purpose:
 431  *              Possibly send a message; possibly receive a message.
 432  *      Conditions:
 433  *              Nothing locked.
 434  *      Returns:
 435  *              All of mach_msg_send and mach_msg_receive error codes.
 436  */
 437
 438 mach_msg_return_t
 439 mach_msg_overwrite_trap(
 440         struct mach_msg_overwrite_trap_args *args)
 441 {
 442         mach_vm_address_t       msg_addr = args->msg;
 443         mach_msg_option_t       option = args->option;
 444         mach_msg_size_t         send_size = args->send_size;
 445         mach_msg_size_t         rcv_size = args->rcv_size;
 446         mach_port_name_t        rcv_name = args->rcv_name;
 447         mach_msg_timeout_t      msg_timeout = args->timeout;
 448         __unused mach_port_name_t notify = args->notify;
 449         mach_vm_address_t       rcv_msg_addr = args->rcv_msg;
 450         __unused mach_port_seqno_t temp_seqno = 0;
 451
 452         mach_msg_return_t  mr = MACH_MSG_SUCCESS;
 453         vm_map_t map = current_map();
 454
 455         /* Only accept options allowed by the user */
 456         option &= MACH_MSG_OPTION_USER;
 457
 458         if (option & MACH_SEND_MSG) {
 459                 ipc_space_t space = current_space();
 460                 ipc_kmsg_t kmsg;
 461
 462                 mr = ipc_kmsg_get(msg_addr, send_size, &kmsg);
 463
 464                 if (mr != MACH_MSG_SUCCESS)
 465                         return mr;
 466
 467                 mr = ipc_kmsg_copyin(kmsg, space, map, &option);
 468
 469                 if (mr != MACH_MSG_SUCCESS) {
 470                         ipc_kmsg_free(kmsg);
 471                         return mr;
 472                 }
 473
 474                 mr = ipc_kmsg_send(kmsg, option, msg_timeout);
 475
 476                 if (mr != MACH_MSG_SUCCESS) {
 477                         mr |= ipc_kmsg_copyout_pseudo(kmsg, space, map, MACH_MSG_BODY_NULL);
 478                         (void) ipc_kmsg_put(msg_addr, kmsg, kmsg->ikm_header->msgh_size);
 479                         return mr;
 480                 }
 481
 482         }
 483
 484         if (option & MACH_RCV_MSG) {
 485                 thread_t self = current_thread();
 486                 ipc_space_t space = current_space();
 487                 ipc_object_t object;
 488                 ipc_mqueue_t mqueue;
 489
 490                 mr = ipc_mqueue_copyin(space, rcv_name, &mqueue, &object);
 491                 if (mr != MACH_MSG_SUCCESS) {
 492                         return mr;
 493                 }
 494                 /* hold ref for object */
 495
 496                 if (rcv_msg_addr != (mach_vm_address_t)0)
 497                         self->ith_msg_addr = rcv_msg_addr;
 498                 else
 499                         self->ith_msg_addr = msg_addr;
 500                 self->ith_object = object;
 501                 self->ith_msize = rcv_size;
 502                 self->ith_option = option;
 503                 self->ith_receiver_name = MACH_PORT_NULL;
 504                 self->ith_continuation = thread_syscall_return;
 505
 506                 ipc_mqueue_receive(mqueue, option, rcv_size, msg_timeout, THREAD_ABORTSAFE);
 507                 if ((option & MACH_RCV_TIMEOUT) && msg_timeout == 0)
 508                         thread_poll_yield(self);
 509                 return mach_msg_receive_results();
 510         }
 511
 512         return MACH_MSG_SUCCESS;
 513 }
 514
 515 /*
 516  *      Routine:        mach_msg_trap [mach trap]
 517  *      Purpose:
 518  *              Possibly send a message; possibly receive a message.
 519  *      Conditions:
 520  *              Nothing locked.
 521  *      Returns:
 522  *              All of mach_msg_send and mach_msg_receive error codes.
 523  */
 524
 525 mach_msg_return_t
 526 mach_msg_trap(
 527         struct mach_msg_overwrite_trap_args *args)
 528 {
 529         kern_return_t kr;
 530         args->rcv_msg = (mach_vm_address_t)0;
 531
 532         kr = mach_msg_overwrite_trap(args);
 533         return kr;
 534 }
 535
 536
 537 /*
 538  *      Routine:        msg_receive_error       [internal]
 539  *      Purpose:
 540  *              Builds a minimal header/trailer and copies it to
 541  *              the user message buffer.  Invoked when in the case of a
 542  *              MACH_RCV_TOO_LARGE or MACH_RCV_BODY_ERROR error.
 543  *      Conditions:
 544  *              Nothing locked.
 545  *      Returns:
 546  *              MACH_MSG_SUCCESS        minimal header/trailer copied
 547  *              MACH_RCV_INVALID_DATA   copyout to user buffer failed
 548  */
 549
 550 mach_msg_return_t
 551 msg_receive_error(
 552         ipc_kmsg_t              kmsg,
 553         mach_vm_address_t       msg_addr,
 554         mach_msg_option_t       option,
 555         mach_port_seqno_t       seqno,
 556         ipc_space_t             space)
 557 {
 558         mach_vm_address_t       context;
 559         mach_msg_trailer_size_t trailer_size;
 560         mach_msg_max_trailer_t  *trailer;
 561
 562         context = kmsg->ikm_header->msgh_remote_port->ip_context;
 563
 564         /*
 565          * Copy out the destination port in the message.
 566          * Destroy all other rights and memory in the message.
 567          */
 568         ipc_kmsg_copyout_dest(kmsg, space);
 569
 570         /*
 571          * Build a minimal message with the requested trailer.
 572          */
 573         trailer = (mach_msg_max_trailer_t *)
 574                         ((vm_offset_t)kmsg->ikm_header +
 575                         round_msg(sizeof(mach_msg_header_t)));
 576         kmsg->ikm_header->msgh_size = sizeof(mach_msg_header_t);
 577         bcopy(  (char *)&trailer_template,
 578                 (char *)trailer,
 579                 sizeof(trailer_template));
 580
 581         trailer_size = ipc_kmsg_add_trailer(kmsg, space,
 582                         option, current_thread(), seqno,
 583                         TRUE, context);
 584
 585         /*
 586          * Copy the message to user space
 587          */
 588         if (ipc_kmsg_put(msg_addr, kmsg, kmsg->ikm_header->msgh_size +
 589                         trailer_size) == MACH_RCV_INVALID_DATA)
 590                 return(MACH_RCV_INVALID_DATA);
 591         else
 592                 return(MACH_MSG_SUCCESS);
 593 }