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 [email protected]
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/cpu_number.h>
83 #include <kern/ipc_kobject.h>
84 #include <kern/ipc_mig.h>
85 #include <kern/task.h>
86 #include <kern/thread.h>
87 #include <kern/sched_prim.h>
88 #include <kern/exception.h>
89 #include <kern/misc_protos.h>
90 #include <kern/processor.h>
91 #include <kern/syscall_subr.h>
92 #include <kern/policy_internal.h>
93 #include <kern/mach_filter.h>
94
95 #include <vm/vm_map_xnu.h>
96
97 #include <ipc/port.h>
98 #include <ipc/ipc_types.h>
99 #include <ipc/ipc_kmsg.h>
100 #include <ipc/ipc_mqueue.h>
101 #include <ipc/ipc_object.h>
102 #include <ipc/ipc_notify.h>
103 #include <ipc/ipc_policy.h>
104 #include <ipc/ipc_port.h>
105 #include <ipc/ipc_pset.h>
106 #include <ipc/ipc_space.h>
107 #include <ipc/ipc_entry.h>
108 #include <ipc/ipc_importance.h>
109 #include <ipc/ipc_voucher.h>
110
111 #include <machine/machine_routines.h>
112 #include <security/mac_mach_internal.h>
113
114 #include <sys/kdebug.h>
115 #include <sys/proc_ro.h>
116
117 #ifndef offsetof
118 #define offsetof(type, member) ((size_t)(&((type *)0)->member))
119 #endif /* offsetof */
120
121 /*
122 * Forward declarations - kernel internal routines
123 */
124
125 static mach_msg_return_t
126 mach_msg_rcv_link_special_reply_port(
127 ipc_port_t special_reply_port,
128 mach_port_name_t dest_name_port);
129
130 void
131 mach_msg_receive_results_complete(ipc_object_t object);
132
133 const security_token_t KERNEL_SECURITY_TOKEN = KERNEL_SECURITY_TOKEN_VALUE;
134 const audit_token_t KERNEL_AUDIT_TOKEN = KERNEL_AUDIT_TOKEN_VALUE;
135
136 #define mach_copyout_field(kaddr, uaddr, type_t, field) \
137 mach_copyout((kaddr), (uaddr) + offsetof(type_t, field), \
138 sizeof(((type_t *)0)->field))
139
140 /*
141 * Routine: mach_msg_receive_too_large()
142 * Purpose:
143 * Helper for mach_msg_receive_results() to handle
144 * the MACH_RCV_TOO_LARGE error when the MACH64_RCV_LARGE
145 * option is set.
146 * Returns:
147 * MACH_RCV_INVALID_DATA or the passed in mr.
148 */
149 static mach_msg_return_t
mach_msg_receive_too_large(mach_msg_recv_bufs_t * recv_bufs,mach_msg_recv_result_t * msgr,mach_msg_option64_t options,mach_msg_return_t mr)150 mach_msg_receive_too_large(
151 mach_msg_recv_bufs_t *recv_bufs,
152 mach_msg_recv_result_t *msgr,
153 mach_msg_option64_t options,
154 mach_msg_return_t mr)
155 {
156 assert(mr == MACH_RCV_TOO_LARGE);
157 assert(options & MACH_RCV_LARGE);
158
159 if (options & MACH64_RCV_LINEAR_VECTOR) {
160 /*
161 * If MACH64_RCV_LINEAR_VECTOR is set, kevent is calling
162 * from filt_machportprocess() and the reporting of name
163 * and sizes happen via the knote in filt_machportprocess()
164 * rather than a receive operation, there's nothing for us
165 * to do here.
166 */
167 return mr;
168 }
169
170 /*
171 * For the regular case, just copyout the size
172 * (and optional port name) in a fake header.
173 */
174 if ((options & MACH64_RCV_LARGE_IDENTITY) &&
175 recv_bufs->recv_msg_size >=
176 offsetof(mach_msg_user_header_t, msgh_voucher_port)) {
177 /*
178 * If MACH64_RCV_LARGE_IDENTITY is set,
179 * we monkey patch the msgh_local_port field.
180 */
181 if (mach_copyout_field(&msgr->msgr_recv_name,
182 recv_bufs->recv_msg_addr,
183 mach_msg_user_header_t, msgh_local_port)) {
184 mr = MACH_RCV_INVALID_DATA;
185 }
186 }
187
188 if (recv_bufs->recv_msg_size >=
189 offsetof(mach_msg_user_header_t, msgh_remote_port)) {
190 /*
191 * For all cases, we monkey patch the msgh_size
192 * field with how much size is needed.
193 */
194 if (mach_copyout_field(&msgr->msgr_msg_size,
195 recv_bufs->recv_msg_addr,
196 mach_msg_user_header_t, msgh_size)) {
197 mr = MACH_RCV_INVALID_DATA;
198 }
199 }
200
201 if (recv_bufs->recv_aux_addr) {
202 /*
203 * Then we report the incoming aux size as well,
204 * if the caller has an aux buffer.
205 */
206 assert(recv_bufs->recv_aux_size >= sizeof(mach_msg_aux_header_t));
207 if (mach_copyout_field(&msgr->msgr_aux_size,
208 recv_bufs->recv_aux_addr,
209 mach_msg_aux_header_t, msgdh_size)) {
210 mr = MACH_RCV_INVALID_DATA;
211 }
212 }
213
214 return mr;
215 }
216
217 /*
218 * Routine: mach_msg_receive_error [internal]
219 * Purpose:
220 * Builds a minimal header/trailer and copies it to
221 * the user message buffer. Invoked when in the case of a
222 * MACH_RCV_TOO_LARGE or MACH_RCV_BODY_ERROR error.
223 * Conditions:
224 * Nothing locked. kmsg is freed upon return.
225 * Returns:
226 * the incoming "mr" minimal header/trailer copied
227 * MACH_RCV_INVALID_DATA copyout to user buffer failed
228 */
229 static mach_msg_return_t
mach_msg_receive_error(ipc_kmsg_t kmsg,mach_msg_recv_bufs_t * recv_bufs,mach_msg_recv_result_t * msgr,mach_msg_option64_t options,ipc_space_t space,vm_map_t map,mach_msg_return_t mr)230 mach_msg_receive_error(
231 ipc_kmsg_t kmsg,
232 mach_msg_recv_bufs_t *recv_bufs,
233 mach_msg_recv_result_t *msgr,
234 mach_msg_option64_t options,
235 ipc_space_t space,
236 vm_map_t map,
237 mach_msg_return_t mr)
238 {
239 /*
240 * Copy out the destination port in the message.
241 *
242 * Destroy all other rights and memory in the message,
243 * and turn it into a very simple bare message with just a header.
244 */
245 ipc_kmsg_copyout_dest_to_user(kmsg, space);
246
247 /*
248 * Copy the message to user space and return the size
249 * (note that ipc_kmsg_put_to_user may also adjust the actual
250 * msg and aux size copied out to user-space).
251 */
252 return ipc_kmsg_put_to_user(kmsg, recv_bufs, msgr, options, map, mr);
253 }
254
255 /*
256 * Routine: mach_msg_receive_results
257 * Purpose:
258 * Receive a message.
259 * Conditions:
260 * Nothing locked.
261 *
262 * Returns:
263 * sizep (out): copied out size of message proper
264 * aux_sizep (out): copied out size of aux data
265 * MACH_MSG_SUCCESS Received a message.
266 * MACH_RCV_INVALID_NAME The name doesn't denote a right,
267 * or the denoted right is not receive or port set.
268 * MACH_RCV_IN_SET Receive right is a member of a set.
269 * MACH_RCV_TOO_LARGE Message wouldn't fit into buffer.
270 * MACH_RCV_TIMED_OUT Timeout expired without a message.
271 * MACH_RCV_INTERRUPTED Reception interrupted.
272 * MACH_RCV_PORT_DIED Port/set died while receiving.
273 * MACH_RCV_PORT_CHANGED Port moved into set while receiving.
274 * MACH_RCV_INVALID_DATA Couldn't copy to user buffer.
275 * MACH_RCV_INVALID_NOTIFY Bad notify port.
276 * MACH_RCV_HEADER_ERROR
277 */
278 mach_msg_return_t
mach_msg_receive_results(mach_msg_recv_result_t * msgr_out)279 mach_msg_receive_results(
280 mach_msg_recv_result_t *msgr_out)
281 {
282 thread_t self = current_thread();
283 ipc_space_t space = current_space();
284 vm_map_t map = current_map();
285
286 /*
287 * /!\IMPORTANT/!\: Pull out values we stashed on thread struct now.
288 * Values may be stomped over if copyio operations in this function
289 * trigger kernel IPC calls.
290 */
291 ipc_object_t object = self->ith_object;
292 mach_msg_return_t mr = self->ith_state;
293 mach_msg_option64_t options = self->ith_option;
294 ipc_kmsg_t kmsg = self->ith_kmsg;
295
296 mach_msg_recv_bufs_t recv_bufs = self->ith_recv_bufs;
297 mach_msg_recv_result_t msgr = {
298 .msgr_seqno = self->ith_seqno,
299 .msgr_context = 0,
300 };
301
302 /*
303 * unlink the special_reply_port before releasing reference to object.
304 * get the thread's turnstile, if the thread donated it's turnstile to the port
305 */
306 mach_msg_receive_results_complete(object);
307 io_release(object);
308
309 if (options & MACH64_RCV_LINEAR_VECTOR) {
310 assert(recv_bufs.recv_aux_addr == 0);
311 assert(recv_bufs.recv_aux_size == 0);
312 }
313
314 if (mr == MACH_RCV_TOO_LARGE) {
315 /* these ith_* fields are only set for MACH_RCV_TOO_LARGE */
316 msgr.msgr_msg_size = self->ith_msize;
317 msgr.msgr_aux_size = self->ith_asize;
318 msgr.msgr_recv_name = self->ith_receiver_name;
319
320 /*
321 * If the receive operation occurs with MACH_RCV_LARGE set
322 * then no message was extracted from the queue, and the size
323 * and (optionally) receiver names were the only thing captured.
324 */
325 if (options & MACH64_RCV_LARGE) {
326 mr = mach_msg_receive_too_large(&recv_bufs, &msgr,
327 options, mr);
328 } else {
329 /* discard importance in message */
330 ipc_importance_clean(kmsg);
331 mr = mach_msg_receive_error(kmsg, &recv_bufs, &msgr,
332 options, space, map, mr);
333 /* kmsg freed */
334 }
335 }
336 if (mr != MACH_MSG_SUCCESS) {
337 goto out;
338 }
339
340 #if IMPORTANCE_INHERITANCE
341
342 /* adopt/transform any importance attributes carried in the message */
343 ipc_importance_receive(kmsg, options);
344
345 #endif /* IMPORTANCE_INHERITANCE */
346
347 /* auto redeem the voucher in the message */
348 ipc_voucher_receive_postprocessing(kmsg, options);
349
350 /* Save destination port context for the trailer before copyout */
351 msgr.msgr_context = ikm_header(kmsg)->msgh_remote_port->ip_context;
352
353 /*
354 * restore the recv_bufs values that are used by
355 * ipc_kmsg_copyout_guarded_port_descriptor()
356 */
357 self->ith_recv_bufs = recv_bufs;
358 mr = ipc_kmsg_copyout(kmsg, space, map, options);
359
360 if (mr != MACH_MSG_SUCCESS) {
361 /* already received importance, so have to undo that here */
362 ipc_importance_unreceive(kmsg, options);
363
364 /* if we had a body error copyout what we have, otherwise a simple header/trailer */
365 if ((mr & ~MACH_MSG_MASK) == MACH_RCV_BODY_ERROR) {
366 mr = ipc_kmsg_put_to_user(kmsg, &recv_bufs, &msgr,
367 options, map, mr);
368 } else {
369 mr = mach_msg_receive_error(kmsg, &recv_bufs, &msgr,
370 options, space, map, mr);
371 }
372 } else {
373 msgr.msgr_priority = kmsg->ikm_ppriority;
374 msgr.msgr_qos_ovrd = kmsg->ikm_qos_override;
375 mr = ipc_kmsg_put_to_user(kmsg, &recv_bufs, &msgr,
376 options, map, mr);
377 }
378 /* kmsg freed */
379
380 out:
381 if (msgr_out) {
382 *msgr_out = msgr;
383 }
384 return mr;
385 }
386
387 void
mach_msg_receive_continue(void)388 mach_msg_receive_continue(void)
389 {
390 mach_msg_return_t mr;
391
392 ipc_port_thread_group_unblocked();
393
394 mr = mach_msg_receive_results(NULL);
395 thread_syscall_return(mr);
396 }
397
398 /*
399 * Routine: mach_msg_validate_data_vectors
400 * Purpose:
401 * Perform validations on message and auxiliary data vectors
402 * we have copied in.
403 */
404 static mach_msg_return_t
mach_msg_validate_data_vectors(mach_msg_vector_t * msg_vec,mach_msg_vector_t * aux_vec,mach_msg_size_t vec_count,__unused mach_msg_option64_t option64,bool sending)405 mach_msg_validate_data_vectors(
406 mach_msg_vector_t *msg_vec,
407 mach_msg_vector_t *aux_vec,
408 mach_msg_size_t vec_count,
409 __unused mach_msg_option64_t option64,
410 bool sending)
411 {
412 mach_msg_size_t msg_size = 0, aux_size = 0; /* user size */
413
414 assert(vec_count <= MACH_MSGV_MAX_COUNT);
415 assert(option64 & MACH64_MSG_VECTOR);
416
417 assert(msg_vec != NULL);
418 assert(aux_vec != NULL);
419
420 if (vec_count == 0) {
421 /*
422 * can't use MACH_RCV_TOO_LARGE or MACH_RCV_INVALID_DATA here because
423 * they imply a message has been dropped. use a new error code that
424 * suggests an early error and that message is still queued.
425 */
426 return sending ? MACH_SEND_MSG_TOO_SMALL : MACH_RCV_INVALID_ARGUMENTS;
427 }
428
429 /*
430 * Validate first (message proper) data vector.
431 *
432 * Since we are using mach_msg2_trap() to shim existing mach_msg() calls,
433 * we unfortunately cannot validate message rcv address or message rcv size
434 * at this point for compatibility reasons.
435 *
436 * (1) If rcv address is invalid, we will destroy the incoming message during
437 * ipc_kmsg_put_to_user(), instead of returning an error before receive
438 * is attempted.
439 * (2) If rcv size is smaller than the minimal message header and trailer
440 * that mach_msg_receive_error() builds, we will truncate the message
441 * and copy out a partial message.
442 *
443 * See: ipc_kmsg_put_vector_to_user().
444 */
445 if (sending) {
446 if (msg_vec->msgv_data == 0) {
447 return MACH_SEND_INVALID_DATA;
448 }
449 msg_size = msg_vec->msgv_send_size;
450 if ((msg_size < sizeof(mach_msg_user_header_t)) || (msg_size & 3)) {
451 return MACH_SEND_MSG_TOO_SMALL;
452 }
453 if (msg_size > IPC_KMSG_MAX_BODY_SPACE) {
454 return MACH_SEND_TOO_LARGE;
455 }
456 }
457
458 /* Validate second (optional auxiliary) data vector */
459 if (vec_count == MACH_MSGV_MAX_COUNT) {
460 if (sending) {
461 aux_size = aux_vec->msgv_send_size;
462 if (aux_size != 0 && aux_vec->msgv_data == 0) {
463 return MACH_SEND_INVALID_DATA;
464 }
465 if (aux_size != 0 && aux_size < sizeof(mach_msg_aux_header_t)) {
466 return MACH_SEND_AUX_TOO_SMALL;
467 }
468 if (aux_size > IPC_KMSG_MAX_AUX_DATA_SPACE) {
469 return MACH_SEND_AUX_TOO_LARGE;
470 }
471 } else {
472 mach_vm_address_t rcv_addr = aux_vec->msgv_rcv_addr ?
473 aux_vec->msgv_rcv_addr : aux_vec->msgv_data;
474
475 if (rcv_addr == 0) {
476 return MACH_RCV_INVALID_ARGUMENTS;
477 }
478 /*
479 * We are using this aux vector to receive, kernel will at
480 * least copy out an empty aux data header.
481 *
482 * See: ipc_kmsg_put_vector_to_user()
483 */
484 aux_size = aux_vec->msgv_rcv_size;
485 if (aux_size < sizeof(mach_msg_aux_header_t)) {
486 return MACH_RCV_INVALID_ARGUMENTS;
487 }
488 }
489 } else {
490 if (sending) {
491 /*
492 * Not sending aux data vector, but we still might have copied it
493 * in if doing a combined send/receive. Nil out the send size.
494 */
495 aux_vec->msgv_send_size = 0;
496 } else {
497 /* Do the same for receive */
498 aux_vec->msgv_rcv_size = 0;
499 }
500 }
501
502 return MACH_MSG_SUCCESS;
503 }
504
505 /*
506 * Routine: mach_msg_copyin_data_vectors
507 * Purpose:
508 * Copy in and message user data vectors.
509 */
510 static mach_msg_return_t
mach_msg_copyin_data_vectors(mach_vm_address_t data_addr,mach_msg_size_t cpin_count,mach_msg_option64_t option64,mach_msg_vector_t * msg_vecp,mach_msg_vector_t * aux_vecp)511 mach_msg_copyin_data_vectors(
512 mach_vm_address_t data_addr,/* user address */
513 mach_msg_size_t cpin_count,
514 mach_msg_option64_t option64,
515 mach_msg_vector_t *msg_vecp,/* out */
516 mach_msg_vector_t *aux_vecp)/* out */
517 {
518 mach_msg_vector_t data_vecs[MACH_MSGV_MAX_COUNT] = {};
519
520 static_assert(MACH_MSGV_MAX_COUNT == 2);
521 assert(option64 & MACH64_MSG_VECTOR);
522
523 if (cpin_count > MACH_MSGV_MAX_COUNT) {
524 return (option64 & MACH64_SEND_MSG) ?
525 MACH_SEND_INVALID_DATA : MACH_RCV_INVALID_ARGUMENTS;
526 }
527
528 if (cpin_count == 0) {
529 return (option64 & MACH64_SEND_MSG) ?
530 MACH_SEND_MSG_TOO_SMALL : MACH_RCV_INVALID_ARGUMENTS;
531 }
532
533 if (mach_copyin(data_addr, data_vecs,
534 cpin_count * sizeof(mach_msg_vector_t))) {
535 return (option64 & MACH64_SEND_MSG) ?
536 MACH_SEND_INVALID_DATA : MACH_RCV_INVALID_ARGUMENTS;
537 }
538
539 memcpy(msg_vecp, &data_vecs[MACH_MSGV_IDX_MSG], sizeof(mach_msg_vector_t));
540
541 if (cpin_count == MACH_MSGV_MAX_COUNT) {
542 memcpy(aux_vecp, &data_vecs[MACH_MSGV_IDX_AUX], sizeof(mach_msg_vector_t));
543 }
544
545 return MACH_MSG_SUCCESS;
546 }
547
548 #if IPC_HAS_LEGACY_MACH_MSG_TRAP
549 /*
550 * Routine: mach_msg_copyin_user_header
551 * Purpose:
552 * Copy in the message header, or up until message body if message is
553 * large enough. Returns the header of the message and number of descriptors.
554 * Used for mach_msg_overwrite_trap() only. Not available on embedded.
555 * Returns:
556 * MACH_MSG_SUCCESS - Copyin succeeded, msg_addr and msg_size are validated.
557 * MACH_SEND_MSG_TOO_SMALL
558 * MACH_SEND_TOO_LARGE
559 * MACH_SEND_INVALID_DATA
560 */
561 static mach_msg_return_t
mach_msg_copyin_user_header(mach_msg_send_uctx_t * send_uctx,mach_msg_option64_t options)562 mach_msg_copyin_user_header(
563 mach_msg_send_uctx_t *send_uctx,
564 mach_msg_option64_t options)
565 {
566 mach_msg_return_t mr = MACH_MSG_SUCCESS;
567
568 if (send_uctx->send_msg_size < sizeof(mach_msg_user_header_t) ||
569 (send_uctx->send_msg_size & 3)) {
570 return MACH_SEND_MSG_TOO_SMALL;
571 }
572
573 if (send_uctx->send_msg_size > IPC_KMSG_MAX_BODY_SPACE) {
574 return MACH_SEND_TOO_LARGE;
575 }
576
577 if (send_uctx->send_msg_size < sizeof(mach_msg_user_base_t)) {
578 static_assert(offsetof(mach_msg_send_uctx_t, send_dsc_count) ==
579 offsetof(mach_msg_user_base_t, body.msgh_descriptor_count));
580
581 mr = copyinmsg(send_uctx->send_msg_addr,
582 &send_uctx->send_header, sizeof(mach_msg_user_header_t));
583 } else {
584 mr = copyinmsg(send_uctx->send_msg_addr,
585 &send_uctx->send_header, sizeof(mach_msg_user_base_t));
586 }
587 if (mr != KERN_SUCCESS) {
588 return MACH_SEND_INVALID_DATA;
589 }
590
591 /*
592 * If the message claims to be complex, it must at least
593 * have the length of a "base" message (header + dsc_count).
594 */
595 if (send_uctx->send_header.msgh_bits & MACH_MSGH_BITS_COMPLEX) {
596 if (send_uctx->send_msg_size < sizeof(mach_msg_user_base_t)) {
597 return MACH_SEND_MSG_TOO_SMALL;
598 }
599 } else {
600 send_uctx->send_dsc_count = 0;
601 }
602 send_uctx->send_header.msgh_size = send_uctx->send_msg_size;
603
604 return ipc_policy_allow_legacy_send_trap(send_uctx->send_header.msgh_id,
605 options);
606 }
607 #endif /* IPC_HAS_LEGACY_MACH_MSG_TRAP */
608
609
610 __attribute__((noinline, cold))
611 static mach_msg_return_t
mach_msg_receive_pseudo(ipc_kmsg_t kmsg,mach_msg_send_uctx_t * send_uctx,mach_msg_option64_t options,ipc_space_t space,vm_map_t map)612 mach_msg_receive_pseudo(
613 ipc_kmsg_t kmsg,
614 mach_msg_send_uctx_t *send_uctx,
615 mach_msg_option64_t options,
616 ipc_space_t space,
617 vm_map_t map)
618 {
619 mach_msg_recv_bufs_t recv_bufs = {
620 .recv_msg_addr = send_uctx->send_msg_addr,
621 .recv_aux_addr = send_uctx->send_aux_addr,
622 .recv_msg_size = send_uctx->send_msg_size,
623 .recv_aux_size = send_uctx->send_aux_size,
624 };
625 mach_msg_recv_result_t msgr = {
626 .msgr_recv_name = MSGR_PSEUDO_RECEIVE,
627 };
628 mach_msg_return_t mr;
629
630 /*
631 * set the recv_bufs values that are used by
632 * ipc_kmsg_copyout_guarded_port_descriptor()
633 */
634 current_thread()->ith_recv_bufs = recv_bufs;
635 mr = ipc_kmsg_copyout_pseudo(kmsg, space, map);
636 (void)ipc_kmsg_put_to_user(kmsg, &recv_bufs, &msgr, options, map, mr);
637 return mr;
638 }
639
640 /*
641 * Routine: mach_msg_trap_send [internal]
642 * Purpose:
643 * Send a message.
644 * Conditions:
645 * MACH_SEND_MSG is set. aux_send_size is bound checked.
646 * send_aux_{addr, size} are 0 if not vector send.
647 * send_msg_size needs additional bound checks.
648 * Returns:
649 * All of mach_msg_send error codes.
650 */
651 static mach_msg_return_t
mach_msg_trap_send(mach_msg_send_uctx_t * send_uctx,mach_msg_option64_t options,mach_msg_timeout_t msg_timeout,mach_msg_priority_t priority)652 mach_msg_trap_send(
653 /* shared args between send and receive */
654 mach_msg_send_uctx_t *send_uctx,
655 mach_msg_option64_t options,
656 mach_msg_timeout_t msg_timeout,
657 mach_msg_priority_t priority)
658 {
659 ipc_space_t space = current_space();
660 vm_map_t map = current_map();
661 ipc_kmsg_t kmsg;
662 mach_msg_return_t mr;
663
664 assert(options & MACH64_SEND_MSG);
665
666 /*
667 * Validate the send sizes and header carefuly.
668 */
669 if (send_uctx->send_msg_size < sizeof(mach_msg_user_header_t) ||
670 (send_uctx->send_msg_size & 3)) {
671 return MACH_SEND_MSG_TOO_SMALL;
672 }
673 if (send_uctx->send_msg_size > IPC_KMSG_MAX_BODY_SPACE) {
674 return MACH_SEND_TOO_LARGE;
675 }
676 /*
677 * Complex message must have a body, also do a bound check on descriptor count
678 * (more in ikm_check_descriptors()).
679 */
680 if (send_uctx->send_header.msgh_bits & MACH_MSGH_BITS_COMPLEX) {
681 if (send_uctx->send_msg_size < sizeof(mach_msg_user_base_t)) {
682 return MACH_SEND_MSG_TOO_SMALL;
683 }
684 if (send_uctx->send_dsc_count >
685 (send_uctx->send_msg_size - sizeof(mach_msg_user_base_t)) /
686 sizeof(mach_msg_type_descriptor_t)) {
687 return MACH_SEND_MSG_TOO_SMALL;
688 }
689 } else if (send_uctx->send_dsc_count != 0) {
690 /*
691 * Simple message cannot contain descriptors.
692 *
693 * This invalid config can only happen from mach_msg2_trap()
694 * since desc_count is passed as its own trap argument.
695 */
696 assert(options & MACH64_MACH_MSG2);
697 return MACH_SEND_TOO_LARGE;
698 }
699
700 /*
701 * Now that we have validated send_msg_size, send_aux_size and
702 * send_dsc_count, copy in the message.
703 */
704 kmsg = ipc_kmsg_alloc(send_uctx->send_msg_size, send_uctx->send_aux_size,
705 send_uctx->send_dsc_count, IPC_KMSG_ALLOC_USER);
706 if (kmsg == IKM_NULL) {
707 return MACH_SEND_NO_BUFFER;
708 }
709
710 KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_IPC, MACH_IPC_KMSG_LINK) | DBG_FUNC_NONE,
711 (uintptr_t)send_uctx->send_msg_addr, VM_KERNEL_ADDRPERM((uintptr_t)kmsg),
712 0, 0, 0);
713
714 /*
715 * holding kmsg ref
716 * may add MACH64_SEND_ALWAYS to options
717 */
718 mr = ipc_kmsg_copyin_from_user(kmsg, send_uctx, space, map, priority, &options);
719 if (mr != MACH_MSG_SUCCESS) {
720 ipc_kmsg_free(kmsg);
721 return mr;
722 }
723
724 mr = ipc_kmsg_send(kmsg, options, msg_timeout);
725
726 if (mr != MACH_MSG_SUCCESS) {
727 mr |= mach_msg_receive_pseudo(kmsg, send_uctx, options, space, map);
728 /* kmsg is freed */
729 }
730
731 return mr;
732 }
733
734 /*
735 * Routine: mach_msg_trap_receive [internal]
736 * Purpose:
737 * Receive a message.
738 * Conditions:
739 * MACH_RCV_MSG is set.
740 * max_{msg, aux}_rcv_size are already validated.
741 * Returns:
742 * All of mach_msg_receive error codes.
743 */
744 static mach_msg_return_t
mach_msg_trap_receive(mach_vm_address_t msg_addr,mach_vm_address_t aux_addr,mach_msg_option64_t option64,mach_msg_timeout_t msg_timeout,mach_port_name_t sync_send,mach_msg_size_t max_msg_rcv_size,mach_msg_size_t max_aux_rcv_size,mach_port_name_t rcv_name)745 mach_msg_trap_receive(
746 /* shared args between send and receive */
747 mach_vm_address_t msg_addr,
748 mach_vm_address_t aux_addr, /* 0 if not vector send/rcv */
749 mach_msg_option64_t option64,
750 mach_msg_timeout_t msg_timeout,
751 mach_port_name_t sync_send,
752 /* msg receive args */
753 mach_msg_size_t max_msg_rcv_size,
754 mach_msg_size_t max_aux_rcv_size, /* 0 if not vector send/rcv */
755 mach_port_name_t rcv_name)
756 {
757 ipc_object_t object;
758
759 thread_t self = current_thread();
760 ipc_space_t space = current_space();
761 mach_msg_return_t mr = MACH_MSG_SUCCESS;
762
763 assert(option64 & MACH64_RCV_MSG);
764
765 mr = ipc_mqueue_copyin(space, rcv_name, &object);
766 if (mr != MACH_MSG_SUCCESS) {
767 return mr;
768 }
769 /* hold ref for object */
770
771 if (sync_send != MACH_PORT_NULL) {
772 ipc_port_t special_reply_port = ip_object_to_port(object);
773 /* link the special reply port to the destination */
774 mr = mach_msg_rcv_link_special_reply_port(special_reply_port, sync_send);
775 if (mr != MACH_MSG_SUCCESS) {
776 io_release(object);
777 return mr;
778 }
779 }
780
781 /* Set up message proper receive params on thread */
782 bzero(&self->ith_receive, sizeof(self->ith_receive));
783 self->ith_recv_bufs = (mach_msg_recv_bufs_t){
784 .recv_msg_addr = msg_addr,
785 .recv_msg_size = max_msg_rcv_size,
786 .recv_aux_addr = max_aux_rcv_size ? aux_addr : 0,
787 .recv_aux_size = max_aux_rcv_size,
788 };
789 self->ith_object = object;
790 self->ith_option = option64;
791 self->ith_knote = ITH_KNOTE_NULL; /* not part of ith_receive */
792
793 ipc_mqueue_receive(io_waitq(object), msg_timeout, THREAD_ABORTSAFE,
794 self, /* continuation ? */ true);
795 /* NOTREACHED if thread started waiting */
796
797 if ((option64 & MACH_RCV_TIMEOUT) && msg_timeout == 0) {
798 thread_poll_yield(self);
799 }
800
801 mr = mach_msg_receive_results(NULL);
802 /* release ref on ith_object */
803
804 return mr;
805 }
806
807 /*
808 * Routine: mach_msg_overwrite_trap [mach trap]
809 * Purpose:
810 * Possibly send a message; possibly receive a message.
811 *
812 * /!\ Deprecated /!\
813 * No longer supported on embedded and will be removed from macOS.
814 * Use mach_msg2_trap() instead.
815 * Conditions:
816 * Nothing locked.
817 * The 'priority' is only a QoS if MACH_SEND_OVERRIDE is passed -
818 * otherwise, it is a port name.
819 * Returns:
820 * All of mach_msg_send and mach_msg_receive error codes.
821 */
822 mach_msg_return_t
mach_msg_overwrite_trap(struct mach_msg_overwrite_trap_args * args)823 mach_msg_overwrite_trap(
824 struct mach_msg_overwrite_trap_args *args)
825 {
826 #if IPC_HAS_LEGACY_MACH_MSG_TRAP
827 mach_msg_option64_t options = args->option;
828 mach_msg_return_t mr = MACH_MSG_SUCCESS;
829
830 options = ipc_current_msg_options(current_task(), options);
831
832 KDBG(MACHDBG_CODE(DBG_MACH_IPC, MACH_IPC_KMSG_INFO) | DBG_FUNC_START);
833
834 if (options & MACH_SEND_MSG) {
835 mach_msg_send_uctx_t send_uctx = {
836 .send_msg_addr = args->msg,
837 .send_msg_size = args->send_size,
838 };
839
840 /*
841 * Perform a crude copyin of the mach_msg_user_header_t,
842 * including the next 4 bytes in case it is a complex message,
843 * in order to mimic mach_msg2_trap() behavior of synthesizing
844 * the mach_msg_user_base_t via the trap arguments.
845 *
846 * mach_msg_trap_send() will do more thorough validation of
847 * sizes and header.
848 */
849
850 mr = mach_msg_copyin_user_header(&send_uctx, options);
851 if (mr != MACH_MSG_SUCCESS) {
852 return mr;
853 }
854
855 mr = mach_msg_trap_send(&send_uctx, options,
856 args->timeout, args->priority);
857 }
858
859 /* If send failed, skip receive */
860 if (mr != MACH_MSG_SUCCESS) {
861 KDBG(MACHDBG_CODE(DBG_MACH_IPC, MACH_IPC_KMSG_INFO) | DBG_FUNC_END, mr);
862 goto end;
863 }
864
865 if (options & MACH_RCV_MSG) {
866 mach_vm_address_t msg_addr = args->rcv_msg ?: args->msg;
867 mach_port_name_t sync_send = MACH_PORT_NULL;
868
869 /*
870 * Although just the presence of MACH_RCV_SYNC_WAIT and absence of
871 * MACH_SEND_OVERRIDE should imply that 'priority' is a valid port name
872 * to link, in practice older userspace is dependent on
873 * MACH_SEND_SYNC_OVERRIDE also excluding this path.
874 */
875 if ((options & MACH_RCV_SYNC_WAIT) &&
876 !(options & (MACH_SEND_OVERRIDE | MACH_SEND_MSG)) &&
877 !(options & MACH_SEND_SYNC_OVERRIDE)) {
878 sync_send = (mach_port_name_t)args->priority;
879 }
880
881 mr = mach_msg_trap_receive(msg_addr, 0, options, args->timeout,
882 sync_send, args->rcv_size, 0, args->rcv_name);
883 }
884
885 end:
886 /* unblock call is idempotent */
887 ipc_port_thread_group_unblocked();
888 return mr;
889 #else
890 (void)args;
891 return KERN_NOT_SUPPORTED;
892 #endif /* IPC_HAS_LEGACY_MACH_MSG_TRAP */
893 }
894
895 /*
896 * Routine: mach_msg_trap [mach trap]
897 * Purpose:
898 * Possibly send a message; possibly receive a message.
899 *
900 * /!\ Deprecated /!\
901 * No longer supported on embedded and will be removed from macOS.
902 * Use mach_msg2_trap() instead.
903 * Conditions:
904 * Nothing locked.
905 * Returns:
906 * All of mach_msg_send and mach_msg_receive error codes.
907 */
908 mach_msg_return_t
mach_msg_trap(struct mach_msg_overwrite_trap_args * args)909 mach_msg_trap(
910 struct mach_msg_overwrite_trap_args *args)
911 {
912 args->rcv_msg = (mach_vm_address_t)0;
913
914 return mach_msg_overwrite_trap(args);
915 }
916
917 /*
918 * Routine: mach_msg2_trap [mach trap]
919 * Purpose:
920 * Modern mach_msg_trap() with vector message and CFI support.
921 * Conditions:
922 * Nothing locked.
923 * Returns:
924 * All of mach_msg_send and mach_msg_receive error codes.
925 */
926 mach_msg_return_t
mach_msg2_trap(struct mach_msg2_trap_args * args)927 mach_msg2_trap(
928 struct mach_msg2_trap_args *args)
929 {
930 /* packed arguments, LO_BITS_and_HI_BITS */
931 uint64_t mb_ss = args->msgh_bits_and_send_size;
932 uint64_t mr_lp = args->msgh_remote_and_local_port;
933 uint64_t mv_id = args->msgh_voucher_and_id;
934 uint64_t dc_rn = args->desc_count_and_rcv_name;
935 uint64_t rs_pr = args->rcv_size_and_priority;
936
937 mach_msg_timeout_t msg_timeout = (mach_msg_timeout_t)args->timeout;
938 mach_msg_vector_t msg_vec = {}, aux_vec = {};
939 mach_msg_size_t vec_snd_count = 0;
940 mach_msg_size_t vec_rcv_count = 0;
941 mach_msg_option64_t option64;
942 mach_msg_return_t mr = MACH_MSG_SUCCESS;
943
944 option64 = ipc_current_msg_options(current_task(),
945 args->options) | MACH64_MACH_MSG2;
946
947 KDBG(MACHDBG_CODE(DBG_MACH_IPC, MACH_IPC_KMSG_INFO) | DBG_FUNC_START);
948
949 mr = ipc_preflight_msg_option64(option64);
950 if (mr != MACH_MSG_SUCCESS) {
951 goto send_fail;
952 }
953
954 if (option64 & MACH64_MSG_VECTOR) {
955 vec_snd_count = (mach_msg_size_t)(mb_ss >> 32);
956 vec_rcv_count = (mach_msg_size_t)rs_pr;
957
958 mr = mach_msg_copyin_data_vectors(args->data,
959 MAX(vec_snd_count, vec_rcv_count), option64, &msg_vec, &aux_vec);
960 if (mr != MACH_MSG_SUCCESS) {
961 goto send_fail;
962 }
963 }
964
965 if (option64 & MACH64_SEND_MSG) {
966 mach_msg_send_uctx_t send_uctx = {
967 .send_header = {
968 .msgh_bits = (mach_msg_bits_t) (mb_ss),
969 .msgh_size = 0,
970 .msgh_remote_port = (mach_port_name_t)(mr_lp),
971 .msgh_local_port = (mach_port_name_t)(mr_lp >> 32),
972 .msgh_voucher_port = (mach_port_name_t)(mv_id),
973 .msgh_id = (mach_msg_id_t) (mv_id >> 32),
974 },
975 .send_dsc_count = (mach_msg_size_t)dc_rn,
976 };
977 mach_msg_priority_t priority = (mach_msg_priority_t)(rs_pr >> 32);
978
979 if (option64 & MACH64_MSG_VECTOR) {
980 /*
981 * only validate msg send related arguments.
982 *
983 * bad receive args do not stop us from sending
984 * during combined send/rcv.
985 */
986 mr = mach_msg_validate_data_vectors(&msg_vec, &aux_vec,
987 vec_snd_count, option64, /* sending? */ TRUE);
988 if (mr != MACH_MSG_SUCCESS) {
989 goto send_fail;
990 }
991
992 send_uctx.send_msg_addr = msg_vec.msgv_data;
993 send_uctx.send_msg_size = msg_vec.msgv_send_size;
994 send_uctx.send_aux_size = aux_vec.msgv_send_size;
995 if (send_uctx.send_aux_size) {
996 send_uctx.send_aux_addr = aux_vec.msgv_data;
997 }
998 } else {
999 send_uctx.send_msg_addr = args->data;
1000 send_uctx.send_msg_size = (mach_msg_size_t)(mb_ss >> 32);
1001 }
1002
1003 mr = mach_msg_trap_send(&send_uctx, option64, msg_timeout, priority);
1004 }
1005
1006 send_fail:
1007 /* if send failed, skip receive */
1008 if (mr != MACH_MSG_SUCCESS) {
1009 KDBG(MACHDBG_CODE(DBG_MACH_IPC, MACH_IPC_KMSG_INFO) | DBG_FUNC_END, mr);
1010 goto end;
1011 }
1012
1013 if (option64 & MACH64_RCV_MSG) {
1014 mach_port_name_t rcv_name = (mach_port_name_t)(dc_rn >> 32);
1015 mach_port_name_t sync_send = MACH_PORT_NULL;
1016 mach_vm_address_t msg_addr = 0;
1017 mach_msg_size_t msg_size = 0;
1018 mach_vm_address_t aux_addr = 0;
1019 mach_msg_size_t aux_size = 0;
1020
1021 if (option64 & MACH64_MSG_VECTOR) {
1022 /* only validate msg receive related arguments */
1023 mr = mach_msg_validate_data_vectors(&msg_vec, &aux_vec,
1024 vec_rcv_count, option64, /* sending? */ FALSE);
1025 if (mr != MACH_MSG_SUCCESS) {
1026 goto end;
1027 }
1028
1029 msg_addr = msg_vec.msgv_rcv_addr ?: msg_vec.msgv_data;
1030 msg_size = msg_vec.msgv_rcv_size;
1031 aux_size = aux_vec.msgv_rcv_size;
1032 if (aux_size) {
1033 aux_addr = aux_vec.msgv_rcv_addr ?: aux_vec.msgv_data;
1034 }
1035 } else {
1036 msg_addr = args->data;
1037 msg_size = (mach_msg_size_t)rs_pr;
1038 }
1039
1040 if (option64 & MACH64_RCV_SYNC_WAIT) {
1041 /* use msgh_remote_port as sync send boosting port */
1042 sync_send = (mach_port_name_t)mr_lp;
1043 }
1044
1045 mr = mach_msg_trap_receive(msg_addr, aux_addr, option64,
1046 msg_timeout, sync_send, msg_size, aux_size, rcv_name);
1047 }
1048
1049 end:
1050 /* unblock call is idempotent */
1051 ipc_port_thread_group_unblocked();
1052 return mr;
1053 }
1054
1055 /*
1056 * Routine: mach_msg_rcv_link_special_reply_port
1057 * Purpose:
1058 * Link the special reply port(rcv right) to the
1059 * other end of the sync ipc channel.
1060 * Conditions:
1061 * Nothing locked.
1062 * Returns:
1063 * None.
1064 */
1065 static mach_msg_return_t
mach_msg_rcv_link_special_reply_port(ipc_port_t special_reply_port,mach_port_name_t dest_name_port)1066 mach_msg_rcv_link_special_reply_port(
1067 ipc_port_t special_reply_port,
1068 mach_port_name_t dest_name_port)
1069 {
1070 ipc_port_t dest_port = IP_NULL;
1071 kern_return_t kr;
1072
1073 if (current_thread()->ith_special_reply_port != special_reply_port) {
1074 return MACH_RCV_INVALID_NOTIFY;
1075 }
1076
1077 /* Copyin the destination port */
1078 if (!MACH_PORT_VALID(dest_name_port)) {
1079 return MACH_RCV_INVALID_NOTIFY;
1080 }
1081
1082 kr = ipc_port_translate_send(current_space(), dest_name_port, &dest_port);
1083 if (kr == KERN_SUCCESS) {
1084 ip_reference(dest_port);
1085 ip_mq_unlock(dest_port);
1086
1087 /*
1088 * The receive right of dest port might have gone away,
1089 * do not fail the receive in that case.
1090 */
1091 ipc_port_link_special_reply_port(special_reply_port,
1092 dest_port, FALSE);
1093
1094 ip_release(dest_port);
1095 }
1096 return MACH_MSG_SUCCESS;
1097 }
1098
1099 /*
1100 * Routine: mach_msg_receive_results_complete
1101 * Purpose:
1102 * Get thread's turnstile back from the object and
1103 * if object is a special reply port then reset its
1104 * linkage.
1105 * Condition:
1106 * Nothing locked.
1107 * Returns:
1108 * None.
1109 */
1110 void
mach_msg_receive_results_complete(ipc_object_t object)1111 mach_msg_receive_results_complete(ipc_object_t object)
1112 {
1113 thread_t self = current_thread();
1114 ipc_port_t port = IP_NULL;
1115 boolean_t get_turnstile = (self->turnstile == TURNSTILE_NULL);
1116
1117 if (io_is_pset(object)) {
1118 assert(self->turnstile != TURNSTILE_NULL);
1119 return;
1120 }
1121
1122 uint8_t flags = IPC_PORT_ADJUST_SR_ALLOW_SYNC_LINKAGE;
1123
1124 /*
1125 * Don't clear the ip_srp_msg_sent bit if...
1126 */
1127 if (!((self->ith_state == MACH_RCV_TOO_LARGE && self->ith_option & MACH_RCV_LARGE) || //msg was too large and the next receive will get it
1128 self->ith_state == MACH_RCV_INTERRUPTED ||
1129 self->ith_state == MACH_RCV_TIMED_OUT ||
1130 self->ith_state == MACH_RCV_PORT_CHANGED)) {
1131 flags |= IPC_PORT_ADJUST_SR_RECEIVED_MSG;
1132 }
1133
1134 port = ip_object_to_port(object);
1135 if (ip_is_special_reply_port(port) || get_turnstile) {
1136 ip_mq_lock(port);
1137 ipc_port_adjust_special_reply_port_locked(port, NULL,
1138 flags, get_turnstile);
1139 /* port unlocked */
1140 }
1141 assert(self->turnstile != TURNSTILE_NULL);
1142 /* thread now has a turnstile */
1143 }
1144
1145
1146 SECURITY_READ_ONLY_LATE(struct mach_msg_filter_callbacks) mach_msg_filter_callbacks;
1147
1148 kern_return_t
mach_msg_filter_register_callback(const struct mach_msg_filter_callbacks * callbacks)1149 mach_msg_filter_register_callback(
1150 const struct mach_msg_filter_callbacks *callbacks)
1151 {
1152 size_t size = 0;
1153
1154 if (callbacks == NULL) {
1155 return KERN_INVALID_ARGUMENT;
1156 }
1157 if (mach_msg_filter_callbacks.fetch_filter_policy != NULL) {
1158 /* double init */
1159 return KERN_FAILURE;
1160 }
1161
1162 if (callbacks->version >= MACH_MSG_FILTER_CALLBACKS_VERSION_0) {
1163 /* check for missing v0 callbacks */
1164 if (callbacks->fetch_filter_policy == NULL) {
1165 return KERN_INVALID_ARGUMENT;
1166 }
1167 size = offsetof(struct mach_msg_filter_callbacks, alloc_service_port_sblabel);
1168 }
1169
1170 if (callbacks->version >= MACH_MSG_FILTER_CALLBACKS_VERSION_1) {
1171 if (callbacks->alloc_service_port_sblabel == NULL ||
1172 callbacks->dealloc_service_port_sblabel == NULL ||
1173 callbacks->derive_sblabel_from_service_port == NULL ||
1174 callbacks->get_connection_port_filter_policy == NULL ||
1175 callbacks->retain_sblabel == NULL) {
1176 return KERN_INVALID_ARGUMENT;
1177 }
1178 size = sizeof(struct mach_msg_filter_callbacks);
1179 }
1180
1181 if (callbacks->version > MACH_MSG_FILTER_CALLBACKS_VERSION_1) {
1182 /* invalid version */
1183 return KERN_INVALID_ARGUMENT;
1184 }
1185
1186 memcpy(&mach_msg_filter_callbacks, callbacks, size);
1187 return KERN_SUCCESS;
1188 }
1189
1190 /* This function should only be called if the task and port allow message filtering */
1191 boolean_t
mach_msg_fetch_filter_policy(void * port_label,mach_msg_id_t msgh_id,mach_msg_filter_id * fid)1192 mach_msg_fetch_filter_policy(
1193 void *port_label,
1194 mach_msg_id_t msgh_id,
1195 mach_msg_filter_id *fid)
1196 {
1197 boolean_t ret = TRUE;
1198
1199 if (mach_msg_fetch_filter_policy_callback == NULL) {
1200 *fid = MACH_MSG_FILTER_POLICY_ALLOW;
1201 return true;
1202 }
1203 ret = mach_msg_fetch_filter_policy_callback(current_task(), port_label, msgh_id, fid);
1204
1205 return ret;
1206 }
1207