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1/*
2 * linux/ipc/msg.c
3 * Copyright (C) 1992 Krishna Balasubramanian
4 *
5 * Removed all the remaining kerneld mess
6 * Catch the -EFAULT stuff properly
7 * Use GFP_KERNEL for messages as in 1.2
8 * Fixed up the unchecked user space derefs
9 * Copyright (C) 1998 Alan Cox & Andi Kleen
10 *
11 * /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
12 *
13 * mostly rewritten, threaded and wake-one semantics added
14 * MSGMAX limit removed, sysctl's added
15 * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
16 *
17 * support for audit of ipc object properties and permission changes
18 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
19 *
20 * namespaces support
21 * OpenVZ, SWsoft Inc.
22 * Pavel Emelianov <xemul@openvz.org>
23 */
24
25#include <linux/capability.h>
26#include <linux/msg.h>
27#include <linux/spinlock.h>
28#include <linux/init.h>
29#include <linux/mm.h>
30#include <linux/proc_fs.h>
31#include <linux/list.h>
32#include <linux/security.h>
33#include <linux/sched.h>
34#include <linux/syscalls.h>
35#include <linux/audit.h>
36#include <linux/seq_file.h>
37#include <linux/rwsem.h>
38#include <linux/nsproxy.h>
39#include <linux/ipc_namespace.h>
40
41#include <asm/current.h>
42#include <linux/uaccess.h>
43#include "util.h"
44
45/* one msg_receiver structure for each sleeping receiver */
46struct msg_receiver {
47 struct list_head r_list;
48 struct task_struct *r_tsk;
49
50 int r_mode;
51 long r_msgtype;
52 long r_maxsize;
53
54 struct msg_msg *r_msg;
55};
56
57/* one msg_sender for each sleeping sender */
58struct msg_sender {
59 struct list_head list;
60 struct task_struct *tsk;
61 size_t msgsz;
62};
63
64#define SEARCH_ANY 1
65#define SEARCH_EQUAL 2
66#define SEARCH_NOTEQUAL 3
67#define SEARCH_LESSEQUAL 4
68#define SEARCH_NUMBER 5
69
70#define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS])
71
72static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
73{
74 struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id);
75
76 if (IS_ERR(ipcp))
77 return ERR_CAST(ipcp);
78
79 return container_of(ipcp, struct msg_queue, q_perm);
80}
81
82static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
83 int id)
84{
85 struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
86
87 if (IS_ERR(ipcp))
88 return ERR_CAST(ipcp);
89
90 return container_of(ipcp, struct msg_queue, q_perm);
91}
92
93static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
94{
95 ipc_rmid(&msg_ids(ns), &s->q_perm);
96}
97
98static void msg_rcu_free(struct rcu_head *head)
99{
100 struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
101 struct msg_queue *msq = ipc_rcu_to_struct(p);
102
103 security_msg_queue_free(msq);
104 ipc_rcu_free(head);
105}
106
107/**
108 * newque - Create a new msg queue
109 * @ns: namespace
110 * @params: ptr to the structure that contains the key and msgflg
111 *
112 * Called with msg_ids.rwsem held (writer)
113 */
114static int newque(struct ipc_namespace *ns, struct ipc_params *params)
115{
116 struct msg_queue *msq;
117 int id, retval;
118 key_t key = params->key;
119 int msgflg = params->flg;
120
121 msq = ipc_rcu_alloc(sizeof(*msq));
122 if (!msq)
123 return -ENOMEM;
124
125 msq->q_perm.mode = msgflg & S_IRWXUGO;
126 msq->q_perm.key = key;
127
128 msq->q_perm.security = NULL;
129 retval = security_msg_queue_alloc(msq);
130 if (retval) {
131 ipc_rcu_putref(msq, ipc_rcu_free);
132 return retval;
133 }
134
135 msq->q_stime = msq->q_rtime = 0;
136 msq->q_ctime = get_seconds();
137 msq->q_cbytes = msq->q_qnum = 0;
138 msq->q_qbytes = ns->msg_ctlmnb;
139 msq->q_lspid = msq->q_lrpid = 0;
140 INIT_LIST_HEAD(&msq->q_messages);
141 INIT_LIST_HEAD(&msq->q_receivers);
142 INIT_LIST_HEAD(&msq->q_senders);
143
144 /* ipc_addid() locks msq upon success. */
145 id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
146 if (id < 0) {
147 ipc_rcu_putref(msq, msg_rcu_free);
148 return id;
149 }
150
151 ipc_unlock_object(&msq->q_perm);
152 rcu_read_unlock();
153
154 return msq->q_perm.id;
155}
156
157static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz)
158{
159 return msgsz + msq->q_cbytes <= msq->q_qbytes &&
160 1 + msq->q_qnum <= msq->q_qbytes;
161}
162
163static inline void ss_add(struct msg_queue *msq,
164 struct msg_sender *mss, size_t msgsz)
165{
166 mss->tsk = current;
167 mss->msgsz = msgsz;
168 __set_current_state(TASK_INTERRUPTIBLE);
169 list_add_tail(&mss->list, &msq->q_senders);
170}
171
172static inline void ss_del(struct msg_sender *mss)
173{
174 if (mss->list.next)
175 list_del(&mss->list);
176}
177
178static void ss_wakeup(struct msg_queue *msq,
179 struct wake_q_head *wake_q, bool kill)
180{
181 struct msg_sender *mss, *t;
182 struct task_struct *stop_tsk = NULL;
183 struct list_head *h = &msq->q_senders;
184
185 list_for_each_entry_safe(mss, t, h, list) {
186 if (kill)
187 mss->list.next = NULL;
188
189 /*
190 * Stop at the first task we don't wakeup,
191 * we've already iterated the original
192 * sender queue.
193 */
194 else if (stop_tsk == mss->tsk)
195 break;
196 /*
197 * We are not in an EIDRM scenario here, therefore
198 * verify that we really need to wakeup the task.
199 * To maintain current semantics and wakeup order,
200 * move the sender to the tail on behalf of the
201 * blocked task.
202 */
203 else if (!msg_fits_inqueue(msq, mss->msgsz)) {
204 if (!stop_tsk)
205 stop_tsk = mss->tsk;
206
207 list_move_tail(&mss->list, &msq->q_senders);
208 continue;
209 }
210
211 wake_q_add(wake_q, mss->tsk);
212 }
213}
214
215static void expunge_all(struct msg_queue *msq, int res,
216 struct wake_q_head *wake_q)
217{
218 struct msg_receiver *msr, *t;
219
220 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
221 wake_q_add(wake_q, msr->r_tsk);
222 WRITE_ONCE(msr->r_msg, ERR_PTR(res));
223 }
224}
225
226/*
227 * freeque() wakes up waiters on the sender and receiver waiting queue,
228 * removes the message queue from message queue ID IDR, and cleans up all the
229 * messages associated with this queue.
230 *
231 * msg_ids.rwsem (writer) and the spinlock for this message queue are held
232 * before freeque() is called. msg_ids.rwsem remains locked on exit.
233 */
234static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
235{
236 struct msg_msg *msg, *t;
237 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
238 DEFINE_WAKE_Q(wake_q);
239
240 expunge_all(msq, -EIDRM, &wake_q);
241 ss_wakeup(msq, &wake_q, true);
242 msg_rmid(ns, msq);
243 ipc_unlock_object(&msq->q_perm);
244 wake_up_q(&wake_q);
245 rcu_read_unlock();
246
247 list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
248 atomic_dec(&ns->msg_hdrs);
249 free_msg(msg);
250 }
251 atomic_sub(msq->q_cbytes, &ns->msg_bytes);
252 ipc_rcu_putref(msq, msg_rcu_free);
253}
254
255/*
256 * Called with msg_ids.rwsem and ipcp locked.
257 */
258static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
259{
260 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
261
262 return security_msg_queue_associate(msq, msgflg);
263}
264
265SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
266{
267 struct ipc_namespace *ns;
268 static const struct ipc_ops msg_ops = {
269 .getnew = newque,
270 .associate = msg_security,
271 };
272 struct ipc_params msg_params;
273
274 ns = current->nsproxy->ipc_ns;
275
276 msg_params.key = key;
277 msg_params.flg = msgflg;
278
279 return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
280}
281
282static inline unsigned long
283copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
284{
285 switch (version) {
286 case IPC_64:
287 return copy_to_user(buf, in, sizeof(*in));
288 case IPC_OLD:
289 {
290 struct msqid_ds out;
291
292 memset(&out, 0, sizeof(out));
293
294 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
295
296 out.msg_stime = in->msg_stime;
297 out.msg_rtime = in->msg_rtime;
298 out.msg_ctime = in->msg_ctime;
299
300 if (in->msg_cbytes > USHRT_MAX)
301 out.msg_cbytes = USHRT_MAX;
302 else
303 out.msg_cbytes = in->msg_cbytes;
304 out.msg_lcbytes = in->msg_cbytes;
305
306 if (in->msg_qnum > USHRT_MAX)
307 out.msg_qnum = USHRT_MAX;
308 else
309 out.msg_qnum = in->msg_qnum;
310
311 if (in->msg_qbytes > USHRT_MAX)
312 out.msg_qbytes = USHRT_MAX;
313 else
314 out.msg_qbytes = in->msg_qbytes;
315 out.msg_lqbytes = in->msg_qbytes;
316
317 out.msg_lspid = in->msg_lspid;
318 out.msg_lrpid = in->msg_lrpid;
319
320 return copy_to_user(buf, &out, sizeof(out));
321 }
322 default:
323 return -EINVAL;
324 }
325}
326
327static inline unsigned long
328copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
329{
330 switch (version) {
331 case IPC_64:
332 if (copy_from_user(out, buf, sizeof(*out)))
333 return -EFAULT;
334 return 0;
335 case IPC_OLD:
336 {
337 struct msqid_ds tbuf_old;
338
339 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
340 return -EFAULT;
341
342 out->msg_perm.uid = tbuf_old.msg_perm.uid;
343 out->msg_perm.gid = tbuf_old.msg_perm.gid;
344 out->msg_perm.mode = tbuf_old.msg_perm.mode;
345
346 if (tbuf_old.msg_qbytes == 0)
347 out->msg_qbytes = tbuf_old.msg_lqbytes;
348 else
349 out->msg_qbytes = tbuf_old.msg_qbytes;
350
351 return 0;
352 }
353 default:
354 return -EINVAL;
355 }
356}
357
358/*
359 * This function handles some msgctl commands which require the rwsem
360 * to be held in write mode.
361 * NOTE: no locks must be held, the rwsem is taken inside this function.
362 */
363static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
364 struct msqid_ds __user *buf, int version)
365{
366 struct kern_ipc_perm *ipcp;
367 struct msqid64_ds uninitialized_var(msqid64);
368 struct msg_queue *msq;
369 int err;
370
371 if (cmd == IPC_SET) {
372 if (copy_msqid_from_user(&msqid64, buf, version))
373 return -EFAULT;
374 }
375
376 down_write(&msg_ids(ns).rwsem);
377 rcu_read_lock();
378
379 ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
380 &msqid64.msg_perm, msqid64.msg_qbytes);
381 if (IS_ERR(ipcp)) {
382 err = PTR_ERR(ipcp);
383 goto out_unlock1;
384 }
385
386 msq = container_of(ipcp, struct msg_queue, q_perm);
387
388 err = security_msg_queue_msgctl(msq, cmd);
389 if (err)
390 goto out_unlock1;
391
392 switch (cmd) {
393 case IPC_RMID:
394 ipc_lock_object(&msq->q_perm);
395 /* freeque unlocks the ipc object and rcu */
396 freeque(ns, ipcp);
397 goto out_up;
398 case IPC_SET:
399 {
400 DEFINE_WAKE_Q(wake_q);
401
402 if (msqid64.msg_qbytes > ns->msg_ctlmnb &&
403 !capable(CAP_SYS_RESOURCE)) {
404 err = -EPERM;
405 goto out_unlock1;
406 }
407
408 ipc_lock_object(&msq->q_perm);
409 err = ipc_update_perm(&msqid64.msg_perm, ipcp);
410 if (err)
411 goto out_unlock0;
412
413 msq->q_qbytes = msqid64.msg_qbytes;
414
415 msq->q_ctime = get_seconds();
416 /*
417 * Sleeping receivers might be excluded by
418 * stricter permissions.
419 */
420 expunge_all(msq, -EAGAIN, &wake_q);
421 /*
422 * Sleeping senders might be able to send
423 * due to a larger queue size.
424 */
425 ss_wakeup(msq, &wake_q, false);
426 ipc_unlock_object(&msq->q_perm);
427 wake_up_q(&wake_q);
428
429 goto out_unlock1;
430 }
431 default:
432 err = -EINVAL;
433 goto out_unlock1;
434 }
435
436out_unlock0:
437 ipc_unlock_object(&msq->q_perm);
438out_unlock1:
439 rcu_read_unlock();
440out_up:
441 up_write(&msg_ids(ns).rwsem);
442 return err;
443}
444
445static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
446 int cmd, int version, void __user *buf)
447{
448 int err;
449 struct msg_queue *msq;
450
451 switch (cmd) {
452 case IPC_INFO:
453 case MSG_INFO:
454 {
455 struct msginfo msginfo;
456 int max_id;
457
458 if (!buf)
459 return -EFAULT;
460
461 /*
462 * We must not return kernel stack data.
463 * due to padding, it's not enough
464 * to set all member fields.
465 */
466 err = security_msg_queue_msgctl(NULL, cmd);
467 if (err)
468 return err;
469
470 memset(&msginfo, 0, sizeof(msginfo));
471 msginfo.msgmni = ns->msg_ctlmni;
472 msginfo.msgmax = ns->msg_ctlmax;
473 msginfo.msgmnb = ns->msg_ctlmnb;
474 msginfo.msgssz = MSGSSZ;
475 msginfo.msgseg = MSGSEG;
476 down_read(&msg_ids(ns).rwsem);
477 if (cmd == MSG_INFO) {
478 msginfo.msgpool = msg_ids(ns).in_use;
479 msginfo.msgmap = atomic_read(&ns->msg_hdrs);
480 msginfo.msgtql = atomic_read(&ns->msg_bytes);
481 } else {
482 msginfo.msgmap = MSGMAP;
483 msginfo.msgpool = MSGPOOL;
484 msginfo.msgtql = MSGTQL;
485 }
486 max_id = ipc_get_maxid(&msg_ids(ns));
487 up_read(&msg_ids(ns).rwsem);
488 if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
489 return -EFAULT;
490 return (max_id < 0) ? 0 : max_id;
491 }
492
493 case MSG_STAT:
494 case IPC_STAT:
495 {
496 struct msqid64_ds tbuf;
497 int success_return;
498
499 if (!buf)
500 return -EFAULT;
501
502 memset(&tbuf, 0, sizeof(tbuf));
503
504 rcu_read_lock();
505 if (cmd == MSG_STAT) {
506 msq = msq_obtain_object(ns, msqid);
507 if (IS_ERR(msq)) {
508 err = PTR_ERR(msq);
509 goto out_unlock;
510 }
511 success_return = msq->q_perm.id;
512 } else {
513 msq = msq_obtain_object_check(ns, msqid);
514 if (IS_ERR(msq)) {
515 err = PTR_ERR(msq);
516 goto out_unlock;
517 }
518 success_return = 0;
519 }
520
521 err = -EACCES;
522 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
523 goto out_unlock;
524
525 err = security_msg_queue_msgctl(msq, cmd);
526 if (err)
527 goto out_unlock;
528
529 kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
530 tbuf.msg_stime = msq->q_stime;
531 tbuf.msg_rtime = msq->q_rtime;
532 tbuf.msg_ctime = msq->q_ctime;
533 tbuf.msg_cbytes = msq->q_cbytes;
534 tbuf.msg_qnum = msq->q_qnum;
535 tbuf.msg_qbytes = msq->q_qbytes;
536 tbuf.msg_lspid = msq->q_lspid;
537 tbuf.msg_lrpid = msq->q_lrpid;
538 rcu_read_unlock();
539
540 if (copy_msqid_to_user(buf, &tbuf, version))
541 return -EFAULT;
542 return success_return;
543 }
544
545 default:
546 return -EINVAL;
547 }
548
549 return err;
550out_unlock:
551 rcu_read_unlock();
552 return err;
553}
554
555SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
556{
557 int version;
558 struct ipc_namespace *ns;
559
560 if (msqid < 0 || cmd < 0)
561 return -EINVAL;
562
563 version = ipc_parse_version(&cmd);
564 ns = current->nsproxy->ipc_ns;
565
566 switch (cmd) {
567 case IPC_INFO:
568 case MSG_INFO:
569 case MSG_STAT: /* msqid is an index rather than a msg queue id */
570 case IPC_STAT:
571 return msgctl_nolock(ns, msqid, cmd, version, buf);
572 case IPC_SET:
573 case IPC_RMID:
574 return msgctl_down(ns, msqid, cmd, buf, version);
575 default:
576 return -EINVAL;
577 }
578}
579
580static int testmsg(struct msg_msg *msg, long type, int mode)
581{
582 switch (mode) {
583 case SEARCH_ANY:
584 case SEARCH_NUMBER:
585 return 1;
586 case SEARCH_LESSEQUAL:
587 if (msg->m_type <= type)
588 return 1;
589 break;
590 case SEARCH_EQUAL:
591 if (msg->m_type == type)
592 return 1;
593 break;
594 case SEARCH_NOTEQUAL:
595 if (msg->m_type != type)
596 return 1;
597 break;
598 }
599 return 0;
600}
601
602static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg,
603 struct wake_q_head *wake_q)
604{
605 struct msg_receiver *msr, *t;
606
607 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
608 if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
609 !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
610 msr->r_msgtype, msr->r_mode)) {
611
612 list_del(&msr->r_list);
613 if (msr->r_maxsize < msg->m_ts) {
614 wake_q_add(wake_q, msr->r_tsk);
615 WRITE_ONCE(msr->r_msg, ERR_PTR(-E2BIG));
616 } else {
617 msq->q_lrpid = task_pid_vnr(msr->r_tsk);
618 msq->q_rtime = get_seconds();
619
620 wake_q_add(wake_q, msr->r_tsk);
621 WRITE_ONCE(msr->r_msg, msg);
622 return 1;
623 }
624 }
625 }
626
627 return 0;
628}
629
630long do_msgsnd(int msqid, long mtype, void __user *mtext,
631 size_t msgsz, int msgflg)
632{
633 struct msg_queue *msq;
634 struct msg_msg *msg;
635 int err;
636 struct ipc_namespace *ns;
637 DEFINE_WAKE_Q(wake_q);
638
639 ns = current->nsproxy->ipc_ns;
640
641 if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
642 return -EINVAL;
643 if (mtype < 1)
644 return -EINVAL;
645
646 msg = load_msg(mtext, msgsz);
647 if (IS_ERR(msg))
648 return PTR_ERR(msg);
649
650 msg->m_type = mtype;
651 msg->m_ts = msgsz;
652
653 rcu_read_lock();
654 msq = msq_obtain_object_check(ns, msqid);
655 if (IS_ERR(msq)) {
656 err = PTR_ERR(msq);
657 goto out_unlock1;
658 }
659
660 ipc_lock_object(&msq->q_perm);
661
662 for (;;) {
663 struct msg_sender s;
664
665 err = -EACCES;
666 if (ipcperms(ns, &msq->q_perm, S_IWUGO))
667 goto out_unlock0;
668
669 /* raced with RMID? */
670 if (!ipc_valid_object(&msq->q_perm)) {
671 err = -EIDRM;
672 goto out_unlock0;
673 }
674
675 err = security_msg_queue_msgsnd(msq, msg, msgflg);
676 if (err)
677 goto out_unlock0;
678
679 if (msg_fits_inqueue(msq, msgsz))
680 break;
681
682 /* queue full, wait: */
683 if (msgflg & IPC_NOWAIT) {
684 err = -EAGAIN;
685 goto out_unlock0;
686 }
687
688 /* enqueue the sender and prepare to block */
689 ss_add(msq, &s, msgsz);
690
691 if (!ipc_rcu_getref(msq)) {
692 err = -EIDRM;
693 goto out_unlock0;
694 }
695
696 ipc_unlock_object(&msq->q_perm);
697 rcu_read_unlock();
698 schedule();
699
700 rcu_read_lock();
701 ipc_lock_object(&msq->q_perm);
702
703 ipc_rcu_putref(msq, msg_rcu_free);
704 /* raced with RMID? */
705 if (!ipc_valid_object(&msq->q_perm)) {
706 err = -EIDRM;
707 goto out_unlock0;
708 }
709 ss_del(&s);
710
711 if (signal_pending(current)) {
712 err = -ERESTARTNOHAND;
713 goto out_unlock0;
714 }
715
716 }
717
718 msq->q_lspid = task_tgid_vnr(current);
719 msq->q_stime = get_seconds();
720
721 if (!pipelined_send(msq, msg, &wake_q)) {
722 /* no one is waiting for this message, enqueue it */
723 list_add_tail(&msg->m_list, &msq->q_messages);
724 msq->q_cbytes += msgsz;
725 msq->q_qnum++;
726 atomic_add(msgsz, &ns->msg_bytes);
727 atomic_inc(&ns->msg_hdrs);
728 }
729
730 err = 0;
731 msg = NULL;
732
733out_unlock0:
734 ipc_unlock_object(&msq->q_perm);
735 wake_up_q(&wake_q);
736out_unlock1:
737 rcu_read_unlock();
738 if (msg != NULL)
739 free_msg(msg);
740 return err;
741}
742
743SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
744 int, msgflg)
745{
746 long mtype;
747
748 if (get_user(mtype, &msgp->mtype))
749 return -EFAULT;
750 return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
751}
752
753static inline int convert_mode(long *msgtyp, int msgflg)
754{
755 if (msgflg & MSG_COPY)
756 return SEARCH_NUMBER;
757 /*
758 * find message of correct type.
759 * msgtyp = 0 => get first.
760 * msgtyp > 0 => get first message of matching type.
761 * msgtyp < 0 => get message with least type must be < abs(msgtype).
762 */
763 if (*msgtyp == 0)
764 return SEARCH_ANY;
765 if (*msgtyp < 0) {
766 if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */
767 *msgtyp = LONG_MAX;
768 else
769 *msgtyp = -*msgtyp;
770 return SEARCH_LESSEQUAL;
771 }
772 if (msgflg & MSG_EXCEPT)
773 return SEARCH_NOTEQUAL;
774 return SEARCH_EQUAL;
775}
776
777static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
778{
779 struct msgbuf __user *msgp = dest;
780 size_t msgsz;
781
782 if (put_user(msg->m_type, &msgp->mtype))
783 return -EFAULT;
784
785 msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
786 if (store_msg(msgp->mtext, msg, msgsz))
787 return -EFAULT;
788 return msgsz;
789}
790
791#ifdef CONFIG_CHECKPOINT_RESTORE
792/*
793 * This function creates new kernel message structure, large enough to store
794 * bufsz message bytes.
795 */
796static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
797{
798 struct msg_msg *copy;
799
800 /*
801 * Create dummy message to copy real message to.
802 */
803 copy = load_msg(buf, bufsz);
804 if (!IS_ERR(copy))
805 copy->m_ts = bufsz;
806 return copy;
807}
808
809static inline void free_copy(struct msg_msg *copy)
810{
811 if (copy)
812 free_msg(copy);
813}
814#else
815static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
816{
817 return ERR_PTR(-ENOSYS);
818}
819
820static inline void free_copy(struct msg_msg *copy)
821{
822}
823#endif
824
825static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
826{
827 struct msg_msg *msg, *found = NULL;
828 long count = 0;
829
830 list_for_each_entry(msg, &msq->q_messages, m_list) {
831 if (testmsg(msg, *msgtyp, mode) &&
832 !security_msg_queue_msgrcv(msq, msg, current,
833 *msgtyp, mode)) {
834 if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
835 *msgtyp = msg->m_type - 1;
836 found = msg;
837 } else if (mode == SEARCH_NUMBER) {
838 if (*msgtyp == count)
839 return msg;
840 } else
841 return msg;
842 count++;
843 }
844 }
845
846 return found ?: ERR_PTR(-EAGAIN);
847}
848
849long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
850 long (*msg_handler)(void __user *, struct msg_msg *, size_t))
851{
852 int mode;
853 struct msg_queue *msq;
854 struct ipc_namespace *ns;
855 struct msg_msg *msg, *copy = NULL;
856 DEFINE_WAKE_Q(wake_q);
857
858 ns = current->nsproxy->ipc_ns;
859
860 if (msqid < 0 || (long) bufsz < 0)
861 return -EINVAL;
862
863 if (msgflg & MSG_COPY) {
864 if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
865 return -EINVAL;
866 copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
867 if (IS_ERR(copy))
868 return PTR_ERR(copy);
869 }
870 mode = convert_mode(&msgtyp, msgflg);
871
872 rcu_read_lock();
873 msq = msq_obtain_object_check(ns, msqid);
874 if (IS_ERR(msq)) {
875 rcu_read_unlock();
876 free_copy(copy);
877 return PTR_ERR(msq);
878 }
879
880 for (;;) {
881 struct msg_receiver msr_d;
882
883 msg = ERR_PTR(-EACCES);
884 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
885 goto out_unlock1;
886
887 ipc_lock_object(&msq->q_perm);
888
889 /* raced with RMID? */
890 if (!ipc_valid_object(&msq->q_perm)) {
891 msg = ERR_PTR(-EIDRM);
892 goto out_unlock0;
893 }
894
895 msg = find_msg(msq, &msgtyp, mode);
896 if (!IS_ERR(msg)) {
897 /*
898 * Found a suitable message.
899 * Unlink it from the queue.
900 */
901 if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
902 msg = ERR_PTR(-E2BIG);
903 goto out_unlock0;
904 }
905 /*
906 * If we are copying, then do not unlink message and do
907 * not update queue parameters.
908 */
909 if (msgflg & MSG_COPY) {
910 msg = copy_msg(msg, copy);
911 goto out_unlock0;
912 }
913
914 list_del(&msg->m_list);
915 msq->q_qnum--;
916 msq->q_rtime = get_seconds();
917 msq->q_lrpid = task_tgid_vnr(current);
918 msq->q_cbytes -= msg->m_ts;
919 atomic_sub(msg->m_ts, &ns->msg_bytes);
920 atomic_dec(&ns->msg_hdrs);
921 ss_wakeup(msq, &wake_q, false);
922
923 goto out_unlock0;
924 }
925
926 /* No message waiting. Wait for a message */
927 if (msgflg & IPC_NOWAIT) {
928 msg = ERR_PTR(-ENOMSG);
929 goto out_unlock0;
930 }
931
932 list_add_tail(&msr_d.r_list, &msq->q_receivers);
933 msr_d.r_tsk = current;
934 msr_d.r_msgtype = msgtyp;
935 msr_d.r_mode = mode;
936 if (msgflg & MSG_NOERROR)
937 msr_d.r_maxsize = INT_MAX;
938 else
939 msr_d.r_maxsize = bufsz;
940 msr_d.r_msg = ERR_PTR(-EAGAIN);
941 __set_current_state(TASK_INTERRUPTIBLE);
942
943 ipc_unlock_object(&msq->q_perm);
944 rcu_read_unlock();
945 schedule();
946
947 /*
948 * Lockless receive, part 1:
949 * We don't hold a reference to the queue and getting a
950 * reference would defeat the idea of a lockless operation,
951 * thus the code relies on rcu to guarantee the existence of
952 * msq:
953 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
954 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
955 */
956 rcu_read_lock();
957
958 /*
959 * Lockless receive, part 2:
960 * The work in pipelined_send() and expunge_all():
961 * - Set pointer to message
962 * - Queue the receiver task for later wakeup
963 * - Wake up the process after the lock is dropped.
964 *
965 * Should the process wake up before this wakeup (due to a
966 * signal) it will either see the message and continue ...
967 */
968 msg = READ_ONCE(msr_d.r_msg);
969 if (msg != ERR_PTR(-EAGAIN))
970 goto out_unlock1;
971
972 /*
973 * ... or see -EAGAIN, acquire the lock to check the message
974 * again.
975 */
976 ipc_lock_object(&msq->q_perm);
977
978 msg = msr_d.r_msg;
979 if (msg != ERR_PTR(-EAGAIN))
980 goto out_unlock0;
981
982 list_del(&msr_d.r_list);
983 if (signal_pending(current)) {
984 msg = ERR_PTR(-ERESTARTNOHAND);
985 goto out_unlock0;
986 }
987
988 ipc_unlock_object(&msq->q_perm);
989 }
990
991out_unlock0:
992 ipc_unlock_object(&msq->q_perm);
993 wake_up_q(&wake_q);
994out_unlock1:
995 rcu_read_unlock();
996 if (IS_ERR(msg)) {
997 free_copy(copy);
998 return PTR_ERR(msg);
999 }
1000
1001 bufsz = msg_handler(buf, msg, bufsz);
1002 free_msg(msg);
1003
1004 return bufsz;
1005}
1006
1007SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1008 long, msgtyp, int, msgflg)
1009{
1010 return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1011}
1012
1013
1014void msg_init_ns(struct ipc_namespace *ns)
1015{
1016 ns->msg_ctlmax = MSGMAX;
1017 ns->msg_ctlmnb = MSGMNB;
1018 ns->msg_ctlmni = MSGMNI;
1019
1020 atomic_set(&ns->msg_bytes, 0);
1021 atomic_set(&ns->msg_hdrs, 0);
1022 ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
1023}
1024
1025#ifdef CONFIG_IPC_NS
1026void msg_exit_ns(struct ipc_namespace *ns)
1027{
1028 free_ipcs(ns, &msg_ids(ns), freeque);
1029 idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
1030}
1031#endif
1032
1033#ifdef CONFIG_PROC_FS
1034static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1035{
1036 struct user_namespace *user_ns = seq_user_ns(s);
1037 struct msg_queue *msq = it;
1038
1039 seq_printf(s,
1040 "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
1041 msq->q_perm.key,
1042 msq->q_perm.id,
1043 msq->q_perm.mode,
1044 msq->q_cbytes,
1045 msq->q_qnum,
1046 msq->q_lspid,
1047 msq->q_lrpid,
1048 from_kuid_munged(user_ns, msq->q_perm.uid),
1049 from_kgid_munged(user_ns, msq->q_perm.gid),
1050 from_kuid_munged(user_ns, msq->q_perm.cuid),
1051 from_kgid_munged(user_ns, msq->q_perm.cgid),
1052 msq->q_stime,
1053 msq->q_rtime,
1054 msq->q_ctime);
1055
1056 return 0;
1057}
1058#endif
1059
1060void __init msg_init(void)
1061{
1062 msg_init_ns(&init_ipc_ns);
1063
1064 ipc_init_proc_interface("sysvipc/msg",
1065 " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n",
1066 IPC_MSG_IDS, sysvipc_msg_proc_show);
1067}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/ipc/msg.c
4 * Copyright (C) 1992 Krishna Balasubramanian
5 *
6 * Removed all the remaining kerneld mess
7 * Catch the -EFAULT stuff properly
8 * Use GFP_KERNEL for messages as in 1.2
9 * Fixed up the unchecked user space derefs
10 * Copyright (C) 1998 Alan Cox & Andi Kleen
11 *
12 * /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
13 *
14 * mostly rewritten, threaded and wake-one semantics added
15 * MSGMAX limit removed, sysctl's added
16 * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
17 *
18 * support for audit of ipc object properties and permission changes
19 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
20 *
21 * namespaces support
22 * OpenVZ, SWsoft Inc.
23 * Pavel Emelianov <xemul@openvz.org>
24 */
25
26#include <linux/capability.h>
27#include <linux/msg.h>
28#include <linux/spinlock.h>
29#include <linux/init.h>
30#include <linux/mm.h>
31#include <linux/proc_fs.h>
32#include <linux/list.h>
33#include <linux/security.h>
34#include <linux/sched/wake_q.h>
35#include <linux/syscalls.h>
36#include <linux/audit.h>
37#include <linux/seq_file.h>
38#include <linux/rwsem.h>
39#include <linux/nsproxy.h>
40#include <linux/ipc_namespace.h>
41#include <linux/rhashtable.h>
42#include <linux/percpu_counter.h>
43
44#include <asm/current.h>
45#include <linux/uaccess.h>
46#include "util.h"
47
48/* one msq_queue structure for each present queue on the system */
49struct msg_queue {
50 struct kern_ipc_perm q_perm;
51 time64_t q_stime; /* last msgsnd time */
52 time64_t q_rtime; /* last msgrcv time */
53 time64_t q_ctime; /* last change time */
54 unsigned long q_cbytes; /* current number of bytes on queue */
55 unsigned long q_qnum; /* number of messages in queue */
56 unsigned long q_qbytes; /* max number of bytes on queue */
57 struct pid *q_lspid; /* pid of last msgsnd */
58 struct pid *q_lrpid; /* last receive pid */
59
60 struct list_head q_messages;
61 struct list_head q_receivers;
62 struct list_head q_senders;
63} __randomize_layout;
64
65/*
66 * MSG_BARRIER Locking:
67 *
68 * Similar to the optimization used in ipc/mqueue.c, one syscall return path
69 * does not acquire any locks when it sees that a message exists in
70 * msg_receiver.r_msg. Therefore r_msg is set using smp_store_release()
71 * and accessed using READ_ONCE()+smp_acquire__after_ctrl_dep(). In addition,
72 * wake_q_add_safe() is used. See ipc/mqueue.c for more details
73 */
74
75/* one msg_receiver structure for each sleeping receiver */
76struct msg_receiver {
77 struct list_head r_list;
78 struct task_struct *r_tsk;
79
80 int r_mode;
81 long r_msgtype;
82 long r_maxsize;
83
84 struct msg_msg *r_msg;
85};
86
87/* one msg_sender for each sleeping sender */
88struct msg_sender {
89 struct list_head list;
90 struct task_struct *tsk;
91 size_t msgsz;
92};
93
94#define SEARCH_ANY 1
95#define SEARCH_EQUAL 2
96#define SEARCH_NOTEQUAL 3
97#define SEARCH_LESSEQUAL 4
98#define SEARCH_NUMBER 5
99
100#define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS])
101
102static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
103{
104 struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id);
105
106 if (IS_ERR(ipcp))
107 return ERR_CAST(ipcp);
108
109 return container_of(ipcp, struct msg_queue, q_perm);
110}
111
112static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
113 int id)
114{
115 struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
116
117 if (IS_ERR(ipcp))
118 return ERR_CAST(ipcp);
119
120 return container_of(ipcp, struct msg_queue, q_perm);
121}
122
123static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
124{
125 ipc_rmid(&msg_ids(ns), &s->q_perm);
126}
127
128static void msg_rcu_free(struct rcu_head *head)
129{
130 struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu);
131 struct msg_queue *msq = container_of(p, struct msg_queue, q_perm);
132
133 security_msg_queue_free(&msq->q_perm);
134 kfree(msq);
135}
136
137/**
138 * newque - Create a new msg queue
139 * @ns: namespace
140 * @params: ptr to the structure that contains the key and msgflg
141 *
142 * Called with msg_ids.rwsem held (writer)
143 */
144static int newque(struct ipc_namespace *ns, struct ipc_params *params)
145{
146 struct msg_queue *msq;
147 int retval;
148 key_t key = params->key;
149 int msgflg = params->flg;
150
151 msq = kmalloc(sizeof(*msq), GFP_KERNEL_ACCOUNT);
152 if (unlikely(!msq))
153 return -ENOMEM;
154
155 msq->q_perm.mode = msgflg & S_IRWXUGO;
156 msq->q_perm.key = key;
157
158 msq->q_perm.security = NULL;
159 retval = security_msg_queue_alloc(&msq->q_perm);
160 if (retval) {
161 kfree(msq);
162 return retval;
163 }
164
165 msq->q_stime = msq->q_rtime = 0;
166 msq->q_ctime = ktime_get_real_seconds();
167 msq->q_cbytes = msq->q_qnum = 0;
168 msq->q_qbytes = ns->msg_ctlmnb;
169 msq->q_lspid = msq->q_lrpid = NULL;
170 INIT_LIST_HEAD(&msq->q_messages);
171 INIT_LIST_HEAD(&msq->q_receivers);
172 INIT_LIST_HEAD(&msq->q_senders);
173
174 /* ipc_addid() locks msq upon success. */
175 retval = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
176 if (retval < 0) {
177 ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
178 return retval;
179 }
180
181 ipc_unlock_object(&msq->q_perm);
182 rcu_read_unlock();
183
184 return msq->q_perm.id;
185}
186
187static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz)
188{
189 return msgsz + msq->q_cbytes <= msq->q_qbytes &&
190 1 + msq->q_qnum <= msq->q_qbytes;
191}
192
193static inline void ss_add(struct msg_queue *msq,
194 struct msg_sender *mss, size_t msgsz)
195{
196 mss->tsk = current;
197 mss->msgsz = msgsz;
198 /*
199 * No memory barrier required: we did ipc_lock_object(),
200 * and the waker obtains that lock before calling wake_q_add().
201 */
202 __set_current_state(TASK_INTERRUPTIBLE);
203 list_add_tail(&mss->list, &msq->q_senders);
204}
205
206static inline void ss_del(struct msg_sender *mss)
207{
208 if (mss->list.next)
209 list_del(&mss->list);
210}
211
212static void ss_wakeup(struct msg_queue *msq,
213 struct wake_q_head *wake_q, bool kill)
214{
215 struct msg_sender *mss, *t;
216 struct task_struct *stop_tsk = NULL;
217 struct list_head *h = &msq->q_senders;
218
219 list_for_each_entry_safe(mss, t, h, list) {
220 if (kill)
221 mss->list.next = NULL;
222
223 /*
224 * Stop at the first task we don't wakeup,
225 * we've already iterated the original
226 * sender queue.
227 */
228 else if (stop_tsk == mss->tsk)
229 break;
230 /*
231 * We are not in an EIDRM scenario here, therefore
232 * verify that we really need to wakeup the task.
233 * To maintain current semantics and wakeup order,
234 * move the sender to the tail on behalf of the
235 * blocked task.
236 */
237 else if (!msg_fits_inqueue(msq, mss->msgsz)) {
238 if (!stop_tsk)
239 stop_tsk = mss->tsk;
240
241 list_move_tail(&mss->list, &msq->q_senders);
242 continue;
243 }
244
245 wake_q_add(wake_q, mss->tsk);
246 }
247}
248
249static void expunge_all(struct msg_queue *msq, int res,
250 struct wake_q_head *wake_q)
251{
252 struct msg_receiver *msr, *t;
253
254 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
255 struct task_struct *r_tsk;
256
257 r_tsk = get_task_struct(msr->r_tsk);
258
259 /* see MSG_BARRIER for purpose/pairing */
260 smp_store_release(&msr->r_msg, ERR_PTR(res));
261 wake_q_add_safe(wake_q, r_tsk);
262 }
263}
264
265/*
266 * freeque() wakes up waiters on the sender and receiver waiting queue,
267 * removes the message queue from message queue ID IDR, and cleans up all the
268 * messages associated with this queue.
269 *
270 * msg_ids.rwsem (writer) and the spinlock for this message queue are held
271 * before freeque() is called. msg_ids.rwsem remains locked on exit.
272 */
273static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
274 __releases(RCU)
275 __releases(&msq->q_perm)
276{
277 struct msg_msg *msg, *t;
278 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
279 DEFINE_WAKE_Q(wake_q);
280
281 expunge_all(msq, -EIDRM, &wake_q);
282 ss_wakeup(msq, &wake_q, true);
283 msg_rmid(ns, msq);
284 ipc_unlock_object(&msq->q_perm);
285 wake_up_q(&wake_q);
286 rcu_read_unlock();
287
288 list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
289 percpu_counter_sub_local(&ns->percpu_msg_hdrs, 1);
290 free_msg(msg);
291 }
292 percpu_counter_sub_local(&ns->percpu_msg_bytes, msq->q_cbytes);
293 ipc_update_pid(&msq->q_lspid, NULL);
294 ipc_update_pid(&msq->q_lrpid, NULL);
295 ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
296}
297
298long ksys_msgget(key_t key, int msgflg)
299{
300 struct ipc_namespace *ns;
301 static const struct ipc_ops msg_ops = {
302 .getnew = newque,
303 .associate = security_msg_queue_associate,
304 };
305 struct ipc_params msg_params;
306
307 ns = current->nsproxy->ipc_ns;
308
309 msg_params.key = key;
310 msg_params.flg = msgflg;
311
312 return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
313}
314
315SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
316{
317 return ksys_msgget(key, msgflg);
318}
319
320static inline unsigned long
321copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
322{
323 switch (version) {
324 case IPC_64:
325 return copy_to_user(buf, in, sizeof(*in));
326 case IPC_OLD:
327 {
328 struct msqid_ds out;
329
330 memset(&out, 0, sizeof(out));
331
332 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
333
334 out.msg_stime = in->msg_stime;
335 out.msg_rtime = in->msg_rtime;
336 out.msg_ctime = in->msg_ctime;
337
338 if (in->msg_cbytes > USHRT_MAX)
339 out.msg_cbytes = USHRT_MAX;
340 else
341 out.msg_cbytes = in->msg_cbytes;
342 out.msg_lcbytes = in->msg_cbytes;
343
344 if (in->msg_qnum > USHRT_MAX)
345 out.msg_qnum = USHRT_MAX;
346 else
347 out.msg_qnum = in->msg_qnum;
348
349 if (in->msg_qbytes > USHRT_MAX)
350 out.msg_qbytes = USHRT_MAX;
351 else
352 out.msg_qbytes = in->msg_qbytes;
353 out.msg_lqbytes = in->msg_qbytes;
354
355 out.msg_lspid = in->msg_lspid;
356 out.msg_lrpid = in->msg_lrpid;
357
358 return copy_to_user(buf, &out, sizeof(out));
359 }
360 default:
361 return -EINVAL;
362 }
363}
364
365static inline unsigned long
366copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
367{
368 switch (version) {
369 case IPC_64:
370 if (copy_from_user(out, buf, sizeof(*out)))
371 return -EFAULT;
372 return 0;
373 case IPC_OLD:
374 {
375 struct msqid_ds tbuf_old;
376
377 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
378 return -EFAULT;
379
380 out->msg_perm.uid = tbuf_old.msg_perm.uid;
381 out->msg_perm.gid = tbuf_old.msg_perm.gid;
382 out->msg_perm.mode = tbuf_old.msg_perm.mode;
383
384 if (tbuf_old.msg_qbytes == 0)
385 out->msg_qbytes = tbuf_old.msg_lqbytes;
386 else
387 out->msg_qbytes = tbuf_old.msg_qbytes;
388
389 return 0;
390 }
391 default:
392 return -EINVAL;
393 }
394}
395
396/*
397 * This function handles some msgctl commands which require the rwsem
398 * to be held in write mode.
399 * NOTE: no locks must be held, the rwsem is taken inside this function.
400 */
401static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
402 struct ipc64_perm *perm, int msg_qbytes)
403{
404 struct kern_ipc_perm *ipcp;
405 struct msg_queue *msq;
406 int err;
407
408 down_write(&msg_ids(ns).rwsem);
409 rcu_read_lock();
410
411 ipcp = ipcctl_obtain_check(ns, &msg_ids(ns), msqid, cmd,
412 perm, msg_qbytes);
413 if (IS_ERR(ipcp)) {
414 err = PTR_ERR(ipcp);
415 goto out_unlock1;
416 }
417
418 msq = container_of(ipcp, struct msg_queue, q_perm);
419
420 err = security_msg_queue_msgctl(&msq->q_perm, cmd);
421 if (err)
422 goto out_unlock1;
423
424 switch (cmd) {
425 case IPC_RMID:
426 ipc_lock_object(&msq->q_perm);
427 /* freeque unlocks the ipc object and rcu */
428 freeque(ns, ipcp);
429 goto out_up;
430 case IPC_SET:
431 {
432 DEFINE_WAKE_Q(wake_q);
433
434 if (msg_qbytes > ns->msg_ctlmnb &&
435 !capable(CAP_SYS_RESOURCE)) {
436 err = -EPERM;
437 goto out_unlock1;
438 }
439
440 ipc_lock_object(&msq->q_perm);
441 err = ipc_update_perm(perm, ipcp);
442 if (err)
443 goto out_unlock0;
444
445 msq->q_qbytes = msg_qbytes;
446
447 msq->q_ctime = ktime_get_real_seconds();
448 /*
449 * Sleeping receivers might be excluded by
450 * stricter permissions.
451 */
452 expunge_all(msq, -EAGAIN, &wake_q);
453 /*
454 * Sleeping senders might be able to send
455 * due to a larger queue size.
456 */
457 ss_wakeup(msq, &wake_q, false);
458 ipc_unlock_object(&msq->q_perm);
459 wake_up_q(&wake_q);
460
461 goto out_unlock1;
462 }
463 default:
464 err = -EINVAL;
465 goto out_unlock1;
466 }
467
468out_unlock0:
469 ipc_unlock_object(&msq->q_perm);
470out_unlock1:
471 rcu_read_unlock();
472out_up:
473 up_write(&msg_ids(ns).rwsem);
474 return err;
475}
476
477static int msgctl_info(struct ipc_namespace *ns, int msqid,
478 int cmd, struct msginfo *msginfo)
479{
480 int err;
481 int max_idx;
482
483 /*
484 * We must not return kernel stack data.
485 * due to padding, it's not enough
486 * to set all member fields.
487 */
488 err = security_msg_queue_msgctl(NULL, cmd);
489 if (err)
490 return err;
491
492 memset(msginfo, 0, sizeof(*msginfo));
493 msginfo->msgmni = ns->msg_ctlmni;
494 msginfo->msgmax = ns->msg_ctlmax;
495 msginfo->msgmnb = ns->msg_ctlmnb;
496 msginfo->msgssz = MSGSSZ;
497 msginfo->msgseg = MSGSEG;
498 down_read(&msg_ids(ns).rwsem);
499 if (cmd == MSG_INFO)
500 msginfo->msgpool = msg_ids(ns).in_use;
501 max_idx = ipc_get_maxidx(&msg_ids(ns));
502 up_read(&msg_ids(ns).rwsem);
503 if (cmd == MSG_INFO) {
504 msginfo->msgmap = min_t(int,
505 percpu_counter_sum(&ns->percpu_msg_hdrs),
506 INT_MAX);
507 msginfo->msgtql = min_t(int,
508 percpu_counter_sum(&ns->percpu_msg_bytes),
509 INT_MAX);
510 } else {
511 msginfo->msgmap = MSGMAP;
512 msginfo->msgpool = MSGPOOL;
513 msginfo->msgtql = MSGTQL;
514 }
515 return (max_idx < 0) ? 0 : max_idx;
516}
517
518static int msgctl_stat(struct ipc_namespace *ns, int msqid,
519 int cmd, struct msqid64_ds *p)
520{
521 struct msg_queue *msq;
522 int err;
523
524 memset(p, 0, sizeof(*p));
525
526 rcu_read_lock();
527 if (cmd == MSG_STAT || cmd == MSG_STAT_ANY) {
528 msq = msq_obtain_object(ns, msqid);
529 if (IS_ERR(msq)) {
530 err = PTR_ERR(msq);
531 goto out_unlock;
532 }
533 } else { /* IPC_STAT */
534 msq = msq_obtain_object_check(ns, msqid);
535 if (IS_ERR(msq)) {
536 err = PTR_ERR(msq);
537 goto out_unlock;
538 }
539 }
540
541 /* see comment for SHM_STAT_ANY */
542 if (cmd == MSG_STAT_ANY)
543 audit_ipc_obj(&msq->q_perm);
544 else {
545 err = -EACCES;
546 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
547 goto out_unlock;
548 }
549
550 err = security_msg_queue_msgctl(&msq->q_perm, cmd);
551 if (err)
552 goto out_unlock;
553
554 ipc_lock_object(&msq->q_perm);
555
556 if (!ipc_valid_object(&msq->q_perm)) {
557 ipc_unlock_object(&msq->q_perm);
558 err = -EIDRM;
559 goto out_unlock;
560 }
561
562 kernel_to_ipc64_perm(&msq->q_perm, &p->msg_perm);
563 p->msg_stime = msq->q_stime;
564 p->msg_rtime = msq->q_rtime;
565 p->msg_ctime = msq->q_ctime;
566#ifndef CONFIG_64BIT
567 p->msg_stime_high = msq->q_stime >> 32;
568 p->msg_rtime_high = msq->q_rtime >> 32;
569 p->msg_ctime_high = msq->q_ctime >> 32;
570#endif
571 p->msg_cbytes = msq->q_cbytes;
572 p->msg_qnum = msq->q_qnum;
573 p->msg_qbytes = msq->q_qbytes;
574 p->msg_lspid = pid_vnr(msq->q_lspid);
575 p->msg_lrpid = pid_vnr(msq->q_lrpid);
576
577 if (cmd == IPC_STAT) {
578 /*
579 * As defined in SUS:
580 * Return 0 on success
581 */
582 err = 0;
583 } else {
584 /*
585 * MSG_STAT and MSG_STAT_ANY (both Linux specific)
586 * Return the full id, including the sequence number
587 */
588 err = msq->q_perm.id;
589 }
590
591 ipc_unlock_object(&msq->q_perm);
592out_unlock:
593 rcu_read_unlock();
594 return err;
595}
596
597static long ksys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf, int version)
598{
599 struct ipc_namespace *ns;
600 struct msqid64_ds msqid64;
601 int err;
602
603 if (msqid < 0 || cmd < 0)
604 return -EINVAL;
605
606 ns = current->nsproxy->ipc_ns;
607
608 switch (cmd) {
609 case IPC_INFO:
610 case MSG_INFO: {
611 struct msginfo msginfo;
612 err = msgctl_info(ns, msqid, cmd, &msginfo);
613 if (err < 0)
614 return err;
615 if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
616 err = -EFAULT;
617 return err;
618 }
619 case MSG_STAT: /* msqid is an index rather than a msg queue id */
620 case MSG_STAT_ANY:
621 case IPC_STAT:
622 err = msgctl_stat(ns, msqid, cmd, &msqid64);
623 if (err < 0)
624 return err;
625 if (copy_msqid_to_user(buf, &msqid64, version))
626 err = -EFAULT;
627 return err;
628 case IPC_SET:
629 if (copy_msqid_from_user(&msqid64, buf, version))
630 return -EFAULT;
631 return msgctl_down(ns, msqid, cmd, &msqid64.msg_perm,
632 msqid64.msg_qbytes);
633 case IPC_RMID:
634 return msgctl_down(ns, msqid, cmd, NULL, 0);
635 default:
636 return -EINVAL;
637 }
638}
639
640SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
641{
642 return ksys_msgctl(msqid, cmd, buf, IPC_64);
643}
644
645#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
646long ksys_old_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
647{
648 int version = ipc_parse_version(&cmd);
649
650 return ksys_msgctl(msqid, cmd, buf, version);
651}
652
653SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
654{
655 return ksys_old_msgctl(msqid, cmd, buf);
656}
657#endif
658
659#ifdef CONFIG_COMPAT
660
661struct compat_msqid_ds {
662 struct compat_ipc_perm msg_perm;
663 compat_uptr_t msg_first;
664 compat_uptr_t msg_last;
665 old_time32_t msg_stime;
666 old_time32_t msg_rtime;
667 old_time32_t msg_ctime;
668 compat_ulong_t msg_lcbytes;
669 compat_ulong_t msg_lqbytes;
670 unsigned short msg_cbytes;
671 unsigned short msg_qnum;
672 unsigned short msg_qbytes;
673 compat_ipc_pid_t msg_lspid;
674 compat_ipc_pid_t msg_lrpid;
675};
676
677static int copy_compat_msqid_from_user(struct msqid64_ds *out, void __user *buf,
678 int version)
679{
680 memset(out, 0, sizeof(*out));
681 if (version == IPC_64) {
682 struct compat_msqid64_ds __user *p = buf;
683 if (get_compat_ipc64_perm(&out->msg_perm, &p->msg_perm))
684 return -EFAULT;
685 if (get_user(out->msg_qbytes, &p->msg_qbytes))
686 return -EFAULT;
687 } else {
688 struct compat_msqid_ds __user *p = buf;
689 if (get_compat_ipc_perm(&out->msg_perm, &p->msg_perm))
690 return -EFAULT;
691 if (get_user(out->msg_qbytes, &p->msg_qbytes))
692 return -EFAULT;
693 }
694 return 0;
695}
696
697static int copy_compat_msqid_to_user(void __user *buf, struct msqid64_ds *in,
698 int version)
699{
700 if (version == IPC_64) {
701 struct compat_msqid64_ds v;
702 memset(&v, 0, sizeof(v));
703 to_compat_ipc64_perm(&v.msg_perm, &in->msg_perm);
704 v.msg_stime = lower_32_bits(in->msg_stime);
705 v.msg_stime_high = upper_32_bits(in->msg_stime);
706 v.msg_rtime = lower_32_bits(in->msg_rtime);
707 v.msg_rtime_high = upper_32_bits(in->msg_rtime);
708 v.msg_ctime = lower_32_bits(in->msg_ctime);
709 v.msg_ctime_high = upper_32_bits(in->msg_ctime);
710 v.msg_cbytes = in->msg_cbytes;
711 v.msg_qnum = in->msg_qnum;
712 v.msg_qbytes = in->msg_qbytes;
713 v.msg_lspid = in->msg_lspid;
714 v.msg_lrpid = in->msg_lrpid;
715 return copy_to_user(buf, &v, sizeof(v));
716 } else {
717 struct compat_msqid_ds v;
718 memset(&v, 0, sizeof(v));
719 to_compat_ipc_perm(&v.msg_perm, &in->msg_perm);
720 v.msg_stime = in->msg_stime;
721 v.msg_rtime = in->msg_rtime;
722 v.msg_ctime = in->msg_ctime;
723 v.msg_cbytes = in->msg_cbytes;
724 v.msg_qnum = in->msg_qnum;
725 v.msg_qbytes = in->msg_qbytes;
726 v.msg_lspid = in->msg_lspid;
727 v.msg_lrpid = in->msg_lrpid;
728 return copy_to_user(buf, &v, sizeof(v));
729 }
730}
731
732static long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr, int version)
733{
734 struct ipc_namespace *ns;
735 int err;
736 struct msqid64_ds msqid64;
737
738 ns = current->nsproxy->ipc_ns;
739
740 if (msqid < 0 || cmd < 0)
741 return -EINVAL;
742
743 switch (cmd & (~IPC_64)) {
744 case IPC_INFO:
745 case MSG_INFO: {
746 struct msginfo msginfo;
747 err = msgctl_info(ns, msqid, cmd, &msginfo);
748 if (err < 0)
749 return err;
750 if (copy_to_user(uptr, &msginfo, sizeof(struct msginfo)))
751 err = -EFAULT;
752 return err;
753 }
754 case IPC_STAT:
755 case MSG_STAT:
756 case MSG_STAT_ANY:
757 err = msgctl_stat(ns, msqid, cmd, &msqid64);
758 if (err < 0)
759 return err;
760 if (copy_compat_msqid_to_user(uptr, &msqid64, version))
761 err = -EFAULT;
762 return err;
763 case IPC_SET:
764 if (copy_compat_msqid_from_user(&msqid64, uptr, version))
765 return -EFAULT;
766 return msgctl_down(ns, msqid, cmd, &msqid64.msg_perm, msqid64.msg_qbytes);
767 case IPC_RMID:
768 return msgctl_down(ns, msqid, cmd, NULL, 0);
769 default:
770 return -EINVAL;
771 }
772}
773
774COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr)
775{
776 return compat_ksys_msgctl(msqid, cmd, uptr, IPC_64);
777}
778
779#ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
780long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr)
781{
782 int version = compat_ipc_parse_version(&cmd);
783
784 return compat_ksys_msgctl(msqid, cmd, uptr, version);
785}
786
787COMPAT_SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, void __user *, uptr)
788{
789 return compat_ksys_old_msgctl(msqid, cmd, uptr);
790}
791#endif
792#endif
793
794static int testmsg(struct msg_msg *msg, long type, int mode)
795{
796 switch (mode) {
797 case SEARCH_ANY:
798 case SEARCH_NUMBER:
799 return 1;
800 case SEARCH_LESSEQUAL:
801 if (msg->m_type <= type)
802 return 1;
803 break;
804 case SEARCH_EQUAL:
805 if (msg->m_type == type)
806 return 1;
807 break;
808 case SEARCH_NOTEQUAL:
809 if (msg->m_type != type)
810 return 1;
811 break;
812 }
813 return 0;
814}
815
816static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg,
817 struct wake_q_head *wake_q)
818{
819 struct msg_receiver *msr, *t;
820
821 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
822 if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
823 !security_msg_queue_msgrcv(&msq->q_perm, msg, msr->r_tsk,
824 msr->r_msgtype, msr->r_mode)) {
825
826 list_del(&msr->r_list);
827 if (msr->r_maxsize < msg->m_ts) {
828 wake_q_add(wake_q, msr->r_tsk);
829
830 /* See expunge_all regarding memory barrier */
831 smp_store_release(&msr->r_msg, ERR_PTR(-E2BIG));
832 } else {
833 ipc_update_pid(&msq->q_lrpid, task_pid(msr->r_tsk));
834 msq->q_rtime = ktime_get_real_seconds();
835
836 wake_q_add(wake_q, msr->r_tsk);
837
838 /* See expunge_all regarding memory barrier */
839 smp_store_release(&msr->r_msg, msg);
840 return 1;
841 }
842 }
843 }
844
845 return 0;
846}
847
848static long do_msgsnd(int msqid, long mtype, void __user *mtext,
849 size_t msgsz, int msgflg)
850{
851 struct msg_queue *msq;
852 struct msg_msg *msg;
853 int err;
854 struct ipc_namespace *ns;
855 DEFINE_WAKE_Q(wake_q);
856
857 ns = current->nsproxy->ipc_ns;
858
859 if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
860 return -EINVAL;
861 if (mtype < 1)
862 return -EINVAL;
863
864 msg = load_msg(mtext, msgsz);
865 if (IS_ERR(msg))
866 return PTR_ERR(msg);
867
868 msg->m_type = mtype;
869 msg->m_ts = msgsz;
870
871 rcu_read_lock();
872 msq = msq_obtain_object_check(ns, msqid);
873 if (IS_ERR(msq)) {
874 err = PTR_ERR(msq);
875 goto out_unlock1;
876 }
877
878 ipc_lock_object(&msq->q_perm);
879
880 for (;;) {
881 struct msg_sender s;
882
883 err = -EACCES;
884 if (ipcperms(ns, &msq->q_perm, S_IWUGO))
885 goto out_unlock0;
886
887 /* raced with RMID? */
888 if (!ipc_valid_object(&msq->q_perm)) {
889 err = -EIDRM;
890 goto out_unlock0;
891 }
892
893 err = security_msg_queue_msgsnd(&msq->q_perm, msg, msgflg);
894 if (err)
895 goto out_unlock0;
896
897 if (msg_fits_inqueue(msq, msgsz))
898 break;
899
900 /* queue full, wait: */
901 if (msgflg & IPC_NOWAIT) {
902 err = -EAGAIN;
903 goto out_unlock0;
904 }
905
906 /* enqueue the sender and prepare to block */
907 ss_add(msq, &s, msgsz);
908
909 if (!ipc_rcu_getref(&msq->q_perm)) {
910 err = -EIDRM;
911 goto out_unlock0;
912 }
913
914 ipc_unlock_object(&msq->q_perm);
915 rcu_read_unlock();
916 schedule();
917
918 rcu_read_lock();
919 ipc_lock_object(&msq->q_perm);
920
921 ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
922 /* raced with RMID? */
923 if (!ipc_valid_object(&msq->q_perm)) {
924 err = -EIDRM;
925 goto out_unlock0;
926 }
927 ss_del(&s);
928
929 if (signal_pending(current)) {
930 err = -ERESTARTNOHAND;
931 goto out_unlock0;
932 }
933
934 }
935
936 ipc_update_pid(&msq->q_lspid, task_tgid(current));
937 msq->q_stime = ktime_get_real_seconds();
938
939 if (!pipelined_send(msq, msg, &wake_q)) {
940 /* no one is waiting for this message, enqueue it */
941 list_add_tail(&msg->m_list, &msq->q_messages);
942 msq->q_cbytes += msgsz;
943 msq->q_qnum++;
944 percpu_counter_add_local(&ns->percpu_msg_bytes, msgsz);
945 percpu_counter_add_local(&ns->percpu_msg_hdrs, 1);
946 }
947
948 err = 0;
949 msg = NULL;
950
951out_unlock0:
952 ipc_unlock_object(&msq->q_perm);
953 wake_up_q(&wake_q);
954out_unlock1:
955 rcu_read_unlock();
956 if (msg != NULL)
957 free_msg(msg);
958 return err;
959}
960
961long ksys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz,
962 int msgflg)
963{
964 long mtype;
965
966 if (get_user(mtype, &msgp->mtype))
967 return -EFAULT;
968 return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
969}
970
971SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
972 int, msgflg)
973{
974 return ksys_msgsnd(msqid, msgp, msgsz, msgflg);
975}
976
977#ifdef CONFIG_COMPAT
978
979struct compat_msgbuf {
980 compat_long_t mtype;
981 char mtext[];
982};
983
984long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
985 compat_ssize_t msgsz, int msgflg)
986{
987 struct compat_msgbuf __user *up = compat_ptr(msgp);
988 compat_long_t mtype;
989
990 if (get_user(mtype, &up->mtype))
991 return -EFAULT;
992 return do_msgsnd(msqid, mtype, up->mtext, (ssize_t)msgsz, msgflg);
993}
994
995COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp,
996 compat_ssize_t, msgsz, int, msgflg)
997{
998 return compat_ksys_msgsnd(msqid, msgp, msgsz, msgflg);
999}
1000#endif
1001
1002static inline int convert_mode(long *msgtyp, int msgflg)
1003{
1004 if (msgflg & MSG_COPY)
1005 return SEARCH_NUMBER;
1006 /*
1007 * find message of correct type.
1008 * msgtyp = 0 => get first.
1009 * msgtyp > 0 => get first message of matching type.
1010 * msgtyp < 0 => get message with least type must be < abs(msgtype).
1011 */
1012 if (*msgtyp == 0)
1013 return SEARCH_ANY;
1014 if (*msgtyp < 0) {
1015 if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */
1016 *msgtyp = LONG_MAX;
1017 else
1018 *msgtyp = -*msgtyp;
1019 return SEARCH_LESSEQUAL;
1020 }
1021 if (msgflg & MSG_EXCEPT)
1022 return SEARCH_NOTEQUAL;
1023 return SEARCH_EQUAL;
1024}
1025
1026static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
1027{
1028 struct msgbuf __user *msgp = dest;
1029 size_t msgsz;
1030
1031 if (put_user(msg->m_type, &msgp->mtype))
1032 return -EFAULT;
1033
1034 msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
1035 if (store_msg(msgp->mtext, msg, msgsz))
1036 return -EFAULT;
1037 return msgsz;
1038}
1039
1040#ifdef CONFIG_CHECKPOINT_RESTORE
1041/*
1042 * This function creates new kernel message structure, large enough to store
1043 * bufsz message bytes.
1044 */
1045static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
1046{
1047 struct msg_msg *copy;
1048
1049 /*
1050 * Create dummy message to copy real message to.
1051 */
1052 copy = load_msg(buf, bufsz);
1053 if (!IS_ERR(copy))
1054 copy->m_ts = bufsz;
1055 return copy;
1056}
1057
1058static inline void free_copy(struct msg_msg *copy)
1059{
1060 if (copy)
1061 free_msg(copy);
1062}
1063#else
1064static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
1065{
1066 return ERR_PTR(-ENOSYS);
1067}
1068
1069static inline void free_copy(struct msg_msg *copy)
1070{
1071}
1072#endif
1073
1074static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
1075{
1076 struct msg_msg *msg, *found = NULL;
1077 long count = 0;
1078
1079 list_for_each_entry(msg, &msq->q_messages, m_list) {
1080 if (testmsg(msg, *msgtyp, mode) &&
1081 !security_msg_queue_msgrcv(&msq->q_perm, msg, current,
1082 *msgtyp, mode)) {
1083 if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
1084 *msgtyp = msg->m_type - 1;
1085 found = msg;
1086 } else if (mode == SEARCH_NUMBER) {
1087 if (*msgtyp == count)
1088 return msg;
1089 } else
1090 return msg;
1091 count++;
1092 }
1093 }
1094
1095 return found ?: ERR_PTR(-EAGAIN);
1096}
1097
1098static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
1099 long (*msg_handler)(void __user *, struct msg_msg *, size_t))
1100{
1101 int mode;
1102 struct msg_queue *msq;
1103 struct ipc_namespace *ns;
1104 struct msg_msg *msg, *copy = NULL;
1105 DEFINE_WAKE_Q(wake_q);
1106
1107 ns = current->nsproxy->ipc_ns;
1108
1109 if (msqid < 0 || (long) bufsz < 0)
1110 return -EINVAL;
1111
1112 if (msgflg & MSG_COPY) {
1113 if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
1114 return -EINVAL;
1115 copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
1116 if (IS_ERR(copy))
1117 return PTR_ERR(copy);
1118 }
1119 mode = convert_mode(&msgtyp, msgflg);
1120
1121 rcu_read_lock();
1122 msq = msq_obtain_object_check(ns, msqid);
1123 if (IS_ERR(msq)) {
1124 rcu_read_unlock();
1125 free_copy(copy);
1126 return PTR_ERR(msq);
1127 }
1128
1129 for (;;) {
1130 struct msg_receiver msr_d;
1131
1132 msg = ERR_PTR(-EACCES);
1133 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
1134 goto out_unlock1;
1135
1136 ipc_lock_object(&msq->q_perm);
1137
1138 /* raced with RMID? */
1139 if (!ipc_valid_object(&msq->q_perm)) {
1140 msg = ERR_PTR(-EIDRM);
1141 goto out_unlock0;
1142 }
1143
1144 msg = find_msg(msq, &msgtyp, mode);
1145 if (!IS_ERR(msg)) {
1146 /*
1147 * Found a suitable message.
1148 * Unlink it from the queue.
1149 */
1150 if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
1151 msg = ERR_PTR(-E2BIG);
1152 goto out_unlock0;
1153 }
1154 /*
1155 * If we are copying, then do not unlink message and do
1156 * not update queue parameters.
1157 */
1158 if (msgflg & MSG_COPY) {
1159 msg = copy_msg(msg, copy);
1160 goto out_unlock0;
1161 }
1162
1163 list_del(&msg->m_list);
1164 msq->q_qnum--;
1165 msq->q_rtime = ktime_get_real_seconds();
1166 ipc_update_pid(&msq->q_lrpid, task_tgid(current));
1167 msq->q_cbytes -= msg->m_ts;
1168 percpu_counter_sub_local(&ns->percpu_msg_bytes, msg->m_ts);
1169 percpu_counter_sub_local(&ns->percpu_msg_hdrs, 1);
1170 ss_wakeup(msq, &wake_q, false);
1171
1172 goto out_unlock0;
1173 }
1174
1175 /* No message waiting. Wait for a message */
1176 if (msgflg & IPC_NOWAIT) {
1177 msg = ERR_PTR(-ENOMSG);
1178 goto out_unlock0;
1179 }
1180
1181 list_add_tail(&msr_d.r_list, &msq->q_receivers);
1182 msr_d.r_tsk = current;
1183 msr_d.r_msgtype = msgtyp;
1184 msr_d.r_mode = mode;
1185 if (msgflg & MSG_NOERROR)
1186 msr_d.r_maxsize = INT_MAX;
1187 else
1188 msr_d.r_maxsize = bufsz;
1189
1190 /* memory barrier not require due to ipc_lock_object() */
1191 WRITE_ONCE(msr_d.r_msg, ERR_PTR(-EAGAIN));
1192
1193 /* memory barrier not required, we own ipc_lock_object() */
1194 __set_current_state(TASK_INTERRUPTIBLE);
1195
1196 ipc_unlock_object(&msq->q_perm);
1197 rcu_read_unlock();
1198 schedule();
1199
1200 /*
1201 * Lockless receive, part 1:
1202 * We don't hold a reference to the queue and getting a
1203 * reference would defeat the idea of a lockless operation,
1204 * thus the code relies on rcu to guarantee the existence of
1205 * msq:
1206 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
1207 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
1208 */
1209 rcu_read_lock();
1210
1211 /*
1212 * Lockless receive, part 2:
1213 * The work in pipelined_send() and expunge_all():
1214 * - Set pointer to message
1215 * - Queue the receiver task for later wakeup
1216 * - Wake up the process after the lock is dropped.
1217 *
1218 * Should the process wake up before this wakeup (due to a
1219 * signal) it will either see the message and continue ...
1220 */
1221 msg = READ_ONCE(msr_d.r_msg);
1222 if (msg != ERR_PTR(-EAGAIN)) {
1223 /* see MSG_BARRIER for purpose/pairing */
1224 smp_acquire__after_ctrl_dep();
1225
1226 goto out_unlock1;
1227 }
1228
1229 /*
1230 * ... or see -EAGAIN, acquire the lock to check the message
1231 * again.
1232 */
1233 ipc_lock_object(&msq->q_perm);
1234
1235 msg = READ_ONCE(msr_d.r_msg);
1236 if (msg != ERR_PTR(-EAGAIN))
1237 goto out_unlock0;
1238
1239 list_del(&msr_d.r_list);
1240 if (signal_pending(current)) {
1241 msg = ERR_PTR(-ERESTARTNOHAND);
1242 goto out_unlock0;
1243 }
1244
1245 ipc_unlock_object(&msq->q_perm);
1246 }
1247
1248out_unlock0:
1249 ipc_unlock_object(&msq->q_perm);
1250 wake_up_q(&wake_q);
1251out_unlock1:
1252 rcu_read_unlock();
1253 if (IS_ERR(msg)) {
1254 free_copy(copy);
1255 return PTR_ERR(msg);
1256 }
1257
1258 bufsz = msg_handler(buf, msg, bufsz);
1259 free_msg(msg);
1260
1261 return bufsz;
1262}
1263
1264long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,
1265 long msgtyp, int msgflg)
1266{
1267 return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1268}
1269
1270SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1271 long, msgtyp, int, msgflg)
1272{
1273 return ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
1274}
1275
1276#ifdef CONFIG_COMPAT
1277static long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
1278{
1279 struct compat_msgbuf __user *msgp = dest;
1280 size_t msgsz;
1281
1282 if (put_user(msg->m_type, &msgp->mtype))
1283 return -EFAULT;
1284
1285 msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
1286 if (store_msg(msgp->mtext, msg, msgsz))
1287 return -EFAULT;
1288 return msgsz;
1289}
1290
1291long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
1292 compat_long_t msgtyp, int msgflg)
1293{
1294 return do_msgrcv(msqid, compat_ptr(msgp), (ssize_t)msgsz, (long)msgtyp,
1295 msgflg, compat_do_msg_fill);
1296}
1297
1298COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp,
1299 compat_ssize_t, msgsz, compat_long_t, msgtyp,
1300 int, msgflg)
1301{
1302 return compat_ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
1303}
1304#endif
1305
1306int msg_init_ns(struct ipc_namespace *ns)
1307{
1308 int ret;
1309
1310 ns->msg_ctlmax = MSGMAX;
1311 ns->msg_ctlmnb = MSGMNB;
1312 ns->msg_ctlmni = MSGMNI;
1313
1314 ret = percpu_counter_init(&ns->percpu_msg_bytes, 0, GFP_KERNEL);
1315 if (ret)
1316 goto fail_msg_bytes;
1317 ret = percpu_counter_init(&ns->percpu_msg_hdrs, 0, GFP_KERNEL);
1318 if (ret)
1319 goto fail_msg_hdrs;
1320 ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
1321 return 0;
1322
1323fail_msg_hdrs:
1324 percpu_counter_destroy(&ns->percpu_msg_bytes);
1325fail_msg_bytes:
1326 return ret;
1327}
1328
1329#ifdef CONFIG_IPC_NS
1330void msg_exit_ns(struct ipc_namespace *ns)
1331{
1332 free_ipcs(ns, &msg_ids(ns), freeque);
1333 idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
1334 rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht);
1335 percpu_counter_destroy(&ns->percpu_msg_bytes);
1336 percpu_counter_destroy(&ns->percpu_msg_hdrs);
1337}
1338#endif
1339
1340#ifdef CONFIG_PROC_FS
1341static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1342{
1343 struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
1344 struct user_namespace *user_ns = seq_user_ns(s);
1345 struct kern_ipc_perm *ipcp = it;
1346 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
1347
1348 seq_printf(s,
1349 "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10llu %10llu %10llu\n",
1350 msq->q_perm.key,
1351 msq->q_perm.id,
1352 msq->q_perm.mode,
1353 msq->q_cbytes,
1354 msq->q_qnum,
1355 pid_nr_ns(msq->q_lspid, pid_ns),
1356 pid_nr_ns(msq->q_lrpid, pid_ns),
1357 from_kuid_munged(user_ns, msq->q_perm.uid),
1358 from_kgid_munged(user_ns, msq->q_perm.gid),
1359 from_kuid_munged(user_ns, msq->q_perm.cuid),
1360 from_kgid_munged(user_ns, msq->q_perm.cgid),
1361 msq->q_stime,
1362 msq->q_rtime,
1363 msq->q_ctime);
1364
1365 return 0;
1366}
1367#endif
1368
1369void __init msg_init(void)
1370{
1371 msg_init_ns(&init_ipc_ns);
1372
1373 ipc_init_proc_interface("sysvipc/msg",
1374 " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n",
1375 IPC_MSG_IDS, sysvipc_msg_proc_show);
1376}