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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 /*
55 * Mark r_msg volatile so that the compiler
56 * does not try to get smart and optimize
57 * it. We rely on this for the lockless
58 * receive algorithm.
59 */
60 struct msg_msg *volatile r_msg;
61};
62
63/* one msg_sender for each sleeping sender */
64struct msg_sender {
65 struct list_head list;
66 struct task_struct *tsk;
67};
68
69#define SEARCH_ANY 1
70#define SEARCH_EQUAL 2
71#define SEARCH_NOTEQUAL 3
72#define SEARCH_LESSEQUAL 4
73#define SEARCH_NUMBER 5
74
75#define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS])
76
77static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
78{
79 struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id);
80
81 if (IS_ERR(ipcp))
82 return ERR_CAST(ipcp);
83
84 return container_of(ipcp, struct msg_queue, q_perm);
85}
86
87static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
88 int id)
89{
90 struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
91
92 if (IS_ERR(ipcp))
93 return ERR_CAST(ipcp);
94
95 return container_of(ipcp, struct msg_queue, q_perm);
96}
97
98static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
99{
100 ipc_rmid(&msg_ids(ns), &s->q_perm);
101}
102
103static void msg_rcu_free(struct rcu_head *head)
104{
105 struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
106 struct msg_queue *msq = ipc_rcu_to_struct(p);
107
108 security_msg_queue_free(msq);
109 ipc_rcu_free(head);
110}
111
112/**
113 * newque - Create a new msg queue
114 * @ns: namespace
115 * @params: ptr to the structure that contains the key and msgflg
116 *
117 * Called with msg_ids.rwsem held (writer)
118 */
119static int newque(struct ipc_namespace *ns, struct ipc_params *params)
120{
121 struct msg_queue *msq;
122 int id, retval;
123 key_t key = params->key;
124 int msgflg = params->flg;
125
126 msq = ipc_rcu_alloc(sizeof(*msq));
127 if (!msq)
128 return -ENOMEM;
129
130 msq->q_perm.mode = msgflg & S_IRWXUGO;
131 msq->q_perm.key = key;
132
133 msq->q_perm.security = NULL;
134 retval = security_msg_queue_alloc(msq);
135 if (retval) {
136 ipc_rcu_putref(msq, ipc_rcu_free);
137 return retval;
138 }
139
140 msq->q_stime = msq->q_rtime = 0;
141 msq->q_ctime = get_seconds();
142 msq->q_cbytes = msq->q_qnum = 0;
143 msq->q_qbytes = ns->msg_ctlmnb;
144 msq->q_lspid = msq->q_lrpid = 0;
145 INIT_LIST_HEAD(&msq->q_messages);
146 INIT_LIST_HEAD(&msq->q_receivers);
147 INIT_LIST_HEAD(&msq->q_senders);
148
149 /* ipc_addid() locks msq upon success. */
150 id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
151 if (id < 0) {
152 ipc_rcu_putref(msq, msg_rcu_free);
153 return id;
154 }
155
156 ipc_unlock_object(&msq->q_perm);
157 rcu_read_unlock();
158
159 return msq->q_perm.id;
160}
161
162static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss)
163{
164 mss->tsk = current;
165 __set_current_state(TASK_INTERRUPTIBLE);
166 list_add_tail(&mss->list, &msq->q_senders);
167}
168
169static inline void ss_del(struct msg_sender *mss)
170{
171 if (mss->list.next != NULL)
172 list_del(&mss->list);
173}
174
175static void ss_wakeup(struct list_head *h, int kill)
176{
177 struct msg_sender *mss, *t;
178
179 list_for_each_entry_safe(mss, t, h, list) {
180 if (kill)
181 mss->list.next = NULL;
182 wake_up_process(mss->tsk);
183 }
184}
185
186static void expunge_all(struct msg_queue *msq, int res)
187{
188 struct msg_receiver *msr, *t;
189
190 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
191 msr->r_msg = NULL; /* initialize expunge ordering */
192 wake_up_process(msr->r_tsk);
193 /*
194 * Ensure that the wakeup is visible before setting r_msg as
195 * the receiving end depends on it: either spinning on a nil,
196 * or dealing with -EAGAIN cases. See lockless receive part 1
197 * and 2 in do_msgrcv().
198 */
199 smp_wmb(); /* barrier (B) */
200 msr->r_msg = ERR_PTR(res);
201 }
202}
203
204/*
205 * freeque() wakes up waiters on the sender and receiver waiting queue,
206 * removes the message queue from message queue ID IDR, and cleans up all the
207 * messages associated with this queue.
208 *
209 * msg_ids.rwsem (writer) and the spinlock for this message queue are held
210 * before freeque() is called. msg_ids.rwsem remains locked on exit.
211 */
212static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
213{
214 struct msg_msg *msg, *t;
215 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
216
217 expunge_all(msq, -EIDRM);
218 ss_wakeup(&msq->q_senders, 1);
219 msg_rmid(ns, msq);
220 ipc_unlock_object(&msq->q_perm);
221 rcu_read_unlock();
222
223 list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
224 atomic_dec(&ns->msg_hdrs);
225 free_msg(msg);
226 }
227 atomic_sub(msq->q_cbytes, &ns->msg_bytes);
228 ipc_rcu_putref(msq, msg_rcu_free);
229}
230
231/*
232 * Called with msg_ids.rwsem and ipcp locked.
233 */
234static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
235{
236 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
237
238 return security_msg_queue_associate(msq, msgflg);
239}
240
241SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
242{
243 struct ipc_namespace *ns;
244 static const struct ipc_ops msg_ops = {
245 .getnew = newque,
246 .associate = msg_security,
247 };
248 struct ipc_params msg_params;
249
250 ns = current->nsproxy->ipc_ns;
251
252 msg_params.key = key;
253 msg_params.flg = msgflg;
254
255 return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
256}
257
258static inline unsigned long
259copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
260{
261 switch (version) {
262 case IPC_64:
263 return copy_to_user(buf, in, sizeof(*in));
264 case IPC_OLD:
265 {
266 struct msqid_ds out;
267
268 memset(&out, 0, sizeof(out));
269
270 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
271
272 out.msg_stime = in->msg_stime;
273 out.msg_rtime = in->msg_rtime;
274 out.msg_ctime = in->msg_ctime;
275
276 if (in->msg_cbytes > USHRT_MAX)
277 out.msg_cbytes = USHRT_MAX;
278 else
279 out.msg_cbytes = in->msg_cbytes;
280 out.msg_lcbytes = in->msg_cbytes;
281
282 if (in->msg_qnum > USHRT_MAX)
283 out.msg_qnum = USHRT_MAX;
284 else
285 out.msg_qnum = in->msg_qnum;
286
287 if (in->msg_qbytes > USHRT_MAX)
288 out.msg_qbytes = USHRT_MAX;
289 else
290 out.msg_qbytes = in->msg_qbytes;
291 out.msg_lqbytes = in->msg_qbytes;
292
293 out.msg_lspid = in->msg_lspid;
294 out.msg_lrpid = in->msg_lrpid;
295
296 return copy_to_user(buf, &out, sizeof(out));
297 }
298 default:
299 return -EINVAL;
300 }
301}
302
303static inline unsigned long
304copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
305{
306 switch (version) {
307 case IPC_64:
308 if (copy_from_user(out, buf, sizeof(*out)))
309 return -EFAULT;
310 return 0;
311 case IPC_OLD:
312 {
313 struct msqid_ds tbuf_old;
314
315 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
316 return -EFAULT;
317
318 out->msg_perm.uid = tbuf_old.msg_perm.uid;
319 out->msg_perm.gid = tbuf_old.msg_perm.gid;
320 out->msg_perm.mode = tbuf_old.msg_perm.mode;
321
322 if (tbuf_old.msg_qbytes == 0)
323 out->msg_qbytes = tbuf_old.msg_lqbytes;
324 else
325 out->msg_qbytes = tbuf_old.msg_qbytes;
326
327 return 0;
328 }
329 default:
330 return -EINVAL;
331 }
332}
333
334/*
335 * This function handles some msgctl commands which require the rwsem
336 * to be held in write mode.
337 * NOTE: no locks must be held, the rwsem is taken inside this function.
338 */
339static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
340 struct msqid_ds __user *buf, int version)
341{
342 struct kern_ipc_perm *ipcp;
343 struct msqid64_ds uninitialized_var(msqid64);
344 struct msg_queue *msq;
345 int err;
346
347 if (cmd == IPC_SET) {
348 if (copy_msqid_from_user(&msqid64, buf, version))
349 return -EFAULT;
350 }
351
352 down_write(&msg_ids(ns).rwsem);
353 rcu_read_lock();
354
355 ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
356 &msqid64.msg_perm, msqid64.msg_qbytes);
357 if (IS_ERR(ipcp)) {
358 err = PTR_ERR(ipcp);
359 goto out_unlock1;
360 }
361
362 msq = container_of(ipcp, struct msg_queue, q_perm);
363
364 err = security_msg_queue_msgctl(msq, cmd);
365 if (err)
366 goto out_unlock1;
367
368 switch (cmd) {
369 case IPC_RMID:
370 ipc_lock_object(&msq->q_perm);
371 /* freeque unlocks the ipc object and rcu */
372 freeque(ns, ipcp);
373 goto out_up;
374 case IPC_SET:
375 if (msqid64.msg_qbytes > ns->msg_ctlmnb &&
376 !capable(CAP_SYS_RESOURCE)) {
377 err = -EPERM;
378 goto out_unlock1;
379 }
380
381 ipc_lock_object(&msq->q_perm);
382 err = ipc_update_perm(&msqid64.msg_perm, ipcp);
383 if (err)
384 goto out_unlock0;
385
386 msq->q_qbytes = msqid64.msg_qbytes;
387
388 msq->q_ctime = get_seconds();
389 /* sleeping receivers might be excluded by
390 * stricter permissions.
391 */
392 expunge_all(msq, -EAGAIN);
393 /* sleeping senders might be able to send
394 * due to a larger queue size.
395 */
396 ss_wakeup(&msq->q_senders, 0);
397 break;
398 default:
399 err = -EINVAL;
400 goto out_unlock1;
401 }
402
403out_unlock0:
404 ipc_unlock_object(&msq->q_perm);
405out_unlock1:
406 rcu_read_unlock();
407out_up:
408 up_write(&msg_ids(ns).rwsem);
409 return err;
410}
411
412static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
413 int cmd, int version, void __user *buf)
414{
415 int err;
416 struct msg_queue *msq;
417
418 switch (cmd) {
419 case IPC_INFO:
420 case MSG_INFO:
421 {
422 struct msginfo msginfo;
423 int max_id;
424
425 if (!buf)
426 return -EFAULT;
427
428 /*
429 * We must not return kernel stack data.
430 * due to padding, it's not enough
431 * to set all member fields.
432 */
433 err = security_msg_queue_msgctl(NULL, cmd);
434 if (err)
435 return err;
436
437 memset(&msginfo, 0, sizeof(msginfo));
438 msginfo.msgmni = ns->msg_ctlmni;
439 msginfo.msgmax = ns->msg_ctlmax;
440 msginfo.msgmnb = ns->msg_ctlmnb;
441 msginfo.msgssz = MSGSSZ;
442 msginfo.msgseg = MSGSEG;
443 down_read(&msg_ids(ns).rwsem);
444 if (cmd == MSG_INFO) {
445 msginfo.msgpool = msg_ids(ns).in_use;
446 msginfo.msgmap = atomic_read(&ns->msg_hdrs);
447 msginfo.msgtql = atomic_read(&ns->msg_bytes);
448 } else {
449 msginfo.msgmap = MSGMAP;
450 msginfo.msgpool = MSGPOOL;
451 msginfo.msgtql = MSGTQL;
452 }
453 max_id = ipc_get_maxid(&msg_ids(ns));
454 up_read(&msg_ids(ns).rwsem);
455 if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
456 return -EFAULT;
457 return (max_id < 0) ? 0 : max_id;
458 }
459
460 case MSG_STAT:
461 case IPC_STAT:
462 {
463 struct msqid64_ds tbuf;
464 int success_return;
465
466 if (!buf)
467 return -EFAULT;
468
469 memset(&tbuf, 0, sizeof(tbuf));
470
471 rcu_read_lock();
472 if (cmd == MSG_STAT) {
473 msq = msq_obtain_object(ns, msqid);
474 if (IS_ERR(msq)) {
475 err = PTR_ERR(msq);
476 goto out_unlock;
477 }
478 success_return = msq->q_perm.id;
479 } else {
480 msq = msq_obtain_object_check(ns, msqid);
481 if (IS_ERR(msq)) {
482 err = PTR_ERR(msq);
483 goto out_unlock;
484 }
485 success_return = 0;
486 }
487
488 err = -EACCES;
489 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
490 goto out_unlock;
491
492 err = security_msg_queue_msgctl(msq, cmd);
493 if (err)
494 goto out_unlock;
495
496 kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
497 tbuf.msg_stime = msq->q_stime;
498 tbuf.msg_rtime = msq->q_rtime;
499 tbuf.msg_ctime = msq->q_ctime;
500 tbuf.msg_cbytes = msq->q_cbytes;
501 tbuf.msg_qnum = msq->q_qnum;
502 tbuf.msg_qbytes = msq->q_qbytes;
503 tbuf.msg_lspid = msq->q_lspid;
504 tbuf.msg_lrpid = msq->q_lrpid;
505 rcu_read_unlock();
506
507 if (copy_msqid_to_user(buf, &tbuf, version))
508 return -EFAULT;
509 return success_return;
510 }
511
512 default:
513 return -EINVAL;
514 }
515
516 return err;
517out_unlock:
518 rcu_read_unlock();
519 return err;
520}
521
522SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
523{
524 int version;
525 struct ipc_namespace *ns;
526
527 if (msqid < 0 || cmd < 0)
528 return -EINVAL;
529
530 version = ipc_parse_version(&cmd);
531 ns = current->nsproxy->ipc_ns;
532
533 switch (cmd) {
534 case IPC_INFO:
535 case MSG_INFO:
536 case MSG_STAT: /* msqid is an index rather than a msg queue id */
537 case IPC_STAT:
538 return msgctl_nolock(ns, msqid, cmd, version, buf);
539 case IPC_SET:
540 case IPC_RMID:
541 return msgctl_down(ns, msqid, cmd, buf, version);
542 default:
543 return -EINVAL;
544 }
545}
546
547static int testmsg(struct msg_msg *msg, long type, int mode)
548{
549 switch (mode) {
550 case SEARCH_ANY:
551 case SEARCH_NUMBER:
552 return 1;
553 case SEARCH_LESSEQUAL:
554 if (msg->m_type <= type)
555 return 1;
556 break;
557 case SEARCH_EQUAL:
558 if (msg->m_type == type)
559 return 1;
560 break;
561 case SEARCH_NOTEQUAL:
562 if (msg->m_type != type)
563 return 1;
564 break;
565 }
566 return 0;
567}
568
569static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg)
570{
571 struct msg_receiver *msr, *t;
572
573 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
574 if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
575 !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
576 msr->r_msgtype, msr->r_mode)) {
577
578 list_del(&msr->r_list);
579 if (msr->r_maxsize < msg->m_ts) {
580 /* initialize pipelined send ordering */
581 msr->r_msg = NULL;
582 wake_up_process(msr->r_tsk);
583 /* barrier (B) see barrier comment below */
584 smp_wmb();
585 msr->r_msg = ERR_PTR(-E2BIG);
586 } else {
587 msr->r_msg = NULL;
588 msq->q_lrpid = task_pid_vnr(msr->r_tsk);
589 msq->q_rtime = get_seconds();
590 wake_up_process(msr->r_tsk);
591 /*
592 * Ensure that the wakeup is visible before
593 * setting r_msg, as the receiving can otherwise
594 * exit - once r_msg is set, the receiver can
595 * continue. See lockless receive part 1 and 2
596 * in do_msgrcv(). Barrier (B).
597 */
598 smp_wmb();
599 msr->r_msg = msg;
600
601 return 1;
602 }
603 }
604 }
605
606 return 0;
607}
608
609long do_msgsnd(int msqid, long mtype, void __user *mtext,
610 size_t msgsz, int msgflg)
611{
612 struct msg_queue *msq;
613 struct msg_msg *msg;
614 int err;
615 struct ipc_namespace *ns;
616
617 ns = current->nsproxy->ipc_ns;
618
619 if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
620 return -EINVAL;
621 if (mtype < 1)
622 return -EINVAL;
623
624 msg = load_msg(mtext, msgsz);
625 if (IS_ERR(msg))
626 return PTR_ERR(msg);
627
628 msg->m_type = mtype;
629 msg->m_ts = msgsz;
630
631 rcu_read_lock();
632 msq = msq_obtain_object_check(ns, msqid);
633 if (IS_ERR(msq)) {
634 err = PTR_ERR(msq);
635 goto out_unlock1;
636 }
637
638 ipc_lock_object(&msq->q_perm);
639
640 for (;;) {
641 struct msg_sender s;
642
643 err = -EACCES;
644 if (ipcperms(ns, &msq->q_perm, S_IWUGO))
645 goto out_unlock0;
646
647 /* raced with RMID? */
648 if (!ipc_valid_object(&msq->q_perm)) {
649 err = -EIDRM;
650 goto out_unlock0;
651 }
652
653 err = security_msg_queue_msgsnd(msq, msg, msgflg);
654 if (err)
655 goto out_unlock0;
656
657 if (msgsz + msq->q_cbytes <= msq->q_qbytes &&
658 1 + msq->q_qnum <= msq->q_qbytes) {
659 break;
660 }
661
662 /* queue full, wait: */
663 if (msgflg & IPC_NOWAIT) {
664 err = -EAGAIN;
665 goto out_unlock0;
666 }
667
668 /* enqueue the sender and prepare to block */
669 ss_add(msq, &s);
670
671 if (!ipc_rcu_getref(msq)) {
672 err = -EIDRM;
673 goto out_unlock0;
674 }
675
676 ipc_unlock_object(&msq->q_perm);
677 rcu_read_unlock();
678 schedule();
679
680 rcu_read_lock();
681 ipc_lock_object(&msq->q_perm);
682
683 ipc_rcu_putref(msq, ipc_rcu_free);
684 /* raced with RMID? */
685 if (!ipc_valid_object(&msq->q_perm)) {
686 err = -EIDRM;
687 goto out_unlock0;
688 }
689
690 ss_del(&s);
691
692 if (signal_pending(current)) {
693 err = -ERESTARTNOHAND;
694 goto out_unlock0;
695 }
696
697 }
698 msq->q_lspid = task_tgid_vnr(current);
699 msq->q_stime = get_seconds();
700
701 if (!pipelined_send(msq, msg)) {
702 /* no one is waiting for this message, enqueue it */
703 list_add_tail(&msg->m_list, &msq->q_messages);
704 msq->q_cbytes += msgsz;
705 msq->q_qnum++;
706 atomic_add(msgsz, &ns->msg_bytes);
707 atomic_inc(&ns->msg_hdrs);
708 }
709
710 err = 0;
711 msg = NULL;
712
713out_unlock0:
714 ipc_unlock_object(&msq->q_perm);
715out_unlock1:
716 rcu_read_unlock();
717 if (msg != NULL)
718 free_msg(msg);
719 return err;
720}
721
722SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
723 int, msgflg)
724{
725 long mtype;
726
727 if (get_user(mtype, &msgp->mtype))
728 return -EFAULT;
729 return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
730}
731
732static inline int convert_mode(long *msgtyp, int msgflg)
733{
734 if (msgflg & MSG_COPY)
735 return SEARCH_NUMBER;
736 /*
737 * find message of correct type.
738 * msgtyp = 0 => get first.
739 * msgtyp > 0 => get first message of matching type.
740 * msgtyp < 0 => get message with least type must be < abs(msgtype).
741 */
742 if (*msgtyp == 0)
743 return SEARCH_ANY;
744 if (*msgtyp < 0) {
745 *msgtyp = -*msgtyp;
746 return SEARCH_LESSEQUAL;
747 }
748 if (msgflg & MSG_EXCEPT)
749 return SEARCH_NOTEQUAL;
750 return SEARCH_EQUAL;
751}
752
753static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
754{
755 struct msgbuf __user *msgp = dest;
756 size_t msgsz;
757
758 if (put_user(msg->m_type, &msgp->mtype))
759 return -EFAULT;
760
761 msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
762 if (store_msg(msgp->mtext, msg, msgsz))
763 return -EFAULT;
764 return msgsz;
765}
766
767#ifdef CONFIG_CHECKPOINT_RESTORE
768/*
769 * This function creates new kernel message structure, large enough to store
770 * bufsz message bytes.
771 */
772static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
773{
774 struct msg_msg *copy;
775
776 /*
777 * Create dummy message to copy real message to.
778 */
779 copy = load_msg(buf, bufsz);
780 if (!IS_ERR(copy))
781 copy->m_ts = bufsz;
782 return copy;
783}
784
785static inline void free_copy(struct msg_msg *copy)
786{
787 if (copy)
788 free_msg(copy);
789}
790#else
791static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
792{
793 return ERR_PTR(-ENOSYS);
794}
795
796static inline void free_copy(struct msg_msg *copy)
797{
798}
799#endif
800
801static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
802{
803 struct msg_msg *msg, *found = NULL;
804 long count = 0;
805
806 list_for_each_entry(msg, &msq->q_messages, m_list) {
807 if (testmsg(msg, *msgtyp, mode) &&
808 !security_msg_queue_msgrcv(msq, msg, current,
809 *msgtyp, mode)) {
810 if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
811 *msgtyp = msg->m_type - 1;
812 found = msg;
813 } else if (mode == SEARCH_NUMBER) {
814 if (*msgtyp == count)
815 return msg;
816 } else
817 return msg;
818 count++;
819 }
820 }
821
822 return found ?: ERR_PTR(-EAGAIN);
823}
824
825long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
826 long (*msg_handler)(void __user *, struct msg_msg *, size_t))
827{
828 int mode;
829 struct msg_queue *msq;
830 struct ipc_namespace *ns;
831 struct msg_msg *msg, *copy = NULL;
832
833 ns = current->nsproxy->ipc_ns;
834
835 if (msqid < 0 || (long) bufsz < 0)
836 return -EINVAL;
837
838 if (msgflg & MSG_COPY) {
839 if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
840 return -EINVAL;
841 copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
842 if (IS_ERR(copy))
843 return PTR_ERR(copy);
844 }
845 mode = convert_mode(&msgtyp, msgflg);
846
847 rcu_read_lock();
848 msq = msq_obtain_object_check(ns, msqid);
849 if (IS_ERR(msq)) {
850 rcu_read_unlock();
851 free_copy(copy);
852 return PTR_ERR(msq);
853 }
854
855 for (;;) {
856 struct msg_receiver msr_d;
857
858 msg = ERR_PTR(-EACCES);
859 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
860 goto out_unlock1;
861
862 ipc_lock_object(&msq->q_perm);
863
864 /* raced with RMID? */
865 if (!ipc_valid_object(&msq->q_perm)) {
866 msg = ERR_PTR(-EIDRM);
867 goto out_unlock0;
868 }
869
870 msg = find_msg(msq, &msgtyp, mode);
871 if (!IS_ERR(msg)) {
872 /*
873 * Found a suitable message.
874 * Unlink it from the queue.
875 */
876 if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
877 msg = ERR_PTR(-E2BIG);
878 goto out_unlock0;
879 }
880 /*
881 * If we are copying, then do not unlink message and do
882 * not update queue parameters.
883 */
884 if (msgflg & MSG_COPY) {
885 msg = copy_msg(msg, copy);
886 goto out_unlock0;
887 }
888
889 list_del(&msg->m_list);
890 msq->q_qnum--;
891 msq->q_rtime = get_seconds();
892 msq->q_lrpid = task_tgid_vnr(current);
893 msq->q_cbytes -= msg->m_ts;
894 atomic_sub(msg->m_ts, &ns->msg_bytes);
895 atomic_dec(&ns->msg_hdrs);
896 ss_wakeup(&msq->q_senders, 0);
897
898 goto out_unlock0;
899 }
900
901 /* No message waiting. Wait for a message */
902 if (msgflg & IPC_NOWAIT) {
903 msg = ERR_PTR(-ENOMSG);
904 goto out_unlock0;
905 }
906
907 list_add_tail(&msr_d.r_list, &msq->q_receivers);
908 msr_d.r_tsk = current;
909 msr_d.r_msgtype = msgtyp;
910 msr_d.r_mode = mode;
911 if (msgflg & MSG_NOERROR)
912 msr_d.r_maxsize = INT_MAX;
913 else
914 msr_d.r_maxsize = bufsz;
915 msr_d.r_msg = ERR_PTR(-EAGAIN);
916 __set_current_state(TASK_INTERRUPTIBLE);
917
918 ipc_unlock_object(&msq->q_perm);
919 rcu_read_unlock();
920 schedule();
921
922 /* Lockless receive, part 1:
923 * Disable preemption. We don't hold a reference to the queue
924 * and getting a reference would defeat the idea of a lockless
925 * operation, thus the code relies on rcu to guarantee the
926 * existence of msq:
927 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
928 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
929 * rcu_read_lock() prevents preemption between reading r_msg
930 * and acquiring the q_perm.lock in ipc_lock_object().
931 */
932 rcu_read_lock();
933
934 /* Lockless receive, part 2:
935 * Wait until pipelined_send or expunge_all are outside of
936 * wake_up_process(). There is a race with exit(), see
937 * ipc/mqueue.c for the details. The correct serialization
938 * ensures that a receiver cannot continue without the wakeup
939 * being visibible _before_ setting r_msg:
940 *
941 * CPU 0 CPU 1
942 * <loop receiver>
943 * smp_rmb(); (A) <-- pair -. <waker thread>
944 * <load ->r_msg> | msr->r_msg = NULL;
945 * | wake_up_process();
946 * <continue> `------> smp_wmb(); (B)
947 * msr->r_msg = msg;
948 *
949 * Where (A) orders the message value read and where (B) orders
950 * the write to the r_msg -- done in both pipelined_send and
951 * expunge_all.
952 */
953 for (;;) {
954 /*
955 * Pairs with writer barrier in pipelined_send
956 * or expunge_all.
957 */
958 smp_rmb(); /* barrier (A) */
959 msg = (struct msg_msg *)msr_d.r_msg;
960 if (msg)
961 break;
962
963 /*
964 * The cpu_relax() call is a compiler barrier
965 * which forces everything in this loop to be
966 * re-loaded.
967 */
968 cpu_relax();
969 }
970
971 /* Lockless receive, part 3:
972 * If there is a message or an error then accept it without
973 * locking.
974 */
975 if (msg != ERR_PTR(-EAGAIN))
976 goto out_unlock1;
977
978 /* Lockless receive, part 3:
979 * Acquire the queue spinlock.
980 */
981 ipc_lock_object(&msq->q_perm);
982
983 /* Lockless receive, part 4:
984 * Repeat test after acquiring the spinlock.
985 */
986 msg = (struct msg_msg *)msr_d.r_msg;
987 if (msg != ERR_PTR(-EAGAIN))
988 goto out_unlock0;
989
990 list_del(&msr_d.r_list);
991 if (signal_pending(current)) {
992 msg = ERR_PTR(-ERESTARTNOHAND);
993 goto out_unlock0;
994 }
995
996 ipc_unlock_object(&msq->q_perm);
997 }
998
999out_unlock0:
1000 ipc_unlock_object(&msq->q_perm);
1001out_unlock1:
1002 rcu_read_unlock();
1003 if (IS_ERR(msg)) {
1004 free_copy(copy);
1005 return PTR_ERR(msg);
1006 }
1007
1008 bufsz = msg_handler(buf, msg, bufsz);
1009 free_msg(msg);
1010
1011 return bufsz;
1012}
1013
1014SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1015 long, msgtyp, int, msgflg)
1016{
1017 return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1018}
1019
1020
1021void msg_init_ns(struct ipc_namespace *ns)
1022{
1023 ns->msg_ctlmax = MSGMAX;
1024 ns->msg_ctlmnb = MSGMNB;
1025 ns->msg_ctlmni = MSGMNI;
1026
1027 atomic_set(&ns->msg_bytes, 0);
1028 atomic_set(&ns->msg_hdrs, 0);
1029 ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
1030}
1031
1032#ifdef CONFIG_IPC_NS
1033void msg_exit_ns(struct ipc_namespace *ns)
1034{
1035 free_ipcs(ns, &msg_ids(ns), freeque);
1036 idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
1037}
1038#endif
1039
1040#ifdef CONFIG_PROC_FS
1041static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1042{
1043 struct user_namespace *user_ns = seq_user_ns(s);
1044 struct msg_queue *msq = it;
1045
1046 seq_printf(s,
1047 "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
1048 msq->q_perm.key,
1049 msq->q_perm.id,
1050 msq->q_perm.mode,
1051 msq->q_cbytes,
1052 msq->q_qnum,
1053 msq->q_lspid,
1054 msq->q_lrpid,
1055 from_kuid_munged(user_ns, msq->q_perm.uid),
1056 from_kgid_munged(user_ns, msq->q_perm.gid),
1057 from_kuid_munged(user_ns, msq->q_perm.cuid),
1058 from_kgid_munged(user_ns, msq->q_perm.cgid),
1059 msq->q_stime,
1060 msq->q_rtime,
1061 msq->q_ctime);
1062
1063 return 0;
1064}
1065#endif
1066
1067void __init msg_init(void)
1068{
1069 msg_init_ns(&init_ipc_ns);
1070
1071 ipc_init_proc_interface("sysvipc/msg",
1072 " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n",
1073 IPC_MSG_IDS, sysvipc_msg_proc_show);
1074}
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 <asm/uaccess.h>
43#include "util.h"
44
45/*
46 * one msg_receiver structure for each sleeping receiver:
47 */
48struct msg_receiver {
49 struct list_head r_list;
50 struct task_struct *r_tsk;
51
52 int r_mode;
53 long r_msgtype;
54 long r_maxsize;
55
56 struct msg_msg *volatile r_msg;
57};
58
59/* one msg_sender for each sleeping sender */
60struct msg_sender {
61 struct list_head list;
62 struct task_struct *tsk;
63};
64
65#define SEARCH_ANY 1
66#define SEARCH_EQUAL 2
67#define SEARCH_NOTEQUAL 3
68#define SEARCH_LESSEQUAL 4
69#define SEARCH_NUMBER 5
70
71#define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS])
72
73static void freeque(struct ipc_namespace *, struct kern_ipc_perm *);
74static int newque(struct ipc_namespace *, struct ipc_params *);
75#ifdef CONFIG_PROC_FS
76static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
77#endif
78
79/*
80 * Scale msgmni with the available lowmem size: the memory dedicated to msg
81 * queues should occupy at most 1/MSG_MEM_SCALE of lowmem.
82 * Also take into account the number of nsproxies created so far.
83 * This should be done staying within the (MSGMNI , IPCMNI/nr_ipc_ns) range.
84 */
85void recompute_msgmni(struct ipc_namespace *ns)
86{
87 struct sysinfo i;
88 unsigned long allowed;
89 int nb_ns;
90
91 si_meminfo(&i);
92 allowed = (((i.totalram - i.totalhigh) / MSG_MEM_SCALE) * i.mem_unit)
93 / MSGMNB;
94 nb_ns = atomic_read(&nr_ipc_ns);
95 allowed /= nb_ns;
96
97 if (allowed < MSGMNI) {
98 ns->msg_ctlmni = MSGMNI;
99 return;
100 }
101
102 if (allowed > IPCMNI / nb_ns) {
103 ns->msg_ctlmni = IPCMNI / nb_ns;
104 return;
105 }
106
107 ns->msg_ctlmni = allowed;
108}
109
110void msg_init_ns(struct ipc_namespace *ns)
111{
112 ns->msg_ctlmax = MSGMAX;
113 ns->msg_ctlmnb = MSGMNB;
114
115 recompute_msgmni(ns);
116
117 atomic_set(&ns->msg_bytes, 0);
118 atomic_set(&ns->msg_hdrs, 0);
119 ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
120}
121
122#ifdef CONFIG_IPC_NS
123void msg_exit_ns(struct ipc_namespace *ns)
124{
125 free_ipcs(ns, &msg_ids(ns), freeque);
126 idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
127}
128#endif
129
130void __init msg_init(void)
131{
132 msg_init_ns(&init_ipc_ns);
133
134 printk(KERN_INFO "msgmni has been set to %d\n",
135 init_ipc_ns.msg_ctlmni);
136
137 ipc_init_proc_interface("sysvipc/msg",
138 " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n",
139 IPC_MSG_IDS, sysvipc_msg_proc_show);
140}
141
142static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
143{
144 struct kern_ipc_perm *ipcp = ipc_obtain_object(&msg_ids(ns), id);
145
146 if (IS_ERR(ipcp))
147 return ERR_CAST(ipcp);
148
149 return container_of(ipcp, struct msg_queue, q_perm);
150}
151
152static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
153 int id)
154{
155 struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
156
157 if (IS_ERR(ipcp))
158 return ERR_CAST(ipcp);
159
160 return container_of(ipcp, struct msg_queue, q_perm);
161}
162
163static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
164{
165 ipc_rmid(&msg_ids(ns), &s->q_perm);
166}
167
168static void msg_rcu_free(struct rcu_head *head)
169{
170 struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
171 struct msg_queue *msq = ipc_rcu_to_struct(p);
172
173 security_msg_queue_free(msq);
174 ipc_rcu_free(head);
175}
176
177/**
178 * newque - Create a new msg queue
179 * @ns: namespace
180 * @params: ptr to the structure that contains the key and msgflg
181 *
182 * Called with msg_ids.rwsem held (writer)
183 */
184static int newque(struct ipc_namespace *ns, struct ipc_params *params)
185{
186 struct msg_queue *msq;
187 int id, retval;
188 key_t key = params->key;
189 int msgflg = params->flg;
190
191 msq = ipc_rcu_alloc(sizeof(*msq));
192 if (!msq)
193 return -ENOMEM;
194
195 msq->q_perm.mode = msgflg & S_IRWXUGO;
196 msq->q_perm.key = key;
197
198 msq->q_perm.security = NULL;
199 retval = security_msg_queue_alloc(msq);
200 if (retval) {
201 ipc_rcu_putref(msq, ipc_rcu_free);
202 return retval;
203 }
204
205 /* ipc_addid() locks msq upon success. */
206 id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
207 if (id < 0) {
208 ipc_rcu_putref(msq, msg_rcu_free);
209 return id;
210 }
211
212 msq->q_stime = msq->q_rtime = 0;
213 msq->q_ctime = get_seconds();
214 msq->q_cbytes = msq->q_qnum = 0;
215 msq->q_qbytes = ns->msg_ctlmnb;
216 msq->q_lspid = msq->q_lrpid = 0;
217 INIT_LIST_HEAD(&msq->q_messages);
218 INIT_LIST_HEAD(&msq->q_receivers);
219 INIT_LIST_HEAD(&msq->q_senders);
220
221 ipc_unlock_object(&msq->q_perm);
222 rcu_read_unlock();
223
224 return msq->q_perm.id;
225}
226
227static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss)
228{
229 mss->tsk = current;
230 current->state = TASK_INTERRUPTIBLE;
231 list_add_tail(&mss->list, &msq->q_senders);
232}
233
234static inline void ss_del(struct msg_sender *mss)
235{
236 if (mss->list.next != NULL)
237 list_del(&mss->list);
238}
239
240static void ss_wakeup(struct list_head *h, int kill)
241{
242 struct msg_sender *mss, *t;
243
244 list_for_each_entry_safe(mss, t, h, list) {
245 if (kill)
246 mss->list.next = NULL;
247 wake_up_process(mss->tsk);
248 }
249}
250
251static void expunge_all(struct msg_queue *msq, int res)
252{
253 struct msg_receiver *msr, *t;
254
255 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
256 msr->r_msg = NULL; /* initialize expunge ordering */
257 wake_up_process(msr->r_tsk);
258 /*
259 * Ensure that the wakeup is visible before setting r_msg as
260 * the receiving end depends on it: either spinning on a nil,
261 * or dealing with -EAGAIN cases. See lockless receive part 1
262 * and 2 in do_msgrcv().
263 */
264 smp_mb();
265 msr->r_msg = ERR_PTR(res);
266 }
267}
268
269/*
270 * freeque() wakes up waiters on the sender and receiver waiting queue,
271 * removes the message queue from message queue ID IDR, and cleans up all the
272 * messages associated with this queue.
273 *
274 * msg_ids.rwsem (writer) and the spinlock for this message queue are held
275 * before freeque() is called. msg_ids.rwsem remains locked on exit.
276 */
277static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
278{
279 struct msg_msg *msg, *t;
280 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
281
282 expunge_all(msq, -EIDRM);
283 ss_wakeup(&msq->q_senders, 1);
284 msg_rmid(ns, msq);
285 ipc_unlock_object(&msq->q_perm);
286 rcu_read_unlock();
287
288 list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
289 atomic_dec(&ns->msg_hdrs);
290 free_msg(msg);
291 }
292 atomic_sub(msq->q_cbytes, &ns->msg_bytes);
293 ipc_rcu_putref(msq, msg_rcu_free);
294}
295
296/*
297 * Called with msg_ids.rwsem and ipcp locked.
298 */
299static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
300{
301 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
302
303 return security_msg_queue_associate(msq, msgflg);
304}
305
306SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
307{
308 struct ipc_namespace *ns;
309 struct ipc_ops msg_ops;
310 struct ipc_params msg_params;
311
312 ns = current->nsproxy->ipc_ns;
313
314 msg_ops.getnew = newque;
315 msg_ops.associate = msg_security;
316 msg_ops.more_checks = NULL;
317
318 msg_params.key = key;
319 msg_params.flg = msgflg;
320
321 return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
322}
323
324static inline unsigned long
325copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
326{
327 switch (version) {
328 case IPC_64:
329 return copy_to_user(buf, in, sizeof(*in));
330 case IPC_OLD:
331 {
332 struct msqid_ds out;
333
334 memset(&out, 0, sizeof(out));
335
336 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
337
338 out.msg_stime = in->msg_stime;
339 out.msg_rtime = in->msg_rtime;
340 out.msg_ctime = in->msg_ctime;
341
342 if (in->msg_cbytes > USHRT_MAX)
343 out.msg_cbytes = USHRT_MAX;
344 else
345 out.msg_cbytes = in->msg_cbytes;
346 out.msg_lcbytes = in->msg_cbytes;
347
348 if (in->msg_qnum > USHRT_MAX)
349 out.msg_qnum = USHRT_MAX;
350 else
351 out.msg_qnum = in->msg_qnum;
352
353 if (in->msg_qbytes > USHRT_MAX)
354 out.msg_qbytes = USHRT_MAX;
355 else
356 out.msg_qbytes = in->msg_qbytes;
357 out.msg_lqbytes = in->msg_qbytes;
358
359 out.msg_lspid = in->msg_lspid;
360 out.msg_lrpid = in->msg_lrpid;
361
362 return copy_to_user(buf, &out, sizeof(out));
363 }
364 default:
365 return -EINVAL;
366 }
367}
368
369static inline unsigned long
370copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
371{
372 switch (version) {
373 case IPC_64:
374 if (copy_from_user(out, buf, sizeof(*out)))
375 return -EFAULT;
376 return 0;
377 case IPC_OLD:
378 {
379 struct msqid_ds tbuf_old;
380
381 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
382 return -EFAULT;
383
384 out->msg_perm.uid = tbuf_old.msg_perm.uid;
385 out->msg_perm.gid = tbuf_old.msg_perm.gid;
386 out->msg_perm.mode = tbuf_old.msg_perm.mode;
387
388 if (tbuf_old.msg_qbytes == 0)
389 out->msg_qbytes = tbuf_old.msg_lqbytes;
390 else
391 out->msg_qbytes = tbuf_old.msg_qbytes;
392
393 return 0;
394 }
395 default:
396 return -EINVAL;
397 }
398}
399
400/*
401 * This function handles some msgctl commands which require the rwsem
402 * to be held in write mode.
403 * NOTE: no locks must be held, the rwsem is taken inside this function.
404 */
405static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
406 struct msqid_ds __user *buf, int version)
407{
408 struct kern_ipc_perm *ipcp;
409 struct msqid64_ds uninitialized_var(msqid64);
410 struct msg_queue *msq;
411 int err;
412
413 if (cmd == IPC_SET) {
414 if (copy_msqid_from_user(&msqid64, buf, version))
415 return -EFAULT;
416 }
417
418 down_write(&msg_ids(ns).rwsem);
419 rcu_read_lock();
420
421 ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
422 &msqid64.msg_perm, msqid64.msg_qbytes);
423 if (IS_ERR(ipcp)) {
424 err = PTR_ERR(ipcp);
425 goto out_unlock1;
426 }
427
428 msq = container_of(ipcp, struct msg_queue, q_perm);
429
430 err = security_msg_queue_msgctl(msq, cmd);
431 if (err)
432 goto out_unlock1;
433
434 switch (cmd) {
435 case IPC_RMID:
436 ipc_lock_object(&msq->q_perm);
437 /* freeque unlocks the ipc object and rcu */
438 freeque(ns, ipcp);
439 goto out_up;
440 case IPC_SET:
441 if (msqid64.msg_qbytes > ns->msg_ctlmnb &&
442 !capable(CAP_SYS_RESOURCE)) {
443 err = -EPERM;
444 goto out_unlock1;
445 }
446
447 ipc_lock_object(&msq->q_perm);
448 err = ipc_update_perm(&msqid64.msg_perm, ipcp);
449 if (err)
450 goto out_unlock0;
451
452 msq->q_qbytes = msqid64.msg_qbytes;
453
454 msq->q_ctime = get_seconds();
455 /* sleeping receivers might be excluded by
456 * stricter permissions.
457 */
458 expunge_all(msq, -EAGAIN);
459 /* sleeping senders might be able to send
460 * due to a larger queue size.
461 */
462 ss_wakeup(&msq->q_senders, 0);
463 break;
464 default:
465 err = -EINVAL;
466 goto out_unlock1;
467 }
468
469out_unlock0:
470 ipc_unlock_object(&msq->q_perm);
471out_unlock1:
472 rcu_read_unlock();
473out_up:
474 up_write(&msg_ids(ns).rwsem);
475 return err;
476}
477
478static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
479 int cmd, int version, void __user *buf)
480{
481 int err;
482 struct msg_queue *msq;
483
484 switch (cmd) {
485 case IPC_INFO:
486 case MSG_INFO:
487 {
488 struct msginfo msginfo;
489 int max_id;
490
491 if (!buf)
492 return -EFAULT;
493
494 /*
495 * We must not return kernel stack data.
496 * due to padding, it's not enough
497 * to set all member fields.
498 */
499 err = security_msg_queue_msgctl(NULL, cmd);
500 if (err)
501 return err;
502
503 memset(&msginfo, 0, sizeof(msginfo));
504 msginfo.msgmni = ns->msg_ctlmni;
505 msginfo.msgmax = ns->msg_ctlmax;
506 msginfo.msgmnb = ns->msg_ctlmnb;
507 msginfo.msgssz = MSGSSZ;
508 msginfo.msgseg = MSGSEG;
509 down_read(&msg_ids(ns).rwsem);
510 if (cmd == MSG_INFO) {
511 msginfo.msgpool = msg_ids(ns).in_use;
512 msginfo.msgmap = atomic_read(&ns->msg_hdrs);
513 msginfo.msgtql = atomic_read(&ns->msg_bytes);
514 } else {
515 msginfo.msgmap = MSGMAP;
516 msginfo.msgpool = MSGPOOL;
517 msginfo.msgtql = MSGTQL;
518 }
519 max_id = ipc_get_maxid(&msg_ids(ns));
520 up_read(&msg_ids(ns).rwsem);
521 if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
522 return -EFAULT;
523 return (max_id < 0) ? 0 : max_id;
524 }
525
526 case MSG_STAT:
527 case IPC_STAT:
528 {
529 struct msqid64_ds tbuf;
530 int success_return;
531
532 if (!buf)
533 return -EFAULT;
534
535 memset(&tbuf, 0, sizeof(tbuf));
536
537 rcu_read_lock();
538 if (cmd == MSG_STAT) {
539 msq = msq_obtain_object(ns, msqid);
540 if (IS_ERR(msq)) {
541 err = PTR_ERR(msq);
542 goto out_unlock;
543 }
544 success_return = msq->q_perm.id;
545 } else {
546 msq = msq_obtain_object_check(ns, msqid);
547 if (IS_ERR(msq)) {
548 err = PTR_ERR(msq);
549 goto out_unlock;
550 }
551 success_return = 0;
552 }
553
554 err = -EACCES;
555 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
556 goto out_unlock;
557
558 err = security_msg_queue_msgctl(msq, cmd);
559 if (err)
560 goto out_unlock;
561
562 kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
563 tbuf.msg_stime = msq->q_stime;
564 tbuf.msg_rtime = msq->q_rtime;
565 tbuf.msg_ctime = msq->q_ctime;
566 tbuf.msg_cbytes = msq->q_cbytes;
567 tbuf.msg_qnum = msq->q_qnum;
568 tbuf.msg_qbytes = msq->q_qbytes;
569 tbuf.msg_lspid = msq->q_lspid;
570 tbuf.msg_lrpid = msq->q_lrpid;
571 rcu_read_unlock();
572
573 if (copy_msqid_to_user(buf, &tbuf, version))
574 return -EFAULT;
575 return success_return;
576 }
577
578 default:
579 return -EINVAL;
580 }
581
582 return err;
583out_unlock:
584 rcu_read_unlock();
585 return err;
586}
587
588SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
589{
590 int version;
591 struct ipc_namespace *ns;
592
593 if (msqid < 0 || cmd < 0)
594 return -EINVAL;
595
596 version = ipc_parse_version(&cmd);
597 ns = current->nsproxy->ipc_ns;
598
599 switch (cmd) {
600 case IPC_INFO:
601 case MSG_INFO:
602 case MSG_STAT: /* msqid is an index rather than a msg queue id */
603 case IPC_STAT:
604 return msgctl_nolock(ns, msqid, cmd, version, buf);
605 case IPC_SET:
606 case IPC_RMID:
607 return msgctl_down(ns, msqid, cmd, buf, version);
608 default:
609 return -EINVAL;
610 }
611}
612
613static int testmsg(struct msg_msg *msg, long type, int mode)
614{
615 switch (mode)
616 {
617 case SEARCH_ANY:
618 case SEARCH_NUMBER:
619 return 1;
620 case SEARCH_LESSEQUAL:
621 if (msg->m_type <= type)
622 return 1;
623 break;
624 case SEARCH_EQUAL:
625 if (msg->m_type == type)
626 return 1;
627 break;
628 case SEARCH_NOTEQUAL:
629 if (msg->m_type != type)
630 return 1;
631 break;
632 }
633 return 0;
634}
635
636static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg)
637{
638 struct msg_receiver *msr, *t;
639
640 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
641 if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
642 !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
643 msr->r_msgtype, msr->r_mode)) {
644
645 list_del(&msr->r_list);
646 if (msr->r_maxsize < msg->m_ts) {
647 /* initialize pipelined send ordering */
648 msr->r_msg = NULL;
649 wake_up_process(msr->r_tsk);
650 smp_mb(); /* see barrier comment below */
651 msr->r_msg = ERR_PTR(-E2BIG);
652 } else {
653 msr->r_msg = NULL;
654 msq->q_lrpid = task_pid_vnr(msr->r_tsk);
655 msq->q_rtime = get_seconds();
656 wake_up_process(msr->r_tsk);
657 /*
658 * Ensure that the wakeup is visible before
659 * setting r_msg, as the receiving end depends
660 * on it. See lockless receive part 1 and 2 in
661 * do_msgrcv().
662 */
663 smp_mb();
664 msr->r_msg = msg;
665
666 return 1;
667 }
668 }
669 }
670
671 return 0;
672}
673
674long do_msgsnd(int msqid, long mtype, void __user *mtext,
675 size_t msgsz, int msgflg)
676{
677 struct msg_queue *msq;
678 struct msg_msg *msg;
679 int err;
680 struct ipc_namespace *ns;
681
682 ns = current->nsproxy->ipc_ns;
683
684 if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
685 return -EINVAL;
686 if (mtype < 1)
687 return -EINVAL;
688
689 msg = load_msg(mtext, msgsz);
690 if (IS_ERR(msg))
691 return PTR_ERR(msg);
692
693 msg->m_type = mtype;
694 msg->m_ts = msgsz;
695
696 rcu_read_lock();
697 msq = msq_obtain_object_check(ns, msqid);
698 if (IS_ERR(msq)) {
699 err = PTR_ERR(msq);
700 goto out_unlock1;
701 }
702
703 ipc_lock_object(&msq->q_perm);
704
705 for (;;) {
706 struct msg_sender s;
707
708 err = -EACCES;
709 if (ipcperms(ns, &msq->q_perm, S_IWUGO))
710 goto out_unlock0;
711
712 /* raced with RMID? */
713 if (!ipc_valid_object(&msq->q_perm)) {
714 err = -EIDRM;
715 goto out_unlock0;
716 }
717
718 err = security_msg_queue_msgsnd(msq, msg, msgflg);
719 if (err)
720 goto out_unlock0;
721
722 if (msgsz + msq->q_cbytes <= msq->q_qbytes &&
723 1 + msq->q_qnum <= msq->q_qbytes) {
724 break;
725 }
726
727 /* queue full, wait: */
728 if (msgflg & IPC_NOWAIT) {
729 err = -EAGAIN;
730 goto out_unlock0;
731 }
732
733 /* enqueue the sender and prepare to block */
734 ss_add(msq, &s);
735
736 if (!ipc_rcu_getref(msq)) {
737 err = -EIDRM;
738 goto out_unlock0;
739 }
740
741 ipc_unlock_object(&msq->q_perm);
742 rcu_read_unlock();
743 schedule();
744
745 rcu_read_lock();
746 ipc_lock_object(&msq->q_perm);
747
748 ipc_rcu_putref(msq, ipc_rcu_free);
749 /* raced with RMID? */
750 if (!ipc_valid_object(&msq->q_perm)) {
751 err = -EIDRM;
752 goto out_unlock0;
753 }
754
755 ss_del(&s);
756
757 if (signal_pending(current)) {
758 err = -ERESTARTNOHAND;
759 goto out_unlock0;
760 }
761
762 }
763 msq->q_lspid = task_tgid_vnr(current);
764 msq->q_stime = get_seconds();
765
766 if (!pipelined_send(msq, msg)) {
767 /* no one is waiting for this message, enqueue it */
768 list_add_tail(&msg->m_list, &msq->q_messages);
769 msq->q_cbytes += msgsz;
770 msq->q_qnum++;
771 atomic_add(msgsz, &ns->msg_bytes);
772 atomic_inc(&ns->msg_hdrs);
773 }
774
775 err = 0;
776 msg = NULL;
777
778out_unlock0:
779 ipc_unlock_object(&msq->q_perm);
780out_unlock1:
781 rcu_read_unlock();
782 if (msg != NULL)
783 free_msg(msg);
784 return err;
785}
786
787SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
788 int, msgflg)
789{
790 long mtype;
791
792 if (get_user(mtype, &msgp->mtype))
793 return -EFAULT;
794 return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
795}
796
797static inline int convert_mode(long *msgtyp, int msgflg)
798{
799 if (msgflg & MSG_COPY)
800 return SEARCH_NUMBER;
801 /*
802 * find message of correct type.
803 * msgtyp = 0 => get first.
804 * msgtyp > 0 => get first message of matching type.
805 * msgtyp < 0 => get message with least type must be < abs(msgtype).
806 */
807 if (*msgtyp == 0)
808 return SEARCH_ANY;
809 if (*msgtyp < 0) {
810 *msgtyp = -*msgtyp;
811 return SEARCH_LESSEQUAL;
812 }
813 if (msgflg & MSG_EXCEPT)
814 return SEARCH_NOTEQUAL;
815 return SEARCH_EQUAL;
816}
817
818static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
819{
820 struct msgbuf __user *msgp = dest;
821 size_t msgsz;
822
823 if (put_user(msg->m_type, &msgp->mtype))
824 return -EFAULT;
825
826 msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
827 if (store_msg(msgp->mtext, msg, msgsz))
828 return -EFAULT;
829 return msgsz;
830}
831
832#ifdef CONFIG_CHECKPOINT_RESTORE
833/*
834 * This function creates new kernel message structure, large enough to store
835 * bufsz message bytes.
836 */
837static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
838{
839 struct msg_msg *copy;
840
841 /*
842 * Create dummy message to copy real message to.
843 */
844 copy = load_msg(buf, bufsz);
845 if (!IS_ERR(copy))
846 copy->m_ts = bufsz;
847 return copy;
848}
849
850static inline void free_copy(struct msg_msg *copy)
851{
852 if (copy)
853 free_msg(copy);
854}
855#else
856static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
857{
858 return ERR_PTR(-ENOSYS);
859}
860
861static inline void free_copy(struct msg_msg *copy)
862{
863}
864#endif
865
866static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
867{
868 struct msg_msg *msg, *found = NULL;
869 long count = 0;
870
871 list_for_each_entry(msg, &msq->q_messages, m_list) {
872 if (testmsg(msg, *msgtyp, mode) &&
873 !security_msg_queue_msgrcv(msq, msg, current,
874 *msgtyp, mode)) {
875 if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
876 *msgtyp = msg->m_type - 1;
877 found = msg;
878 } else if (mode == SEARCH_NUMBER) {
879 if (*msgtyp == count)
880 return msg;
881 } else
882 return msg;
883 count++;
884 }
885 }
886
887 return found ?: ERR_PTR(-EAGAIN);
888}
889
890long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
891 long (*msg_handler)(void __user *, struct msg_msg *, size_t))
892{
893 int mode;
894 struct msg_queue *msq;
895 struct ipc_namespace *ns;
896 struct msg_msg *msg, *copy = NULL;
897
898 ns = current->nsproxy->ipc_ns;
899
900 if (msqid < 0 || (long) bufsz < 0)
901 return -EINVAL;
902
903 if (msgflg & MSG_COPY) {
904 if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
905 return -EINVAL;
906 copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
907 if (IS_ERR(copy))
908 return PTR_ERR(copy);
909 }
910 mode = convert_mode(&msgtyp, msgflg);
911
912 rcu_read_lock();
913 msq = msq_obtain_object_check(ns, msqid);
914 if (IS_ERR(msq)) {
915 rcu_read_unlock();
916 free_copy(copy);
917 return PTR_ERR(msq);
918 }
919
920 for (;;) {
921 struct msg_receiver msr_d;
922
923 msg = ERR_PTR(-EACCES);
924 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
925 goto out_unlock1;
926
927 ipc_lock_object(&msq->q_perm);
928
929 /* raced with RMID? */
930 if (!ipc_valid_object(&msq->q_perm)) {
931 msg = ERR_PTR(-EIDRM);
932 goto out_unlock0;
933 }
934
935 msg = find_msg(msq, &msgtyp, mode);
936 if (!IS_ERR(msg)) {
937 /*
938 * Found a suitable message.
939 * Unlink it from the queue.
940 */
941 if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
942 msg = ERR_PTR(-E2BIG);
943 goto out_unlock0;
944 }
945 /*
946 * If we are copying, then do not unlink message and do
947 * not update queue parameters.
948 */
949 if (msgflg & MSG_COPY) {
950 msg = copy_msg(msg, copy);
951 goto out_unlock0;
952 }
953
954 list_del(&msg->m_list);
955 msq->q_qnum--;
956 msq->q_rtime = get_seconds();
957 msq->q_lrpid = task_tgid_vnr(current);
958 msq->q_cbytes -= msg->m_ts;
959 atomic_sub(msg->m_ts, &ns->msg_bytes);
960 atomic_dec(&ns->msg_hdrs);
961 ss_wakeup(&msq->q_senders, 0);
962
963 goto out_unlock0;
964 }
965
966 /* No message waiting. Wait for a message */
967 if (msgflg & IPC_NOWAIT) {
968 msg = ERR_PTR(-ENOMSG);
969 goto out_unlock0;
970 }
971
972 list_add_tail(&msr_d.r_list, &msq->q_receivers);
973 msr_d.r_tsk = current;
974 msr_d.r_msgtype = msgtyp;
975 msr_d.r_mode = mode;
976 if (msgflg & MSG_NOERROR)
977 msr_d.r_maxsize = INT_MAX;
978 else
979 msr_d.r_maxsize = bufsz;
980 msr_d.r_msg = ERR_PTR(-EAGAIN);
981 current->state = TASK_INTERRUPTIBLE;
982
983 ipc_unlock_object(&msq->q_perm);
984 rcu_read_unlock();
985 schedule();
986
987 /* Lockless receive, part 1:
988 * Disable preemption. We don't hold a reference to the queue
989 * and getting a reference would defeat the idea of a lockless
990 * operation, thus the code relies on rcu to guarantee the
991 * existence of msq:
992 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
993 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
994 * rcu_read_lock() prevents preemption between reading r_msg
995 * and acquiring the q_perm.lock in ipc_lock_object().
996 */
997 rcu_read_lock();
998
999 /* Lockless receive, part 2:
1000 * Wait until pipelined_send or expunge_all are outside of
1001 * wake_up_process(). There is a race with exit(), see
1002 * ipc/mqueue.c for the details.
1003 */
1004 msg = (struct msg_msg *)msr_d.r_msg;
1005 while (msg == NULL) {
1006 cpu_relax();
1007 msg = (struct msg_msg *)msr_d.r_msg;
1008 }
1009
1010 /* Lockless receive, part 3:
1011 * If there is a message or an error then accept it without
1012 * locking.
1013 */
1014 if (msg != ERR_PTR(-EAGAIN))
1015 goto out_unlock1;
1016
1017 /* Lockless receive, part 3:
1018 * Acquire the queue spinlock.
1019 */
1020 ipc_lock_object(&msq->q_perm);
1021
1022 /* Lockless receive, part 4:
1023 * Repeat test after acquiring the spinlock.
1024 */
1025 msg = (struct msg_msg *)msr_d.r_msg;
1026 if (msg != ERR_PTR(-EAGAIN))
1027 goto out_unlock0;
1028
1029 list_del(&msr_d.r_list);
1030 if (signal_pending(current)) {
1031 msg = ERR_PTR(-ERESTARTNOHAND);
1032 goto out_unlock0;
1033 }
1034
1035 ipc_unlock_object(&msq->q_perm);
1036 }
1037
1038out_unlock0:
1039 ipc_unlock_object(&msq->q_perm);
1040out_unlock1:
1041 rcu_read_unlock();
1042 if (IS_ERR(msg)) {
1043 free_copy(copy);
1044 return PTR_ERR(msg);
1045 }
1046
1047 bufsz = msg_handler(buf, msg, bufsz);
1048 free_msg(msg);
1049
1050 return bufsz;
1051}
1052
1053SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1054 long, msgtyp, int, msgflg)
1055{
1056 return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1057}
1058
1059#ifdef CONFIG_PROC_FS
1060static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1061{
1062 struct user_namespace *user_ns = seq_user_ns(s);
1063 struct msg_queue *msq = it;
1064
1065 return seq_printf(s,
1066 "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
1067 msq->q_perm.key,
1068 msq->q_perm.id,
1069 msq->q_perm.mode,
1070 msq->q_cbytes,
1071 msq->q_qnum,
1072 msq->q_lspid,
1073 msq->q_lrpid,
1074 from_kuid_munged(user_ns, msq->q_perm.uid),
1075 from_kgid_munged(user_ns, msq->q_perm.gid),
1076 from_kuid_munged(user_ns, msq->q_perm.cuid),
1077 from_kgid_munged(user_ns, msq->q_perm.cgid),
1078 msq->q_stime,
1079 msq->q_rtime,
1080 msq->q_ctime);
1081}
1082#endif