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