blob: cd92d342953e500717557a475f09dca9535c6c1a [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Christian Kujau624dffc2006-01-15 02:43:54 +010015 * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
Steve Grubb073115d2006-04-02 17:07:33 -040016 *
17 * support for audit of ipc object properties and permission changes
18 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019 */
20
Randy.Dunlapc59ede72006-01-11 12:17:46 -080021#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/slab.h>
23#include <linux/msg.h>
24#include <linux/spinlock.h>
25#include <linux/init.h>
26#include <linux/proc_fs.h>
27#include <linux/list.h>
28#include <linux/security.h>
29#include <linux/sched.h>
30#include <linux/syscalls.h>
31#include <linux/audit.h>
Mike Waychison19b49462005-09-06 15:17:10 -070032#include <linux/seq_file.h>
Ingo Molnar5f921ae2006-03-26 01:37:17 -080033#include <linux/mutex.h>
34
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#include <asm/current.h>
36#include <asm/uaccess.h>
37#include "util.h"
38
39/* sysctl: */
40int msg_ctlmax = MSGMAX;
41int msg_ctlmnb = MSGMNB;
42int msg_ctlmni = MSGMNI;
43
44/* one msg_receiver structure for each sleeping receiver */
45struct msg_receiver {
46 struct list_head r_list;
47 struct task_struct* r_tsk;
48
49 int r_mode;
50 long r_msgtype;
51 long r_maxsize;
52
53 struct msg_msg* volatile r_msg;
54};
55
56/* one msg_sender for each sleeping sender */
57struct msg_sender {
58 struct list_head list;
59 struct task_struct* tsk;
60};
61
62#define SEARCH_ANY 1
63#define SEARCH_EQUAL 2
64#define SEARCH_NOTEQUAL 3
65#define SEARCH_LESSEQUAL 4
66
67static atomic_t msg_bytes = ATOMIC_INIT(0);
68static atomic_t msg_hdrs = ATOMIC_INIT(0);
69
70static struct ipc_ids msg_ids;
71
72#define msg_lock(id) ((struct msg_queue*)ipc_lock(&msg_ids,id))
73#define msg_unlock(msq) ipc_unlock(&(msq)->q_perm)
74#define msg_rmid(id) ((struct msg_queue*)ipc_rmid(&msg_ids,id))
75#define msg_checkid(msq, msgid) \
76 ipc_checkid(&msg_ids,&msq->q_perm,msgid)
77#define msg_buildid(id, seq) \
78 ipc_buildid(&msg_ids, id, seq)
79
80static void freeque (struct msg_queue *msq, int id);
81static int newque (key_t key, int msgflg);
82#ifdef CONFIG_PROC_FS
Mike Waychison19b49462005-09-06 15:17:10 -070083static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
Linus Torvalds1da177e2005-04-16 15:20:36 -070084#endif
85
86void __init msg_init (void)
87{
88 ipc_init_ids(&msg_ids,msg_ctlmni);
Mike Waychison19b49462005-09-06 15:17:10 -070089 ipc_init_proc_interface("sysvipc/msg",
90 " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n",
91 &msg_ids,
92 sysvipc_msg_proc_show);
Linus Torvalds1da177e2005-04-16 15:20:36 -070093}
94
95static int newque (key_t key, int msgflg)
96{
97 int id;
98 int retval;
99 struct msg_queue *msq;
100
101 msq = ipc_rcu_alloc(sizeof(*msq));
102 if (!msq)
103 return -ENOMEM;
104
105 msq->q_perm.mode = (msgflg & S_IRWXUGO);
106 msq->q_perm.key = key;
107
108 msq->q_perm.security = NULL;
109 retval = security_msg_queue_alloc(msq);
110 if (retval) {
111 ipc_rcu_putref(msq);
112 return retval;
113 }
114
115 id = ipc_addid(&msg_ids, &msq->q_perm, msg_ctlmni);
116 if(id == -1) {
117 security_msg_queue_free(msq);
118 ipc_rcu_putref(msq);
119 return -ENOSPC;
120 }
121
Mike Waychison19b49462005-09-06 15:17:10 -0700122 msq->q_id = msg_buildid(id,msq->q_perm.seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 msq->q_stime = msq->q_rtime = 0;
124 msq->q_ctime = get_seconds();
125 msq->q_cbytes = msq->q_qnum = 0;
126 msq->q_qbytes = msg_ctlmnb;
127 msq->q_lspid = msq->q_lrpid = 0;
128 INIT_LIST_HEAD(&msq->q_messages);
129 INIT_LIST_HEAD(&msq->q_receivers);
130 INIT_LIST_HEAD(&msq->q_senders);
131 msg_unlock(msq);
132
Mike Waychison19b49462005-09-06 15:17:10 -0700133 return msq->q_id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134}
135
136static inline void ss_add(struct msg_queue* msq, struct msg_sender* mss)
137{
138 mss->tsk=current;
139 current->state=TASK_INTERRUPTIBLE;
140 list_add_tail(&mss->list,&msq->q_senders);
141}
142
143static inline void ss_del(struct msg_sender* mss)
144{
145 if(mss->list.next != NULL)
146 list_del(&mss->list);
147}
148
149static void ss_wakeup(struct list_head* h, int kill)
150{
151 struct list_head *tmp;
152
153 tmp = h->next;
154 while (tmp != h) {
155 struct msg_sender* mss;
156
157 mss = list_entry(tmp,struct msg_sender,list);
158 tmp = tmp->next;
159 if(kill)
160 mss->list.next=NULL;
161 wake_up_process(mss->tsk);
162 }
163}
164
165static void expunge_all(struct msg_queue* msq, int res)
166{
167 struct list_head *tmp;
168
169 tmp = msq->q_receivers.next;
170 while (tmp != &msq->q_receivers) {
171 struct msg_receiver* msr;
172
173 msr = list_entry(tmp,struct msg_receiver,r_list);
174 tmp = tmp->next;
175 msr->r_msg = NULL;
176 wake_up_process(msr->r_tsk);
177 smp_mb();
178 msr->r_msg = ERR_PTR(res);
179 }
180}
181/*
182 * freeque() wakes up waiters on the sender and receiver waiting queue,
183 * removes the message queue from message queue ID
184 * array, and cleans up all the messages associated with this queue.
185 *
Ingo Molnar5f921ae2006-03-26 01:37:17 -0800186 * msg_ids.mutex and the spinlock for this message queue is hold
187 * before freeque() is called. msg_ids.mutex remains locked on exit.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188 */
189static void freeque (struct msg_queue *msq, int id)
190{
191 struct list_head *tmp;
192
193 expunge_all(msq,-EIDRM);
194 ss_wakeup(&msq->q_senders,1);
195 msq = msg_rmid(id);
196 msg_unlock(msq);
197
198 tmp = msq->q_messages.next;
199 while(tmp != &msq->q_messages) {
200 struct msg_msg* msg = list_entry(tmp,struct msg_msg,m_list);
201 tmp = tmp->next;
202 atomic_dec(&msg_hdrs);
203 free_msg(msg);
204 }
205 atomic_sub(msq->q_cbytes, &msg_bytes);
206 security_msg_queue_free(msq);
207 ipc_rcu_putref(msq);
208}
209
210asmlinkage long sys_msgget (key_t key, int msgflg)
211{
212 int id, ret = -EPERM;
213 struct msg_queue *msq;
214
Ingo Molnar5f921ae2006-03-26 01:37:17 -0800215 mutex_lock(&msg_ids.mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 if (key == IPC_PRIVATE)
217 ret = newque(key, msgflg);
218 else if ((id = ipc_findkey(&msg_ids, key)) == -1) { /* key not used */
219 if (!(msgflg & IPC_CREAT))
220 ret = -ENOENT;
221 else
222 ret = newque(key, msgflg);
223 } else if (msgflg & IPC_CREAT && msgflg & IPC_EXCL) {
224 ret = -EEXIST;
225 } else {
226 msq = msg_lock(id);
Eric Sesterhenn8cd52832006-03-24 18:44:22 +0100227 BUG_ON(msq==NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228 if (ipcperms(&msq->q_perm, msgflg))
229 ret = -EACCES;
230 else {
231 int qid = msg_buildid(id, msq->q_perm.seq);
232 ret = security_msg_queue_associate(msq, msgflg);
233 if (!ret)
234 ret = qid;
235 }
236 msg_unlock(msq);
237 }
Ingo Molnar5f921ae2006-03-26 01:37:17 -0800238 mutex_unlock(&msg_ids.mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 return ret;
240}
241
242static inline unsigned long copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
243{
244 switch(version) {
245 case IPC_64:
246 return copy_to_user (buf, in, sizeof(*in));
247 case IPC_OLD:
248 {
249 struct msqid_ds out;
250
251 memset(&out,0,sizeof(out));
252
253 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
254
255 out.msg_stime = in->msg_stime;
256 out.msg_rtime = in->msg_rtime;
257 out.msg_ctime = in->msg_ctime;
258
259 if(in->msg_cbytes > USHRT_MAX)
260 out.msg_cbytes = USHRT_MAX;
261 else
262 out.msg_cbytes = in->msg_cbytes;
263 out.msg_lcbytes = in->msg_cbytes;
264
265 if(in->msg_qnum > USHRT_MAX)
266 out.msg_qnum = USHRT_MAX;
267 else
268 out.msg_qnum = in->msg_qnum;
269
270 if(in->msg_qbytes > USHRT_MAX)
271 out.msg_qbytes = USHRT_MAX;
272 else
273 out.msg_qbytes = in->msg_qbytes;
274 out.msg_lqbytes = in->msg_qbytes;
275
276 out.msg_lspid = in->msg_lspid;
277 out.msg_lrpid = in->msg_lrpid;
278
279 return copy_to_user (buf, &out, sizeof(out));
280 }
281 default:
282 return -EINVAL;
283 }
284}
285
286struct msq_setbuf {
287 unsigned long qbytes;
288 uid_t uid;
289 gid_t gid;
290 mode_t mode;
291};
292
293static inline unsigned long copy_msqid_from_user(struct msq_setbuf *out, void __user *buf, int version)
294{
295 switch(version) {
296 case IPC_64:
297 {
298 struct msqid64_ds tbuf;
299
300 if (copy_from_user (&tbuf, buf, sizeof (tbuf)))
301 return -EFAULT;
302
303 out->qbytes = tbuf.msg_qbytes;
304 out->uid = tbuf.msg_perm.uid;
305 out->gid = tbuf.msg_perm.gid;
306 out->mode = tbuf.msg_perm.mode;
307
308 return 0;
309 }
310 case IPC_OLD:
311 {
312 struct msqid_ds tbuf_old;
313
314 if (copy_from_user (&tbuf_old, buf, sizeof (tbuf_old)))
315 return -EFAULT;
316
317 out->uid = tbuf_old.msg_perm.uid;
318 out->gid = tbuf_old.msg_perm.gid;
319 out->mode = tbuf_old.msg_perm.mode;
320
321 if(tbuf_old.msg_qbytes == 0)
322 out->qbytes = tbuf_old.msg_lqbytes;
323 else
324 out->qbytes = tbuf_old.msg_qbytes;
325
326 return 0;
327 }
328 default:
329 return -EINVAL;
330 }
331}
332
333asmlinkage long sys_msgctl (int msqid, int cmd, struct msqid_ds __user *buf)
334{
335 int err, version;
336 struct msg_queue *msq;
337 struct msq_setbuf setbuf;
338 struct kern_ipc_perm *ipcp;
339
340 if (msqid < 0 || cmd < 0)
341 return -EINVAL;
342
343 version = ipc_parse_version(&cmd);
344
345 switch (cmd) {
346 case IPC_INFO:
347 case MSG_INFO:
348 {
349 struct msginfo msginfo;
350 int max_id;
351 if (!buf)
352 return -EFAULT;
353 /* We must not return kernel stack data.
354 * due to padding, it's not enough
355 * to set all member fields.
356 */
357
358 err = security_msg_queue_msgctl(NULL, cmd);
359 if (err)
360 return err;
361
362 memset(&msginfo,0,sizeof(msginfo));
363 msginfo.msgmni = msg_ctlmni;
364 msginfo.msgmax = msg_ctlmax;
365 msginfo.msgmnb = msg_ctlmnb;
366 msginfo.msgssz = MSGSSZ;
367 msginfo.msgseg = MSGSEG;
Ingo Molnar5f921ae2006-03-26 01:37:17 -0800368 mutex_lock(&msg_ids.mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 if (cmd == MSG_INFO) {
370 msginfo.msgpool = msg_ids.in_use;
371 msginfo.msgmap = atomic_read(&msg_hdrs);
372 msginfo.msgtql = atomic_read(&msg_bytes);
373 } else {
374 msginfo.msgmap = MSGMAP;
375 msginfo.msgpool = MSGPOOL;
376 msginfo.msgtql = MSGTQL;
377 }
378 max_id = msg_ids.max_id;
Ingo Molnar5f921ae2006-03-26 01:37:17 -0800379 mutex_unlock(&msg_ids.mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 if (copy_to_user (buf, &msginfo, sizeof(struct msginfo)))
381 return -EFAULT;
382 return (max_id < 0) ? 0: max_id;
383 }
384 case MSG_STAT:
385 case IPC_STAT:
386 {
387 struct msqid64_ds tbuf;
388 int success_return;
389 if (!buf)
390 return -EFAULT;
391 if(cmd == MSG_STAT && msqid >= msg_ids.entries->size)
392 return -EINVAL;
393
394 memset(&tbuf,0,sizeof(tbuf));
395
396 msq = msg_lock(msqid);
397 if (msq == NULL)
398 return -EINVAL;
399
400 if(cmd == MSG_STAT) {
401 success_return = msg_buildid(msqid, msq->q_perm.seq);
402 } else {
403 err = -EIDRM;
404 if (msg_checkid(msq,msqid))
405 goto out_unlock;
406 success_return = 0;
407 }
408 err = -EACCES;
409 if (ipcperms (&msq->q_perm, S_IRUGO))
410 goto out_unlock;
411
412 err = security_msg_queue_msgctl(msq, cmd);
413 if (err)
414 goto out_unlock;
415
416 kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
417 tbuf.msg_stime = msq->q_stime;
418 tbuf.msg_rtime = msq->q_rtime;
419 tbuf.msg_ctime = msq->q_ctime;
420 tbuf.msg_cbytes = msq->q_cbytes;
421 tbuf.msg_qnum = msq->q_qnum;
422 tbuf.msg_qbytes = msq->q_qbytes;
423 tbuf.msg_lspid = msq->q_lspid;
424 tbuf.msg_lrpid = msq->q_lrpid;
425 msg_unlock(msq);
426 if (copy_msqid_to_user(buf, &tbuf, version))
427 return -EFAULT;
428 return success_return;
429 }
430 case IPC_SET:
431 if (!buf)
432 return -EFAULT;
433 if (copy_msqid_from_user (&setbuf, buf, version))
434 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435 break;
436 case IPC_RMID:
437 break;
438 default:
439 return -EINVAL;
440 }
441
Ingo Molnar5f921ae2006-03-26 01:37:17 -0800442 mutex_lock(&msg_ids.mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443 msq = msg_lock(msqid);
444 err=-EINVAL;
445 if (msq == NULL)
446 goto out_up;
447
448 err = -EIDRM;
449 if (msg_checkid(msq,msqid))
450 goto out_unlock_up;
451 ipcp = &msq->q_perm;
Steve Grubb073115d2006-04-02 17:07:33 -0400452
453 err = audit_ipc_obj(ipcp);
454 if (err)
455 goto out_unlock_up;
Linda Knippersac032212006-05-16 22:03:48 -0400456 if (cmd==IPC_SET) {
457 err = audit_ipc_set_perm(setbuf.qbytes, setbuf.uid, setbuf.gid, setbuf.mode);
458 if (err)
459 goto out_unlock_up;
460 }
Steve Grubb073115d2006-04-02 17:07:33 -0400461
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462 err = -EPERM;
463 if (current->euid != ipcp->cuid &&
464 current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN))
465 /* We _could_ check for CAP_CHOWN above, but we don't */
466 goto out_unlock_up;
467
468 err = security_msg_queue_msgctl(msq, cmd);
469 if (err)
470 goto out_unlock_up;
471
472 switch (cmd) {
473 case IPC_SET:
474 {
475 err = -EPERM;
476 if (setbuf.qbytes > msg_ctlmnb && !capable(CAP_SYS_RESOURCE))
477 goto out_unlock_up;
478
479 msq->q_qbytes = setbuf.qbytes;
480
481 ipcp->uid = setbuf.uid;
482 ipcp->gid = setbuf.gid;
483 ipcp->mode = (ipcp->mode & ~S_IRWXUGO) |
484 (S_IRWXUGO & setbuf.mode);
485 msq->q_ctime = get_seconds();
486 /* sleeping receivers might be excluded by
487 * stricter permissions.
488 */
489 expunge_all(msq,-EAGAIN);
490 /* sleeping senders might be able to send
491 * due to a larger queue size.
492 */
493 ss_wakeup(&msq->q_senders,0);
494 msg_unlock(msq);
495 break;
496 }
497 case IPC_RMID:
498 freeque (msq, msqid);
499 break;
500 }
501 err = 0;
502out_up:
Ingo Molnar5f921ae2006-03-26 01:37:17 -0800503 mutex_unlock(&msg_ids.mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 return err;
505out_unlock_up:
506 msg_unlock(msq);
507 goto out_up;
508out_unlock:
509 msg_unlock(msq);
510 return err;
511}
512
513static int testmsg(struct msg_msg* msg,long type,int mode)
514{
515 switch(mode)
516 {
517 case SEARCH_ANY:
518 return 1;
519 case SEARCH_LESSEQUAL:
520 if(msg->m_type <=type)
521 return 1;
522 break;
523 case SEARCH_EQUAL:
524 if(msg->m_type == type)
525 return 1;
526 break;
527 case SEARCH_NOTEQUAL:
528 if(msg->m_type != type)
529 return 1;
530 break;
531 }
532 return 0;
533}
534
535static inline int pipelined_send(struct msg_queue* msq, struct msg_msg* msg)
536{
537 struct list_head* tmp;
538
539 tmp = msq->q_receivers.next;
540 while (tmp != &msq->q_receivers) {
541 struct msg_receiver* msr;
542 msr = list_entry(tmp,struct msg_receiver,r_list);
543 tmp = tmp->next;
544 if(testmsg(msg,msr->r_msgtype,msr->r_mode) &&
545 !security_msg_queue_msgrcv(msq, msg, msr->r_tsk, msr->r_msgtype, msr->r_mode)) {
546 list_del(&msr->r_list);
547 if(msr->r_maxsize < msg->m_ts) {
548 msr->r_msg = NULL;
549 wake_up_process(msr->r_tsk);
550 smp_mb();
551 msr->r_msg = ERR_PTR(-E2BIG);
552 } else {
553 msr->r_msg = NULL;
554 msq->q_lrpid = msr->r_tsk->pid;
555 msq->q_rtime = get_seconds();
556 wake_up_process(msr->r_tsk);
557 smp_mb();
558 msr->r_msg = msg;
559 return 1;
560 }
561 }
562 }
563 return 0;
564}
565
566asmlinkage long sys_msgsnd (int msqid, struct msgbuf __user *msgp, size_t msgsz, int msgflg)
567{
568 struct msg_queue *msq;
569 struct msg_msg *msg;
570 long mtype;
571 int err;
572
573 if (msgsz > msg_ctlmax || (long) msgsz < 0 || msqid < 0)
574 return -EINVAL;
575 if (get_user(mtype, &msgp->mtype))
576 return -EFAULT;
577 if (mtype < 1)
578 return -EINVAL;
579
580 msg = load_msg(msgp->mtext, msgsz);
581 if(IS_ERR(msg))
582 return PTR_ERR(msg);
583
584 msg->m_type = mtype;
585 msg->m_ts = msgsz;
586
587 msq = msg_lock(msqid);
588 err=-EINVAL;
589 if(msq==NULL)
590 goto out_free;
591
592 err= -EIDRM;
593 if (msg_checkid(msq,msqid))
594 goto out_unlock_free;
595
596 for (;;) {
597 struct msg_sender s;
598
599 err=-EACCES;
600 if (ipcperms(&msq->q_perm, S_IWUGO))
601 goto out_unlock_free;
602
603 err = security_msg_queue_msgsnd(msq, msg, msgflg);
604 if (err)
605 goto out_unlock_free;
606
607 if(msgsz + msq->q_cbytes <= msq->q_qbytes &&
608 1 + msq->q_qnum <= msq->q_qbytes) {
609 break;
610 }
611
612 /* queue full, wait: */
613 if(msgflg&IPC_NOWAIT) {
614 err=-EAGAIN;
615 goto out_unlock_free;
616 }
617 ss_add(msq, &s);
618 ipc_rcu_getref(msq);
619 msg_unlock(msq);
620 schedule();
621
622 ipc_lock_by_ptr(&msq->q_perm);
623 ipc_rcu_putref(msq);
624 if (msq->q_perm.deleted) {
625 err = -EIDRM;
626 goto out_unlock_free;
627 }
628 ss_del(&s);
629
630 if (signal_pending(current)) {
631 err=-ERESTARTNOHAND;
632 goto out_unlock_free;
633 }
634 }
635
636 msq->q_lspid = current->tgid;
637 msq->q_stime = get_seconds();
638
639 if(!pipelined_send(msq,msg)) {
640 /* noone is waiting for this message, enqueue it */
641 list_add_tail(&msg->m_list,&msq->q_messages);
642 msq->q_cbytes += msgsz;
643 msq->q_qnum++;
644 atomic_add(msgsz,&msg_bytes);
645 atomic_inc(&msg_hdrs);
646 }
647
648 err = 0;
649 msg = NULL;
650
651out_unlock_free:
652 msg_unlock(msq);
653out_free:
654 if(msg!=NULL)
655 free_msg(msg);
656 return err;
657}
658
659static inline int convert_mode(long* msgtyp, int msgflg)
660{
661 /*
662 * find message of correct type.
663 * msgtyp = 0 => get first.
664 * msgtyp > 0 => get first message of matching type.
665 * msgtyp < 0 => get message with least type must be < abs(msgtype).
666 */
667 if(*msgtyp==0)
668 return SEARCH_ANY;
669 if(*msgtyp<0) {
670 *msgtyp=-(*msgtyp);
671 return SEARCH_LESSEQUAL;
672 }
673 if(msgflg & MSG_EXCEPT)
674 return SEARCH_NOTEQUAL;
675 return SEARCH_EQUAL;
676}
677
678asmlinkage long sys_msgrcv (int msqid, struct msgbuf __user *msgp, size_t msgsz,
679 long msgtyp, int msgflg)
680{
681 struct msg_queue *msq;
682 struct msg_msg *msg;
683 int mode;
684
685 if (msqid < 0 || (long) msgsz < 0)
686 return -EINVAL;
687 mode = convert_mode(&msgtyp,msgflg);
688
689 msq = msg_lock(msqid);
690 if(msq==NULL)
691 return -EINVAL;
692
693 msg = ERR_PTR(-EIDRM);
694 if (msg_checkid(msq,msqid))
695 goto out_unlock;
696
697 for (;;) {
698 struct msg_receiver msr_d;
699 struct list_head* tmp;
700
701 msg = ERR_PTR(-EACCES);
702 if (ipcperms (&msq->q_perm, S_IRUGO))
703 goto out_unlock;
704
705 msg = ERR_PTR(-EAGAIN);
706 tmp = msq->q_messages.next;
707 while (tmp != &msq->q_messages) {
708 struct msg_msg *walk_msg;
709 walk_msg = list_entry(tmp,struct msg_msg,m_list);
710 if(testmsg(walk_msg,msgtyp,mode) &&
711 !security_msg_queue_msgrcv(msq, walk_msg, current, msgtyp, mode)) {
712 msg = walk_msg;
713 if(mode == SEARCH_LESSEQUAL && walk_msg->m_type != 1) {
714 msg=walk_msg;
715 msgtyp=walk_msg->m_type-1;
716 } else {
717 msg=walk_msg;
718 break;
719 }
720 }
721 tmp = tmp->next;
722 }
723 if(!IS_ERR(msg)) {
724 /* Found a suitable message. Unlink it from the queue. */
725 if ((msgsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
726 msg = ERR_PTR(-E2BIG);
727 goto out_unlock;
728 }
729 list_del(&msg->m_list);
730 msq->q_qnum--;
731 msq->q_rtime = get_seconds();
732 msq->q_lrpid = current->tgid;
733 msq->q_cbytes -= msg->m_ts;
734 atomic_sub(msg->m_ts,&msg_bytes);
735 atomic_dec(&msg_hdrs);
736 ss_wakeup(&msq->q_senders,0);
737 msg_unlock(msq);
738 break;
739 }
740 /* No message waiting. Wait for a message */
741 if (msgflg & IPC_NOWAIT) {
742 msg = ERR_PTR(-ENOMSG);
743 goto out_unlock;
744 }
745 list_add_tail(&msr_d.r_list,&msq->q_receivers);
746 msr_d.r_tsk = current;
747 msr_d.r_msgtype = msgtyp;
748 msr_d.r_mode = mode;
749 if(msgflg & MSG_NOERROR)
750 msr_d.r_maxsize = INT_MAX;
751 else
752 msr_d.r_maxsize = msgsz;
753 msr_d.r_msg = ERR_PTR(-EAGAIN);
754 current->state = TASK_INTERRUPTIBLE;
755 msg_unlock(msq);
756
757 schedule();
758
759 /* Lockless receive, part 1:
760 * Disable preemption. We don't hold a reference to the queue
761 * and getting a reference would defeat the idea of a lockless
762 * operation, thus the code relies on rcu to guarantee the
763 * existance of msq:
764 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
765 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
766 * rcu_read_lock() prevents preemption between reading r_msg
767 * and the spin_lock() inside ipc_lock_by_ptr().
768 */
769 rcu_read_lock();
770
771 /* Lockless receive, part 2:
772 * Wait until pipelined_send or expunge_all are outside of
773 * wake_up_process(). There is a race with exit(), see
774 * ipc/mqueue.c for the details.
775 */
776 msg = (struct msg_msg*) msr_d.r_msg;
777 while (msg == NULL) {
778 cpu_relax();
779 msg = (struct msg_msg*) msr_d.r_msg;
780 }
781
782 /* Lockless receive, part 3:
783 * If there is a message or an error then accept it without
784 * locking.
785 */
786 if(msg != ERR_PTR(-EAGAIN)) {
787 rcu_read_unlock();
788 break;
789 }
790
791 /* Lockless receive, part 3:
792 * Acquire the queue spinlock.
793 */
794 ipc_lock_by_ptr(&msq->q_perm);
795 rcu_read_unlock();
796
797 /* Lockless receive, part 4:
798 * Repeat test after acquiring the spinlock.
799 */
800 msg = (struct msg_msg*)msr_d.r_msg;
801 if(msg != ERR_PTR(-EAGAIN))
802 goto out_unlock;
803
804 list_del(&msr_d.r_list);
805 if (signal_pending(current)) {
806 msg = ERR_PTR(-ERESTARTNOHAND);
807out_unlock:
808 msg_unlock(msq);
809 break;
810 }
811 }
812 if (IS_ERR(msg))
813 return PTR_ERR(msg);
814
815 msgsz = (msgsz > msg->m_ts) ? msg->m_ts : msgsz;
816 if (put_user (msg->m_type, &msgp->mtype) ||
817 store_msg(msgp->mtext, msg, msgsz)) {
818 msgsz = -EFAULT;
819 }
820 free_msg(msg);
821 return msgsz;
822}
823
824#ifdef CONFIG_PROC_FS
Mike Waychison19b49462005-09-06 15:17:10 -0700825static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826{
Mike Waychison19b49462005-09-06 15:17:10 -0700827 struct msg_queue *msq = it;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828
Mike Waychison19b49462005-09-06 15:17:10 -0700829 return seq_printf(s,
830 "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
831 msq->q_perm.key,
832 msq->q_id,
833 msq->q_perm.mode,
834 msq->q_cbytes,
835 msq->q_qnum,
836 msq->q_lspid,
837 msq->q_lrpid,
838 msq->q_perm.uid,
839 msq->q_perm.gid,
840 msq->q_perm.cuid,
841 msq->q_perm.cgid,
842 msq->q_stime,
843 msq->q_rtime,
844 msq->q_ctime);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845}
846#endif