mfd: wm8350-i2c: Make sure the i2c regmap functions are compiled
[linux/fpc-iii.git] / ipc / msg.c
blobf8c22afff4509becfd41f333847967de7db0de77
1 /*
2 * linux/ipc/msg.c
3 * Copyright (C) 1992 Krishna Balasubramanian
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
11 * /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
13 * mostly rewritten, threaded and wake-one semantics added
14 * MSGMAX limit removed, sysctl's added
15 * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
17 * support for audit of ipc object properties and permission changes
18 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
20 * namespaces support
21 * OpenVZ, SWsoft Inc.
22 * Pavel Emelianov <xemul@openvz.org>
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>
41 #include <asm/current.h>
42 #include <asm/uaccess.h>
43 #include "util.h"
46 * one msg_receiver structure for each sleeping receiver:
48 struct msg_receiver {
49 struct list_head r_list;
50 struct task_struct *r_tsk;
52 int r_mode;
53 long r_msgtype;
54 long r_maxsize;
56 struct msg_msg *volatile r_msg;
59 /* one msg_sender for each sleeping sender */
60 struct msg_sender {
61 struct list_head list;
62 struct task_struct *tsk;
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
71 #define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS])
73 static void freeque(struct ipc_namespace *, struct kern_ipc_perm *);
74 static int newque(struct ipc_namespace *, struct ipc_params *);
75 #ifdef CONFIG_PROC_FS
76 static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
77 #endif
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.
85 void recompute_msgmni(struct ipc_namespace *ns)
87 struct sysinfo i;
88 unsigned long allowed;
89 int nb_ns;
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;
97 if (allowed < MSGMNI) {
98 ns->msg_ctlmni = MSGMNI;
99 return;
102 if (allowed > IPCMNI / nb_ns) {
103 ns->msg_ctlmni = IPCMNI / nb_ns;
104 return;
107 ns->msg_ctlmni = allowed;
110 void msg_init_ns(struct ipc_namespace *ns)
112 ns->msg_ctlmax = MSGMAX;
113 ns->msg_ctlmnb = MSGMNB;
115 recompute_msgmni(ns);
117 atomic_set(&ns->msg_bytes, 0);
118 atomic_set(&ns->msg_hdrs, 0);
119 ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
122 #ifdef CONFIG_IPC_NS
123 void msg_exit_ns(struct ipc_namespace *ns)
125 free_ipcs(ns, &msg_ids(ns), freeque);
126 idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
128 #endif
130 void __init msg_init(void)
132 msg_init_ns(&init_ipc_ns);
134 printk(KERN_INFO "msgmni has been set to %d\n",
135 init_ipc_ns.msg_ctlmni);
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);
142 static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
144 struct kern_ipc_perm *ipcp = ipc_obtain_object(&msg_ids(ns), id);
146 if (IS_ERR(ipcp))
147 return ERR_CAST(ipcp);
149 return container_of(ipcp, struct msg_queue, q_perm);
152 static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
153 int id)
155 struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
157 if (IS_ERR(ipcp))
158 return ERR_CAST(ipcp);
160 return container_of(ipcp, struct msg_queue, q_perm);
163 static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
165 ipc_rmid(&msg_ids(ns), &s->q_perm);
168 static void msg_rcu_free(struct rcu_head *head)
170 struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
171 struct msg_queue *msq = ipc_rcu_to_struct(p);
173 security_msg_queue_free(msq);
174 ipc_rcu_free(head);
178 * newque - Create a new msg queue
179 * @ns: namespace
180 * @params: ptr to the structure that contains the key and msgflg
182 * Called with msg_ids.rwsem held (writer)
184 static int newque(struct ipc_namespace *ns, struct ipc_params *params)
186 struct msg_queue *msq;
187 int id, retval;
188 key_t key = params->key;
189 int msgflg = params->flg;
191 msq = ipc_rcu_alloc(sizeof(*msq));
192 if (!msq)
193 return -ENOMEM;
195 msq->q_perm.mode = msgflg & S_IRWXUGO;
196 msq->q_perm.key = key;
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;
205 msq->q_stime = msq->q_rtime = 0;
206 msq->q_ctime = get_seconds();
207 msq->q_cbytes = msq->q_qnum = 0;
208 msq->q_qbytes = ns->msg_ctlmnb;
209 msq->q_lspid = msq->q_lrpid = 0;
210 INIT_LIST_HEAD(&msq->q_messages);
211 INIT_LIST_HEAD(&msq->q_receivers);
212 INIT_LIST_HEAD(&msq->q_senders);
214 /* ipc_addid() locks msq upon success. */
215 id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
216 if (id < 0) {
217 ipc_rcu_putref(msq, msg_rcu_free);
218 return id;
221 ipc_unlock_object(&msq->q_perm);
222 rcu_read_unlock();
224 return msq->q_perm.id;
227 static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss)
229 mss->tsk = current;
230 current->state = TASK_INTERRUPTIBLE;
231 list_add_tail(&mss->list, &msq->q_senders);
234 static inline void ss_del(struct msg_sender *mss)
236 if (mss->list.next != NULL)
237 list_del(&mss->list);
240 static void ss_wakeup(struct list_head *h, int kill)
242 struct msg_sender *mss, *t;
244 list_for_each_entry_safe(mss, t, h, list) {
245 if (kill)
246 mss->list.next = NULL;
247 wake_up_process(mss->tsk);
251 static void expunge_all(struct msg_queue *msq, int res)
253 struct msg_receiver *msr, *t;
255 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
256 msr->r_msg = NULL;
257 wake_up_process(msr->r_tsk);
258 smp_mb();
259 msr->r_msg = ERR_PTR(res);
264 * freeque() wakes up waiters on the sender and receiver waiting queue,
265 * removes the message queue from message queue ID IDR, and cleans up all the
266 * messages associated with this queue.
268 * msg_ids.rwsem (writer) and the spinlock for this message queue are held
269 * before freeque() is called. msg_ids.rwsem remains locked on exit.
271 static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
273 struct msg_msg *msg, *t;
274 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
276 expunge_all(msq, -EIDRM);
277 ss_wakeup(&msq->q_senders, 1);
278 msg_rmid(ns, msq);
279 ipc_unlock_object(&msq->q_perm);
280 rcu_read_unlock();
282 list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
283 atomic_dec(&ns->msg_hdrs);
284 free_msg(msg);
286 atomic_sub(msq->q_cbytes, &ns->msg_bytes);
287 ipc_rcu_putref(msq, msg_rcu_free);
291 * Called with msg_ids.rwsem and ipcp locked.
293 static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
295 struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
297 return security_msg_queue_associate(msq, msgflg);
300 SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
302 struct ipc_namespace *ns;
303 struct ipc_ops msg_ops;
304 struct ipc_params msg_params;
306 ns = current->nsproxy->ipc_ns;
308 msg_ops.getnew = newque;
309 msg_ops.associate = msg_security;
310 msg_ops.more_checks = NULL;
312 msg_params.key = key;
313 msg_params.flg = msgflg;
315 return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
318 static inline unsigned long
319 copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
321 switch(version) {
322 case IPC_64:
323 return copy_to_user(buf, in, sizeof(*in));
324 case IPC_OLD:
326 struct msqid_ds out;
328 memset(&out, 0, sizeof(out));
330 ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
332 out.msg_stime = in->msg_stime;
333 out.msg_rtime = in->msg_rtime;
334 out.msg_ctime = in->msg_ctime;
336 if (in->msg_cbytes > USHRT_MAX)
337 out.msg_cbytes = USHRT_MAX;
338 else
339 out.msg_cbytes = in->msg_cbytes;
340 out.msg_lcbytes = in->msg_cbytes;
342 if (in->msg_qnum > USHRT_MAX)
343 out.msg_qnum = USHRT_MAX;
344 else
345 out.msg_qnum = in->msg_qnum;
347 if (in->msg_qbytes > USHRT_MAX)
348 out.msg_qbytes = USHRT_MAX;
349 else
350 out.msg_qbytes = in->msg_qbytes;
351 out.msg_lqbytes = in->msg_qbytes;
353 out.msg_lspid = in->msg_lspid;
354 out.msg_lrpid = in->msg_lrpid;
356 return copy_to_user(buf, &out, sizeof(out));
358 default:
359 return -EINVAL;
363 static inline unsigned long
364 copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
366 switch(version) {
367 case IPC_64:
368 if (copy_from_user(out, buf, sizeof(*out)))
369 return -EFAULT;
370 return 0;
371 case IPC_OLD:
373 struct msqid_ds tbuf_old;
375 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
376 return -EFAULT;
378 out->msg_perm.uid = tbuf_old.msg_perm.uid;
379 out->msg_perm.gid = tbuf_old.msg_perm.gid;
380 out->msg_perm.mode = tbuf_old.msg_perm.mode;
382 if (tbuf_old.msg_qbytes == 0)
383 out->msg_qbytes = tbuf_old.msg_lqbytes;
384 else
385 out->msg_qbytes = tbuf_old.msg_qbytes;
387 return 0;
389 default:
390 return -EINVAL;
395 * This function handles some msgctl commands which require the rwsem
396 * to be held in write mode.
397 * NOTE: no locks must be held, the rwsem is taken inside this function.
399 static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
400 struct msqid_ds __user *buf, int version)
402 struct kern_ipc_perm *ipcp;
403 struct msqid64_ds uninitialized_var(msqid64);
404 struct msg_queue *msq;
405 int err;
407 if (cmd == IPC_SET) {
408 if (copy_msqid_from_user(&msqid64, buf, version))
409 return -EFAULT;
412 down_write(&msg_ids(ns).rwsem);
413 rcu_read_lock();
415 ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
416 &msqid64.msg_perm, msqid64.msg_qbytes);
417 if (IS_ERR(ipcp)) {
418 err = PTR_ERR(ipcp);
419 goto out_unlock1;
422 msq = container_of(ipcp, struct msg_queue, q_perm);
424 err = security_msg_queue_msgctl(msq, cmd);
425 if (err)
426 goto out_unlock1;
428 switch (cmd) {
429 case IPC_RMID:
430 ipc_lock_object(&msq->q_perm);
431 /* freeque unlocks the ipc object and rcu */
432 freeque(ns, ipcp);
433 goto out_up;
434 case IPC_SET:
435 if (msqid64.msg_qbytes > ns->msg_ctlmnb &&
436 !capable(CAP_SYS_RESOURCE)) {
437 err = -EPERM;
438 goto out_unlock1;
441 ipc_lock_object(&msq->q_perm);
442 err = ipc_update_perm(&msqid64.msg_perm, ipcp);
443 if (err)
444 goto out_unlock0;
446 msq->q_qbytes = msqid64.msg_qbytes;
448 msq->q_ctime = get_seconds();
449 /* sleeping receivers might be excluded by
450 * stricter permissions.
452 expunge_all(msq, -EAGAIN);
453 /* sleeping senders might be able to send
454 * due to a larger queue size.
456 ss_wakeup(&msq->q_senders, 0);
457 break;
458 default:
459 err = -EINVAL;
460 goto out_unlock1;
463 out_unlock0:
464 ipc_unlock_object(&msq->q_perm);
465 out_unlock1:
466 rcu_read_unlock();
467 out_up:
468 up_write(&msg_ids(ns).rwsem);
469 return err;
472 static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
473 int cmd, int version, void __user *buf)
475 int err;
476 struct msg_queue *msq;
478 switch (cmd) {
479 case IPC_INFO:
480 case MSG_INFO:
482 struct msginfo msginfo;
483 int max_id;
485 if (!buf)
486 return -EFAULT;
489 * We must not return kernel stack data.
490 * due to padding, it's not enough
491 * to set all member fields.
493 err = security_msg_queue_msgctl(NULL, cmd);
494 if (err)
495 return err;
497 memset(&msginfo, 0, sizeof(msginfo));
498 msginfo.msgmni = ns->msg_ctlmni;
499 msginfo.msgmax = ns->msg_ctlmax;
500 msginfo.msgmnb = ns->msg_ctlmnb;
501 msginfo.msgssz = MSGSSZ;
502 msginfo.msgseg = MSGSEG;
503 down_read(&msg_ids(ns).rwsem);
504 if (cmd == MSG_INFO) {
505 msginfo.msgpool = msg_ids(ns).in_use;
506 msginfo.msgmap = atomic_read(&ns->msg_hdrs);
507 msginfo.msgtql = atomic_read(&ns->msg_bytes);
508 } else {
509 msginfo.msgmap = MSGMAP;
510 msginfo.msgpool = MSGPOOL;
511 msginfo.msgtql = MSGTQL;
513 max_id = ipc_get_maxid(&msg_ids(ns));
514 up_read(&msg_ids(ns).rwsem);
515 if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
516 return -EFAULT;
517 return (max_id < 0) ? 0 : max_id;
520 case MSG_STAT:
521 case IPC_STAT:
523 struct msqid64_ds tbuf;
524 int success_return;
526 if (!buf)
527 return -EFAULT;
529 memset(&tbuf, 0, sizeof(tbuf));
531 rcu_read_lock();
532 if (cmd == MSG_STAT) {
533 msq = msq_obtain_object(ns, msqid);
534 if (IS_ERR(msq)) {
535 err = PTR_ERR(msq);
536 goto out_unlock;
538 success_return = msq->q_perm.id;
539 } else {
540 msq = msq_obtain_object_check(ns, msqid);
541 if (IS_ERR(msq)) {
542 err = PTR_ERR(msq);
543 goto out_unlock;
545 success_return = 0;
548 err = -EACCES;
549 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
550 goto out_unlock;
552 err = security_msg_queue_msgctl(msq, cmd);
553 if (err)
554 goto out_unlock;
556 kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
557 tbuf.msg_stime = msq->q_stime;
558 tbuf.msg_rtime = msq->q_rtime;
559 tbuf.msg_ctime = msq->q_ctime;
560 tbuf.msg_cbytes = msq->q_cbytes;
561 tbuf.msg_qnum = msq->q_qnum;
562 tbuf.msg_qbytes = msq->q_qbytes;
563 tbuf.msg_lspid = msq->q_lspid;
564 tbuf.msg_lrpid = msq->q_lrpid;
565 rcu_read_unlock();
567 if (copy_msqid_to_user(buf, &tbuf, version))
568 return -EFAULT;
569 return success_return;
572 default:
573 return -EINVAL;
576 return err;
577 out_unlock:
578 rcu_read_unlock();
579 return err;
582 SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
584 int version;
585 struct ipc_namespace *ns;
587 if (msqid < 0 || cmd < 0)
588 return -EINVAL;
590 version = ipc_parse_version(&cmd);
591 ns = current->nsproxy->ipc_ns;
593 switch (cmd) {
594 case IPC_INFO:
595 case MSG_INFO:
596 case MSG_STAT: /* msqid is an index rather than a msg queue id */
597 case IPC_STAT:
598 return msgctl_nolock(ns, msqid, cmd, version, buf);
599 case IPC_SET:
600 case IPC_RMID:
601 return msgctl_down(ns, msqid, cmd, buf, version);
602 default:
603 return -EINVAL;
607 static int testmsg(struct msg_msg *msg, long type, int mode)
609 switch(mode)
611 case SEARCH_ANY:
612 case SEARCH_NUMBER:
613 return 1;
614 case SEARCH_LESSEQUAL:
615 if (msg->m_type <=type)
616 return 1;
617 break;
618 case SEARCH_EQUAL:
619 if (msg->m_type == type)
620 return 1;
621 break;
622 case SEARCH_NOTEQUAL:
623 if (msg->m_type != type)
624 return 1;
625 break;
627 return 0;
630 static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg)
632 struct msg_receiver *msr, *t;
634 list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
635 if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
636 !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
637 msr->r_msgtype, msr->r_mode)) {
639 list_del(&msr->r_list);
640 if (msr->r_maxsize < msg->m_ts) {
641 msr->r_msg = NULL;
642 wake_up_process(msr->r_tsk);
643 smp_mb();
644 msr->r_msg = ERR_PTR(-E2BIG);
645 } else {
646 msr->r_msg = NULL;
647 msq->q_lrpid = task_pid_vnr(msr->r_tsk);
648 msq->q_rtime = get_seconds();
649 wake_up_process(msr->r_tsk);
650 smp_mb();
651 msr->r_msg = msg;
653 return 1;
657 return 0;
660 long do_msgsnd(int msqid, long mtype, void __user *mtext,
661 size_t msgsz, int msgflg)
663 struct msg_queue *msq;
664 struct msg_msg *msg;
665 int err;
666 struct ipc_namespace *ns;
668 ns = current->nsproxy->ipc_ns;
670 if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
671 return -EINVAL;
672 if (mtype < 1)
673 return -EINVAL;
675 msg = load_msg(mtext, msgsz);
676 if (IS_ERR(msg))
677 return PTR_ERR(msg);
679 msg->m_type = mtype;
680 msg->m_ts = msgsz;
682 rcu_read_lock();
683 msq = msq_obtain_object_check(ns, msqid);
684 if (IS_ERR(msq)) {
685 err = PTR_ERR(msq);
686 goto out_unlock1;
689 ipc_lock_object(&msq->q_perm);
691 for (;;) {
692 struct msg_sender s;
694 err = -EACCES;
695 if (ipcperms(ns, &msq->q_perm, S_IWUGO))
696 goto out_unlock0;
698 /* raced with RMID? */
699 if (msq->q_perm.deleted) {
700 err = -EIDRM;
701 goto out_unlock0;
704 err = security_msg_queue_msgsnd(msq, msg, msgflg);
705 if (err)
706 goto out_unlock0;
708 if (msgsz + msq->q_cbytes <= msq->q_qbytes &&
709 1 + msq->q_qnum <= msq->q_qbytes) {
710 break;
713 /* queue full, wait: */
714 if (msgflg & IPC_NOWAIT) {
715 err = -EAGAIN;
716 goto out_unlock0;
719 ss_add(msq, &s);
721 if (!ipc_rcu_getref(msq)) {
722 err = -EIDRM;
723 goto out_unlock0;
726 ipc_unlock_object(&msq->q_perm);
727 rcu_read_unlock();
728 schedule();
730 rcu_read_lock();
731 ipc_lock_object(&msq->q_perm);
733 ipc_rcu_putref(msq, msg_rcu_free);
734 if (msq->q_perm.deleted) {
735 err = -EIDRM;
736 goto out_unlock0;
739 ss_del(&s);
741 if (signal_pending(current)) {
742 err = -ERESTARTNOHAND;
743 goto out_unlock0;
747 msq->q_lspid = task_tgid_vnr(current);
748 msq->q_stime = get_seconds();
750 if (!pipelined_send(msq, msg)) {
751 /* no one is waiting for this message, enqueue it */
752 list_add_tail(&msg->m_list, &msq->q_messages);
753 msq->q_cbytes += msgsz;
754 msq->q_qnum++;
755 atomic_add(msgsz, &ns->msg_bytes);
756 atomic_inc(&ns->msg_hdrs);
759 err = 0;
760 msg = NULL;
762 out_unlock0:
763 ipc_unlock_object(&msq->q_perm);
764 out_unlock1:
765 rcu_read_unlock();
766 if (msg != NULL)
767 free_msg(msg);
768 return err;
771 SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
772 int, msgflg)
774 long mtype;
776 if (get_user(mtype, &msgp->mtype))
777 return -EFAULT;
778 return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
781 static inline int convert_mode(long *msgtyp, int msgflg)
783 if (msgflg & MSG_COPY)
784 return SEARCH_NUMBER;
786 * find message of correct type.
787 * msgtyp = 0 => get first.
788 * msgtyp > 0 => get first message of matching type.
789 * msgtyp < 0 => get message with least type must be < abs(msgtype).
791 if (*msgtyp == 0)
792 return SEARCH_ANY;
793 if (*msgtyp < 0) {
794 *msgtyp = -*msgtyp;
795 return SEARCH_LESSEQUAL;
797 if (msgflg & MSG_EXCEPT)
798 return SEARCH_NOTEQUAL;
799 return SEARCH_EQUAL;
802 static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
804 struct msgbuf __user *msgp = dest;
805 size_t msgsz;
807 if (put_user(msg->m_type, &msgp->mtype))
808 return -EFAULT;
810 msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
811 if (store_msg(msgp->mtext, msg, msgsz))
812 return -EFAULT;
813 return msgsz;
816 #ifdef CONFIG_CHECKPOINT_RESTORE
818 * This function creates new kernel message structure, large enough to store
819 * bufsz message bytes.
821 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
823 struct msg_msg *copy;
826 * Create dummy message to copy real message to.
828 copy = load_msg(buf, bufsz);
829 if (!IS_ERR(copy))
830 copy->m_ts = bufsz;
831 return copy;
834 static inline void free_copy(struct msg_msg *copy)
836 if (copy)
837 free_msg(copy);
839 #else
840 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
842 return ERR_PTR(-ENOSYS);
845 static inline void free_copy(struct msg_msg *copy)
848 #endif
850 static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
852 struct msg_msg *msg, *found = NULL;
853 long count = 0;
855 list_for_each_entry(msg, &msq->q_messages, m_list) {
856 if (testmsg(msg, *msgtyp, mode) &&
857 !security_msg_queue_msgrcv(msq, msg, current,
858 *msgtyp, mode)) {
859 if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
860 *msgtyp = msg->m_type - 1;
861 found = msg;
862 } else if (mode == SEARCH_NUMBER) {
863 if (*msgtyp == count)
864 return msg;
865 } else
866 return msg;
867 count++;
871 return found ?: ERR_PTR(-EAGAIN);
874 long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
875 long (*msg_handler)(void __user *, struct msg_msg *, size_t))
877 int mode;
878 struct msg_queue *msq;
879 struct ipc_namespace *ns;
880 struct msg_msg *msg, *copy = NULL;
882 ns = current->nsproxy->ipc_ns;
884 if (msqid < 0 || (long) bufsz < 0)
885 return -EINVAL;
887 if (msgflg & MSG_COPY) {
888 if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
889 return -EINVAL;
890 copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
891 if (IS_ERR(copy))
892 return PTR_ERR(copy);
894 mode = convert_mode(&msgtyp, msgflg);
896 rcu_read_lock();
897 msq = msq_obtain_object_check(ns, msqid);
898 if (IS_ERR(msq)) {
899 rcu_read_unlock();
900 free_copy(copy);
901 return PTR_ERR(msq);
904 for (;;) {
905 struct msg_receiver msr_d;
907 msg = ERR_PTR(-EACCES);
908 if (ipcperms(ns, &msq->q_perm, S_IRUGO))
909 goto out_unlock1;
911 ipc_lock_object(&msq->q_perm);
913 /* raced with RMID? */
914 if (msq->q_perm.deleted) {
915 msg = ERR_PTR(-EIDRM);
916 goto out_unlock0;
919 msg = find_msg(msq, &msgtyp, mode);
920 if (!IS_ERR(msg)) {
922 * Found a suitable message.
923 * Unlink it from the queue.
925 if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
926 msg = ERR_PTR(-E2BIG);
927 goto out_unlock0;
930 * If we are copying, then do not unlink message and do
931 * not update queue parameters.
933 if (msgflg & MSG_COPY) {
934 msg = copy_msg(msg, copy);
935 goto out_unlock0;
938 list_del(&msg->m_list);
939 msq->q_qnum--;
940 msq->q_rtime = get_seconds();
941 msq->q_lrpid = task_tgid_vnr(current);
942 msq->q_cbytes -= msg->m_ts;
943 atomic_sub(msg->m_ts, &ns->msg_bytes);
944 atomic_dec(&ns->msg_hdrs);
945 ss_wakeup(&msq->q_senders, 0);
947 goto out_unlock0;
950 /* No message waiting. Wait for a message */
951 if (msgflg & IPC_NOWAIT) {
952 msg = ERR_PTR(-ENOMSG);
953 goto out_unlock0;
956 list_add_tail(&msr_d.r_list, &msq->q_receivers);
957 msr_d.r_tsk = current;
958 msr_d.r_msgtype = msgtyp;
959 msr_d.r_mode = mode;
960 if (msgflg & MSG_NOERROR)
961 msr_d.r_maxsize = INT_MAX;
962 else
963 msr_d.r_maxsize = bufsz;
964 msr_d.r_msg = ERR_PTR(-EAGAIN);
965 current->state = TASK_INTERRUPTIBLE;
967 ipc_unlock_object(&msq->q_perm);
968 rcu_read_unlock();
969 schedule();
971 /* Lockless receive, part 1:
972 * Disable preemption. We don't hold a reference to the queue
973 * and getting a reference would defeat the idea of a lockless
974 * operation, thus the code relies on rcu to guarantee the
975 * existence of msq:
976 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
977 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
978 * rcu_read_lock() prevents preemption between reading r_msg
979 * and acquiring the q_perm.lock in ipc_lock_object().
981 rcu_read_lock();
983 /* Lockless receive, part 2:
984 * Wait until pipelined_send or expunge_all are outside of
985 * wake_up_process(). There is a race with exit(), see
986 * ipc/mqueue.c for the details.
988 msg = (struct msg_msg*)msr_d.r_msg;
989 while (msg == NULL) {
990 cpu_relax();
991 msg = (struct msg_msg *)msr_d.r_msg;
994 /* Lockless receive, part 3:
995 * If there is a message or an error then accept it without
996 * locking.
998 if (msg != ERR_PTR(-EAGAIN))
999 goto out_unlock1;
1001 /* Lockless receive, part 3:
1002 * Acquire the queue spinlock.
1004 ipc_lock_object(&msq->q_perm);
1006 /* Lockless receive, part 4:
1007 * Repeat test after acquiring the spinlock.
1009 msg = (struct msg_msg*)msr_d.r_msg;
1010 if (msg != ERR_PTR(-EAGAIN))
1011 goto out_unlock0;
1013 list_del(&msr_d.r_list);
1014 if (signal_pending(current)) {
1015 msg = ERR_PTR(-ERESTARTNOHAND);
1016 goto out_unlock0;
1019 ipc_unlock_object(&msq->q_perm);
1022 out_unlock0:
1023 ipc_unlock_object(&msq->q_perm);
1024 out_unlock1:
1025 rcu_read_unlock();
1026 if (IS_ERR(msg)) {
1027 free_copy(copy);
1028 return PTR_ERR(msg);
1031 bufsz = msg_handler(buf, msg, bufsz);
1032 free_msg(msg);
1034 return bufsz;
1037 SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1038 long, msgtyp, int, msgflg)
1040 return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1043 #ifdef CONFIG_PROC_FS
1044 static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1046 struct user_namespace *user_ns = seq_user_ns(s);
1047 struct msg_queue *msq = it;
1049 return seq_printf(s,
1050 "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
1051 msq->q_perm.key,
1052 msq->q_perm.id,
1053 msq->q_perm.mode,
1054 msq->q_cbytes,
1055 msq->q_qnum,
1056 msq->q_lspid,
1057 msq->q_lrpid,
1058 from_kuid_munged(user_ns, msq->q_perm.uid),
1059 from_kgid_munged(user_ns, msq->q_perm.gid),
1060 from_kuid_munged(user_ns, msq->q_perm.cuid),
1061 from_kgid_munged(user_ns, msq->q_perm.cgid),
1062 msq->q_stime,
1063 msq->q_rtime,
1064 msq->q_ctime);
1066 #endif