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Root/ipc/mqueue.c

1	/*
2	* POSIX message queues filesystem for Linux.
3	*
4	* Copyright (C) 2003,2004 Krzysztof Benedyczak (golbi@mat.uni.torun.pl)
5	* Michal Wronski (michal.wronski@gmail.com)
6	*
7	* Spinlocks: Mohamed Abbas (abbas.mohamed@intel.com)
8	* Lockless receive & send, fd based notify:
9	* Manfred Spraul (manfred@colorfullife.com)
10	*
11	* Audit: George Wilson (ltcgcw@us.ibm.com)
12	*
13	* This file is released under the GPL.
14	*/
15
16	#include <linux/capability.h>
17	#include <linux/init.h>
18	#include <linux/pagemap.h>
19	#include <linux/file.h>
20	#include <linux/mount.h>
21	#include <linux/namei.h>
22	#include <linux/sysctl.h>
23	#include <linux/poll.h>
24	#include <linux/mqueue.h>
25	#include <linux/msg.h>
26	#include <linux/skbuff.h>
27	#include <linux/vmalloc.h>
28	#include <linux/netlink.h>
29	#include <linux/syscalls.h>
30	#include <linux/audit.h>
31	#include <linux/signal.h>
32	#include <linux/mutex.h>
33	#include <linux/nsproxy.h>
34	#include <linux/pid.h>
35	#include <linux/ipc_namespace.h>
36	#include <linux/user_namespace.h>
37	#include <linux/slab.h>
38
39	#include <net/sock.h>
40	#include "util.h"
41
42	#define MQUEUE_MAGIC 0x19800202
43	#define DIRENT_SIZE 20
44	#define FILENT_SIZE 80
45
46	#define SEND 0
47	#define RECV 1
48
49	#define STATE_NONE 0
50	#define STATE_PENDING 1
51	#define STATE_READY 2
52
53	struct posix_msg_tree_node {
54	struct rb_node rb_node;
55	struct list_head msg_list;
56	int priority;
57	};
58
59	struct ext_wait_queue { /* queue of sleeping tasks */
60	struct task_struct *task;
61	struct list_head list;
62	struct msg_msg msg; / ptr of loaded message */
63	int state; /* one of STATE_* values */
64	};
65
66	struct mqueue_inode_info {
67	spinlock_t lock;
68	struct inode vfs_inode;
69	wait_queue_head_t wait_q;
70
71	struct rb_root msg_tree;
72	struct posix_msg_tree_node *node_cache;
73	struct mq_attr attr;
74
75	struct sigevent notify;
76	struct pid* notify_owner;
77	struct user_namespace *notify_user_ns;
78	struct user_struct user; / user who created, for accounting */
79	struct sock *notify_sock;
80	struct sk_buff *notify_cookie;
81
82	/* for tasks waiting for free space and messages, respectively */
83	struct ext_wait_queue e_wait_q[2];
84
85	unsigned long qsize; /* size of queue in memory (sum of all msgs) */
86	};
87
88	static const struct inode_operations mqueue_dir_inode_operations;
89	static const struct file_operations mqueue_file_operations;
90	static const struct super_operations mqueue_super_ops;
91	static void remove_notification(struct mqueue_inode_info *info);
92
93	static struct kmem_cache *mqueue_inode_cachep;
94
95	static struct ctl_table_header * mq_sysctl_table;
96
97	static inline struct mqueue_inode_info MQUEUE_I(struct inode inode)
98	{
99	return container_of(inode, struct mqueue_inode_info, vfs_inode);
100	}
101
102	/*
103	* This routine should be called with the mq_lock held.
104	*/
105	static inline struct ipc_namespace __get_ns_from_inode(struct inode inode)
106	{
107	return get_ipc_ns(inode->i_sb->s_fs_info);
108	}
109
110	static struct ipc_namespace get_ns_from_inode(struct inode inode)
111	{
112	struct ipc_namespace *ns;
113
114	spin_lock(&mq_lock);
115	ns = __get_ns_from_inode(inode);
116	spin_unlock(&mq_lock);
117	return ns;
118	}
119
120	/* Auxiliary functions to manipulate messages' list */
121	static int msg_insert(struct msg_msg msg, struct mqueue_inode_info info)
122	{
123	struct rb_node *p, parent = NULL;
124	struct posix_msg_tree_node *leaf;
125
126	p = &info->msg_tree.rb_node;
127	while (*p) {
128	parent = *p;
129	leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
130
131	if (likely(leaf->priority == msg->m_type))
132	goto insert_msg;
133	else if (msg->m_type < leaf->priority)
134	p = &(*p)->rb_left;
135	else
136	p = &(*p)->rb_right;
137	}
138	if (info->node_cache) {
139	leaf = info->node_cache;
140	info->node_cache = NULL;
141	} else {
142	leaf = kmalloc(sizeof(*leaf), GFP_ATOMIC);
143	if (!leaf)
144	return -ENOMEM;
145	INIT_LIST_HEAD(&leaf->msg_list);
146	info->qsize += sizeof(*leaf);
147	}
148	leaf->priority = msg->m_type;
149	rb_link_node(&leaf->rb_node, parent, p);
150	rb_insert_color(&leaf->rb_node, &info->msg_tree);
151	insert_msg:
152	info->attr.mq_curmsgs++;
153	info->qsize += msg->m_ts;
154	list_add_tail(&msg->m_list, &leaf->msg_list);
155	return 0;
156	}
157
158	static inline struct msg_msg msg_get(struct mqueue_inode_info info)
159	{
160	struct rb_node *p, parent = NULL;
161	struct posix_msg_tree_node *leaf;
162	struct msg_msg *msg;
163
164	try_again:
165	p = &info->msg_tree.rb_node;
166	while (*p) {
167	parent = *p;
168	/*
169	* During insert, low priorities go to the left and high to the
170	* right. On receive, we want the highest priorities first, so
171	* walk all the way to the right.
172	*/
173	p = &(*p)->rb_right;
174	}
175	if (!parent) {
176	if (info->attr.mq_curmsgs) {
177	pr_warn_once("Inconsistency in POSIX message queue, "
178	"no tree element, but supposedly messages "
179	"should exist!\n");
180	info->attr.mq_curmsgs = 0;
181	}
182	return NULL;
183	}
184	leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
185	if (unlikely(list_empty(&leaf->msg_list))) {
186	pr_warn_once("Inconsistency in POSIX message queue, "
187	"empty leaf node but we haven't implemented "
188	"lazy leaf delete!\n");
189	rb_erase(&leaf->rb_node, &info->msg_tree);
190	if (info->node_cache) {
191	info->qsize -= sizeof(*leaf);
192	kfree(leaf);
193	} else {
194	info->node_cache = leaf;
195	}
196	goto try_again;
197	} else {
198	msg = list_first_entry(&leaf->msg_list,
199	struct msg_msg, m_list);
200	list_del(&msg->m_list);
201	if (list_empty(&leaf->msg_list)) {
202	rb_erase(&leaf->rb_node, &info->msg_tree);
203	if (info->node_cache) {
204	info->qsize -= sizeof(*leaf);
205	kfree(leaf);
206	} else {
207	info->node_cache = leaf;
208	}
209	}
210	}
211	info->attr.mq_curmsgs--;
212	info->qsize -= msg->m_ts;
213	return msg;
214	}
215
216	static struct inode mqueue_get_inode(struct super_block sb,
217	struct ipc_namespace *ipc_ns, umode_t mode,
218	struct mq_attr *attr)
219	{
220	struct user_struct *u = current_user();
221	struct inode *inode;
222	int ret = -ENOMEM;
223
224	inode = new_inode(sb);
225	if (!inode)
226	goto err;
227
228	inode->i_ino = get_next_ino();
229	inode->i_mode = mode;
230	inode->i_uid = current_fsuid();
231	inode->i_gid = current_fsgid();
232	inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
233
234	if (S_ISREG(mode)) {
235	struct mqueue_inode_info *info;
236	unsigned long mq_bytes, mq_treesize;
237
238	inode->i_fop = &mqueue_file_operations;
239	inode->i_size = FILENT_SIZE;
240	/* mqueue specific info */
241	info = MQUEUE_I(inode);
242	spin_lock_init(&info->lock);
243	init_waitqueue_head(&info->wait_q);
244	INIT_LIST_HEAD(&info->e_wait_q[0].list);
245	INIT_LIST_HEAD(&info->e_wait_q[1].list);
246	info->notify_owner = NULL;
247	info->notify_user_ns = NULL;
248	info->qsize = 0;
249	info->user = NULL; /* set when all is ok */
250	info->msg_tree = RB_ROOT;
251	info->node_cache = NULL;
252	memset(&info->attr, 0, sizeof(info->attr));
253	info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
254	ipc_ns->mq_msg_default);
255	info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
256	ipc_ns->mq_msgsize_default);
257	if (attr) {
258	info->attr.mq_maxmsg = attr->mq_maxmsg;
259	info->attr.mq_msgsize = attr->mq_msgsize;
260	}
261	/*
262	* We used to allocate a static array of pointers and account
263	* the size of that array as well as one msg_msg struct per
264	* possible message into the queue size. That's no longer
265	* accurate as the queue is now an rbtree and will grow and
266	* shrink depending on usage patterns. We can, however, still
267	* account one msg_msg struct per message, but the nodes are
268	* allocated depending on priority usage, and most programs
269	* only use one, or a handful, of priorities. However, since
270	* this is pinned memory, we need to assume worst case, so
271	* that means the min(mq_maxmsg, max_priorities) * struct
272	* posix_msg_tree_node.
273	*/
274	mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
275	min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
276	sizeof(struct posix_msg_tree_node);
277
278	mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
279	info->attr.mq_msgsize);
280
281	spin_lock(&mq_lock);
282	if (u->mq_bytes + mq_bytes < u->mq_bytes \|\|
283	u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
284	spin_unlock(&mq_lock);
285	/* mqueue_evict_inode() releases info->messages */
286	ret = -EMFILE;
287	goto out_inode;
288	}
289	u->mq_bytes += mq_bytes;
290	spin_unlock(&mq_lock);
291
292	/* all is ok */
293	info->user = get_uid(u);
294	} else if (S_ISDIR(mode)) {
295	inc_nlink(inode);
296	/* Some things misbehave if size == 0 on a directory */
297	inode->i_size = 2 * DIRENT_SIZE;
298	inode->i_op = &mqueue_dir_inode_operations;
299	inode->i_fop = &simple_dir_operations;
300	}
301
302	return inode;
303	out_inode:
304	iput(inode);
305	err:
306	return ERR_PTR(ret);
307	}
308
309	static int mqueue_fill_super(struct super_block sb, void data, int silent)
310	{
311	struct inode *inode;
312	struct ipc_namespace *ns = data;
313
314	sb->s_blocksize = PAGE_CACHE_SIZE;
315	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
316	sb->s_magic = MQUEUE_MAGIC;
317	sb->s_op = &mqueue_super_ops;
318
319	inode = mqueue_get_inode(sb, ns, S_IFDIR \| S_ISVTX \| S_IRWXUGO, NULL);
320	if (IS_ERR(inode))
321	return PTR_ERR(inode);
322
323	sb->s_root = d_make_root(inode);
324	if (!sb->s_root)
325	return -ENOMEM;
326	return 0;
327	}
328
329	static struct dentry mqueue_mount(struct file_system_type fs_type,
330	int flags, const char *dev_name,
331	void *data)
332	{
333	if (!(flags & MS_KERNMOUNT)) {
334	struct ipc_namespace *ns = current->nsproxy->ipc_ns;
335	/* Don't allow mounting unless the caller has CAP_SYS_ADMIN
336	* over the ipc namespace.
337	*/
338	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
339	return ERR_PTR(-EPERM);
340
341	data = ns;
342	}
343	return mount_ns(fs_type, flags, data, mqueue_fill_super);
344	}
345
346	static void init_once(void *foo)
347	{
348	struct mqueue_inode_info p = (struct mqueue_inode_info ) foo;
349
350	inode_init_once(&p->vfs_inode);
351	}
352
353	static struct inode mqueue_alloc_inode(struct super_block sb)
354	{
355	struct mqueue_inode_info *ei;
356
357	ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
358	if (!ei)
359	return NULL;
360	return &ei->vfs_inode;
361	}
362
363	static void mqueue_i_callback(struct rcu_head *head)
364	{
365	struct inode *inode = container_of(head, struct inode, i_rcu);
366	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
367	}
368
369	static void mqueue_destroy_inode(struct inode *inode)
370	{
371	call_rcu(&inode->i_rcu, mqueue_i_callback);
372	}
373
374	static void mqueue_evict_inode(struct inode *inode)
375	{
376	struct mqueue_inode_info *info;
377	struct user_struct *user;
378	unsigned long mq_bytes, mq_treesize;
379	struct ipc_namespace *ipc_ns;
380	struct msg_msg *msg;
381
382	clear_inode(inode);
383
384	if (S_ISDIR(inode->i_mode))
385	return;
386
387	ipc_ns = get_ns_from_inode(inode);
388	info = MQUEUE_I(inode);
389	spin_lock(&info->lock);
390	while ((msg = msg_get(info)) != NULL)
391	free_msg(msg);
392	kfree(info->node_cache);
393	spin_unlock(&info->lock);
394
395	/* Total amount of bytes accounted for the mqueue */
396	mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
397	min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
398	sizeof(struct posix_msg_tree_node);
399
400	mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
401	info->attr.mq_msgsize);
402
403	user = info->user;
404	if (user) {
405	spin_lock(&mq_lock);
406	user->mq_bytes -= mq_bytes;
407	/*
408	* get_ns_from_inode() ensures that the
409	* (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
410	* to which we now hold a reference, or it is NULL.
411	* We can't put it here under mq_lock, though.
412	*/
413	if (ipc_ns)
414	ipc_ns->mq_queues_count--;
415	spin_unlock(&mq_lock);
416	free_uid(user);
417	}
418	if (ipc_ns)
419	put_ipc_ns(ipc_ns);
420	}
421
422	static int mqueue_create(struct inode dir, struct dentry dentry,
423	umode_t mode, bool excl)
424	{
425	struct inode *inode;
426	struct mq_attr *attr = dentry->d_fsdata;
427	int error;
428	struct ipc_namespace *ipc_ns;
429
430	spin_lock(&mq_lock);
431	ipc_ns = __get_ns_from_inode(dir);
432	if (!ipc_ns) {
433	error = -EACCES;
434	goto out_unlock;
435	}
436	if (ipc_ns->mq_queues_count >= HARD_QUEUESMAX \|\|
437	(ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
438	!capable(CAP_SYS_RESOURCE))) {
439	error = -ENOSPC;
440	goto out_unlock;
441	}
442	ipc_ns->mq_queues_count++;
443	spin_unlock(&mq_lock);
444
445	inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
446	if (IS_ERR(inode)) {
447	error = PTR_ERR(inode);
448	spin_lock(&mq_lock);
449	ipc_ns->mq_queues_count--;
450	goto out_unlock;
451	}
452
453	put_ipc_ns(ipc_ns);
454	dir->i_size += DIRENT_SIZE;
455	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
456
457	d_instantiate(dentry, inode);
458	dget(dentry);
459	return 0;
460	out_unlock:
461	spin_unlock(&mq_lock);
462	if (ipc_ns)
463	put_ipc_ns(ipc_ns);
464	return error;
465	}
466
467	static int mqueue_unlink(struct inode dir, struct dentry dentry)
468	{
469	struct inode *inode = dentry->d_inode;
470
471	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
472	dir->i_size -= DIRENT_SIZE;
473	drop_nlink(inode);
474	dput(dentry);
475	return 0;
476	}
477
478	/*
479	* This is routine for system read from queue file.
480	* To avoid mess with doing here some sort of mq_receive we allow
481	* to read only queue size & notification info (the only values
482	* that are interesting from user point of view and aren't accessible
483	* through std routines)
484	*/
485	static ssize_t mqueue_read_file(struct file filp, char __user u_data,
486	size_t count, loff_t *off)
487	{
488	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
489	char buffer[FILENT_SIZE];
490	ssize_t ret;
491
492	spin_lock(&info->lock);
493	snprintf(buffer, sizeof(buffer),
494	"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
495	info->qsize,
496	info->notify_owner ? info->notify.sigev_notify : 0,
497	(info->notify_owner &&
498	info->notify.sigev_notify == SIGEV_SIGNAL) ?
499	info->notify.sigev_signo : 0,
500	pid_vnr(info->notify_owner));
501	spin_unlock(&info->lock);
502	buffer[sizeof(buffer)-1] = '\0';
503
504	ret = simple_read_from_buffer(u_data, count, off, buffer,
505	strlen(buffer));
506	if (ret <= 0)
507	return ret;
508
509	file_inode(filp)->i_atime = file_inode(filp)->i_ctime = CURRENT_TIME;
510	return ret;
511	}
512
513	static int mqueue_flush_file(struct file *filp, fl_owner_t id)
514	{
515	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
516
517	spin_lock(&info->lock);
518	if (task_tgid(current) == info->notify_owner)
519	remove_notification(info);
520
521	spin_unlock(&info->lock);
522	return 0;
523	}
524
525	static unsigned int mqueue_poll_file(struct file filp, struct poll_table_struct poll_tab)
526	{
527	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
528	int retval = 0;
529
530	poll_wait(filp, &info->wait_q, poll_tab);
531
532	spin_lock(&info->lock);
533	if (info->attr.mq_curmsgs)
534	retval = POLLIN \| POLLRDNORM;
535
536	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
537	retval \|= POLLOUT \| POLLWRNORM;
538	spin_unlock(&info->lock);
539
540	return retval;
541	}
542
543	/* Adds current to info->e_wait_q[sr] before element with smaller prio */
544	static void wq_add(struct mqueue_inode_info *info, int sr,
545	struct ext_wait_queue *ewp)
546	{
547	struct ext_wait_queue *walk;
548
549	ewp->task = current;
550
551	list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
552	if (walk->task->static_prio <= current->static_prio) {
553	list_add_tail(&ewp->list, &walk->list);
554	return;
555	}
556	}
557	list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
558	}
559
560	/*
561	* Puts current task to sleep. Caller must hold queue lock. After return
562	* lock isn't held.
563	* sr: SEND or RECV
564	*/
565	static int wq_sleep(struct mqueue_inode_info *info, int sr,
566	ktime_t timeout, struct ext_wait_queue ewp)
567	{
568	int retval;
569	signed long time;
570
571	wq_add(info, sr, ewp);
572
573	for (;;) {
574	set_current_state(TASK_INTERRUPTIBLE);
575
576	spin_unlock(&info->lock);
577	time = schedule_hrtimeout_range_clock(timeout, 0,
578	HRTIMER_MODE_ABS, CLOCK_REALTIME);
579
580	while (ewp->state == STATE_PENDING)
581	cpu_relax();
582
583	if (ewp->state == STATE_READY) {
584	retval = 0;
585	goto out;
586	}
587	spin_lock(&info->lock);
588	if (ewp->state == STATE_READY) {
589	retval = 0;
590	goto out_unlock;
591	}
592	if (signal_pending(current)) {
593	retval = -ERESTARTSYS;
594	break;
595	}
596	if (time == 0) {
597	retval = -ETIMEDOUT;
598	break;
599	}
600	}
601	list_del(&ewp->list);
602	out_unlock:
603	spin_unlock(&info->lock);
604	out:
605	return retval;
606	}
607
608	/*
609	* Returns waiting task that should be serviced first or NULL if none exists
610	*/
611	static struct ext_wait_queue *wq_get_first_waiter(
612	struct mqueue_inode_info *info, int sr)
613	{
614	struct list_head *ptr;
615
616	ptr = info->e_wait_q[sr].list.prev;
617	if (ptr == &info->e_wait_q[sr].list)
618	return NULL;
619	return list_entry(ptr, struct ext_wait_queue, list);
620	}
621
622
623	static inline void set_cookie(struct sk_buff *skb, char code)
624	{
625	((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
626	}
627
628	/*
629	* The next function is only to split too long sys_mq_timedsend
630	*/
631	static void __do_notify(struct mqueue_inode_info *info)
632	{
633	/* notification
634	* invoked when there is registered process and there isn't process
635	* waiting synchronously for message AND state of queue changed from
636	* empty to not empty. Here we are sure that no one is waiting
637	* synchronously. */
638	if (info->notify_owner &&
639	info->attr.mq_curmsgs == 1) {
640	struct siginfo sig_i;
641	switch (info->notify.sigev_notify) {
642	case SIGEV_NONE:
643	break;
644	case SIGEV_SIGNAL:
645	/* sends signal */
646
647	sig_i.si_signo = info->notify.sigev_signo;
648	sig_i.si_errno = 0;
649	sig_i.si_code = SI_MESGQ;
650	sig_i.si_value = info->notify.sigev_value;
651	/* map current pid/uid into info->owner's namespaces */
652	rcu_read_lock();
653	sig_i.si_pid = task_tgid_nr_ns(current,
654	ns_of_pid(info->notify_owner));
655	sig_i.si_uid = from_kuid_munged(info->notify_user_ns, current_uid());
656	rcu_read_unlock();
657
658	kill_pid_info(info->notify.sigev_signo,
659	&sig_i, info->notify_owner);
660	break;
661	case SIGEV_THREAD:
662	set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
663	netlink_sendskb(info->notify_sock, info->notify_cookie);
664	break;
665	}
666	/* after notification unregisters process */
667	put_pid(info->notify_owner);
668	put_user_ns(info->notify_user_ns);
669	info->notify_owner = NULL;
670	info->notify_user_ns = NULL;
671	}
672	wake_up(&info->wait_q);
673	}
674
675	static int prepare_timeout(const struct timespec __user *u_abs_timeout,
676	ktime_t expires, struct timespec ts)
677	{
678	if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
679	return -EFAULT;
680	if (!timespec_valid(ts))
681	return -EINVAL;
682
683	expires = timespec_to_ktime(ts);
684	return 0;
685	}
686
687	static void remove_notification(struct mqueue_inode_info *info)
688	{
689	if (info->notify_owner != NULL &&
690	info->notify.sigev_notify == SIGEV_THREAD) {
691	set_cookie(info->notify_cookie, NOTIFY_REMOVED);
692	netlink_sendskb(info->notify_sock, info->notify_cookie);
693	}
694	put_pid(info->notify_owner);
695	put_user_ns(info->notify_user_ns);
696	info->notify_owner = NULL;
697	info->notify_user_ns = NULL;
698	}
699
700	static int mq_attr_ok(struct ipc_namespace ipc_ns, struct mq_attr attr)
701	{
702	int mq_treesize;
703	unsigned long total_size;
704
705	if (attr->mq_maxmsg <= 0 \|\| attr->mq_msgsize <= 0)
706	return -EINVAL;
707	if (capable(CAP_SYS_RESOURCE)) {
708	if (attr->mq_maxmsg > HARD_MSGMAX \|\|
709	attr->mq_msgsize > HARD_MSGSIZEMAX)
710	return -EINVAL;
711	} else {
712	if (attr->mq_maxmsg > ipc_ns->mq_msg_max \|\|
713	attr->mq_msgsize > ipc_ns->mq_msgsize_max)
714	return -EINVAL;
715	}
716	/* check for overflow */
717	if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
718	return -EOVERFLOW;
719	mq_treesize = attr->mq_maxmsg * sizeof(struct msg_msg) +
720	min_t(unsigned int, attr->mq_maxmsg, MQ_PRIO_MAX) *
721	sizeof(struct posix_msg_tree_node);
722	total_size = attr->mq_maxmsg * attr->mq_msgsize;
723	if (total_size + mq_treesize < total_size)
724	return -EOVERFLOW;
725	return 0;
726	}
727
728	/*
729	* Invoked when creating a new queue via sys_mq_open
730	*/
731	static struct file do_create(struct ipc_namespace ipc_ns, struct inode *dir,
732	struct path *path, int oflag, umode_t mode,
733	struct mq_attr *attr)
734	{
735	const struct cred *cred = current_cred();
736	int ret;
737
738	if (attr) {
739	ret = mq_attr_ok(ipc_ns, attr);
740	if (ret)
741	return ERR_PTR(ret);
742	/* store for use during create */
743	path->dentry->d_fsdata = attr;
744	} else {
745	struct mq_attr def_attr;
746
747	def_attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
748	ipc_ns->mq_msg_default);
749	def_attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
750	ipc_ns->mq_msgsize_default);
751	ret = mq_attr_ok(ipc_ns, &def_attr);
752	if (ret)
753	return ERR_PTR(ret);
754	}
755
756	mode &= ~current_umask();
757	ret = vfs_create(dir, path->dentry, mode, true);
758	path->dentry->d_fsdata = NULL;
759	if (ret)
760	return ERR_PTR(ret);
761	return dentry_open(path, oflag, cred);
762	}
763
764	/* Opens existing queue */
765	static struct file do_open(struct path path, int oflag)
766	{
767	static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
768	MAY_READ \| MAY_WRITE };
769	int acc;
770	if ((oflag & O_ACCMODE) == (O_RDWR \| O_WRONLY))
771	return ERR_PTR(-EINVAL);
772	acc = oflag2acc[oflag & O_ACCMODE];
773	if (inode_permission(path->dentry->d_inode, acc))
774	return ERR_PTR(-EACCES);
775	return dentry_open(path, oflag, current_cred());
776	}
777
778	SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
779	struct mq_attr __user *, u_attr)
780	{
781	struct path path;
782	struct file *filp;
783	struct filename *name;
784	struct mq_attr attr;
785	int fd, error;
786	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
787	struct vfsmount *mnt = ipc_ns->mq_mnt;
788	struct dentry *root = mnt->mnt_root;
789	int ro;
790
791	if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
792	return -EFAULT;
793
794	audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
795
796	if (IS_ERR(name = getname(u_name)))
797	return PTR_ERR(name);
798
799	fd = get_unused_fd_flags(O_CLOEXEC);
800	if (fd < 0)
801	goto out_putname;
802
803	ro = mnt_want_write(mnt); /* we'll drop it in any case */
804	error = 0;
805	mutex_lock(&root->d_inode->i_mutex);
806	path.dentry = lookup_one_len(name->name, root, strlen(name->name));
807	if (IS_ERR(path.dentry)) {
808	error = PTR_ERR(path.dentry);
809	goto out_putfd;
810	}
811	path.mnt = mntget(mnt);
812
813	if (oflag & O_CREAT) {
814	if (path.dentry->d_inode) { /* entry already exists */
815	audit_inode(name, path.dentry, 0);
816	if (oflag & O_EXCL) {
817	error = -EEXIST;
818	goto out;
819	}
820	filp = do_open(&path, oflag);
821	} else {
822	if (ro) {
823	error = ro;
824	goto out;
825	}
826	filp = do_create(ipc_ns, root->d_inode,
827	&path, oflag, mode,
828	u_attr ? &attr : NULL);
829	}
830	} else {
831	if (!path.dentry->d_inode) {
832	error = -ENOENT;
833	goto out;
834	}
835	audit_inode(name, path.dentry, 0);
836	filp = do_open(&path, oflag);
837	}
838
839	if (!IS_ERR(filp))
840	fd_install(fd, filp);
841	else
842	error = PTR_ERR(filp);
843	out:
844	path_put(&path);
845	out_putfd:
846	if (error) {
847	put_unused_fd(fd);
848	fd = error;
849	}
850	mutex_unlock(&root->d_inode->i_mutex);
851	if (!ro)
852	mnt_drop_write(mnt);
853	out_putname:
854	putname(name);
855	return fd;
856	}
857
858	SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
859	{
860	int err;
861	struct filename *name;
862	struct dentry *dentry;
863	struct inode *inode = NULL;
864	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
865	struct vfsmount *mnt = ipc_ns->mq_mnt;
866
867	name = getname(u_name);
868	if (IS_ERR(name))
869	return PTR_ERR(name);
870
871	err = mnt_want_write(mnt);
872	if (err)
873	goto out_name;
874	mutex_lock_nested(&mnt->mnt_root->d_inode->i_mutex, I_MUTEX_PARENT);
875	dentry = lookup_one_len(name->name, mnt->mnt_root,
876	strlen(name->name));
877	if (IS_ERR(dentry)) {
878	err = PTR_ERR(dentry);
879	goto out_unlock;
880	}
881
882	inode = dentry->d_inode;
883	if (!inode) {
884	err = -ENOENT;
885	} else {
886	ihold(inode);
887	err = vfs_unlink(dentry->d_parent->d_inode, dentry);
888	}
889	dput(dentry);
890
891	out_unlock:
892	mutex_unlock(&mnt->mnt_root->d_inode->i_mutex);
893	if (inode)
894	iput(inode);
895	mnt_drop_write(mnt);
896	out_name:
897	putname(name);
898
899	return err;
900	}
901
902	/* Pipelined send and receive functions.
903	*
904	* If a receiver finds no waiting message, then it registers itself in the
905	* list of waiting receivers. A sender checks that list before adding the new
906	* message into the message array. If there is a waiting receiver, then it
907	* bypasses the message array and directly hands the message over to the
908	* receiver.
909	* The receiver accepts the message and returns without grabbing the queue
910	* spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
911	* are necessary. The same algorithm is used for sysv semaphores, see
912	* ipc/sem.c for more details.
913	*
914	* The same algorithm is used for senders.
915	*/
916
917	/* pipelined_send() - send a message directly to the task waiting in
918	* sys_mq_timedreceive() (without inserting message into a queue).
919	*/
920	static inline void pipelined_send(struct mqueue_inode_info *info,
921	struct msg_msg *message,
922	struct ext_wait_queue *receiver)
923	{
924	receiver->msg = message;
925	list_del(&receiver->list);
926	receiver->state = STATE_PENDING;
927	wake_up_process(receiver->task);
928	smp_wmb();
929	receiver->state = STATE_READY;
930	}
931
932	/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
933	* gets its message and put to the queue (we have one free place for sure). */
934	static inline void pipelined_receive(struct mqueue_inode_info *info)
935	{
936	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
937
938	if (!sender) {
939	/* for poll */
940	wake_up_interruptible(&info->wait_q);
941	return;
942	}
943	if (msg_insert(sender->msg, info))
944	return;
945	list_del(&sender->list);
946	sender->state = STATE_PENDING;
947	wake_up_process(sender->task);
948	smp_wmb();
949	sender->state = STATE_READY;
950	}
951
952	SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
953	size_t, msg_len, unsigned int, msg_prio,
954	const struct timespec __user *, u_abs_timeout)
955	{
956	struct fd f;
957	struct inode *inode;
958	struct ext_wait_queue wait;
959	struct ext_wait_queue *receiver;
960	struct msg_msg *msg_ptr;
961	struct mqueue_inode_info *info;
962	ktime_t expires, *timeout = NULL;
963	struct timespec ts;
964	struct posix_msg_tree_node *new_leaf = NULL;
965	int ret = 0;
966
967	if (u_abs_timeout) {
968	int res = prepare_timeout(u_abs_timeout, &expires, &ts);
969	if (res)
970	return res;
971	timeout = &expires;
972	}
973
974	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
975	return -EINVAL;
976
977	audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
978
979	f = fdget(mqdes);
980	if (unlikely(!f.file)) {
981	ret = -EBADF;
982	goto out;
983	}
984
985	inode = file_inode(f.file);
986	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
987	ret = -EBADF;
988	goto out_fput;
989	}
990	info = MQUEUE_I(inode);
991	audit_inode(NULL, f.file->f_path.dentry, 0);
992
993	if (unlikely(!(f.file->f_mode & FMODE_WRITE))) {
994	ret = -EBADF;
995	goto out_fput;
996	}
997
998	if (unlikely(msg_len > info->attr.mq_msgsize)) {
999	ret = -EMSGSIZE;
1000	goto out_fput;
1001	}
1002
1003	/* First try to allocate memory, before doing anything with
1004	* existing queues. */
1005	msg_ptr = load_msg(u_msg_ptr, msg_len);
1006	if (IS_ERR(msg_ptr)) {
1007	ret = PTR_ERR(msg_ptr);
1008	goto out_fput;
1009	}
1010	msg_ptr->m_ts = msg_len;
1011	msg_ptr->m_type = msg_prio;
1012
1013	/*
1014	* msg_insert really wants us to have a valid, spare node struct so
1015	* it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1016	* fall back to that if necessary.
1017	*/
1018	if (!info->node_cache)
1019	new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1020
1021	spin_lock(&info->lock);
1022
1023	if (!info->node_cache && new_leaf) {
1024	/* Save our speculative allocation into the cache */
1025	INIT_LIST_HEAD(&new_leaf->msg_list);
1026	info->node_cache = new_leaf;
1027	info->qsize += sizeof(*new_leaf);
1028	new_leaf = NULL;
1029	} else {
1030	kfree(new_leaf);
1031	}
1032
1033	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
1034	if (f.file->f_flags & O_NONBLOCK) {
1035	ret = -EAGAIN;
1036	} else {
1037	wait.task = current;
1038	wait.msg = (void *) msg_ptr;
1039	wait.state = STATE_NONE;
1040	ret = wq_sleep(info, SEND, timeout, &wait);
1041	/*
1042	* wq_sleep must be called with info->lock held, and
1043	* returns with the lock released
1044	*/
1045	goto out_free;
1046	}
1047	} else {
1048	receiver = wq_get_first_waiter(info, RECV);
1049	if (receiver) {
1050	pipelined_send(info, msg_ptr, receiver);
1051	} else {
1052	/* adds message to the queue */
1053	ret = msg_insert(msg_ptr, info);
1054	if (ret)
1055	goto out_unlock;
1056	__do_notify(info);
1057	}
1058	inode->i_atime = inode->i_mtime = inode->i_ctime =
1059	CURRENT_TIME;
1060	}
1061	out_unlock:
1062	spin_unlock(&info->lock);
1063	out_free:
1064	if (ret)
1065	free_msg(msg_ptr);
1066	out_fput:
1067	fdput(f);
1068	out:
1069	return ret;
1070	}
1071
1072	SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
1073	size_t, msg_len, unsigned int __user *, u_msg_prio,
1074	const struct timespec __user *, u_abs_timeout)
1075	{
1076	ssize_t ret;
1077	struct msg_msg *msg_ptr;
1078	struct fd f;
1079	struct inode *inode;
1080	struct mqueue_inode_info *info;
1081	struct ext_wait_queue wait;
1082	ktime_t expires, *timeout = NULL;
1083	struct timespec ts;
1084	struct posix_msg_tree_node *new_leaf = NULL;
1085
1086	if (u_abs_timeout) {
1087	int res = prepare_timeout(u_abs_timeout, &expires, &ts);
1088	if (res)
1089	return res;
1090	timeout = &expires;
1091	}
1092
1093	audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
1094
1095	f = fdget(mqdes);
1096	if (unlikely(!f.file)) {
1097	ret = -EBADF;
1098	goto out;
1099	}
1100
1101	inode = file_inode(f.file);
1102	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1103	ret = -EBADF;
1104	goto out_fput;
1105	}
1106	info = MQUEUE_I(inode);
1107	audit_inode(NULL, f.file->f_path.dentry, 0);
1108
1109	if (unlikely(!(f.file->f_mode & FMODE_READ))) {
1110	ret = -EBADF;
1111	goto out_fput;
1112	}
1113
1114	/* checks if buffer is big enough */
1115	if (unlikely(msg_len < info->attr.mq_msgsize)) {
1116	ret = -EMSGSIZE;
1117	goto out_fput;
1118	}
1119
1120	/*
1121	* msg_insert really wants us to have a valid, spare node struct so
1122	* it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1123	* fall back to that if necessary.
1124	*/
1125	if (!info->node_cache)
1126	new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1127
1128	spin_lock(&info->lock);
1129
1130	if (!info->node_cache && new_leaf) {
1131	/* Save our speculative allocation into the cache */
1132	INIT_LIST_HEAD(&new_leaf->msg_list);
1133	info->node_cache = new_leaf;
1134	info->qsize += sizeof(*new_leaf);
1135	} else {
1136	kfree(new_leaf);
1137	}
1138
1139	if (info->attr.mq_curmsgs == 0) {
1140	if (f.file->f_flags & O_NONBLOCK) {
1141	spin_unlock(&info->lock);
1142	ret = -EAGAIN;
1143	} else {
1144	wait.task = current;
1145	wait.state = STATE_NONE;
1146	ret = wq_sleep(info, RECV, timeout, &wait);
1147	msg_ptr = wait.msg;
1148	}
1149	} else {
1150	msg_ptr = msg_get(info);
1151
1152	inode->i_atime = inode->i_mtime = inode->i_ctime =
1153	CURRENT_TIME;
1154
1155	/* There is now free space in queue. */
1156	pipelined_receive(info);
1157	spin_unlock(&info->lock);
1158	ret = 0;
1159	}
1160	if (ret == 0) {
1161	ret = msg_ptr->m_ts;
1162
1163	if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) \|\|
1164	store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1165	ret = -EFAULT;
1166	}
1167	free_msg(msg_ptr);
1168	}
1169	out_fput:
1170	fdput(f);
1171	out:
1172	return ret;
1173	}
1174
1175	/*
1176	* Notes: the case when user wants us to deregister (with NULL as pointer)
1177	* and he isn't currently owner of notification, will be silently discarded.
1178	* It isn't explicitly defined in the POSIX.
1179	*/
1180	SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1181	const struct sigevent __user *, u_notification)
1182	{
1183	int ret;
1184	struct fd f;
1185	struct sock *sock;
1186	struct inode *inode;
1187	struct sigevent notification;
1188	struct mqueue_inode_info *info;
1189	struct sk_buff *nc;
1190
1191	if (u_notification) {
1192	if (copy_from_user(&notification, u_notification,
1193	sizeof(struct sigevent)))
1194	return -EFAULT;
1195	}
1196
1197	audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1198
1199	nc = NULL;
1200	sock = NULL;
1201	if (u_notification != NULL) {
1202	if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1203	notification.sigev_notify != SIGEV_SIGNAL &&
1204	notification.sigev_notify != SIGEV_THREAD))
1205	return -EINVAL;
1206	if (notification.sigev_notify == SIGEV_SIGNAL &&
1207	!valid_signal(notification.sigev_signo)) {
1208	return -EINVAL;
1209	}
1210	if (notification.sigev_notify == SIGEV_THREAD) {
1211	long timeo;
1212
1213	/* create the notify skb */
1214	nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1215	if (!nc) {
1216	ret = -ENOMEM;
1217	goto out;
1218	}
1219	if (copy_from_user(nc->data,
1220	notification.sigev_value.sival_ptr,
1221	NOTIFY_COOKIE_LEN)) {
1222	ret = -EFAULT;
1223	goto out;
1224	}
1225
1226	/* TODO: add a header? */
1227	skb_put(nc, NOTIFY_COOKIE_LEN);
1228	/* and attach it to the socket */
1229	retry:
1230	f = fdget(notification.sigev_signo);
1231	if (!f.file) {
1232	ret = -EBADF;
1233	goto out;
1234	}
1235	sock = netlink_getsockbyfilp(f.file);
1236	fdput(f);
1237	if (IS_ERR(sock)) {
1238	ret = PTR_ERR(sock);
1239	sock = NULL;
1240	goto out;
1241	}
1242
1243	timeo = MAX_SCHEDULE_TIMEOUT;
1244	ret = netlink_attachskb(sock, nc, &timeo, NULL);
1245	if (ret == 1)
1246	goto retry;
1247	if (ret) {
1248	sock = NULL;
1249	nc = NULL;
1250	goto out;
1251	}
1252	}
1253	}
1254
1255	f = fdget(mqdes);
1256	if (!f.file) {
1257	ret = -EBADF;
1258	goto out;
1259	}
1260
1261	inode = file_inode(f.file);
1262	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1263	ret = -EBADF;
1264	goto out_fput;
1265	}
1266	info = MQUEUE_I(inode);
1267
1268	ret = 0;
1269	spin_lock(&info->lock);
1270	if (u_notification == NULL) {
1271	if (info->notify_owner == task_tgid(current)) {
1272	remove_notification(info);
1273	inode->i_atime = inode->i_ctime = CURRENT_TIME;
1274	}
1275	} else if (info->notify_owner != NULL) {
1276	ret = -EBUSY;
1277	} else {
1278	switch (notification.sigev_notify) {
1279	case SIGEV_NONE:
1280	info->notify.sigev_notify = SIGEV_NONE;
1281	break;
1282	case SIGEV_THREAD:
1283	info->notify_sock = sock;
1284	info->notify_cookie = nc;
1285	sock = NULL;
1286	nc = NULL;
1287	info->notify.sigev_notify = SIGEV_THREAD;
1288	break;
1289	case SIGEV_SIGNAL:
1290	info->notify.sigev_signo = notification.sigev_signo;
1291	info->notify.sigev_value = notification.sigev_value;
1292	info->notify.sigev_notify = SIGEV_SIGNAL;
1293	break;
1294	}
1295
1296	info->notify_owner = get_pid(task_tgid(current));
1297	info->notify_user_ns = get_user_ns(current_user_ns());
1298	inode->i_atime = inode->i_ctime = CURRENT_TIME;
1299	}
1300	spin_unlock(&info->lock);
1301	out_fput:
1302	fdput(f);
1303	out:
1304	if (sock) {
1305	netlink_detachskb(sock, nc);
1306	} else if (nc) {
1307	dev_kfree_skb(nc);
1308	}
1309	return ret;
1310	}
1311
1312	SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1313	const struct mq_attr __user *, u_mqstat,
1314	struct mq_attr __user *, u_omqstat)
1315	{
1316	int ret;
1317	struct mq_attr mqstat, omqstat;
1318	struct fd f;
1319	struct inode *inode;
1320	struct mqueue_inode_info *info;
1321
1322	if (u_mqstat != NULL) {
1323	if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1324	return -EFAULT;
1325	if (mqstat.mq_flags & (~O_NONBLOCK))
1326	return -EINVAL;
1327	}
1328
1329	f = fdget(mqdes);
1330	if (!f.file) {
1331	ret = -EBADF;
1332	goto out;
1333	}
1334
1335	inode = file_inode(f.file);
1336	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1337	ret = -EBADF;
1338	goto out_fput;
1339	}
1340	info = MQUEUE_I(inode);
1341
1342	spin_lock(&info->lock);
1343
1344	omqstat = info->attr;
1345	omqstat.mq_flags = f.file->f_flags & O_NONBLOCK;
1346	if (u_mqstat) {
1347	audit_mq_getsetattr(mqdes, &mqstat);
1348	spin_lock(&f.file->f_lock);
1349	if (mqstat.mq_flags & O_NONBLOCK)
1350	f.file->f_flags \|= O_NONBLOCK;
1351	else
1352	f.file->f_flags &= ~O_NONBLOCK;
1353	spin_unlock(&f.file->f_lock);
1354
1355	inode->i_atime = inode->i_ctime = CURRENT_TIME;
1356	}
1357
1358	spin_unlock(&info->lock);
1359
1360	ret = 0;
1361	if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1362	sizeof(struct mq_attr)))
1363	ret = -EFAULT;
1364
1365	out_fput:
1366	fdput(f);
1367	out:
1368	return ret;
1369	}
1370
1371	static const struct inode_operations mqueue_dir_inode_operations = {
1372	.lookup = simple_lookup,
1373	.create = mqueue_create,
1374	.unlink = mqueue_unlink,
1375	};
1376
1377	static const struct file_operations mqueue_file_operations = {
1378	.flush = mqueue_flush_file,
1379	.poll = mqueue_poll_file,
1380	.read = mqueue_read_file,
1381	.llseek = default_llseek,
1382	};
1383
1384	static const struct super_operations mqueue_super_ops = {
1385	.alloc_inode = mqueue_alloc_inode,
1386	.destroy_inode = mqueue_destroy_inode,
1387	.evict_inode = mqueue_evict_inode,
1388	.statfs = simple_statfs,
1389	};
1390
1391	static struct file_system_type mqueue_fs_type = {
1392	.name = "mqueue",
1393	.mount = mqueue_mount,
1394	.kill_sb = kill_litter_super,
1395	.fs_flags = FS_USERNS_MOUNT,
1396	};
1397
1398	int mq_init_ns(struct ipc_namespace *ns)
1399	{
1400	ns->mq_queues_count = 0;
1401	ns->mq_queues_max = DFLT_QUEUESMAX;
1402	ns->mq_msg_max = DFLT_MSGMAX;
1403	ns->mq_msgsize_max = DFLT_MSGSIZEMAX;
1404	ns->mq_msg_default = DFLT_MSG;
1405	ns->mq_msgsize_default = DFLT_MSGSIZE;
1406
1407	ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1408	if (IS_ERR(ns->mq_mnt)) {
1409	int err = PTR_ERR(ns->mq_mnt);
1410	ns->mq_mnt = NULL;
1411	return err;
1412	}
1413	return 0;
1414	}
1415
1416	void mq_clear_sbinfo(struct ipc_namespace *ns)
1417	{
1418	ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1419	}
1420
1421	void mq_put_mnt(struct ipc_namespace *ns)
1422	{
1423	kern_unmount(ns->mq_mnt);
1424	}
1425
1426	static int __init init_mqueue_fs(void)
1427	{
1428	int error;
1429
1430	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1431	sizeof(struct mqueue_inode_info), 0,
1432	SLAB_HWCACHE_ALIGN, init_once);
1433	if (mqueue_inode_cachep == NULL)
1434	return -ENOMEM;
1435
1436	/* ignore failures - they are not fatal */
1437	mq_sysctl_table = mq_register_sysctl_table();
1438
1439	error = register_filesystem(&mqueue_fs_type);
1440	if (error)
1441	goto out_sysctl;
1442
1443	spin_lock_init(&mq_lock);
1444
1445	error = mq_init_ns(&init_ipc_ns);
1446	if (error)
1447	goto out_filesystem;
1448
1449	return 0;
1450
1451	out_filesystem:
1452	unregister_filesystem(&mqueue_fs_type);
1453	out_sysctl:
1454	if (mq_sysctl_table)
1455	unregister_sysctl_table(mq_sysctl_table);
1456	kmem_cache_destroy(mqueue_inode_cachep);
1457	return error;
1458	}
1459
1460	__initcall(init_mqueue_fs);
1461

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