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

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