mqueue.c revision df0a4283
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
51struct 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
58struct 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
78static const struct inode_operations mqueue_dir_inode_operations;
79static const struct file_operations mqueue_file_operations;
80static const struct super_operations mqueue_super_ops;
81static void remove_notification(struct mqueue_inode_info *info);
82
83static struct kmem_cache *mqueue_inode_cachep;
84
85static struct ctl_table_header * mq_sysctl_table;
86
87static 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 */
95static 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
100static 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
110static struct inode *mqueue_get_inode(struct super_block *sb,
111		struct ipc_namespace *ipc_ns, umode_t mode,
112		struct mq_attr *attr)
113{
114	struct user_struct *u = current_user();
115	struct inode *inode;
116	int ret = -ENOMEM;
117
118	inode = new_inode(sb);
119	if (!inode)
120		goto err;
121
122	inode->i_ino = get_next_ino();
123	inode->i_mode = mode;
124	inode->i_uid = current_fsuid();
125	inode->i_gid = current_fsgid();
126	inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
127
128	if (S_ISREG(mode)) {
129		struct mqueue_inode_info *info;
130		struct task_struct *p = current;
131		unsigned long mq_bytes, mq_msg_tblsz;
132
133		inode->i_fop = &mqueue_file_operations;
134		inode->i_size = FILENT_SIZE;
135		/* mqueue specific info */
136		info = MQUEUE_I(inode);
137		spin_lock_init(&info->lock);
138		init_waitqueue_head(&info->wait_q);
139		INIT_LIST_HEAD(&info->e_wait_q[0].list);
140		INIT_LIST_HEAD(&info->e_wait_q[1].list);
141		info->notify_owner = NULL;
142		info->qsize = 0;
143		info->user = NULL;	/* set when all is ok */
144		memset(&info->attr, 0, sizeof(info->attr));
145		info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
146		info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
147		if (attr) {
148			info->attr.mq_maxmsg = attr->mq_maxmsg;
149			info->attr.mq_msgsize = attr->mq_msgsize;
150		}
151		mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
152		info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
153		if (!info->messages)
154			goto out_inode;
155
156		mq_bytes = (mq_msg_tblsz +
157			(info->attr.mq_maxmsg * info->attr.mq_msgsize));
158
159		spin_lock(&mq_lock);
160		if (u->mq_bytes + mq_bytes < u->mq_bytes ||
161		    u->mq_bytes + mq_bytes > task_rlimit(p, RLIMIT_MSGQUEUE)) {
162			spin_unlock(&mq_lock);
163			/* mqueue_evict_inode() releases info->messages */
164			ret = -EMFILE;
165			goto out_inode;
166		}
167		u->mq_bytes += mq_bytes;
168		spin_unlock(&mq_lock);
169
170		/* all is ok */
171		info->user = get_uid(u);
172	} else if (S_ISDIR(mode)) {
173		inc_nlink(inode);
174		/* Some things misbehave if size == 0 on a directory */
175		inode->i_size = 2 * DIRENT_SIZE;
176		inode->i_op = &mqueue_dir_inode_operations;
177		inode->i_fop = &simple_dir_operations;
178	}
179
180	return inode;
181out_inode:
182	iput(inode);
183err:
184	return ERR_PTR(ret);
185}
186
187static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
188{
189	struct inode *inode;
190	struct ipc_namespace *ns = data;
191	int error;
192
193	sb->s_blocksize = PAGE_CACHE_SIZE;
194	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
195	sb->s_magic = MQUEUE_MAGIC;
196	sb->s_op = &mqueue_super_ops;
197
198	inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO,
199				NULL);
200	if (IS_ERR(inode)) {
201		error = PTR_ERR(inode);
202		goto out;
203	}
204
205	sb->s_root = d_alloc_root(inode);
206	if (!sb->s_root) {
207		iput(inode);
208		error = -ENOMEM;
209		goto out;
210	}
211	error = 0;
212
213out:
214	return error;
215}
216
217static struct dentry *mqueue_mount(struct file_system_type *fs_type,
218			 int flags, const char *dev_name,
219			 void *data)
220{
221	if (!(flags & MS_KERNMOUNT))
222		data = current->nsproxy->ipc_ns;
223	return mount_ns(fs_type, flags, data, mqueue_fill_super);
224}
225
226static void init_once(void *foo)
227{
228	struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
229
230	inode_init_once(&p->vfs_inode);
231}
232
233static struct inode *mqueue_alloc_inode(struct super_block *sb)
234{
235	struct mqueue_inode_info *ei;
236
237	ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
238	if (!ei)
239		return NULL;
240	return &ei->vfs_inode;
241}
242
243static void mqueue_i_callback(struct rcu_head *head)
244{
245	struct inode *inode = container_of(head, struct inode, i_rcu);
246	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
247}
248
249static void mqueue_destroy_inode(struct inode *inode)
250{
251	call_rcu(&inode->i_rcu, mqueue_i_callback);
252}
253
254static void mqueue_evict_inode(struct inode *inode)
255{
256	struct mqueue_inode_info *info;
257	struct user_struct *user;
258	unsigned long mq_bytes;
259	int i;
260	struct ipc_namespace *ipc_ns;
261
262	end_writeback(inode);
263
264	if (S_ISDIR(inode->i_mode))
265		return;
266
267	ipc_ns = get_ns_from_inode(inode);
268	info = MQUEUE_I(inode);
269	spin_lock(&info->lock);
270	for (i = 0; i < info->attr.mq_curmsgs; i++)
271		free_msg(info->messages[i]);
272	kfree(info->messages);
273	spin_unlock(&info->lock);
274
275	/* Total amount of bytes accounted for the mqueue */
276	mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
277	    + info->attr.mq_msgsize);
278	user = info->user;
279	if (user) {
280		spin_lock(&mq_lock);
281		user->mq_bytes -= mq_bytes;
282		/*
283		 * get_ns_from_inode() ensures that the
284		 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
285		 * to which we now hold a reference, or it is NULL.
286		 * We can't put it here under mq_lock, though.
287		 */
288		if (ipc_ns)
289			ipc_ns->mq_queues_count--;
290		spin_unlock(&mq_lock);
291		free_uid(user);
292	}
293	if (ipc_ns)
294		put_ipc_ns(ipc_ns);
295}
296
297static int mqueue_create(struct inode *dir, struct dentry *dentry,
298				umode_t mode, struct nameidata *nd)
299{
300	struct inode *inode;
301	struct mq_attr *attr = dentry->d_fsdata;
302	int error;
303	struct ipc_namespace *ipc_ns;
304
305	spin_lock(&mq_lock);
306	ipc_ns = __get_ns_from_inode(dir);
307	if (!ipc_ns) {
308		error = -EACCES;
309		goto out_unlock;
310	}
311	if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
312			!capable(CAP_SYS_RESOURCE)) {
313		error = -ENOSPC;
314		goto out_unlock;
315	}
316	ipc_ns->mq_queues_count++;
317	spin_unlock(&mq_lock);
318
319	inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
320	if (IS_ERR(inode)) {
321		error = PTR_ERR(inode);
322		spin_lock(&mq_lock);
323		ipc_ns->mq_queues_count--;
324		goto out_unlock;
325	}
326
327	put_ipc_ns(ipc_ns);
328	dir->i_size += DIRENT_SIZE;
329	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
330
331	d_instantiate(dentry, inode);
332	dget(dentry);
333	return 0;
334out_unlock:
335	spin_unlock(&mq_lock);
336	if (ipc_ns)
337		put_ipc_ns(ipc_ns);
338	return error;
339}
340
341static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
342{
343  	struct inode *inode = dentry->d_inode;
344
345	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
346	dir->i_size -= DIRENT_SIZE;
347  	drop_nlink(inode);
348  	dput(dentry);
349  	return 0;
350}
351
352/*
353*	This is routine for system read from queue file.
354*	To avoid mess with doing here some sort of mq_receive we allow
355*	to read only queue size & notification info (the only values
356*	that are interesting from user point of view and aren't accessible
357*	through std routines)
358*/
359static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
360				size_t count, loff_t *off)
361{
362	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
363	char buffer[FILENT_SIZE];
364	ssize_t ret;
365
366	spin_lock(&info->lock);
367	snprintf(buffer, sizeof(buffer),
368			"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
369			info->qsize,
370			info->notify_owner ? info->notify.sigev_notify : 0,
371			(info->notify_owner &&
372			 info->notify.sigev_notify == SIGEV_SIGNAL) ?
373				info->notify.sigev_signo : 0,
374			pid_vnr(info->notify_owner));
375	spin_unlock(&info->lock);
376	buffer[sizeof(buffer)-1] = '\0';
377
378	ret = simple_read_from_buffer(u_data, count, off, buffer,
379				strlen(buffer));
380	if (ret <= 0)
381		return ret;
382
383	filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
384	return ret;
385}
386
387static int mqueue_flush_file(struct file *filp, fl_owner_t id)
388{
389	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
390
391	spin_lock(&info->lock);
392	if (task_tgid(current) == info->notify_owner)
393		remove_notification(info);
394
395	spin_unlock(&info->lock);
396	return 0;
397}
398
399static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
400{
401	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
402	int retval = 0;
403
404	poll_wait(filp, &info->wait_q, poll_tab);
405
406	spin_lock(&info->lock);
407	if (info->attr.mq_curmsgs)
408		retval = POLLIN | POLLRDNORM;
409
410	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
411		retval |= POLLOUT | POLLWRNORM;
412	spin_unlock(&info->lock);
413
414	return retval;
415}
416
417/* Adds current to info->e_wait_q[sr] before element with smaller prio */
418static void wq_add(struct mqueue_inode_info *info, int sr,
419			struct ext_wait_queue *ewp)
420{
421	struct ext_wait_queue *walk;
422
423	ewp->task = current;
424
425	list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
426		if (walk->task->static_prio <= current->static_prio) {
427			list_add_tail(&ewp->list, &walk->list);
428			return;
429		}
430	}
431	list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
432}
433
434/*
435 * Puts current task to sleep. Caller must hold queue lock. After return
436 * lock isn't held.
437 * sr: SEND or RECV
438 */
439static int wq_sleep(struct mqueue_inode_info *info, int sr,
440		    ktime_t *timeout, struct ext_wait_queue *ewp)
441{
442	int retval;
443	signed long time;
444
445	wq_add(info, sr, ewp);
446
447	for (;;) {
448		set_current_state(TASK_INTERRUPTIBLE);
449
450		spin_unlock(&info->lock);
451		time = schedule_hrtimeout_range_clock(timeout, 0,
452			HRTIMER_MODE_ABS, CLOCK_REALTIME);
453
454		while (ewp->state == STATE_PENDING)
455			cpu_relax();
456
457		if (ewp->state == STATE_READY) {
458			retval = 0;
459			goto out;
460		}
461		spin_lock(&info->lock);
462		if (ewp->state == STATE_READY) {
463			retval = 0;
464			goto out_unlock;
465		}
466		if (signal_pending(current)) {
467			retval = -ERESTARTSYS;
468			break;
469		}
470		if (time == 0) {
471			retval = -ETIMEDOUT;
472			break;
473		}
474	}
475	list_del(&ewp->list);
476out_unlock:
477	spin_unlock(&info->lock);
478out:
479	return retval;
480}
481
482/*
483 * Returns waiting task that should be serviced first or NULL if none exists
484 */
485static struct ext_wait_queue *wq_get_first_waiter(
486		struct mqueue_inode_info *info, int sr)
487{
488	struct list_head *ptr;
489
490	ptr = info->e_wait_q[sr].list.prev;
491	if (ptr == &info->e_wait_q[sr].list)
492		return NULL;
493	return list_entry(ptr, struct ext_wait_queue, list);
494}
495
496/* Auxiliary functions to manipulate messages' list */
497static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
498{
499	int k;
500
501	k = info->attr.mq_curmsgs - 1;
502	while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
503		info->messages[k + 1] = info->messages[k];
504		k--;
505	}
506	info->attr.mq_curmsgs++;
507	info->qsize += ptr->m_ts;
508	info->messages[k + 1] = ptr;
509}
510
511static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
512{
513	info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
514	return info->messages[info->attr.mq_curmsgs];
515}
516
517static inline void set_cookie(struct sk_buff *skb, char code)
518{
519	((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
520}
521
522/*
523 * The next function is only to split too long sys_mq_timedsend
524 */
525static void __do_notify(struct mqueue_inode_info *info)
526{
527	/* notification
528	 * invoked when there is registered process and there isn't process
529	 * waiting synchronously for message AND state of queue changed from
530	 * empty to not empty. Here we are sure that no one is waiting
531	 * synchronously. */
532	if (info->notify_owner &&
533	    info->attr.mq_curmsgs == 1) {
534		struct siginfo sig_i;
535		switch (info->notify.sigev_notify) {
536		case SIGEV_NONE:
537			break;
538		case SIGEV_SIGNAL:
539			/* sends signal */
540
541			sig_i.si_signo = info->notify.sigev_signo;
542			sig_i.si_errno = 0;
543			sig_i.si_code = SI_MESGQ;
544			sig_i.si_value = info->notify.sigev_value;
545			sig_i.si_pid = task_tgid_nr_ns(current,
546						ns_of_pid(info->notify_owner));
547			sig_i.si_uid = current_uid();
548
549			kill_pid_info(info->notify.sigev_signo,
550				      &sig_i, info->notify_owner);
551			break;
552		case SIGEV_THREAD:
553			set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
554			netlink_sendskb(info->notify_sock, info->notify_cookie);
555			break;
556		}
557		/* after notification unregisters process */
558		put_pid(info->notify_owner);
559		info->notify_owner = NULL;
560	}
561	wake_up(&info->wait_q);
562}
563
564static int prepare_timeout(const struct timespec __user *u_abs_timeout,
565			   ktime_t *expires, struct timespec *ts)
566{
567	if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
568		return -EFAULT;
569	if (!timespec_valid(ts))
570		return -EINVAL;
571
572	*expires = timespec_to_ktime(*ts);
573	return 0;
574}
575
576static void remove_notification(struct mqueue_inode_info *info)
577{
578	if (info->notify_owner != NULL &&
579	    info->notify.sigev_notify == SIGEV_THREAD) {
580		set_cookie(info->notify_cookie, NOTIFY_REMOVED);
581		netlink_sendskb(info->notify_sock, info->notify_cookie);
582	}
583	put_pid(info->notify_owner);
584	info->notify_owner = NULL;
585}
586
587static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
588{
589	if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
590		return 0;
591	if (capable(CAP_SYS_RESOURCE)) {
592		if (attr->mq_maxmsg > HARD_MSGMAX)
593			return 0;
594	} else {
595		if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
596				attr->mq_msgsize > ipc_ns->mq_msgsize_max)
597			return 0;
598	}
599	/* check for overflow */
600	if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
601		return 0;
602	if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
603	    + sizeof (struct msg_msg *))) <
604	    (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
605		return 0;
606	return 1;
607}
608
609/*
610 * Invoked when creating a new queue via sys_mq_open
611 */
612static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
613			struct dentry *dentry, int oflag, umode_t mode,
614			struct mq_attr *attr)
615{
616	const struct cred *cred = current_cred();
617	struct file *result;
618	int ret;
619
620	if (attr) {
621		if (!mq_attr_ok(ipc_ns, attr)) {
622			ret = -EINVAL;
623			goto out;
624		}
625		/* store for use during create */
626		dentry->d_fsdata = attr;
627	}
628
629	mode &= ~current_umask();
630	ret = mnt_want_write(ipc_ns->mq_mnt);
631	if (ret)
632		goto out;
633	ret = vfs_create(dir->d_inode, dentry, mode, NULL);
634	dentry->d_fsdata = NULL;
635	if (ret)
636		goto out_drop_write;
637
638	result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
639	/*
640	 * dentry_open() took a persistent mnt_want_write(),
641	 * so we can now drop this one.
642	 */
643	mnt_drop_write(ipc_ns->mq_mnt);
644	return result;
645
646out_drop_write:
647	mnt_drop_write(ipc_ns->mq_mnt);
648out:
649	dput(dentry);
650	mntput(ipc_ns->mq_mnt);
651	return ERR_PTR(ret);
652}
653
654/* Opens existing queue */
655static struct file *do_open(struct ipc_namespace *ipc_ns,
656				struct dentry *dentry, int oflag)
657{
658	int ret;
659	const struct cred *cred = current_cred();
660
661	static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
662						  MAY_READ | MAY_WRITE };
663
664	if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
665		ret = -EINVAL;
666		goto err;
667	}
668
669	if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
670		ret = -EACCES;
671		goto err;
672	}
673
674	return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
675
676err:
677	dput(dentry);
678	mntput(ipc_ns->mq_mnt);
679	return ERR_PTR(ret);
680}
681
682SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
683		struct mq_attr __user *, u_attr)
684{
685	struct dentry *dentry;
686	struct file *filp;
687	char *name;
688	struct mq_attr attr;
689	int fd, error;
690	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
691
692	if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
693		return -EFAULT;
694
695	audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
696
697	if (IS_ERR(name = getname(u_name)))
698		return PTR_ERR(name);
699
700	fd = get_unused_fd_flags(O_CLOEXEC);
701	if (fd < 0)
702		goto out_putname;
703
704	mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
705	dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
706	if (IS_ERR(dentry)) {
707		error = PTR_ERR(dentry);
708		goto out_putfd;
709	}
710	mntget(ipc_ns->mq_mnt);
711
712	if (oflag & O_CREAT) {
713		if (dentry->d_inode) {	/* entry already exists */
714			audit_inode(name, dentry);
715			if (oflag & O_EXCL) {
716				error = -EEXIST;
717				goto out;
718			}
719			filp = do_open(ipc_ns, dentry, oflag);
720		} else {
721			filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
722						dentry, oflag, mode,
723						u_attr ? &attr : NULL);
724		}
725	} else {
726		if (!dentry->d_inode) {
727			error = -ENOENT;
728			goto out;
729		}
730		audit_inode(name, dentry);
731		filp = do_open(ipc_ns, dentry, oflag);
732	}
733
734	if (IS_ERR(filp)) {
735		error = PTR_ERR(filp);
736		goto out_putfd;
737	}
738
739	fd_install(fd, filp);
740	goto out_upsem;
741
742out:
743	dput(dentry);
744	mntput(ipc_ns->mq_mnt);
745out_putfd:
746	put_unused_fd(fd);
747	fd = error;
748out_upsem:
749	mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
750out_putname:
751	putname(name);
752	return fd;
753}
754
755SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
756{
757	int err;
758	char *name;
759	struct dentry *dentry;
760	struct inode *inode = NULL;
761	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
762
763	name = getname(u_name);
764	if (IS_ERR(name))
765		return PTR_ERR(name);
766
767	mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
768			I_MUTEX_PARENT);
769	dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
770	if (IS_ERR(dentry)) {
771		err = PTR_ERR(dentry);
772		goto out_unlock;
773	}
774
775	if (!dentry->d_inode) {
776		err = -ENOENT;
777		goto out_err;
778	}
779
780	inode = dentry->d_inode;
781	if (inode)
782		ihold(inode);
783	err = mnt_want_write(ipc_ns->mq_mnt);
784	if (err)
785		goto out_err;
786	err = vfs_unlink(dentry->d_parent->d_inode, dentry);
787	mnt_drop_write(ipc_ns->mq_mnt);
788out_err:
789	dput(dentry);
790
791out_unlock:
792	mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
793	putname(name);
794	if (inode)
795		iput(inode);
796
797	return err;
798}
799
800/* Pipelined send and receive functions.
801 *
802 * If a receiver finds no waiting message, then it registers itself in the
803 * list of waiting receivers. A sender checks that list before adding the new
804 * message into the message array. If there is a waiting receiver, then it
805 * bypasses the message array and directly hands the message over to the
806 * receiver.
807 * The receiver accepts the message and returns without grabbing the queue
808 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
809 * are necessary. The same algorithm is used for sysv semaphores, see
810 * ipc/sem.c for more details.
811 *
812 * The same algorithm is used for senders.
813 */
814
815/* pipelined_send() - send a message directly to the task waiting in
816 * sys_mq_timedreceive() (without inserting message into a queue).
817 */
818static inline void pipelined_send(struct mqueue_inode_info *info,
819				  struct msg_msg *message,
820				  struct ext_wait_queue *receiver)
821{
822	receiver->msg = message;
823	list_del(&receiver->list);
824	receiver->state = STATE_PENDING;
825	wake_up_process(receiver->task);
826	smp_wmb();
827	receiver->state = STATE_READY;
828}
829
830/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
831 * gets its message and put to the queue (we have one free place for sure). */
832static inline void pipelined_receive(struct mqueue_inode_info *info)
833{
834	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
835
836	if (!sender) {
837		/* for poll */
838		wake_up_interruptible(&info->wait_q);
839		return;
840	}
841	msg_insert(sender->msg, info);
842	list_del(&sender->list);
843	sender->state = STATE_PENDING;
844	wake_up_process(sender->task);
845	smp_wmb();
846	sender->state = STATE_READY;
847}
848
849SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
850		size_t, msg_len, unsigned int, msg_prio,
851		const struct timespec __user *, u_abs_timeout)
852{
853	struct file *filp;
854	struct inode *inode;
855	struct ext_wait_queue wait;
856	struct ext_wait_queue *receiver;
857	struct msg_msg *msg_ptr;
858	struct mqueue_inode_info *info;
859	ktime_t expires, *timeout = NULL;
860	struct timespec ts;
861	int ret;
862
863	if (u_abs_timeout) {
864		int res = prepare_timeout(u_abs_timeout, &expires, &ts);
865		if (res)
866			return res;
867		timeout = &expires;
868	}
869
870	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
871		return -EINVAL;
872
873	audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
874
875	filp = fget(mqdes);
876	if (unlikely(!filp)) {
877		ret = -EBADF;
878		goto out;
879	}
880
881	inode = filp->f_path.dentry->d_inode;
882	if (unlikely(filp->f_op != &mqueue_file_operations)) {
883		ret = -EBADF;
884		goto out_fput;
885	}
886	info = MQUEUE_I(inode);
887	audit_inode(NULL, filp->f_path.dentry);
888
889	if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
890		ret = -EBADF;
891		goto out_fput;
892	}
893
894	if (unlikely(msg_len > info->attr.mq_msgsize)) {
895		ret = -EMSGSIZE;
896		goto out_fput;
897	}
898
899	/* First try to allocate memory, before doing anything with
900	 * existing queues. */
901	msg_ptr = load_msg(u_msg_ptr, msg_len);
902	if (IS_ERR(msg_ptr)) {
903		ret = PTR_ERR(msg_ptr);
904		goto out_fput;
905	}
906	msg_ptr->m_ts = msg_len;
907	msg_ptr->m_type = msg_prio;
908
909	spin_lock(&info->lock);
910
911	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
912		if (filp->f_flags & O_NONBLOCK) {
913			spin_unlock(&info->lock);
914			ret = -EAGAIN;
915		} else {
916			wait.task = current;
917			wait.msg = (void *) msg_ptr;
918			wait.state = STATE_NONE;
919			ret = wq_sleep(info, SEND, timeout, &wait);
920		}
921		if (ret < 0)
922			free_msg(msg_ptr);
923	} else {
924		receiver = wq_get_first_waiter(info, RECV);
925		if (receiver) {
926			pipelined_send(info, msg_ptr, receiver);
927		} else {
928			/* adds message to the queue */
929			msg_insert(msg_ptr, info);
930			__do_notify(info);
931		}
932		inode->i_atime = inode->i_mtime = inode->i_ctime =
933				CURRENT_TIME;
934		spin_unlock(&info->lock);
935		ret = 0;
936	}
937out_fput:
938	fput(filp);
939out:
940	return ret;
941}
942
943SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
944		size_t, msg_len, unsigned int __user *, u_msg_prio,
945		const struct timespec __user *, u_abs_timeout)
946{
947	ssize_t ret;
948	struct msg_msg *msg_ptr;
949	struct file *filp;
950	struct inode *inode;
951	struct mqueue_inode_info *info;
952	struct ext_wait_queue wait;
953	ktime_t expires, *timeout = NULL;
954	struct timespec ts;
955
956	if (u_abs_timeout) {
957		int res = prepare_timeout(u_abs_timeout, &expires, &ts);
958		if (res)
959			return res;
960		timeout = &expires;
961	}
962
963	audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
964
965	filp = fget(mqdes);
966	if (unlikely(!filp)) {
967		ret = -EBADF;
968		goto out;
969	}
970
971	inode = filp->f_path.dentry->d_inode;
972	if (unlikely(filp->f_op != &mqueue_file_operations)) {
973		ret = -EBADF;
974		goto out_fput;
975	}
976	info = MQUEUE_I(inode);
977	audit_inode(NULL, filp->f_path.dentry);
978
979	if (unlikely(!(filp->f_mode & FMODE_READ))) {
980		ret = -EBADF;
981		goto out_fput;
982	}
983
984	/* checks if buffer is big enough */
985	if (unlikely(msg_len < info->attr.mq_msgsize)) {
986		ret = -EMSGSIZE;
987		goto out_fput;
988	}
989
990	spin_lock(&info->lock);
991	if (info->attr.mq_curmsgs == 0) {
992		if (filp->f_flags & O_NONBLOCK) {
993			spin_unlock(&info->lock);
994			ret = -EAGAIN;
995		} else {
996			wait.task = current;
997			wait.state = STATE_NONE;
998			ret = wq_sleep(info, RECV, timeout, &wait);
999			msg_ptr = wait.msg;
1000		}
1001	} else {
1002		msg_ptr = msg_get(info);
1003
1004		inode->i_atime = inode->i_mtime = inode->i_ctime =
1005				CURRENT_TIME;
1006
1007		/* There is now free space in queue. */
1008		pipelined_receive(info);
1009		spin_unlock(&info->lock);
1010		ret = 0;
1011	}
1012	if (ret == 0) {
1013		ret = msg_ptr->m_ts;
1014
1015		if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1016			store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1017			ret = -EFAULT;
1018		}
1019		free_msg(msg_ptr);
1020	}
1021out_fput:
1022	fput(filp);
1023out:
1024	return ret;
1025}
1026
1027/*
1028 * Notes: the case when user wants us to deregister (with NULL as pointer)
1029 * and he isn't currently owner of notification, will be silently discarded.
1030 * It isn't explicitly defined in the POSIX.
1031 */
1032SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1033		const struct sigevent __user *, u_notification)
1034{
1035	int ret;
1036	struct file *filp;
1037	struct sock *sock;
1038	struct inode *inode;
1039	struct sigevent notification;
1040	struct mqueue_inode_info *info;
1041	struct sk_buff *nc;
1042
1043	if (u_notification) {
1044		if (copy_from_user(&notification, u_notification,
1045					sizeof(struct sigevent)))
1046			return -EFAULT;
1047	}
1048
1049	audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1050
1051	nc = NULL;
1052	sock = NULL;
1053	if (u_notification != NULL) {
1054		if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1055			     notification.sigev_notify != SIGEV_SIGNAL &&
1056			     notification.sigev_notify != SIGEV_THREAD))
1057			return -EINVAL;
1058		if (notification.sigev_notify == SIGEV_SIGNAL &&
1059			!valid_signal(notification.sigev_signo)) {
1060			return -EINVAL;
1061		}
1062		if (notification.sigev_notify == SIGEV_THREAD) {
1063			long timeo;
1064
1065			/* create the notify skb */
1066			nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1067			if (!nc) {
1068				ret = -ENOMEM;
1069				goto out;
1070			}
1071			if (copy_from_user(nc->data,
1072					notification.sigev_value.sival_ptr,
1073					NOTIFY_COOKIE_LEN)) {
1074				ret = -EFAULT;
1075				goto out;
1076			}
1077
1078			/* TODO: add a header? */
1079			skb_put(nc, NOTIFY_COOKIE_LEN);
1080			/* and attach it to the socket */
1081retry:
1082			filp = fget(notification.sigev_signo);
1083			if (!filp) {
1084				ret = -EBADF;
1085				goto out;
1086			}
1087			sock = netlink_getsockbyfilp(filp);
1088			fput(filp);
1089			if (IS_ERR(sock)) {
1090				ret = PTR_ERR(sock);
1091				sock = NULL;
1092				goto out;
1093			}
1094
1095			timeo = MAX_SCHEDULE_TIMEOUT;
1096			ret = netlink_attachskb(sock, nc, &timeo, NULL);
1097			if (ret == 1)
1098				goto retry;
1099			if (ret) {
1100				sock = NULL;
1101				nc = NULL;
1102				goto out;
1103			}
1104		}
1105	}
1106
1107	filp = fget(mqdes);
1108	if (!filp) {
1109		ret = -EBADF;
1110		goto out;
1111	}
1112
1113	inode = filp->f_path.dentry->d_inode;
1114	if (unlikely(filp->f_op != &mqueue_file_operations)) {
1115		ret = -EBADF;
1116		goto out_fput;
1117	}
1118	info = MQUEUE_I(inode);
1119
1120	ret = 0;
1121	spin_lock(&info->lock);
1122	if (u_notification == NULL) {
1123		if (info->notify_owner == task_tgid(current)) {
1124			remove_notification(info);
1125			inode->i_atime = inode->i_ctime = CURRENT_TIME;
1126		}
1127	} else if (info->notify_owner != NULL) {
1128		ret = -EBUSY;
1129	} else {
1130		switch (notification.sigev_notify) {
1131		case SIGEV_NONE:
1132			info->notify.sigev_notify = SIGEV_NONE;
1133			break;
1134		case SIGEV_THREAD:
1135			info->notify_sock = sock;
1136			info->notify_cookie = nc;
1137			sock = NULL;
1138			nc = NULL;
1139			info->notify.sigev_notify = SIGEV_THREAD;
1140			break;
1141		case SIGEV_SIGNAL:
1142			info->notify.sigev_signo = notification.sigev_signo;
1143			info->notify.sigev_value = notification.sigev_value;
1144			info->notify.sigev_notify = SIGEV_SIGNAL;
1145			break;
1146		}
1147
1148		info->notify_owner = get_pid(task_tgid(current));
1149		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1150	}
1151	spin_unlock(&info->lock);
1152out_fput:
1153	fput(filp);
1154out:
1155	if (sock) {
1156		netlink_detachskb(sock, nc);
1157	} else if (nc) {
1158		dev_kfree_skb(nc);
1159	}
1160	return ret;
1161}
1162
1163SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1164		const struct mq_attr __user *, u_mqstat,
1165		struct mq_attr __user *, u_omqstat)
1166{
1167	int ret;
1168	struct mq_attr mqstat, omqstat;
1169	struct file *filp;
1170	struct inode *inode;
1171	struct mqueue_inode_info *info;
1172
1173	if (u_mqstat != NULL) {
1174		if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1175			return -EFAULT;
1176		if (mqstat.mq_flags & (~O_NONBLOCK))
1177			return -EINVAL;
1178	}
1179
1180	filp = fget(mqdes);
1181	if (!filp) {
1182		ret = -EBADF;
1183		goto out;
1184	}
1185
1186	inode = filp->f_path.dentry->d_inode;
1187	if (unlikely(filp->f_op != &mqueue_file_operations)) {
1188		ret = -EBADF;
1189		goto out_fput;
1190	}
1191	info = MQUEUE_I(inode);
1192
1193	spin_lock(&info->lock);
1194
1195	omqstat = info->attr;
1196	omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1197	if (u_mqstat) {
1198		audit_mq_getsetattr(mqdes, &mqstat);
1199		spin_lock(&filp->f_lock);
1200		if (mqstat.mq_flags & O_NONBLOCK)
1201			filp->f_flags |= O_NONBLOCK;
1202		else
1203			filp->f_flags &= ~O_NONBLOCK;
1204		spin_unlock(&filp->f_lock);
1205
1206		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1207	}
1208
1209	spin_unlock(&info->lock);
1210
1211	ret = 0;
1212	if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1213						sizeof(struct mq_attr)))
1214		ret = -EFAULT;
1215
1216out_fput:
1217	fput(filp);
1218out:
1219	return ret;
1220}
1221
1222static const struct inode_operations mqueue_dir_inode_operations = {
1223	.lookup = simple_lookup,
1224	.create = mqueue_create,
1225	.unlink = mqueue_unlink,
1226};
1227
1228static const struct file_operations mqueue_file_operations = {
1229	.flush = mqueue_flush_file,
1230	.poll = mqueue_poll_file,
1231	.read = mqueue_read_file,
1232	.llseek = default_llseek,
1233};
1234
1235static const struct super_operations mqueue_super_ops = {
1236	.alloc_inode = mqueue_alloc_inode,
1237	.destroy_inode = mqueue_destroy_inode,
1238	.evict_inode = mqueue_evict_inode,
1239	.statfs = simple_statfs,
1240};
1241
1242static struct file_system_type mqueue_fs_type = {
1243	.name = "mqueue",
1244	.mount = mqueue_mount,
1245	.kill_sb = kill_litter_super,
1246};
1247
1248int mq_init_ns(struct ipc_namespace *ns)
1249{
1250	ns->mq_queues_count  = 0;
1251	ns->mq_queues_max    = DFLT_QUEUESMAX;
1252	ns->mq_msg_max       = DFLT_MSGMAX;
1253	ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1254
1255	ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1256	if (IS_ERR(ns->mq_mnt)) {
1257		int err = PTR_ERR(ns->mq_mnt);
1258		ns->mq_mnt = NULL;
1259		return err;
1260	}
1261	return 0;
1262}
1263
1264void mq_clear_sbinfo(struct ipc_namespace *ns)
1265{
1266	ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1267}
1268
1269void mq_put_mnt(struct ipc_namespace *ns)
1270{
1271	kern_unmount(ns->mq_mnt);
1272}
1273
1274static int __init init_mqueue_fs(void)
1275{
1276	int error;
1277
1278	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1279				sizeof(struct mqueue_inode_info), 0,
1280				SLAB_HWCACHE_ALIGN, init_once);
1281	if (mqueue_inode_cachep == NULL)
1282		return -ENOMEM;
1283
1284	/* ignore failures - they are not fatal */
1285	mq_sysctl_table = mq_register_sysctl_table();
1286
1287	error = register_filesystem(&mqueue_fs_type);
1288	if (error)
1289		goto out_sysctl;
1290
1291	spin_lock_init(&mq_lock);
1292
1293	error = mq_init_ns(&init_ipc_ns);
1294	if (error)
1295		goto out_filesystem;
1296
1297	return 0;
1298
1299out_filesystem:
1300	unregister_filesystem(&mqueue_fs_type);
1301out_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