mqueue.c revision 4fc03b9beb2314f3adb9e72b7935a80c577954d1 
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
33#include <net/sock.h>
34#include "util.h"
35
36#define MQUEUE_MAGIC	0x19800202
37#define DIRENT_SIZE	20
38#define FILENT_SIZE	80
39
40#define SEND		0
41#define RECV		1
42
43#define STATE_NONE	0
44#define STATE_PENDING	1
45#define STATE_READY	2
46
47/* used by sysctl */
48#define FS_MQUEUE 	1
49#define CTL_QUEUESMAX 	2
50#define CTL_MSGMAX 	3
51#define CTL_MSGSIZEMAX 	4
52
53/* default values */
54#define DFLT_QUEUESMAX	256	/* max number of message queues */
55#define DFLT_MSGMAX 	10	/* max number of messages in each queue */
56#define HARD_MSGMAX 	(131072/sizeof(void*))
57#define DFLT_MSGSIZEMAX 8192	/* max message size */
58
59
60struct ext_wait_queue {		/* queue of sleeping tasks */
61	struct task_struct *task;
62	struct list_head list;
63	struct msg_msg *msg;	/* ptr of loaded message */
64	int state;		/* one of STATE_* values */
65};
66
67struct mqueue_inode_info {
68	spinlock_t lock;
69	struct inode vfs_inode;
70	wait_queue_head_t wait_q;
71
72	struct msg_msg **messages;
73	struct mq_attr attr;
74
75	struct sigevent notify;
76	struct pid* notify_owner;
77	struct user_struct *user;	/* user who created, for accounting */
78	struct sock *notify_sock;
79	struct sk_buff *notify_cookie;
80
81	/* for tasks waiting for free space and messages, respectively */
82	struct ext_wait_queue e_wait_q[2];
83
84	unsigned long qsize; /* size of queue in memory (sum of all msgs) */
85};
86
87static const struct inode_operations mqueue_dir_inode_operations;
88static const struct file_operations mqueue_file_operations;
89static struct super_operations mqueue_super_ops;
90static void remove_notification(struct mqueue_inode_info *info);
91
92static spinlock_t mq_lock;
93static struct kmem_cache *mqueue_inode_cachep;
94static struct vfsmount *mqueue_mnt;
95
96static unsigned int queues_count;
97static unsigned int queues_max 	= DFLT_QUEUESMAX;
98static unsigned int msg_max 	= DFLT_MSGMAX;
99static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
100
101static struct ctl_table_header * mq_sysctl_table;
102
103static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
104{
105	return container_of(inode, struct mqueue_inode_info, vfs_inode);
106}
107
108static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
109							struct mq_attr *attr)
110{
111	struct inode *inode;
112
113	inode = new_inode(sb);
114	if (inode) {
115		inode->i_mode = mode;
116		inode->i_uid = current->fsuid;
117		inode->i_gid = current->fsgid;
118		inode->i_blocks = 0;
119		inode->i_mtime = inode->i_ctime = inode->i_atime =
120				CURRENT_TIME;
121
122		if (S_ISREG(mode)) {
123			struct mqueue_inode_info *info;
124			struct task_struct *p = current;
125			struct user_struct *u = p->user;
126			unsigned long mq_bytes, mq_msg_tblsz;
127
128			inode->i_fop = &mqueue_file_operations;
129			inode->i_size = FILENT_SIZE;
130			/* mqueue specific info */
131			info = MQUEUE_I(inode);
132			spin_lock_init(&info->lock);
133			init_waitqueue_head(&info->wait_q);
134			INIT_LIST_HEAD(&info->e_wait_q[0].list);
135			INIT_LIST_HEAD(&info->e_wait_q[1].list);
136			info->messages = NULL;
137			info->notify_owner = NULL;
138			info->qsize = 0;
139			info->user = NULL;	/* set when all is ok */
140			memset(&info->attr, 0, sizeof(info->attr));
141			info->attr.mq_maxmsg = DFLT_MSGMAX;
142			info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
143			if (attr) {
144				info->attr.mq_maxmsg = attr->mq_maxmsg;
145				info->attr.mq_msgsize = attr->mq_msgsize;
146			}
147			mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
148			mq_bytes = (mq_msg_tblsz +
149				(info->attr.mq_maxmsg * info->attr.mq_msgsize));
150
151			spin_lock(&mq_lock);
152			if (u->mq_bytes + mq_bytes < u->mq_bytes ||
153		 	    u->mq_bytes + mq_bytes >
154			    p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
155				spin_unlock(&mq_lock);
156				goto out_inode;
157			}
158			u->mq_bytes += mq_bytes;
159			spin_unlock(&mq_lock);
160
161			info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
162			if (!info->messages) {
163				spin_lock(&mq_lock);
164				u->mq_bytes -= mq_bytes;
165				spin_unlock(&mq_lock);
166				goto out_inode;
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;
179out_inode:
180	make_bad_inode(inode);
181	iput(inode);
182	return NULL;
183}
184
185static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
186{
187	struct inode *inode;
188
189	sb->s_blocksize = PAGE_CACHE_SIZE;
190	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
191	sb->s_magic = MQUEUE_MAGIC;
192	sb->s_op = &mqueue_super_ops;
193
194	inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
195	if (!inode)
196		return -ENOMEM;
197
198	sb->s_root = d_alloc_root(inode);
199	if (!sb->s_root) {
200		iput(inode);
201		return -ENOMEM;
202	}
203
204	return 0;
205}
206
207static int mqueue_get_sb(struct file_system_type *fs_type,
208			 int flags, const char *dev_name,
209			 void *data, struct vfsmount *mnt)
210{
211	return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
212}
213
214static void init_once(void *foo, struct kmem_cache * cachep, unsigned long flags)
215{
216	struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
217
218	if (flags & SLAB_CTOR_CONSTRUCTOR)
219		inode_init_once(&p->vfs_inode);
220}
221
222static struct inode *mqueue_alloc_inode(struct super_block *sb)
223{
224	struct mqueue_inode_info *ei;
225
226	ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
227	if (!ei)
228		return NULL;
229	return &ei->vfs_inode;
230}
231
232static void mqueue_destroy_inode(struct inode *inode)
233{
234	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
235}
236
237static void mqueue_delete_inode(struct inode *inode)
238{
239	struct mqueue_inode_info *info;
240	struct user_struct *user;
241	unsigned long mq_bytes;
242	int i;
243
244	if (S_ISDIR(inode->i_mode)) {
245		clear_inode(inode);
246		return;
247	}
248	info = MQUEUE_I(inode);
249	spin_lock(&info->lock);
250	for (i = 0; i < info->attr.mq_curmsgs; i++)
251		free_msg(info->messages[i]);
252	kfree(info->messages);
253	spin_unlock(&info->lock);
254
255	clear_inode(inode);
256
257	mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
258		   (info->attr.mq_maxmsg * info->attr.mq_msgsize));
259	user = info->user;
260	if (user) {
261		spin_lock(&mq_lock);
262		user->mq_bytes -= mq_bytes;
263		queues_count--;
264		spin_unlock(&mq_lock);
265		free_uid(user);
266	}
267}
268
269static int mqueue_create(struct inode *dir, struct dentry *dentry,
270				int mode, struct nameidata *nd)
271{
272	struct inode *inode;
273	struct mq_attr *attr = dentry->d_fsdata;
274	int error;
275
276	spin_lock(&mq_lock);
277	if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
278		error = -ENOSPC;
279		goto out_lock;
280	}
281	queues_count++;
282	spin_unlock(&mq_lock);
283
284	inode = mqueue_get_inode(dir->i_sb, mode, attr);
285	if (!inode) {
286		error = -ENOMEM;
287		spin_lock(&mq_lock);
288		queues_count--;
289		goto out_lock;
290	}
291
292	dir->i_size += DIRENT_SIZE;
293	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
294
295	d_instantiate(dentry, inode);
296	dget(dentry);
297	return 0;
298out_lock:
299	spin_unlock(&mq_lock);
300	return error;
301}
302
303static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
304{
305  	struct inode *inode = dentry->d_inode;
306
307	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
308	dir->i_size -= DIRENT_SIZE;
309  	drop_nlink(inode);
310  	dput(dentry);
311  	return 0;
312}
313
314/*
315*	This is routine for system read from queue file.
316*	To avoid mess with doing here some sort of mq_receive we allow
317*	to read only queue size & notification info (the only values
318*	that are interesting from user point of view and aren't accessible
319*	through std routines)
320*/
321static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
322				size_t count, loff_t * off)
323{
324	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
325	char buffer[FILENT_SIZE];
326	size_t slen;
327	loff_t o;
328
329	if (!count)
330		return 0;
331
332	spin_lock(&info->lock);
333	snprintf(buffer, sizeof(buffer),
334			"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
335			info->qsize,
336			info->notify_owner ? info->notify.sigev_notify : 0,
337			(info->notify_owner &&
338			 info->notify.sigev_notify == SIGEV_SIGNAL) ?
339				info->notify.sigev_signo : 0,
340			pid_nr(info->notify_owner));
341	spin_unlock(&info->lock);
342	buffer[sizeof(buffer)-1] = '\0';
343	slen = strlen(buffer)+1;
344
345	o = *off;
346	if (o > slen)
347		return 0;
348
349	if (o + count > slen)
350		count = slen - o;
351
352	if (copy_to_user(u_data, buffer + o, count))
353		return -EFAULT;
354
355	*off = o + count;
356	filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
357	return count;
358}
359
360static int mqueue_flush_file(struct file *filp, fl_owner_t id)
361{
362	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
363
364	spin_lock(&info->lock);
365	if (task_tgid(current) == info->notify_owner)
366		remove_notification(info);
367
368	spin_unlock(&info->lock);
369	return 0;
370}
371
372static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
373{
374	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
375	int retval = 0;
376
377	poll_wait(filp, &info->wait_q, poll_tab);
378
379	spin_lock(&info->lock);
380	if (info->attr.mq_curmsgs)
381		retval = POLLIN | POLLRDNORM;
382
383	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
384		retval |= POLLOUT | POLLWRNORM;
385	spin_unlock(&info->lock);
386
387	return retval;
388}
389
390/* Adds current to info->e_wait_q[sr] before element with smaller prio */
391static void wq_add(struct mqueue_inode_info *info, int sr,
392			struct ext_wait_queue *ewp)
393{
394	struct ext_wait_queue *walk;
395
396	ewp->task = current;
397
398	list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
399		if (walk->task->static_prio <= current->static_prio) {
400			list_add_tail(&ewp->list, &walk->list);
401			return;
402		}
403	}
404	list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
405}
406
407/*
408 * Puts current task to sleep. Caller must hold queue lock. After return
409 * lock isn't held.
410 * sr: SEND or RECV
411 */
412static int wq_sleep(struct mqueue_inode_info *info, int sr,
413			long timeout, struct ext_wait_queue *ewp)
414{
415	int retval;
416	signed long time;
417
418	wq_add(info, sr, ewp);
419
420	for (;;) {
421		set_current_state(TASK_INTERRUPTIBLE);
422
423		spin_unlock(&info->lock);
424		time = schedule_timeout(timeout);
425
426		while (ewp->state == STATE_PENDING)
427			cpu_relax();
428
429		if (ewp->state == STATE_READY) {
430			retval = 0;
431			goto out;
432		}
433		spin_lock(&info->lock);
434		if (ewp->state == STATE_READY) {
435			retval = 0;
436			goto out_unlock;
437		}
438		if (signal_pending(current)) {
439			retval = -ERESTARTSYS;
440			break;
441		}
442		if (time == 0) {
443			retval = -ETIMEDOUT;
444			break;
445		}
446	}
447	list_del(&ewp->list);
448out_unlock:
449	spin_unlock(&info->lock);
450out:
451	return retval;
452}
453
454/*
455 * Returns waiting task that should be serviced first or NULL if none exists
456 */
457static struct ext_wait_queue *wq_get_first_waiter(
458		struct mqueue_inode_info *info, int sr)
459{
460	struct list_head *ptr;
461
462	ptr = info->e_wait_q[sr].list.prev;
463	if (ptr == &info->e_wait_q[sr].list)
464		return NULL;
465	return list_entry(ptr, struct ext_wait_queue, list);
466}
467
468/* Auxiliary functions to manipulate messages' list */
469static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
470{
471	int k;
472
473	k = info->attr.mq_curmsgs - 1;
474	while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
475		info->messages[k + 1] = info->messages[k];
476		k--;
477	}
478	info->attr.mq_curmsgs++;
479	info->qsize += ptr->m_ts;
480	info->messages[k + 1] = ptr;
481}
482
483static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
484{
485	info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
486	return info->messages[info->attr.mq_curmsgs];
487}
488
489static inline void set_cookie(struct sk_buff *skb, char code)
490{
491	((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
492}
493
494/*
495 * The next function is only to split too long sys_mq_timedsend
496 */
497static void __do_notify(struct mqueue_inode_info *info)
498{
499	/* notification
500	 * invoked when there is registered process and there isn't process
501	 * waiting synchronously for message AND state of queue changed from
502	 * empty to not empty. Here we are sure that no one is waiting
503	 * synchronously. */
504	if (info->notify_owner &&
505	    info->attr.mq_curmsgs == 1) {
506		struct siginfo sig_i;
507		switch (info->notify.sigev_notify) {
508		case SIGEV_NONE:
509			break;
510		case SIGEV_SIGNAL:
511			/* sends signal */
512
513			sig_i.si_signo = info->notify.sigev_signo;
514			sig_i.si_errno = 0;
515			sig_i.si_code = SI_MESGQ;
516			sig_i.si_value = info->notify.sigev_value;
517			sig_i.si_pid = current->tgid;
518			sig_i.si_uid = current->uid;
519
520			kill_pid_info(info->notify.sigev_signo,
521				      &sig_i, info->notify_owner);
522			break;
523		case SIGEV_THREAD:
524			set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
525			netlink_sendskb(info->notify_sock,
526					info->notify_cookie, 0);
527			break;
528		}
529		/* after notification unregisters process */
530		put_pid(info->notify_owner);
531		info->notify_owner = NULL;
532	}
533	wake_up(&info->wait_q);
534}
535
536static long prepare_timeout(const struct timespec __user *u_arg)
537{
538	struct timespec ts, nowts;
539	long timeout;
540
541	if (u_arg) {
542		if (unlikely(copy_from_user(&ts, u_arg,
543					sizeof(struct timespec))))
544			return -EFAULT;
545
546		if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
547			|| ts.tv_nsec >= NSEC_PER_SEC))
548			return -EINVAL;
549		nowts = CURRENT_TIME;
550		/* first subtract as jiffies can't be too big */
551		ts.tv_sec -= nowts.tv_sec;
552		if (ts.tv_nsec < nowts.tv_nsec) {
553			ts.tv_nsec += NSEC_PER_SEC;
554			ts.tv_sec--;
555		}
556		ts.tv_nsec -= nowts.tv_nsec;
557		if (ts.tv_sec < 0)
558			return 0;
559
560		timeout = timespec_to_jiffies(&ts) + 1;
561	} else
562		return MAX_SCHEDULE_TIMEOUT;
563
564	return timeout;
565}
566
567static void remove_notification(struct mqueue_inode_info *info)
568{
569	if (info->notify_owner != NULL &&
570	    info->notify.sigev_notify == SIGEV_THREAD) {
571		set_cookie(info->notify_cookie, NOTIFY_REMOVED);
572		netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
573	}
574	put_pid(info->notify_owner);
575	info->notify_owner = NULL;
576}
577
578static int mq_attr_ok(struct mq_attr *attr)
579{
580	if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
581		return 0;
582	if (capable(CAP_SYS_RESOURCE)) {
583		if (attr->mq_maxmsg > HARD_MSGMAX)
584			return 0;
585	} else {
586		if (attr->mq_maxmsg > msg_max ||
587				attr->mq_msgsize > msgsize_max)
588			return 0;
589	}
590	/* check for overflow */
591	if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
592		return 0;
593	if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
594	    (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
595	    (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
596		return 0;
597	return 1;
598}
599
600/*
601 * Invoked when creating a new queue via sys_mq_open
602 */
603static struct file *do_create(struct dentry *dir, struct dentry *dentry,
604			int oflag, mode_t mode, struct mq_attr __user *u_attr)
605{
606	struct mq_attr attr;
607	int ret;
608
609	if (u_attr) {
610		ret = -EFAULT;
611		if (copy_from_user(&attr, u_attr, sizeof(attr)))
612			goto out;
613		ret = -EINVAL;
614		if (!mq_attr_ok(&attr))
615			goto out;
616		/* store for use during create */
617		dentry->d_fsdata = &attr;
618	}
619
620	mode &= ~current->fs->umask;
621	ret = vfs_create(dir->d_inode, dentry, mode, NULL);
622	dentry->d_fsdata = NULL;
623	if (ret)
624		goto out;
625
626	return dentry_open(dentry, mqueue_mnt, oflag);
627
628out:
629	dput(dentry);
630	mntput(mqueue_mnt);
631	return ERR_PTR(ret);
632}
633
634/* Opens existing queue */
635static struct file *do_open(struct dentry *dentry, int oflag)
636{
637static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
638					MAY_READ | MAY_WRITE };
639
640	if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
641		dput(dentry);
642		mntput(mqueue_mnt);
643		return ERR_PTR(-EINVAL);
644	}
645
646	if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
647		dput(dentry);
648		mntput(mqueue_mnt);
649		return ERR_PTR(-EACCES);
650	}
651
652	return dentry_open(dentry, mqueue_mnt, oflag);
653}
654
655asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
656				struct mq_attr __user *u_attr)
657{
658	struct dentry *dentry;
659	struct file *filp;
660	char *name;
661	int fd, error;
662
663	error = audit_mq_open(oflag, mode, u_attr);
664	if (error != 0)
665		return error;
666
667	if (IS_ERR(name = getname(u_name)))
668		return PTR_ERR(name);
669
670	fd = get_unused_fd();
671	if (fd < 0)
672		goto out_putname;
673
674	mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
675	dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
676	if (IS_ERR(dentry)) {
677		error = PTR_ERR(dentry);
678		goto out_err;
679	}
680	mntget(mqueue_mnt);
681
682	if (oflag & O_CREAT) {
683		if (dentry->d_inode) {	/* entry already exists */
684			audit_inode(name, dentry->d_inode);
685			error = -EEXIST;
686			if (oflag & O_EXCL)
687				goto out;
688			filp = do_open(dentry, oflag);
689		} else {
690			filp = do_create(mqueue_mnt->mnt_root, dentry,
691						oflag, mode, u_attr);
692		}
693	} else {
694		error = -ENOENT;
695		if (!dentry->d_inode)
696			goto out;
697		audit_inode(name, dentry->d_inode);
698		filp = do_open(dentry, oflag);
699	}
700
701	if (IS_ERR(filp)) {
702		error = PTR_ERR(filp);
703		goto out_putfd;
704	}
705
706	set_close_on_exec(fd, 1);
707	fd_install(fd, filp);
708	goto out_upsem;
709
710out:
711	dput(dentry);
712	mntput(mqueue_mnt);
713out_putfd:
714	put_unused_fd(fd);
715out_err:
716	fd = error;
717out_upsem:
718	mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
719out_putname:
720	putname(name);
721	return fd;
722}
723
724asmlinkage long sys_mq_unlink(const char __user *u_name)
725{
726	int err;
727	char *name;
728	struct dentry *dentry;
729	struct inode *inode = NULL;
730
731	name = getname(u_name);
732	if (IS_ERR(name))
733		return PTR_ERR(name);
734
735	mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
736			I_MUTEX_PARENT);
737	dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
738	if (IS_ERR(dentry)) {
739		err = PTR_ERR(dentry);
740		goto out_unlock;
741	}
742
743	if (!dentry->d_inode) {
744		err = -ENOENT;
745		goto out_err;
746	}
747
748	inode = dentry->d_inode;
749	if (inode)
750		atomic_inc(&inode->i_count);
751
752	err = vfs_unlink(dentry->d_parent->d_inode, dentry);
753out_err:
754	dput(dentry);
755
756out_unlock:
757	mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
758	putname(name);
759	if (inode)
760		iput(inode);
761
762	return err;
763}
764
765/* Pipelined send and receive functions.
766 *
767 * If a receiver finds no waiting message, then it registers itself in the
768 * list of waiting receivers. A sender checks that list before adding the new
769 * message into the message array. If there is a waiting receiver, then it
770 * bypasses the message array and directly hands the message over to the
771 * receiver.
772 * The receiver accepts the message and returns without grabbing the queue
773 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
774 * are necessary. The same algorithm is used for sysv semaphores, see
775 * ipc/sem.c for more details.
776 *
777 * The same algorithm is used for senders.
778 */
779
780/* pipelined_send() - send a message directly to the task waiting in
781 * sys_mq_timedreceive() (without inserting message into a queue).
782 */
783static inline void pipelined_send(struct mqueue_inode_info *info,
784				  struct msg_msg *message,
785				  struct ext_wait_queue *receiver)
786{
787	receiver->msg = message;
788	list_del(&receiver->list);
789	receiver->state = STATE_PENDING;
790	wake_up_process(receiver->task);
791	smp_wmb();
792	receiver->state = STATE_READY;
793}
794
795/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
796 * gets its message and put to the queue (we have one free place for sure). */
797static inline void pipelined_receive(struct mqueue_inode_info *info)
798{
799	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
800
801	if (!sender) {
802		/* for poll */
803		wake_up_interruptible(&info->wait_q);
804		return;
805	}
806	msg_insert(sender->msg, info);
807	list_del(&sender->list);
808	sender->state = STATE_PENDING;
809	wake_up_process(sender->task);
810	smp_wmb();
811	sender->state = STATE_READY;
812}
813
814asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
815	size_t msg_len, unsigned int msg_prio,
816	const struct timespec __user *u_abs_timeout)
817{
818	struct file *filp;
819	struct inode *inode;
820	struct ext_wait_queue wait;
821	struct ext_wait_queue *receiver;
822	struct msg_msg *msg_ptr;
823	struct mqueue_inode_info *info;
824	long timeout;
825	int ret;
826
827	ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
828	if (ret != 0)
829		return ret;
830
831	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
832		return -EINVAL;
833
834	timeout = prepare_timeout(u_abs_timeout);
835
836	ret = -EBADF;
837	filp = fget(mqdes);
838	if (unlikely(!filp))
839		goto out;
840
841	inode = filp->f_path.dentry->d_inode;
842	if (unlikely(filp->f_op != &mqueue_file_operations))
843		goto out_fput;
844	info = MQUEUE_I(inode);
845	audit_inode(NULL, inode);
846
847	if (unlikely(!(filp->f_mode & FMODE_WRITE)))
848		goto out_fput;
849
850	if (unlikely(msg_len > info->attr.mq_msgsize)) {
851		ret = -EMSGSIZE;
852		goto out_fput;
853	}
854
855	/* First try to allocate memory, before doing anything with
856	 * existing queues. */
857	msg_ptr = load_msg(u_msg_ptr, msg_len);
858	if (IS_ERR(msg_ptr)) {
859		ret = PTR_ERR(msg_ptr);
860		goto out_fput;
861	}
862	msg_ptr->m_ts = msg_len;
863	msg_ptr->m_type = msg_prio;
864
865	spin_lock(&info->lock);
866
867	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
868		if (filp->f_flags & O_NONBLOCK) {
869			spin_unlock(&info->lock);
870			ret = -EAGAIN;
871		} else if (unlikely(timeout < 0)) {
872			spin_unlock(&info->lock);
873			ret = timeout;
874		} else {
875			wait.task = current;
876			wait.msg = (void *) msg_ptr;
877			wait.state = STATE_NONE;
878			ret = wq_sleep(info, SEND, timeout, &wait);
879		}
880		if (ret < 0)
881			free_msg(msg_ptr);
882	} else {
883		receiver = wq_get_first_waiter(info, RECV);
884		if (receiver) {
885			pipelined_send(info, msg_ptr, receiver);
886		} else {
887			/* adds message to the queue */
888			msg_insert(msg_ptr, info);
889			__do_notify(info);
890		}
891		inode->i_atime = inode->i_mtime = inode->i_ctime =
892				CURRENT_TIME;
893		spin_unlock(&info->lock);
894		ret = 0;
895	}
896out_fput:
897	fput(filp);
898out:
899	return ret;
900}
901
902asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
903	size_t msg_len, unsigned int __user *u_msg_prio,
904	const struct timespec __user *u_abs_timeout)
905{
906	long timeout;
907	ssize_t ret;
908	struct msg_msg *msg_ptr;
909	struct file *filp;
910	struct inode *inode;
911	struct mqueue_inode_info *info;
912	struct ext_wait_queue wait;
913
914	ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
915	if (ret != 0)
916		return ret;
917
918	timeout = prepare_timeout(u_abs_timeout);
919
920	ret = -EBADF;
921	filp = fget(mqdes);
922	if (unlikely(!filp))
923		goto out;
924
925	inode = filp->f_path.dentry->d_inode;
926	if (unlikely(filp->f_op != &mqueue_file_operations))
927		goto out_fput;
928	info = MQUEUE_I(inode);
929	audit_inode(NULL, inode);
930
931	if (unlikely(!(filp->f_mode & FMODE_READ)))
932		goto out_fput;
933
934	/* checks if buffer is big enough */
935	if (unlikely(msg_len < info->attr.mq_msgsize)) {
936		ret = -EMSGSIZE;
937		goto out_fput;
938	}
939
940	spin_lock(&info->lock);
941	if (info->attr.mq_curmsgs == 0) {
942		if (filp->f_flags & O_NONBLOCK) {
943			spin_unlock(&info->lock);
944			ret = -EAGAIN;
945			msg_ptr = NULL;
946		} else if (unlikely(timeout < 0)) {
947			spin_unlock(&info->lock);
948			ret = timeout;
949			msg_ptr = NULL;
950		} else {
951			wait.task = current;
952			wait.state = STATE_NONE;
953			ret = wq_sleep(info, RECV, timeout, &wait);
954			msg_ptr = wait.msg;
955		}
956	} else {
957		msg_ptr = msg_get(info);
958
959		inode->i_atime = inode->i_mtime = inode->i_ctime =
960				CURRENT_TIME;
961
962		/* There is now free space in queue. */
963		pipelined_receive(info);
964		spin_unlock(&info->lock);
965		ret = 0;
966	}
967	if (ret == 0) {
968		ret = msg_ptr->m_ts;
969
970		if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
971			store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
972			ret = -EFAULT;
973		}
974		free_msg(msg_ptr);
975	}
976out_fput:
977	fput(filp);
978out:
979	return ret;
980}
981
982/*
983 * Notes: the case when user wants us to deregister (with NULL as pointer)
984 * and he isn't currently owner of notification, will be silently discarded.
985 * It isn't explicitly defined in the POSIX.
986 */
987asmlinkage long sys_mq_notify(mqd_t mqdes,
988				const struct sigevent __user *u_notification)
989{
990	int ret;
991	struct file *filp;
992	struct sock *sock;
993	struct inode *inode;
994	struct sigevent notification;
995	struct mqueue_inode_info *info;
996	struct sk_buff *nc;
997
998	ret = audit_mq_notify(mqdes, u_notification);
999	if (ret != 0)
1000		return ret;
1001
1002	nc = NULL;
1003	sock = NULL;
1004	if (u_notification != NULL) {
1005		if (copy_from_user(&notification, u_notification,
1006					sizeof(struct sigevent)))
1007			return -EFAULT;
1008
1009		if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1010			     notification.sigev_notify != SIGEV_SIGNAL &&
1011			     notification.sigev_notify != SIGEV_THREAD))
1012			return -EINVAL;
1013		if (notification.sigev_notify == SIGEV_SIGNAL &&
1014			!valid_signal(notification.sigev_signo)) {
1015			return -EINVAL;
1016		}
1017		if (notification.sigev_notify == SIGEV_THREAD) {
1018			/* create the notify skb */
1019			nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1020			ret = -ENOMEM;
1021			if (!nc)
1022				goto out;
1023			ret = -EFAULT;
1024			if (copy_from_user(nc->data,
1025					notification.sigev_value.sival_ptr,
1026					NOTIFY_COOKIE_LEN)) {
1027				goto out;
1028			}
1029
1030			/* TODO: add a header? */
1031			skb_put(nc, NOTIFY_COOKIE_LEN);
1032			/* and attach it to the socket */
1033retry:
1034			filp = fget(notification.sigev_signo);
1035			ret = -EBADF;
1036			if (!filp)
1037				goto out;
1038			sock = netlink_getsockbyfilp(filp);
1039			fput(filp);
1040			if (IS_ERR(sock)) {
1041				ret = PTR_ERR(sock);
1042				sock = NULL;
1043				goto out;
1044			}
1045
1046			ret = netlink_attachskb(sock, nc, 0,
1047					MAX_SCHEDULE_TIMEOUT, NULL);
1048			if (ret == 1)
1049		       		goto retry;
1050			if (ret) {
1051				sock = NULL;
1052				nc = NULL;
1053				goto out;
1054			}
1055		}
1056	}
1057
1058	ret = -EBADF;
1059	filp = fget(mqdes);
1060	if (!filp)
1061		goto out;
1062
1063	inode = filp->f_path.dentry->d_inode;
1064	if (unlikely(filp->f_op != &mqueue_file_operations))
1065		goto out_fput;
1066	info = MQUEUE_I(inode);
1067
1068	ret = 0;
1069	spin_lock(&info->lock);
1070	if (u_notification == NULL) {
1071		if (info->notify_owner == task_tgid(current)) {
1072			remove_notification(info);
1073			inode->i_atime = inode->i_ctime = CURRENT_TIME;
1074		}
1075	} else if (info->notify_owner != NULL) {
1076		ret = -EBUSY;
1077	} else {
1078		switch (notification.sigev_notify) {
1079		case SIGEV_NONE:
1080			info->notify.sigev_notify = SIGEV_NONE;
1081			break;
1082		case SIGEV_THREAD:
1083			info->notify_sock = sock;
1084			info->notify_cookie = nc;
1085			sock = NULL;
1086			nc = NULL;
1087			info->notify.sigev_notify = SIGEV_THREAD;
1088			break;
1089		case SIGEV_SIGNAL:
1090			info->notify.sigev_signo = notification.sigev_signo;
1091			info->notify.sigev_value = notification.sigev_value;
1092			info->notify.sigev_notify = SIGEV_SIGNAL;
1093			break;
1094		}
1095
1096		info->notify_owner = get_pid(task_tgid(current));
1097		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1098	}
1099	spin_unlock(&info->lock);
1100out_fput:
1101	fput(filp);
1102out:
1103	if (sock) {
1104		netlink_detachskb(sock, nc);
1105	} else if (nc) {
1106		dev_kfree_skb(nc);
1107	}
1108	return ret;
1109}
1110
1111asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1112			const struct mq_attr __user *u_mqstat,
1113			struct mq_attr __user *u_omqstat)
1114{
1115	int ret;
1116	struct mq_attr mqstat, omqstat;
1117	struct file *filp;
1118	struct inode *inode;
1119	struct mqueue_inode_info *info;
1120
1121	if (u_mqstat != NULL) {
1122		if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1123			return -EFAULT;
1124		if (mqstat.mq_flags & (~O_NONBLOCK))
1125			return -EINVAL;
1126	}
1127
1128	ret = -EBADF;
1129	filp = fget(mqdes);
1130	if (!filp)
1131		goto out;
1132
1133	inode = filp->f_path.dentry->d_inode;
1134	if (unlikely(filp->f_op != &mqueue_file_operations))
1135		goto out_fput;
1136	info = MQUEUE_I(inode);
1137
1138	spin_lock(&info->lock);
1139
1140	omqstat = info->attr;
1141	omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1142	if (u_mqstat) {
1143		ret = audit_mq_getsetattr(mqdes, &mqstat);
1144		if (ret != 0)
1145			goto out;
1146		if (mqstat.mq_flags & O_NONBLOCK)
1147			filp->f_flags |= O_NONBLOCK;
1148		else
1149			filp->f_flags &= ~O_NONBLOCK;
1150
1151		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1152	}
1153
1154	spin_unlock(&info->lock);
1155
1156	ret = 0;
1157	if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1158						sizeof(struct mq_attr)))
1159		ret = -EFAULT;
1160
1161out_fput:
1162	fput(filp);
1163out:
1164	return ret;
1165}
1166
1167static const struct inode_operations mqueue_dir_inode_operations = {
1168	.lookup = simple_lookup,
1169	.create = mqueue_create,
1170	.unlink = mqueue_unlink,
1171};
1172
1173static const struct file_operations mqueue_file_operations = {
1174	.flush = mqueue_flush_file,
1175	.poll = mqueue_poll_file,
1176	.read = mqueue_read_file,
1177};
1178
1179static struct super_operations mqueue_super_ops = {
1180	.alloc_inode = mqueue_alloc_inode,
1181	.destroy_inode = mqueue_destroy_inode,
1182	.statfs = simple_statfs,
1183	.delete_inode = mqueue_delete_inode,
1184	.drop_inode = generic_delete_inode,
1185};
1186
1187static struct file_system_type mqueue_fs_type = {
1188	.name = "mqueue",
1189	.get_sb = mqueue_get_sb,
1190	.kill_sb = kill_litter_super,
1191};
1192
1193static int msg_max_limit_min = DFLT_MSGMAX;
1194static int msg_max_limit_max = HARD_MSGMAX;
1195
1196static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1197static int msg_maxsize_limit_max = INT_MAX;
1198
1199static ctl_table mq_sysctls[] = {
1200	{
1201		.ctl_name	= CTL_QUEUESMAX,
1202		.procname	= "queues_max",
1203		.data		= &queues_max,
1204		.maxlen		= sizeof(int),
1205		.mode		= 0644,
1206		.proc_handler	= &proc_dointvec,
1207	},
1208	{
1209		.ctl_name	= CTL_MSGMAX,
1210		.procname	= "msg_max",
1211		.data		= &msg_max,
1212		.maxlen		= sizeof(int),
1213		.mode		= 0644,
1214		.proc_handler	= &proc_dointvec_minmax,
1215		.extra1		= &msg_max_limit_min,
1216		.extra2		= &msg_max_limit_max,
1217	},
1218	{
1219		.ctl_name	= CTL_MSGSIZEMAX,
1220		.procname	= "msgsize_max",
1221		.data		= &msgsize_max,
1222		.maxlen		= sizeof(int),
1223		.mode		= 0644,
1224		.proc_handler	= &proc_dointvec_minmax,
1225		.extra1		= &msg_maxsize_limit_min,
1226		.extra2		= &msg_maxsize_limit_max,
1227	},
1228	{ .ctl_name = 0 }
1229};
1230
1231static ctl_table mq_sysctl_dir[] = {
1232	{
1233		.ctl_name	= FS_MQUEUE,
1234		.procname	= "mqueue",
1235		.mode		= 0555,
1236		.child		= mq_sysctls,
1237	},
1238	{ .ctl_name = 0 }
1239};
1240
1241static ctl_table mq_sysctl_root[] = {
1242	{
1243		.ctl_name	= CTL_FS,
1244		.procname	= "fs",
1245		.mode		= 0555,
1246		.child		= mq_sysctl_dir,
1247	},
1248	{ .ctl_name = 0 }
1249};
1250
1251static int __init init_mqueue_fs(void)
1252{
1253	int error;
1254
1255	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1256				sizeof(struct mqueue_inode_info), 0,
1257				SLAB_HWCACHE_ALIGN, init_once, NULL);
1258	if (mqueue_inode_cachep == NULL)
1259		return -ENOMEM;
1260
1261	/* ignore failues - they are not fatal */
1262	mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1263
1264	error = register_filesystem(&mqueue_fs_type);
1265	if (error)
1266		goto out_sysctl;
1267
1268	if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1269		error = PTR_ERR(mqueue_mnt);
1270		goto out_filesystem;
1271	}
1272
1273	/* internal initialization - not common for vfs */
1274	queues_count = 0;
1275	spin_lock_init(&mq_lock);
1276
1277	return 0;
1278
1279out_filesystem:
1280	unregister_filesystem(&mqueue_fs_type);
1281out_sysctl:
1282	if (mq_sysctl_table)
1283		unregister_sysctl_table(mq_sysctl_table);
1284	kmem_cache_destroy(mqueue_inode_cachep);
1285	return error;
1286}
1287
1288__initcall(init_mqueue_fs);
1289