mqueue.c revision 50953fe9e00ebbeffa032a565ab2f08312d51a87 
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			error = -EEXIST;
685			if (oflag & O_EXCL)
686				goto out;
687			filp = do_open(dentry, oflag);
688		} else {
689			filp = do_create(mqueue_mnt->mnt_root, dentry,
690						oflag, mode, u_attr);
691		}
692	} else {
693		error = -ENOENT;
694		if (!dentry->d_inode)
695			goto out;
696		filp = do_open(dentry, oflag);
697	}
698
699	if (IS_ERR(filp)) {
700		error = PTR_ERR(filp);
701		goto out_putfd;
702	}
703
704	set_close_on_exec(fd, 1);
705	fd_install(fd, filp);
706	goto out_upsem;
707
708out:
709	dput(dentry);
710	mntput(mqueue_mnt);
711out_putfd:
712	put_unused_fd(fd);
713out_err:
714	fd = error;
715out_upsem:
716	mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
717out_putname:
718	putname(name);
719	return fd;
720}
721
722asmlinkage long sys_mq_unlink(const char __user *u_name)
723{
724	int err;
725	char *name;
726	struct dentry *dentry;
727	struct inode *inode = NULL;
728
729	name = getname(u_name);
730	if (IS_ERR(name))
731		return PTR_ERR(name);
732
733	mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
734			I_MUTEX_PARENT);
735	dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
736	if (IS_ERR(dentry)) {
737		err = PTR_ERR(dentry);
738		goto out_unlock;
739	}
740
741	if (!dentry->d_inode) {
742		err = -ENOENT;
743		goto out_err;
744	}
745
746	inode = dentry->d_inode;
747	if (inode)
748		atomic_inc(&inode->i_count);
749
750	err = vfs_unlink(dentry->d_parent->d_inode, dentry);
751out_err:
752	dput(dentry);
753
754out_unlock:
755	mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
756	putname(name);
757	if (inode)
758		iput(inode);
759
760	return err;
761}
762
763/* Pipelined send and receive functions.
764 *
765 * If a receiver finds no waiting message, then it registers itself in the
766 * list of waiting receivers. A sender checks that list before adding the new
767 * message into the message array. If there is a waiting receiver, then it
768 * bypasses the message array and directly hands the message over to the
769 * receiver.
770 * The receiver accepts the message and returns without grabbing the queue
771 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
772 * are necessary. The same algorithm is used for sysv semaphores, see
773 * ipc/sem.c for more details.
774 *
775 * The same algorithm is used for senders.
776 */
777
778/* pipelined_send() - send a message directly to the task waiting in
779 * sys_mq_timedreceive() (without inserting message into a queue).
780 */
781static inline void pipelined_send(struct mqueue_inode_info *info,
782				  struct msg_msg *message,
783				  struct ext_wait_queue *receiver)
784{
785	receiver->msg = message;
786	list_del(&receiver->list);
787	receiver->state = STATE_PENDING;
788	wake_up_process(receiver->task);
789	smp_wmb();
790	receiver->state = STATE_READY;
791}
792
793/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
794 * gets its message and put to the queue (we have one free place for sure). */
795static inline void pipelined_receive(struct mqueue_inode_info *info)
796{
797	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
798
799	if (!sender) {
800		/* for poll */
801		wake_up_interruptible(&info->wait_q);
802		return;
803	}
804	msg_insert(sender->msg, info);
805	list_del(&sender->list);
806	sender->state = STATE_PENDING;
807	wake_up_process(sender->task);
808	smp_wmb();
809	sender->state = STATE_READY;
810}
811
812asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
813	size_t msg_len, unsigned int msg_prio,
814	const struct timespec __user *u_abs_timeout)
815{
816	struct file *filp;
817	struct inode *inode;
818	struct ext_wait_queue wait;
819	struct ext_wait_queue *receiver;
820	struct msg_msg *msg_ptr;
821	struct mqueue_inode_info *info;
822	long timeout;
823	int ret;
824
825	ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
826	if (ret != 0)
827		return ret;
828
829	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
830		return -EINVAL;
831
832	timeout = prepare_timeout(u_abs_timeout);
833
834	ret = -EBADF;
835	filp = fget(mqdes);
836	if (unlikely(!filp))
837		goto out;
838
839	inode = filp->f_path.dentry->d_inode;
840	if (unlikely(filp->f_op != &mqueue_file_operations))
841		goto out_fput;
842	info = MQUEUE_I(inode);
843
844	if (unlikely(!(filp->f_mode & FMODE_WRITE)))
845		goto out_fput;
846
847	if (unlikely(msg_len > info->attr.mq_msgsize)) {
848		ret = -EMSGSIZE;
849		goto out_fput;
850	}
851
852	/* First try to allocate memory, before doing anything with
853	 * existing queues. */
854	msg_ptr = load_msg(u_msg_ptr, msg_len);
855	if (IS_ERR(msg_ptr)) {
856		ret = PTR_ERR(msg_ptr);
857		goto out_fput;
858	}
859	msg_ptr->m_ts = msg_len;
860	msg_ptr->m_type = msg_prio;
861
862	spin_lock(&info->lock);
863
864	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
865		if (filp->f_flags & O_NONBLOCK) {
866			spin_unlock(&info->lock);
867			ret = -EAGAIN;
868		} else if (unlikely(timeout < 0)) {
869			spin_unlock(&info->lock);
870			ret = timeout;
871		} else {
872			wait.task = current;
873			wait.msg = (void *) msg_ptr;
874			wait.state = STATE_NONE;
875			ret = wq_sleep(info, SEND, timeout, &wait);
876		}
877		if (ret < 0)
878			free_msg(msg_ptr);
879	} else {
880		receiver = wq_get_first_waiter(info, RECV);
881		if (receiver) {
882			pipelined_send(info, msg_ptr, receiver);
883		} else {
884			/* adds message to the queue */
885			msg_insert(msg_ptr, info);
886			__do_notify(info);
887		}
888		inode->i_atime = inode->i_mtime = inode->i_ctime =
889				CURRENT_TIME;
890		spin_unlock(&info->lock);
891		ret = 0;
892	}
893out_fput:
894	fput(filp);
895out:
896	return ret;
897}
898
899asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
900	size_t msg_len, unsigned int __user *u_msg_prio,
901	const struct timespec __user *u_abs_timeout)
902{
903	long timeout;
904	ssize_t ret;
905	struct msg_msg *msg_ptr;
906	struct file *filp;
907	struct inode *inode;
908	struct mqueue_inode_info *info;
909	struct ext_wait_queue wait;
910
911	ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
912	if (ret != 0)
913		return ret;
914
915	timeout = prepare_timeout(u_abs_timeout);
916
917	ret = -EBADF;
918	filp = fget(mqdes);
919	if (unlikely(!filp))
920		goto out;
921
922	inode = filp->f_path.dentry->d_inode;
923	if (unlikely(filp->f_op != &mqueue_file_operations))
924		goto out_fput;
925	info = MQUEUE_I(inode);
926
927	if (unlikely(!(filp->f_mode & FMODE_READ)))
928		goto out_fput;
929
930	/* checks if buffer is big enough */
931	if (unlikely(msg_len < info->attr.mq_msgsize)) {
932		ret = -EMSGSIZE;
933		goto out_fput;
934	}
935
936	spin_lock(&info->lock);
937	if (info->attr.mq_curmsgs == 0) {
938		if (filp->f_flags & O_NONBLOCK) {
939			spin_unlock(&info->lock);
940			ret = -EAGAIN;
941			msg_ptr = NULL;
942		} else if (unlikely(timeout < 0)) {
943			spin_unlock(&info->lock);
944			ret = timeout;
945			msg_ptr = NULL;
946		} else {
947			wait.task = current;
948			wait.state = STATE_NONE;
949			ret = wq_sleep(info, RECV, timeout, &wait);
950			msg_ptr = wait.msg;
951		}
952	} else {
953		msg_ptr = msg_get(info);
954
955		inode->i_atime = inode->i_mtime = inode->i_ctime =
956				CURRENT_TIME;
957
958		/* There is now free space in queue. */
959		pipelined_receive(info);
960		spin_unlock(&info->lock);
961		ret = 0;
962	}
963	if (ret == 0) {
964		ret = msg_ptr->m_ts;
965
966		if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
967			store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
968			ret = -EFAULT;
969		}
970		free_msg(msg_ptr);
971	}
972out_fput:
973	fput(filp);
974out:
975	return ret;
976}
977
978/*
979 * Notes: the case when user wants us to deregister (with NULL as pointer)
980 * and he isn't currently owner of notification, will be silently discarded.
981 * It isn't explicitly defined in the POSIX.
982 */
983asmlinkage long sys_mq_notify(mqd_t mqdes,
984				const struct sigevent __user *u_notification)
985{
986	int ret;
987	struct file *filp;
988	struct sock *sock;
989	struct inode *inode;
990	struct sigevent notification;
991	struct mqueue_inode_info *info;
992	struct sk_buff *nc;
993
994	ret = audit_mq_notify(mqdes, u_notification);
995	if (ret != 0)
996		return ret;
997
998	nc = NULL;
999	sock = NULL;
1000	if (u_notification != NULL) {
1001		if (copy_from_user(&notification, u_notification,
1002					sizeof(struct sigevent)))
1003			return -EFAULT;
1004
1005		if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1006			     notification.sigev_notify != SIGEV_SIGNAL &&
1007			     notification.sigev_notify != SIGEV_THREAD))
1008			return -EINVAL;
1009		if (notification.sigev_notify == SIGEV_SIGNAL &&
1010			!valid_signal(notification.sigev_signo)) {
1011			return -EINVAL;
1012		}
1013		if (notification.sigev_notify == SIGEV_THREAD) {
1014			/* create the notify skb */
1015			nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1016			ret = -ENOMEM;
1017			if (!nc)
1018				goto out;
1019			ret = -EFAULT;
1020			if (copy_from_user(nc->data,
1021					notification.sigev_value.sival_ptr,
1022					NOTIFY_COOKIE_LEN)) {
1023				goto out;
1024			}
1025
1026			/* TODO: add a header? */
1027			skb_put(nc, NOTIFY_COOKIE_LEN);
1028			/* and attach it to the socket */
1029retry:
1030			filp = fget(notification.sigev_signo);
1031			ret = -EBADF;
1032			if (!filp)
1033				goto out;
1034			sock = netlink_getsockbyfilp(filp);
1035			fput(filp);
1036			if (IS_ERR(sock)) {
1037				ret = PTR_ERR(sock);
1038				sock = NULL;
1039				goto out;
1040			}
1041
1042			ret = netlink_attachskb(sock, nc, 0,
1043					MAX_SCHEDULE_TIMEOUT, NULL);
1044			if (ret == 1)
1045		       		goto retry;
1046			if (ret) {
1047				sock = NULL;
1048				nc = NULL;
1049				goto out;
1050			}
1051		}
1052	}
1053
1054	ret = -EBADF;
1055	filp = fget(mqdes);
1056	if (!filp)
1057		goto out;
1058
1059	inode = filp->f_path.dentry->d_inode;
1060	if (unlikely(filp->f_op != &mqueue_file_operations))
1061		goto out_fput;
1062	info = MQUEUE_I(inode);
1063
1064	ret = 0;
1065	spin_lock(&info->lock);
1066	if (u_notification == NULL) {
1067		if (info->notify_owner == task_tgid(current)) {
1068			remove_notification(info);
1069			inode->i_atime = inode->i_ctime = CURRENT_TIME;
1070		}
1071	} else if (info->notify_owner != NULL) {
1072		ret = -EBUSY;
1073	} else {
1074		switch (notification.sigev_notify) {
1075		case SIGEV_NONE:
1076			info->notify.sigev_notify = SIGEV_NONE;
1077			break;
1078		case SIGEV_THREAD:
1079			info->notify_sock = sock;
1080			info->notify_cookie = nc;
1081			sock = NULL;
1082			nc = NULL;
1083			info->notify.sigev_notify = SIGEV_THREAD;
1084			break;
1085		case SIGEV_SIGNAL:
1086			info->notify.sigev_signo = notification.sigev_signo;
1087			info->notify.sigev_value = notification.sigev_value;
1088			info->notify.sigev_notify = SIGEV_SIGNAL;
1089			break;
1090		}
1091
1092		info->notify_owner = get_pid(task_tgid(current));
1093		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1094	}
1095	spin_unlock(&info->lock);
1096out_fput:
1097	fput(filp);
1098out:
1099	if (sock) {
1100		netlink_detachskb(sock, nc);
1101	} else if (nc) {
1102		dev_kfree_skb(nc);
1103	}
1104	return ret;
1105}
1106
1107asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1108			const struct mq_attr __user *u_mqstat,
1109			struct mq_attr __user *u_omqstat)
1110{
1111	int ret;
1112	struct mq_attr mqstat, omqstat;
1113	struct file *filp;
1114	struct inode *inode;
1115	struct mqueue_inode_info *info;
1116
1117	if (u_mqstat != NULL) {
1118		if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1119			return -EFAULT;
1120		if (mqstat.mq_flags & (~O_NONBLOCK))
1121			return -EINVAL;
1122	}
1123
1124	ret = -EBADF;
1125	filp = fget(mqdes);
1126	if (!filp)
1127		goto out;
1128
1129	inode = filp->f_path.dentry->d_inode;
1130	if (unlikely(filp->f_op != &mqueue_file_operations))
1131		goto out_fput;
1132	info = MQUEUE_I(inode);
1133
1134	spin_lock(&info->lock);
1135
1136	omqstat = info->attr;
1137	omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1138	if (u_mqstat) {
1139		ret = audit_mq_getsetattr(mqdes, &mqstat);
1140		if (ret != 0)
1141			goto out;
1142		if (mqstat.mq_flags & O_NONBLOCK)
1143			filp->f_flags |= O_NONBLOCK;
1144		else
1145			filp->f_flags &= ~O_NONBLOCK;
1146
1147		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1148	}
1149
1150	spin_unlock(&info->lock);
1151
1152	ret = 0;
1153	if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1154						sizeof(struct mq_attr)))
1155		ret = -EFAULT;
1156
1157out_fput:
1158	fput(filp);
1159out:
1160	return ret;
1161}
1162
1163static const struct inode_operations mqueue_dir_inode_operations = {
1164	.lookup = simple_lookup,
1165	.create = mqueue_create,
1166	.unlink = mqueue_unlink,
1167};
1168
1169static const struct file_operations mqueue_file_operations = {
1170	.flush = mqueue_flush_file,
1171	.poll = mqueue_poll_file,
1172	.read = mqueue_read_file,
1173};
1174
1175static struct super_operations mqueue_super_ops = {
1176	.alloc_inode = mqueue_alloc_inode,
1177	.destroy_inode = mqueue_destroy_inode,
1178	.statfs = simple_statfs,
1179	.delete_inode = mqueue_delete_inode,
1180	.drop_inode = generic_delete_inode,
1181};
1182
1183static struct file_system_type mqueue_fs_type = {
1184	.name = "mqueue",
1185	.get_sb = mqueue_get_sb,
1186	.kill_sb = kill_litter_super,
1187};
1188
1189static int msg_max_limit_min = DFLT_MSGMAX;
1190static int msg_max_limit_max = HARD_MSGMAX;
1191
1192static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1193static int msg_maxsize_limit_max = INT_MAX;
1194
1195static ctl_table mq_sysctls[] = {
1196	{
1197		.ctl_name	= CTL_QUEUESMAX,
1198		.procname	= "queues_max",
1199		.data		= &queues_max,
1200		.maxlen		= sizeof(int),
1201		.mode		= 0644,
1202		.proc_handler	= &proc_dointvec,
1203	},
1204	{
1205		.ctl_name	= CTL_MSGMAX,
1206		.procname	= "msg_max",
1207		.data		= &msg_max,
1208		.maxlen		= sizeof(int),
1209		.mode		= 0644,
1210		.proc_handler	= &proc_dointvec_minmax,
1211		.extra1		= &msg_max_limit_min,
1212		.extra2		= &msg_max_limit_max,
1213	},
1214	{
1215		.ctl_name	= CTL_MSGSIZEMAX,
1216		.procname	= "msgsize_max",
1217		.data		= &msgsize_max,
1218		.maxlen		= sizeof(int),
1219		.mode		= 0644,
1220		.proc_handler	= &proc_dointvec_minmax,
1221		.extra1		= &msg_maxsize_limit_min,
1222		.extra2		= &msg_maxsize_limit_max,
1223	},
1224	{ .ctl_name = 0 }
1225};
1226
1227static ctl_table mq_sysctl_dir[] = {
1228	{
1229		.ctl_name	= FS_MQUEUE,
1230		.procname	= "mqueue",
1231		.mode		= 0555,
1232		.child		= mq_sysctls,
1233	},
1234	{ .ctl_name = 0 }
1235};
1236
1237static ctl_table mq_sysctl_root[] = {
1238	{
1239		.ctl_name	= CTL_FS,
1240		.procname	= "fs",
1241		.mode		= 0555,
1242		.child		= mq_sysctl_dir,
1243	},
1244	{ .ctl_name = 0 }
1245};
1246
1247static int __init init_mqueue_fs(void)
1248{
1249	int error;
1250
1251	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1252				sizeof(struct mqueue_inode_info), 0,
1253				SLAB_HWCACHE_ALIGN, init_once, NULL);
1254	if (mqueue_inode_cachep == NULL)
1255		return -ENOMEM;
1256
1257	/* ignore failues - they are not fatal */
1258	mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1259
1260	error = register_filesystem(&mqueue_fs_type);
1261	if (error)
1262		goto out_sysctl;
1263
1264	if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1265		error = PTR_ERR(mqueue_mnt);
1266		goto out_filesystem;
1267	}
1268
1269	/* internal initialization - not common for vfs */
1270	queues_count = 0;
1271	spin_lock_init(&mq_lock);
1272
1273	return 0;
1274
1275out_filesystem:
1276	unregister_filesystem(&mqueue_fs_type);
1277out_sysctl:
1278	if (mq_sysctl_table)
1279		unregister_sysctl_table(mq_sysctl_table);
1280	kmem_cache_destroy(mqueue_inode_cachep);
1281	return error;
1282}
1283
1284__initcall(init_mqueue_fs);
1285