mqueue.c revision 7ee015e0fa3c856416e9477aac4b850ec6f09017 
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	inode_init_once(&p->vfs_inode);
219}
220
221static struct inode *mqueue_alloc_inode(struct super_block *sb)
222{
223	struct mqueue_inode_info *ei;
224
225	ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
226	if (!ei)
227		return NULL;
228	return &ei->vfs_inode;
229}
230
231static void mqueue_destroy_inode(struct inode *inode)
232{
233	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
234}
235
236static void mqueue_delete_inode(struct inode *inode)
237{
238	struct mqueue_inode_info *info;
239	struct user_struct *user;
240	unsigned long mq_bytes;
241	int i;
242
243	if (S_ISDIR(inode->i_mode)) {
244		clear_inode(inode);
245		return;
246	}
247	info = MQUEUE_I(inode);
248	spin_lock(&info->lock);
249	for (i = 0; i < info->attr.mq_curmsgs; i++)
250		free_msg(info->messages[i]);
251	kfree(info->messages);
252	spin_unlock(&info->lock);
253
254	clear_inode(inode);
255
256	mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
257		   (info->attr.mq_maxmsg * info->attr.mq_msgsize));
258	user = info->user;
259	if (user) {
260		spin_lock(&mq_lock);
261		user->mq_bytes -= mq_bytes;
262		queues_count--;
263		spin_unlock(&mq_lock);
264		free_uid(user);
265	}
266}
267
268static int mqueue_create(struct inode *dir, struct dentry *dentry,
269				int mode, struct nameidata *nd)
270{
271	struct inode *inode;
272	struct mq_attr *attr = dentry->d_fsdata;
273	int error;
274
275	spin_lock(&mq_lock);
276	if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
277		error = -ENOSPC;
278		goto out_lock;
279	}
280	queues_count++;
281	spin_unlock(&mq_lock);
282
283	inode = mqueue_get_inode(dir->i_sb, mode, attr);
284	if (!inode) {
285		error = -ENOMEM;
286		spin_lock(&mq_lock);
287		queues_count--;
288		goto out_lock;
289	}
290
291	dir->i_size += DIRENT_SIZE;
292	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
293
294	d_instantiate(dentry, inode);
295	dget(dentry);
296	return 0;
297out_lock:
298	spin_unlock(&mq_lock);
299	return error;
300}
301
302static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
303{
304  	struct inode *inode = dentry->d_inode;
305
306	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
307	dir->i_size -= DIRENT_SIZE;
308  	drop_nlink(inode);
309  	dput(dentry);
310  	return 0;
311}
312
313/*
314*	This is routine for system read from queue file.
315*	To avoid mess with doing here some sort of mq_receive we allow
316*	to read only queue size & notification info (the only values
317*	that are interesting from user point of view and aren't accessible
318*	through std routines)
319*/
320static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
321				size_t count, loff_t * off)
322{
323	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
324	char buffer[FILENT_SIZE];
325	size_t slen;
326	loff_t o;
327
328	if (!count)
329		return 0;
330
331	spin_lock(&info->lock);
332	snprintf(buffer, sizeof(buffer),
333			"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
334			info->qsize,
335			info->notify_owner ? info->notify.sigev_notify : 0,
336			(info->notify_owner &&
337			 info->notify.sigev_notify == SIGEV_SIGNAL) ?
338				info->notify.sigev_signo : 0,
339			pid_nr(info->notify_owner));
340	spin_unlock(&info->lock);
341	buffer[sizeof(buffer)-1] = '\0';
342	slen = strlen(buffer)+1;
343
344	o = *off;
345	if (o > slen)
346		return 0;
347
348	if (o + count > slen)
349		count = slen - o;
350
351	if (copy_to_user(u_data, buffer + o, count))
352		return -EFAULT;
353
354	*off = o + count;
355	filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
356	return count;
357}
358
359static int mqueue_flush_file(struct file *filp, fl_owner_t id)
360{
361	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
362
363	spin_lock(&info->lock);
364	if (task_tgid(current) == info->notify_owner)
365		remove_notification(info);
366
367	spin_unlock(&info->lock);
368	return 0;
369}
370
371static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
372{
373	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
374	int retval = 0;
375
376	poll_wait(filp, &info->wait_q, poll_tab);
377
378	spin_lock(&info->lock);
379	if (info->attr.mq_curmsgs)
380		retval = POLLIN | POLLRDNORM;
381
382	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
383		retval |= POLLOUT | POLLWRNORM;
384	spin_unlock(&info->lock);
385
386	return retval;
387}
388
389/* Adds current to info->e_wait_q[sr] before element with smaller prio */
390static void wq_add(struct mqueue_inode_info *info, int sr,
391			struct ext_wait_queue *ewp)
392{
393	struct ext_wait_queue *walk;
394
395	ewp->task = current;
396
397	list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
398		if (walk->task->static_prio <= current->static_prio) {
399			list_add_tail(&ewp->list, &walk->list);
400			return;
401		}
402	}
403	list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
404}
405
406/*
407 * Puts current task to sleep. Caller must hold queue lock. After return
408 * lock isn't held.
409 * sr: SEND or RECV
410 */
411static int wq_sleep(struct mqueue_inode_info *info, int sr,
412			long timeout, struct ext_wait_queue *ewp)
413{
414	int retval;
415	signed long time;
416
417	wq_add(info, sr, ewp);
418
419	for (;;) {
420		set_current_state(TASK_INTERRUPTIBLE);
421
422		spin_unlock(&info->lock);
423		time = schedule_timeout(timeout);
424
425		while (ewp->state == STATE_PENDING)
426			cpu_relax();
427
428		if (ewp->state == STATE_READY) {
429			retval = 0;
430			goto out;
431		}
432		spin_lock(&info->lock);
433		if (ewp->state == STATE_READY) {
434			retval = 0;
435			goto out_unlock;
436		}
437		if (signal_pending(current)) {
438			retval = -ERESTARTSYS;
439			break;
440		}
441		if (time == 0) {
442			retval = -ETIMEDOUT;
443			break;
444		}
445	}
446	list_del(&ewp->list);
447out_unlock:
448	spin_unlock(&info->lock);
449out:
450	return retval;
451}
452
453/*
454 * Returns waiting task that should be serviced first or NULL if none exists
455 */
456static struct ext_wait_queue *wq_get_first_waiter(
457		struct mqueue_inode_info *info, int sr)
458{
459	struct list_head *ptr;
460
461	ptr = info->e_wait_q[sr].list.prev;
462	if (ptr == &info->e_wait_q[sr].list)
463		return NULL;
464	return list_entry(ptr, struct ext_wait_queue, list);
465}
466
467/* Auxiliary functions to manipulate messages' list */
468static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
469{
470	int k;
471
472	k = info->attr.mq_curmsgs - 1;
473	while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
474		info->messages[k + 1] = info->messages[k];
475		k--;
476	}
477	info->attr.mq_curmsgs++;
478	info->qsize += ptr->m_ts;
479	info->messages[k + 1] = ptr;
480}
481
482static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
483{
484	info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
485	return info->messages[info->attr.mq_curmsgs];
486}
487
488static inline void set_cookie(struct sk_buff *skb, char code)
489{
490	((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
491}
492
493/*
494 * The next function is only to split too long sys_mq_timedsend
495 */
496static void __do_notify(struct mqueue_inode_info *info)
497{
498	/* notification
499	 * invoked when there is registered process and there isn't process
500	 * waiting synchronously for message AND state of queue changed from
501	 * empty to not empty. Here we are sure that no one is waiting
502	 * synchronously. */
503	if (info->notify_owner &&
504	    info->attr.mq_curmsgs == 1) {
505		struct siginfo sig_i;
506		switch (info->notify.sigev_notify) {
507		case SIGEV_NONE:
508			break;
509		case SIGEV_SIGNAL:
510			/* sends signal */
511
512			sig_i.si_signo = info->notify.sigev_signo;
513			sig_i.si_errno = 0;
514			sig_i.si_code = SI_MESGQ;
515			sig_i.si_value = info->notify.sigev_value;
516			sig_i.si_pid = current->tgid;
517			sig_i.si_uid = current->uid;
518
519			kill_pid_info(info->notify.sigev_signo,
520				      &sig_i, info->notify_owner);
521			break;
522		case SIGEV_THREAD:
523			set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
524			netlink_sendskb(info->notify_sock, info->notify_cookie);
525			break;
526		}
527		/* after notification unregisters process */
528		put_pid(info->notify_owner);
529		info->notify_owner = NULL;
530	}
531	wake_up(&info->wait_q);
532}
533
534static long prepare_timeout(const struct timespec __user *u_arg)
535{
536	struct timespec ts, nowts;
537	long timeout;
538
539	if (u_arg) {
540		if (unlikely(copy_from_user(&ts, u_arg,
541					sizeof(struct timespec))))
542			return -EFAULT;
543
544		if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
545			|| ts.tv_nsec >= NSEC_PER_SEC))
546			return -EINVAL;
547		nowts = CURRENT_TIME;
548		/* first subtract as jiffies can't be too big */
549		ts.tv_sec -= nowts.tv_sec;
550		if (ts.tv_nsec < nowts.tv_nsec) {
551			ts.tv_nsec += NSEC_PER_SEC;
552			ts.tv_sec--;
553		}
554		ts.tv_nsec -= nowts.tv_nsec;
555		if (ts.tv_sec < 0)
556			return 0;
557
558		timeout = timespec_to_jiffies(&ts) + 1;
559	} else
560		return MAX_SCHEDULE_TIMEOUT;
561
562	return timeout;
563}
564
565static void remove_notification(struct mqueue_inode_info *info)
566{
567	if (info->notify_owner != NULL &&
568	    info->notify.sigev_notify == SIGEV_THREAD) {
569		set_cookie(info->notify_cookie, NOTIFY_REMOVED);
570		netlink_sendskb(info->notify_sock, info->notify_cookie);
571	}
572	put_pid(info->notify_owner);
573	info->notify_owner = NULL;
574}
575
576static int mq_attr_ok(struct mq_attr *attr)
577{
578	if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
579		return 0;
580	if (capable(CAP_SYS_RESOURCE)) {
581		if (attr->mq_maxmsg > HARD_MSGMAX)
582			return 0;
583	} else {
584		if (attr->mq_maxmsg > msg_max ||
585				attr->mq_msgsize > msgsize_max)
586			return 0;
587	}
588	/* check for overflow */
589	if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
590		return 0;
591	if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
592	    (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
593	    (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
594		return 0;
595	return 1;
596}
597
598/*
599 * Invoked when creating a new queue via sys_mq_open
600 */
601static struct file *do_create(struct dentry *dir, struct dentry *dentry,
602			int oflag, mode_t mode, struct mq_attr __user *u_attr)
603{
604	struct mq_attr attr;
605	int ret;
606
607	if (u_attr) {
608		ret = -EFAULT;
609		if (copy_from_user(&attr, u_attr, sizeof(attr)))
610			goto out;
611		ret = -EINVAL;
612		if (!mq_attr_ok(&attr))
613			goto out;
614		/* store for use during create */
615		dentry->d_fsdata = &attr;
616	}
617
618	mode &= ~current->fs->umask;
619	ret = vfs_create(dir->d_inode, dentry, mode, NULL);
620	dentry->d_fsdata = NULL;
621	if (ret)
622		goto out;
623
624	return dentry_open(dentry, mqueue_mnt, oflag);
625
626out:
627	dput(dentry);
628	mntput(mqueue_mnt);
629	return ERR_PTR(ret);
630}
631
632/* Opens existing queue */
633static struct file *do_open(struct dentry *dentry, int oflag)
634{
635static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
636					MAY_READ | MAY_WRITE };
637
638	if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
639		dput(dentry);
640		mntput(mqueue_mnt);
641		return ERR_PTR(-EINVAL);
642	}
643
644	if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
645		dput(dentry);
646		mntput(mqueue_mnt);
647		return ERR_PTR(-EACCES);
648	}
649
650	return dentry_open(dentry, mqueue_mnt, oflag);
651}
652
653asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
654				struct mq_attr __user *u_attr)
655{
656	struct dentry *dentry;
657	struct file *filp;
658	char *name;
659	int fd, error;
660
661	error = audit_mq_open(oflag, mode, u_attr);
662	if (error != 0)
663		return error;
664
665	if (IS_ERR(name = getname(u_name)))
666		return PTR_ERR(name);
667
668	fd = get_unused_fd();
669	if (fd < 0)
670		goto out_putname;
671
672	mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
673	dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
674	if (IS_ERR(dentry)) {
675		error = PTR_ERR(dentry);
676		goto out_err;
677	}
678	mntget(mqueue_mnt);
679
680	if (oflag & O_CREAT) {
681		if (dentry->d_inode) {	/* entry already exists */
682			audit_inode(name, dentry->d_inode);
683			error = -EEXIST;
684			if (oflag & O_EXCL)
685				goto out;
686			filp = do_open(dentry, oflag);
687		} else {
688			filp = do_create(mqueue_mnt->mnt_root, dentry,
689						oflag, mode, u_attr);
690		}
691	} else {
692		error = -ENOENT;
693		if (!dentry->d_inode)
694			goto out;
695		audit_inode(name, dentry->d_inode);
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	audit_inode(NULL, inode);
844
845	if (unlikely(!(filp->f_mode & FMODE_WRITE)))
846		goto out_fput;
847
848	if (unlikely(msg_len > info->attr.mq_msgsize)) {
849		ret = -EMSGSIZE;
850		goto out_fput;
851	}
852
853	/* First try to allocate memory, before doing anything with
854	 * existing queues. */
855	msg_ptr = load_msg(u_msg_ptr, msg_len);
856	if (IS_ERR(msg_ptr)) {
857		ret = PTR_ERR(msg_ptr);
858		goto out_fput;
859	}
860	msg_ptr->m_ts = msg_len;
861	msg_ptr->m_type = msg_prio;
862
863	spin_lock(&info->lock);
864
865	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
866		if (filp->f_flags & O_NONBLOCK) {
867			spin_unlock(&info->lock);
868			ret = -EAGAIN;
869		} else if (unlikely(timeout < 0)) {
870			spin_unlock(&info->lock);
871			ret = timeout;
872		} else {
873			wait.task = current;
874			wait.msg = (void *) msg_ptr;
875			wait.state = STATE_NONE;
876			ret = wq_sleep(info, SEND, timeout, &wait);
877		}
878		if (ret < 0)
879			free_msg(msg_ptr);
880	} else {
881		receiver = wq_get_first_waiter(info, RECV);
882		if (receiver) {
883			pipelined_send(info, msg_ptr, receiver);
884		} else {
885			/* adds message to the queue */
886			msg_insert(msg_ptr, info);
887			__do_notify(info);
888		}
889		inode->i_atime = inode->i_mtime = inode->i_ctime =
890				CURRENT_TIME;
891		spin_unlock(&info->lock);
892		ret = 0;
893	}
894out_fput:
895	fput(filp);
896out:
897	return ret;
898}
899
900asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
901	size_t msg_len, unsigned int __user *u_msg_prio,
902	const struct timespec __user *u_abs_timeout)
903{
904	long timeout;
905	ssize_t ret;
906	struct msg_msg *msg_ptr;
907	struct file *filp;
908	struct inode *inode;
909	struct mqueue_inode_info *info;
910	struct ext_wait_queue wait;
911
912	ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
913	if (ret != 0)
914		return ret;
915
916	timeout = prepare_timeout(u_abs_timeout);
917
918	ret = -EBADF;
919	filp = fget(mqdes);
920	if (unlikely(!filp))
921		goto out;
922
923	inode = filp->f_path.dentry->d_inode;
924	if (unlikely(filp->f_op != &mqueue_file_operations))
925		goto out_fput;
926	info = MQUEUE_I(inode);
927	audit_inode(NULL, inode);
928
929	if (unlikely(!(filp->f_mode & FMODE_READ)))
930		goto out_fput;
931
932	/* checks if buffer is big enough */
933	if (unlikely(msg_len < info->attr.mq_msgsize)) {
934		ret = -EMSGSIZE;
935		goto out_fput;
936	}
937
938	spin_lock(&info->lock);
939	if (info->attr.mq_curmsgs == 0) {
940		if (filp->f_flags & O_NONBLOCK) {
941			spin_unlock(&info->lock);
942			ret = -EAGAIN;
943			msg_ptr = NULL;
944		} else if (unlikely(timeout < 0)) {
945			spin_unlock(&info->lock);
946			ret = timeout;
947			msg_ptr = NULL;
948		} else {
949			wait.task = current;
950			wait.state = STATE_NONE;
951			ret = wq_sleep(info, RECV, timeout, &wait);
952			msg_ptr = wait.msg;
953		}
954	} else {
955		msg_ptr = msg_get(info);
956
957		inode->i_atime = inode->i_mtime = inode->i_ctime =
958				CURRENT_TIME;
959
960		/* There is now free space in queue. */
961		pipelined_receive(info);
962		spin_unlock(&info->lock);
963		ret = 0;
964	}
965	if (ret == 0) {
966		ret = msg_ptr->m_ts;
967
968		if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
969			store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
970			ret = -EFAULT;
971		}
972		free_msg(msg_ptr);
973	}
974out_fput:
975	fput(filp);
976out:
977	return ret;
978}
979
980/*
981 * Notes: the case when user wants us to deregister (with NULL as pointer)
982 * and he isn't currently owner of notification, will be silently discarded.
983 * It isn't explicitly defined in the POSIX.
984 */
985asmlinkage long sys_mq_notify(mqd_t mqdes,
986				const struct sigevent __user *u_notification)
987{
988	int ret;
989	struct file *filp;
990	struct sock *sock;
991	struct inode *inode;
992	struct sigevent notification;
993	struct mqueue_inode_info *info;
994	struct sk_buff *nc;
995
996	ret = audit_mq_notify(mqdes, u_notification);
997	if (ret != 0)
998		return ret;
999
1000	nc = NULL;
1001	sock = NULL;
1002	if (u_notification != NULL) {
1003		if (copy_from_user(&notification, u_notification,
1004					sizeof(struct sigevent)))
1005			return -EFAULT;
1006
1007		if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1008			     notification.sigev_notify != SIGEV_SIGNAL &&
1009			     notification.sigev_notify != SIGEV_THREAD))
1010			return -EINVAL;
1011		if (notification.sigev_notify == SIGEV_SIGNAL &&
1012			!valid_signal(notification.sigev_signo)) {
1013			return -EINVAL;
1014		}
1015		if (notification.sigev_notify == SIGEV_THREAD) {
1016			/* create the notify skb */
1017			nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1018			ret = -ENOMEM;
1019			if (!nc)
1020				goto out;
1021			ret = -EFAULT;
1022			if (copy_from_user(nc->data,
1023					notification.sigev_value.sival_ptr,
1024					NOTIFY_COOKIE_LEN)) {
1025				goto out;
1026			}
1027
1028			/* TODO: add a header? */
1029			skb_put(nc, NOTIFY_COOKIE_LEN);
1030			/* and attach it to the socket */
1031retry:
1032			filp = fget(notification.sigev_signo);
1033			ret = -EBADF;
1034			if (!filp)
1035				goto out;
1036			sock = netlink_getsockbyfilp(filp);
1037			fput(filp);
1038			if (IS_ERR(sock)) {
1039				ret = PTR_ERR(sock);
1040				sock = NULL;
1041				goto out;
1042			}
1043
1044			ret = netlink_attachskb(sock, nc, 0,
1045					MAX_SCHEDULE_TIMEOUT, NULL);
1046			if (ret == 1)
1047		       		goto retry;
1048			if (ret) {
1049				sock = NULL;
1050				nc = NULL;
1051				goto out;
1052			}
1053		}
1054	}
1055
1056	ret = -EBADF;
1057	filp = fget(mqdes);
1058	if (!filp)
1059		goto out;
1060
1061	inode = filp->f_path.dentry->d_inode;
1062	if (unlikely(filp->f_op != &mqueue_file_operations))
1063		goto out_fput;
1064	info = MQUEUE_I(inode);
1065
1066	ret = 0;
1067	spin_lock(&info->lock);
1068	if (u_notification == NULL) {
1069		if (info->notify_owner == task_tgid(current)) {
1070			remove_notification(info);
1071			inode->i_atime = inode->i_ctime = CURRENT_TIME;
1072		}
1073	} else if (info->notify_owner != NULL) {
1074		ret = -EBUSY;
1075	} else {
1076		switch (notification.sigev_notify) {
1077		case SIGEV_NONE:
1078			info->notify.sigev_notify = SIGEV_NONE;
1079			break;
1080		case SIGEV_THREAD:
1081			info->notify_sock = sock;
1082			info->notify_cookie = nc;
1083			sock = NULL;
1084			nc = NULL;
1085			info->notify.sigev_notify = SIGEV_THREAD;
1086			break;
1087		case SIGEV_SIGNAL:
1088			info->notify.sigev_signo = notification.sigev_signo;
1089			info->notify.sigev_value = notification.sigev_value;
1090			info->notify.sigev_notify = SIGEV_SIGNAL;
1091			break;
1092		}
1093
1094		info->notify_owner = get_pid(task_tgid(current));
1095		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1096	}
1097	spin_unlock(&info->lock);
1098out_fput:
1099	fput(filp);
1100out:
1101	if (sock) {
1102		netlink_detachskb(sock, nc);
1103	} else if (nc) {
1104		dev_kfree_skb(nc);
1105	}
1106	return ret;
1107}
1108
1109asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1110			const struct mq_attr __user *u_mqstat,
1111			struct mq_attr __user *u_omqstat)
1112{
1113	int ret;
1114	struct mq_attr mqstat, omqstat;
1115	struct file *filp;
1116	struct inode *inode;
1117	struct mqueue_inode_info *info;
1118
1119	if (u_mqstat != NULL) {
1120		if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1121			return -EFAULT;
1122		if (mqstat.mq_flags & (~O_NONBLOCK))
1123			return -EINVAL;
1124	}
1125
1126	ret = -EBADF;
1127	filp = fget(mqdes);
1128	if (!filp)
1129		goto out;
1130
1131	inode = filp->f_path.dentry->d_inode;
1132	if (unlikely(filp->f_op != &mqueue_file_operations))
1133		goto out_fput;
1134	info = MQUEUE_I(inode);
1135
1136	spin_lock(&info->lock);
1137
1138	omqstat = info->attr;
1139	omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1140	if (u_mqstat) {
1141		ret = audit_mq_getsetattr(mqdes, &mqstat);
1142		if (ret != 0)
1143			goto out;
1144		if (mqstat.mq_flags & O_NONBLOCK)
1145			filp->f_flags |= O_NONBLOCK;
1146		else
1147			filp->f_flags &= ~O_NONBLOCK;
1148
1149		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1150	}
1151
1152	spin_unlock(&info->lock);
1153
1154	ret = 0;
1155	if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1156						sizeof(struct mq_attr)))
1157		ret = -EFAULT;
1158
1159out_fput:
1160	fput(filp);
1161out:
1162	return ret;
1163}
1164
1165static const struct inode_operations mqueue_dir_inode_operations = {
1166	.lookup = simple_lookup,
1167	.create = mqueue_create,
1168	.unlink = mqueue_unlink,
1169};
1170
1171static const struct file_operations mqueue_file_operations = {
1172	.flush = mqueue_flush_file,
1173	.poll = mqueue_poll_file,
1174	.read = mqueue_read_file,
1175};
1176
1177static struct super_operations mqueue_super_ops = {
1178	.alloc_inode = mqueue_alloc_inode,
1179	.destroy_inode = mqueue_destroy_inode,
1180	.statfs = simple_statfs,
1181	.delete_inode = mqueue_delete_inode,
1182	.drop_inode = generic_delete_inode,
1183};
1184
1185static struct file_system_type mqueue_fs_type = {
1186	.name = "mqueue",
1187	.get_sb = mqueue_get_sb,
1188	.kill_sb = kill_litter_super,
1189};
1190
1191static int msg_max_limit_min = DFLT_MSGMAX;
1192static int msg_max_limit_max = HARD_MSGMAX;
1193
1194static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1195static int msg_maxsize_limit_max = INT_MAX;
1196
1197static ctl_table mq_sysctls[] = {
1198	{
1199		.ctl_name	= CTL_QUEUESMAX,
1200		.procname	= "queues_max",
1201		.data		= &queues_max,
1202		.maxlen		= sizeof(int),
1203		.mode		= 0644,
1204		.proc_handler	= &proc_dointvec,
1205	},
1206	{
1207		.ctl_name	= CTL_MSGMAX,
1208		.procname	= "msg_max",
1209		.data		= &msg_max,
1210		.maxlen		= sizeof(int),
1211		.mode		= 0644,
1212		.proc_handler	= &proc_dointvec_minmax,
1213		.extra1		= &msg_max_limit_min,
1214		.extra2		= &msg_max_limit_max,
1215	},
1216	{
1217		.ctl_name	= CTL_MSGSIZEMAX,
1218		.procname	= "msgsize_max",
1219		.data		= &msgsize_max,
1220		.maxlen		= sizeof(int),
1221		.mode		= 0644,
1222		.proc_handler	= &proc_dointvec_minmax,
1223		.extra1		= &msg_maxsize_limit_min,
1224		.extra2		= &msg_maxsize_limit_max,
1225	},
1226	{ .ctl_name = 0 }
1227};
1228
1229static ctl_table mq_sysctl_dir[] = {
1230	{
1231		.ctl_name	= FS_MQUEUE,
1232		.procname	= "mqueue",
1233		.mode		= 0555,
1234		.child		= mq_sysctls,
1235	},
1236	{ .ctl_name = 0 }
1237};
1238
1239static ctl_table mq_sysctl_root[] = {
1240	{
1241		.ctl_name	= CTL_FS,
1242		.procname	= "fs",
1243		.mode		= 0555,
1244		.child		= mq_sysctl_dir,
1245	},
1246	{ .ctl_name = 0 }
1247};
1248
1249static int __init init_mqueue_fs(void)
1250{
1251	int error;
1252
1253	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1254				sizeof(struct mqueue_inode_info), 0,
1255				SLAB_HWCACHE_ALIGN, init_once);
1256	if (mqueue_inode_cachep == NULL)
1257		return -ENOMEM;
1258
1259	/* ignore failues - they are not fatal */
1260	mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1261
1262	error = register_filesystem(&mqueue_fs_type);
1263	if (error)
1264		goto out_sysctl;
1265
1266	if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1267		error = PTR_ERR(mqueue_mnt);
1268		goto out_filesystem;
1269	}
1270
1271	/* internal initialization - not common for vfs */
1272	queues_count = 0;
1273	spin_lock_init(&mq_lock);
1274
1275	return 0;
1276
1277out_filesystem:
1278	unregister_filesystem(&mqueue_fs_type);
1279out_sysctl:
1280	if (mq_sysctl_table)
1281		unregister_sysctl_table(mq_sysctl_table);
1282	kmem_cache_destroy(mqueue_inode_cachep);
1283	return error;
1284}
1285
1286__initcall(init_mqueue_fs);
1287