xref: /openbmc/linux/ipc/mqueue.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2  * POSIX message queues filesystem for Linux.
3  *
4  * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
5  *                          Michal Wronski          (wrona@mat.uni.torun.pl)
6  *
7  * Spinlocks:               Mohamed Abbas           (abbas.mohamed@intel.com)
8  * Lockless receive & send, fd based notify:
9  * 			    Manfred Spraul	    (manfred@colorfullife.com)
10  *
11  * This file is released under the GPL.
12  */
13 
14 #include <linux/init.h>
15 #include <linux/pagemap.h>
16 #include <linux/file.h>
17 #include <linux/mount.h>
18 #include <linux/namei.h>
19 #include <linux/sysctl.h>
20 #include <linux/poll.h>
21 #include <linux/mqueue.h>
22 #include <linux/msg.h>
23 #include <linux/skbuff.h>
24 #include <linux/netlink.h>
25 #include <linux/syscalls.h>
26 #include <linux/signal.h>
27 #include <net/sock.h>
28 #include "util.h"
29 
30 #define MQUEUE_MAGIC	0x19800202
31 #define DIRENT_SIZE	20
32 #define FILENT_SIZE	80
33 
34 #define SEND		0
35 #define RECV		1
36 
37 #define STATE_NONE	0
38 #define STATE_PENDING	1
39 #define STATE_READY	2
40 
41 /* used by sysctl */
42 #define FS_MQUEUE 	1
43 #define CTL_QUEUESMAX 	2
44 #define CTL_MSGMAX 	3
45 #define CTL_MSGSIZEMAX 	4
46 
47 /* default values */
48 #define DFLT_QUEUESMAX	256	/* max number of message queues */
49 #define DFLT_MSGMAX 	10	/* max number of messages in each queue */
50 #define HARD_MSGMAX 	(131072/sizeof(void*))
51 #define DFLT_MSGSIZEMAX 8192	/* max message size */
52 
53 #define NOTIFY_COOKIE_LEN	32
54 
55 struct ext_wait_queue {		/* queue of sleeping tasks */
56 	struct task_struct *task;
57 	struct list_head list;
58 	struct msg_msg *msg;	/* ptr of loaded message */
59 	int state;		/* one of STATE_* values */
60 };
61 
62 struct mqueue_inode_info {
63 	spinlock_t lock;
64 	struct inode vfs_inode;
65 	wait_queue_head_t wait_q;
66 
67 	struct msg_msg **messages;
68 	struct mq_attr attr;
69 
70 	struct sigevent notify;
71 	pid_t notify_owner;
72 	struct user_struct *user;	/* user who created, for accounting */
73 	struct sock *notify_sock;
74 	struct sk_buff *notify_cookie;
75 
76 	/* for tasks waiting for free space and messages, respectively */
77 	struct ext_wait_queue e_wait_q[2];
78 
79 	unsigned long qsize; /* size of queue in memory (sum of all msgs) */
80 };
81 
82 static struct inode_operations mqueue_dir_inode_operations;
83 static struct file_operations mqueue_file_operations;
84 static struct super_operations mqueue_super_ops;
85 static void remove_notification(struct mqueue_inode_info *info);
86 
87 static spinlock_t mq_lock;
88 static kmem_cache_t *mqueue_inode_cachep;
89 static struct vfsmount *mqueue_mnt;
90 
91 static unsigned int queues_count;
92 static unsigned int queues_max 	= DFLT_QUEUESMAX;
93 static unsigned int msg_max 	= DFLT_MSGMAX;
94 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
95 
96 static struct ctl_table_header * mq_sysctl_table;
97 
98 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
99 {
100 	return container_of(inode, struct mqueue_inode_info, vfs_inode);
101 }
102 
103 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
104 							struct mq_attr *attr)
105 {
106 	struct inode *inode;
107 
108 	inode = new_inode(sb);
109 	if (inode) {
110 		inode->i_mode = mode;
111 		inode->i_uid = current->fsuid;
112 		inode->i_gid = current->fsgid;
113 		inode->i_blksize = PAGE_CACHE_SIZE;
114 		inode->i_blocks = 0;
115 		inode->i_mtime = inode->i_ctime = inode->i_atime =
116 				CURRENT_TIME;
117 
118 		if (S_ISREG(mode)) {
119 			struct mqueue_inode_info *info;
120 			struct task_struct *p = current;
121 			struct user_struct *u = p->user;
122 			unsigned long mq_bytes, mq_msg_tblsz;
123 
124 			inode->i_fop = &mqueue_file_operations;
125 			inode->i_size = FILENT_SIZE;
126 			/* mqueue specific info */
127 			info = MQUEUE_I(inode);
128 			spin_lock_init(&info->lock);
129 			init_waitqueue_head(&info->wait_q);
130 			INIT_LIST_HEAD(&info->e_wait_q[0].list);
131 			INIT_LIST_HEAD(&info->e_wait_q[1].list);
132 			info->messages = NULL;
133 			info->notify_owner = 0;
134 			info->qsize = 0;
135 			info->user = NULL;	/* set when all is ok */
136 			memset(&info->attr, 0, sizeof(info->attr));
137 			info->attr.mq_maxmsg = DFLT_MSGMAX;
138 			info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
139 			if (attr) {
140 				info->attr.mq_maxmsg = attr->mq_maxmsg;
141 				info->attr.mq_msgsize = attr->mq_msgsize;
142 			}
143 			mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
144 			mq_bytes = (mq_msg_tblsz +
145 				(info->attr.mq_maxmsg * info->attr.mq_msgsize));
146 
147 			spin_lock(&mq_lock);
148 			if (u->mq_bytes + mq_bytes < u->mq_bytes ||
149 		 	    u->mq_bytes + mq_bytes >
150 			    p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
151 				spin_unlock(&mq_lock);
152 				goto out_inode;
153 			}
154 			u->mq_bytes += mq_bytes;
155 			spin_unlock(&mq_lock);
156 
157 			info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
158 			if (!info->messages) {
159 				spin_lock(&mq_lock);
160 				u->mq_bytes -= mq_bytes;
161 				spin_unlock(&mq_lock);
162 				goto out_inode;
163 			}
164 			/* all is ok */
165 			info->user = get_uid(u);
166 		} else if (S_ISDIR(mode)) {
167 			inode->i_nlink++;
168 			/* Some things misbehave if size == 0 on a directory */
169 			inode->i_size = 2 * DIRENT_SIZE;
170 			inode->i_op = &mqueue_dir_inode_operations;
171 			inode->i_fop = &simple_dir_operations;
172 		}
173 	}
174 	return inode;
175 out_inode:
176 	make_bad_inode(inode);
177 	iput(inode);
178 	return NULL;
179 }
180 
181 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
182 {
183 	struct inode *inode;
184 
185 	sb->s_blocksize = PAGE_CACHE_SIZE;
186 	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
187 	sb->s_magic = MQUEUE_MAGIC;
188 	sb->s_op = &mqueue_super_ops;
189 
190 	inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
191 	if (!inode)
192 		return -ENOMEM;
193 
194 	sb->s_root = d_alloc_root(inode);
195 	if (!sb->s_root) {
196 		iput(inode);
197 		return -ENOMEM;
198 	}
199 
200 	return 0;
201 }
202 
203 static struct super_block *mqueue_get_sb(struct file_system_type *fs_type,
204 					 int flags, const char *dev_name,
205 					 void *data)
206 {
207 	return get_sb_single(fs_type, flags, data, mqueue_fill_super);
208 }
209 
210 static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags)
211 {
212 	struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
213 
214 	if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
215 		SLAB_CTOR_CONSTRUCTOR)
216 		inode_init_once(&p->vfs_inode);
217 }
218 
219 static struct inode *mqueue_alloc_inode(struct super_block *sb)
220 {
221 	struct mqueue_inode_info *ei;
222 
223 	ei = kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL);
224 	if (!ei)
225 		return NULL;
226 	return &ei->vfs_inode;
227 }
228 
229 static void mqueue_destroy_inode(struct inode *inode)
230 {
231 	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
232 }
233 
234 static void mqueue_delete_inode(struct inode *inode)
235 {
236 	struct mqueue_inode_info *info;
237 	struct user_struct *user;
238 	unsigned long mq_bytes;
239 	int i;
240 
241 	if (S_ISDIR(inode->i_mode)) {
242 		clear_inode(inode);
243 		return;
244 	}
245 	info = MQUEUE_I(inode);
246 	spin_lock(&info->lock);
247 	for (i = 0; i < info->attr.mq_curmsgs; i++)
248 		free_msg(info->messages[i]);
249 	kfree(info->messages);
250 	spin_unlock(&info->lock);
251 
252 	clear_inode(inode);
253 
254 	mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
255 		   (info->attr.mq_maxmsg * info->attr.mq_msgsize));
256 	user = info->user;
257 	if (user) {
258 		spin_lock(&mq_lock);
259 		user->mq_bytes -= mq_bytes;
260 		queues_count--;
261 		spin_unlock(&mq_lock);
262 		free_uid(user);
263 	}
264 }
265 
266 static int mqueue_create(struct inode *dir, struct dentry *dentry,
267 				int mode, struct nameidata *nd)
268 {
269 	struct inode *inode;
270 	struct mq_attr *attr = dentry->d_fsdata;
271 	int error;
272 
273 	spin_lock(&mq_lock);
274 	if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
275 		error = -ENOSPC;
276 		goto out_lock;
277 	}
278 	queues_count++;
279 	spin_unlock(&mq_lock);
280 
281 	inode = mqueue_get_inode(dir->i_sb, mode, attr);
282 	if (!inode) {
283 		error = -ENOMEM;
284 		spin_lock(&mq_lock);
285 		queues_count--;
286 		goto out_lock;
287 	}
288 
289 	dir->i_size += DIRENT_SIZE;
290 	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
291 
292 	d_instantiate(dentry, inode);
293 	dget(dentry);
294 	return 0;
295 out_lock:
296 	spin_unlock(&mq_lock);
297 	return error;
298 }
299 
300 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
301 {
302   	struct inode *inode = dentry->d_inode;
303 
304 	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
305 	dir->i_size -= DIRENT_SIZE;
306   	inode->i_nlink--;
307   	dput(dentry);
308   	return 0;
309 }
310 
311 /*
312 *	This is routine for system read from queue file.
313 *	To avoid mess with doing here some sort of mq_receive we allow
314 *	to read only queue size & notification info (the only values
315 *	that are interesting from user point of view and aren't accessible
316 *	through std routines)
317 */
318 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
319 				size_t count, loff_t * off)
320 {
321 	struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
322 	char buffer[FILENT_SIZE];
323 	size_t slen;
324 	loff_t o;
325 
326 	if (!count)
327 		return 0;
328 
329 	spin_lock(&info->lock);
330 	snprintf(buffer, sizeof(buffer),
331 			"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
332 			info->qsize,
333 			info->notify_owner ? info->notify.sigev_notify : 0,
334 			(info->notify_owner &&
335 			 info->notify.sigev_notify == SIGEV_SIGNAL) ?
336 				info->notify.sigev_signo : 0,
337 			info->notify_owner);
338 	spin_unlock(&info->lock);
339 	buffer[sizeof(buffer)-1] = '\0';
340 	slen = strlen(buffer)+1;
341 
342 	o = *off;
343 	if (o > slen)
344 		return 0;
345 
346 	if (o + count > slen)
347 		count = slen - o;
348 
349 	if (copy_to_user(u_data, buffer + o, count))
350 		return -EFAULT;
351 
352 	*off = o + count;
353 	filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME;
354 	return count;
355 }
356 
357 static int mqueue_flush_file(struct file *filp)
358 {
359 	struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
360 
361 	spin_lock(&info->lock);
362 	if (current->tgid == info->notify_owner)
363 		remove_notification(info);
364 
365 	spin_unlock(&info->lock);
366 	return 0;
367 }
368 
369 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
370 {
371 	struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
372 	int retval = 0;
373 
374 	poll_wait(filp, &info->wait_q, poll_tab);
375 
376 	spin_lock(&info->lock);
377 	if (info->attr.mq_curmsgs)
378 		retval = POLLIN | POLLRDNORM;
379 
380 	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
381 		retval |= POLLOUT | POLLWRNORM;
382 	spin_unlock(&info->lock);
383 
384 	return retval;
385 }
386 
387 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
388 static void wq_add(struct mqueue_inode_info *info, int sr,
389 			struct ext_wait_queue *ewp)
390 {
391 	struct ext_wait_queue *walk;
392 
393 	ewp->task = current;
394 
395 	list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
396 		if (walk->task->static_prio <= current->static_prio) {
397 			list_add_tail(&ewp->list, &walk->list);
398 			return;
399 		}
400 	}
401 	list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
402 }
403 
404 /*
405  * Puts current task to sleep. Caller must hold queue lock. After return
406  * lock isn't held.
407  * sr: SEND or RECV
408  */
409 static int wq_sleep(struct mqueue_inode_info *info, int sr,
410 			long timeout, struct ext_wait_queue *ewp)
411 {
412 	int retval;
413 	signed long time;
414 
415 	wq_add(info, sr, ewp);
416 
417 	for (;;) {
418 		set_current_state(TASK_INTERRUPTIBLE);
419 
420 		spin_unlock(&info->lock);
421 		time = schedule_timeout(timeout);
422 
423 		while (ewp->state == STATE_PENDING)
424 			cpu_relax();
425 
426 		if (ewp->state == STATE_READY) {
427 			retval = 0;
428 			goto out;
429 		}
430 		spin_lock(&info->lock);
431 		if (ewp->state == STATE_READY) {
432 			retval = 0;
433 			goto out_unlock;
434 		}
435 		if (signal_pending(current)) {
436 			retval = -ERESTARTSYS;
437 			break;
438 		}
439 		if (time == 0) {
440 			retval = -ETIMEDOUT;
441 			break;
442 		}
443 	}
444 	list_del(&ewp->list);
445 out_unlock:
446 	spin_unlock(&info->lock);
447 out:
448 	return retval;
449 }
450 
451 /*
452  * Returns waiting task that should be serviced first or NULL if none exists
453  */
454 static struct ext_wait_queue *wq_get_first_waiter(
455 		struct mqueue_inode_info *info, int sr)
456 {
457 	struct list_head *ptr;
458 
459 	ptr = info->e_wait_q[sr].list.prev;
460 	if (ptr == &info->e_wait_q[sr].list)
461 		return NULL;
462 	return list_entry(ptr, struct ext_wait_queue, list);
463 }
464 
465 /* Auxiliary functions to manipulate messages' list */
466 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
467 {
468 	int k;
469 
470 	k = info->attr.mq_curmsgs - 1;
471 	while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
472 		info->messages[k + 1] = info->messages[k];
473 		k--;
474 	}
475 	info->attr.mq_curmsgs++;
476 	info->qsize += ptr->m_ts;
477 	info->messages[k + 1] = ptr;
478 }
479 
480 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
481 {
482 	info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
483 	return info->messages[info->attr.mq_curmsgs];
484 }
485 
486 static inline void set_cookie(struct sk_buff *skb, char code)
487 {
488 	((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
489 }
490 
491 /*
492  * The next function is only to split too long sys_mq_timedsend
493  */
494 static void __do_notify(struct mqueue_inode_info *info)
495 {
496 	/* notification
497 	 * invoked when there is registered process and there isn't process
498 	 * waiting synchronously for message AND state of queue changed from
499 	 * empty to not empty. Here we are sure that no one is waiting
500 	 * synchronously. */
501 	if (info->notify_owner &&
502 	    info->attr.mq_curmsgs == 1) {
503 		struct siginfo sig_i;
504 		switch (info->notify.sigev_notify) {
505 		case SIGEV_NONE:
506 			break;
507 		case SIGEV_SIGNAL:
508 			/* sends signal */
509 
510 			sig_i.si_signo = info->notify.sigev_signo;
511 			sig_i.si_errno = 0;
512 			sig_i.si_code = SI_MESGQ;
513 			sig_i.si_value = info->notify.sigev_value;
514 			sig_i.si_pid = current->tgid;
515 			sig_i.si_uid = current->uid;
516 
517 			kill_proc_info(info->notify.sigev_signo,
518 				       &sig_i, info->notify_owner);
519 			break;
520 		case SIGEV_THREAD:
521 			set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
522 			netlink_sendskb(info->notify_sock,
523 					info->notify_cookie, 0);
524 			break;
525 		}
526 		/* after notification unregisters process */
527 		info->notify_owner = 0;
528 	}
529 	wake_up(&info->wait_q);
530 }
531 
532 static long prepare_timeout(const struct timespec __user *u_arg)
533 {
534 	struct timespec ts, nowts;
535 	long timeout;
536 
537 	if (u_arg) {
538 		if (unlikely(copy_from_user(&ts, u_arg,
539 					sizeof(struct timespec))))
540 			return -EFAULT;
541 
542 		if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
543 			|| ts.tv_nsec >= NSEC_PER_SEC))
544 			return -EINVAL;
545 		nowts = CURRENT_TIME;
546 		/* first subtract as jiffies can't be too big */
547 		ts.tv_sec -= nowts.tv_sec;
548 		if (ts.tv_nsec < nowts.tv_nsec) {
549 			ts.tv_nsec += NSEC_PER_SEC;
550 			ts.tv_sec--;
551 		}
552 		ts.tv_nsec -= nowts.tv_nsec;
553 		if (ts.tv_sec < 0)
554 			return 0;
555 
556 		timeout = timespec_to_jiffies(&ts) + 1;
557 	} else
558 		return MAX_SCHEDULE_TIMEOUT;
559 
560 	return timeout;
561 }
562 
563 static void remove_notification(struct mqueue_inode_info *info)
564 {
565 	if (info->notify_owner != 0 &&
566 	    info->notify.sigev_notify == SIGEV_THREAD) {
567 		set_cookie(info->notify_cookie, NOTIFY_REMOVED);
568 		netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
569 	}
570 	info->notify_owner = 0;
571 }
572 
573 static int mq_attr_ok(struct mq_attr *attr)
574 {
575 	if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
576 		return 0;
577 	if (capable(CAP_SYS_RESOURCE)) {
578 		if (attr->mq_maxmsg > HARD_MSGMAX)
579 			return 0;
580 	} else {
581 		if (attr->mq_maxmsg > msg_max ||
582 				attr->mq_msgsize > msgsize_max)
583 			return 0;
584 	}
585 	/* check for overflow */
586 	if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
587 		return 0;
588 	if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
589 	    (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
590 	    (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
591 		return 0;
592 	return 1;
593 }
594 
595 /*
596  * Invoked when creating a new queue via sys_mq_open
597  */
598 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
599 			int oflag, mode_t mode, struct mq_attr __user *u_attr)
600 {
601 	struct file *filp;
602 	struct mq_attr attr;
603 	int ret;
604 
605 	if (u_attr != NULL) {
606 		if (copy_from_user(&attr, u_attr, sizeof(attr)))
607 			return ERR_PTR(-EFAULT);
608 		if (!mq_attr_ok(&attr))
609 			return ERR_PTR(-EINVAL);
610 		/* store for use during create */
611 		dentry->d_fsdata = &attr;
612 	}
613 
614 	mode &= ~current->fs->umask;
615 	ret = vfs_create(dir->d_inode, dentry, mode, NULL);
616 	dentry->d_fsdata = NULL;
617 	if (ret)
618 		return ERR_PTR(ret);
619 
620 	filp = dentry_open(dentry, mqueue_mnt, oflag);
621 	if (!IS_ERR(filp))
622 		dget(dentry);
623 
624 	return filp;
625 }
626 
627 /* Opens existing queue */
628 static struct file *do_open(struct dentry *dentry, int oflag)
629 {
630 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
631 					MAY_READ | MAY_WRITE };
632 	struct file *filp;
633 
634 	if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
635 		return ERR_PTR(-EINVAL);
636 
637 	if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL))
638 		return ERR_PTR(-EACCES);
639 
640 	filp = dentry_open(dentry, mqueue_mnt, oflag);
641 
642 	if (!IS_ERR(filp))
643 		dget(dentry);
644 
645 	return filp;
646 }
647 
648 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
649 				struct mq_attr __user *u_attr)
650 {
651 	struct dentry *dentry;
652 	struct file *filp;
653 	char *name;
654 	int fd, error;
655 
656 	if (IS_ERR(name = getname(u_name)))
657 		return PTR_ERR(name);
658 
659 	fd = get_unused_fd();
660 	if (fd < 0)
661 		goto out_putname;
662 
663 	down(&mqueue_mnt->mnt_root->d_inode->i_sem);
664 	dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
665 	if (IS_ERR(dentry)) {
666 		error = PTR_ERR(dentry);
667 		goto out_err;
668 	}
669 	mntget(mqueue_mnt);
670 
671 	if (oflag & O_CREAT) {
672 		if (dentry->d_inode) {	/* entry already exists */
673 			filp = (oflag & O_EXCL) ? ERR_PTR(-EEXIST) :
674 					do_open(dentry, oflag);
675 		} else {
676 			filp = do_create(mqueue_mnt->mnt_root, dentry,
677 						oflag, mode, u_attr);
678 		}
679 	} else
680 		filp = (dentry->d_inode) ? do_open(dentry, oflag) :
681 					ERR_PTR(-ENOENT);
682 
683 	dput(dentry);
684 
685 	if (IS_ERR(filp)) {
686 		error = PTR_ERR(filp);
687 		goto out_putfd;
688 	}
689 
690 	set_close_on_exec(fd, 1);
691 	fd_install(fd, filp);
692 	goto out_upsem;
693 
694 out_putfd:
695 	mntput(mqueue_mnt);
696 	put_unused_fd(fd);
697 out_err:
698 	fd = error;
699 out_upsem:
700 	up(&mqueue_mnt->mnt_root->d_inode->i_sem);
701 out_putname:
702 	putname(name);
703 	return fd;
704 }
705 
706 asmlinkage long sys_mq_unlink(const char __user *u_name)
707 {
708 	int err;
709 	char *name;
710 	struct dentry *dentry;
711 	struct inode *inode = NULL;
712 
713 	name = getname(u_name);
714 	if (IS_ERR(name))
715 		return PTR_ERR(name);
716 
717 	down(&mqueue_mnt->mnt_root->d_inode->i_sem);
718 	dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
719 	if (IS_ERR(dentry)) {
720 		err = PTR_ERR(dentry);
721 		goto out_unlock;
722 	}
723 
724 	if (!dentry->d_inode) {
725 		err = -ENOENT;
726 		goto out_err;
727 	}
728 
729 	inode = dentry->d_inode;
730 	if (inode)
731 		atomic_inc(&inode->i_count);
732 
733 	err = vfs_unlink(dentry->d_parent->d_inode, dentry);
734 out_err:
735 	dput(dentry);
736 
737 out_unlock:
738 	up(&mqueue_mnt->mnt_root->d_inode->i_sem);
739 	putname(name);
740 	if (inode)
741 		iput(inode);
742 
743 	return err;
744 }
745 
746 /* Pipelined send and receive functions.
747  *
748  * If a receiver finds no waiting message, then it registers itself in the
749  * list of waiting receivers. A sender checks that list before adding the new
750  * message into the message array. If there is a waiting receiver, then it
751  * bypasses the message array and directly hands the message over to the
752  * receiver.
753  * The receiver accepts the message and returns without grabbing the queue
754  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
755  * are necessary. The same algorithm is used for sysv semaphores, see
756  * ipc/sem.c fore more details.
757  *
758  * The same algorithm is used for senders.
759  */
760 
761 /* pipelined_send() - send a message directly to the task waiting in
762  * sys_mq_timedreceive() (without inserting message into a queue).
763  */
764 static inline void pipelined_send(struct mqueue_inode_info *info,
765 				  struct msg_msg *message,
766 				  struct ext_wait_queue *receiver)
767 {
768 	receiver->msg = message;
769 	list_del(&receiver->list);
770 	receiver->state = STATE_PENDING;
771 	wake_up_process(receiver->task);
772 	smp_wmb();
773 	receiver->state = STATE_READY;
774 }
775 
776 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
777  * gets its message and put to the queue (we have one free place for sure). */
778 static inline void pipelined_receive(struct mqueue_inode_info *info)
779 {
780 	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
781 
782 	if (!sender) {
783 		/* for poll */
784 		wake_up_interruptible(&info->wait_q);
785 		return;
786 	}
787 	msg_insert(sender->msg, info);
788 	list_del(&sender->list);
789 	sender->state = STATE_PENDING;
790 	wake_up_process(sender->task);
791 	smp_wmb();
792 	sender->state = STATE_READY;
793 }
794 
795 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
796 	size_t msg_len, unsigned int msg_prio,
797 	const struct timespec __user *u_abs_timeout)
798 {
799 	struct file *filp;
800 	struct inode *inode;
801 	struct ext_wait_queue wait;
802 	struct ext_wait_queue *receiver;
803 	struct msg_msg *msg_ptr;
804 	struct mqueue_inode_info *info;
805 	long timeout;
806 	int ret;
807 
808 	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
809 		return -EINVAL;
810 
811 	timeout = prepare_timeout(u_abs_timeout);
812 
813 	ret = -EBADF;
814 	filp = fget(mqdes);
815 	if (unlikely(!filp))
816 		goto out;
817 
818 	inode = filp->f_dentry->d_inode;
819 	if (unlikely(filp->f_op != &mqueue_file_operations))
820 		goto out_fput;
821 	info = MQUEUE_I(inode);
822 
823 	if (unlikely(!(filp->f_mode & FMODE_WRITE)))
824 		goto out_fput;
825 
826 	if (unlikely(msg_len > info->attr.mq_msgsize)) {
827 		ret = -EMSGSIZE;
828 		goto out_fput;
829 	}
830 
831 	/* First try to allocate memory, before doing anything with
832 	 * existing queues. */
833 	msg_ptr = load_msg(u_msg_ptr, msg_len);
834 	if (IS_ERR(msg_ptr)) {
835 		ret = PTR_ERR(msg_ptr);
836 		goto out_fput;
837 	}
838 	msg_ptr->m_ts = msg_len;
839 	msg_ptr->m_type = msg_prio;
840 
841 	spin_lock(&info->lock);
842 
843 	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
844 		if (filp->f_flags & O_NONBLOCK) {
845 			spin_unlock(&info->lock);
846 			ret = -EAGAIN;
847 		} else if (unlikely(timeout < 0)) {
848 			spin_unlock(&info->lock);
849 			ret = timeout;
850 		} else {
851 			wait.task = current;
852 			wait.msg = (void *) msg_ptr;
853 			wait.state = STATE_NONE;
854 			ret = wq_sleep(info, SEND, timeout, &wait);
855 		}
856 		if (ret < 0)
857 			free_msg(msg_ptr);
858 	} else {
859 		receiver = wq_get_first_waiter(info, RECV);
860 		if (receiver) {
861 			pipelined_send(info, msg_ptr, receiver);
862 		} else {
863 			/* adds message to the queue */
864 			msg_insert(msg_ptr, info);
865 			__do_notify(info);
866 		}
867 		inode->i_atime = inode->i_mtime = inode->i_ctime =
868 				CURRENT_TIME;
869 		spin_unlock(&info->lock);
870 		ret = 0;
871 	}
872 out_fput:
873 	fput(filp);
874 out:
875 	return ret;
876 }
877 
878 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
879 	size_t msg_len, unsigned int __user *u_msg_prio,
880 	const struct timespec __user *u_abs_timeout)
881 {
882 	long timeout;
883 	ssize_t ret;
884 	struct msg_msg *msg_ptr;
885 	struct file *filp;
886 	struct inode *inode;
887 	struct mqueue_inode_info *info;
888 	struct ext_wait_queue wait;
889 
890 	timeout = prepare_timeout(u_abs_timeout);
891 
892 	ret = -EBADF;
893 	filp = fget(mqdes);
894 	if (unlikely(!filp))
895 		goto out;
896 
897 	inode = filp->f_dentry->d_inode;
898 	if (unlikely(filp->f_op != &mqueue_file_operations))
899 		goto out_fput;
900 	info = MQUEUE_I(inode);
901 
902 	if (unlikely(!(filp->f_mode & FMODE_READ)))
903 		goto out_fput;
904 
905 	/* checks if buffer is big enough */
906 	if (unlikely(msg_len < info->attr.mq_msgsize)) {
907 		ret = -EMSGSIZE;
908 		goto out_fput;
909 	}
910 
911 	spin_lock(&info->lock);
912 	if (info->attr.mq_curmsgs == 0) {
913 		if (filp->f_flags & O_NONBLOCK) {
914 			spin_unlock(&info->lock);
915 			ret = -EAGAIN;
916 			msg_ptr = NULL;
917 		} else if (unlikely(timeout < 0)) {
918 			spin_unlock(&info->lock);
919 			ret = timeout;
920 			msg_ptr = NULL;
921 		} else {
922 			wait.task = current;
923 			wait.state = STATE_NONE;
924 			ret = wq_sleep(info, RECV, timeout, &wait);
925 			msg_ptr = wait.msg;
926 		}
927 	} else {
928 		msg_ptr = msg_get(info);
929 
930 		inode->i_atime = inode->i_mtime = inode->i_ctime =
931 				CURRENT_TIME;
932 
933 		/* There is now free space in queue. */
934 		pipelined_receive(info);
935 		spin_unlock(&info->lock);
936 		ret = 0;
937 	}
938 	if (ret == 0) {
939 		ret = msg_ptr->m_ts;
940 
941 		if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
942 			store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
943 			ret = -EFAULT;
944 		}
945 		free_msg(msg_ptr);
946 	}
947 out_fput:
948 	fput(filp);
949 out:
950 	return ret;
951 }
952 
953 /*
954  * Notes: the case when user wants us to deregister (with NULL as pointer)
955  * and he isn't currently owner of notification, will be silently discarded.
956  * It isn't explicitly defined in the POSIX.
957  */
958 asmlinkage long sys_mq_notify(mqd_t mqdes,
959 				const struct sigevent __user *u_notification)
960 {
961 	int ret;
962 	struct file *filp;
963 	struct sock *sock;
964 	struct inode *inode;
965 	struct sigevent notification;
966 	struct mqueue_inode_info *info;
967 	struct sk_buff *nc;
968 
969 	nc = NULL;
970 	sock = NULL;
971 	if (u_notification != NULL) {
972 		if (copy_from_user(&notification, u_notification,
973 					sizeof(struct sigevent)))
974 			return -EFAULT;
975 
976 		if (unlikely(notification.sigev_notify != SIGEV_NONE &&
977 			     notification.sigev_notify != SIGEV_SIGNAL &&
978 			     notification.sigev_notify != SIGEV_THREAD))
979 			return -EINVAL;
980 		if (notification.sigev_notify == SIGEV_SIGNAL &&
981 			!valid_signal(notification.sigev_signo)) {
982 			return -EINVAL;
983 		}
984 		if (notification.sigev_notify == SIGEV_THREAD) {
985 			/* create the notify skb */
986 			nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
987 			ret = -ENOMEM;
988 			if (!nc)
989 				goto out;
990 			ret = -EFAULT;
991 			if (copy_from_user(nc->data,
992 					notification.sigev_value.sival_ptr,
993 					NOTIFY_COOKIE_LEN)) {
994 				goto out;
995 			}
996 
997 			/* TODO: add a header? */
998 			skb_put(nc, NOTIFY_COOKIE_LEN);
999 			/* and attach it to the socket */
1000 retry:
1001 			filp = fget(notification.sigev_signo);
1002 			ret = -EBADF;
1003 			if (!filp)
1004 				goto out;
1005 			sock = netlink_getsockbyfilp(filp);
1006 			fput(filp);
1007 			if (IS_ERR(sock)) {
1008 				ret = PTR_ERR(sock);
1009 				sock = NULL;
1010 				goto out;
1011 			}
1012 
1013 			ret = netlink_attachskb(sock, nc, 0, MAX_SCHEDULE_TIMEOUT);
1014 			if (ret == 1)
1015 		       		goto retry;
1016 			if (ret) {
1017 				sock = NULL;
1018 				nc = NULL;
1019 				goto out;
1020 			}
1021 		}
1022 	}
1023 
1024 	ret = -EBADF;
1025 	filp = fget(mqdes);
1026 	if (!filp)
1027 		goto out;
1028 
1029 	inode = filp->f_dentry->d_inode;
1030 	if (unlikely(filp->f_op != &mqueue_file_operations))
1031 		goto out_fput;
1032 	info = MQUEUE_I(inode);
1033 
1034 	ret = 0;
1035 	spin_lock(&info->lock);
1036 	if (u_notification == NULL) {
1037 		if (info->notify_owner == current->tgid) {
1038 			remove_notification(info);
1039 			inode->i_atime = inode->i_ctime = CURRENT_TIME;
1040 		}
1041 	} else if (info->notify_owner != 0) {
1042 		ret = -EBUSY;
1043 	} else {
1044 		switch (notification.sigev_notify) {
1045 		case SIGEV_NONE:
1046 			info->notify.sigev_notify = SIGEV_NONE;
1047 			break;
1048 		case SIGEV_THREAD:
1049 			info->notify_sock = sock;
1050 			info->notify_cookie = nc;
1051 			sock = NULL;
1052 			nc = NULL;
1053 			info->notify.sigev_notify = SIGEV_THREAD;
1054 			break;
1055 		case SIGEV_SIGNAL:
1056 			info->notify.sigev_signo = notification.sigev_signo;
1057 			info->notify.sigev_value = notification.sigev_value;
1058 			info->notify.sigev_notify = SIGEV_SIGNAL;
1059 			break;
1060 		}
1061 		info->notify_owner = current->tgid;
1062 		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1063 	}
1064 	spin_unlock(&info->lock);
1065 out_fput:
1066 	fput(filp);
1067 out:
1068 	if (sock) {
1069 		netlink_detachskb(sock, nc);
1070 	} else if (nc) {
1071 		dev_kfree_skb(nc);
1072 	}
1073 	return ret;
1074 }
1075 
1076 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1077 			const struct mq_attr __user *u_mqstat,
1078 			struct mq_attr __user *u_omqstat)
1079 {
1080 	int ret;
1081 	struct mq_attr mqstat, omqstat;
1082 	struct file *filp;
1083 	struct inode *inode;
1084 	struct mqueue_inode_info *info;
1085 
1086 	if (u_mqstat != NULL) {
1087 		if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1088 			return -EFAULT;
1089 		if (mqstat.mq_flags & (~O_NONBLOCK))
1090 			return -EINVAL;
1091 	}
1092 
1093 	ret = -EBADF;
1094 	filp = fget(mqdes);
1095 	if (!filp)
1096 		goto out;
1097 
1098 	inode = filp->f_dentry->d_inode;
1099 	if (unlikely(filp->f_op != &mqueue_file_operations))
1100 		goto out_fput;
1101 	info = MQUEUE_I(inode);
1102 
1103 	spin_lock(&info->lock);
1104 
1105 	omqstat = info->attr;
1106 	omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1107 	if (u_mqstat) {
1108 		if (mqstat.mq_flags & O_NONBLOCK)
1109 			filp->f_flags |= O_NONBLOCK;
1110 		else
1111 			filp->f_flags &= ~O_NONBLOCK;
1112 
1113 		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1114 	}
1115 
1116 	spin_unlock(&info->lock);
1117 
1118 	ret = 0;
1119 	if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1120 						sizeof(struct mq_attr)))
1121 		ret = -EFAULT;
1122 
1123 out_fput:
1124 	fput(filp);
1125 out:
1126 	return ret;
1127 }
1128 
1129 static struct inode_operations mqueue_dir_inode_operations = {
1130 	.lookup = simple_lookup,
1131 	.create = mqueue_create,
1132 	.unlink = mqueue_unlink,
1133 };
1134 
1135 static struct file_operations mqueue_file_operations = {
1136 	.flush = mqueue_flush_file,
1137 	.poll = mqueue_poll_file,
1138 	.read = mqueue_read_file,
1139 };
1140 
1141 static struct super_operations mqueue_super_ops = {
1142 	.alloc_inode = mqueue_alloc_inode,
1143 	.destroy_inode = mqueue_destroy_inode,
1144 	.statfs = simple_statfs,
1145 	.delete_inode = mqueue_delete_inode,
1146 	.drop_inode = generic_delete_inode,
1147 };
1148 
1149 static struct file_system_type mqueue_fs_type = {
1150 	.name = "mqueue",
1151 	.get_sb = mqueue_get_sb,
1152 	.kill_sb = kill_litter_super,
1153 };
1154 
1155 static int msg_max_limit_min = DFLT_MSGMAX;
1156 static int msg_max_limit_max = HARD_MSGMAX;
1157 
1158 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1159 static int msg_maxsize_limit_max = INT_MAX;
1160 
1161 static ctl_table mq_sysctls[] = {
1162 	{
1163 		.ctl_name	= CTL_QUEUESMAX,
1164 		.procname	= "queues_max",
1165 		.data		= &queues_max,
1166 		.maxlen		= sizeof(int),
1167 		.mode		= 0644,
1168 		.proc_handler	= &proc_dointvec,
1169 	},
1170 	{
1171 		.ctl_name	= CTL_MSGMAX,
1172 		.procname	= "msg_max",
1173 		.data		= &msg_max,
1174 		.maxlen		= sizeof(int),
1175 		.mode		= 0644,
1176 		.proc_handler	= &proc_dointvec_minmax,
1177 		.extra1		= &msg_max_limit_min,
1178 		.extra2		= &msg_max_limit_max,
1179 	},
1180 	{
1181 		.ctl_name	= CTL_MSGSIZEMAX,
1182 		.procname	= "msgsize_max",
1183 		.data		= &msgsize_max,
1184 		.maxlen		= sizeof(int),
1185 		.mode		= 0644,
1186 		.proc_handler	= &proc_dointvec_minmax,
1187 		.extra1		= &msg_maxsize_limit_min,
1188 		.extra2		= &msg_maxsize_limit_max,
1189 	},
1190 	{ .ctl_name = 0 }
1191 };
1192 
1193 static ctl_table mq_sysctl_dir[] = {
1194 	{
1195 		.ctl_name	= FS_MQUEUE,
1196 		.procname	= "mqueue",
1197 		.mode		= 0555,
1198 		.child		= mq_sysctls,
1199 	},
1200 	{ .ctl_name = 0 }
1201 };
1202 
1203 static ctl_table mq_sysctl_root[] = {
1204 	{
1205 		.ctl_name	= CTL_FS,
1206 		.procname	= "fs",
1207 		.mode		= 0555,
1208 		.child		= mq_sysctl_dir,
1209 	},
1210 	{ .ctl_name = 0 }
1211 };
1212 
1213 static int __init init_mqueue_fs(void)
1214 {
1215 	int error;
1216 
1217 	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1218 				sizeof(struct mqueue_inode_info), 0,
1219 				SLAB_HWCACHE_ALIGN, init_once, NULL);
1220 	if (mqueue_inode_cachep == NULL)
1221 		return -ENOMEM;
1222 
1223 	/* ignore failues - they are not fatal */
1224 	mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0);
1225 
1226 	error = register_filesystem(&mqueue_fs_type);
1227 	if (error)
1228 		goto out_sysctl;
1229 
1230 	if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1231 		error = PTR_ERR(mqueue_mnt);
1232 		goto out_filesystem;
1233 	}
1234 
1235 	/* internal initialization - not common for vfs */
1236 	queues_count = 0;
1237 	spin_lock_init(&mq_lock);
1238 
1239 	return 0;
1240 
1241 out_filesystem:
1242 	unregister_filesystem(&mqueue_fs_type);
1243 out_sysctl:
1244 	if (mq_sysctl_table)
1245 		unregister_sysctl_table(mq_sysctl_table);
1246 	if (kmem_cache_destroy(mqueue_inode_cachep)) {
1247 		printk(KERN_INFO
1248 			"mqueue_inode_cache: not all structures were freed\n");
1249 	}
1250 	return error;
1251 }
1252 
1253 __initcall(init_mqueue_fs);
1254