mqueue.c revision 6f9ac6d9
1/*
2 * POSIX message queues filesystem for Linux.
3 *
4 * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
5 *                          Michal Wronski          (michal.wronski@gmail.com)
6 *
7 * Spinlocks:               Mohamed Abbas           (abbas.mohamed@intel.com)
8 * Lockless receive & send, fd based notify:
9 * 			    Manfred Spraul	    (manfred@colorfullife.com)
10 *
11 * Audit:                   George Wilson           (ltcgcw@us.ibm.com)
12 *
13 * This file is released under the GPL.
14 */
15
16#include <linux/capability.h>
17#include <linux/init.h>
18#include <linux/pagemap.h>
19#include <linux/file.h>
20#include <linux/mount.h>
21#include <linux/namei.h>
22#include <linux/sysctl.h>
23#include <linux/poll.h>
24#include <linux/mqueue.h>
25#include <linux/msg.h>
26#include <linux/skbuff.h>
27#include <linux/netlink.h>
28#include <linux/syscalls.h>
29#include <linux/audit.h>
30#include <linux/signal.h>
31#include <linux/mutex.h>
32#include <linux/nsproxy.h>
33#include <linux/pid.h>
34#include <linux/ipc_namespace.h>
35#include <linux/user_namespace.h>
36#include <linux/slab.h>
37
38#include <net/sock.h>
39#include "util.h"
40
41#define MQUEUE_MAGIC	0x19800202
42#define DIRENT_SIZE	20
43#define FILENT_SIZE	80
44
45#define SEND		0
46#define RECV		1
47
48#define STATE_NONE	0
49#define STATE_PENDING	1
50#define STATE_READY	2
51
52struct ext_wait_queue {		/* queue of sleeping tasks */
53	struct task_struct *task;
54	struct list_head list;
55	struct msg_msg *msg;	/* ptr of loaded message */
56	int state;		/* one of STATE_* values */
57};
58
59struct mqueue_inode_info {
60	spinlock_t lock;
61	struct inode vfs_inode;
62	wait_queue_head_t wait_q;
63
64	struct msg_msg **messages;
65	struct mq_attr attr;
66
67	struct sigevent notify;
68	struct pid* notify_owner;
69	struct user_namespace *notify_user_ns;
70	struct user_struct *user;	/* user who created, for accounting */
71	struct sock *notify_sock;
72	struct sk_buff *notify_cookie;
73
74	/* for tasks waiting for free space and messages, respectively */
75	struct ext_wait_queue e_wait_q[2];
76
77	unsigned long qsize; /* size of queue in memory (sum of all msgs) */
78};
79
80static const struct inode_operations mqueue_dir_inode_operations;
81static const struct file_operations mqueue_file_operations;
82static const struct super_operations mqueue_super_ops;
83static void remove_notification(struct mqueue_inode_info *info);
84
85static struct kmem_cache *mqueue_inode_cachep;
86
87static struct ctl_table_header * mq_sysctl_table;
88
89static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
90{
91	return container_of(inode, struct mqueue_inode_info, vfs_inode);
92}
93
94/*
95 * This routine should be called with the mq_lock held.
96 */
97static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
98{
99	return get_ipc_ns(inode->i_sb->s_fs_info);
100}
101
102static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
103{
104	struct ipc_namespace *ns;
105
106	spin_lock(&mq_lock);
107	ns = __get_ns_from_inode(inode);
108	spin_unlock(&mq_lock);
109	return ns;
110}
111
112static struct inode *mqueue_get_inode(struct super_block *sb,
113		struct ipc_namespace *ipc_ns, umode_t mode,
114		struct mq_attr *attr)
115{
116	struct user_struct *u = current_user();
117	struct inode *inode;
118	int ret = -ENOMEM;
119
120	inode = new_inode(sb);
121	if (!inode)
122		goto err;
123
124	inode->i_ino = get_next_ino();
125	inode->i_mode = mode;
126	inode->i_uid = current_fsuid();
127	inode->i_gid = current_fsgid();
128	inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
129
130	if (S_ISREG(mode)) {
131		struct mqueue_inode_info *info;
132		unsigned long mq_bytes, mq_msg_tblsz;
133
134		inode->i_fop = &mqueue_file_operations;
135		inode->i_size = FILENT_SIZE;
136		/* mqueue specific info */
137		info = MQUEUE_I(inode);
138		spin_lock_init(&info->lock);
139		init_waitqueue_head(&info->wait_q);
140		INIT_LIST_HEAD(&info->e_wait_q[0].list);
141		INIT_LIST_HEAD(&info->e_wait_q[1].list);
142		info->notify_owner = NULL;
143		info->notify_user_ns = NULL;
144		info->qsize = 0;
145		info->user = NULL;	/* set when all is ok */
146		memset(&info->attr, 0, sizeof(info->attr));
147		info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
148		info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
149		if (attr) {
150			info->attr.mq_maxmsg = attr->mq_maxmsg;
151			info->attr.mq_msgsize = attr->mq_msgsize;
152		}
153		mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
154		info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
155		if (!info->messages)
156			goto out_inode;
157
158		mq_bytes = (mq_msg_tblsz +
159			(info->attr.mq_maxmsg * info->attr.mq_msgsize));
160
161		spin_lock(&mq_lock);
162		if (u->mq_bytes + mq_bytes < u->mq_bytes ||
163		    u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
164			spin_unlock(&mq_lock);
165			/* mqueue_evict_inode() releases info->messages */
166			ret = -EMFILE;
167			goto out_inode;
168		}
169		u->mq_bytes += mq_bytes;
170		spin_unlock(&mq_lock);
171
172		/* all is ok */
173		info->user = get_uid(u);
174	} else if (S_ISDIR(mode)) {
175		inc_nlink(inode);
176		/* Some things misbehave if size == 0 on a directory */
177		inode->i_size = 2 * DIRENT_SIZE;
178		inode->i_op = &mqueue_dir_inode_operations;
179		inode->i_fop = &simple_dir_operations;
180	}
181
182	return inode;
183out_inode:
184	iput(inode);
185err:
186	return ERR_PTR(ret);
187}
188
189static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
190{
191	struct inode *inode;
192	struct ipc_namespace *ns = data;
193
194	sb->s_blocksize = PAGE_CACHE_SIZE;
195	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
196	sb->s_magic = MQUEUE_MAGIC;
197	sb->s_op = &mqueue_super_ops;
198
199	inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
200	if (IS_ERR(inode))
201		return PTR_ERR(inode);
202
203	sb->s_root = d_make_root(inode);
204	if (!sb->s_root)
205		return -ENOMEM;
206	return 0;
207}
208
209static struct dentry *mqueue_mount(struct file_system_type *fs_type,
210			 int flags, const char *dev_name,
211			 void *data)
212{
213	if (!(flags & MS_KERNMOUNT))
214		data = current->nsproxy->ipc_ns;
215	return mount_ns(fs_type, flags, data, mqueue_fill_super);
216}
217
218static void init_once(void *foo)
219{
220	struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
221
222	inode_init_once(&p->vfs_inode);
223}
224
225static struct inode *mqueue_alloc_inode(struct super_block *sb)
226{
227	struct mqueue_inode_info *ei;
228
229	ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
230	if (!ei)
231		return NULL;
232	return &ei->vfs_inode;
233}
234
235static void mqueue_i_callback(struct rcu_head *head)
236{
237	struct inode *inode = container_of(head, struct inode, i_rcu);
238	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
239}
240
241static void mqueue_destroy_inode(struct inode *inode)
242{
243	call_rcu(&inode->i_rcu, mqueue_i_callback);
244}
245
246static void mqueue_evict_inode(struct inode *inode)
247{
248	struct mqueue_inode_info *info;
249	struct user_struct *user;
250	unsigned long mq_bytes;
251	int i;
252	struct ipc_namespace *ipc_ns;
253
254	end_writeback(inode);
255
256	if (S_ISDIR(inode->i_mode))
257		return;
258
259	ipc_ns = get_ns_from_inode(inode);
260	info = MQUEUE_I(inode);
261	spin_lock(&info->lock);
262	for (i = 0; i < info->attr.mq_curmsgs; i++)
263		free_msg(info->messages[i]);
264	kfree(info->messages);
265	spin_unlock(&info->lock);
266
267	/* Total amount of bytes accounted for the mqueue */
268	mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
269	    + info->attr.mq_msgsize);
270	user = info->user;
271	if (user) {
272		spin_lock(&mq_lock);
273		user->mq_bytes -= mq_bytes;
274		/*
275		 * get_ns_from_inode() ensures that the
276		 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
277		 * to which we now hold a reference, or it is NULL.
278		 * We can't put it here under mq_lock, though.
279		 */
280		if (ipc_ns)
281			ipc_ns->mq_queues_count--;
282		spin_unlock(&mq_lock);
283		free_uid(user);
284	}
285	if (ipc_ns)
286		put_ipc_ns(ipc_ns);
287}
288
289static int mqueue_create(struct inode *dir, struct dentry *dentry,
290				umode_t mode, struct nameidata *nd)
291{
292	struct inode *inode;
293	struct mq_attr *attr = dentry->d_fsdata;
294	int error;
295	struct ipc_namespace *ipc_ns;
296
297	spin_lock(&mq_lock);
298	ipc_ns = __get_ns_from_inode(dir);
299	if (!ipc_ns) {
300		error = -EACCES;
301		goto out_unlock;
302	}
303	if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
304			!capable(CAP_SYS_RESOURCE)) {
305		error = -ENOSPC;
306		goto out_unlock;
307	}
308	ipc_ns->mq_queues_count++;
309	spin_unlock(&mq_lock);
310
311	inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
312	if (IS_ERR(inode)) {
313		error = PTR_ERR(inode);
314		spin_lock(&mq_lock);
315		ipc_ns->mq_queues_count--;
316		goto out_unlock;
317	}
318
319	put_ipc_ns(ipc_ns);
320	dir->i_size += DIRENT_SIZE;
321	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
322
323	d_instantiate(dentry, inode);
324	dget(dentry);
325	return 0;
326out_unlock:
327	spin_unlock(&mq_lock);
328	if (ipc_ns)
329		put_ipc_ns(ipc_ns);
330	return error;
331}
332
333static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
334{
335  	struct inode *inode = dentry->d_inode;
336
337	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
338	dir->i_size -= DIRENT_SIZE;
339  	drop_nlink(inode);
340  	dput(dentry);
341  	return 0;
342}
343
344/*
345*	This is routine for system read from queue file.
346*	To avoid mess with doing here some sort of mq_receive we allow
347*	to read only queue size & notification info (the only values
348*	that are interesting from user point of view and aren't accessible
349*	through std routines)
350*/
351static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
352				size_t count, loff_t *off)
353{
354	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
355	char buffer[FILENT_SIZE];
356	ssize_t ret;
357
358	spin_lock(&info->lock);
359	snprintf(buffer, sizeof(buffer),
360			"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
361			info->qsize,
362			info->notify_owner ? info->notify.sigev_notify : 0,
363			(info->notify_owner &&
364			 info->notify.sigev_notify == SIGEV_SIGNAL) ?
365				info->notify.sigev_signo : 0,
366			pid_vnr(info->notify_owner));
367	spin_unlock(&info->lock);
368	buffer[sizeof(buffer)-1] = '\0';
369
370	ret = simple_read_from_buffer(u_data, count, off, buffer,
371				strlen(buffer));
372	if (ret <= 0)
373		return ret;
374
375	filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
376	return ret;
377}
378
379static int mqueue_flush_file(struct file *filp, fl_owner_t id)
380{
381	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
382
383	spin_lock(&info->lock);
384	if (task_tgid(current) == info->notify_owner)
385		remove_notification(info);
386
387	spin_unlock(&info->lock);
388	return 0;
389}
390
391static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
392{
393	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
394	int retval = 0;
395
396	poll_wait(filp, &info->wait_q, poll_tab);
397
398	spin_lock(&info->lock);
399	if (info->attr.mq_curmsgs)
400		retval = POLLIN | POLLRDNORM;
401
402	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
403		retval |= POLLOUT | POLLWRNORM;
404	spin_unlock(&info->lock);
405
406	return retval;
407}
408
409/* Adds current to info->e_wait_q[sr] before element with smaller prio */
410static void wq_add(struct mqueue_inode_info *info, int sr,
411			struct ext_wait_queue *ewp)
412{
413	struct ext_wait_queue *walk;
414
415	ewp->task = current;
416
417	list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
418		if (walk->task->static_prio <= current->static_prio) {
419			list_add_tail(&ewp->list, &walk->list);
420			return;
421		}
422	}
423	list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
424}
425
426/*
427 * Puts current task to sleep. Caller must hold queue lock. After return
428 * lock isn't held.
429 * sr: SEND or RECV
430 */
431static int wq_sleep(struct mqueue_inode_info *info, int sr,
432		    ktime_t *timeout, struct ext_wait_queue *ewp)
433{
434	int retval;
435	signed long time;
436
437	wq_add(info, sr, ewp);
438
439	for (;;) {
440		set_current_state(TASK_INTERRUPTIBLE);
441
442		spin_unlock(&info->lock);
443		time = schedule_hrtimeout_range_clock(timeout, 0,
444			HRTIMER_MODE_ABS, CLOCK_REALTIME);
445
446		while (ewp->state == STATE_PENDING)
447			cpu_relax();
448
449		if (ewp->state == STATE_READY) {
450			retval = 0;
451			goto out;
452		}
453		spin_lock(&info->lock);
454		if (ewp->state == STATE_READY) {
455			retval = 0;
456			goto out_unlock;
457		}
458		if (signal_pending(current)) {
459			retval = -ERESTARTSYS;
460			break;
461		}
462		if (time == 0) {
463			retval = -ETIMEDOUT;
464			break;
465		}
466	}
467	list_del(&ewp->list);
468out_unlock:
469	spin_unlock(&info->lock);
470out:
471	return retval;
472}
473
474/*
475 * Returns waiting task that should be serviced first or NULL if none exists
476 */
477static struct ext_wait_queue *wq_get_first_waiter(
478		struct mqueue_inode_info *info, int sr)
479{
480	struct list_head *ptr;
481
482	ptr = info->e_wait_q[sr].list.prev;
483	if (ptr == &info->e_wait_q[sr].list)
484		return NULL;
485	return list_entry(ptr, struct ext_wait_queue, list);
486}
487
488/* Auxiliary functions to manipulate messages' list */
489static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
490{
491	int k;
492
493	k = info->attr.mq_curmsgs - 1;
494	while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
495		info->messages[k + 1] = info->messages[k];
496		k--;
497	}
498	info->attr.mq_curmsgs++;
499	info->qsize += ptr->m_ts;
500	info->messages[k + 1] = ptr;
501}
502
503static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
504{
505	info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
506	return info->messages[info->attr.mq_curmsgs];
507}
508
509static inline void set_cookie(struct sk_buff *skb, char code)
510{
511	((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
512}
513
514/*
515 * The next function is only to split too long sys_mq_timedsend
516 */
517static void __do_notify(struct mqueue_inode_info *info)
518{
519	/* notification
520	 * invoked when there is registered process and there isn't process
521	 * waiting synchronously for message AND state of queue changed from
522	 * empty to not empty. Here we are sure that no one is waiting
523	 * synchronously. */
524	if (info->notify_owner &&
525	    info->attr.mq_curmsgs == 1) {
526		struct siginfo sig_i;
527		switch (info->notify.sigev_notify) {
528		case SIGEV_NONE:
529			break;
530		case SIGEV_SIGNAL:
531			/* sends signal */
532
533			sig_i.si_signo = info->notify.sigev_signo;
534			sig_i.si_errno = 0;
535			sig_i.si_code = SI_MESGQ;
536			sig_i.si_value = info->notify.sigev_value;
537			/* map current pid/uid into info->owner's namespaces */
538			rcu_read_lock();
539			sig_i.si_pid = task_tgid_nr_ns(current,
540						ns_of_pid(info->notify_owner));
541			sig_i.si_uid = user_ns_map_uid(info->notify_user_ns,
542						current_cred(), current_uid());
543			rcu_read_unlock();
544
545			kill_pid_info(info->notify.sigev_signo,
546				      &sig_i, info->notify_owner);
547			break;
548		case SIGEV_THREAD:
549			set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
550			netlink_sendskb(info->notify_sock, info->notify_cookie);
551			break;
552		}
553		/* after notification unregisters process */
554		put_pid(info->notify_owner);
555		put_user_ns(info->notify_user_ns);
556		info->notify_owner = NULL;
557		info->notify_user_ns = NULL;
558	}
559	wake_up(&info->wait_q);
560}
561
562static int prepare_timeout(const struct timespec __user *u_abs_timeout,
563			   ktime_t *expires, struct timespec *ts)
564{
565	if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
566		return -EFAULT;
567	if (!timespec_valid(ts))
568		return -EINVAL;
569
570	*expires = timespec_to_ktime(*ts);
571	return 0;
572}
573
574static void remove_notification(struct mqueue_inode_info *info)
575{
576	if (info->notify_owner != NULL &&
577	    info->notify.sigev_notify == SIGEV_THREAD) {
578		set_cookie(info->notify_cookie, NOTIFY_REMOVED);
579		netlink_sendskb(info->notify_sock, info->notify_cookie);
580	}
581	put_pid(info->notify_owner);
582	put_user_ns(info->notify_user_ns);
583	info->notify_owner = NULL;
584	info->notify_user_ns = NULL;
585}
586
587static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
588{
589	if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
590		return 0;
591	if (capable(CAP_SYS_RESOURCE)) {
592		if (attr->mq_maxmsg > HARD_MSGMAX)
593			return 0;
594	} else {
595		if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
596				attr->mq_msgsize > ipc_ns->mq_msgsize_max)
597			return 0;
598	}
599	/* check for overflow */
600	if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
601		return 0;
602	if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
603	    + sizeof (struct msg_msg *))) <
604	    (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
605		return 0;
606	return 1;
607}
608
609/*
610 * Invoked when creating a new queue via sys_mq_open
611 */
612static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
613			struct dentry *dentry, int oflag, umode_t mode,
614			struct mq_attr *attr)
615{
616	const struct cred *cred = current_cred();
617	struct file *result;
618	int ret;
619
620	if (attr) {
621		if (!mq_attr_ok(ipc_ns, attr)) {
622			ret = -EINVAL;
623			goto out;
624		}
625		/* store for use during create */
626		dentry->d_fsdata = attr;
627	}
628
629	mode &= ~current_umask();
630	ret = mnt_want_write(ipc_ns->mq_mnt);
631	if (ret)
632		goto out;
633	ret = vfs_create(dir->d_inode, dentry, mode, NULL);
634	dentry->d_fsdata = NULL;
635	if (ret)
636		goto out_drop_write;
637
638	result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
639	/*
640	 * dentry_open() took a persistent mnt_want_write(),
641	 * so we can now drop this one.
642	 */
643	mnt_drop_write(ipc_ns->mq_mnt);
644	return result;
645
646out_drop_write:
647	mnt_drop_write(ipc_ns->mq_mnt);
648out:
649	dput(dentry);
650	mntput(ipc_ns->mq_mnt);
651	return ERR_PTR(ret);
652}
653
654/* Opens existing queue */
655static struct file *do_open(struct ipc_namespace *ipc_ns,
656				struct dentry *dentry, int oflag)
657{
658	int ret;
659	const struct cred *cred = current_cred();
660
661	static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
662						  MAY_READ | MAY_WRITE };
663
664	if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
665		ret = -EINVAL;
666		goto err;
667	}
668
669	if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
670		ret = -EACCES;
671		goto err;
672	}
673
674	return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
675
676err:
677	dput(dentry);
678	mntput(ipc_ns->mq_mnt);
679	return ERR_PTR(ret);
680}
681
682SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
683		struct mq_attr __user *, u_attr)
684{
685	struct dentry *dentry;
686	struct file *filp;
687	char *name;
688	struct mq_attr attr;
689	int fd, error;
690	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
691
692	if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
693		return -EFAULT;
694
695	audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
696
697	if (IS_ERR(name = getname(u_name)))
698		return PTR_ERR(name);
699
700	fd = get_unused_fd_flags(O_CLOEXEC);
701	if (fd < 0)
702		goto out_putname;
703
704	mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
705	dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
706	if (IS_ERR(dentry)) {
707		error = PTR_ERR(dentry);
708		goto out_putfd;
709	}
710	mntget(ipc_ns->mq_mnt);
711
712	if (oflag & O_CREAT) {
713		if (dentry->d_inode) {	/* entry already exists */
714			audit_inode(name, dentry);
715			if (oflag & O_EXCL) {
716				error = -EEXIST;
717				goto out;
718			}
719			filp = do_open(ipc_ns, dentry, oflag);
720		} else {
721			filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
722						dentry, oflag, mode,
723						u_attr ? &attr : NULL);
724		}
725	} else {
726		if (!dentry->d_inode) {
727			error = -ENOENT;
728			goto out;
729		}
730		audit_inode(name, dentry);
731		filp = do_open(ipc_ns, dentry, oflag);
732	}
733
734	if (IS_ERR(filp)) {
735		error = PTR_ERR(filp);
736		goto out_putfd;
737	}
738
739	fd_install(fd, filp);
740	goto out_upsem;
741
742out:
743	dput(dentry);
744	mntput(ipc_ns->mq_mnt);
745out_putfd:
746	put_unused_fd(fd);
747	fd = error;
748out_upsem:
749	mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
750out_putname:
751	putname(name);
752	return fd;
753}
754
755SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
756{
757	int err;
758	char *name;
759	struct dentry *dentry;
760	struct inode *inode = NULL;
761	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
762
763	name = getname(u_name);
764	if (IS_ERR(name))
765		return PTR_ERR(name);
766
767	mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
768			I_MUTEX_PARENT);
769	dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
770	if (IS_ERR(dentry)) {
771		err = PTR_ERR(dentry);
772		goto out_unlock;
773	}
774
775	if (!dentry->d_inode) {
776		err = -ENOENT;
777		goto out_err;
778	}
779
780	inode = dentry->d_inode;
781	if (inode)
782		ihold(inode);
783	err = mnt_want_write(ipc_ns->mq_mnt);
784	if (err)
785		goto out_err;
786	err = vfs_unlink(dentry->d_parent->d_inode, dentry);
787	mnt_drop_write(ipc_ns->mq_mnt);
788out_err:
789	dput(dentry);
790
791out_unlock:
792	mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
793	putname(name);
794	if (inode)
795		iput(inode);
796
797	return err;
798}
799
800/* Pipelined send and receive functions.
801 *
802 * If a receiver finds no waiting message, then it registers itself in the
803 * list of waiting receivers. A sender checks that list before adding the new
804 * message into the message array. If there is a waiting receiver, then it
805 * bypasses the message array and directly hands the message over to the
806 * receiver.
807 * The receiver accepts the message and returns without grabbing the queue
808 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
809 * are necessary. The same algorithm is used for sysv semaphores, see
810 * ipc/sem.c for more details.
811 *
812 * The same algorithm is used for senders.
813 */
814
815/* pipelined_send() - send a message directly to the task waiting in
816 * sys_mq_timedreceive() (without inserting message into a queue).
817 */
818static inline void pipelined_send(struct mqueue_inode_info *info,
819				  struct msg_msg *message,
820				  struct ext_wait_queue *receiver)
821{
822	receiver->msg = message;
823	list_del(&receiver->list);
824	receiver->state = STATE_PENDING;
825	wake_up_process(receiver->task);
826	smp_wmb();
827	receiver->state = STATE_READY;
828}
829
830/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
831 * gets its message and put to the queue (we have one free place for sure). */
832static inline void pipelined_receive(struct mqueue_inode_info *info)
833{
834	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
835
836	if (!sender) {
837		/* for poll */
838		wake_up_interruptible(&info->wait_q);
839		return;
840	}
841	msg_insert(sender->msg, info);
842	list_del(&sender->list);
843	sender->state = STATE_PENDING;
844	wake_up_process(sender->task);
845	smp_wmb();
846	sender->state = STATE_READY;
847}
848
849SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
850		size_t, msg_len, unsigned int, msg_prio,
851		const struct timespec __user *, u_abs_timeout)
852{
853	struct file *filp;
854	struct inode *inode;
855	struct ext_wait_queue wait;
856	struct ext_wait_queue *receiver;
857	struct msg_msg *msg_ptr;
858	struct mqueue_inode_info *info;
859	ktime_t expires, *timeout = NULL;
860	struct timespec ts;
861	int ret;
862
863	if (u_abs_timeout) {
864		int res = prepare_timeout(u_abs_timeout, &expires, &ts);
865		if (res)
866			return res;
867		timeout = &expires;
868	}
869
870	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
871		return -EINVAL;
872
873	audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
874
875	filp = fget(mqdes);
876	if (unlikely(!filp)) {
877		ret = -EBADF;
878		goto out;
879	}
880
881	inode = filp->f_path.dentry->d_inode;
882	if (unlikely(filp->f_op != &mqueue_file_operations)) {
883		ret = -EBADF;
884		goto out_fput;
885	}
886	info = MQUEUE_I(inode);
887	audit_inode(NULL, filp->f_path.dentry);
888
889	if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
890		ret = -EBADF;
891		goto out_fput;
892	}
893
894	if (unlikely(msg_len > info->attr.mq_msgsize)) {
895		ret = -EMSGSIZE;
896		goto out_fput;
897	}
898
899	/* First try to allocate memory, before doing anything with
900	 * existing queues. */
901	msg_ptr = load_msg(u_msg_ptr, msg_len);
902	if (IS_ERR(msg_ptr)) {
903		ret = PTR_ERR(msg_ptr);
904		goto out_fput;
905	}
906	msg_ptr->m_ts = msg_len;
907	msg_ptr->m_type = msg_prio;
908
909	spin_lock(&info->lock);
910
911	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
912		if (filp->f_flags & O_NONBLOCK) {
913			spin_unlock(&info->lock);
914			ret = -EAGAIN;
915		} else {
916			wait.task = current;
917			wait.msg = (void *) msg_ptr;
918			wait.state = STATE_NONE;
919			ret = wq_sleep(info, SEND, timeout, &wait);
920		}
921		if (ret < 0)
922			free_msg(msg_ptr);
923	} else {
924		receiver = wq_get_first_waiter(info, RECV);
925		if (receiver) {
926			pipelined_send(info, msg_ptr, receiver);
927		} else {
928			/* adds message to the queue */
929			msg_insert(msg_ptr, info);
930			__do_notify(info);
931		}
932		inode->i_atime = inode->i_mtime = inode->i_ctime =
933				CURRENT_TIME;
934		spin_unlock(&info->lock);
935		ret = 0;
936	}
937out_fput:
938	fput(filp);
939out:
940	return ret;
941}
942
943SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
944		size_t, msg_len, unsigned int __user *, u_msg_prio,
945		const struct timespec __user *, u_abs_timeout)
946{
947	ssize_t ret;
948	struct msg_msg *msg_ptr;
949	struct file *filp;
950	struct inode *inode;
951	struct mqueue_inode_info *info;
952	struct ext_wait_queue wait;
953	ktime_t expires, *timeout = NULL;
954	struct timespec ts;
955
956	if (u_abs_timeout) {
957		int res = prepare_timeout(u_abs_timeout, &expires, &ts);
958		if (res)
959			return res;
960		timeout = &expires;
961	}
962
963	audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
964
965	filp = fget(mqdes);
966	if (unlikely(!filp)) {
967		ret = -EBADF;
968		goto out;
969	}
970
971	inode = filp->f_path.dentry->d_inode;
972	if (unlikely(filp->f_op != &mqueue_file_operations)) {
973		ret = -EBADF;
974		goto out_fput;
975	}
976	info = MQUEUE_I(inode);
977	audit_inode(NULL, filp->f_path.dentry);
978
979	if (unlikely(!(filp->f_mode & FMODE_READ))) {
980		ret = -EBADF;
981		goto out_fput;
982	}
983
984	/* checks if buffer is big enough */
985	if (unlikely(msg_len < info->attr.mq_msgsize)) {
986		ret = -EMSGSIZE;
987		goto out_fput;
988	}
989
990	spin_lock(&info->lock);
991	if (info->attr.mq_curmsgs == 0) {
992		if (filp->f_flags & O_NONBLOCK) {
993			spin_unlock(&info->lock);
994			ret = -EAGAIN;
995		} else {
996			wait.task = current;
997			wait.state = STATE_NONE;
998			ret = wq_sleep(info, RECV, timeout, &wait);
999			msg_ptr = wait.msg;
1000		}
1001	} else {
1002		msg_ptr = msg_get(info);
1003
1004		inode->i_atime = inode->i_mtime = inode->i_ctime =
1005				CURRENT_TIME;
1006
1007		/* There is now free space in queue. */
1008		pipelined_receive(info);
1009		spin_unlock(&info->lock);
1010		ret = 0;
1011	}
1012	if (ret == 0) {
1013		ret = msg_ptr->m_ts;
1014
1015		if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1016			store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1017			ret = -EFAULT;
1018		}
1019		free_msg(msg_ptr);
1020	}
1021out_fput:
1022	fput(filp);
1023out:
1024	return ret;
1025}
1026
1027/*
1028 * Notes: the case when user wants us to deregister (with NULL as pointer)
1029 * and he isn't currently owner of notification, will be silently discarded.
1030 * It isn't explicitly defined in the POSIX.
1031 */
1032SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1033		const struct sigevent __user *, u_notification)
1034{
1035	int ret;
1036	struct file *filp;
1037	struct sock *sock;
1038	struct inode *inode;
1039	struct sigevent notification;
1040	struct mqueue_inode_info *info;
1041	struct sk_buff *nc;
1042
1043	if (u_notification) {
1044		if (copy_from_user(&notification, u_notification,
1045					sizeof(struct sigevent)))
1046			return -EFAULT;
1047	}
1048
1049	audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1050
1051	nc = NULL;
1052	sock = NULL;
1053	if (u_notification != NULL) {
1054		if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1055			     notification.sigev_notify != SIGEV_SIGNAL &&
1056			     notification.sigev_notify != SIGEV_THREAD))
1057			return -EINVAL;
1058		if (notification.sigev_notify == SIGEV_SIGNAL &&
1059			!valid_signal(notification.sigev_signo)) {
1060			return -EINVAL;
1061		}
1062		if (notification.sigev_notify == SIGEV_THREAD) {
1063			long timeo;
1064
1065			/* create the notify skb */
1066			nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1067			if (!nc) {
1068				ret = -ENOMEM;
1069				goto out;
1070			}
1071			if (copy_from_user(nc->data,
1072					notification.sigev_value.sival_ptr,
1073					NOTIFY_COOKIE_LEN)) {
1074				ret = -EFAULT;
1075				goto out;
1076			}
1077
1078			/* TODO: add a header? */
1079			skb_put(nc, NOTIFY_COOKIE_LEN);
1080			/* and attach it to the socket */
1081retry:
1082			filp = fget(notification.sigev_signo);
1083			if (!filp) {
1084				ret = -EBADF;
1085				goto out;
1086			}
1087			sock = netlink_getsockbyfilp(filp);
1088			fput(filp);
1089			if (IS_ERR(sock)) {
1090				ret = PTR_ERR(sock);
1091				sock = NULL;
1092				goto out;
1093			}
1094
1095			timeo = MAX_SCHEDULE_TIMEOUT;
1096			ret = netlink_attachskb(sock, nc, &timeo, NULL);
1097			if (ret == 1)
1098				goto retry;
1099			if (ret) {
1100				sock = NULL;
1101				nc = NULL;
1102				goto out;
1103			}
1104		}
1105	}
1106
1107	filp = fget(mqdes);
1108	if (!filp) {
1109		ret = -EBADF;
1110		goto out;
1111	}
1112
1113	inode = filp->f_path.dentry->d_inode;
1114	if (unlikely(filp->f_op != &mqueue_file_operations)) {
1115		ret = -EBADF;
1116		goto out_fput;
1117	}
1118	info = MQUEUE_I(inode);
1119
1120	ret = 0;
1121	spin_lock(&info->lock);
1122	if (u_notification == NULL) {
1123		if (info->notify_owner == task_tgid(current)) {
1124			remove_notification(info);
1125			inode->i_atime = inode->i_ctime = CURRENT_TIME;
1126		}
1127	} else if (info->notify_owner != NULL) {
1128		ret = -EBUSY;
1129	} else {
1130		switch (notification.sigev_notify) {
1131		case SIGEV_NONE:
1132			info->notify.sigev_notify = SIGEV_NONE;
1133			break;
1134		case SIGEV_THREAD:
1135			info->notify_sock = sock;
1136			info->notify_cookie = nc;
1137			sock = NULL;
1138			nc = NULL;
1139			info->notify.sigev_notify = SIGEV_THREAD;
1140			break;
1141		case SIGEV_SIGNAL:
1142			info->notify.sigev_signo = notification.sigev_signo;
1143			info->notify.sigev_value = notification.sigev_value;
1144			info->notify.sigev_notify = SIGEV_SIGNAL;
1145			break;
1146		}
1147
1148		info->notify_owner = get_pid(task_tgid(current));
1149		info->notify_user_ns = get_user_ns(current_user_ns());
1150		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1151	}
1152	spin_unlock(&info->lock);
1153out_fput:
1154	fput(filp);
1155out:
1156	if (sock) {
1157		netlink_detachskb(sock, nc);
1158	} else if (nc) {
1159		dev_kfree_skb(nc);
1160	}
1161	return ret;
1162}
1163
1164SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1165		const struct mq_attr __user *, u_mqstat,
1166		struct mq_attr __user *, u_omqstat)
1167{
1168	int ret;
1169	struct mq_attr mqstat, omqstat;
1170	struct file *filp;
1171	struct inode *inode;
1172	struct mqueue_inode_info *info;
1173
1174	if (u_mqstat != NULL) {
1175		if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1176			return -EFAULT;
1177		if (mqstat.mq_flags & (~O_NONBLOCK))
1178			return -EINVAL;
1179	}
1180
1181	filp = fget(mqdes);
1182	if (!filp) {
1183		ret = -EBADF;
1184		goto out;
1185	}
1186
1187	inode = filp->f_path.dentry->d_inode;
1188	if (unlikely(filp->f_op != &mqueue_file_operations)) {
1189		ret = -EBADF;
1190		goto out_fput;
1191	}
1192	info = MQUEUE_I(inode);
1193
1194	spin_lock(&info->lock);
1195
1196	omqstat = info->attr;
1197	omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1198	if (u_mqstat) {
1199		audit_mq_getsetattr(mqdes, &mqstat);
1200		spin_lock(&filp->f_lock);
1201		if (mqstat.mq_flags & O_NONBLOCK)
1202			filp->f_flags |= O_NONBLOCK;
1203		else
1204			filp->f_flags &= ~O_NONBLOCK;
1205		spin_unlock(&filp->f_lock);
1206
1207		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1208	}
1209
1210	spin_unlock(&info->lock);
1211
1212	ret = 0;
1213	if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1214						sizeof(struct mq_attr)))
1215		ret = -EFAULT;
1216
1217out_fput:
1218	fput(filp);
1219out:
1220	return ret;
1221}
1222
1223static const struct inode_operations mqueue_dir_inode_operations = {
1224	.lookup = simple_lookup,
1225	.create = mqueue_create,
1226	.unlink = mqueue_unlink,
1227};
1228
1229static const struct file_operations mqueue_file_operations = {
1230	.flush = mqueue_flush_file,
1231	.poll = mqueue_poll_file,
1232	.read = mqueue_read_file,
1233	.llseek = default_llseek,
1234};
1235
1236static const struct super_operations mqueue_super_ops = {
1237	.alloc_inode = mqueue_alloc_inode,
1238	.destroy_inode = mqueue_destroy_inode,
1239	.evict_inode = mqueue_evict_inode,
1240	.statfs = simple_statfs,
1241};
1242
1243static struct file_system_type mqueue_fs_type = {
1244	.name = "mqueue",
1245	.mount = mqueue_mount,
1246	.kill_sb = kill_litter_super,
1247};
1248
1249int mq_init_ns(struct ipc_namespace *ns)
1250{
1251	ns->mq_queues_count  = 0;
1252	ns->mq_queues_max    = DFLT_QUEUESMAX;
1253	ns->mq_msg_max       = DFLT_MSGMAX;
1254	ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1255
1256	ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1257	if (IS_ERR(ns->mq_mnt)) {
1258		int err = PTR_ERR(ns->mq_mnt);
1259		ns->mq_mnt = NULL;
1260		return err;
1261	}
1262	return 0;
1263}
1264
1265void mq_clear_sbinfo(struct ipc_namespace *ns)
1266{
1267	ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1268}
1269
1270void mq_put_mnt(struct ipc_namespace *ns)
1271{
1272	kern_unmount(ns->mq_mnt);
1273}
1274
1275static int __init init_mqueue_fs(void)
1276{
1277	int error;
1278
1279	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1280				sizeof(struct mqueue_inode_info), 0,
1281				SLAB_HWCACHE_ALIGN, init_once);
1282	if (mqueue_inode_cachep == NULL)
1283		return -ENOMEM;
1284
1285	/* ignore failures - they are not fatal */
1286	mq_sysctl_table = mq_register_sysctl_table();
1287
1288	error = register_filesystem(&mqueue_fs_type);
1289	if (error)
1290		goto out_sysctl;
1291
1292	spin_lock_init(&mq_lock);
1293
1294	error = mq_init_ns(&init_ipc_ns);
1295	if (error)
1296		goto out_filesystem;
1297
1298	return 0;
1299
1300out_filesystem:
1301	unregister_filesystem(&mqueue_fs_type);
1302out_sysctl:
1303	if (mq_sysctl_table)
1304		unregister_sysctl_table(mq_sysctl_table);
1305	kmem_cache_destroy(mqueue_inode_cachep);
1306	return error;
1307}
1308
1309__initcall(init_mqueue_fs);
1310