mqueue.c revision fd1f87d2
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/vmalloc.h>
28#include <linux/netlink.h>
29#include <linux/syscalls.h>
30#include <linux/audit.h>
31#include <linux/signal.h>
32#include <linux/mutex.h>
33#include <linux/nsproxy.h>
34#include <linux/pid.h>
35#include <linux/ipc_namespace.h>
36#include <linux/user_namespace.h>
37#include <linux/slab.h>
38
39#include <net/sock.h>
40#include "util.h"
41
42#define MQUEUE_MAGIC	0x19800202
43#define DIRENT_SIZE	20
44#define FILENT_SIZE	80
45
46#define SEND		0
47#define RECV		1
48
49#define STATE_NONE	0
50#define STATE_PENDING	1
51#define STATE_READY	2
52
53struct ext_wait_queue {		/* queue of sleeping tasks */
54	struct task_struct *task;
55	struct list_head list;
56	struct msg_msg *msg;	/* ptr of loaded message */
57	int state;		/* one of STATE_* values */
58};
59
60struct mqueue_inode_info {
61	spinlock_t lock;
62	struct inode vfs_inode;
63	wait_queue_head_t wait_q;
64
65	struct msg_msg **messages;
66	struct mq_attr attr;
67
68	struct sigevent notify;
69	struct pid* notify_owner;
70	struct user_namespace *notify_user_ns;
71	struct user_struct *user;	/* user who created, for accounting */
72	struct sock *notify_sock;
73	struct sk_buff *notify_cookie;
74
75	/* for tasks waiting for free space and messages, respectively */
76	struct ext_wait_queue e_wait_q[2];
77
78	unsigned long qsize; /* size of queue in memory (sum of all msgs) */
79};
80
81static const struct inode_operations mqueue_dir_inode_operations;
82static const struct file_operations mqueue_file_operations;
83static const struct super_operations mqueue_super_ops;
84static void remove_notification(struct mqueue_inode_info *info);
85
86static struct kmem_cache *mqueue_inode_cachep;
87
88static struct ctl_table_header * mq_sysctl_table;
89
90static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
91{
92	return container_of(inode, struct mqueue_inode_info, vfs_inode);
93}
94
95/*
96 * This routine should be called with the mq_lock held.
97 */
98static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
99{
100	return get_ipc_ns(inode->i_sb->s_fs_info);
101}
102
103static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
104{
105	struct ipc_namespace *ns;
106
107	spin_lock(&mq_lock);
108	ns = __get_ns_from_inode(inode);
109	spin_unlock(&mq_lock);
110	return ns;
111}
112
113static struct inode *mqueue_get_inode(struct super_block *sb,
114		struct ipc_namespace *ipc_ns, umode_t mode,
115		struct mq_attr *attr)
116{
117	struct user_struct *u = current_user();
118	struct inode *inode;
119	int ret = -ENOMEM;
120
121	inode = new_inode(sb);
122	if (!inode)
123		goto err;
124
125	inode->i_ino = get_next_ino();
126	inode->i_mode = mode;
127	inode->i_uid = current_fsuid();
128	inode->i_gid = current_fsgid();
129	inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
130
131	if (S_ISREG(mode)) {
132		struct mqueue_inode_info *info;
133		unsigned long mq_bytes, mq_msg_tblsz;
134
135		inode->i_fop = &mqueue_file_operations;
136		inode->i_size = FILENT_SIZE;
137		/* mqueue specific info */
138		info = MQUEUE_I(inode);
139		spin_lock_init(&info->lock);
140		init_waitqueue_head(&info->wait_q);
141		INIT_LIST_HEAD(&info->e_wait_q[0].list);
142		INIT_LIST_HEAD(&info->e_wait_q[1].list);
143		info->notify_owner = NULL;
144		info->notify_user_ns = NULL;
145		info->qsize = 0;
146		info->user = NULL;	/* set when all is ok */
147		memset(&info->attr, 0, sizeof(info->attr));
148		info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max, DFLT_MSG);
149		info->attr.mq_msgsize =
150			min(ipc_ns->mq_msgsize_max, DFLT_MSGSIZE);
151		if (attr) {
152			info->attr.mq_maxmsg = attr->mq_maxmsg;
153			info->attr.mq_msgsize = attr->mq_msgsize;
154		}
155		mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
156		if (mq_msg_tblsz > PAGE_SIZE)
157			info->messages = vmalloc(mq_msg_tblsz);
158		else
159			info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
160		if (!info->messages)
161			goto out_inode;
162
163		mq_bytes = (mq_msg_tblsz +
164			(info->attr.mq_maxmsg * info->attr.mq_msgsize));
165
166		spin_lock(&mq_lock);
167		if (u->mq_bytes + mq_bytes < u->mq_bytes ||
168		    u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
169			spin_unlock(&mq_lock);
170			/* mqueue_evict_inode() releases info->messages */
171			ret = -EMFILE;
172			goto out_inode;
173		}
174		u->mq_bytes += mq_bytes;
175		spin_unlock(&mq_lock);
176
177		/* all is ok */
178		info->user = get_uid(u);
179	} else if (S_ISDIR(mode)) {
180		inc_nlink(inode);
181		/* Some things misbehave if size == 0 on a directory */
182		inode->i_size = 2 * DIRENT_SIZE;
183		inode->i_op = &mqueue_dir_inode_operations;
184		inode->i_fop = &simple_dir_operations;
185	}
186
187	return inode;
188out_inode:
189	iput(inode);
190err:
191	return ERR_PTR(ret);
192}
193
194static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
195{
196	struct inode *inode;
197	struct ipc_namespace *ns = data;
198
199	sb->s_blocksize = PAGE_CACHE_SIZE;
200	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
201	sb->s_magic = MQUEUE_MAGIC;
202	sb->s_op = &mqueue_super_ops;
203
204	inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
205	if (IS_ERR(inode))
206		return PTR_ERR(inode);
207
208	sb->s_root = d_make_root(inode);
209	if (!sb->s_root)
210		return -ENOMEM;
211	return 0;
212}
213
214static struct dentry *mqueue_mount(struct file_system_type *fs_type,
215			 int flags, const char *dev_name,
216			 void *data)
217{
218	if (!(flags & MS_KERNMOUNT))
219		data = current->nsproxy->ipc_ns;
220	return mount_ns(fs_type, flags, data, mqueue_fill_super);
221}
222
223static void init_once(void *foo)
224{
225	struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
226
227	inode_init_once(&p->vfs_inode);
228}
229
230static struct inode *mqueue_alloc_inode(struct super_block *sb)
231{
232	struct mqueue_inode_info *ei;
233
234	ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
235	if (!ei)
236		return NULL;
237	return &ei->vfs_inode;
238}
239
240static void mqueue_i_callback(struct rcu_head *head)
241{
242	struct inode *inode = container_of(head, struct inode, i_rcu);
243	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
244}
245
246static void mqueue_destroy_inode(struct inode *inode)
247{
248	call_rcu(&inode->i_rcu, mqueue_i_callback);
249}
250
251static void mqueue_evict_inode(struct inode *inode)
252{
253	struct mqueue_inode_info *info;
254	struct user_struct *user;
255	unsigned long mq_bytes;
256	int i;
257	struct ipc_namespace *ipc_ns;
258
259	clear_inode(inode);
260
261	if (S_ISDIR(inode->i_mode))
262		return;
263
264	ipc_ns = get_ns_from_inode(inode);
265	info = MQUEUE_I(inode);
266	spin_lock(&info->lock);
267	for (i = 0; i < info->attr.mq_curmsgs; i++)
268		free_msg(info->messages[i]);
269	if (is_vmalloc_addr(info->messages))
270		vfree(info->messages);
271	else
272		kfree(info->messages);
273	spin_unlock(&info->lock);
274
275	/* Total amount of bytes accounted for the mqueue */
276	mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
277	    + info->attr.mq_msgsize);
278	user = info->user;
279	if (user) {
280		spin_lock(&mq_lock);
281		user->mq_bytes -= mq_bytes;
282		/*
283		 * get_ns_from_inode() ensures that the
284		 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
285		 * to which we now hold a reference, or it is NULL.
286		 * We can't put it here under mq_lock, though.
287		 */
288		if (ipc_ns)
289			ipc_ns->mq_queues_count--;
290		spin_unlock(&mq_lock);
291		free_uid(user);
292	}
293	if (ipc_ns)
294		put_ipc_ns(ipc_ns);
295}
296
297static int mqueue_create(struct inode *dir, struct dentry *dentry,
298				umode_t mode, struct nameidata *nd)
299{
300	struct inode *inode;
301	struct mq_attr *attr = dentry->d_fsdata;
302	int error;
303	struct ipc_namespace *ipc_ns;
304
305	spin_lock(&mq_lock);
306	ipc_ns = __get_ns_from_inode(dir);
307	if (!ipc_ns) {
308		error = -EACCES;
309		goto out_unlock;
310	}
311	if (ipc_ns->mq_queues_count >= HARD_QUEUESMAX ||
312	    (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
313	     !capable(CAP_SYS_RESOURCE))) {
314		error = -ENOSPC;
315		goto out_unlock;
316	}
317	ipc_ns->mq_queues_count++;
318	spin_unlock(&mq_lock);
319
320	inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
321	if (IS_ERR(inode)) {
322		error = PTR_ERR(inode);
323		spin_lock(&mq_lock);
324		ipc_ns->mq_queues_count--;
325		goto out_unlock;
326	}
327
328	put_ipc_ns(ipc_ns);
329	dir->i_size += DIRENT_SIZE;
330	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
331
332	d_instantiate(dentry, inode);
333	dget(dentry);
334	return 0;
335out_unlock:
336	spin_unlock(&mq_lock);
337	if (ipc_ns)
338		put_ipc_ns(ipc_ns);
339	return error;
340}
341
342static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
343{
344  	struct inode *inode = dentry->d_inode;
345
346	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
347	dir->i_size -= DIRENT_SIZE;
348  	drop_nlink(inode);
349  	dput(dentry);
350  	return 0;
351}
352
353/*
354*	This is routine for system read from queue file.
355*	To avoid mess with doing here some sort of mq_receive we allow
356*	to read only queue size & notification info (the only values
357*	that are interesting from user point of view and aren't accessible
358*	through std routines)
359*/
360static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
361				size_t count, loff_t *off)
362{
363	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
364	char buffer[FILENT_SIZE];
365	ssize_t ret;
366
367	spin_lock(&info->lock);
368	snprintf(buffer, sizeof(buffer),
369			"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
370			info->qsize,
371			info->notify_owner ? info->notify.sigev_notify : 0,
372			(info->notify_owner &&
373			 info->notify.sigev_notify == SIGEV_SIGNAL) ?
374				info->notify.sigev_signo : 0,
375			pid_vnr(info->notify_owner));
376	spin_unlock(&info->lock);
377	buffer[sizeof(buffer)-1] = '\0';
378
379	ret = simple_read_from_buffer(u_data, count, off, buffer,
380				strlen(buffer));
381	if (ret <= 0)
382		return ret;
383
384	filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
385	return ret;
386}
387
388static int mqueue_flush_file(struct file *filp, fl_owner_t id)
389{
390	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
391
392	spin_lock(&info->lock);
393	if (task_tgid(current) == info->notify_owner)
394		remove_notification(info);
395
396	spin_unlock(&info->lock);
397	return 0;
398}
399
400static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
401{
402	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
403	int retval = 0;
404
405	poll_wait(filp, &info->wait_q, poll_tab);
406
407	spin_lock(&info->lock);
408	if (info->attr.mq_curmsgs)
409		retval = POLLIN | POLLRDNORM;
410
411	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
412		retval |= POLLOUT | POLLWRNORM;
413	spin_unlock(&info->lock);
414
415	return retval;
416}
417
418/* Adds current to info->e_wait_q[sr] before element with smaller prio */
419static void wq_add(struct mqueue_inode_info *info, int sr,
420			struct ext_wait_queue *ewp)
421{
422	struct ext_wait_queue *walk;
423
424	ewp->task = current;
425
426	list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
427		if (walk->task->static_prio <= current->static_prio) {
428			list_add_tail(&ewp->list, &walk->list);
429			return;
430		}
431	}
432	list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
433}
434
435/*
436 * Puts current task to sleep. Caller must hold queue lock. After return
437 * lock isn't held.
438 * sr: SEND or RECV
439 */
440static int wq_sleep(struct mqueue_inode_info *info, int sr,
441		    ktime_t *timeout, struct ext_wait_queue *ewp)
442{
443	int retval;
444	signed long time;
445
446	wq_add(info, sr, ewp);
447
448	for (;;) {
449		set_current_state(TASK_INTERRUPTIBLE);
450
451		spin_unlock(&info->lock);
452		time = schedule_hrtimeout_range_clock(timeout, 0,
453			HRTIMER_MODE_ABS, CLOCK_REALTIME);
454
455		while (ewp->state == STATE_PENDING)
456			cpu_relax();
457
458		if (ewp->state == STATE_READY) {
459			retval = 0;
460			goto out;
461		}
462		spin_lock(&info->lock);
463		if (ewp->state == STATE_READY) {
464			retval = 0;
465			goto out_unlock;
466		}
467		if (signal_pending(current)) {
468			retval = -ERESTARTSYS;
469			break;
470		}
471		if (time == 0) {
472			retval = -ETIMEDOUT;
473			break;
474		}
475	}
476	list_del(&ewp->list);
477out_unlock:
478	spin_unlock(&info->lock);
479out:
480	return retval;
481}
482
483/*
484 * Returns waiting task that should be serviced first or NULL if none exists
485 */
486static struct ext_wait_queue *wq_get_first_waiter(
487		struct mqueue_inode_info *info, int sr)
488{
489	struct list_head *ptr;
490
491	ptr = info->e_wait_q[sr].list.prev;
492	if (ptr == &info->e_wait_q[sr].list)
493		return NULL;
494	return list_entry(ptr, struct ext_wait_queue, list);
495}
496
497/* Auxiliary functions to manipulate messages' list */
498static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
499{
500	int k;
501
502	k = info->attr.mq_curmsgs - 1;
503	while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
504		info->messages[k + 1] = info->messages[k];
505		k--;
506	}
507	info->attr.mq_curmsgs++;
508	info->qsize += ptr->m_ts;
509	info->messages[k + 1] = ptr;
510}
511
512static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
513{
514	info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
515	return info->messages[info->attr.mq_curmsgs];
516}
517
518static inline void set_cookie(struct sk_buff *skb, char code)
519{
520	((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
521}
522
523/*
524 * The next function is only to split too long sys_mq_timedsend
525 */
526static void __do_notify(struct mqueue_inode_info *info)
527{
528	/* notification
529	 * invoked when there is registered process and there isn't process
530	 * waiting synchronously for message AND state of queue changed from
531	 * empty to not empty. Here we are sure that no one is waiting
532	 * synchronously. */
533	if (info->notify_owner &&
534	    info->attr.mq_curmsgs == 1) {
535		struct siginfo sig_i;
536		switch (info->notify.sigev_notify) {
537		case SIGEV_NONE:
538			break;
539		case SIGEV_SIGNAL:
540			/* sends signal */
541
542			sig_i.si_signo = info->notify.sigev_signo;
543			sig_i.si_errno = 0;
544			sig_i.si_code = SI_MESGQ;
545			sig_i.si_value = info->notify.sigev_value;
546			/* map current pid/uid into info->owner's namespaces */
547			rcu_read_lock();
548			sig_i.si_pid = task_tgid_nr_ns(current,
549						ns_of_pid(info->notify_owner));
550			sig_i.si_uid = from_kuid_munged(info->notify_user_ns, current_uid());
551			rcu_read_unlock();
552
553			kill_pid_info(info->notify.sigev_signo,
554				      &sig_i, info->notify_owner);
555			break;
556		case SIGEV_THREAD:
557			set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
558			netlink_sendskb(info->notify_sock, info->notify_cookie);
559			break;
560		}
561		/* after notification unregisters process */
562		put_pid(info->notify_owner);
563		put_user_ns(info->notify_user_ns);
564		info->notify_owner = NULL;
565		info->notify_user_ns = NULL;
566	}
567	wake_up(&info->wait_q);
568}
569
570static int prepare_timeout(const struct timespec __user *u_abs_timeout,
571			   ktime_t *expires, struct timespec *ts)
572{
573	if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
574		return -EFAULT;
575	if (!timespec_valid(ts))
576		return -EINVAL;
577
578	*expires = timespec_to_ktime(*ts);
579	return 0;
580}
581
582static void remove_notification(struct mqueue_inode_info *info)
583{
584	if (info->notify_owner != NULL &&
585	    info->notify.sigev_notify == SIGEV_THREAD) {
586		set_cookie(info->notify_cookie, NOTIFY_REMOVED);
587		netlink_sendskb(info->notify_sock, info->notify_cookie);
588	}
589	put_pid(info->notify_owner);
590	put_user_ns(info->notify_user_ns);
591	info->notify_owner = NULL;
592	info->notify_user_ns = NULL;
593}
594
595static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
596{
597	if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
598		return 0;
599	if (capable(CAP_SYS_RESOURCE)) {
600		if (attr->mq_maxmsg > HARD_MSGMAX ||
601		    attr->mq_msgsize > HARD_MSGSIZEMAX)
602			return 0;
603	} else {
604		if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
605				attr->mq_msgsize > ipc_ns->mq_msgsize_max)
606			return 0;
607	}
608	/* check for overflow */
609	if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
610		return 0;
611	if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
612	    + sizeof (struct msg_msg *))) <
613	    (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
614		return 0;
615	return 1;
616}
617
618/*
619 * Invoked when creating a new queue via sys_mq_open
620 */
621static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
622			struct dentry *dentry, int oflag, umode_t mode,
623			struct mq_attr *attr)
624{
625	const struct cred *cred = current_cred();
626	struct file *result;
627	int ret;
628
629	if (attr) {
630		if (!mq_attr_ok(ipc_ns, attr)) {
631			ret = -EINVAL;
632			goto out;
633		}
634		/* store for use during create */
635		dentry->d_fsdata = attr;
636	}
637
638	mode &= ~current_umask();
639	ret = mnt_want_write(ipc_ns->mq_mnt);
640	if (ret)
641		goto out;
642	ret = vfs_create(dir->d_inode, dentry, mode, NULL);
643	dentry->d_fsdata = NULL;
644	if (ret)
645		goto out_drop_write;
646
647	result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
648	/*
649	 * dentry_open() took a persistent mnt_want_write(),
650	 * so we can now drop this one.
651	 */
652	mnt_drop_write(ipc_ns->mq_mnt);
653	return result;
654
655out_drop_write:
656	mnt_drop_write(ipc_ns->mq_mnt);
657out:
658	dput(dentry);
659	mntput(ipc_ns->mq_mnt);
660	return ERR_PTR(ret);
661}
662
663/* Opens existing queue */
664static struct file *do_open(struct ipc_namespace *ipc_ns,
665				struct dentry *dentry, int oflag)
666{
667	int ret;
668	const struct cred *cred = current_cred();
669
670	static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
671						  MAY_READ | MAY_WRITE };
672
673	if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
674		ret = -EINVAL;
675		goto err;
676	}
677
678	if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
679		ret = -EACCES;
680		goto err;
681	}
682
683	return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
684
685err:
686	dput(dentry);
687	mntput(ipc_ns->mq_mnt);
688	return ERR_PTR(ret);
689}
690
691SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
692		struct mq_attr __user *, u_attr)
693{
694	struct dentry *dentry;
695	struct file *filp;
696	char *name;
697	struct mq_attr attr;
698	int fd, error;
699	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
700
701	if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
702		return -EFAULT;
703
704	audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
705
706	if (IS_ERR(name = getname(u_name)))
707		return PTR_ERR(name);
708
709	fd = get_unused_fd_flags(O_CLOEXEC);
710	if (fd < 0)
711		goto out_putname;
712
713	mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
714	dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
715	if (IS_ERR(dentry)) {
716		error = PTR_ERR(dentry);
717		goto out_putfd;
718	}
719	mntget(ipc_ns->mq_mnt);
720
721	if (oflag & O_CREAT) {
722		if (dentry->d_inode) {	/* entry already exists */
723			audit_inode(name, dentry);
724			if (oflag & O_EXCL) {
725				error = -EEXIST;
726				goto out;
727			}
728			filp = do_open(ipc_ns, dentry, oflag);
729		} else {
730			filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
731						dentry, oflag, mode,
732						u_attr ? &attr : NULL);
733		}
734	} else {
735		if (!dentry->d_inode) {
736			error = -ENOENT;
737			goto out;
738		}
739		audit_inode(name, dentry);
740		filp = do_open(ipc_ns, dentry, oflag);
741	}
742
743	if (IS_ERR(filp)) {
744		error = PTR_ERR(filp);
745		goto out_putfd;
746	}
747
748	fd_install(fd, filp);
749	goto out_upsem;
750
751out:
752	dput(dentry);
753	mntput(ipc_ns->mq_mnt);
754out_putfd:
755	put_unused_fd(fd);
756	fd = error;
757out_upsem:
758	mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
759out_putname:
760	putname(name);
761	return fd;
762}
763
764SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
765{
766	int err;
767	char *name;
768	struct dentry *dentry;
769	struct inode *inode = NULL;
770	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
771
772	name = getname(u_name);
773	if (IS_ERR(name))
774		return PTR_ERR(name);
775
776	mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
777			I_MUTEX_PARENT);
778	dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
779	if (IS_ERR(dentry)) {
780		err = PTR_ERR(dentry);
781		goto out_unlock;
782	}
783
784	if (!dentry->d_inode) {
785		err = -ENOENT;
786		goto out_err;
787	}
788
789	inode = dentry->d_inode;
790	if (inode)
791		ihold(inode);
792	err = mnt_want_write(ipc_ns->mq_mnt);
793	if (err)
794		goto out_err;
795	err = vfs_unlink(dentry->d_parent->d_inode, dentry);
796	mnt_drop_write(ipc_ns->mq_mnt);
797out_err:
798	dput(dentry);
799
800out_unlock:
801	mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
802	putname(name);
803	if (inode)
804		iput(inode);
805
806	return err;
807}
808
809/* Pipelined send and receive functions.
810 *
811 * If a receiver finds no waiting message, then it registers itself in the
812 * list of waiting receivers. A sender checks that list before adding the new
813 * message into the message array. If there is a waiting receiver, then it
814 * bypasses the message array and directly hands the message over to the
815 * receiver.
816 * The receiver accepts the message and returns without grabbing the queue
817 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
818 * are necessary. The same algorithm is used for sysv semaphores, see
819 * ipc/sem.c for more details.
820 *
821 * The same algorithm is used for senders.
822 */
823
824/* pipelined_send() - send a message directly to the task waiting in
825 * sys_mq_timedreceive() (without inserting message into a queue).
826 */
827static inline void pipelined_send(struct mqueue_inode_info *info,
828				  struct msg_msg *message,
829				  struct ext_wait_queue *receiver)
830{
831	receiver->msg = message;
832	list_del(&receiver->list);
833	receiver->state = STATE_PENDING;
834	wake_up_process(receiver->task);
835	smp_wmb();
836	receiver->state = STATE_READY;
837}
838
839/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
840 * gets its message and put to the queue (we have one free place for sure). */
841static inline void pipelined_receive(struct mqueue_inode_info *info)
842{
843	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
844
845	if (!sender) {
846		/* for poll */
847		wake_up_interruptible(&info->wait_q);
848		return;
849	}
850	msg_insert(sender->msg, info);
851	list_del(&sender->list);
852	sender->state = STATE_PENDING;
853	wake_up_process(sender->task);
854	smp_wmb();
855	sender->state = STATE_READY;
856}
857
858SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
859		size_t, msg_len, unsigned int, msg_prio,
860		const struct timespec __user *, u_abs_timeout)
861{
862	struct file *filp;
863	struct inode *inode;
864	struct ext_wait_queue wait;
865	struct ext_wait_queue *receiver;
866	struct msg_msg *msg_ptr;
867	struct mqueue_inode_info *info;
868	ktime_t expires, *timeout = NULL;
869	struct timespec ts;
870	int ret;
871
872	if (u_abs_timeout) {
873		int res = prepare_timeout(u_abs_timeout, &expires, &ts);
874		if (res)
875			return res;
876		timeout = &expires;
877	}
878
879	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
880		return -EINVAL;
881
882	audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
883
884	filp = fget(mqdes);
885	if (unlikely(!filp)) {
886		ret = -EBADF;
887		goto out;
888	}
889
890	inode = filp->f_path.dentry->d_inode;
891	if (unlikely(filp->f_op != &mqueue_file_operations)) {
892		ret = -EBADF;
893		goto out_fput;
894	}
895	info = MQUEUE_I(inode);
896	audit_inode(NULL, filp->f_path.dentry);
897
898	if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
899		ret = -EBADF;
900		goto out_fput;
901	}
902
903	if (unlikely(msg_len > info->attr.mq_msgsize)) {
904		ret = -EMSGSIZE;
905		goto out_fput;
906	}
907
908	/* First try to allocate memory, before doing anything with
909	 * existing queues. */
910	msg_ptr = load_msg(u_msg_ptr, msg_len);
911	if (IS_ERR(msg_ptr)) {
912		ret = PTR_ERR(msg_ptr);
913		goto out_fput;
914	}
915	msg_ptr->m_ts = msg_len;
916	msg_ptr->m_type = msg_prio;
917
918	spin_lock(&info->lock);
919
920	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
921		if (filp->f_flags & O_NONBLOCK) {
922			spin_unlock(&info->lock);
923			ret = -EAGAIN;
924		} else {
925			wait.task = current;
926			wait.msg = (void *) msg_ptr;
927			wait.state = STATE_NONE;
928			ret = wq_sleep(info, SEND, timeout, &wait);
929		}
930		if (ret < 0)
931			free_msg(msg_ptr);
932	} else {
933		receiver = wq_get_first_waiter(info, RECV);
934		if (receiver) {
935			pipelined_send(info, msg_ptr, receiver);
936		} else {
937			/* adds message to the queue */
938			msg_insert(msg_ptr, info);
939			__do_notify(info);
940		}
941		inode->i_atime = inode->i_mtime = inode->i_ctime =
942				CURRENT_TIME;
943		spin_unlock(&info->lock);
944		ret = 0;
945	}
946out_fput:
947	fput(filp);
948out:
949	return ret;
950}
951
952SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
953		size_t, msg_len, unsigned int __user *, u_msg_prio,
954		const struct timespec __user *, u_abs_timeout)
955{
956	ssize_t ret;
957	struct msg_msg *msg_ptr;
958	struct file *filp;
959	struct inode *inode;
960	struct mqueue_inode_info *info;
961	struct ext_wait_queue wait;
962	ktime_t expires, *timeout = NULL;
963	struct timespec ts;
964
965	if (u_abs_timeout) {
966		int res = prepare_timeout(u_abs_timeout, &expires, &ts);
967		if (res)
968			return res;
969		timeout = &expires;
970	}
971
972	audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
973
974	filp = fget(mqdes);
975	if (unlikely(!filp)) {
976		ret = -EBADF;
977		goto out;
978	}
979
980	inode = filp->f_path.dentry->d_inode;
981	if (unlikely(filp->f_op != &mqueue_file_operations)) {
982		ret = -EBADF;
983		goto out_fput;
984	}
985	info = MQUEUE_I(inode);
986	audit_inode(NULL, filp->f_path.dentry);
987
988	if (unlikely(!(filp->f_mode & FMODE_READ))) {
989		ret = -EBADF;
990		goto out_fput;
991	}
992
993	/* checks if buffer is big enough */
994	if (unlikely(msg_len < info->attr.mq_msgsize)) {
995		ret = -EMSGSIZE;
996		goto out_fput;
997	}
998
999	spin_lock(&info->lock);
1000	if (info->attr.mq_curmsgs == 0) {
1001		if (filp->f_flags & O_NONBLOCK) {
1002			spin_unlock(&info->lock);
1003			ret = -EAGAIN;
1004		} else {
1005			wait.task = current;
1006			wait.state = STATE_NONE;
1007			ret = wq_sleep(info, RECV, timeout, &wait);
1008			msg_ptr = wait.msg;
1009		}
1010	} else {
1011		msg_ptr = msg_get(info);
1012
1013		inode->i_atime = inode->i_mtime = inode->i_ctime =
1014				CURRENT_TIME;
1015
1016		/* There is now free space in queue. */
1017		pipelined_receive(info);
1018		spin_unlock(&info->lock);
1019		ret = 0;
1020	}
1021	if (ret == 0) {
1022		ret = msg_ptr->m_ts;
1023
1024		if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1025			store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1026			ret = -EFAULT;
1027		}
1028		free_msg(msg_ptr);
1029	}
1030out_fput:
1031	fput(filp);
1032out:
1033	return ret;
1034}
1035
1036/*
1037 * Notes: the case when user wants us to deregister (with NULL as pointer)
1038 * and he isn't currently owner of notification, will be silently discarded.
1039 * It isn't explicitly defined in the POSIX.
1040 */
1041SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1042		const struct sigevent __user *, u_notification)
1043{
1044	int ret;
1045	struct file *filp;
1046	struct sock *sock;
1047	struct inode *inode;
1048	struct sigevent notification;
1049	struct mqueue_inode_info *info;
1050	struct sk_buff *nc;
1051
1052	if (u_notification) {
1053		if (copy_from_user(&notification, u_notification,
1054					sizeof(struct sigevent)))
1055			return -EFAULT;
1056	}
1057
1058	audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1059
1060	nc = NULL;
1061	sock = NULL;
1062	if (u_notification != NULL) {
1063		if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1064			     notification.sigev_notify != SIGEV_SIGNAL &&
1065			     notification.sigev_notify != SIGEV_THREAD))
1066			return -EINVAL;
1067		if (notification.sigev_notify == SIGEV_SIGNAL &&
1068			!valid_signal(notification.sigev_signo)) {
1069			return -EINVAL;
1070		}
1071		if (notification.sigev_notify == SIGEV_THREAD) {
1072			long timeo;
1073
1074			/* create the notify skb */
1075			nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1076			if (!nc) {
1077				ret = -ENOMEM;
1078				goto out;
1079			}
1080			if (copy_from_user(nc->data,
1081					notification.sigev_value.sival_ptr,
1082					NOTIFY_COOKIE_LEN)) {
1083				ret = -EFAULT;
1084				goto out;
1085			}
1086
1087			/* TODO: add a header? */
1088			skb_put(nc, NOTIFY_COOKIE_LEN);
1089			/* and attach it to the socket */
1090retry:
1091			filp = fget(notification.sigev_signo);
1092			if (!filp) {
1093				ret = -EBADF;
1094				goto out;
1095			}
1096			sock = netlink_getsockbyfilp(filp);
1097			fput(filp);
1098			if (IS_ERR(sock)) {
1099				ret = PTR_ERR(sock);
1100				sock = NULL;
1101				goto out;
1102			}
1103
1104			timeo = MAX_SCHEDULE_TIMEOUT;
1105			ret = netlink_attachskb(sock, nc, &timeo, NULL);
1106			if (ret == 1)
1107				goto retry;
1108			if (ret) {
1109				sock = NULL;
1110				nc = NULL;
1111				goto out;
1112			}
1113		}
1114	}
1115
1116	filp = fget(mqdes);
1117	if (!filp) {
1118		ret = -EBADF;
1119		goto out;
1120	}
1121
1122	inode = filp->f_path.dentry->d_inode;
1123	if (unlikely(filp->f_op != &mqueue_file_operations)) {
1124		ret = -EBADF;
1125		goto out_fput;
1126	}
1127	info = MQUEUE_I(inode);
1128
1129	ret = 0;
1130	spin_lock(&info->lock);
1131	if (u_notification == NULL) {
1132		if (info->notify_owner == task_tgid(current)) {
1133			remove_notification(info);
1134			inode->i_atime = inode->i_ctime = CURRENT_TIME;
1135		}
1136	} else if (info->notify_owner != NULL) {
1137		ret = -EBUSY;
1138	} else {
1139		switch (notification.sigev_notify) {
1140		case SIGEV_NONE:
1141			info->notify.sigev_notify = SIGEV_NONE;
1142			break;
1143		case SIGEV_THREAD:
1144			info->notify_sock = sock;
1145			info->notify_cookie = nc;
1146			sock = NULL;
1147			nc = NULL;
1148			info->notify.sigev_notify = SIGEV_THREAD;
1149			break;
1150		case SIGEV_SIGNAL:
1151			info->notify.sigev_signo = notification.sigev_signo;
1152			info->notify.sigev_value = notification.sigev_value;
1153			info->notify.sigev_notify = SIGEV_SIGNAL;
1154			break;
1155		}
1156
1157		info->notify_owner = get_pid(task_tgid(current));
1158		info->notify_user_ns = get_user_ns(current_user_ns());
1159		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1160	}
1161	spin_unlock(&info->lock);
1162out_fput:
1163	fput(filp);
1164out:
1165	if (sock) {
1166		netlink_detachskb(sock, nc);
1167	} else if (nc) {
1168		dev_kfree_skb(nc);
1169	}
1170	return ret;
1171}
1172
1173SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1174		const struct mq_attr __user *, u_mqstat,
1175		struct mq_attr __user *, u_omqstat)
1176{
1177	int ret;
1178	struct mq_attr mqstat, omqstat;
1179	struct file *filp;
1180	struct inode *inode;
1181	struct mqueue_inode_info *info;
1182
1183	if (u_mqstat != NULL) {
1184		if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1185			return -EFAULT;
1186		if (mqstat.mq_flags & (~O_NONBLOCK))
1187			return -EINVAL;
1188	}
1189
1190	filp = fget(mqdes);
1191	if (!filp) {
1192		ret = -EBADF;
1193		goto out;
1194	}
1195
1196	inode = filp->f_path.dentry->d_inode;
1197	if (unlikely(filp->f_op != &mqueue_file_operations)) {
1198		ret = -EBADF;
1199		goto out_fput;
1200	}
1201	info = MQUEUE_I(inode);
1202
1203	spin_lock(&info->lock);
1204
1205	omqstat = info->attr;
1206	omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1207	if (u_mqstat) {
1208		audit_mq_getsetattr(mqdes, &mqstat);
1209		spin_lock(&filp->f_lock);
1210		if (mqstat.mq_flags & O_NONBLOCK)
1211			filp->f_flags |= O_NONBLOCK;
1212		else
1213			filp->f_flags &= ~O_NONBLOCK;
1214		spin_unlock(&filp->f_lock);
1215
1216		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1217	}
1218
1219	spin_unlock(&info->lock);
1220
1221	ret = 0;
1222	if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1223						sizeof(struct mq_attr)))
1224		ret = -EFAULT;
1225
1226out_fput:
1227	fput(filp);
1228out:
1229	return ret;
1230}
1231
1232static const struct inode_operations mqueue_dir_inode_operations = {
1233	.lookup = simple_lookup,
1234	.create = mqueue_create,
1235	.unlink = mqueue_unlink,
1236};
1237
1238static const struct file_operations mqueue_file_operations = {
1239	.flush = mqueue_flush_file,
1240	.poll = mqueue_poll_file,
1241	.read = mqueue_read_file,
1242	.llseek = default_llseek,
1243};
1244
1245static const struct super_operations mqueue_super_ops = {
1246	.alloc_inode = mqueue_alloc_inode,
1247	.destroy_inode = mqueue_destroy_inode,
1248	.evict_inode = mqueue_evict_inode,
1249	.statfs = simple_statfs,
1250};
1251
1252static struct file_system_type mqueue_fs_type = {
1253	.name = "mqueue",
1254	.mount = mqueue_mount,
1255	.kill_sb = kill_litter_super,
1256};
1257
1258int mq_init_ns(struct ipc_namespace *ns)
1259{
1260	ns->mq_queues_count  = 0;
1261	ns->mq_queues_max    = DFLT_QUEUESMAX;
1262	ns->mq_msg_max       = DFLT_MSGMAX;
1263	ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1264
1265	ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1266	if (IS_ERR(ns->mq_mnt)) {
1267		int err = PTR_ERR(ns->mq_mnt);
1268		ns->mq_mnt = NULL;
1269		return err;
1270	}
1271	return 0;
1272}
1273
1274void mq_clear_sbinfo(struct ipc_namespace *ns)
1275{
1276	ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1277}
1278
1279void mq_put_mnt(struct ipc_namespace *ns)
1280{
1281	kern_unmount(ns->mq_mnt);
1282}
1283
1284static int __init init_mqueue_fs(void)
1285{
1286	int error;
1287
1288	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1289				sizeof(struct mqueue_inode_info), 0,
1290				SLAB_HWCACHE_ALIGN, init_once);
1291	if (mqueue_inode_cachep == NULL)
1292		return -ENOMEM;
1293
1294	/* ignore failures - they are not fatal */
1295	mq_sysctl_table = mq_register_sysctl_table();
1296
1297	error = register_filesystem(&mqueue_fs_type);
1298	if (error)
1299		goto out_sysctl;
1300
1301	spin_lock_init(&mq_lock);
1302
1303	error = mq_init_ns(&init_ipc_ns);
1304	if (error)
1305		goto out_filesystem;
1306
1307	return 0;
1308
1309out_filesystem:
1310	unregister_filesystem(&mqueue_fs_type);
1311out_sysctl:
1312	if (mq_sysctl_table)
1313		unregister_sysctl_table(mq_sysctl_table);
1314	kmem_cache_destroy(mqueue_inode_cachep);
1315	return error;
1316}
1317
1318__initcall(init_mqueue_fs);
1319