mqueue.c revision 85fe4025
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/slab.h>
36
37#include <net/sock.h>
38#include "util.h"
39
40#define MQUEUE_MAGIC	0x19800202
41#define DIRENT_SIZE	20
42#define FILENT_SIZE	80
43
44#define SEND		0
45#define RECV		1
46
47#define STATE_NONE	0
48#define STATE_PENDING	1
49#define STATE_READY	2
50
51struct ext_wait_queue {		/* queue of sleeping tasks */
52	struct task_struct *task;
53	struct list_head list;
54	struct msg_msg *msg;	/* ptr of loaded message */
55	int state;		/* one of STATE_* values */
56};
57
58struct mqueue_inode_info {
59	spinlock_t lock;
60	struct inode vfs_inode;
61	wait_queue_head_t wait_q;
62
63	struct msg_msg **messages;
64	struct mq_attr attr;
65
66	struct sigevent notify;
67	struct pid* notify_owner;
68	struct user_struct *user;	/* user who created, for accounting */
69	struct sock *notify_sock;
70	struct sk_buff *notify_cookie;
71
72	/* for tasks waiting for free space and messages, respectively */
73	struct ext_wait_queue e_wait_q[2];
74
75	unsigned long qsize; /* size of queue in memory (sum of all msgs) */
76};
77
78static const struct inode_operations mqueue_dir_inode_operations;
79static const struct file_operations mqueue_file_operations;
80static const struct super_operations mqueue_super_ops;
81static void remove_notification(struct mqueue_inode_info *info);
82
83static struct kmem_cache *mqueue_inode_cachep;
84
85static struct ctl_table_header * mq_sysctl_table;
86
87static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
88{
89	return container_of(inode, struct mqueue_inode_info, vfs_inode);
90}
91
92/*
93 * This routine should be called with the mq_lock held.
94 */
95static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
96{
97	return get_ipc_ns(inode->i_sb->s_fs_info);
98}
99
100static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
101{
102	struct ipc_namespace *ns;
103
104	spin_lock(&mq_lock);
105	ns = __get_ns_from_inode(inode);
106	spin_unlock(&mq_lock);
107	return ns;
108}
109
110static struct inode *mqueue_get_inode(struct super_block *sb,
111		struct ipc_namespace *ipc_ns, int mode,
112		struct mq_attr *attr)
113{
114	struct user_struct *u = current_user();
115	struct inode *inode;
116
117	inode = new_inode(sb);
118	if (inode) {
119		inode->i_ino = get_next_ino();
120		inode->i_mode = mode;
121		inode->i_uid = current_fsuid();
122		inode->i_gid = current_fsgid();
123		inode->i_mtime = inode->i_ctime = inode->i_atime =
124				CURRENT_TIME;
125
126		if (S_ISREG(mode)) {
127			struct mqueue_inode_info *info;
128			struct task_struct *p = current;
129			unsigned long mq_bytes, mq_msg_tblsz;
130
131			inode->i_fop = &mqueue_file_operations;
132			inode->i_size = FILENT_SIZE;
133			/* mqueue specific info */
134			info = MQUEUE_I(inode);
135			spin_lock_init(&info->lock);
136			init_waitqueue_head(&info->wait_q);
137			INIT_LIST_HEAD(&info->e_wait_q[0].list);
138			INIT_LIST_HEAD(&info->e_wait_q[1].list);
139			info->notify_owner = NULL;
140			info->qsize = 0;
141			info->user = NULL;	/* set when all is ok */
142			memset(&info->attr, 0, sizeof(info->attr));
143			info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
144			info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
145			if (attr) {
146				info->attr.mq_maxmsg = attr->mq_maxmsg;
147				info->attr.mq_msgsize = attr->mq_msgsize;
148			}
149			mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
150			info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
151			if (!info->messages)
152				goto out_inode;
153
154			mq_bytes = (mq_msg_tblsz +
155				(info->attr.mq_maxmsg * info->attr.mq_msgsize));
156
157			spin_lock(&mq_lock);
158			if (u->mq_bytes + mq_bytes < u->mq_bytes ||
159		 	    u->mq_bytes + mq_bytes >
160			    task_rlimit(p, RLIMIT_MSGQUEUE)) {
161				spin_unlock(&mq_lock);
162				/* mqueue_evict_inode() releases info->messages */
163				goto out_inode;
164			}
165			u->mq_bytes += mq_bytes;
166			spin_unlock(&mq_lock);
167
168			/* all is ok */
169			info->user = get_uid(u);
170		} else if (S_ISDIR(mode)) {
171			inc_nlink(inode);
172			/* Some things misbehave if size == 0 on a directory */
173			inode->i_size = 2 * DIRENT_SIZE;
174			inode->i_op = &mqueue_dir_inode_operations;
175			inode->i_fop = &simple_dir_operations;
176		}
177	}
178	return inode;
179out_inode:
180	iput(inode);
181	return NULL;
182}
183
184static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
185{
186	struct inode *inode;
187	struct ipc_namespace *ns = data;
188	int error;
189
190	sb->s_blocksize = PAGE_CACHE_SIZE;
191	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
192	sb->s_magic = MQUEUE_MAGIC;
193	sb->s_op = &mqueue_super_ops;
194
195	inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO,
196				NULL);
197	if (!inode) {
198		error = -ENOMEM;
199		goto out;
200	}
201
202	sb->s_root = d_alloc_root(inode);
203	if (!sb->s_root) {
204		iput(inode);
205		error = -ENOMEM;
206		goto out;
207	}
208	error = 0;
209
210out:
211	return error;
212}
213
214static int mqueue_get_sb(struct file_system_type *fs_type,
215			 int flags, const char *dev_name,
216			 void *data, struct vfsmount *mnt)
217{
218	if (!(flags & MS_KERNMOUNT))
219		data = current->nsproxy->ipc_ns;
220	return get_sb_ns(fs_type, flags, data, mqueue_fill_super, mnt);
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_destroy_inode(struct inode *inode)
241{
242	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
243}
244
245static void mqueue_evict_inode(struct inode *inode)
246{
247	struct mqueue_inode_info *info;
248	struct user_struct *user;
249	unsigned long mq_bytes;
250	int i;
251	struct ipc_namespace *ipc_ns;
252
253	end_writeback(inode);
254
255	if (S_ISDIR(inode->i_mode))
256		return;
257
258	ipc_ns = get_ns_from_inode(inode);
259	info = MQUEUE_I(inode);
260	spin_lock(&info->lock);
261	for (i = 0; i < info->attr.mq_curmsgs; i++)
262		free_msg(info->messages[i]);
263	kfree(info->messages);
264	spin_unlock(&info->lock);
265
266	/* Total amount of bytes accounted for the mqueue */
267	mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
268	    + info->attr.mq_msgsize);
269	user = info->user;
270	if (user) {
271		spin_lock(&mq_lock);
272		user->mq_bytes -= mq_bytes;
273		/*
274		 * get_ns_from_inode() ensures that the
275		 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
276		 * to which we now hold a reference, or it is NULL.
277		 * We can't put it here under mq_lock, though.
278		 */
279		if (ipc_ns)
280			ipc_ns->mq_queues_count--;
281		spin_unlock(&mq_lock);
282		free_uid(user);
283	}
284	if (ipc_ns)
285		put_ipc_ns(ipc_ns);
286}
287
288static int mqueue_create(struct inode *dir, struct dentry *dentry,
289				int mode, struct nameidata *nd)
290{
291	struct inode *inode;
292	struct mq_attr *attr = dentry->d_fsdata;
293	int error;
294	struct ipc_namespace *ipc_ns;
295
296	spin_lock(&mq_lock);
297	ipc_ns = __get_ns_from_inode(dir);
298	if (!ipc_ns) {
299		error = -EACCES;
300		goto out_unlock;
301	}
302	if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
303			!capable(CAP_SYS_RESOURCE)) {
304		error = -ENOSPC;
305		goto out_unlock;
306	}
307	ipc_ns->mq_queues_count++;
308	spin_unlock(&mq_lock);
309
310	inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
311	if (!inode) {
312		error = -ENOMEM;
313		spin_lock(&mq_lock);
314		ipc_ns->mq_queues_count--;
315		goto out_unlock;
316	}
317
318	put_ipc_ns(ipc_ns);
319	dir->i_size += DIRENT_SIZE;
320	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
321
322	d_instantiate(dentry, inode);
323	dget(dentry);
324	return 0;
325out_unlock:
326	spin_unlock(&mq_lock);
327	if (ipc_ns)
328		put_ipc_ns(ipc_ns);
329	return error;
330}
331
332static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
333{
334  	struct inode *inode = dentry->d_inode;
335
336	dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
337	dir->i_size -= DIRENT_SIZE;
338  	drop_nlink(inode);
339  	dput(dentry);
340  	return 0;
341}
342
343/*
344*	This is routine for system read from queue file.
345*	To avoid mess with doing here some sort of mq_receive we allow
346*	to read only queue size & notification info (the only values
347*	that are interesting from user point of view and aren't accessible
348*	through std routines)
349*/
350static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
351				size_t count, loff_t *off)
352{
353	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
354	char buffer[FILENT_SIZE];
355	ssize_t ret;
356
357	spin_lock(&info->lock);
358	snprintf(buffer, sizeof(buffer),
359			"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
360			info->qsize,
361			info->notify_owner ? info->notify.sigev_notify : 0,
362			(info->notify_owner &&
363			 info->notify.sigev_notify == SIGEV_SIGNAL) ?
364				info->notify.sigev_signo : 0,
365			pid_vnr(info->notify_owner));
366	spin_unlock(&info->lock);
367	buffer[sizeof(buffer)-1] = '\0';
368
369	ret = simple_read_from_buffer(u_data, count, off, buffer,
370				strlen(buffer));
371	if (ret <= 0)
372		return ret;
373
374	filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
375	return ret;
376}
377
378static int mqueue_flush_file(struct file *filp, fl_owner_t id)
379{
380	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
381
382	spin_lock(&info->lock);
383	if (task_tgid(current) == info->notify_owner)
384		remove_notification(info);
385
386	spin_unlock(&info->lock);
387	return 0;
388}
389
390static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
391{
392	struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
393	int retval = 0;
394
395	poll_wait(filp, &info->wait_q, poll_tab);
396
397	spin_lock(&info->lock);
398	if (info->attr.mq_curmsgs)
399		retval = POLLIN | POLLRDNORM;
400
401	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
402		retval |= POLLOUT | POLLWRNORM;
403	spin_unlock(&info->lock);
404
405	return retval;
406}
407
408/* Adds current to info->e_wait_q[sr] before element with smaller prio */
409static void wq_add(struct mqueue_inode_info *info, int sr,
410			struct ext_wait_queue *ewp)
411{
412	struct ext_wait_queue *walk;
413
414	ewp->task = current;
415
416	list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
417		if (walk->task->static_prio <= current->static_prio) {
418			list_add_tail(&ewp->list, &walk->list);
419			return;
420		}
421	}
422	list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
423}
424
425/*
426 * Puts current task to sleep. Caller must hold queue lock. After return
427 * lock isn't held.
428 * sr: SEND or RECV
429 */
430static int wq_sleep(struct mqueue_inode_info *info, int sr,
431		    ktime_t *timeout, struct ext_wait_queue *ewp)
432{
433	int retval;
434	signed long time;
435
436	wq_add(info, sr, ewp);
437
438	for (;;) {
439		set_current_state(TASK_INTERRUPTIBLE);
440
441		spin_unlock(&info->lock);
442		time = schedule_hrtimeout_range_clock(timeout,
443		    HRTIMER_MODE_ABS, 0, CLOCK_REALTIME);
444
445		while (ewp->state == STATE_PENDING)
446			cpu_relax();
447
448		if (ewp->state == STATE_READY) {
449			retval = 0;
450			goto out;
451		}
452		spin_lock(&info->lock);
453		if (ewp->state == STATE_READY) {
454			retval = 0;
455			goto out_unlock;
456		}
457		if (signal_pending(current)) {
458			retval = -ERESTARTSYS;
459			break;
460		}
461		if (time == 0) {
462			retval = -ETIMEDOUT;
463			break;
464		}
465	}
466	list_del(&ewp->list);
467out_unlock:
468	spin_unlock(&info->lock);
469out:
470	return retval;
471}
472
473/*
474 * Returns waiting task that should be serviced first or NULL if none exists
475 */
476static struct ext_wait_queue *wq_get_first_waiter(
477		struct mqueue_inode_info *info, int sr)
478{
479	struct list_head *ptr;
480
481	ptr = info->e_wait_q[sr].list.prev;
482	if (ptr == &info->e_wait_q[sr].list)
483		return NULL;
484	return list_entry(ptr, struct ext_wait_queue, list);
485}
486
487/* Auxiliary functions to manipulate messages' list */
488static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
489{
490	int k;
491
492	k = info->attr.mq_curmsgs - 1;
493	while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
494		info->messages[k + 1] = info->messages[k];
495		k--;
496	}
497	info->attr.mq_curmsgs++;
498	info->qsize += ptr->m_ts;
499	info->messages[k + 1] = ptr;
500}
501
502static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
503{
504	info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
505	return info->messages[info->attr.mq_curmsgs];
506}
507
508static inline void set_cookie(struct sk_buff *skb, char code)
509{
510	((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
511}
512
513/*
514 * The next function is only to split too long sys_mq_timedsend
515 */
516static void __do_notify(struct mqueue_inode_info *info)
517{
518	/* notification
519	 * invoked when there is registered process and there isn't process
520	 * waiting synchronously for message AND state of queue changed from
521	 * empty to not empty. Here we are sure that no one is waiting
522	 * synchronously. */
523	if (info->notify_owner &&
524	    info->attr.mq_curmsgs == 1) {
525		struct siginfo sig_i;
526		switch (info->notify.sigev_notify) {
527		case SIGEV_NONE:
528			break;
529		case SIGEV_SIGNAL:
530			/* sends signal */
531
532			sig_i.si_signo = info->notify.sigev_signo;
533			sig_i.si_errno = 0;
534			sig_i.si_code = SI_MESGQ;
535			sig_i.si_value = info->notify.sigev_value;
536			sig_i.si_pid = task_tgid_nr_ns(current,
537						ns_of_pid(info->notify_owner));
538			sig_i.si_uid = current_uid();
539
540			kill_pid_info(info->notify.sigev_signo,
541				      &sig_i, info->notify_owner);
542			break;
543		case SIGEV_THREAD:
544			set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
545			netlink_sendskb(info->notify_sock, info->notify_cookie);
546			break;
547		}
548		/* after notification unregisters process */
549		put_pid(info->notify_owner);
550		info->notify_owner = NULL;
551	}
552	wake_up(&info->wait_q);
553}
554
555static int prepare_timeout(const struct timespec __user *u_abs_timeout,
556			   ktime_t *expires, struct timespec *ts)
557{
558	if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
559		return -EFAULT;
560	if (!timespec_valid(ts))
561		return -EINVAL;
562
563	*expires = timespec_to_ktime(*ts);
564	return 0;
565}
566
567static void remove_notification(struct mqueue_inode_info *info)
568{
569	if (info->notify_owner != NULL &&
570	    info->notify.sigev_notify == SIGEV_THREAD) {
571		set_cookie(info->notify_cookie, NOTIFY_REMOVED);
572		netlink_sendskb(info->notify_sock, info->notify_cookie);
573	}
574	put_pid(info->notify_owner);
575	info->notify_owner = NULL;
576}
577
578static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
579{
580	if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
581		return 0;
582	if (capable(CAP_SYS_RESOURCE)) {
583		if (attr->mq_maxmsg > HARD_MSGMAX)
584			return 0;
585	} else {
586		if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
587				attr->mq_msgsize > ipc_ns->mq_msgsize_max)
588			return 0;
589	}
590	/* check for overflow */
591	if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
592		return 0;
593	if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
594	    + sizeof (struct msg_msg *))) <
595	    (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
596		return 0;
597	return 1;
598}
599
600/*
601 * Invoked when creating a new queue via sys_mq_open
602 */
603static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
604			struct dentry *dentry, int oflag, mode_t mode,
605			struct mq_attr *attr)
606{
607	const struct cred *cred = current_cred();
608	struct file *result;
609	int ret;
610
611	if (attr) {
612		if (!mq_attr_ok(ipc_ns, attr)) {
613			ret = -EINVAL;
614			goto out;
615		}
616		/* store for use during create */
617		dentry->d_fsdata = attr;
618	}
619
620	mode &= ~current_umask();
621	ret = mnt_want_write(ipc_ns->mq_mnt);
622	if (ret)
623		goto out;
624	ret = vfs_create(dir->d_inode, dentry, mode, NULL);
625	dentry->d_fsdata = NULL;
626	if (ret)
627		goto out_drop_write;
628
629	result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
630	/*
631	 * dentry_open() took a persistent mnt_want_write(),
632	 * so we can now drop this one.
633	 */
634	mnt_drop_write(ipc_ns->mq_mnt);
635	return result;
636
637out_drop_write:
638	mnt_drop_write(ipc_ns->mq_mnt);
639out:
640	dput(dentry);
641	mntput(ipc_ns->mq_mnt);
642	return ERR_PTR(ret);
643}
644
645/* Opens existing queue */
646static struct file *do_open(struct ipc_namespace *ipc_ns,
647				struct dentry *dentry, int oflag)
648{
649	int ret;
650	const struct cred *cred = current_cred();
651
652	static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
653						  MAY_READ | MAY_WRITE };
654
655	if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
656		ret = -EINVAL;
657		goto err;
658	}
659
660	if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
661		ret = -EACCES;
662		goto err;
663	}
664
665	return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
666
667err:
668	dput(dentry);
669	mntput(ipc_ns->mq_mnt);
670	return ERR_PTR(ret);
671}
672
673SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
674		struct mq_attr __user *, u_attr)
675{
676	struct dentry *dentry;
677	struct file *filp;
678	char *name;
679	struct mq_attr attr;
680	int fd, error;
681	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
682
683	if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
684		return -EFAULT;
685
686	audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
687
688	if (IS_ERR(name = getname(u_name)))
689		return PTR_ERR(name);
690
691	fd = get_unused_fd_flags(O_CLOEXEC);
692	if (fd < 0)
693		goto out_putname;
694
695	mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
696	dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
697	if (IS_ERR(dentry)) {
698		error = PTR_ERR(dentry);
699		goto out_putfd;
700	}
701	mntget(ipc_ns->mq_mnt);
702
703	if (oflag & O_CREAT) {
704		if (dentry->d_inode) {	/* entry already exists */
705			audit_inode(name, dentry);
706			if (oflag & O_EXCL) {
707				error = -EEXIST;
708				goto out;
709			}
710			filp = do_open(ipc_ns, dentry, oflag);
711		} else {
712			filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
713						dentry, oflag, mode,
714						u_attr ? &attr : NULL);
715		}
716	} else {
717		if (!dentry->d_inode) {
718			error = -ENOENT;
719			goto out;
720		}
721		audit_inode(name, dentry);
722		filp = do_open(ipc_ns, dentry, oflag);
723	}
724
725	if (IS_ERR(filp)) {
726		error = PTR_ERR(filp);
727		goto out_putfd;
728	}
729
730	fd_install(fd, filp);
731	goto out_upsem;
732
733out:
734	dput(dentry);
735	mntput(ipc_ns->mq_mnt);
736out_putfd:
737	put_unused_fd(fd);
738	fd = error;
739out_upsem:
740	mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
741out_putname:
742	putname(name);
743	return fd;
744}
745
746SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
747{
748	int err;
749	char *name;
750	struct dentry *dentry;
751	struct inode *inode = NULL;
752	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
753
754	name = getname(u_name);
755	if (IS_ERR(name))
756		return PTR_ERR(name);
757
758	mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
759			I_MUTEX_PARENT);
760	dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
761	if (IS_ERR(dentry)) {
762		err = PTR_ERR(dentry);
763		goto out_unlock;
764	}
765
766	if (!dentry->d_inode) {
767		err = -ENOENT;
768		goto out_err;
769	}
770
771	inode = dentry->d_inode;
772	if (inode)
773		ihold(inode);
774	err = mnt_want_write(ipc_ns->mq_mnt);
775	if (err)
776		goto out_err;
777	err = vfs_unlink(dentry->d_parent->d_inode, dentry);
778	mnt_drop_write(ipc_ns->mq_mnt);
779out_err:
780	dput(dentry);
781
782out_unlock:
783	mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
784	putname(name);
785	if (inode)
786		iput(inode);
787
788	return err;
789}
790
791/* Pipelined send and receive functions.
792 *
793 * If a receiver finds no waiting message, then it registers itself in the
794 * list of waiting receivers. A sender checks that list before adding the new
795 * message into the message array. If there is a waiting receiver, then it
796 * bypasses the message array and directly hands the message over to the
797 * receiver.
798 * The receiver accepts the message and returns without grabbing the queue
799 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
800 * are necessary. The same algorithm is used for sysv semaphores, see
801 * ipc/sem.c for more details.
802 *
803 * The same algorithm is used for senders.
804 */
805
806/* pipelined_send() - send a message directly to the task waiting in
807 * sys_mq_timedreceive() (without inserting message into a queue).
808 */
809static inline void pipelined_send(struct mqueue_inode_info *info,
810				  struct msg_msg *message,
811				  struct ext_wait_queue *receiver)
812{
813	receiver->msg = message;
814	list_del(&receiver->list);
815	receiver->state = STATE_PENDING;
816	wake_up_process(receiver->task);
817	smp_wmb();
818	receiver->state = STATE_READY;
819}
820
821/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
822 * gets its message and put to the queue (we have one free place for sure). */
823static inline void pipelined_receive(struct mqueue_inode_info *info)
824{
825	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
826
827	if (!sender) {
828		/* for poll */
829		wake_up_interruptible(&info->wait_q);
830		return;
831	}
832	msg_insert(sender->msg, info);
833	list_del(&sender->list);
834	sender->state = STATE_PENDING;
835	wake_up_process(sender->task);
836	smp_wmb();
837	sender->state = STATE_READY;
838}
839
840SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
841		size_t, msg_len, unsigned int, msg_prio,
842		const struct timespec __user *, u_abs_timeout)
843{
844	struct file *filp;
845	struct inode *inode;
846	struct ext_wait_queue wait;
847	struct ext_wait_queue *receiver;
848	struct msg_msg *msg_ptr;
849	struct mqueue_inode_info *info;
850	ktime_t expires, *timeout = NULL;
851	struct timespec ts;
852	int ret;
853
854	if (u_abs_timeout) {
855		int res = prepare_timeout(u_abs_timeout, &expires, &ts);
856		if (res)
857			return res;
858		timeout = &expires;
859	}
860
861	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
862		return -EINVAL;
863
864	audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
865
866	filp = fget(mqdes);
867	if (unlikely(!filp)) {
868		ret = -EBADF;
869		goto out;
870	}
871
872	inode = filp->f_path.dentry->d_inode;
873	if (unlikely(filp->f_op != &mqueue_file_operations)) {
874		ret = -EBADF;
875		goto out_fput;
876	}
877	info = MQUEUE_I(inode);
878	audit_inode(NULL, filp->f_path.dentry);
879
880	if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
881		ret = -EBADF;
882		goto out_fput;
883	}
884
885	if (unlikely(msg_len > info->attr.mq_msgsize)) {
886		ret = -EMSGSIZE;
887		goto out_fput;
888	}
889
890	/* First try to allocate memory, before doing anything with
891	 * existing queues. */
892	msg_ptr = load_msg(u_msg_ptr, msg_len);
893	if (IS_ERR(msg_ptr)) {
894		ret = PTR_ERR(msg_ptr);
895		goto out_fput;
896	}
897	msg_ptr->m_ts = msg_len;
898	msg_ptr->m_type = msg_prio;
899
900	spin_lock(&info->lock);
901
902	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
903		if (filp->f_flags & O_NONBLOCK) {
904			spin_unlock(&info->lock);
905			ret = -EAGAIN;
906		} else {
907			wait.task = current;
908			wait.msg = (void *) msg_ptr;
909			wait.state = STATE_NONE;
910			ret = wq_sleep(info, SEND, timeout, &wait);
911		}
912		if (ret < 0)
913			free_msg(msg_ptr);
914	} else {
915		receiver = wq_get_first_waiter(info, RECV);
916		if (receiver) {
917			pipelined_send(info, msg_ptr, receiver);
918		} else {
919			/* adds message to the queue */
920			msg_insert(msg_ptr, info);
921			__do_notify(info);
922		}
923		inode->i_atime = inode->i_mtime = inode->i_ctime =
924				CURRENT_TIME;
925		spin_unlock(&info->lock);
926		ret = 0;
927	}
928out_fput:
929	fput(filp);
930out:
931	return ret;
932}
933
934SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
935		size_t, msg_len, unsigned int __user *, u_msg_prio,
936		const struct timespec __user *, u_abs_timeout)
937{
938	ssize_t ret;
939	struct msg_msg *msg_ptr;
940	struct file *filp;
941	struct inode *inode;
942	struct mqueue_inode_info *info;
943	struct ext_wait_queue wait;
944	ktime_t expires, *timeout = NULL;
945	struct timespec ts;
946
947	if (u_abs_timeout) {
948		int res = prepare_timeout(u_abs_timeout, &expires, &ts);
949		if (res)
950			return res;
951		timeout = &expires;
952	}
953
954	audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
955
956	filp = fget(mqdes);
957	if (unlikely(!filp)) {
958		ret = -EBADF;
959		goto out;
960	}
961
962	inode = filp->f_path.dentry->d_inode;
963	if (unlikely(filp->f_op != &mqueue_file_operations)) {
964		ret = -EBADF;
965		goto out_fput;
966	}
967	info = MQUEUE_I(inode);
968	audit_inode(NULL, filp->f_path.dentry);
969
970	if (unlikely(!(filp->f_mode & FMODE_READ))) {
971		ret = -EBADF;
972		goto out_fput;
973	}
974
975	/* checks if buffer is big enough */
976	if (unlikely(msg_len < info->attr.mq_msgsize)) {
977		ret = -EMSGSIZE;
978		goto out_fput;
979	}
980
981	spin_lock(&info->lock);
982	if (info->attr.mq_curmsgs == 0) {
983		if (filp->f_flags & O_NONBLOCK) {
984			spin_unlock(&info->lock);
985			ret = -EAGAIN;
986		} else {
987			wait.task = current;
988			wait.state = STATE_NONE;
989			ret = wq_sleep(info, RECV, timeout, &wait);
990			msg_ptr = wait.msg;
991		}
992	} else {
993		msg_ptr = msg_get(info);
994
995		inode->i_atime = inode->i_mtime = inode->i_ctime =
996				CURRENT_TIME;
997
998		/* There is now free space in queue. */
999		pipelined_receive(info);
1000		spin_unlock(&info->lock);
1001		ret = 0;
1002	}
1003	if (ret == 0) {
1004		ret = msg_ptr->m_ts;
1005
1006		if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1007			store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1008			ret = -EFAULT;
1009		}
1010		free_msg(msg_ptr);
1011	}
1012out_fput:
1013	fput(filp);
1014out:
1015	return ret;
1016}
1017
1018/*
1019 * Notes: the case when user wants us to deregister (with NULL as pointer)
1020 * and he isn't currently owner of notification, will be silently discarded.
1021 * It isn't explicitly defined in the POSIX.
1022 */
1023SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1024		const struct sigevent __user *, u_notification)
1025{
1026	int ret;
1027	struct file *filp;
1028	struct sock *sock;
1029	struct inode *inode;
1030	struct sigevent notification;
1031	struct mqueue_inode_info *info;
1032	struct sk_buff *nc;
1033
1034	if (u_notification) {
1035		if (copy_from_user(&notification, u_notification,
1036					sizeof(struct sigevent)))
1037			return -EFAULT;
1038	}
1039
1040	audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1041
1042	nc = NULL;
1043	sock = NULL;
1044	if (u_notification != NULL) {
1045		if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1046			     notification.sigev_notify != SIGEV_SIGNAL &&
1047			     notification.sigev_notify != SIGEV_THREAD))
1048			return -EINVAL;
1049		if (notification.sigev_notify == SIGEV_SIGNAL &&
1050			!valid_signal(notification.sigev_signo)) {
1051			return -EINVAL;
1052		}
1053		if (notification.sigev_notify == SIGEV_THREAD) {
1054			long timeo;
1055
1056			/* create the notify skb */
1057			nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1058			if (!nc) {
1059				ret = -ENOMEM;
1060				goto out;
1061			}
1062			if (copy_from_user(nc->data,
1063					notification.sigev_value.sival_ptr,
1064					NOTIFY_COOKIE_LEN)) {
1065				ret = -EFAULT;
1066				goto out;
1067			}
1068
1069			/* TODO: add a header? */
1070			skb_put(nc, NOTIFY_COOKIE_LEN);
1071			/* and attach it to the socket */
1072retry:
1073			filp = fget(notification.sigev_signo);
1074			if (!filp) {
1075				ret = -EBADF;
1076				goto out;
1077			}
1078			sock = netlink_getsockbyfilp(filp);
1079			fput(filp);
1080			if (IS_ERR(sock)) {
1081				ret = PTR_ERR(sock);
1082				sock = NULL;
1083				goto out;
1084			}
1085
1086			timeo = MAX_SCHEDULE_TIMEOUT;
1087			ret = netlink_attachskb(sock, nc, &timeo, NULL);
1088			if (ret == 1)
1089				goto retry;
1090			if (ret) {
1091				sock = NULL;
1092				nc = NULL;
1093				goto out;
1094			}
1095		}
1096	}
1097
1098	filp = fget(mqdes);
1099	if (!filp) {
1100		ret = -EBADF;
1101		goto out;
1102	}
1103
1104	inode = filp->f_path.dentry->d_inode;
1105	if (unlikely(filp->f_op != &mqueue_file_operations)) {
1106		ret = -EBADF;
1107		goto out_fput;
1108	}
1109	info = MQUEUE_I(inode);
1110
1111	ret = 0;
1112	spin_lock(&info->lock);
1113	if (u_notification == NULL) {
1114		if (info->notify_owner == task_tgid(current)) {
1115			remove_notification(info);
1116			inode->i_atime = inode->i_ctime = CURRENT_TIME;
1117		}
1118	} else if (info->notify_owner != NULL) {
1119		ret = -EBUSY;
1120	} else {
1121		switch (notification.sigev_notify) {
1122		case SIGEV_NONE:
1123			info->notify.sigev_notify = SIGEV_NONE;
1124			break;
1125		case SIGEV_THREAD:
1126			info->notify_sock = sock;
1127			info->notify_cookie = nc;
1128			sock = NULL;
1129			nc = NULL;
1130			info->notify.sigev_notify = SIGEV_THREAD;
1131			break;
1132		case SIGEV_SIGNAL:
1133			info->notify.sigev_signo = notification.sigev_signo;
1134			info->notify.sigev_value = notification.sigev_value;
1135			info->notify.sigev_notify = SIGEV_SIGNAL;
1136			break;
1137		}
1138
1139		info->notify_owner = get_pid(task_tgid(current));
1140		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1141	}
1142	spin_unlock(&info->lock);
1143out_fput:
1144	fput(filp);
1145out:
1146	if (sock) {
1147		netlink_detachskb(sock, nc);
1148	} else if (nc) {
1149		dev_kfree_skb(nc);
1150	}
1151	return ret;
1152}
1153
1154SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1155		const struct mq_attr __user *, u_mqstat,
1156		struct mq_attr __user *, u_omqstat)
1157{
1158	int ret;
1159	struct mq_attr mqstat, omqstat;
1160	struct file *filp;
1161	struct inode *inode;
1162	struct mqueue_inode_info *info;
1163
1164	if (u_mqstat != NULL) {
1165		if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1166			return -EFAULT;
1167		if (mqstat.mq_flags & (~O_NONBLOCK))
1168			return -EINVAL;
1169	}
1170
1171	filp = fget(mqdes);
1172	if (!filp) {
1173		ret = -EBADF;
1174		goto out;
1175	}
1176
1177	inode = filp->f_path.dentry->d_inode;
1178	if (unlikely(filp->f_op != &mqueue_file_operations)) {
1179		ret = -EBADF;
1180		goto out_fput;
1181	}
1182	info = MQUEUE_I(inode);
1183
1184	spin_lock(&info->lock);
1185
1186	omqstat = info->attr;
1187	omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1188	if (u_mqstat) {
1189		audit_mq_getsetattr(mqdes, &mqstat);
1190		spin_lock(&filp->f_lock);
1191		if (mqstat.mq_flags & O_NONBLOCK)
1192			filp->f_flags |= O_NONBLOCK;
1193		else
1194			filp->f_flags &= ~O_NONBLOCK;
1195		spin_unlock(&filp->f_lock);
1196
1197		inode->i_atime = inode->i_ctime = CURRENT_TIME;
1198	}
1199
1200	spin_unlock(&info->lock);
1201
1202	ret = 0;
1203	if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1204						sizeof(struct mq_attr)))
1205		ret = -EFAULT;
1206
1207out_fput:
1208	fput(filp);
1209out:
1210	return ret;
1211}
1212
1213static const struct inode_operations mqueue_dir_inode_operations = {
1214	.lookup = simple_lookup,
1215	.create = mqueue_create,
1216	.unlink = mqueue_unlink,
1217};
1218
1219static const struct file_operations mqueue_file_operations = {
1220	.flush = mqueue_flush_file,
1221	.poll = mqueue_poll_file,
1222	.read = mqueue_read_file,
1223	.llseek = default_llseek,
1224};
1225
1226static const struct super_operations mqueue_super_ops = {
1227	.alloc_inode = mqueue_alloc_inode,
1228	.destroy_inode = mqueue_destroy_inode,
1229	.evict_inode = mqueue_evict_inode,
1230	.statfs = simple_statfs,
1231};
1232
1233static struct file_system_type mqueue_fs_type = {
1234	.name = "mqueue",
1235	.get_sb = mqueue_get_sb,
1236	.kill_sb = kill_litter_super,
1237};
1238
1239int mq_init_ns(struct ipc_namespace *ns)
1240{
1241	ns->mq_queues_count  = 0;
1242	ns->mq_queues_max    = DFLT_QUEUESMAX;
1243	ns->mq_msg_max       = DFLT_MSGMAX;
1244	ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1245
1246	ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1247	if (IS_ERR(ns->mq_mnt)) {
1248		int err = PTR_ERR(ns->mq_mnt);
1249		ns->mq_mnt = NULL;
1250		return err;
1251	}
1252	return 0;
1253}
1254
1255void mq_clear_sbinfo(struct ipc_namespace *ns)
1256{
1257	ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1258}
1259
1260void mq_put_mnt(struct ipc_namespace *ns)
1261{
1262	mntput(ns->mq_mnt);
1263}
1264
1265static int __init init_mqueue_fs(void)
1266{
1267	int error;
1268
1269	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1270				sizeof(struct mqueue_inode_info), 0,
1271				SLAB_HWCACHE_ALIGN, init_once);
1272	if (mqueue_inode_cachep == NULL)
1273		return -ENOMEM;
1274
1275	/* ignore failures - they are not fatal */
1276	mq_sysctl_table = mq_register_sysctl_table();
1277
1278	error = register_filesystem(&mqueue_fs_type);
1279	if (error)
1280		goto out_sysctl;
1281
1282	spin_lock_init(&mq_lock);
1283
1284	init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns);
1285	if (IS_ERR(init_ipc_ns.mq_mnt)) {
1286		error = PTR_ERR(init_ipc_ns.mq_mnt);
1287		goto out_filesystem;
1288	}
1289
1290	return 0;
1291
1292out_filesystem:
1293	unregister_filesystem(&mqueue_fs_type);
1294out_sysctl:
1295	if (mq_sysctl_table)
1296		unregister_sysctl_table(mq_sysctl_table);
1297	kmem_cache_destroy(mqueue_inode_cachep);
1298	return error;
1299}
1300
1301__initcall(init_mqueue_fs);
1302