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Root/ipc/mqueue.c

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
51	struct 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
58	struct 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
78	static const struct inode_operations mqueue_dir_inode_operations;
79	static const struct file_operations mqueue_file_operations;
80	static const struct super_operations mqueue_super_ops;
81	static void remove_notification(struct mqueue_inode_info *info);
82
83	static struct kmem_cache *mqueue_inode_cachep;
84
85	static struct ctl_table_header * mq_sysctl_table;
86
87	static 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	*/
95	static 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
100	static 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
110	static 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_mode = mode;
120	inode->i_uid = current_fsuid();
121	inode->i_gid = current_fsgid();
122	inode->i_mtime = inode->i_ctime = inode->i_atime =
123	CURRENT_TIME;
124
125	if (S_ISREG(mode)) {
126	struct mqueue_inode_info *info;
127	struct task_struct *p = current;
128	unsigned long mq_bytes, mq_msg_tblsz;
129
130	inode->i_fop = &mqueue_file_operations;
131	inode->i_size = FILENT_SIZE;
132	/* mqueue specific info */
133	info = MQUEUE_I(inode);
134	spin_lock_init(&info->lock);
135	init_waitqueue_head(&info->wait_q);
136	INIT_LIST_HEAD(&info->e_wait_q[0].list);
137	INIT_LIST_HEAD(&info->e_wait_q[1].list);
138	info->notify_owner = NULL;
139	info->qsize = 0;
140	info->user = NULL; /* set when all is ok */
141	memset(&info->attr, 0, sizeof(info->attr));
142	info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
143	info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
144	if (attr) {
145	info->attr.mq_maxmsg = attr->mq_maxmsg;
146	info->attr.mq_msgsize = attr->mq_msgsize;
147	}
148	mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
149	info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
150	if (!info->messages)
151	goto out_inode;
152
153	mq_bytes = (mq_msg_tblsz +
154	(info->attr.mq_maxmsg * info->attr.mq_msgsize));
155
156	spin_lock(&mq_lock);
157	if (u->mq_bytes + mq_bytes < u->mq_bytes \|\|
158	u->mq_bytes + mq_bytes >
159	task_rlimit(p, RLIMIT_MSGQUEUE)) {
160	spin_unlock(&mq_lock);
161	kfree(info->messages);
162	goto out_inode;
163	}
164	u->mq_bytes += mq_bytes;
165	spin_unlock(&mq_lock);
166
167	/* all is ok */
168	info->user = get_uid(u);
169	} else if (S_ISDIR(mode)) {
170	inc_nlink(inode);
171	/* Some things misbehave if size == 0 on a directory */
172	inode->i_size = 2 * DIRENT_SIZE;
173	inode->i_op = &mqueue_dir_inode_operations;
174	inode->i_fop = &simple_dir_operations;
175	}
176	}
177	return inode;
178	out_inode:
179	make_bad_inode(inode);
180	iput(inode);
181	return NULL;
182	}
183
184	static 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
210	out:
211	return error;
212	}
213
214	static 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
223	static 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
230	static 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
240	static void mqueue_destroy_inode(struct inode *inode)
241	{
242	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
243	}
244
245	static void mqueue_delete_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	if (S_ISDIR(inode->i_mode)) {
254	clear_inode(inode);
255	return;
256	}
257	ipc_ns = get_ns_from_inode(inode);
258	info = MQUEUE_I(inode);
259	spin_lock(&info->lock);
260	for (i = 0; i < info->attr.mq_curmsgs; i++)
261	free_msg(info->messages[i]);
262	kfree(info->messages);
263	spin_unlock(&info->lock);
264
265	clear_inode(inode);
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
289	static int mqueue_create(struct inode dir, struct dentry dentry,
290	int 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 (!inode) {
313	error = -ENOMEM;
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;
326	out_unlock:
327	spin_unlock(&mq_lock);
328	if (ipc_ns)
329	put_ipc_ns(ipc_ns);
330	return error;
331	}
332
333	static 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	*/
351	static 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
379	static 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
391	static 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 */
410	static 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	*/
431	static int wq_sleep(struct mqueue_inode_info *info, int sr,
432	long 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_timeout(timeout);
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);
467	out_unlock:
468	spin_unlock(&info->lock);
469	out:
470	return retval;
471	}
472
473	/*
474	* Returns waiting task that should be serviced first or NULL if none exists
475	*/
476	static 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 */
488	static 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
502	static 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
508	static 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	*/
516	static 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
555	static long prepare_timeout(struct timespec *p)
556	{
557	struct timespec nowts;
558	long timeout;
559
560	if (p) {
561	if (unlikely(p->tv_nsec < 0 \|\| p->tv_sec < 0
562	\|\| p->tv_nsec >= NSEC_PER_SEC))
563	return -EINVAL;
564	nowts = CURRENT_TIME;
565	/* first subtract as jiffies can't be too big */
566	p->tv_sec -= nowts.tv_sec;
567	if (p->tv_nsec < nowts.tv_nsec) {
568	p->tv_nsec += NSEC_PER_SEC;
569	p->tv_sec--;
570	}
571	p->tv_nsec -= nowts.tv_nsec;
572	if (p->tv_sec < 0)
573	return 0;
574
575	timeout = timespec_to_jiffies(p) + 1;
576	} else
577	return MAX_SCHEDULE_TIMEOUT;
578
579	return timeout;
580	}
581
582	static 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	info->notify_owner = NULL;
591	}
592
593	static int mq_attr_ok(struct ipc_namespace ipc_ns, struct mq_attr attr)
594	{
595	if (attr->mq_maxmsg <= 0 \|\| attr->mq_msgsize <= 0)
596	return 0;
597	if (capable(CAP_SYS_RESOURCE)) {
598	if (attr->mq_maxmsg > HARD_MSGMAX)
599	return 0;
600	} else {
601	if (attr->mq_maxmsg > ipc_ns->mq_msg_max \|\|
602	attr->mq_msgsize > ipc_ns->mq_msgsize_max)
603	return 0;
604	}
605	/* check for overflow */
606	if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
607	return 0;
608	if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
609	+ sizeof (struct msg_msg *))) <
610	(unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
611	return 0;
612	return 1;
613	}
614
615	/*
616	* Invoked when creating a new queue via sys_mq_open
617	*/
618	static struct file do_create(struct ipc_namespace ipc_ns, struct dentry *dir,
619	struct dentry *dentry, int oflag, mode_t mode,
620	struct mq_attr *attr)
621	{
622	const struct cred *cred = current_cred();
623	struct file *result;
624	int ret;
625
626	if (attr) {
627	if (!mq_attr_ok(ipc_ns, attr)) {
628	ret = -EINVAL;
629	goto out;
630	}
631	/* store for use during create */
632	dentry->d_fsdata = attr;
633	}
634
635	mode &= ~current_umask();
636	ret = mnt_want_write(ipc_ns->mq_mnt);
637	if (ret)
638	goto out;
639	ret = vfs_create(dir->d_inode, dentry, mode, NULL);
640	dentry->d_fsdata = NULL;
641	if (ret)
642	goto out_drop_write;
643
644	result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
645	/*
646	* dentry_open() took a persistent mnt_want_write(),
647	* so we can now drop this one.
648	*/
649	mnt_drop_write(ipc_ns->mq_mnt);
650	return result;
651
652	out_drop_write:
653	mnt_drop_write(ipc_ns->mq_mnt);
654	out:
655	dput(dentry);
656	mntput(ipc_ns->mq_mnt);
657	return ERR_PTR(ret);
658	}
659
660	/* Opens existing queue */
661	static struct file do_open(struct ipc_namespace ipc_ns,
662	struct dentry *dentry, int oflag)
663	{
664	int ret;
665	const struct cred *cred = current_cred();
666
667	static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
668	MAY_READ \| MAY_WRITE };
669
670	if ((oflag & O_ACCMODE) == (O_RDWR \| O_WRONLY)) {
671	ret = -EINVAL;
672	goto err;
673	}
674
675	if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
676	ret = -EACCES;
677	goto err;
678	}
679
680	return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
681
682	err:
683	dput(dentry);
684	mntput(ipc_ns->mq_mnt);
685	return ERR_PTR(ret);
686	}
687
688	SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
689	struct mq_attr __user *, u_attr)
690	{
691	struct dentry *dentry;
692	struct file *filp;
693	char *name;
694	struct mq_attr attr;
695	int fd, error;
696	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
697
698	if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
699	return -EFAULT;
700
701	audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
702
703	if (IS_ERR(name = getname(u_name)))
704	return PTR_ERR(name);
705
706	fd = get_unused_fd_flags(O_CLOEXEC);
707	if (fd < 0)
708	goto out_putname;
709
710	mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
711	dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
712	if (IS_ERR(dentry)) {
713	error = PTR_ERR(dentry);
714	goto out_putfd;
715	}
716	mntget(ipc_ns->mq_mnt);
717
718	if (oflag & O_CREAT) {
719	if (dentry->d_inode) { /* entry already exists */
720	audit_inode(name, dentry);
721	if (oflag & O_EXCL) {
722	error = -EEXIST;
723	goto out;
724	}
725	filp = do_open(ipc_ns, dentry, oflag);
726	} else {
727	filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
728	dentry, oflag, mode,
729	u_attr ? &attr : NULL);
730	}
731	} else {
732	if (!dentry->d_inode) {
733	error = -ENOENT;
734	goto out;
735	}
736	audit_inode(name, dentry);
737	filp = do_open(ipc_ns, dentry, oflag);
738	}
739
740	if (IS_ERR(filp)) {
741	error = PTR_ERR(filp);
742	goto out_putfd;
743	}
744
745	fd_install(fd, filp);
746	goto out_upsem;
747
748	out:
749	dput(dentry);
750	mntput(ipc_ns->mq_mnt);
751	out_putfd:
752	put_unused_fd(fd);
753	fd = error;
754	out_upsem:
755	mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
756	out_putname:
757	putname(name);
758	return fd;
759	}
760
761	SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
762	{
763	int err;
764	char *name;
765	struct dentry *dentry;
766	struct inode *inode = NULL;
767	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
768
769	name = getname(u_name);
770	if (IS_ERR(name))
771	return PTR_ERR(name);
772
773	mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
774	I_MUTEX_PARENT);
775	dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
776	if (IS_ERR(dentry)) {
777	err = PTR_ERR(dentry);
778	goto out_unlock;
779	}
780
781	if (!dentry->d_inode) {
782	err = -ENOENT;
783	goto out_err;
784	}
785
786	inode = dentry->d_inode;
787	if (inode)
788	atomic_inc(&inode->i_count);
789	err = mnt_want_write(ipc_ns->mq_mnt);
790	if (err)
791	goto out_err;
792	err = vfs_unlink(dentry->d_parent->d_inode, dentry);
793	mnt_drop_write(ipc_ns->mq_mnt);
794	out_err:
795	dput(dentry);
796
797	out_unlock:
798	mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
799	putname(name);
800	if (inode)
801	iput(inode);
802
803	return err;
804	}
805
806	/* Pipelined send and receive functions.
807	*
808	* If a receiver finds no waiting message, then it registers itself in the
809	* list of waiting receivers. A sender checks that list before adding the new
810	* message into the message array. If there is a waiting receiver, then it
811	* bypasses the message array and directly hands the message over to the
812	* receiver.
813	* The receiver accepts the message and returns without grabbing the queue
814	* spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
815	* are necessary. The same algorithm is used for sysv semaphores, see
816	* ipc/sem.c for more details.
817	*
818	* The same algorithm is used for senders.
819	*/
820
821	/* pipelined_send() - send a message directly to the task waiting in
822	* sys_mq_timedreceive() (without inserting message into a queue).
823	*/
824	static inline void pipelined_send(struct mqueue_inode_info *info,
825	struct msg_msg *message,
826	struct ext_wait_queue *receiver)
827	{
828	receiver->msg = message;
829	list_del(&receiver->list);
830	receiver->state = STATE_PENDING;
831	wake_up_process(receiver->task);
832	smp_wmb();
833	receiver->state = STATE_READY;
834	}
835
836	/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
837	* gets its message and put to the queue (we have one free place for sure). */
838	static inline void pipelined_receive(struct mqueue_inode_info *info)
839	{
840	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
841
842	if (!sender) {
843	/* for poll */
844	wake_up_interruptible(&info->wait_q);
845	return;
846	}
847	msg_insert(sender->msg, info);
848	list_del(&sender->list);
849	sender->state = STATE_PENDING;
850	wake_up_process(sender->task);
851	smp_wmb();
852	sender->state = STATE_READY;
853	}
854
855	SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
856	size_t, msg_len, unsigned int, msg_prio,
857	const struct timespec __user *, u_abs_timeout)
858	{
859	struct file *filp;
860	struct inode *inode;
861	struct ext_wait_queue wait;
862	struct ext_wait_queue *receiver;
863	struct msg_msg *msg_ptr;
864	struct mqueue_inode_info *info;
865	struct timespec ts, *p = NULL;
866	long timeout;
867	int ret;
868
869	if (u_abs_timeout) {
870	if (copy_from_user(&ts, u_abs_timeout,
871	sizeof(struct timespec)))
872	return -EFAULT;
873	p = &ts;
874	}
875
876	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
877	return -EINVAL;
878
879	audit_mq_sendrecv(mqdes, msg_len, msg_prio, p);
880	timeout = prepare_timeout(p);
881
882	filp = fget(mqdes);
883	if (unlikely(!filp)) {
884	ret = -EBADF;
885	goto out;
886	}
887
888	inode = filp->f_path.dentry->d_inode;
889	if (unlikely(filp->f_op != &mqueue_file_operations)) {
890	ret = -EBADF;
891	goto out_fput;
892	}
893	info = MQUEUE_I(inode);
894	audit_inode(NULL, filp->f_path.dentry);
895
896	if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
897	ret = -EBADF;
898	goto out_fput;
899	}
900
901	if (unlikely(msg_len > info->attr.mq_msgsize)) {
902	ret = -EMSGSIZE;
903	goto out_fput;
904	}
905
906	/* First try to allocate memory, before doing anything with
907	* existing queues. */
908	msg_ptr = load_msg(u_msg_ptr, msg_len);
909	if (IS_ERR(msg_ptr)) {
910	ret = PTR_ERR(msg_ptr);
911	goto out_fput;
912	}
913	msg_ptr->m_ts = msg_len;
914	msg_ptr->m_type = msg_prio;
915
916	spin_lock(&info->lock);
917
918	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
919	if (filp->f_flags & O_NONBLOCK) {
920	spin_unlock(&info->lock);
921	ret = -EAGAIN;
922	} else if (unlikely(timeout < 0)) {
923	spin_unlock(&info->lock);
924	ret = timeout;
925	} else {
926	wait.task = current;
927	wait.msg = (void *) msg_ptr;
928	wait.state = STATE_NONE;
929	ret = wq_sleep(info, SEND, timeout, &wait);
930	}
931	if (ret < 0)
932	free_msg(msg_ptr);
933	} else {
934	receiver = wq_get_first_waiter(info, RECV);
935	if (receiver) {
936	pipelined_send(info, msg_ptr, receiver);
937	} else {
938	/* adds message to the queue */
939	msg_insert(msg_ptr, info);
940	__do_notify(info);
941	}
942	inode->i_atime = inode->i_mtime = inode->i_ctime =
943	CURRENT_TIME;
944	spin_unlock(&info->lock);
945	ret = 0;
946	}
947	out_fput:
948	fput(filp);
949	out:
950	return ret;
951	}
952
953	SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
954	size_t, msg_len, unsigned int __user *, u_msg_prio,
955	const struct timespec __user *, u_abs_timeout)
956	{
957	long timeout;
958	ssize_t ret;
959	struct msg_msg *msg_ptr;
960	struct file *filp;
961	struct inode *inode;
962	struct mqueue_inode_info *info;
963	struct ext_wait_queue wait;
964	struct timespec ts, *p = NULL;
965
966	if (u_abs_timeout) {
967	if (copy_from_user(&ts, u_abs_timeout,
968	sizeof(struct timespec)))
969	return -EFAULT;
970	p = &ts;
971	}
972
973	audit_mq_sendrecv(mqdes, msg_len, 0, p);
974	timeout = prepare_timeout(p);
975
976	filp = fget(mqdes);
977	if (unlikely(!filp)) {
978	ret = -EBADF;
979	goto out;
980	}
981
982	inode = filp->f_path.dentry->d_inode;
983	if (unlikely(filp->f_op != &mqueue_file_operations)) {
984	ret = -EBADF;
985	goto out_fput;
986	}
987	info = MQUEUE_I(inode);
988	audit_inode(NULL, filp->f_path.dentry);
989
990	if (unlikely(!(filp->f_mode & FMODE_READ))) {
991	ret = -EBADF;
992	goto out_fput;
993	}
994
995	/* checks if buffer is big enough */
996	if (unlikely(msg_len < info->attr.mq_msgsize)) {
997	ret = -EMSGSIZE;
998	goto out_fput;
999	}
1000
1001	spin_lock(&info->lock);
1002	if (info->attr.mq_curmsgs == 0) {
1003	if (filp->f_flags & O_NONBLOCK) {
1004	spin_unlock(&info->lock);
1005	ret = -EAGAIN;
1006	msg_ptr = NULL;
1007	} else if (unlikely(timeout < 0)) {
1008	spin_unlock(&info->lock);
1009	ret = timeout;
1010	msg_ptr = NULL;
1011	} else {
1012	wait.task = current;
1013	wait.state = STATE_NONE;
1014	ret = wq_sleep(info, RECV, timeout, &wait);
1015	msg_ptr = wait.msg;
1016	}
1017	} else {
1018	msg_ptr = msg_get(info);
1019
1020	inode->i_atime = inode->i_mtime = inode->i_ctime =
1021	CURRENT_TIME;
1022
1023	/* There is now free space in queue. */
1024	pipelined_receive(info);
1025	spin_unlock(&info->lock);
1026	ret = 0;
1027	}
1028	if (ret == 0) {
1029	ret = msg_ptr->m_ts;
1030
1031	if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) \|\|
1032	store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1033	ret = -EFAULT;
1034	}
1035	free_msg(msg_ptr);
1036	}
1037	out_fput:
1038	fput(filp);
1039	out:
1040	return ret;
1041	}
1042
1043	/*
1044	* Notes: the case when user wants us to deregister (with NULL as pointer)
1045	* and he isn't currently owner of notification, will be silently discarded.
1046	* It isn't explicitly defined in the POSIX.
1047	*/
1048	SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1049	const struct sigevent __user *, u_notification)
1050	{
1051	int ret;
1052	struct file *filp;
1053	struct sock *sock;
1054	struct inode *inode;
1055	struct sigevent notification;
1056	struct mqueue_inode_info *info;
1057	struct sk_buff *nc;
1058
1059	if (u_notification) {
1060	if (copy_from_user(&notification, u_notification,
1061	sizeof(struct sigevent)))
1062	return -EFAULT;
1063	}
1064
1065	audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1066
1067	nc = NULL;
1068	sock = NULL;
1069	if (u_notification != NULL) {
1070	if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1071	notification.sigev_notify != SIGEV_SIGNAL &&
1072	notification.sigev_notify != SIGEV_THREAD))
1073	return -EINVAL;
1074	if (notification.sigev_notify == SIGEV_SIGNAL &&
1075	!valid_signal(notification.sigev_signo)) {
1076	return -EINVAL;
1077	}
1078	if (notification.sigev_notify == SIGEV_THREAD) {
1079	long timeo;
1080
1081	/* create the notify skb */
1082	nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1083	if (!nc) {
1084	ret = -ENOMEM;
1085	goto out;
1086	}
1087	if (copy_from_user(nc->data,
1088	notification.sigev_value.sival_ptr,
1089	NOTIFY_COOKIE_LEN)) {
1090	ret = -EFAULT;
1091	goto out;
1092	}
1093
1094	/* TODO: add a header? */
1095	skb_put(nc, NOTIFY_COOKIE_LEN);
1096	/* and attach it to the socket */
1097	retry:
1098	filp = fget(notification.sigev_signo);
1099	if (!filp) {
1100	ret = -EBADF;
1101	goto out;
1102	}
1103	sock = netlink_getsockbyfilp(filp);
1104	fput(filp);
1105	if (IS_ERR(sock)) {
1106	ret = PTR_ERR(sock);
1107	sock = NULL;
1108	goto out;
1109	}
1110
1111	timeo = MAX_SCHEDULE_TIMEOUT;
1112	ret = netlink_attachskb(sock, nc, &timeo, NULL);
1113	if (ret == 1)
1114	goto retry;
1115	if (ret) {
1116	sock = NULL;
1117	nc = NULL;
1118	goto out;
1119	}
1120	}
1121	}
1122
1123	filp = fget(mqdes);
1124	if (!filp) {
1125	ret = -EBADF;
1126	goto out;
1127	}
1128
1129	inode = filp->f_path.dentry->d_inode;
1130	if (unlikely(filp->f_op != &mqueue_file_operations)) {
1131	ret = -EBADF;
1132	goto out_fput;
1133	}
1134	info = MQUEUE_I(inode);
1135
1136	ret = 0;
1137	spin_lock(&info->lock);
1138	if (u_notification == NULL) {
1139	if (info->notify_owner == task_tgid(current)) {
1140	remove_notification(info);
1141	inode->i_atime = inode->i_ctime = CURRENT_TIME;
1142	}
1143	} else if (info->notify_owner != NULL) {
1144	ret = -EBUSY;
1145	} else {
1146	switch (notification.sigev_notify) {
1147	case SIGEV_NONE:
1148	info->notify.sigev_notify = SIGEV_NONE;
1149	break;
1150	case SIGEV_THREAD:
1151	info->notify_sock = sock;
1152	info->notify_cookie = nc;
1153	sock = NULL;
1154	nc = NULL;
1155	info->notify.sigev_notify = SIGEV_THREAD;
1156	break;
1157	case SIGEV_SIGNAL:
1158	info->notify.sigev_signo = notification.sigev_signo;
1159	info->notify.sigev_value = notification.sigev_value;
1160	info->notify.sigev_notify = SIGEV_SIGNAL;
1161	break;
1162	}
1163
1164	info->notify_owner = get_pid(task_tgid(current));
1165	inode->i_atime = inode->i_ctime = CURRENT_TIME;
1166	}
1167	spin_unlock(&info->lock);
1168	out_fput:
1169	fput(filp);
1170	out:
1171	if (sock) {
1172	netlink_detachskb(sock, nc);
1173	} else if (nc) {
1174	dev_kfree_skb(nc);
1175	}
1176	return ret;
1177	}
1178
1179	SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1180	const struct mq_attr __user *, u_mqstat,
1181	struct mq_attr __user *, u_omqstat)
1182	{
1183	int ret;
1184	struct mq_attr mqstat, omqstat;
1185	struct file *filp;
1186	struct inode *inode;
1187	struct mqueue_inode_info *info;
1188
1189	if (u_mqstat != NULL) {
1190	if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1191	return -EFAULT;
1192	if (mqstat.mq_flags & (~O_NONBLOCK))
1193	return -EINVAL;
1194	}
1195
1196	filp = fget(mqdes);
1197	if (!filp) {
1198	ret = -EBADF;
1199	goto out;
1200	}
1201
1202	inode = filp->f_path.dentry->d_inode;
1203	if (unlikely(filp->f_op != &mqueue_file_operations)) {
1204	ret = -EBADF;
1205	goto out_fput;
1206	}
1207	info = MQUEUE_I(inode);
1208
1209	spin_lock(&info->lock);
1210
1211	omqstat = info->attr;
1212	omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1213	if (u_mqstat) {
1214	audit_mq_getsetattr(mqdes, &mqstat);
1215	spin_lock(&filp->f_lock);
1216	if (mqstat.mq_flags & O_NONBLOCK)
1217	filp->f_flags \|= O_NONBLOCK;
1218	else
1219	filp->f_flags &= ~O_NONBLOCK;
1220	spin_unlock(&filp->f_lock);
1221
1222	inode->i_atime = inode->i_ctime = CURRENT_TIME;
1223	}
1224
1225	spin_unlock(&info->lock);
1226
1227	ret = 0;
1228	if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1229	sizeof(struct mq_attr)))
1230	ret = -EFAULT;
1231
1232	out_fput:
1233	fput(filp);
1234	out:
1235	return ret;
1236	}
1237
1238	static const struct inode_operations mqueue_dir_inode_operations = {
1239	.lookup = simple_lookup,
1240	.create = mqueue_create,
1241	.unlink = mqueue_unlink,
1242	};
1243
1244	static const struct file_operations mqueue_file_operations = {
1245	.flush = mqueue_flush_file,
1246	.poll = mqueue_poll_file,
1247	.read = mqueue_read_file,
1248	};
1249
1250	static const struct super_operations mqueue_super_ops = {
1251	.alloc_inode = mqueue_alloc_inode,
1252	.destroy_inode = mqueue_destroy_inode,
1253	.statfs = simple_statfs,
1254	.delete_inode = mqueue_delete_inode,
1255	.drop_inode = generic_delete_inode,
1256	};
1257
1258	static struct file_system_type mqueue_fs_type = {
1259	.name = "mqueue",
1260	.get_sb = mqueue_get_sb,
1261	.kill_sb = kill_litter_super,
1262	};
1263
1264	int mq_init_ns(struct ipc_namespace *ns)
1265	{
1266	ns->mq_queues_count = 0;
1267	ns->mq_queues_max = DFLT_QUEUESMAX;
1268	ns->mq_msg_max = DFLT_MSGMAX;
1269	ns->mq_msgsize_max = DFLT_MSGSIZEMAX;
1270
1271	ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1272	if (IS_ERR(ns->mq_mnt)) {
1273	int err = PTR_ERR(ns->mq_mnt);
1274	ns->mq_mnt = NULL;
1275	return err;
1276	}
1277	return 0;
1278	}
1279
1280	void mq_clear_sbinfo(struct ipc_namespace *ns)
1281	{
1282	ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1283	}
1284
1285	void mq_put_mnt(struct ipc_namespace *ns)
1286	{
1287	mntput(ns->mq_mnt);
1288	}
1289
1290	static int __init init_mqueue_fs(void)
1291	{
1292	int error;
1293
1294	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1295	sizeof(struct mqueue_inode_info), 0,
1296	SLAB_HWCACHE_ALIGN, init_once);
1297	if (mqueue_inode_cachep == NULL)
1298	return -ENOMEM;
1299
1300	/* ignore failures - they are not fatal */
1301	mq_sysctl_table = mq_register_sysctl_table();
1302
1303	error = register_filesystem(&mqueue_fs_type);
1304	if (error)
1305	goto out_sysctl;
1306
1307	spin_lock_init(&mq_lock);
1308
1309	init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns);
1310	if (IS_ERR(init_ipc_ns.mq_mnt)) {
1311	error = PTR_ERR(init_ipc_ns.mq_mnt);
1312	goto out_filesystem;
1313	}
1314
1315	return 0;
1316
1317	out_filesystem:
1318	unregister_filesystem(&mqueue_fs_type);
1319	out_sysctl:
1320	if (mq_sysctl_table)
1321	unregister_sysctl_table(mq_sysctl_table);
1322	kmem_cache_destroy(mqueue_inode_cachep);
1323	return error;
1324	}
1325
1326	__initcall(init_mqueue_fs);
1327

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jz47xx-2.6.38
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9

Kernel

Kernel Git Source Tree

Root/ipc/mqueue.c

interactive