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fs: use kmem_cache_zalloc instead
[pv_ops_mirror.git] / ipc / mqueue.c
blob774843cff756fe169948b8a084649d5f36dcb7fa
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
33 #include <net/sock.h>
34 #include "util.h"
35
36 #define MQUEUE_MAGIC 0x19800202
37 #define DIRENT_SIZE 20
38 #define FILENT_SIZE 80
39
40 #define SEND 0
41 #define RECV 1
42
43 #define STATE_NONE 0
44 #define STATE_PENDING 1
45 #define STATE_READY 2
46
47 /* used by sysctl */
48 #define FS_MQUEUE 1
49 #define CTL_QUEUESMAX 2
50 #define CTL_MSGMAX 3
51 #define CTL_MSGSIZEMAX 4
52
53 /* default values */
54 #define DFLT_QUEUESMAX 256 /* max number of message queues */
55 #define DFLT_MSGMAX 10 /* max number of messages in each queue */
56 #define HARD_MSGMAX (131072/sizeof(void*))
57 #define DFLT_MSGSIZEMAX 8192 /* max message size */
58
59
60 struct ext_wait_queue { /* queue of sleeping tasks */
61 struct task_struct *task;
62 struct list_head list;
63 struct msg_msg *msg; /* ptr of loaded message */
64 int state; /* one of STATE_* values */
65 };
66
67 struct mqueue_inode_info {
68 spinlock_t lock;
69 struct inode vfs_inode;
70 wait_queue_head_t wait_q;
71
72 struct msg_msg **messages;
73 struct mq_attr attr;
74
75 struct sigevent notify;
76 struct pid* notify_owner;
77 struct user_struct *user; /* user who created, for accounting */
78 struct sock *notify_sock;
79 struct sk_buff *notify_cookie;
80
81 /* for tasks waiting for free space and messages, respectively */
82 struct ext_wait_queue e_wait_q[2];
83
84 unsigned long qsize; /* size of queue in memory (sum of all msgs) */
85 };
86
87 static const struct inode_operations mqueue_dir_inode_operations;
88 static const struct file_operations mqueue_file_operations;
89 static struct super_operations mqueue_super_ops;
90 static void remove_notification(struct mqueue_inode_info *info);
91
92 static spinlock_t mq_lock;
93 static struct kmem_cache *mqueue_inode_cachep;
94 static struct vfsmount *mqueue_mnt;
95
96 static unsigned int queues_count;
97 static unsigned int queues_max = DFLT_QUEUESMAX;
98 static unsigned int msg_max = DFLT_MSGMAX;
99 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
100
101 static struct ctl_table_header * mq_sysctl_table;
102
103 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
104 {
105 return container_of(inode, struct mqueue_inode_info, vfs_inode);
106 }
107
108 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
109 struct mq_attr *attr)
110 {
111 struct inode *inode;
112
113 inode = new_inode(sb);
114 if (inode) {
115 inode->i_mode = mode;
116 inode->i_uid = current->fsuid;
117 inode->i_gid = current->fsgid;
118 inode->i_blocks = 0;
119 inode->i_mtime = inode->i_ctime = inode->i_atime =
120 CURRENT_TIME;
121
122 if (S_ISREG(mode)) {
123 struct mqueue_inode_info *info;
124 struct task_struct *p = current;
125 struct user_struct *u = p->user;
126 unsigned long mq_bytes, mq_msg_tblsz;
127
128 inode->i_fop = &mqueue_file_operations;
129 inode->i_size = FILENT_SIZE;
130 /* mqueue specific info */
131 info = MQUEUE_I(inode);
132 spin_lock_init(&info->lock);
133 init_waitqueue_head(&info->wait_q);
134 INIT_LIST_HEAD(&info->e_wait_q[0].list);
135 INIT_LIST_HEAD(&info->e_wait_q[1].list);
136 info->messages = NULL;
137 info->notify_owner = NULL;
138 info->qsize = 0;
139 info->user = NULL; /* set when all is ok */
140 memset(&info->attr, 0, sizeof(info->attr));
141 info->attr.mq_maxmsg = DFLT_MSGMAX;
142 info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
143 if (attr) {
144 info->attr.mq_maxmsg = attr->mq_maxmsg;
145 info->attr.mq_msgsize = attr->mq_msgsize;
146 }
147 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
148 mq_bytes = (mq_msg_tblsz +
149 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
150
151 spin_lock(&mq_lock);
152 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
153 u->mq_bytes + mq_bytes >
154 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
155 spin_unlock(&mq_lock);
156 goto out_inode;
157 }
158 u->mq_bytes += mq_bytes;
159 spin_unlock(&mq_lock);
160
161 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
162 if (!info->messages) {
163 spin_lock(&mq_lock);
164 u->mq_bytes -= mq_bytes;
165 spin_unlock(&mq_lock);
166 goto out_inode;
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;
179 out_inode:
180 make_bad_inode(inode);
181 iput(inode);
182 return NULL;
183 }
184
185 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
186 {
187 struct inode *inode;
188
189 sb->s_blocksize = PAGE_CACHE_SIZE;
190 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
191 sb->s_magic = MQUEUE_MAGIC;
192 sb->s_op = &mqueue_super_ops;
193
194 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
195 if (!inode)
196 return -ENOMEM;
197
198 sb->s_root = d_alloc_root(inode);
199 if (!sb->s_root) {
200 iput(inode);
201 return -ENOMEM;
202 }
203
204 return 0;
205 }
206
207 static int mqueue_get_sb(struct file_system_type *fs_type,
208 int flags, const char *dev_name,
209 void *data, struct vfsmount *mnt)
210 {
211 return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
212 }
213
214 static void init_once(struct kmem_cache *cachep, void *foo)
215 {
216 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
217
218 inode_init_once(&p->vfs_inode);
219 }
220
221 static struct inode *mqueue_alloc_inode(struct super_block *sb)
222 {
223 struct mqueue_inode_info *ei;
224
225 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
226 if (!ei)
227 return NULL;
228 return &ei->vfs_inode;
229 }
230
231 static void mqueue_destroy_inode(struct inode *inode)
232 {
233 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
234 }
235
236 static void mqueue_delete_inode(struct inode *inode)
237 {
238 struct mqueue_inode_info *info;
239 struct user_struct *user;
240 unsigned long mq_bytes;
241 int i;
242
243 if (S_ISDIR(inode->i_mode)) {
244 clear_inode(inode);
245 return;
246 }
247 info = MQUEUE_I(inode);
248 spin_lock(&info->lock);
249 for (i = 0; i < info->attr.mq_curmsgs; i++)
250 free_msg(info->messages[i]);
251 kfree(info->messages);
252 spin_unlock(&info->lock);
253
254 clear_inode(inode);
255
256 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
257 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
258 user = info->user;
259 if (user) {
260 spin_lock(&mq_lock);
261 user->mq_bytes -= mq_bytes;
262 queues_count--;
263 spin_unlock(&mq_lock);
264 free_uid(user);
265 }
266 }
267
268 static int mqueue_create(struct inode *dir, struct dentry *dentry,
269 int mode, struct nameidata *nd)
270 {
271 struct inode *inode;
272 struct mq_attr *attr = dentry->d_fsdata;
273 int error;
274
275 spin_lock(&mq_lock);
276 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
277 error = -ENOSPC;
278 goto out_lock;
279 }
280 queues_count++;
281 spin_unlock(&mq_lock);
282
283 inode = mqueue_get_inode(dir->i_sb, mode, attr);
284 if (!inode) {
285 error = -ENOMEM;
286 spin_lock(&mq_lock);
287 queues_count--;
288 goto out_lock;
289 }
290
291 dir->i_size += DIRENT_SIZE;
292 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
293
294 d_instantiate(dentry, inode);
295 dget(dentry);
296 return 0;
297 out_lock:
298 spin_unlock(&mq_lock);
299 return error;
300 }
301
302 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
303 {
304 struct inode *inode = dentry->d_inode;
305
306 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
307 dir->i_size -= DIRENT_SIZE;
308 drop_nlink(inode);
309 dput(dentry);
310 return 0;
311 }
312
313 /*
314 * This is routine for system read from queue file.
315 * To avoid mess with doing here some sort of mq_receive we allow
316 * to read only queue size & notification info (the only values
317 * that are interesting from user point of view and aren't accessible
318 * through std routines)
319 */
320 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
321 size_t count, loff_t * off)
322 {
323 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
324 char buffer[FILENT_SIZE];
325 size_t slen;
326 loff_t o;
327
328 if (!count)
329 return 0;
330
331 spin_lock(&info->lock);
332 snprintf(buffer, sizeof(buffer),
333 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
334 info->qsize,
335 info->notify_owner ? info->notify.sigev_notify : 0,
336 (info->notify_owner &&
337 info->notify.sigev_notify == SIGEV_SIGNAL) ?
338 info->notify.sigev_signo : 0,
339 pid_nr(info->notify_owner));
340 spin_unlock(&info->lock);
341 buffer[sizeof(buffer)-1] = '\0';
342 slen = strlen(buffer)+1;
343
344 o = *off;
345 if (o > slen)
346 return 0;
347
348 if (o + count > slen)
349 count = slen - o;
350
351 if (copy_to_user(u_data, buffer + o, count))
352 return -EFAULT;
353
354 *off = o + count;
355 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
356 return count;
357 }
358
359 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
360 {
361 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
362
363 spin_lock(&info->lock);
364 if (task_tgid(current) == info->notify_owner)
365 remove_notification(info);
366
367 spin_unlock(&info->lock);
368 return 0;
369 }
370
371 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
372 {
373 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
374 int retval = 0;
375
376 poll_wait(filp, &info->wait_q, poll_tab);
377
378 spin_lock(&info->lock);
379 if (info->attr.mq_curmsgs)
380 retval = POLLIN | POLLRDNORM;
381
382 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
383 retval |= POLLOUT | POLLWRNORM;
384 spin_unlock(&info->lock);
385
386 return retval;
387 }
388
389 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
390 static void wq_add(struct mqueue_inode_info *info, int sr,
391 struct ext_wait_queue *ewp)
392 {
393 struct ext_wait_queue *walk;
394
395 ewp->task = current;
396
397 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
398 if (walk->task->static_prio <= current->static_prio) {
399 list_add_tail(&ewp->list, &walk->list);
400 return;
401 }
402 }
403 list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
404 }
405
406 /*
407 * Puts current task to sleep. Caller must hold queue lock. After return
408 * lock isn't held.
409 * sr: SEND or RECV
410 */
411 static int wq_sleep(struct mqueue_inode_info *info, int sr,
412 long timeout, struct ext_wait_queue *ewp)
413 {
414 int retval;
415 signed long time;
416
417 wq_add(info, sr, ewp);
418
419 for (;;) {
420 set_current_state(TASK_INTERRUPTIBLE);
421
422 spin_unlock(&info->lock);
423 time = schedule_timeout(timeout);
424
425 while (ewp->state == STATE_PENDING)
426 cpu_relax();
427
428 if (ewp->state == STATE_READY) {
429 retval = 0;
430 goto out;
431 }
432 spin_lock(&info->lock);
433 if (ewp->state == STATE_READY) {
434 retval = 0;
435 goto out_unlock;
436 }
437 if (signal_pending(current)) {
438 retval = -ERESTARTSYS;
439 break;
440 }
441 if (time == 0) {
442 retval = -ETIMEDOUT;
443 break;
444 }
445 }
446 list_del(&ewp->list);
447 out_unlock:
448 spin_unlock(&info->lock);
449 out:
450 return retval;
451 }
452
453 /*
454 * Returns waiting task that should be serviced first or NULL if none exists
455 */
456 static struct ext_wait_queue *wq_get_first_waiter(
457 struct mqueue_inode_info *info, int sr)
458 {
459 struct list_head *ptr;
460
461 ptr = info->e_wait_q[sr].list.prev;
462 if (ptr == &info->e_wait_q[sr].list)
463 return NULL;
464 return list_entry(ptr, struct ext_wait_queue, list);
465 }
466
467 /* Auxiliary functions to manipulate messages' list */
468 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
469 {
470 int k;
471
472 k = info->attr.mq_curmsgs - 1;
473 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
474 info->messages[k + 1] = info->messages[k];
475 k--;
476 }
477 info->attr.mq_curmsgs++;
478 info->qsize += ptr->m_ts;
479 info->messages[k + 1] = ptr;
480 }
481
482 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
483 {
484 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
485 return info->messages[info->attr.mq_curmsgs];
486 }
487
488 static inline void set_cookie(struct sk_buff *skb, char code)
489 {
490 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
491 }
492
493 /*
494 * The next function is only to split too long sys_mq_timedsend
495 */
496 static void __do_notify(struct mqueue_inode_info *info)
497 {
498 /* notification
499 * invoked when there is registered process and there isn't process
500 * waiting synchronously for message AND state of queue changed from
501 * empty to not empty. Here we are sure that no one is waiting
502 * synchronously. */
503 if (info->notify_owner &&
504 info->attr.mq_curmsgs == 1) {
505 struct siginfo sig_i;
506 switch (info->notify.sigev_notify) {
507 case SIGEV_NONE:
508 break;
509 case SIGEV_SIGNAL:
510 /* sends signal */
511
512 sig_i.si_signo = info->notify.sigev_signo;
513 sig_i.si_errno = 0;
514 sig_i.si_code = SI_MESGQ;
515 sig_i.si_value = info->notify.sigev_value;
516 sig_i.si_pid = current->tgid;
517 sig_i.si_uid = current->uid;
518
519 kill_pid_info(info->notify.sigev_signo,
520 &sig_i, info->notify_owner);
521 break;
522 case SIGEV_THREAD:
523 set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
524 netlink_sendskb(info->notify_sock, info->notify_cookie);
525 break;
526 }
527 /* after notification unregisters process */
528 put_pid(info->notify_owner);
529 info->notify_owner = NULL;
530 }
531 wake_up(&info->wait_q);
532 }
533
534 static long prepare_timeout(const struct timespec __user *u_arg)
535 {
536 struct timespec ts, nowts;
537 long timeout;
538
539 if (u_arg) {
540 if (unlikely(copy_from_user(&ts, u_arg,
541 sizeof(struct timespec))))
542 return -EFAULT;
543
544 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
545 || ts.tv_nsec >= NSEC_PER_SEC))
546 return -EINVAL;
547 nowts = CURRENT_TIME;
548 /* first subtract as jiffies can't be too big */
549 ts.tv_sec -= nowts.tv_sec;
550 if (ts.tv_nsec < nowts.tv_nsec) {
551 ts.tv_nsec += NSEC_PER_SEC;
552 ts.tv_sec--;
553 }
554 ts.tv_nsec -= nowts.tv_nsec;
555 if (ts.tv_sec < 0)
556 return 0;
557
558 timeout = timespec_to_jiffies(&ts) + 1;
559 } else
560 return MAX_SCHEDULE_TIMEOUT;
561
562 return timeout;
563 }
564
565 static void remove_notification(struct mqueue_inode_info *info)
566 {
567 if (info->notify_owner != NULL &&
568 info->notify.sigev_notify == SIGEV_THREAD) {
569 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
570 netlink_sendskb(info->notify_sock, info->notify_cookie);
571 }
572 put_pid(info->notify_owner);
573 info->notify_owner = NULL;
574 }
575
576 static int mq_attr_ok(struct mq_attr *attr)
577 {
578 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
579 return 0;
580 if (capable(CAP_SYS_RESOURCE)) {
581 if (attr->mq_maxmsg > HARD_MSGMAX)
582 return 0;
583 } else {
584 if (attr->mq_maxmsg > msg_max ||
585 attr->mq_msgsize > msgsize_max)
586 return 0;
587 }
588 /* check for overflow */
589 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
590 return 0;
591 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
592 (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
593 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
594 return 0;
595 return 1;
596 }
597
598 /*
599 * Invoked when creating a new queue via sys_mq_open
600 */
601 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
602 int oflag, mode_t mode, struct mq_attr __user *u_attr)
603 {
604 struct mq_attr attr;
605 int ret;
606
607 if (u_attr) {
608 ret = -EFAULT;
609 if (copy_from_user(&attr, u_attr, sizeof(attr)))
610 goto out;
611 ret = -EINVAL;
612 if (!mq_attr_ok(&attr))
613 goto out;
614 /* store for use during create */
615 dentry->d_fsdata = &attr;
616 }
617
618 mode &= ~current->fs->umask;
619 ret = vfs_create(dir->d_inode, dentry, mode, NULL);
620 dentry->d_fsdata = NULL;
621 if (ret)
622 goto out;
623
624 return dentry_open(dentry, mqueue_mnt, oflag);
625
626 out:
627 dput(dentry);
628 mntput(mqueue_mnt);
629 return ERR_PTR(ret);
630 }
631
632 /* Opens existing queue */
633 static struct file *do_open(struct dentry *dentry, int oflag)
634 {
635 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
636 MAY_READ | MAY_WRITE };
637
638 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
639 dput(dentry);
640 mntput(mqueue_mnt);
641 return ERR_PTR(-EINVAL);
642 }
643
644 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
645 dput(dentry);
646 mntput(mqueue_mnt);
647 return ERR_PTR(-EACCES);
648 }
649
650 return dentry_open(dentry, mqueue_mnt, oflag);
651 }
652
653 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
654 struct mq_attr __user *u_attr)
655 {
656 struct dentry *dentry;
657 struct file *filp;
658 char *name;
659 int fd, error;
660
661 error = audit_mq_open(oflag, mode, u_attr);
662 if (error != 0)
663 return error;
664
665 if (IS_ERR(name = getname(u_name)))
666 return PTR_ERR(name);
667
668 fd = get_unused_fd();
669 if (fd < 0)
670 goto out_putname;
671
672 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
673 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
674 if (IS_ERR(dentry)) {
675 error = PTR_ERR(dentry);
676 goto out_err;
677 }
678 mntget(mqueue_mnt);
679
680 if (oflag & O_CREAT) {
681 if (dentry->d_inode) { /* entry already exists */
682 audit_inode(name, dentry->d_inode);
683 error = -EEXIST;
684 if (oflag & O_EXCL)
685 goto out;
686 filp = do_open(dentry, oflag);
687 } else {
688 filp = do_create(mqueue_mnt->mnt_root, dentry,
689 oflag, mode, u_attr);
690 }
691 } else {
692 error = -ENOENT;
693 if (!dentry->d_inode)
694 goto out;
695 audit_inode(name, dentry->d_inode);
696 filp = do_open(dentry, oflag);
697 }
698
699 if (IS_ERR(filp)) {
700 error = PTR_ERR(filp);
701 goto out_putfd;
702 }
703
704 set_close_on_exec(fd, 1);
705 fd_install(fd, filp);
706 goto out_upsem;
707
708 out:
709 dput(dentry);
710 mntput(mqueue_mnt);
711 out_putfd:
712 put_unused_fd(fd);
713 out_err:
714 fd = error;
715 out_upsem:
716 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
717 out_putname:
718 putname(name);
719 return fd;
720 }
721
722 asmlinkage long sys_mq_unlink(const char __user *u_name)
723 {
724 int err;
725 char *name;
726 struct dentry *dentry;
727 struct inode *inode = NULL;
728
729 name = getname(u_name);
730 if (IS_ERR(name))
731 return PTR_ERR(name);
732
733 mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
734 I_MUTEX_PARENT);
735 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
736 if (IS_ERR(dentry)) {
737 err = PTR_ERR(dentry);
738 goto out_unlock;
739 }
740
741 if (!dentry->d_inode) {
742 err = -ENOENT;
743 goto out_err;
744 }
745
746 inode = dentry->d_inode;
747 if (inode)
748 atomic_inc(&inode->i_count);
749
750 err = vfs_unlink(dentry->d_parent->d_inode, dentry);
751 out_err:
752 dput(dentry);
753
754 out_unlock:
755 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
756 putname(name);
757 if (inode)
758 iput(inode);
759
760 return err;
761 }
762
763 /* Pipelined send and receive functions.
764 *
765 * If a receiver finds no waiting message, then it registers itself in the
766 * list of waiting receivers. A sender checks that list before adding the new
767 * message into the message array. If there is a waiting receiver, then it
768 * bypasses the message array and directly hands the message over to the
769 * receiver.
770 * The receiver accepts the message and returns without grabbing the queue
771 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
772 * are necessary. The same algorithm is used for sysv semaphores, see
773 * ipc/sem.c for more details.
774 *
775 * The same algorithm is used for senders.
776 */
777
778 /* pipelined_send() - send a message directly to the task waiting in
779 * sys_mq_timedreceive() (without inserting message into a queue).
780 */
781 static inline void pipelined_send(struct mqueue_inode_info *info,
782 struct msg_msg *message,
783 struct ext_wait_queue *receiver)
784 {
785 receiver->msg = message;
786 list_del(&receiver->list);
787 receiver->state = STATE_PENDING;
788 wake_up_process(receiver->task);
789 smp_wmb();
790 receiver->state = STATE_READY;
791 }
792
793 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
794 * gets its message and put to the queue (we have one free place for sure). */
795 static inline void pipelined_receive(struct mqueue_inode_info *info)
796 {
797 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
798
799 if (!sender) {
800 /* for poll */
801 wake_up_interruptible(&info->wait_q);
802 return;
803 }
804 msg_insert(sender->msg, info);
805 list_del(&sender->list);
806 sender->state = STATE_PENDING;
807 wake_up_process(sender->task);
808 smp_wmb();
809 sender->state = STATE_READY;
810 }
811
812 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
813 size_t msg_len, unsigned int msg_prio,
814 const struct timespec __user *u_abs_timeout)
815 {
816 struct file *filp;
817 struct inode *inode;
818 struct ext_wait_queue wait;
819 struct ext_wait_queue *receiver;
820 struct msg_msg *msg_ptr;
821 struct mqueue_inode_info *info;
822 long timeout;
823 int ret;
824
825 ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
826 if (ret != 0)
827 return ret;
828
829 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
830 return -EINVAL;
831
832 timeout = prepare_timeout(u_abs_timeout);
833
834 ret = -EBADF;
835 filp = fget(mqdes);
836 if (unlikely(!filp))
837 goto out;
838
839 inode = filp->f_path.dentry->d_inode;
840 if (unlikely(filp->f_op != &mqueue_file_operations))
841 goto out_fput;
842 info = MQUEUE_I(inode);
843 audit_inode(NULL, inode);
844
845 if (unlikely(!(filp->f_mode & FMODE_WRITE)))
846 goto out_fput;
847
848 if (unlikely(msg_len > info->attr.mq_msgsize)) {
849 ret = -EMSGSIZE;
850 goto out_fput;
851 }
852
853 /* First try to allocate memory, before doing anything with
854 * existing queues. */
855 msg_ptr = load_msg(u_msg_ptr, msg_len);
856 if (IS_ERR(msg_ptr)) {
857 ret = PTR_ERR(msg_ptr);
858 goto out_fput;
859 }
860 msg_ptr->m_ts = msg_len;
861 msg_ptr->m_type = msg_prio;
862
863 spin_lock(&info->lock);
864
865 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
866 if (filp->f_flags & O_NONBLOCK) {
867 spin_unlock(&info->lock);
868 ret = -EAGAIN;
869 } else if (unlikely(timeout < 0)) {
870 spin_unlock(&info->lock);
871 ret = timeout;
872 } else {
873 wait.task = current;
874 wait.msg = (void *) msg_ptr;
875 wait.state = STATE_NONE;
876 ret = wq_sleep(info, SEND, timeout, &wait);
877 }
878 if (ret < 0)
879 free_msg(msg_ptr);
880 } else {
881 receiver = wq_get_first_waiter(info, RECV);
882 if (receiver) {
883 pipelined_send(info, msg_ptr, receiver);
884 } else {
885 /* adds message to the queue */
886 msg_insert(msg_ptr, info);
887 __do_notify(info);
888 }
889 inode->i_atime = inode->i_mtime = inode->i_ctime =
890 CURRENT_TIME;
891 spin_unlock(&info->lock);
892 ret = 0;
893 }
894 out_fput:
895 fput(filp);
896 out:
897 return ret;
898 }
899
900 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
901 size_t msg_len, unsigned int __user *u_msg_prio,
902 const struct timespec __user *u_abs_timeout)
903 {
904 long timeout;
905 ssize_t ret;
906 struct msg_msg *msg_ptr;
907 struct file *filp;
908 struct inode *inode;
909 struct mqueue_inode_info *info;
910 struct ext_wait_queue wait;
911
912 ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
913 if (ret != 0)
914 return ret;
915
916 timeout = prepare_timeout(u_abs_timeout);
917
918 ret = -EBADF;
919 filp = fget(mqdes);
920 if (unlikely(!filp))
921 goto out;
922
923 inode = filp->f_path.dentry->d_inode;
924 if (unlikely(filp->f_op != &mqueue_file_operations))
925 goto out_fput;
926 info = MQUEUE_I(inode);
927 audit_inode(NULL, inode);
928
929 if (unlikely(!(filp->f_mode & FMODE_READ)))
930 goto out_fput;
931
932 /* checks if buffer is big enough */
933 if (unlikely(msg_len < info->attr.mq_msgsize)) {
934 ret = -EMSGSIZE;
935 goto out_fput;
936 }
937
938 spin_lock(&info->lock);
939 if (info->attr.mq_curmsgs == 0) {
940 if (filp->f_flags & O_NONBLOCK) {
941 spin_unlock(&info->lock);
942 ret = -EAGAIN;
943 msg_ptr = NULL;
944 } else if (unlikely(timeout < 0)) {
945 spin_unlock(&info->lock);
946 ret = timeout;
947 msg_ptr = NULL;
948 } else {
949 wait.task = current;
950 wait.state = STATE_NONE;
951 ret = wq_sleep(info, RECV, timeout, &wait);
952 msg_ptr = wait.msg;
953 }
954 } else {
955 msg_ptr = msg_get(info);
956
957 inode->i_atime = inode->i_mtime = inode->i_ctime =
958 CURRENT_TIME;
959
960 /* There is now free space in queue. */
961 pipelined_receive(info);
962 spin_unlock(&info->lock);
963 ret = 0;
964 }
965 if (ret == 0) {
966 ret = msg_ptr->m_ts;
967
968 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
969 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
970 ret = -EFAULT;
971 }
972 free_msg(msg_ptr);
973 }
974 out_fput:
975 fput(filp);
976 out:
977 return ret;
978 }
979
980 /*
981 * Notes: the case when user wants us to deregister (with NULL as pointer)
982 * and he isn't currently owner of notification, will be silently discarded.
983 * It isn't explicitly defined in the POSIX.
984 */
985 asmlinkage long sys_mq_notify(mqd_t mqdes,
986 const struct sigevent __user *u_notification)
987 {
988 int ret;
989 struct file *filp;
990 struct sock *sock;
991 struct inode *inode;
992 struct sigevent notification;
993 struct mqueue_inode_info *info;
994 struct sk_buff *nc;
995
996 ret = audit_mq_notify(mqdes, u_notification);
997 if (ret != 0)
998 return ret;
999
1000 nc = NULL;
1001 sock = NULL;
1002 if (u_notification != NULL) {
1003 if (copy_from_user(&notification, u_notification,
1004 sizeof(struct sigevent)))
1005 return -EFAULT;
1006
1007 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1008 notification.sigev_notify != SIGEV_SIGNAL &&
1009 notification.sigev_notify != SIGEV_THREAD))
1010 return -EINVAL;
1011 if (notification.sigev_notify == SIGEV_SIGNAL &&
1012 !valid_signal(notification.sigev_signo)) {
1013 return -EINVAL;
1014 }
1015 if (notification.sigev_notify == SIGEV_THREAD) {
1016 /* create the notify skb */
1017 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1018 ret = -ENOMEM;
1019 if (!nc)
1020 goto out;
1021 ret = -EFAULT;
1022 if (copy_from_user(nc->data,
1023 notification.sigev_value.sival_ptr,
1024 NOTIFY_COOKIE_LEN)) {
1025 goto out;
1026 }
1027
1028 /* TODO: add a header? */
1029 skb_put(nc, NOTIFY_COOKIE_LEN);
1030 /* and attach it to the socket */
1031 retry:
1032 filp = fget(notification.sigev_signo);
1033 ret = -EBADF;
1034 if (!filp)
1035 goto out;
1036 sock = netlink_getsockbyfilp(filp);
1037 fput(filp);
1038 if (IS_ERR(sock)) {
1039 ret = PTR_ERR(sock);
1040 sock = NULL;
1041 goto out;
1042 }
1043
1044 ret = netlink_attachskb(sock, nc, 0,
1045 MAX_SCHEDULE_TIMEOUT, NULL);
1046 if (ret == 1)
1047 goto retry;
1048 if (ret) {
1049 sock = NULL;
1050 nc = NULL;
1051 goto out;
1052 }
1053 }
1054 }
1055
1056 ret = -EBADF;
1057 filp = fget(mqdes);
1058 if (!filp)
1059 goto out;
1060
1061 inode = filp->f_path.dentry->d_inode;
1062 if (unlikely(filp->f_op != &mqueue_file_operations))
1063 goto out_fput;
1064 info = MQUEUE_I(inode);
1065
1066 ret = 0;
1067 spin_lock(&info->lock);
1068 if (u_notification == NULL) {
1069 if (info->notify_owner == task_tgid(current)) {
1070 remove_notification(info);
1071 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1072 }
1073 } else if (info->notify_owner != NULL) {
1074 ret = -EBUSY;
1075 } else {
1076 switch (notification.sigev_notify) {
1077 case SIGEV_NONE:
1078 info->notify.sigev_notify = SIGEV_NONE;
1079 break;
1080 case SIGEV_THREAD:
1081 info->notify_sock = sock;
1082 info->notify_cookie = nc;
1083 sock = NULL;
1084 nc = NULL;
1085 info->notify.sigev_notify = SIGEV_THREAD;
1086 break;
1087 case SIGEV_SIGNAL:
1088 info->notify.sigev_signo = notification.sigev_signo;
1089 info->notify.sigev_value = notification.sigev_value;
1090 info->notify.sigev_notify = SIGEV_SIGNAL;
1091 break;
1092 }
1093
1094 info->notify_owner = get_pid(task_tgid(current));
1095 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1096 }
1097 spin_unlock(&info->lock);
1098 out_fput:
1099 fput(filp);
1100 out:
1101 if (sock) {
1102 netlink_detachskb(sock, nc);
1103 } else if (nc) {
1104 dev_kfree_skb(nc);
1105 }
1106 return ret;
1107 }
1108
1109 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1110 const struct mq_attr __user *u_mqstat,
1111 struct mq_attr __user *u_omqstat)
1112 {
1113 int ret;
1114 struct mq_attr mqstat, omqstat;
1115 struct file *filp;
1116 struct inode *inode;
1117 struct mqueue_inode_info *info;
1118
1119 if (u_mqstat != NULL) {
1120 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1121 return -EFAULT;
1122 if (mqstat.mq_flags & (~O_NONBLOCK))
1123 return -EINVAL;
1124 }
1125
1126 ret = -EBADF;
1127 filp = fget(mqdes);
1128 if (!filp)
1129 goto out;
1130
1131 inode = filp->f_path.dentry->d_inode;
1132 if (unlikely(filp->f_op != &mqueue_file_operations))
1133 goto out_fput;
1134 info = MQUEUE_I(inode);
1135
1136 spin_lock(&info->lock);
1137
1138 omqstat = info->attr;
1139 omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1140 if (u_mqstat) {
1141 ret = audit_mq_getsetattr(mqdes, &mqstat);
1142 if (ret != 0)
1143 goto out;
1144 if (mqstat.mq_flags & O_NONBLOCK)
1145 filp->f_flags |= O_NONBLOCK;
1146 else
1147 filp->f_flags &= ~O_NONBLOCK;
1148
1149 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1150 }
1151
1152 spin_unlock(&info->lock);
1153
1154 ret = 0;
1155 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1156 sizeof(struct mq_attr)))
1157 ret = -EFAULT;
1158
1159 out_fput:
1160 fput(filp);
1161 out:
1162 return ret;
1163 }
1164
1165 static const struct inode_operations mqueue_dir_inode_operations = {
1166 .lookup = simple_lookup,
1167 .create = mqueue_create,
1168 .unlink = mqueue_unlink,
1169 };
1170
1171 static const struct file_operations mqueue_file_operations = {
1172 .flush = mqueue_flush_file,
1173 .poll = mqueue_poll_file,
1174 .read = mqueue_read_file,
1175 };
1176
1177 static struct super_operations mqueue_super_ops = {
1178 .alloc_inode = mqueue_alloc_inode,
1179 .destroy_inode = mqueue_destroy_inode,
1180 .statfs = simple_statfs,
1181 .delete_inode = mqueue_delete_inode,
1182 .drop_inode = generic_delete_inode,
1183 };
1184
1185 static struct file_system_type mqueue_fs_type = {
1186 .name = "mqueue",
1187 .get_sb = mqueue_get_sb,
1188 .kill_sb = kill_litter_super,
1189 };
1190
1191 static int msg_max_limit_min = DFLT_MSGMAX;
1192 static int msg_max_limit_max = HARD_MSGMAX;
1193
1194 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1195 static int msg_maxsize_limit_max = INT_MAX;
1196
1197 static ctl_table mq_sysctls[] = {
1198 {
1199 .ctl_name = CTL_QUEUESMAX,
1200 .procname = "queues_max",
1201 .data = &queues_max,
1202 .maxlen = sizeof(int),
1203 .mode = 0644,
1204 .proc_handler = &proc_dointvec,
1205 },
1206 {
1207 .ctl_name = CTL_MSGMAX,
1208 .procname = "msg_max",
1209 .data = &msg_max,
1210 .maxlen = sizeof(int),
1211 .mode = 0644,
1212 .proc_handler = &proc_dointvec_minmax,
1213 .extra1 = &msg_max_limit_min,
1214 .extra2 = &msg_max_limit_max,
1215 },
1216 {
1217 .ctl_name = CTL_MSGSIZEMAX,
1218 .procname = "msgsize_max",
1219 .data = &msgsize_max,
1220 .maxlen = sizeof(int),
1221 .mode = 0644,
1222 .proc_handler = &proc_dointvec_minmax,
1223 .extra1 = &msg_maxsize_limit_min,
1224 .extra2 = &msg_maxsize_limit_max,
1225 },
1226 { .ctl_name = 0 }
1227 };
1228
1229 static ctl_table mq_sysctl_dir[] = {
1230 {
1231 .ctl_name = FS_MQUEUE,
1232 .procname = "mqueue",
1233 .mode = 0555,
1234 .child = mq_sysctls,
1235 },
1236 { .ctl_name = 0 }
1237 };
1238
1239 static ctl_table mq_sysctl_root[] = {
1240 {
1241 .ctl_name = CTL_FS,
1242 .procname = "fs",
1243 .mode = 0555,
1244 .child = mq_sysctl_dir,
1245 },
1246 { .ctl_name = 0 }
1247 };
1248
1249 static int __init init_mqueue_fs(void)
1250 {
1251 int error;
1252
1253 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1254 sizeof(struct mqueue_inode_info), 0,
1255 SLAB_HWCACHE_ALIGN, init_once);
1256 if (mqueue_inode_cachep == NULL)
1257 return -ENOMEM;
1258
1259 /* ignore failues - they are not fatal */
1260 mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1261
1262 error = register_filesystem(&mqueue_fs_type);
1263 if (error)
1264 goto out_sysctl;
1265
1266 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1267 error = PTR_ERR(mqueue_mnt);
1268 goto out_filesystem;
1269 }
1270
1271 /* internal initialization - not common for vfs */
1272 queues_count = 0;
1273 spin_lock_init(&mq_lock);
1274
1275 return 0;
1276
1277 out_filesystem:
1278 unregister_filesystem(&mqueue_fs_type);
1279 out_sysctl:
1280 if (mq_sysctl_table)
1281 unregister_sysctl_table(mq_sysctl_table);
1282 kmem_cache_destroy(mqueue_inode_cachep);
1283 return error;
1284 }
1285
1286 __initcall(init_mqueue_fs);
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