Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6
[linux-2.6.git] / 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
35 #include <net/sock.h>
36 #include "util.h"
37
38 #define MQUEUE_MAGIC    0x19800202
39 #define DIRENT_SIZE     20
40 #define FILENT_SIZE     80
41
42 #define SEND            0
43 #define RECV            1
44
45 #define STATE_NONE      0
46 #define STATE_PENDING   1
47 #define STATE_READY     2
48
49 /* default values */
50 #define DFLT_QUEUESMAX  256     /* max number of message queues */
51 #define DFLT_MSGMAX     10      /* max number of messages in each queue */
52 #define HARD_MSGMAX     (131072/sizeof(void*))
53 #define DFLT_MSGSIZEMAX 8192    /* max message size */
54
55 /*
56  * Define the ranges various user-specified maximum values can
57  * be set to.
58  */
59 #define MIN_MSGMAX      1               /* min value for msg_max */
60 #define MAX_MSGMAX      HARD_MSGMAX     /* max value for msg_max */
61 #define MIN_MSGSIZEMAX  128             /* min value for msgsize_max */
62 #define MAX_MSGSIZEMAX  (8192*128)      /* max value for msgsize_max */
63
64 struct ext_wait_queue {         /* queue of sleeping tasks */
65         struct task_struct *task;
66         struct list_head list;
67         struct msg_msg *msg;    /* ptr of loaded message */
68         int state;              /* one of STATE_* values */
69 };
70
71 struct mqueue_inode_info {
72         spinlock_t lock;
73         struct inode vfs_inode;
74         wait_queue_head_t wait_q;
75
76         struct msg_msg **messages;
77         struct mq_attr attr;
78
79         struct sigevent notify;
80         struct pid* notify_owner;
81         struct user_struct *user;       /* user who created, for accounting */
82         struct sock *notify_sock;
83         struct sk_buff *notify_cookie;
84
85         /* for tasks waiting for free space and messages, respectively */
86         struct ext_wait_queue e_wait_q[2];
87
88         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
89 };
90
91 static const struct inode_operations mqueue_dir_inode_operations;
92 static const struct file_operations mqueue_file_operations;
93 static struct super_operations mqueue_super_ops;
94 static void remove_notification(struct mqueue_inode_info *info);
95
96 static spinlock_t mq_lock;
97 static struct kmem_cache *mqueue_inode_cachep;
98 static struct vfsmount *mqueue_mnt;
99
100 static unsigned int queues_count;
101 static unsigned int queues_max  = DFLT_QUEUESMAX;
102 static unsigned int msg_max     = DFLT_MSGMAX;
103 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
104
105 static struct ctl_table_header * mq_sysctl_table;
106
107 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
108 {
109         return container_of(inode, struct mqueue_inode_info, vfs_inode);
110 }
111
112 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
113                                                         struct mq_attr *attr)
114 {
115         struct user_struct *u = current_user();
116         struct inode *inode;
117
118         inode = new_inode(sb);
119         if (inode) {
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->messages = NULL;
140                         info->notify_owner = NULL;
141                         info->qsize = 0;
142                         info->user = NULL;      /* set when all is ok */
143                         memset(&info->attr, 0, sizeof(info->attr));
144                         info->attr.mq_maxmsg = msg_max;
145                         info->attr.mq_msgsize = msgsize_max;
146                         if (attr) {
147                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
148                                 info->attr.mq_msgsize = attr->mq_msgsize;
149                         }
150                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
151                         mq_bytes = (mq_msg_tblsz +
152                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
153
154                         spin_lock(&mq_lock);
155                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
156                             u->mq_bytes + mq_bytes >
157                             p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
158                                 spin_unlock(&mq_lock);
159                                 goto out_inode;
160                         }
161                         u->mq_bytes += mq_bytes;
162                         spin_unlock(&mq_lock);
163
164                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
165                         if (!info->messages) {
166                                 spin_lock(&mq_lock);
167                                 u->mq_bytes -= mq_bytes;
168                                 spin_unlock(&mq_lock);
169                                 goto out_inode;
170                         }
171                         /* all is ok */
172                         info->user = get_uid(u);
173                 } else if (S_ISDIR(mode)) {
174                         inc_nlink(inode);
175                         /* Some things misbehave if size == 0 on a directory */
176                         inode->i_size = 2 * DIRENT_SIZE;
177                         inode->i_op = &mqueue_dir_inode_operations;
178                         inode->i_fop = &simple_dir_operations;
179                 }
180         }
181         return inode;
182 out_inode:
183         make_bad_inode(inode);
184         iput(inode);
185         return NULL;
186 }
187
188 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
189 {
190         struct inode *inode;
191
192         sb->s_blocksize = PAGE_CACHE_SIZE;
193         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
194         sb->s_magic = MQUEUE_MAGIC;
195         sb->s_op = &mqueue_super_ops;
196
197         inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
198         if (!inode)
199                 return -ENOMEM;
200
201         sb->s_root = d_alloc_root(inode);
202         if (!sb->s_root) {
203                 iput(inode);
204                 return -ENOMEM;
205         }
206
207         return 0;
208 }
209
210 static int mqueue_get_sb(struct file_system_type *fs_type,
211                          int flags, const char *dev_name,
212                          void *data, struct vfsmount *mnt)
213 {
214         return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
215 }
216
217 static void init_once(void *foo)
218 {
219         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
220
221         inode_init_once(&p->vfs_inode);
222 }
223
224 static struct inode *mqueue_alloc_inode(struct super_block *sb)
225 {
226         struct mqueue_inode_info *ei;
227
228         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
229         if (!ei)
230                 return NULL;
231         return &ei->vfs_inode;
232 }
233
234 static void mqueue_destroy_inode(struct inode *inode)
235 {
236         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
237 }
238
239 static void mqueue_delete_inode(struct inode *inode)
240 {
241         struct mqueue_inode_info *info;
242         struct user_struct *user;
243         unsigned long mq_bytes;
244         int i;
245
246         if (S_ISDIR(inode->i_mode)) {
247                 clear_inode(inode);
248                 return;
249         }
250         info = MQUEUE_I(inode);
251         spin_lock(&info->lock);
252         for (i = 0; i < info->attr.mq_curmsgs; i++)
253                 free_msg(info->messages[i]);
254         kfree(info->messages);
255         spin_unlock(&info->lock);
256
257         clear_inode(inode);
258
259         mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
260                    (info->attr.mq_maxmsg * info->attr.mq_msgsize));
261         user = info->user;
262         if (user) {
263                 spin_lock(&mq_lock);
264                 user->mq_bytes -= mq_bytes;
265                 queues_count--;
266                 spin_unlock(&mq_lock);
267                 free_uid(user);
268         }
269 }
270
271 static int mqueue_create(struct inode *dir, struct dentry *dentry,
272                                 int mode, struct nameidata *nd)
273 {
274         struct inode *inode;
275         struct mq_attr *attr = dentry->d_fsdata;
276         int error;
277
278         spin_lock(&mq_lock);
279         if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
280                 error = -ENOSPC;
281                 goto out_lock;
282         }
283         queues_count++;
284         spin_unlock(&mq_lock);
285
286         inode = mqueue_get_inode(dir->i_sb, mode, attr);
287         if (!inode) {
288                 error = -ENOMEM;
289                 spin_lock(&mq_lock);
290                 queues_count--;
291                 goto out_lock;
292         }
293
294         dir->i_size += DIRENT_SIZE;
295         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
296
297         d_instantiate(dentry, inode);
298         dget(dentry);
299         return 0;
300 out_lock:
301         spin_unlock(&mq_lock);
302         return error;
303 }
304
305 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
306 {
307         struct inode *inode = dentry->d_inode;
308
309         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
310         dir->i_size -= DIRENT_SIZE;
311         drop_nlink(inode);
312         dput(dentry);
313         return 0;
314 }
315
316 /*
317 *       This is routine for system read from queue file.
318 *       To avoid mess with doing here some sort of mq_receive we allow
319 *       to read only queue size & notification info (the only values
320 *       that are interesting from user point of view and aren't accessible
321 *       through std routines)
322 */
323 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
324                                 size_t count, loff_t *off)
325 {
326         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
327         char buffer[FILENT_SIZE];
328         ssize_t ret;
329
330         spin_lock(&info->lock);
331         snprintf(buffer, sizeof(buffer),
332                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
333                         info->qsize,
334                         info->notify_owner ? info->notify.sigev_notify : 0,
335                         (info->notify_owner &&
336                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
337                                 info->notify.sigev_signo : 0,
338                         pid_vnr(info->notify_owner));
339         spin_unlock(&info->lock);
340         buffer[sizeof(buffer)-1] = '\0';
341
342         ret = simple_read_from_buffer(u_data, count, off, buffer,
343                                 strlen(buffer));
344         if (ret <= 0)
345                 return ret;
346
347         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
348         return ret;
349 }
350
351 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
352 {
353         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
354
355         spin_lock(&info->lock);
356         if (task_tgid(current) == info->notify_owner)
357                 remove_notification(info);
358
359         spin_unlock(&info->lock);
360         return 0;
361 }
362
363 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
364 {
365         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
366         int retval = 0;
367
368         poll_wait(filp, &info->wait_q, poll_tab);
369
370         spin_lock(&info->lock);
371         if (info->attr.mq_curmsgs)
372                 retval = POLLIN | POLLRDNORM;
373
374         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
375                 retval |= POLLOUT | POLLWRNORM;
376         spin_unlock(&info->lock);
377
378         return retval;
379 }
380
381 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
382 static void wq_add(struct mqueue_inode_info *info, int sr,
383                         struct ext_wait_queue *ewp)
384 {
385         struct ext_wait_queue *walk;
386
387         ewp->task = current;
388
389         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
390                 if (walk->task->static_prio <= current->static_prio) {
391                         list_add_tail(&ewp->list, &walk->list);
392                         return;
393                 }
394         }
395         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
396 }
397
398 /*
399  * Puts current task to sleep. Caller must hold queue lock. After return
400  * lock isn't held.
401  * sr: SEND or RECV
402  */
403 static int wq_sleep(struct mqueue_inode_info *info, int sr,
404                         long timeout, struct ext_wait_queue *ewp)
405 {
406         int retval;
407         signed long time;
408
409         wq_add(info, sr, ewp);
410
411         for (;;) {
412                 set_current_state(TASK_INTERRUPTIBLE);
413
414                 spin_unlock(&info->lock);
415                 time = schedule_timeout(timeout);
416
417                 while (ewp->state == STATE_PENDING)
418                         cpu_relax();
419
420                 if (ewp->state == STATE_READY) {
421                         retval = 0;
422                         goto out;
423                 }
424                 spin_lock(&info->lock);
425                 if (ewp->state == STATE_READY) {
426                         retval = 0;
427                         goto out_unlock;
428                 }
429                 if (signal_pending(current)) {
430                         retval = -ERESTARTSYS;
431                         break;
432                 }
433                 if (time == 0) {
434                         retval = -ETIMEDOUT;
435                         break;
436                 }
437         }
438         list_del(&ewp->list);
439 out_unlock:
440         spin_unlock(&info->lock);
441 out:
442         return retval;
443 }
444
445 /*
446  * Returns waiting task that should be serviced first or NULL if none exists
447  */
448 static struct ext_wait_queue *wq_get_first_waiter(
449                 struct mqueue_inode_info *info, int sr)
450 {
451         struct list_head *ptr;
452
453         ptr = info->e_wait_q[sr].list.prev;
454         if (ptr == &info->e_wait_q[sr].list)
455                 return NULL;
456         return list_entry(ptr, struct ext_wait_queue, list);
457 }
458
459 /* Auxiliary functions to manipulate messages' list */
460 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
461 {
462         int k;
463
464         k = info->attr.mq_curmsgs - 1;
465         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
466                 info->messages[k + 1] = info->messages[k];
467                 k--;
468         }
469         info->attr.mq_curmsgs++;
470         info->qsize += ptr->m_ts;
471         info->messages[k + 1] = ptr;
472 }
473
474 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
475 {
476         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
477         return info->messages[info->attr.mq_curmsgs];
478 }
479
480 static inline void set_cookie(struct sk_buff *skb, char code)
481 {
482         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
483 }
484
485 /*
486  * The next function is only to split too long sys_mq_timedsend
487  */
488 static void __do_notify(struct mqueue_inode_info *info)
489 {
490         /* notification
491          * invoked when there is registered process and there isn't process
492          * waiting synchronously for message AND state of queue changed from
493          * empty to not empty. Here we are sure that no one is waiting
494          * synchronously. */
495         if (info->notify_owner &&
496             info->attr.mq_curmsgs == 1) {
497                 struct siginfo sig_i;
498                 switch (info->notify.sigev_notify) {
499                 case SIGEV_NONE:
500                         break;
501                 case SIGEV_SIGNAL:
502                         /* sends signal */
503
504                         sig_i.si_signo = info->notify.sigev_signo;
505                         sig_i.si_errno = 0;
506                         sig_i.si_code = SI_MESGQ;
507                         sig_i.si_value = info->notify.sigev_value;
508                         sig_i.si_pid = task_tgid_vnr(current);
509                         sig_i.si_uid = current_uid();
510
511                         kill_pid_info(info->notify.sigev_signo,
512                                       &sig_i, info->notify_owner);
513                         break;
514                 case SIGEV_THREAD:
515                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
516                         netlink_sendskb(info->notify_sock, info->notify_cookie);
517                         break;
518                 }
519                 /* after notification unregisters process */
520                 put_pid(info->notify_owner);
521                 info->notify_owner = NULL;
522         }
523         wake_up(&info->wait_q);
524 }
525
526 static long prepare_timeout(struct timespec *p)
527 {
528         struct timespec nowts;
529         long timeout;
530
531         if (p) {
532                 if (unlikely(p->tv_nsec < 0 || p->tv_sec < 0
533                         || p->tv_nsec >= NSEC_PER_SEC))
534                         return -EINVAL;
535                 nowts = CURRENT_TIME;
536                 /* first subtract as jiffies can't be too big */
537                 p->tv_sec -= nowts.tv_sec;
538                 if (p->tv_nsec < nowts.tv_nsec) {
539                         p->tv_nsec += NSEC_PER_SEC;
540                         p->tv_sec--;
541                 }
542                 p->tv_nsec -= nowts.tv_nsec;
543                 if (p->tv_sec < 0)
544                         return 0;
545
546                 timeout = timespec_to_jiffies(p) + 1;
547         } else
548                 return MAX_SCHEDULE_TIMEOUT;
549
550         return timeout;
551 }
552
553 static void remove_notification(struct mqueue_inode_info *info)
554 {
555         if (info->notify_owner != NULL &&
556             info->notify.sigev_notify == SIGEV_THREAD) {
557                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
558                 netlink_sendskb(info->notify_sock, info->notify_cookie);
559         }
560         put_pid(info->notify_owner);
561         info->notify_owner = NULL;
562 }
563
564 static int mq_attr_ok(struct mq_attr *attr)
565 {
566         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
567                 return 0;
568         if (capable(CAP_SYS_RESOURCE)) {
569                 if (attr->mq_maxmsg > HARD_MSGMAX)
570                         return 0;
571         } else {
572                 if (attr->mq_maxmsg > msg_max ||
573                                 attr->mq_msgsize > msgsize_max)
574                         return 0;
575         }
576         /* check for overflow */
577         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
578                 return 0;
579         if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
580             (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
581             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
582                 return 0;
583         return 1;
584 }
585
586 /*
587  * Invoked when creating a new queue via sys_mq_open
588  */
589 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
590                         int oflag, mode_t mode, struct mq_attr *attr)
591 {
592         const struct cred *cred = current_cred();
593         struct file *result;
594         int ret;
595
596         if (attr) {
597                 ret = -EINVAL;
598                 if (!mq_attr_ok(attr))
599                         goto out;
600                 /* store for use during create */
601                 dentry->d_fsdata = attr;
602         }
603
604         mode &= ~current->fs->umask;
605         ret = mnt_want_write(mqueue_mnt);
606         if (ret)
607                 goto out;
608         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
609         dentry->d_fsdata = NULL;
610         if (ret)
611                 goto out_drop_write;
612
613         result = dentry_open(dentry, mqueue_mnt, oflag, cred);
614         /*
615          * dentry_open() took a persistent mnt_want_write(),
616          * so we can now drop this one.
617          */
618         mnt_drop_write(mqueue_mnt);
619         return result;
620
621 out_drop_write:
622         mnt_drop_write(mqueue_mnt);
623 out:
624         dput(dentry);
625         mntput(mqueue_mnt);
626         return ERR_PTR(ret);
627 }
628
629 /* Opens existing queue */
630 static struct file *do_open(struct dentry *dentry, int oflag)
631 {
632         const struct cred *cred = current_cred();
633
634         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
635                                                   MAY_READ | MAY_WRITE };
636
637         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
638                 dput(dentry);
639                 mntput(mqueue_mnt);
640                 return ERR_PTR(-EINVAL);
641         }
642
643         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
644                 dput(dentry);
645                 mntput(mqueue_mnt);
646                 return ERR_PTR(-EACCES);
647         }
648
649         return dentry_open(dentry, mqueue_mnt, oflag, cred);
650 }
651
652 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
653                                 struct mq_attr __user *u_attr)
654 {
655         struct dentry *dentry;
656         struct file *filp;
657         char *name;
658         struct mq_attr attr;
659         int fd, error;
660
661         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
662                 return -EFAULT;
663
664         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
665
666         if (IS_ERR(name = getname(u_name)))
667                 return PTR_ERR(name);
668
669         fd = get_unused_fd_flags(O_CLOEXEC);
670         if (fd < 0)
671                 goto out_putname;
672
673         mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
674         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
675         if (IS_ERR(dentry)) {
676                 error = PTR_ERR(dentry);
677                 goto out_err;
678         }
679         mntget(mqueue_mnt);
680
681         if (oflag & O_CREAT) {
682                 if (dentry->d_inode) {  /* entry already exists */
683                         audit_inode(name, dentry);
684                         error = -EEXIST;
685                         if (oflag & O_EXCL)
686                                 goto out;
687                         filp = do_open(dentry, oflag);
688                 } else {
689                         filp = do_create(mqueue_mnt->mnt_root, dentry,
690                                                 oflag, mode,
691                                                 u_attr ? &attr : NULL);
692                 }
693         } else {
694                 error = -ENOENT;
695                 if (!dentry->d_inode)
696                         goto out;
697                 audit_inode(name, dentry);
698                 filp = do_open(dentry, oflag);
699         }
700
701         if (IS_ERR(filp)) {
702                 error = PTR_ERR(filp);
703                 goto out_putfd;
704         }
705
706         fd_install(fd, filp);
707         goto out_upsem;
708
709 out:
710         dput(dentry);
711         mntput(mqueue_mnt);
712 out_putfd:
713         put_unused_fd(fd);
714 out_err:
715         fd = error;
716 out_upsem:
717         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
718 out_putname:
719         putname(name);
720         return fd;
721 }
722
723 asmlinkage long sys_mq_unlink(const char __user *u_name)
724 {
725         int err;
726         char *name;
727         struct dentry *dentry;
728         struct inode *inode = NULL;
729
730         name = getname(u_name);
731         if (IS_ERR(name))
732                 return PTR_ERR(name);
733
734         mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
735                         I_MUTEX_PARENT);
736         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
737         if (IS_ERR(dentry)) {
738                 err = PTR_ERR(dentry);
739                 goto out_unlock;
740         }
741
742         if (!dentry->d_inode) {
743                 err = -ENOENT;
744                 goto out_err;
745         }
746
747         inode = dentry->d_inode;
748         if (inode)
749                 atomic_inc(&inode->i_count);
750         err = mnt_want_write(mqueue_mnt);
751         if (err)
752                 goto out_err;
753         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
754         mnt_drop_write(mqueue_mnt);
755 out_err:
756         dput(dentry);
757
758 out_unlock:
759         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
760         putname(name);
761         if (inode)
762                 iput(inode);
763
764         return err;
765 }
766
767 /* Pipelined send and receive functions.
768  *
769  * If a receiver finds no waiting message, then it registers itself in the
770  * list of waiting receivers. A sender checks that list before adding the new
771  * message into the message array. If there is a waiting receiver, then it
772  * bypasses the message array and directly hands the message over to the
773  * receiver.
774  * The receiver accepts the message and returns without grabbing the queue
775  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
776  * are necessary. The same algorithm is used for sysv semaphores, see
777  * ipc/sem.c for more details.
778  *
779  * The same algorithm is used for senders.
780  */
781
782 /* pipelined_send() - send a message directly to the task waiting in
783  * sys_mq_timedreceive() (without inserting message into a queue).
784  */
785 static inline void pipelined_send(struct mqueue_inode_info *info,
786                                   struct msg_msg *message,
787                                   struct ext_wait_queue *receiver)
788 {
789         receiver->msg = message;
790         list_del(&receiver->list);
791         receiver->state = STATE_PENDING;
792         wake_up_process(receiver->task);
793         smp_wmb();
794         receiver->state = STATE_READY;
795 }
796
797 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
798  * gets its message and put to the queue (we have one free place for sure). */
799 static inline void pipelined_receive(struct mqueue_inode_info *info)
800 {
801         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
802
803         if (!sender) {
804                 /* for poll */
805                 wake_up_interruptible(&info->wait_q);
806                 return;
807         }
808         msg_insert(sender->msg, info);
809         list_del(&sender->list);
810         sender->state = STATE_PENDING;
811         wake_up_process(sender->task);
812         smp_wmb();
813         sender->state = STATE_READY;
814 }
815
816 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
817         size_t msg_len, unsigned int msg_prio,
818         const struct timespec __user *u_abs_timeout)
819 {
820         struct file *filp;
821         struct inode *inode;
822         struct ext_wait_queue wait;
823         struct ext_wait_queue *receiver;
824         struct msg_msg *msg_ptr;
825         struct mqueue_inode_info *info;
826         struct timespec ts, *p = NULL;
827         long timeout;
828         int ret;
829
830         if (u_abs_timeout) {
831                 if (copy_from_user(&ts, u_abs_timeout, 
832                                         sizeof(struct timespec)))
833                         return -EFAULT;
834                 p = &ts;
835         }
836
837         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
838                 return -EINVAL;
839
840         audit_mq_sendrecv(mqdes, msg_len, msg_prio, p);
841         timeout = prepare_timeout(p);
842
843         ret = -EBADF;
844         filp = fget(mqdes);
845         if (unlikely(!filp))
846                 goto out;
847
848         inode = filp->f_path.dentry->d_inode;
849         if (unlikely(filp->f_op != &mqueue_file_operations))
850                 goto out_fput;
851         info = MQUEUE_I(inode);
852         audit_inode(NULL, filp->f_path.dentry);
853
854         if (unlikely(!(filp->f_mode & FMODE_WRITE)))
855                 goto out_fput;
856
857         if (unlikely(msg_len > info->attr.mq_msgsize)) {
858                 ret = -EMSGSIZE;
859                 goto out_fput;
860         }
861
862         /* First try to allocate memory, before doing anything with
863          * existing queues. */
864         msg_ptr = load_msg(u_msg_ptr, msg_len);
865         if (IS_ERR(msg_ptr)) {
866                 ret = PTR_ERR(msg_ptr);
867                 goto out_fput;
868         }
869         msg_ptr->m_ts = msg_len;
870         msg_ptr->m_type = msg_prio;
871
872         spin_lock(&info->lock);
873
874         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
875                 if (filp->f_flags & O_NONBLOCK) {
876                         spin_unlock(&info->lock);
877                         ret = -EAGAIN;
878                 } else if (unlikely(timeout < 0)) {
879                         spin_unlock(&info->lock);
880                         ret = timeout;
881                 } else {
882                         wait.task = current;
883                         wait.msg = (void *) msg_ptr;
884                         wait.state = STATE_NONE;
885                         ret = wq_sleep(info, SEND, timeout, &wait);
886                 }
887                 if (ret < 0)
888                         free_msg(msg_ptr);
889         } else {
890                 receiver = wq_get_first_waiter(info, RECV);
891                 if (receiver) {
892                         pipelined_send(info, msg_ptr, receiver);
893                 } else {
894                         /* adds message to the queue */
895                         msg_insert(msg_ptr, info);
896                         __do_notify(info);
897                 }
898                 inode->i_atime = inode->i_mtime = inode->i_ctime =
899                                 CURRENT_TIME;
900                 spin_unlock(&info->lock);
901                 ret = 0;
902         }
903 out_fput:
904         fput(filp);
905 out:
906         return ret;
907 }
908
909 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
910         size_t msg_len, unsigned int __user *u_msg_prio,
911         const struct timespec __user *u_abs_timeout)
912 {
913         long timeout;
914         ssize_t ret;
915         struct msg_msg *msg_ptr;
916         struct file *filp;
917         struct inode *inode;
918         struct mqueue_inode_info *info;
919         struct ext_wait_queue wait;
920         struct timespec ts, *p = NULL;
921
922         if (u_abs_timeout) {
923                 if (copy_from_user(&ts, u_abs_timeout, 
924                                         sizeof(struct timespec)))
925                         return -EFAULT;
926                 p = &ts;
927         }
928
929         audit_mq_sendrecv(mqdes, msg_len, 0, p);
930         timeout = prepare_timeout(p);
931
932         ret = -EBADF;
933         filp = fget(mqdes);
934         if (unlikely(!filp))
935                 goto out;
936
937         inode = filp->f_path.dentry->d_inode;
938         if (unlikely(filp->f_op != &mqueue_file_operations))
939                 goto out_fput;
940         info = MQUEUE_I(inode);
941         audit_inode(NULL, filp->f_path.dentry);
942
943         if (unlikely(!(filp->f_mode & FMODE_READ)))
944                 goto out_fput;
945
946         /* checks if buffer is big enough */
947         if (unlikely(msg_len < info->attr.mq_msgsize)) {
948                 ret = -EMSGSIZE;
949                 goto out_fput;
950         }
951
952         spin_lock(&info->lock);
953         if (info->attr.mq_curmsgs == 0) {
954                 if (filp->f_flags & O_NONBLOCK) {
955                         spin_unlock(&info->lock);
956                         ret = -EAGAIN;
957                         msg_ptr = NULL;
958                 } else if (unlikely(timeout < 0)) {
959                         spin_unlock(&info->lock);
960                         ret = timeout;
961                         msg_ptr = NULL;
962                 } else {
963                         wait.task = current;
964                         wait.state = STATE_NONE;
965                         ret = wq_sleep(info, RECV, timeout, &wait);
966                         msg_ptr = wait.msg;
967                 }
968         } else {
969                 msg_ptr = msg_get(info);
970
971                 inode->i_atime = inode->i_mtime = inode->i_ctime =
972                                 CURRENT_TIME;
973
974                 /* There is now free space in queue. */
975                 pipelined_receive(info);
976                 spin_unlock(&info->lock);
977                 ret = 0;
978         }
979         if (ret == 0) {
980                 ret = msg_ptr->m_ts;
981
982                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
983                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
984                         ret = -EFAULT;
985                 }
986                 free_msg(msg_ptr);
987         }
988 out_fput:
989         fput(filp);
990 out:
991         return ret;
992 }
993
994 /*
995  * Notes: the case when user wants us to deregister (with NULL as pointer)
996  * and he isn't currently owner of notification, will be silently discarded.
997  * It isn't explicitly defined in the POSIX.
998  */
999 asmlinkage long sys_mq_notify(mqd_t mqdes,
1000                                 const struct sigevent __user *u_notification)
1001 {
1002         int ret;
1003         struct file *filp;
1004         struct sock *sock;
1005         struct inode *inode;
1006         struct sigevent notification;
1007         struct mqueue_inode_info *info;
1008         struct sk_buff *nc;
1009
1010         if (u_notification) {
1011                 if (copy_from_user(&notification, u_notification,
1012                                         sizeof(struct sigevent)))
1013                         return -EFAULT;
1014         }
1015
1016         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1017
1018         nc = NULL;
1019         sock = NULL;
1020         if (u_notification != NULL) {
1021                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1022                              notification.sigev_notify != SIGEV_SIGNAL &&
1023                              notification.sigev_notify != SIGEV_THREAD))
1024                         return -EINVAL;
1025                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1026                         !valid_signal(notification.sigev_signo)) {
1027                         return -EINVAL;
1028                 }
1029                 if (notification.sigev_notify == SIGEV_THREAD) {
1030                         long timeo;
1031
1032                         /* create the notify skb */
1033                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1034                         ret = -ENOMEM;
1035                         if (!nc)
1036                                 goto out;
1037                         ret = -EFAULT;
1038                         if (copy_from_user(nc->data,
1039                                         notification.sigev_value.sival_ptr,
1040                                         NOTIFY_COOKIE_LEN)) {
1041                                 goto out;
1042                         }
1043
1044                         /* TODO: add a header? */
1045                         skb_put(nc, NOTIFY_COOKIE_LEN);
1046                         /* and attach it to the socket */
1047 retry:
1048                         filp = fget(notification.sigev_signo);
1049                         ret = -EBADF;
1050                         if (!filp)
1051                                 goto out;
1052                         sock = netlink_getsockbyfilp(filp);
1053                         fput(filp);
1054                         if (IS_ERR(sock)) {
1055                                 ret = PTR_ERR(sock);
1056                                 sock = NULL;
1057                                 goto out;
1058                         }
1059
1060                         timeo = MAX_SCHEDULE_TIMEOUT;
1061                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1062                         if (ret == 1)
1063                                 goto retry;
1064                         if (ret) {
1065                                 sock = NULL;
1066                                 nc = NULL;
1067                                 goto out;
1068                         }
1069                 }
1070         }
1071
1072         ret = -EBADF;
1073         filp = fget(mqdes);
1074         if (!filp)
1075                 goto out;
1076
1077         inode = filp->f_path.dentry->d_inode;
1078         if (unlikely(filp->f_op != &mqueue_file_operations))
1079                 goto out_fput;
1080         info = MQUEUE_I(inode);
1081
1082         ret = 0;
1083         spin_lock(&info->lock);
1084         if (u_notification == NULL) {
1085                 if (info->notify_owner == task_tgid(current)) {
1086                         remove_notification(info);
1087                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1088                 }
1089         } else if (info->notify_owner != NULL) {
1090                 ret = -EBUSY;
1091         } else {
1092                 switch (notification.sigev_notify) {
1093                 case SIGEV_NONE:
1094                         info->notify.sigev_notify = SIGEV_NONE;
1095                         break;
1096                 case SIGEV_THREAD:
1097                         info->notify_sock = sock;
1098                         info->notify_cookie = nc;
1099                         sock = NULL;
1100                         nc = NULL;
1101                         info->notify.sigev_notify = SIGEV_THREAD;
1102                         break;
1103                 case SIGEV_SIGNAL:
1104                         info->notify.sigev_signo = notification.sigev_signo;
1105                         info->notify.sigev_value = notification.sigev_value;
1106                         info->notify.sigev_notify = SIGEV_SIGNAL;
1107                         break;
1108                 }
1109
1110                 info->notify_owner = get_pid(task_tgid(current));
1111                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1112         }
1113         spin_unlock(&info->lock);
1114 out_fput:
1115         fput(filp);
1116 out:
1117         if (sock) {
1118                 netlink_detachskb(sock, nc);
1119         } else if (nc) {
1120                 dev_kfree_skb(nc);
1121         }
1122         return ret;
1123 }
1124
1125 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1126                         const struct mq_attr __user *u_mqstat,
1127                         struct mq_attr __user *u_omqstat)
1128 {
1129         int ret;
1130         struct mq_attr mqstat, omqstat;
1131         struct file *filp;
1132         struct inode *inode;
1133         struct mqueue_inode_info *info;
1134
1135         if (u_mqstat != NULL) {
1136                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1137                         return -EFAULT;
1138                 if (mqstat.mq_flags & (~O_NONBLOCK))
1139                         return -EINVAL;
1140         }
1141
1142         ret = -EBADF;
1143         filp = fget(mqdes);
1144         if (!filp)
1145                 goto out;
1146
1147         inode = filp->f_path.dentry->d_inode;
1148         if (unlikely(filp->f_op != &mqueue_file_operations))
1149                 goto out_fput;
1150         info = MQUEUE_I(inode);
1151
1152         spin_lock(&info->lock);
1153
1154         omqstat = info->attr;
1155         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1156         if (u_mqstat) {
1157                 audit_mq_getsetattr(mqdes, &mqstat);
1158                 if (mqstat.mq_flags & O_NONBLOCK)
1159                         filp->f_flags |= O_NONBLOCK;
1160                 else
1161                         filp->f_flags &= ~O_NONBLOCK;
1162
1163                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1164         }
1165
1166         spin_unlock(&info->lock);
1167
1168         ret = 0;
1169         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1170                                                 sizeof(struct mq_attr)))
1171                 ret = -EFAULT;
1172
1173 out_fput:
1174         fput(filp);
1175 out:
1176         return ret;
1177 }
1178
1179 static const struct inode_operations mqueue_dir_inode_operations = {
1180         .lookup = simple_lookup,
1181         .create = mqueue_create,
1182         .unlink = mqueue_unlink,
1183 };
1184
1185 static const struct file_operations mqueue_file_operations = {
1186         .flush = mqueue_flush_file,
1187         .poll = mqueue_poll_file,
1188         .read = mqueue_read_file,
1189 };
1190
1191 static struct super_operations mqueue_super_ops = {
1192         .alloc_inode = mqueue_alloc_inode,
1193         .destroy_inode = mqueue_destroy_inode,
1194         .statfs = simple_statfs,
1195         .delete_inode = mqueue_delete_inode,
1196         .drop_inode = generic_delete_inode,
1197 };
1198
1199 static struct file_system_type mqueue_fs_type = {
1200         .name = "mqueue",
1201         .get_sb = mqueue_get_sb,
1202         .kill_sb = kill_litter_super,
1203 };
1204
1205 static int msg_max_limit_min = MIN_MSGMAX;
1206 static int msg_max_limit_max = MAX_MSGMAX;
1207
1208 static int msg_maxsize_limit_min = MIN_MSGSIZEMAX;
1209 static int msg_maxsize_limit_max = MAX_MSGSIZEMAX;
1210
1211 static ctl_table mq_sysctls[] = {
1212         {
1213                 .procname       = "queues_max",
1214                 .data           = &queues_max,
1215                 .maxlen         = sizeof(int),
1216                 .mode           = 0644,
1217                 .proc_handler   = &proc_dointvec,
1218         },
1219         {
1220                 .procname       = "msg_max",
1221                 .data           = &msg_max,
1222                 .maxlen         = sizeof(int),
1223                 .mode           = 0644,
1224                 .proc_handler   = &proc_dointvec_minmax,
1225                 .extra1         = &msg_max_limit_min,
1226                 .extra2         = &msg_max_limit_max,
1227         },
1228         {
1229                 .procname       = "msgsize_max",
1230                 .data           = &msgsize_max,
1231                 .maxlen         = sizeof(int),
1232                 .mode           = 0644,
1233                 .proc_handler   = &proc_dointvec_minmax,
1234                 .extra1         = &msg_maxsize_limit_min,
1235                 .extra2         = &msg_maxsize_limit_max,
1236         },
1237         { .ctl_name = 0 }
1238 };
1239
1240 static ctl_table mq_sysctl_dir[] = {
1241         {
1242                 .procname       = "mqueue",
1243                 .mode           = 0555,
1244                 .child          = mq_sysctls,
1245         },
1246         { .ctl_name = 0 }
1247 };
1248
1249 static ctl_table mq_sysctl_root[] = {
1250         {
1251                 .ctl_name       = CTL_FS,
1252                 .procname       = "fs",
1253                 .mode           = 0555,
1254                 .child          = mq_sysctl_dir,
1255         },
1256         { .ctl_name = 0 }
1257 };
1258
1259 static int __init init_mqueue_fs(void)
1260 {
1261         int error;
1262
1263         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1264                                 sizeof(struct mqueue_inode_info), 0,
1265                                 SLAB_HWCACHE_ALIGN, init_once);
1266         if (mqueue_inode_cachep == NULL)
1267                 return -ENOMEM;
1268
1269         /* ignore failues - they are not fatal */
1270         mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1271
1272         error = register_filesystem(&mqueue_fs_type);
1273         if (error)
1274                 goto out_sysctl;
1275
1276         if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1277                 error = PTR_ERR(mqueue_mnt);
1278                 goto out_filesystem;
1279         }
1280
1281         /* internal initialization - not common for vfs */
1282         queues_count = 0;
1283         spin_lock_init(&mq_lock);
1284
1285         return 0;
1286
1287 out_filesystem:
1288         unregister_filesystem(&mqueue_fs_type);
1289 out_sysctl:
1290         if (mq_sysctl_table)
1291                 unregister_sysctl_table(mq_sysctl_table);
1292         kmem_cache_destroy(mqueue_inode_cachep);
1293         return error;
1294 }
1295
1296 __initcall(init_mqueue_fs);