sysvipc: fix the ipc structures initialization
[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 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_blocks = 0;
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                         struct user_struct *u = p->user;
130                         unsigned long mq_bytes, mq_msg_tblsz;
131
132                         inode->i_fop = &mqueue_file_operations;
133                         inode->i_size = FILENT_SIZE;
134                         /* mqueue specific info */
135                         info = MQUEUE_I(inode);
136                         spin_lock_init(&info->lock);
137                         init_waitqueue_head(&info->wait_q);
138                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
139                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
140                         info->messages = NULL;
141                         info->notify_owner = NULL;
142                         info->qsize = 0;
143                         info->user = NULL;      /* set when all is ok */
144                         memset(&info->attr, 0, sizeof(info->attr));
145                         info->attr.mq_maxmsg = msg_max;
146                         info->attr.mq_msgsize = msgsize_max;
147                         if (attr) {
148                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
149                                 info->attr.mq_msgsize = attr->mq_msgsize;
150                         }
151                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
152                         mq_bytes = (mq_msg_tblsz +
153                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
154
155                         spin_lock(&mq_lock);
156                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
157                             u->mq_bytes + mq_bytes >
158                             p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
159                                 spin_unlock(&mq_lock);
160                                 goto out_inode;
161                         }
162                         u->mq_bytes += mq_bytes;
163                         spin_unlock(&mq_lock);
164
165                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
166                         if (!info->messages) {
167                                 spin_lock(&mq_lock);
168                                 u->mq_bytes -= mq_bytes;
169                                 spin_unlock(&mq_lock);
170                                 goto out_inode;
171                         }
172                         /* all is ok */
173                         info->user = get_uid(u);
174                 } else if (S_ISDIR(mode)) {
175                         inc_nlink(inode);
176                         /* Some things misbehave if size == 0 on a directory */
177                         inode->i_size = 2 * DIRENT_SIZE;
178                         inode->i_op = &mqueue_dir_inode_operations;
179                         inode->i_fop = &simple_dir_operations;
180                 }
181         }
182         return inode;
183 out_inode:
184         make_bad_inode(inode);
185         iput(inode);
186         return NULL;
187 }
188
189 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
190 {
191         struct inode *inode;
192
193         sb->s_blocksize = PAGE_CACHE_SIZE;
194         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
195         sb->s_magic = MQUEUE_MAGIC;
196         sb->s_op = &mqueue_super_ops;
197
198         inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
199         if (!inode)
200                 return -ENOMEM;
201
202         sb->s_root = d_alloc_root(inode);
203         if (!sb->s_root) {
204                 iput(inode);
205                 return -ENOMEM;
206         }
207
208         return 0;
209 }
210
211 static int mqueue_get_sb(struct file_system_type *fs_type,
212                          int flags, const char *dev_name,
213                          void *data, struct vfsmount *mnt)
214 {
215         return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
216 }
217
218 static void init_once(void *foo)
219 {
220         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
221
222         inode_init_once(&p->vfs_inode);
223 }
224
225 static struct inode *mqueue_alloc_inode(struct super_block *sb)
226 {
227         struct mqueue_inode_info *ei;
228
229         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
230         if (!ei)
231                 return NULL;
232         return &ei->vfs_inode;
233 }
234
235 static void mqueue_destroy_inode(struct inode *inode)
236 {
237         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
238 }
239
240 static void mqueue_delete_inode(struct inode *inode)
241 {
242         struct mqueue_inode_info *info;
243         struct user_struct *user;
244         unsigned long mq_bytes;
245         int i;
246
247         if (S_ISDIR(inode->i_mode)) {
248                 clear_inode(inode);
249                 return;
250         }
251         info = MQUEUE_I(inode);
252         spin_lock(&info->lock);
253         for (i = 0; i < info->attr.mq_curmsgs; i++)
254                 free_msg(info->messages[i]);
255         kfree(info->messages);
256         spin_unlock(&info->lock);
257
258         clear_inode(inode);
259
260         mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
261                    (info->attr.mq_maxmsg * info->attr.mq_msgsize));
262         user = info->user;
263         if (user) {
264                 spin_lock(&mq_lock);
265                 user->mq_bytes -= mq_bytes;
266                 queues_count--;
267                 spin_unlock(&mq_lock);
268                 free_uid(user);
269         }
270 }
271
272 static int mqueue_create(struct inode *dir, struct dentry *dentry,
273                                 int mode, struct nameidata *nd)
274 {
275         struct inode *inode;
276         struct mq_attr *attr = dentry->d_fsdata;
277         int error;
278
279         spin_lock(&mq_lock);
280         if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
281                 error = -ENOSPC;
282                 goto out_lock;
283         }
284         queues_count++;
285         spin_unlock(&mq_lock);
286
287         inode = mqueue_get_inode(dir->i_sb, mode, attr);
288         if (!inode) {
289                 error = -ENOMEM;
290                 spin_lock(&mq_lock);
291                 queues_count--;
292                 goto out_lock;
293         }
294
295         dir->i_size += DIRENT_SIZE;
296         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
297
298         d_instantiate(dentry, inode);
299         dget(dentry);
300         return 0;
301 out_lock:
302         spin_unlock(&mq_lock);
303         return error;
304 }
305
306 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
307 {
308         struct inode *inode = dentry->d_inode;
309
310         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
311         dir->i_size -= DIRENT_SIZE;
312         drop_nlink(inode);
313         dput(dentry);
314         return 0;
315 }
316
317 /*
318 *       This is routine for system read from queue file.
319 *       To avoid mess with doing here some sort of mq_receive we allow
320 *       to read only queue size & notification info (the only values
321 *       that are interesting from user point of view and aren't accessible
322 *       through std routines)
323 */
324 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
325                                 size_t count, loff_t *off)
326 {
327         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
328         char buffer[FILENT_SIZE];
329         ssize_t ret;
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_vnr(info->notify_owner));
340         spin_unlock(&info->lock);
341         buffer[sizeof(buffer)-1] = '\0';
342
343         ret = simple_read_from_buffer(u_data, count, off, buffer,
344                                 strlen(buffer));
345         if (ret <= 0)
346                 return ret;
347
348         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
349         return ret;
350 }
351
352 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
353 {
354         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
355
356         spin_lock(&info->lock);
357         if (task_tgid(current) == info->notify_owner)
358                 remove_notification(info);
359
360         spin_unlock(&info->lock);
361         return 0;
362 }
363
364 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
365 {
366         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
367         int retval = 0;
368
369         poll_wait(filp, &info->wait_q, poll_tab);
370
371         spin_lock(&info->lock);
372         if (info->attr.mq_curmsgs)
373                 retval = POLLIN | POLLRDNORM;
374
375         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
376                 retval |= POLLOUT | POLLWRNORM;
377         spin_unlock(&info->lock);
378
379         return retval;
380 }
381
382 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
383 static void wq_add(struct mqueue_inode_info *info, int sr,
384                         struct ext_wait_queue *ewp)
385 {
386         struct ext_wait_queue *walk;
387
388         ewp->task = current;
389
390         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
391                 if (walk->task->static_prio <= current->static_prio) {
392                         list_add_tail(&ewp->list, &walk->list);
393                         return;
394                 }
395         }
396         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
397 }
398
399 /*
400  * Puts current task to sleep. Caller must hold queue lock. After return
401  * lock isn't held.
402  * sr: SEND or RECV
403  */
404 static int wq_sleep(struct mqueue_inode_info *info, int sr,
405                         long timeout, struct ext_wait_queue *ewp)
406 {
407         int retval;
408         signed long time;
409
410         wq_add(info, sr, ewp);
411
412         for (;;) {
413                 set_current_state(TASK_INTERRUPTIBLE);
414
415                 spin_unlock(&info->lock);
416                 time = schedule_timeout(timeout);
417
418                 while (ewp->state == STATE_PENDING)
419                         cpu_relax();
420
421                 if (ewp->state == STATE_READY) {
422                         retval = 0;
423                         goto out;
424                 }
425                 spin_lock(&info->lock);
426                 if (ewp->state == STATE_READY) {
427                         retval = 0;
428                         goto out_unlock;
429                 }
430                 if (signal_pending(current)) {
431                         retval = -ERESTARTSYS;
432                         break;
433                 }
434                 if (time == 0) {
435                         retval = -ETIMEDOUT;
436                         break;
437                 }
438         }
439         list_del(&ewp->list);
440 out_unlock:
441         spin_unlock(&info->lock);
442 out:
443         return retval;
444 }
445
446 /*
447  * Returns waiting task that should be serviced first or NULL if none exists
448  */
449 static struct ext_wait_queue *wq_get_first_waiter(
450                 struct mqueue_inode_info *info, int sr)
451 {
452         struct list_head *ptr;
453
454         ptr = info->e_wait_q[sr].list.prev;
455         if (ptr == &info->e_wait_q[sr].list)
456                 return NULL;
457         return list_entry(ptr, struct ext_wait_queue, list);
458 }
459
460 /* Auxiliary functions to manipulate messages' list */
461 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
462 {
463         int k;
464
465         k = info->attr.mq_curmsgs - 1;
466         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
467                 info->messages[k + 1] = info->messages[k];
468                 k--;
469         }
470         info->attr.mq_curmsgs++;
471         info->qsize += ptr->m_ts;
472         info->messages[k + 1] = ptr;
473 }
474
475 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
476 {
477         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
478         return info->messages[info->attr.mq_curmsgs];
479 }
480
481 static inline void set_cookie(struct sk_buff *skb, char code)
482 {
483         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
484 }
485
486 /*
487  * The next function is only to split too long sys_mq_timedsend
488  */
489 static void __do_notify(struct mqueue_inode_info *info)
490 {
491         /* notification
492          * invoked when there is registered process and there isn't process
493          * waiting synchronously for message AND state of queue changed from
494          * empty to not empty. Here we are sure that no one is waiting
495          * synchronously. */
496         if (info->notify_owner &&
497             info->attr.mq_curmsgs == 1) {
498                 struct siginfo sig_i;
499                 switch (info->notify.sigev_notify) {
500                 case SIGEV_NONE:
501                         break;
502                 case SIGEV_SIGNAL:
503                         /* sends signal */
504
505                         sig_i.si_signo = info->notify.sigev_signo;
506                         sig_i.si_errno = 0;
507                         sig_i.si_code = SI_MESGQ;
508                         sig_i.si_value = info->notify.sigev_value;
509                         sig_i.si_pid = task_tgid_vnr(current);
510                         sig_i.si_uid = current->uid;
511
512                         kill_pid_info(info->notify.sigev_signo,
513                                       &sig_i, info->notify_owner);
514                         break;
515                 case SIGEV_THREAD:
516                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
517                         netlink_sendskb(info->notify_sock, info->notify_cookie);
518                         break;
519                 }
520                 /* after notification unregisters process */
521                 put_pid(info->notify_owner);
522                 info->notify_owner = NULL;
523         }
524         wake_up(&info->wait_q);
525 }
526
527 static long prepare_timeout(const struct timespec __user *u_arg)
528 {
529         struct timespec ts, nowts;
530         long timeout;
531
532         if (u_arg) {
533                 if (unlikely(copy_from_user(&ts, u_arg,
534                                         sizeof(struct timespec))))
535                         return -EFAULT;
536
537                 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
538                         || ts.tv_nsec >= NSEC_PER_SEC))
539                         return -EINVAL;
540                 nowts = CURRENT_TIME;
541                 /* first subtract as jiffies can't be too big */
542                 ts.tv_sec -= nowts.tv_sec;
543                 if (ts.tv_nsec < nowts.tv_nsec) {
544                         ts.tv_nsec += NSEC_PER_SEC;
545                         ts.tv_sec--;
546                 }
547                 ts.tv_nsec -= nowts.tv_nsec;
548                 if (ts.tv_sec < 0)
549                         return 0;
550
551                 timeout = timespec_to_jiffies(&ts) + 1;
552         } else
553                 return MAX_SCHEDULE_TIMEOUT;
554
555         return timeout;
556 }
557
558 static void remove_notification(struct mqueue_inode_info *info)
559 {
560         if (info->notify_owner != NULL &&
561             info->notify.sigev_notify == SIGEV_THREAD) {
562                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
563                 netlink_sendskb(info->notify_sock, info->notify_cookie);
564         }
565         put_pid(info->notify_owner);
566         info->notify_owner = NULL;
567 }
568
569 static int mq_attr_ok(struct mq_attr *attr)
570 {
571         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
572                 return 0;
573         if (capable(CAP_SYS_RESOURCE)) {
574                 if (attr->mq_maxmsg > HARD_MSGMAX)
575                         return 0;
576         } else {
577                 if (attr->mq_maxmsg > msg_max ||
578                                 attr->mq_msgsize > msgsize_max)
579                         return 0;
580         }
581         /* check for overflow */
582         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
583                 return 0;
584         if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
585             (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
586             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
587                 return 0;
588         return 1;
589 }
590
591 /*
592  * Invoked when creating a new queue via sys_mq_open
593  */
594 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
595                         int oflag, mode_t mode, struct mq_attr __user *u_attr)
596 {
597         struct mq_attr attr;
598         struct file *result;
599         int ret;
600
601         if (u_attr) {
602                 ret = -EFAULT;
603                 if (copy_from_user(&attr, u_attr, sizeof(attr)))
604                         goto out;
605                 ret = -EINVAL;
606                 if (!mq_attr_ok(&attr))
607                         goto out;
608                 /* store for use during create */
609                 dentry->d_fsdata = &attr;
610         }
611
612         mode &= ~current->fs->umask;
613         ret = mnt_want_write(mqueue_mnt);
614         if (ret)
615                 goto out;
616         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
617         dentry->d_fsdata = NULL;
618         if (ret)
619                 goto out_drop_write;
620
621         result = dentry_open(dentry, mqueue_mnt, oflag);
622         /*
623          * dentry_open() took a persistent mnt_want_write(),
624          * so we can now drop this one.
625          */
626         mnt_drop_write(mqueue_mnt);
627         return result;
628
629 out_drop_write:
630         mnt_drop_write(mqueue_mnt);
631 out:
632         dput(dentry);
633         mntput(mqueue_mnt);
634         return ERR_PTR(ret);
635 }
636
637 /* Opens existing queue */
638 static struct file *do_open(struct dentry *dentry, int oflag)
639 {
640 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
641                                         MAY_READ | MAY_WRITE };
642
643         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
644                 dput(dentry);
645                 mntput(mqueue_mnt);
646                 return ERR_PTR(-EINVAL);
647         }
648
649         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
650                 dput(dentry);
651                 mntput(mqueue_mnt);
652                 return ERR_PTR(-EACCES);
653         }
654
655         return dentry_open(dentry, mqueue_mnt, oflag);
656 }
657
658 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
659                                 struct mq_attr __user *u_attr)
660 {
661         struct dentry *dentry;
662         struct file *filp;
663         char *name;
664         int fd, error;
665
666         error = audit_mq_open(oflag, mode, u_attr);
667         if (error != 0)
668                 return error;
669
670         if (IS_ERR(name = getname(u_name)))
671                 return PTR_ERR(name);
672
673         fd = get_unused_fd_flags(O_CLOEXEC);
674         if (fd < 0)
675                 goto out_putname;
676
677         mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
678         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
679         if (IS_ERR(dentry)) {
680                 error = PTR_ERR(dentry);
681                 goto out_err;
682         }
683         mntget(mqueue_mnt);
684
685         if (oflag & O_CREAT) {
686                 if (dentry->d_inode) {  /* entry already exists */
687                         audit_inode(name, dentry);
688                         error = -EEXIST;
689                         if (oflag & O_EXCL)
690                                 goto out;
691                         filp = do_open(dentry, oflag);
692                 } else {
693                         filp = do_create(mqueue_mnt->mnt_root, dentry,
694                                                 oflag, mode, u_attr);
695                 }
696         } else {
697                 error = -ENOENT;
698                 if (!dentry->d_inode)
699                         goto out;
700                 audit_inode(name, dentry);
701                 filp = do_open(dentry, oflag);
702         }
703
704         if (IS_ERR(filp)) {
705                 error = PTR_ERR(filp);
706                 goto out_putfd;
707         }
708
709         fd_install(fd, filp);
710         goto out_upsem;
711
712 out:
713         dput(dentry);
714         mntput(mqueue_mnt);
715 out_putfd:
716         put_unused_fd(fd);
717 out_err:
718         fd = error;
719 out_upsem:
720         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
721 out_putname:
722         putname(name);
723         return fd;
724 }
725
726 asmlinkage long sys_mq_unlink(const char __user *u_name)
727 {
728         int err;
729         char *name;
730         struct dentry *dentry;
731         struct inode *inode = NULL;
732
733         name = getname(u_name);
734         if (IS_ERR(name))
735                 return PTR_ERR(name);
736
737         mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
738                         I_MUTEX_PARENT);
739         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
740         if (IS_ERR(dentry)) {
741                 err = PTR_ERR(dentry);
742                 goto out_unlock;
743         }
744
745         if (!dentry->d_inode) {
746                 err = -ENOENT;
747                 goto out_err;
748         }
749
750         inode = dentry->d_inode;
751         if (inode)
752                 atomic_inc(&inode->i_count);
753         err = mnt_want_write(mqueue_mnt);
754         if (err)
755                 goto out_err;
756         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
757         mnt_drop_write(mqueue_mnt);
758 out_err:
759         dput(dentry);
760
761 out_unlock:
762         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
763         putname(name);
764         if (inode)
765                 iput(inode);
766
767         return err;
768 }
769
770 /* Pipelined send and receive functions.
771  *
772  * If a receiver finds no waiting message, then it registers itself in the
773  * list of waiting receivers. A sender checks that list before adding the new
774  * message into the message array. If there is a waiting receiver, then it
775  * bypasses the message array and directly hands the message over to the
776  * receiver.
777  * The receiver accepts the message and returns without grabbing the queue
778  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
779  * are necessary. The same algorithm is used for sysv semaphores, see
780  * ipc/sem.c for more details.
781  *
782  * The same algorithm is used for senders.
783  */
784
785 /* pipelined_send() - send a message directly to the task waiting in
786  * sys_mq_timedreceive() (without inserting message into a queue).
787  */
788 static inline void pipelined_send(struct mqueue_inode_info *info,
789                                   struct msg_msg *message,
790                                   struct ext_wait_queue *receiver)
791 {
792         receiver->msg = message;
793         list_del(&receiver->list);
794         receiver->state = STATE_PENDING;
795         wake_up_process(receiver->task);
796         smp_wmb();
797         receiver->state = STATE_READY;
798 }
799
800 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
801  * gets its message and put to the queue (we have one free place for sure). */
802 static inline void pipelined_receive(struct mqueue_inode_info *info)
803 {
804         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
805
806         if (!sender) {
807                 /* for poll */
808                 wake_up_interruptible(&info->wait_q);
809                 return;
810         }
811         msg_insert(sender->msg, info);
812         list_del(&sender->list);
813         sender->state = STATE_PENDING;
814         wake_up_process(sender->task);
815         smp_wmb();
816         sender->state = STATE_READY;
817 }
818
819 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
820         size_t msg_len, unsigned int msg_prio,
821         const struct timespec __user *u_abs_timeout)
822 {
823         struct file *filp;
824         struct inode *inode;
825         struct ext_wait_queue wait;
826         struct ext_wait_queue *receiver;
827         struct msg_msg *msg_ptr;
828         struct mqueue_inode_info *info;
829         long timeout;
830         int ret;
831
832         ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
833         if (ret != 0)
834                 return ret;
835
836         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
837                 return -EINVAL;
838
839         timeout = prepare_timeout(u_abs_timeout);
840
841         ret = -EBADF;
842         filp = fget(mqdes);
843         if (unlikely(!filp))
844                 goto out;
845
846         inode = filp->f_path.dentry->d_inode;
847         if (unlikely(filp->f_op != &mqueue_file_operations))
848                 goto out_fput;
849         info = MQUEUE_I(inode);
850         audit_inode(NULL, filp->f_path.dentry);
851
852         if (unlikely(!(filp->f_mode & FMODE_WRITE)))
853                 goto out_fput;
854
855         if (unlikely(msg_len > info->attr.mq_msgsize)) {
856                 ret = -EMSGSIZE;
857                 goto out_fput;
858         }
859
860         /* First try to allocate memory, before doing anything with
861          * existing queues. */
862         msg_ptr = load_msg(u_msg_ptr, msg_len);
863         if (IS_ERR(msg_ptr)) {
864                 ret = PTR_ERR(msg_ptr);
865                 goto out_fput;
866         }
867         msg_ptr->m_ts = msg_len;
868         msg_ptr->m_type = msg_prio;
869
870         spin_lock(&info->lock);
871
872         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
873                 if (filp->f_flags & O_NONBLOCK) {
874                         spin_unlock(&info->lock);
875                         ret = -EAGAIN;
876                 } else if (unlikely(timeout < 0)) {
877                         spin_unlock(&info->lock);
878                         ret = timeout;
879                 } else {
880                         wait.task = current;
881                         wait.msg = (void *) msg_ptr;
882                         wait.state = STATE_NONE;
883                         ret = wq_sleep(info, SEND, timeout, &wait);
884                 }
885                 if (ret < 0)
886                         free_msg(msg_ptr);
887         } else {
888                 receiver = wq_get_first_waiter(info, RECV);
889                 if (receiver) {
890                         pipelined_send(info, msg_ptr, receiver);
891                 } else {
892                         /* adds message to the queue */
893                         msg_insert(msg_ptr, info);
894                         __do_notify(info);
895                 }
896                 inode->i_atime = inode->i_mtime = inode->i_ctime =
897                                 CURRENT_TIME;
898                 spin_unlock(&info->lock);
899                 ret = 0;
900         }
901 out_fput:
902         fput(filp);
903 out:
904         return ret;
905 }
906
907 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
908         size_t msg_len, unsigned int __user *u_msg_prio,
909         const struct timespec __user *u_abs_timeout)
910 {
911         long timeout;
912         ssize_t ret;
913         struct msg_msg *msg_ptr;
914         struct file *filp;
915         struct inode *inode;
916         struct mqueue_inode_info *info;
917         struct ext_wait_queue wait;
918
919         ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
920         if (ret != 0)
921                 return ret;
922
923         timeout = prepare_timeout(u_abs_timeout);
924
925         ret = -EBADF;
926         filp = fget(mqdes);
927         if (unlikely(!filp))
928                 goto out;
929
930         inode = filp->f_path.dentry->d_inode;
931         if (unlikely(filp->f_op != &mqueue_file_operations))
932                 goto out_fput;
933         info = MQUEUE_I(inode);
934         audit_inode(NULL, filp->f_path.dentry);
935
936         if (unlikely(!(filp->f_mode & FMODE_READ)))
937                 goto out_fput;
938
939         /* checks if buffer is big enough */
940         if (unlikely(msg_len < info->attr.mq_msgsize)) {
941                 ret = -EMSGSIZE;
942                 goto out_fput;
943         }
944
945         spin_lock(&info->lock);
946         if (info->attr.mq_curmsgs == 0) {
947                 if (filp->f_flags & O_NONBLOCK) {
948                         spin_unlock(&info->lock);
949                         ret = -EAGAIN;
950                         msg_ptr = NULL;
951                 } else if (unlikely(timeout < 0)) {
952                         spin_unlock(&info->lock);
953                         ret = timeout;
954                         msg_ptr = NULL;
955                 } else {
956                         wait.task = current;
957                         wait.state = STATE_NONE;
958                         ret = wq_sleep(info, RECV, timeout, &wait);
959                         msg_ptr = wait.msg;
960                 }
961         } else {
962                 msg_ptr = msg_get(info);
963
964                 inode->i_atime = inode->i_mtime = inode->i_ctime =
965                                 CURRENT_TIME;
966
967                 /* There is now free space in queue. */
968                 pipelined_receive(info);
969                 spin_unlock(&info->lock);
970                 ret = 0;
971         }
972         if (ret == 0) {
973                 ret = msg_ptr->m_ts;
974
975                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
976                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
977                         ret = -EFAULT;
978                 }
979                 free_msg(msg_ptr);
980         }
981 out_fput:
982         fput(filp);
983 out:
984         return ret;
985 }
986
987 /*
988  * Notes: the case when user wants us to deregister (with NULL as pointer)
989  * and he isn't currently owner of notification, will be silently discarded.
990  * It isn't explicitly defined in the POSIX.
991  */
992 asmlinkage long sys_mq_notify(mqd_t mqdes,
993                                 const struct sigevent __user *u_notification)
994 {
995         int ret;
996         struct file *filp;
997         struct sock *sock;
998         struct inode *inode;
999         struct sigevent notification;
1000         struct mqueue_inode_info *info;
1001         struct sk_buff *nc;
1002
1003         ret = audit_mq_notify(mqdes, u_notification);
1004         if (ret != 0)
1005                 return ret;
1006
1007         nc = NULL;
1008         sock = NULL;
1009         if (u_notification != NULL) {
1010                 if (copy_from_user(&notification, u_notification,
1011                                         sizeof(struct sigevent)))
1012                         return -EFAULT;
1013
1014                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1015                              notification.sigev_notify != SIGEV_SIGNAL &&
1016                              notification.sigev_notify != SIGEV_THREAD))
1017                         return -EINVAL;
1018                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1019                         !valid_signal(notification.sigev_signo)) {
1020                         return -EINVAL;
1021                 }
1022                 if (notification.sigev_notify == SIGEV_THREAD) {
1023                         long timeo;
1024
1025                         /* create the notify skb */
1026                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1027                         ret = -ENOMEM;
1028                         if (!nc)
1029                                 goto out;
1030                         ret = -EFAULT;
1031                         if (copy_from_user(nc->data,
1032                                         notification.sigev_value.sival_ptr,
1033                                         NOTIFY_COOKIE_LEN)) {
1034                                 goto out;
1035                         }
1036
1037                         /* TODO: add a header? */
1038                         skb_put(nc, NOTIFY_COOKIE_LEN);
1039                         /* and attach it to the socket */
1040 retry:
1041                         filp = fget(notification.sigev_signo);
1042                         ret = -EBADF;
1043                         if (!filp)
1044                                 goto out;
1045                         sock = netlink_getsockbyfilp(filp);
1046                         fput(filp);
1047                         if (IS_ERR(sock)) {
1048                                 ret = PTR_ERR(sock);
1049                                 sock = NULL;
1050                                 goto out;
1051                         }
1052
1053                         timeo = MAX_SCHEDULE_TIMEOUT;
1054                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1055                         if (ret == 1)
1056                                 goto retry;
1057                         if (ret) {
1058                                 sock = NULL;
1059                                 nc = NULL;
1060                                 goto out;
1061                         }
1062                 }
1063         }
1064
1065         ret = -EBADF;
1066         filp = fget(mqdes);
1067         if (!filp)
1068                 goto out;
1069
1070         inode = filp->f_path.dentry->d_inode;
1071         if (unlikely(filp->f_op != &mqueue_file_operations))
1072                 goto out_fput;
1073         info = MQUEUE_I(inode);
1074
1075         ret = 0;
1076         spin_lock(&info->lock);
1077         if (u_notification == NULL) {
1078                 if (info->notify_owner == task_tgid(current)) {
1079                         remove_notification(info);
1080                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1081                 }
1082         } else if (info->notify_owner != NULL) {
1083                 ret = -EBUSY;
1084         } else {
1085                 switch (notification.sigev_notify) {
1086                 case SIGEV_NONE:
1087                         info->notify.sigev_notify = SIGEV_NONE;
1088                         break;
1089                 case SIGEV_THREAD:
1090                         info->notify_sock = sock;
1091                         info->notify_cookie = nc;
1092                         sock = NULL;
1093                         nc = NULL;
1094                         info->notify.sigev_notify = SIGEV_THREAD;
1095                         break;
1096                 case SIGEV_SIGNAL:
1097                         info->notify.sigev_signo = notification.sigev_signo;
1098                         info->notify.sigev_value = notification.sigev_value;
1099                         info->notify.sigev_notify = SIGEV_SIGNAL;
1100                         break;
1101                 }
1102
1103                 info->notify_owner = get_pid(task_tgid(current));
1104                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1105         }
1106         spin_unlock(&info->lock);
1107 out_fput:
1108         fput(filp);
1109 out:
1110         if (sock) {
1111                 netlink_detachskb(sock, nc);
1112         } else if (nc) {
1113                 dev_kfree_skb(nc);
1114         }
1115         return ret;
1116 }
1117
1118 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1119                         const struct mq_attr __user *u_mqstat,
1120                         struct mq_attr __user *u_omqstat)
1121 {
1122         int ret;
1123         struct mq_attr mqstat, omqstat;
1124         struct file *filp;
1125         struct inode *inode;
1126         struct mqueue_inode_info *info;
1127
1128         if (u_mqstat != NULL) {
1129                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1130                         return -EFAULT;
1131                 if (mqstat.mq_flags & (~O_NONBLOCK))
1132                         return -EINVAL;
1133         }
1134
1135         ret = -EBADF;
1136         filp = fget(mqdes);
1137         if (!filp)
1138                 goto out;
1139
1140         inode = filp->f_path.dentry->d_inode;
1141         if (unlikely(filp->f_op != &mqueue_file_operations))
1142                 goto out_fput;
1143         info = MQUEUE_I(inode);
1144
1145         spin_lock(&info->lock);
1146
1147         omqstat = info->attr;
1148         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1149         if (u_mqstat) {
1150                 ret = audit_mq_getsetattr(mqdes, &mqstat);
1151                 if (ret != 0) {
1152                         spin_unlock(&info->lock);
1153                         goto out_fput;
1154                 }
1155                 if (mqstat.mq_flags & O_NONBLOCK)
1156                         filp->f_flags |= O_NONBLOCK;
1157                 else
1158                         filp->f_flags &= ~O_NONBLOCK;
1159
1160                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1161         }
1162
1163         spin_unlock(&info->lock);
1164
1165         ret = 0;
1166         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1167                                                 sizeof(struct mq_attr)))
1168                 ret = -EFAULT;
1169
1170 out_fput:
1171         fput(filp);
1172 out:
1173         return ret;
1174 }
1175
1176 static const struct inode_operations mqueue_dir_inode_operations = {
1177         .lookup = simple_lookup,
1178         .create = mqueue_create,
1179         .unlink = mqueue_unlink,
1180 };
1181
1182 static const struct file_operations mqueue_file_operations = {
1183         .flush = mqueue_flush_file,
1184         .poll = mqueue_poll_file,
1185         .read = mqueue_read_file,
1186 };
1187
1188 static struct super_operations mqueue_super_ops = {
1189         .alloc_inode = mqueue_alloc_inode,
1190         .destroy_inode = mqueue_destroy_inode,
1191         .statfs = simple_statfs,
1192         .delete_inode = mqueue_delete_inode,
1193         .drop_inode = generic_delete_inode,
1194 };
1195
1196 static struct file_system_type mqueue_fs_type = {
1197         .name = "mqueue",
1198         .get_sb = mqueue_get_sb,
1199         .kill_sb = kill_litter_super,
1200 };
1201
1202 static int msg_max_limit_min = MIN_MSGMAX;
1203 static int msg_max_limit_max = MAX_MSGMAX;
1204
1205 static int msg_maxsize_limit_min = MIN_MSGSIZEMAX;
1206 static int msg_maxsize_limit_max = MAX_MSGSIZEMAX;
1207
1208 static ctl_table mq_sysctls[] = {
1209         {
1210                 .procname       = "queues_max",
1211                 .data           = &queues_max,
1212                 .maxlen         = sizeof(int),
1213                 .mode           = 0644,
1214                 .proc_handler   = &proc_dointvec,
1215         },
1216         {
1217                 .procname       = "msg_max",
1218                 .data           = &msg_max,
1219                 .maxlen         = sizeof(int),
1220                 .mode           = 0644,
1221                 .proc_handler   = &proc_dointvec_minmax,
1222                 .extra1         = &msg_max_limit_min,
1223                 .extra2         = &msg_max_limit_max,
1224         },
1225         {
1226                 .procname       = "msgsize_max",
1227                 .data           = &msgsize_max,
1228                 .maxlen         = sizeof(int),
1229                 .mode           = 0644,
1230                 .proc_handler   = &proc_dointvec_minmax,
1231                 .extra1         = &msg_maxsize_limit_min,
1232                 .extra2         = &msg_maxsize_limit_max,
1233         },
1234         { .ctl_name = 0 }
1235 };
1236
1237 static ctl_table mq_sysctl_dir[] = {
1238         {
1239                 .procname       = "mqueue",
1240                 .mode           = 0555,
1241                 .child          = mq_sysctls,
1242         },
1243         { .ctl_name = 0 }
1244 };
1245
1246 static ctl_table mq_sysctl_root[] = {
1247         {
1248                 .ctl_name       = CTL_FS,
1249                 .procname       = "fs",
1250                 .mode           = 0555,
1251                 .child          = mq_sysctl_dir,
1252         },
1253         { .ctl_name = 0 }
1254 };
1255
1256 static int __init init_mqueue_fs(void)
1257 {
1258         int error;
1259
1260         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1261                                 sizeof(struct mqueue_inode_info), 0,
1262                                 SLAB_HWCACHE_ALIGN, init_once);
1263         if (mqueue_inode_cachep == NULL)
1264                 return -ENOMEM;
1265
1266         /* ignore failues - they are not fatal */
1267         mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1268
1269         error = register_filesystem(&mqueue_fs_type);
1270         if (error)
1271                 goto out_sysctl;
1272
1273         if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1274                 error = PTR_ERR(mqueue_mnt);
1275                 goto out_filesystem;
1276         }
1277
1278         /* internal initialization - not common for vfs */
1279         queues_count = 0;
1280         spin_lock_init(&mq_lock);
1281
1282         return 0;
1283
1284 out_filesystem:
1285         unregister_filesystem(&mqueue_fs_type);
1286 out_sysctl:
1287         if (mq_sysctl_table)
1288                 unregister_sysctl_table(mq_sysctl_table);
1289         kmem_cache_destroy(mqueue_inode_cachep);
1290         return error;
1291 }
1292
1293 __initcall(init_mqueue_fs);