sysctl mqueue: remove the binary sysctl numbers
[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
33 #include <net/sock.h>
34 #include "util.h"
35
36 #define MQUEUE_MAGIC    0x19800202
37 #define DIRENT_SIZE     20
38 #define FILENT_SIZE     80
39
40 #define SEND            0
41 #define RECV            1
42
43 #define STATE_NONE      0
44 #define STATE_PENDING   1
45 #define STATE_READY     2
46
47 /* default values */
48 #define DFLT_QUEUESMAX  256     /* max number of message queues */
49 #define DFLT_MSGMAX     10      /* max number of messages in each queue */
50 #define HARD_MSGMAX     (131072/sizeof(void*))
51 #define DFLT_MSGSIZEMAX 8192    /* max message size */
52
53
54 struct ext_wait_queue {         /* queue of sleeping tasks */
55         struct task_struct *task;
56         struct list_head list;
57         struct msg_msg *msg;    /* ptr of loaded message */
58         int state;              /* one of STATE_* values */
59 };
60
61 struct mqueue_inode_info {
62         spinlock_t lock;
63         struct inode vfs_inode;
64         wait_queue_head_t wait_q;
65
66         struct msg_msg **messages;
67         struct mq_attr attr;
68
69         struct sigevent notify;
70         struct pid* notify_owner;
71         struct user_struct *user;       /* user who created, for accounting */
72         struct sock *notify_sock;
73         struct sk_buff *notify_cookie;
74
75         /* for tasks waiting for free space and messages, respectively */
76         struct ext_wait_queue e_wait_q[2];
77
78         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
79 };
80
81 static const struct inode_operations mqueue_dir_inode_operations;
82 static const struct file_operations mqueue_file_operations;
83 static struct super_operations mqueue_super_ops;
84 static void remove_notification(struct mqueue_inode_info *info);
85
86 static spinlock_t mq_lock;
87 static struct kmem_cache *mqueue_inode_cachep;
88 static struct vfsmount *mqueue_mnt;
89
90 static unsigned int queues_count;
91 static unsigned int queues_max  = DFLT_QUEUESMAX;
92 static unsigned int msg_max     = DFLT_MSGMAX;
93 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
94
95 static struct ctl_table_header * mq_sysctl_table;
96
97 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
98 {
99         return container_of(inode, struct mqueue_inode_info, vfs_inode);
100 }
101
102 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
103                                                         struct mq_attr *attr)
104 {
105         struct inode *inode;
106
107         inode = new_inode(sb);
108         if (inode) {
109                 inode->i_mode = mode;
110                 inode->i_uid = current->fsuid;
111                 inode->i_gid = current->fsgid;
112                 inode->i_blocks = 0;
113                 inode->i_mtime = inode->i_ctime = inode->i_atime =
114                                 CURRENT_TIME;
115
116                 if (S_ISREG(mode)) {
117                         struct mqueue_inode_info *info;
118                         struct task_struct *p = current;
119                         struct user_struct *u = p->user;
120                         unsigned long mq_bytes, mq_msg_tblsz;
121
122                         inode->i_fop = &mqueue_file_operations;
123                         inode->i_size = FILENT_SIZE;
124                         /* mqueue specific info */
125                         info = MQUEUE_I(inode);
126                         spin_lock_init(&info->lock);
127                         init_waitqueue_head(&info->wait_q);
128                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
129                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
130                         info->messages = NULL;
131                         info->notify_owner = NULL;
132                         info->qsize = 0;
133                         info->user = NULL;      /* set when all is ok */
134                         memset(&info->attr, 0, sizeof(info->attr));
135                         info->attr.mq_maxmsg = DFLT_MSGMAX;
136                         info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
137                         if (attr) {
138                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
139                                 info->attr.mq_msgsize = attr->mq_msgsize;
140                         }
141                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
142                         mq_bytes = (mq_msg_tblsz +
143                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
144
145                         spin_lock(&mq_lock);
146                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
147                             u->mq_bytes + mq_bytes >
148                             p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
149                                 spin_unlock(&mq_lock);
150                                 goto out_inode;
151                         }
152                         u->mq_bytes += mq_bytes;
153                         spin_unlock(&mq_lock);
154
155                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
156                         if (!info->messages) {
157                                 spin_lock(&mq_lock);
158                                 u->mq_bytes -= mq_bytes;
159                                 spin_unlock(&mq_lock);
160                                 goto out_inode;
161                         }
162                         /* all is ok */
163                         info->user = get_uid(u);
164                 } else if (S_ISDIR(mode)) {
165                         inc_nlink(inode);
166                         /* Some things misbehave if size == 0 on a directory */
167                         inode->i_size = 2 * DIRENT_SIZE;
168                         inode->i_op = &mqueue_dir_inode_operations;
169                         inode->i_fop = &simple_dir_operations;
170                 }
171         }
172         return inode;
173 out_inode:
174         make_bad_inode(inode);
175         iput(inode);
176         return NULL;
177 }
178
179 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
180 {
181         struct inode *inode;
182
183         sb->s_blocksize = PAGE_CACHE_SIZE;
184         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
185         sb->s_magic = MQUEUE_MAGIC;
186         sb->s_op = &mqueue_super_ops;
187
188         inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
189         if (!inode)
190                 return -ENOMEM;
191
192         sb->s_root = d_alloc_root(inode);
193         if (!sb->s_root) {
194                 iput(inode);
195                 return -ENOMEM;
196         }
197
198         return 0;
199 }
200
201 static int mqueue_get_sb(struct file_system_type *fs_type,
202                          int flags, const char *dev_name,
203                          void *data, struct vfsmount *mnt)
204 {
205         return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
206 }
207
208 static void init_once(struct kmem_cache *cachep, void *foo)
209 {
210         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
211
212         inode_init_once(&p->vfs_inode);
213 }
214
215 static struct inode *mqueue_alloc_inode(struct super_block *sb)
216 {
217         struct mqueue_inode_info *ei;
218
219         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
220         if (!ei)
221                 return NULL;
222         return &ei->vfs_inode;
223 }
224
225 static void mqueue_destroy_inode(struct inode *inode)
226 {
227         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
228 }
229
230 static void mqueue_delete_inode(struct inode *inode)
231 {
232         struct mqueue_inode_info *info;
233         struct user_struct *user;
234         unsigned long mq_bytes;
235         int i;
236
237         if (S_ISDIR(inode->i_mode)) {
238                 clear_inode(inode);
239                 return;
240         }
241         info = MQUEUE_I(inode);
242         spin_lock(&info->lock);
243         for (i = 0; i < info->attr.mq_curmsgs; i++)
244                 free_msg(info->messages[i]);
245         kfree(info->messages);
246         spin_unlock(&info->lock);
247
248         clear_inode(inode);
249
250         mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
251                    (info->attr.mq_maxmsg * info->attr.mq_msgsize));
252         user = info->user;
253         if (user) {
254                 spin_lock(&mq_lock);
255                 user->mq_bytes -= mq_bytes;
256                 queues_count--;
257                 spin_unlock(&mq_lock);
258                 free_uid(user);
259         }
260 }
261
262 static int mqueue_create(struct inode *dir, struct dentry *dentry,
263                                 int mode, struct nameidata *nd)
264 {
265         struct inode *inode;
266         struct mq_attr *attr = dentry->d_fsdata;
267         int error;
268
269         spin_lock(&mq_lock);
270         if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
271                 error = -ENOSPC;
272                 goto out_lock;
273         }
274         queues_count++;
275         spin_unlock(&mq_lock);
276
277         inode = mqueue_get_inode(dir->i_sb, mode, attr);
278         if (!inode) {
279                 error = -ENOMEM;
280                 spin_lock(&mq_lock);
281                 queues_count--;
282                 goto out_lock;
283         }
284
285         dir->i_size += DIRENT_SIZE;
286         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
287
288         d_instantiate(dentry, inode);
289         dget(dentry);
290         return 0;
291 out_lock:
292         spin_unlock(&mq_lock);
293         return error;
294 }
295
296 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
297 {
298         struct inode *inode = dentry->d_inode;
299
300         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
301         dir->i_size -= DIRENT_SIZE;
302         drop_nlink(inode);
303         dput(dentry);
304         return 0;
305 }
306
307 /*
308 *       This is routine for system read from queue file.
309 *       To avoid mess with doing here some sort of mq_receive we allow
310 *       to read only queue size & notification info (the only values
311 *       that are interesting from user point of view and aren't accessible
312 *       through std routines)
313 */
314 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
315                                 size_t count, loff_t * off)
316 {
317         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
318         char buffer[FILENT_SIZE];
319         size_t slen;
320         loff_t o;
321
322         if (!count)
323                 return 0;
324
325         spin_lock(&info->lock);
326         snprintf(buffer, sizeof(buffer),
327                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
328                         info->qsize,
329                         info->notify_owner ? info->notify.sigev_notify : 0,
330                         (info->notify_owner &&
331                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
332                                 info->notify.sigev_signo : 0,
333                         pid_nr(info->notify_owner));
334         spin_unlock(&info->lock);
335         buffer[sizeof(buffer)-1] = '\0';
336         slen = strlen(buffer)+1;
337
338         o = *off;
339         if (o > slen)
340                 return 0;
341
342         if (o + count > slen)
343                 count = slen - o;
344
345         if (copy_to_user(u_data, buffer + o, count))
346                 return -EFAULT;
347
348         *off = o + count;
349         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
350         return count;
351 }
352
353 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
354 {
355         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
356
357         spin_lock(&info->lock);
358         if (task_tgid(current) == info->notify_owner)
359                 remove_notification(info);
360
361         spin_unlock(&info->lock);
362         return 0;
363 }
364
365 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
366 {
367         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
368         int retval = 0;
369
370         poll_wait(filp, &info->wait_q, poll_tab);
371
372         spin_lock(&info->lock);
373         if (info->attr.mq_curmsgs)
374                 retval = POLLIN | POLLRDNORM;
375
376         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
377                 retval |= POLLOUT | POLLWRNORM;
378         spin_unlock(&info->lock);
379
380         return retval;
381 }
382
383 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
384 static void wq_add(struct mqueue_inode_info *info, int sr,
385                         struct ext_wait_queue *ewp)
386 {
387         struct ext_wait_queue *walk;
388
389         ewp->task = current;
390
391         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
392                 if (walk->task->static_prio <= current->static_prio) {
393                         list_add_tail(&ewp->list, &walk->list);
394                         return;
395                 }
396         }
397         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
398 }
399
400 /*
401  * Puts current task to sleep. Caller must hold queue lock. After return
402  * lock isn't held.
403  * sr: SEND or RECV
404  */
405 static int wq_sleep(struct mqueue_inode_info *info, int sr,
406                         long timeout, struct ext_wait_queue *ewp)
407 {
408         int retval;
409         signed long time;
410
411         wq_add(info, sr, ewp);
412
413         for (;;) {
414                 set_current_state(TASK_INTERRUPTIBLE);
415
416                 spin_unlock(&info->lock);
417                 time = schedule_timeout(timeout);
418
419                 while (ewp->state == STATE_PENDING)
420                         cpu_relax();
421
422                 if (ewp->state == STATE_READY) {
423                         retval = 0;
424                         goto out;
425                 }
426                 spin_lock(&info->lock);
427                 if (ewp->state == STATE_READY) {
428                         retval = 0;
429                         goto out_unlock;
430                 }
431                 if (signal_pending(current)) {
432                         retval = -ERESTARTSYS;
433                         break;
434                 }
435                 if (time == 0) {
436                         retval = -ETIMEDOUT;
437                         break;
438                 }
439         }
440         list_del(&ewp->list);
441 out_unlock:
442         spin_unlock(&info->lock);
443 out:
444         return retval;
445 }
446
447 /*
448  * Returns waiting task that should be serviced first or NULL if none exists
449  */
450 static struct ext_wait_queue *wq_get_first_waiter(
451                 struct mqueue_inode_info *info, int sr)
452 {
453         struct list_head *ptr;
454
455         ptr = info->e_wait_q[sr].list.prev;
456         if (ptr == &info->e_wait_q[sr].list)
457                 return NULL;
458         return list_entry(ptr, struct ext_wait_queue, list);
459 }
460
461 /* Auxiliary functions to manipulate messages' list */
462 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
463 {
464         int k;
465
466         k = info->attr.mq_curmsgs - 1;
467         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
468                 info->messages[k + 1] = info->messages[k];
469                 k--;
470         }
471         info->attr.mq_curmsgs++;
472         info->qsize += ptr->m_ts;
473         info->messages[k + 1] = ptr;
474 }
475
476 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
477 {
478         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
479         return info->messages[info->attr.mq_curmsgs];
480 }
481
482 static inline void set_cookie(struct sk_buff *skb, char code)
483 {
484         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
485 }
486
487 /*
488  * The next function is only to split too long sys_mq_timedsend
489  */
490 static void __do_notify(struct mqueue_inode_info *info)
491 {
492         /* notification
493          * invoked when there is registered process and there isn't process
494          * waiting synchronously for message AND state of queue changed from
495          * empty to not empty. Here we are sure that no one is waiting
496          * synchronously. */
497         if (info->notify_owner &&
498             info->attr.mq_curmsgs == 1) {
499                 struct siginfo sig_i;
500                 switch (info->notify.sigev_notify) {
501                 case SIGEV_NONE:
502                         break;
503                 case SIGEV_SIGNAL:
504                         /* sends signal */
505
506                         sig_i.si_signo = info->notify.sigev_signo;
507                         sig_i.si_errno = 0;
508                         sig_i.si_code = SI_MESGQ;
509                         sig_i.si_value = info->notify.sigev_value;
510                         sig_i.si_pid = current->tgid;
511                         sig_i.si_uid = current->uid;
512
513                         kill_pid_info(info->notify.sigev_signo,
514                                       &sig_i, info->notify_owner);
515                         break;
516                 case SIGEV_THREAD:
517                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
518                         netlink_sendskb(info->notify_sock, info->notify_cookie);
519                         break;
520                 }
521                 /* after notification unregisters process */
522                 put_pid(info->notify_owner);
523                 info->notify_owner = NULL;
524         }
525         wake_up(&info->wait_q);
526 }
527
528 static long prepare_timeout(const struct timespec __user *u_arg)
529 {
530         struct timespec ts, nowts;
531         long timeout;
532
533         if (u_arg) {
534                 if (unlikely(copy_from_user(&ts, u_arg,
535                                         sizeof(struct timespec))))
536                         return -EFAULT;
537
538                 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
539                         || ts.tv_nsec >= NSEC_PER_SEC))
540                         return -EINVAL;
541                 nowts = CURRENT_TIME;
542                 /* first subtract as jiffies can't be too big */
543                 ts.tv_sec -= nowts.tv_sec;
544                 if (ts.tv_nsec < nowts.tv_nsec) {
545                         ts.tv_nsec += NSEC_PER_SEC;
546                         ts.tv_sec--;
547                 }
548                 ts.tv_nsec -= nowts.tv_nsec;
549                 if (ts.tv_sec < 0)
550                         return 0;
551
552                 timeout = timespec_to_jiffies(&ts) + 1;
553         } else
554                 return MAX_SCHEDULE_TIMEOUT;
555
556         return timeout;
557 }
558
559 static void remove_notification(struct mqueue_inode_info *info)
560 {
561         if (info->notify_owner != NULL &&
562             info->notify.sigev_notify == SIGEV_THREAD) {
563                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
564                 netlink_sendskb(info->notify_sock, info->notify_cookie);
565         }
566         put_pid(info->notify_owner);
567         info->notify_owner = NULL;
568 }
569
570 static int mq_attr_ok(struct mq_attr *attr)
571 {
572         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
573                 return 0;
574         if (capable(CAP_SYS_RESOURCE)) {
575                 if (attr->mq_maxmsg > HARD_MSGMAX)
576                         return 0;
577         } else {
578                 if (attr->mq_maxmsg > msg_max ||
579                                 attr->mq_msgsize > msgsize_max)
580                         return 0;
581         }
582         /* check for overflow */
583         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
584                 return 0;
585         if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
586             (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
587             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
588                 return 0;
589         return 1;
590 }
591
592 /*
593  * Invoked when creating a new queue via sys_mq_open
594  */
595 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
596                         int oflag, mode_t mode, struct mq_attr __user *u_attr)
597 {
598         struct mq_attr attr;
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 = vfs_create(dir->d_inode, dentry, mode, NULL);
614         dentry->d_fsdata = NULL;
615         if (ret)
616                 goto out;
617
618         return dentry_open(dentry, mqueue_mnt, oflag);
619
620 out:
621         dput(dentry);
622         mntput(mqueue_mnt);
623         return ERR_PTR(ret);
624 }
625
626 /* Opens existing queue */
627 static struct file *do_open(struct dentry *dentry, int oflag)
628 {
629 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
630                                         MAY_READ | MAY_WRITE };
631
632         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
633                 dput(dentry);
634                 mntput(mqueue_mnt);
635                 return ERR_PTR(-EINVAL);
636         }
637
638         if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
639                 dput(dentry);
640                 mntput(mqueue_mnt);
641                 return ERR_PTR(-EACCES);
642         }
643
644         return dentry_open(dentry, mqueue_mnt, oflag);
645 }
646
647 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
648                                 struct mq_attr __user *u_attr)
649 {
650         struct dentry *dentry;
651         struct file *filp;
652         char *name;
653         int fd, error;
654
655         error = audit_mq_open(oflag, mode, u_attr);
656         if (error != 0)
657                 return error;
658
659         if (IS_ERR(name = getname(u_name)))
660                 return PTR_ERR(name);
661
662         fd = get_unused_fd();
663         if (fd < 0)
664                 goto out_putname;
665
666         mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
667         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
668         if (IS_ERR(dentry)) {
669                 error = PTR_ERR(dentry);
670                 goto out_err;
671         }
672         mntget(mqueue_mnt);
673
674         if (oflag & O_CREAT) {
675                 if (dentry->d_inode) {  /* entry already exists */
676                         audit_inode(name, dentry->d_inode);
677                         error = -EEXIST;
678                         if (oflag & O_EXCL)
679                                 goto out;
680                         filp = do_open(dentry, oflag);
681                 } else {
682                         filp = do_create(mqueue_mnt->mnt_root, dentry,
683                                                 oflag, mode, u_attr);
684                 }
685         } else {
686                 error = -ENOENT;
687                 if (!dentry->d_inode)
688                         goto out;
689                 audit_inode(name, dentry->d_inode);
690                 filp = do_open(dentry, oflag);
691         }
692
693         if (IS_ERR(filp)) {
694                 error = PTR_ERR(filp);
695                 goto out_putfd;
696         }
697
698         set_close_on_exec(fd, 1);
699         fd_install(fd, filp);
700         goto out_upsem;
701
702 out:
703         dput(dentry);
704         mntput(mqueue_mnt);
705 out_putfd:
706         put_unused_fd(fd);
707 out_err:
708         fd = error;
709 out_upsem:
710         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
711 out_putname:
712         putname(name);
713         return fd;
714 }
715
716 asmlinkage long sys_mq_unlink(const char __user *u_name)
717 {
718         int err;
719         char *name;
720         struct dentry *dentry;
721         struct inode *inode = NULL;
722
723         name = getname(u_name);
724         if (IS_ERR(name))
725                 return PTR_ERR(name);
726
727         mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
728                         I_MUTEX_PARENT);
729         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
730         if (IS_ERR(dentry)) {
731                 err = PTR_ERR(dentry);
732                 goto out_unlock;
733         }
734
735         if (!dentry->d_inode) {
736                 err = -ENOENT;
737                 goto out_err;
738         }
739
740         inode = dentry->d_inode;
741         if (inode)
742                 atomic_inc(&inode->i_count);
743
744         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
745 out_err:
746         dput(dentry);
747
748 out_unlock:
749         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
750         putname(name);
751         if (inode)
752                 iput(inode);
753
754         return err;
755 }
756
757 /* Pipelined send and receive functions.
758  *
759  * If a receiver finds no waiting message, then it registers itself in the
760  * list of waiting receivers. A sender checks that list before adding the new
761  * message into the message array. If there is a waiting receiver, then it
762  * bypasses the message array and directly hands the message over to the
763  * receiver.
764  * The receiver accepts the message and returns without grabbing the queue
765  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
766  * are necessary. The same algorithm is used for sysv semaphores, see
767  * ipc/sem.c for more details.
768  *
769  * The same algorithm is used for senders.
770  */
771
772 /* pipelined_send() - send a message directly to the task waiting in
773  * sys_mq_timedreceive() (without inserting message into a queue).
774  */
775 static inline void pipelined_send(struct mqueue_inode_info *info,
776                                   struct msg_msg *message,
777                                   struct ext_wait_queue *receiver)
778 {
779         receiver->msg = message;
780         list_del(&receiver->list);
781         receiver->state = STATE_PENDING;
782         wake_up_process(receiver->task);
783         smp_wmb();
784         receiver->state = STATE_READY;
785 }
786
787 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
788  * gets its message and put to the queue (we have one free place for sure). */
789 static inline void pipelined_receive(struct mqueue_inode_info *info)
790 {
791         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
792
793         if (!sender) {
794                 /* for poll */
795                 wake_up_interruptible(&info->wait_q);
796                 return;
797         }
798         msg_insert(sender->msg, info);
799         list_del(&sender->list);
800         sender->state = STATE_PENDING;
801         wake_up_process(sender->task);
802         smp_wmb();
803         sender->state = STATE_READY;
804 }
805
806 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
807         size_t msg_len, unsigned int msg_prio,
808         const struct timespec __user *u_abs_timeout)
809 {
810         struct file *filp;
811         struct inode *inode;
812         struct ext_wait_queue wait;
813         struct ext_wait_queue *receiver;
814         struct msg_msg *msg_ptr;
815         struct mqueue_inode_info *info;
816         long timeout;
817         int ret;
818
819         ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
820         if (ret != 0)
821                 return ret;
822
823         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
824                 return -EINVAL;
825
826         timeout = prepare_timeout(u_abs_timeout);
827
828         ret = -EBADF;
829         filp = fget(mqdes);
830         if (unlikely(!filp))
831                 goto out;
832
833         inode = filp->f_path.dentry->d_inode;
834         if (unlikely(filp->f_op != &mqueue_file_operations))
835                 goto out_fput;
836         info = MQUEUE_I(inode);
837         audit_inode(NULL, inode);
838
839         if (unlikely(!(filp->f_mode & FMODE_WRITE)))
840                 goto out_fput;
841
842         if (unlikely(msg_len > info->attr.mq_msgsize)) {
843                 ret = -EMSGSIZE;
844                 goto out_fput;
845         }
846
847         /* First try to allocate memory, before doing anything with
848          * existing queues. */
849         msg_ptr = load_msg(u_msg_ptr, msg_len);
850         if (IS_ERR(msg_ptr)) {
851                 ret = PTR_ERR(msg_ptr);
852                 goto out_fput;
853         }
854         msg_ptr->m_ts = msg_len;
855         msg_ptr->m_type = msg_prio;
856
857         spin_lock(&info->lock);
858
859         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
860                 if (filp->f_flags & O_NONBLOCK) {
861                         spin_unlock(&info->lock);
862                         ret = -EAGAIN;
863                 } else if (unlikely(timeout < 0)) {
864                         spin_unlock(&info->lock);
865                         ret = timeout;
866                 } else {
867                         wait.task = current;
868                         wait.msg = (void *) msg_ptr;
869                         wait.state = STATE_NONE;
870                         ret = wq_sleep(info, SEND, timeout, &wait);
871                 }
872                 if (ret < 0)
873                         free_msg(msg_ptr);
874         } else {
875                 receiver = wq_get_first_waiter(info, RECV);
876                 if (receiver) {
877                         pipelined_send(info, msg_ptr, receiver);
878                 } else {
879                         /* adds message to the queue */
880                         msg_insert(msg_ptr, info);
881                         __do_notify(info);
882                 }
883                 inode->i_atime = inode->i_mtime = inode->i_ctime =
884                                 CURRENT_TIME;
885                 spin_unlock(&info->lock);
886                 ret = 0;
887         }
888 out_fput:
889         fput(filp);
890 out:
891         return ret;
892 }
893
894 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
895         size_t msg_len, unsigned int __user *u_msg_prio,
896         const struct timespec __user *u_abs_timeout)
897 {
898         long timeout;
899         ssize_t ret;
900         struct msg_msg *msg_ptr;
901         struct file *filp;
902         struct inode *inode;
903         struct mqueue_inode_info *info;
904         struct ext_wait_queue wait;
905
906         ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
907         if (ret != 0)
908                 return ret;
909
910         timeout = prepare_timeout(u_abs_timeout);
911
912         ret = -EBADF;
913         filp = fget(mqdes);
914         if (unlikely(!filp))
915                 goto out;
916
917         inode = filp->f_path.dentry->d_inode;
918         if (unlikely(filp->f_op != &mqueue_file_operations))
919                 goto out_fput;
920         info = MQUEUE_I(inode);
921         audit_inode(NULL, inode);
922
923         if (unlikely(!(filp->f_mode & FMODE_READ)))
924                 goto out_fput;
925
926         /* checks if buffer is big enough */
927         if (unlikely(msg_len < info->attr.mq_msgsize)) {
928                 ret = -EMSGSIZE;
929                 goto out_fput;
930         }
931
932         spin_lock(&info->lock);
933         if (info->attr.mq_curmsgs == 0) {
934                 if (filp->f_flags & O_NONBLOCK) {
935                         spin_unlock(&info->lock);
936                         ret = -EAGAIN;
937                         msg_ptr = NULL;
938                 } else if (unlikely(timeout < 0)) {
939                         spin_unlock(&info->lock);
940                         ret = timeout;
941                         msg_ptr = NULL;
942                 } else {
943                         wait.task = current;
944                         wait.state = STATE_NONE;
945                         ret = wq_sleep(info, RECV, timeout, &wait);
946                         msg_ptr = wait.msg;
947                 }
948         } else {
949                 msg_ptr = msg_get(info);
950
951                 inode->i_atime = inode->i_mtime = inode->i_ctime =
952                                 CURRENT_TIME;
953
954                 /* There is now free space in queue. */
955                 pipelined_receive(info);
956                 spin_unlock(&info->lock);
957                 ret = 0;
958         }
959         if (ret == 0) {
960                 ret = msg_ptr->m_ts;
961
962                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
963                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
964                         ret = -EFAULT;
965                 }
966                 free_msg(msg_ptr);
967         }
968 out_fput:
969         fput(filp);
970 out:
971         return ret;
972 }
973
974 /*
975  * Notes: the case when user wants us to deregister (with NULL as pointer)
976  * and he isn't currently owner of notification, will be silently discarded.
977  * It isn't explicitly defined in the POSIX.
978  */
979 asmlinkage long sys_mq_notify(mqd_t mqdes,
980                                 const struct sigevent __user *u_notification)
981 {
982         int ret;
983         struct file *filp;
984         struct sock *sock;
985         struct inode *inode;
986         struct sigevent notification;
987         struct mqueue_inode_info *info;
988         struct sk_buff *nc;
989
990         ret = audit_mq_notify(mqdes, u_notification);
991         if (ret != 0)
992                 return ret;
993
994         nc = NULL;
995         sock = NULL;
996         if (u_notification != NULL) {
997                 if (copy_from_user(&notification, u_notification,
998                                         sizeof(struct sigevent)))
999                         return -EFAULT;
1000
1001                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1002                              notification.sigev_notify != SIGEV_SIGNAL &&
1003                              notification.sigev_notify != SIGEV_THREAD))
1004                         return -EINVAL;
1005                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1006                         !valid_signal(notification.sigev_signo)) {
1007                         return -EINVAL;
1008                 }
1009                 if (notification.sigev_notify == SIGEV_THREAD) {
1010                         /* create the notify skb */
1011                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1012                         ret = -ENOMEM;
1013                         if (!nc)
1014                                 goto out;
1015                         ret = -EFAULT;
1016                         if (copy_from_user(nc->data,
1017                                         notification.sigev_value.sival_ptr,
1018                                         NOTIFY_COOKIE_LEN)) {
1019                                 goto out;
1020                         }
1021
1022                         /* TODO: add a header? */
1023                         skb_put(nc, NOTIFY_COOKIE_LEN);
1024                         /* and attach it to the socket */
1025 retry:
1026                         filp = fget(notification.sigev_signo);
1027                         ret = -EBADF;
1028                         if (!filp)
1029                                 goto out;
1030                         sock = netlink_getsockbyfilp(filp);
1031                         fput(filp);
1032                         if (IS_ERR(sock)) {
1033                                 ret = PTR_ERR(sock);
1034                                 sock = NULL;
1035                                 goto out;
1036                         }
1037
1038                         ret = netlink_attachskb(sock, nc, 0,
1039                                         MAX_SCHEDULE_TIMEOUT, NULL);
1040                         if (ret == 1)
1041                                 goto retry;
1042                         if (ret) {
1043                                 sock = NULL;
1044                                 nc = NULL;
1045                                 goto out;
1046                         }
1047                 }
1048         }
1049
1050         ret = -EBADF;
1051         filp = fget(mqdes);
1052         if (!filp)
1053                 goto out;
1054
1055         inode = filp->f_path.dentry->d_inode;
1056         if (unlikely(filp->f_op != &mqueue_file_operations))
1057                 goto out_fput;
1058         info = MQUEUE_I(inode);
1059
1060         ret = 0;
1061         spin_lock(&info->lock);
1062         if (u_notification == NULL) {
1063                 if (info->notify_owner == task_tgid(current)) {
1064                         remove_notification(info);
1065                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1066                 }
1067         } else if (info->notify_owner != NULL) {
1068                 ret = -EBUSY;
1069         } else {
1070                 switch (notification.sigev_notify) {
1071                 case SIGEV_NONE:
1072                         info->notify.sigev_notify = SIGEV_NONE;
1073                         break;
1074                 case SIGEV_THREAD:
1075                         info->notify_sock = sock;
1076                         info->notify_cookie = nc;
1077                         sock = NULL;
1078                         nc = NULL;
1079                         info->notify.sigev_notify = SIGEV_THREAD;
1080                         break;
1081                 case SIGEV_SIGNAL:
1082                         info->notify.sigev_signo = notification.sigev_signo;
1083                         info->notify.sigev_value = notification.sigev_value;
1084                         info->notify.sigev_notify = SIGEV_SIGNAL;
1085                         break;
1086                 }
1087
1088                 info->notify_owner = get_pid(task_tgid(current));
1089                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1090         }
1091         spin_unlock(&info->lock);
1092 out_fput:
1093         fput(filp);
1094 out:
1095         if (sock) {
1096                 netlink_detachskb(sock, nc);
1097         } else if (nc) {
1098                 dev_kfree_skb(nc);
1099         }
1100         return ret;
1101 }
1102
1103 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1104                         const struct mq_attr __user *u_mqstat,
1105                         struct mq_attr __user *u_omqstat)
1106 {
1107         int ret;
1108         struct mq_attr mqstat, omqstat;
1109         struct file *filp;
1110         struct inode *inode;
1111         struct mqueue_inode_info *info;
1112
1113         if (u_mqstat != NULL) {
1114                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1115                         return -EFAULT;
1116                 if (mqstat.mq_flags & (~O_NONBLOCK))
1117                         return -EINVAL;
1118         }
1119
1120         ret = -EBADF;
1121         filp = fget(mqdes);
1122         if (!filp)
1123                 goto out;
1124
1125         inode = filp->f_path.dentry->d_inode;
1126         if (unlikely(filp->f_op != &mqueue_file_operations))
1127                 goto out_fput;
1128         info = MQUEUE_I(inode);
1129
1130         spin_lock(&info->lock);
1131
1132         omqstat = info->attr;
1133         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1134         if (u_mqstat) {
1135                 ret = audit_mq_getsetattr(mqdes, &mqstat);
1136                 if (ret != 0)
1137                         goto out;
1138                 if (mqstat.mq_flags & O_NONBLOCK)
1139                         filp->f_flags |= O_NONBLOCK;
1140                 else
1141                         filp->f_flags &= ~O_NONBLOCK;
1142
1143                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1144         }
1145
1146         spin_unlock(&info->lock);
1147
1148         ret = 0;
1149         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1150                                                 sizeof(struct mq_attr)))
1151                 ret = -EFAULT;
1152
1153 out_fput:
1154         fput(filp);
1155 out:
1156         return ret;
1157 }
1158
1159 static const struct inode_operations mqueue_dir_inode_operations = {
1160         .lookup = simple_lookup,
1161         .create = mqueue_create,
1162         .unlink = mqueue_unlink,
1163 };
1164
1165 static const struct file_operations mqueue_file_operations = {
1166         .flush = mqueue_flush_file,
1167         .poll = mqueue_poll_file,
1168         .read = mqueue_read_file,
1169 };
1170
1171 static struct super_operations mqueue_super_ops = {
1172         .alloc_inode = mqueue_alloc_inode,
1173         .destroy_inode = mqueue_destroy_inode,
1174         .statfs = simple_statfs,
1175         .delete_inode = mqueue_delete_inode,
1176         .drop_inode = generic_delete_inode,
1177 };
1178
1179 static struct file_system_type mqueue_fs_type = {
1180         .name = "mqueue",
1181         .get_sb = mqueue_get_sb,
1182         .kill_sb = kill_litter_super,
1183 };
1184
1185 static int msg_max_limit_min = DFLT_MSGMAX;
1186 static int msg_max_limit_max = HARD_MSGMAX;
1187
1188 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1189 static int msg_maxsize_limit_max = INT_MAX;
1190
1191 static ctl_table mq_sysctls[] = {
1192         {
1193                 .procname       = "queues_max",
1194                 .data           = &queues_max,
1195                 .maxlen         = sizeof(int),
1196                 .mode           = 0644,
1197                 .proc_handler   = &proc_dointvec,
1198         },
1199         {
1200                 .procname       = "msg_max",
1201                 .data           = &msg_max,
1202                 .maxlen         = sizeof(int),
1203                 .mode           = 0644,
1204                 .proc_handler   = &proc_dointvec_minmax,
1205                 .extra1         = &msg_max_limit_min,
1206                 .extra2         = &msg_max_limit_max,
1207         },
1208         {
1209                 .procname       = "msgsize_max",
1210                 .data           = &msgsize_max,
1211                 .maxlen         = sizeof(int),
1212                 .mode           = 0644,
1213                 .proc_handler   = &proc_dointvec_minmax,
1214                 .extra1         = &msg_maxsize_limit_min,
1215                 .extra2         = &msg_maxsize_limit_max,
1216         },
1217         { .ctl_name = 0 }
1218 };
1219
1220 static ctl_table mq_sysctl_dir[] = {
1221         {
1222                 .procname       = "mqueue",
1223                 .mode           = 0555,
1224                 .child          = mq_sysctls,
1225         },
1226         { .ctl_name = 0 }
1227 };
1228
1229 static ctl_table mq_sysctl_root[] = {
1230         {
1231                 .ctl_name       = CTL_FS,
1232                 .procname       = "fs",
1233                 .mode           = 0555,
1234                 .child          = mq_sysctl_dir,
1235         },
1236         { .ctl_name = 0 }
1237 };
1238
1239 static int __init init_mqueue_fs(void)
1240 {
1241         int error;
1242
1243         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1244                                 sizeof(struct mqueue_inode_info), 0,
1245                                 SLAB_HWCACHE_ALIGN, init_once);
1246         if (mqueue_inode_cachep == NULL)
1247                 return -ENOMEM;
1248
1249         /* ignore failues - they are not fatal */
1250         mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1251
1252         error = register_filesystem(&mqueue_fs_type);
1253         if (error)
1254                 goto out_sysctl;
1255
1256         if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1257                 error = PTR_ERR(mqueue_mnt);
1258                 goto out_filesystem;
1259         }
1260
1261         /* internal initialization - not common for vfs */
1262         queues_count = 0;
1263         spin_lock_init(&mq_lock);
1264
1265         return 0;
1266
1267 out_filesystem:
1268         unregister_filesystem(&mqueue_fs_type);
1269 out_sysctl:
1270         if (mq_sysctl_table)
1271                 unregister_sysctl_table(mq_sysctl_table);
1272         kmem_cache_destroy(mqueue_inode_cachep);
1273         return error;
1274 }
1275
1276 __initcall(init_mqueue_fs);