Fix race between attach_task and cpuset_exit
[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 /* used by sysctl */
48 #define FS_MQUEUE       1
49 #define CTL_QUEUESMAX   2
50 #define CTL_MSGMAX      3
51 #define CTL_MSGSIZEMAX  4
52
53 /* default values */
54 #define DFLT_QUEUESMAX  256     /* max number of message queues */
55 #define DFLT_MSGMAX     10      /* max number of messages in each queue */
56 #define HARD_MSGMAX     (131072/sizeof(void*))
57 #define DFLT_MSGSIZEMAX 8192    /* max message size */
58
59
60 struct ext_wait_queue {         /* queue of sleeping tasks */
61         struct task_struct *task;
62         struct list_head list;
63         struct msg_msg *msg;    /* ptr of loaded message */
64         int state;              /* one of STATE_* values */
65 };
66
67 struct mqueue_inode_info {
68         spinlock_t lock;
69         struct inode vfs_inode;
70         wait_queue_head_t wait_q;
71
72         struct msg_msg **messages;
73         struct mq_attr attr;
74
75         struct sigevent notify;
76         struct pid* notify_owner;
77         struct user_struct *user;       /* user who created, for accounting */
78         struct sock *notify_sock;
79         struct sk_buff *notify_cookie;
80
81         /* for tasks waiting for free space and messages, respectively */
82         struct ext_wait_queue e_wait_q[2];
83
84         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
85 };
86
87 static const struct inode_operations mqueue_dir_inode_operations;
88 static const struct file_operations mqueue_file_operations;
89 static struct super_operations mqueue_super_ops;
90 static void remove_notification(struct mqueue_inode_info *info);
91
92 static spinlock_t mq_lock;
93 static struct kmem_cache *mqueue_inode_cachep;
94 static struct vfsmount *mqueue_mnt;
95
96 static unsigned int queues_count;
97 static unsigned int queues_max  = DFLT_QUEUESMAX;
98 static unsigned int msg_max     = DFLT_MSGMAX;
99 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
100
101 static struct ctl_table_header * mq_sysctl_table;
102
103 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
104 {
105         return container_of(inode, struct mqueue_inode_info, vfs_inode);
106 }
107
108 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
109                                                         struct mq_attr *attr)
110 {
111         struct inode *inode;
112
113         inode = new_inode(sb);
114         if (inode) {
115                 inode->i_mode = mode;
116                 inode->i_uid = current->fsuid;
117                 inode->i_gid = current->fsgid;
118                 inode->i_blocks = 0;
119                 inode->i_mtime = inode->i_ctime = inode->i_atime =
120                                 CURRENT_TIME;
121
122                 if (S_ISREG(mode)) {
123                         struct mqueue_inode_info *info;
124                         struct task_struct *p = current;
125                         struct user_struct *u = p->user;
126                         unsigned long mq_bytes, mq_msg_tblsz;
127
128                         inode->i_fop = &mqueue_file_operations;
129                         inode->i_size = FILENT_SIZE;
130                         /* mqueue specific info */
131                         info = MQUEUE_I(inode);
132                         spin_lock_init(&info->lock);
133                         init_waitqueue_head(&info->wait_q);
134                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
135                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
136                         info->messages = NULL;
137                         info->notify_owner = NULL;
138                         info->qsize = 0;
139                         info->user = NULL;      /* set when all is ok */
140                         memset(&info->attr, 0, sizeof(info->attr));
141                         info->attr.mq_maxmsg = DFLT_MSGMAX;
142                         info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
143                         if (attr) {
144                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
145                                 info->attr.mq_msgsize = attr->mq_msgsize;
146                         }
147                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
148                         mq_bytes = (mq_msg_tblsz +
149                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
150
151                         spin_lock(&mq_lock);
152                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
153                             u->mq_bytes + mq_bytes >
154                             p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
155                                 spin_unlock(&mq_lock);
156                                 goto out_inode;
157                         }
158                         u->mq_bytes += mq_bytes;
159                         spin_unlock(&mq_lock);
160
161                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
162                         if (!info->messages) {
163                                 spin_lock(&mq_lock);
164                                 u->mq_bytes -= mq_bytes;
165                                 spin_unlock(&mq_lock);
166                                 goto out_inode;
167                         }
168                         /* all is ok */
169                         info->user = get_uid(u);
170                 } else if (S_ISDIR(mode)) {
171                         inc_nlink(inode);
172                         /* Some things misbehave if size == 0 on a directory */
173                         inode->i_size = 2 * DIRENT_SIZE;
174                         inode->i_op = &mqueue_dir_inode_operations;
175                         inode->i_fop = &simple_dir_operations;
176                 }
177         }
178         return inode;
179 out_inode:
180         make_bad_inode(inode);
181         iput(inode);
182         return NULL;
183 }
184
185 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
186 {
187         struct inode *inode;
188
189         sb->s_blocksize = PAGE_CACHE_SIZE;
190         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
191         sb->s_magic = MQUEUE_MAGIC;
192         sb->s_op = &mqueue_super_ops;
193
194         inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
195         if (!inode)
196                 return -ENOMEM;
197
198         sb->s_root = d_alloc_root(inode);
199         if (!sb->s_root) {
200                 iput(inode);
201                 return -ENOMEM;
202         }
203
204         return 0;
205 }
206
207 static int mqueue_get_sb(struct file_system_type *fs_type,
208                          int flags, const char *dev_name,
209                          void *data, struct vfsmount *mnt)
210 {
211         return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
212 }
213
214 static void init_once(void *foo, struct kmem_cache * cachep, unsigned long flags)
215 {
216         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
217
218         if (flags & SLAB_CTOR_CONSTRUCTOR)
219                 inode_init_once(&p->vfs_inode);
220 }
221
222 static struct inode *mqueue_alloc_inode(struct super_block *sb)
223 {
224         struct mqueue_inode_info *ei;
225
226         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
227         if (!ei)
228                 return NULL;
229         return &ei->vfs_inode;
230 }
231
232 static void mqueue_destroy_inode(struct inode *inode)
233 {
234         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
235 }
236
237 static void mqueue_delete_inode(struct inode *inode)
238 {
239         struct mqueue_inode_info *info;
240         struct user_struct *user;
241         unsigned long mq_bytes;
242         int i;
243
244         if (S_ISDIR(inode->i_mode)) {
245                 clear_inode(inode);
246                 return;
247         }
248         info = MQUEUE_I(inode);
249         spin_lock(&info->lock);
250         for (i = 0; i < info->attr.mq_curmsgs; i++)
251                 free_msg(info->messages[i]);
252         kfree(info->messages);
253         spin_unlock(&info->lock);
254
255         clear_inode(inode);
256
257         mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
258                    (info->attr.mq_maxmsg * info->attr.mq_msgsize));
259         user = info->user;
260         if (user) {
261                 spin_lock(&mq_lock);
262                 user->mq_bytes -= mq_bytes;
263                 queues_count--;
264                 spin_unlock(&mq_lock);
265                 free_uid(user);
266         }
267 }
268
269 static int mqueue_create(struct inode *dir, struct dentry *dentry,
270                                 int mode, struct nameidata *nd)
271 {
272         struct inode *inode;
273         struct mq_attr *attr = dentry->d_fsdata;
274         int error;
275
276         spin_lock(&mq_lock);
277         if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
278                 error = -ENOSPC;
279                 goto out_lock;
280         }
281         queues_count++;
282         spin_unlock(&mq_lock);
283
284         inode = mqueue_get_inode(dir->i_sb, mode, attr);
285         if (!inode) {
286                 error = -ENOMEM;
287                 spin_lock(&mq_lock);
288                 queues_count--;
289                 goto out_lock;
290         }
291
292         dir->i_size += DIRENT_SIZE;
293         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
294
295         d_instantiate(dentry, inode);
296         dget(dentry);
297         return 0;
298 out_lock:
299         spin_unlock(&mq_lock);
300         return error;
301 }
302
303 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
304 {
305         struct inode *inode = dentry->d_inode;
306
307         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
308         dir->i_size -= DIRENT_SIZE;
309         drop_nlink(inode);
310         dput(dentry);
311         return 0;
312 }
313
314 /*
315 *       This is routine for system read from queue file.
316 *       To avoid mess with doing here some sort of mq_receive we allow
317 *       to read only queue size & notification info (the only values
318 *       that are interesting from user point of view and aren't accessible
319 *       through std routines)
320 */
321 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
322                                 size_t count, loff_t * off)
323 {
324         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
325         char buffer[FILENT_SIZE];
326         size_t slen;
327         loff_t o;
328
329         if (!count)
330                 return 0;
331
332         spin_lock(&info->lock);
333         snprintf(buffer, sizeof(buffer),
334                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
335                         info->qsize,
336                         info->notify_owner ? info->notify.sigev_notify : 0,
337                         (info->notify_owner &&
338                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
339                                 info->notify.sigev_signo : 0,
340                         pid_nr(info->notify_owner));
341         spin_unlock(&info->lock);
342         buffer[sizeof(buffer)-1] = '\0';
343         slen = strlen(buffer)+1;
344
345         o = *off;
346         if (o > slen)
347                 return 0;
348
349         if (o + count > slen)
350                 count = slen - o;
351
352         if (copy_to_user(u_data, buffer + o, count))
353                 return -EFAULT;
354
355         *off = o + count;
356         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
357         return count;
358 }
359
360 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
361 {
362         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
363
364         spin_lock(&info->lock);
365         if (task_tgid(current) == info->notify_owner)
366                 remove_notification(info);
367
368         spin_unlock(&info->lock);
369         return 0;
370 }
371
372 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
373 {
374         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
375         int retval = 0;
376
377         poll_wait(filp, &info->wait_q, poll_tab);
378
379         spin_lock(&info->lock);
380         if (info->attr.mq_curmsgs)
381                 retval = POLLIN | POLLRDNORM;
382
383         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
384                 retval |= POLLOUT | POLLWRNORM;
385         spin_unlock(&info->lock);
386
387         return retval;
388 }
389
390 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
391 static void wq_add(struct mqueue_inode_info *info, int sr,
392                         struct ext_wait_queue *ewp)
393 {
394         struct ext_wait_queue *walk;
395
396         ewp->task = current;
397
398         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
399                 if (walk->task->static_prio <= current->static_prio) {
400                         list_add_tail(&ewp->list, &walk->list);
401                         return;
402                 }
403         }
404         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
405 }
406
407 /*
408  * Puts current task to sleep. Caller must hold queue lock. After return
409  * lock isn't held.
410  * sr: SEND or RECV
411  */
412 static int wq_sleep(struct mqueue_inode_info *info, int sr,
413                         long timeout, struct ext_wait_queue *ewp)
414 {
415         int retval;
416         signed long time;
417
418         wq_add(info, sr, ewp);
419
420         for (;;) {
421                 set_current_state(TASK_INTERRUPTIBLE);
422
423                 spin_unlock(&info->lock);
424                 time = schedule_timeout(timeout);
425
426                 while (ewp->state == STATE_PENDING)
427                         cpu_relax();
428
429                 if (ewp->state == STATE_READY) {
430                         retval = 0;
431                         goto out;
432                 }
433                 spin_lock(&info->lock);
434                 if (ewp->state == STATE_READY) {
435                         retval = 0;
436                         goto out_unlock;
437                 }
438                 if (signal_pending(current)) {
439                         retval = -ERESTARTSYS;
440                         break;
441                 }
442                 if (time == 0) {
443                         retval = -ETIMEDOUT;
444                         break;
445                 }
446         }
447         list_del(&ewp->list);
448 out_unlock:
449         spin_unlock(&info->lock);
450 out:
451         return retval;
452 }
453
454 /*
455  * Returns waiting task that should be serviced first or NULL if none exists
456  */
457 static struct ext_wait_queue *wq_get_first_waiter(
458                 struct mqueue_inode_info *info, int sr)
459 {
460         struct list_head *ptr;
461
462         ptr = info->e_wait_q[sr].list.prev;
463         if (ptr == &info->e_wait_q[sr].list)
464                 return NULL;
465         return list_entry(ptr, struct ext_wait_queue, list);
466 }
467
468 /* Auxiliary functions to manipulate messages' list */
469 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
470 {
471         int k;
472
473         k = info->attr.mq_curmsgs - 1;
474         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
475                 info->messages[k + 1] = info->messages[k];
476                 k--;
477         }
478         info->attr.mq_curmsgs++;
479         info->qsize += ptr->m_ts;
480         info->messages[k + 1] = ptr;
481 }
482
483 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
484 {
485         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
486         return info->messages[info->attr.mq_curmsgs];
487 }
488
489 static inline void set_cookie(struct sk_buff *skb, char code)
490 {
491         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
492 }
493
494 /*
495  * The next function is only to split too long sys_mq_timedsend
496  */
497 static void __do_notify(struct mqueue_inode_info *info)
498 {
499         /* notification
500          * invoked when there is registered process and there isn't process
501          * waiting synchronously for message AND state of queue changed from
502          * empty to not empty. Here we are sure that no one is waiting
503          * synchronously. */
504         if (info->notify_owner &&
505             info->attr.mq_curmsgs == 1) {
506                 struct siginfo sig_i;
507                 switch (info->notify.sigev_notify) {
508                 case SIGEV_NONE:
509                         break;
510                 case SIGEV_SIGNAL:
511                         /* sends signal */
512
513                         sig_i.si_signo = info->notify.sigev_signo;
514                         sig_i.si_errno = 0;
515                         sig_i.si_code = SI_MESGQ;
516                         sig_i.si_value = info->notify.sigev_value;
517                         sig_i.si_pid = current->tgid;
518                         sig_i.si_uid = current->uid;
519
520                         kill_pid_info(info->notify.sigev_signo,
521                                       &sig_i, info->notify_owner);
522                         break;
523                 case SIGEV_THREAD:
524                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
525                         netlink_sendskb(info->notify_sock,
526                                         info->notify_cookie, 0);
527                         break;
528                 }
529                 /* after notification unregisters process */
530                 put_pid(info->notify_owner);
531                 info->notify_owner = NULL;
532         }
533         wake_up(&info->wait_q);
534 }
535
536 static long prepare_timeout(const struct timespec __user *u_arg)
537 {
538         struct timespec ts, nowts;
539         long timeout;
540
541         if (u_arg) {
542                 if (unlikely(copy_from_user(&ts, u_arg,
543                                         sizeof(struct timespec))))
544                         return -EFAULT;
545
546                 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
547                         || ts.tv_nsec >= NSEC_PER_SEC))
548                         return -EINVAL;
549                 nowts = CURRENT_TIME;
550                 /* first subtract as jiffies can't be too big */
551                 ts.tv_sec -= nowts.tv_sec;
552                 if (ts.tv_nsec < nowts.tv_nsec) {
553                         ts.tv_nsec += NSEC_PER_SEC;
554                         ts.tv_sec--;
555                 }
556                 ts.tv_nsec -= nowts.tv_nsec;
557                 if (ts.tv_sec < 0)
558                         return 0;
559
560                 timeout = timespec_to_jiffies(&ts) + 1;
561         } else
562                 return MAX_SCHEDULE_TIMEOUT;
563
564         return timeout;
565 }
566
567 static void remove_notification(struct mqueue_inode_info *info)
568 {
569         if (info->notify_owner != NULL &&
570             info->notify.sigev_notify == SIGEV_THREAD) {
571                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
572                 netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
573         }
574         put_pid(info->notify_owner);
575         info->notify_owner = NULL;
576 }
577
578 static int mq_attr_ok(struct mq_attr *attr)
579 {
580         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
581                 return 0;
582         if (capable(CAP_SYS_RESOURCE)) {
583                 if (attr->mq_maxmsg > HARD_MSGMAX)
584                         return 0;
585         } else {
586                 if (attr->mq_maxmsg > msg_max ||
587                                 attr->mq_msgsize > msgsize_max)
588                         return 0;
589         }
590         /* check for overflow */
591         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
592                 return 0;
593         if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
594             (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
595             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
596                 return 0;
597         return 1;
598 }
599
600 /*
601  * Invoked when creating a new queue via sys_mq_open
602  */
603 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
604                         int oflag, mode_t mode, struct mq_attr __user *u_attr)
605 {
606         struct mq_attr attr;
607         int ret;
608
609         if (u_attr) {
610                 ret = -EFAULT;
611                 if (copy_from_user(&attr, u_attr, sizeof(attr)))
612                         goto out;
613                 ret = -EINVAL;
614                 if (!mq_attr_ok(&attr))
615                         goto out;
616                 /* store for use during create */
617                 dentry->d_fsdata = &attr;
618         }
619
620         mode &= ~current->fs->umask;
621         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
622         dentry->d_fsdata = NULL;
623         if (ret)
624                 goto out;
625
626         return dentry_open(dentry, mqueue_mnt, oflag);
627
628 out:
629         dput(dentry);
630         mntput(mqueue_mnt);
631         return ERR_PTR(ret);
632 }
633
634 /* Opens existing queue */
635 static struct file *do_open(struct dentry *dentry, int oflag)
636 {
637 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
638                                         MAY_READ | MAY_WRITE };
639
640         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
641                 dput(dentry);
642                 mntput(mqueue_mnt);
643                 return ERR_PTR(-EINVAL);
644         }
645
646         if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
647                 dput(dentry);
648                 mntput(mqueue_mnt);
649                 return ERR_PTR(-EACCES);
650         }
651
652         return dentry_open(dentry, mqueue_mnt, oflag);
653 }
654
655 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
656                                 struct mq_attr __user *u_attr)
657 {
658         struct dentry *dentry;
659         struct file *filp;
660         char *name;
661         int fd, error;
662
663         error = audit_mq_open(oflag, mode, u_attr);
664         if (error != 0)
665                 return error;
666
667         if (IS_ERR(name = getname(u_name)))
668                 return PTR_ERR(name);
669
670         fd = get_unused_fd();
671         if (fd < 0)
672                 goto out_putname;
673
674         mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
675         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
676         if (IS_ERR(dentry)) {
677                 error = PTR_ERR(dentry);
678                 goto out_err;
679         }
680         mntget(mqueue_mnt);
681
682         if (oflag & O_CREAT) {
683                 if (dentry->d_inode) {  /* entry already exists */
684                         error = -EEXIST;
685                         if (oflag & O_EXCL)
686                                 goto out;
687                         filp = do_open(dentry, oflag);
688                 } else {
689                         filp = do_create(mqueue_mnt->mnt_root, dentry,
690                                                 oflag, mode, u_attr);
691                 }
692         } else {
693                 error = -ENOENT;
694                 if (!dentry->d_inode)
695                         goto out;
696                 filp = do_open(dentry, oflag);
697         }
698
699         if (IS_ERR(filp)) {
700                 error = PTR_ERR(filp);
701                 goto out_putfd;
702         }
703
704         set_close_on_exec(fd, 1);
705         fd_install(fd, filp);
706         goto out_upsem;
707
708 out:
709         dput(dentry);
710         mntput(mqueue_mnt);
711 out_putfd:
712         put_unused_fd(fd);
713 out_err:
714         fd = error;
715 out_upsem:
716         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
717 out_putname:
718         putname(name);
719         return fd;
720 }
721
722 asmlinkage long sys_mq_unlink(const char __user *u_name)
723 {
724         int err;
725         char *name;
726         struct dentry *dentry;
727         struct inode *inode = NULL;
728
729         name = getname(u_name);
730         if (IS_ERR(name))
731                 return PTR_ERR(name);
732
733         mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
734                         I_MUTEX_PARENT);
735         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
736         if (IS_ERR(dentry)) {
737                 err = PTR_ERR(dentry);
738                 goto out_unlock;
739         }
740
741         if (!dentry->d_inode) {
742                 err = -ENOENT;
743                 goto out_err;
744         }
745
746         inode = dentry->d_inode;
747         if (inode)
748                 atomic_inc(&inode->i_count);
749
750         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
751 out_err:
752         dput(dentry);
753
754 out_unlock:
755         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
756         putname(name);
757         if (inode)
758                 iput(inode);
759
760         return err;
761 }
762
763 /* Pipelined send and receive functions.
764  *
765  * If a receiver finds no waiting message, then it registers itself in the
766  * list of waiting receivers. A sender checks that list before adding the new
767  * message into the message array. If there is a waiting receiver, then it
768  * bypasses the message array and directly hands the message over to the
769  * receiver.
770  * The receiver accepts the message and returns without grabbing the queue
771  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
772  * are necessary. The same algorithm is used for sysv semaphores, see
773  * ipc/sem.c for more details.
774  *
775  * The same algorithm is used for senders.
776  */
777
778 /* pipelined_send() - send a message directly to the task waiting in
779  * sys_mq_timedreceive() (without inserting message into a queue).
780  */
781 static inline void pipelined_send(struct mqueue_inode_info *info,
782                                   struct msg_msg *message,
783                                   struct ext_wait_queue *receiver)
784 {
785         receiver->msg = message;
786         list_del(&receiver->list);
787         receiver->state = STATE_PENDING;
788         wake_up_process(receiver->task);
789         smp_wmb();
790         receiver->state = STATE_READY;
791 }
792
793 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
794  * gets its message and put to the queue (we have one free place for sure). */
795 static inline void pipelined_receive(struct mqueue_inode_info *info)
796 {
797         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
798
799         if (!sender) {
800                 /* for poll */
801                 wake_up_interruptible(&info->wait_q);
802                 return;
803         }
804         msg_insert(sender->msg, info);
805         list_del(&sender->list);
806         sender->state = STATE_PENDING;
807         wake_up_process(sender->task);
808         smp_wmb();
809         sender->state = STATE_READY;
810 }
811
812 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
813         size_t msg_len, unsigned int msg_prio,
814         const struct timespec __user *u_abs_timeout)
815 {
816         struct file *filp;
817         struct inode *inode;
818         struct ext_wait_queue wait;
819         struct ext_wait_queue *receiver;
820         struct msg_msg *msg_ptr;
821         struct mqueue_inode_info *info;
822         long timeout;
823         int ret;
824
825         ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
826         if (ret != 0)
827                 return ret;
828
829         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
830                 return -EINVAL;
831
832         timeout = prepare_timeout(u_abs_timeout);
833
834         ret = -EBADF;
835         filp = fget(mqdes);
836         if (unlikely(!filp))
837                 goto out;
838
839         inode = filp->f_path.dentry->d_inode;
840         if (unlikely(filp->f_op != &mqueue_file_operations))
841                 goto out_fput;
842         info = MQUEUE_I(inode);
843
844         if (unlikely(!(filp->f_mode & FMODE_WRITE)))
845                 goto out_fput;
846
847         if (unlikely(msg_len > info->attr.mq_msgsize)) {
848                 ret = -EMSGSIZE;
849                 goto out_fput;
850         }
851
852         /* First try to allocate memory, before doing anything with
853          * existing queues. */
854         msg_ptr = load_msg(u_msg_ptr, msg_len);
855         if (IS_ERR(msg_ptr)) {
856                 ret = PTR_ERR(msg_ptr);
857                 goto out_fput;
858         }
859         msg_ptr->m_ts = msg_len;
860         msg_ptr->m_type = msg_prio;
861
862         spin_lock(&info->lock);
863
864         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
865                 if (filp->f_flags & O_NONBLOCK) {
866                         spin_unlock(&info->lock);
867                         ret = -EAGAIN;
868                 } else if (unlikely(timeout < 0)) {
869                         spin_unlock(&info->lock);
870                         ret = timeout;
871                 } else {
872                         wait.task = current;
873                         wait.msg = (void *) msg_ptr;
874                         wait.state = STATE_NONE;
875                         ret = wq_sleep(info, SEND, timeout, &wait);
876                 }
877                 if (ret < 0)
878                         free_msg(msg_ptr);
879         } else {
880                 receiver = wq_get_first_waiter(info, RECV);
881                 if (receiver) {
882                         pipelined_send(info, msg_ptr, receiver);
883                 } else {
884                         /* adds message to the queue */
885                         msg_insert(msg_ptr, info);
886                         __do_notify(info);
887                 }
888                 inode->i_atime = inode->i_mtime = inode->i_ctime =
889                                 CURRENT_TIME;
890                 spin_unlock(&info->lock);
891                 ret = 0;
892         }
893 out_fput:
894         fput(filp);
895 out:
896         return ret;
897 }
898
899 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
900         size_t msg_len, unsigned int __user *u_msg_prio,
901         const struct timespec __user *u_abs_timeout)
902 {
903         long timeout;
904         ssize_t ret;
905         struct msg_msg *msg_ptr;
906         struct file *filp;
907         struct inode *inode;
908         struct mqueue_inode_info *info;
909         struct ext_wait_queue wait;
910
911         ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
912         if (ret != 0)
913                 return ret;
914
915         timeout = prepare_timeout(u_abs_timeout);
916
917         ret = -EBADF;
918         filp = fget(mqdes);
919         if (unlikely(!filp))
920                 goto out;
921
922         inode = filp->f_path.dentry->d_inode;
923         if (unlikely(filp->f_op != &mqueue_file_operations))
924                 goto out_fput;
925         info = MQUEUE_I(inode);
926
927         if (unlikely(!(filp->f_mode & FMODE_READ)))
928                 goto out_fput;
929
930         /* checks if buffer is big enough */
931         if (unlikely(msg_len < info->attr.mq_msgsize)) {
932                 ret = -EMSGSIZE;
933                 goto out_fput;
934         }
935
936         spin_lock(&info->lock);
937         if (info->attr.mq_curmsgs == 0) {
938                 if (filp->f_flags & O_NONBLOCK) {
939                         spin_unlock(&info->lock);
940                         ret = -EAGAIN;
941                         msg_ptr = NULL;
942                 } else if (unlikely(timeout < 0)) {
943                         spin_unlock(&info->lock);
944                         ret = timeout;
945                         msg_ptr = NULL;
946                 } else {
947                         wait.task = current;
948                         wait.state = STATE_NONE;
949                         ret = wq_sleep(info, RECV, timeout, &wait);
950                         msg_ptr = wait.msg;
951                 }
952         } else {
953                 msg_ptr = msg_get(info);
954
955                 inode->i_atime = inode->i_mtime = inode->i_ctime =
956                                 CURRENT_TIME;
957
958                 /* There is now free space in queue. */
959                 pipelined_receive(info);
960                 spin_unlock(&info->lock);
961                 ret = 0;
962         }
963         if (ret == 0) {
964                 ret = msg_ptr->m_ts;
965
966                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
967                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
968                         ret = -EFAULT;
969                 }
970                 free_msg(msg_ptr);
971         }
972 out_fput:
973         fput(filp);
974 out:
975         return ret;
976 }
977
978 /*
979  * Notes: the case when user wants us to deregister (with NULL as pointer)
980  * and he isn't currently owner of notification, will be silently discarded.
981  * It isn't explicitly defined in the POSIX.
982  */
983 asmlinkage long sys_mq_notify(mqd_t mqdes,
984                                 const struct sigevent __user *u_notification)
985 {
986         int ret;
987         struct file *filp;
988         struct sock *sock;
989         struct inode *inode;
990         struct sigevent notification;
991         struct mqueue_inode_info *info;
992         struct sk_buff *nc;
993
994         ret = audit_mq_notify(mqdes, u_notification);
995         if (ret != 0)
996                 return ret;
997
998         nc = NULL;
999         sock = NULL;
1000         if (u_notification != NULL) {
1001                 if (copy_from_user(&notification, u_notification,
1002                                         sizeof(struct sigevent)))
1003                         return -EFAULT;
1004
1005                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1006                              notification.sigev_notify != SIGEV_SIGNAL &&
1007                              notification.sigev_notify != SIGEV_THREAD))
1008                         return -EINVAL;
1009                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1010                         !valid_signal(notification.sigev_signo)) {
1011                         return -EINVAL;
1012                 }
1013                 if (notification.sigev_notify == SIGEV_THREAD) {
1014                         /* create the notify skb */
1015                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1016                         ret = -ENOMEM;
1017                         if (!nc)
1018                                 goto out;
1019                         ret = -EFAULT;
1020                         if (copy_from_user(nc->data,
1021                                         notification.sigev_value.sival_ptr,
1022                                         NOTIFY_COOKIE_LEN)) {
1023                                 goto out;
1024                         }
1025
1026                         /* TODO: add a header? */
1027                         skb_put(nc, NOTIFY_COOKIE_LEN);
1028                         /* and attach it to the socket */
1029 retry:
1030                         filp = fget(notification.sigev_signo);
1031                         ret = -EBADF;
1032                         if (!filp)
1033                                 goto out;
1034                         sock = netlink_getsockbyfilp(filp);
1035                         fput(filp);
1036                         if (IS_ERR(sock)) {
1037                                 ret = PTR_ERR(sock);
1038                                 sock = NULL;
1039                                 goto out;
1040                         }
1041
1042                         ret = netlink_attachskb(sock, nc, 0,
1043                                         MAX_SCHEDULE_TIMEOUT, NULL);
1044                         if (ret == 1)
1045                                 goto retry;
1046                         if (ret) {
1047                                 sock = NULL;
1048                                 nc = NULL;
1049                                 goto out;
1050                         }
1051                 }
1052         }
1053
1054         ret = -EBADF;
1055         filp = fget(mqdes);
1056         if (!filp)
1057                 goto out;
1058
1059         inode = filp->f_path.dentry->d_inode;
1060         if (unlikely(filp->f_op != &mqueue_file_operations))
1061                 goto out_fput;
1062         info = MQUEUE_I(inode);
1063
1064         ret = 0;
1065         spin_lock(&info->lock);
1066         if (u_notification == NULL) {
1067                 if (info->notify_owner == task_tgid(current)) {
1068                         remove_notification(info);
1069                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1070                 }
1071         } else if (info->notify_owner != NULL) {
1072                 ret = -EBUSY;
1073         } else {
1074                 switch (notification.sigev_notify) {
1075                 case SIGEV_NONE:
1076                         info->notify.sigev_notify = SIGEV_NONE;
1077                         break;
1078                 case SIGEV_THREAD:
1079                         info->notify_sock = sock;
1080                         info->notify_cookie = nc;
1081                         sock = NULL;
1082                         nc = NULL;
1083                         info->notify.sigev_notify = SIGEV_THREAD;
1084                         break;
1085                 case SIGEV_SIGNAL:
1086                         info->notify.sigev_signo = notification.sigev_signo;
1087                         info->notify.sigev_value = notification.sigev_value;
1088                         info->notify.sigev_notify = SIGEV_SIGNAL;
1089                         break;
1090                 }
1091
1092                 info->notify_owner = get_pid(task_tgid(current));
1093                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1094         }
1095         spin_unlock(&info->lock);
1096 out_fput:
1097         fput(filp);
1098 out:
1099         if (sock) {
1100                 netlink_detachskb(sock, nc);
1101         } else if (nc) {
1102                 dev_kfree_skb(nc);
1103         }
1104         return ret;
1105 }
1106
1107 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1108                         const struct mq_attr __user *u_mqstat,
1109                         struct mq_attr __user *u_omqstat)
1110 {
1111         int ret;
1112         struct mq_attr mqstat, omqstat;
1113         struct file *filp;
1114         struct inode *inode;
1115         struct mqueue_inode_info *info;
1116
1117         if (u_mqstat != NULL) {
1118                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1119                         return -EFAULT;
1120                 if (mqstat.mq_flags & (~O_NONBLOCK))
1121                         return -EINVAL;
1122         }
1123
1124         ret = -EBADF;
1125         filp = fget(mqdes);
1126         if (!filp)
1127                 goto out;
1128
1129         inode = filp->f_path.dentry->d_inode;
1130         if (unlikely(filp->f_op != &mqueue_file_operations))
1131                 goto out_fput;
1132         info = MQUEUE_I(inode);
1133
1134         spin_lock(&info->lock);
1135
1136         omqstat = info->attr;
1137         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1138         if (u_mqstat) {
1139                 ret = audit_mq_getsetattr(mqdes, &mqstat);
1140                 if (ret != 0)
1141                         goto out;
1142                 if (mqstat.mq_flags & O_NONBLOCK)
1143                         filp->f_flags |= O_NONBLOCK;
1144                 else
1145                         filp->f_flags &= ~O_NONBLOCK;
1146
1147                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1148         }
1149
1150         spin_unlock(&info->lock);
1151
1152         ret = 0;
1153         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1154                                                 sizeof(struct mq_attr)))
1155                 ret = -EFAULT;
1156
1157 out_fput:
1158         fput(filp);
1159 out:
1160         return ret;
1161 }
1162
1163 static const struct inode_operations mqueue_dir_inode_operations = {
1164         .lookup = simple_lookup,
1165         .create = mqueue_create,
1166         .unlink = mqueue_unlink,
1167 };
1168
1169 static const struct file_operations mqueue_file_operations = {
1170         .flush = mqueue_flush_file,
1171         .poll = mqueue_poll_file,
1172         .read = mqueue_read_file,
1173 };
1174
1175 static struct super_operations mqueue_super_ops = {
1176         .alloc_inode = mqueue_alloc_inode,
1177         .destroy_inode = mqueue_destroy_inode,
1178         .statfs = simple_statfs,
1179         .delete_inode = mqueue_delete_inode,
1180         .drop_inode = generic_delete_inode,
1181 };
1182
1183 static struct file_system_type mqueue_fs_type = {
1184         .name = "mqueue",
1185         .get_sb = mqueue_get_sb,
1186         .kill_sb = kill_litter_super,
1187 };
1188
1189 static int msg_max_limit_min = DFLT_MSGMAX;
1190 static int msg_max_limit_max = HARD_MSGMAX;
1191
1192 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1193 static int msg_maxsize_limit_max = INT_MAX;
1194
1195 static ctl_table mq_sysctls[] = {
1196         {
1197                 .ctl_name       = CTL_QUEUESMAX,
1198                 .procname       = "queues_max",
1199                 .data           = &queues_max,
1200                 .maxlen         = sizeof(int),
1201                 .mode           = 0644,
1202                 .proc_handler   = &proc_dointvec,
1203         },
1204         {
1205                 .ctl_name       = CTL_MSGMAX,
1206                 .procname       = "msg_max",
1207                 .data           = &msg_max,
1208                 .maxlen         = sizeof(int),
1209                 .mode           = 0644,
1210                 .proc_handler   = &proc_dointvec_minmax,
1211                 .extra1         = &msg_max_limit_min,
1212                 .extra2         = &msg_max_limit_max,
1213         },
1214         {
1215                 .ctl_name       = CTL_MSGSIZEMAX,
1216                 .procname       = "msgsize_max",
1217                 .data           = &msgsize_max,
1218                 .maxlen         = sizeof(int),
1219                 .mode           = 0644,
1220                 .proc_handler   = &proc_dointvec_minmax,
1221                 .extra1         = &msg_maxsize_limit_min,
1222                 .extra2         = &msg_maxsize_limit_max,
1223         },
1224         { .ctl_name = 0 }
1225 };
1226
1227 static ctl_table mq_sysctl_dir[] = {
1228         {
1229                 .ctl_name       = FS_MQUEUE,
1230                 .procname       = "mqueue",
1231                 .mode           = 0555,
1232                 .child          = mq_sysctls,
1233         },
1234         { .ctl_name = 0 }
1235 };
1236
1237 static ctl_table mq_sysctl_root[] = {
1238         {
1239                 .ctl_name       = CTL_FS,
1240                 .procname       = "fs",
1241                 .mode           = 0555,
1242                 .child          = mq_sysctl_dir,
1243         },
1244         { .ctl_name = 0 }
1245 };
1246
1247 static int __init init_mqueue_fs(void)
1248 {
1249         int error;
1250
1251         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1252                                 sizeof(struct mqueue_inode_info), 0,
1253                                 SLAB_HWCACHE_ALIGN, init_once, NULL);
1254         if (mqueue_inode_cachep == NULL)
1255                 return -ENOMEM;
1256
1257         /* ignore failues - they are not fatal */
1258         mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1259
1260         error = register_filesystem(&mqueue_fs_type);
1261         if (error)
1262                 goto out_sysctl;
1263
1264         if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1265                 error = PTR_ERR(mqueue_mnt);
1266                 goto out_filesystem;
1267         }
1268
1269         /* internal initialization - not common for vfs */
1270         queues_count = 0;
1271         spin_lock_init(&mq_lock);
1272
1273         return 0;
1274
1275 out_filesystem:
1276         unregister_filesystem(&mqueue_fs_type);
1277 out_sysctl:
1278         if (mq_sysctl_table)
1279                 unregister_sysctl_table(mq_sysctl_table);
1280         kmem_cache_destroy(mqueue_inode_cachep);
1281         return error;
1282 }
1283
1284 __initcall(init_mqueue_fs);