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