ipc: store ipcs into IDRs
[linux-2.6.git] / ipc / mqueue.c
1 /*
2  * POSIX message queues filesystem for Linux.
3  *
4  * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
5  *                          Michal Wronski          (michal.wronski@gmail.com)
6  *
7  * Spinlocks:               Mohamed Abbas           (abbas.mohamed@intel.com)
8  * Lockless receive & send, fd based notify:
9  *                          Manfred Spraul          (manfred@colorfullife.com)
10  *
11  * Audit:                   George Wilson           (ltcgcw@us.ibm.com)
12  *
13  * This file is released under the GPL.
14  */
15
16 #include <linux/capability.h>
17 #include <linux/init.h>
18 #include <linux/pagemap.h>
19 #include <linux/file.h>
20 #include <linux/mount.h>
21 #include <linux/namei.h>
22 #include <linux/sysctl.h>
23 #include <linux/poll.h>
24 #include <linux/mqueue.h>
25 #include <linux/msg.h>
26 #include <linux/skbuff.h>
27 #include <linux/netlink.h>
28 #include <linux/syscalls.h>
29 #include <linux/audit.h>
30 #include <linux/signal.h>
31 #include <linux/mutex.h>
32 #include <linux/nsproxy.h>
33 #include <linux/pid.h>
34
35 #include <net/sock.h>
36 #include "util.h"
37
38 #define MQUEUE_MAGIC    0x19800202
39 #define DIRENT_SIZE     20
40 #define FILENT_SIZE     80
41
42 #define SEND            0
43 #define RECV            1
44
45 #define STATE_NONE      0
46 #define STATE_PENDING   1
47 #define STATE_READY     2
48
49 /* default values */
50 #define DFLT_QUEUESMAX  256     /* max number of message queues */
51 #define DFLT_MSGMAX     10      /* max number of messages in each queue */
52 #define HARD_MSGMAX     (131072/sizeof(void*))
53 #define DFLT_MSGSIZEMAX 8192    /* max message size */
54
55
56 struct ext_wait_queue {         /* queue of sleeping tasks */
57         struct task_struct *task;
58         struct list_head list;
59         struct msg_msg *msg;    /* ptr of loaded message */
60         int state;              /* one of STATE_* values */
61 };
62
63 struct mqueue_inode_info {
64         spinlock_t lock;
65         struct inode vfs_inode;
66         wait_queue_head_t wait_q;
67
68         struct msg_msg **messages;
69         struct mq_attr attr;
70
71         struct sigevent notify;
72         struct pid* notify_owner;
73         struct user_struct *user;       /* user who created, for accounting */
74         struct sock *notify_sock;
75         struct sk_buff *notify_cookie;
76
77         /* for tasks waiting for free space and messages, respectively */
78         struct ext_wait_queue e_wait_q[2];
79
80         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
81 };
82
83 static const struct inode_operations mqueue_dir_inode_operations;
84 static const struct file_operations mqueue_file_operations;
85 static struct super_operations mqueue_super_ops;
86 static void remove_notification(struct mqueue_inode_info *info);
87
88 static spinlock_t mq_lock;
89 static struct kmem_cache *mqueue_inode_cachep;
90 static struct vfsmount *mqueue_mnt;
91
92 static unsigned int queues_count;
93 static unsigned int queues_max  = DFLT_QUEUESMAX;
94 static unsigned int msg_max     = DFLT_MSGMAX;
95 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
96
97 static struct ctl_table_header * mq_sysctl_table;
98
99 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
100 {
101         return container_of(inode, struct mqueue_inode_info, vfs_inode);
102 }
103
104 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
105                                                         struct mq_attr *attr)
106 {
107         struct inode *inode;
108
109         inode = new_inode(sb);
110         if (inode) {
111                 inode->i_mode = mode;
112                 inode->i_uid = current->fsuid;
113                 inode->i_gid = current->fsgid;
114                 inode->i_blocks = 0;
115                 inode->i_mtime = inode->i_ctime = inode->i_atime =
116                                 CURRENT_TIME;
117
118                 if (S_ISREG(mode)) {
119                         struct mqueue_inode_info *info;
120                         struct task_struct *p = current;
121                         struct user_struct *u = p->user;
122                         unsigned long mq_bytes, mq_msg_tblsz;
123
124                         inode->i_fop = &mqueue_file_operations;
125                         inode->i_size = FILENT_SIZE;
126                         /* mqueue specific info */
127                         info = MQUEUE_I(inode);
128                         spin_lock_init(&info->lock);
129                         init_waitqueue_head(&info->wait_q);
130                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
131                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
132                         info->messages = NULL;
133                         info->notify_owner = NULL;
134                         info->qsize = 0;
135                         info->user = NULL;      /* set when all is ok */
136                         memset(&info->attr, 0, sizeof(info->attr));
137                         info->attr.mq_maxmsg = DFLT_MSGMAX;
138                         info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
139                         if (attr) {
140                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
141                                 info->attr.mq_msgsize = attr->mq_msgsize;
142                         }
143                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
144                         mq_bytes = (mq_msg_tblsz +
145                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
146
147                         spin_lock(&mq_lock);
148                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
149                             u->mq_bytes + mq_bytes >
150                             p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
151                                 spin_unlock(&mq_lock);
152                                 goto out_inode;
153                         }
154                         u->mq_bytes += mq_bytes;
155                         spin_unlock(&mq_lock);
156
157                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
158                         if (!info->messages) {
159                                 spin_lock(&mq_lock);
160                                 u->mq_bytes -= mq_bytes;
161                                 spin_unlock(&mq_lock);
162                                 goto out_inode;
163                         }
164                         /* all is ok */
165                         info->user = get_uid(u);
166                 } else if (S_ISDIR(mode)) {
167                         inc_nlink(inode);
168                         /* Some things misbehave if size == 0 on a directory */
169                         inode->i_size = 2 * DIRENT_SIZE;
170                         inode->i_op = &mqueue_dir_inode_operations;
171                         inode->i_fop = &simple_dir_operations;
172                 }
173         }
174         return inode;
175 out_inode:
176         make_bad_inode(inode);
177         iput(inode);
178         return NULL;
179 }
180
181 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
182 {
183         struct inode *inode;
184
185         sb->s_blocksize = PAGE_CACHE_SIZE;
186         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
187         sb->s_magic = MQUEUE_MAGIC;
188         sb->s_op = &mqueue_super_ops;
189
190         inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
191         if (!inode)
192                 return -ENOMEM;
193
194         sb->s_root = d_alloc_root(inode);
195         if (!sb->s_root) {
196                 iput(inode);
197                 return -ENOMEM;
198         }
199
200         return 0;
201 }
202
203 static int mqueue_get_sb(struct file_system_type *fs_type,
204                          int flags, const char *dev_name,
205                          void *data, struct vfsmount *mnt)
206 {
207         return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
208 }
209
210 static void init_once(struct kmem_cache *cachep, void *foo)
211 {
212         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
213
214         inode_init_once(&p->vfs_inode);
215 }
216
217 static struct inode *mqueue_alloc_inode(struct super_block *sb)
218 {
219         struct mqueue_inode_info *ei;
220
221         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
222         if (!ei)
223                 return NULL;
224         return &ei->vfs_inode;
225 }
226
227 static void mqueue_destroy_inode(struct inode *inode)
228 {
229         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
230 }
231
232 static void mqueue_delete_inode(struct inode *inode)
233 {
234         struct mqueue_inode_info *info;
235         struct user_struct *user;
236         unsigned long mq_bytes;
237         int i;
238
239         if (S_ISDIR(inode->i_mode)) {
240                 clear_inode(inode);
241                 return;
242         }
243         info = MQUEUE_I(inode);
244         spin_lock(&info->lock);
245         for (i = 0; i < info->attr.mq_curmsgs; i++)
246                 free_msg(info->messages[i]);
247         kfree(info->messages);
248         spin_unlock(&info->lock);
249
250         clear_inode(inode);
251
252         mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
253                    (info->attr.mq_maxmsg * info->attr.mq_msgsize));
254         user = info->user;
255         if (user) {
256                 spin_lock(&mq_lock);
257                 user->mq_bytes -= mq_bytes;
258                 queues_count--;
259                 spin_unlock(&mq_lock);
260                 free_uid(user);
261         }
262 }
263
264 static int mqueue_create(struct inode *dir, struct dentry *dentry,
265                                 int mode, struct nameidata *nd)
266 {
267         struct inode *inode;
268         struct mq_attr *attr = dentry->d_fsdata;
269         int error;
270
271         spin_lock(&mq_lock);
272         if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
273                 error = -ENOSPC;
274                 goto out_lock;
275         }
276         queues_count++;
277         spin_unlock(&mq_lock);
278
279         inode = mqueue_get_inode(dir->i_sb, mode, attr);
280         if (!inode) {
281                 error = -ENOMEM;
282                 spin_lock(&mq_lock);
283                 queues_count--;
284                 goto out_lock;
285         }
286
287         dir->i_size += DIRENT_SIZE;
288         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
289
290         d_instantiate(dentry, inode);
291         dget(dentry);
292         return 0;
293 out_lock:
294         spin_unlock(&mq_lock);
295         return error;
296 }
297
298 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
299 {
300         struct inode *inode = dentry->d_inode;
301
302         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
303         dir->i_size -= DIRENT_SIZE;
304         drop_nlink(inode);
305         dput(dentry);
306         return 0;
307 }
308
309 /*
310 *       This is routine for system read from queue file.
311 *       To avoid mess with doing here some sort of mq_receive we allow
312 *       to read only queue size & notification info (the only values
313 *       that are interesting from user point of view and aren't accessible
314 *       through std routines)
315 */
316 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
317                                 size_t count, loff_t * off)
318 {
319         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
320         char buffer[FILENT_SIZE];
321         size_t slen;
322         loff_t o;
323
324         if (!count)
325                 return 0;
326
327         spin_lock(&info->lock);
328         snprintf(buffer, sizeof(buffer),
329                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
330                         info->qsize,
331                         info->notify_owner ? info->notify.sigev_notify : 0,
332                         (info->notify_owner &&
333                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
334                                 info->notify.sigev_signo : 0,
335                         pid_nr_ns(info->notify_owner,
336                                 current->nsproxy->pid_ns));
337         spin_unlock(&info->lock);
338         buffer[sizeof(buffer)-1] = '\0';
339         slen = strlen(buffer)+1;
340
341         o = *off;
342         if (o > slen)
343                 return 0;
344
345         if (o + count > slen)
346                 count = slen - o;
347
348         if (copy_to_user(u_data, buffer + o, count))
349                 return -EFAULT;
350
351         *off = o + count;
352         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
353         return count;
354 }
355
356 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
357 {
358         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
359
360         spin_lock(&info->lock);
361         if (task_tgid(current) == info->notify_owner)
362                 remove_notification(info);
363
364         spin_unlock(&info->lock);
365         return 0;
366 }
367
368 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
369 {
370         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
371         int retval = 0;
372
373         poll_wait(filp, &info->wait_q, poll_tab);
374
375         spin_lock(&info->lock);
376         if (info->attr.mq_curmsgs)
377                 retval = POLLIN | POLLRDNORM;
378
379         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
380                 retval |= POLLOUT | POLLWRNORM;
381         spin_unlock(&info->lock);
382
383         return retval;
384 }
385
386 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
387 static void wq_add(struct mqueue_inode_info *info, int sr,
388                         struct ext_wait_queue *ewp)
389 {
390         struct ext_wait_queue *walk;
391
392         ewp->task = current;
393
394         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
395                 if (walk->task->static_prio <= current->static_prio) {
396                         list_add_tail(&ewp->list, &walk->list);
397                         return;
398                 }
399         }
400         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
401 }
402
403 /*
404  * Puts current task to sleep. Caller must hold queue lock. After return
405  * lock isn't held.
406  * sr: SEND or RECV
407  */
408 static int wq_sleep(struct mqueue_inode_info *info, int sr,
409                         long timeout, struct ext_wait_queue *ewp)
410 {
411         int retval;
412         signed long time;
413
414         wq_add(info, sr, ewp);
415
416         for (;;) {
417                 set_current_state(TASK_INTERRUPTIBLE);
418
419                 spin_unlock(&info->lock);
420                 time = schedule_timeout(timeout);
421
422                 while (ewp->state == STATE_PENDING)
423                         cpu_relax();
424
425                 if (ewp->state == STATE_READY) {
426                         retval = 0;
427                         goto out;
428                 }
429                 spin_lock(&info->lock);
430                 if (ewp->state == STATE_READY) {
431                         retval = 0;
432                         goto out_unlock;
433                 }
434                 if (signal_pending(current)) {
435                         retval = -ERESTARTSYS;
436                         break;
437                 }
438                 if (time == 0) {
439                         retval = -ETIMEDOUT;
440                         break;
441                 }
442         }
443         list_del(&ewp->list);
444 out_unlock:
445         spin_unlock(&info->lock);
446 out:
447         return retval;
448 }
449
450 /*
451  * Returns waiting task that should be serviced first or NULL if none exists
452  */
453 static struct ext_wait_queue *wq_get_first_waiter(
454                 struct mqueue_inode_info *info, int sr)
455 {
456         struct list_head *ptr;
457
458         ptr = info->e_wait_q[sr].list.prev;
459         if (ptr == &info->e_wait_q[sr].list)
460                 return NULL;
461         return list_entry(ptr, struct ext_wait_queue, list);
462 }
463
464 /* Auxiliary functions to manipulate messages' list */
465 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
466 {
467         int k;
468
469         k = info->attr.mq_curmsgs - 1;
470         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
471                 info->messages[k + 1] = info->messages[k];
472                 k--;
473         }
474         info->attr.mq_curmsgs++;
475         info->qsize += ptr->m_ts;
476         info->messages[k + 1] = ptr;
477 }
478
479 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
480 {
481         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
482         return info->messages[info->attr.mq_curmsgs];
483 }
484
485 static inline void set_cookie(struct sk_buff *skb, char code)
486 {
487         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
488 }
489
490 /*
491  * The next function is only to split too long sys_mq_timedsend
492  */
493 static void __do_notify(struct mqueue_inode_info *info)
494 {
495         /* notification
496          * invoked when there is registered process and there isn't process
497          * waiting synchronously for message AND state of queue changed from
498          * empty to not empty. Here we are sure that no one is waiting
499          * synchronously. */
500         if (info->notify_owner &&
501             info->attr.mq_curmsgs == 1) {
502                 struct siginfo sig_i;
503                 switch (info->notify.sigev_notify) {
504                 case SIGEV_NONE:
505                         break;
506                 case SIGEV_SIGNAL:
507                         /* sends signal */
508
509                         sig_i.si_signo = info->notify.sigev_signo;
510                         sig_i.si_errno = 0;
511                         sig_i.si_code = SI_MESGQ;
512                         sig_i.si_value = info->notify.sigev_value;
513                         sig_i.si_pid = task_pid_vnr(current);
514                         sig_i.si_uid = current->uid;
515
516                         kill_pid_info(info->notify.sigev_signo,
517                                       &sig_i, info->notify_owner);
518                         break;
519                 case SIGEV_THREAD:
520                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
521                         netlink_sendskb(info->notify_sock, info->notify_cookie);
522                         break;
523                 }
524                 /* after notification unregisters process */
525                 put_pid(info->notify_owner);
526                 info->notify_owner = NULL;
527         }
528         wake_up(&info->wait_q);
529 }
530
531 static long prepare_timeout(const struct timespec __user *u_arg)
532 {
533         struct timespec ts, nowts;
534         long timeout;
535
536         if (u_arg) {
537                 if (unlikely(copy_from_user(&ts, u_arg,
538                                         sizeof(struct timespec))))
539                         return -EFAULT;
540
541                 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
542                         || ts.tv_nsec >= NSEC_PER_SEC))
543                         return -EINVAL;
544                 nowts = CURRENT_TIME;
545                 /* first subtract as jiffies can't be too big */
546                 ts.tv_sec -= nowts.tv_sec;
547                 if (ts.tv_nsec < nowts.tv_nsec) {
548                         ts.tv_nsec += NSEC_PER_SEC;
549                         ts.tv_sec--;
550                 }
551                 ts.tv_nsec -= nowts.tv_nsec;
552                 if (ts.tv_sec < 0)
553                         return 0;
554
555                 timeout = timespec_to_jiffies(&ts) + 1;
556         } else
557                 return MAX_SCHEDULE_TIMEOUT;
558
559         return timeout;
560 }
561
562 static void remove_notification(struct mqueue_inode_info *info)
563 {
564         if (info->notify_owner != NULL &&
565             info->notify.sigev_notify == SIGEV_THREAD) {
566                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
567                 netlink_sendskb(info->notify_sock, info->notify_cookie);
568         }
569         put_pid(info->notify_owner);
570         info->notify_owner = NULL;
571 }
572
573 static int mq_attr_ok(struct mq_attr *attr)
574 {
575         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
576                 return 0;
577         if (capable(CAP_SYS_RESOURCE)) {
578                 if (attr->mq_maxmsg > HARD_MSGMAX)
579                         return 0;
580         } else {
581                 if (attr->mq_maxmsg > msg_max ||
582                                 attr->mq_msgsize > msgsize_max)
583                         return 0;
584         }
585         /* check for overflow */
586         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
587                 return 0;
588         if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
589             (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
590             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
591                 return 0;
592         return 1;
593 }
594
595 /*
596  * Invoked when creating a new queue via sys_mq_open
597  */
598 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
599                         int oflag, mode_t mode, struct mq_attr __user *u_attr)
600 {
601         struct mq_attr attr;
602         int ret;
603
604         if (u_attr) {
605                 ret = -EFAULT;
606                 if (copy_from_user(&attr, u_attr, sizeof(attr)))
607                         goto out;
608                 ret = -EINVAL;
609                 if (!mq_attr_ok(&attr))
610                         goto out;
611                 /* store for use during create */
612                 dentry->d_fsdata = &attr;
613         }
614
615         mode &= ~current->fs->umask;
616         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
617         dentry->d_fsdata = NULL;
618         if (ret)
619                 goto out;
620
621         return dentry_open(dentry, mqueue_mnt, oflag);
622
623 out:
624         dput(dentry);
625         mntput(mqueue_mnt);
626         return ERR_PTR(ret);
627 }
628
629 /* Opens existing queue */
630 static struct file *do_open(struct dentry *dentry, int oflag)
631 {
632 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
633                                         MAY_READ | MAY_WRITE };
634
635         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
636                 dput(dentry);
637                 mntput(mqueue_mnt);
638                 return ERR_PTR(-EINVAL);
639         }
640
641         if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
642                 dput(dentry);
643                 mntput(mqueue_mnt);
644                 return ERR_PTR(-EACCES);
645         }
646
647         return dentry_open(dentry, mqueue_mnt, oflag);
648 }
649
650 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
651                                 struct mq_attr __user *u_attr)
652 {
653         struct dentry *dentry;
654         struct file *filp;
655         char *name;
656         int fd, error;
657
658         error = audit_mq_open(oflag, mode, u_attr);
659         if (error != 0)
660                 return error;
661
662         if (IS_ERR(name = getname(u_name)))
663                 return PTR_ERR(name);
664
665         fd = get_unused_fd();
666         if (fd < 0)
667                 goto out_putname;
668
669         mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
670         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
671         if (IS_ERR(dentry)) {
672                 error = PTR_ERR(dentry);
673                 goto out_err;
674         }
675         mntget(mqueue_mnt);
676
677         if (oflag & O_CREAT) {
678                 if (dentry->d_inode) {  /* entry already exists */
679                         audit_inode(name, dentry->d_inode);
680                         error = -EEXIST;
681                         if (oflag & O_EXCL)
682                                 goto out;
683                         filp = do_open(dentry, oflag);
684                 } else {
685                         filp = do_create(mqueue_mnt->mnt_root, dentry,
686                                                 oflag, mode, u_attr);
687                 }
688         } else {
689                 error = -ENOENT;
690                 if (!dentry->d_inode)
691                         goto out;
692                 audit_inode(name, dentry->d_inode);
693                 filp = do_open(dentry, oflag);
694         }
695
696         if (IS_ERR(filp)) {
697                 error = PTR_ERR(filp);
698                 goto out_putfd;
699         }
700
701         set_close_on_exec(fd, 1);
702         fd_install(fd, filp);
703         goto out_upsem;
704
705 out:
706         dput(dentry);
707         mntput(mqueue_mnt);
708 out_putfd:
709         put_unused_fd(fd);
710 out_err:
711         fd = error;
712 out_upsem:
713         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
714 out_putname:
715         putname(name);
716         return fd;
717 }
718
719 asmlinkage long sys_mq_unlink(const char __user *u_name)
720 {
721         int err;
722         char *name;
723         struct dentry *dentry;
724         struct inode *inode = NULL;
725
726         name = getname(u_name);
727         if (IS_ERR(name))
728                 return PTR_ERR(name);
729
730         mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
731                         I_MUTEX_PARENT);
732         dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
733         if (IS_ERR(dentry)) {
734                 err = PTR_ERR(dentry);
735                 goto out_unlock;
736         }
737
738         if (!dentry->d_inode) {
739                 err = -ENOENT;
740                 goto out_err;
741         }
742
743         inode = dentry->d_inode;
744         if (inode)
745                 atomic_inc(&inode->i_count);
746
747         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
748 out_err:
749         dput(dentry);
750
751 out_unlock:
752         mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
753         putname(name);
754         if (inode)
755                 iput(inode);
756
757         return err;
758 }
759
760 /* Pipelined send and receive functions.
761  *
762  * If a receiver finds no waiting message, then it registers itself in the
763  * list of waiting receivers. A sender checks that list before adding the new
764  * message into the message array. If there is a waiting receiver, then it
765  * bypasses the message array and directly hands the message over to the
766  * receiver.
767  * The receiver accepts the message and returns without grabbing the queue
768  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
769  * are necessary. The same algorithm is used for sysv semaphores, see
770  * ipc/sem.c for more details.
771  *
772  * The same algorithm is used for senders.
773  */
774
775 /* pipelined_send() - send a message directly to the task waiting in
776  * sys_mq_timedreceive() (without inserting message into a queue).
777  */
778 static inline void pipelined_send(struct mqueue_inode_info *info,
779                                   struct msg_msg *message,
780                                   struct ext_wait_queue *receiver)
781 {
782         receiver->msg = message;
783         list_del(&receiver->list);
784         receiver->state = STATE_PENDING;
785         wake_up_process(receiver->task);
786         smp_wmb();
787         receiver->state = STATE_READY;
788 }
789
790 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
791  * gets its message and put to the queue (we have one free place for sure). */
792 static inline void pipelined_receive(struct mqueue_inode_info *info)
793 {
794         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
795
796         if (!sender) {
797                 /* for poll */
798                 wake_up_interruptible(&info->wait_q);
799                 return;
800         }
801         msg_insert(sender->msg, info);
802         list_del(&sender->list);
803         sender->state = STATE_PENDING;
804         wake_up_process(sender->task);
805         smp_wmb();
806         sender->state = STATE_READY;
807 }
808
809 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
810         size_t msg_len, unsigned int msg_prio,
811         const struct timespec __user *u_abs_timeout)
812 {
813         struct file *filp;
814         struct inode *inode;
815         struct ext_wait_queue wait;
816         struct ext_wait_queue *receiver;
817         struct msg_msg *msg_ptr;
818         struct mqueue_inode_info *info;
819         long timeout;
820         int ret;
821
822         ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
823         if (ret != 0)
824                 return ret;
825
826         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
827                 return -EINVAL;
828
829         timeout = prepare_timeout(u_abs_timeout);
830
831         ret = -EBADF;
832         filp = fget(mqdes);
833         if (unlikely(!filp))
834                 goto out;
835
836         inode = filp->f_path.dentry->d_inode;
837         if (unlikely(filp->f_op != &mqueue_file_operations))
838                 goto out_fput;
839         info = MQUEUE_I(inode);
840         audit_inode(NULL, 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_path.dentry->d_inode;
921         if (unlikely(filp->f_op != &mqueue_file_operations))
922                 goto out_fput;
923         info = MQUEUE_I(inode);
924         audit_inode(NULL, inode);
925
926         if (unlikely(!(filp->f_mode & FMODE_READ)))
927                 goto out_fput;
928
929         /* checks if buffer is big enough */
930         if (unlikely(msg_len < info->attr.mq_msgsize)) {
931                 ret = -EMSGSIZE;
932                 goto out_fput;
933         }
934
935         spin_lock(&info->lock);
936         if (info->attr.mq_curmsgs == 0) {
937                 if (filp->f_flags & O_NONBLOCK) {
938                         spin_unlock(&info->lock);
939                         ret = -EAGAIN;
940                         msg_ptr = NULL;
941                 } else if (unlikely(timeout < 0)) {
942                         spin_unlock(&info->lock);
943                         ret = timeout;
944                         msg_ptr = NULL;
945                 } else {
946                         wait.task = current;
947                         wait.state = STATE_NONE;
948                         ret = wq_sleep(info, RECV, timeout, &wait);
949                         msg_ptr = wait.msg;
950                 }
951         } else {
952                 msg_ptr = msg_get(info);
953
954                 inode->i_atime = inode->i_mtime = inode->i_ctime =
955                                 CURRENT_TIME;
956
957                 /* There is now free space in queue. */
958                 pipelined_receive(info);
959                 spin_unlock(&info->lock);
960                 ret = 0;
961         }
962         if (ret == 0) {
963                 ret = msg_ptr->m_ts;
964
965                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
966                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
967                         ret = -EFAULT;
968                 }
969                 free_msg(msg_ptr);
970         }
971 out_fput:
972         fput(filp);
973 out:
974         return ret;
975 }
976
977 /*
978  * Notes: the case when user wants us to deregister (with NULL as pointer)
979  * and he isn't currently owner of notification, will be silently discarded.
980  * It isn't explicitly defined in the POSIX.
981  */
982 asmlinkage long sys_mq_notify(mqd_t mqdes,
983                                 const struct sigevent __user *u_notification)
984 {
985         int ret;
986         struct file *filp;
987         struct sock *sock;
988         struct inode *inode;
989         struct sigevent notification;
990         struct mqueue_inode_info *info;
991         struct sk_buff *nc;
992
993         ret = audit_mq_notify(mqdes, u_notification);
994         if (ret != 0)
995                 return ret;
996
997         nc = NULL;
998         sock = NULL;
999         if (u_notification != NULL) {
1000                 if (copy_from_user(&notification, u_notification,
1001                                         sizeof(struct sigevent)))
1002                         return -EFAULT;
1003
1004                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1005                              notification.sigev_notify != SIGEV_SIGNAL &&
1006                              notification.sigev_notify != SIGEV_THREAD))
1007                         return -EINVAL;
1008                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1009                         !valid_signal(notification.sigev_signo)) {
1010                         return -EINVAL;
1011                 }
1012                 if (notification.sigev_notify == SIGEV_THREAD) {
1013                         /* create the notify skb */
1014                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1015                         ret = -ENOMEM;
1016                         if (!nc)
1017                                 goto out;
1018                         ret = -EFAULT;
1019                         if (copy_from_user(nc->data,
1020                                         notification.sigev_value.sival_ptr,
1021                                         NOTIFY_COOKIE_LEN)) {
1022                                 goto out;
1023                         }
1024
1025                         /* TODO: add a header? */
1026                         skb_put(nc, NOTIFY_COOKIE_LEN);
1027                         /* and attach it to the socket */
1028 retry:
1029                         filp = fget(notification.sigev_signo);
1030                         ret = -EBADF;
1031                         if (!filp)
1032                                 goto out;
1033                         sock = netlink_getsockbyfilp(filp);
1034                         fput(filp);
1035                         if (IS_ERR(sock)) {
1036                                 ret = PTR_ERR(sock);
1037                                 sock = NULL;
1038                                 goto out;
1039                         }
1040
1041                         ret = netlink_attachskb(sock, nc, 0,
1042                                         MAX_SCHEDULE_TIMEOUT, NULL);
1043                         if (ret == 1)
1044                                 goto retry;
1045                         if (ret) {
1046                                 sock = NULL;
1047                                 nc = NULL;
1048                                 goto out;
1049                         }
1050                 }
1051         }
1052
1053         ret = -EBADF;
1054         filp = fget(mqdes);
1055         if (!filp)
1056                 goto out;
1057
1058         inode = filp->f_path.dentry->d_inode;
1059         if (unlikely(filp->f_op != &mqueue_file_operations))
1060                 goto out_fput;
1061         info = MQUEUE_I(inode);
1062
1063         ret = 0;
1064         spin_lock(&info->lock);
1065         if (u_notification == NULL) {
1066                 if (info->notify_owner == task_tgid(current)) {
1067                         remove_notification(info);
1068                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1069                 }
1070         } else if (info->notify_owner != NULL) {
1071                 ret = -EBUSY;
1072         } else {
1073                 switch (notification.sigev_notify) {
1074                 case SIGEV_NONE:
1075                         info->notify.sigev_notify = SIGEV_NONE;
1076                         break;
1077                 case SIGEV_THREAD:
1078                         info->notify_sock = sock;
1079                         info->notify_cookie = nc;
1080                         sock = NULL;
1081                         nc = NULL;
1082                         info->notify.sigev_notify = SIGEV_THREAD;
1083                         break;
1084                 case SIGEV_SIGNAL:
1085                         info->notify.sigev_signo = notification.sigev_signo;
1086                         info->notify.sigev_value = notification.sigev_value;
1087                         info->notify.sigev_notify = SIGEV_SIGNAL;
1088                         break;
1089                 }
1090
1091                 info->notify_owner = get_pid(task_tgid(current));
1092                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1093         }
1094         spin_unlock(&info->lock);
1095 out_fput:
1096         fput(filp);
1097 out:
1098         if (sock) {
1099                 netlink_detachskb(sock, nc);
1100         } else if (nc) {
1101                 dev_kfree_skb(nc);
1102         }
1103         return ret;
1104 }
1105
1106 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1107                         const struct mq_attr __user *u_mqstat,
1108                         struct mq_attr __user *u_omqstat)
1109 {
1110         int ret;
1111         struct mq_attr mqstat, omqstat;
1112         struct file *filp;
1113         struct inode *inode;
1114         struct mqueue_inode_info *info;
1115
1116         if (u_mqstat != NULL) {
1117                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1118                         return -EFAULT;
1119                 if (mqstat.mq_flags & (~O_NONBLOCK))
1120                         return -EINVAL;
1121         }
1122
1123         ret = -EBADF;
1124         filp = fget(mqdes);
1125         if (!filp)
1126                 goto out;
1127
1128         inode = filp->f_path.dentry->d_inode;
1129         if (unlikely(filp->f_op != &mqueue_file_operations))
1130                 goto out_fput;
1131         info = MQUEUE_I(inode);
1132
1133         spin_lock(&info->lock);
1134
1135         omqstat = info->attr;
1136         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1137         if (u_mqstat) {
1138                 ret = audit_mq_getsetattr(mqdes, &mqstat);
1139                 if (ret != 0)
1140                         goto out;
1141                 if (mqstat.mq_flags & O_NONBLOCK)
1142                         filp->f_flags |= O_NONBLOCK;
1143                 else
1144                         filp->f_flags &= ~O_NONBLOCK;
1145
1146                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1147         }
1148
1149         spin_unlock(&info->lock);
1150
1151         ret = 0;
1152         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1153                                                 sizeof(struct mq_attr)))
1154                 ret = -EFAULT;
1155
1156 out_fput:
1157         fput(filp);
1158 out:
1159         return ret;
1160 }
1161
1162 static const struct inode_operations mqueue_dir_inode_operations = {
1163         .lookup = simple_lookup,
1164         .create = mqueue_create,
1165         .unlink = mqueue_unlink,
1166 };
1167
1168 static const struct file_operations mqueue_file_operations = {
1169         .flush = mqueue_flush_file,
1170         .poll = mqueue_poll_file,
1171         .read = mqueue_read_file,
1172 };
1173
1174 static struct super_operations mqueue_super_ops = {
1175         .alloc_inode = mqueue_alloc_inode,
1176         .destroy_inode = mqueue_destroy_inode,
1177         .statfs = simple_statfs,
1178         .delete_inode = mqueue_delete_inode,
1179         .drop_inode = generic_delete_inode,
1180 };
1181
1182 static struct file_system_type mqueue_fs_type = {
1183         .name = "mqueue",
1184         .get_sb = mqueue_get_sb,
1185         .kill_sb = kill_litter_super,
1186 };
1187
1188 static int msg_max_limit_min = DFLT_MSGMAX;
1189 static int msg_max_limit_max = HARD_MSGMAX;
1190
1191 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1192 static int msg_maxsize_limit_max = INT_MAX;
1193
1194 static ctl_table mq_sysctls[] = {
1195         {
1196                 .procname       = "queues_max",
1197                 .data           = &queues_max,
1198                 .maxlen         = sizeof(int),
1199                 .mode           = 0644,
1200                 .proc_handler   = &proc_dointvec,
1201         },
1202         {
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                 .procname       = "msgsize_max",
1213                 .data           = &msgsize_max,
1214                 .maxlen         = sizeof(int),
1215                 .mode           = 0644,
1216                 .proc_handler   = &proc_dointvec_minmax,
1217                 .extra1         = &msg_maxsize_limit_min,
1218                 .extra2         = &msg_maxsize_limit_max,
1219         },
1220         { .ctl_name = 0 }
1221 };
1222
1223 static ctl_table mq_sysctl_dir[] = {
1224         {
1225                 .procname       = "mqueue",
1226                 .mode           = 0555,
1227                 .child          = mq_sysctls,
1228         },
1229         { .ctl_name = 0 }
1230 };
1231
1232 static ctl_table mq_sysctl_root[] = {
1233         {
1234                 .ctl_name       = CTL_FS,
1235                 .procname       = "fs",
1236                 .mode           = 0555,
1237                 .child          = mq_sysctl_dir,
1238         },
1239         { .ctl_name = 0 }
1240 };
1241
1242 static int __init init_mqueue_fs(void)
1243 {
1244         int error;
1245
1246         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1247                                 sizeof(struct mqueue_inode_info), 0,
1248                                 SLAB_HWCACHE_ALIGN, init_once);
1249         if (mqueue_inode_cachep == NULL)
1250                 return -ENOMEM;
1251
1252         /* ignore failues - they are not fatal */
1253         mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1254
1255         error = register_filesystem(&mqueue_fs_type);
1256         if (error)
1257                 goto out_sysctl;
1258
1259         if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1260                 error = PTR_ERR(mqueue_mnt);
1261                 goto out_filesystem;
1262         }
1263
1264         /* internal initialization - not common for vfs */
1265         queues_count = 0;
1266         spin_lock_init(&mq_lock);
1267
1268         return 0;
1269
1270 out_filesystem:
1271         unregister_filesystem(&mqueue_fs_type);
1272 out_sysctl:
1273         if (mq_sysctl_table)
1274                 unregister_sysctl_table(mq_sysctl_table);
1275         kmem_cache_destroy(mqueue_inode_cachep);
1276         return error;
1277 }
1278
1279 __initcall(init_mqueue_fs);