mqueue: remove unneeded info->messages initialization
[linux-3.10.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 #include <linux/ipc_namespace.h>
35
36 #include <net/sock.h>
37 #include "util.h"
38
39 #define MQUEUE_MAGIC    0x19800202
40 #define DIRENT_SIZE     20
41 #define FILENT_SIZE     80
42
43 #define SEND            0
44 #define RECV            1
45
46 #define STATE_NONE      0
47 #define STATE_PENDING   1
48 #define STATE_READY     2
49
50 struct ext_wait_queue {         /* queue of sleeping tasks */
51         struct task_struct *task;
52         struct list_head list;
53         struct msg_msg *msg;    /* ptr of loaded message */
54         int state;              /* one of STATE_* values */
55 };
56
57 struct mqueue_inode_info {
58         spinlock_t lock;
59         struct inode vfs_inode;
60         wait_queue_head_t wait_q;
61
62         struct msg_msg **messages;
63         struct mq_attr attr;
64
65         struct sigevent notify;
66         struct pid* notify_owner;
67         struct user_struct *user;       /* user who created, for accounting */
68         struct sock *notify_sock;
69         struct sk_buff *notify_cookie;
70
71         /* for tasks waiting for free space and messages, respectively */
72         struct ext_wait_queue e_wait_q[2];
73
74         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
75 };
76
77 static const struct inode_operations mqueue_dir_inode_operations;
78 static const struct file_operations mqueue_file_operations;
79 static const struct super_operations mqueue_super_ops;
80 static void remove_notification(struct mqueue_inode_info *info);
81
82 static struct kmem_cache *mqueue_inode_cachep;
83
84 static struct ctl_table_header * mq_sysctl_table;
85
86 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
87 {
88         return container_of(inode, struct mqueue_inode_info, vfs_inode);
89 }
90
91 /*
92  * This routine should be called with the mq_lock held.
93  */
94 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
95 {
96         return get_ipc_ns(inode->i_sb->s_fs_info);
97 }
98
99 static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
100 {
101         struct ipc_namespace *ns;
102
103         spin_lock(&mq_lock);
104         ns = __get_ns_from_inode(inode);
105         spin_unlock(&mq_lock);
106         return ns;
107 }
108
109 static struct inode *mqueue_get_inode(struct super_block *sb,
110                 struct ipc_namespace *ipc_ns, int mode,
111                 struct mq_attr *attr)
112 {
113         struct user_struct *u = current_user();
114         struct inode *inode;
115
116         inode = new_inode(sb);
117         if (inode) {
118                 inode->i_mode = mode;
119                 inode->i_uid = current_fsuid();
120                 inode->i_gid = current_fsgid();
121                 inode->i_mtime = inode->i_ctime = inode->i_atime =
122                                 CURRENT_TIME;
123
124                 if (S_ISREG(mode)) {
125                         struct mqueue_inode_info *info;
126                         struct task_struct *p = current;
127                         unsigned long mq_bytes, mq_msg_tblsz;
128
129                         inode->i_fop = &mqueue_file_operations;
130                         inode->i_size = FILENT_SIZE;
131                         /* mqueue specific info */
132                         info = MQUEUE_I(inode);
133                         spin_lock_init(&info->lock);
134                         init_waitqueue_head(&info->wait_q);
135                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
136                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
137                         info->notify_owner = NULL;
138                         info->qsize = 0;
139                         info->user = NULL;      /* set when all is ok */
140                         memset(&info->attr, 0, sizeof(info->attr));
141                         info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
142                         info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
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                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
149                         if (!info->messages)
150                                 goto out_inode;
151
152                         mq_bytes = (mq_msg_tblsz +
153                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
154
155                         spin_lock(&mq_lock);
156                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
157                             u->mq_bytes + mq_bytes >
158                             p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
159                                 spin_unlock(&mq_lock);
160                                 kfree(info->messages);
161                                 goto out_inode;
162                         }
163                         u->mq_bytes += mq_bytes;
164                         spin_unlock(&mq_lock);
165
166                         /* all is ok */
167                         info->user = get_uid(u);
168                 } else if (S_ISDIR(mode)) {
169                         inc_nlink(inode);
170                         /* Some things misbehave if size == 0 on a directory */
171                         inode->i_size = 2 * DIRENT_SIZE;
172                         inode->i_op = &mqueue_dir_inode_operations;
173                         inode->i_fop = &simple_dir_operations;
174                 }
175         }
176         return inode;
177 out_inode:
178         make_bad_inode(inode);
179         iput(inode);
180         return NULL;
181 }
182
183 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
184 {
185         struct inode *inode;
186         struct ipc_namespace *ns = data;
187         int error = 0;
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, ns, S_IFDIR | S_ISVTX | S_IRWXUGO,
195                                 NULL);
196         if (!inode) {
197                 error = -ENOMEM;
198                 goto out;
199         }
200
201         sb->s_root = d_alloc_root(inode);
202         if (!sb->s_root) {
203                 iput(inode);
204                 error = -ENOMEM;
205         }
206
207 out:
208         return error;
209 }
210
211 static int mqueue_get_sb(struct file_system_type *fs_type,
212                          int flags, const char *dev_name,
213                          void *data, struct vfsmount *mnt)
214 {
215         if (!(flags & MS_KERNMOUNT))
216                 data = current->nsproxy->ipc_ns;
217         return get_sb_ns(fs_type, flags, data, mqueue_fill_super, mnt);
218 }
219
220 static void init_once(void *foo)
221 {
222         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
223
224         inode_init_once(&p->vfs_inode);
225 }
226
227 static struct inode *mqueue_alloc_inode(struct super_block *sb)
228 {
229         struct mqueue_inode_info *ei;
230
231         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
232         if (!ei)
233                 return NULL;
234         return &ei->vfs_inode;
235 }
236
237 static void mqueue_destroy_inode(struct inode *inode)
238 {
239         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
240 }
241
242 static void mqueue_delete_inode(struct inode *inode)
243 {
244         struct mqueue_inode_info *info;
245         struct user_struct *user;
246         unsigned long mq_bytes;
247         int i;
248         struct ipc_namespace *ipc_ns;
249
250         if (S_ISDIR(inode->i_mode)) {
251                 clear_inode(inode);
252                 return;
253         }
254         ipc_ns = get_ns_from_inode(inode);
255         info = MQUEUE_I(inode);
256         spin_lock(&info->lock);
257         for (i = 0; i < info->attr.mq_curmsgs; i++)
258                 free_msg(info->messages[i]);
259         kfree(info->messages);
260         spin_unlock(&info->lock);
261
262         clear_inode(inode);
263
264         mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
265                    (info->attr.mq_maxmsg * info->attr.mq_msgsize));
266         user = info->user;
267         if (user) {
268                 spin_lock(&mq_lock);
269                 user->mq_bytes -= mq_bytes;
270                 /*
271                  * get_ns_from_inode() ensures that the
272                  * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
273                  * to which we now hold a reference, or it is NULL.
274                  * We can't put it here under mq_lock, though.
275                  */
276                 if (ipc_ns)
277                         ipc_ns->mq_queues_count--;
278                 spin_unlock(&mq_lock);
279                 free_uid(user);
280         }
281         if (ipc_ns)
282                 put_ipc_ns(ipc_ns);
283 }
284
285 static int mqueue_create(struct inode *dir, struct dentry *dentry,
286                                 int mode, struct nameidata *nd)
287 {
288         struct inode *inode;
289         struct mq_attr *attr = dentry->d_fsdata;
290         int error;
291         struct ipc_namespace *ipc_ns;
292
293         spin_lock(&mq_lock);
294         ipc_ns = __get_ns_from_inode(dir);
295         if (!ipc_ns) {
296                 error = -EACCES;
297                 goto out_unlock;
298         }
299         if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
300                         !capable(CAP_SYS_RESOURCE)) {
301                 error = -ENOSPC;
302                 goto out_unlock;
303         }
304         ipc_ns->mq_queues_count++;
305         spin_unlock(&mq_lock);
306
307         inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
308         if (!inode) {
309                 error = -ENOMEM;
310                 spin_lock(&mq_lock);
311                 ipc_ns->mq_queues_count--;
312                 goto out_unlock;
313         }
314
315         put_ipc_ns(ipc_ns);
316         dir->i_size += DIRENT_SIZE;
317         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
318
319         d_instantiate(dentry, inode);
320         dget(dentry);
321         return 0;
322 out_unlock:
323         spin_unlock(&mq_lock);
324         if (ipc_ns)
325                 put_ipc_ns(ipc_ns);
326         return error;
327 }
328
329 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
330 {
331         struct inode *inode = dentry->d_inode;
332
333         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
334         dir->i_size -= DIRENT_SIZE;
335         drop_nlink(inode);
336         dput(dentry);
337         return 0;
338 }
339
340 /*
341 *       This is routine for system read from queue file.
342 *       To avoid mess with doing here some sort of mq_receive we allow
343 *       to read only queue size & notification info (the only values
344 *       that are interesting from user point of view and aren't accessible
345 *       through std routines)
346 */
347 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
348                                 size_t count, loff_t *off)
349 {
350         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
351         char buffer[FILENT_SIZE];
352         ssize_t ret;
353
354         spin_lock(&info->lock);
355         snprintf(buffer, sizeof(buffer),
356                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
357                         info->qsize,
358                         info->notify_owner ? info->notify.sigev_notify : 0,
359                         (info->notify_owner &&
360                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
361                                 info->notify.sigev_signo : 0,
362                         pid_vnr(info->notify_owner));
363         spin_unlock(&info->lock);
364         buffer[sizeof(buffer)-1] = '\0';
365
366         ret = simple_read_from_buffer(u_data, count, off, buffer,
367                                 strlen(buffer));
368         if (ret <= 0)
369                 return ret;
370
371         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
372         return ret;
373 }
374
375 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
376 {
377         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
378
379         spin_lock(&info->lock);
380         if (task_tgid(current) == info->notify_owner)
381                 remove_notification(info);
382
383         spin_unlock(&info->lock);
384         return 0;
385 }
386
387 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
388 {
389         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
390         int retval = 0;
391
392         poll_wait(filp, &info->wait_q, poll_tab);
393
394         spin_lock(&info->lock);
395         if (info->attr.mq_curmsgs)
396                 retval = POLLIN | POLLRDNORM;
397
398         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
399                 retval |= POLLOUT | POLLWRNORM;
400         spin_unlock(&info->lock);
401
402         return retval;
403 }
404
405 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
406 static void wq_add(struct mqueue_inode_info *info, int sr,
407                         struct ext_wait_queue *ewp)
408 {
409         struct ext_wait_queue *walk;
410
411         ewp->task = current;
412
413         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
414                 if (walk->task->static_prio <= current->static_prio) {
415                         list_add_tail(&ewp->list, &walk->list);
416                         return;
417                 }
418         }
419         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
420 }
421
422 /*
423  * Puts current task to sleep. Caller must hold queue lock. After return
424  * lock isn't held.
425  * sr: SEND or RECV
426  */
427 static int wq_sleep(struct mqueue_inode_info *info, int sr,
428                         long timeout, struct ext_wait_queue *ewp)
429 {
430         int retval;
431         signed long time;
432
433         wq_add(info, sr, ewp);
434
435         for (;;) {
436                 set_current_state(TASK_INTERRUPTIBLE);
437
438                 spin_unlock(&info->lock);
439                 time = schedule_timeout(timeout);
440
441                 while (ewp->state == STATE_PENDING)
442                         cpu_relax();
443
444                 if (ewp->state == STATE_READY) {
445                         retval = 0;
446                         goto out;
447                 }
448                 spin_lock(&info->lock);
449                 if (ewp->state == STATE_READY) {
450                         retval = 0;
451                         goto out_unlock;
452                 }
453                 if (signal_pending(current)) {
454                         retval = -ERESTARTSYS;
455                         break;
456                 }
457                 if (time == 0) {
458                         retval = -ETIMEDOUT;
459                         break;
460                 }
461         }
462         list_del(&ewp->list);
463 out_unlock:
464         spin_unlock(&info->lock);
465 out:
466         return retval;
467 }
468
469 /*
470  * Returns waiting task that should be serviced first or NULL if none exists
471  */
472 static struct ext_wait_queue *wq_get_first_waiter(
473                 struct mqueue_inode_info *info, int sr)
474 {
475         struct list_head *ptr;
476
477         ptr = info->e_wait_q[sr].list.prev;
478         if (ptr == &info->e_wait_q[sr].list)
479                 return NULL;
480         return list_entry(ptr, struct ext_wait_queue, list);
481 }
482
483 /* Auxiliary functions to manipulate messages' list */
484 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
485 {
486         int k;
487
488         k = info->attr.mq_curmsgs - 1;
489         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
490                 info->messages[k + 1] = info->messages[k];
491                 k--;
492         }
493         info->attr.mq_curmsgs++;
494         info->qsize += ptr->m_ts;
495         info->messages[k + 1] = ptr;
496 }
497
498 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
499 {
500         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
501         return info->messages[info->attr.mq_curmsgs];
502 }
503
504 static inline void set_cookie(struct sk_buff *skb, char code)
505 {
506         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
507 }
508
509 /*
510  * The next function is only to split too long sys_mq_timedsend
511  */
512 static void __do_notify(struct mqueue_inode_info *info)
513 {
514         /* notification
515          * invoked when there is registered process and there isn't process
516          * waiting synchronously for message AND state of queue changed from
517          * empty to not empty. Here we are sure that no one is waiting
518          * synchronously. */
519         if (info->notify_owner &&
520             info->attr.mq_curmsgs == 1) {
521                 struct siginfo sig_i;
522                 switch (info->notify.sigev_notify) {
523                 case SIGEV_NONE:
524                         break;
525                 case SIGEV_SIGNAL:
526                         /* sends signal */
527
528                         sig_i.si_signo = info->notify.sigev_signo;
529                         sig_i.si_errno = 0;
530                         sig_i.si_code = SI_MESGQ;
531                         sig_i.si_value = info->notify.sigev_value;
532                         sig_i.si_pid = task_tgid_nr_ns(current,
533                                                 ns_of_pid(info->notify_owner));
534                         sig_i.si_uid = current_uid();
535
536                         kill_pid_info(info->notify.sigev_signo,
537                                       &sig_i, info->notify_owner);
538                         break;
539                 case SIGEV_THREAD:
540                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
541                         netlink_sendskb(info->notify_sock, info->notify_cookie);
542                         break;
543                 }
544                 /* after notification unregisters process */
545                 put_pid(info->notify_owner);
546                 info->notify_owner = NULL;
547         }
548         wake_up(&info->wait_q);
549 }
550
551 static long prepare_timeout(struct timespec *p)
552 {
553         struct timespec nowts;
554         long timeout;
555
556         if (p) {
557                 if (unlikely(p->tv_nsec < 0 || p->tv_sec < 0
558                         || p->tv_nsec >= NSEC_PER_SEC))
559                         return -EINVAL;
560                 nowts = CURRENT_TIME;
561                 /* first subtract as jiffies can't be too big */
562                 p->tv_sec -= nowts.tv_sec;
563                 if (p->tv_nsec < nowts.tv_nsec) {
564                         p->tv_nsec += NSEC_PER_SEC;
565                         p->tv_sec--;
566                 }
567                 p->tv_nsec -= nowts.tv_nsec;
568                 if (p->tv_sec < 0)
569                         return 0;
570
571                 timeout = timespec_to_jiffies(p) + 1;
572         } else
573                 return MAX_SCHEDULE_TIMEOUT;
574
575         return timeout;
576 }
577
578 static void remove_notification(struct mqueue_inode_info *info)
579 {
580         if (info->notify_owner != NULL &&
581             info->notify.sigev_notify == SIGEV_THREAD) {
582                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
583                 netlink_sendskb(info->notify_sock, info->notify_cookie);
584         }
585         put_pid(info->notify_owner);
586         info->notify_owner = NULL;
587 }
588
589 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
590 {
591         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
592                 return 0;
593         if (capable(CAP_SYS_RESOURCE)) {
594                 if (attr->mq_maxmsg > HARD_MSGMAX)
595                         return 0;
596         } else {
597                 if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
598                                 attr->mq_msgsize > ipc_ns->mq_msgsize_max)
599                         return 0;
600         }
601         /* check for overflow */
602         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
603                 return 0;
604         if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
605             (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
606             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
607                 return 0;
608         return 1;
609 }
610
611 /*
612  * Invoked when creating a new queue via sys_mq_open
613  */
614 static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
615                         struct dentry *dentry, int oflag, mode_t mode,
616                         struct mq_attr *attr)
617 {
618         const struct cred *cred = current_cred();
619         struct file *result;
620         int ret;
621
622         if (attr) {
623                 ret = -EINVAL;
624                 if (!mq_attr_ok(ipc_ns, attr))
625                         goto out;
626                 /* store for use during create */
627                 dentry->d_fsdata = attr;
628         }
629
630         mode &= ~current_umask();
631         ret = mnt_want_write(ipc_ns->mq_mnt);
632         if (ret)
633                 goto out;
634         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
635         dentry->d_fsdata = NULL;
636         if (ret)
637                 goto out_drop_write;
638
639         result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
640         /*
641          * dentry_open() took a persistent mnt_want_write(),
642          * so we can now drop this one.
643          */
644         mnt_drop_write(ipc_ns->mq_mnt);
645         return result;
646
647 out_drop_write:
648         mnt_drop_write(ipc_ns->mq_mnt);
649 out:
650         dput(dentry);
651         mntput(ipc_ns->mq_mnt);
652         return ERR_PTR(ret);
653 }
654
655 /* Opens existing queue */
656 static struct file *do_open(struct ipc_namespace *ipc_ns,
657                                 struct dentry *dentry, int oflag)
658 {
659         const struct cred *cred = current_cred();
660
661         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
662                                                   MAY_READ | MAY_WRITE };
663
664         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
665                 dput(dentry);
666                 mntput(ipc_ns->mq_mnt);
667                 return ERR_PTR(-EINVAL);
668         }
669
670         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
671                 dput(dentry);
672                 mntput(ipc_ns->mq_mnt);
673                 return ERR_PTR(-EACCES);
674         }
675
676         return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
677 }
678
679 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
680                 struct mq_attr __user *, u_attr)
681 {
682         struct dentry *dentry;
683         struct file *filp;
684         char *name;
685         struct mq_attr attr;
686         int fd, error;
687         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
688
689         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
690                 return -EFAULT;
691
692         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
693
694         if (IS_ERR(name = getname(u_name)))
695                 return PTR_ERR(name);
696
697         fd = get_unused_fd_flags(O_CLOEXEC);
698         if (fd < 0)
699                 goto out_putname;
700
701         mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
702         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
703         if (IS_ERR(dentry)) {
704                 error = PTR_ERR(dentry);
705                 goto out_putfd;
706         }
707         mntget(ipc_ns->mq_mnt);
708
709         if (oflag & O_CREAT) {
710                 if (dentry->d_inode) {  /* entry already exists */
711                         audit_inode(name, dentry);
712                         error = -EEXIST;
713                         if (oflag & O_EXCL)
714                                 goto out;
715                         filp = do_open(ipc_ns, dentry, oflag);
716                 } else {
717                         filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
718                                                 dentry, oflag, mode,
719                                                 u_attr ? &attr : NULL);
720                 }
721         } else {
722                 error = -ENOENT;
723                 if (!dentry->d_inode)
724                         goto out;
725                 audit_inode(name, dentry);
726                 filp = do_open(ipc_ns, dentry, oflag);
727         }
728
729         if (IS_ERR(filp)) {
730                 error = PTR_ERR(filp);
731                 goto out_putfd;
732         }
733
734         fd_install(fd, filp);
735         goto out_upsem;
736
737 out:
738         dput(dentry);
739         mntput(ipc_ns->mq_mnt);
740 out_putfd:
741         put_unused_fd(fd);
742         fd = error;
743 out_upsem:
744         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
745 out_putname:
746         putname(name);
747         return fd;
748 }
749
750 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
751 {
752         int err;
753         char *name;
754         struct dentry *dentry;
755         struct inode *inode = NULL;
756         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
757
758         name = getname(u_name);
759         if (IS_ERR(name))
760                 return PTR_ERR(name);
761
762         mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
763                         I_MUTEX_PARENT);
764         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
765         if (IS_ERR(dentry)) {
766                 err = PTR_ERR(dentry);
767                 goto out_unlock;
768         }
769
770         if (!dentry->d_inode) {
771                 err = -ENOENT;
772                 goto out_err;
773         }
774
775         inode = dentry->d_inode;
776         if (inode)
777                 atomic_inc(&inode->i_count);
778         err = mnt_want_write(ipc_ns->mq_mnt);
779         if (err)
780                 goto out_err;
781         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
782         mnt_drop_write(ipc_ns->mq_mnt);
783 out_err:
784         dput(dentry);
785
786 out_unlock:
787         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
788         putname(name);
789         if (inode)
790                 iput(inode);
791
792         return err;
793 }
794
795 /* Pipelined send and receive functions.
796  *
797  * If a receiver finds no waiting message, then it registers itself in the
798  * list of waiting receivers. A sender checks that list before adding the new
799  * message into the message array. If there is a waiting receiver, then it
800  * bypasses the message array and directly hands the message over to the
801  * receiver.
802  * The receiver accepts the message and returns without grabbing the queue
803  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
804  * are necessary. The same algorithm is used for sysv semaphores, see
805  * ipc/sem.c for more details.
806  *
807  * The same algorithm is used for senders.
808  */
809
810 /* pipelined_send() - send a message directly to the task waiting in
811  * sys_mq_timedreceive() (without inserting message into a queue).
812  */
813 static inline void pipelined_send(struct mqueue_inode_info *info,
814                                   struct msg_msg *message,
815                                   struct ext_wait_queue *receiver)
816 {
817         receiver->msg = message;
818         list_del(&receiver->list);
819         receiver->state = STATE_PENDING;
820         wake_up_process(receiver->task);
821         smp_wmb();
822         receiver->state = STATE_READY;
823 }
824
825 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
826  * gets its message and put to the queue (we have one free place for sure). */
827 static inline void pipelined_receive(struct mqueue_inode_info *info)
828 {
829         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
830
831         if (!sender) {
832                 /* for poll */
833                 wake_up_interruptible(&info->wait_q);
834                 return;
835         }
836         msg_insert(sender->msg, info);
837         list_del(&sender->list);
838         sender->state = STATE_PENDING;
839         wake_up_process(sender->task);
840         smp_wmb();
841         sender->state = STATE_READY;
842 }
843
844 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
845                 size_t, msg_len, unsigned int, msg_prio,
846                 const struct timespec __user *, u_abs_timeout)
847 {
848         struct file *filp;
849         struct inode *inode;
850         struct ext_wait_queue wait;
851         struct ext_wait_queue *receiver;
852         struct msg_msg *msg_ptr;
853         struct mqueue_inode_info *info;
854         struct timespec ts, *p = NULL;
855         long timeout;
856         int ret;
857
858         if (u_abs_timeout) {
859                 if (copy_from_user(&ts, u_abs_timeout, 
860                                         sizeof(struct timespec)))
861                         return -EFAULT;
862                 p = &ts;
863         }
864
865         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
866                 return -EINVAL;
867
868         audit_mq_sendrecv(mqdes, msg_len, msg_prio, p);
869         timeout = prepare_timeout(p);
870
871         ret = -EBADF;
872         filp = fget(mqdes);
873         if (unlikely(!filp))
874                 goto out;
875
876         inode = filp->f_path.dentry->d_inode;
877         if (unlikely(filp->f_op != &mqueue_file_operations))
878                 goto out_fput;
879         info = MQUEUE_I(inode);
880         audit_inode(NULL, filp->f_path.dentry);
881
882         if (unlikely(!(filp->f_mode & FMODE_WRITE)))
883                 goto out_fput;
884
885         if (unlikely(msg_len > info->attr.mq_msgsize)) {
886                 ret = -EMSGSIZE;
887                 goto out_fput;
888         }
889
890         /* First try to allocate memory, before doing anything with
891          * existing queues. */
892         msg_ptr = load_msg(u_msg_ptr, msg_len);
893         if (IS_ERR(msg_ptr)) {
894                 ret = PTR_ERR(msg_ptr);
895                 goto out_fput;
896         }
897         msg_ptr->m_ts = msg_len;
898         msg_ptr->m_type = msg_prio;
899
900         spin_lock(&info->lock);
901
902         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
903                 if (filp->f_flags & O_NONBLOCK) {
904                         spin_unlock(&info->lock);
905                         ret = -EAGAIN;
906                 } else if (unlikely(timeout < 0)) {
907                         spin_unlock(&info->lock);
908                         ret = timeout;
909                 } else {
910                         wait.task = current;
911                         wait.msg = (void *) msg_ptr;
912                         wait.state = STATE_NONE;
913                         ret = wq_sleep(info, SEND, timeout, &wait);
914                 }
915                 if (ret < 0)
916                         free_msg(msg_ptr);
917         } else {
918                 receiver = wq_get_first_waiter(info, RECV);
919                 if (receiver) {
920                         pipelined_send(info, msg_ptr, receiver);
921                 } else {
922                         /* adds message to the queue */
923                         msg_insert(msg_ptr, info);
924                         __do_notify(info);
925                 }
926                 inode->i_atime = inode->i_mtime = inode->i_ctime =
927                                 CURRENT_TIME;
928                 spin_unlock(&info->lock);
929                 ret = 0;
930         }
931 out_fput:
932         fput(filp);
933 out:
934         return ret;
935 }
936
937 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
938                 size_t, msg_len, unsigned int __user *, u_msg_prio,
939                 const struct timespec __user *, u_abs_timeout)
940 {
941         long timeout;
942         ssize_t ret;
943         struct msg_msg *msg_ptr;
944         struct file *filp;
945         struct inode *inode;
946         struct mqueue_inode_info *info;
947         struct ext_wait_queue wait;
948         struct timespec ts, *p = NULL;
949
950         if (u_abs_timeout) {
951                 if (copy_from_user(&ts, u_abs_timeout, 
952                                         sizeof(struct timespec)))
953                         return -EFAULT;
954                 p = &ts;
955         }
956
957         audit_mq_sendrecv(mqdes, msg_len, 0, p);
958         timeout = prepare_timeout(p);
959
960         ret = -EBADF;
961         filp = fget(mqdes);
962         if (unlikely(!filp))
963                 goto out;
964
965         inode = filp->f_path.dentry->d_inode;
966         if (unlikely(filp->f_op != &mqueue_file_operations))
967                 goto out_fput;
968         info = MQUEUE_I(inode);
969         audit_inode(NULL, filp->f_path.dentry);
970
971         if (unlikely(!(filp->f_mode & FMODE_READ)))
972                 goto out_fput;
973
974         /* checks if buffer is big enough */
975         if (unlikely(msg_len < info->attr.mq_msgsize)) {
976                 ret = -EMSGSIZE;
977                 goto out_fput;
978         }
979
980         spin_lock(&info->lock);
981         if (info->attr.mq_curmsgs == 0) {
982                 if (filp->f_flags & O_NONBLOCK) {
983                         spin_unlock(&info->lock);
984                         ret = -EAGAIN;
985                         msg_ptr = NULL;
986                 } else if (unlikely(timeout < 0)) {
987                         spin_unlock(&info->lock);
988                         ret = timeout;
989                         msg_ptr = NULL;
990                 } else {
991                         wait.task = current;
992                         wait.state = STATE_NONE;
993                         ret = wq_sleep(info, RECV, timeout, &wait);
994                         msg_ptr = wait.msg;
995                 }
996         } else {
997                 msg_ptr = msg_get(info);
998
999                 inode->i_atime = inode->i_mtime = inode->i_ctime =
1000                                 CURRENT_TIME;
1001
1002                 /* There is now free space in queue. */
1003                 pipelined_receive(info);
1004                 spin_unlock(&info->lock);
1005                 ret = 0;
1006         }
1007         if (ret == 0) {
1008                 ret = msg_ptr->m_ts;
1009
1010                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1011                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1012                         ret = -EFAULT;
1013                 }
1014                 free_msg(msg_ptr);
1015         }
1016 out_fput:
1017         fput(filp);
1018 out:
1019         return ret;
1020 }
1021
1022 /*
1023  * Notes: the case when user wants us to deregister (with NULL as pointer)
1024  * and he isn't currently owner of notification, will be silently discarded.
1025  * It isn't explicitly defined in the POSIX.
1026  */
1027 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1028                 const struct sigevent __user *, u_notification)
1029 {
1030         int ret;
1031         struct file *filp;
1032         struct sock *sock;
1033         struct inode *inode;
1034         struct sigevent notification;
1035         struct mqueue_inode_info *info;
1036         struct sk_buff *nc;
1037
1038         if (u_notification) {
1039                 if (copy_from_user(&notification, u_notification,
1040                                         sizeof(struct sigevent)))
1041                         return -EFAULT;
1042         }
1043
1044         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1045
1046         nc = NULL;
1047         sock = NULL;
1048         if (u_notification != NULL) {
1049                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1050                              notification.sigev_notify != SIGEV_SIGNAL &&
1051                              notification.sigev_notify != SIGEV_THREAD))
1052                         return -EINVAL;
1053                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1054                         !valid_signal(notification.sigev_signo)) {
1055                         return -EINVAL;
1056                 }
1057                 if (notification.sigev_notify == SIGEV_THREAD) {
1058                         long timeo;
1059
1060                         /* create the notify skb */
1061                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1062                         ret = -ENOMEM;
1063                         if (!nc)
1064                                 goto out;
1065                         ret = -EFAULT;
1066                         if (copy_from_user(nc->data,
1067                                         notification.sigev_value.sival_ptr,
1068                                         NOTIFY_COOKIE_LEN)) {
1069                                 goto out;
1070                         }
1071
1072                         /* TODO: add a header? */
1073                         skb_put(nc, NOTIFY_COOKIE_LEN);
1074                         /* and attach it to the socket */
1075 retry:
1076                         filp = fget(notification.sigev_signo);
1077                         ret = -EBADF;
1078                         if (!filp)
1079                                 goto out;
1080                         sock = netlink_getsockbyfilp(filp);
1081                         fput(filp);
1082                         if (IS_ERR(sock)) {
1083                                 ret = PTR_ERR(sock);
1084                                 sock = NULL;
1085                                 goto out;
1086                         }
1087
1088                         timeo = MAX_SCHEDULE_TIMEOUT;
1089                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1090                         if (ret == 1)
1091                                 goto retry;
1092                         if (ret) {
1093                                 sock = NULL;
1094                                 nc = NULL;
1095                                 goto out;
1096                         }
1097                 }
1098         }
1099
1100         ret = -EBADF;
1101         filp = fget(mqdes);
1102         if (!filp)
1103                 goto out;
1104
1105         inode = filp->f_path.dentry->d_inode;
1106         if (unlikely(filp->f_op != &mqueue_file_operations))
1107                 goto out_fput;
1108         info = MQUEUE_I(inode);
1109
1110         ret = 0;
1111         spin_lock(&info->lock);
1112         if (u_notification == NULL) {
1113                 if (info->notify_owner == task_tgid(current)) {
1114                         remove_notification(info);
1115                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1116                 }
1117         } else if (info->notify_owner != NULL) {
1118                 ret = -EBUSY;
1119         } else {
1120                 switch (notification.sigev_notify) {
1121                 case SIGEV_NONE:
1122                         info->notify.sigev_notify = SIGEV_NONE;
1123                         break;
1124                 case SIGEV_THREAD:
1125                         info->notify_sock = sock;
1126                         info->notify_cookie = nc;
1127                         sock = NULL;
1128                         nc = NULL;
1129                         info->notify.sigev_notify = SIGEV_THREAD;
1130                         break;
1131                 case SIGEV_SIGNAL:
1132                         info->notify.sigev_signo = notification.sigev_signo;
1133                         info->notify.sigev_value = notification.sigev_value;
1134                         info->notify.sigev_notify = SIGEV_SIGNAL;
1135                         break;
1136                 }
1137
1138                 info->notify_owner = get_pid(task_tgid(current));
1139                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1140         }
1141         spin_unlock(&info->lock);
1142 out_fput:
1143         fput(filp);
1144 out:
1145         if (sock) {
1146                 netlink_detachskb(sock, nc);
1147         } else if (nc) {
1148                 dev_kfree_skb(nc);
1149         }
1150         return ret;
1151 }
1152
1153 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1154                 const struct mq_attr __user *, u_mqstat,
1155                 struct mq_attr __user *, u_omqstat)
1156 {
1157         int ret;
1158         struct mq_attr mqstat, omqstat;
1159         struct file *filp;
1160         struct inode *inode;
1161         struct mqueue_inode_info *info;
1162
1163         if (u_mqstat != NULL) {
1164                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1165                         return -EFAULT;
1166                 if (mqstat.mq_flags & (~O_NONBLOCK))
1167                         return -EINVAL;
1168         }
1169
1170         ret = -EBADF;
1171         filp = fget(mqdes);
1172         if (!filp)
1173                 goto out;
1174
1175         inode = filp->f_path.dentry->d_inode;
1176         if (unlikely(filp->f_op != &mqueue_file_operations))
1177                 goto out_fput;
1178         info = MQUEUE_I(inode);
1179
1180         spin_lock(&info->lock);
1181
1182         omqstat = info->attr;
1183         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1184         if (u_mqstat) {
1185                 audit_mq_getsetattr(mqdes, &mqstat);
1186                 spin_lock(&filp->f_lock);
1187                 if (mqstat.mq_flags & O_NONBLOCK)
1188                         filp->f_flags |= O_NONBLOCK;
1189                 else
1190                         filp->f_flags &= ~O_NONBLOCK;
1191                 spin_unlock(&filp->f_lock);
1192
1193                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1194         }
1195
1196         spin_unlock(&info->lock);
1197
1198         ret = 0;
1199         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1200                                                 sizeof(struct mq_attr)))
1201                 ret = -EFAULT;
1202
1203 out_fput:
1204         fput(filp);
1205 out:
1206         return ret;
1207 }
1208
1209 static const struct inode_operations mqueue_dir_inode_operations = {
1210         .lookup = simple_lookup,
1211         .create = mqueue_create,
1212         .unlink = mqueue_unlink,
1213 };
1214
1215 static const struct file_operations mqueue_file_operations = {
1216         .flush = mqueue_flush_file,
1217         .poll = mqueue_poll_file,
1218         .read = mqueue_read_file,
1219 };
1220
1221 static const struct super_operations mqueue_super_ops = {
1222         .alloc_inode = mqueue_alloc_inode,
1223         .destroy_inode = mqueue_destroy_inode,
1224         .statfs = simple_statfs,
1225         .delete_inode = mqueue_delete_inode,
1226         .drop_inode = generic_delete_inode,
1227 };
1228
1229 static struct file_system_type mqueue_fs_type = {
1230         .name = "mqueue",
1231         .get_sb = mqueue_get_sb,
1232         .kill_sb = kill_litter_super,
1233 };
1234
1235 int mq_init_ns(struct ipc_namespace *ns)
1236 {
1237         ns->mq_queues_count  = 0;
1238         ns->mq_queues_max    = DFLT_QUEUESMAX;
1239         ns->mq_msg_max       = DFLT_MSGMAX;
1240         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1241
1242         ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1243         if (IS_ERR(ns->mq_mnt)) {
1244                 int err = PTR_ERR(ns->mq_mnt);
1245                 ns->mq_mnt = NULL;
1246                 return err;
1247         }
1248         return 0;
1249 }
1250
1251 void mq_clear_sbinfo(struct ipc_namespace *ns)
1252 {
1253         ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1254 }
1255
1256 void mq_put_mnt(struct ipc_namespace *ns)
1257 {
1258         mntput(ns->mq_mnt);
1259 }
1260
1261 static int __init init_mqueue_fs(void)
1262 {
1263         int error;
1264
1265         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1266                                 sizeof(struct mqueue_inode_info), 0,
1267                                 SLAB_HWCACHE_ALIGN, init_once);
1268         if (mqueue_inode_cachep == NULL)
1269                 return -ENOMEM;
1270
1271         /* ignore failues - they are not fatal */
1272         mq_sysctl_table = mq_register_sysctl_table();
1273
1274         error = register_filesystem(&mqueue_fs_type);
1275         if (error)
1276                 goto out_sysctl;
1277
1278         spin_lock_init(&mq_lock);
1279
1280         init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns);
1281         if (IS_ERR(init_ipc_ns.mq_mnt)) {
1282                 error = PTR_ERR(init_ipc_ns.mq_mnt);
1283                 goto out_filesystem;
1284         }
1285
1286         return 0;
1287
1288 out_filesystem:
1289         unregister_filesystem(&mqueue_fs_type);
1290 out_sysctl:
1291         if (mq_sysctl_table)
1292                 unregister_sysctl_table(mq_sysctl_table);
1293         kmem_cache_destroy(mqueue_inode_cachep);
1294         return error;
1295 }
1296
1297 __initcall(init_mqueue_fs);