Merge branch 'linus' into timers/core
[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 #include <linux/ipc_namespace.h>
35 #include <linux/slab.h>
36
37 #include <net/sock.h>
38 #include "util.h"
39
40 #define MQUEUE_MAGIC    0x19800202
41 #define DIRENT_SIZE     20
42 #define FILENT_SIZE     80
43
44 #define SEND            0
45 #define RECV            1
46
47 #define STATE_NONE      0
48 #define STATE_PENDING   1
49 #define STATE_READY     2
50
51 struct ext_wait_queue {         /* queue of sleeping tasks */
52         struct task_struct *task;
53         struct list_head list;
54         struct msg_msg *msg;    /* ptr of loaded message */
55         int state;              /* one of STATE_* values */
56 };
57
58 struct mqueue_inode_info {
59         spinlock_t lock;
60         struct inode vfs_inode;
61         wait_queue_head_t wait_q;
62
63         struct msg_msg **messages;
64         struct mq_attr attr;
65
66         struct sigevent notify;
67         struct pid* notify_owner;
68         struct user_struct *user;       /* user who created, for accounting */
69         struct sock *notify_sock;
70         struct sk_buff *notify_cookie;
71
72         /* for tasks waiting for free space and messages, respectively */
73         struct ext_wait_queue e_wait_q[2];
74
75         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
76 };
77
78 static const struct inode_operations mqueue_dir_inode_operations;
79 static const struct file_operations mqueue_file_operations;
80 static const struct super_operations mqueue_super_ops;
81 static void remove_notification(struct mqueue_inode_info *info);
82
83 static struct kmem_cache *mqueue_inode_cachep;
84
85 static struct ctl_table_header * mq_sysctl_table;
86
87 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
88 {
89         return container_of(inode, struct mqueue_inode_info, vfs_inode);
90 }
91
92 /*
93  * This routine should be called with the mq_lock held.
94  */
95 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
96 {
97         return get_ipc_ns(inode->i_sb->s_fs_info);
98 }
99
100 static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
101 {
102         struct ipc_namespace *ns;
103
104         spin_lock(&mq_lock);
105         ns = __get_ns_from_inode(inode);
106         spin_unlock(&mq_lock);
107         return ns;
108 }
109
110 static struct inode *mqueue_get_inode(struct super_block *sb,
111                 struct ipc_namespace *ipc_ns, int mode,
112                 struct mq_attr *attr)
113 {
114         struct user_struct *u = current_user();
115         struct inode *inode;
116
117         inode = new_inode(sb);
118         if (inode) {
119                 inode->i_mode = mode;
120                 inode->i_uid = current_fsuid();
121                 inode->i_gid = current_fsgid();
122                 inode->i_mtime = inode->i_ctime = inode->i_atime =
123                                 CURRENT_TIME;
124
125                 if (S_ISREG(mode)) {
126                         struct mqueue_inode_info *info;
127                         struct task_struct *p = current;
128                         unsigned long mq_bytes, mq_msg_tblsz;
129
130                         inode->i_fop = &mqueue_file_operations;
131                         inode->i_size = FILENT_SIZE;
132                         /* mqueue specific info */
133                         info = MQUEUE_I(inode);
134                         spin_lock_init(&info->lock);
135                         init_waitqueue_head(&info->wait_q);
136                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
137                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
138                         info->notify_owner = NULL;
139                         info->qsize = 0;
140                         info->user = NULL;      /* set when all is ok */
141                         memset(&info->attr, 0, sizeof(info->attr));
142                         info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
143                         info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
144                         if (attr) {
145                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
146                                 info->attr.mq_msgsize = attr->mq_msgsize;
147                         }
148                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
149                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
150                         if (!info->messages)
151                                 goto out_inode;
152
153                         mq_bytes = (mq_msg_tblsz +
154                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
155
156                         spin_lock(&mq_lock);
157                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
158                             u->mq_bytes + mq_bytes >
159                             task_rlimit(p, RLIMIT_MSGQUEUE)) {
160                                 spin_unlock(&mq_lock);
161                                 kfree(info->messages);
162                                 goto out_inode;
163                         }
164                         u->mq_bytes += mq_bytes;
165                         spin_unlock(&mq_lock);
166
167                         /* all is ok */
168                         info->user = get_uid(u);
169                 } else if (S_ISDIR(mode)) {
170                         inc_nlink(inode);
171                         /* Some things misbehave if size == 0 on a directory */
172                         inode->i_size = 2 * DIRENT_SIZE;
173                         inode->i_op = &mqueue_dir_inode_operations;
174                         inode->i_fop = &simple_dir_operations;
175                 }
176         }
177         return inode;
178 out_inode:
179         make_bad_inode(inode);
180         iput(inode);
181         return NULL;
182 }
183
184 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
185 {
186         struct inode *inode;
187         struct ipc_namespace *ns = data;
188         int error;
189
190         sb->s_blocksize = PAGE_CACHE_SIZE;
191         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
192         sb->s_magic = MQUEUE_MAGIC;
193         sb->s_op = &mqueue_super_ops;
194
195         inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO,
196                                 NULL);
197         if (!inode) {
198                 error = -ENOMEM;
199                 goto out;
200         }
201
202         sb->s_root = d_alloc_root(inode);
203         if (!sb->s_root) {
204                 iput(inode);
205                 error = -ENOMEM;
206                 goto out;
207         }
208         error = 0;
209
210 out:
211         return error;
212 }
213
214 static int mqueue_get_sb(struct file_system_type *fs_type,
215                          int flags, const char *dev_name,
216                          void *data, struct vfsmount *mnt)
217 {
218         if (!(flags & MS_KERNMOUNT))
219                 data = current->nsproxy->ipc_ns;
220         return get_sb_ns(fs_type, flags, data, mqueue_fill_super, mnt);
221 }
222
223 static void init_once(void *foo)
224 {
225         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
226
227         inode_init_once(&p->vfs_inode);
228 }
229
230 static struct inode *mqueue_alloc_inode(struct super_block *sb)
231 {
232         struct mqueue_inode_info *ei;
233
234         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
235         if (!ei)
236                 return NULL;
237         return &ei->vfs_inode;
238 }
239
240 static void mqueue_destroy_inode(struct inode *inode)
241 {
242         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
243 }
244
245 static void mqueue_delete_inode(struct inode *inode)
246 {
247         struct mqueue_inode_info *info;
248         struct user_struct *user;
249         unsigned long mq_bytes;
250         int i;
251         struct ipc_namespace *ipc_ns;
252
253         if (S_ISDIR(inode->i_mode)) {
254                 clear_inode(inode);
255                 return;
256         }
257         ipc_ns = get_ns_from_inode(inode);
258         info = MQUEUE_I(inode);
259         spin_lock(&info->lock);
260         for (i = 0; i < info->attr.mq_curmsgs; i++)
261                 free_msg(info->messages[i]);
262         kfree(info->messages);
263         spin_unlock(&info->lock);
264
265         clear_inode(inode);
266
267         /* Total amount of bytes accounted for the mqueue */
268         mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
269             + info->attr.mq_msgsize);
270         user = info->user;
271         if (user) {
272                 spin_lock(&mq_lock);
273                 user->mq_bytes -= mq_bytes;
274                 /*
275                  * get_ns_from_inode() ensures that the
276                  * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
277                  * to which we now hold a reference, or it is NULL.
278                  * We can't put it here under mq_lock, though.
279                  */
280                 if (ipc_ns)
281                         ipc_ns->mq_queues_count--;
282                 spin_unlock(&mq_lock);
283                 free_uid(user);
284         }
285         if (ipc_ns)
286                 put_ipc_ns(ipc_ns);
287 }
288
289 static int mqueue_create(struct inode *dir, struct dentry *dentry,
290                                 int mode, struct nameidata *nd)
291 {
292         struct inode *inode;
293         struct mq_attr *attr = dentry->d_fsdata;
294         int error;
295         struct ipc_namespace *ipc_ns;
296
297         spin_lock(&mq_lock);
298         ipc_ns = __get_ns_from_inode(dir);
299         if (!ipc_ns) {
300                 error = -EACCES;
301                 goto out_unlock;
302         }
303         if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
304                         !capable(CAP_SYS_RESOURCE)) {
305                 error = -ENOSPC;
306                 goto out_unlock;
307         }
308         ipc_ns->mq_queues_count++;
309         spin_unlock(&mq_lock);
310
311         inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
312         if (!inode) {
313                 error = -ENOMEM;
314                 spin_lock(&mq_lock);
315                 ipc_ns->mq_queues_count--;
316                 goto out_unlock;
317         }
318
319         put_ipc_ns(ipc_ns);
320         dir->i_size += DIRENT_SIZE;
321         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
322
323         d_instantiate(dentry, inode);
324         dget(dentry);
325         return 0;
326 out_unlock:
327         spin_unlock(&mq_lock);
328         if (ipc_ns)
329                 put_ipc_ns(ipc_ns);
330         return error;
331 }
332
333 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
334 {
335         struct inode *inode = dentry->d_inode;
336
337         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
338         dir->i_size -= DIRENT_SIZE;
339         drop_nlink(inode);
340         dput(dentry);
341         return 0;
342 }
343
344 /*
345 *       This is routine for system read from queue file.
346 *       To avoid mess with doing here some sort of mq_receive we allow
347 *       to read only queue size & notification info (the only values
348 *       that are interesting from user point of view and aren't accessible
349 *       through std routines)
350 */
351 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
352                                 size_t count, loff_t *off)
353 {
354         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
355         char buffer[FILENT_SIZE];
356         ssize_t ret;
357
358         spin_lock(&info->lock);
359         snprintf(buffer, sizeof(buffer),
360                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
361                         info->qsize,
362                         info->notify_owner ? info->notify.sigev_notify : 0,
363                         (info->notify_owner &&
364                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
365                                 info->notify.sigev_signo : 0,
366                         pid_vnr(info->notify_owner));
367         spin_unlock(&info->lock);
368         buffer[sizeof(buffer)-1] = '\0';
369
370         ret = simple_read_from_buffer(u_data, count, off, buffer,
371                                 strlen(buffer));
372         if (ret <= 0)
373                 return ret;
374
375         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
376         return ret;
377 }
378
379 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
380 {
381         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
382
383         spin_lock(&info->lock);
384         if (task_tgid(current) == info->notify_owner)
385                 remove_notification(info);
386
387         spin_unlock(&info->lock);
388         return 0;
389 }
390
391 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
392 {
393         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
394         int retval = 0;
395
396         poll_wait(filp, &info->wait_q, poll_tab);
397
398         spin_lock(&info->lock);
399         if (info->attr.mq_curmsgs)
400                 retval = POLLIN | POLLRDNORM;
401
402         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
403                 retval |= POLLOUT | POLLWRNORM;
404         spin_unlock(&info->lock);
405
406         return retval;
407 }
408
409 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
410 static void wq_add(struct mqueue_inode_info *info, int sr,
411                         struct ext_wait_queue *ewp)
412 {
413         struct ext_wait_queue *walk;
414
415         ewp->task = current;
416
417         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
418                 if (walk->task->static_prio <= current->static_prio) {
419                         list_add_tail(&ewp->list, &walk->list);
420                         return;
421                 }
422         }
423         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
424 }
425
426 /*
427  * Puts current task to sleep. Caller must hold queue lock. After return
428  * lock isn't held.
429  * sr: SEND or RECV
430  */
431 static int wq_sleep(struct mqueue_inode_info *info, int sr,
432                     ktime_t *timeout, struct ext_wait_queue *ewp)
433 {
434         int retval;
435         signed long time;
436
437         wq_add(info, sr, ewp);
438
439         for (;;) {
440                 set_current_state(TASK_INTERRUPTIBLE);
441
442                 spin_unlock(&info->lock);
443                 time = schedule_hrtimeout_range_clock(timeout,
444                     HRTIMER_MODE_ABS, 0, CLOCK_REALTIME);
445
446                 while (ewp->state == STATE_PENDING)
447                         cpu_relax();
448
449                 if (ewp->state == STATE_READY) {
450                         retval = 0;
451                         goto out;
452                 }
453                 spin_lock(&info->lock);
454                 if (ewp->state == STATE_READY) {
455                         retval = 0;
456                         goto out_unlock;
457                 }
458                 if (signal_pending(current)) {
459                         retval = -ERESTARTSYS;
460                         break;
461                 }
462                 if (time == 0) {
463                         retval = -ETIMEDOUT;
464                         break;
465                 }
466         }
467         list_del(&ewp->list);
468 out_unlock:
469         spin_unlock(&info->lock);
470 out:
471         return retval;
472 }
473
474 /*
475  * Returns waiting task that should be serviced first or NULL if none exists
476  */
477 static struct ext_wait_queue *wq_get_first_waiter(
478                 struct mqueue_inode_info *info, int sr)
479 {
480         struct list_head *ptr;
481
482         ptr = info->e_wait_q[sr].list.prev;
483         if (ptr == &info->e_wait_q[sr].list)
484                 return NULL;
485         return list_entry(ptr, struct ext_wait_queue, list);
486 }
487
488 /* Auxiliary functions to manipulate messages' list */
489 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
490 {
491         int k;
492
493         k = info->attr.mq_curmsgs - 1;
494         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
495                 info->messages[k + 1] = info->messages[k];
496                 k--;
497         }
498         info->attr.mq_curmsgs++;
499         info->qsize += ptr->m_ts;
500         info->messages[k + 1] = ptr;
501 }
502
503 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
504 {
505         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
506         return info->messages[info->attr.mq_curmsgs];
507 }
508
509 static inline void set_cookie(struct sk_buff *skb, char code)
510 {
511         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
512 }
513
514 /*
515  * The next function is only to split too long sys_mq_timedsend
516  */
517 static void __do_notify(struct mqueue_inode_info *info)
518 {
519         /* notification
520          * invoked when there is registered process and there isn't process
521          * waiting synchronously for message AND state of queue changed from
522          * empty to not empty. Here we are sure that no one is waiting
523          * synchronously. */
524         if (info->notify_owner &&
525             info->attr.mq_curmsgs == 1) {
526                 struct siginfo sig_i;
527                 switch (info->notify.sigev_notify) {
528                 case SIGEV_NONE:
529                         break;
530                 case SIGEV_SIGNAL:
531                         /* sends signal */
532
533                         sig_i.si_signo = info->notify.sigev_signo;
534                         sig_i.si_errno = 0;
535                         sig_i.si_code = SI_MESGQ;
536                         sig_i.si_value = info->notify.sigev_value;
537                         sig_i.si_pid = task_tgid_nr_ns(current,
538                                                 ns_of_pid(info->notify_owner));
539                         sig_i.si_uid = current_uid();
540
541                         kill_pid_info(info->notify.sigev_signo,
542                                       &sig_i, info->notify_owner);
543                         break;
544                 case SIGEV_THREAD:
545                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
546                         netlink_sendskb(info->notify_sock, info->notify_cookie);
547                         break;
548                 }
549                 /* after notification unregisters process */
550                 put_pid(info->notify_owner);
551                 info->notify_owner = NULL;
552         }
553         wake_up(&info->wait_q);
554 }
555
556 static int prepare_timeout(const struct timespec __user *u_abs_timeout,
557                            ktime_t *expires, struct timespec *ts)
558 {
559         if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
560                 return -EFAULT;
561         if (!timespec_valid(ts))
562                 return -EINVAL;
563
564         *expires = timespec_to_ktime(*ts);
565         return 0;
566 }
567
568 static void remove_notification(struct mqueue_inode_info *info)
569 {
570         if (info->notify_owner != NULL &&
571             info->notify.sigev_notify == SIGEV_THREAD) {
572                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
573                 netlink_sendskb(info->notify_sock, info->notify_cookie);
574         }
575         put_pid(info->notify_owner);
576         info->notify_owner = NULL;
577 }
578
579 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
580 {
581         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
582                 return 0;
583         if (capable(CAP_SYS_RESOURCE)) {
584                 if (attr->mq_maxmsg > HARD_MSGMAX)
585                         return 0;
586         } else {
587                 if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
588                                 attr->mq_msgsize > ipc_ns->mq_msgsize_max)
589                         return 0;
590         }
591         /* check for overflow */
592         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
593                 return 0;
594         if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
595             + sizeof (struct msg_msg *))) <
596             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
597                 return 0;
598         return 1;
599 }
600
601 /*
602  * Invoked when creating a new queue via sys_mq_open
603  */
604 static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
605                         struct dentry *dentry, int oflag, mode_t mode,
606                         struct mq_attr *attr)
607 {
608         const struct cred *cred = current_cred();
609         struct file *result;
610         int ret;
611
612         if (attr) {
613                 if (!mq_attr_ok(ipc_ns, attr)) {
614                         ret = -EINVAL;
615                         goto out;
616                 }
617                 /* store for use during create */
618                 dentry->d_fsdata = attr;
619         }
620
621         mode &= ~current_umask();
622         ret = mnt_want_write(ipc_ns->mq_mnt);
623         if (ret)
624                 goto out;
625         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
626         dentry->d_fsdata = NULL;
627         if (ret)
628                 goto out_drop_write;
629
630         result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
631         /*
632          * dentry_open() took a persistent mnt_want_write(),
633          * so we can now drop this one.
634          */
635         mnt_drop_write(ipc_ns->mq_mnt);
636         return result;
637
638 out_drop_write:
639         mnt_drop_write(ipc_ns->mq_mnt);
640 out:
641         dput(dentry);
642         mntput(ipc_ns->mq_mnt);
643         return ERR_PTR(ret);
644 }
645
646 /* Opens existing queue */
647 static struct file *do_open(struct ipc_namespace *ipc_ns,
648                                 struct dentry *dentry, int oflag)
649 {
650         int ret;
651         const struct cred *cred = current_cred();
652
653         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
654                                                   MAY_READ | MAY_WRITE };
655
656         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
657                 ret = -EINVAL;
658                 goto err;
659         }
660
661         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
662                 ret = -EACCES;
663                 goto err;
664         }
665
666         return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
667
668 err:
669         dput(dentry);
670         mntput(ipc_ns->mq_mnt);
671         return ERR_PTR(ret);
672 }
673
674 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
675                 struct mq_attr __user *, u_attr)
676 {
677         struct dentry *dentry;
678         struct file *filp;
679         char *name;
680         struct mq_attr attr;
681         int fd, error;
682         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
683
684         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
685                 return -EFAULT;
686
687         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
688
689         if (IS_ERR(name = getname(u_name)))
690                 return PTR_ERR(name);
691
692         fd = get_unused_fd_flags(O_CLOEXEC);
693         if (fd < 0)
694                 goto out_putname;
695
696         mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
697         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
698         if (IS_ERR(dentry)) {
699                 error = PTR_ERR(dentry);
700                 goto out_putfd;
701         }
702         mntget(ipc_ns->mq_mnt);
703
704         if (oflag & O_CREAT) {
705                 if (dentry->d_inode) {  /* entry already exists */
706                         audit_inode(name, dentry);
707                         if (oflag & O_EXCL) {
708                                 error = -EEXIST;
709                                 goto out;
710                         }
711                         filp = do_open(ipc_ns, dentry, oflag);
712                 } else {
713                         filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
714                                                 dentry, oflag, mode,
715                                                 u_attr ? &attr : NULL);
716                 }
717         } else {
718                 if (!dentry->d_inode) {
719                         error = -ENOENT;
720                         goto out;
721                 }
722                 audit_inode(name, dentry);
723                 filp = do_open(ipc_ns, dentry, oflag);
724         }
725
726         if (IS_ERR(filp)) {
727                 error = PTR_ERR(filp);
728                 goto out_putfd;
729         }
730
731         fd_install(fd, filp);
732         goto out_upsem;
733
734 out:
735         dput(dentry);
736         mntput(ipc_ns->mq_mnt);
737 out_putfd:
738         put_unused_fd(fd);
739         fd = error;
740 out_upsem:
741         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
742 out_putname:
743         putname(name);
744         return fd;
745 }
746
747 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
748 {
749         int err;
750         char *name;
751         struct dentry *dentry;
752         struct inode *inode = NULL;
753         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
754
755         name = getname(u_name);
756         if (IS_ERR(name))
757                 return PTR_ERR(name);
758
759         mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
760                         I_MUTEX_PARENT);
761         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
762         if (IS_ERR(dentry)) {
763                 err = PTR_ERR(dentry);
764                 goto out_unlock;
765         }
766
767         if (!dentry->d_inode) {
768                 err = -ENOENT;
769                 goto out_err;
770         }
771
772         inode = dentry->d_inode;
773         if (inode)
774                 atomic_inc(&inode->i_count);
775         err = mnt_want_write(ipc_ns->mq_mnt);
776         if (err)
777                 goto out_err;
778         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
779         mnt_drop_write(ipc_ns->mq_mnt);
780 out_err:
781         dput(dentry);
782
783 out_unlock:
784         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
785         putname(name);
786         if (inode)
787                 iput(inode);
788
789         return err;
790 }
791
792 /* Pipelined send and receive functions.
793  *
794  * If a receiver finds no waiting message, then it registers itself in the
795  * list of waiting receivers. A sender checks that list before adding the new
796  * message into the message array. If there is a waiting receiver, then it
797  * bypasses the message array and directly hands the message over to the
798  * receiver.
799  * The receiver accepts the message and returns without grabbing the queue
800  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
801  * are necessary. The same algorithm is used for sysv semaphores, see
802  * ipc/sem.c for more details.
803  *
804  * The same algorithm is used for senders.
805  */
806
807 /* pipelined_send() - send a message directly to the task waiting in
808  * sys_mq_timedreceive() (without inserting message into a queue).
809  */
810 static inline void pipelined_send(struct mqueue_inode_info *info,
811                                   struct msg_msg *message,
812                                   struct ext_wait_queue *receiver)
813 {
814         receiver->msg = message;
815         list_del(&receiver->list);
816         receiver->state = STATE_PENDING;
817         wake_up_process(receiver->task);
818         smp_wmb();
819         receiver->state = STATE_READY;
820 }
821
822 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
823  * gets its message and put to the queue (we have one free place for sure). */
824 static inline void pipelined_receive(struct mqueue_inode_info *info)
825 {
826         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
827
828         if (!sender) {
829                 /* for poll */
830                 wake_up_interruptible(&info->wait_q);
831                 return;
832         }
833         msg_insert(sender->msg, info);
834         list_del(&sender->list);
835         sender->state = STATE_PENDING;
836         wake_up_process(sender->task);
837         smp_wmb();
838         sender->state = STATE_READY;
839 }
840
841 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
842                 size_t, msg_len, unsigned int, msg_prio,
843                 const struct timespec __user *, u_abs_timeout)
844 {
845         struct file *filp;
846         struct inode *inode;
847         struct ext_wait_queue wait;
848         struct ext_wait_queue *receiver;
849         struct msg_msg *msg_ptr;
850         struct mqueue_inode_info *info;
851         ktime_t expires, *timeout = NULL;
852         struct timespec ts;
853         int ret;
854
855         if (u_abs_timeout) {
856                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
857                 if (res)
858                         return res;
859                 timeout = &expires;
860         }
861
862         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
863                 return -EINVAL;
864
865         audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
866
867         filp = fget(mqdes);
868         if (unlikely(!filp)) {
869                 ret = -EBADF;
870                 goto out;
871         }
872
873         inode = filp->f_path.dentry->d_inode;
874         if (unlikely(filp->f_op != &mqueue_file_operations)) {
875                 ret = -EBADF;
876                 goto out_fput;
877         }
878         info = MQUEUE_I(inode);
879         audit_inode(NULL, filp->f_path.dentry);
880
881         if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
882                 ret = -EBADF;
883                 goto out_fput;
884         }
885
886         if (unlikely(msg_len > info->attr.mq_msgsize)) {
887                 ret = -EMSGSIZE;
888                 goto out_fput;
889         }
890
891         /* First try to allocate memory, before doing anything with
892          * existing queues. */
893         msg_ptr = load_msg(u_msg_ptr, msg_len);
894         if (IS_ERR(msg_ptr)) {
895                 ret = PTR_ERR(msg_ptr);
896                 goto out_fput;
897         }
898         msg_ptr->m_ts = msg_len;
899         msg_ptr->m_type = msg_prio;
900
901         spin_lock(&info->lock);
902
903         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
904                 if (filp->f_flags & O_NONBLOCK) {
905                         spin_unlock(&info->lock);
906                         ret = -EAGAIN;
907                 } else {
908                         wait.task = current;
909                         wait.msg = (void *) msg_ptr;
910                         wait.state = STATE_NONE;
911                         ret = wq_sleep(info, SEND, timeout, &wait);
912                 }
913                 if (ret < 0)
914                         free_msg(msg_ptr);
915         } else {
916                 receiver = wq_get_first_waiter(info, RECV);
917                 if (receiver) {
918                         pipelined_send(info, msg_ptr, receiver);
919                 } else {
920                         /* adds message to the queue */
921                         msg_insert(msg_ptr, info);
922                         __do_notify(info);
923                 }
924                 inode->i_atime = inode->i_mtime = inode->i_ctime =
925                                 CURRENT_TIME;
926                 spin_unlock(&info->lock);
927                 ret = 0;
928         }
929 out_fput:
930         fput(filp);
931 out:
932         return ret;
933 }
934
935 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
936                 size_t, msg_len, unsigned int __user *, u_msg_prio,
937                 const struct timespec __user *, u_abs_timeout)
938 {
939         ssize_t ret;
940         struct msg_msg *msg_ptr;
941         struct file *filp;
942         struct inode *inode;
943         struct mqueue_inode_info *info;
944         struct ext_wait_queue wait;
945         ktime_t expires, *timeout = NULL;
946         struct timespec ts;
947
948         if (u_abs_timeout) {
949                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
950                 if (res)
951                         return res;
952                 timeout = &expires;
953         }
954
955         audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
956
957         filp = fget(mqdes);
958         if (unlikely(!filp)) {
959                 ret = -EBADF;
960                 goto out;
961         }
962
963         inode = filp->f_path.dentry->d_inode;
964         if (unlikely(filp->f_op != &mqueue_file_operations)) {
965                 ret = -EBADF;
966                 goto out_fput;
967         }
968         info = MQUEUE_I(inode);
969         audit_inode(NULL, filp->f_path.dentry);
970
971         if (unlikely(!(filp->f_mode & FMODE_READ))) {
972                 ret = -EBADF;
973                 goto out_fput;
974         }
975
976         /* checks if buffer is big enough */
977         if (unlikely(msg_len < info->attr.mq_msgsize)) {
978                 ret = -EMSGSIZE;
979                 goto out_fput;
980         }
981
982         spin_lock(&info->lock);
983         if (info->attr.mq_curmsgs == 0) {
984                 if (filp->f_flags & O_NONBLOCK) {
985                         spin_unlock(&info->lock);
986                         ret = -EAGAIN;
987                 } else {
988                         wait.task = current;
989                         wait.state = STATE_NONE;
990                         ret = wq_sleep(info, RECV, timeout, &wait);
991                         msg_ptr = wait.msg;
992                 }
993         } else {
994                 msg_ptr = msg_get(info);
995
996                 inode->i_atime = inode->i_mtime = inode->i_ctime =
997                                 CURRENT_TIME;
998
999                 /* There is now free space in queue. */
1000                 pipelined_receive(info);
1001                 spin_unlock(&info->lock);
1002                 ret = 0;
1003         }
1004         if (ret == 0) {
1005                 ret = msg_ptr->m_ts;
1006
1007                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1008                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1009                         ret = -EFAULT;
1010                 }
1011                 free_msg(msg_ptr);
1012         }
1013 out_fput:
1014         fput(filp);
1015 out:
1016         return ret;
1017 }
1018
1019 /*
1020  * Notes: the case when user wants us to deregister (with NULL as pointer)
1021  * and he isn't currently owner of notification, will be silently discarded.
1022  * It isn't explicitly defined in the POSIX.
1023  */
1024 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1025                 const struct sigevent __user *, u_notification)
1026 {
1027         int ret;
1028         struct file *filp;
1029         struct sock *sock;
1030         struct inode *inode;
1031         struct sigevent notification;
1032         struct mqueue_inode_info *info;
1033         struct sk_buff *nc;
1034
1035         if (u_notification) {
1036                 if (copy_from_user(&notification, u_notification,
1037                                         sizeof(struct sigevent)))
1038                         return -EFAULT;
1039         }
1040
1041         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1042
1043         nc = NULL;
1044         sock = NULL;
1045         if (u_notification != NULL) {
1046                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1047                              notification.sigev_notify != SIGEV_SIGNAL &&
1048                              notification.sigev_notify != SIGEV_THREAD))
1049                         return -EINVAL;
1050                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1051                         !valid_signal(notification.sigev_signo)) {
1052                         return -EINVAL;
1053                 }
1054                 if (notification.sigev_notify == SIGEV_THREAD) {
1055                         long timeo;
1056
1057                         /* create the notify skb */
1058                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1059                         if (!nc) {
1060                                 ret = -ENOMEM;
1061                                 goto out;
1062                         }
1063                         if (copy_from_user(nc->data,
1064                                         notification.sigev_value.sival_ptr,
1065                                         NOTIFY_COOKIE_LEN)) {
1066                                 ret = -EFAULT;
1067                                 goto out;
1068                         }
1069
1070                         /* TODO: add a header? */
1071                         skb_put(nc, NOTIFY_COOKIE_LEN);
1072                         /* and attach it to the socket */
1073 retry:
1074                         filp = fget(notification.sigev_signo);
1075                         if (!filp) {
1076                                 ret = -EBADF;
1077                                 goto out;
1078                         }
1079                         sock = netlink_getsockbyfilp(filp);
1080                         fput(filp);
1081                         if (IS_ERR(sock)) {
1082                                 ret = PTR_ERR(sock);
1083                                 sock = NULL;
1084                                 goto out;
1085                         }
1086
1087                         timeo = MAX_SCHEDULE_TIMEOUT;
1088                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1089                         if (ret == 1)
1090                                 goto retry;
1091                         if (ret) {
1092                                 sock = NULL;
1093                                 nc = NULL;
1094                                 goto out;
1095                         }
1096                 }
1097         }
1098
1099         filp = fget(mqdes);
1100         if (!filp) {
1101                 ret = -EBADF;
1102                 goto out;
1103         }
1104
1105         inode = filp->f_path.dentry->d_inode;
1106         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1107                 ret = -EBADF;
1108                 goto out_fput;
1109         }
1110         info = MQUEUE_I(inode);
1111
1112         ret = 0;
1113         spin_lock(&info->lock);
1114         if (u_notification == NULL) {
1115                 if (info->notify_owner == task_tgid(current)) {
1116                         remove_notification(info);
1117                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1118                 }
1119         } else if (info->notify_owner != NULL) {
1120                 ret = -EBUSY;
1121         } else {
1122                 switch (notification.sigev_notify) {
1123                 case SIGEV_NONE:
1124                         info->notify.sigev_notify = SIGEV_NONE;
1125                         break;
1126                 case SIGEV_THREAD:
1127                         info->notify_sock = sock;
1128                         info->notify_cookie = nc;
1129                         sock = NULL;
1130                         nc = NULL;
1131                         info->notify.sigev_notify = SIGEV_THREAD;
1132                         break;
1133                 case SIGEV_SIGNAL:
1134                         info->notify.sigev_signo = notification.sigev_signo;
1135                         info->notify.sigev_value = notification.sigev_value;
1136                         info->notify.sigev_notify = SIGEV_SIGNAL;
1137                         break;
1138                 }
1139
1140                 info->notify_owner = get_pid(task_tgid(current));
1141                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1142         }
1143         spin_unlock(&info->lock);
1144 out_fput:
1145         fput(filp);
1146 out:
1147         if (sock) {
1148                 netlink_detachskb(sock, nc);
1149         } else if (nc) {
1150                 dev_kfree_skb(nc);
1151         }
1152         return ret;
1153 }
1154
1155 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1156                 const struct mq_attr __user *, u_mqstat,
1157                 struct mq_attr __user *, u_omqstat)
1158 {
1159         int ret;
1160         struct mq_attr mqstat, omqstat;
1161         struct file *filp;
1162         struct inode *inode;
1163         struct mqueue_inode_info *info;
1164
1165         if (u_mqstat != NULL) {
1166                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1167                         return -EFAULT;
1168                 if (mqstat.mq_flags & (~O_NONBLOCK))
1169                         return -EINVAL;
1170         }
1171
1172         filp = fget(mqdes);
1173         if (!filp) {
1174                 ret = -EBADF;
1175                 goto out;
1176         }
1177
1178         inode = filp->f_path.dentry->d_inode;
1179         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1180                 ret = -EBADF;
1181                 goto out_fput;
1182         }
1183         info = MQUEUE_I(inode);
1184
1185         spin_lock(&info->lock);
1186
1187         omqstat = info->attr;
1188         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1189         if (u_mqstat) {
1190                 audit_mq_getsetattr(mqdes, &mqstat);
1191                 spin_lock(&filp->f_lock);
1192                 if (mqstat.mq_flags & O_NONBLOCK)
1193                         filp->f_flags |= O_NONBLOCK;
1194                 else
1195                         filp->f_flags &= ~O_NONBLOCK;
1196                 spin_unlock(&filp->f_lock);
1197
1198                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1199         }
1200
1201         spin_unlock(&info->lock);
1202
1203         ret = 0;
1204         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1205                                                 sizeof(struct mq_attr)))
1206                 ret = -EFAULT;
1207
1208 out_fput:
1209         fput(filp);
1210 out:
1211         return ret;
1212 }
1213
1214 static const struct inode_operations mqueue_dir_inode_operations = {
1215         .lookup = simple_lookup,
1216         .create = mqueue_create,
1217         .unlink = mqueue_unlink,
1218 };
1219
1220 static const struct file_operations mqueue_file_operations = {
1221         .flush = mqueue_flush_file,
1222         .poll = mqueue_poll_file,
1223         .read = mqueue_read_file,
1224 };
1225
1226 static const struct super_operations mqueue_super_ops = {
1227         .alloc_inode = mqueue_alloc_inode,
1228         .destroy_inode = mqueue_destroy_inode,
1229         .statfs = simple_statfs,
1230         .delete_inode = mqueue_delete_inode,
1231         .drop_inode = generic_delete_inode,
1232 };
1233
1234 static struct file_system_type mqueue_fs_type = {
1235         .name = "mqueue",
1236         .get_sb = mqueue_get_sb,
1237         .kill_sb = kill_litter_super,
1238 };
1239
1240 int mq_init_ns(struct ipc_namespace *ns)
1241 {
1242         ns->mq_queues_count  = 0;
1243         ns->mq_queues_max    = DFLT_QUEUESMAX;
1244         ns->mq_msg_max       = DFLT_MSGMAX;
1245         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1246
1247         ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1248         if (IS_ERR(ns->mq_mnt)) {
1249                 int err = PTR_ERR(ns->mq_mnt);
1250                 ns->mq_mnt = NULL;
1251                 return err;
1252         }
1253         return 0;
1254 }
1255
1256 void mq_clear_sbinfo(struct ipc_namespace *ns)
1257 {
1258         ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1259 }
1260
1261 void mq_put_mnt(struct ipc_namespace *ns)
1262 {
1263         mntput(ns->mq_mnt);
1264 }
1265
1266 static int __init init_mqueue_fs(void)
1267 {
1268         int error;
1269
1270         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1271                                 sizeof(struct mqueue_inode_info), 0,
1272                                 SLAB_HWCACHE_ALIGN, init_once);
1273         if (mqueue_inode_cachep == NULL)
1274                 return -ENOMEM;
1275
1276         /* ignore failures - they are not fatal */
1277         mq_sysctl_table = mq_register_sysctl_table();
1278
1279         error = register_filesystem(&mqueue_fs_type);
1280         if (error)
1281                 goto out_sysctl;
1282
1283         spin_lock_init(&mq_lock);
1284
1285         init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns);
1286         if (IS_ERR(init_ipc_ns.mq_mnt)) {
1287                 error = PTR_ERR(init_ipc_ns.mq_mnt);
1288                 goto out_filesystem;
1289         }
1290
1291         return 0;
1292
1293 out_filesystem:
1294         unregister_filesystem(&mqueue_fs_type);
1295 out_sysctl:
1296         if (mq_sysctl_table)
1297                 unregister_sysctl_table(mq_sysctl_table);
1298         kmem_cache_destroy(mqueue_inode_cachep);
1299         return error;
1300 }
1301
1302 __initcall(init_mqueue_fs);