of/i2c: Fix request module by alias
[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_ino = get_next_ino();
120                 inode->i_mode = mode;
121                 inode->i_uid = current_fsuid();
122                 inode->i_gid = current_fsgid();
123                 inode->i_mtime = inode->i_ctime = inode->i_atime =
124                                 CURRENT_TIME;
125
126                 if (S_ISREG(mode)) {
127                         struct mqueue_inode_info *info;
128                         struct task_struct *p = current;
129                         unsigned long mq_bytes, mq_msg_tblsz;
130
131                         inode->i_fop = &mqueue_file_operations;
132                         inode->i_size = FILENT_SIZE;
133                         /* mqueue specific info */
134                         info = MQUEUE_I(inode);
135                         spin_lock_init(&info->lock);
136                         init_waitqueue_head(&info->wait_q);
137                         INIT_LIST_HEAD(&info->e_wait_q[0].list);
138                         INIT_LIST_HEAD(&info->e_wait_q[1].list);
139                         info->notify_owner = NULL;
140                         info->qsize = 0;
141                         info->user = NULL;      /* set when all is ok */
142                         memset(&info->attr, 0, sizeof(info->attr));
143                         info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
144                         info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
145                         if (attr) {
146                                 info->attr.mq_maxmsg = attr->mq_maxmsg;
147                                 info->attr.mq_msgsize = attr->mq_msgsize;
148                         }
149                         mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
150                         info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
151                         if (!info->messages)
152                                 goto out_inode;
153
154                         mq_bytes = (mq_msg_tblsz +
155                                 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
156
157                         spin_lock(&mq_lock);
158                         if (u->mq_bytes + mq_bytes < u->mq_bytes ||
159                             u->mq_bytes + mq_bytes >
160                             task_rlimit(p, RLIMIT_MSGQUEUE)) {
161                                 spin_unlock(&mq_lock);
162                                 /* mqueue_evict_inode() releases info->messages */
163                                 goto out_inode;
164                         }
165                         u->mq_bytes += mq_bytes;
166                         spin_unlock(&mq_lock);
167
168                         /* all is ok */
169                         info->user = get_uid(u);
170                 } else if (S_ISDIR(mode)) {
171                         inc_nlink(inode);
172                         /* Some things misbehave if size == 0 on a directory */
173                         inode->i_size = 2 * DIRENT_SIZE;
174                         inode->i_op = &mqueue_dir_inode_operations;
175                         inode->i_fop = &simple_dir_operations;
176                 }
177         }
178         return inode;
179 out_inode:
180         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 struct dentry *mqueue_mount(struct file_system_type *fs_type,
215                          int flags, const char *dev_name,
216                          void *data)
217 {
218         if (!(flags & MS_KERNMOUNT))
219                 data = current->nsproxy->ipc_ns;
220         return mount_ns(fs_type, flags, data, mqueue_fill_super);
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_evict_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         end_writeback(inode);
254
255         if (S_ISDIR(inode->i_mode))
256                 return;
257
258         ipc_ns = get_ns_from_inode(inode);
259         info = MQUEUE_I(inode);
260         spin_lock(&info->lock);
261         for (i = 0; i < info->attr.mq_curmsgs; i++)
262                 free_msg(info->messages[i]);
263         kfree(info->messages);
264         spin_unlock(&info->lock);
265
266         /* Total amount of bytes accounted for the mqueue */
267         mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
268             + info->attr.mq_msgsize);
269         user = info->user;
270         if (user) {
271                 spin_lock(&mq_lock);
272                 user->mq_bytes -= mq_bytes;
273                 /*
274                  * get_ns_from_inode() ensures that the
275                  * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
276                  * to which we now hold a reference, or it is NULL.
277                  * We can't put it here under mq_lock, though.
278                  */
279                 if (ipc_ns)
280                         ipc_ns->mq_queues_count--;
281                 spin_unlock(&mq_lock);
282                 free_uid(user);
283         }
284         if (ipc_ns)
285                 put_ipc_ns(ipc_ns);
286 }
287
288 static int mqueue_create(struct inode *dir, struct dentry *dentry,
289                                 int mode, struct nameidata *nd)
290 {
291         struct inode *inode;
292         struct mq_attr *attr = dentry->d_fsdata;
293         int error;
294         struct ipc_namespace *ipc_ns;
295
296         spin_lock(&mq_lock);
297         ipc_ns = __get_ns_from_inode(dir);
298         if (!ipc_ns) {
299                 error = -EACCES;
300                 goto out_unlock;
301         }
302         if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
303                         !capable(CAP_SYS_RESOURCE)) {
304                 error = -ENOSPC;
305                 goto out_unlock;
306         }
307         ipc_ns->mq_queues_count++;
308         spin_unlock(&mq_lock);
309
310         inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
311         if (!inode) {
312                 error = -ENOMEM;
313                 spin_lock(&mq_lock);
314                 ipc_ns->mq_queues_count--;
315                 goto out_unlock;
316         }
317
318         put_ipc_ns(ipc_ns);
319         dir->i_size += DIRENT_SIZE;
320         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
321
322         d_instantiate(dentry, inode);
323         dget(dentry);
324         return 0;
325 out_unlock:
326         spin_unlock(&mq_lock);
327         if (ipc_ns)
328                 put_ipc_ns(ipc_ns);
329         return error;
330 }
331
332 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
333 {
334         struct inode *inode = dentry->d_inode;
335
336         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
337         dir->i_size -= DIRENT_SIZE;
338         drop_nlink(inode);
339         dput(dentry);
340         return 0;
341 }
342
343 /*
344 *       This is routine for system read from queue file.
345 *       To avoid mess with doing here some sort of mq_receive we allow
346 *       to read only queue size & notification info (the only values
347 *       that are interesting from user point of view and aren't accessible
348 *       through std routines)
349 */
350 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
351                                 size_t count, loff_t *off)
352 {
353         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
354         char buffer[FILENT_SIZE];
355         ssize_t ret;
356
357         spin_lock(&info->lock);
358         snprintf(buffer, sizeof(buffer),
359                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
360                         info->qsize,
361                         info->notify_owner ? info->notify.sigev_notify : 0,
362                         (info->notify_owner &&
363                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
364                                 info->notify.sigev_signo : 0,
365                         pid_vnr(info->notify_owner));
366         spin_unlock(&info->lock);
367         buffer[sizeof(buffer)-1] = '\0';
368
369         ret = simple_read_from_buffer(u_data, count, off, buffer,
370                                 strlen(buffer));
371         if (ret <= 0)
372                 return ret;
373
374         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
375         return ret;
376 }
377
378 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
379 {
380         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
381
382         spin_lock(&info->lock);
383         if (task_tgid(current) == info->notify_owner)
384                 remove_notification(info);
385
386         spin_unlock(&info->lock);
387         return 0;
388 }
389
390 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
391 {
392         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
393         int retval = 0;
394
395         poll_wait(filp, &info->wait_q, poll_tab);
396
397         spin_lock(&info->lock);
398         if (info->attr.mq_curmsgs)
399                 retval = POLLIN | POLLRDNORM;
400
401         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
402                 retval |= POLLOUT | POLLWRNORM;
403         spin_unlock(&info->lock);
404
405         return retval;
406 }
407
408 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
409 static void wq_add(struct mqueue_inode_info *info, int sr,
410                         struct ext_wait_queue *ewp)
411 {
412         struct ext_wait_queue *walk;
413
414         ewp->task = current;
415
416         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
417                 if (walk->task->static_prio <= current->static_prio) {
418                         list_add_tail(&ewp->list, &walk->list);
419                         return;
420                 }
421         }
422         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
423 }
424
425 /*
426  * Puts current task to sleep. Caller must hold queue lock. After return
427  * lock isn't held.
428  * sr: SEND or RECV
429  */
430 static int wq_sleep(struct mqueue_inode_info *info, int sr,
431                     ktime_t *timeout, struct ext_wait_queue *ewp)
432 {
433         int retval;
434         signed long time;
435
436         wq_add(info, sr, ewp);
437
438         for (;;) {
439                 set_current_state(TASK_INTERRUPTIBLE);
440
441                 spin_unlock(&info->lock);
442                 time = schedule_hrtimeout_range_clock(timeout,
443                     HRTIMER_MODE_ABS, 0, CLOCK_REALTIME);
444
445                 while (ewp->state == STATE_PENDING)
446                         cpu_relax();
447
448                 if (ewp->state == STATE_READY) {
449                         retval = 0;
450                         goto out;
451                 }
452                 spin_lock(&info->lock);
453                 if (ewp->state == STATE_READY) {
454                         retval = 0;
455                         goto out_unlock;
456                 }
457                 if (signal_pending(current)) {
458                         retval = -ERESTARTSYS;
459                         break;
460                 }
461                 if (time == 0) {
462                         retval = -ETIMEDOUT;
463                         break;
464                 }
465         }
466         list_del(&ewp->list);
467 out_unlock:
468         spin_unlock(&info->lock);
469 out:
470         return retval;
471 }
472
473 /*
474  * Returns waiting task that should be serviced first or NULL if none exists
475  */
476 static struct ext_wait_queue *wq_get_first_waiter(
477                 struct mqueue_inode_info *info, int sr)
478 {
479         struct list_head *ptr;
480
481         ptr = info->e_wait_q[sr].list.prev;
482         if (ptr == &info->e_wait_q[sr].list)
483                 return NULL;
484         return list_entry(ptr, struct ext_wait_queue, list);
485 }
486
487 /* Auxiliary functions to manipulate messages' list */
488 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
489 {
490         int k;
491
492         k = info->attr.mq_curmsgs - 1;
493         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
494                 info->messages[k + 1] = info->messages[k];
495                 k--;
496         }
497         info->attr.mq_curmsgs++;
498         info->qsize += ptr->m_ts;
499         info->messages[k + 1] = ptr;
500 }
501
502 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
503 {
504         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
505         return info->messages[info->attr.mq_curmsgs];
506 }
507
508 static inline void set_cookie(struct sk_buff *skb, char code)
509 {
510         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
511 }
512
513 /*
514  * The next function is only to split too long sys_mq_timedsend
515  */
516 static void __do_notify(struct mqueue_inode_info *info)
517 {
518         /* notification
519          * invoked when there is registered process and there isn't process
520          * waiting synchronously for message AND state of queue changed from
521          * empty to not empty. Here we are sure that no one is waiting
522          * synchronously. */
523         if (info->notify_owner &&
524             info->attr.mq_curmsgs == 1) {
525                 struct siginfo sig_i;
526                 switch (info->notify.sigev_notify) {
527                 case SIGEV_NONE:
528                         break;
529                 case SIGEV_SIGNAL:
530                         /* sends signal */
531
532                         sig_i.si_signo = info->notify.sigev_signo;
533                         sig_i.si_errno = 0;
534                         sig_i.si_code = SI_MESGQ;
535                         sig_i.si_value = info->notify.sigev_value;
536                         sig_i.si_pid = task_tgid_nr_ns(current,
537                                                 ns_of_pid(info->notify_owner));
538                         sig_i.si_uid = current_uid();
539
540                         kill_pid_info(info->notify.sigev_signo,
541                                       &sig_i, info->notify_owner);
542                         break;
543                 case SIGEV_THREAD:
544                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
545                         netlink_sendskb(info->notify_sock, info->notify_cookie);
546                         break;
547                 }
548                 /* after notification unregisters process */
549                 put_pid(info->notify_owner);
550                 info->notify_owner = NULL;
551         }
552         wake_up(&info->wait_q);
553 }
554
555 static int prepare_timeout(const struct timespec __user *u_abs_timeout,
556                            ktime_t *expires, struct timespec *ts)
557 {
558         if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
559                 return -EFAULT;
560         if (!timespec_valid(ts))
561                 return -EINVAL;
562
563         *expires = timespec_to_ktime(*ts);
564         return 0;
565 }
566
567 static void remove_notification(struct mqueue_inode_info *info)
568 {
569         if (info->notify_owner != NULL &&
570             info->notify.sigev_notify == SIGEV_THREAD) {
571                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
572                 netlink_sendskb(info->notify_sock, info->notify_cookie);
573         }
574         put_pid(info->notify_owner);
575         info->notify_owner = NULL;
576 }
577
578 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
579 {
580         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
581                 return 0;
582         if (capable(CAP_SYS_RESOURCE)) {
583                 if (attr->mq_maxmsg > HARD_MSGMAX)
584                         return 0;
585         } else {
586                 if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
587                                 attr->mq_msgsize > ipc_ns->mq_msgsize_max)
588                         return 0;
589         }
590         /* check for overflow */
591         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
592                 return 0;
593         if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
594             + sizeof (struct msg_msg *))) <
595             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
596                 return 0;
597         return 1;
598 }
599
600 /*
601  * Invoked when creating a new queue via sys_mq_open
602  */
603 static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
604                         struct dentry *dentry, int oflag, mode_t mode,
605                         struct mq_attr *attr)
606 {
607         const struct cred *cred = current_cred();
608         struct file *result;
609         int ret;
610
611         if (attr) {
612                 if (!mq_attr_ok(ipc_ns, attr)) {
613                         ret = -EINVAL;
614                         goto out;
615                 }
616                 /* store for use during create */
617                 dentry->d_fsdata = attr;
618         }
619
620         mode &= ~current_umask();
621         ret = mnt_want_write(ipc_ns->mq_mnt);
622         if (ret)
623                 goto out;
624         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
625         dentry->d_fsdata = NULL;
626         if (ret)
627                 goto out_drop_write;
628
629         result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
630         /*
631          * dentry_open() took a persistent mnt_want_write(),
632          * so we can now drop this one.
633          */
634         mnt_drop_write(ipc_ns->mq_mnt);
635         return result;
636
637 out_drop_write:
638         mnt_drop_write(ipc_ns->mq_mnt);
639 out:
640         dput(dentry);
641         mntput(ipc_ns->mq_mnt);
642         return ERR_PTR(ret);
643 }
644
645 /* Opens existing queue */
646 static struct file *do_open(struct ipc_namespace *ipc_ns,
647                                 struct dentry *dentry, int oflag)
648 {
649         int ret;
650         const struct cred *cred = current_cred();
651
652         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
653                                                   MAY_READ | MAY_WRITE };
654
655         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
656                 ret = -EINVAL;
657                 goto err;
658         }
659
660         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
661                 ret = -EACCES;
662                 goto err;
663         }
664
665         return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
666
667 err:
668         dput(dentry);
669         mntput(ipc_ns->mq_mnt);
670         return ERR_PTR(ret);
671 }
672
673 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
674                 struct mq_attr __user *, u_attr)
675 {
676         struct dentry *dentry;
677         struct file *filp;
678         char *name;
679         struct mq_attr attr;
680         int fd, error;
681         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
682
683         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
684                 return -EFAULT;
685
686         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
687
688         if (IS_ERR(name = getname(u_name)))
689                 return PTR_ERR(name);
690
691         fd = get_unused_fd_flags(O_CLOEXEC);
692         if (fd < 0)
693                 goto out_putname;
694
695         mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
696         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
697         if (IS_ERR(dentry)) {
698                 error = PTR_ERR(dentry);
699                 goto out_putfd;
700         }
701         mntget(ipc_ns->mq_mnt);
702
703         if (oflag & O_CREAT) {
704                 if (dentry->d_inode) {  /* entry already exists */
705                         audit_inode(name, dentry);
706                         if (oflag & O_EXCL) {
707                                 error = -EEXIST;
708                                 goto out;
709                         }
710                         filp = do_open(ipc_ns, dentry, oflag);
711                 } else {
712                         filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
713                                                 dentry, oflag, mode,
714                                                 u_attr ? &attr : NULL);
715                 }
716         } else {
717                 if (!dentry->d_inode) {
718                         error = -ENOENT;
719                         goto out;
720                 }
721                 audit_inode(name, dentry);
722                 filp = do_open(ipc_ns, dentry, oflag);
723         }
724
725         if (IS_ERR(filp)) {
726                 error = PTR_ERR(filp);
727                 goto out_putfd;
728         }
729
730         fd_install(fd, filp);
731         goto out_upsem;
732
733 out:
734         dput(dentry);
735         mntput(ipc_ns->mq_mnt);
736 out_putfd:
737         put_unused_fd(fd);
738         fd = error;
739 out_upsem:
740         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
741 out_putname:
742         putname(name);
743         return fd;
744 }
745
746 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
747 {
748         int err;
749         char *name;
750         struct dentry *dentry;
751         struct inode *inode = NULL;
752         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
753
754         name = getname(u_name);
755         if (IS_ERR(name))
756                 return PTR_ERR(name);
757
758         mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
759                         I_MUTEX_PARENT);
760         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
761         if (IS_ERR(dentry)) {
762                 err = PTR_ERR(dentry);
763                 goto out_unlock;
764         }
765
766         if (!dentry->d_inode) {
767                 err = -ENOENT;
768                 goto out_err;
769         }
770
771         inode = dentry->d_inode;
772         if (inode)
773                 ihold(inode);
774         err = mnt_want_write(ipc_ns->mq_mnt);
775         if (err)
776                 goto out_err;
777         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
778         mnt_drop_write(ipc_ns->mq_mnt);
779 out_err:
780         dput(dentry);
781
782 out_unlock:
783         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
784         putname(name);
785         if (inode)
786                 iput(inode);
787
788         return err;
789 }
790
791 /* Pipelined send and receive functions.
792  *
793  * If a receiver finds no waiting message, then it registers itself in the
794  * list of waiting receivers. A sender checks that list before adding the new
795  * message into the message array. If there is a waiting receiver, then it
796  * bypasses the message array and directly hands the message over to the
797  * receiver.
798  * The receiver accepts the message and returns without grabbing the queue
799  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
800  * are necessary. The same algorithm is used for sysv semaphores, see
801  * ipc/sem.c for more details.
802  *
803  * The same algorithm is used for senders.
804  */
805
806 /* pipelined_send() - send a message directly to the task waiting in
807  * sys_mq_timedreceive() (without inserting message into a queue).
808  */
809 static inline void pipelined_send(struct mqueue_inode_info *info,
810                                   struct msg_msg *message,
811                                   struct ext_wait_queue *receiver)
812 {
813         receiver->msg = message;
814         list_del(&receiver->list);
815         receiver->state = STATE_PENDING;
816         wake_up_process(receiver->task);
817         smp_wmb();
818         receiver->state = STATE_READY;
819 }
820
821 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
822  * gets its message and put to the queue (we have one free place for sure). */
823 static inline void pipelined_receive(struct mqueue_inode_info *info)
824 {
825         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
826
827         if (!sender) {
828                 /* for poll */
829                 wake_up_interruptible(&info->wait_q);
830                 return;
831         }
832         msg_insert(sender->msg, info);
833         list_del(&sender->list);
834         sender->state = STATE_PENDING;
835         wake_up_process(sender->task);
836         smp_wmb();
837         sender->state = STATE_READY;
838 }
839
840 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
841                 size_t, msg_len, unsigned int, msg_prio,
842                 const struct timespec __user *, u_abs_timeout)
843 {
844         struct file *filp;
845         struct inode *inode;
846         struct ext_wait_queue wait;
847         struct ext_wait_queue *receiver;
848         struct msg_msg *msg_ptr;
849         struct mqueue_inode_info *info;
850         ktime_t expires, *timeout = NULL;
851         struct timespec ts;
852         int ret;
853
854         if (u_abs_timeout) {
855                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
856                 if (res)
857                         return res;
858                 timeout = &expires;
859         }
860
861         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
862                 return -EINVAL;
863
864         audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
865
866         filp = fget(mqdes);
867         if (unlikely(!filp)) {
868                 ret = -EBADF;
869                 goto out;
870         }
871
872         inode = filp->f_path.dentry->d_inode;
873         if (unlikely(filp->f_op != &mqueue_file_operations)) {
874                 ret = -EBADF;
875                 goto out_fput;
876         }
877         info = MQUEUE_I(inode);
878         audit_inode(NULL, filp->f_path.dentry);
879
880         if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
881                 ret = -EBADF;
882                 goto out_fput;
883         }
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 {
907                         wait.task = current;
908                         wait.msg = (void *) msg_ptr;
909                         wait.state = STATE_NONE;
910                         ret = wq_sleep(info, SEND, timeout, &wait);
911                 }
912                 if (ret < 0)
913                         free_msg(msg_ptr);
914         } else {
915                 receiver = wq_get_first_waiter(info, RECV);
916                 if (receiver) {
917                         pipelined_send(info, msg_ptr, receiver);
918                 } else {
919                         /* adds message to the queue */
920                         msg_insert(msg_ptr, info);
921                         __do_notify(info);
922                 }
923                 inode->i_atime = inode->i_mtime = inode->i_ctime =
924                                 CURRENT_TIME;
925                 spin_unlock(&info->lock);
926                 ret = 0;
927         }
928 out_fput:
929         fput(filp);
930 out:
931         return ret;
932 }
933
934 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
935                 size_t, msg_len, unsigned int __user *, u_msg_prio,
936                 const struct timespec __user *, u_abs_timeout)
937 {
938         ssize_t ret;
939         struct msg_msg *msg_ptr;
940         struct file *filp;
941         struct inode *inode;
942         struct mqueue_inode_info *info;
943         struct ext_wait_queue wait;
944         ktime_t expires, *timeout = NULL;
945         struct timespec ts;
946
947         if (u_abs_timeout) {
948                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
949                 if (res)
950                         return res;
951                 timeout = &expires;
952         }
953
954         audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
955
956         filp = fget(mqdes);
957         if (unlikely(!filp)) {
958                 ret = -EBADF;
959                 goto out;
960         }
961
962         inode = filp->f_path.dentry->d_inode;
963         if (unlikely(filp->f_op != &mqueue_file_operations)) {
964                 ret = -EBADF;
965                 goto out_fput;
966         }
967         info = MQUEUE_I(inode);
968         audit_inode(NULL, filp->f_path.dentry);
969
970         if (unlikely(!(filp->f_mode & FMODE_READ))) {
971                 ret = -EBADF;
972                 goto out_fput;
973         }
974
975         /* checks if buffer is big enough */
976         if (unlikely(msg_len < info->attr.mq_msgsize)) {
977                 ret = -EMSGSIZE;
978                 goto out_fput;
979         }
980
981         spin_lock(&info->lock);
982         if (info->attr.mq_curmsgs == 0) {
983                 if (filp->f_flags & O_NONBLOCK) {
984                         spin_unlock(&info->lock);
985                         ret = -EAGAIN;
986                 } else {
987                         wait.task = current;
988                         wait.state = STATE_NONE;
989                         ret = wq_sleep(info, RECV, timeout, &wait);
990                         msg_ptr = wait.msg;
991                 }
992         } else {
993                 msg_ptr = msg_get(info);
994
995                 inode->i_atime = inode->i_mtime = inode->i_ctime =
996                                 CURRENT_TIME;
997
998                 /* There is now free space in queue. */
999                 pipelined_receive(info);
1000                 spin_unlock(&info->lock);
1001                 ret = 0;
1002         }
1003         if (ret == 0) {
1004                 ret = msg_ptr->m_ts;
1005
1006                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1007                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1008                         ret = -EFAULT;
1009                 }
1010                 free_msg(msg_ptr);
1011         }
1012 out_fput:
1013         fput(filp);
1014 out:
1015         return ret;
1016 }
1017
1018 /*
1019  * Notes: the case when user wants us to deregister (with NULL as pointer)
1020  * and he isn't currently owner of notification, will be silently discarded.
1021  * It isn't explicitly defined in the POSIX.
1022  */
1023 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1024                 const struct sigevent __user *, u_notification)
1025 {
1026         int ret;
1027         struct file *filp;
1028         struct sock *sock;
1029         struct inode *inode;
1030         struct sigevent notification;
1031         struct mqueue_inode_info *info;
1032         struct sk_buff *nc;
1033
1034         if (u_notification) {
1035                 if (copy_from_user(&notification, u_notification,
1036                                         sizeof(struct sigevent)))
1037                         return -EFAULT;
1038         }
1039
1040         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1041
1042         nc = NULL;
1043         sock = NULL;
1044         if (u_notification != NULL) {
1045                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1046                              notification.sigev_notify != SIGEV_SIGNAL &&
1047                              notification.sigev_notify != SIGEV_THREAD))
1048                         return -EINVAL;
1049                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1050                         !valid_signal(notification.sigev_signo)) {
1051                         return -EINVAL;
1052                 }
1053                 if (notification.sigev_notify == SIGEV_THREAD) {
1054                         long timeo;
1055
1056                         /* create the notify skb */
1057                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1058                         if (!nc) {
1059                                 ret = -ENOMEM;
1060                                 goto out;
1061                         }
1062                         if (copy_from_user(nc->data,
1063                                         notification.sigev_value.sival_ptr,
1064                                         NOTIFY_COOKIE_LEN)) {
1065                                 ret = -EFAULT;
1066                                 goto out;
1067                         }
1068
1069                         /* TODO: add a header? */
1070                         skb_put(nc, NOTIFY_COOKIE_LEN);
1071                         /* and attach it to the socket */
1072 retry:
1073                         filp = fget(notification.sigev_signo);
1074                         if (!filp) {
1075                                 ret = -EBADF;
1076                                 goto out;
1077                         }
1078                         sock = netlink_getsockbyfilp(filp);
1079                         fput(filp);
1080                         if (IS_ERR(sock)) {
1081                                 ret = PTR_ERR(sock);
1082                                 sock = NULL;
1083                                 goto out;
1084                         }
1085
1086                         timeo = MAX_SCHEDULE_TIMEOUT;
1087                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1088                         if (ret == 1)
1089                                 goto retry;
1090                         if (ret) {
1091                                 sock = NULL;
1092                                 nc = NULL;
1093                                 goto out;
1094                         }
1095                 }
1096         }
1097
1098         filp = fget(mqdes);
1099         if (!filp) {
1100                 ret = -EBADF;
1101                 goto out;
1102         }
1103
1104         inode = filp->f_path.dentry->d_inode;
1105         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1106                 ret = -EBADF;
1107                 goto out_fput;
1108         }
1109         info = MQUEUE_I(inode);
1110
1111         ret = 0;
1112         spin_lock(&info->lock);
1113         if (u_notification == NULL) {
1114                 if (info->notify_owner == task_tgid(current)) {
1115                         remove_notification(info);
1116                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1117                 }
1118         } else if (info->notify_owner != NULL) {
1119                 ret = -EBUSY;
1120         } else {
1121                 switch (notification.sigev_notify) {
1122                 case SIGEV_NONE:
1123                         info->notify.sigev_notify = SIGEV_NONE;
1124                         break;
1125                 case SIGEV_THREAD:
1126                         info->notify_sock = sock;
1127                         info->notify_cookie = nc;
1128                         sock = NULL;
1129                         nc = NULL;
1130                         info->notify.sigev_notify = SIGEV_THREAD;
1131                         break;
1132                 case SIGEV_SIGNAL:
1133                         info->notify.sigev_signo = notification.sigev_signo;
1134                         info->notify.sigev_value = notification.sigev_value;
1135                         info->notify.sigev_notify = SIGEV_SIGNAL;
1136                         break;
1137                 }
1138
1139                 info->notify_owner = get_pid(task_tgid(current));
1140                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1141         }
1142         spin_unlock(&info->lock);
1143 out_fput:
1144         fput(filp);
1145 out:
1146         if (sock) {
1147                 netlink_detachskb(sock, nc);
1148         } else if (nc) {
1149                 dev_kfree_skb(nc);
1150         }
1151         return ret;
1152 }
1153
1154 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1155                 const struct mq_attr __user *, u_mqstat,
1156                 struct mq_attr __user *, u_omqstat)
1157 {
1158         int ret;
1159         struct mq_attr mqstat, omqstat;
1160         struct file *filp;
1161         struct inode *inode;
1162         struct mqueue_inode_info *info;
1163
1164         if (u_mqstat != NULL) {
1165                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1166                         return -EFAULT;
1167                 if (mqstat.mq_flags & (~O_NONBLOCK))
1168                         return -EINVAL;
1169         }
1170
1171         filp = fget(mqdes);
1172         if (!filp) {
1173                 ret = -EBADF;
1174                 goto out;
1175         }
1176
1177         inode = filp->f_path.dentry->d_inode;
1178         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1179                 ret = -EBADF;
1180                 goto out_fput;
1181         }
1182         info = MQUEUE_I(inode);
1183
1184         spin_lock(&info->lock);
1185
1186         omqstat = info->attr;
1187         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1188         if (u_mqstat) {
1189                 audit_mq_getsetattr(mqdes, &mqstat);
1190                 spin_lock(&filp->f_lock);
1191                 if (mqstat.mq_flags & O_NONBLOCK)
1192                         filp->f_flags |= O_NONBLOCK;
1193                 else
1194                         filp->f_flags &= ~O_NONBLOCK;
1195                 spin_unlock(&filp->f_lock);
1196
1197                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1198         }
1199
1200         spin_unlock(&info->lock);
1201
1202         ret = 0;
1203         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1204                                                 sizeof(struct mq_attr)))
1205                 ret = -EFAULT;
1206
1207 out_fput:
1208         fput(filp);
1209 out:
1210         return ret;
1211 }
1212
1213 static const struct inode_operations mqueue_dir_inode_operations = {
1214         .lookup = simple_lookup,
1215         .create = mqueue_create,
1216         .unlink = mqueue_unlink,
1217 };
1218
1219 static const struct file_operations mqueue_file_operations = {
1220         .flush = mqueue_flush_file,
1221         .poll = mqueue_poll_file,
1222         .read = mqueue_read_file,
1223         .llseek = default_llseek,
1224 };
1225
1226 static const struct super_operations mqueue_super_ops = {
1227         .alloc_inode = mqueue_alloc_inode,
1228         .destroy_inode = mqueue_destroy_inode,
1229         .evict_inode = mqueue_evict_inode,
1230         .statfs = simple_statfs,
1231 };
1232
1233 static struct file_system_type mqueue_fs_type = {
1234         .name = "mqueue",
1235         .mount = mqueue_mount,
1236         .kill_sb = kill_litter_super,
1237 };
1238
1239 int mq_init_ns(struct ipc_namespace *ns)
1240 {
1241         ns->mq_queues_count  = 0;
1242         ns->mq_queues_max    = DFLT_QUEUESMAX;
1243         ns->mq_msg_max       = DFLT_MSGMAX;
1244         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1245
1246         ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1247         if (IS_ERR(ns->mq_mnt)) {
1248                 int err = PTR_ERR(ns->mq_mnt);
1249                 ns->mq_mnt = NULL;
1250                 return err;
1251         }
1252         return 0;
1253 }
1254
1255 void mq_clear_sbinfo(struct ipc_namespace *ns)
1256 {
1257         ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1258 }
1259
1260 void mq_put_mnt(struct ipc_namespace *ns)
1261 {
1262         mntput(ns->mq_mnt);
1263 }
1264
1265 static int __init init_mqueue_fs(void)
1266 {
1267         int error;
1268
1269         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1270                                 sizeof(struct mqueue_inode_info), 0,
1271                                 SLAB_HWCACHE_ALIGN, init_once);
1272         if (mqueue_inode_cachep == NULL)
1273                 return -ENOMEM;
1274
1275         /* ignore failures - they are not fatal */
1276         mq_sysctl_table = mq_register_sysctl_table();
1277
1278         error = register_filesystem(&mqueue_fs_type);
1279         if (error)
1280                 goto out_sysctl;
1281
1282         spin_lock_init(&mq_lock);
1283
1284         init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns);
1285         if (IS_ERR(init_ipc_ns.mq_mnt)) {
1286                 error = PTR_ERR(init_ipc_ns.mq_mnt);
1287                 goto out_filesystem;
1288         }
1289
1290         return 0;
1291
1292 out_filesystem:
1293         unregister_filesystem(&mqueue_fs_type);
1294 out_sysctl:
1295         if (mq_sysctl_table)
1296                 unregister_sysctl_table(mq_sysctl_table);
1297         kmem_cache_destroy(mqueue_inode_cachep);
1298         return error;
1299 }
1300
1301 __initcall(init_mqueue_fs);