Merge branch 'next' of git://git.monstr.eu/linux-2.6-microblaze
[linux-3.10.git] / ipc / mqueue.c
1 /*
2  * POSIX message queues filesystem for Linux.
3  *
4  * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
5  *                          Michal Wronski          (michal.wronski@gmail.com)
6  *
7  * Spinlocks:               Mohamed Abbas           (abbas.mohamed@intel.com)
8  * Lockless receive & send, fd based notify:
9  *                          Manfred Spraul          (manfred@colorfullife.com)
10  *
11  * Audit:                   George Wilson           (ltcgcw@us.ibm.com)
12  *
13  * This file is released under the GPL.
14  */
15
16 #include <linux/capability.h>
17 #include <linux/init.h>
18 #include <linux/pagemap.h>
19 #include <linux/file.h>
20 #include <linux/mount.h>
21 #include <linux/namei.h>
22 #include <linux/sysctl.h>
23 #include <linux/poll.h>
24 #include <linux/mqueue.h>
25 #include <linux/msg.h>
26 #include <linux/skbuff.h>
27 #include <linux/netlink.h>
28 #include <linux/syscalls.h>
29 #include <linux/audit.h>
30 #include <linux/signal.h>
31 #include <linux/mutex.h>
32 #include <linux/nsproxy.h>
33 #include <linux/pid.h>
34 #include <linux/ipc_namespace.h>
35 #include <linux/user_namespace.h>
36 #include <linux/slab.h>
37
38 #include <net/sock.h>
39 #include "util.h"
40
41 #define MQUEUE_MAGIC    0x19800202
42 #define DIRENT_SIZE     20
43 #define FILENT_SIZE     80
44
45 #define SEND            0
46 #define RECV            1
47
48 #define STATE_NONE      0
49 #define STATE_PENDING   1
50 #define STATE_READY     2
51
52 struct ext_wait_queue {         /* queue of sleeping tasks */
53         struct task_struct *task;
54         struct list_head list;
55         struct msg_msg *msg;    /* ptr of loaded message */
56         int state;              /* one of STATE_* values */
57 };
58
59 struct mqueue_inode_info {
60         spinlock_t lock;
61         struct inode vfs_inode;
62         wait_queue_head_t wait_q;
63
64         struct msg_msg **messages;
65         struct mq_attr attr;
66
67         struct sigevent notify;
68         struct pid* notify_owner;
69         struct user_namespace *notify_user_ns;
70         struct user_struct *user;       /* user who created, for accounting */
71         struct sock *notify_sock;
72         struct sk_buff *notify_cookie;
73
74         /* for tasks waiting for free space and messages, respectively */
75         struct ext_wait_queue e_wait_q[2];
76
77         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
78 };
79
80 static const struct inode_operations mqueue_dir_inode_operations;
81 static const struct file_operations mqueue_file_operations;
82 static const struct super_operations mqueue_super_ops;
83 static void remove_notification(struct mqueue_inode_info *info);
84
85 static struct kmem_cache *mqueue_inode_cachep;
86
87 static struct ctl_table_header * mq_sysctl_table;
88
89 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
90 {
91         return container_of(inode, struct mqueue_inode_info, vfs_inode);
92 }
93
94 /*
95  * This routine should be called with the mq_lock held.
96  */
97 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
98 {
99         return get_ipc_ns(inode->i_sb->s_fs_info);
100 }
101
102 static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
103 {
104         struct ipc_namespace *ns;
105
106         spin_lock(&mq_lock);
107         ns = __get_ns_from_inode(inode);
108         spin_unlock(&mq_lock);
109         return ns;
110 }
111
112 static struct inode *mqueue_get_inode(struct super_block *sb,
113                 struct ipc_namespace *ipc_ns, umode_t mode,
114                 struct mq_attr *attr)
115 {
116         struct user_struct *u = current_user();
117         struct inode *inode;
118         int ret = -ENOMEM;
119
120         inode = new_inode(sb);
121         if (!inode)
122                 goto err;
123
124         inode->i_ino = get_next_ino();
125         inode->i_mode = mode;
126         inode->i_uid = current_fsuid();
127         inode->i_gid = current_fsgid();
128         inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
129
130         if (S_ISREG(mode)) {
131                 struct mqueue_inode_info *info;
132                 unsigned long mq_bytes, mq_msg_tblsz;
133
134                 inode->i_fop = &mqueue_file_operations;
135                 inode->i_size = FILENT_SIZE;
136                 /* mqueue specific info */
137                 info = MQUEUE_I(inode);
138                 spin_lock_init(&info->lock);
139                 init_waitqueue_head(&info->wait_q);
140                 INIT_LIST_HEAD(&info->e_wait_q[0].list);
141                 INIT_LIST_HEAD(&info->e_wait_q[1].list);
142                 info->notify_owner = NULL;
143                 info->notify_user_ns = NULL;
144                 info->qsize = 0;
145                 info->user = NULL;      /* set when all is ok */
146                 memset(&info->attr, 0, sizeof(info->attr));
147                 info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
148                 info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
149                 if (attr) {
150                         info->attr.mq_maxmsg = attr->mq_maxmsg;
151                         info->attr.mq_msgsize = attr->mq_msgsize;
152                 }
153                 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
154                 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
155                 if (!info->messages)
156                         goto out_inode;
157
158                 mq_bytes = (mq_msg_tblsz +
159                         (info->attr.mq_maxmsg * info->attr.mq_msgsize));
160
161                 spin_lock(&mq_lock);
162                 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
163                     u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
164                         spin_unlock(&mq_lock);
165                         /* mqueue_evict_inode() releases info->messages */
166                         ret = -EMFILE;
167                         goto out_inode;
168                 }
169                 u->mq_bytes += mq_bytes;
170                 spin_unlock(&mq_lock);
171
172                 /* all is ok */
173                 info->user = get_uid(u);
174         } else if (S_ISDIR(mode)) {
175                 inc_nlink(inode);
176                 /* Some things misbehave if size == 0 on a directory */
177                 inode->i_size = 2 * DIRENT_SIZE;
178                 inode->i_op = &mqueue_dir_inode_operations;
179                 inode->i_fop = &simple_dir_operations;
180         }
181
182         return inode;
183 out_inode:
184         iput(inode);
185 err:
186         return ERR_PTR(ret);
187 }
188
189 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
190 {
191         struct inode *inode;
192         struct ipc_namespace *ns = data;
193
194         sb->s_blocksize = PAGE_CACHE_SIZE;
195         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
196         sb->s_magic = MQUEUE_MAGIC;
197         sb->s_op = &mqueue_super_ops;
198
199         inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
200         if (IS_ERR(inode))
201                 return PTR_ERR(inode);
202
203         sb->s_root = d_make_root(inode);
204         if (!sb->s_root)
205                 return -ENOMEM;
206         return 0;
207 }
208
209 static struct dentry *mqueue_mount(struct file_system_type *fs_type,
210                          int flags, const char *dev_name,
211                          void *data)
212 {
213         if (!(flags & MS_KERNMOUNT))
214                 data = current->nsproxy->ipc_ns;
215         return mount_ns(fs_type, flags, data, mqueue_fill_super);
216 }
217
218 static void init_once(void *foo)
219 {
220         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
221
222         inode_init_once(&p->vfs_inode);
223 }
224
225 static struct inode *mqueue_alloc_inode(struct super_block *sb)
226 {
227         struct mqueue_inode_info *ei;
228
229         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
230         if (!ei)
231                 return NULL;
232         return &ei->vfs_inode;
233 }
234
235 static void mqueue_i_callback(struct rcu_head *head)
236 {
237         struct inode *inode = container_of(head, struct inode, i_rcu);
238         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
239 }
240
241 static void mqueue_destroy_inode(struct inode *inode)
242 {
243         call_rcu(&inode->i_rcu, mqueue_i_callback);
244 }
245
246 static void mqueue_evict_inode(struct inode *inode)
247 {
248         struct mqueue_inode_info *info;
249         struct user_struct *user;
250         unsigned long mq_bytes;
251         int i;
252         struct ipc_namespace *ipc_ns;
253
254         end_writeback(inode);
255
256         if (S_ISDIR(inode->i_mode))
257                 return;
258
259         ipc_ns = get_ns_from_inode(inode);
260         info = MQUEUE_I(inode);
261         spin_lock(&info->lock);
262         for (i = 0; i < info->attr.mq_curmsgs; i++)
263                 free_msg(info->messages[i]);
264         kfree(info->messages);
265         spin_unlock(&info->lock);
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                                 umode_t 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 (IS_ERR(inode)) {
313                 error = PTR_ERR(inode);
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, 0,
444                         HRTIMER_MODE_ABS, 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                         /* map current pid/uid into info->owner's namespaces */
538                         rcu_read_lock();
539                         sig_i.si_pid = task_tgid_nr_ns(current,
540                                                 ns_of_pid(info->notify_owner));
541                         sig_i.si_uid = from_kuid_munged(info->notify_user_ns, current_uid());
542                         rcu_read_unlock();
543
544                         kill_pid_info(info->notify.sigev_signo,
545                                       &sig_i, info->notify_owner);
546                         break;
547                 case SIGEV_THREAD:
548                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
549                         netlink_sendskb(info->notify_sock, info->notify_cookie);
550                         break;
551                 }
552                 /* after notification unregisters process */
553                 put_pid(info->notify_owner);
554                 put_user_ns(info->notify_user_ns);
555                 info->notify_owner = NULL;
556                 info->notify_user_ns = NULL;
557         }
558         wake_up(&info->wait_q);
559 }
560
561 static int prepare_timeout(const struct timespec __user *u_abs_timeout,
562                            ktime_t *expires, struct timespec *ts)
563 {
564         if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
565                 return -EFAULT;
566         if (!timespec_valid(ts))
567                 return -EINVAL;
568
569         *expires = timespec_to_ktime(*ts);
570         return 0;
571 }
572
573 static void remove_notification(struct mqueue_inode_info *info)
574 {
575         if (info->notify_owner != NULL &&
576             info->notify.sigev_notify == SIGEV_THREAD) {
577                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
578                 netlink_sendskb(info->notify_sock, info->notify_cookie);
579         }
580         put_pid(info->notify_owner);
581         put_user_ns(info->notify_user_ns);
582         info->notify_owner = NULL;
583         info->notify_user_ns = NULL;
584 }
585
586 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
587 {
588         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
589                 return 0;
590         if (capable(CAP_SYS_RESOURCE)) {
591                 if (attr->mq_maxmsg > HARD_MSGMAX)
592                         return 0;
593         } else {
594                 if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
595                                 attr->mq_msgsize > ipc_ns->mq_msgsize_max)
596                         return 0;
597         }
598         /* check for overflow */
599         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
600                 return 0;
601         if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
602             + sizeof (struct msg_msg *))) <
603             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
604                 return 0;
605         return 1;
606 }
607
608 /*
609  * Invoked when creating a new queue via sys_mq_open
610  */
611 static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
612                         struct dentry *dentry, int oflag, umode_t mode,
613                         struct mq_attr *attr)
614 {
615         const struct cred *cred = current_cred();
616         struct file *result;
617         int ret;
618
619         if (attr) {
620                 if (!mq_attr_ok(ipc_ns, attr)) {
621                         ret = -EINVAL;
622                         goto out;
623                 }
624                 /* store for use during create */
625                 dentry->d_fsdata = attr;
626         }
627
628         mode &= ~current_umask();
629         ret = mnt_want_write(ipc_ns->mq_mnt);
630         if (ret)
631                 goto out;
632         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
633         dentry->d_fsdata = NULL;
634         if (ret)
635                 goto out_drop_write;
636
637         result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
638         /*
639          * dentry_open() took a persistent mnt_want_write(),
640          * so we can now drop this one.
641          */
642         mnt_drop_write(ipc_ns->mq_mnt);
643         return result;
644
645 out_drop_write:
646         mnt_drop_write(ipc_ns->mq_mnt);
647 out:
648         dput(dentry);
649         mntput(ipc_ns->mq_mnt);
650         return ERR_PTR(ret);
651 }
652
653 /* Opens existing queue */
654 static struct file *do_open(struct ipc_namespace *ipc_ns,
655                                 struct dentry *dentry, int oflag)
656 {
657         int ret;
658         const struct cred *cred = current_cred();
659
660         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
661                                                   MAY_READ | MAY_WRITE };
662
663         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
664                 ret = -EINVAL;
665                 goto err;
666         }
667
668         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
669                 ret = -EACCES;
670                 goto err;
671         }
672
673         return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
674
675 err:
676         dput(dentry);
677         mntput(ipc_ns->mq_mnt);
678         return ERR_PTR(ret);
679 }
680
681 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
682                 struct mq_attr __user *, u_attr)
683 {
684         struct dentry *dentry;
685         struct file *filp;
686         char *name;
687         struct mq_attr attr;
688         int fd, error;
689         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
690
691         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
692                 return -EFAULT;
693
694         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
695
696         if (IS_ERR(name = getname(u_name)))
697                 return PTR_ERR(name);
698
699         fd = get_unused_fd_flags(O_CLOEXEC);
700         if (fd < 0)
701                 goto out_putname;
702
703         mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
704         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
705         if (IS_ERR(dentry)) {
706                 error = PTR_ERR(dentry);
707                 goto out_putfd;
708         }
709         mntget(ipc_ns->mq_mnt);
710
711         if (oflag & O_CREAT) {
712                 if (dentry->d_inode) {  /* entry already exists */
713                         audit_inode(name, dentry);
714                         if (oflag & O_EXCL) {
715                                 error = -EEXIST;
716                                 goto out;
717                         }
718                         filp = do_open(ipc_ns, dentry, oflag);
719                 } else {
720                         filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
721                                                 dentry, oflag, mode,
722                                                 u_attr ? &attr : NULL);
723                 }
724         } else {
725                 if (!dentry->d_inode) {
726                         error = -ENOENT;
727                         goto out;
728                 }
729                 audit_inode(name, dentry);
730                 filp = do_open(ipc_ns, dentry, oflag);
731         }
732
733         if (IS_ERR(filp)) {
734                 error = PTR_ERR(filp);
735                 goto out_putfd;
736         }
737
738         fd_install(fd, filp);
739         goto out_upsem;
740
741 out:
742         dput(dentry);
743         mntput(ipc_ns->mq_mnt);
744 out_putfd:
745         put_unused_fd(fd);
746         fd = error;
747 out_upsem:
748         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
749 out_putname:
750         putname(name);
751         return fd;
752 }
753
754 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
755 {
756         int err;
757         char *name;
758         struct dentry *dentry;
759         struct inode *inode = NULL;
760         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
761
762         name = getname(u_name);
763         if (IS_ERR(name))
764                 return PTR_ERR(name);
765
766         mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
767                         I_MUTEX_PARENT);
768         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
769         if (IS_ERR(dentry)) {
770                 err = PTR_ERR(dentry);
771                 goto out_unlock;
772         }
773
774         if (!dentry->d_inode) {
775                 err = -ENOENT;
776                 goto out_err;
777         }
778
779         inode = dentry->d_inode;
780         if (inode)
781                 ihold(inode);
782         err = mnt_want_write(ipc_ns->mq_mnt);
783         if (err)
784                 goto out_err;
785         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
786         mnt_drop_write(ipc_ns->mq_mnt);
787 out_err:
788         dput(dentry);
789
790 out_unlock:
791         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
792         putname(name);
793         if (inode)
794                 iput(inode);
795
796         return err;
797 }
798
799 /* Pipelined send and receive functions.
800  *
801  * If a receiver finds no waiting message, then it registers itself in the
802  * list of waiting receivers. A sender checks that list before adding the new
803  * message into the message array. If there is a waiting receiver, then it
804  * bypasses the message array and directly hands the message over to the
805  * receiver.
806  * The receiver accepts the message and returns without grabbing the queue
807  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
808  * are necessary. The same algorithm is used for sysv semaphores, see
809  * ipc/sem.c for more details.
810  *
811  * The same algorithm is used for senders.
812  */
813
814 /* pipelined_send() - send a message directly to the task waiting in
815  * sys_mq_timedreceive() (without inserting message into a queue).
816  */
817 static inline void pipelined_send(struct mqueue_inode_info *info,
818                                   struct msg_msg *message,
819                                   struct ext_wait_queue *receiver)
820 {
821         receiver->msg = message;
822         list_del(&receiver->list);
823         receiver->state = STATE_PENDING;
824         wake_up_process(receiver->task);
825         smp_wmb();
826         receiver->state = STATE_READY;
827 }
828
829 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
830  * gets its message and put to the queue (we have one free place for sure). */
831 static inline void pipelined_receive(struct mqueue_inode_info *info)
832 {
833         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
834
835         if (!sender) {
836                 /* for poll */
837                 wake_up_interruptible(&info->wait_q);
838                 return;
839         }
840         msg_insert(sender->msg, info);
841         list_del(&sender->list);
842         sender->state = STATE_PENDING;
843         wake_up_process(sender->task);
844         smp_wmb();
845         sender->state = STATE_READY;
846 }
847
848 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
849                 size_t, msg_len, unsigned int, msg_prio,
850                 const struct timespec __user *, u_abs_timeout)
851 {
852         struct file *filp;
853         struct inode *inode;
854         struct ext_wait_queue wait;
855         struct ext_wait_queue *receiver;
856         struct msg_msg *msg_ptr;
857         struct mqueue_inode_info *info;
858         ktime_t expires, *timeout = NULL;
859         struct timespec ts;
860         int ret;
861
862         if (u_abs_timeout) {
863                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
864                 if (res)
865                         return res;
866                 timeout = &expires;
867         }
868
869         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
870                 return -EINVAL;
871
872         audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
873
874         filp = fget(mqdes);
875         if (unlikely(!filp)) {
876                 ret = -EBADF;
877                 goto out;
878         }
879
880         inode = filp->f_path.dentry->d_inode;
881         if (unlikely(filp->f_op != &mqueue_file_operations)) {
882                 ret = -EBADF;
883                 goto out_fput;
884         }
885         info = MQUEUE_I(inode);
886         audit_inode(NULL, filp->f_path.dentry);
887
888         if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
889                 ret = -EBADF;
890                 goto out_fput;
891         }
892
893         if (unlikely(msg_len > info->attr.mq_msgsize)) {
894                 ret = -EMSGSIZE;
895                 goto out_fput;
896         }
897
898         /* First try to allocate memory, before doing anything with
899          * existing queues. */
900         msg_ptr = load_msg(u_msg_ptr, msg_len);
901         if (IS_ERR(msg_ptr)) {
902                 ret = PTR_ERR(msg_ptr);
903                 goto out_fput;
904         }
905         msg_ptr->m_ts = msg_len;
906         msg_ptr->m_type = msg_prio;
907
908         spin_lock(&info->lock);
909
910         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
911                 if (filp->f_flags & O_NONBLOCK) {
912                         spin_unlock(&info->lock);
913                         ret = -EAGAIN;
914                 } else {
915                         wait.task = current;
916                         wait.msg = (void *) msg_ptr;
917                         wait.state = STATE_NONE;
918                         ret = wq_sleep(info, SEND, timeout, &wait);
919                 }
920                 if (ret < 0)
921                         free_msg(msg_ptr);
922         } else {
923                 receiver = wq_get_first_waiter(info, RECV);
924                 if (receiver) {
925                         pipelined_send(info, msg_ptr, receiver);
926                 } else {
927                         /* adds message to the queue */
928                         msg_insert(msg_ptr, info);
929                         __do_notify(info);
930                 }
931                 inode->i_atime = inode->i_mtime = inode->i_ctime =
932                                 CURRENT_TIME;
933                 spin_unlock(&info->lock);
934                 ret = 0;
935         }
936 out_fput:
937         fput(filp);
938 out:
939         return ret;
940 }
941
942 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
943                 size_t, msg_len, unsigned int __user *, u_msg_prio,
944                 const struct timespec __user *, u_abs_timeout)
945 {
946         ssize_t ret;
947         struct msg_msg *msg_ptr;
948         struct file *filp;
949         struct inode *inode;
950         struct mqueue_inode_info *info;
951         struct ext_wait_queue wait;
952         ktime_t expires, *timeout = NULL;
953         struct timespec ts;
954
955         if (u_abs_timeout) {
956                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
957                 if (res)
958                         return res;
959                 timeout = &expires;
960         }
961
962         audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
963
964         filp = fget(mqdes);
965         if (unlikely(!filp)) {
966                 ret = -EBADF;
967                 goto out;
968         }
969
970         inode = filp->f_path.dentry->d_inode;
971         if (unlikely(filp->f_op != &mqueue_file_operations)) {
972                 ret = -EBADF;
973                 goto out_fput;
974         }
975         info = MQUEUE_I(inode);
976         audit_inode(NULL, filp->f_path.dentry);
977
978         if (unlikely(!(filp->f_mode & FMODE_READ))) {
979                 ret = -EBADF;
980                 goto out_fput;
981         }
982
983         /* checks if buffer is big enough */
984         if (unlikely(msg_len < info->attr.mq_msgsize)) {
985                 ret = -EMSGSIZE;
986                 goto out_fput;
987         }
988
989         spin_lock(&info->lock);
990         if (info->attr.mq_curmsgs == 0) {
991                 if (filp->f_flags & O_NONBLOCK) {
992                         spin_unlock(&info->lock);
993                         ret = -EAGAIN;
994                 } else {
995                         wait.task = current;
996                         wait.state = STATE_NONE;
997                         ret = wq_sleep(info, RECV, timeout, &wait);
998                         msg_ptr = wait.msg;
999                 }
1000         } else {
1001                 msg_ptr = msg_get(info);
1002
1003                 inode->i_atime = inode->i_mtime = inode->i_ctime =
1004                                 CURRENT_TIME;
1005
1006                 /* There is now free space in queue. */
1007                 pipelined_receive(info);
1008                 spin_unlock(&info->lock);
1009                 ret = 0;
1010         }
1011         if (ret == 0) {
1012                 ret = msg_ptr->m_ts;
1013
1014                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1015                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1016                         ret = -EFAULT;
1017                 }
1018                 free_msg(msg_ptr);
1019         }
1020 out_fput:
1021         fput(filp);
1022 out:
1023         return ret;
1024 }
1025
1026 /*
1027  * Notes: the case when user wants us to deregister (with NULL as pointer)
1028  * and he isn't currently owner of notification, will be silently discarded.
1029  * It isn't explicitly defined in the POSIX.
1030  */
1031 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1032                 const struct sigevent __user *, u_notification)
1033 {
1034         int ret;
1035         struct file *filp;
1036         struct sock *sock;
1037         struct inode *inode;
1038         struct sigevent notification;
1039         struct mqueue_inode_info *info;
1040         struct sk_buff *nc;
1041
1042         if (u_notification) {
1043                 if (copy_from_user(&notification, u_notification,
1044                                         sizeof(struct sigevent)))
1045                         return -EFAULT;
1046         }
1047
1048         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1049
1050         nc = NULL;
1051         sock = NULL;
1052         if (u_notification != NULL) {
1053                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1054                              notification.sigev_notify != SIGEV_SIGNAL &&
1055                              notification.sigev_notify != SIGEV_THREAD))
1056                         return -EINVAL;
1057                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1058                         !valid_signal(notification.sigev_signo)) {
1059                         return -EINVAL;
1060                 }
1061                 if (notification.sigev_notify == SIGEV_THREAD) {
1062                         long timeo;
1063
1064                         /* create the notify skb */
1065                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1066                         if (!nc) {
1067                                 ret = -ENOMEM;
1068                                 goto out;
1069                         }
1070                         if (copy_from_user(nc->data,
1071                                         notification.sigev_value.sival_ptr,
1072                                         NOTIFY_COOKIE_LEN)) {
1073                                 ret = -EFAULT;
1074                                 goto out;
1075                         }
1076
1077                         /* TODO: add a header? */
1078                         skb_put(nc, NOTIFY_COOKIE_LEN);
1079                         /* and attach it to the socket */
1080 retry:
1081                         filp = fget(notification.sigev_signo);
1082                         if (!filp) {
1083                                 ret = -EBADF;
1084                                 goto out;
1085                         }
1086                         sock = netlink_getsockbyfilp(filp);
1087                         fput(filp);
1088                         if (IS_ERR(sock)) {
1089                                 ret = PTR_ERR(sock);
1090                                 sock = NULL;
1091                                 goto out;
1092                         }
1093
1094                         timeo = MAX_SCHEDULE_TIMEOUT;
1095                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1096                         if (ret == 1)
1097                                 goto retry;
1098                         if (ret) {
1099                                 sock = NULL;
1100                                 nc = NULL;
1101                                 goto out;
1102                         }
1103                 }
1104         }
1105
1106         filp = fget(mqdes);
1107         if (!filp) {
1108                 ret = -EBADF;
1109                 goto out;
1110         }
1111
1112         inode = filp->f_path.dentry->d_inode;
1113         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1114                 ret = -EBADF;
1115                 goto out_fput;
1116         }
1117         info = MQUEUE_I(inode);
1118
1119         ret = 0;
1120         spin_lock(&info->lock);
1121         if (u_notification == NULL) {
1122                 if (info->notify_owner == task_tgid(current)) {
1123                         remove_notification(info);
1124                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1125                 }
1126         } else if (info->notify_owner != NULL) {
1127                 ret = -EBUSY;
1128         } else {
1129                 switch (notification.sigev_notify) {
1130                 case SIGEV_NONE:
1131                         info->notify.sigev_notify = SIGEV_NONE;
1132                         break;
1133                 case SIGEV_THREAD:
1134                         info->notify_sock = sock;
1135                         info->notify_cookie = nc;
1136                         sock = NULL;
1137                         nc = NULL;
1138                         info->notify.sigev_notify = SIGEV_THREAD;
1139                         break;
1140                 case SIGEV_SIGNAL:
1141                         info->notify.sigev_signo = notification.sigev_signo;
1142                         info->notify.sigev_value = notification.sigev_value;
1143                         info->notify.sigev_notify = SIGEV_SIGNAL;
1144                         break;
1145                 }
1146
1147                 info->notify_owner = get_pid(task_tgid(current));
1148                 info->notify_user_ns = get_user_ns(current_user_ns());
1149                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1150         }
1151         spin_unlock(&info->lock);
1152 out_fput:
1153         fput(filp);
1154 out:
1155         if (sock) {
1156                 netlink_detachskb(sock, nc);
1157         } else if (nc) {
1158                 dev_kfree_skb(nc);
1159         }
1160         return ret;
1161 }
1162
1163 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1164                 const struct mq_attr __user *, u_mqstat,
1165                 struct mq_attr __user *, u_omqstat)
1166 {
1167         int ret;
1168         struct mq_attr mqstat, omqstat;
1169         struct file *filp;
1170         struct inode *inode;
1171         struct mqueue_inode_info *info;
1172
1173         if (u_mqstat != NULL) {
1174                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1175                         return -EFAULT;
1176                 if (mqstat.mq_flags & (~O_NONBLOCK))
1177                         return -EINVAL;
1178         }
1179
1180         filp = fget(mqdes);
1181         if (!filp) {
1182                 ret = -EBADF;
1183                 goto out;
1184         }
1185
1186         inode = filp->f_path.dentry->d_inode;
1187         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1188                 ret = -EBADF;
1189                 goto out_fput;
1190         }
1191         info = MQUEUE_I(inode);
1192
1193         spin_lock(&info->lock);
1194
1195         omqstat = info->attr;
1196         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1197         if (u_mqstat) {
1198                 audit_mq_getsetattr(mqdes, &mqstat);
1199                 spin_lock(&filp->f_lock);
1200                 if (mqstat.mq_flags & O_NONBLOCK)
1201                         filp->f_flags |= O_NONBLOCK;
1202                 else
1203                         filp->f_flags &= ~O_NONBLOCK;
1204                 spin_unlock(&filp->f_lock);
1205
1206                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1207         }
1208
1209         spin_unlock(&info->lock);
1210
1211         ret = 0;
1212         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1213                                                 sizeof(struct mq_attr)))
1214                 ret = -EFAULT;
1215
1216 out_fput:
1217         fput(filp);
1218 out:
1219         return ret;
1220 }
1221
1222 static const struct inode_operations mqueue_dir_inode_operations = {
1223         .lookup = simple_lookup,
1224         .create = mqueue_create,
1225         .unlink = mqueue_unlink,
1226 };
1227
1228 static const struct file_operations mqueue_file_operations = {
1229         .flush = mqueue_flush_file,
1230         .poll = mqueue_poll_file,
1231         .read = mqueue_read_file,
1232         .llseek = default_llseek,
1233 };
1234
1235 static const struct super_operations mqueue_super_ops = {
1236         .alloc_inode = mqueue_alloc_inode,
1237         .destroy_inode = mqueue_destroy_inode,
1238         .evict_inode = mqueue_evict_inode,
1239         .statfs = simple_statfs,
1240 };
1241
1242 static struct file_system_type mqueue_fs_type = {
1243         .name = "mqueue",
1244         .mount = mqueue_mount,
1245         .kill_sb = kill_litter_super,
1246 };
1247
1248 int mq_init_ns(struct ipc_namespace *ns)
1249 {
1250         ns->mq_queues_count  = 0;
1251         ns->mq_queues_max    = DFLT_QUEUESMAX;
1252         ns->mq_msg_max       = DFLT_MSGMAX;
1253         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1254
1255         ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1256         if (IS_ERR(ns->mq_mnt)) {
1257                 int err = PTR_ERR(ns->mq_mnt);
1258                 ns->mq_mnt = NULL;
1259                 return err;
1260         }
1261         return 0;
1262 }
1263
1264 void mq_clear_sbinfo(struct ipc_namespace *ns)
1265 {
1266         ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1267 }
1268
1269 void mq_put_mnt(struct ipc_namespace *ns)
1270 {
1271         kern_unmount(ns->mq_mnt);
1272 }
1273
1274 static int __init init_mqueue_fs(void)
1275 {
1276         int error;
1277
1278         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1279                                 sizeof(struct mqueue_inode_info), 0,
1280                                 SLAB_HWCACHE_ALIGN, init_once);
1281         if (mqueue_inode_cachep == NULL)
1282                 return -ENOMEM;
1283
1284         /* ignore failures - they are not fatal */
1285         mq_sysctl_table = mq_register_sysctl_table();
1286
1287         error = register_filesystem(&mqueue_fs_type);
1288         if (error)
1289                 goto out_sysctl;
1290
1291         spin_lock_init(&mq_lock);
1292
1293         error = mq_init_ns(&init_ipc_ns);
1294         if (error)
1295                 goto out_filesystem;
1296
1297         return 0;
1298
1299 out_filesystem:
1300         unregister_filesystem(&mqueue_fs_type);
1301 out_sysctl:
1302         if (mq_sysctl_table)
1303                 unregister_sysctl_table(mq_sysctl_table);
1304         kmem_cache_destroy(mqueue_inode_cachep);
1305         return error;
1306 }
1307
1308 __initcall(init_mqueue_fs);