9b7c8ab7d75cad27e92272c0a0c81927c9fbaa03
[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_struct *user;       /* user who created, for accounting */
70         struct sock *notify_sock;
71         struct sk_buff *notify_cookie;
72
73         /* for tasks waiting for free space and messages, respectively */
74         struct ext_wait_queue e_wait_q[2];
75
76         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
77 };
78
79 static const struct inode_operations mqueue_dir_inode_operations;
80 static const struct file_operations mqueue_file_operations;
81 static const struct super_operations mqueue_super_ops;
82 static void remove_notification(struct mqueue_inode_info *info);
83
84 static struct kmem_cache *mqueue_inode_cachep;
85
86 static struct ctl_table_header * mq_sysctl_table;
87
88 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
89 {
90         return container_of(inode, struct mqueue_inode_info, vfs_inode);
91 }
92
93 /*
94  * This routine should be called with the mq_lock held.
95  */
96 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
97 {
98         return get_ipc_ns(inode->i_sb->s_fs_info);
99 }
100
101 static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
102 {
103         struct ipc_namespace *ns;
104
105         spin_lock(&mq_lock);
106         ns = __get_ns_from_inode(inode);
107         spin_unlock(&mq_lock);
108         return ns;
109 }
110
111 static struct inode *mqueue_get_inode(struct super_block *sb,
112                 struct ipc_namespace *ipc_ns, umode_t mode,
113                 struct mq_attr *attr)
114 {
115         struct user_struct *u = current_user();
116         struct inode *inode;
117         int ret = -ENOMEM;
118
119         inode = new_inode(sb);
120         if (!inode)
121                 goto err;
122
123         inode->i_ino = get_next_ino();
124         inode->i_mode = mode;
125         inode->i_uid = current_fsuid();
126         inode->i_gid = current_fsgid();
127         inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
128
129         if (S_ISREG(mode)) {
130                 struct mqueue_inode_info *info;
131                 struct task_struct *p = current;
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->qsize = 0;
144                 info->user = NULL;      /* set when all is ok */
145                 memset(&info->attr, 0, sizeof(info->attr));
146                 info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
147                 info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
148                 if (attr) {
149                         info->attr.mq_maxmsg = attr->mq_maxmsg;
150                         info->attr.mq_msgsize = attr->mq_msgsize;
151                 }
152                 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
153                 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
154                 if (!info->messages)
155                         goto out_inode;
156
157                 mq_bytes = (mq_msg_tblsz +
158                         (info->attr.mq_maxmsg * info->attr.mq_msgsize));
159
160                 spin_lock(&mq_lock);
161                 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
162                     u->mq_bytes + mq_bytes > task_rlimit(p, RLIMIT_MSGQUEUE)) {
163                         spin_unlock(&mq_lock);
164                         /* mqueue_evict_inode() releases info->messages */
165                         ret = -EMFILE;
166                         goto out_inode;
167                 }
168                 u->mq_bytes += mq_bytes;
169                 spin_unlock(&mq_lock);
170
171                 /* all is ok */
172                 info->user = get_uid(u);
173         } else if (S_ISDIR(mode)) {
174                 inc_nlink(inode);
175                 /* Some things misbehave if size == 0 on a directory */
176                 inode->i_size = 2 * DIRENT_SIZE;
177                 inode->i_op = &mqueue_dir_inode_operations;
178                 inode->i_fop = &simple_dir_operations;
179         }
180
181         return inode;
182 out_inode:
183         iput(inode);
184 err:
185         return ERR_PTR(ret);
186 }
187
188 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
189 {
190         struct inode *inode;
191         struct ipc_namespace *ns = data;
192         int error;
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,
200                                 NULL);
201         if (IS_ERR(inode)) {
202                 error = PTR_ERR(inode);
203                 goto out;
204         }
205
206         sb->s_root = d_alloc_root(inode);
207         if (!sb->s_root) {
208                 iput(inode);
209                 error = -ENOMEM;
210                 goto out;
211         }
212         error = 0;
213
214 out:
215         return error;
216 }
217
218 static struct dentry *mqueue_mount(struct file_system_type *fs_type,
219                          int flags, const char *dev_name,
220                          void *data)
221 {
222         if (!(flags & MS_KERNMOUNT))
223                 data = current->nsproxy->ipc_ns;
224         return mount_ns(fs_type, flags, data, mqueue_fill_super);
225 }
226
227 static void init_once(void *foo)
228 {
229         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
230
231         inode_init_once(&p->vfs_inode);
232 }
233
234 static struct inode *mqueue_alloc_inode(struct super_block *sb)
235 {
236         struct mqueue_inode_info *ei;
237
238         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
239         if (!ei)
240                 return NULL;
241         return &ei->vfs_inode;
242 }
243
244 static void mqueue_i_callback(struct rcu_head *head)
245 {
246         struct inode *inode = container_of(head, struct inode, i_rcu);
247         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
248 }
249
250 static void mqueue_destroy_inode(struct inode *inode)
251 {
252         call_rcu(&inode->i_rcu, mqueue_i_callback);
253 }
254
255 static void mqueue_evict_inode(struct inode *inode)
256 {
257         struct mqueue_inode_info *info;
258         struct user_struct *user;
259         unsigned long mq_bytes;
260         int i;
261         struct ipc_namespace *ipc_ns;
262
263         end_writeback(inode);
264
265         if (S_ISDIR(inode->i_mode))
266                 return;
267
268         ipc_ns = get_ns_from_inode(inode);
269         info = MQUEUE_I(inode);
270         spin_lock(&info->lock);
271         for (i = 0; i < info->attr.mq_curmsgs; i++)
272                 free_msg(info->messages[i]);
273         kfree(info->messages);
274         spin_unlock(&info->lock);
275
276         /* Total amount of bytes accounted for the mqueue */
277         mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
278             + info->attr.mq_msgsize);
279         user = info->user;
280         if (user) {
281                 spin_lock(&mq_lock);
282                 user->mq_bytes -= mq_bytes;
283                 /*
284                  * get_ns_from_inode() ensures that the
285                  * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
286                  * to which we now hold a reference, or it is NULL.
287                  * We can't put it here under mq_lock, though.
288                  */
289                 if (ipc_ns)
290                         ipc_ns->mq_queues_count--;
291                 spin_unlock(&mq_lock);
292                 free_uid(user);
293         }
294         if (ipc_ns)
295                 put_ipc_ns(ipc_ns);
296 }
297
298 static int mqueue_create(struct inode *dir, struct dentry *dentry,
299                                 umode_t mode, struct nameidata *nd)
300 {
301         struct inode *inode;
302         struct mq_attr *attr = dentry->d_fsdata;
303         int error;
304         struct ipc_namespace *ipc_ns;
305
306         spin_lock(&mq_lock);
307         ipc_ns = __get_ns_from_inode(dir);
308         if (!ipc_ns) {
309                 error = -EACCES;
310                 goto out_unlock;
311         }
312         if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
313                         !capable(CAP_SYS_RESOURCE)) {
314                 error = -ENOSPC;
315                 goto out_unlock;
316         }
317         ipc_ns->mq_queues_count++;
318         spin_unlock(&mq_lock);
319
320         inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
321         if (IS_ERR(inode)) {
322                 error = PTR_ERR(inode);
323                 spin_lock(&mq_lock);
324                 ipc_ns->mq_queues_count--;
325                 goto out_unlock;
326         }
327
328         put_ipc_ns(ipc_ns);
329         dir->i_size += DIRENT_SIZE;
330         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
331
332         d_instantiate(dentry, inode);
333         dget(dentry);
334         return 0;
335 out_unlock:
336         spin_unlock(&mq_lock);
337         if (ipc_ns)
338                 put_ipc_ns(ipc_ns);
339         return error;
340 }
341
342 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
343 {
344         struct inode *inode = dentry->d_inode;
345
346         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
347         dir->i_size -= DIRENT_SIZE;
348         drop_nlink(inode);
349         dput(dentry);
350         return 0;
351 }
352
353 /*
354 *       This is routine for system read from queue file.
355 *       To avoid mess with doing here some sort of mq_receive we allow
356 *       to read only queue size & notification info (the only values
357 *       that are interesting from user point of view and aren't accessible
358 *       through std routines)
359 */
360 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
361                                 size_t count, loff_t *off)
362 {
363         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
364         char buffer[FILENT_SIZE];
365         ssize_t ret;
366
367         spin_lock(&info->lock);
368         snprintf(buffer, sizeof(buffer),
369                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
370                         info->qsize,
371                         info->notify_owner ? info->notify.sigev_notify : 0,
372                         (info->notify_owner &&
373                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
374                                 info->notify.sigev_signo : 0,
375                         pid_vnr(info->notify_owner));
376         spin_unlock(&info->lock);
377         buffer[sizeof(buffer)-1] = '\0';
378
379         ret = simple_read_from_buffer(u_data, count, off, buffer,
380                                 strlen(buffer));
381         if (ret <= 0)
382                 return ret;
383
384         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
385         return ret;
386 }
387
388 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
389 {
390         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
391
392         spin_lock(&info->lock);
393         if (task_tgid(current) == info->notify_owner)
394                 remove_notification(info);
395
396         spin_unlock(&info->lock);
397         return 0;
398 }
399
400 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
401 {
402         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
403         int retval = 0;
404
405         poll_wait(filp, &info->wait_q, poll_tab);
406
407         spin_lock(&info->lock);
408         if (info->attr.mq_curmsgs)
409                 retval = POLLIN | POLLRDNORM;
410
411         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
412                 retval |= POLLOUT | POLLWRNORM;
413         spin_unlock(&info->lock);
414
415         return retval;
416 }
417
418 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
419 static void wq_add(struct mqueue_inode_info *info, int sr,
420                         struct ext_wait_queue *ewp)
421 {
422         struct ext_wait_queue *walk;
423
424         ewp->task = current;
425
426         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
427                 if (walk->task->static_prio <= current->static_prio) {
428                         list_add_tail(&ewp->list, &walk->list);
429                         return;
430                 }
431         }
432         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
433 }
434
435 /*
436  * Puts current task to sleep. Caller must hold queue lock. After return
437  * lock isn't held.
438  * sr: SEND or RECV
439  */
440 static int wq_sleep(struct mqueue_inode_info *info, int sr,
441                     ktime_t *timeout, struct ext_wait_queue *ewp)
442 {
443         int retval;
444         signed long time;
445
446         wq_add(info, sr, ewp);
447
448         for (;;) {
449                 set_current_state(TASK_INTERRUPTIBLE);
450
451                 spin_unlock(&info->lock);
452                 time = schedule_hrtimeout_range_clock(timeout, 0,
453                         HRTIMER_MODE_ABS, CLOCK_REALTIME);
454
455                 while (ewp->state == STATE_PENDING)
456                         cpu_relax();
457
458                 if (ewp->state == STATE_READY) {
459                         retval = 0;
460                         goto out;
461                 }
462                 spin_lock(&info->lock);
463                 if (ewp->state == STATE_READY) {
464                         retval = 0;
465                         goto out_unlock;
466                 }
467                 if (signal_pending(current)) {
468                         retval = -ERESTARTSYS;
469                         break;
470                 }
471                 if (time == 0) {
472                         retval = -ETIMEDOUT;
473                         break;
474                 }
475         }
476         list_del(&ewp->list);
477 out_unlock:
478         spin_unlock(&info->lock);
479 out:
480         return retval;
481 }
482
483 /*
484  * Returns waiting task that should be serviced first or NULL if none exists
485  */
486 static struct ext_wait_queue *wq_get_first_waiter(
487                 struct mqueue_inode_info *info, int sr)
488 {
489         struct list_head *ptr;
490
491         ptr = info->e_wait_q[sr].list.prev;
492         if (ptr == &info->e_wait_q[sr].list)
493                 return NULL;
494         return list_entry(ptr, struct ext_wait_queue, list);
495 }
496
497 /* Auxiliary functions to manipulate messages' list */
498 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
499 {
500         int k;
501
502         k = info->attr.mq_curmsgs - 1;
503         while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
504                 info->messages[k + 1] = info->messages[k];
505                 k--;
506         }
507         info->attr.mq_curmsgs++;
508         info->qsize += ptr->m_ts;
509         info->messages[k + 1] = ptr;
510 }
511
512 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
513 {
514         info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
515         return info->messages[info->attr.mq_curmsgs];
516 }
517
518 static inline void set_cookie(struct sk_buff *skb, char code)
519 {
520         ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
521 }
522
523 /*
524  * The next function is only to split too long sys_mq_timedsend
525  */
526 static void __do_notify(struct mqueue_inode_info *info)
527 {
528         /* notification
529          * invoked when there is registered process and there isn't process
530          * waiting synchronously for message AND state of queue changed from
531          * empty to not empty. Here we are sure that no one is waiting
532          * synchronously. */
533         if (info->notify_owner &&
534             info->attr.mq_curmsgs == 1) {
535                 struct siginfo sig_i;
536                 switch (info->notify.sigev_notify) {
537                 case SIGEV_NONE:
538                         break;
539                 case SIGEV_SIGNAL:
540                         /* sends signal */
541
542                         sig_i.si_signo = info->notify.sigev_signo;
543                         sig_i.si_errno = 0;
544                         sig_i.si_code = SI_MESGQ;
545                         sig_i.si_value = info->notify.sigev_value;
546                         /* map current pid/uid into info->owner's namespaces */
547                         rcu_read_lock();
548                         sig_i.si_pid = task_tgid_nr_ns(current,
549                                                 ns_of_pid(info->notify_owner));
550                         sig_i.si_uid = user_ns_map_uid(info->user->user_ns,
551                                                 current_cred(), current_uid());
552                         rcu_read_unlock();
553
554                         kill_pid_info(info->notify.sigev_signo,
555                                       &sig_i, info->notify_owner);
556                         break;
557                 case SIGEV_THREAD:
558                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
559                         netlink_sendskb(info->notify_sock, info->notify_cookie);
560                         break;
561                 }
562                 /* after notification unregisters process */
563                 put_pid(info->notify_owner);
564                 info->notify_owner = NULL;
565         }
566         wake_up(&info->wait_q);
567 }
568
569 static int prepare_timeout(const struct timespec __user *u_abs_timeout,
570                            ktime_t *expires, struct timespec *ts)
571 {
572         if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
573                 return -EFAULT;
574         if (!timespec_valid(ts))
575                 return -EINVAL;
576
577         *expires = timespec_to_ktime(*ts);
578         return 0;
579 }
580
581 static void remove_notification(struct mqueue_inode_info *info)
582 {
583         if (info->notify_owner != NULL &&
584             info->notify.sigev_notify == SIGEV_THREAD) {
585                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
586                 netlink_sendskb(info->notify_sock, info->notify_cookie);
587         }
588         put_pid(info->notify_owner);
589         info->notify_owner = NULL;
590 }
591
592 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
593 {
594         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
595                 return 0;
596         if (capable(CAP_SYS_RESOURCE)) {
597                 if (attr->mq_maxmsg > HARD_MSGMAX)
598                         return 0;
599         } else {
600                 if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
601                                 attr->mq_msgsize > ipc_ns->mq_msgsize_max)
602                         return 0;
603         }
604         /* check for overflow */
605         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
606                 return 0;
607         if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
608             + sizeof (struct msg_msg *))) <
609             (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
610                 return 0;
611         return 1;
612 }
613
614 /*
615  * Invoked when creating a new queue via sys_mq_open
616  */
617 static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
618                         struct dentry *dentry, int oflag, umode_t mode,
619                         struct mq_attr *attr)
620 {
621         const struct cred *cred = current_cred();
622         struct file *result;
623         int ret;
624
625         if (attr) {
626                 if (!mq_attr_ok(ipc_ns, attr)) {
627                         ret = -EINVAL;
628                         goto out;
629                 }
630                 /* store for use during create */
631                 dentry->d_fsdata = attr;
632         }
633
634         mode &= ~current_umask();
635         ret = mnt_want_write(ipc_ns->mq_mnt);
636         if (ret)
637                 goto out;
638         ret = vfs_create(dir->d_inode, dentry, mode, NULL);
639         dentry->d_fsdata = NULL;
640         if (ret)
641                 goto out_drop_write;
642
643         result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
644         /*
645          * dentry_open() took a persistent mnt_want_write(),
646          * so we can now drop this one.
647          */
648         mnt_drop_write(ipc_ns->mq_mnt);
649         return result;
650
651 out_drop_write:
652         mnt_drop_write(ipc_ns->mq_mnt);
653 out:
654         dput(dentry);
655         mntput(ipc_ns->mq_mnt);
656         return ERR_PTR(ret);
657 }
658
659 /* Opens existing queue */
660 static struct file *do_open(struct ipc_namespace *ipc_ns,
661                                 struct dentry *dentry, int oflag)
662 {
663         int ret;
664         const struct cred *cred = current_cred();
665
666         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
667                                                   MAY_READ | MAY_WRITE };
668
669         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
670                 ret = -EINVAL;
671                 goto err;
672         }
673
674         if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
675                 ret = -EACCES;
676                 goto err;
677         }
678
679         return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
680
681 err:
682         dput(dentry);
683         mntput(ipc_ns->mq_mnt);
684         return ERR_PTR(ret);
685 }
686
687 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
688                 struct mq_attr __user *, u_attr)
689 {
690         struct dentry *dentry;
691         struct file *filp;
692         char *name;
693         struct mq_attr attr;
694         int fd, error;
695         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
696
697         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
698                 return -EFAULT;
699
700         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
701
702         if (IS_ERR(name = getname(u_name)))
703                 return PTR_ERR(name);
704
705         fd = get_unused_fd_flags(O_CLOEXEC);
706         if (fd < 0)
707                 goto out_putname;
708
709         mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
710         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
711         if (IS_ERR(dentry)) {
712                 error = PTR_ERR(dentry);
713                 goto out_putfd;
714         }
715         mntget(ipc_ns->mq_mnt);
716
717         if (oflag & O_CREAT) {
718                 if (dentry->d_inode) {  /* entry already exists */
719                         audit_inode(name, dentry);
720                         if (oflag & O_EXCL) {
721                                 error = -EEXIST;
722                                 goto out;
723                         }
724                         filp = do_open(ipc_ns, dentry, oflag);
725                 } else {
726                         filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
727                                                 dentry, oflag, mode,
728                                                 u_attr ? &attr : NULL);
729                 }
730         } else {
731                 if (!dentry->d_inode) {
732                         error = -ENOENT;
733                         goto out;
734                 }
735                 audit_inode(name, dentry);
736                 filp = do_open(ipc_ns, dentry, oflag);
737         }
738
739         if (IS_ERR(filp)) {
740                 error = PTR_ERR(filp);
741                 goto out_putfd;
742         }
743
744         fd_install(fd, filp);
745         goto out_upsem;
746
747 out:
748         dput(dentry);
749         mntput(ipc_ns->mq_mnt);
750 out_putfd:
751         put_unused_fd(fd);
752         fd = error;
753 out_upsem:
754         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
755 out_putname:
756         putname(name);
757         return fd;
758 }
759
760 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
761 {
762         int err;
763         char *name;
764         struct dentry *dentry;
765         struct inode *inode = NULL;
766         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
767
768         name = getname(u_name);
769         if (IS_ERR(name))
770                 return PTR_ERR(name);
771
772         mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
773                         I_MUTEX_PARENT);
774         dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
775         if (IS_ERR(dentry)) {
776                 err = PTR_ERR(dentry);
777                 goto out_unlock;
778         }
779
780         if (!dentry->d_inode) {
781                 err = -ENOENT;
782                 goto out_err;
783         }
784
785         inode = dentry->d_inode;
786         if (inode)
787                 ihold(inode);
788         err = mnt_want_write(ipc_ns->mq_mnt);
789         if (err)
790                 goto out_err;
791         err = vfs_unlink(dentry->d_parent->d_inode, dentry);
792         mnt_drop_write(ipc_ns->mq_mnt);
793 out_err:
794         dput(dentry);
795
796 out_unlock:
797         mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
798         putname(name);
799         if (inode)
800                 iput(inode);
801
802         return err;
803 }
804
805 /* Pipelined send and receive functions.
806  *
807  * If a receiver finds no waiting message, then it registers itself in the
808  * list of waiting receivers. A sender checks that list before adding the new
809  * message into the message array. If there is a waiting receiver, then it
810  * bypasses the message array and directly hands the message over to the
811  * receiver.
812  * The receiver accepts the message and returns without grabbing the queue
813  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
814  * are necessary. The same algorithm is used for sysv semaphores, see
815  * ipc/sem.c for more details.
816  *
817  * The same algorithm is used for senders.
818  */
819
820 /* pipelined_send() - send a message directly to the task waiting in
821  * sys_mq_timedreceive() (without inserting message into a queue).
822  */
823 static inline void pipelined_send(struct mqueue_inode_info *info,
824                                   struct msg_msg *message,
825                                   struct ext_wait_queue *receiver)
826 {
827         receiver->msg = message;
828         list_del(&receiver->list);
829         receiver->state = STATE_PENDING;
830         wake_up_process(receiver->task);
831         smp_wmb();
832         receiver->state = STATE_READY;
833 }
834
835 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
836  * gets its message and put to the queue (we have one free place for sure). */
837 static inline void pipelined_receive(struct mqueue_inode_info *info)
838 {
839         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
840
841         if (!sender) {
842                 /* for poll */
843                 wake_up_interruptible(&info->wait_q);
844                 return;
845         }
846         msg_insert(sender->msg, info);
847         list_del(&sender->list);
848         sender->state = STATE_PENDING;
849         wake_up_process(sender->task);
850         smp_wmb();
851         sender->state = STATE_READY;
852 }
853
854 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
855                 size_t, msg_len, unsigned int, msg_prio,
856                 const struct timespec __user *, u_abs_timeout)
857 {
858         struct file *filp;
859         struct inode *inode;
860         struct ext_wait_queue wait;
861         struct ext_wait_queue *receiver;
862         struct msg_msg *msg_ptr;
863         struct mqueue_inode_info *info;
864         ktime_t expires, *timeout = NULL;
865         struct timespec ts;
866         int ret;
867
868         if (u_abs_timeout) {
869                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
870                 if (res)
871                         return res;
872                 timeout = &expires;
873         }
874
875         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
876                 return -EINVAL;
877
878         audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
879
880         filp = fget(mqdes);
881         if (unlikely(!filp)) {
882                 ret = -EBADF;
883                 goto out;
884         }
885
886         inode = filp->f_path.dentry->d_inode;
887         if (unlikely(filp->f_op != &mqueue_file_operations)) {
888                 ret = -EBADF;
889                 goto out_fput;
890         }
891         info = MQUEUE_I(inode);
892         audit_inode(NULL, filp->f_path.dentry);
893
894         if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
895                 ret = -EBADF;
896                 goto out_fput;
897         }
898
899         if (unlikely(msg_len > info->attr.mq_msgsize)) {
900                 ret = -EMSGSIZE;
901                 goto out_fput;
902         }
903
904         /* First try to allocate memory, before doing anything with
905          * existing queues. */
906         msg_ptr = load_msg(u_msg_ptr, msg_len);
907         if (IS_ERR(msg_ptr)) {
908                 ret = PTR_ERR(msg_ptr);
909                 goto out_fput;
910         }
911         msg_ptr->m_ts = msg_len;
912         msg_ptr->m_type = msg_prio;
913
914         spin_lock(&info->lock);
915
916         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
917                 if (filp->f_flags & O_NONBLOCK) {
918                         spin_unlock(&info->lock);
919                         ret = -EAGAIN;
920                 } else {
921                         wait.task = current;
922                         wait.msg = (void *) msg_ptr;
923                         wait.state = STATE_NONE;
924                         ret = wq_sleep(info, SEND, timeout, &wait);
925                 }
926                 if (ret < 0)
927                         free_msg(msg_ptr);
928         } else {
929                 receiver = wq_get_first_waiter(info, RECV);
930                 if (receiver) {
931                         pipelined_send(info, msg_ptr, receiver);
932                 } else {
933                         /* adds message to the queue */
934                         msg_insert(msg_ptr, info);
935                         __do_notify(info);
936                 }
937                 inode->i_atime = inode->i_mtime = inode->i_ctime =
938                                 CURRENT_TIME;
939                 spin_unlock(&info->lock);
940                 ret = 0;
941         }
942 out_fput:
943         fput(filp);
944 out:
945         return ret;
946 }
947
948 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
949                 size_t, msg_len, unsigned int __user *, u_msg_prio,
950                 const struct timespec __user *, u_abs_timeout)
951 {
952         ssize_t ret;
953         struct msg_msg *msg_ptr;
954         struct file *filp;
955         struct inode *inode;
956         struct mqueue_inode_info *info;
957         struct ext_wait_queue wait;
958         ktime_t expires, *timeout = NULL;
959         struct timespec ts;
960
961         if (u_abs_timeout) {
962                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
963                 if (res)
964                         return res;
965                 timeout = &expires;
966         }
967
968         audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
969
970         filp = fget(mqdes);
971         if (unlikely(!filp)) {
972                 ret = -EBADF;
973                 goto out;
974         }
975
976         inode = filp->f_path.dentry->d_inode;
977         if (unlikely(filp->f_op != &mqueue_file_operations)) {
978                 ret = -EBADF;
979                 goto out_fput;
980         }
981         info = MQUEUE_I(inode);
982         audit_inode(NULL, filp->f_path.dentry);
983
984         if (unlikely(!(filp->f_mode & FMODE_READ))) {
985                 ret = -EBADF;
986                 goto out_fput;
987         }
988
989         /* checks if buffer is big enough */
990         if (unlikely(msg_len < info->attr.mq_msgsize)) {
991                 ret = -EMSGSIZE;
992                 goto out_fput;
993         }
994
995         spin_lock(&info->lock);
996         if (info->attr.mq_curmsgs == 0) {
997                 if (filp->f_flags & O_NONBLOCK) {
998                         spin_unlock(&info->lock);
999                         ret = -EAGAIN;
1000                 } else {
1001                         wait.task = current;
1002                         wait.state = STATE_NONE;
1003                         ret = wq_sleep(info, RECV, timeout, &wait);
1004                         msg_ptr = wait.msg;
1005                 }
1006         } else {
1007                 msg_ptr = msg_get(info);
1008
1009                 inode->i_atime = inode->i_mtime = inode->i_ctime =
1010                                 CURRENT_TIME;
1011
1012                 /* There is now free space in queue. */
1013                 pipelined_receive(info);
1014                 spin_unlock(&info->lock);
1015                 ret = 0;
1016         }
1017         if (ret == 0) {
1018                 ret = msg_ptr->m_ts;
1019
1020                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1021                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1022                         ret = -EFAULT;
1023                 }
1024                 free_msg(msg_ptr);
1025         }
1026 out_fput:
1027         fput(filp);
1028 out:
1029         return ret;
1030 }
1031
1032 /*
1033  * Notes: the case when user wants us to deregister (with NULL as pointer)
1034  * and he isn't currently owner of notification, will be silently discarded.
1035  * It isn't explicitly defined in the POSIX.
1036  */
1037 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1038                 const struct sigevent __user *, u_notification)
1039 {
1040         int ret;
1041         struct file *filp;
1042         struct sock *sock;
1043         struct inode *inode;
1044         struct sigevent notification;
1045         struct mqueue_inode_info *info;
1046         struct sk_buff *nc;
1047
1048         if (u_notification) {
1049                 if (copy_from_user(&notification, u_notification,
1050                                         sizeof(struct sigevent)))
1051                         return -EFAULT;
1052         }
1053
1054         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1055
1056         nc = NULL;
1057         sock = NULL;
1058         if (u_notification != NULL) {
1059                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1060                              notification.sigev_notify != SIGEV_SIGNAL &&
1061                              notification.sigev_notify != SIGEV_THREAD))
1062                         return -EINVAL;
1063                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1064                         !valid_signal(notification.sigev_signo)) {
1065                         return -EINVAL;
1066                 }
1067                 if (notification.sigev_notify == SIGEV_THREAD) {
1068                         long timeo;
1069
1070                         /* create the notify skb */
1071                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1072                         if (!nc) {
1073                                 ret = -ENOMEM;
1074                                 goto out;
1075                         }
1076                         if (copy_from_user(nc->data,
1077                                         notification.sigev_value.sival_ptr,
1078                                         NOTIFY_COOKIE_LEN)) {
1079                                 ret = -EFAULT;
1080                                 goto out;
1081                         }
1082
1083                         /* TODO: add a header? */
1084                         skb_put(nc, NOTIFY_COOKIE_LEN);
1085                         /* and attach it to the socket */
1086 retry:
1087                         filp = fget(notification.sigev_signo);
1088                         if (!filp) {
1089                                 ret = -EBADF;
1090                                 goto out;
1091                         }
1092                         sock = netlink_getsockbyfilp(filp);
1093                         fput(filp);
1094                         if (IS_ERR(sock)) {
1095                                 ret = PTR_ERR(sock);
1096                                 sock = NULL;
1097                                 goto out;
1098                         }
1099
1100                         timeo = MAX_SCHEDULE_TIMEOUT;
1101                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1102                         if (ret == 1)
1103                                 goto retry;
1104                         if (ret) {
1105                                 sock = NULL;
1106                                 nc = NULL;
1107                                 goto out;
1108                         }
1109                 }
1110         }
1111
1112         filp = fget(mqdes);
1113         if (!filp) {
1114                 ret = -EBADF;
1115                 goto out;
1116         }
1117
1118         inode = filp->f_path.dentry->d_inode;
1119         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1120                 ret = -EBADF;
1121                 goto out_fput;
1122         }
1123         info = MQUEUE_I(inode);
1124
1125         ret = 0;
1126         spin_lock(&info->lock);
1127         if (u_notification == NULL) {
1128                 if (info->notify_owner == task_tgid(current)) {
1129                         remove_notification(info);
1130                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1131                 }
1132         } else if (info->notify_owner != NULL) {
1133                 ret = -EBUSY;
1134         } else {
1135                 switch (notification.sigev_notify) {
1136                 case SIGEV_NONE:
1137                         info->notify.sigev_notify = SIGEV_NONE;
1138                         break;
1139                 case SIGEV_THREAD:
1140                         info->notify_sock = sock;
1141                         info->notify_cookie = nc;
1142                         sock = NULL;
1143                         nc = NULL;
1144                         info->notify.sigev_notify = SIGEV_THREAD;
1145                         break;
1146                 case SIGEV_SIGNAL:
1147                         info->notify.sigev_signo = notification.sigev_signo;
1148                         info->notify.sigev_value = notification.sigev_value;
1149                         info->notify.sigev_notify = SIGEV_SIGNAL;
1150                         break;
1151                 }
1152
1153                 info->notify_owner = get_pid(task_tgid(current));
1154                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1155         }
1156         spin_unlock(&info->lock);
1157 out_fput:
1158         fput(filp);
1159 out:
1160         if (sock) {
1161                 netlink_detachskb(sock, nc);
1162         } else if (nc) {
1163                 dev_kfree_skb(nc);
1164         }
1165         return ret;
1166 }
1167
1168 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1169                 const struct mq_attr __user *, u_mqstat,
1170                 struct mq_attr __user *, u_omqstat)
1171 {
1172         int ret;
1173         struct mq_attr mqstat, omqstat;
1174         struct file *filp;
1175         struct inode *inode;
1176         struct mqueue_inode_info *info;
1177
1178         if (u_mqstat != NULL) {
1179                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1180                         return -EFAULT;
1181                 if (mqstat.mq_flags & (~O_NONBLOCK))
1182                         return -EINVAL;
1183         }
1184
1185         filp = fget(mqdes);
1186         if (!filp) {
1187                 ret = -EBADF;
1188                 goto out;
1189         }
1190
1191         inode = filp->f_path.dentry->d_inode;
1192         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1193                 ret = -EBADF;
1194                 goto out_fput;
1195         }
1196         info = MQUEUE_I(inode);
1197
1198         spin_lock(&info->lock);
1199
1200         omqstat = info->attr;
1201         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1202         if (u_mqstat) {
1203                 audit_mq_getsetattr(mqdes, &mqstat);
1204                 spin_lock(&filp->f_lock);
1205                 if (mqstat.mq_flags & O_NONBLOCK)
1206                         filp->f_flags |= O_NONBLOCK;
1207                 else
1208                         filp->f_flags &= ~O_NONBLOCK;
1209                 spin_unlock(&filp->f_lock);
1210
1211                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1212         }
1213
1214         spin_unlock(&info->lock);
1215
1216         ret = 0;
1217         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1218                                                 sizeof(struct mq_attr)))
1219                 ret = -EFAULT;
1220
1221 out_fput:
1222         fput(filp);
1223 out:
1224         return ret;
1225 }
1226
1227 static const struct inode_operations mqueue_dir_inode_operations = {
1228         .lookup = simple_lookup,
1229         .create = mqueue_create,
1230         .unlink = mqueue_unlink,
1231 };
1232
1233 static const struct file_operations mqueue_file_operations = {
1234         .flush = mqueue_flush_file,
1235         .poll = mqueue_poll_file,
1236         .read = mqueue_read_file,
1237         .llseek = default_llseek,
1238 };
1239
1240 static const struct super_operations mqueue_super_ops = {
1241         .alloc_inode = mqueue_alloc_inode,
1242         .destroy_inode = mqueue_destroy_inode,
1243         .evict_inode = mqueue_evict_inode,
1244         .statfs = simple_statfs,
1245 };
1246
1247 static struct file_system_type mqueue_fs_type = {
1248         .name = "mqueue",
1249         .mount = mqueue_mount,
1250         .kill_sb = kill_litter_super,
1251 };
1252
1253 int mq_init_ns(struct ipc_namespace *ns)
1254 {
1255         ns->mq_queues_count  = 0;
1256         ns->mq_queues_max    = DFLT_QUEUESMAX;
1257         ns->mq_msg_max       = DFLT_MSGMAX;
1258         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1259
1260         ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1261         if (IS_ERR(ns->mq_mnt)) {
1262                 int err = PTR_ERR(ns->mq_mnt);
1263                 ns->mq_mnt = NULL;
1264                 return err;
1265         }
1266         return 0;
1267 }
1268
1269 void mq_clear_sbinfo(struct ipc_namespace *ns)
1270 {
1271         ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1272 }
1273
1274 void mq_put_mnt(struct ipc_namespace *ns)
1275 {
1276         kern_unmount(ns->mq_mnt);
1277 }
1278
1279 static int __init init_mqueue_fs(void)
1280 {
1281         int error;
1282
1283         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1284                                 sizeof(struct mqueue_inode_info), 0,
1285                                 SLAB_HWCACHE_ALIGN, init_once);
1286         if (mqueue_inode_cachep == NULL)
1287                 return -ENOMEM;
1288
1289         /* ignore failures - they are not fatal */
1290         mq_sysctl_table = mq_register_sysctl_table();
1291
1292         error = register_filesystem(&mqueue_fs_type);
1293         if (error)
1294                 goto out_sysctl;
1295
1296         spin_lock_init(&mq_lock);
1297
1298         error = mq_init_ns(&init_ipc_ns);
1299         if (error)
1300                 goto out_filesystem;
1301
1302         return 0;
1303
1304 out_filesystem:
1305         unregister_filesystem(&mqueue_fs_type);
1306 out_sysctl:
1307         if (mq_sysctl_table)
1308                 unregister_sysctl_table(mq_sysctl_table);
1309         kmem_cache_destroy(mqueue_inode_cachep);
1310         return error;
1311 }
1312
1313 __initcall(init_mqueue_fs);