Version:  2.0.40 2.2.26 2.4.37 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2

Linux/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/vmalloc.h>
 28 #include <linux/netlink.h>
 29 #include <linux/syscalls.h>
 30 #include <linux/audit.h>
 31 #include <linux/signal.h>
 32 #include <linux/mutex.h>
 33 #include <linux/nsproxy.h>
 34 #include <linux/pid.h>
 35 #include <linux/ipc_namespace.h>
 36 #include <linux/user_namespace.h>
 37 #include <linux/slab.h>
 38 
 39 #include <net/sock.h>
 40 #include "util.h"
 41 
 42 #define MQUEUE_MAGIC    0x19800202
 43 #define DIRENT_SIZE     20
 44 #define FILENT_SIZE     80
 45 
 46 #define SEND            0
 47 #define RECV            1
 48 
 49 #define STATE_NONE      0
 50 #define STATE_READY     1
 51 
 52 struct posix_msg_tree_node {
 53         struct rb_node          rb_node;
 54         struct list_head        msg_list;
 55         int                     priority;
 56 };
 57 
 58 struct ext_wait_queue {         /* queue of sleeping tasks */
 59         struct task_struct *task;
 60         struct list_head list;
 61         struct msg_msg *msg;    /* ptr of loaded message */
 62         int state;              /* one of STATE_* values */
 63 };
 64 
 65 struct mqueue_inode_info {
 66         spinlock_t lock;
 67         struct inode vfs_inode;
 68         wait_queue_head_t wait_q;
 69 
 70         struct rb_root msg_tree;
 71         struct posix_msg_tree_node *node_cache;
 72         struct mq_attr attr;
 73 
 74         struct sigevent notify;
 75         struct pid *notify_owner;
 76         struct user_namespace *notify_user_ns;
 77         struct user_struct *user;       /* user who created, for accounting */
 78         struct sock *notify_sock;
 79         struct sk_buff *notify_cookie;
 80 
 81         /* for tasks waiting for free space and messages, respectively */
 82         struct ext_wait_queue e_wait_q[2];
 83 
 84         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
 85 };
 86 
 87 static const struct inode_operations mqueue_dir_inode_operations;
 88 static const struct file_operations mqueue_file_operations;
 89 static const struct super_operations mqueue_super_ops;
 90 static void remove_notification(struct mqueue_inode_info *info);
 91 
 92 static struct kmem_cache *mqueue_inode_cachep;
 93 
 94 static struct ctl_table_header *mq_sysctl_table;
 95 
 96 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
 97 {
 98         return container_of(inode, struct mqueue_inode_info, vfs_inode);
 99 }
100 
101 /*
102  * This routine should be called with the mq_lock held.
103  */
104 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
105 {
106         return get_ipc_ns(inode->i_sb->s_fs_info);
107 }
108 
109 static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
110 {
111         struct ipc_namespace *ns;
112 
113         spin_lock(&mq_lock);
114         ns = __get_ns_from_inode(inode);
115         spin_unlock(&mq_lock);
116         return ns;
117 }
118 
119 /* Auxiliary functions to manipulate messages' list */
120 static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
121 {
122         struct rb_node **p, *parent = NULL;
123         struct posix_msg_tree_node *leaf;
124 
125         p = &info->msg_tree.rb_node;
126         while (*p) {
127                 parent = *p;
128                 leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
129 
130                 if (likely(leaf->priority == msg->m_type))
131                         goto insert_msg;
132                 else if (msg->m_type < leaf->priority)
133                         p = &(*p)->rb_left;
134                 else
135                         p = &(*p)->rb_right;
136         }
137         if (info->node_cache) {
138                 leaf = info->node_cache;
139                 info->node_cache = NULL;
140         } else {
141                 leaf = kmalloc(sizeof(*leaf), GFP_ATOMIC);
142                 if (!leaf)
143                         return -ENOMEM;
144                 INIT_LIST_HEAD(&leaf->msg_list);
145         }
146         leaf->priority = msg->m_type;
147         rb_link_node(&leaf->rb_node, parent, p);
148         rb_insert_color(&leaf->rb_node, &info->msg_tree);
149 insert_msg:
150         info->attr.mq_curmsgs++;
151         info->qsize += msg->m_ts;
152         list_add_tail(&msg->m_list, &leaf->msg_list);
153         return 0;
154 }
155 
156 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
157 {
158         struct rb_node **p, *parent = NULL;
159         struct posix_msg_tree_node *leaf;
160         struct msg_msg *msg;
161 
162 try_again:
163         p = &info->msg_tree.rb_node;
164         while (*p) {
165                 parent = *p;
166                 /*
167                  * During insert, low priorities go to the left and high to the
168                  * right.  On receive, we want the highest priorities first, so
169                  * walk all the way to the right.
170                  */
171                 p = &(*p)->rb_right;
172         }
173         if (!parent) {
174                 if (info->attr.mq_curmsgs) {
175                         pr_warn_once("Inconsistency in POSIX message queue, "
176                                      "no tree element, but supposedly messages "
177                                      "should exist!\n");
178                         info->attr.mq_curmsgs = 0;
179                 }
180                 return NULL;
181         }
182         leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
183         if (unlikely(list_empty(&leaf->msg_list))) {
184                 pr_warn_once("Inconsistency in POSIX message queue, "
185                              "empty leaf node but we haven't implemented "
186                              "lazy leaf delete!\n");
187                 rb_erase(&leaf->rb_node, &info->msg_tree);
188                 if (info->node_cache) {
189                         kfree(leaf);
190                 } else {
191                         info->node_cache = leaf;
192                 }
193                 goto try_again;
194         } else {
195                 msg = list_first_entry(&leaf->msg_list,
196                                        struct msg_msg, m_list);
197                 list_del(&msg->m_list);
198                 if (list_empty(&leaf->msg_list)) {
199                         rb_erase(&leaf->rb_node, &info->msg_tree);
200                         if (info->node_cache) {
201                                 kfree(leaf);
202                         } else {
203                                 info->node_cache = leaf;
204                         }
205                 }
206         }
207         info->attr.mq_curmsgs--;
208         info->qsize -= msg->m_ts;
209         return msg;
210 }
211 
212 static struct inode *mqueue_get_inode(struct super_block *sb,
213                 struct ipc_namespace *ipc_ns, umode_t mode,
214                 struct mq_attr *attr)
215 {
216         struct user_struct *u = current_user();
217         struct inode *inode;
218         int ret = -ENOMEM;
219 
220         inode = new_inode(sb);
221         if (!inode)
222                 goto err;
223 
224         inode->i_ino = get_next_ino();
225         inode->i_mode = mode;
226         inode->i_uid = current_fsuid();
227         inode->i_gid = current_fsgid();
228         inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
229 
230         if (S_ISREG(mode)) {
231                 struct mqueue_inode_info *info;
232                 unsigned long mq_bytes, mq_treesize;
233 
234                 inode->i_fop = &mqueue_file_operations;
235                 inode->i_size = FILENT_SIZE;
236                 /* mqueue specific info */
237                 info = MQUEUE_I(inode);
238                 spin_lock_init(&info->lock);
239                 init_waitqueue_head(&info->wait_q);
240                 INIT_LIST_HEAD(&info->e_wait_q[0].list);
241                 INIT_LIST_HEAD(&info->e_wait_q[1].list);
242                 info->notify_owner = NULL;
243                 info->notify_user_ns = NULL;
244                 info->qsize = 0;
245                 info->user = NULL;      /* set when all is ok */
246                 info->msg_tree = RB_ROOT;
247                 info->node_cache = NULL;
248                 memset(&info->attr, 0, sizeof(info->attr));
249                 info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
250                                            ipc_ns->mq_msg_default);
251                 info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
252                                             ipc_ns->mq_msgsize_default);
253                 if (attr) {
254                         info->attr.mq_maxmsg = attr->mq_maxmsg;
255                         info->attr.mq_msgsize = attr->mq_msgsize;
256                 }
257                 /*
258                  * We used to allocate a static array of pointers and account
259                  * the size of that array as well as one msg_msg struct per
260                  * possible message into the queue size. That's no longer
261                  * accurate as the queue is now an rbtree and will grow and
262                  * shrink depending on usage patterns.  We can, however, still
263                  * account one msg_msg struct per message, but the nodes are
264                  * allocated depending on priority usage, and most programs
265                  * only use one, or a handful, of priorities.  However, since
266                  * this is pinned memory, we need to assume worst case, so
267                  * that means the min(mq_maxmsg, max_priorities) * struct
268                  * posix_msg_tree_node.
269                  */
270                 mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
271                         min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
272                         sizeof(struct posix_msg_tree_node);
273 
274                 mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
275                                           info->attr.mq_msgsize);
276 
277                 spin_lock(&mq_lock);
278                 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
279                     u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
280                         spin_unlock(&mq_lock);
281                         /* mqueue_evict_inode() releases info->messages */
282                         ret = -EMFILE;
283                         goto out_inode;
284                 }
285                 u->mq_bytes += mq_bytes;
286                 spin_unlock(&mq_lock);
287 
288                 /* all is ok */
289                 info->user = get_uid(u);
290         } else if (S_ISDIR(mode)) {
291                 inc_nlink(inode);
292                 /* Some things misbehave if size == 0 on a directory */
293                 inode->i_size = 2 * DIRENT_SIZE;
294                 inode->i_op = &mqueue_dir_inode_operations;
295                 inode->i_fop = &simple_dir_operations;
296         }
297 
298         return inode;
299 out_inode:
300         iput(inode);
301 err:
302         return ERR_PTR(ret);
303 }
304 
305 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
306 {
307         struct inode *inode;
308         struct ipc_namespace *ns = data;
309 
310         sb->s_blocksize = PAGE_CACHE_SIZE;
311         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
312         sb->s_magic = MQUEUE_MAGIC;
313         sb->s_op = &mqueue_super_ops;
314 
315         inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
316         if (IS_ERR(inode))
317                 return PTR_ERR(inode);
318 
319         sb->s_root = d_make_root(inode);
320         if (!sb->s_root)
321                 return -ENOMEM;
322         return 0;
323 }
324 
325 static struct dentry *mqueue_mount(struct file_system_type *fs_type,
326                          int flags, const char *dev_name,
327                          void *data)
328 {
329         if (!(flags & MS_KERNMOUNT)) {
330                 struct ipc_namespace *ns = current->nsproxy->ipc_ns;
331                 /* Don't allow mounting unless the caller has CAP_SYS_ADMIN
332                  * over the ipc namespace.
333                  */
334                 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
335                         return ERR_PTR(-EPERM);
336 
337                 data = ns;
338         }
339         return mount_ns(fs_type, flags, data, mqueue_fill_super);
340 }
341 
342 static void init_once(void *foo)
343 {
344         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
345 
346         inode_init_once(&p->vfs_inode);
347 }
348 
349 static struct inode *mqueue_alloc_inode(struct super_block *sb)
350 {
351         struct mqueue_inode_info *ei;
352 
353         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
354         if (!ei)
355                 return NULL;
356         return &ei->vfs_inode;
357 }
358 
359 static void mqueue_i_callback(struct rcu_head *head)
360 {
361         struct inode *inode = container_of(head, struct inode, i_rcu);
362         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
363 }
364 
365 static void mqueue_destroy_inode(struct inode *inode)
366 {
367         call_rcu(&inode->i_rcu, mqueue_i_callback);
368 }
369 
370 static void mqueue_evict_inode(struct inode *inode)
371 {
372         struct mqueue_inode_info *info;
373         struct user_struct *user;
374         unsigned long mq_bytes, mq_treesize;
375         struct ipc_namespace *ipc_ns;
376         struct msg_msg *msg;
377 
378         clear_inode(inode);
379 
380         if (S_ISDIR(inode->i_mode))
381                 return;
382 
383         ipc_ns = get_ns_from_inode(inode);
384         info = MQUEUE_I(inode);
385         spin_lock(&info->lock);
386         while ((msg = msg_get(info)) != NULL)
387                 free_msg(msg);
388         kfree(info->node_cache);
389         spin_unlock(&info->lock);
390 
391         /* Total amount of bytes accounted for the mqueue */
392         mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
393                 min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
394                 sizeof(struct posix_msg_tree_node);
395 
396         mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
397                                   info->attr.mq_msgsize);
398 
399         user = info->user;
400         if (user) {
401                 spin_lock(&mq_lock);
402                 user->mq_bytes -= mq_bytes;
403                 /*
404                  * get_ns_from_inode() ensures that the
405                  * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
406                  * to which we now hold a reference, or it is NULL.
407                  * We can't put it here under mq_lock, though.
408                  */
409                 if (ipc_ns)
410                         ipc_ns->mq_queues_count--;
411                 spin_unlock(&mq_lock);
412                 free_uid(user);
413         }
414         if (ipc_ns)
415                 put_ipc_ns(ipc_ns);
416 }
417 
418 static int mqueue_create(struct inode *dir, struct dentry *dentry,
419                                 umode_t mode, bool excl)
420 {
421         struct inode *inode;
422         struct mq_attr *attr = dentry->d_fsdata;
423         int error;
424         struct ipc_namespace *ipc_ns;
425 
426         spin_lock(&mq_lock);
427         ipc_ns = __get_ns_from_inode(dir);
428         if (!ipc_ns) {
429                 error = -EACCES;
430                 goto out_unlock;
431         }
432 
433         if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
434             !capable(CAP_SYS_RESOURCE)) {
435                 error = -ENOSPC;
436                 goto out_unlock;
437         }
438         ipc_ns->mq_queues_count++;
439         spin_unlock(&mq_lock);
440 
441         inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
442         if (IS_ERR(inode)) {
443                 error = PTR_ERR(inode);
444                 spin_lock(&mq_lock);
445                 ipc_ns->mq_queues_count--;
446                 goto out_unlock;
447         }
448 
449         put_ipc_ns(ipc_ns);
450         dir->i_size += DIRENT_SIZE;
451         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
452 
453         d_instantiate(dentry, inode);
454         dget(dentry);
455         return 0;
456 out_unlock:
457         spin_unlock(&mq_lock);
458         if (ipc_ns)
459                 put_ipc_ns(ipc_ns);
460         return error;
461 }
462 
463 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
464 {
465         struct inode *inode = d_inode(dentry);
466 
467         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
468         dir->i_size -= DIRENT_SIZE;
469         drop_nlink(inode);
470         dput(dentry);
471         return 0;
472 }
473 
474 /*
475 *       This is routine for system read from queue file.
476 *       To avoid mess with doing here some sort of mq_receive we allow
477 *       to read only queue size & notification info (the only values
478 *       that are interesting from user point of view and aren't accessible
479 *       through std routines)
480 */
481 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
482                                 size_t count, loff_t *off)
483 {
484         struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
485         char buffer[FILENT_SIZE];
486         ssize_t ret;
487 
488         spin_lock(&info->lock);
489         snprintf(buffer, sizeof(buffer),
490                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
491                         info->qsize,
492                         info->notify_owner ? info->notify.sigev_notify : 0,
493                         (info->notify_owner &&
494                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
495                                 info->notify.sigev_signo : 0,
496                         pid_vnr(info->notify_owner));
497         spin_unlock(&info->lock);
498         buffer[sizeof(buffer)-1] = '\0';
499 
500         ret = simple_read_from_buffer(u_data, count, off, buffer,
501                                 strlen(buffer));
502         if (ret <= 0)
503                 return ret;
504 
505         file_inode(filp)->i_atime = file_inode(filp)->i_ctime = CURRENT_TIME;
506         return ret;
507 }
508 
509 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
510 {
511         struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
512 
513         spin_lock(&info->lock);
514         if (task_tgid(current) == info->notify_owner)
515                 remove_notification(info);
516 
517         spin_unlock(&info->lock);
518         return 0;
519 }
520 
521 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
522 {
523         struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
524         int retval = 0;
525 
526         poll_wait(filp, &info->wait_q, poll_tab);
527 
528         spin_lock(&info->lock);
529         if (info->attr.mq_curmsgs)
530                 retval = POLLIN | POLLRDNORM;
531 
532         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
533                 retval |= POLLOUT | POLLWRNORM;
534         spin_unlock(&info->lock);
535 
536         return retval;
537 }
538 
539 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
540 static void wq_add(struct mqueue_inode_info *info, int sr,
541                         struct ext_wait_queue *ewp)
542 {
543         struct ext_wait_queue *walk;
544 
545         ewp->task = current;
546 
547         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
548                 if (walk->task->static_prio <= current->static_prio) {
549                         list_add_tail(&ewp->list, &walk->list);
550                         return;
551                 }
552         }
553         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
554 }
555 
556 /*
557  * Puts current task to sleep. Caller must hold queue lock. After return
558  * lock isn't held.
559  * sr: SEND or RECV
560  */
561 static int wq_sleep(struct mqueue_inode_info *info, int sr,
562                     ktime_t *timeout, struct ext_wait_queue *ewp)
563 {
564         int retval;
565         signed long time;
566 
567         wq_add(info, sr, ewp);
568 
569         for (;;) {
570                 __set_current_state(TASK_INTERRUPTIBLE);
571 
572                 spin_unlock(&info->lock);
573                 time = schedule_hrtimeout_range_clock(timeout, 0,
574                         HRTIMER_MODE_ABS, CLOCK_REALTIME);
575 
576                 if (ewp->state == STATE_READY) {
577                         retval = 0;
578                         goto out;
579                 }
580                 spin_lock(&info->lock);
581                 if (ewp->state == STATE_READY) {
582                         retval = 0;
583                         goto out_unlock;
584                 }
585                 if (signal_pending(current)) {
586                         retval = -ERESTARTSYS;
587                         break;
588                 }
589                 if (time == 0) {
590                         retval = -ETIMEDOUT;
591                         break;
592                 }
593         }
594         list_del(&ewp->list);
595 out_unlock:
596         spin_unlock(&info->lock);
597 out:
598         return retval;
599 }
600 
601 /*
602  * Returns waiting task that should be serviced first or NULL if none exists
603  */
604 static struct ext_wait_queue *wq_get_first_waiter(
605                 struct mqueue_inode_info *info, int sr)
606 {
607         struct list_head *ptr;
608 
609         ptr = info->e_wait_q[sr].list.prev;
610         if (ptr == &info->e_wait_q[sr].list)
611                 return NULL;
612         return list_entry(ptr, struct ext_wait_queue, list);
613 }
614 
615 
616 static inline void set_cookie(struct sk_buff *skb, char code)
617 {
618         ((char *)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
619 }
620 
621 /*
622  * The next function is only to split too long sys_mq_timedsend
623  */
624 static void __do_notify(struct mqueue_inode_info *info)
625 {
626         /* notification
627          * invoked when there is registered process and there isn't process
628          * waiting synchronously for message AND state of queue changed from
629          * empty to not empty. Here we are sure that no one is waiting
630          * synchronously. */
631         if (info->notify_owner &&
632             info->attr.mq_curmsgs == 1) {
633                 struct siginfo sig_i;
634                 switch (info->notify.sigev_notify) {
635                 case SIGEV_NONE:
636                         break;
637                 case SIGEV_SIGNAL:
638                         /* sends signal */
639 
640                         sig_i.si_signo = info->notify.sigev_signo;
641                         sig_i.si_errno = 0;
642                         sig_i.si_code = SI_MESGQ;
643                         sig_i.si_value = info->notify.sigev_value;
644                         /* map current pid/uid into info->owner's namespaces */
645                         rcu_read_lock();
646                         sig_i.si_pid = task_tgid_nr_ns(current,
647                                                 ns_of_pid(info->notify_owner));
648                         sig_i.si_uid = from_kuid_munged(info->notify_user_ns, current_uid());
649                         rcu_read_unlock();
650 
651                         kill_pid_info(info->notify.sigev_signo,
652                                       &sig_i, info->notify_owner);
653                         break;
654                 case SIGEV_THREAD:
655                         set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
656                         netlink_sendskb(info->notify_sock, info->notify_cookie);
657                         break;
658                 }
659                 /* after notification unregisters process */
660                 put_pid(info->notify_owner);
661                 put_user_ns(info->notify_user_ns);
662                 info->notify_owner = NULL;
663                 info->notify_user_ns = NULL;
664         }
665         wake_up(&info->wait_q);
666 }
667 
668 static int prepare_timeout(const struct timespec __user *u_abs_timeout,
669                            ktime_t *expires, struct timespec *ts)
670 {
671         if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
672                 return -EFAULT;
673         if (!timespec_valid(ts))
674                 return -EINVAL;
675 
676         *expires = timespec_to_ktime(*ts);
677         return 0;
678 }
679 
680 static void remove_notification(struct mqueue_inode_info *info)
681 {
682         if (info->notify_owner != NULL &&
683             info->notify.sigev_notify == SIGEV_THREAD) {
684                 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
685                 netlink_sendskb(info->notify_sock, info->notify_cookie);
686         }
687         put_pid(info->notify_owner);
688         put_user_ns(info->notify_user_ns);
689         info->notify_owner = NULL;
690         info->notify_user_ns = NULL;
691 }
692 
693 static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
694 {
695         int mq_treesize;
696         unsigned long total_size;
697 
698         if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
699                 return -EINVAL;
700         if (capable(CAP_SYS_RESOURCE)) {
701                 if (attr->mq_maxmsg > HARD_MSGMAX ||
702                     attr->mq_msgsize > HARD_MSGSIZEMAX)
703                         return -EINVAL;
704         } else {
705                 if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
706                                 attr->mq_msgsize > ipc_ns->mq_msgsize_max)
707                         return -EINVAL;
708         }
709         /* check for overflow */
710         if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
711                 return -EOVERFLOW;
712         mq_treesize = attr->mq_maxmsg * sizeof(struct msg_msg) +
713                 min_t(unsigned int, attr->mq_maxmsg, MQ_PRIO_MAX) *
714                 sizeof(struct posix_msg_tree_node);
715         total_size = attr->mq_maxmsg * attr->mq_msgsize;
716         if (total_size + mq_treesize < total_size)
717                 return -EOVERFLOW;
718         return 0;
719 }
720 
721 /*
722  * Invoked when creating a new queue via sys_mq_open
723  */
724 static struct file *do_create(struct ipc_namespace *ipc_ns, struct inode *dir,
725                         struct path *path, int oflag, umode_t mode,
726                         struct mq_attr *attr)
727 {
728         const struct cred *cred = current_cred();
729         int ret;
730 
731         if (attr) {
732                 ret = mq_attr_ok(ipc_ns, attr);
733                 if (ret)
734                         return ERR_PTR(ret);
735                 /* store for use during create */
736                 path->dentry->d_fsdata = attr;
737         } else {
738                 struct mq_attr def_attr;
739 
740                 def_attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
741                                          ipc_ns->mq_msg_default);
742                 def_attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
743                                           ipc_ns->mq_msgsize_default);
744                 ret = mq_attr_ok(ipc_ns, &def_attr);
745                 if (ret)
746                         return ERR_PTR(ret);
747         }
748 
749         mode &= ~current_umask();
750         ret = vfs_create(dir, path->dentry, mode, true);
751         path->dentry->d_fsdata = NULL;
752         if (ret)
753                 return ERR_PTR(ret);
754         return dentry_open(path, oflag, cred);
755 }
756 
757 /* Opens existing queue */
758 static struct file *do_open(struct path *path, int oflag)
759 {
760         static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
761                                                   MAY_READ | MAY_WRITE };
762         int acc;
763         if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
764                 return ERR_PTR(-EINVAL);
765         acc = oflag2acc[oflag & O_ACCMODE];
766         if (inode_permission(d_inode(path->dentry), acc))
767                 return ERR_PTR(-EACCES);
768         return dentry_open(path, oflag, current_cred());
769 }
770 
771 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
772                 struct mq_attr __user *, u_attr)
773 {
774         struct path path;
775         struct file *filp;
776         struct filename *name;
777         struct mq_attr attr;
778         int fd, error;
779         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
780         struct vfsmount *mnt = ipc_ns->mq_mnt;
781         struct dentry *root = mnt->mnt_root;
782         int ro;
783 
784         if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
785                 return -EFAULT;
786 
787         audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
788 
789         if (IS_ERR(name = getname(u_name)))
790                 return PTR_ERR(name);
791 
792         fd = get_unused_fd_flags(O_CLOEXEC);
793         if (fd < 0)
794                 goto out_putname;
795 
796         ro = mnt_want_write(mnt);       /* we'll drop it in any case */
797         error = 0;
798         mutex_lock(&d_inode(root)->i_mutex);
799         path.dentry = lookup_one_len(name->name, root, strlen(name->name));
800         if (IS_ERR(path.dentry)) {
801                 error = PTR_ERR(path.dentry);
802                 goto out_putfd;
803         }
804         path.mnt = mntget(mnt);
805 
806         if (oflag & O_CREAT) {
807                 if (d_really_is_positive(path.dentry)) {        /* entry already exists */
808                         audit_inode(name, path.dentry, 0);
809                         if (oflag & O_EXCL) {
810                                 error = -EEXIST;
811                                 goto out;
812                         }
813                         filp = do_open(&path, oflag);
814                 } else {
815                         if (ro) {
816                                 error = ro;
817                                 goto out;
818                         }
819                         audit_inode_parent_hidden(name, root);
820                         filp = do_create(ipc_ns, d_inode(root),
821                                                 &path, oflag, mode,
822                                                 u_attr ? &attr : NULL);
823                 }
824         } else {
825                 if (d_really_is_negative(path.dentry)) {
826                         error = -ENOENT;
827                         goto out;
828                 }
829                 audit_inode(name, path.dentry, 0);
830                 filp = do_open(&path, oflag);
831         }
832 
833         if (!IS_ERR(filp))
834                 fd_install(fd, filp);
835         else
836                 error = PTR_ERR(filp);
837 out:
838         path_put(&path);
839 out_putfd:
840         if (error) {
841                 put_unused_fd(fd);
842                 fd = error;
843         }
844         mutex_unlock(&d_inode(root)->i_mutex);
845         if (!ro)
846                 mnt_drop_write(mnt);
847 out_putname:
848         putname(name);
849         return fd;
850 }
851 
852 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
853 {
854         int err;
855         struct filename *name;
856         struct dentry *dentry;
857         struct inode *inode = NULL;
858         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
859         struct vfsmount *mnt = ipc_ns->mq_mnt;
860 
861         name = getname(u_name);
862         if (IS_ERR(name))
863                 return PTR_ERR(name);
864 
865         audit_inode_parent_hidden(name, mnt->mnt_root);
866         err = mnt_want_write(mnt);
867         if (err)
868                 goto out_name;
869         mutex_lock_nested(&d_inode(mnt->mnt_root)->i_mutex, I_MUTEX_PARENT);
870         dentry = lookup_one_len(name->name, mnt->mnt_root,
871                                 strlen(name->name));
872         if (IS_ERR(dentry)) {
873                 err = PTR_ERR(dentry);
874                 goto out_unlock;
875         }
876 
877         inode = d_inode(dentry);
878         if (!inode) {
879                 err = -ENOENT;
880         } else {
881                 ihold(inode);
882                 err = vfs_unlink(d_inode(dentry->d_parent), dentry, NULL);
883         }
884         dput(dentry);
885 
886 out_unlock:
887         mutex_unlock(&d_inode(mnt->mnt_root)->i_mutex);
888         if (inode)
889                 iput(inode);
890         mnt_drop_write(mnt);
891 out_name:
892         putname(name);
893 
894         return err;
895 }
896 
897 /* Pipelined send and receive functions.
898  *
899  * If a receiver finds no waiting message, then it registers itself in the
900  * list of waiting receivers. A sender checks that list before adding the new
901  * message into the message array. If there is a waiting receiver, then it
902  * bypasses the message array and directly hands the message over to the
903  * receiver. The receiver accepts the message and returns without grabbing the
904  * queue spinlock:
905  *
906  * - Set pointer to message.
907  * - Queue the receiver task for later wakeup (without the info->lock).
908  * - Update its state to STATE_READY. Now the receiver can continue.
909  * - Wake up the process after the lock is dropped. Should the process wake up
910  *   before this wakeup (due to a timeout or a signal) it will either see
911  *   STATE_READY and continue or acquire the lock to check the state again.
912  *
913  * The same algorithm is used for senders.
914  */
915 
916 /* pipelined_send() - send a message directly to the task waiting in
917  * sys_mq_timedreceive() (without inserting message into a queue).
918  */
919 static inline void pipelined_send(struct wake_q_head *wake_q,
920                                   struct mqueue_inode_info *info,
921                                   struct msg_msg *message,
922                                   struct ext_wait_queue *receiver)
923 {
924         receiver->msg = message;
925         list_del(&receiver->list);
926         wake_q_add(wake_q, receiver->task);
927         /*
928          * Rely on the implicit cmpxchg barrier from wake_q_add such
929          * that we can ensure that updating receiver->state is the last
930          * write operation: As once set, the receiver can continue,
931          * and if we don't have the reference count from the wake_q,
932          * yet, at that point we can later have a use-after-free
933          * condition and bogus wakeup.
934          */
935         receiver->state = STATE_READY;
936 }
937 
938 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
939  * gets its message and put to the queue (we have one free place for sure). */
940 static inline void pipelined_receive(struct wake_q_head *wake_q,
941                                      struct mqueue_inode_info *info)
942 {
943         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
944 
945         if (!sender) {
946                 /* for poll */
947                 wake_up_interruptible(&info->wait_q);
948                 return;
949         }
950         if (msg_insert(sender->msg, info))
951                 return;
952 
953         list_del(&sender->list);
954         wake_q_add(wake_q, sender->task);
955         sender->state = STATE_READY;
956 }
957 
958 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
959                 size_t, msg_len, unsigned int, msg_prio,
960                 const struct timespec __user *, u_abs_timeout)
961 {
962         struct fd f;
963         struct inode *inode;
964         struct ext_wait_queue wait;
965         struct ext_wait_queue *receiver;
966         struct msg_msg *msg_ptr;
967         struct mqueue_inode_info *info;
968         ktime_t expires, *timeout = NULL;
969         struct timespec ts;
970         struct posix_msg_tree_node *new_leaf = NULL;
971         int ret = 0;
972         WAKE_Q(wake_q);
973 
974         if (u_abs_timeout) {
975                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
976                 if (res)
977                         return res;
978                 timeout = &expires;
979         }
980 
981         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
982                 return -EINVAL;
983 
984         audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
985 
986         f = fdget(mqdes);
987         if (unlikely(!f.file)) {
988                 ret = -EBADF;
989                 goto out;
990         }
991 
992         inode = file_inode(f.file);
993         if (unlikely(f.file->f_op != &mqueue_file_operations)) {
994                 ret = -EBADF;
995                 goto out_fput;
996         }
997         info = MQUEUE_I(inode);
998         audit_file(f.file);
999 
1000         if (unlikely(!(f.file->f_mode & FMODE_WRITE))) {
1001                 ret = -EBADF;
1002                 goto out_fput;
1003         }
1004 
1005         if (unlikely(msg_len > info->attr.mq_msgsize)) {
1006                 ret = -EMSGSIZE;
1007                 goto out_fput;
1008         }
1009 
1010         /* First try to allocate memory, before doing anything with
1011          * existing queues. */
1012         msg_ptr = load_msg(u_msg_ptr, msg_len);
1013         if (IS_ERR(msg_ptr)) {
1014                 ret = PTR_ERR(msg_ptr);
1015                 goto out_fput;
1016         }
1017         msg_ptr->m_ts = msg_len;
1018         msg_ptr->m_type = msg_prio;
1019 
1020         /*
1021          * msg_insert really wants us to have a valid, spare node struct so
1022          * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1023          * fall back to that if necessary.
1024          */
1025         if (!info->node_cache)
1026                 new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1027 
1028         spin_lock(&info->lock);
1029 
1030         if (!info->node_cache && new_leaf) {
1031                 /* Save our speculative allocation into the cache */
1032                 INIT_LIST_HEAD(&new_leaf->msg_list);
1033                 info->node_cache = new_leaf;
1034                 new_leaf = NULL;
1035         } else {
1036                 kfree(new_leaf);
1037         }
1038 
1039         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
1040                 if (f.file->f_flags & O_NONBLOCK) {
1041                         ret = -EAGAIN;
1042                 } else {
1043                         wait.task = current;
1044                         wait.msg = (void *) msg_ptr;
1045                         wait.state = STATE_NONE;
1046                         ret = wq_sleep(info, SEND, timeout, &wait);
1047                         /*
1048                          * wq_sleep must be called with info->lock held, and
1049                          * returns with the lock released
1050                          */
1051                         goto out_free;
1052                 }
1053         } else {
1054                 receiver = wq_get_first_waiter(info, RECV);
1055                 if (receiver) {
1056                         pipelined_send(&wake_q, info, msg_ptr, receiver);
1057                 } else {
1058                         /* adds message to the queue */
1059                         ret = msg_insert(msg_ptr, info);
1060                         if (ret)
1061                                 goto out_unlock;
1062                         __do_notify(info);
1063                 }
1064                 inode->i_atime = inode->i_mtime = inode->i_ctime =
1065                                 CURRENT_TIME;
1066         }
1067 out_unlock:
1068         spin_unlock(&info->lock);
1069         wake_up_q(&wake_q);
1070 out_free:
1071         if (ret)
1072                 free_msg(msg_ptr);
1073 out_fput:
1074         fdput(f);
1075 out:
1076         return ret;
1077 }
1078 
1079 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
1080                 size_t, msg_len, unsigned int __user *, u_msg_prio,
1081                 const struct timespec __user *, u_abs_timeout)
1082 {
1083         ssize_t ret;
1084         struct msg_msg *msg_ptr;
1085         struct fd f;
1086         struct inode *inode;
1087         struct mqueue_inode_info *info;
1088         struct ext_wait_queue wait;
1089         ktime_t expires, *timeout = NULL;
1090         struct timespec ts;
1091         struct posix_msg_tree_node *new_leaf = NULL;
1092 
1093         if (u_abs_timeout) {
1094                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
1095                 if (res)
1096                         return res;
1097                 timeout = &expires;
1098         }
1099 
1100         audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
1101 
1102         f = fdget(mqdes);
1103         if (unlikely(!f.file)) {
1104                 ret = -EBADF;
1105                 goto out;
1106         }
1107 
1108         inode = file_inode(f.file);
1109         if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1110                 ret = -EBADF;
1111                 goto out_fput;
1112         }
1113         info = MQUEUE_I(inode);
1114         audit_file(f.file);
1115 
1116         if (unlikely(!(f.file->f_mode & FMODE_READ))) {
1117                 ret = -EBADF;
1118                 goto out_fput;
1119         }
1120 
1121         /* checks if buffer is big enough */
1122         if (unlikely(msg_len < info->attr.mq_msgsize)) {
1123                 ret = -EMSGSIZE;
1124                 goto out_fput;
1125         }
1126 
1127         /*
1128          * msg_insert really wants us to have a valid, spare node struct so
1129          * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1130          * fall back to that if necessary.
1131          */
1132         if (!info->node_cache)
1133                 new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1134 
1135         spin_lock(&info->lock);
1136 
1137         if (!info->node_cache && new_leaf) {
1138                 /* Save our speculative allocation into the cache */
1139                 INIT_LIST_HEAD(&new_leaf->msg_list);
1140                 info->node_cache = new_leaf;
1141         } else {
1142                 kfree(new_leaf);
1143         }
1144 
1145         if (info->attr.mq_curmsgs == 0) {
1146                 if (f.file->f_flags & O_NONBLOCK) {
1147                         spin_unlock(&info->lock);
1148                         ret = -EAGAIN;
1149                 } else {
1150                         wait.task = current;
1151                         wait.state = STATE_NONE;
1152                         ret = wq_sleep(info, RECV, timeout, &wait);
1153                         msg_ptr = wait.msg;
1154                 }
1155         } else {
1156                 WAKE_Q(wake_q);
1157 
1158                 msg_ptr = msg_get(info);
1159 
1160                 inode->i_atime = inode->i_mtime = inode->i_ctime =
1161                                 CURRENT_TIME;
1162 
1163                 /* There is now free space in queue. */
1164                 pipelined_receive(&wake_q, info);
1165                 spin_unlock(&info->lock);
1166                 wake_up_q(&wake_q);
1167                 ret = 0;
1168         }
1169         if (ret == 0) {
1170                 ret = msg_ptr->m_ts;
1171 
1172                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1173                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1174                         ret = -EFAULT;
1175                 }
1176                 free_msg(msg_ptr);
1177         }
1178 out_fput:
1179         fdput(f);
1180 out:
1181         return ret;
1182 }
1183 
1184 /*
1185  * Notes: the case when user wants us to deregister (with NULL as pointer)
1186  * and he isn't currently owner of notification, will be silently discarded.
1187  * It isn't explicitly defined in the POSIX.
1188  */
1189 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1190                 const struct sigevent __user *, u_notification)
1191 {
1192         int ret;
1193         struct fd f;
1194         struct sock *sock;
1195         struct inode *inode;
1196         struct sigevent notification;
1197         struct mqueue_inode_info *info;
1198         struct sk_buff *nc;
1199 
1200         if (u_notification) {
1201                 if (copy_from_user(&notification, u_notification,
1202                                         sizeof(struct sigevent)))
1203                         return -EFAULT;
1204         }
1205 
1206         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1207 
1208         nc = NULL;
1209         sock = NULL;
1210         if (u_notification != NULL) {
1211                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1212                              notification.sigev_notify != SIGEV_SIGNAL &&
1213                              notification.sigev_notify != SIGEV_THREAD))
1214                         return -EINVAL;
1215                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1216                         !valid_signal(notification.sigev_signo)) {
1217                         return -EINVAL;
1218                 }
1219                 if (notification.sigev_notify == SIGEV_THREAD) {
1220                         long timeo;
1221 
1222                         /* create the notify skb */
1223                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1224                         if (!nc) {
1225                                 ret = -ENOMEM;
1226                                 goto out;
1227                         }
1228                         if (copy_from_user(nc->data,
1229                                         notification.sigev_value.sival_ptr,
1230                                         NOTIFY_COOKIE_LEN)) {
1231                                 ret = -EFAULT;
1232                                 goto out;
1233                         }
1234 
1235                         /* TODO: add a header? */
1236                         skb_put(nc, NOTIFY_COOKIE_LEN);
1237                         /* and attach it to the socket */
1238 retry:
1239                         f = fdget(notification.sigev_signo);
1240                         if (!f.file) {
1241                                 ret = -EBADF;
1242                                 goto out;
1243                         }
1244                         sock = netlink_getsockbyfilp(f.file);
1245                         fdput(f);
1246                         if (IS_ERR(sock)) {
1247                                 ret = PTR_ERR(sock);
1248                                 sock = NULL;
1249                                 goto out;
1250                         }
1251 
1252                         timeo = MAX_SCHEDULE_TIMEOUT;
1253                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1254                         if (ret == 1)
1255                                 goto retry;
1256                         if (ret) {
1257                                 sock = NULL;
1258                                 nc = NULL;
1259                                 goto out;
1260                         }
1261                 }
1262         }
1263 
1264         f = fdget(mqdes);
1265         if (!f.file) {
1266                 ret = -EBADF;
1267                 goto out;
1268         }
1269 
1270         inode = file_inode(f.file);
1271         if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1272                 ret = -EBADF;
1273                 goto out_fput;
1274         }
1275         info = MQUEUE_I(inode);
1276 
1277         ret = 0;
1278         spin_lock(&info->lock);
1279         if (u_notification == NULL) {
1280                 if (info->notify_owner == task_tgid(current)) {
1281                         remove_notification(info);
1282                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1283                 }
1284         } else if (info->notify_owner != NULL) {
1285                 ret = -EBUSY;
1286         } else {
1287                 switch (notification.sigev_notify) {
1288                 case SIGEV_NONE:
1289                         info->notify.sigev_notify = SIGEV_NONE;
1290                         break;
1291                 case SIGEV_THREAD:
1292                         info->notify_sock = sock;
1293                         info->notify_cookie = nc;
1294                         sock = NULL;
1295                         nc = NULL;
1296                         info->notify.sigev_notify = SIGEV_THREAD;
1297                         break;
1298                 case SIGEV_SIGNAL:
1299                         info->notify.sigev_signo = notification.sigev_signo;
1300                         info->notify.sigev_value = notification.sigev_value;
1301                         info->notify.sigev_notify = SIGEV_SIGNAL;
1302                         break;
1303                 }
1304 
1305                 info->notify_owner = get_pid(task_tgid(current));
1306                 info->notify_user_ns = get_user_ns(current_user_ns());
1307                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1308         }
1309         spin_unlock(&info->lock);
1310 out_fput:
1311         fdput(f);
1312 out:
1313         if (sock)
1314                 netlink_detachskb(sock, nc);
1315         else if (nc)
1316                 dev_kfree_skb(nc);
1317 
1318         return ret;
1319 }
1320 
1321 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1322                 const struct mq_attr __user *, u_mqstat,
1323                 struct mq_attr __user *, u_omqstat)
1324 {
1325         int ret;
1326         struct mq_attr mqstat, omqstat;
1327         struct fd f;
1328         struct inode *inode;
1329         struct mqueue_inode_info *info;
1330 
1331         if (u_mqstat != NULL) {
1332                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1333                         return -EFAULT;
1334                 if (mqstat.mq_flags & (~O_NONBLOCK))
1335                         return -EINVAL;
1336         }
1337 
1338         f = fdget(mqdes);
1339         if (!f.file) {
1340                 ret = -EBADF;
1341                 goto out;
1342         }
1343 
1344         inode = file_inode(f.file);
1345         if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1346                 ret = -EBADF;
1347                 goto out_fput;
1348         }
1349         info = MQUEUE_I(inode);
1350 
1351         spin_lock(&info->lock);
1352 
1353         omqstat = info->attr;
1354         omqstat.mq_flags = f.file->f_flags & O_NONBLOCK;
1355         if (u_mqstat) {
1356                 audit_mq_getsetattr(mqdes, &mqstat);
1357                 spin_lock(&f.file->f_lock);
1358                 if (mqstat.mq_flags & O_NONBLOCK)
1359                         f.file->f_flags |= O_NONBLOCK;
1360                 else
1361                         f.file->f_flags &= ~O_NONBLOCK;
1362                 spin_unlock(&f.file->f_lock);
1363 
1364                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1365         }
1366 
1367         spin_unlock(&info->lock);
1368 
1369         ret = 0;
1370         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1371                                                 sizeof(struct mq_attr)))
1372                 ret = -EFAULT;
1373 
1374 out_fput:
1375         fdput(f);
1376 out:
1377         return ret;
1378 }
1379 
1380 static const struct inode_operations mqueue_dir_inode_operations = {
1381         .lookup = simple_lookup,
1382         .create = mqueue_create,
1383         .unlink = mqueue_unlink,
1384 };
1385 
1386 static const struct file_operations mqueue_file_operations = {
1387         .flush = mqueue_flush_file,
1388         .poll = mqueue_poll_file,
1389         .read = mqueue_read_file,
1390         .llseek = default_llseek,
1391 };
1392 
1393 static const struct super_operations mqueue_super_ops = {
1394         .alloc_inode = mqueue_alloc_inode,
1395         .destroy_inode = mqueue_destroy_inode,
1396         .evict_inode = mqueue_evict_inode,
1397         .statfs = simple_statfs,
1398 };
1399 
1400 static struct file_system_type mqueue_fs_type = {
1401         .name = "mqueue",
1402         .mount = mqueue_mount,
1403         .kill_sb = kill_litter_super,
1404         .fs_flags = FS_USERNS_MOUNT,
1405 };
1406 
1407 int mq_init_ns(struct ipc_namespace *ns)
1408 {
1409         ns->mq_queues_count  = 0;
1410         ns->mq_queues_max    = DFLT_QUEUESMAX;
1411         ns->mq_msg_max       = DFLT_MSGMAX;
1412         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1413         ns->mq_msg_default   = DFLT_MSG;
1414         ns->mq_msgsize_default  = DFLT_MSGSIZE;
1415 
1416         ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1417         if (IS_ERR(ns->mq_mnt)) {
1418                 int err = PTR_ERR(ns->mq_mnt);
1419                 ns->mq_mnt = NULL;
1420                 return err;
1421         }
1422         return 0;
1423 }
1424 
1425 void mq_clear_sbinfo(struct ipc_namespace *ns)
1426 {
1427         ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1428 }
1429 
1430 void mq_put_mnt(struct ipc_namespace *ns)
1431 {
1432         kern_unmount(ns->mq_mnt);
1433 }
1434 
1435 static int __init init_mqueue_fs(void)
1436 {
1437         int error;
1438 
1439         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1440                                 sizeof(struct mqueue_inode_info), 0,
1441                                 SLAB_HWCACHE_ALIGN, init_once);
1442         if (mqueue_inode_cachep == NULL)
1443                 return -ENOMEM;
1444 
1445         /* ignore failures - they are not fatal */
1446         mq_sysctl_table = mq_register_sysctl_table();
1447 
1448         error = register_filesystem(&mqueue_fs_type);
1449         if (error)
1450                 goto out_sysctl;
1451 
1452         spin_lock_init(&mq_lock);
1453 
1454         error = mq_init_ns(&init_ipc_ns);
1455         if (error)
1456                 goto out_filesystem;
1457 
1458         return 0;
1459 
1460 out_filesystem:
1461         unregister_filesystem(&mqueue_fs_type);
1462 out_sysctl:
1463         if (mq_sysctl_table)
1464                 unregister_sysctl_table(mq_sysctl_table);
1465         kmem_cache_destroy(mqueue_inode_cachep);
1466         return error;
1467 }
1468 
1469 device_initcall(init_mqueue_fs);
1470 

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