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TOMOYO Linux Cross Reference
Linux/ipc/mqueue.c

Version: ~ [ linux-5.4.2 ] ~ [ linux-5.3.15 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.88 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.158 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.206 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.206 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.78 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  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_PENDING   1
 51 #define STATE_READY     2
 52 
 53 struct posix_msg_tree_node {
 54         struct rb_node          rb_node;
 55         struct list_head        msg_list;
 56         int                     priority;
 57 };
 58 
 59 struct ext_wait_queue {         /* queue of sleeping tasks */
 60         struct task_struct *task;
 61         struct list_head list;
 62         struct msg_msg *msg;    /* ptr of loaded message */
 63         int state;              /* one of STATE_* values */
 64 };
 65 
 66 struct mqueue_inode_info {
 67         spinlock_t lock;
 68         struct inode vfs_inode;
 69         wait_queue_head_t wait_q;
 70 
 71         struct rb_root msg_tree;
 72         struct posix_msg_tree_node *node_cache;
 73         struct mq_attr attr;
 74 
 75         struct sigevent notify;
 76         struct pid* notify_owner;
 77         struct user_namespace *notify_user_ns;
 78         struct user_struct *user;       /* user who created, for accounting */
 79         struct sock *notify_sock;
 80         struct sk_buff *notify_cookie;
 81 
 82         /* for tasks waiting for free space and messages, respectively */
 83         struct ext_wait_queue e_wait_q[2];
 84 
 85         unsigned long qsize; /* size of queue in memory (sum of all msgs) */
 86 };
 87 
 88 static const struct inode_operations mqueue_dir_inode_operations;
 89 static const struct file_operations mqueue_file_operations;
 90 static const struct super_operations mqueue_super_ops;
 91 static void remove_notification(struct mqueue_inode_info *info);
 92 
 93 static struct kmem_cache *mqueue_inode_cachep;
 94 
 95 static struct ctl_table_header * mq_sysctl_table;
 96 
 97 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
 98 {
 99         return container_of(inode, struct mqueue_inode_info, vfs_inode);
100 }
101 
102 /*
103  * This routine should be called with the mq_lock held.
104  */
105 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
106 {
107         return get_ipc_ns(inode->i_sb->s_fs_info);
108 }
109 
110 static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
111 {
112         struct ipc_namespace *ns;
113 
114         spin_lock(&mq_lock);
115         ns = __get_ns_from_inode(inode);
116         spin_unlock(&mq_lock);
117         return ns;
118 }
119 
120 /* Auxiliary functions to manipulate messages' list */
121 static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
122 {
123         struct rb_node **p, *parent = NULL;
124         struct posix_msg_tree_node *leaf;
125 
126         p = &info->msg_tree.rb_node;
127         while (*p) {
128                 parent = *p;
129                 leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
130 
131                 if (likely(leaf->priority == msg->m_type))
132                         goto insert_msg;
133                 else if (msg->m_type < leaf->priority)
134                         p = &(*p)->rb_left;
135                 else
136                         p = &(*p)->rb_right;
137         }
138         if (info->node_cache) {
139                 leaf = info->node_cache;
140                 info->node_cache = NULL;
141         } else {
142                 leaf = kmalloc(sizeof(*leaf), GFP_ATOMIC);
143                 if (!leaf)
144                         return -ENOMEM;
145                 rb_init_node(&leaf->rb_node);
146                 INIT_LIST_HEAD(&leaf->msg_list);
147                 info->qsize += sizeof(*leaf);
148         }
149         leaf->priority = msg->m_type;
150         rb_link_node(&leaf->rb_node, parent, p);
151         rb_insert_color(&leaf->rb_node, &info->msg_tree);
152 insert_msg:
153         info->attr.mq_curmsgs++;
154         info->qsize += msg->m_ts;
155         list_add_tail(&msg->m_list, &leaf->msg_list);
156         return 0;
157 }
158 
159 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
160 {
161         struct rb_node **p, *parent = NULL;
162         struct posix_msg_tree_node *leaf;
163         struct msg_msg *msg;
164 
165 try_again:
166         p = &info->msg_tree.rb_node;
167         while (*p) {
168                 parent = *p;
169                 /*
170                  * During insert, low priorities go to the left and high to the
171                  * right.  On receive, we want the highest priorities first, so
172                  * walk all the way to the right.
173                  */
174                 p = &(*p)->rb_right;
175         }
176         if (!parent) {
177                 if (info->attr.mq_curmsgs) {
178                         pr_warn_once("Inconsistency in POSIX message queue, "
179                                      "no tree element, but supposedly messages "
180                                      "should exist!\n");
181                         info->attr.mq_curmsgs = 0;
182                 }
183                 return NULL;
184         }
185         leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
186         if (unlikely(list_empty(&leaf->msg_list))) {
187                 pr_warn_once("Inconsistency in POSIX message queue, "
188                              "empty leaf node but we haven't implemented "
189                              "lazy leaf delete!\n");
190                 rb_erase(&leaf->rb_node, &info->msg_tree);
191                 if (info->node_cache) {
192                         info->qsize -= sizeof(*leaf);
193                         kfree(leaf);
194                 } else {
195                         info->node_cache = leaf;
196                 }
197                 goto try_again;
198         } else {
199                 msg = list_first_entry(&leaf->msg_list,
200                                        struct msg_msg, m_list);
201                 list_del(&msg->m_list);
202                 if (list_empty(&leaf->msg_list)) {
203                         rb_erase(&leaf->rb_node, &info->msg_tree);
204                         if (info->node_cache) {
205                                 info->qsize -= sizeof(*leaf);
206                                 kfree(leaf);
207                         } else {
208                                 info->node_cache = leaf;
209                         }
210                 }
211         }
212         info->attr.mq_curmsgs--;
213         info->qsize -= msg->m_ts;
214         return msg;
215 }
216 
217 static struct inode *mqueue_get_inode(struct super_block *sb,
218                 struct ipc_namespace *ipc_ns, umode_t mode,
219                 struct mq_attr *attr)
220 {
221         struct user_struct *u = current_user();
222         struct inode *inode;
223         int ret = -ENOMEM;
224 
225         inode = new_inode(sb);
226         if (!inode)
227                 goto err;
228 
229         inode->i_ino = get_next_ino();
230         inode->i_mode = mode;
231         inode->i_uid = current_fsuid();
232         inode->i_gid = current_fsgid();
233         inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
234 
235         if (S_ISREG(mode)) {
236                 struct mqueue_inode_info *info;
237                 unsigned long mq_bytes, mq_treesize;
238 
239                 inode->i_fop = &mqueue_file_operations;
240                 inode->i_size = FILENT_SIZE;
241                 /* mqueue specific info */
242                 info = MQUEUE_I(inode);
243                 spin_lock_init(&info->lock);
244                 init_waitqueue_head(&info->wait_q);
245                 INIT_LIST_HEAD(&info->e_wait_q[0].list);
246                 INIT_LIST_HEAD(&info->e_wait_q[1].list);
247                 info->notify_owner = NULL;
248                 info->notify_user_ns = NULL;
249                 info->qsize = 0;
250                 info->user = NULL;      /* set when all is ok */
251                 info->msg_tree = RB_ROOT;
252                 info->node_cache = NULL;
253                 memset(&info->attr, 0, sizeof(info->attr));
254                 info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
255                                            ipc_ns->mq_msg_default);
256                 info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
257                                             ipc_ns->mq_msgsize_default);
258                 if (attr) {
259                         info->attr.mq_maxmsg = attr->mq_maxmsg;
260                         info->attr.mq_msgsize = attr->mq_msgsize;
261                 }
262                 /*
263                  * We used to allocate a static array of pointers and account
264                  * the size of that array as well as one msg_msg struct per
265                  * possible message into the queue size. That's no longer
266                  * accurate as the queue is now an rbtree and will grow and
267                  * shrink depending on usage patterns.  We can, however, still
268                  * account one msg_msg struct per message, but the nodes are
269                  * allocated depending on priority usage, and most programs
270                  * only use one, or a handful, of priorities.  However, since
271                  * this is pinned memory, we need to assume worst case, so
272                  * that means the min(mq_maxmsg, max_priorities) * struct
273                  * posix_msg_tree_node.
274                  */
275                 mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
276                         min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
277                         sizeof(struct posix_msg_tree_node);
278 
279                 mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
280                                           info->attr.mq_msgsize);
281 
282                 spin_lock(&mq_lock);
283                 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
284                     u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
285                         spin_unlock(&mq_lock);
286                         /* mqueue_evict_inode() releases info->messages */
287                         ret = -EMFILE;
288                         goto out_inode;
289                 }
290                 u->mq_bytes += mq_bytes;
291                 spin_unlock(&mq_lock);
292 
293                 /* all is ok */
294                 info->user = get_uid(u);
295         } else if (S_ISDIR(mode)) {
296                 inc_nlink(inode);
297                 /* Some things misbehave if size == 0 on a directory */
298                 inode->i_size = 2 * DIRENT_SIZE;
299                 inode->i_op = &mqueue_dir_inode_operations;
300                 inode->i_fop = &simple_dir_operations;
301         }
302 
303         return inode;
304 out_inode:
305         iput(inode);
306 err:
307         return ERR_PTR(ret);
308 }
309 
310 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
311 {
312         struct inode *inode;
313         struct ipc_namespace *ns = data;
314 
315         sb->s_blocksize = PAGE_CACHE_SIZE;
316         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
317         sb->s_magic = MQUEUE_MAGIC;
318         sb->s_op = &mqueue_super_ops;
319 
320         inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
321         if (IS_ERR(inode))
322                 return PTR_ERR(inode);
323 
324         sb->s_root = d_make_root(inode);
325         if (!sb->s_root)
326                 return -ENOMEM;
327         return 0;
328 }
329 
330 static struct dentry *mqueue_mount(struct file_system_type *fs_type,
331                          int flags, const char *dev_name,
332                          void *data)
333 {
334         if (!(flags & MS_KERNMOUNT))
335                 data = current->nsproxy->ipc_ns;
336         return mount_ns(fs_type, flags, data, mqueue_fill_super);
337 }
338 
339 static void init_once(void *foo)
340 {
341         struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
342 
343         inode_init_once(&p->vfs_inode);
344 }
345 
346 static struct inode *mqueue_alloc_inode(struct super_block *sb)
347 {
348         struct mqueue_inode_info *ei;
349 
350         ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
351         if (!ei)
352                 return NULL;
353         return &ei->vfs_inode;
354 }
355 
356 static void mqueue_i_callback(struct rcu_head *head)
357 {
358         struct inode *inode = container_of(head, struct inode, i_rcu);
359         kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
360 }
361 
362 static void mqueue_destroy_inode(struct inode *inode)
363 {
364         call_rcu(&inode->i_rcu, mqueue_i_callback);
365 }
366 
367 static void mqueue_evict_inode(struct inode *inode)
368 {
369         struct mqueue_inode_info *info;
370         struct user_struct *user;
371         unsigned long mq_bytes, mq_treesize;
372         struct ipc_namespace *ipc_ns;
373         struct msg_msg *msg;
374 
375         clear_inode(inode);
376 
377         if (S_ISDIR(inode->i_mode))
378                 return;
379 
380         ipc_ns = get_ns_from_inode(inode);
381         info = MQUEUE_I(inode);
382         spin_lock(&info->lock);
383         while ((msg = msg_get(info)) != NULL)
384                 free_msg(msg);
385         kfree(info->node_cache);
386         spin_unlock(&info->lock);
387 
388         /* Total amount of bytes accounted for the mqueue */
389         mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
390                 min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
391                 sizeof(struct posix_msg_tree_node);
392 
393         mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
394                                   info->attr.mq_msgsize);
395 
396         user = info->user;
397         if (user) {
398                 spin_lock(&mq_lock);
399                 user->mq_bytes -= mq_bytes;
400                 /*
401                  * get_ns_from_inode() ensures that the
402                  * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
403                  * to which we now hold a reference, or it is NULL.
404                  * We can't put it here under mq_lock, though.
405                  */
406                 if (ipc_ns)
407                         ipc_ns->mq_queues_count--;
408                 spin_unlock(&mq_lock);
409                 free_uid(user);
410         }
411         if (ipc_ns)
412                 put_ipc_ns(ipc_ns);
413 }
414 
415 static int mqueue_create(struct inode *dir, struct dentry *dentry,
416                                 umode_t mode, bool excl)
417 {
418         struct inode *inode;
419         struct mq_attr *attr = dentry->d_fsdata;
420         int error;
421         struct ipc_namespace *ipc_ns;
422 
423         spin_lock(&mq_lock);
424         ipc_ns = __get_ns_from_inode(dir);
425         if (!ipc_ns) {
426                 error = -EACCES;
427                 goto out_unlock;
428         }
429         if (ipc_ns->mq_queues_count >= HARD_QUEUESMAX ||
430             (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
431              !capable(CAP_SYS_RESOURCE))) {
432                 error = -ENOSPC;
433                 goto out_unlock;
434         }
435         ipc_ns->mq_queues_count++;
436         spin_unlock(&mq_lock);
437 
438         inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
439         if (IS_ERR(inode)) {
440                 error = PTR_ERR(inode);
441                 spin_lock(&mq_lock);
442                 ipc_ns->mq_queues_count--;
443                 goto out_unlock;
444         }
445 
446         put_ipc_ns(ipc_ns);
447         dir->i_size += DIRENT_SIZE;
448         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
449 
450         d_instantiate(dentry, inode);
451         dget(dentry);
452         return 0;
453 out_unlock:
454         spin_unlock(&mq_lock);
455         if (ipc_ns)
456                 put_ipc_ns(ipc_ns);
457         return error;
458 }
459 
460 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
461 {
462         struct inode *inode = dentry->d_inode;
463 
464         dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
465         dir->i_size -= DIRENT_SIZE;
466         drop_nlink(inode);
467         dput(dentry);
468         return 0;
469 }
470 
471 /*
472 *       This is routine for system read from queue file.
473 *       To avoid mess with doing here some sort of mq_receive we allow
474 *       to read only queue size & notification info (the only values
475 *       that are interesting from user point of view and aren't accessible
476 *       through std routines)
477 */
478 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
479                                 size_t count, loff_t *off)
480 {
481         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
482         char buffer[FILENT_SIZE];
483         ssize_t ret;
484 
485         spin_lock(&info->lock);
486         snprintf(buffer, sizeof(buffer),
487                         "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
488                         info->qsize,
489                         info->notify_owner ? info->notify.sigev_notify : 0,
490                         (info->notify_owner &&
491                          info->notify.sigev_notify == SIGEV_SIGNAL) ?
492                                 info->notify.sigev_signo : 0,
493                         pid_vnr(info->notify_owner));
494         spin_unlock(&info->lock);
495         buffer[sizeof(buffer)-1] = '\0';
496 
497         ret = simple_read_from_buffer(u_data, count, off, buffer,
498                                 strlen(buffer));
499         if (ret <= 0)
500                 return ret;
501 
502         filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
503         return ret;
504 }
505 
506 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
507 {
508         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
509 
510         spin_lock(&info->lock);
511         if (task_tgid(current) == info->notify_owner)
512                 remove_notification(info);
513 
514         spin_unlock(&info->lock);
515         return 0;
516 }
517 
518 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
519 {
520         struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
521         int retval = 0;
522 
523         poll_wait(filp, &info->wait_q, poll_tab);
524 
525         spin_lock(&info->lock);
526         if (info->attr.mq_curmsgs)
527                 retval = POLLIN | POLLRDNORM;
528 
529         if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
530                 retval |= POLLOUT | POLLWRNORM;
531         spin_unlock(&info->lock);
532 
533         return retval;
534 }
535 
536 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
537 static void wq_add(struct mqueue_inode_info *info, int sr,
538                         struct ext_wait_queue *ewp)
539 {
540         struct ext_wait_queue *walk;
541 
542         ewp->task = current;
543 
544         list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
545                 if (walk->task->static_prio <= current->static_prio) {
546                         list_add_tail(&ewp->list, &walk->list);
547                         return;
548                 }
549         }
550         list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
551 }
552 
553 /*
554  * Puts current task to sleep. Caller must hold queue lock. After return
555  * lock isn't held.
556  * sr: SEND or RECV
557  */
558 static int wq_sleep(struct mqueue_inode_info *info, int sr,
559                     ktime_t *timeout, struct ext_wait_queue *ewp)
560 {
561         int retval;
562         signed long time;
563 
564         wq_add(info, sr, ewp);
565 
566         for (;;) {
567                 set_current_state(TASK_INTERRUPTIBLE);
568 
569                 spin_unlock(&info->lock);
570                 time = schedule_hrtimeout_range_clock(timeout, 0,
571                         HRTIMER_MODE_ABS, CLOCK_REALTIME);
572 
573                 while (ewp->state == STATE_PENDING)
574                         cpu_relax();
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(path->dentry->d_inode, 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         char *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(&root->d_inode->i_mutex);
799         path.dentry = lookup_one_len(name, root, strlen(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 (path.dentry->d_inode) {     /* entry already exists */
808                         audit_inode(name, path.dentry);
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                         filp = do_create(ipc_ns, root->d_inode,
820                                                 &path, oflag, mode,
821                                                 u_attr ? &attr : NULL);
822                 }
823         } else {
824                 if (!path.dentry->d_inode) {
825                         error = -ENOENT;
826                         goto out;
827                 }
828                 audit_inode(name, path.dentry);
829                 filp = do_open(&path, oflag);
830         }
831 
832         if (!IS_ERR(filp))
833                 fd_install(fd, filp);
834         else
835                 error = PTR_ERR(filp);
836 out:
837         path_put(&path);
838 out_putfd:
839         if (error) {
840                 put_unused_fd(fd);
841                 fd = error;
842         }
843         mutex_unlock(&root->d_inode->i_mutex);
844         mnt_drop_write(mnt);
845 out_putname:
846         putname(name);
847         return fd;
848 }
849 
850 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
851 {
852         int err;
853         char *name;
854         struct dentry *dentry;
855         struct inode *inode = NULL;
856         struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
857         struct vfsmount *mnt = ipc_ns->mq_mnt;
858 
859         name = getname(u_name);
860         if (IS_ERR(name))
861                 return PTR_ERR(name);
862 
863         err = mnt_want_write(mnt);
864         if (err)
865                 goto out_name;
866         mutex_lock_nested(&mnt->mnt_root->d_inode->i_mutex, I_MUTEX_PARENT);
867         dentry = lookup_one_len(name, mnt->mnt_root, strlen(name));
868         if (IS_ERR(dentry)) {
869                 err = PTR_ERR(dentry);
870                 goto out_unlock;
871         }
872 
873         inode = dentry->d_inode;
874         if (!inode) {
875                 err = -ENOENT;
876         } else {
877                 ihold(inode);
878                 err = vfs_unlink(dentry->d_parent->d_inode, dentry);
879         }
880         dput(dentry);
881 
882 out_unlock:
883         mutex_unlock(&mnt->mnt_root->d_inode->i_mutex);
884         if (inode)
885                 iput(inode);
886         mnt_drop_write(mnt);
887 out_name:
888         putname(name);
889 
890         return err;
891 }
892 
893 /* Pipelined send and receive functions.
894  *
895  * If a receiver finds no waiting message, then it registers itself in the
896  * list of waiting receivers. A sender checks that list before adding the new
897  * message into the message array. If there is a waiting receiver, then it
898  * bypasses the message array and directly hands the message over to the
899  * receiver.
900  * The receiver accepts the message and returns without grabbing the queue
901  * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
902  * are necessary. The same algorithm is used for sysv semaphores, see
903  * ipc/sem.c for more details.
904  *
905  * The same algorithm is used for senders.
906  */
907 
908 /* pipelined_send() - send a message directly to the task waiting in
909  * sys_mq_timedreceive() (without inserting message into a queue).
910  */
911 static inline void pipelined_send(struct mqueue_inode_info *info,
912                                   struct msg_msg *message,
913                                   struct ext_wait_queue *receiver)
914 {
915         receiver->msg = message;
916         list_del(&receiver->list);
917         receiver->state = STATE_PENDING;
918         wake_up_process(receiver->task);
919         smp_wmb();
920         receiver->state = STATE_READY;
921 }
922 
923 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
924  * gets its message and put to the queue (we have one free place for sure). */
925 static inline void pipelined_receive(struct mqueue_inode_info *info)
926 {
927         struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
928 
929         if (!sender) {
930                 /* for poll */
931                 wake_up_interruptible(&info->wait_q);
932                 return;
933         }
934         if (msg_insert(sender->msg, info))
935                 return;
936         list_del(&sender->list);
937         sender->state = STATE_PENDING;
938         wake_up_process(sender->task);
939         smp_wmb();
940         sender->state = STATE_READY;
941 }
942 
943 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
944                 size_t, msg_len, unsigned int, msg_prio,
945                 const struct timespec __user *, u_abs_timeout)
946 {
947         struct file *filp;
948         struct inode *inode;
949         struct ext_wait_queue wait;
950         struct ext_wait_queue *receiver;
951         struct msg_msg *msg_ptr;
952         struct mqueue_inode_info *info;
953         ktime_t expires, *timeout = NULL;
954         struct timespec ts;
955         struct posix_msg_tree_node *new_leaf = NULL;
956         int ret = 0;
957 
958         if (u_abs_timeout) {
959                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
960                 if (res)
961                         return res;
962                 timeout = &expires;
963         }
964 
965         if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
966                 return -EINVAL;
967 
968         audit_mq_sendrecv(mqdes, msg_len, msg_prio, 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_WRITE))) {
985                 ret = -EBADF;
986                 goto out_fput;
987         }
988 
989         if (unlikely(msg_len > info->attr.mq_msgsize)) {
990                 ret = -EMSGSIZE;
991                 goto out_fput;
992         }
993 
994         /* First try to allocate memory, before doing anything with
995          * existing queues. */
996         msg_ptr = load_msg(u_msg_ptr, msg_len);
997         if (IS_ERR(msg_ptr)) {
998                 ret = PTR_ERR(msg_ptr);
999                 goto out_fput;
1000         }
1001         msg_ptr->m_ts = msg_len;
1002         msg_ptr->m_type = msg_prio;
1003 
1004         /*
1005          * msg_insert really wants us to have a valid, spare node struct so
1006          * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1007          * fall back to that if necessary.
1008          */
1009         if (!info->node_cache)
1010                 new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1011 
1012         spin_lock(&info->lock);
1013 
1014         if (!info->node_cache && new_leaf) {
1015                 /* Save our speculative allocation into the cache */
1016                 rb_init_node(&new_leaf->rb_node);
1017                 INIT_LIST_HEAD(&new_leaf->msg_list);
1018                 info->node_cache = new_leaf;
1019                 info->qsize += sizeof(*new_leaf);
1020                 new_leaf = NULL;
1021         } else {
1022                 kfree(new_leaf);
1023         }
1024 
1025         if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
1026                 if (filp->f_flags & O_NONBLOCK) {
1027                         ret = -EAGAIN;
1028                 } else {
1029                         wait.task = current;
1030                         wait.msg = (void *) msg_ptr;
1031                         wait.state = STATE_NONE;
1032                         ret = wq_sleep(info, SEND, timeout, &wait);
1033                         /*
1034                          * wq_sleep must be called with info->lock held, and
1035                          * returns with the lock released
1036                          */
1037                         goto out_free;
1038                 }
1039         } else {
1040                 receiver = wq_get_first_waiter(info, RECV);
1041                 if (receiver) {
1042                         pipelined_send(info, msg_ptr, receiver);
1043                 } else {
1044                         /* adds message to the queue */
1045                         ret = msg_insert(msg_ptr, info);
1046                         if (ret)
1047                                 goto out_unlock;
1048                         __do_notify(info);
1049                 }
1050                 inode->i_atime = inode->i_mtime = inode->i_ctime =
1051                                 CURRENT_TIME;
1052         }
1053 out_unlock:
1054         spin_unlock(&info->lock);
1055 out_free:
1056         if (ret)
1057                 free_msg(msg_ptr);
1058 out_fput:
1059         fput(filp);
1060 out:
1061         return ret;
1062 }
1063 
1064 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
1065                 size_t, msg_len, unsigned int __user *, u_msg_prio,
1066                 const struct timespec __user *, u_abs_timeout)
1067 {
1068         ssize_t ret;
1069         struct msg_msg *msg_ptr;
1070         struct file *filp;
1071         struct inode *inode;
1072         struct mqueue_inode_info *info;
1073         struct ext_wait_queue wait;
1074         ktime_t expires, *timeout = NULL;
1075         struct timespec ts;
1076         struct posix_msg_tree_node *new_leaf = NULL;
1077 
1078         if (u_abs_timeout) {
1079                 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
1080                 if (res)
1081                         return res;
1082                 timeout = &expires;
1083         }
1084 
1085         audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
1086 
1087         filp = fget(mqdes);
1088         if (unlikely(!filp)) {
1089                 ret = -EBADF;
1090                 goto out;
1091         }
1092 
1093         inode = filp->f_path.dentry->d_inode;
1094         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1095                 ret = -EBADF;
1096                 goto out_fput;
1097         }
1098         info = MQUEUE_I(inode);
1099         audit_inode(NULL, filp->f_path.dentry);
1100 
1101         if (unlikely(!(filp->f_mode & FMODE_READ))) {
1102                 ret = -EBADF;
1103                 goto out_fput;
1104         }
1105 
1106         /* checks if buffer is big enough */
1107         if (unlikely(msg_len < info->attr.mq_msgsize)) {
1108                 ret = -EMSGSIZE;
1109                 goto out_fput;
1110         }
1111 
1112         /*
1113          * msg_insert really wants us to have a valid, spare node struct so
1114          * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1115          * fall back to that if necessary.
1116          */
1117         if (!info->node_cache)
1118                 new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1119 
1120         spin_lock(&info->lock);
1121 
1122         if (!info->node_cache && new_leaf) {
1123                 /* Save our speculative allocation into the cache */
1124                 rb_init_node(&new_leaf->rb_node);
1125                 INIT_LIST_HEAD(&new_leaf->msg_list);
1126                 info->node_cache = new_leaf;
1127                 info->qsize += sizeof(*new_leaf);
1128         } else {
1129                 kfree(new_leaf);
1130         }
1131 
1132         if (info->attr.mq_curmsgs == 0) {
1133                 if (filp->f_flags & O_NONBLOCK) {
1134                         spin_unlock(&info->lock);
1135                         ret = -EAGAIN;
1136                 } else {
1137                         wait.task = current;
1138                         wait.state = STATE_NONE;
1139                         ret = wq_sleep(info, RECV, timeout, &wait);
1140                         msg_ptr = wait.msg;
1141                 }
1142         } else {
1143                 msg_ptr = msg_get(info);
1144 
1145                 inode->i_atime = inode->i_mtime = inode->i_ctime =
1146                                 CURRENT_TIME;
1147 
1148                 /* There is now free space in queue. */
1149                 pipelined_receive(info);
1150                 spin_unlock(&info->lock);
1151                 ret = 0;
1152         }
1153         if (ret == 0) {
1154                 ret = msg_ptr->m_ts;
1155 
1156                 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1157                         store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1158                         ret = -EFAULT;
1159                 }
1160                 free_msg(msg_ptr);
1161         }
1162 out_fput:
1163         fput(filp);
1164 out:
1165         return ret;
1166 }
1167 
1168 /*
1169  * Notes: the case when user wants us to deregister (with NULL as pointer)
1170  * and he isn't currently owner of notification, will be silently discarded.
1171  * It isn't explicitly defined in the POSIX.
1172  */
1173 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1174                 const struct sigevent __user *, u_notification)
1175 {
1176         int ret;
1177         struct file *filp;
1178         struct sock *sock;
1179         struct inode *inode;
1180         struct sigevent notification;
1181         struct mqueue_inode_info *info;
1182         struct sk_buff *nc;
1183 
1184         if (u_notification) {
1185                 if (copy_from_user(&notification, u_notification,
1186                                         sizeof(struct sigevent)))
1187                         return -EFAULT;
1188         }
1189 
1190         audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1191 
1192         nc = NULL;
1193         sock = NULL;
1194         if (u_notification != NULL) {
1195                 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1196                              notification.sigev_notify != SIGEV_SIGNAL &&
1197                              notification.sigev_notify != SIGEV_THREAD))
1198                         return -EINVAL;
1199                 if (notification.sigev_notify == SIGEV_SIGNAL &&
1200                         !valid_signal(notification.sigev_signo)) {
1201                         return -EINVAL;
1202                 }
1203                 if (notification.sigev_notify == SIGEV_THREAD) {
1204                         long timeo;
1205 
1206                         /* create the notify skb */
1207                         nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1208                         if (!nc) {
1209                                 ret = -ENOMEM;
1210                                 goto out;
1211                         }
1212                         if (copy_from_user(nc->data,
1213                                         notification.sigev_value.sival_ptr,
1214                                         NOTIFY_COOKIE_LEN)) {
1215                                 ret = -EFAULT;
1216                                 goto out;
1217                         }
1218 
1219                         /* TODO: add a header? */
1220                         skb_put(nc, NOTIFY_COOKIE_LEN);
1221                         /* and attach it to the socket */
1222 retry:
1223                         filp = fget(notification.sigev_signo);
1224                         if (!filp) {
1225                                 ret = -EBADF;
1226                                 goto out;
1227                         }
1228                         sock = netlink_getsockbyfilp(filp);
1229                         fput(filp);
1230                         if (IS_ERR(sock)) {
1231                                 ret = PTR_ERR(sock);
1232                                 sock = NULL;
1233                                 goto out;
1234                         }
1235 
1236                         timeo = MAX_SCHEDULE_TIMEOUT;
1237                         ret = netlink_attachskb(sock, nc, &timeo, NULL);
1238                         if (ret == 1)
1239                                 goto retry;
1240                         if (ret) {
1241                                 sock = NULL;
1242                                 nc = NULL;
1243                                 goto out;
1244                         }
1245                 }
1246         }
1247 
1248         filp = fget(mqdes);
1249         if (!filp) {
1250                 ret = -EBADF;
1251                 goto out;
1252         }
1253 
1254         inode = filp->f_path.dentry->d_inode;
1255         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1256                 ret = -EBADF;
1257                 goto out_fput;
1258         }
1259         info = MQUEUE_I(inode);
1260 
1261         ret = 0;
1262         spin_lock(&info->lock);
1263         if (u_notification == NULL) {
1264                 if (info->notify_owner == task_tgid(current)) {
1265                         remove_notification(info);
1266                         inode->i_atime = inode->i_ctime = CURRENT_TIME;
1267                 }
1268         } else if (info->notify_owner != NULL) {
1269                 ret = -EBUSY;
1270         } else {
1271                 switch (notification.sigev_notify) {
1272                 case SIGEV_NONE:
1273                         info->notify.sigev_notify = SIGEV_NONE;
1274                         break;
1275                 case SIGEV_THREAD:
1276                         info->notify_sock = sock;
1277                         info->notify_cookie = nc;
1278                         sock = NULL;
1279                         nc = NULL;
1280                         info->notify.sigev_notify = SIGEV_THREAD;
1281                         break;
1282                 case SIGEV_SIGNAL:
1283                         info->notify.sigev_signo = notification.sigev_signo;
1284                         info->notify.sigev_value = notification.sigev_value;
1285                         info->notify.sigev_notify = SIGEV_SIGNAL;
1286                         break;
1287                 }
1288 
1289                 info->notify_owner = get_pid(task_tgid(current));
1290                 info->notify_user_ns = get_user_ns(current_user_ns());
1291                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1292         }
1293         spin_unlock(&info->lock);
1294 out_fput:
1295         fput(filp);
1296 out:
1297         if (sock) {
1298                 netlink_detachskb(sock, nc);
1299         } else if (nc) {
1300                 dev_kfree_skb(nc);
1301         }
1302         return ret;
1303 }
1304 
1305 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1306                 const struct mq_attr __user *, u_mqstat,
1307                 struct mq_attr __user *, u_omqstat)
1308 {
1309         int ret;
1310         struct mq_attr mqstat, omqstat;
1311         struct file *filp;
1312         struct inode *inode;
1313         struct mqueue_inode_info *info;
1314 
1315         if (u_mqstat != NULL) {
1316                 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1317                         return -EFAULT;
1318                 if (mqstat.mq_flags & (~O_NONBLOCK))
1319                         return -EINVAL;
1320         }
1321 
1322         filp = fget(mqdes);
1323         if (!filp) {
1324                 ret = -EBADF;
1325                 goto out;
1326         }
1327 
1328         inode = filp->f_path.dentry->d_inode;
1329         if (unlikely(filp->f_op != &mqueue_file_operations)) {
1330                 ret = -EBADF;
1331                 goto out_fput;
1332         }
1333         info = MQUEUE_I(inode);
1334 
1335         spin_lock(&info->lock);
1336 
1337         omqstat = info->attr;
1338         omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1339         if (u_mqstat) {
1340                 audit_mq_getsetattr(mqdes, &mqstat);
1341                 spin_lock(&filp->f_lock);
1342                 if (mqstat.mq_flags & O_NONBLOCK)
1343                         filp->f_flags |= O_NONBLOCK;
1344                 else
1345                         filp->f_flags &= ~O_NONBLOCK;
1346                 spin_unlock(&filp->f_lock);
1347 
1348                 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1349         }
1350 
1351         spin_unlock(&info->lock);
1352 
1353         ret = 0;
1354         if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1355                                                 sizeof(struct mq_attr)))
1356                 ret = -EFAULT;
1357 
1358 out_fput:
1359         fput(filp);
1360 out:
1361         return ret;
1362 }
1363 
1364 static const struct inode_operations mqueue_dir_inode_operations = {
1365         .lookup = simple_lookup,
1366         .create = mqueue_create,
1367         .unlink = mqueue_unlink,
1368 };
1369 
1370 static const struct file_operations mqueue_file_operations = {
1371         .flush = mqueue_flush_file,
1372         .poll = mqueue_poll_file,
1373         .read = mqueue_read_file,
1374         .llseek = default_llseek,
1375 };
1376 
1377 static const struct super_operations mqueue_super_ops = {
1378         .alloc_inode = mqueue_alloc_inode,
1379         .destroy_inode = mqueue_destroy_inode,
1380         .evict_inode = mqueue_evict_inode,
1381         .statfs = simple_statfs,
1382 };
1383 
1384 static struct file_system_type mqueue_fs_type = {
1385         .name = "mqueue",
1386         .mount = mqueue_mount,
1387         .kill_sb = kill_litter_super,
1388 };
1389 
1390 int mq_init_ns(struct ipc_namespace *ns)
1391 {
1392         ns->mq_queues_count  = 0;
1393         ns->mq_queues_max    = DFLT_QUEUESMAX;
1394         ns->mq_msg_max       = DFLT_MSGMAX;
1395         ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1396         ns->mq_msg_default   = DFLT_MSG;
1397         ns->mq_msgsize_default  = DFLT_MSGSIZE;
1398 
1399         ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1400         if (IS_ERR(ns->mq_mnt)) {
1401                 int err = PTR_ERR(ns->mq_mnt);
1402                 ns->mq_mnt = NULL;
1403                 return err;
1404         }
1405         return 0;
1406 }
1407 
1408 void mq_clear_sbinfo(struct ipc_namespace *ns)
1409 {
1410         ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1411 }
1412 
1413 void mq_put_mnt(struct ipc_namespace *ns)
1414 {
1415         kern_unmount(ns->mq_mnt);
1416 }
1417 
1418 static int __init init_mqueue_fs(void)
1419 {
1420         int error;
1421 
1422         mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1423                                 sizeof(struct mqueue_inode_info), 0,
1424                                 SLAB_HWCACHE_ALIGN, init_once);
1425         if (mqueue_inode_cachep == NULL)
1426                 return -ENOMEM;
1427 
1428         /* ignore failures - they are not fatal */
1429         mq_sysctl_table = mq_register_sysctl_table();
1430 
1431         error = register_filesystem(&mqueue_fs_type);
1432         if (error)
1433                 goto out_sysctl;
1434 
1435         spin_lock_init(&mq_lock);
1436 
1437         error = mq_init_ns(&init_ipc_ns);
1438         if (error)
1439                 goto out_filesystem;
1440 
1441         return 0;
1442 
1443 out_filesystem:
1444         unregister_filesystem(&mqueue_fs_type);
1445 out_sysctl:
1446         if (mq_sysctl_table)
1447                 unregister_sysctl_table(mq_sysctl_table);
1448         kmem_cache_destroy(mqueue_inode_cachep);
1449         return error;
1450 }
1451 
1452 __initcall(init_mqueue_fs);
1453 

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