xref: /openbmc/linux/ipc/mqueue.c (revision cfdfc14e)
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  #include <linux/sched/wake_q.h>
39  #include <linux/sched/signal.h>
40  #include <linux/sched/user.h>
41  
42  #include <net/sock.h>
43  #include "util.h"
44  
45  #define MQUEUE_MAGIC	0x19800202
46  #define DIRENT_SIZE	20
47  #define FILENT_SIZE	80
48  
49  #define SEND		0
50  #define RECV		1
51  
52  #define STATE_NONE	0
53  #define STATE_READY	1
54  
55  struct posix_msg_tree_node {
56  	struct rb_node		rb_node;
57  	struct list_head	msg_list;
58  	int			priority;
59  };
60  
61  struct ext_wait_queue {		/* queue of sleeping tasks */
62  	struct task_struct *task;
63  	struct list_head list;
64  	struct msg_msg *msg;	/* ptr of loaded message */
65  	int state;		/* one of STATE_* values */
66  };
67  
68  struct mqueue_inode_info {
69  	spinlock_t lock;
70  	struct inode vfs_inode;
71  	wait_queue_head_t wait_q;
72  
73  	struct rb_root msg_tree;
74  	struct posix_msg_tree_node *node_cache;
75  	struct mq_attr attr;
76  
77  	struct sigevent notify;
78  	struct pid *notify_owner;
79  	struct user_namespace *notify_user_ns;
80  	struct user_struct *user;	/* user who created, for accounting */
81  	struct sock *notify_sock;
82  	struct sk_buff *notify_cookie;
83  
84  	/* for tasks waiting for free space and messages, respectively */
85  	struct ext_wait_queue e_wait_q[2];
86  
87  	unsigned long qsize; /* size of queue in memory (sum of all msgs) */
88  };
89  
90  static const struct inode_operations mqueue_dir_inode_operations;
91  static const struct file_operations mqueue_file_operations;
92  static const struct super_operations mqueue_super_ops;
93  static void remove_notification(struct mqueue_inode_info *info);
94  
95  static struct kmem_cache *mqueue_inode_cachep;
96  
97  static struct ctl_table_header *mq_sysctl_table;
98  
99  static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
100  {
101  	return container_of(inode, struct mqueue_inode_info, vfs_inode);
102  }
103  
104  /*
105   * This routine should be called with the mq_lock held.
106   */
107  static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
108  {
109  	return get_ipc_ns(inode->i_sb->s_fs_info);
110  }
111  
112  static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
113  {
114  	struct ipc_namespace *ns;
115  
116  	spin_lock(&mq_lock);
117  	ns = __get_ns_from_inode(inode);
118  	spin_unlock(&mq_lock);
119  	return ns;
120  }
121  
122  /* Auxiliary functions to manipulate messages' list */
123  static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
124  {
125  	struct rb_node **p, *parent = NULL;
126  	struct posix_msg_tree_node *leaf;
127  
128  	p = &info->msg_tree.rb_node;
129  	while (*p) {
130  		parent = *p;
131  		leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
132  
133  		if (likely(leaf->priority == msg->m_type))
134  			goto insert_msg;
135  		else if (msg->m_type < leaf->priority)
136  			p = &(*p)->rb_left;
137  		else
138  			p = &(*p)->rb_right;
139  	}
140  	if (info->node_cache) {
141  		leaf = info->node_cache;
142  		info->node_cache = NULL;
143  	} else {
144  		leaf = kmalloc(sizeof(*leaf), GFP_ATOMIC);
145  		if (!leaf)
146  			return -ENOMEM;
147  		INIT_LIST_HEAD(&leaf->msg_list);
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  			kfree(leaf);
193  		} else {
194  			info->node_cache = leaf;
195  		}
196  		goto try_again;
197  	} else {
198  		msg = list_first_entry(&leaf->msg_list,
199  				       struct msg_msg, m_list);
200  		list_del(&msg->m_list);
201  		if (list_empty(&leaf->msg_list)) {
202  			rb_erase(&leaf->rb_node, &info->msg_tree);
203  			if (info->node_cache) {
204  				kfree(leaf);
205  			} else {
206  				info->node_cache = leaf;
207  			}
208  		}
209  	}
210  	info->attr.mq_curmsgs--;
211  	info->qsize -= msg->m_ts;
212  	return msg;
213  }
214  
215  static struct inode *mqueue_get_inode(struct super_block *sb,
216  		struct ipc_namespace *ipc_ns, umode_t mode,
217  		struct mq_attr *attr)
218  {
219  	struct user_struct *u = current_user();
220  	struct inode *inode;
221  	int ret = -ENOMEM;
222  
223  	inode = new_inode(sb);
224  	if (!inode)
225  		goto err;
226  
227  	inode->i_ino = get_next_ino();
228  	inode->i_mode = mode;
229  	inode->i_uid = current_fsuid();
230  	inode->i_gid = current_fsgid();
231  	inode->i_mtime = inode->i_ctime = inode->i_atime = current_time(inode);
232  
233  	if (S_ISREG(mode)) {
234  		struct mqueue_inode_info *info;
235  		unsigned long mq_bytes, mq_treesize;
236  
237  		inode->i_fop = &mqueue_file_operations;
238  		inode->i_size = FILENT_SIZE;
239  		/* mqueue specific info */
240  		info = MQUEUE_I(inode);
241  		spin_lock_init(&info->lock);
242  		init_waitqueue_head(&info->wait_q);
243  		INIT_LIST_HEAD(&info->e_wait_q[0].list);
244  		INIT_LIST_HEAD(&info->e_wait_q[1].list);
245  		info->notify_owner = NULL;
246  		info->notify_user_ns = NULL;
247  		info->qsize = 0;
248  		info->user = NULL;	/* set when all is ok */
249  		info->msg_tree = RB_ROOT;
250  		info->node_cache = NULL;
251  		memset(&info->attr, 0, sizeof(info->attr));
252  		info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
253  					   ipc_ns->mq_msg_default);
254  		info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
255  					    ipc_ns->mq_msgsize_default);
256  		if (attr) {
257  			info->attr.mq_maxmsg = attr->mq_maxmsg;
258  			info->attr.mq_msgsize = attr->mq_msgsize;
259  		}
260  		/*
261  		 * We used to allocate a static array of pointers and account
262  		 * the size of that array as well as one msg_msg struct per
263  		 * possible message into the queue size. That's no longer
264  		 * accurate as the queue is now an rbtree and will grow and
265  		 * shrink depending on usage patterns.  We can, however, still
266  		 * account one msg_msg struct per message, but the nodes are
267  		 * allocated depending on priority usage, and most programs
268  		 * only use one, or a handful, of priorities.  However, since
269  		 * this is pinned memory, we need to assume worst case, so
270  		 * that means the min(mq_maxmsg, max_priorities) * struct
271  		 * posix_msg_tree_node.
272  		 */
273  
274  		ret = -EINVAL;
275  		if (info->attr.mq_maxmsg <= 0 || info->attr.mq_msgsize <= 0)
276  			goto out_inode;
277  		if (capable(CAP_SYS_RESOURCE)) {
278  			if (info->attr.mq_maxmsg > HARD_MSGMAX ||
279  			    info->attr.mq_msgsize > HARD_MSGSIZEMAX)
280  				goto out_inode;
281  		} else {
282  			if (info->attr.mq_maxmsg > ipc_ns->mq_msg_max ||
283  					info->attr.mq_msgsize > ipc_ns->mq_msgsize_max)
284  				goto out_inode;
285  		}
286  		ret = -EOVERFLOW;
287  		/* check for overflow */
288  		if (info->attr.mq_msgsize > ULONG_MAX/info->attr.mq_maxmsg)
289  			goto out_inode;
290  		mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
291  			min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
292  			sizeof(struct posix_msg_tree_node);
293  		mq_bytes = info->attr.mq_maxmsg * info->attr.mq_msgsize;
294  		if (mq_bytes + mq_treesize < mq_bytes)
295  			goto out_inode;
296  		mq_bytes += mq_treesize;
297  		spin_lock(&mq_lock);
298  		if (u->mq_bytes + mq_bytes < u->mq_bytes ||
299  		    u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
300  			spin_unlock(&mq_lock);
301  			/* mqueue_evict_inode() releases info->messages */
302  			ret = -EMFILE;
303  			goto out_inode;
304  		}
305  		u->mq_bytes += mq_bytes;
306  		spin_unlock(&mq_lock);
307  
308  		/* all is ok */
309  		info->user = get_uid(u);
310  	} else if (S_ISDIR(mode)) {
311  		inc_nlink(inode);
312  		/* Some things misbehave if size == 0 on a directory */
313  		inode->i_size = 2 * DIRENT_SIZE;
314  		inode->i_op = &mqueue_dir_inode_operations;
315  		inode->i_fop = &simple_dir_operations;
316  	}
317  
318  	return inode;
319  out_inode:
320  	iput(inode);
321  err:
322  	return ERR_PTR(ret);
323  }
324  
325  static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
326  {
327  	struct inode *inode;
328  	struct ipc_namespace *ns = sb->s_fs_info;
329  
330  	sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV;
331  	sb->s_blocksize = PAGE_SIZE;
332  	sb->s_blocksize_bits = PAGE_SHIFT;
333  	sb->s_magic = MQUEUE_MAGIC;
334  	sb->s_op = &mqueue_super_ops;
335  
336  	inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
337  	if (IS_ERR(inode))
338  		return PTR_ERR(inode);
339  
340  	sb->s_root = d_make_root(inode);
341  	if (!sb->s_root)
342  		return -ENOMEM;
343  	return 0;
344  }
345  
346  static struct dentry *mqueue_mount(struct file_system_type *fs_type,
347  			 int flags, const char *dev_name,
348  			 void *data)
349  {
350  	struct ipc_namespace *ns;
351  	if (flags & SB_KERNMOUNT) {
352  		ns = data;
353  		data = NULL;
354  	} else {
355  		ns = current->nsproxy->ipc_ns;
356  	}
357  	return mount_ns(fs_type, flags, data, ns, ns->user_ns, mqueue_fill_super);
358  }
359  
360  static void init_once(void *foo)
361  {
362  	struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
363  
364  	inode_init_once(&p->vfs_inode);
365  }
366  
367  static struct inode *mqueue_alloc_inode(struct super_block *sb)
368  {
369  	struct mqueue_inode_info *ei;
370  
371  	ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
372  	if (!ei)
373  		return NULL;
374  	return &ei->vfs_inode;
375  }
376  
377  static void mqueue_i_callback(struct rcu_head *head)
378  {
379  	struct inode *inode = container_of(head, struct inode, i_rcu);
380  	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
381  }
382  
383  static void mqueue_destroy_inode(struct inode *inode)
384  {
385  	call_rcu(&inode->i_rcu, mqueue_i_callback);
386  }
387  
388  static void mqueue_evict_inode(struct inode *inode)
389  {
390  	struct mqueue_inode_info *info;
391  	struct user_struct *user;
392  	unsigned long mq_bytes, mq_treesize;
393  	struct ipc_namespace *ipc_ns;
394  	struct msg_msg *msg;
395  
396  	clear_inode(inode);
397  
398  	if (S_ISDIR(inode->i_mode))
399  		return;
400  
401  	ipc_ns = get_ns_from_inode(inode);
402  	info = MQUEUE_I(inode);
403  	spin_lock(&info->lock);
404  	while ((msg = msg_get(info)) != NULL)
405  		free_msg(msg);
406  	kfree(info->node_cache);
407  	spin_unlock(&info->lock);
408  
409  	/* Total amount of bytes accounted for the mqueue */
410  	mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
411  		min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
412  		sizeof(struct posix_msg_tree_node);
413  
414  	mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
415  				  info->attr.mq_msgsize);
416  
417  	user = info->user;
418  	if (user) {
419  		spin_lock(&mq_lock);
420  		user->mq_bytes -= mq_bytes;
421  		/*
422  		 * get_ns_from_inode() ensures that the
423  		 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
424  		 * to which we now hold a reference, or it is NULL.
425  		 * We can't put it here under mq_lock, though.
426  		 */
427  		if (ipc_ns)
428  			ipc_ns->mq_queues_count--;
429  		spin_unlock(&mq_lock);
430  		free_uid(user);
431  	}
432  	if (ipc_ns)
433  		put_ipc_ns(ipc_ns);
434  }
435  
436  static int mqueue_create_attr(struct dentry *dentry, umode_t mode, void *arg)
437  {
438  	struct inode *dir = dentry->d_parent->d_inode;
439  	struct inode *inode;
440  	struct mq_attr *attr = arg;
441  	int error;
442  	struct ipc_namespace *ipc_ns;
443  
444  	spin_lock(&mq_lock);
445  	ipc_ns = __get_ns_from_inode(dir);
446  	if (!ipc_ns) {
447  		error = -EACCES;
448  		goto out_unlock;
449  	}
450  
451  	if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
452  	    !capable(CAP_SYS_RESOURCE)) {
453  		error = -ENOSPC;
454  		goto out_unlock;
455  	}
456  	ipc_ns->mq_queues_count++;
457  	spin_unlock(&mq_lock);
458  
459  	inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
460  	if (IS_ERR(inode)) {
461  		error = PTR_ERR(inode);
462  		spin_lock(&mq_lock);
463  		ipc_ns->mq_queues_count--;
464  		goto out_unlock;
465  	}
466  
467  	put_ipc_ns(ipc_ns);
468  	dir->i_size += DIRENT_SIZE;
469  	dir->i_ctime = dir->i_mtime = dir->i_atime = current_time(dir);
470  
471  	d_instantiate(dentry, inode);
472  	dget(dentry);
473  	return 0;
474  out_unlock:
475  	spin_unlock(&mq_lock);
476  	if (ipc_ns)
477  		put_ipc_ns(ipc_ns);
478  	return error;
479  }
480  
481  static int mqueue_create(struct inode *dir, struct dentry *dentry,
482  				umode_t mode, bool excl)
483  {
484  	return mqueue_create_attr(dentry, mode, NULL);
485  }
486  
487  static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
488  {
489  	struct inode *inode = d_inode(dentry);
490  
491  	dir->i_ctime = dir->i_mtime = dir->i_atime = current_time(dir);
492  	dir->i_size -= DIRENT_SIZE;
493  	drop_nlink(inode);
494  	dput(dentry);
495  	return 0;
496  }
497  
498  /*
499  *	This is routine for system read from queue file.
500  *	To avoid mess with doing here some sort of mq_receive we allow
501  *	to read only queue size & notification info (the only values
502  *	that are interesting from user point of view and aren't accessible
503  *	through std routines)
504  */
505  static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
506  				size_t count, loff_t *off)
507  {
508  	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
509  	char buffer[FILENT_SIZE];
510  	ssize_t ret;
511  
512  	spin_lock(&info->lock);
513  	snprintf(buffer, sizeof(buffer),
514  			"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
515  			info->qsize,
516  			info->notify_owner ? info->notify.sigev_notify : 0,
517  			(info->notify_owner &&
518  			 info->notify.sigev_notify == SIGEV_SIGNAL) ?
519  				info->notify.sigev_signo : 0,
520  			pid_vnr(info->notify_owner));
521  	spin_unlock(&info->lock);
522  	buffer[sizeof(buffer)-1] = '\0';
523  
524  	ret = simple_read_from_buffer(u_data, count, off, buffer,
525  				strlen(buffer));
526  	if (ret <= 0)
527  		return ret;
528  
529  	file_inode(filp)->i_atime = file_inode(filp)->i_ctime = current_time(file_inode(filp));
530  	return ret;
531  }
532  
533  static int mqueue_flush_file(struct file *filp, fl_owner_t id)
534  {
535  	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
536  
537  	spin_lock(&info->lock);
538  	if (task_tgid(current) == info->notify_owner)
539  		remove_notification(info);
540  
541  	spin_unlock(&info->lock);
542  	return 0;
543  }
544  
545  static __poll_t mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
546  {
547  	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
548  	__poll_t retval = 0;
549  
550  	poll_wait(filp, &info->wait_q, poll_tab);
551  
552  	spin_lock(&info->lock);
553  	if (info->attr.mq_curmsgs)
554  		retval = EPOLLIN | EPOLLRDNORM;
555  
556  	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
557  		retval |= EPOLLOUT | EPOLLWRNORM;
558  	spin_unlock(&info->lock);
559  
560  	return retval;
561  }
562  
563  /* Adds current to info->e_wait_q[sr] before element with smaller prio */
564  static void wq_add(struct mqueue_inode_info *info, int sr,
565  			struct ext_wait_queue *ewp)
566  {
567  	struct ext_wait_queue *walk;
568  
569  	ewp->task = current;
570  
571  	list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
572  		if (walk->task->prio <= current->prio) {
573  			list_add_tail(&ewp->list, &walk->list);
574  			return;
575  		}
576  	}
577  	list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
578  }
579  
580  /*
581   * Puts current task to sleep. Caller must hold queue lock. After return
582   * lock isn't held.
583   * sr: SEND or RECV
584   */
585  static int wq_sleep(struct mqueue_inode_info *info, int sr,
586  		    ktime_t *timeout, struct ext_wait_queue *ewp)
587  	__releases(&info->lock)
588  {
589  	int retval;
590  	signed long time;
591  
592  	wq_add(info, sr, ewp);
593  
594  	for (;;) {
595  		__set_current_state(TASK_INTERRUPTIBLE);
596  
597  		spin_unlock(&info->lock);
598  		time = schedule_hrtimeout_range_clock(timeout, 0,
599  			HRTIMER_MODE_ABS, CLOCK_REALTIME);
600  
601  		if (ewp->state == STATE_READY) {
602  			retval = 0;
603  			goto out;
604  		}
605  		spin_lock(&info->lock);
606  		if (ewp->state == STATE_READY) {
607  			retval = 0;
608  			goto out_unlock;
609  		}
610  		if (signal_pending(current)) {
611  			retval = -ERESTARTSYS;
612  			break;
613  		}
614  		if (time == 0) {
615  			retval = -ETIMEDOUT;
616  			break;
617  		}
618  	}
619  	list_del(&ewp->list);
620  out_unlock:
621  	spin_unlock(&info->lock);
622  out:
623  	return retval;
624  }
625  
626  /*
627   * Returns waiting task that should be serviced first or NULL if none exists
628   */
629  static struct ext_wait_queue *wq_get_first_waiter(
630  		struct mqueue_inode_info *info, int sr)
631  {
632  	struct list_head *ptr;
633  
634  	ptr = info->e_wait_q[sr].list.prev;
635  	if (ptr == &info->e_wait_q[sr].list)
636  		return NULL;
637  	return list_entry(ptr, struct ext_wait_queue, list);
638  }
639  
640  
641  static inline void set_cookie(struct sk_buff *skb, char code)
642  {
643  	((char *)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
644  }
645  
646  /*
647   * The next function is only to split too long sys_mq_timedsend
648   */
649  static void __do_notify(struct mqueue_inode_info *info)
650  {
651  	/* notification
652  	 * invoked when there is registered process and there isn't process
653  	 * waiting synchronously for message AND state of queue changed from
654  	 * empty to not empty. Here we are sure that no one is waiting
655  	 * synchronously. */
656  	if (info->notify_owner &&
657  	    info->attr.mq_curmsgs == 1) {
658  		struct siginfo sig_i;
659  		switch (info->notify.sigev_notify) {
660  		case SIGEV_NONE:
661  			break;
662  		case SIGEV_SIGNAL:
663  			/* sends signal */
664  
665  			clear_siginfo(&sig_i);
666  			sig_i.si_signo = info->notify.sigev_signo;
667  			sig_i.si_errno = 0;
668  			sig_i.si_code = SI_MESGQ;
669  			sig_i.si_value = info->notify.sigev_value;
670  			/* map current pid/uid into info->owner's namespaces */
671  			rcu_read_lock();
672  			sig_i.si_pid = task_tgid_nr_ns(current,
673  						ns_of_pid(info->notify_owner));
674  			sig_i.si_uid = from_kuid_munged(info->notify_user_ns, current_uid());
675  			rcu_read_unlock();
676  
677  			kill_pid_info(info->notify.sigev_signo,
678  				      &sig_i, info->notify_owner);
679  			break;
680  		case SIGEV_THREAD:
681  			set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
682  			netlink_sendskb(info->notify_sock, info->notify_cookie);
683  			break;
684  		}
685  		/* after notification unregisters process */
686  		put_pid(info->notify_owner);
687  		put_user_ns(info->notify_user_ns);
688  		info->notify_owner = NULL;
689  		info->notify_user_ns = NULL;
690  	}
691  	wake_up(&info->wait_q);
692  }
693  
694  static int prepare_timeout(const struct __kernel_timespec __user *u_abs_timeout,
695  			   struct timespec64 *ts)
696  {
697  	if (get_timespec64(ts, u_abs_timeout))
698  		return -EFAULT;
699  	if (!timespec64_valid(ts))
700  		return -EINVAL;
701  	return 0;
702  }
703  
704  static void remove_notification(struct mqueue_inode_info *info)
705  {
706  	if (info->notify_owner != NULL &&
707  	    info->notify.sigev_notify == SIGEV_THREAD) {
708  		set_cookie(info->notify_cookie, NOTIFY_REMOVED);
709  		netlink_sendskb(info->notify_sock, info->notify_cookie);
710  	}
711  	put_pid(info->notify_owner);
712  	put_user_ns(info->notify_user_ns);
713  	info->notify_owner = NULL;
714  	info->notify_user_ns = NULL;
715  }
716  
717  static int prepare_open(struct dentry *dentry, int oflag, int ro,
718  			umode_t mode, struct filename *name,
719  			struct mq_attr *attr)
720  {
721  	static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
722  						  MAY_READ | MAY_WRITE };
723  	int acc;
724  
725  	if (d_really_is_negative(dentry)) {
726  		if (!(oflag & O_CREAT))
727  			return -ENOENT;
728  		if (ro)
729  			return ro;
730  		audit_inode_parent_hidden(name, dentry->d_parent);
731  		return vfs_mkobj(dentry, mode & ~current_umask(),
732  				  mqueue_create_attr, attr);
733  	}
734  	/* it already existed */
735  	audit_inode(name, dentry, 0);
736  	if ((oflag & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
737  		return -EEXIST;
738  	if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
739  		return -EINVAL;
740  	acc = oflag2acc[oflag & O_ACCMODE];
741  	return inode_permission(d_inode(dentry), acc);
742  }
743  
744  static int do_mq_open(const char __user *u_name, int oflag, umode_t mode,
745  		      struct mq_attr *attr)
746  {
747  	struct vfsmount *mnt = current->nsproxy->ipc_ns->mq_mnt;
748  	struct dentry *root = mnt->mnt_root;
749  	struct filename *name;
750  	struct path path;
751  	int fd, error;
752  	int ro;
753  
754  	audit_mq_open(oflag, mode, attr);
755  
756  	if (IS_ERR(name = getname(u_name)))
757  		return PTR_ERR(name);
758  
759  	fd = get_unused_fd_flags(O_CLOEXEC);
760  	if (fd < 0)
761  		goto out_putname;
762  
763  	ro = mnt_want_write(mnt);	/* we'll drop it in any case */
764  	inode_lock(d_inode(root));
765  	path.dentry = lookup_one_len(name->name, root, strlen(name->name));
766  	if (IS_ERR(path.dentry)) {
767  		error = PTR_ERR(path.dentry);
768  		goto out_putfd;
769  	}
770  	path.mnt = mntget(mnt);
771  	error = prepare_open(path.dentry, oflag, ro, mode, name, attr);
772  	if (!error) {
773  		struct file *file = dentry_open(&path, oflag, current_cred());
774  		if (!IS_ERR(file))
775  			fd_install(fd, file);
776  		else
777  			error = PTR_ERR(file);
778  	}
779  	path_put(&path);
780  out_putfd:
781  	if (error) {
782  		put_unused_fd(fd);
783  		fd = error;
784  	}
785  	inode_unlock(d_inode(root));
786  	if (!ro)
787  		mnt_drop_write(mnt);
788  out_putname:
789  	putname(name);
790  	return fd;
791  }
792  
793  SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
794  		struct mq_attr __user *, u_attr)
795  {
796  	struct mq_attr attr;
797  	if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
798  		return -EFAULT;
799  
800  	return do_mq_open(u_name, oflag, mode, u_attr ? &attr : NULL);
801  }
802  
803  SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
804  {
805  	int err;
806  	struct filename *name;
807  	struct dentry *dentry;
808  	struct inode *inode = NULL;
809  	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
810  	struct vfsmount *mnt = ipc_ns->mq_mnt;
811  
812  	name = getname(u_name);
813  	if (IS_ERR(name))
814  		return PTR_ERR(name);
815  
816  	audit_inode_parent_hidden(name, mnt->mnt_root);
817  	err = mnt_want_write(mnt);
818  	if (err)
819  		goto out_name;
820  	inode_lock_nested(d_inode(mnt->mnt_root), I_MUTEX_PARENT);
821  	dentry = lookup_one_len(name->name, mnt->mnt_root,
822  				strlen(name->name));
823  	if (IS_ERR(dentry)) {
824  		err = PTR_ERR(dentry);
825  		goto out_unlock;
826  	}
827  
828  	inode = d_inode(dentry);
829  	if (!inode) {
830  		err = -ENOENT;
831  	} else {
832  		ihold(inode);
833  		err = vfs_unlink(d_inode(dentry->d_parent), dentry, NULL);
834  	}
835  	dput(dentry);
836  
837  out_unlock:
838  	inode_unlock(d_inode(mnt->mnt_root));
839  	if (inode)
840  		iput(inode);
841  	mnt_drop_write(mnt);
842  out_name:
843  	putname(name);
844  
845  	return err;
846  }
847  
848  /* Pipelined send and receive functions.
849   *
850   * If a receiver finds no waiting message, then it registers itself in the
851   * list of waiting receivers. A sender checks that list before adding the new
852   * message into the message array. If there is a waiting receiver, then it
853   * bypasses the message array and directly hands the message over to the
854   * receiver. The receiver accepts the message and returns without grabbing the
855   * queue spinlock:
856   *
857   * - Set pointer to message.
858   * - Queue the receiver task for later wakeup (without the info->lock).
859   * - Update its state to STATE_READY. Now the receiver can continue.
860   * - Wake up the process after the lock is dropped. Should the process wake up
861   *   before this wakeup (due to a timeout or a signal) it will either see
862   *   STATE_READY and continue or acquire the lock to check the state again.
863   *
864   * The same algorithm is used for senders.
865   */
866  
867  /* pipelined_send() - send a message directly to the task waiting in
868   * sys_mq_timedreceive() (without inserting message into a queue).
869   */
870  static inline void pipelined_send(struct wake_q_head *wake_q,
871  				  struct mqueue_inode_info *info,
872  				  struct msg_msg *message,
873  				  struct ext_wait_queue *receiver)
874  {
875  	receiver->msg = message;
876  	list_del(&receiver->list);
877  	wake_q_add(wake_q, receiver->task);
878  	/*
879  	 * Rely on the implicit cmpxchg barrier from wake_q_add such
880  	 * that we can ensure that updating receiver->state is the last
881  	 * write operation: As once set, the receiver can continue,
882  	 * and if we don't have the reference count from the wake_q,
883  	 * yet, at that point we can later have a use-after-free
884  	 * condition and bogus wakeup.
885  	 */
886  	receiver->state = STATE_READY;
887  }
888  
889  /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
890   * gets its message and put to the queue (we have one free place for sure). */
891  static inline void pipelined_receive(struct wake_q_head *wake_q,
892  				     struct mqueue_inode_info *info)
893  {
894  	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
895  
896  	if (!sender) {
897  		/* for poll */
898  		wake_up_interruptible(&info->wait_q);
899  		return;
900  	}
901  	if (msg_insert(sender->msg, info))
902  		return;
903  
904  	list_del(&sender->list);
905  	wake_q_add(wake_q, sender->task);
906  	sender->state = STATE_READY;
907  }
908  
909  static int do_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
910  		size_t msg_len, unsigned int msg_prio,
911  		struct timespec64 *ts)
912  {
913  	struct fd f;
914  	struct inode *inode;
915  	struct ext_wait_queue wait;
916  	struct ext_wait_queue *receiver;
917  	struct msg_msg *msg_ptr;
918  	struct mqueue_inode_info *info;
919  	ktime_t expires, *timeout = NULL;
920  	struct posix_msg_tree_node *new_leaf = NULL;
921  	int ret = 0;
922  	DEFINE_WAKE_Q(wake_q);
923  
924  	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
925  		return -EINVAL;
926  
927  	if (ts) {
928  		expires = timespec64_to_ktime(*ts);
929  		timeout = &expires;
930  	}
931  
932  	audit_mq_sendrecv(mqdes, msg_len, msg_prio, ts);
933  
934  	f = fdget(mqdes);
935  	if (unlikely(!f.file)) {
936  		ret = -EBADF;
937  		goto out;
938  	}
939  
940  	inode = file_inode(f.file);
941  	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
942  		ret = -EBADF;
943  		goto out_fput;
944  	}
945  	info = MQUEUE_I(inode);
946  	audit_file(f.file);
947  
948  	if (unlikely(!(f.file->f_mode & FMODE_WRITE))) {
949  		ret = -EBADF;
950  		goto out_fput;
951  	}
952  
953  	if (unlikely(msg_len > info->attr.mq_msgsize)) {
954  		ret = -EMSGSIZE;
955  		goto out_fput;
956  	}
957  
958  	/* First try to allocate memory, before doing anything with
959  	 * existing queues. */
960  	msg_ptr = load_msg(u_msg_ptr, msg_len);
961  	if (IS_ERR(msg_ptr)) {
962  		ret = PTR_ERR(msg_ptr);
963  		goto out_fput;
964  	}
965  	msg_ptr->m_ts = msg_len;
966  	msg_ptr->m_type = msg_prio;
967  
968  	/*
969  	 * msg_insert really wants us to have a valid, spare node struct so
970  	 * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
971  	 * fall back to that if necessary.
972  	 */
973  	if (!info->node_cache)
974  		new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
975  
976  	spin_lock(&info->lock);
977  
978  	if (!info->node_cache && new_leaf) {
979  		/* Save our speculative allocation into the cache */
980  		INIT_LIST_HEAD(&new_leaf->msg_list);
981  		info->node_cache = new_leaf;
982  		new_leaf = NULL;
983  	} else {
984  		kfree(new_leaf);
985  	}
986  
987  	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
988  		if (f.file->f_flags & O_NONBLOCK) {
989  			ret = -EAGAIN;
990  		} else {
991  			wait.task = current;
992  			wait.msg = (void *) msg_ptr;
993  			wait.state = STATE_NONE;
994  			ret = wq_sleep(info, SEND, timeout, &wait);
995  			/*
996  			 * wq_sleep must be called with info->lock held, and
997  			 * returns with the lock released
998  			 */
999  			goto out_free;
1000  		}
1001  	} else {
1002  		receiver = wq_get_first_waiter(info, RECV);
1003  		if (receiver) {
1004  			pipelined_send(&wake_q, info, msg_ptr, receiver);
1005  		} else {
1006  			/* adds message to the queue */
1007  			ret = msg_insert(msg_ptr, info);
1008  			if (ret)
1009  				goto out_unlock;
1010  			__do_notify(info);
1011  		}
1012  		inode->i_atime = inode->i_mtime = inode->i_ctime =
1013  				current_time(inode);
1014  	}
1015  out_unlock:
1016  	spin_unlock(&info->lock);
1017  	wake_up_q(&wake_q);
1018  out_free:
1019  	if (ret)
1020  		free_msg(msg_ptr);
1021  out_fput:
1022  	fdput(f);
1023  out:
1024  	return ret;
1025  }
1026  
1027  static int do_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
1028  		size_t msg_len, unsigned int __user *u_msg_prio,
1029  		struct timespec64 *ts)
1030  {
1031  	ssize_t ret;
1032  	struct msg_msg *msg_ptr;
1033  	struct fd f;
1034  	struct inode *inode;
1035  	struct mqueue_inode_info *info;
1036  	struct ext_wait_queue wait;
1037  	ktime_t expires, *timeout = NULL;
1038  	struct posix_msg_tree_node *new_leaf = NULL;
1039  
1040  	if (ts) {
1041  		expires = timespec64_to_ktime(*ts);
1042  		timeout = &expires;
1043  	}
1044  
1045  	audit_mq_sendrecv(mqdes, msg_len, 0, ts);
1046  
1047  	f = fdget(mqdes);
1048  	if (unlikely(!f.file)) {
1049  		ret = -EBADF;
1050  		goto out;
1051  	}
1052  
1053  	inode = file_inode(f.file);
1054  	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1055  		ret = -EBADF;
1056  		goto out_fput;
1057  	}
1058  	info = MQUEUE_I(inode);
1059  	audit_file(f.file);
1060  
1061  	if (unlikely(!(f.file->f_mode & FMODE_READ))) {
1062  		ret = -EBADF;
1063  		goto out_fput;
1064  	}
1065  
1066  	/* checks if buffer is big enough */
1067  	if (unlikely(msg_len < info->attr.mq_msgsize)) {
1068  		ret = -EMSGSIZE;
1069  		goto out_fput;
1070  	}
1071  
1072  	/*
1073  	 * msg_insert really wants us to have a valid, spare node struct so
1074  	 * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1075  	 * fall back to that if necessary.
1076  	 */
1077  	if (!info->node_cache)
1078  		new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1079  
1080  	spin_lock(&info->lock);
1081  
1082  	if (!info->node_cache && new_leaf) {
1083  		/* Save our speculative allocation into the cache */
1084  		INIT_LIST_HEAD(&new_leaf->msg_list);
1085  		info->node_cache = new_leaf;
1086  	} else {
1087  		kfree(new_leaf);
1088  	}
1089  
1090  	if (info->attr.mq_curmsgs == 0) {
1091  		if (f.file->f_flags & O_NONBLOCK) {
1092  			spin_unlock(&info->lock);
1093  			ret = -EAGAIN;
1094  		} else {
1095  			wait.task = current;
1096  			wait.state = STATE_NONE;
1097  			ret = wq_sleep(info, RECV, timeout, &wait);
1098  			msg_ptr = wait.msg;
1099  		}
1100  	} else {
1101  		DEFINE_WAKE_Q(wake_q);
1102  
1103  		msg_ptr = msg_get(info);
1104  
1105  		inode->i_atime = inode->i_mtime = inode->i_ctime =
1106  				current_time(inode);
1107  
1108  		/* There is now free space in queue. */
1109  		pipelined_receive(&wake_q, info);
1110  		spin_unlock(&info->lock);
1111  		wake_up_q(&wake_q);
1112  		ret = 0;
1113  	}
1114  	if (ret == 0) {
1115  		ret = msg_ptr->m_ts;
1116  
1117  		if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1118  			store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1119  			ret = -EFAULT;
1120  		}
1121  		free_msg(msg_ptr);
1122  	}
1123  out_fput:
1124  	fdput(f);
1125  out:
1126  	return ret;
1127  }
1128  
1129  SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
1130  		size_t, msg_len, unsigned int, msg_prio,
1131  		const struct __kernel_timespec __user *, u_abs_timeout)
1132  {
1133  	struct timespec64 ts, *p = NULL;
1134  	if (u_abs_timeout) {
1135  		int res = prepare_timeout(u_abs_timeout, &ts);
1136  		if (res)
1137  			return res;
1138  		p = &ts;
1139  	}
1140  	return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p);
1141  }
1142  
1143  SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
1144  		size_t, msg_len, unsigned int __user *, u_msg_prio,
1145  		const struct __kernel_timespec __user *, u_abs_timeout)
1146  {
1147  	struct timespec64 ts, *p = NULL;
1148  	if (u_abs_timeout) {
1149  		int res = prepare_timeout(u_abs_timeout, &ts);
1150  		if (res)
1151  			return res;
1152  		p = &ts;
1153  	}
1154  	return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p);
1155  }
1156  
1157  /*
1158   * Notes: the case when user wants us to deregister (with NULL as pointer)
1159   * and he isn't currently owner of notification, will be silently discarded.
1160   * It isn't explicitly defined in the POSIX.
1161   */
1162  static int do_mq_notify(mqd_t mqdes, const struct sigevent *notification)
1163  {
1164  	int ret;
1165  	struct fd f;
1166  	struct sock *sock;
1167  	struct inode *inode;
1168  	struct mqueue_inode_info *info;
1169  	struct sk_buff *nc;
1170  
1171  	audit_mq_notify(mqdes, notification);
1172  
1173  	nc = NULL;
1174  	sock = NULL;
1175  	if (notification != NULL) {
1176  		if (unlikely(notification->sigev_notify != SIGEV_NONE &&
1177  			     notification->sigev_notify != SIGEV_SIGNAL &&
1178  			     notification->sigev_notify != SIGEV_THREAD))
1179  			return -EINVAL;
1180  		if (notification->sigev_notify == SIGEV_SIGNAL &&
1181  			!valid_signal(notification->sigev_signo)) {
1182  			return -EINVAL;
1183  		}
1184  		if (notification->sigev_notify == SIGEV_THREAD) {
1185  			long timeo;
1186  
1187  			/* create the notify skb */
1188  			nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1189  			if (!nc) {
1190  				ret = -ENOMEM;
1191  				goto out;
1192  			}
1193  			if (copy_from_user(nc->data,
1194  					notification->sigev_value.sival_ptr,
1195  					NOTIFY_COOKIE_LEN)) {
1196  				ret = -EFAULT;
1197  				goto out;
1198  			}
1199  
1200  			/* TODO: add a header? */
1201  			skb_put(nc, NOTIFY_COOKIE_LEN);
1202  			/* and attach it to the socket */
1203  retry:
1204  			f = fdget(notification->sigev_signo);
1205  			if (!f.file) {
1206  				ret = -EBADF;
1207  				goto out;
1208  			}
1209  			sock = netlink_getsockbyfilp(f.file);
1210  			fdput(f);
1211  			if (IS_ERR(sock)) {
1212  				ret = PTR_ERR(sock);
1213  				sock = NULL;
1214  				goto out;
1215  			}
1216  
1217  			timeo = MAX_SCHEDULE_TIMEOUT;
1218  			ret = netlink_attachskb(sock, nc, &timeo, NULL);
1219  			if (ret == 1) {
1220  				sock = NULL;
1221  				goto retry;
1222  			}
1223  			if (ret) {
1224  				sock = NULL;
1225  				nc = NULL;
1226  				goto out;
1227  			}
1228  		}
1229  	}
1230  
1231  	f = fdget(mqdes);
1232  	if (!f.file) {
1233  		ret = -EBADF;
1234  		goto out;
1235  	}
1236  
1237  	inode = file_inode(f.file);
1238  	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1239  		ret = -EBADF;
1240  		goto out_fput;
1241  	}
1242  	info = MQUEUE_I(inode);
1243  
1244  	ret = 0;
1245  	spin_lock(&info->lock);
1246  	if (notification == NULL) {
1247  		if (info->notify_owner == task_tgid(current)) {
1248  			remove_notification(info);
1249  			inode->i_atime = inode->i_ctime = current_time(inode);
1250  		}
1251  	} else if (info->notify_owner != NULL) {
1252  		ret = -EBUSY;
1253  	} else {
1254  		switch (notification->sigev_notify) {
1255  		case SIGEV_NONE:
1256  			info->notify.sigev_notify = SIGEV_NONE;
1257  			break;
1258  		case SIGEV_THREAD:
1259  			info->notify_sock = sock;
1260  			info->notify_cookie = nc;
1261  			sock = NULL;
1262  			nc = NULL;
1263  			info->notify.sigev_notify = SIGEV_THREAD;
1264  			break;
1265  		case SIGEV_SIGNAL:
1266  			info->notify.sigev_signo = notification->sigev_signo;
1267  			info->notify.sigev_value = notification->sigev_value;
1268  			info->notify.sigev_notify = SIGEV_SIGNAL;
1269  			break;
1270  		}
1271  
1272  		info->notify_owner = get_pid(task_tgid(current));
1273  		info->notify_user_ns = get_user_ns(current_user_ns());
1274  		inode->i_atime = inode->i_ctime = current_time(inode);
1275  	}
1276  	spin_unlock(&info->lock);
1277  out_fput:
1278  	fdput(f);
1279  out:
1280  	if (sock)
1281  		netlink_detachskb(sock, nc);
1282  	else if (nc)
1283  		dev_kfree_skb(nc);
1284  
1285  	return ret;
1286  }
1287  
1288  SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1289  		const struct sigevent __user *, u_notification)
1290  {
1291  	struct sigevent n, *p = NULL;
1292  	if (u_notification) {
1293  		if (copy_from_user(&n, u_notification, sizeof(struct sigevent)))
1294  			return -EFAULT;
1295  		p = &n;
1296  	}
1297  	return do_mq_notify(mqdes, p);
1298  }
1299  
1300  static int do_mq_getsetattr(int mqdes, struct mq_attr *new, struct mq_attr *old)
1301  {
1302  	struct fd f;
1303  	struct inode *inode;
1304  	struct mqueue_inode_info *info;
1305  
1306  	if (new && (new->mq_flags & (~O_NONBLOCK)))
1307  		return -EINVAL;
1308  
1309  	f = fdget(mqdes);
1310  	if (!f.file)
1311  		return -EBADF;
1312  
1313  	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1314  		fdput(f);
1315  		return -EBADF;
1316  	}
1317  
1318  	inode = file_inode(f.file);
1319  	info = MQUEUE_I(inode);
1320  
1321  	spin_lock(&info->lock);
1322  
1323  	if (old) {
1324  		*old = info->attr;
1325  		old->mq_flags = f.file->f_flags & O_NONBLOCK;
1326  	}
1327  	if (new) {
1328  		audit_mq_getsetattr(mqdes, new);
1329  		spin_lock(&f.file->f_lock);
1330  		if (new->mq_flags & O_NONBLOCK)
1331  			f.file->f_flags |= O_NONBLOCK;
1332  		else
1333  			f.file->f_flags &= ~O_NONBLOCK;
1334  		spin_unlock(&f.file->f_lock);
1335  
1336  		inode->i_atime = inode->i_ctime = current_time(inode);
1337  	}
1338  
1339  	spin_unlock(&info->lock);
1340  	fdput(f);
1341  	return 0;
1342  }
1343  
1344  SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1345  		const struct mq_attr __user *, u_mqstat,
1346  		struct mq_attr __user *, u_omqstat)
1347  {
1348  	int ret;
1349  	struct mq_attr mqstat, omqstat;
1350  	struct mq_attr *new = NULL, *old = NULL;
1351  
1352  	if (u_mqstat) {
1353  		new = &mqstat;
1354  		if (copy_from_user(new, u_mqstat, sizeof(struct mq_attr)))
1355  			return -EFAULT;
1356  	}
1357  	if (u_omqstat)
1358  		old = &omqstat;
1359  
1360  	ret = do_mq_getsetattr(mqdes, new, old);
1361  	if (ret || !old)
1362  		return ret;
1363  
1364  	if (copy_to_user(u_omqstat, old, sizeof(struct mq_attr)))
1365  		return -EFAULT;
1366  	return 0;
1367  }
1368  
1369  #ifdef CONFIG_COMPAT
1370  
1371  struct compat_mq_attr {
1372  	compat_long_t mq_flags;      /* message queue flags		     */
1373  	compat_long_t mq_maxmsg;     /* maximum number of messages	     */
1374  	compat_long_t mq_msgsize;    /* maximum message size		     */
1375  	compat_long_t mq_curmsgs;    /* number of messages currently queued  */
1376  	compat_long_t __reserved[4]; /* ignored for input, zeroed for output */
1377  };
1378  
1379  static inline int get_compat_mq_attr(struct mq_attr *attr,
1380  			const struct compat_mq_attr __user *uattr)
1381  {
1382  	struct compat_mq_attr v;
1383  
1384  	if (copy_from_user(&v, uattr, sizeof(*uattr)))
1385  		return -EFAULT;
1386  
1387  	memset(attr, 0, sizeof(*attr));
1388  	attr->mq_flags = v.mq_flags;
1389  	attr->mq_maxmsg = v.mq_maxmsg;
1390  	attr->mq_msgsize = v.mq_msgsize;
1391  	attr->mq_curmsgs = v.mq_curmsgs;
1392  	return 0;
1393  }
1394  
1395  static inline int put_compat_mq_attr(const struct mq_attr *attr,
1396  			struct compat_mq_attr __user *uattr)
1397  {
1398  	struct compat_mq_attr v;
1399  
1400  	memset(&v, 0, sizeof(v));
1401  	v.mq_flags = attr->mq_flags;
1402  	v.mq_maxmsg = attr->mq_maxmsg;
1403  	v.mq_msgsize = attr->mq_msgsize;
1404  	v.mq_curmsgs = attr->mq_curmsgs;
1405  	if (copy_to_user(uattr, &v, sizeof(*uattr)))
1406  		return -EFAULT;
1407  	return 0;
1408  }
1409  
1410  COMPAT_SYSCALL_DEFINE4(mq_open, const char __user *, u_name,
1411  		       int, oflag, compat_mode_t, mode,
1412  		       struct compat_mq_attr __user *, u_attr)
1413  {
1414  	struct mq_attr attr, *p = NULL;
1415  	if (u_attr && oflag & O_CREAT) {
1416  		p = &attr;
1417  		if (get_compat_mq_attr(&attr, u_attr))
1418  			return -EFAULT;
1419  	}
1420  	return do_mq_open(u_name, oflag, mode, p);
1421  }
1422  
1423  COMPAT_SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1424  		       const struct compat_sigevent __user *, u_notification)
1425  {
1426  	struct sigevent n, *p = NULL;
1427  	if (u_notification) {
1428  		if (get_compat_sigevent(&n, u_notification))
1429  			return -EFAULT;
1430  		if (n.sigev_notify == SIGEV_THREAD)
1431  			n.sigev_value.sival_ptr = compat_ptr(n.sigev_value.sival_int);
1432  		p = &n;
1433  	}
1434  	return do_mq_notify(mqdes, p);
1435  }
1436  
1437  COMPAT_SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1438  		       const struct compat_mq_attr __user *, u_mqstat,
1439  		       struct compat_mq_attr __user *, u_omqstat)
1440  {
1441  	int ret;
1442  	struct mq_attr mqstat, omqstat;
1443  	struct mq_attr *new = NULL, *old = NULL;
1444  
1445  	if (u_mqstat) {
1446  		new = &mqstat;
1447  		if (get_compat_mq_attr(new, u_mqstat))
1448  			return -EFAULT;
1449  	}
1450  	if (u_omqstat)
1451  		old = &omqstat;
1452  
1453  	ret = do_mq_getsetattr(mqdes, new, old);
1454  	if (ret || !old)
1455  		return ret;
1456  
1457  	if (put_compat_mq_attr(old, u_omqstat))
1458  		return -EFAULT;
1459  	return 0;
1460  }
1461  #endif
1462  
1463  #ifdef CONFIG_COMPAT_32BIT_TIME
1464  static int compat_prepare_timeout(const struct compat_timespec __user *p,
1465  				   struct timespec64 *ts)
1466  {
1467  	if (compat_get_timespec64(ts, p))
1468  		return -EFAULT;
1469  	if (!timespec64_valid(ts))
1470  		return -EINVAL;
1471  	return 0;
1472  }
1473  
1474  COMPAT_SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes,
1475  		       const char __user *, u_msg_ptr,
1476  		       compat_size_t, msg_len, unsigned int, msg_prio,
1477  		       const struct compat_timespec __user *, u_abs_timeout)
1478  {
1479  	struct timespec64 ts, *p = NULL;
1480  	if (u_abs_timeout) {
1481  		int res = compat_prepare_timeout(u_abs_timeout, &ts);
1482  		if (res)
1483  			return res;
1484  		p = &ts;
1485  	}
1486  	return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p);
1487  }
1488  
1489  COMPAT_SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes,
1490  		       char __user *, u_msg_ptr,
1491  		       compat_size_t, msg_len, unsigned int __user *, u_msg_prio,
1492  		       const struct compat_timespec __user *, u_abs_timeout)
1493  {
1494  	struct timespec64 ts, *p = NULL;
1495  	if (u_abs_timeout) {
1496  		int res = compat_prepare_timeout(u_abs_timeout, &ts);
1497  		if (res)
1498  			return res;
1499  		p = &ts;
1500  	}
1501  	return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p);
1502  }
1503  #endif
1504  
1505  static const struct inode_operations mqueue_dir_inode_operations = {
1506  	.lookup = simple_lookup,
1507  	.create = mqueue_create,
1508  	.unlink = mqueue_unlink,
1509  };
1510  
1511  static const struct file_operations mqueue_file_operations = {
1512  	.flush = mqueue_flush_file,
1513  	.poll = mqueue_poll_file,
1514  	.read = mqueue_read_file,
1515  	.llseek = default_llseek,
1516  };
1517  
1518  static const struct super_operations mqueue_super_ops = {
1519  	.alloc_inode = mqueue_alloc_inode,
1520  	.destroy_inode = mqueue_destroy_inode,
1521  	.evict_inode = mqueue_evict_inode,
1522  	.statfs = simple_statfs,
1523  };
1524  
1525  static struct file_system_type mqueue_fs_type = {
1526  	.name = "mqueue",
1527  	.mount = mqueue_mount,
1528  	.kill_sb = kill_litter_super,
1529  	.fs_flags = FS_USERNS_MOUNT,
1530  };
1531  
1532  int mq_init_ns(struct ipc_namespace *ns)
1533  {
1534  	ns->mq_queues_count  = 0;
1535  	ns->mq_queues_max    = DFLT_QUEUESMAX;
1536  	ns->mq_msg_max       = DFLT_MSGMAX;
1537  	ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1538  	ns->mq_msg_default   = DFLT_MSG;
1539  	ns->mq_msgsize_default  = DFLT_MSGSIZE;
1540  
1541  	ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1542  	if (IS_ERR(ns->mq_mnt)) {
1543  		int err = PTR_ERR(ns->mq_mnt);
1544  		ns->mq_mnt = NULL;
1545  		return err;
1546  	}
1547  	return 0;
1548  }
1549  
1550  void mq_clear_sbinfo(struct ipc_namespace *ns)
1551  {
1552  	ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1553  }
1554  
1555  void mq_put_mnt(struct ipc_namespace *ns)
1556  {
1557  	kern_unmount(ns->mq_mnt);
1558  }
1559  
1560  static int __init init_mqueue_fs(void)
1561  {
1562  	int error;
1563  
1564  	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1565  				sizeof(struct mqueue_inode_info), 0,
1566  				SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT, init_once);
1567  	if (mqueue_inode_cachep == NULL)
1568  		return -ENOMEM;
1569  
1570  	/* ignore failures - they are not fatal */
1571  	mq_sysctl_table = mq_register_sysctl_table();
1572  
1573  	error = register_filesystem(&mqueue_fs_type);
1574  	if (error)
1575  		goto out_sysctl;
1576  
1577  	spin_lock_init(&mq_lock);
1578  
1579  	error = mq_init_ns(&init_ipc_ns);
1580  	if (error)
1581  		goto out_filesystem;
1582  
1583  	return 0;
1584  
1585  out_filesystem:
1586  	unregister_filesystem(&mqueue_fs_type);
1587  out_sysctl:
1588  	if (mq_sysctl_table)
1589  		unregister_sysctl_table(mq_sysctl_table);
1590  	kmem_cache_destroy(mqueue_inode_cachep);
1591  	return error;
1592  }
1593  
1594  device_initcall(init_mqueue_fs);
1595