xref: /openbmc/linux/ipc/mqueue.c (revision b18d2847)
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/fs_context.h>
22 #include <linux/namei.h>
23 #include <linux/sysctl.h>
24 #include <linux/poll.h>
25 #include <linux/mqueue.h>
26 #include <linux/msg.h>
27 #include <linux/skbuff.h>
28 #include <linux/vmalloc.h>
29 #include <linux/netlink.h>
30 #include <linux/syscalls.h>
31 #include <linux/audit.h>
32 #include <linux/signal.h>
33 #include <linux/mutex.h>
34 #include <linux/nsproxy.h>
35 #include <linux/pid.h>
36 #include <linux/ipc_namespace.h>
37 #include <linux/user_namespace.h>
38 #include <linux/slab.h>
39 #include <linux/sched/wake_q.h>
40 #include <linux/sched/signal.h>
41 #include <linux/sched/user.h>
42 
43 #include <net/sock.h>
44 #include "util.h"
45 
46 struct mqueue_fs_context {
47 	struct ipc_namespace	*ipc_ns;
48 };
49 
50 #define MQUEUE_MAGIC	0x19800202
51 #define DIRENT_SIZE	20
52 #define FILENT_SIZE	80
53 
54 #define SEND		0
55 #define RECV		1
56 
57 #define STATE_NONE	0
58 #define STATE_READY	1
59 
60 struct posix_msg_tree_node {
61 	struct rb_node		rb_node;
62 	struct list_head	msg_list;
63 	int			priority;
64 };
65 
66 /*
67  * Locking:
68  *
69  * Accesses to a message queue are synchronized by acquiring info->lock.
70  *
71  * There are two notable exceptions:
72  * - The actual wakeup of a sleeping task is performed using the wake_q
73  *   framework. info->lock is already released when wake_up_q is called.
74  * - The exit codepaths after sleeping check ext_wait_queue->state without
75  *   any locks. If it is STATE_READY, then the syscall is completed without
76  *   acquiring info->lock.
77  *
78  * MQ_BARRIER:
79  * To achieve proper release/acquire memory barrier pairing, the state is set to
80  * STATE_READY with smp_store_release(), and it is read with READ_ONCE followed
81  * by smp_acquire__after_ctrl_dep(). In addition, wake_q_add_safe() is used.
82  *
83  * This prevents the following races:
84  *
85  * 1) With the simple wake_q_add(), the task could be gone already before
86  *    the increase of the reference happens
87  * Thread A
88  *				Thread B
89  * WRITE_ONCE(wait.state, STATE_NONE);
90  * schedule_hrtimeout()
91  *				wake_q_add(A)
92  *				if (cmpxchg()) // success
93  *				   ->state = STATE_READY (reordered)
94  * <timeout returns>
95  * if (wait.state == STATE_READY) return;
96  * sysret to user space
97  * sys_exit()
98  *				get_task_struct() // UaF
99  *
100  * Solution: Use wake_q_add_safe() and perform the get_task_struct() before
101  * the smp_store_release() that does ->state = STATE_READY.
102  *
103  * 2) Without proper _release/_acquire barriers, the woken up task
104  *    could read stale data
105  *
106  * Thread A
107  *				Thread B
108  * do_mq_timedreceive
109  * WRITE_ONCE(wait.state, STATE_NONE);
110  * schedule_hrtimeout()
111  *				state = STATE_READY;
112  * <timeout returns>
113  * if (wait.state == STATE_READY) return;
114  * msg_ptr = wait.msg;		// Access to stale data!
115  *				receiver->msg = message; (reordered)
116  *
117  * Solution: use _release and _acquire barriers.
118  *
119  * 3) There is intentionally no barrier when setting current->state
120  *    to TASK_INTERRUPTIBLE: spin_unlock(&info->lock) provides the
121  *    release memory barrier, and the wakeup is triggered when holding
122  *    info->lock, i.e. spin_lock(&info->lock) provided a pairing
123  *    acquire memory barrier.
124  */
125 
126 struct ext_wait_queue {		/* queue of sleeping tasks */
127 	struct task_struct *task;
128 	struct list_head list;
129 	struct msg_msg *msg;	/* ptr of loaded message */
130 	int state;		/* one of STATE_* values */
131 };
132 
133 struct mqueue_inode_info {
134 	spinlock_t lock;
135 	struct inode vfs_inode;
136 	wait_queue_head_t wait_q;
137 
138 	struct rb_root msg_tree;
139 	struct rb_node *msg_tree_rightmost;
140 	struct posix_msg_tree_node *node_cache;
141 	struct mq_attr attr;
142 
143 	struct sigevent notify;
144 	struct pid *notify_owner;
145 	u32 notify_self_exec_id;
146 	struct user_namespace *notify_user_ns;
147 	struct ucounts *ucounts;	/* user who created, for accounting */
148 	struct sock *notify_sock;
149 	struct sk_buff *notify_cookie;
150 
151 	/* for tasks waiting for free space and messages, respectively */
152 	struct ext_wait_queue e_wait_q[2];
153 
154 	unsigned long qsize; /* size of queue in memory (sum of all msgs) */
155 };
156 
157 static struct file_system_type mqueue_fs_type;
158 static const struct inode_operations mqueue_dir_inode_operations;
159 static const struct file_operations mqueue_file_operations;
160 static const struct super_operations mqueue_super_ops;
161 static const struct fs_context_operations mqueue_fs_context_ops;
162 static void remove_notification(struct mqueue_inode_info *info);
163 
164 static struct kmem_cache *mqueue_inode_cachep;
165 
166 static struct ctl_table_header *mq_sysctl_table;
167 
168 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
169 {
170 	return container_of(inode, struct mqueue_inode_info, vfs_inode);
171 }
172 
173 /*
174  * This routine should be called with the mq_lock held.
175  */
176 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
177 {
178 	return get_ipc_ns(inode->i_sb->s_fs_info);
179 }
180 
181 static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
182 {
183 	struct ipc_namespace *ns;
184 
185 	spin_lock(&mq_lock);
186 	ns = __get_ns_from_inode(inode);
187 	spin_unlock(&mq_lock);
188 	return ns;
189 }
190 
191 /* Auxiliary functions to manipulate messages' list */
192 static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
193 {
194 	struct rb_node **p, *parent = NULL;
195 	struct posix_msg_tree_node *leaf;
196 	bool rightmost = true;
197 
198 	p = &info->msg_tree.rb_node;
199 	while (*p) {
200 		parent = *p;
201 		leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
202 
203 		if (likely(leaf->priority == msg->m_type))
204 			goto insert_msg;
205 		else if (msg->m_type < leaf->priority) {
206 			p = &(*p)->rb_left;
207 			rightmost = false;
208 		} else
209 			p = &(*p)->rb_right;
210 	}
211 	if (info->node_cache) {
212 		leaf = info->node_cache;
213 		info->node_cache = NULL;
214 	} else {
215 		leaf = kmalloc(sizeof(*leaf), GFP_ATOMIC);
216 		if (!leaf)
217 			return -ENOMEM;
218 		INIT_LIST_HEAD(&leaf->msg_list);
219 	}
220 	leaf->priority = msg->m_type;
221 
222 	if (rightmost)
223 		info->msg_tree_rightmost = &leaf->rb_node;
224 
225 	rb_link_node(&leaf->rb_node, parent, p);
226 	rb_insert_color(&leaf->rb_node, &info->msg_tree);
227 insert_msg:
228 	info->attr.mq_curmsgs++;
229 	info->qsize += msg->m_ts;
230 	list_add_tail(&msg->m_list, &leaf->msg_list);
231 	return 0;
232 }
233 
234 static inline void msg_tree_erase(struct posix_msg_tree_node *leaf,
235 				  struct mqueue_inode_info *info)
236 {
237 	struct rb_node *node = &leaf->rb_node;
238 
239 	if (info->msg_tree_rightmost == node)
240 		info->msg_tree_rightmost = rb_prev(node);
241 
242 	rb_erase(node, &info->msg_tree);
243 	if (info->node_cache)
244 		kfree(leaf);
245 	else
246 		info->node_cache = leaf;
247 }
248 
249 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
250 {
251 	struct rb_node *parent = NULL;
252 	struct posix_msg_tree_node *leaf;
253 	struct msg_msg *msg;
254 
255 try_again:
256 	/*
257 	 * During insert, low priorities go to the left and high to the
258 	 * right.  On receive, we want the highest priorities first, so
259 	 * walk all the way to the right.
260 	 */
261 	parent = info->msg_tree_rightmost;
262 	if (!parent) {
263 		if (info->attr.mq_curmsgs) {
264 			pr_warn_once("Inconsistency in POSIX message queue, "
265 				     "no tree element, but supposedly messages "
266 				     "should exist!\n");
267 			info->attr.mq_curmsgs = 0;
268 		}
269 		return NULL;
270 	}
271 	leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
272 	if (unlikely(list_empty(&leaf->msg_list))) {
273 		pr_warn_once("Inconsistency in POSIX message queue, "
274 			     "empty leaf node but we haven't implemented "
275 			     "lazy leaf delete!\n");
276 		msg_tree_erase(leaf, info);
277 		goto try_again;
278 	} else {
279 		msg = list_first_entry(&leaf->msg_list,
280 				       struct msg_msg, m_list);
281 		list_del(&msg->m_list);
282 		if (list_empty(&leaf->msg_list)) {
283 			msg_tree_erase(leaf, info);
284 		}
285 	}
286 	info->attr.mq_curmsgs--;
287 	info->qsize -= msg->m_ts;
288 	return msg;
289 }
290 
291 static struct inode *mqueue_get_inode(struct super_block *sb,
292 		struct ipc_namespace *ipc_ns, umode_t mode,
293 		struct mq_attr *attr)
294 {
295 	struct inode *inode;
296 	int ret = -ENOMEM;
297 
298 	inode = new_inode(sb);
299 	if (!inode)
300 		goto err;
301 
302 	inode->i_ino = get_next_ino();
303 	inode->i_mode = mode;
304 	inode->i_uid = current_fsuid();
305 	inode->i_gid = current_fsgid();
306 	inode->i_mtime = inode->i_ctime = inode->i_atime = current_time(inode);
307 
308 	if (S_ISREG(mode)) {
309 		struct mqueue_inode_info *info;
310 		unsigned long mq_bytes, mq_treesize;
311 
312 		inode->i_fop = &mqueue_file_operations;
313 		inode->i_size = FILENT_SIZE;
314 		/* mqueue specific info */
315 		info = MQUEUE_I(inode);
316 		spin_lock_init(&info->lock);
317 		init_waitqueue_head(&info->wait_q);
318 		INIT_LIST_HEAD(&info->e_wait_q[0].list);
319 		INIT_LIST_HEAD(&info->e_wait_q[1].list);
320 		info->notify_owner = NULL;
321 		info->notify_user_ns = NULL;
322 		info->qsize = 0;
323 		info->ucounts = NULL;	/* set when all is ok */
324 		info->msg_tree = RB_ROOT;
325 		info->msg_tree_rightmost = NULL;
326 		info->node_cache = NULL;
327 		memset(&info->attr, 0, sizeof(info->attr));
328 		info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
329 					   ipc_ns->mq_msg_default);
330 		info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
331 					    ipc_ns->mq_msgsize_default);
332 		if (attr) {
333 			info->attr.mq_maxmsg = attr->mq_maxmsg;
334 			info->attr.mq_msgsize = attr->mq_msgsize;
335 		}
336 		/*
337 		 * We used to allocate a static array of pointers and account
338 		 * the size of that array as well as one msg_msg struct per
339 		 * possible message into the queue size. That's no longer
340 		 * accurate as the queue is now an rbtree and will grow and
341 		 * shrink depending on usage patterns.  We can, however, still
342 		 * account one msg_msg struct per message, but the nodes are
343 		 * allocated depending on priority usage, and most programs
344 		 * only use one, or a handful, of priorities.  However, since
345 		 * this is pinned memory, we need to assume worst case, so
346 		 * that means the min(mq_maxmsg, max_priorities) * struct
347 		 * posix_msg_tree_node.
348 		 */
349 
350 		ret = -EINVAL;
351 		if (info->attr.mq_maxmsg <= 0 || info->attr.mq_msgsize <= 0)
352 			goto out_inode;
353 		if (capable(CAP_SYS_RESOURCE)) {
354 			if (info->attr.mq_maxmsg > HARD_MSGMAX ||
355 			    info->attr.mq_msgsize > HARD_MSGSIZEMAX)
356 				goto out_inode;
357 		} else {
358 			if (info->attr.mq_maxmsg > ipc_ns->mq_msg_max ||
359 					info->attr.mq_msgsize > ipc_ns->mq_msgsize_max)
360 				goto out_inode;
361 		}
362 		ret = -EOVERFLOW;
363 		/* check for overflow */
364 		if (info->attr.mq_msgsize > ULONG_MAX/info->attr.mq_maxmsg)
365 			goto out_inode;
366 		mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
367 			min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
368 			sizeof(struct posix_msg_tree_node);
369 		mq_bytes = info->attr.mq_maxmsg * info->attr.mq_msgsize;
370 		if (mq_bytes + mq_treesize < mq_bytes)
371 			goto out_inode;
372 		mq_bytes += mq_treesize;
373 		info->ucounts = get_ucounts(current_ucounts());
374 		if (info->ucounts) {
375 			long msgqueue;
376 
377 			spin_lock(&mq_lock);
378 			msgqueue = inc_rlimit_ucounts(info->ucounts, UCOUNT_RLIMIT_MSGQUEUE, mq_bytes);
379 			if (msgqueue == LONG_MAX || msgqueue > rlimit(RLIMIT_MSGQUEUE)) {
380 				dec_rlimit_ucounts(info->ucounts, UCOUNT_RLIMIT_MSGQUEUE, mq_bytes);
381 				spin_unlock(&mq_lock);
382 				put_ucounts(info->ucounts);
383 				info->ucounts = NULL;
384 				/* mqueue_evict_inode() releases info->messages */
385 				ret = -EMFILE;
386 				goto out_inode;
387 			}
388 			spin_unlock(&mq_lock);
389 		}
390 	} else if (S_ISDIR(mode)) {
391 		inc_nlink(inode);
392 		/* Some things misbehave if size == 0 on a directory */
393 		inode->i_size = 2 * DIRENT_SIZE;
394 		inode->i_op = &mqueue_dir_inode_operations;
395 		inode->i_fop = &simple_dir_operations;
396 	}
397 
398 	return inode;
399 out_inode:
400 	iput(inode);
401 err:
402 	return ERR_PTR(ret);
403 }
404 
405 static int mqueue_fill_super(struct super_block *sb, struct fs_context *fc)
406 {
407 	struct inode *inode;
408 	struct ipc_namespace *ns = sb->s_fs_info;
409 
410 	sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV;
411 	sb->s_blocksize = PAGE_SIZE;
412 	sb->s_blocksize_bits = PAGE_SHIFT;
413 	sb->s_magic = MQUEUE_MAGIC;
414 	sb->s_op = &mqueue_super_ops;
415 
416 	inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
417 	if (IS_ERR(inode))
418 		return PTR_ERR(inode);
419 
420 	sb->s_root = d_make_root(inode);
421 	if (!sb->s_root)
422 		return -ENOMEM;
423 	return 0;
424 }
425 
426 static int mqueue_get_tree(struct fs_context *fc)
427 {
428 	struct mqueue_fs_context *ctx = fc->fs_private;
429 
430 	return get_tree_keyed(fc, mqueue_fill_super, ctx->ipc_ns);
431 }
432 
433 static void mqueue_fs_context_free(struct fs_context *fc)
434 {
435 	struct mqueue_fs_context *ctx = fc->fs_private;
436 
437 	put_ipc_ns(ctx->ipc_ns);
438 	kfree(ctx);
439 }
440 
441 static int mqueue_init_fs_context(struct fs_context *fc)
442 {
443 	struct mqueue_fs_context *ctx;
444 
445 	ctx = kzalloc(sizeof(struct mqueue_fs_context), GFP_KERNEL);
446 	if (!ctx)
447 		return -ENOMEM;
448 
449 	ctx->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
450 	put_user_ns(fc->user_ns);
451 	fc->user_ns = get_user_ns(ctx->ipc_ns->user_ns);
452 	fc->fs_private = ctx;
453 	fc->ops = &mqueue_fs_context_ops;
454 	return 0;
455 }
456 
457 static struct vfsmount *mq_create_mount(struct ipc_namespace *ns)
458 {
459 	struct mqueue_fs_context *ctx;
460 	struct fs_context *fc;
461 	struct vfsmount *mnt;
462 
463 	fc = fs_context_for_mount(&mqueue_fs_type, SB_KERNMOUNT);
464 	if (IS_ERR(fc))
465 		return ERR_CAST(fc);
466 
467 	ctx = fc->fs_private;
468 	put_ipc_ns(ctx->ipc_ns);
469 	ctx->ipc_ns = get_ipc_ns(ns);
470 	put_user_ns(fc->user_ns);
471 	fc->user_ns = get_user_ns(ctx->ipc_ns->user_ns);
472 
473 	mnt = fc_mount(fc);
474 	put_fs_context(fc);
475 	return mnt;
476 }
477 
478 static void init_once(void *foo)
479 {
480 	struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
481 
482 	inode_init_once(&p->vfs_inode);
483 }
484 
485 static struct inode *mqueue_alloc_inode(struct super_block *sb)
486 {
487 	struct mqueue_inode_info *ei;
488 
489 	ei = alloc_inode_sb(sb, mqueue_inode_cachep, GFP_KERNEL);
490 	if (!ei)
491 		return NULL;
492 	return &ei->vfs_inode;
493 }
494 
495 static void mqueue_free_inode(struct inode *inode)
496 {
497 	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
498 }
499 
500 static void mqueue_evict_inode(struct inode *inode)
501 {
502 	struct mqueue_inode_info *info;
503 	struct ipc_namespace *ipc_ns;
504 	struct msg_msg *msg, *nmsg;
505 	LIST_HEAD(tmp_msg);
506 
507 	clear_inode(inode);
508 
509 	if (S_ISDIR(inode->i_mode))
510 		return;
511 
512 	ipc_ns = get_ns_from_inode(inode);
513 	info = MQUEUE_I(inode);
514 	spin_lock(&info->lock);
515 	while ((msg = msg_get(info)) != NULL)
516 		list_add_tail(&msg->m_list, &tmp_msg);
517 	kfree(info->node_cache);
518 	spin_unlock(&info->lock);
519 
520 	list_for_each_entry_safe(msg, nmsg, &tmp_msg, m_list) {
521 		list_del(&msg->m_list);
522 		free_msg(msg);
523 	}
524 
525 	if (info->ucounts) {
526 		unsigned long mq_bytes, mq_treesize;
527 
528 		/* Total amount of bytes accounted for the mqueue */
529 		mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
530 			min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
531 			sizeof(struct posix_msg_tree_node);
532 
533 		mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
534 					  info->attr.mq_msgsize);
535 
536 		spin_lock(&mq_lock);
537 		dec_rlimit_ucounts(info->ucounts, UCOUNT_RLIMIT_MSGQUEUE, mq_bytes);
538 		/*
539 		 * get_ns_from_inode() ensures that the
540 		 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
541 		 * to which we now hold a reference, or it is NULL.
542 		 * We can't put it here under mq_lock, though.
543 		 */
544 		if (ipc_ns)
545 			ipc_ns->mq_queues_count--;
546 		spin_unlock(&mq_lock);
547 		put_ucounts(info->ucounts);
548 		info->ucounts = NULL;
549 	}
550 	if (ipc_ns)
551 		put_ipc_ns(ipc_ns);
552 }
553 
554 static int mqueue_create_attr(struct dentry *dentry, umode_t mode, void *arg)
555 {
556 	struct inode *dir = dentry->d_parent->d_inode;
557 	struct inode *inode;
558 	struct mq_attr *attr = arg;
559 	int error;
560 	struct ipc_namespace *ipc_ns;
561 
562 	spin_lock(&mq_lock);
563 	ipc_ns = __get_ns_from_inode(dir);
564 	if (!ipc_ns) {
565 		error = -EACCES;
566 		goto out_unlock;
567 	}
568 
569 	if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
570 	    !capable(CAP_SYS_RESOURCE)) {
571 		error = -ENOSPC;
572 		goto out_unlock;
573 	}
574 	ipc_ns->mq_queues_count++;
575 	spin_unlock(&mq_lock);
576 
577 	inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
578 	if (IS_ERR(inode)) {
579 		error = PTR_ERR(inode);
580 		spin_lock(&mq_lock);
581 		ipc_ns->mq_queues_count--;
582 		goto out_unlock;
583 	}
584 
585 	put_ipc_ns(ipc_ns);
586 	dir->i_size += DIRENT_SIZE;
587 	dir->i_ctime = dir->i_mtime = dir->i_atime = current_time(dir);
588 
589 	d_instantiate(dentry, inode);
590 	dget(dentry);
591 	return 0;
592 out_unlock:
593 	spin_unlock(&mq_lock);
594 	if (ipc_ns)
595 		put_ipc_ns(ipc_ns);
596 	return error;
597 }
598 
599 static int mqueue_create(struct user_namespace *mnt_userns, struct inode *dir,
600 			 struct dentry *dentry, umode_t mode, bool excl)
601 {
602 	return mqueue_create_attr(dentry, mode, NULL);
603 }
604 
605 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
606 {
607 	struct inode *inode = d_inode(dentry);
608 
609 	dir->i_ctime = dir->i_mtime = dir->i_atime = current_time(dir);
610 	dir->i_size -= DIRENT_SIZE;
611 	drop_nlink(inode);
612 	dput(dentry);
613 	return 0;
614 }
615 
616 /*
617 *	This is routine for system read from queue file.
618 *	To avoid mess with doing here some sort of mq_receive we allow
619 *	to read only queue size & notification info (the only values
620 *	that are interesting from user point of view and aren't accessible
621 *	through std routines)
622 */
623 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
624 				size_t count, loff_t *off)
625 {
626 	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
627 	char buffer[FILENT_SIZE];
628 	ssize_t ret;
629 
630 	spin_lock(&info->lock);
631 	snprintf(buffer, sizeof(buffer),
632 			"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
633 			info->qsize,
634 			info->notify_owner ? info->notify.sigev_notify : 0,
635 			(info->notify_owner &&
636 			 info->notify.sigev_notify == SIGEV_SIGNAL) ?
637 				info->notify.sigev_signo : 0,
638 			pid_vnr(info->notify_owner));
639 	spin_unlock(&info->lock);
640 	buffer[sizeof(buffer)-1] = '\0';
641 
642 	ret = simple_read_from_buffer(u_data, count, off, buffer,
643 				strlen(buffer));
644 	if (ret <= 0)
645 		return ret;
646 
647 	file_inode(filp)->i_atime = file_inode(filp)->i_ctime = current_time(file_inode(filp));
648 	return ret;
649 }
650 
651 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
652 {
653 	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
654 
655 	spin_lock(&info->lock);
656 	if (task_tgid(current) == info->notify_owner)
657 		remove_notification(info);
658 
659 	spin_unlock(&info->lock);
660 	return 0;
661 }
662 
663 static __poll_t mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
664 {
665 	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
666 	__poll_t retval = 0;
667 
668 	poll_wait(filp, &info->wait_q, poll_tab);
669 
670 	spin_lock(&info->lock);
671 	if (info->attr.mq_curmsgs)
672 		retval = EPOLLIN | EPOLLRDNORM;
673 
674 	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
675 		retval |= EPOLLOUT | EPOLLWRNORM;
676 	spin_unlock(&info->lock);
677 
678 	return retval;
679 }
680 
681 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
682 static void wq_add(struct mqueue_inode_info *info, int sr,
683 			struct ext_wait_queue *ewp)
684 {
685 	struct ext_wait_queue *walk;
686 
687 	list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
688 		if (walk->task->prio <= current->prio) {
689 			list_add_tail(&ewp->list, &walk->list);
690 			return;
691 		}
692 	}
693 	list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
694 }
695 
696 /*
697  * Puts current task to sleep. Caller must hold queue lock. After return
698  * lock isn't held.
699  * sr: SEND or RECV
700  */
701 static int wq_sleep(struct mqueue_inode_info *info, int sr,
702 		    ktime_t *timeout, struct ext_wait_queue *ewp)
703 	__releases(&info->lock)
704 {
705 	int retval;
706 	signed long time;
707 
708 	wq_add(info, sr, ewp);
709 
710 	for (;;) {
711 		/* memory barrier not required, we hold info->lock */
712 		__set_current_state(TASK_INTERRUPTIBLE);
713 
714 		spin_unlock(&info->lock);
715 		time = schedule_hrtimeout_range_clock(timeout, 0,
716 			HRTIMER_MODE_ABS, CLOCK_REALTIME);
717 
718 		if (READ_ONCE(ewp->state) == STATE_READY) {
719 			/* see MQ_BARRIER for purpose/pairing */
720 			smp_acquire__after_ctrl_dep();
721 			retval = 0;
722 			goto out;
723 		}
724 		spin_lock(&info->lock);
725 
726 		/* we hold info->lock, so no memory barrier required */
727 		if (READ_ONCE(ewp->state) == STATE_READY) {
728 			retval = 0;
729 			goto out_unlock;
730 		}
731 		if (signal_pending(current)) {
732 			retval = -ERESTARTSYS;
733 			break;
734 		}
735 		if (time == 0) {
736 			retval = -ETIMEDOUT;
737 			break;
738 		}
739 	}
740 	list_del(&ewp->list);
741 out_unlock:
742 	spin_unlock(&info->lock);
743 out:
744 	return retval;
745 }
746 
747 /*
748  * Returns waiting task that should be serviced first or NULL if none exists
749  */
750 static struct ext_wait_queue *wq_get_first_waiter(
751 		struct mqueue_inode_info *info, int sr)
752 {
753 	struct list_head *ptr;
754 
755 	ptr = info->e_wait_q[sr].list.prev;
756 	if (ptr == &info->e_wait_q[sr].list)
757 		return NULL;
758 	return list_entry(ptr, struct ext_wait_queue, list);
759 }
760 
761 
762 static inline void set_cookie(struct sk_buff *skb, char code)
763 {
764 	((char *)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
765 }
766 
767 /*
768  * The next function is only to split too long sys_mq_timedsend
769  */
770 static void __do_notify(struct mqueue_inode_info *info)
771 {
772 	/* notification
773 	 * invoked when there is registered process and there isn't process
774 	 * waiting synchronously for message AND state of queue changed from
775 	 * empty to not empty. Here we are sure that no one is waiting
776 	 * synchronously. */
777 	if (info->notify_owner &&
778 	    info->attr.mq_curmsgs == 1) {
779 		switch (info->notify.sigev_notify) {
780 		case SIGEV_NONE:
781 			break;
782 		case SIGEV_SIGNAL: {
783 			struct kernel_siginfo sig_i;
784 			struct task_struct *task;
785 
786 			/* do_mq_notify() accepts sigev_signo == 0, why?? */
787 			if (!info->notify.sigev_signo)
788 				break;
789 
790 			clear_siginfo(&sig_i);
791 			sig_i.si_signo = info->notify.sigev_signo;
792 			sig_i.si_errno = 0;
793 			sig_i.si_code = SI_MESGQ;
794 			sig_i.si_value = info->notify.sigev_value;
795 			rcu_read_lock();
796 			/* map current pid/uid into info->owner's namespaces */
797 			sig_i.si_pid = task_tgid_nr_ns(current,
798 						ns_of_pid(info->notify_owner));
799 			sig_i.si_uid = from_kuid_munged(info->notify_user_ns,
800 						current_uid());
801 			/*
802 			 * We can't use kill_pid_info(), this signal should
803 			 * bypass check_kill_permission(). It is from kernel
804 			 * but si_fromuser() can't know this.
805 			 * We do check the self_exec_id, to avoid sending
806 			 * signals to programs that don't expect them.
807 			 */
808 			task = pid_task(info->notify_owner, PIDTYPE_TGID);
809 			if (task && task->self_exec_id ==
810 						info->notify_self_exec_id) {
811 				do_send_sig_info(info->notify.sigev_signo,
812 						&sig_i, task, PIDTYPE_TGID);
813 			}
814 			rcu_read_unlock();
815 			break;
816 		}
817 		case SIGEV_THREAD:
818 			set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
819 			netlink_sendskb(info->notify_sock, info->notify_cookie);
820 			break;
821 		}
822 		/* after notification unregisters process */
823 		put_pid(info->notify_owner);
824 		put_user_ns(info->notify_user_ns);
825 		info->notify_owner = NULL;
826 		info->notify_user_ns = NULL;
827 	}
828 	wake_up(&info->wait_q);
829 }
830 
831 static int prepare_timeout(const struct __kernel_timespec __user *u_abs_timeout,
832 			   struct timespec64 *ts)
833 {
834 	if (get_timespec64(ts, u_abs_timeout))
835 		return -EFAULT;
836 	if (!timespec64_valid(ts))
837 		return -EINVAL;
838 	return 0;
839 }
840 
841 static void remove_notification(struct mqueue_inode_info *info)
842 {
843 	if (info->notify_owner != NULL &&
844 	    info->notify.sigev_notify == SIGEV_THREAD) {
845 		set_cookie(info->notify_cookie, NOTIFY_REMOVED);
846 		netlink_sendskb(info->notify_sock, info->notify_cookie);
847 	}
848 	put_pid(info->notify_owner);
849 	put_user_ns(info->notify_user_ns);
850 	info->notify_owner = NULL;
851 	info->notify_user_ns = NULL;
852 }
853 
854 static int prepare_open(struct dentry *dentry, int oflag, int ro,
855 			umode_t mode, struct filename *name,
856 			struct mq_attr *attr)
857 {
858 	static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
859 						  MAY_READ | MAY_WRITE };
860 	int acc;
861 
862 	if (d_really_is_negative(dentry)) {
863 		if (!(oflag & O_CREAT))
864 			return -ENOENT;
865 		if (ro)
866 			return ro;
867 		audit_inode_parent_hidden(name, dentry->d_parent);
868 		return vfs_mkobj(dentry, mode & ~current_umask(),
869 				  mqueue_create_attr, attr);
870 	}
871 	/* it already existed */
872 	audit_inode(name, dentry, 0);
873 	if ((oflag & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
874 		return -EEXIST;
875 	if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
876 		return -EINVAL;
877 	acc = oflag2acc[oflag & O_ACCMODE];
878 	return inode_permission(&init_user_ns, d_inode(dentry), acc);
879 }
880 
881 static int do_mq_open(const char __user *u_name, int oflag, umode_t mode,
882 		      struct mq_attr *attr)
883 {
884 	struct vfsmount *mnt = current->nsproxy->ipc_ns->mq_mnt;
885 	struct dentry *root = mnt->mnt_root;
886 	struct filename *name;
887 	struct path path;
888 	int fd, error;
889 	int ro;
890 
891 	audit_mq_open(oflag, mode, attr);
892 
893 	if (IS_ERR(name = getname(u_name)))
894 		return PTR_ERR(name);
895 
896 	fd = get_unused_fd_flags(O_CLOEXEC);
897 	if (fd < 0)
898 		goto out_putname;
899 
900 	ro = mnt_want_write(mnt);	/* we'll drop it in any case */
901 	inode_lock(d_inode(root));
902 	path.dentry = lookup_one_len(name->name, root, strlen(name->name));
903 	if (IS_ERR(path.dentry)) {
904 		error = PTR_ERR(path.dentry);
905 		goto out_putfd;
906 	}
907 	path.mnt = mntget(mnt);
908 	error = prepare_open(path.dentry, oflag, ro, mode, name, attr);
909 	if (!error) {
910 		struct file *file = dentry_open(&path, oflag, current_cred());
911 		if (!IS_ERR(file))
912 			fd_install(fd, file);
913 		else
914 			error = PTR_ERR(file);
915 	}
916 	path_put(&path);
917 out_putfd:
918 	if (error) {
919 		put_unused_fd(fd);
920 		fd = error;
921 	}
922 	inode_unlock(d_inode(root));
923 	if (!ro)
924 		mnt_drop_write(mnt);
925 out_putname:
926 	putname(name);
927 	return fd;
928 }
929 
930 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
931 		struct mq_attr __user *, u_attr)
932 {
933 	struct mq_attr attr;
934 	if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
935 		return -EFAULT;
936 
937 	return do_mq_open(u_name, oflag, mode, u_attr ? &attr : NULL);
938 }
939 
940 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
941 {
942 	int err;
943 	struct filename *name;
944 	struct dentry *dentry;
945 	struct inode *inode = NULL;
946 	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
947 	struct vfsmount *mnt = ipc_ns->mq_mnt;
948 
949 	name = getname(u_name);
950 	if (IS_ERR(name))
951 		return PTR_ERR(name);
952 
953 	audit_inode_parent_hidden(name, mnt->mnt_root);
954 	err = mnt_want_write(mnt);
955 	if (err)
956 		goto out_name;
957 	inode_lock_nested(d_inode(mnt->mnt_root), I_MUTEX_PARENT);
958 	dentry = lookup_one_len(name->name, mnt->mnt_root,
959 				strlen(name->name));
960 	if (IS_ERR(dentry)) {
961 		err = PTR_ERR(dentry);
962 		goto out_unlock;
963 	}
964 
965 	inode = d_inode(dentry);
966 	if (!inode) {
967 		err = -ENOENT;
968 	} else {
969 		ihold(inode);
970 		err = vfs_unlink(&init_user_ns, d_inode(dentry->d_parent),
971 				 dentry, NULL);
972 	}
973 	dput(dentry);
974 
975 out_unlock:
976 	inode_unlock(d_inode(mnt->mnt_root));
977 	if (inode)
978 		iput(inode);
979 	mnt_drop_write(mnt);
980 out_name:
981 	putname(name);
982 
983 	return err;
984 }
985 
986 /* Pipelined send and receive functions.
987  *
988  * If a receiver finds no waiting message, then it registers itself in the
989  * list of waiting receivers. A sender checks that list before adding the new
990  * message into the message array. If there is a waiting receiver, then it
991  * bypasses the message array and directly hands the message over to the
992  * receiver. The receiver accepts the message and returns without grabbing the
993  * queue spinlock:
994  *
995  * - Set pointer to message.
996  * - Queue the receiver task for later wakeup (without the info->lock).
997  * - Update its state to STATE_READY. Now the receiver can continue.
998  * - Wake up the process after the lock is dropped. Should the process wake up
999  *   before this wakeup (due to a timeout or a signal) it will either see
1000  *   STATE_READY and continue or acquire the lock to check the state again.
1001  *
1002  * The same algorithm is used for senders.
1003  */
1004 
1005 static inline void __pipelined_op(struct wake_q_head *wake_q,
1006 				  struct mqueue_inode_info *info,
1007 				  struct ext_wait_queue *this)
1008 {
1009 	struct task_struct *task;
1010 
1011 	list_del(&this->list);
1012 	task = get_task_struct(this->task);
1013 
1014 	/* see MQ_BARRIER for purpose/pairing */
1015 	smp_store_release(&this->state, STATE_READY);
1016 	wake_q_add_safe(wake_q, task);
1017 }
1018 
1019 /* pipelined_send() - send a message directly to the task waiting in
1020  * sys_mq_timedreceive() (without inserting message into a queue).
1021  */
1022 static inline void pipelined_send(struct wake_q_head *wake_q,
1023 				  struct mqueue_inode_info *info,
1024 				  struct msg_msg *message,
1025 				  struct ext_wait_queue *receiver)
1026 {
1027 	receiver->msg = message;
1028 	__pipelined_op(wake_q, info, receiver);
1029 }
1030 
1031 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
1032  * gets its message and put to the queue (we have one free place for sure). */
1033 static inline void pipelined_receive(struct wake_q_head *wake_q,
1034 				     struct mqueue_inode_info *info)
1035 {
1036 	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
1037 
1038 	if (!sender) {
1039 		/* for poll */
1040 		wake_up_interruptible(&info->wait_q);
1041 		return;
1042 	}
1043 	if (msg_insert(sender->msg, info))
1044 		return;
1045 
1046 	__pipelined_op(wake_q, info, sender);
1047 }
1048 
1049 static int do_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
1050 		size_t msg_len, unsigned int msg_prio,
1051 		struct timespec64 *ts)
1052 {
1053 	struct fd f;
1054 	struct inode *inode;
1055 	struct ext_wait_queue wait;
1056 	struct ext_wait_queue *receiver;
1057 	struct msg_msg *msg_ptr;
1058 	struct mqueue_inode_info *info;
1059 	ktime_t expires, *timeout = NULL;
1060 	struct posix_msg_tree_node *new_leaf = NULL;
1061 	int ret = 0;
1062 	DEFINE_WAKE_Q(wake_q);
1063 
1064 	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
1065 		return -EINVAL;
1066 
1067 	if (ts) {
1068 		expires = timespec64_to_ktime(*ts);
1069 		timeout = &expires;
1070 	}
1071 
1072 	audit_mq_sendrecv(mqdes, msg_len, msg_prio, ts);
1073 
1074 	f = fdget(mqdes);
1075 	if (unlikely(!f.file)) {
1076 		ret = -EBADF;
1077 		goto out;
1078 	}
1079 
1080 	inode = file_inode(f.file);
1081 	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1082 		ret = -EBADF;
1083 		goto out_fput;
1084 	}
1085 	info = MQUEUE_I(inode);
1086 	audit_file(f.file);
1087 
1088 	if (unlikely(!(f.file->f_mode & FMODE_WRITE))) {
1089 		ret = -EBADF;
1090 		goto out_fput;
1091 	}
1092 
1093 	if (unlikely(msg_len > info->attr.mq_msgsize)) {
1094 		ret = -EMSGSIZE;
1095 		goto out_fput;
1096 	}
1097 
1098 	/* First try to allocate memory, before doing anything with
1099 	 * existing queues. */
1100 	msg_ptr = load_msg(u_msg_ptr, msg_len);
1101 	if (IS_ERR(msg_ptr)) {
1102 		ret = PTR_ERR(msg_ptr);
1103 		goto out_fput;
1104 	}
1105 	msg_ptr->m_ts = msg_len;
1106 	msg_ptr->m_type = msg_prio;
1107 
1108 	/*
1109 	 * msg_insert really wants us to have a valid, spare node struct so
1110 	 * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1111 	 * fall back to that if necessary.
1112 	 */
1113 	if (!info->node_cache)
1114 		new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1115 
1116 	spin_lock(&info->lock);
1117 
1118 	if (!info->node_cache && new_leaf) {
1119 		/* Save our speculative allocation into the cache */
1120 		INIT_LIST_HEAD(&new_leaf->msg_list);
1121 		info->node_cache = new_leaf;
1122 		new_leaf = NULL;
1123 	} else {
1124 		kfree(new_leaf);
1125 	}
1126 
1127 	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
1128 		if (f.file->f_flags & O_NONBLOCK) {
1129 			ret = -EAGAIN;
1130 		} else {
1131 			wait.task = current;
1132 			wait.msg = (void *) msg_ptr;
1133 
1134 			/* memory barrier not required, we hold info->lock */
1135 			WRITE_ONCE(wait.state, STATE_NONE);
1136 			ret = wq_sleep(info, SEND, timeout, &wait);
1137 			/*
1138 			 * wq_sleep must be called with info->lock held, and
1139 			 * returns with the lock released
1140 			 */
1141 			goto out_free;
1142 		}
1143 	} else {
1144 		receiver = wq_get_first_waiter(info, RECV);
1145 		if (receiver) {
1146 			pipelined_send(&wake_q, info, msg_ptr, receiver);
1147 		} else {
1148 			/* adds message to the queue */
1149 			ret = msg_insert(msg_ptr, info);
1150 			if (ret)
1151 				goto out_unlock;
1152 			__do_notify(info);
1153 		}
1154 		inode->i_atime = inode->i_mtime = inode->i_ctime =
1155 				current_time(inode);
1156 	}
1157 out_unlock:
1158 	spin_unlock(&info->lock);
1159 	wake_up_q(&wake_q);
1160 out_free:
1161 	if (ret)
1162 		free_msg(msg_ptr);
1163 out_fput:
1164 	fdput(f);
1165 out:
1166 	return ret;
1167 }
1168 
1169 static int do_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
1170 		size_t msg_len, unsigned int __user *u_msg_prio,
1171 		struct timespec64 *ts)
1172 {
1173 	ssize_t ret;
1174 	struct msg_msg *msg_ptr;
1175 	struct fd f;
1176 	struct inode *inode;
1177 	struct mqueue_inode_info *info;
1178 	struct ext_wait_queue wait;
1179 	ktime_t expires, *timeout = NULL;
1180 	struct posix_msg_tree_node *new_leaf = NULL;
1181 
1182 	if (ts) {
1183 		expires = timespec64_to_ktime(*ts);
1184 		timeout = &expires;
1185 	}
1186 
1187 	audit_mq_sendrecv(mqdes, msg_len, 0, ts);
1188 
1189 	f = fdget(mqdes);
1190 	if (unlikely(!f.file)) {
1191 		ret = -EBADF;
1192 		goto out;
1193 	}
1194 
1195 	inode = file_inode(f.file);
1196 	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1197 		ret = -EBADF;
1198 		goto out_fput;
1199 	}
1200 	info = MQUEUE_I(inode);
1201 	audit_file(f.file);
1202 
1203 	if (unlikely(!(f.file->f_mode & FMODE_READ))) {
1204 		ret = -EBADF;
1205 		goto out_fput;
1206 	}
1207 
1208 	/* checks if buffer is big enough */
1209 	if (unlikely(msg_len < info->attr.mq_msgsize)) {
1210 		ret = -EMSGSIZE;
1211 		goto out_fput;
1212 	}
1213 
1214 	/*
1215 	 * msg_insert really wants us to have a valid, spare node struct so
1216 	 * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1217 	 * fall back to that if necessary.
1218 	 */
1219 	if (!info->node_cache)
1220 		new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1221 
1222 	spin_lock(&info->lock);
1223 
1224 	if (!info->node_cache && new_leaf) {
1225 		/* Save our speculative allocation into the cache */
1226 		INIT_LIST_HEAD(&new_leaf->msg_list);
1227 		info->node_cache = new_leaf;
1228 	} else {
1229 		kfree(new_leaf);
1230 	}
1231 
1232 	if (info->attr.mq_curmsgs == 0) {
1233 		if (f.file->f_flags & O_NONBLOCK) {
1234 			spin_unlock(&info->lock);
1235 			ret = -EAGAIN;
1236 		} else {
1237 			wait.task = current;
1238 
1239 			/* memory barrier not required, we hold info->lock */
1240 			WRITE_ONCE(wait.state, STATE_NONE);
1241 			ret = wq_sleep(info, RECV, timeout, &wait);
1242 			msg_ptr = wait.msg;
1243 		}
1244 	} else {
1245 		DEFINE_WAKE_Q(wake_q);
1246 
1247 		msg_ptr = msg_get(info);
1248 
1249 		inode->i_atime = inode->i_mtime = inode->i_ctime =
1250 				current_time(inode);
1251 
1252 		/* There is now free space in queue. */
1253 		pipelined_receive(&wake_q, info);
1254 		spin_unlock(&info->lock);
1255 		wake_up_q(&wake_q);
1256 		ret = 0;
1257 	}
1258 	if (ret == 0) {
1259 		ret = msg_ptr->m_ts;
1260 
1261 		if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1262 			store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1263 			ret = -EFAULT;
1264 		}
1265 		free_msg(msg_ptr);
1266 	}
1267 out_fput:
1268 	fdput(f);
1269 out:
1270 	return ret;
1271 }
1272 
1273 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
1274 		size_t, msg_len, unsigned int, msg_prio,
1275 		const struct __kernel_timespec __user *, u_abs_timeout)
1276 {
1277 	struct timespec64 ts, *p = NULL;
1278 	if (u_abs_timeout) {
1279 		int res = prepare_timeout(u_abs_timeout, &ts);
1280 		if (res)
1281 			return res;
1282 		p = &ts;
1283 	}
1284 	return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p);
1285 }
1286 
1287 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
1288 		size_t, msg_len, unsigned int __user *, u_msg_prio,
1289 		const struct __kernel_timespec __user *, u_abs_timeout)
1290 {
1291 	struct timespec64 ts, *p = NULL;
1292 	if (u_abs_timeout) {
1293 		int res = prepare_timeout(u_abs_timeout, &ts);
1294 		if (res)
1295 			return res;
1296 		p = &ts;
1297 	}
1298 	return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p);
1299 }
1300 
1301 /*
1302  * Notes: the case when user wants us to deregister (with NULL as pointer)
1303  * and he isn't currently owner of notification, will be silently discarded.
1304  * It isn't explicitly defined in the POSIX.
1305  */
1306 static int do_mq_notify(mqd_t mqdes, const struct sigevent *notification)
1307 {
1308 	int ret;
1309 	struct fd f;
1310 	struct sock *sock;
1311 	struct inode *inode;
1312 	struct mqueue_inode_info *info;
1313 	struct sk_buff *nc;
1314 
1315 	audit_mq_notify(mqdes, notification);
1316 
1317 	nc = NULL;
1318 	sock = NULL;
1319 	if (notification != NULL) {
1320 		if (unlikely(notification->sigev_notify != SIGEV_NONE &&
1321 			     notification->sigev_notify != SIGEV_SIGNAL &&
1322 			     notification->sigev_notify != SIGEV_THREAD))
1323 			return -EINVAL;
1324 		if (notification->sigev_notify == SIGEV_SIGNAL &&
1325 			!valid_signal(notification->sigev_signo)) {
1326 			return -EINVAL;
1327 		}
1328 		if (notification->sigev_notify == SIGEV_THREAD) {
1329 			long timeo;
1330 
1331 			/* create the notify skb */
1332 			nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1333 			if (!nc)
1334 				return -ENOMEM;
1335 
1336 			if (copy_from_user(nc->data,
1337 					notification->sigev_value.sival_ptr,
1338 					NOTIFY_COOKIE_LEN)) {
1339 				ret = -EFAULT;
1340 				goto free_skb;
1341 			}
1342 
1343 			/* TODO: add a header? */
1344 			skb_put(nc, NOTIFY_COOKIE_LEN);
1345 			/* and attach it to the socket */
1346 retry:
1347 			f = fdget(notification->sigev_signo);
1348 			if (!f.file) {
1349 				ret = -EBADF;
1350 				goto out;
1351 			}
1352 			sock = netlink_getsockbyfilp(f.file);
1353 			fdput(f);
1354 			if (IS_ERR(sock)) {
1355 				ret = PTR_ERR(sock);
1356 				goto free_skb;
1357 			}
1358 
1359 			timeo = MAX_SCHEDULE_TIMEOUT;
1360 			ret = netlink_attachskb(sock, nc, &timeo, NULL);
1361 			if (ret == 1) {
1362 				sock = NULL;
1363 				goto retry;
1364 			}
1365 			if (ret)
1366 				return ret;
1367 		}
1368 	}
1369 
1370 	f = fdget(mqdes);
1371 	if (!f.file) {
1372 		ret = -EBADF;
1373 		goto out;
1374 	}
1375 
1376 	inode = file_inode(f.file);
1377 	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1378 		ret = -EBADF;
1379 		goto out_fput;
1380 	}
1381 	info = MQUEUE_I(inode);
1382 
1383 	ret = 0;
1384 	spin_lock(&info->lock);
1385 	if (notification == NULL) {
1386 		if (info->notify_owner == task_tgid(current)) {
1387 			remove_notification(info);
1388 			inode->i_atime = inode->i_ctime = current_time(inode);
1389 		}
1390 	} else if (info->notify_owner != NULL) {
1391 		ret = -EBUSY;
1392 	} else {
1393 		switch (notification->sigev_notify) {
1394 		case SIGEV_NONE:
1395 			info->notify.sigev_notify = SIGEV_NONE;
1396 			break;
1397 		case SIGEV_THREAD:
1398 			info->notify_sock = sock;
1399 			info->notify_cookie = nc;
1400 			sock = NULL;
1401 			nc = NULL;
1402 			info->notify.sigev_notify = SIGEV_THREAD;
1403 			break;
1404 		case SIGEV_SIGNAL:
1405 			info->notify.sigev_signo = notification->sigev_signo;
1406 			info->notify.sigev_value = notification->sigev_value;
1407 			info->notify.sigev_notify = SIGEV_SIGNAL;
1408 			info->notify_self_exec_id = current->self_exec_id;
1409 			break;
1410 		}
1411 
1412 		info->notify_owner = get_pid(task_tgid(current));
1413 		info->notify_user_ns = get_user_ns(current_user_ns());
1414 		inode->i_atime = inode->i_ctime = current_time(inode);
1415 	}
1416 	spin_unlock(&info->lock);
1417 out_fput:
1418 	fdput(f);
1419 out:
1420 	if (sock)
1421 		netlink_detachskb(sock, nc);
1422 	else
1423 free_skb:
1424 		dev_kfree_skb(nc);
1425 
1426 	return ret;
1427 }
1428 
1429 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1430 		const struct sigevent __user *, u_notification)
1431 {
1432 	struct sigevent n, *p = NULL;
1433 	if (u_notification) {
1434 		if (copy_from_user(&n, u_notification, sizeof(struct sigevent)))
1435 			return -EFAULT;
1436 		p = &n;
1437 	}
1438 	return do_mq_notify(mqdes, p);
1439 }
1440 
1441 static int do_mq_getsetattr(int mqdes, struct mq_attr *new, struct mq_attr *old)
1442 {
1443 	struct fd f;
1444 	struct inode *inode;
1445 	struct mqueue_inode_info *info;
1446 
1447 	if (new && (new->mq_flags & (~O_NONBLOCK)))
1448 		return -EINVAL;
1449 
1450 	f = fdget(mqdes);
1451 	if (!f.file)
1452 		return -EBADF;
1453 
1454 	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1455 		fdput(f);
1456 		return -EBADF;
1457 	}
1458 
1459 	inode = file_inode(f.file);
1460 	info = MQUEUE_I(inode);
1461 
1462 	spin_lock(&info->lock);
1463 
1464 	if (old) {
1465 		*old = info->attr;
1466 		old->mq_flags = f.file->f_flags & O_NONBLOCK;
1467 	}
1468 	if (new) {
1469 		audit_mq_getsetattr(mqdes, new);
1470 		spin_lock(&f.file->f_lock);
1471 		if (new->mq_flags & O_NONBLOCK)
1472 			f.file->f_flags |= O_NONBLOCK;
1473 		else
1474 			f.file->f_flags &= ~O_NONBLOCK;
1475 		spin_unlock(&f.file->f_lock);
1476 
1477 		inode->i_atime = inode->i_ctime = current_time(inode);
1478 	}
1479 
1480 	spin_unlock(&info->lock);
1481 	fdput(f);
1482 	return 0;
1483 }
1484 
1485 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1486 		const struct mq_attr __user *, u_mqstat,
1487 		struct mq_attr __user *, u_omqstat)
1488 {
1489 	int ret;
1490 	struct mq_attr mqstat, omqstat;
1491 	struct mq_attr *new = NULL, *old = NULL;
1492 
1493 	if (u_mqstat) {
1494 		new = &mqstat;
1495 		if (copy_from_user(new, u_mqstat, sizeof(struct mq_attr)))
1496 			return -EFAULT;
1497 	}
1498 	if (u_omqstat)
1499 		old = &omqstat;
1500 
1501 	ret = do_mq_getsetattr(mqdes, new, old);
1502 	if (ret || !old)
1503 		return ret;
1504 
1505 	if (copy_to_user(u_omqstat, old, sizeof(struct mq_attr)))
1506 		return -EFAULT;
1507 	return 0;
1508 }
1509 
1510 #ifdef CONFIG_COMPAT
1511 
1512 struct compat_mq_attr {
1513 	compat_long_t mq_flags;      /* message queue flags		     */
1514 	compat_long_t mq_maxmsg;     /* maximum number of messages	     */
1515 	compat_long_t mq_msgsize;    /* maximum message size		     */
1516 	compat_long_t mq_curmsgs;    /* number of messages currently queued  */
1517 	compat_long_t __reserved[4]; /* ignored for input, zeroed for output */
1518 };
1519 
1520 static inline int get_compat_mq_attr(struct mq_attr *attr,
1521 			const struct compat_mq_attr __user *uattr)
1522 {
1523 	struct compat_mq_attr v;
1524 
1525 	if (copy_from_user(&v, uattr, sizeof(*uattr)))
1526 		return -EFAULT;
1527 
1528 	memset(attr, 0, sizeof(*attr));
1529 	attr->mq_flags = v.mq_flags;
1530 	attr->mq_maxmsg = v.mq_maxmsg;
1531 	attr->mq_msgsize = v.mq_msgsize;
1532 	attr->mq_curmsgs = v.mq_curmsgs;
1533 	return 0;
1534 }
1535 
1536 static inline int put_compat_mq_attr(const struct mq_attr *attr,
1537 			struct compat_mq_attr __user *uattr)
1538 {
1539 	struct compat_mq_attr v;
1540 
1541 	memset(&v, 0, sizeof(v));
1542 	v.mq_flags = attr->mq_flags;
1543 	v.mq_maxmsg = attr->mq_maxmsg;
1544 	v.mq_msgsize = attr->mq_msgsize;
1545 	v.mq_curmsgs = attr->mq_curmsgs;
1546 	if (copy_to_user(uattr, &v, sizeof(*uattr)))
1547 		return -EFAULT;
1548 	return 0;
1549 }
1550 
1551 COMPAT_SYSCALL_DEFINE4(mq_open, const char __user *, u_name,
1552 		       int, oflag, compat_mode_t, mode,
1553 		       struct compat_mq_attr __user *, u_attr)
1554 {
1555 	struct mq_attr attr, *p = NULL;
1556 	if (u_attr && oflag & O_CREAT) {
1557 		p = &attr;
1558 		if (get_compat_mq_attr(&attr, u_attr))
1559 			return -EFAULT;
1560 	}
1561 	return do_mq_open(u_name, oflag, mode, p);
1562 }
1563 
1564 COMPAT_SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1565 		       const struct compat_sigevent __user *, u_notification)
1566 {
1567 	struct sigevent n, *p = NULL;
1568 	if (u_notification) {
1569 		if (get_compat_sigevent(&n, u_notification))
1570 			return -EFAULT;
1571 		if (n.sigev_notify == SIGEV_THREAD)
1572 			n.sigev_value.sival_ptr = compat_ptr(n.sigev_value.sival_int);
1573 		p = &n;
1574 	}
1575 	return do_mq_notify(mqdes, p);
1576 }
1577 
1578 COMPAT_SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1579 		       const struct compat_mq_attr __user *, u_mqstat,
1580 		       struct compat_mq_attr __user *, u_omqstat)
1581 {
1582 	int ret;
1583 	struct mq_attr mqstat, omqstat;
1584 	struct mq_attr *new = NULL, *old = NULL;
1585 
1586 	if (u_mqstat) {
1587 		new = &mqstat;
1588 		if (get_compat_mq_attr(new, u_mqstat))
1589 			return -EFAULT;
1590 	}
1591 	if (u_omqstat)
1592 		old = &omqstat;
1593 
1594 	ret = do_mq_getsetattr(mqdes, new, old);
1595 	if (ret || !old)
1596 		return ret;
1597 
1598 	if (put_compat_mq_attr(old, u_omqstat))
1599 		return -EFAULT;
1600 	return 0;
1601 }
1602 #endif
1603 
1604 #ifdef CONFIG_COMPAT_32BIT_TIME
1605 static int compat_prepare_timeout(const struct old_timespec32 __user *p,
1606 				   struct timespec64 *ts)
1607 {
1608 	if (get_old_timespec32(ts, p))
1609 		return -EFAULT;
1610 	if (!timespec64_valid(ts))
1611 		return -EINVAL;
1612 	return 0;
1613 }
1614 
1615 SYSCALL_DEFINE5(mq_timedsend_time32, mqd_t, mqdes,
1616 		const char __user *, u_msg_ptr,
1617 		unsigned int, msg_len, unsigned int, msg_prio,
1618 		const struct old_timespec32 __user *, u_abs_timeout)
1619 {
1620 	struct timespec64 ts, *p = NULL;
1621 	if (u_abs_timeout) {
1622 		int res = compat_prepare_timeout(u_abs_timeout, &ts);
1623 		if (res)
1624 			return res;
1625 		p = &ts;
1626 	}
1627 	return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p);
1628 }
1629 
1630 SYSCALL_DEFINE5(mq_timedreceive_time32, mqd_t, mqdes,
1631 		char __user *, u_msg_ptr,
1632 		unsigned int, msg_len, unsigned int __user *, u_msg_prio,
1633 		const struct old_timespec32 __user *, u_abs_timeout)
1634 {
1635 	struct timespec64 ts, *p = NULL;
1636 	if (u_abs_timeout) {
1637 		int res = compat_prepare_timeout(u_abs_timeout, &ts);
1638 		if (res)
1639 			return res;
1640 		p = &ts;
1641 	}
1642 	return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p);
1643 }
1644 #endif
1645 
1646 static const struct inode_operations mqueue_dir_inode_operations = {
1647 	.lookup = simple_lookup,
1648 	.create = mqueue_create,
1649 	.unlink = mqueue_unlink,
1650 };
1651 
1652 static const struct file_operations mqueue_file_operations = {
1653 	.flush = mqueue_flush_file,
1654 	.poll = mqueue_poll_file,
1655 	.read = mqueue_read_file,
1656 	.llseek = default_llseek,
1657 };
1658 
1659 static const struct super_operations mqueue_super_ops = {
1660 	.alloc_inode = mqueue_alloc_inode,
1661 	.free_inode = mqueue_free_inode,
1662 	.evict_inode = mqueue_evict_inode,
1663 	.statfs = simple_statfs,
1664 };
1665 
1666 static const struct fs_context_operations mqueue_fs_context_ops = {
1667 	.free		= mqueue_fs_context_free,
1668 	.get_tree	= mqueue_get_tree,
1669 };
1670 
1671 static struct file_system_type mqueue_fs_type = {
1672 	.name			= "mqueue",
1673 	.init_fs_context	= mqueue_init_fs_context,
1674 	.kill_sb		= kill_litter_super,
1675 	.fs_flags		= FS_USERNS_MOUNT,
1676 };
1677 
1678 int mq_init_ns(struct ipc_namespace *ns)
1679 {
1680 	struct vfsmount *m;
1681 
1682 	ns->mq_queues_count  = 0;
1683 	ns->mq_queues_max    = DFLT_QUEUESMAX;
1684 	ns->mq_msg_max       = DFLT_MSGMAX;
1685 	ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1686 	ns->mq_msg_default   = DFLT_MSG;
1687 	ns->mq_msgsize_default  = DFLT_MSGSIZE;
1688 
1689 	m = mq_create_mount(ns);
1690 	if (IS_ERR(m))
1691 		return PTR_ERR(m);
1692 	ns->mq_mnt = m;
1693 	return 0;
1694 }
1695 
1696 void mq_clear_sbinfo(struct ipc_namespace *ns)
1697 {
1698 	ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1699 }
1700 
1701 void mq_put_mnt(struct ipc_namespace *ns)
1702 {
1703 	kern_unmount(ns->mq_mnt);
1704 }
1705 
1706 static int __init init_mqueue_fs(void)
1707 {
1708 	int error;
1709 
1710 	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1711 				sizeof(struct mqueue_inode_info), 0,
1712 				SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT, init_once);
1713 	if (mqueue_inode_cachep == NULL)
1714 		return -ENOMEM;
1715 
1716 	/* ignore failures - they are not fatal */
1717 	mq_sysctl_table = mq_register_sysctl_table();
1718 
1719 	error = register_filesystem(&mqueue_fs_type);
1720 	if (error)
1721 		goto out_sysctl;
1722 
1723 	spin_lock_init(&mq_lock);
1724 
1725 	error = mq_init_ns(&init_ipc_ns);
1726 	if (error)
1727 		goto out_filesystem;
1728 
1729 	return 0;
1730 
1731 out_filesystem:
1732 	unregister_filesystem(&mqueue_fs_type);
1733 out_sysctl:
1734 	if (mq_sysctl_table)
1735 		unregister_sysctl_table(mq_sysctl_table);
1736 	kmem_cache_destroy(mqueue_inode_cachep);
1737 	return error;
1738 }
1739 
1740 device_initcall(init_mqueue_fs);
1741