mqueue.c revision 43afe4d3
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
46struct 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
60struct 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
126struct 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
133struct 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	struct user_namespace *notify_user_ns;
146	struct user_struct *user;	/* user who created, for accounting */
147	struct sock *notify_sock;
148	struct sk_buff *notify_cookie;
149
150	/* for tasks waiting for free space and messages, respectively */
151	struct ext_wait_queue e_wait_q[2];
152
153	unsigned long qsize; /* size of queue in memory (sum of all msgs) */
154};
155
156static struct file_system_type mqueue_fs_type;
157static const struct inode_operations mqueue_dir_inode_operations;
158static const struct file_operations mqueue_file_operations;
159static const struct super_operations mqueue_super_ops;
160static const struct fs_context_operations mqueue_fs_context_ops;
161static void remove_notification(struct mqueue_inode_info *info);
162
163static struct kmem_cache *mqueue_inode_cachep;
164
165static struct ctl_table_header *mq_sysctl_table;
166
167static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
168{
169	return container_of(inode, struct mqueue_inode_info, vfs_inode);
170}
171
172/*
173 * This routine should be called with the mq_lock held.
174 */
175static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
176{
177	return get_ipc_ns(inode->i_sb->s_fs_info);
178}
179
180static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
181{
182	struct ipc_namespace *ns;
183
184	spin_lock(&mq_lock);
185	ns = __get_ns_from_inode(inode);
186	spin_unlock(&mq_lock);
187	return ns;
188}
189
190/* Auxiliary functions to manipulate messages' list */
191static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
192{
193	struct rb_node **p, *parent = NULL;
194	struct posix_msg_tree_node *leaf;
195	bool rightmost = true;
196
197	p = &info->msg_tree.rb_node;
198	while (*p) {
199		parent = *p;
200		leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
201
202		if (likely(leaf->priority == msg->m_type))
203			goto insert_msg;
204		else if (msg->m_type < leaf->priority) {
205			p = &(*p)->rb_left;
206			rightmost = false;
207		} else
208			p = &(*p)->rb_right;
209	}
210	if (info->node_cache) {
211		leaf = info->node_cache;
212		info->node_cache = NULL;
213	} else {
214		leaf = kmalloc(sizeof(*leaf), GFP_ATOMIC);
215		if (!leaf)
216			return -ENOMEM;
217		INIT_LIST_HEAD(&leaf->msg_list);
218	}
219	leaf->priority = msg->m_type;
220
221	if (rightmost)
222		info->msg_tree_rightmost = &leaf->rb_node;
223
224	rb_link_node(&leaf->rb_node, parent, p);
225	rb_insert_color(&leaf->rb_node, &info->msg_tree);
226insert_msg:
227	info->attr.mq_curmsgs++;
228	info->qsize += msg->m_ts;
229	list_add_tail(&msg->m_list, &leaf->msg_list);
230	return 0;
231}
232
233static inline void msg_tree_erase(struct posix_msg_tree_node *leaf,
234				  struct mqueue_inode_info *info)
235{
236	struct rb_node *node = &leaf->rb_node;
237
238	if (info->msg_tree_rightmost == node)
239		info->msg_tree_rightmost = rb_prev(node);
240
241	rb_erase(node, &info->msg_tree);
242	if (info->node_cache)
243		kfree(leaf);
244	else
245		info->node_cache = leaf;
246}
247
248static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
249{
250	struct rb_node *parent = NULL;
251	struct posix_msg_tree_node *leaf;
252	struct msg_msg *msg;
253
254try_again:
255	/*
256	 * During insert, low priorities go to the left and high to the
257	 * right.  On receive, we want the highest priorities first, so
258	 * walk all the way to the right.
259	 */
260	parent = info->msg_tree_rightmost;
261	if (!parent) {
262		if (info->attr.mq_curmsgs) {
263			pr_warn_once("Inconsistency in POSIX message queue, "
264				     "no tree element, but supposedly messages "
265				     "should exist!\n");
266			info->attr.mq_curmsgs = 0;
267		}
268		return NULL;
269	}
270	leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
271	if (unlikely(list_empty(&leaf->msg_list))) {
272		pr_warn_once("Inconsistency in POSIX message queue, "
273			     "empty leaf node but we haven't implemented "
274			     "lazy leaf delete!\n");
275		msg_tree_erase(leaf, info);
276		goto try_again;
277	} else {
278		msg = list_first_entry(&leaf->msg_list,
279				       struct msg_msg, m_list);
280		list_del(&msg->m_list);
281		if (list_empty(&leaf->msg_list)) {
282			msg_tree_erase(leaf, info);
283		}
284	}
285	info->attr.mq_curmsgs--;
286	info->qsize -= msg->m_ts;
287	return msg;
288}
289
290static struct inode *mqueue_get_inode(struct super_block *sb,
291		struct ipc_namespace *ipc_ns, umode_t mode,
292		struct mq_attr *attr)
293{
294	struct user_struct *u = current_user();
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->user = 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		spin_lock(&mq_lock);
374		if (u->mq_bytes + mq_bytes < u->mq_bytes ||
375		    u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
376			spin_unlock(&mq_lock);
377			/* mqueue_evict_inode() releases info->messages */
378			ret = -EMFILE;
379			goto out_inode;
380		}
381		u->mq_bytes += mq_bytes;
382		spin_unlock(&mq_lock);
383
384		/* all is ok */
385		info->user = get_uid(u);
386	} else if (S_ISDIR(mode)) {
387		inc_nlink(inode);
388		/* Some things misbehave if size == 0 on a directory */
389		inode->i_size = 2 * DIRENT_SIZE;
390		inode->i_op = &mqueue_dir_inode_operations;
391		inode->i_fop = &simple_dir_operations;
392	}
393
394	return inode;
395out_inode:
396	iput(inode);
397err:
398	return ERR_PTR(ret);
399}
400
401static int mqueue_fill_super(struct super_block *sb, struct fs_context *fc)
402{
403	struct inode *inode;
404	struct ipc_namespace *ns = sb->s_fs_info;
405
406	sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV;
407	sb->s_blocksize = PAGE_SIZE;
408	sb->s_blocksize_bits = PAGE_SHIFT;
409	sb->s_magic = MQUEUE_MAGIC;
410	sb->s_op = &mqueue_super_ops;
411
412	inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
413	if (IS_ERR(inode))
414		return PTR_ERR(inode);
415
416	sb->s_root = d_make_root(inode);
417	if (!sb->s_root)
418		return -ENOMEM;
419	return 0;
420}
421
422static int mqueue_get_tree(struct fs_context *fc)
423{
424	struct mqueue_fs_context *ctx = fc->fs_private;
425
426	return get_tree_keyed(fc, mqueue_fill_super, ctx->ipc_ns);
427}
428
429static void mqueue_fs_context_free(struct fs_context *fc)
430{
431	struct mqueue_fs_context *ctx = fc->fs_private;
432
433	put_ipc_ns(ctx->ipc_ns);
434	kfree(ctx);
435}
436
437static int mqueue_init_fs_context(struct fs_context *fc)
438{
439	struct mqueue_fs_context *ctx;
440
441	ctx = kzalloc(sizeof(struct mqueue_fs_context), GFP_KERNEL);
442	if (!ctx)
443		return -ENOMEM;
444
445	ctx->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
446	put_user_ns(fc->user_ns);
447	fc->user_ns = get_user_ns(ctx->ipc_ns->user_ns);
448	fc->fs_private = ctx;
449	fc->ops = &mqueue_fs_context_ops;
450	return 0;
451}
452
453static struct vfsmount *mq_create_mount(struct ipc_namespace *ns)
454{
455	struct mqueue_fs_context *ctx;
456	struct fs_context *fc;
457	struct vfsmount *mnt;
458
459	fc = fs_context_for_mount(&mqueue_fs_type, SB_KERNMOUNT);
460	if (IS_ERR(fc))
461		return ERR_CAST(fc);
462
463	ctx = fc->fs_private;
464	put_ipc_ns(ctx->ipc_ns);
465	ctx->ipc_ns = get_ipc_ns(ns);
466	put_user_ns(fc->user_ns);
467	fc->user_ns = get_user_ns(ctx->ipc_ns->user_ns);
468
469	mnt = fc_mount(fc);
470	put_fs_context(fc);
471	return mnt;
472}
473
474static void init_once(void *foo)
475{
476	struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
477
478	inode_init_once(&p->vfs_inode);
479}
480
481static struct inode *mqueue_alloc_inode(struct super_block *sb)
482{
483	struct mqueue_inode_info *ei;
484
485	ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
486	if (!ei)
487		return NULL;
488	return &ei->vfs_inode;
489}
490
491static void mqueue_free_inode(struct inode *inode)
492{
493	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
494}
495
496static void mqueue_evict_inode(struct inode *inode)
497{
498	struct mqueue_inode_info *info;
499	struct user_struct *user;
500	struct ipc_namespace *ipc_ns;
501	struct msg_msg *msg, *nmsg;
502	LIST_HEAD(tmp_msg);
503
504	clear_inode(inode);
505
506	if (S_ISDIR(inode->i_mode))
507		return;
508
509	ipc_ns = get_ns_from_inode(inode);
510	info = MQUEUE_I(inode);
511	spin_lock(&info->lock);
512	while ((msg = msg_get(info)) != NULL)
513		list_add_tail(&msg->m_list, &tmp_msg);
514	kfree(info->node_cache);
515	spin_unlock(&info->lock);
516
517	list_for_each_entry_safe(msg, nmsg, &tmp_msg, m_list) {
518		list_del(&msg->m_list);
519		free_msg(msg);
520	}
521
522	user = info->user;
523	if (user) {
524		unsigned long mq_bytes, mq_treesize;
525
526		/* Total amount of bytes accounted for the mqueue */
527		mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
528			min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
529			sizeof(struct posix_msg_tree_node);
530
531		mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
532					  info->attr.mq_msgsize);
533
534		spin_lock(&mq_lock);
535		user->mq_bytes -= mq_bytes;
536		/*
537		 * get_ns_from_inode() ensures that the
538		 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
539		 * to which we now hold a reference, or it is NULL.
540		 * We can't put it here under mq_lock, though.
541		 */
542		if (ipc_ns)
543			ipc_ns->mq_queues_count--;
544		spin_unlock(&mq_lock);
545		free_uid(user);
546	}
547	if (ipc_ns)
548		put_ipc_ns(ipc_ns);
549}
550
551static int mqueue_create_attr(struct dentry *dentry, umode_t mode, void *arg)
552{
553	struct inode *dir = dentry->d_parent->d_inode;
554	struct inode *inode;
555	struct mq_attr *attr = arg;
556	int error;
557	struct ipc_namespace *ipc_ns;
558
559	spin_lock(&mq_lock);
560	ipc_ns = __get_ns_from_inode(dir);
561	if (!ipc_ns) {
562		error = -EACCES;
563		goto out_unlock;
564	}
565
566	if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
567	    !capable(CAP_SYS_RESOURCE)) {
568		error = -ENOSPC;
569		goto out_unlock;
570	}
571	ipc_ns->mq_queues_count++;
572	spin_unlock(&mq_lock);
573
574	inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
575	if (IS_ERR(inode)) {
576		error = PTR_ERR(inode);
577		spin_lock(&mq_lock);
578		ipc_ns->mq_queues_count--;
579		goto out_unlock;
580	}
581
582	put_ipc_ns(ipc_ns);
583	dir->i_size += DIRENT_SIZE;
584	dir->i_ctime = dir->i_mtime = dir->i_atime = current_time(dir);
585
586	d_instantiate(dentry, inode);
587	dget(dentry);
588	return 0;
589out_unlock:
590	spin_unlock(&mq_lock);
591	if (ipc_ns)
592		put_ipc_ns(ipc_ns);
593	return error;
594}
595
596static int mqueue_create(struct inode *dir, struct dentry *dentry,
597				umode_t mode, bool excl)
598{
599	return mqueue_create_attr(dentry, mode, NULL);
600}
601
602static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
603{
604	struct inode *inode = d_inode(dentry);
605
606	dir->i_ctime = dir->i_mtime = dir->i_atime = current_time(dir);
607	dir->i_size -= DIRENT_SIZE;
608	drop_nlink(inode);
609	dput(dentry);
610	return 0;
611}
612
613/*
614*	This is routine for system read from queue file.
615*	To avoid mess with doing here some sort of mq_receive we allow
616*	to read only queue size & notification info (the only values
617*	that are interesting from user point of view and aren't accessible
618*	through std routines)
619*/
620static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
621				size_t count, loff_t *off)
622{
623	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
624	char buffer[FILENT_SIZE];
625	ssize_t ret;
626
627	spin_lock(&info->lock);
628	snprintf(buffer, sizeof(buffer),
629			"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
630			info->qsize,
631			info->notify_owner ? info->notify.sigev_notify : 0,
632			(info->notify_owner &&
633			 info->notify.sigev_notify == SIGEV_SIGNAL) ?
634				info->notify.sigev_signo : 0,
635			pid_vnr(info->notify_owner));
636	spin_unlock(&info->lock);
637	buffer[sizeof(buffer)-1] = '\0';
638
639	ret = simple_read_from_buffer(u_data, count, off, buffer,
640				strlen(buffer));
641	if (ret <= 0)
642		return ret;
643
644	file_inode(filp)->i_atime = file_inode(filp)->i_ctime = current_time(file_inode(filp));
645	return ret;
646}
647
648static int mqueue_flush_file(struct file *filp, fl_owner_t id)
649{
650	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
651
652	spin_lock(&info->lock);
653	if (task_tgid(current) == info->notify_owner)
654		remove_notification(info);
655
656	spin_unlock(&info->lock);
657	return 0;
658}
659
660static __poll_t mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
661{
662	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
663	__poll_t retval = 0;
664
665	poll_wait(filp, &info->wait_q, poll_tab);
666
667	spin_lock(&info->lock);
668	if (info->attr.mq_curmsgs)
669		retval = EPOLLIN | EPOLLRDNORM;
670
671	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
672		retval |= EPOLLOUT | EPOLLWRNORM;
673	spin_unlock(&info->lock);
674
675	return retval;
676}
677
678/* Adds current to info->e_wait_q[sr] before element with smaller prio */
679static void wq_add(struct mqueue_inode_info *info, int sr,
680			struct ext_wait_queue *ewp)
681{
682	struct ext_wait_queue *walk;
683
684	list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
685		if (walk->task->prio <= current->prio) {
686			list_add_tail(&ewp->list, &walk->list);
687			return;
688		}
689	}
690	list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
691}
692
693/*
694 * Puts current task to sleep. Caller must hold queue lock. After return
695 * lock isn't held.
696 * sr: SEND or RECV
697 */
698static int wq_sleep(struct mqueue_inode_info *info, int sr,
699		    ktime_t *timeout, struct ext_wait_queue *ewp)
700	__releases(&info->lock)
701{
702	int retval;
703	signed long time;
704
705	wq_add(info, sr, ewp);
706
707	for (;;) {
708		/* memory barrier not required, we hold info->lock */
709		__set_current_state(TASK_INTERRUPTIBLE);
710
711		spin_unlock(&info->lock);
712		time = schedule_hrtimeout_range_clock(timeout, 0,
713			HRTIMER_MODE_ABS, CLOCK_REALTIME);
714
715		if (READ_ONCE(ewp->state) == STATE_READY) {
716			/* see MQ_BARRIER for purpose/pairing */
717			smp_acquire__after_ctrl_dep();
718			retval = 0;
719			goto out;
720		}
721		spin_lock(&info->lock);
722
723		/* we hold info->lock, so no memory barrier required */
724		if (READ_ONCE(ewp->state) == STATE_READY) {
725			retval = 0;
726			goto out_unlock;
727		}
728		if (signal_pending(current)) {
729			retval = -ERESTARTSYS;
730			break;
731		}
732		if (time == 0) {
733			retval = -ETIMEDOUT;
734			break;
735		}
736	}
737	list_del(&ewp->list);
738out_unlock:
739	spin_unlock(&info->lock);
740out:
741	return retval;
742}
743
744/*
745 * Returns waiting task that should be serviced first or NULL if none exists
746 */
747static struct ext_wait_queue *wq_get_first_waiter(
748		struct mqueue_inode_info *info, int sr)
749{
750	struct list_head *ptr;
751
752	ptr = info->e_wait_q[sr].list.prev;
753	if (ptr == &info->e_wait_q[sr].list)
754		return NULL;
755	return list_entry(ptr, struct ext_wait_queue, list);
756}
757
758
759static inline void set_cookie(struct sk_buff *skb, char code)
760{
761	((char *)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
762}
763
764/*
765 * The next function is only to split too long sys_mq_timedsend
766 */
767static void __do_notify(struct mqueue_inode_info *info)
768{
769	/* notification
770	 * invoked when there is registered process and there isn't process
771	 * waiting synchronously for message AND state of queue changed from
772	 * empty to not empty. Here we are sure that no one is waiting
773	 * synchronously. */
774	if (info->notify_owner &&
775	    info->attr.mq_curmsgs == 1) {
776		struct kernel_siginfo sig_i;
777		switch (info->notify.sigev_notify) {
778		case SIGEV_NONE:
779			break;
780		case SIGEV_SIGNAL:
781			/* sends signal */
782
783			clear_siginfo(&sig_i);
784			sig_i.si_signo = info->notify.sigev_signo;
785			sig_i.si_errno = 0;
786			sig_i.si_code = SI_MESGQ;
787			sig_i.si_value = info->notify.sigev_value;
788			/* map current pid/uid into info->owner's namespaces */
789			rcu_read_lock();
790			sig_i.si_pid = task_tgid_nr_ns(current,
791						ns_of_pid(info->notify_owner));
792			sig_i.si_uid = from_kuid_munged(info->notify_user_ns, current_uid());
793			rcu_read_unlock();
794
795			kill_pid_info(info->notify.sigev_signo,
796				      &sig_i, info->notify_owner);
797			break;
798		case SIGEV_THREAD:
799			set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
800			netlink_sendskb(info->notify_sock, info->notify_cookie);
801			break;
802		}
803		/* after notification unregisters process */
804		put_pid(info->notify_owner);
805		put_user_ns(info->notify_user_ns);
806		info->notify_owner = NULL;
807		info->notify_user_ns = NULL;
808	}
809	wake_up(&info->wait_q);
810}
811
812static int prepare_timeout(const struct __kernel_timespec __user *u_abs_timeout,
813			   struct timespec64 *ts)
814{
815	if (get_timespec64(ts, u_abs_timeout))
816		return -EFAULT;
817	if (!timespec64_valid(ts))
818		return -EINVAL;
819	return 0;
820}
821
822static void remove_notification(struct mqueue_inode_info *info)
823{
824	if (info->notify_owner != NULL &&
825	    info->notify.sigev_notify == SIGEV_THREAD) {
826		set_cookie(info->notify_cookie, NOTIFY_REMOVED);
827		netlink_sendskb(info->notify_sock, info->notify_cookie);
828	}
829	put_pid(info->notify_owner);
830	put_user_ns(info->notify_user_ns);
831	info->notify_owner = NULL;
832	info->notify_user_ns = NULL;
833}
834
835static int prepare_open(struct dentry *dentry, int oflag, int ro,
836			umode_t mode, struct filename *name,
837			struct mq_attr *attr)
838{
839	static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
840						  MAY_READ | MAY_WRITE };
841	int acc;
842
843	if (d_really_is_negative(dentry)) {
844		if (!(oflag & O_CREAT))
845			return -ENOENT;
846		if (ro)
847			return ro;
848		audit_inode_parent_hidden(name, dentry->d_parent);
849		return vfs_mkobj(dentry, mode & ~current_umask(),
850				  mqueue_create_attr, attr);
851	}
852	/* it already existed */
853	audit_inode(name, dentry, 0);
854	if ((oflag & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
855		return -EEXIST;
856	if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
857		return -EINVAL;
858	acc = oflag2acc[oflag & O_ACCMODE];
859	return inode_permission(d_inode(dentry), acc);
860}
861
862static int do_mq_open(const char __user *u_name, int oflag, umode_t mode,
863		      struct mq_attr *attr)
864{
865	struct vfsmount *mnt = current->nsproxy->ipc_ns->mq_mnt;
866	struct dentry *root = mnt->mnt_root;
867	struct filename *name;
868	struct path path;
869	int fd, error;
870	int ro;
871
872	audit_mq_open(oflag, mode, attr);
873
874	if (IS_ERR(name = getname(u_name)))
875		return PTR_ERR(name);
876
877	fd = get_unused_fd_flags(O_CLOEXEC);
878	if (fd < 0)
879		goto out_putname;
880
881	ro = mnt_want_write(mnt);	/* we'll drop it in any case */
882	inode_lock(d_inode(root));
883	path.dentry = lookup_one_len(name->name, root, strlen(name->name));
884	if (IS_ERR(path.dentry)) {
885		error = PTR_ERR(path.dentry);
886		goto out_putfd;
887	}
888	path.mnt = mntget(mnt);
889	error = prepare_open(path.dentry, oflag, ro, mode, name, attr);
890	if (!error) {
891		struct file *file = dentry_open(&path, oflag, current_cred());
892		if (!IS_ERR(file))
893			fd_install(fd, file);
894		else
895			error = PTR_ERR(file);
896	}
897	path_put(&path);
898out_putfd:
899	if (error) {
900		put_unused_fd(fd);
901		fd = error;
902	}
903	inode_unlock(d_inode(root));
904	if (!ro)
905		mnt_drop_write(mnt);
906out_putname:
907	putname(name);
908	return fd;
909}
910
911SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
912		struct mq_attr __user *, u_attr)
913{
914	struct mq_attr attr;
915	if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
916		return -EFAULT;
917
918	return do_mq_open(u_name, oflag, mode, u_attr ? &attr : NULL);
919}
920
921SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
922{
923	int err;
924	struct filename *name;
925	struct dentry *dentry;
926	struct inode *inode = NULL;
927	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
928	struct vfsmount *mnt = ipc_ns->mq_mnt;
929
930	name = getname(u_name);
931	if (IS_ERR(name))
932		return PTR_ERR(name);
933
934	audit_inode_parent_hidden(name, mnt->mnt_root);
935	err = mnt_want_write(mnt);
936	if (err)
937		goto out_name;
938	inode_lock_nested(d_inode(mnt->mnt_root), I_MUTEX_PARENT);
939	dentry = lookup_one_len(name->name, mnt->mnt_root,
940				strlen(name->name));
941	if (IS_ERR(dentry)) {
942		err = PTR_ERR(dentry);
943		goto out_unlock;
944	}
945
946	inode = d_inode(dentry);
947	if (!inode) {
948		err = -ENOENT;
949	} else {
950		ihold(inode);
951		err = vfs_unlink(d_inode(dentry->d_parent), dentry, NULL);
952	}
953	dput(dentry);
954
955out_unlock:
956	inode_unlock(d_inode(mnt->mnt_root));
957	if (inode)
958		iput(inode);
959	mnt_drop_write(mnt);
960out_name:
961	putname(name);
962
963	return err;
964}
965
966/* Pipelined send and receive functions.
967 *
968 * If a receiver finds no waiting message, then it registers itself in the
969 * list of waiting receivers. A sender checks that list before adding the new
970 * message into the message array. If there is a waiting receiver, then it
971 * bypasses the message array and directly hands the message over to the
972 * receiver. The receiver accepts the message and returns without grabbing the
973 * queue spinlock:
974 *
975 * - Set pointer to message.
976 * - Queue the receiver task for later wakeup (without the info->lock).
977 * - Update its state to STATE_READY. Now the receiver can continue.
978 * - Wake up the process after the lock is dropped. Should the process wake up
979 *   before this wakeup (due to a timeout or a signal) it will either see
980 *   STATE_READY and continue or acquire the lock to check the state again.
981 *
982 * The same algorithm is used for senders.
983 */
984
985static inline void __pipelined_op(struct wake_q_head *wake_q,
986				  struct mqueue_inode_info *info,
987				  struct ext_wait_queue *this)
988{
989	list_del(&this->list);
990	get_task_struct(this->task);
991
992	/* see MQ_BARRIER for purpose/pairing */
993	smp_store_release(&this->state, STATE_READY);
994	wake_q_add_safe(wake_q, this->task);
995}
996
997/* pipelined_send() - send a message directly to the task waiting in
998 * sys_mq_timedreceive() (without inserting message into a queue).
999 */
1000static inline void pipelined_send(struct wake_q_head *wake_q,
1001				  struct mqueue_inode_info *info,
1002				  struct msg_msg *message,
1003				  struct ext_wait_queue *receiver)
1004{
1005	receiver->msg = message;
1006	__pipelined_op(wake_q, info, receiver);
1007}
1008
1009/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
1010 * gets its message and put to the queue (we have one free place for sure). */
1011static inline void pipelined_receive(struct wake_q_head *wake_q,
1012				     struct mqueue_inode_info *info)
1013{
1014	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
1015
1016	if (!sender) {
1017		/* for poll */
1018		wake_up_interruptible(&info->wait_q);
1019		return;
1020	}
1021	if (msg_insert(sender->msg, info))
1022		return;
1023
1024	__pipelined_op(wake_q, info, sender);
1025}
1026
1027static int do_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
1028		size_t msg_len, unsigned int msg_prio,
1029		struct timespec64 *ts)
1030{
1031	struct fd f;
1032	struct inode *inode;
1033	struct ext_wait_queue wait;
1034	struct ext_wait_queue *receiver;
1035	struct msg_msg *msg_ptr;
1036	struct mqueue_inode_info *info;
1037	ktime_t expires, *timeout = NULL;
1038	struct posix_msg_tree_node *new_leaf = NULL;
1039	int ret = 0;
1040	DEFINE_WAKE_Q(wake_q);
1041
1042	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
1043		return -EINVAL;
1044
1045	if (ts) {
1046		expires = timespec64_to_ktime(*ts);
1047		timeout = &expires;
1048	}
1049
1050	audit_mq_sendrecv(mqdes, msg_len, msg_prio, ts);
1051
1052	f = fdget(mqdes);
1053	if (unlikely(!f.file)) {
1054		ret = -EBADF;
1055		goto out;
1056	}
1057
1058	inode = file_inode(f.file);
1059	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1060		ret = -EBADF;
1061		goto out_fput;
1062	}
1063	info = MQUEUE_I(inode);
1064	audit_file(f.file);
1065
1066	if (unlikely(!(f.file->f_mode & FMODE_WRITE))) {
1067		ret = -EBADF;
1068		goto out_fput;
1069	}
1070
1071	if (unlikely(msg_len > info->attr.mq_msgsize)) {
1072		ret = -EMSGSIZE;
1073		goto out_fput;
1074	}
1075
1076	/* First try to allocate memory, before doing anything with
1077	 * existing queues. */
1078	msg_ptr = load_msg(u_msg_ptr, msg_len);
1079	if (IS_ERR(msg_ptr)) {
1080		ret = PTR_ERR(msg_ptr);
1081		goto out_fput;
1082	}
1083	msg_ptr->m_ts = msg_len;
1084	msg_ptr->m_type = msg_prio;
1085
1086	/*
1087	 * msg_insert really wants us to have a valid, spare node struct so
1088	 * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1089	 * fall back to that if necessary.
1090	 */
1091	if (!info->node_cache)
1092		new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1093
1094	spin_lock(&info->lock);
1095
1096	if (!info->node_cache && new_leaf) {
1097		/* Save our speculative allocation into the cache */
1098		INIT_LIST_HEAD(&new_leaf->msg_list);
1099		info->node_cache = new_leaf;
1100		new_leaf = NULL;
1101	} else {
1102		kfree(new_leaf);
1103	}
1104
1105	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
1106		if (f.file->f_flags & O_NONBLOCK) {
1107			ret = -EAGAIN;
1108		} else {
1109			wait.task = current;
1110			wait.msg = (void *) msg_ptr;
1111
1112			/* memory barrier not required, we hold info->lock */
1113			WRITE_ONCE(wait.state, STATE_NONE);
1114			ret = wq_sleep(info, SEND, timeout, &wait);
1115			/*
1116			 * wq_sleep must be called with info->lock held, and
1117			 * returns with the lock released
1118			 */
1119			goto out_free;
1120		}
1121	} else {
1122		receiver = wq_get_first_waiter(info, RECV);
1123		if (receiver) {
1124			pipelined_send(&wake_q, info, msg_ptr, receiver);
1125		} else {
1126			/* adds message to the queue */
1127			ret = msg_insert(msg_ptr, info);
1128			if (ret)
1129				goto out_unlock;
1130			__do_notify(info);
1131		}
1132		inode->i_atime = inode->i_mtime = inode->i_ctime =
1133				current_time(inode);
1134	}
1135out_unlock:
1136	spin_unlock(&info->lock);
1137	wake_up_q(&wake_q);
1138out_free:
1139	if (ret)
1140		free_msg(msg_ptr);
1141out_fput:
1142	fdput(f);
1143out:
1144	return ret;
1145}
1146
1147static int do_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
1148		size_t msg_len, unsigned int __user *u_msg_prio,
1149		struct timespec64 *ts)
1150{
1151	ssize_t ret;
1152	struct msg_msg *msg_ptr;
1153	struct fd f;
1154	struct inode *inode;
1155	struct mqueue_inode_info *info;
1156	struct ext_wait_queue wait;
1157	ktime_t expires, *timeout = NULL;
1158	struct posix_msg_tree_node *new_leaf = NULL;
1159
1160	if (ts) {
1161		expires = timespec64_to_ktime(*ts);
1162		timeout = &expires;
1163	}
1164
1165	audit_mq_sendrecv(mqdes, msg_len, 0, ts);
1166
1167	f = fdget(mqdes);
1168	if (unlikely(!f.file)) {
1169		ret = -EBADF;
1170		goto out;
1171	}
1172
1173	inode = file_inode(f.file);
1174	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1175		ret = -EBADF;
1176		goto out_fput;
1177	}
1178	info = MQUEUE_I(inode);
1179	audit_file(f.file);
1180
1181	if (unlikely(!(f.file->f_mode & FMODE_READ))) {
1182		ret = -EBADF;
1183		goto out_fput;
1184	}
1185
1186	/* checks if buffer is big enough */
1187	if (unlikely(msg_len < info->attr.mq_msgsize)) {
1188		ret = -EMSGSIZE;
1189		goto out_fput;
1190	}
1191
1192	/*
1193	 * msg_insert really wants us to have a valid, spare node struct so
1194	 * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1195	 * fall back to that if necessary.
1196	 */
1197	if (!info->node_cache)
1198		new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1199
1200	spin_lock(&info->lock);
1201
1202	if (!info->node_cache && new_leaf) {
1203		/* Save our speculative allocation into the cache */
1204		INIT_LIST_HEAD(&new_leaf->msg_list);
1205		info->node_cache = new_leaf;
1206	} else {
1207		kfree(new_leaf);
1208	}
1209
1210	if (info->attr.mq_curmsgs == 0) {
1211		if (f.file->f_flags & O_NONBLOCK) {
1212			spin_unlock(&info->lock);
1213			ret = -EAGAIN;
1214		} else {
1215			wait.task = current;
1216
1217			/* memory barrier not required, we hold info->lock */
1218			WRITE_ONCE(wait.state, STATE_NONE);
1219			ret = wq_sleep(info, RECV, timeout, &wait);
1220			msg_ptr = wait.msg;
1221		}
1222	} else {
1223		DEFINE_WAKE_Q(wake_q);
1224
1225		msg_ptr = msg_get(info);
1226
1227		inode->i_atime = inode->i_mtime = inode->i_ctime =
1228				current_time(inode);
1229
1230		/* There is now free space in queue. */
1231		pipelined_receive(&wake_q, info);
1232		spin_unlock(&info->lock);
1233		wake_up_q(&wake_q);
1234		ret = 0;
1235	}
1236	if (ret == 0) {
1237		ret = msg_ptr->m_ts;
1238
1239		if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1240			store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1241			ret = -EFAULT;
1242		}
1243		free_msg(msg_ptr);
1244	}
1245out_fput:
1246	fdput(f);
1247out:
1248	return ret;
1249}
1250
1251SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
1252		size_t, msg_len, unsigned int, msg_prio,
1253		const struct __kernel_timespec __user *, u_abs_timeout)
1254{
1255	struct timespec64 ts, *p = NULL;
1256	if (u_abs_timeout) {
1257		int res = prepare_timeout(u_abs_timeout, &ts);
1258		if (res)
1259			return res;
1260		p = &ts;
1261	}
1262	return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p);
1263}
1264
1265SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
1266		size_t, msg_len, unsigned int __user *, u_msg_prio,
1267		const struct __kernel_timespec __user *, u_abs_timeout)
1268{
1269	struct timespec64 ts, *p = NULL;
1270	if (u_abs_timeout) {
1271		int res = prepare_timeout(u_abs_timeout, &ts);
1272		if (res)
1273			return res;
1274		p = &ts;
1275	}
1276	return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p);
1277}
1278
1279/*
1280 * Notes: the case when user wants us to deregister (with NULL as pointer)
1281 * and he isn't currently owner of notification, will be silently discarded.
1282 * It isn't explicitly defined in the POSIX.
1283 */
1284static int do_mq_notify(mqd_t mqdes, const struct sigevent *notification)
1285{
1286	int ret;
1287	struct fd f;
1288	struct sock *sock;
1289	struct inode *inode;
1290	struct mqueue_inode_info *info;
1291	struct sk_buff *nc;
1292
1293	audit_mq_notify(mqdes, notification);
1294
1295	nc = NULL;
1296	sock = NULL;
1297	if (notification != NULL) {
1298		if (unlikely(notification->sigev_notify != SIGEV_NONE &&
1299			     notification->sigev_notify != SIGEV_SIGNAL &&
1300			     notification->sigev_notify != SIGEV_THREAD))
1301			return -EINVAL;
1302		if (notification->sigev_notify == SIGEV_SIGNAL &&
1303			!valid_signal(notification->sigev_signo)) {
1304			return -EINVAL;
1305		}
1306		if (notification->sigev_notify == SIGEV_THREAD) {
1307			long timeo;
1308
1309			/* create the notify skb */
1310			nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1311			if (!nc)
1312				return -ENOMEM;
1313
1314			if (copy_from_user(nc->data,
1315					notification->sigev_value.sival_ptr,
1316					NOTIFY_COOKIE_LEN)) {
1317				ret = -EFAULT;
1318				goto free_skb;
1319			}
1320
1321			/* TODO: add a header? */
1322			skb_put(nc, NOTIFY_COOKIE_LEN);
1323			/* and attach it to the socket */
1324retry:
1325			f = fdget(notification->sigev_signo);
1326			if (!f.file) {
1327				ret = -EBADF;
1328				goto out;
1329			}
1330			sock = netlink_getsockbyfilp(f.file);
1331			fdput(f);
1332			if (IS_ERR(sock)) {
1333				ret = PTR_ERR(sock);
1334				goto free_skb;
1335			}
1336
1337			timeo = MAX_SCHEDULE_TIMEOUT;
1338			ret = netlink_attachskb(sock, nc, &timeo, NULL);
1339			if (ret == 1) {
1340				sock = NULL;
1341				goto retry;
1342			}
1343			if (ret)
1344				return ret;
1345		}
1346	}
1347
1348	f = fdget(mqdes);
1349	if (!f.file) {
1350		ret = -EBADF;
1351		goto out;
1352	}
1353
1354	inode = file_inode(f.file);
1355	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1356		ret = -EBADF;
1357		goto out_fput;
1358	}
1359	info = MQUEUE_I(inode);
1360
1361	ret = 0;
1362	spin_lock(&info->lock);
1363	if (notification == NULL) {
1364		if (info->notify_owner == task_tgid(current)) {
1365			remove_notification(info);
1366			inode->i_atime = inode->i_ctime = current_time(inode);
1367		}
1368	} else if (info->notify_owner != NULL) {
1369		ret = -EBUSY;
1370	} else {
1371		switch (notification->sigev_notify) {
1372		case SIGEV_NONE:
1373			info->notify.sigev_notify = SIGEV_NONE;
1374			break;
1375		case SIGEV_THREAD:
1376			info->notify_sock = sock;
1377			info->notify_cookie = nc;
1378			sock = NULL;
1379			nc = NULL;
1380			info->notify.sigev_notify = SIGEV_THREAD;
1381			break;
1382		case SIGEV_SIGNAL:
1383			info->notify.sigev_signo = notification->sigev_signo;
1384			info->notify.sigev_value = notification->sigev_value;
1385			info->notify.sigev_notify = SIGEV_SIGNAL;
1386			break;
1387		}
1388
1389		info->notify_owner = get_pid(task_tgid(current));
1390		info->notify_user_ns = get_user_ns(current_user_ns());
1391		inode->i_atime = inode->i_ctime = current_time(inode);
1392	}
1393	spin_unlock(&info->lock);
1394out_fput:
1395	fdput(f);
1396out:
1397	if (sock)
1398		netlink_detachskb(sock, nc);
1399	else
1400free_skb:
1401		dev_kfree_skb(nc);
1402
1403	return ret;
1404}
1405
1406SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1407		const struct sigevent __user *, u_notification)
1408{
1409	struct sigevent n, *p = NULL;
1410	if (u_notification) {
1411		if (copy_from_user(&n, u_notification, sizeof(struct sigevent)))
1412			return -EFAULT;
1413		p = &n;
1414	}
1415	return do_mq_notify(mqdes, p);
1416}
1417
1418static int do_mq_getsetattr(int mqdes, struct mq_attr *new, struct mq_attr *old)
1419{
1420	struct fd f;
1421	struct inode *inode;
1422	struct mqueue_inode_info *info;
1423
1424	if (new && (new->mq_flags & (~O_NONBLOCK)))
1425		return -EINVAL;
1426
1427	f = fdget(mqdes);
1428	if (!f.file)
1429		return -EBADF;
1430
1431	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1432		fdput(f);
1433		return -EBADF;
1434	}
1435
1436	inode = file_inode(f.file);
1437	info = MQUEUE_I(inode);
1438
1439	spin_lock(&info->lock);
1440
1441	if (old) {
1442		*old = info->attr;
1443		old->mq_flags = f.file->f_flags & O_NONBLOCK;
1444	}
1445	if (new) {
1446		audit_mq_getsetattr(mqdes, new);
1447		spin_lock(&f.file->f_lock);
1448		if (new->mq_flags & O_NONBLOCK)
1449			f.file->f_flags |= O_NONBLOCK;
1450		else
1451			f.file->f_flags &= ~O_NONBLOCK;
1452		spin_unlock(&f.file->f_lock);
1453
1454		inode->i_atime = inode->i_ctime = current_time(inode);
1455	}
1456
1457	spin_unlock(&info->lock);
1458	fdput(f);
1459	return 0;
1460}
1461
1462SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1463		const struct mq_attr __user *, u_mqstat,
1464		struct mq_attr __user *, u_omqstat)
1465{
1466	int ret;
1467	struct mq_attr mqstat, omqstat;
1468	struct mq_attr *new = NULL, *old = NULL;
1469
1470	if (u_mqstat) {
1471		new = &mqstat;
1472		if (copy_from_user(new, u_mqstat, sizeof(struct mq_attr)))
1473			return -EFAULT;
1474	}
1475	if (u_omqstat)
1476		old = &omqstat;
1477
1478	ret = do_mq_getsetattr(mqdes, new, old);
1479	if (ret || !old)
1480		return ret;
1481
1482	if (copy_to_user(u_omqstat, old, sizeof(struct mq_attr)))
1483		return -EFAULT;
1484	return 0;
1485}
1486
1487#ifdef CONFIG_COMPAT
1488
1489struct compat_mq_attr {
1490	compat_long_t mq_flags;      /* message queue flags		     */
1491	compat_long_t mq_maxmsg;     /* maximum number of messages	     */
1492	compat_long_t mq_msgsize;    /* maximum message size		     */
1493	compat_long_t mq_curmsgs;    /* number of messages currently queued  */
1494	compat_long_t __reserved[4]; /* ignored for input, zeroed for output */
1495};
1496
1497static inline int get_compat_mq_attr(struct mq_attr *attr,
1498			const struct compat_mq_attr __user *uattr)
1499{
1500	struct compat_mq_attr v;
1501
1502	if (copy_from_user(&v, uattr, sizeof(*uattr)))
1503		return -EFAULT;
1504
1505	memset(attr, 0, sizeof(*attr));
1506	attr->mq_flags = v.mq_flags;
1507	attr->mq_maxmsg = v.mq_maxmsg;
1508	attr->mq_msgsize = v.mq_msgsize;
1509	attr->mq_curmsgs = v.mq_curmsgs;
1510	return 0;
1511}
1512
1513static inline int put_compat_mq_attr(const struct mq_attr *attr,
1514			struct compat_mq_attr __user *uattr)
1515{
1516	struct compat_mq_attr v;
1517
1518	memset(&v, 0, sizeof(v));
1519	v.mq_flags = attr->mq_flags;
1520	v.mq_maxmsg = attr->mq_maxmsg;
1521	v.mq_msgsize = attr->mq_msgsize;
1522	v.mq_curmsgs = attr->mq_curmsgs;
1523	if (copy_to_user(uattr, &v, sizeof(*uattr)))
1524		return -EFAULT;
1525	return 0;
1526}
1527
1528COMPAT_SYSCALL_DEFINE4(mq_open, const char __user *, u_name,
1529		       int, oflag, compat_mode_t, mode,
1530		       struct compat_mq_attr __user *, u_attr)
1531{
1532	struct mq_attr attr, *p = NULL;
1533	if (u_attr && oflag & O_CREAT) {
1534		p = &attr;
1535		if (get_compat_mq_attr(&attr, u_attr))
1536			return -EFAULT;
1537	}
1538	return do_mq_open(u_name, oflag, mode, p);
1539}
1540
1541COMPAT_SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1542		       const struct compat_sigevent __user *, u_notification)
1543{
1544	struct sigevent n, *p = NULL;
1545	if (u_notification) {
1546		if (get_compat_sigevent(&n, u_notification))
1547			return -EFAULT;
1548		if (n.sigev_notify == SIGEV_THREAD)
1549			n.sigev_value.sival_ptr = compat_ptr(n.sigev_value.sival_int);
1550		p = &n;
1551	}
1552	return do_mq_notify(mqdes, p);
1553}
1554
1555COMPAT_SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1556		       const struct compat_mq_attr __user *, u_mqstat,
1557		       struct compat_mq_attr __user *, u_omqstat)
1558{
1559	int ret;
1560	struct mq_attr mqstat, omqstat;
1561	struct mq_attr *new = NULL, *old = NULL;
1562
1563	if (u_mqstat) {
1564		new = &mqstat;
1565		if (get_compat_mq_attr(new, u_mqstat))
1566			return -EFAULT;
1567	}
1568	if (u_omqstat)
1569		old = &omqstat;
1570
1571	ret = do_mq_getsetattr(mqdes, new, old);
1572	if (ret || !old)
1573		return ret;
1574
1575	if (put_compat_mq_attr(old, u_omqstat))
1576		return -EFAULT;
1577	return 0;
1578}
1579#endif
1580
1581#ifdef CONFIG_COMPAT_32BIT_TIME
1582static int compat_prepare_timeout(const struct old_timespec32 __user *p,
1583				   struct timespec64 *ts)
1584{
1585	if (get_old_timespec32(ts, p))
1586		return -EFAULT;
1587	if (!timespec64_valid(ts))
1588		return -EINVAL;
1589	return 0;
1590}
1591
1592SYSCALL_DEFINE5(mq_timedsend_time32, mqd_t, mqdes,
1593		const char __user *, u_msg_ptr,
1594		unsigned int, msg_len, unsigned int, msg_prio,
1595		const struct old_timespec32 __user *, u_abs_timeout)
1596{
1597	struct timespec64 ts, *p = NULL;
1598	if (u_abs_timeout) {
1599		int res = compat_prepare_timeout(u_abs_timeout, &ts);
1600		if (res)
1601			return res;
1602		p = &ts;
1603	}
1604	return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p);
1605}
1606
1607SYSCALL_DEFINE5(mq_timedreceive_time32, mqd_t, mqdes,
1608		char __user *, u_msg_ptr,
1609		unsigned int, msg_len, unsigned int __user *, u_msg_prio,
1610		const struct old_timespec32 __user *, u_abs_timeout)
1611{
1612	struct timespec64 ts, *p = NULL;
1613	if (u_abs_timeout) {
1614		int res = compat_prepare_timeout(u_abs_timeout, &ts);
1615		if (res)
1616			return res;
1617		p = &ts;
1618	}
1619	return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p);
1620}
1621#endif
1622
1623static const struct inode_operations mqueue_dir_inode_operations = {
1624	.lookup = simple_lookup,
1625	.create = mqueue_create,
1626	.unlink = mqueue_unlink,
1627};
1628
1629static const struct file_operations mqueue_file_operations = {
1630	.flush = mqueue_flush_file,
1631	.poll = mqueue_poll_file,
1632	.read = mqueue_read_file,
1633	.llseek = default_llseek,
1634};
1635
1636static const struct super_operations mqueue_super_ops = {
1637	.alloc_inode = mqueue_alloc_inode,
1638	.free_inode = mqueue_free_inode,
1639	.evict_inode = mqueue_evict_inode,
1640	.statfs = simple_statfs,
1641};
1642
1643static const struct fs_context_operations mqueue_fs_context_ops = {
1644	.free		= mqueue_fs_context_free,
1645	.get_tree	= mqueue_get_tree,
1646};
1647
1648static struct file_system_type mqueue_fs_type = {
1649	.name			= "mqueue",
1650	.init_fs_context	= mqueue_init_fs_context,
1651	.kill_sb		= kill_litter_super,
1652	.fs_flags		= FS_USERNS_MOUNT,
1653};
1654
1655int mq_init_ns(struct ipc_namespace *ns)
1656{
1657	struct vfsmount *m;
1658
1659	ns->mq_queues_count  = 0;
1660	ns->mq_queues_max    = DFLT_QUEUESMAX;
1661	ns->mq_msg_max       = DFLT_MSGMAX;
1662	ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1663	ns->mq_msg_default   = DFLT_MSG;
1664	ns->mq_msgsize_default  = DFLT_MSGSIZE;
1665
1666	m = mq_create_mount(ns);
1667	if (IS_ERR(m))
1668		return PTR_ERR(m);
1669	ns->mq_mnt = m;
1670	return 0;
1671}
1672
1673void mq_clear_sbinfo(struct ipc_namespace *ns)
1674{
1675	ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1676}
1677
1678void mq_put_mnt(struct ipc_namespace *ns)
1679{
1680	kern_unmount(ns->mq_mnt);
1681}
1682
1683static int __init init_mqueue_fs(void)
1684{
1685	int error;
1686
1687	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1688				sizeof(struct mqueue_inode_info), 0,
1689				SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT, init_once);
1690	if (mqueue_inode_cachep == NULL)
1691		return -ENOMEM;
1692
1693	/* ignore failures - they are not fatal */
1694	mq_sysctl_table = mq_register_sysctl_table();
1695
1696	error = register_filesystem(&mqueue_fs_type);
1697	if (error)
1698		goto out_sysctl;
1699
1700	spin_lock_init(&mq_lock);
1701
1702	error = mq_init_ns(&init_ipc_ns);
1703	if (error)
1704		goto out_filesystem;
1705
1706	return 0;
1707
1708out_filesystem:
1709	unregister_filesystem(&mqueue_fs_type);
1710out_sysctl:
1711	if (mq_sysctl_table)
1712		unregister_sysctl_table(mq_sysctl_table);
1713	kmem_cache_destroy(mqueue_inode_cachep);
1714	return error;
1715}
1716
1717device_initcall(init_mqueue_fs);
1718