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	bool			 newns;	/* Set if newly created ipc namespace */
49};
50
51#define MQUEUE_MAGIC	0x19800202
52#define DIRENT_SIZE	20
53#define FILENT_SIZE	80
54
55#define SEND		0
56#define RECV		1
57
58#define STATE_NONE	0
59#define STATE_READY	1
60
61struct posix_msg_tree_node {
62	struct rb_node		rb_node;
63	struct list_head	msg_list;
64	int			priority;
65};
66
67/*
68 * Locking:
69 *
70 * Accesses to a message queue are synchronized by acquiring info->lock.
71 *
72 * There are two notable exceptions:
73 * - The actual wakeup of a sleeping task is performed using the wake_q
74 *   framework. info->lock is already released when wake_up_q is called.
75 * - The exit codepaths after sleeping check ext_wait_queue->state without
76 *   any locks. If it is STATE_READY, then the syscall is completed without
77 *   acquiring info->lock.
78 *
79 * MQ_BARRIER:
80 * To achieve proper release/acquire memory barrier pairing, the state is set to
81 * STATE_READY with smp_store_release(), and it is read with READ_ONCE followed
82 * by smp_acquire__after_ctrl_dep(). In addition, wake_q_add_safe() is used.
83 *
84 * This prevents the following races:
85 *
86 * 1) With the simple wake_q_add(), the task could be gone already before
87 *    the increase of the reference happens
88 * Thread A
89 *				Thread B
90 * WRITE_ONCE(wait.state, STATE_NONE);
91 * schedule_hrtimeout()
92 *				wake_q_add(A)
93 *				if (cmpxchg()) // success
94 *				   ->state = STATE_READY (reordered)
95 * <timeout returns>
96 * if (wait.state == STATE_READY) return;
97 * sysret to user space
98 * sys_exit()
99 *				get_task_struct() // UaF
100 *
101 * Solution: Use wake_q_add_safe() and perform the get_task_struct() before
102 * the smp_store_release() that does ->state = STATE_READY.
103 *
104 * 2) Without proper _release/_acquire barriers, the woken up task
105 *    could read stale data
106 *
107 * Thread A
108 *				Thread B
109 * do_mq_timedreceive
110 * WRITE_ONCE(wait.state, STATE_NONE);
111 * schedule_hrtimeout()
112 *				state = STATE_READY;
113 * <timeout returns>
114 * if (wait.state == STATE_READY) return;
115 * msg_ptr = wait.msg;		// Access to stale data!
116 *				receiver->msg = message; (reordered)
117 *
118 * Solution: use _release and _acquire barriers.
119 *
120 * 3) There is intentionally no barrier when setting current->state
121 *    to TASK_INTERRUPTIBLE: spin_unlock(&info->lock) provides the
122 *    release memory barrier, and the wakeup is triggered when holding
123 *    info->lock, i.e. spin_lock(&info->lock) provided a pairing
124 *    acquire memory barrier.
125 */
126
127struct ext_wait_queue {		/* queue of sleeping tasks */
128	struct task_struct *task;
129	struct list_head list;
130	struct msg_msg *msg;	/* ptr of loaded message */
131	int state;		/* one of STATE_* values */
132};
133
134struct mqueue_inode_info {
135	spinlock_t lock;
136	struct inode vfs_inode;
137	wait_queue_head_t wait_q;
138
139	struct rb_root msg_tree;
140	struct rb_node *msg_tree_rightmost;
141	struct posix_msg_tree_node *node_cache;
142	struct mq_attr attr;
143
144	struct sigevent notify;
145	struct pid *notify_owner;
146	u32 notify_self_exec_id;
147	struct user_namespace *notify_user_ns;
148	struct ucounts *ucounts;	/* user who created, for accounting */
149	struct sock *notify_sock;
150	struct sk_buff *notify_cookie;
151
152	/* for tasks waiting for free space and messages, respectively */
153	struct ext_wait_queue e_wait_q[2];
154
155	unsigned long qsize; /* size of queue in memory (sum of all msgs) */
156};
157
158static struct file_system_type mqueue_fs_type;
159static const struct inode_operations mqueue_dir_inode_operations;
160static const struct file_operations mqueue_file_operations;
161static const struct super_operations mqueue_super_ops;
162static const struct fs_context_operations mqueue_fs_context_ops;
163static void remove_notification(struct mqueue_inode_info *info);
164
165static struct kmem_cache *mqueue_inode_cachep;
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 inode *inode;
295	int ret = -ENOMEM;
296
297	inode = new_inode(sb);
298	if (!inode)
299		goto err;
300
301	inode->i_ino = get_next_ino();
302	inode->i_mode = mode;
303	inode->i_uid = current_fsuid();
304	inode->i_gid = current_fsgid();
305	inode->i_mtime = inode->i_ctime = inode->i_atime = current_time(inode);
306
307	if (S_ISREG(mode)) {
308		struct mqueue_inode_info *info;
309		unsigned long mq_bytes, mq_treesize;
310
311		inode->i_fop = &mqueue_file_operations;
312		inode->i_size = FILENT_SIZE;
313		/* mqueue specific info */
314		info = MQUEUE_I(inode);
315		spin_lock_init(&info->lock);
316		init_waitqueue_head(&info->wait_q);
317		INIT_LIST_HEAD(&info->e_wait_q[0].list);
318		INIT_LIST_HEAD(&info->e_wait_q[1].list);
319		info->notify_owner = NULL;
320		info->notify_user_ns = NULL;
321		info->qsize = 0;
322		info->ucounts = NULL;	/* set when all is ok */
323		info->msg_tree = RB_ROOT;
324		info->msg_tree_rightmost = NULL;
325		info->node_cache = NULL;
326		memset(&info->attr, 0, sizeof(info->attr));
327		info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
328					   ipc_ns->mq_msg_default);
329		info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
330					    ipc_ns->mq_msgsize_default);
331		if (attr) {
332			info->attr.mq_maxmsg = attr->mq_maxmsg;
333			info->attr.mq_msgsize = attr->mq_msgsize;
334		}
335		/*
336		 * We used to allocate a static array of pointers and account
337		 * the size of that array as well as one msg_msg struct per
338		 * possible message into the queue size. That's no longer
339		 * accurate as the queue is now an rbtree and will grow and
340		 * shrink depending on usage patterns.  We can, however, still
341		 * account one msg_msg struct per message, but the nodes are
342		 * allocated depending on priority usage, and most programs
343		 * only use one, or a handful, of priorities.  However, since
344		 * this is pinned memory, we need to assume worst case, so
345		 * that means the min(mq_maxmsg, max_priorities) * struct
346		 * posix_msg_tree_node.
347		 */
348
349		ret = -EINVAL;
350		if (info->attr.mq_maxmsg <= 0 || info->attr.mq_msgsize <= 0)
351			goto out_inode;
352		if (capable(CAP_SYS_RESOURCE)) {
353			if (info->attr.mq_maxmsg > HARD_MSGMAX ||
354			    info->attr.mq_msgsize > HARD_MSGSIZEMAX)
355				goto out_inode;
356		} else {
357			if (info->attr.mq_maxmsg > ipc_ns->mq_msg_max ||
358					info->attr.mq_msgsize > ipc_ns->mq_msgsize_max)
359				goto out_inode;
360		}
361		ret = -EOVERFLOW;
362		/* check for overflow */
363		if (info->attr.mq_msgsize > ULONG_MAX/info->attr.mq_maxmsg)
364			goto out_inode;
365		mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
366			min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
367			sizeof(struct posix_msg_tree_node);
368		mq_bytes = info->attr.mq_maxmsg * info->attr.mq_msgsize;
369		if (mq_bytes + mq_treesize < mq_bytes)
370			goto out_inode;
371		mq_bytes += mq_treesize;
372		info->ucounts = get_ucounts(current_ucounts());
373		if (info->ucounts) {
374			long msgqueue;
375
376			spin_lock(&mq_lock);
377			msgqueue = inc_rlimit_ucounts(info->ucounts, UCOUNT_RLIMIT_MSGQUEUE, mq_bytes);
378			if (msgqueue == LONG_MAX || msgqueue > rlimit(RLIMIT_MSGQUEUE)) {
379				dec_rlimit_ucounts(info->ucounts, UCOUNT_RLIMIT_MSGQUEUE, mq_bytes);
380				spin_unlock(&mq_lock);
381				put_ucounts(info->ucounts);
382				info->ucounts = NULL;
383				/* mqueue_evict_inode() releases info->messages */
384				ret = -EMFILE;
385				goto out_inode;
386			}
387			spin_unlock(&mq_lock);
388		}
389	} else if (S_ISDIR(mode)) {
390		inc_nlink(inode);
391		/* Some things misbehave if size == 0 on a directory */
392		inode->i_size = 2 * DIRENT_SIZE;
393		inode->i_op = &mqueue_dir_inode_operations;
394		inode->i_fop = &simple_dir_operations;
395	}
396
397	return inode;
398out_inode:
399	iput(inode);
400err:
401	return ERR_PTR(ret);
402}
403
404static int mqueue_fill_super(struct super_block *sb, struct fs_context *fc)
405{
406	struct inode *inode;
407	struct ipc_namespace *ns = sb->s_fs_info;
408
409	sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV;
410	sb->s_blocksize = PAGE_SIZE;
411	sb->s_blocksize_bits = PAGE_SHIFT;
412	sb->s_magic = MQUEUE_MAGIC;
413	sb->s_op = &mqueue_super_ops;
414
415	inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
416	if (IS_ERR(inode))
417		return PTR_ERR(inode);
418
419	sb->s_root = d_make_root(inode);
420	if (!sb->s_root)
421		return -ENOMEM;
422	return 0;
423}
424
425static int mqueue_get_tree(struct fs_context *fc)
426{
427	struct mqueue_fs_context *ctx = fc->fs_private;
428
429	/*
430	 * With a newly created ipc namespace, we don't need to do a search
431	 * for an ipc namespace match, but we still need to set s_fs_info.
432	 */
433	if (ctx->newns) {
434		fc->s_fs_info = ctx->ipc_ns;
435		return get_tree_nodev(fc, mqueue_fill_super);
436	}
437	return get_tree_keyed(fc, mqueue_fill_super, ctx->ipc_ns);
438}
439
440static void mqueue_fs_context_free(struct fs_context *fc)
441{
442	struct mqueue_fs_context *ctx = fc->fs_private;
443
444	put_ipc_ns(ctx->ipc_ns);
445	kfree(ctx);
446}
447
448static int mqueue_init_fs_context(struct fs_context *fc)
449{
450	struct mqueue_fs_context *ctx;
451
452	ctx = kzalloc(sizeof(struct mqueue_fs_context), GFP_KERNEL);
453	if (!ctx)
454		return -ENOMEM;
455
456	ctx->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
457	put_user_ns(fc->user_ns);
458	fc->user_ns = get_user_ns(ctx->ipc_ns->user_ns);
459	fc->fs_private = ctx;
460	fc->ops = &mqueue_fs_context_ops;
461	return 0;
462}
463
464/*
465 * mq_init_ns() is currently the only caller of mq_create_mount().
466 * So the ns parameter is always a newly created ipc namespace.
467 */
468static struct vfsmount *mq_create_mount(struct ipc_namespace *ns)
469{
470	struct mqueue_fs_context *ctx;
471	struct fs_context *fc;
472	struct vfsmount *mnt;
473
474	fc = fs_context_for_mount(&mqueue_fs_type, SB_KERNMOUNT);
475	if (IS_ERR(fc))
476		return ERR_CAST(fc);
477
478	ctx = fc->fs_private;
479	ctx->newns = true;
480	put_ipc_ns(ctx->ipc_ns);
481	ctx->ipc_ns = get_ipc_ns(ns);
482	put_user_ns(fc->user_ns);
483	fc->user_ns = get_user_ns(ctx->ipc_ns->user_ns);
484
485	mnt = fc_mount(fc);
486	put_fs_context(fc);
487	return mnt;
488}
489
490static void init_once(void *foo)
491{
492	struct mqueue_inode_info *p = foo;
493
494	inode_init_once(&p->vfs_inode);
495}
496
497static struct inode *mqueue_alloc_inode(struct super_block *sb)
498{
499	struct mqueue_inode_info *ei;
500
501	ei = alloc_inode_sb(sb, mqueue_inode_cachep, GFP_KERNEL);
502	if (!ei)
503		return NULL;
504	return &ei->vfs_inode;
505}
506
507static void mqueue_free_inode(struct inode *inode)
508{
509	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
510}
511
512static void mqueue_evict_inode(struct inode *inode)
513{
514	struct mqueue_inode_info *info;
515	struct ipc_namespace *ipc_ns;
516	struct msg_msg *msg, *nmsg;
517	LIST_HEAD(tmp_msg);
518
519	clear_inode(inode);
520
521	if (S_ISDIR(inode->i_mode))
522		return;
523
524	ipc_ns = get_ns_from_inode(inode);
525	info = MQUEUE_I(inode);
526	spin_lock(&info->lock);
527	while ((msg = msg_get(info)) != NULL)
528		list_add_tail(&msg->m_list, &tmp_msg);
529	kfree(info->node_cache);
530	spin_unlock(&info->lock);
531
532	list_for_each_entry_safe(msg, nmsg, &tmp_msg, m_list) {
533		list_del(&msg->m_list);
534		free_msg(msg);
535	}
536
537	if (info->ucounts) {
538		unsigned long mq_bytes, mq_treesize;
539
540		/* Total amount of bytes accounted for the mqueue */
541		mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
542			min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
543			sizeof(struct posix_msg_tree_node);
544
545		mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
546					  info->attr.mq_msgsize);
547
548		spin_lock(&mq_lock);
549		dec_rlimit_ucounts(info->ucounts, UCOUNT_RLIMIT_MSGQUEUE, mq_bytes);
550		/*
551		 * get_ns_from_inode() ensures that the
552		 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
553		 * to which we now hold a reference, or it is NULL.
554		 * We can't put it here under mq_lock, though.
555		 */
556		if (ipc_ns)
557			ipc_ns->mq_queues_count--;
558		spin_unlock(&mq_lock);
559		put_ucounts(info->ucounts);
560		info->ucounts = NULL;
561	}
562	if (ipc_ns)
563		put_ipc_ns(ipc_ns);
564}
565
566static int mqueue_create_attr(struct dentry *dentry, umode_t mode, void *arg)
567{
568	struct inode *dir = dentry->d_parent->d_inode;
569	struct inode *inode;
570	struct mq_attr *attr = arg;
571	int error;
572	struct ipc_namespace *ipc_ns;
573
574	spin_lock(&mq_lock);
575	ipc_ns = __get_ns_from_inode(dir);
576	if (!ipc_ns) {
577		error = -EACCES;
578		goto out_unlock;
579	}
580
581	if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
582	    !capable(CAP_SYS_RESOURCE)) {
583		error = -ENOSPC;
584		goto out_unlock;
585	}
586	ipc_ns->mq_queues_count++;
587	spin_unlock(&mq_lock);
588
589	inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
590	if (IS_ERR(inode)) {
591		error = PTR_ERR(inode);
592		spin_lock(&mq_lock);
593		ipc_ns->mq_queues_count--;
594		goto out_unlock;
595	}
596
597	put_ipc_ns(ipc_ns);
598	dir->i_size += DIRENT_SIZE;
599	dir->i_ctime = dir->i_mtime = dir->i_atime = current_time(dir);
600
601	d_instantiate(dentry, inode);
602	dget(dentry);
603	return 0;
604out_unlock:
605	spin_unlock(&mq_lock);
606	if (ipc_ns)
607		put_ipc_ns(ipc_ns);
608	return error;
609}
610
611static int mqueue_create(struct user_namespace *mnt_userns, struct inode *dir,
612			 struct dentry *dentry, umode_t mode, bool excl)
613{
614	return mqueue_create_attr(dentry, mode, NULL);
615}
616
617static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
618{
619	struct inode *inode = d_inode(dentry);
620
621	dir->i_ctime = dir->i_mtime = dir->i_atime = current_time(dir);
622	dir->i_size -= DIRENT_SIZE;
623	drop_nlink(inode);
624	dput(dentry);
625	return 0;
626}
627
628/*
629*	This is routine for system read from queue file.
630*	To avoid mess with doing here some sort of mq_receive we allow
631*	to read only queue size & notification info (the only values
632*	that are interesting from user point of view and aren't accessible
633*	through std routines)
634*/
635static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
636				size_t count, loff_t *off)
637{
638	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
639	char buffer[FILENT_SIZE];
640	ssize_t ret;
641
642	spin_lock(&info->lock);
643	snprintf(buffer, sizeof(buffer),
644			"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
645			info->qsize,
646			info->notify_owner ? info->notify.sigev_notify : 0,
647			(info->notify_owner &&
648			 info->notify.sigev_notify == SIGEV_SIGNAL) ?
649				info->notify.sigev_signo : 0,
650			pid_vnr(info->notify_owner));
651	spin_unlock(&info->lock);
652	buffer[sizeof(buffer)-1] = '\0';
653
654	ret = simple_read_from_buffer(u_data, count, off, buffer,
655				strlen(buffer));
656	if (ret <= 0)
657		return ret;
658
659	file_inode(filp)->i_atime = file_inode(filp)->i_ctime = current_time(file_inode(filp));
660	return ret;
661}
662
663static int mqueue_flush_file(struct file *filp, fl_owner_t id)
664{
665	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
666
667	spin_lock(&info->lock);
668	if (task_tgid(current) == info->notify_owner)
669		remove_notification(info);
670
671	spin_unlock(&info->lock);
672	return 0;
673}
674
675static __poll_t mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
676{
677	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
678	__poll_t retval = 0;
679
680	poll_wait(filp, &info->wait_q, poll_tab);
681
682	spin_lock(&info->lock);
683	if (info->attr.mq_curmsgs)
684		retval = EPOLLIN | EPOLLRDNORM;
685
686	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
687		retval |= EPOLLOUT | EPOLLWRNORM;
688	spin_unlock(&info->lock);
689
690	return retval;
691}
692
693/* Adds current to info->e_wait_q[sr] before element with smaller prio */
694static void wq_add(struct mqueue_inode_info *info, int sr,
695			struct ext_wait_queue *ewp)
696{
697	struct ext_wait_queue *walk;
698
699	list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
700		if (walk->task->prio <= current->prio) {
701			list_add_tail(&ewp->list, &walk->list);
702			return;
703		}
704	}
705	list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
706}
707
708/*
709 * Puts current task to sleep. Caller must hold queue lock. After return
710 * lock isn't held.
711 * sr: SEND or RECV
712 */
713static int wq_sleep(struct mqueue_inode_info *info, int sr,
714		    ktime_t *timeout, struct ext_wait_queue *ewp)
715	__releases(&info->lock)
716{
717	int retval;
718	signed long time;
719
720	wq_add(info, sr, ewp);
721
722	for (;;) {
723		/* memory barrier not required, we hold info->lock */
724		__set_current_state(TASK_INTERRUPTIBLE);
725
726		spin_unlock(&info->lock);
727		time = schedule_hrtimeout_range_clock(timeout, 0,
728			HRTIMER_MODE_ABS, CLOCK_REALTIME);
729
730		if (READ_ONCE(ewp->state) == STATE_READY) {
731			/* see MQ_BARRIER for purpose/pairing */
732			smp_acquire__after_ctrl_dep();
733			retval = 0;
734			goto out;
735		}
736		spin_lock(&info->lock);
737
738		/* we hold info->lock, so no memory barrier required */
739		if (READ_ONCE(ewp->state) == STATE_READY) {
740			retval = 0;
741			goto out_unlock;
742		}
743		if (signal_pending(current)) {
744			retval = -ERESTARTSYS;
745			break;
746		}
747		if (time == 0) {
748			retval = -ETIMEDOUT;
749			break;
750		}
751	}
752	list_del(&ewp->list);
753out_unlock:
754	spin_unlock(&info->lock);
755out:
756	return retval;
757}
758
759/*
760 * Returns waiting task that should be serviced first or NULL if none exists
761 */
762static struct ext_wait_queue *wq_get_first_waiter(
763		struct mqueue_inode_info *info, int sr)
764{
765	struct list_head *ptr;
766
767	ptr = info->e_wait_q[sr].list.prev;
768	if (ptr == &info->e_wait_q[sr].list)
769		return NULL;
770	return list_entry(ptr, struct ext_wait_queue, list);
771}
772
773
774static inline void set_cookie(struct sk_buff *skb, char code)
775{
776	((char *)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
777}
778
779/*
780 * The next function is only to split too long sys_mq_timedsend
781 */
782static void __do_notify(struct mqueue_inode_info *info)
783{
784	/* notification
785	 * invoked when there is registered process and there isn't process
786	 * waiting synchronously for message AND state of queue changed from
787	 * empty to not empty. Here we are sure that no one is waiting
788	 * synchronously. */
789	if (info->notify_owner &&
790	    info->attr.mq_curmsgs == 1) {
791		switch (info->notify.sigev_notify) {
792		case SIGEV_NONE:
793			break;
794		case SIGEV_SIGNAL: {
795			struct kernel_siginfo sig_i;
796			struct task_struct *task;
797
798			/* do_mq_notify() accepts sigev_signo == 0, why?? */
799			if (!info->notify.sigev_signo)
800				break;
801
802			clear_siginfo(&sig_i);
803			sig_i.si_signo = info->notify.sigev_signo;
804			sig_i.si_errno = 0;
805			sig_i.si_code = SI_MESGQ;
806			sig_i.si_value = info->notify.sigev_value;
807			rcu_read_lock();
808			/* map current pid/uid into info->owner's namespaces */
809			sig_i.si_pid = task_tgid_nr_ns(current,
810						ns_of_pid(info->notify_owner));
811			sig_i.si_uid = from_kuid_munged(info->notify_user_ns,
812						current_uid());
813			/*
814			 * We can't use kill_pid_info(), this signal should
815			 * bypass check_kill_permission(). It is from kernel
816			 * but si_fromuser() can't know this.
817			 * We do check the self_exec_id, to avoid sending
818			 * signals to programs that don't expect them.
819			 */
820			task = pid_task(info->notify_owner, PIDTYPE_TGID);
821			if (task && task->self_exec_id ==
822						info->notify_self_exec_id) {
823				do_send_sig_info(info->notify.sigev_signo,
824						&sig_i, task, PIDTYPE_TGID);
825			}
826			rcu_read_unlock();
827			break;
828		}
829		case SIGEV_THREAD:
830			set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
831			netlink_sendskb(info->notify_sock, info->notify_cookie);
832			break;
833		}
834		/* after notification unregisters process */
835		put_pid(info->notify_owner);
836		put_user_ns(info->notify_user_ns);
837		info->notify_owner = NULL;
838		info->notify_user_ns = NULL;
839	}
840	wake_up(&info->wait_q);
841}
842
843static int prepare_timeout(const struct __kernel_timespec __user *u_abs_timeout,
844			   struct timespec64 *ts)
845{
846	if (get_timespec64(ts, u_abs_timeout))
847		return -EFAULT;
848	if (!timespec64_valid(ts))
849		return -EINVAL;
850	return 0;
851}
852
853static void remove_notification(struct mqueue_inode_info *info)
854{
855	if (info->notify_owner != NULL &&
856	    info->notify.sigev_notify == SIGEV_THREAD) {
857		set_cookie(info->notify_cookie, NOTIFY_REMOVED);
858		netlink_sendskb(info->notify_sock, info->notify_cookie);
859	}
860	put_pid(info->notify_owner);
861	put_user_ns(info->notify_user_ns);
862	info->notify_owner = NULL;
863	info->notify_user_ns = NULL;
864}
865
866static int prepare_open(struct dentry *dentry, int oflag, int ro,
867			umode_t mode, struct filename *name,
868			struct mq_attr *attr)
869{
870	static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
871						  MAY_READ | MAY_WRITE };
872	int acc;
873
874	if (d_really_is_negative(dentry)) {
875		if (!(oflag & O_CREAT))
876			return -ENOENT;
877		if (ro)
878			return ro;
879		audit_inode_parent_hidden(name, dentry->d_parent);
880		return vfs_mkobj(dentry, mode & ~current_umask(),
881				  mqueue_create_attr, attr);
882	}
883	/* it already existed */
884	audit_inode(name, dentry, 0);
885	if ((oflag & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
886		return -EEXIST;
887	if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
888		return -EINVAL;
889	acc = oflag2acc[oflag & O_ACCMODE];
890	return inode_permission(&init_user_ns, d_inode(dentry), acc);
891}
892
893static int do_mq_open(const char __user *u_name, int oflag, umode_t mode,
894		      struct mq_attr *attr)
895{
896	struct vfsmount *mnt = current->nsproxy->ipc_ns->mq_mnt;
897	struct dentry *root = mnt->mnt_root;
898	struct filename *name;
899	struct path path;
900	int fd, error;
901	int ro;
902
903	audit_mq_open(oflag, mode, attr);
904
905	if (IS_ERR(name = getname(u_name)))
906		return PTR_ERR(name);
907
908	fd = get_unused_fd_flags(O_CLOEXEC);
909	if (fd < 0)
910		goto out_putname;
911
912	ro = mnt_want_write(mnt);	/* we'll drop it in any case */
913	inode_lock(d_inode(root));
914	path.dentry = lookup_one_len(name->name, root, strlen(name->name));
915	if (IS_ERR(path.dentry)) {
916		error = PTR_ERR(path.dentry);
917		goto out_putfd;
918	}
919	path.mnt = mntget(mnt);
920	error = prepare_open(path.dentry, oflag, ro, mode, name, attr);
921	if (!error) {
922		struct file *file = dentry_open(&path, oflag, current_cred());
923		if (!IS_ERR(file))
924			fd_install(fd, file);
925		else
926			error = PTR_ERR(file);
927	}
928	path_put(&path);
929out_putfd:
930	if (error) {
931		put_unused_fd(fd);
932		fd = error;
933	}
934	inode_unlock(d_inode(root));
935	if (!ro)
936		mnt_drop_write(mnt);
937out_putname:
938	putname(name);
939	return fd;
940}
941
942SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
943		struct mq_attr __user *, u_attr)
944{
945	struct mq_attr attr;
946	if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
947		return -EFAULT;
948
949	return do_mq_open(u_name, oflag, mode, u_attr ? &attr : NULL);
950}
951
952SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
953{
954	int err;
955	struct filename *name;
956	struct dentry *dentry;
957	struct inode *inode = NULL;
958	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
959	struct vfsmount *mnt = ipc_ns->mq_mnt;
960
961	name = getname(u_name);
962	if (IS_ERR(name))
963		return PTR_ERR(name);
964
965	audit_inode_parent_hidden(name, mnt->mnt_root);
966	err = mnt_want_write(mnt);
967	if (err)
968		goto out_name;
969	inode_lock_nested(d_inode(mnt->mnt_root), I_MUTEX_PARENT);
970	dentry = lookup_one_len(name->name, mnt->mnt_root,
971				strlen(name->name));
972	if (IS_ERR(dentry)) {
973		err = PTR_ERR(dentry);
974		goto out_unlock;
975	}
976
977	inode = d_inode(dentry);
978	if (!inode) {
979		err = -ENOENT;
980	} else {
981		ihold(inode);
982		err = vfs_unlink(&init_user_ns, d_inode(dentry->d_parent),
983				 dentry, NULL);
984	}
985	dput(dentry);
986
987out_unlock:
988	inode_unlock(d_inode(mnt->mnt_root));
989	if (inode)
990		iput(inode);
991	mnt_drop_write(mnt);
992out_name:
993	putname(name);
994
995	return err;
996}
997
998/* Pipelined send and receive functions.
999 *
1000 * If a receiver finds no waiting message, then it registers itself in the
1001 * list of waiting receivers. A sender checks that list before adding the new
1002 * message into the message array. If there is a waiting receiver, then it
1003 * bypasses the message array and directly hands the message over to the
1004 * receiver. The receiver accepts the message and returns without grabbing the
1005 * queue spinlock:
1006 *
1007 * - Set pointer to message.
1008 * - Queue the receiver task for later wakeup (without the info->lock).
1009 * - Update its state to STATE_READY. Now the receiver can continue.
1010 * - Wake up the process after the lock is dropped. Should the process wake up
1011 *   before this wakeup (due to a timeout or a signal) it will either see
1012 *   STATE_READY and continue or acquire the lock to check the state again.
1013 *
1014 * The same algorithm is used for senders.
1015 */
1016
1017static inline void __pipelined_op(struct wake_q_head *wake_q,
1018				  struct mqueue_inode_info *info,
1019				  struct ext_wait_queue *this)
1020{
1021	struct task_struct *task;
1022
1023	list_del(&this->list);
1024	task = get_task_struct(this->task);
1025
1026	/* see MQ_BARRIER for purpose/pairing */
1027	smp_store_release(&this->state, STATE_READY);
1028	wake_q_add_safe(wake_q, task);
1029}
1030
1031/* pipelined_send() - send a message directly to the task waiting in
1032 * sys_mq_timedreceive() (without inserting message into a queue).
1033 */
1034static inline void pipelined_send(struct wake_q_head *wake_q,
1035				  struct mqueue_inode_info *info,
1036				  struct msg_msg *message,
1037				  struct ext_wait_queue *receiver)
1038{
1039	receiver->msg = message;
1040	__pipelined_op(wake_q, info, receiver);
1041}
1042
1043/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
1044 * gets its message and put to the queue (we have one free place for sure). */
1045static inline void pipelined_receive(struct wake_q_head *wake_q,
1046				     struct mqueue_inode_info *info)
1047{
1048	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
1049
1050	if (!sender) {
1051		/* for poll */
1052		wake_up_interruptible(&info->wait_q);
1053		return;
1054	}
1055	if (msg_insert(sender->msg, info))
1056		return;
1057
1058	__pipelined_op(wake_q, info, sender);
1059}
1060
1061static int do_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
1062		size_t msg_len, unsigned int msg_prio,
1063		struct timespec64 *ts)
1064{
1065	struct fd f;
1066	struct inode *inode;
1067	struct ext_wait_queue wait;
1068	struct ext_wait_queue *receiver;
1069	struct msg_msg *msg_ptr;
1070	struct mqueue_inode_info *info;
1071	ktime_t expires, *timeout = NULL;
1072	struct posix_msg_tree_node *new_leaf = NULL;
1073	int ret = 0;
1074	DEFINE_WAKE_Q(wake_q);
1075
1076	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
1077		return -EINVAL;
1078
1079	if (ts) {
1080		expires = timespec64_to_ktime(*ts);
1081		timeout = &expires;
1082	}
1083
1084	audit_mq_sendrecv(mqdes, msg_len, msg_prio, ts);
1085
1086	f = fdget(mqdes);
1087	if (unlikely(!f.file)) {
1088		ret = -EBADF;
1089		goto out;
1090	}
1091
1092	inode = file_inode(f.file);
1093	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1094		ret = -EBADF;
1095		goto out_fput;
1096	}
1097	info = MQUEUE_I(inode);
1098	audit_file(f.file);
1099
1100	if (unlikely(!(f.file->f_mode & FMODE_WRITE))) {
1101		ret = -EBADF;
1102		goto out_fput;
1103	}
1104
1105	if (unlikely(msg_len > info->attr.mq_msgsize)) {
1106		ret = -EMSGSIZE;
1107		goto out_fput;
1108	}
1109
1110	/* First try to allocate memory, before doing anything with
1111	 * existing queues. */
1112	msg_ptr = load_msg(u_msg_ptr, msg_len);
1113	if (IS_ERR(msg_ptr)) {
1114		ret = PTR_ERR(msg_ptr);
1115		goto out_fput;
1116	}
1117	msg_ptr->m_ts = msg_len;
1118	msg_ptr->m_type = msg_prio;
1119
1120	/*
1121	 * msg_insert really wants us to have a valid, spare node struct so
1122	 * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1123	 * fall back to that if necessary.
1124	 */
1125	if (!info->node_cache)
1126		new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1127
1128	spin_lock(&info->lock);
1129
1130	if (!info->node_cache && new_leaf) {
1131		/* Save our speculative allocation into the cache */
1132		INIT_LIST_HEAD(&new_leaf->msg_list);
1133		info->node_cache = new_leaf;
1134		new_leaf = NULL;
1135	} else {
1136		kfree(new_leaf);
1137	}
1138
1139	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
1140		if (f.file->f_flags & O_NONBLOCK) {
1141			ret = -EAGAIN;
1142		} else {
1143			wait.task = current;
1144			wait.msg = (void *) msg_ptr;
1145
1146			/* memory barrier not required, we hold info->lock */
1147			WRITE_ONCE(wait.state, STATE_NONE);
1148			ret = wq_sleep(info, SEND, timeout, &wait);
1149			/*
1150			 * wq_sleep must be called with info->lock held, and
1151			 * returns with the lock released
1152			 */
1153			goto out_free;
1154		}
1155	} else {
1156		receiver = wq_get_first_waiter(info, RECV);
1157		if (receiver) {
1158			pipelined_send(&wake_q, info, msg_ptr, receiver);
1159		} else {
1160			/* adds message to the queue */
1161			ret = msg_insert(msg_ptr, info);
1162			if (ret)
1163				goto out_unlock;
1164			__do_notify(info);
1165		}
1166		inode->i_atime = inode->i_mtime = inode->i_ctime =
1167				current_time(inode);
1168	}
1169out_unlock:
1170	spin_unlock(&info->lock);
1171	wake_up_q(&wake_q);
1172out_free:
1173	if (ret)
1174		free_msg(msg_ptr);
1175out_fput:
1176	fdput(f);
1177out:
1178	return ret;
1179}
1180
1181static int do_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
1182		size_t msg_len, unsigned int __user *u_msg_prio,
1183		struct timespec64 *ts)
1184{
1185	ssize_t ret;
1186	struct msg_msg *msg_ptr;
1187	struct fd f;
1188	struct inode *inode;
1189	struct mqueue_inode_info *info;
1190	struct ext_wait_queue wait;
1191	ktime_t expires, *timeout = NULL;
1192	struct posix_msg_tree_node *new_leaf = NULL;
1193
1194	if (ts) {
1195		expires = timespec64_to_ktime(*ts);
1196		timeout = &expires;
1197	}
1198
1199	audit_mq_sendrecv(mqdes, msg_len, 0, ts);
1200
1201	f = fdget(mqdes);
1202	if (unlikely(!f.file)) {
1203		ret = -EBADF;
1204		goto out;
1205	}
1206
1207	inode = file_inode(f.file);
1208	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1209		ret = -EBADF;
1210		goto out_fput;
1211	}
1212	info = MQUEUE_I(inode);
1213	audit_file(f.file);
1214
1215	if (unlikely(!(f.file->f_mode & FMODE_READ))) {
1216		ret = -EBADF;
1217		goto out_fput;
1218	}
1219
1220	/* checks if buffer is big enough */
1221	if (unlikely(msg_len < info->attr.mq_msgsize)) {
1222		ret = -EMSGSIZE;
1223		goto out_fput;
1224	}
1225
1226	/*
1227	 * msg_insert really wants us to have a valid, spare node struct so
1228	 * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1229	 * fall back to that if necessary.
1230	 */
1231	if (!info->node_cache)
1232		new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1233
1234	spin_lock(&info->lock);
1235
1236	if (!info->node_cache && new_leaf) {
1237		/* Save our speculative allocation into the cache */
1238		INIT_LIST_HEAD(&new_leaf->msg_list);
1239		info->node_cache = new_leaf;
1240	} else {
1241		kfree(new_leaf);
1242	}
1243
1244	if (info->attr.mq_curmsgs == 0) {
1245		if (f.file->f_flags & O_NONBLOCK) {
1246			spin_unlock(&info->lock);
1247			ret = -EAGAIN;
1248		} else {
1249			wait.task = current;
1250
1251			/* memory barrier not required, we hold info->lock */
1252			WRITE_ONCE(wait.state, STATE_NONE);
1253			ret = wq_sleep(info, RECV, timeout, &wait);
1254			msg_ptr = wait.msg;
1255		}
1256	} else {
1257		DEFINE_WAKE_Q(wake_q);
1258
1259		msg_ptr = msg_get(info);
1260
1261		inode->i_atime = inode->i_mtime = inode->i_ctime =
1262				current_time(inode);
1263
1264		/* There is now free space in queue. */
1265		pipelined_receive(&wake_q, info);
1266		spin_unlock(&info->lock);
1267		wake_up_q(&wake_q);
1268		ret = 0;
1269	}
1270	if (ret == 0) {
1271		ret = msg_ptr->m_ts;
1272
1273		if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1274			store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1275			ret = -EFAULT;
1276		}
1277		free_msg(msg_ptr);
1278	}
1279out_fput:
1280	fdput(f);
1281out:
1282	return ret;
1283}
1284
1285SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
1286		size_t, msg_len, unsigned int, msg_prio,
1287		const struct __kernel_timespec __user *, u_abs_timeout)
1288{
1289	struct timespec64 ts, *p = NULL;
1290	if (u_abs_timeout) {
1291		int res = prepare_timeout(u_abs_timeout, &ts);
1292		if (res)
1293			return res;
1294		p = &ts;
1295	}
1296	return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p);
1297}
1298
1299SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
1300		size_t, msg_len, unsigned int __user *, u_msg_prio,
1301		const struct __kernel_timespec __user *, u_abs_timeout)
1302{
1303	struct timespec64 ts, *p = NULL;
1304	if (u_abs_timeout) {
1305		int res = prepare_timeout(u_abs_timeout, &ts);
1306		if (res)
1307			return res;
1308		p = &ts;
1309	}
1310	return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p);
1311}
1312
1313/*
1314 * Notes: the case when user wants us to deregister (with NULL as pointer)
1315 * and he isn't currently owner of notification, will be silently discarded.
1316 * It isn't explicitly defined in the POSIX.
1317 */
1318static int do_mq_notify(mqd_t mqdes, const struct sigevent *notification)
1319{
1320	int ret;
1321	struct fd f;
1322	struct sock *sock;
1323	struct inode *inode;
1324	struct mqueue_inode_info *info;
1325	struct sk_buff *nc;
1326
1327	audit_mq_notify(mqdes, notification);
1328
1329	nc = NULL;
1330	sock = NULL;
1331	if (notification != NULL) {
1332		if (unlikely(notification->sigev_notify != SIGEV_NONE &&
1333			     notification->sigev_notify != SIGEV_SIGNAL &&
1334			     notification->sigev_notify != SIGEV_THREAD))
1335			return -EINVAL;
1336		if (notification->sigev_notify == SIGEV_SIGNAL &&
1337			!valid_signal(notification->sigev_signo)) {
1338			return -EINVAL;
1339		}
1340		if (notification->sigev_notify == SIGEV_THREAD) {
1341			long timeo;
1342
1343			/* create the notify skb */
1344			nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1345			if (!nc)
1346				return -ENOMEM;
1347
1348			if (copy_from_user(nc->data,
1349					notification->sigev_value.sival_ptr,
1350					NOTIFY_COOKIE_LEN)) {
1351				ret = -EFAULT;
1352				goto free_skb;
1353			}
1354
1355			/* TODO: add a header? */
1356			skb_put(nc, NOTIFY_COOKIE_LEN);
1357			/* and attach it to the socket */
1358retry:
1359			f = fdget(notification->sigev_signo);
1360			if (!f.file) {
1361				ret = -EBADF;
1362				goto out;
1363			}
1364			sock = netlink_getsockbyfilp(f.file);
1365			fdput(f);
1366			if (IS_ERR(sock)) {
1367				ret = PTR_ERR(sock);
1368				goto free_skb;
1369			}
1370
1371			timeo = MAX_SCHEDULE_TIMEOUT;
1372			ret = netlink_attachskb(sock, nc, &timeo, NULL);
1373			if (ret == 1) {
1374				sock = NULL;
1375				goto retry;
1376			}
1377			if (ret)
1378				return ret;
1379		}
1380	}
1381
1382	f = fdget(mqdes);
1383	if (!f.file) {
1384		ret = -EBADF;
1385		goto out;
1386	}
1387
1388	inode = file_inode(f.file);
1389	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1390		ret = -EBADF;
1391		goto out_fput;
1392	}
1393	info = MQUEUE_I(inode);
1394
1395	ret = 0;
1396	spin_lock(&info->lock);
1397	if (notification == NULL) {
1398		if (info->notify_owner == task_tgid(current)) {
1399			remove_notification(info);
1400			inode->i_atime = inode->i_ctime = current_time(inode);
1401		}
1402	} else if (info->notify_owner != NULL) {
1403		ret = -EBUSY;
1404	} else {
1405		switch (notification->sigev_notify) {
1406		case SIGEV_NONE:
1407			info->notify.sigev_notify = SIGEV_NONE;
1408			break;
1409		case SIGEV_THREAD:
1410			info->notify_sock = sock;
1411			info->notify_cookie = nc;
1412			sock = NULL;
1413			nc = NULL;
1414			info->notify.sigev_notify = SIGEV_THREAD;
1415			break;
1416		case SIGEV_SIGNAL:
1417			info->notify.sigev_signo = notification->sigev_signo;
1418			info->notify.sigev_value = notification->sigev_value;
1419			info->notify.sigev_notify = SIGEV_SIGNAL;
1420			info->notify_self_exec_id = current->self_exec_id;
1421			break;
1422		}
1423
1424		info->notify_owner = get_pid(task_tgid(current));
1425		info->notify_user_ns = get_user_ns(current_user_ns());
1426		inode->i_atime = inode->i_ctime = current_time(inode);
1427	}
1428	spin_unlock(&info->lock);
1429out_fput:
1430	fdput(f);
1431out:
1432	if (sock)
1433		netlink_detachskb(sock, nc);
1434	else
1435free_skb:
1436		dev_kfree_skb(nc);
1437
1438	return ret;
1439}
1440
1441SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1442		const struct sigevent __user *, u_notification)
1443{
1444	struct sigevent n, *p = NULL;
1445	if (u_notification) {
1446		if (copy_from_user(&n, u_notification, sizeof(struct sigevent)))
1447			return -EFAULT;
1448		p = &n;
1449	}
1450	return do_mq_notify(mqdes, p);
1451}
1452
1453static int do_mq_getsetattr(int mqdes, struct mq_attr *new, struct mq_attr *old)
1454{
1455	struct fd f;
1456	struct inode *inode;
1457	struct mqueue_inode_info *info;
1458
1459	if (new && (new->mq_flags & (~O_NONBLOCK)))
1460		return -EINVAL;
1461
1462	f = fdget(mqdes);
1463	if (!f.file)
1464		return -EBADF;
1465
1466	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1467		fdput(f);
1468		return -EBADF;
1469	}
1470
1471	inode = file_inode(f.file);
1472	info = MQUEUE_I(inode);
1473
1474	spin_lock(&info->lock);
1475
1476	if (old) {
1477		*old = info->attr;
1478		old->mq_flags = f.file->f_flags & O_NONBLOCK;
1479	}
1480	if (new) {
1481		audit_mq_getsetattr(mqdes, new);
1482		spin_lock(&f.file->f_lock);
1483		if (new->mq_flags & O_NONBLOCK)
1484			f.file->f_flags |= O_NONBLOCK;
1485		else
1486			f.file->f_flags &= ~O_NONBLOCK;
1487		spin_unlock(&f.file->f_lock);
1488
1489		inode->i_atime = inode->i_ctime = current_time(inode);
1490	}
1491
1492	spin_unlock(&info->lock);
1493	fdput(f);
1494	return 0;
1495}
1496
1497SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1498		const struct mq_attr __user *, u_mqstat,
1499		struct mq_attr __user *, u_omqstat)
1500{
1501	int ret;
1502	struct mq_attr mqstat, omqstat;
1503	struct mq_attr *new = NULL, *old = NULL;
1504
1505	if (u_mqstat) {
1506		new = &mqstat;
1507		if (copy_from_user(new, u_mqstat, sizeof(struct mq_attr)))
1508			return -EFAULT;
1509	}
1510	if (u_omqstat)
1511		old = &omqstat;
1512
1513	ret = do_mq_getsetattr(mqdes, new, old);
1514	if (ret || !old)
1515		return ret;
1516
1517	if (copy_to_user(u_omqstat, old, sizeof(struct mq_attr)))
1518		return -EFAULT;
1519	return 0;
1520}
1521
1522#ifdef CONFIG_COMPAT
1523
1524struct compat_mq_attr {
1525	compat_long_t mq_flags;      /* message queue flags		     */
1526	compat_long_t mq_maxmsg;     /* maximum number of messages	     */
1527	compat_long_t mq_msgsize;    /* maximum message size		     */
1528	compat_long_t mq_curmsgs;    /* number of messages currently queued  */
1529	compat_long_t __reserved[4]; /* ignored for input, zeroed for output */
1530};
1531
1532static inline int get_compat_mq_attr(struct mq_attr *attr,
1533			const struct compat_mq_attr __user *uattr)
1534{
1535	struct compat_mq_attr v;
1536
1537	if (copy_from_user(&v, uattr, sizeof(*uattr)))
1538		return -EFAULT;
1539
1540	memset(attr, 0, sizeof(*attr));
1541	attr->mq_flags = v.mq_flags;
1542	attr->mq_maxmsg = v.mq_maxmsg;
1543	attr->mq_msgsize = v.mq_msgsize;
1544	attr->mq_curmsgs = v.mq_curmsgs;
1545	return 0;
1546}
1547
1548static inline int put_compat_mq_attr(const struct mq_attr *attr,
1549			struct compat_mq_attr __user *uattr)
1550{
1551	struct compat_mq_attr v;
1552
1553	memset(&v, 0, sizeof(v));
1554	v.mq_flags = attr->mq_flags;
1555	v.mq_maxmsg = attr->mq_maxmsg;
1556	v.mq_msgsize = attr->mq_msgsize;
1557	v.mq_curmsgs = attr->mq_curmsgs;
1558	if (copy_to_user(uattr, &v, sizeof(*uattr)))
1559		return -EFAULT;
1560	return 0;
1561}
1562
1563COMPAT_SYSCALL_DEFINE4(mq_open, const char __user *, u_name,
1564		       int, oflag, compat_mode_t, mode,
1565		       struct compat_mq_attr __user *, u_attr)
1566{
1567	struct mq_attr attr, *p = NULL;
1568	if (u_attr && oflag & O_CREAT) {
1569		p = &attr;
1570		if (get_compat_mq_attr(&attr, u_attr))
1571			return -EFAULT;
1572	}
1573	return do_mq_open(u_name, oflag, mode, p);
1574}
1575
1576COMPAT_SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1577		       const struct compat_sigevent __user *, u_notification)
1578{
1579	struct sigevent n, *p = NULL;
1580	if (u_notification) {
1581		if (get_compat_sigevent(&n, u_notification))
1582			return -EFAULT;
1583		if (n.sigev_notify == SIGEV_THREAD)
1584			n.sigev_value.sival_ptr = compat_ptr(n.sigev_value.sival_int);
1585		p = &n;
1586	}
1587	return do_mq_notify(mqdes, p);
1588}
1589
1590COMPAT_SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1591		       const struct compat_mq_attr __user *, u_mqstat,
1592		       struct compat_mq_attr __user *, u_omqstat)
1593{
1594	int ret;
1595	struct mq_attr mqstat, omqstat;
1596	struct mq_attr *new = NULL, *old = NULL;
1597
1598	if (u_mqstat) {
1599		new = &mqstat;
1600		if (get_compat_mq_attr(new, u_mqstat))
1601			return -EFAULT;
1602	}
1603	if (u_omqstat)
1604		old = &omqstat;
1605
1606	ret = do_mq_getsetattr(mqdes, new, old);
1607	if (ret || !old)
1608		return ret;
1609
1610	if (put_compat_mq_attr(old, u_omqstat))
1611		return -EFAULT;
1612	return 0;
1613}
1614#endif
1615
1616#ifdef CONFIG_COMPAT_32BIT_TIME
1617static int compat_prepare_timeout(const struct old_timespec32 __user *p,
1618				   struct timespec64 *ts)
1619{
1620	if (get_old_timespec32(ts, p))
1621		return -EFAULT;
1622	if (!timespec64_valid(ts))
1623		return -EINVAL;
1624	return 0;
1625}
1626
1627SYSCALL_DEFINE5(mq_timedsend_time32, mqd_t, mqdes,
1628		const char __user *, u_msg_ptr,
1629		unsigned int, msg_len, unsigned int, msg_prio,
1630		const struct old_timespec32 __user *, u_abs_timeout)
1631{
1632	struct timespec64 ts, *p = NULL;
1633	if (u_abs_timeout) {
1634		int res = compat_prepare_timeout(u_abs_timeout, &ts);
1635		if (res)
1636			return res;
1637		p = &ts;
1638	}
1639	return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p);
1640}
1641
1642SYSCALL_DEFINE5(mq_timedreceive_time32, mqd_t, mqdes,
1643		char __user *, u_msg_ptr,
1644		unsigned int, msg_len, unsigned int __user *, u_msg_prio,
1645		const struct old_timespec32 __user *, u_abs_timeout)
1646{
1647	struct timespec64 ts, *p = NULL;
1648	if (u_abs_timeout) {
1649		int res = compat_prepare_timeout(u_abs_timeout, &ts);
1650		if (res)
1651			return res;
1652		p = &ts;
1653	}
1654	return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p);
1655}
1656#endif
1657
1658static const struct inode_operations mqueue_dir_inode_operations = {
1659	.lookup = simple_lookup,
1660	.create = mqueue_create,
1661	.unlink = mqueue_unlink,
1662};
1663
1664static const struct file_operations mqueue_file_operations = {
1665	.flush = mqueue_flush_file,
1666	.poll = mqueue_poll_file,
1667	.read = mqueue_read_file,
1668	.llseek = default_llseek,
1669};
1670
1671static const struct super_operations mqueue_super_ops = {
1672	.alloc_inode = mqueue_alloc_inode,
1673	.free_inode = mqueue_free_inode,
1674	.evict_inode = mqueue_evict_inode,
1675	.statfs = simple_statfs,
1676};
1677
1678static const struct fs_context_operations mqueue_fs_context_ops = {
1679	.free		= mqueue_fs_context_free,
1680	.get_tree	= mqueue_get_tree,
1681};
1682
1683static struct file_system_type mqueue_fs_type = {
1684	.name			= "mqueue",
1685	.init_fs_context	= mqueue_init_fs_context,
1686	.kill_sb		= kill_litter_super,
1687	.fs_flags		= FS_USERNS_MOUNT,
1688};
1689
1690int mq_init_ns(struct ipc_namespace *ns)
1691{
1692	struct vfsmount *m;
1693
1694	ns->mq_queues_count  = 0;
1695	ns->mq_queues_max    = DFLT_QUEUESMAX;
1696	ns->mq_msg_max       = DFLT_MSGMAX;
1697	ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1698	ns->mq_msg_default   = DFLT_MSG;
1699	ns->mq_msgsize_default  = DFLT_MSGSIZE;
1700
1701	m = mq_create_mount(ns);
1702	if (IS_ERR(m))
1703		return PTR_ERR(m);
1704	ns->mq_mnt = m;
1705	return 0;
1706}
1707
1708void mq_clear_sbinfo(struct ipc_namespace *ns)
1709{
1710	ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1711}
1712
1713void mq_put_mnt(struct ipc_namespace *ns)
1714{
1715	kern_unmount(ns->mq_mnt);
1716}
1717
1718static int __init init_mqueue_fs(void)
1719{
1720	int error;
1721
1722	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1723				sizeof(struct mqueue_inode_info), 0,
1724				SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT, init_once);
1725	if (mqueue_inode_cachep == NULL)
1726		return -ENOMEM;
1727
1728	if (!setup_mq_sysctls(&init_ipc_ns)) {
1729		pr_warn("sysctl registration failed\n");
1730		return -ENOMEM;
1731	}
1732
1733	error = register_filesystem(&mqueue_fs_type);
1734	if (error)
1735		goto out_sysctl;
1736
1737	spin_lock_init(&mq_lock);
1738
1739	error = mq_init_ns(&init_ipc_ns);
1740	if (error)
1741		goto out_filesystem;
1742
1743	return 0;
1744
1745out_filesystem:
1746	unregister_filesystem(&mqueue_fs_type);
1747out_sysctl:
1748	kmem_cache_destroy(mqueue_inode_cachep);
1749	return error;
1750}
1751
1752device_initcall(init_mqueue_fs);
1753