1	/*
2	* POSIX message queues filesystem for Linux.
3	*
4	* Copyright (C) 2003,2004 Krzysztof Benedyczak (golbi@mat.uni.torun.pl)
5	* Michal Wronski (michal.wronski@gmail.com)
6	*
7	* Spinlocks: Mohamed Abbas (abbas.mohamed@intel.com)
8	* Lockless receive & send, fd based notify:
9	* Manfred Spraul (manfred@colorfullife.com)
10	*
11	* Audit: George Wilson (ltcgcw@us.ibm.com)
12	*
13	* This file is released under the GPL.
14	*/
15
16	#include <linux/capability.h>
17	#include <linux/init.h>
18	#include <linux/pagemap.h>
19	#include <linux/file.h>
20	#include <linux/mount.h>
21	#include <linux/fs_context.h>
22	#include <linux/namei.h>
23	#include <linux/sysctl.h>
24	#include <linux/poll.h>
25	#include <linux/mqueue.h>
26	#include <linux/msg.h>
27	#include <linux/skbuff.h>
28	#include <linux/vmalloc.h>
29	#include <linux/netlink.h>
30	#include <linux/syscalls.h>
31	#include <linux/audit.h>
32	#include <linux/signal.h>
33	#include <linux/mutex.h>
34	#include <linux/nsproxy.h>
35	#include <linux/pid.h>
36	#include <linux/ipc_namespace.h>
37	#include <linux/user_namespace.h>
38	#include <linux/slab.h>
39	#include <linux/sched/wake_q.h>
40	#include <linux/sched/signal.h>
41	#include <linux/sched/user.h>
42
43	#include <net/sock.h>
44	#include "util.h"
45
46	struct mqueue_fs_context {
47	struct ipc_namespace *ipc_ns;
48	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
61	struct 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
127	struct 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
134	struct 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
158	static struct file_system_type mqueue_fs_type;
159	static const struct inode_operations mqueue_dir_inode_operations;
160	static const struct file_operations mqueue_file_operations;
161	static const struct super_operations mqueue_super_ops;
162	static const struct fs_context_operations mqueue_fs_context_ops;
163	static void remove_notification(struct mqueue_inode_info *info);
164
165	static struct kmem_cache *mqueue_inode_cachep;
166
167	static 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	*/
175	static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
176	{
177	return get_ipc_ns(ns: inode->i_sb->s_fs_info);
178	}
179
180	static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
181	{
182	struct ipc_namespace *ns;
183
184	spin_lock(lock: &mq_lock);
185	ns = __get_ns_from_inode(inode);
186	spin_unlock(lock: &mq_lock);
187	return ns;
188	}
189
190	/* Auxiliary functions to manipulate messages' list */
191	static 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(size: sizeof(*leaf), GFP_ATOMIC);
215	if (!leaf)
216	return -ENOMEM;
217	INIT_LIST_HEAD(list: &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(node: &leaf->rb_node, parent, rb_link: p);
225	rb_insert_color(&leaf->rb_node, &info->msg_tree);
226	insert_msg:
227	info->attr.mq_curmsgs++;
228	info->qsize += msg->m_ts;
229	list_add_tail(new: &msg->m_list, head: &leaf->msg_list);
230	return 0;
231	}
232
233	static 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(objp: leaf);
244	else
245	info->node_cache = leaf;
246	}
247
248	static 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
254	try_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(entry: &msg->m_list);
281	if (list_empty(head: &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
290	static 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(list: &info->e_wait_q[0].list);
318	INIT_LIST_HEAD(list: &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(s: &info->attr, c: 0, n: 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(lock: &mq_lock);
377	msgqueue = inc_rlimit_ucounts(ucounts: info->ucounts, type: UCOUNT_RLIMIT_MSGQUEUE, v: mq_bytes);
378	if (msgqueue == LONG_MAX || msgqueue > rlimit(RLIMIT_MSGQUEUE)) {
379	dec_rlimit_ucounts(ucounts: info->ucounts, type: UCOUNT_RLIMIT_MSGQUEUE, v: mq_bytes);
380	spin_unlock(lock: &mq_lock);
381	put_ucounts(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(lock: &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;
398	out_inode:
399	iput(inode);
400	err:
401	return ERR_PTR(error: ret);
402	}
403
404	static 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, ipc_ns: ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
416	if (IS_ERR(ptr: inode))
417	return PTR_ERR(ptr: inode);
418
419	sb->s_root = d_make_root(inode);
420	if (!sb->s_root)
421	return -ENOMEM;
422	return 0;
423	}
424
425	static 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, fill_super: mqueue_fill_super);
436	}
437	return get_tree_keyed(fc, fill_super: mqueue_fill_super, key: ctx->ipc_ns);
438	}
439
440	static void mqueue_fs_context_free(struct fs_context *fc)
441	{
442	struct mqueue_fs_context *ctx = fc->fs_private;
443
444	put_ipc_ns(ns: ctx->ipc_ns);
445	kfree(objp: ctx);
446	}
447
448	static int mqueue_init_fs_context(struct fs_context *fc)
449	{
450	struct mqueue_fs_context *ctx;
451
452	ctx = kzalloc(size: 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(ns: fc->user_ns);
458	fc->user_ns = get_user_ns(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	*/
468	static 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(fs_type: &mqueue_fs_type, SB_KERNMOUNT);
475	if (IS_ERR(ptr: fc))
476	return ERR_CAST(ptr: fc);
477
478	ctx = fc->fs_private;
479	ctx->newns = true;
480	put_ipc_ns(ns: ctx->ipc_ns);
481	ctx->ipc_ns = get_ipc_ns(ns);
482	put_user_ns(ns: fc->user_ns);
483	fc->user_ns = get_user_ns(ns: ctx->ipc_ns->user_ns);
484
485	mnt = fc_mount(fc);
486	put_fs_context(fc);
487	return mnt;
488	}
489
490	static void init_once(void *foo)
491	{
492	struct mqueue_inode_info *p = foo;
493
494	inode_init_once(&p->vfs_inode);
495	}
496
497	static struct inode *mqueue_alloc_inode(struct super_block *sb)
498	{
499	struct mqueue_inode_info *ei;
500
501	ei = alloc_inode_sb(sb, cache: mqueue_inode_cachep, GFP_KERNEL);
502	if (!ei)
503	return NULL;
504	return &ei->vfs_inode;
505	}
506
507	static void mqueue_free_inode(struct inode *inode)
508	{
509	kmem_cache_free(s: mqueue_inode_cachep, objp: MQUEUE_I(inode));
510	}
511
512	static 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(lock: &info->lock);
527	while ((msg = msg_get(info)) != NULL)
528	list_add_tail(new: &msg->m_list, head: &tmp_msg);
529	kfree(objp: info->node_cache);
530	spin_unlock(lock: &info->lock);
531
532	list_for_each_entry_safe(msg, nmsg, &tmp_msg, m_list) {
533	list_del(entry: &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(lock: &mq_lock);
549	dec_rlimit_ucounts(ucounts: info->ucounts, type: UCOUNT_RLIMIT_MSGQUEUE, v: 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(lock: &mq_lock);
559	put_ucounts(ucounts: info->ucounts);
560	info->ucounts = NULL;
561	}
562	if (ipc_ns)
563	put_ipc_ns(ns: ipc_ns);
564	}
565
566	static 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(lock: &mq_lock);
575	ipc_ns = __get_ns_from_inode(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(lock: &mq_lock);
588
589	inode = mqueue_get_inode(sb: dir->i_sb, ipc_ns, mode, attr);
590	if (IS_ERR(ptr: inode)) {
591	error = PTR_ERR(ptr: inode);
592	spin_lock(lock: &mq_lock);
593	ipc_ns->mq_queues_count--;
594	goto out_unlock;
595	}
596
597	put_ipc_ns(ns: ipc_ns);
598	dir->i_size += DIRENT_SIZE;
599	dir->i_ctime = dir->i_mtime = dir->i_atime = current_time(inode: dir);
600
601	d_instantiate(dentry, inode);
602	dget(dentry);
603	return 0;
604	out_unlock:
605	spin_unlock(lock: &mq_lock);
606	if (ipc_ns)
607	put_ipc_ns(ns: ipc_ns);
608	return error;
609	}
610
611	static int mqueue_create(struct mnt_idmap *idmap, struct inode *dir,
612	struct dentry *dentry, umode_t mode, bool excl)
613	{
614	return mqueue_create_attr(dentry, mode, NULL);
615	}
616
617	static 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(inode: 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	*/
635	static 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(inode: file_inode(f: filp));
639	char buffer[FILENT_SIZE];
640	ssize_t ret;
641
642	spin_lock(lock: &info->lock);
643	snprintf(buf: buffer, size: sizeof(buffer),
644	fmt: "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(pid: info->notify_owner));
651	spin_unlock(lock: &info->lock);
652	buffer[sizeof(buffer)-1] = '\0';
653
654	ret = simple_read_from_buffer(to: u_data, count, ppos: off, from: buffer,
655	available: strlen(buffer));
656	if (ret <= 0)
657	return ret;
658
659	file_inode(f: filp)->i_atime = file_inode(f: filp)->i_ctime = current_time(inode: file_inode(f: filp));
660	return ret;
661	}
662
663	static int mqueue_flush_file(struct file *filp, fl_owner_t id)
664	{
665	struct mqueue_inode_info *info = MQUEUE_I(inode: file_inode(f: filp));
666
667	spin_lock(lock: &info->lock);
668	if (task_tgid(current) == info->notify_owner)
669	remove_notification(info);
670
671	spin_unlock(lock: &info->lock);
672	return 0;
673	}
674
675	static __poll_t mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
676	{
677	struct mqueue_inode_info *info = MQUEUE_I(inode: file_inode(f: filp));
678	__poll_t retval = 0;
679
680	poll_wait(filp, wait_address: &info->wait_q, p: poll_tab);
681
682	spin_lock(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(lock: &info->lock);
689
690	return retval;
691	}
692
693	/* Adds current to info->e_wait_q[sr] before element with smaller prio */
694	static 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(new: &ewp->list, head: &walk->list);
702	return;
703	}
704	}
705	list_add_tail(new: &ewp->list, head: &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	*/
713	static 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(lock: &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(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(entry: &ewp->list);
753	out_unlock:
754	spin_unlock(lock: &info->lock);
755	out:
756	return retval;
757	}
758
759	/*
760	* Returns waiting task that should be serviced first or NULL if none exists
761	*/
762	static 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
774	static 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	*/
782	static 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(info: &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: ns_of_pid(pid: info->notify_owner));
811	sig_i.si_uid = from_kuid_munged(to: 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(pid: info->notify_owner, PIDTYPE_TGID);
821	if (task && task->self_exec_id ==
822	info->notify_self_exec_id) {
823	do_send_sig_info(sig: info->notify.sigev_signo,
824	info: &sig_i, p: task, type: PIDTYPE_TGID);
825	}
826	rcu_read_unlock();
827	break;
828	}
829	case SIGEV_THREAD:
830	set_cookie(skb: info->notify_cookie, NOTIFY_WOKENUP);
831	netlink_sendskb(sk: info->notify_sock, skb: info->notify_cookie);
832	break;
833	}
834	/* after notification unregisters process */
835	put_pid(pid: info->notify_owner);
836	put_user_ns(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
843	static 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
853	static 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(skb: info->notify_cookie, NOTIFY_REMOVED);
858	netlink_sendskb(sk: info->notify_sock, skb: info->notify_cookie);
859	}
860	put_pid(pid: info->notify_owner);
861	put_user_ns(ns: info->notify_user_ns);
862	info->notify_owner = NULL;
863	info->notify_user_ns = NULL;
864	}
865
866	static 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: dentry->d_parent);
880	return vfs_mkobj(dentry, mode & ~current_umask(),
881	f: mqueue_create_attr, attr);
882	}
883	/* it already existed */
884	audit_inode(name, dentry, aflags: 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(&nop_mnt_idmap, d_inode(dentry), acc);
891	}
892
893	static 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(ptr: name = getname(u_name)))
906	return PTR_ERR(ptr: 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(inode: d_inode(dentry: root));
914	path.dentry = lookup_one_len(name->name, root, strlen(name->name));
915	if (IS_ERR(ptr: path.dentry)) {
916	error = PTR_ERR(ptr: path.dentry);
917	goto out_putfd;
918	}
919	path.mnt = mntget(mnt);
920	error = prepare_open(dentry: path.dentry, oflag, ro, mode, name, attr);
921	if (!error) {
922	struct file *file = dentry_open(&path, oflag, current_cred());
923	if (!IS_ERR(ptr: file))
924	fd_install(fd, file);
925	else
926	error = PTR_ERR(ptr: file);
927	}
928	path_put(&path);
929	out_putfd:
930	if (error) {
931	put_unused_fd(fd);
932	fd = error;
933	}
934	inode_unlock(inode: d_inode(dentry: root));
935	if (!ro)
936	mnt_drop_write(mnt);
937	out_putname:
938	putname(name);
939	return fd;
940	}
941
942	SYSCALL_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, attr: u_attr ? &attr : NULL);
950	}
951
952	SYSCALL_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(ptr: name))
963	return PTR_ERR(ptr: name);
964
965	audit_inode_parent_hidden(name, dentry: mnt->mnt_root);
966	err = mnt_want_write(mnt);
967	if (err)
968	goto out_name;
969	inode_lock_nested(inode: d_inode(dentry: mnt->mnt_root), subclass: I_MUTEX_PARENT);
970	dentry = lookup_one_len(name->name, mnt->mnt_root,
971	strlen(name->name));
972	if (IS_ERR(ptr: dentry)) {
973	err = PTR_ERR(ptr: 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(&nop_mnt_idmap, d_inode(dentry: dentry->d_parent),
983	dentry, NULL);
984	}
985	dput(dentry);
986
987	out_unlock:
988	inode_unlock(inode: d_inode(dentry: mnt->mnt_root));
989	iput(inode);
990	mnt_drop_write(mnt);
991	out_name:
992	putname(name);
993
994	return err;
995	}
996
997	/* Pipelined send and receive functions.
998	*
999	* If a receiver finds no waiting message, then it registers itself in the
1000	* list of waiting receivers. A sender checks that list before adding the new
1001	* message into the message array. If there is a waiting receiver, then it
1002	* bypasses the message array and directly hands the message over to the
1003	* receiver. The receiver accepts the message and returns without grabbing the
1004	* queue spinlock:
1005	*
1006	* - Set pointer to message.
1007	* - Queue the receiver task for later wakeup (without the info->lock).
1008	* - Update its state to STATE_READY. Now the receiver can continue.
1009	* - Wake up the process after the lock is dropped. Should the process wake up
1010	* before this wakeup (due to a timeout or a signal) it will either see
1011	* STATE_READY and continue or acquire the lock to check the state again.
1012	*
1013	* The same algorithm is used for senders.
1014	*/
1015
1016	static inline void __pipelined_op(struct wake_q_head *wake_q,
1017	struct mqueue_inode_info *info,
1018	struct ext_wait_queue *this)
1019	{
1020	struct task_struct *task;
1021
1022	list_del(entry: &this->list);
1023	task = get_task_struct(t: this->task);
1024
1025	/* see MQ_BARRIER for purpose/pairing */
1026	smp_store_release(&this->state, STATE_READY);
1027	wake_q_add_safe(head: wake_q, task);
1028	}
1029
1030	/* pipelined_send() - send a message directly to the task waiting in
1031	* sys_mq_timedreceive() (without inserting message into a queue).
1032	*/
1033	static inline void pipelined_send(struct wake_q_head *wake_q,
1034	struct mqueue_inode_info *info,
1035	struct msg_msg *message,
1036	struct ext_wait_queue *receiver)
1037	{
1038	receiver->msg = message;
1039	__pipelined_op(wake_q, info, this: receiver);
1040	}
1041
1042	/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
1043	* gets its message and put to the queue (we have one free place for sure). */
1044	static inline void pipelined_receive(struct wake_q_head *wake_q,
1045	struct mqueue_inode_info *info)
1046	{
1047	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
1048
1049	if (!sender) {
1050	/* for poll */
1051	wake_up_interruptible(&info->wait_q);
1052	return;
1053	}
1054	if (msg_insert(msg: sender->msg, info))
1055	return;
1056
1057	__pipelined_op(wake_q, info, this: sender);
1058	}
1059
1060	static int do_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
1061	size_t msg_len, unsigned int msg_prio,
1062	struct timespec64 *ts)
1063	{
1064	struct fd f;
1065	struct inode *inode;
1066	struct ext_wait_queue wait;
1067	struct ext_wait_queue *receiver;
1068	struct msg_msg *msg_ptr;
1069	struct mqueue_inode_info *info;
1070	ktime_t expires, *timeout = NULL;
1071	struct posix_msg_tree_node *new_leaf = NULL;
1072	int ret = 0;
1073	DEFINE_WAKE_Q(wake_q);
1074
1075	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
1076	return -EINVAL;
1077
1078	if (ts) {
1079	expires = timespec64_to_ktime(ts: *ts);
1080	timeout = &expires;
1081	}
1082
1083	audit_mq_sendrecv(mqdes, msg_len, msg_prio, abs_timeout: ts);
1084
1085	f = fdget(fd: mqdes);
1086	if (unlikely(!f.file)) {
1087	ret = -EBADF;
1088	goto out;
1089	}
1090
1091	inode = file_inode(f: f.file);
1092	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1093	ret = -EBADF;
1094	goto out_fput;
1095	}
1096	info = MQUEUE_I(inode);
1097	audit_file(file: f.file);
1098
1099	if (unlikely(!(f.file->f_mode & FMODE_WRITE))) {
1100	ret = -EBADF;
1101	goto out_fput;
1102	}
1103
1104	if (unlikely(msg_len > info->attr.mq_msgsize)) {
1105	ret = -EMSGSIZE;
1106	goto out_fput;
1107	}
1108
1109	/* First try to allocate memory, before doing anything with
1110	* existing queues. */
1111	msg_ptr = load_msg(src: u_msg_ptr, len: msg_len);
1112	if (IS_ERR(ptr: msg_ptr)) {
1113	ret = PTR_ERR(ptr: msg_ptr);
1114	goto out_fput;
1115	}
1116	msg_ptr->m_ts = msg_len;
1117	msg_ptr->m_type = msg_prio;
1118
1119	/*
1120	* msg_insert really wants us to have a valid, spare node struct so
1121	* it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1122	* fall back to that if necessary.
1123	*/
1124	if (!info->node_cache)
1125	new_leaf = kmalloc(size: sizeof(*new_leaf), GFP_KERNEL);
1126
1127	spin_lock(lock: &info->lock);
1128
1129	if (!info->node_cache && new_leaf) {
1130	/* Save our speculative allocation into the cache */
1131	INIT_LIST_HEAD(list: &new_leaf->msg_list);
1132	info->node_cache = new_leaf;
1133	new_leaf = NULL;
1134	} else {
1135	kfree(objp: new_leaf);
1136	}
1137
1138	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
1139	if (f.file->f_flags & O_NONBLOCK) {
1140	ret = -EAGAIN;
1141	} else {
1142	wait.task = current;
1143	wait.msg = (void *) msg_ptr;
1144
1145	/* memory barrier not required, we hold info->lock */
1146	WRITE_ONCE(wait.state, STATE_NONE);
1147	ret = wq_sleep(info, SEND, timeout, ewp: &wait);
1148	/*
1149	* wq_sleep must be called with info->lock held, and
1150	* returns with the lock released
1151	*/
1152	goto out_free;
1153	}
1154	} else {
1155	receiver = wq_get_first_waiter(info, RECV);
1156	if (receiver) {
1157	pipelined_send(wake_q: &wake_q, info, message: msg_ptr, receiver);
1158	} else {
1159	/* adds message to the queue */
1160	ret = msg_insert(msg: msg_ptr, info);
1161	if (ret)
1162	goto out_unlock;
1163	__do_notify(info);
1164	}
1165	inode->i_atime = inode->i_mtime = inode->i_ctime =
1166	current_time(inode);
1167	}
1168	out_unlock:
1169	spin_unlock(lock: &info->lock);
1170	wake_up_q(head: &wake_q);
1171	out_free:
1172	if (ret)
1173	free_msg(msg: msg_ptr);
1174	out_fput:
1175	fdput(fd: f);
1176	out:
1177	return ret;
1178	}
1179
1180	static int do_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
1181	size_t msg_len, unsigned int __user *u_msg_prio,
1182	struct timespec64 *ts)
1183	{
1184	ssize_t ret;
1185	struct msg_msg *msg_ptr;
1186	struct fd f;
1187	struct inode *inode;
1188	struct mqueue_inode_info *info;
1189	struct ext_wait_queue wait;
1190	ktime_t expires, *timeout = NULL;
1191	struct posix_msg_tree_node *new_leaf = NULL;
1192
1193	if (ts) {
1194	expires = timespec64_to_ktime(ts: *ts);
1195	timeout = &expires;
1196	}
1197
1198	audit_mq_sendrecv(mqdes, msg_len, msg_prio: 0, abs_timeout: ts);
1199
1200	f = fdget(fd: mqdes);
1201	if (unlikely(!f.file)) {
1202	ret = -EBADF;
1203	goto out;
1204	}
1205
1206	inode = file_inode(f: f.file);
1207	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1208	ret = -EBADF;
1209	goto out_fput;
1210	}
1211	info = MQUEUE_I(inode);
1212	audit_file(file: f.file);
1213
1214	if (unlikely(!(f.file->f_mode & FMODE_READ))) {
1215	ret = -EBADF;
1216	goto out_fput;
1217	}
1218
1219	/* checks if buffer is big enough */
1220	if (unlikely(msg_len < info->attr.mq_msgsize)) {
1221	ret = -EMSGSIZE;
1222	goto out_fput;
1223	}
1224
1225	/*
1226	* msg_insert really wants us to have a valid, spare node struct so
1227	* it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1228	* fall back to that if necessary.
1229	*/
1230	if (!info->node_cache)
1231	new_leaf = kmalloc(size: sizeof(*new_leaf), GFP_KERNEL);
1232
1233	spin_lock(lock: &info->lock);
1234
1235	if (!info->node_cache && new_leaf) {
1236	/* Save our speculative allocation into the cache */
1237	INIT_LIST_HEAD(list: &new_leaf->msg_list);
1238	info->node_cache = new_leaf;
1239	} else {
1240	kfree(objp: new_leaf);
1241	}
1242
1243	if (info->attr.mq_curmsgs == 0) {
1244	if (f.file->f_flags & O_NONBLOCK) {
1245	spin_unlock(lock: &info->lock);
1246	ret = -EAGAIN;
1247	} else {
1248	wait.task = current;
1249
1250	/* memory barrier not required, we hold info->lock */
1251	WRITE_ONCE(wait.state, STATE_NONE);
1252	ret = wq_sleep(info, RECV, timeout, ewp: &wait);
1253	msg_ptr = wait.msg;
1254	}
1255	} else {
1256	DEFINE_WAKE_Q(wake_q);
1257
1258	msg_ptr = msg_get(info);
1259
1260	inode->i_atime = inode->i_mtime = inode->i_ctime =
1261	current_time(inode);
1262
1263	/* There is now free space in queue. */
1264	pipelined_receive(wake_q: &wake_q, info);
1265	spin_unlock(lock: &info->lock);
1266	wake_up_q(head: &wake_q);
1267	ret = 0;
1268	}
1269	if (ret == 0) {
1270	ret = msg_ptr->m_ts;
1271
1272	if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1273	store_msg(dest: u_msg_ptr, msg: msg_ptr, len: msg_ptr->m_ts)) {
1274	ret = -EFAULT;
1275	}
1276	free_msg(msg: msg_ptr);
1277	}
1278	out_fput:
1279	fdput(fd: f);
1280	out:
1281	return ret;
1282	}
1283
1284	SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
1285	size_t, msg_len, unsigned int, msg_prio,
1286	const struct __kernel_timespec __user *, u_abs_timeout)
1287	{
1288	struct timespec64 ts, *p = NULL;
1289	if (u_abs_timeout) {
1290	int res = prepare_timeout(u_abs_timeout, ts: &ts);
1291	if (res)
1292	return res;
1293	p = &ts;
1294	}
1295	return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, ts: p);
1296	}
1297
1298	SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
1299	size_t, msg_len, unsigned int __user *, u_msg_prio,
1300	const struct __kernel_timespec __user *, u_abs_timeout)
1301	{
1302	struct timespec64 ts, *p = NULL;
1303	if (u_abs_timeout) {
1304	int res = prepare_timeout(u_abs_timeout, ts: &ts);
1305	if (res)
1306	return res;
1307	p = &ts;
1308	}
1309	return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, ts: p);
1310	}
1311
1312	/*
1313	* Notes: the case when user wants us to deregister (with NULL as pointer)
1314	* and he isn't currently owner of notification, will be silently discarded.
1315	* It isn't explicitly defined in the POSIX.
1316	*/
1317	static int do_mq_notify(mqd_t mqdes, const struct sigevent *notification)
1318	{
1319	int ret;
1320	struct fd f;
1321	struct sock *sock;
1322	struct inode *inode;
1323	struct mqueue_inode_info *info;
1324	struct sk_buff *nc;
1325
1326	audit_mq_notify(mqdes, notification);
1327
1328	nc = NULL;
1329	sock = NULL;
1330	if (notification != NULL) {
1331	if (unlikely(notification->sigev_notify != SIGEV_NONE &&
1332	notification->sigev_notify != SIGEV_SIGNAL &&
1333	notification->sigev_notify != SIGEV_THREAD))
1334	return -EINVAL;
1335	if (notification->sigev_notify == SIGEV_SIGNAL &&
1336	!valid_signal(sig: notification->sigev_signo)) {
1337	return -EINVAL;
1338	}
1339	if (notification->sigev_notify == SIGEV_THREAD) {
1340	long timeo;
1341
1342	/* create the notify skb */
1343	nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1344	if (!nc)
1345	return -ENOMEM;
1346
1347	if (copy_from_user(to: nc->data,
1348	from: notification->sigev_value.sival_ptr,
1349	NOTIFY_COOKIE_LEN)) {
1350	ret = -EFAULT;
1351	goto free_skb;
1352	}
1353
1354	/* TODO: add a header? */
1355	skb_put(skb: nc, NOTIFY_COOKIE_LEN);
1356	/* and attach it to the socket */
1357	retry:
1358	f = fdget(fd: notification->sigev_signo);
1359	if (!f.file) {
1360	ret = -EBADF;
1361	goto out;
1362	}
1363	sock = netlink_getsockbyfilp(filp: f.file);
1364	fdput(fd: f);
1365	if (IS_ERR(ptr: sock)) {
1366	ret = PTR_ERR(ptr: sock);
1367	goto free_skb;
1368	}
1369
1370	timeo = MAX_SCHEDULE_TIMEOUT;
1371	ret = netlink_attachskb(sk: sock, skb: nc, timeo: &timeo, NULL);
1372	if (ret == 1) {
1373	sock = NULL;
1374	goto retry;
1375	}
1376	if (ret)
1377	return ret;
1378	}
1379	}
1380
1381	f = fdget(fd: mqdes);
1382	if (!f.file) {
1383	ret = -EBADF;
1384	goto out;
1385	}
1386
1387	inode = file_inode(f: f.file);
1388	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1389	ret = -EBADF;
1390	goto out_fput;
1391	}
1392	info = MQUEUE_I(inode);
1393
1394	ret = 0;
1395	spin_lock(lock: &info->lock);
1396	if (notification == NULL) {
1397	if (info->notify_owner == task_tgid(current)) {
1398	remove_notification(info);
1399	inode->i_atime = inode->i_ctime = current_time(inode);
1400	}
1401	} else if (info->notify_owner != NULL) {
1402	ret = -EBUSY;
1403	} else {
1404	switch (notification->sigev_notify) {
1405	case SIGEV_NONE:
1406	info->notify.sigev_notify = SIGEV_NONE;
1407	break;
1408	case SIGEV_THREAD:
1409	info->notify_sock = sock;
1410	info->notify_cookie = nc;
1411	sock = NULL;
1412	nc = NULL;
1413	info->notify.sigev_notify = SIGEV_THREAD;
1414	break;
1415	case SIGEV_SIGNAL:
1416	info->notify.sigev_signo = notification->sigev_signo;
1417	info->notify.sigev_value = notification->sigev_value;
1418	info->notify.sigev_notify = SIGEV_SIGNAL;
1419	info->notify_self_exec_id = current->self_exec_id;
1420	break;
1421	}
1422
1423	info->notify_owner = get_pid(pid: task_tgid(current));
1424	info->notify_user_ns = get_user_ns(ns: current_user_ns());
1425	inode->i_atime = inode->i_ctime = current_time(inode);
1426	}
1427	spin_unlock(lock: &info->lock);
1428	out_fput:
1429	fdput(fd: f);
1430	out:
1431	if (sock)
1432	netlink_detachskb(sk: sock, skb: nc);
1433	else
1434	free_skb:
1435	dev_kfree_skb(nc);
1436
1437	return ret;
1438	}
1439
1440	SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1441	const struct sigevent __user *, u_notification)
1442	{
1443	struct sigevent n, *p = NULL;
1444	if (u_notification) {
1445	if (copy_from_user(&n, u_notification, sizeof(struct sigevent)))
1446	return -EFAULT;
1447	p = &n;
1448	}
1449	return do_mq_notify(mqdes, notification: p);
1450	}
1451
1452	static int do_mq_getsetattr(int mqdes, struct mq_attr *new, struct mq_attr *old)
1453	{
1454	struct fd f;
1455	struct inode *inode;
1456	struct mqueue_inode_info *info;
1457
1458	if (new && (new->mq_flags & (~O_NONBLOCK)))
1459	return -EINVAL;
1460
1461	f = fdget(fd: mqdes);
1462	if (!f.file)
1463	return -EBADF;
1464
1465	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1466	fdput(fd: f);
1467	return -EBADF;
1468	}
1469
1470	inode = file_inode(f: f.file);
1471	info = MQUEUE_I(inode);
1472
1473	spin_lock(lock: &info->lock);
1474
1475	if (old) {
1476	*old = info->attr;
1477	old->mq_flags = f.file->f_flags & O_NONBLOCK;
1478	}
1479	if (new) {
1480	audit_mq_getsetattr(mqdes, mqstat: new);
1481	spin_lock(lock: &f.file->f_lock);
1482	if (new->mq_flags & O_NONBLOCK)
1483	f.file->f_flags |= O_NONBLOCK;
1484	else
1485	f.file->f_flags &= ~O_NONBLOCK;
1486	spin_unlock(lock: &f.file->f_lock);
1487
1488	inode->i_atime = inode->i_ctime = current_time(inode);
1489	}
1490
1491	spin_unlock(lock: &info->lock);
1492	fdput(fd: f);
1493	return 0;
1494	}
1495
1496	SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1497	const struct mq_attr __user *, u_mqstat,
1498	struct mq_attr __user *, u_omqstat)
1499	{
1500	int ret;
1501	struct mq_attr mqstat, omqstat;
1502	struct mq_attr *new = NULL, *old = NULL;
1503
1504	if (u_mqstat) {
1505	new = &mqstat;
1506	if (copy_from_user(new, u_mqstat, sizeof(struct mq_attr)))
1507	return -EFAULT;
1508	}
1509	if (u_omqstat)
1510	old = &omqstat;
1511
1512	ret = do_mq_getsetattr(mqdes, new, old);
1513	if (ret || !old)
1514	return ret;
1515
1516	if (copy_to_user(u_omqstat, old, sizeof(struct mq_attr)))
1517	return -EFAULT;
1518	return 0;
1519	}
1520
1521	#ifdef CONFIG_COMPAT
1522
1523	struct compat_mq_attr {
1524	compat_long_t mq_flags; /* message queue flags */
1525	compat_long_t mq_maxmsg; /* maximum number of messages */
1526	compat_long_t mq_msgsize; /* maximum message size */
1527	compat_long_t mq_curmsgs; /* number of messages currently queued */
1528	compat_long_t __reserved[4]; /* ignored for input, zeroed for output */
1529	};
1530
1531	static inline int get_compat_mq_attr(struct mq_attr *attr,
1532	const struct compat_mq_attr __user *uattr)
1533	{
1534	struct compat_mq_attr v;
1535
1536	if (copy_from_user(&v, uattr, sizeof(*uattr)))
1537	return -EFAULT;
1538
1539	memset(attr, 0, sizeof(*attr));
1540	attr->mq_flags = v.mq_flags;
1541	attr->mq_maxmsg = v.mq_maxmsg;
1542	attr->mq_msgsize = v.mq_msgsize;
1543	attr->mq_curmsgs = v.mq_curmsgs;
1544	return 0;
1545	}
1546
1547	static inline int put_compat_mq_attr(const struct mq_attr *attr,
1548	struct compat_mq_attr __user *uattr)
1549	{
1550	struct compat_mq_attr v;
1551
1552	memset(&v, 0, sizeof(v));
1553	v.mq_flags = attr->mq_flags;
1554	v.mq_maxmsg = attr->mq_maxmsg;
1555	v.mq_msgsize = attr->mq_msgsize;
1556	v.mq_curmsgs = attr->mq_curmsgs;
1557	if (copy_to_user(uattr, &v, sizeof(*uattr)))
1558	return -EFAULT;
1559	return 0;
1560	}
1561
1562	COMPAT_SYSCALL_DEFINE4(mq_open, const char __user *, u_name,
1563	int, oflag, compat_mode_t, mode,
1564	struct compat_mq_attr __user *, u_attr)
1565	{
1566	struct mq_attr attr, *p = NULL;
1567	if (u_attr && oflag & O_CREAT) {
1568	p = &attr;
1569	if (get_compat_mq_attr(&attr, u_attr))
1570	return -EFAULT;
1571	}
1572	return do_mq_open(u_name, oflag, mode, p);
1573	}
1574
1575	COMPAT_SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1576	const struct compat_sigevent __user *, u_notification)
1577	{
1578	struct sigevent n, *p = NULL;
1579	if (u_notification) {
1580	if (get_compat_sigevent(&n, u_notification))
1581	return -EFAULT;
1582	if (n.sigev_notify == SIGEV_THREAD)
1583	n.sigev_value.sival_ptr = compat_ptr(n.sigev_value.sival_int);
1584	p = &n;
1585	}
1586	return do_mq_notify(mqdes, p);
1587	}
1588
1589	COMPAT_SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1590	const struct compat_mq_attr __user *, u_mqstat,
1591	struct compat_mq_attr __user *, u_omqstat)
1592	{
1593	int ret;
1594	struct mq_attr mqstat, omqstat;
1595	struct mq_attr *new = NULL, *old = NULL;
1596
1597	if (u_mqstat) {
1598	new = &mqstat;
1599	if (get_compat_mq_attr(new, u_mqstat))
1600	return -EFAULT;
1601	}
1602	if (u_omqstat)
1603	old = &omqstat;
1604
1605	ret = do_mq_getsetattr(mqdes, new, old);
1606	if (ret || !old)
1607	return ret;
1608
1609	if (put_compat_mq_attr(old, u_omqstat))
1610	return -EFAULT;
1611	return 0;
1612	}
1613	#endif
1614
1615	#ifdef CONFIG_COMPAT_32BIT_TIME
1616	static int compat_prepare_timeout(const struct old_timespec32 __user *p,
1617	struct timespec64 *ts)
1618	{
1619	if (get_old_timespec32(ts, p))
1620	return -EFAULT;
1621	if (!timespec64_valid(ts))
1622	return -EINVAL;
1623	return 0;
1624	}
1625
1626	SYSCALL_DEFINE5(mq_timedsend_time32, mqd_t, mqdes,
1627	const char __user *, u_msg_ptr,
1628	unsigned int, msg_len, unsigned int, msg_prio,
1629	const struct old_timespec32 __user *, u_abs_timeout)
1630	{
1631	struct timespec64 ts, *p = NULL;
1632	if (u_abs_timeout) {
1633	int res = compat_prepare_timeout(u_abs_timeout, &ts);
1634	if (res)
1635	return res;
1636	p = &ts;
1637	}
1638	return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p);
1639	}
1640
1641	SYSCALL_DEFINE5(mq_timedreceive_time32, mqd_t, mqdes,
1642	char __user *, u_msg_ptr,
1643	unsigned int, msg_len, unsigned int __user *, u_msg_prio,
1644	const struct old_timespec32 __user *, u_abs_timeout)
1645	{
1646	struct timespec64 ts, *p = NULL;
1647	if (u_abs_timeout) {
1648	int res = compat_prepare_timeout(u_abs_timeout, &ts);
1649	if (res)
1650	return res;
1651	p = &ts;
1652	}
1653	return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p);
1654	}
1655	#endif
1656
1657	static const struct inode_operations mqueue_dir_inode_operations = {
1658	.lookup = simple_lookup,
1659	.create = mqueue_create,
1660	.unlink = mqueue_unlink,
1661	};
1662
1663	static const struct file_operations mqueue_file_operations = {
1664	.flush = mqueue_flush_file,
1665	.poll = mqueue_poll_file,
1666	.read = mqueue_read_file,
1667	.llseek = default_llseek,
1668	};
1669
1670	static const struct super_operations mqueue_super_ops = {
1671	.alloc_inode = mqueue_alloc_inode,
1672	.free_inode = mqueue_free_inode,
1673	.evict_inode = mqueue_evict_inode,
1674	.statfs = simple_statfs,
1675	};
1676
1677	static const struct fs_context_operations mqueue_fs_context_ops = {
1678	.free = mqueue_fs_context_free,
1679	.get_tree = mqueue_get_tree,
1680	};
1681
1682	static struct file_system_type mqueue_fs_type = {
1683	.name = "mqueue",
1684	.init_fs_context = mqueue_init_fs_context,
1685	.kill_sb = kill_litter_super,
1686	.fs_flags = FS_USERNS_MOUNT,
1687	};
1688
1689	int mq_init_ns(struct ipc_namespace *ns)
1690	{
1691	struct vfsmount *m;
1692
1693	ns->mq_queues_count = 0;
1694	ns->mq_queues_max = DFLT_QUEUESMAX;
1695	ns->mq_msg_max = DFLT_MSGMAX;
1696	ns->mq_msgsize_max = DFLT_MSGSIZEMAX;
1697	ns->mq_msg_default = DFLT_MSG;
1698	ns->mq_msgsize_default = DFLT_MSGSIZE;
1699
1700	m = mq_create_mount(ns);
1701	if (IS_ERR(ptr: m))
1702	return PTR_ERR(ptr: m);
1703	ns->mq_mnt = m;
1704	return 0;
1705	}
1706
1707	void mq_clear_sbinfo(struct ipc_namespace *ns)
1708	{
1709	ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1710	}
1711
1712	static int __init init_mqueue_fs(void)
1713	{
1714	int error;
1715
1716	mqueue_inode_cachep = kmem_cache_create(name: "mqueue_inode_cache",
1717	size: sizeof(struct mqueue_inode_info), align: 0,
1718	SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT, ctor: init_once);
1719	if (mqueue_inode_cachep == NULL)
1720	return -ENOMEM;
1721
1722	if (!setup_mq_sysctls(&init_ipc_ns)) {
1723	pr_warn("sysctl registration failed\n");
1724	error = -ENOMEM;
1725	goto out_kmem;
1726	}
1727
1728	error = register_filesystem(&mqueue_fs_type);
1729	if (error)
1730	goto out_sysctl;
1731
1732	spin_lock_init(&mq_lock);
1733
1734	error = mq_init_ns(&init_ipc_ns);
1735	if (error)
1736	goto out_filesystem;
1737
1738	return 0;
1739
1740	out_filesystem:
1741	unregister_filesystem(&mqueue_fs_type);
1742	out_sysctl:
1743	retire_mq_sysctls(ns: &init_ipc_ns);
1744	out_kmem:
1745	kmem_cache_destroy(s: mqueue_inode_cachep);
1746	return error;
1747	}
1748
1749	device_initcall(init_mqueue_fs);
1750